1 //===--- ExprConstant.cpp - Expression Constant Evaluator -----------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements the Expr constant evaluator. 10 // 11 // Constant expression evaluation produces four main results: 12 // 13 // * A success/failure flag indicating whether constant folding was successful. 14 // This is the 'bool' return value used by most of the code in this file. A 15 // 'false' return value indicates that constant folding has failed, and any 16 // appropriate diagnostic has already been produced. 17 // 18 // * An evaluated result, valid only if constant folding has not failed. 19 // 20 // * A flag indicating if evaluation encountered (unevaluated) side-effects. 21 // These arise in cases such as (sideEffect(), 0) and (sideEffect() || 1), 22 // where it is possible to determine the evaluated result regardless. 23 // 24 // * A set of notes indicating why the evaluation was not a constant expression 25 // (under the C++11 / C++1y rules only, at the moment), or, if folding failed 26 // too, why the expression could not be folded. 27 // 28 // If we are checking for a potential constant expression, failure to constant 29 // fold a potential constant sub-expression will be indicated by a 'false' 30 // return value (the expression could not be folded) and no diagnostic (the 31 // expression is not necessarily non-constant). 32 // 33 //===----------------------------------------------------------------------===// 34 35 #include "Interp/Context.h" 36 #include "Interp/Frame.h" 37 #include "Interp/State.h" 38 #include "clang/AST/APValue.h" 39 #include "clang/AST/ASTContext.h" 40 #include "clang/AST/ASTDiagnostic.h" 41 #include "clang/AST/ASTLambda.h" 42 #include "clang/AST/Attr.h" 43 #include "clang/AST/CXXInheritance.h" 44 #include "clang/AST/CharUnits.h" 45 #include "clang/AST/CurrentSourceLocExprScope.h" 46 #include "clang/AST/Expr.h" 47 #include "clang/AST/OSLog.h" 48 #include "clang/AST/OptionalDiagnostic.h" 49 #include "clang/AST/RecordLayout.h" 50 #include "clang/AST/StmtVisitor.h" 51 #include "clang/AST/TypeLoc.h" 52 #include "clang/Basic/Builtins.h" 53 #include "clang/Basic/TargetInfo.h" 54 #include "llvm/ADT/APFixedPoint.h" 55 #include "llvm/ADT/Optional.h" 56 #include "llvm/ADT/SmallBitVector.h" 57 #include "llvm/Support/Debug.h" 58 #include "llvm/Support/SaveAndRestore.h" 59 #include "llvm/Support/raw_ostream.h" 60 #include <cstring> 61 #include <functional> 62 63 #define DEBUG_TYPE "exprconstant" 64 65 using namespace clang; 66 using llvm::APFixedPoint; 67 using llvm::APInt; 68 using llvm::APSInt; 69 using llvm::APFloat; 70 using llvm::FixedPointSemantics; 71 using llvm::Optional; 72 73 namespace { 74 struct LValue; 75 class CallStackFrame; 76 class EvalInfo; 77 78 using SourceLocExprScopeGuard = 79 CurrentSourceLocExprScope::SourceLocExprScopeGuard; 80 81 static QualType getType(APValue::LValueBase B) { 82 return B.getType(); 83 } 84 85 /// Get an LValue path entry, which is known to not be an array index, as a 86 /// field declaration. 87 static const FieldDecl *getAsField(APValue::LValuePathEntry E) { 88 return dyn_cast_or_null<FieldDecl>(E.getAsBaseOrMember().getPointer()); 89 } 90 /// Get an LValue path entry, which is known to not be an array index, as a 91 /// base class declaration. 92 static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) { 93 return dyn_cast_or_null<CXXRecordDecl>(E.getAsBaseOrMember().getPointer()); 94 } 95 /// Determine whether this LValue path entry for a base class names a virtual 96 /// base class. 97 static bool isVirtualBaseClass(APValue::LValuePathEntry E) { 98 return E.getAsBaseOrMember().getInt(); 99 } 100 101 /// Given an expression, determine the type used to store the result of 102 /// evaluating that expression. 103 static QualType getStorageType(const ASTContext &Ctx, const Expr *E) { 104 if (E->isPRValue()) 105 return E->getType(); 106 return Ctx.getLValueReferenceType(E->getType()); 107 } 108 109 /// Given a CallExpr, try to get the alloc_size attribute. May return null. 110 static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) { 111 if (const FunctionDecl *DirectCallee = CE->getDirectCallee()) 112 return DirectCallee->getAttr<AllocSizeAttr>(); 113 if (const Decl *IndirectCallee = CE->getCalleeDecl()) 114 return IndirectCallee->getAttr<AllocSizeAttr>(); 115 return nullptr; 116 } 117 118 /// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr. 119 /// This will look through a single cast. 120 /// 121 /// Returns null if we couldn't unwrap a function with alloc_size. 122 static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) { 123 if (!E->getType()->isPointerType()) 124 return nullptr; 125 126 E = E->IgnoreParens(); 127 // If we're doing a variable assignment from e.g. malloc(N), there will 128 // probably be a cast of some kind. In exotic cases, we might also see a 129 // top-level ExprWithCleanups. Ignore them either way. 130 if (const auto *FE = dyn_cast<FullExpr>(E)) 131 E = FE->getSubExpr()->IgnoreParens(); 132 133 if (const auto *Cast = dyn_cast<CastExpr>(E)) 134 E = Cast->getSubExpr()->IgnoreParens(); 135 136 if (const auto *CE = dyn_cast<CallExpr>(E)) 137 return getAllocSizeAttr(CE) ? CE : nullptr; 138 return nullptr; 139 } 140 141 /// Determines whether or not the given Base contains a call to a function 142 /// with the alloc_size attribute. 143 static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) { 144 const auto *E = Base.dyn_cast<const Expr *>(); 145 return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E); 146 } 147 148 /// Determines whether the given kind of constant expression is only ever 149 /// used for name mangling. If so, it's permitted to reference things that we 150 /// can't generate code for (in particular, dllimported functions). 151 static bool isForManglingOnly(ConstantExprKind Kind) { 152 switch (Kind) { 153 case ConstantExprKind::Normal: 154 case ConstantExprKind::ClassTemplateArgument: 155 case ConstantExprKind::ImmediateInvocation: 156 // Note that non-type template arguments of class type are emitted as 157 // template parameter objects. 158 return false; 159 160 case ConstantExprKind::NonClassTemplateArgument: 161 return true; 162 } 163 llvm_unreachable("unknown ConstantExprKind"); 164 } 165 166 static bool isTemplateArgument(ConstantExprKind Kind) { 167 switch (Kind) { 168 case ConstantExprKind::Normal: 169 case ConstantExprKind::ImmediateInvocation: 170 return false; 171 172 case ConstantExprKind::ClassTemplateArgument: 173 case ConstantExprKind::NonClassTemplateArgument: 174 return true; 175 } 176 llvm_unreachable("unknown ConstantExprKind"); 177 } 178 179 /// The bound to claim that an array of unknown bound has. 180 /// The value in MostDerivedArraySize is undefined in this case. So, set it 181 /// to an arbitrary value that's likely to loudly break things if it's used. 182 static const uint64_t AssumedSizeForUnsizedArray = 183 std::numeric_limits<uint64_t>::max() / 2; 184 185 /// Determines if an LValue with the given LValueBase will have an unsized 186 /// array in its designator. 187 /// Find the path length and type of the most-derived subobject in the given 188 /// path, and find the size of the containing array, if any. 189 static unsigned 190 findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base, 191 ArrayRef<APValue::LValuePathEntry> Path, 192 uint64_t &ArraySize, QualType &Type, bool &IsArray, 193 bool &FirstEntryIsUnsizedArray) { 194 // This only accepts LValueBases from APValues, and APValues don't support 195 // arrays that lack size info. 196 assert(!isBaseAnAllocSizeCall(Base) && 197 "Unsized arrays shouldn't appear here"); 198 unsigned MostDerivedLength = 0; 199 Type = getType(Base); 200 201 for (unsigned I = 0, N = Path.size(); I != N; ++I) { 202 if (Type->isArrayType()) { 203 const ArrayType *AT = Ctx.getAsArrayType(Type); 204 Type = AT->getElementType(); 205 MostDerivedLength = I + 1; 206 IsArray = true; 207 208 if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) { 209 ArraySize = CAT->getSize().getZExtValue(); 210 } else { 211 assert(I == 0 && "unexpected unsized array designator"); 212 FirstEntryIsUnsizedArray = true; 213 ArraySize = AssumedSizeForUnsizedArray; 214 } 215 } else if (Type->isAnyComplexType()) { 216 const ComplexType *CT = Type->castAs<ComplexType>(); 217 Type = CT->getElementType(); 218 ArraySize = 2; 219 MostDerivedLength = I + 1; 220 IsArray = true; 221 } else if (const FieldDecl *FD = getAsField(Path[I])) { 222 Type = FD->getType(); 223 ArraySize = 0; 224 MostDerivedLength = I + 1; 225 IsArray = false; 226 } else { 227 // Path[I] describes a base class. 228 ArraySize = 0; 229 IsArray = false; 230 } 231 } 232 return MostDerivedLength; 233 } 234 235 /// A path from a glvalue to a subobject of that glvalue. 236 struct SubobjectDesignator { 237 /// True if the subobject was named in a manner not supported by C++11. Such 238 /// lvalues can still be folded, but they are not core constant expressions 239 /// and we cannot perform lvalue-to-rvalue conversions on them. 240 unsigned Invalid : 1; 241 242 /// Is this a pointer one past the end of an object? 243 unsigned IsOnePastTheEnd : 1; 244 245 /// Indicator of whether the first entry is an unsized array. 246 unsigned FirstEntryIsAnUnsizedArray : 1; 247 248 /// Indicator of whether the most-derived object is an array element. 249 unsigned MostDerivedIsArrayElement : 1; 250 251 /// The length of the path to the most-derived object of which this is a 252 /// subobject. 253 unsigned MostDerivedPathLength : 28; 254 255 /// The size of the array of which the most-derived object is an element. 256 /// This will always be 0 if the most-derived object is not an array 257 /// element. 0 is not an indicator of whether or not the most-derived object 258 /// is an array, however, because 0-length arrays are allowed. 259 /// 260 /// If the current array is an unsized array, the value of this is 261 /// undefined. 262 uint64_t MostDerivedArraySize; 263 264 /// The type of the most derived object referred to by this address. 265 QualType MostDerivedType; 266 267 typedef APValue::LValuePathEntry PathEntry; 268 269 /// The entries on the path from the glvalue to the designated subobject. 270 SmallVector<PathEntry, 8> Entries; 271 272 SubobjectDesignator() : Invalid(true) {} 273 274 explicit SubobjectDesignator(QualType T) 275 : Invalid(false), IsOnePastTheEnd(false), 276 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false), 277 MostDerivedPathLength(0), MostDerivedArraySize(0), 278 MostDerivedType(T) {} 279 280 SubobjectDesignator(ASTContext &Ctx, const APValue &V) 281 : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false), 282 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false), 283 MostDerivedPathLength(0), MostDerivedArraySize(0) { 284 assert(V.isLValue() && "Non-LValue used to make an LValue designator?"); 285 if (!Invalid) { 286 IsOnePastTheEnd = V.isLValueOnePastTheEnd(); 287 ArrayRef<PathEntry> VEntries = V.getLValuePath(); 288 Entries.insert(Entries.end(), VEntries.begin(), VEntries.end()); 289 if (V.getLValueBase()) { 290 bool IsArray = false; 291 bool FirstIsUnsizedArray = false; 292 MostDerivedPathLength = findMostDerivedSubobject( 293 Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize, 294 MostDerivedType, IsArray, FirstIsUnsizedArray); 295 MostDerivedIsArrayElement = IsArray; 296 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray; 297 } 298 } 299 } 300 301 void truncate(ASTContext &Ctx, APValue::LValueBase Base, 302 unsigned NewLength) { 303 if (Invalid) 304 return; 305 306 assert(Base && "cannot truncate path for null pointer"); 307 assert(NewLength <= Entries.size() && "not a truncation"); 308 309 if (NewLength == Entries.size()) 310 return; 311 Entries.resize(NewLength); 312 313 bool IsArray = false; 314 bool FirstIsUnsizedArray = false; 315 MostDerivedPathLength = findMostDerivedSubobject( 316 Ctx, Base, Entries, MostDerivedArraySize, MostDerivedType, IsArray, 317 FirstIsUnsizedArray); 318 MostDerivedIsArrayElement = IsArray; 319 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray; 320 } 321 322 void setInvalid() { 323 Invalid = true; 324 Entries.clear(); 325 } 326 327 /// Determine whether the most derived subobject is an array without a 328 /// known bound. 329 bool isMostDerivedAnUnsizedArray() const { 330 assert(!Invalid && "Calling this makes no sense on invalid designators"); 331 return Entries.size() == 1 && FirstEntryIsAnUnsizedArray; 332 } 333 334 /// Determine what the most derived array's size is. Results in an assertion 335 /// failure if the most derived array lacks a size. 336 uint64_t getMostDerivedArraySize() const { 337 assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size"); 338 return MostDerivedArraySize; 339 } 340 341 /// Determine whether this is a one-past-the-end pointer. 342 bool isOnePastTheEnd() const { 343 assert(!Invalid); 344 if (IsOnePastTheEnd) 345 return true; 346 if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement && 347 Entries[MostDerivedPathLength - 1].getAsArrayIndex() == 348 MostDerivedArraySize) 349 return true; 350 return false; 351 } 352 353 /// Get the range of valid index adjustments in the form 354 /// {maximum value that can be subtracted from this pointer, 355 /// maximum value that can be added to this pointer} 356 std::pair<uint64_t, uint64_t> validIndexAdjustments() { 357 if (Invalid || isMostDerivedAnUnsizedArray()) 358 return {0, 0}; 359 360 // [expr.add]p4: For the purposes of these operators, a pointer to a 361 // nonarray object behaves the same as a pointer to the first element of 362 // an array of length one with the type of the object as its element type. 363 bool IsArray = MostDerivedPathLength == Entries.size() && 364 MostDerivedIsArrayElement; 365 uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex() 366 : (uint64_t)IsOnePastTheEnd; 367 uint64_t ArraySize = 368 IsArray ? getMostDerivedArraySize() : (uint64_t)1; 369 return {ArrayIndex, ArraySize - ArrayIndex}; 370 } 371 372 /// Check that this refers to a valid subobject. 373 bool isValidSubobject() const { 374 if (Invalid) 375 return false; 376 return !isOnePastTheEnd(); 377 } 378 /// Check that this refers to a valid subobject, and if not, produce a 379 /// relevant diagnostic and set the designator as invalid. 380 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK); 381 382 /// Get the type of the designated object. 383 QualType getType(ASTContext &Ctx) const { 384 assert(!Invalid && "invalid designator has no subobject type"); 385 return MostDerivedPathLength == Entries.size() 386 ? MostDerivedType 387 : Ctx.getRecordType(getAsBaseClass(Entries.back())); 388 } 389 390 /// Update this designator to refer to the first element within this array. 391 void addArrayUnchecked(const ConstantArrayType *CAT) { 392 Entries.push_back(PathEntry::ArrayIndex(0)); 393 394 // This is a most-derived object. 395 MostDerivedType = CAT->getElementType(); 396 MostDerivedIsArrayElement = true; 397 MostDerivedArraySize = CAT->getSize().getZExtValue(); 398 MostDerivedPathLength = Entries.size(); 399 } 400 /// Update this designator to refer to the first element within the array of 401 /// elements of type T. This is an array of unknown size. 402 void addUnsizedArrayUnchecked(QualType ElemTy) { 403 Entries.push_back(PathEntry::ArrayIndex(0)); 404 405 MostDerivedType = ElemTy; 406 MostDerivedIsArrayElement = true; 407 // The value in MostDerivedArraySize is undefined in this case. So, set it 408 // to an arbitrary value that's likely to loudly break things if it's 409 // used. 410 MostDerivedArraySize = AssumedSizeForUnsizedArray; 411 MostDerivedPathLength = Entries.size(); 412 } 413 /// Update this designator to refer to the given base or member of this 414 /// object. 415 void addDeclUnchecked(const Decl *D, bool Virtual = false) { 416 Entries.push_back(APValue::BaseOrMemberType(D, Virtual)); 417 418 // If this isn't a base class, it's a new most-derived object. 419 if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) { 420 MostDerivedType = FD->getType(); 421 MostDerivedIsArrayElement = false; 422 MostDerivedArraySize = 0; 423 MostDerivedPathLength = Entries.size(); 424 } 425 } 426 /// Update this designator to refer to the given complex component. 427 void addComplexUnchecked(QualType EltTy, bool Imag) { 428 Entries.push_back(PathEntry::ArrayIndex(Imag)); 429 430 // This is technically a most-derived object, though in practice this 431 // is unlikely to matter. 432 MostDerivedType = EltTy; 433 MostDerivedIsArrayElement = true; 434 MostDerivedArraySize = 2; 435 MostDerivedPathLength = Entries.size(); 436 } 437 void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E); 438 void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E, 439 const APSInt &N); 440 /// Add N to the address of this subobject. 441 void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) { 442 if (Invalid || !N) return; 443 uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue(); 444 if (isMostDerivedAnUnsizedArray()) { 445 diagnoseUnsizedArrayPointerArithmetic(Info, E); 446 // Can't verify -- trust that the user is doing the right thing (or if 447 // not, trust that the caller will catch the bad behavior). 448 // FIXME: Should we reject if this overflows, at least? 449 Entries.back() = PathEntry::ArrayIndex( 450 Entries.back().getAsArrayIndex() + TruncatedN); 451 return; 452 } 453 454 // [expr.add]p4: For the purposes of these operators, a pointer to a 455 // nonarray object behaves the same as a pointer to the first element of 456 // an array of length one with the type of the object as its element type. 457 bool IsArray = MostDerivedPathLength == Entries.size() && 458 MostDerivedIsArrayElement; 459 uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex() 460 : (uint64_t)IsOnePastTheEnd; 461 uint64_t ArraySize = 462 IsArray ? getMostDerivedArraySize() : (uint64_t)1; 463 464 if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) { 465 // Calculate the actual index in a wide enough type, so we can include 466 // it in the note. 467 N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65)); 468 (llvm::APInt&)N += ArrayIndex; 469 assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index"); 470 diagnosePointerArithmetic(Info, E, N); 471 setInvalid(); 472 return; 473 } 474 475 ArrayIndex += TruncatedN; 476 assert(ArrayIndex <= ArraySize && 477 "bounds check succeeded for out-of-bounds index"); 478 479 if (IsArray) 480 Entries.back() = PathEntry::ArrayIndex(ArrayIndex); 481 else 482 IsOnePastTheEnd = (ArrayIndex != 0); 483 } 484 }; 485 486 /// A scope at the end of which an object can need to be destroyed. 487 enum class ScopeKind { 488 Block, 489 FullExpression, 490 Call 491 }; 492 493 /// A reference to a particular call and its arguments. 494 struct CallRef { 495 CallRef() : OrigCallee(), CallIndex(0), Version() {} 496 CallRef(const FunctionDecl *Callee, unsigned CallIndex, unsigned Version) 497 : OrigCallee(Callee), CallIndex(CallIndex), Version(Version) {} 498 499 explicit operator bool() const { return OrigCallee; } 500 501 /// Get the parameter that the caller initialized, corresponding to the 502 /// given parameter in the callee. 503 const ParmVarDecl *getOrigParam(const ParmVarDecl *PVD) const { 504 return OrigCallee ? OrigCallee->getParamDecl(PVD->getFunctionScopeIndex()) 505 : PVD; 506 } 507 508 /// The callee at the point where the arguments were evaluated. This might 509 /// be different from the actual callee (a different redeclaration, or a 510 /// virtual override), but this function's parameters are the ones that 511 /// appear in the parameter map. 512 const FunctionDecl *OrigCallee; 513 /// The call index of the frame that holds the argument values. 514 unsigned CallIndex; 515 /// The version of the parameters corresponding to this call. 516 unsigned Version; 517 }; 518 519 /// A stack frame in the constexpr call stack. 520 class CallStackFrame : public interp::Frame { 521 public: 522 EvalInfo &Info; 523 524 /// Parent - The caller of this stack frame. 525 CallStackFrame *Caller; 526 527 /// Callee - The function which was called. 528 const FunctionDecl *Callee; 529 530 /// This - The binding for the this pointer in this call, if any. 531 const LValue *This; 532 533 /// Information on how to find the arguments to this call. Our arguments 534 /// are stored in our parent's CallStackFrame, using the ParmVarDecl* as a 535 /// key and this value as the version. 536 CallRef Arguments; 537 538 /// Source location information about the default argument or default 539 /// initializer expression we're evaluating, if any. 540 CurrentSourceLocExprScope CurSourceLocExprScope; 541 542 // Note that we intentionally use std::map here so that references to 543 // values are stable. 544 typedef std::pair<const void *, unsigned> MapKeyTy; 545 typedef std::map<MapKeyTy, APValue> MapTy; 546 /// Temporaries - Temporary lvalues materialized within this stack frame. 547 MapTy Temporaries; 548 549 /// CallLoc - The location of the call expression for this call. 550 SourceLocation CallLoc; 551 552 /// Index - The call index of this call. 553 unsigned Index; 554 555 /// The stack of integers for tracking version numbers for temporaries. 556 SmallVector<unsigned, 2> TempVersionStack = {1}; 557 unsigned CurTempVersion = TempVersionStack.back(); 558 559 unsigned getTempVersion() const { return TempVersionStack.back(); } 560 561 void pushTempVersion() { 562 TempVersionStack.push_back(++CurTempVersion); 563 } 564 565 void popTempVersion() { 566 TempVersionStack.pop_back(); 567 } 568 569 CallRef createCall(const FunctionDecl *Callee) { 570 return {Callee, Index, ++CurTempVersion}; 571 } 572 573 // FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact 574 // on the overall stack usage of deeply-recursing constexpr evaluations. 575 // (We should cache this map rather than recomputing it repeatedly.) 576 // But let's try this and see how it goes; we can look into caching the map 577 // as a later change. 578 579 /// LambdaCaptureFields - Mapping from captured variables/this to 580 /// corresponding data members in the closure class. 581 llvm::DenseMap<const VarDecl *, FieldDecl *> LambdaCaptureFields; 582 FieldDecl *LambdaThisCaptureField; 583 584 CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, 585 const FunctionDecl *Callee, const LValue *This, 586 CallRef Arguments); 587 ~CallStackFrame(); 588 589 // Return the temporary for Key whose version number is Version. 590 APValue *getTemporary(const void *Key, unsigned Version) { 591 MapKeyTy KV(Key, Version); 592 auto LB = Temporaries.lower_bound(KV); 593 if (LB != Temporaries.end() && LB->first == KV) 594 return &LB->second; 595 // Pair (Key,Version) wasn't found in the map. Check that no elements 596 // in the map have 'Key' as their key. 597 assert((LB == Temporaries.end() || LB->first.first != Key) && 598 (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) && 599 "Element with key 'Key' found in map"); 600 return nullptr; 601 } 602 603 // Return the current temporary for Key in the map. 604 APValue *getCurrentTemporary(const void *Key) { 605 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX)); 606 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key) 607 return &std::prev(UB)->second; 608 return nullptr; 609 } 610 611 // Return the version number of the current temporary for Key. 612 unsigned getCurrentTemporaryVersion(const void *Key) const { 613 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX)); 614 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key) 615 return std::prev(UB)->first.second; 616 return 0; 617 } 618 619 /// Allocate storage for an object of type T in this stack frame. 620 /// Populates LV with a handle to the created object. Key identifies 621 /// the temporary within the stack frame, and must not be reused without 622 /// bumping the temporary version number. 623 template<typename KeyT> 624 APValue &createTemporary(const KeyT *Key, QualType T, 625 ScopeKind Scope, LValue &LV); 626 627 /// Allocate storage for a parameter of a function call made in this frame. 628 APValue &createParam(CallRef Args, const ParmVarDecl *PVD, LValue &LV); 629 630 void describe(llvm::raw_ostream &OS) override; 631 632 Frame *getCaller() const override { return Caller; } 633 SourceLocation getCallLocation() const override { return CallLoc; } 634 const FunctionDecl *getCallee() const override { return Callee; } 635 636 bool isStdFunction() const { 637 for (const DeclContext *DC = Callee; DC; DC = DC->getParent()) 638 if (DC->isStdNamespace()) 639 return true; 640 return false; 641 } 642 643 private: 644 APValue &createLocal(APValue::LValueBase Base, const void *Key, QualType T, 645 ScopeKind Scope); 646 }; 647 648 /// Temporarily override 'this'. 649 class ThisOverrideRAII { 650 public: 651 ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable) 652 : Frame(Frame), OldThis(Frame.This) { 653 if (Enable) 654 Frame.This = NewThis; 655 } 656 ~ThisOverrideRAII() { 657 Frame.This = OldThis; 658 } 659 private: 660 CallStackFrame &Frame; 661 const LValue *OldThis; 662 }; 663 } 664 665 static bool HandleDestruction(EvalInfo &Info, const Expr *E, 666 const LValue &This, QualType ThisType); 667 static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc, 668 APValue::LValueBase LVBase, APValue &Value, 669 QualType T); 670 671 namespace { 672 /// A cleanup, and a flag indicating whether it is lifetime-extended. 673 class Cleanup { 674 llvm::PointerIntPair<APValue*, 2, ScopeKind> Value; 675 APValue::LValueBase Base; 676 QualType T; 677 678 public: 679 Cleanup(APValue *Val, APValue::LValueBase Base, QualType T, 680 ScopeKind Scope) 681 : Value(Val, Scope), Base(Base), T(T) {} 682 683 /// Determine whether this cleanup should be performed at the end of the 684 /// given kind of scope. 685 bool isDestroyedAtEndOf(ScopeKind K) const { 686 return (int)Value.getInt() >= (int)K; 687 } 688 bool endLifetime(EvalInfo &Info, bool RunDestructors) { 689 if (RunDestructors) { 690 SourceLocation Loc; 691 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) 692 Loc = VD->getLocation(); 693 else if (const Expr *E = Base.dyn_cast<const Expr*>()) 694 Loc = E->getExprLoc(); 695 return HandleDestruction(Info, Loc, Base, *Value.getPointer(), T); 696 } 697 *Value.getPointer() = APValue(); 698 return true; 699 } 700 701 bool hasSideEffect() { 702 return T.isDestructedType(); 703 } 704 }; 705 706 /// A reference to an object whose construction we are currently evaluating. 707 struct ObjectUnderConstruction { 708 APValue::LValueBase Base; 709 ArrayRef<APValue::LValuePathEntry> Path; 710 friend bool operator==(const ObjectUnderConstruction &LHS, 711 const ObjectUnderConstruction &RHS) { 712 return LHS.Base == RHS.Base && LHS.Path == RHS.Path; 713 } 714 friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) { 715 return llvm::hash_combine(Obj.Base, Obj.Path); 716 } 717 }; 718 enum class ConstructionPhase { 719 None, 720 Bases, 721 AfterBases, 722 AfterFields, 723 Destroying, 724 DestroyingBases 725 }; 726 } 727 728 namespace llvm { 729 template<> struct DenseMapInfo<ObjectUnderConstruction> { 730 using Base = DenseMapInfo<APValue::LValueBase>; 731 static ObjectUnderConstruction getEmptyKey() { 732 return {Base::getEmptyKey(), {}}; } 733 static ObjectUnderConstruction getTombstoneKey() { 734 return {Base::getTombstoneKey(), {}}; 735 } 736 static unsigned getHashValue(const ObjectUnderConstruction &Object) { 737 return hash_value(Object); 738 } 739 static bool isEqual(const ObjectUnderConstruction &LHS, 740 const ObjectUnderConstruction &RHS) { 741 return LHS == RHS; 742 } 743 }; 744 } 745 746 namespace { 747 /// A dynamically-allocated heap object. 748 struct DynAlloc { 749 /// The value of this heap-allocated object. 750 APValue Value; 751 /// The allocating expression; used for diagnostics. Either a CXXNewExpr 752 /// or a CallExpr (the latter is for direct calls to operator new inside 753 /// std::allocator<T>::allocate). 754 const Expr *AllocExpr = nullptr; 755 756 enum Kind { 757 New, 758 ArrayNew, 759 StdAllocator 760 }; 761 762 /// Get the kind of the allocation. This must match between allocation 763 /// and deallocation. 764 Kind getKind() const { 765 if (auto *NE = dyn_cast<CXXNewExpr>(AllocExpr)) 766 return NE->isArray() ? ArrayNew : New; 767 assert(isa<CallExpr>(AllocExpr)); 768 return StdAllocator; 769 } 770 }; 771 772 struct DynAllocOrder { 773 bool operator()(DynamicAllocLValue L, DynamicAllocLValue R) const { 774 return L.getIndex() < R.getIndex(); 775 } 776 }; 777 778 /// EvalInfo - This is a private struct used by the evaluator to capture 779 /// information about a subexpression as it is folded. It retains information 780 /// about the AST context, but also maintains information about the folded 781 /// expression. 782 /// 783 /// If an expression could be evaluated, it is still possible it is not a C 784 /// "integer constant expression" or constant expression. If not, this struct 785 /// captures information about how and why not. 786 /// 787 /// One bit of information passed *into* the request for constant folding 788 /// indicates whether the subexpression is "evaluated" or not according to C 789 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can 790 /// evaluate the expression regardless of what the RHS is, but C only allows 791 /// certain things in certain situations. 792 class EvalInfo : public interp::State { 793 public: 794 ASTContext &Ctx; 795 796 /// EvalStatus - Contains information about the evaluation. 797 Expr::EvalStatus &EvalStatus; 798 799 /// CurrentCall - The top of the constexpr call stack. 800 CallStackFrame *CurrentCall; 801 802 /// CallStackDepth - The number of calls in the call stack right now. 803 unsigned CallStackDepth; 804 805 /// NextCallIndex - The next call index to assign. 806 unsigned NextCallIndex; 807 808 /// StepsLeft - The remaining number of evaluation steps we're permitted 809 /// to perform. This is essentially a limit for the number of statements 810 /// we will evaluate. 811 unsigned StepsLeft; 812 813 /// Enable the experimental new constant interpreter. If an expression is 814 /// not supported by the interpreter, an error is triggered. 815 bool EnableNewConstInterp; 816 817 /// BottomFrame - The frame in which evaluation started. This must be 818 /// initialized after CurrentCall and CallStackDepth. 819 CallStackFrame BottomFrame; 820 821 /// A stack of values whose lifetimes end at the end of some surrounding 822 /// evaluation frame. 823 llvm::SmallVector<Cleanup, 16> CleanupStack; 824 825 /// EvaluatingDecl - This is the declaration whose initializer is being 826 /// evaluated, if any. 827 APValue::LValueBase EvaluatingDecl; 828 829 enum class EvaluatingDeclKind { 830 None, 831 /// We're evaluating the construction of EvaluatingDecl. 832 Ctor, 833 /// We're evaluating the destruction of EvaluatingDecl. 834 Dtor, 835 }; 836 EvaluatingDeclKind IsEvaluatingDecl = EvaluatingDeclKind::None; 837 838 /// EvaluatingDeclValue - This is the value being constructed for the 839 /// declaration whose initializer is being evaluated, if any. 840 APValue *EvaluatingDeclValue; 841 842 /// Set of objects that are currently being constructed. 843 llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase> 844 ObjectsUnderConstruction; 845 846 /// Current heap allocations, along with the location where each was 847 /// allocated. We use std::map here because we need stable addresses 848 /// for the stored APValues. 849 std::map<DynamicAllocLValue, DynAlloc, DynAllocOrder> HeapAllocs; 850 851 /// The number of heap allocations performed so far in this evaluation. 852 unsigned NumHeapAllocs = 0; 853 854 struct EvaluatingConstructorRAII { 855 EvalInfo &EI; 856 ObjectUnderConstruction Object; 857 bool DidInsert; 858 EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object, 859 bool HasBases) 860 : EI(EI), Object(Object) { 861 DidInsert = 862 EI.ObjectsUnderConstruction 863 .insert({Object, HasBases ? ConstructionPhase::Bases 864 : ConstructionPhase::AfterBases}) 865 .second; 866 } 867 void finishedConstructingBases() { 868 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases; 869 } 870 void finishedConstructingFields() { 871 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterFields; 872 } 873 ~EvaluatingConstructorRAII() { 874 if (DidInsert) EI.ObjectsUnderConstruction.erase(Object); 875 } 876 }; 877 878 struct EvaluatingDestructorRAII { 879 EvalInfo &EI; 880 ObjectUnderConstruction Object; 881 bool DidInsert; 882 EvaluatingDestructorRAII(EvalInfo &EI, ObjectUnderConstruction Object) 883 : EI(EI), Object(Object) { 884 DidInsert = EI.ObjectsUnderConstruction 885 .insert({Object, ConstructionPhase::Destroying}) 886 .second; 887 } 888 void startedDestroyingBases() { 889 EI.ObjectsUnderConstruction[Object] = 890 ConstructionPhase::DestroyingBases; 891 } 892 ~EvaluatingDestructorRAII() { 893 if (DidInsert) 894 EI.ObjectsUnderConstruction.erase(Object); 895 } 896 }; 897 898 ConstructionPhase 899 isEvaluatingCtorDtor(APValue::LValueBase Base, 900 ArrayRef<APValue::LValuePathEntry> Path) { 901 return ObjectsUnderConstruction.lookup({Base, Path}); 902 } 903 904 /// If we're currently speculatively evaluating, the outermost call stack 905 /// depth at which we can mutate state, otherwise 0. 906 unsigned SpeculativeEvaluationDepth = 0; 907 908 /// The current array initialization index, if we're performing array 909 /// initialization. 910 uint64_t ArrayInitIndex = -1; 911 912 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further 913 /// notes attached to it will also be stored, otherwise they will not be. 914 bool HasActiveDiagnostic; 915 916 /// Have we emitted a diagnostic explaining why we couldn't constant 917 /// fold (not just why it's not strictly a constant expression)? 918 bool HasFoldFailureDiagnostic; 919 920 /// Whether or not we're in a context where the front end requires a 921 /// constant value. 922 bool InConstantContext; 923 924 /// Whether we're checking that an expression is a potential constant 925 /// expression. If so, do not fail on constructs that could become constant 926 /// later on (such as a use of an undefined global). 927 bool CheckingPotentialConstantExpression = false; 928 929 /// Whether we're checking for an expression that has undefined behavior. 930 /// If so, we will produce warnings if we encounter an operation that is 931 /// always undefined. 932 /// 933 /// Note that we still need to evaluate the expression normally when this 934 /// is set; this is used when evaluating ICEs in C. 935 bool CheckingForUndefinedBehavior = false; 936 937 enum EvaluationMode { 938 /// Evaluate as a constant expression. Stop if we find that the expression 939 /// is not a constant expression. 940 EM_ConstantExpression, 941 942 /// Evaluate as a constant expression. Stop if we find that the expression 943 /// is not a constant expression. Some expressions can be retried in the 944 /// optimizer if we don't constant fold them here, but in an unevaluated 945 /// context we try to fold them immediately since the optimizer never 946 /// gets a chance to look at it. 947 EM_ConstantExpressionUnevaluated, 948 949 /// Fold the expression to a constant. Stop if we hit a side-effect that 950 /// we can't model. 951 EM_ConstantFold, 952 953 /// Evaluate in any way we know how. Don't worry about side-effects that 954 /// can't be modeled. 955 EM_IgnoreSideEffects, 956 } EvalMode; 957 958 /// Are we checking whether the expression is a potential constant 959 /// expression? 960 bool checkingPotentialConstantExpression() const override { 961 return CheckingPotentialConstantExpression; 962 } 963 964 /// Are we checking an expression for overflow? 965 // FIXME: We should check for any kind of undefined or suspicious behavior 966 // in such constructs, not just overflow. 967 bool checkingForUndefinedBehavior() const override { 968 return CheckingForUndefinedBehavior; 969 } 970 971 EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode) 972 : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr), 973 CallStackDepth(0), NextCallIndex(1), 974 StepsLeft(C.getLangOpts().ConstexprStepLimit), 975 EnableNewConstInterp(C.getLangOpts().EnableNewConstInterp), 976 BottomFrame(*this, SourceLocation(), nullptr, nullptr, CallRef()), 977 EvaluatingDecl((const ValueDecl *)nullptr), 978 EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false), 979 HasFoldFailureDiagnostic(false), InConstantContext(false), 980 EvalMode(Mode) {} 981 982 ~EvalInfo() { 983 discardCleanups(); 984 } 985 986 void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value, 987 EvaluatingDeclKind EDK = EvaluatingDeclKind::Ctor) { 988 EvaluatingDecl = Base; 989 IsEvaluatingDecl = EDK; 990 EvaluatingDeclValue = &Value; 991 } 992 993 bool CheckCallLimit(SourceLocation Loc) { 994 // Don't perform any constexpr calls (other than the call we're checking) 995 // when checking a potential constant expression. 996 if (checkingPotentialConstantExpression() && CallStackDepth > 1) 997 return false; 998 if (NextCallIndex == 0) { 999 // NextCallIndex has wrapped around. 1000 FFDiag(Loc, diag::note_constexpr_call_limit_exceeded); 1001 return false; 1002 } 1003 if (CallStackDepth <= getLangOpts().ConstexprCallDepth) 1004 return true; 1005 FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded) 1006 << getLangOpts().ConstexprCallDepth; 1007 return false; 1008 } 1009 1010 std::pair<CallStackFrame *, unsigned> 1011 getCallFrameAndDepth(unsigned CallIndex) { 1012 assert(CallIndex && "no call index in getCallFrameAndDepth"); 1013 // We will eventually hit BottomFrame, which has Index 1, so Frame can't 1014 // be null in this loop. 1015 unsigned Depth = CallStackDepth; 1016 CallStackFrame *Frame = CurrentCall; 1017 while (Frame->Index > CallIndex) { 1018 Frame = Frame->Caller; 1019 --Depth; 1020 } 1021 if (Frame->Index == CallIndex) 1022 return {Frame, Depth}; 1023 return {nullptr, 0}; 1024 } 1025 1026 bool nextStep(const Stmt *S) { 1027 if (!StepsLeft) { 1028 FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded); 1029 return false; 1030 } 1031 --StepsLeft; 1032 return true; 1033 } 1034 1035 APValue *createHeapAlloc(const Expr *E, QualType T, LValue &LV); 1036 1037 Optional<DynAlloc*> lookupDynamicAlloc(DynamicAllocLValue DA) { 1038 Optional<DynAlloc*> Result; 1039 auto It = HeapAllocs.find(DA); 1040 if (It != HeapAllocs.end()) 1041 Result = &It->second; 1042 return Result; 1043 } 1044 1045 /// Get the allocated storage for the given parameter of the given call. 1046 APValue *getParamSlot(CallRef Call, const ParmVarDecl *PVD) { 1047 CallStackFrame *Frame = getCallFrameAndDepth(Call.CallIndex).first; 1048 return Frame ? Frame->getTemporary(Call.getOrigParam(PVD), Call.Version) 1049 : nullptr; 1050 } 1051 1052 /// Information about a stack frame for std::allocator<T>::[de]allocate. 1053 struct StdAllocatorCaller { 1054 unsigned FrameIndex; 1055 QualType ElemType; 1056 explicit operator bool() const { return FrameIndex != 0; }; 1057 }; 1058 1059 StdAllocatorCaller getStdAllocatorCaller(StringRef FnName) const { 1060 for (const CallStackFrame *Call = CurrentCall; Call != &BottomFrame; 1061 Call = Call->Caller) { 1062 const auto *MD = dyn_cast_or_null<CXXMethodDecl>(Call->Callee); 1063 if (!MD) 1064 continue; 1065 const IdentifierInfo *FnII = MD->getIdentifier(); 1066 if (!FnII || !FnII->isStr(FnName)) 1067 continue; 1068 1069 const auto *CTSD = 1070 dyn_cast<ClassTemplateSpecializationDecl>(MD->getParent()); 1071 if (!CTSD) 1072 continue; 1073 1074 const IdentifierInfo *ClassII = CTSD->getIdentifier(); 1075 const TemplateArgumentList &TAL = CTSD->getTemplateArgs(); 1076 if (CTSD->isInStdNamespace() && ClassII && 1077 ClassII->isStr("allocator") && TAL.size() >= 1 && 1078 TAL[0].getKind() == TemplateArgument::Type) 1079 return {Call->Index, TAL[0].getAsType()}; 1080 } 1081 1082 return {}; 1083 } 1084 1085 void performLifetimeExtension() { 1086 // Disable the cleanups for lifetime-extended temporaries. 1087 CleanupStack.erase(std::remove_if(CleanupStack.begin(), 1088 CleanupStack.end(), 1089 [](Cleanup &C) { 1090 return !C.isDestroyedAtEndOf( 1091 ScopeKind::FullExpression); 1092 }), 1093 CleanupStack.end()); 1094 } 1095 1096 /// Throw away any remaining cleanups at the end of evaluation. If any 1097 /// cleanups would have had a side-effect, note that as an unmodeled 1098 /// side-effect and return false. Otherwise, return true. 1099 bool discardCleanups() { 1100 for (Cleanup &C : CleanupStack) { 1101 if (C.hasSideEffect() && !noteSideEffect()) { 1102 CleanupStack.clear(); 1103 return false; 1104 } 1105 } 1106 CleanupStack.clear(); 1107 return true; 1108 } 1109 1110 private: 1111 interp::Frame *getCurrentFrame() override { return CurrentCall; } 1112 const interp::Frame *getBottomFrame() const override { return &BottomFrame; } 1113 1114 bool hasActiveDiagnostic() override { return HasActiveDiagnostic; } 1115 void setActiveDiagnostic(bool Flag) override { HasActiveDiagnostic = Flag; } 1116 1117 void setFoldFailureDiagnostic(bool Flag) override { 1118 HasFoldFailureDiagnostic = Flag; 1119 } 1120 1121 Expr::EvalStatus &getEvalStatus() const override { return EvalStatus; } 1122 1123 ASTContext &getCtx() const override { return Ctx; } 1124 1125 // If we have a prior diagnostic, it will be noting that the expression 1126 // isn't a constant expression. This diagnostic is more important, 1127 // unless we require this evaluation to produce a constant expression. 1128 // 1129 // FIXME: We might want to show both diagnostics to the user in 1130 // EM_ConstantFold mode. 1131 bool hasPriorDiagnostic() override { 1132 if (!EvalStatus.Diag->empty()) { 1133 switch (EvalMode) { 1134 case EM_ConstantFold: 1135 case EM_IgnoreSideEffects: 1136 if (!HasFoldFailureDiagnostic) 1137 break; 1138 // We've already failed to fold something. Keep that diagnostic. 1139 LLVM_FALLTHROUGH; 1140 case EM_ConstantExpression: 1141 case EM_ConstantExpressionUnevaluated: 1142 setActiveDiagnostic(false); 1143 return true; 1144 } 1145 } 1146 return false; 1147 } 1148 1149 unsigned getCallStackDepth() override { return CallStackDepth; } 1150 1151 public: 1152 /// Should we continue evaluation after encountering a side-effect that we 1153 /// couldn't model? 1154 bool keepEvaluatingAfterSideEffect() { 1155 switch (EvalMode) { 1156 case EM_IgnoreSideEffects: 1157 return true; 1158 1159 case EM_ConstantExpression: 1160 case EM_ConstantExpressionUnevaluated: 1161 case EM_ConstantFold: 1162 // By default, assume any side effect might be valid in some other 1163 // evaluation of this expression from a different context. 1164 return checkingPotentialConstantExpression() || 1165 checkingForUndefinedBehavior(); 1166 } 1167 llvm_unreachable("Missed EvalMode case"); 1168 } 1169 1170 /// Note that we have had a side-effect, and determine whether we should 1171 /// keep evaluating. 1172 bool noteSideEffect() { 1173 EvalStatus.HasSideEffects = true; 1174 return keepEvaluatingAfterSideEffect(); 1175 } 1176 1177 /// Should we continue evaluation after encountering undefined behavior? 1178 bool keepEvaluatingAfterUndefinedBehavior() { 1179 switch (EvalMode) { 1180 case EM_IgnoreSideEffects: 1181 case EM_ConstantFold: 1182 return true; 1183 1184 case EM_ConstantExpression: 1185 case EM_ConstantExpressionUnevaluated: 1186 return checkingForUndefinedBehavior(); 1187 } 1188 llvm_unreachable("Missed EvalMode case"); 1189 } 1190 1191 /// Note that we hit something that was technically undefined behavior, but 1192 /// that we can evaluate past it (such as signed overflow or floating-point 1193 /// division by zero.) 1194 bool noteUndefinedBehavior() override { 1195 EvalStatus.HasUndefinedBehavior = true; 1196 return keepEvaluatingAfterUndefinedBehavior(); 1197 } 1198 1199 /// Should we continue evaluation as much as possible after encountering a 1200 /// construct which can't be reduced to a value? 1201 bool keepEvaluatingAfterFailure() const override { 1202 if (!StepsLeft) 1203 return false; 1204 1205 switch (EvalMode) { 1206 case EM_ConstantExpression: 1207 case EM_ConstantExpressionUnevaluated: 1208 case EM_ConstantFold: 1209 case EM_IgnoreSideEffects: 1210 return checkingPotentialConstantExpression() || 1211 checkingForUndefinedBehavior(); 1212 } 1213 llvm_unreachable("Missed EvalMode case"); 1214 } 1215 1216 /// Notes that we failed to evaluate an expression that other expressions 1217 /// directly depend on, and determine if we should keep evaluating. This 1218 /// should only be called if we actually intend to keep evaluating. 1219 /// 1220 /// Call noteSideEffect() instead if we may be able to ignore the value that 1221 /// we failed to evaluate, e.g. if we failed to evaluate Foo() in: 1222 /// 1223 /// (Foo(), 1) // use noteSideEffect 1224 /// (Foo() || true) // use noteSideEffect 1225 /// Foo() + 1 // use noteFailure 1226 LLVM_NODISCARD bool noteFailure() { 1227 // Failure when evaluating some expression often means there is some 1228 // subexpression whose evaluation was skipped. Therefore, (because we 1229 // don't track whether we skipped an expression when unwinding after an 1230 // evaluation failure) every evaluation failure that bubbles up from a 1231 // subexpression implies that a side-effect has potentially happened. We 1232 // skip setting the HasSideEffects flag to true until we decide to 1233 // continue evaluating after that point, which happens here. 1234 bool KeepGoing = keepEvaluatingAfterFailure(); 1235 EvalStatus.HasSideEffects |= KeepGoing; 1236 return KeepGoing; 1237 } 1238 1239 class ArrayInitLoopIndex { 1240 EvalInfo &Info; 1241 uint64_t OuterIndex; 1242 1243 public: 1244 ArrayInitLoopIndex(EvalInfo &Info) 1245 : Info(Info), OuterIndex(Info.ArrayInitIndex) { 1246 Info.ArrayInitIndex = 0; 1247 } 1248 ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; } 1249 1250 operator uint64_t&() { return Info.ArrayInitIndex; } 1251 }; 1252 }; 1253 1254 /// Object used to treat all foldable expressions as constant expressions. 1255 struct FoldConstant { 1256 EvalInfo &Info; 1257 bool Enabled; 1258 bool HadNoPriorDiags; 1259 EvalInfo::EvaluationMode OldMode; 1260 1261 explicit FoldConstant(EvalInfo &Info, bool Enabled) 1262 : Info(Info), 1263 Enabled(Enabled), 1264 HadNoPriorDiags(Info.EvalStatus.Diag && 1265 Info.EvalStatus.Diag->empty() && 1266 !Info.EvalStatus.HasSideEffects), 1267 OldMode(Info.EvalMode) { 1268 if (Enabled) 1269 Info.EvalMode = EvalInfo::EM_ConstantFold; 1270 } 1271 void keepDiagnostics() { Enabled = false; } 1272 ~FoldConstant() { 1273 if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() && 1274 !Info.EvalStatus.HasSideEffects) 1275 Info.EvalStatus.Diag->clear(); 1276 Info.EvalMode = OldMode; 1277 } 1278 }; 1279 1280 /// RAII object used to set the current evaluation mode to ignore 1281 /// side-effects. 1282 struct IgnoreSideEffectsRAII { 1283 EvalInfo &Info; 1284 EvalInfo::EvaluationMode OldMode; 1285 explicit IgnoreSideEffectsRAII(EvalInfo &Info) 1286 : Info(Info), OldMode(Info.EvalMode) { 1287 Info.EvalMode = EvalInfo::EM_IgnoreSideEffects; 1288 } 1289 1290 ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; } 1291 }; 1292 1293 /// RAII object used to optionally suppress diagnostics and side-effects from 1294 /// a speculative evaluation. 1295 class SpeculativeEvaluationRAII { 1296 EvalInfo *Info = nullptr; 1297 Expr::EvalStatus OldStatus; 1298 unsigned OldSpeculativeEvaluationDepth; 1299 1300 void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) { 1301 Info = Other.Info; 1302 OldStatus = Other.OldStatus; 1303 OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth; 1304 Other.Info = nullptr; 1305 } 1306 1307 void maybeRestoreState() { 1308 if (!Info) 1309 return; 1310 1311 Info->EvalStatus = OldStatus; 1312 Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth; 1313 } 1314 1315 public: 1316 SpeculativeEvaluationRAII() = default; 1317 1318 SpeculativeEvaluationRAII( 1319 EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr) 1320 : Info(&Info), OldStatus(Info.EvalStatus), 1321 OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) { 1322 Info.EvalStatus.Diag = NewDiag; 1323 Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1; 1324 } 1325 1326 SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete; 1327 SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) { 1328 moveFromAndCancel(std::move(Other)); 1329 } 1330 1331 SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) { 1332 maybeRestoreState(); 1333 moveFromAndCancel(std::move(Other)); 1334 return *this; 1335 } 1336 1337 ~SpeculativeEvaluationRAII() { maybeRestoreState(); } 1338 }; 1339 1340 /// RAII object wrapping a full-expression or block scope, and handling 1341 /// the ending of the lifetime of temporaries created within it. 1342 template<ScopeKind Kind> 1343 class ScopeRAII { 1344 EvalInfo &Info; 1345 unsigned OldStackSize; 1346 public: 1347 ScopeRAII(EvalInfo &Info) 1348 : Info(Info), OldStackSize(Info.CleanupStack.size()) { 1349 // Push a new temporary version. This is needed to distinguish between 1350 // temporaries created in different iterations of a loop. 1351 Info.CurrentCall->pushTempVersion(); 1352 } 1353 bool destroy(bool RunDestructors = true) { 1354 bool OK = cleanup(Info, RunDestructors, OldStackSize); 1355 OldStackSize = -1U; 1356 return OK; 1357 } 1358 ~ScopeRAII() { 1359 if (OldStackSize != -1U) 1360 destroy(false); 1361 // Body moved to a static method to encourage the compiler to inline away 1362 // instances of this class. 1363 Info.CurrentCall->popTempVersion(); 1364 } 1365 private: 1366 static bool cleanup(EvalInfo &Info, bool RunDestructors, 1367 unsigned OldStackSize) { 1368 assert(OldStackSize <= Info.CleanupStack.size() && 1369 "running cleanups out of order?"); 1370 1371 // Run all cleanups for a block scope, and non-lifetime-extended cleanups 1372 // for a full-expression scope. 1373 bool Success = true; 1374 for (unsigned I = Info.CleanupStack.size(); I > OldStackSize; --I) { 1375 if (Info.CleanupStack[I - 1].isDestroyedAtEndOf(Kind)) { 1376 if (!Info.CleanupStack[I - 1].endLifetime(Info, RunDestructors)) { 1377 Success = false; 1378 break; 1379 } 1380 } 1381 } 1382 1383 // Compact any retained cleanups. 1384 auto NewEnd = Info.CleanupStack.begin() + OldStackSize; 1385 if (Kind != ScopeKind::Block) 1386 NewEnd = 1387 std::remove_if(NewEnd, Info.CleanupStack.end(), [](Cleanup &C) { 1388 return C.isDestroyedAtEndOf(Kind); 1389 }); 1390 Info.CleanupStack.erase(NewEnd, Info.CleanupStack.end()); 1391 return Success; 1392 } 1393 }; 1394 typedef ScopeRAII<ScopeKind::Block> BlockScopeRAII; 1395 typedef ScopeRAII<ScopeKind::FullExpression> FullExpressionRAII; 1396 typedef ScopeRAII<ScopeKind::Call> CallScopeRAII; 1397 } 1398 1399 bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E, 1400 CheckSubobjectKind CSK) { 1401 if (Invalid) 1402 return false; 1403 if (isOnePastTheEnd()) { 1404 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject) 1405 << CSK; 1406 setInvalid(); 1407 return false; 1408 } 1409 // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there 1410 // must actually be at least one array element; even a VLA cannot have a 1411 // bound of zero. And if our index is nonzero, we already had a CCEDiag. 1412 return true; 1413 } 1414 1415 void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, 1416 const Expr *E) { 1417 Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed); 1418 // Do not set the designator as invalid: we can represent this situation, 1419 // and correct handling of __builtin_object_size requires us to do so. 1420 } 1421 1422 void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info, 1423 const Expr *E, 1424 const APSInt &N) { 1425 // If we're complaining, we must be able to statically determine the size of 1426 // the most derived array. 1427 if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement) 1428 Info.CCEDiag(E, diag::note_constexpr_array_index) 1429 << N << /*array*/ 0 1430 << static_cast<unsigned>(getMostDerivedArraySize()); 1431 else 1432 Info.CCEDiag(E, diag::note_constexpr_array_index) 1433 << N << /*non-array*/ 1; 1434 setInvalid(); 1435 } 1436 1437 CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, 1438 const FunctionDecl *Callee, const LValue *This, 1439 CallRef Call) 1440 : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This), 1441 Arguments(Call), CallLoc(CallLoc), Index(Info.NextCallIndex++) { 1442 Info.CurrentCall = this; 1443 ++Info.CallStackDepth; 1444 } 1445 1446 CallStackFrame::~CallStackFrame() { 1447 assert(Info.CurrentCall == this && "calls retired out of order"); 1448 --Info.CallStackDepth; 1449 Info.CurrentCall = Caller; 1450 } 1451 1452 static bool isRead(AccessKinds AK) { 1453 return AK == AK_Read || AK == AK_ReadObjectRepresentation; 1454 } 1455 1456 static bool isModification(AccessKinds AK) { 1457 switch (AK) { 1458 case AK_Read: 1459 case AK_ReadObjectRepresentation: 1460 case AK_MemberCall: 1461 case AK_DynamicCast: 1462 case AK_TypeId: 1463 return false; 1464 case AK_Assign: 1465 case AK_Increment: 1466 case AK_Decrement: 1467 case AK_Construct: 1468 case AK_Destroy: 1469 return true; 1470 } 1471 llvm_unreachable("unknown access kind"); 1472 } 1473 1474 static bool isAnyAccess(AccessKinds AK) { 1475 return isRead(AK) || isModification(AK); 1476 } 1477 1478 /// Is this an access per the C++ definition? 1479 static bool isFormalAccess(AccessKinds AK) { 1480 return isAnyAccess(AK) && AK != AK_Construct && AK != AK_Destroy; 1481 } 1482 1483 /// Is this kind of axcess valid on an indeterminate object value? 1484 static bool isValidIndeterminateAccess(AccessKinds AK) { 1485 switch (AK) { 1486 case AK_Read: 1487 case AK_Increment: 1488 case AK_Decrement: 1489 // These need the object's value. 1490 return false; 1491 1492 case AK_ReadObjectRepresentation: 1493 case AK_Assign: 1494 case AK_Construct: 1495 case AK_Destroy: 1496 // Construction and destruction don't need the value. 1497 return true; 1498 1499 case AK_MemberCall: 1500 case AK_DynamicCast: 1501 case AK_TypeId: 1502 // These aren't really meaningful on scalars. 1503 return true; 1504 } 1505 llvm_unreachable("unknown access kind"); 1506 } 1507 1508 namespace { 1509 struct ComplexValue { 1510 private: 1511 bool IsInt; 1512 1513 public: 1514 APSInt IntReal, IntImag; 1515 APFloat FloatReal, FloatImag; 1516 1517 ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {} 1518 1519 void makeComplexFloat() { IsInt = false; } 1520 bool isComplexFloat() const { return !IsInt; } 1521 APFloat &getComplexFloatReal() { return FloatReal; } 1522 APFloat &getComplexFloatImag() { return FloatImag; } 1523 1524 void makeComplexInt() { IsInt = true; } 1525 bool isComplexInt() const { return IsInt; } 1526 APSInt &getComplexIntReal() { return IntReal; } 1527 APSInt &getComplexIntImag() { return IntImag; } 1528 1529 void moveInto(APValue &v) const { 1530 if (isComplexFloat()) 1531 v = APValue(FloatReal, FloatImag); 1532 else 1533 v = APValue(IntReal, IntImag); 1534 } 1535 void setFrom(const APValue &v) { 1536 assert(v.isComplexFloat() || v.isComplexInt()); 1537 if (v.isComplexFloat()) { 1538 makeComplexFloat(); 1539 FloatReal = v.getComplexFloatReal(); 1540 FloatImag = v.getComplexFloatImag(); 1541 } else { 1542 makeComplexInt(); 1543 IntReal = v.getComplexIntReal(); 1544 IntImag = v.getComplexIntImag(); 1545 } 1546 } 1547 }; 1548 1549 struct LValue { 1550 APValue::LValueBase Base; 1551 CharUnits Offset; 1552 SubobjectDesignator Designator; 1553 bool IsNullPtr : 1; 1554 bool InvalidBase : 1; 1555 1556 const APValue::LValueBase getLValueBase() const { return Base; } 1557 CharUnits &getLValueOffset() { return Offset; } 1558 const CharUnits &getLValueOffset() const { return Offset; } 1559 SubobjectDesignator &getLValueDesignator() { return Designator; } 1560 const SubobjectDesignator &getLValueDesignator() const { return Designator;} 1561 bool isNullPointer() const { return IsNullPtr;} 1562 1563 unsigned getLValueCallIndex() const { return Base.getCallIndex(); } 1564 unsigned getLValueVersion() const { return Base.getVersion(); } 1565 1566 void moveInto(APValue &V) const { 1567 if (Designator.Invalid) 1568 V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr); 1569 else { 1570 assert(!InvalidBase && "APValues can't handle invalid LValue bases"); 1571 V = APValue(Base, Offset, Designator.Entries, 1572 Designator.IsOnePastTheEnd, IsNullPtr); 1573 } 1574 } 1575 void setFrom(ASTContext &Ctx, const APValue &V) { 1576 assert(V.isLValue() && "Setting LValue from a non-LValue?"); 1577 Base = V.getLValueBase(); 1578 Offset = V.getLValueOffset(); 1579 InvalidBase = false; 1580 Designator = SubobjectDesignator(Ctx, V); 1581 IsNullPtr = V.isNullPointer(); 1582 } 1583 1584 void set(APValue::LValueBase B, bool BInvalid = false) { 1585 #ifndef NDEBUG 1586 // We only allow a few types of invalid bases. Enforce that here. 1587 if (BInvalid) { 1588 const auto *E = B.get<const Expr *>(); 1589 assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) && 1590 "Unexpected type of invalid base"); 1591 } 1592 #endif 1593 1594 Base = B; 1595 Offset = CharUnits::fromQuantity(0); 1596 InvalidBase = BInvalid; 1597 Designator = SubobjectDesignator(getType(B)); 1598 IsNullPtr = false; 1599 } 1600 1601 void setNull(ASTContext &Ctx, QualType PointerTy) { 1602 Base = (const ValueDecl *)nullptr; 1603 Offset = 1604 CharUnits::fromQuantity(Ctx.getTargetNullPointerValue(PointerTy)); 1605 InvalidBase = false; 1606 Designator = SubobjectDesignator(PointerTy->getPointeeType()); 1607 IsNullPtr = true; 1608 } 1609 1610 void setInvalid(APValue::LValueBase B, unsigned I = 0) { 1611 set(B, true); 1612 } 1613 1614 std::string toString(ASTContext &Ctx, QualType T) const { 1615 APValue Printable; 1616 moveInto(Printable); 1617 return Printable.getAsString(Ctx, T); 1618 } 1619 1620 private: 1621 // Check that this LValue is not based on a null pointer. If it is, produce 1622 // a diagnostic and mark the designator as invalid. 1623 template <typename GenDiagType> 1624 bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) { 1625 if (Designator.Invalid) 1626 return false; 1627 if (IsNullPtr) { 1628 GenDiag(); 1629 Designator.setInvalid(); 1630 return false; 1631 } 1632 return true; 1633 } 1634 1635 public: 1636 bool checkNullPointer(EvalInfo &Info, const Expr *E, 1637 CheckSubobjectKind CSK) { 1638 return checkNullPointerDiagnosingWith([&Info, E, CSK] { 1639 Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK; 1640 }); 1641 } 1642 1643 bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E, 1644 AccessKinds AK) { 1645 return checkNullPointerDiagnosingWith([&Info, E, AK] { 1646 Info.FFDiag(E, diag::note_constexpr_access_null) << AK; 1647 }); 1648 } 1649 1650 // Check this LValue refers to an object. If not, set the designator to be 1651 // invalid and emit a diagnostic. 1652 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { 1653 return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) && 1654 Designator.checkSubobject(Info, E, CSK); 1655 } 1656 1657 void addDecl(EvalInfo &Info, const Expr *E, 1658 const Decl *D, bool Virtual = false) { 1659 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base)) 1660 Designator.addDeclUnchecked(D, Virtual); 1661 } 1662 void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) { 1663 if (!Designator.Entries.empty()) { 1664 Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array); 1665 Designator.setInvalid(); 1666 return; 1667 } 1668 if (checkSubobject(Info, E, CSK_ArrayToPointer)) { 1669 assert(getType(Base)->isPointerType() || getType(Base)->isArrayType()); 1670 Designator.FirstEntryIsAnUnsizedArray = true; 1671 Designator.addUnsizedArrayUnchecked(ElemTy); 1672 } 1673 } 1674 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) { 1675 if (checkSubobject(Info, E, CSK_ArrayToPointer)) 1676 Designator.addArrayUnchecked(CAT); 1677 } 1678 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) { 1679 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real)) 1680 Designator.addComplexUnchecked(EltTy, Imag); 1681 } 1682 void clearIsNullPointer() { 1683 IsNullPtr = false; 1684 } 1685 void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E, 1686 const APSInt &Index, CharUnits ElementSize) { 1687 // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB, 1688 // but we're not required to diagnose it and it's valid in C++.) 1689 if (!Index) 1690 return; 1691 1692 // Compute the new offset in the appropriate width, wrapping at 64 bits. 1693 // FIXME: When compiling for a 32-bit target, we should use 32-bit 1694 // offsets. 1695 uint64_t Offset64 = Offset.getQuantity(); 1696 uint64_t ElemSize64 = ElementSize.getQuantity(); 1697 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue(); 1698 Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64); 1699 1700 if (checkNullPointer(Info, E, CSK_ArrayIndex)) 1701 Designator.adjustIndex(Info, E, Index); 1702 clearIsNullPointer(); 1703 } 1704 void adjustOffset(CharUnits N) { 1705 Offset += N; 1706 if (N.getQuantity()) 1707 clearIsNullPointer(); 1708 } 1709 }; 1710 1711 struct MemberPtr { 1712 MemberPtr() {} 1713 explicit MemberPtr(const ValueDecl *Decl) : 1714 DeclAndIsDerivedMember(Decl, false), Path() {} 1715 1716 /// The member or (direct or indirect) field referred to by this member 1717 /// pointer, or 0 if this is a null member pointer. 1718 const ValueDecl *getDecl() const { 1719 return DeclAndIsDerivedMember.getPointer(); 1720 } 1721 /// Is this actually a member of some type derived from the relevant class? 1722 bool isDerivedMember() const { 1723 return DeclAndIsDerivedMember.getInt(); 1724 } 1725 /// Get the class which the declaration actually lives in. 1726 const CXXRecordDecl *getContainingRecord() const { 1727 return cast<CXXRecordDecl>( 1728 DeclAndIsDerivedMember.getPointer()->getDeclContext()); 1729 } 1730 1731 void moveInto(APValue &V) const { 1732 V = APValue(getDecl(), isDerivedMember(), Path); 1733 } 1734 void setFrom(const APValue &V) { 1735 assert(V.isMemberPointer()); 1736 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl()); 1737 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember()); 1738 Path.clear(); 1739 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath(); 1740 Path.insert(Path.end(), P.begin(), P.end()); 1741 } 1742 1743 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating 1744 /// whether the member is a member of some class derived from the class type 1745 /// of the member pointer. 1746 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember; 1747 /// Path - The path of base/derived classes from the member declaration's 1748 /// class (exclusive) to the class type of the member pointer (inclusive). 1749 SmallVector<const CXXRecordDecl*, 4> Path; 1750 1751 /// Perform a cast towards the class of the Decl (either up or down the 1752 /// hierarchy). 1753 bool castBack(const CXXRecordDecl *Class) { 1754 assert(!Path.empty()); 1755 const CXXRecordDecl *Expected; 1756 if (Path.size() >= 2) 1757 Expected = Path[Path.size() - 2]; 1758 else 1759 Expected = getContainingRecord(); 1760 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) { 1761 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*), 1762 // if B does not contain the original member and is not a base or 1763 // derived class of the class containing the original member, the result 1764 // of the cast is undefined. 1765 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to 1766 // (D::*). We consider that to be a language defect. 1767 return false; 1768 } 1769 Path.pop_back(); 1770 return true; 1771 } 1772 /// Perform a base-to-derived member pointer cast. 1773 bool castToDerived(const CXXRecordDecl *Derived) { 1774 if (!getDecl()) 1775 return true; 1776 if (!isDerivedMember()) { 1777 Path.push_back(Derived); 1778 return true; 1779 } 1780 if (!castBack(Derived)) 1781 return false; 1782 if (Path.empty()) 1783 DeclAndIsDerivedMember.setInt(false); 1784 return true; 1785 } 1786 /// Perform a derived-to-base member pointer cast. 1787 bool castToBase(const CXXRecordDecl *Base) { 1788 if (!getDecl()) 1789 return true; 1790 if (Path.empty()) 1791 DeclAndIsDerivedMember.setInt(true); 1792 if (isDerivedMember()) { 1793 Path.push_back(Base); 1794 return true; 1795 } 1796 return castBack(Base); 1797 } 1798 }; 1799 1800 /// Compare two member pointers, which are assumed to be of the same type. 1801 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) { 1802 if (!LHS.getDecl() || !RHS.getDecl()) 1803 return !LHS.getDecl() && !RHS.getDecl(); 1804 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl()) 1805 return false; 1806 return LHS.Path == RHS.Path; 1807 } 1808 } 1809 1810 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E); 1811 static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, 1812 const LValue &This, const Expr *E, 1813 bool AllowNonLiteralTypes = false); 1814 static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info, 1815 bool InvalidBaseOK = false); 1816 static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info, 1817 bool InvalidBaseOK = false); 1818 static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, 1819 EvalInfo &Info); 1820 static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info); 1821 static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info); 1822 static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, 1823 EvalInfo &Info); 1824 static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info); 1825 static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info); 1826 static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result, 1827 EvalInfo &Info); 1828 static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result); 1829 1830 /// Evaluate an integer or fixed point expression into an APResult. 1831 static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result, 1832 EvalInfo &Info); 1833 1834 /// Evaluate only a fixed point expression into an APResult. 1835 static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result, 1836 EvalInfo &Info); 1837 1838 //===----------------------------------------------------------------------===// 1839 // Misc utilities 1840 //===----------------------------------------------------------------------===// 1841 1842 /// Negate an APSInt in place, converting it to a signed form if necessary, and 1843 /// preserving its value (by extending by up to one bit as needed). 1844 static void negateAsSigned(APSInt &Int) { 1845 if (Int.isUnsigned() || Int.isMinSignedValue()) { 1846 Int = Int.extend(Int.getBitWidth() + 1); 1847 Int.setIsSigned(true); 1848 } 1849 Int = -Int; 1850 } 1851 1852 template<typename KeyT> 1853 APValue &CallStackFrame::createTemporary(const KeyT *Key, QualType T, 1854 ScopeKind Scope, LValue &LV) { 1855 unsigned Version = getTempVersion(); 1856 APValue::LValueBase Base(Key, Index, Version); 1857 LV.set(Base); 1858 return createLocal(Base, Key, T, Scope); 1859 } 1860 1861 /// Allocate storage for a parameter of a function call made in this frame. 1862 APValue &CallStackFrame::createParam(CallRef Args, const ParmVarDecl *PVD, 1863 LValue &LV) { 1864 assert(Args.CallIndex == Index && "creating parameter in wrong frame"); 1865 APValue::LValueBase Base(PVD, Index, Args.Version); 1866 LV.set(Base); 1867 // We always destroy parameters at the end of the call, even if we'd allow 1868 // them to live to the end of the full-expression at runtime, in order to 1869 // give portable results and match other compilers. 1870 return createLocal(Base, PVD, PVD->getType(), ScopeKind::Call); 1871 } 1872 1873 APValue &CallStackFrame::createLocal(APValue::LValueBase Base, const void *Key, 1874 QualType T, ScopeKind Scope) { 1875 assert(Base.getCallIndex() == Index && "lvalue for wrong frame"); 1876 unsigned Version = Base.getVersion(); 1877 APValue &Result = Temporaries[MapKeyTy(Key, Version)]; 1878 assert(Result.isAbsent() && "local created multiple times"); 1879 1880 // If we're creating a local immediately in the operand of a speculative 1881 // evaluation, don't register a cleanup to be run outside the speculative 1882 // evaluation context, since we won't actually be able to initialize this 1883 // object. 1884 if (Index <= Info.SpeculativeEvaluationDepth) { 1885 if (T.isDestructedType()) 1886 Info.noteSideEffect(); 1887 } else { 1888 Info.CleanupStack.push_back(Cleanup(&Result, Base, T, Scope)); 1889 } 1890 return Result; 1891 } 1892 1893 APValue *EvalInfo::createHeapAlloc(const Expr *E, QualType T, LValue &LV) { 1894 if (NumHeapAllocs > DynamicAllocLValue::getMaxIndex()) { 1895 FFDiag(E, diag::note_constexpr_heap_alloc_limit_exceeded); 1896 return nullptr; 1897 } 1898 1899 DynamicAllocLValue DA(NumHeapAllocs++); 1900 LV.set(APValue::LValueBase::getDynamicAlloc(DA, T)); 1901 auto Result = HeapAllocs.emplace(std::piecewise_construct, 1902 std::forward_as_tuple(DA), std::tuple<>()); 1903 assert(Result.second && "reused a heap alloc index?"); 1904 Result.first->second.AllocExpr = E; 1905 return &Result.first->second.Value; 1906 } 1907 1908 /// Produce a string describing the given constexpr call. 1909 void CallStackFrame::describe(raw_ostream &Out) { 1910 unsigned ArgIndex = 0; 1911 bool IsMemberCall = isa<CXXMethodDecl>(Callee) && 1912 !isa<CXXConstructorDecl>(Callee) && 1913 cast<CXXMethodDecl>(Callee)->isInstance(); 1914 1915 if (!IsMemberCall) 1916 Out << *Callee << '('; 1917 1918 if (This && IsMemberCall) { 1919 APValue Val; 1920 This->moveInto(Val); 1921 Val.printPretty(Out, Info.Ctx, 1922 This->Designator.MostDerivedType); 1923 // FIXME: Add parens around Val if needed. 1924 Out << "->" << *Callee << '('; 1925 IsMemberCall = false; 1926 } 1927 1928 for (FunctionDecl::param_const_iterator I = Callee->param_begin(), 1929 E = Callee->param_end(); I != E; ++I, ++ArgIndex) { 1930 if (ArgIndex > (unsigned)IsMemberCall) 1931 Out << ", "; 1932 1933 const ParmVarDecl *Param = *I; 1934 APValue *V = Info.getParamSlot(Arguments, Param); 1935 if (V) 1936 V->printPretty(Out, Info.Ctx, Param->getType()); 1937 else 1938 Out << "<...>"; 1939 1940 if (ArgIndex == 0 && IsMemberCall) 1941 Out << "->" << *Callee << '('; 1942 } 1943 1944 Out << ')'; 1945 } 1946 1947 /// Evaluate an expression to see if it had side-effects, and discard its 1948 /// result. 1949 /// \return \c true if the caller should keep evaluating. 1950 static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) { 1951 assert(!E->isValueDependent()); 1952 APValue Scratch; 1953 if (!Evaluate(Scratch, Info, E)) 1954 // We don't need the value, but we might have skipped a side effect here. 1955 return Info.noteSideEffect(); 1956 return true; 1957 } 1958 1959 /// Should this call expression be treated as a string literal? 1960 static bool IsStringLiteralCall(const CallExpr *E) { 1961 unsigned Builtin = E->getBuiltinCallee(); 1962 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString || 1963 Builtin == Builtin::BI__builtin___NSStringMakeConstantString); 1964 } 1965 1966 static bool IsGlobalLValue(APValue::LValueBase B) { 1967 // C++11 [expr.const]p3 An address constant expression is a prvalue core 1968 // constant expression of pointer type that evaluates to... 1969 1970 // ... a null pointer value, or a prvalue core constant expression of type 1971 // std::nullptr_t. 1972 if (!B) return true; 1973 1974 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { 1975 // ... the address of an object with static storage duration, 1976 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 1977 return VD->hasGlobalStorage(); 1978 if (isa<TemplateParamObjectDecl>(D)) 1979 return true; 1980 // ... the address of a function, 1981 // ... the address of a GUID [MS extension], 1982 return isa<FunctionDecl>(D) || isa<MSGuidDecl>(D); 1983 } 1984 1985 if (B.is<TypeInfoLValue>() || B.is<DynamicAllocLValue>()) 1986 return true; 1987 1988 const Expr *E = B.get<const Expr*>(); 1989 switch (E->getStmtClass()) { 1990 default: 1991 return false; 1992 case Expr::CompoundLiteralExprClass: { 1993 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 1994 return CLE->isFileScope() && CLE->isLValue(); 1995 } 1996 case Expr::MaterializeTemporaryExprClass: 1997 // A materialized temporary might have been lifetime-extended to static 1998 // storage duration. 1999 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static; 2000 // A string literal has static storage duration. 2001 case Expr::StringLiteralClass: 2002 case Expr::PredefinedExprClass: 2003 case Expr::ObjCStringLiteralClass: 2004 case Expr::ObjCEncodeExprClass: 2005 return true; 2006 case Expr::ObjCBoxedExprClass: 2007 return cast<ObjCBoxedExpr>(E)->isExpressibleAsConstantInitializer(); 2008 case Expr::CallExprClass: 2009 return IsStringLiteralCall(cast<CallExpr>(E)); 2010 // For GCC compatibility, &&label has static storage duration. 2011 case Expr::AddrLabelExprClass: 2012 return true; 2013 // A Block literal expression may be used as the initialization value for 2014 // Block variables at global or local static scope. 2015 case Expr::BlockExprClass: 2016 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures(); 2017 case Expr::ImplicitValueInitExprClass: 2018 // FIXME: 2019 // We can never form an lvalue with an implicit value initialization as its 2020 // base through expression evaluation, so these only appear in one case: the 2021 // implicit variable declaration we invent when checking whether a constexpr 2022 // constructor can produce a constant expression. We must assume that such 2023 // an expression might be a global lvalue. 2024 return true; 2025 } 2026 } 2027 2028 static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) { 2029 return LVal.Base.dyn_cast<const ValueDecl*>(); 2030 } 2031 2032 static bool IsLiteralLValue(const LValue &Value) { 2033 if (Value.getLValueCallIndex()) 2034 return false; 2035 const Expr *E = Value.Base.dyn_cast<const Expr*>(); 2036 return E && !isa<MaterializeTemporaryExpr>(E); 2037 } 2038 2039 static bool IsWeakLValue(const LValue &Value) { 2040 const ValueDecl *Decl = GetLValueBaseDecl(Value); 2041 return Decl && Decl->isWeak(); 2042 } 2043 2044 static bool isZeroSized(const LValue &Value) { 2045 const ValueDecl *Decl = GetLValueBaseDecl(Value); 2046 if (Decl && isa<VarDecl>(Decl)) { 2047 QualType Ty = Decl->getType(); 2048 if (Ty->isArrayType()) 2049 return Ty->isIncompleteType() || 2050 Decl->getASTContext().getTypeSize(Ty) == 0; 2051 } 2052 return false; 2053 } 2054 2055 static bool HasSameBase(const LValue &A, const LValue &B) { 2056 if (!A.getLValueBase()) 2057 return !B.getLValueBase(); 2058 if (!B.getLValueBase()) 2059 return false; 2060 2061 if (A.getLValueBase().getOpaqueValue() != 2062 B.getLValueBase().getOpaqueValue()) 2063 return false; 2064 2065 return A.getLValueCallIndex() == B.getLValueCallIndex() && 2066 A.getLValueVersion() == B.getLValueVersion(); 2067 } 2068 2069 static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) { 2070 assert(Base && "no location for a null lvalue"); 2071 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 2072 2073 // For a parameter, find the corresponding call stack frame (if it still 2074 // exists), and point at the parameter of the function definition we actually 2075 // invoked. 2076 if (auto *PVD = dyn_cast_or_null<ParmVarDecl>(VD)) { 2077 unsigned Idx = PVD->getFunctionScopeIndex(); 2078 for (CallStackFrame *F = Info.CurrentCall; F; F = F->Caller) { 2079 if (F->Arguments.CallIndex == Base.getCallIndex() && 2080 F->Arguments.Version == Base.getVersion() && F->Callee && 2081 Idx < F->Callee->getNumParams()) { 2082 VD = F->Callee->getParamDecl(Idx); 2083 break; 2084 } 2085 } 2086 } 2087 2088 if (VD) 2089 Info.Note(VD->getLocation(), diag::note_declared_at); 2090 else if (const Expr *E = Base.dyn_cast<const Expr*>()) 2091 Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here); 2092 else if (DynamicAllocLValue DA = Base.dyn_cast<DynamicAllocLValue>()) { 2093 // FIXME: Produce a note for dangling pointers too. 2094 if (Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA)) 2095 Info.Note((*Alloc)->AllocExpr->getExprLoc(), 2096 diag::note_constexpr_dynamic_alloc_here); 2097 } 2098 // We have no information to show for a typeid(T) object. 2099 } 2100 2101 enum class CheckEvaluationResultKind { 2102 ConstantExpression, 2103 FullyInitialized, 2104 }; 2105 2106 /// Materialized temporaries that we've already checked to determine if they're 2107 /// initializsed by a constant expression. 2108 using CheckedTemporaries = 2109 llvm::SmallPtrSet<const MaterializeTemporaryExpr *, 8>; 2110 2111 static bool CheckEvaluationResult(CheckEvaluationResultKind CERK, 2112 EvalInfo &Info, SourceLocation DiagLoc, 2113 QualType Type, const APValue &Value, 2114 ConstantExprKind Kind, 2115 SourceLocation SubobjectLoc, 2116 CheckedTemporaries &CheckedTemps); 2117 2118 /// Check that this reference or pointer core constant expression is a valid 2119 /// value for an address or reference constant expression. Return true if we 2120 /// can fold this expression, whether or not it's a constant expression. 2121 static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc, 2122 QualType Type, const LValue &LVal, 2123 ConstantExprKind Kind, 2124 CheckedTemporaries &CheckedTemps) { 2125 bool IsReferenceType = Type->isReferenceType(); 2126 2127 APValue::LValueBase Base = LVal.getLValueBase(); 2128 const SubobjectDesignator &Designator = LVal.getLValueDesignator(); 2129 2130 const Expr *BaseE = Base.dyn_cast<const Expr *>(); 2131 const ValueDecl *BaseVD = Base.dyn_cast<const ValueDecl*>(); 2132 2133 // Additional restrictions apply in a template argument. We only enforce the 2134 // C++20 restrictions here; additional syntactic and semantic restrictions 2135 // are applied elsewhere. 2136 if (isTemplateArgument(Kind)) { 2137 int InvalidBaseKind = -1; 2138 StringRef Ident; 2139 if (Base.is<TypeInfoLValue>()) 2140 InvalidBaseKind = 0; 2141 else if (isa_and_nonnull<StringLiteral>(BaseE)) 2142 InvalidBaseKind = 1; 2143 else if (isa_and_nonnull<MaterializeTemporaryExpr>(BaseE) || 2144 isa_and_nonnull<LifetimeExtendedTemporaryDecl>(BaseVD)) 2145 InvalidBaseKind = 2; 2146 else if (auto *PE = dyn_cast_or_null<PredefinedExpr>(BaseE)) { 2147 InvalidBaseKind = 3; 2148 Ident = PE->getIdentKindName(); 2149 } 2150 2151 if (InvalidBaseKind != -1) { 2152 Info.FFDiag(Loc, diag::note_constexpr_invalid_template_arg) 2153 << IsReferenceType << !Designator.Entries.empty() << InvalidBaseKind 2154 << Ident; 2155 return false; 2156 } 2157 } 2158 2159 if (auto *FD = dyn_cast_or_null<FunctionDecl>(BaseVD)) { 2160 if (FD->isConsteval()) { 2161 Info.FFDiag(Loc, diag::note_consteval_address_accessible) 2162 << !Type->isAnyPointerType(); 2163 Info.Note(FD->getLocation(), diag::note_declared_at); 2164 return false; 2165 } 2166 } 2167 2168 // Check that the object is a global. Note that the fake 'this' object we 2169 // manufacture when checking potential constant expressions is conservatively 2170 // assumed to be global here. 2171 if (!IsGlobalLValue(Base)) { 2172 if (Info.getLangOpts().CPlusPlus11) { 2173 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 2174 Info.FFDiag(Loc, diag::note_constexpr_non_global, 1) 2175 << IsReferenceType << !Designator.Entries.empty() 2176 << !!VD << VD; 2177 2178 auto *VarD = dyn_cast_or_null<VarDecl>(VD); 2179 if (VarD && VarD->isConstexpr()) { 2180 // Non-static local constexpr variables have unintuitive semantics: 2181 // constexpr int a = 1; 2182 // constexpr const int *p = &a; 2183 // ... is invalid because the address of 'a' is not constant. Suggest 2184 // adding a 'static' in this case. 2185 Info.Note(VarD->getLocation(), diag::note_constexpr_not_static) 2186 << VarD 2187 << FixItHint::CreateInsertion(VarD->getBeginLoc(), "static "); 2188 } else { 2189 NoteLValueLocation(Info, Base); 2190 } 2191 } else { 2192 Info.FFDiag(Loc); 2193 } 2194 // Don't allow references to temporaries to escape. 2195 return false; 2196 } 2197 assert((Info.checkingPotentialConstantExpression() || 2198 LVal.getLValueCallIndex() == 0) && 2199 "have call index for global lvalue"); 2200 2201 if (Base.is<DynamicAllocLValue>()) { 2202 Info.FFDiag(Loc, diag::note_constexpr_dynamic_alloc) 2203 << IsReferenceType << !Designator.Entries.empty(); 2204 NoteLValueLocation(Info, Base); 2205 return false; 2206 } 2207 2208 if (BaseVD) { 2209 if (const VarDecl *Var = dyn_cast<const VarDecl>(BaseVD)) { 2210 // Check if this is a thread-local variable. 2211 if (Var->getTLSKind()) 2212 // FIXME: Diagnostic! 2213 return false; 2214 2215 // A dllimport variable never acts like a constant, unless we're 2216 // evaluating a value for use only in name mangling. 2217 if (!isForManglingOnly(Kind) && Var->hasAttr<DLLImportAttr>()) 2218 // FIXME: Diagnostic! 2219 return false; 2220 } 2221 if (const auto *FD = dyn_cast<const FunctionDecl>(BaseVD)) { 2222 // __declspec(dllimport) must be handled very carefully: 2223 // We must never initialize an expression with the thunk in C++. 2224 // Doing otherwise would allow the same id-expression to yield 2225 // different addresses for the same function in different translation 2226 // units. However, this means that we must dynamically initialize the 2227 // expression with the contents of the import address table at runtime. 2228 // 2229 // The C language has no notion of ODR; furthermore, it has no notion of 2230 // dynamic initialization. This means that we are permitted to 2231 // perform initialization with the address of the thunk. 2232 if (Info.getLangOpts().CPlusPlus && !isForManglingOnly(Kind) && 2233 FD->hasAttr<DLLImportAttr>()) 2234 // FIXME: Diagnostic! 2235 return false; 2236 } 2237 } else if (const auto *MTE = 2238 dyn_cast_or_null<MaterializeTemporaryExpr>(BaseE)) { 2239 if (CheckedTemps.insert(MTE).second) { 2240 QualType TempType = getType(Base); 2241 if (TempType.isDestructedType()) { 2242 Info.FFDiag(MTE->getExprLoc(), 2243 diag::note_constexpr_unsupported_temporary_nontrivial_dtor) 2244 << TempType; 2245 return false; 2246 } 2247 2248 APValue *V = MTE->getOrCreateValue(false); 2249 assert(V && "evasluation result refers to uninitialised temporary"); 2250 if (!CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression, 2251 Info, MTE->getExprLoc(), TempType, *V, 2252 Kind, SourceLocation(), CheckedTemps)) 2253 return false; 2254 } 2255 } 2256 2257 // Allow address constant expressions to be past-the-end pointers. This is 2258 // an extension: the standard requires them to point to an object. 2259 if (!IsReferenceType) 2260 return true; 2261 2262 // A reference constant expression must refer to an object. 2263 if (!Base) { 2264 // FIXME: diagnostic 2265 Info.CCEDiag(Loc); 2266 return true; 2267 } 2268 2269 // Does this refer one past the end of some object? 2270 if (!Designator.Invalid && Designator.isOnePastTheEnd()) { 2271 Info.FFDiag(Loc, diag::note_constexpr_past_end, 1) 2272 << !Designator.Entries.empty() << !!BaseVD << BaseVD; 2273 NoteLValueLocation(Info, Base); 2274 } 2275 2276 return true; 2277 } 2278 2279 /// Member pointers are constant expressions unless they point to a 2280 /// non-virtual dllimport member function. 2281 static bool CheckMemberPointerConstantExpression(EvalInfo &Info, 2282 SourceLocation Loc, 2283 QualType Type, 2284 const APValue &Value, 2285 ConstantExprKind Kind) { 2286 const ValueDecl *Member = Value.getMemberPointerDecl(); 2287 const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member); 2288 if (!FD) 2289 return true; 2290 if (FD->isConsteval()) { 2291 Info.FFDiag(Loc, diag::note_consteval_address_accessible) << /*pointer*/ 0; 2292 Info.Note(FD->getLocation(), diag::note_declared_at); 2293 return false; 2294 } 2295 return isForManglingOnly(Kind) || FD->isVirtual() || 2296 !FD->hasAttr<DLLImportAttr>(); 2297 } 2298 2299 /// Check that this core constant expression is of literal type, and if not, 2300 /// produce an appropriate diagnostic. 2301 static bool CheckLiteralType(EvalInfo &Info, const Expr *E, 2302 const LValue *This = nullptr) { 2303 if (!E->isPRValue() || E->getType()->isLiteralType(Info.Ctx)) 2304 return true; 2305 2306 // C++1y: A constant initializer for an object o [...] may also invoke 2307 // constexpr constructors for o and its subobjects even if those objects 2308 // are of non-literal class types. 2309 // 2310 // C++11 missed this detail for aggregates, so classes like this: 2311 // struct foo_t { union { int i; volatile int j; } u; }; 2312 // are not (obviously) initializable like so: 2313 // __attribute__((__require_constant_initialization__)) 2314 // static const foo_t x = {{0}}; 2315 // because "i" is a subobject with non-literal initialization (due to the 2316 // volatile member of the union). See: 2317 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677 2318 // Therefore, we use the C++1y behavior. 2319 if (This && Info.EvaluatingDecl == This->getLValueBase()) 2320 return true; 2321 2322 // Prvalue constant expressions must be of literal types. 2323 if (Info.getLangOpts().CPlusPlus11) 2324 Info.FFDiag(E, diag::note_constexpr_nonliteral) 2325 << E->getType(); 2326 else 2327 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 2328 return false; 2329 } 2330 2331 static bool CheckEvaluationResult(CheckEvaluationResultKind CERK, 2332 EvalInfo &Info, SourceLocation DiagLoc, 2333 QualType Type, const APValue &Value, 2334 ConstantExprKind Kind, 2335 SourceLocation SubobjectLoc, 2336 CheckedTemporaries &CheckedTemps) { 2337 if (!Value.hasValue()) { 2338 Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized) 2339 << true << Type; 2340 if (SubobjectLoc.isValid()) 2341 Info.Note(SubobjectLoc, diag::note_constexpr_subobject_declared_here); 2342 return false; 2343 } 2344 2345 // We allow _Atomic(T) to be initialized from anything that T can be 2346 // initialized from. 2347 if (const AtomicType *AT = Type->getAs<AtomicType>()) 2348 Type = AT->getValueType(); 2349 2350 // Core issue 1454: For a literal constant expression of array or class type, 2351 // each subobject of its value shall have been initialized by a constant 2352 // expression. 2353 if (Value.isArray()) { 2354 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType(); 2355 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) { 2356 if (!CheckEvaluationResult(CERK, Info, DiagLoc, EltTy, 2357 Value.getArrayInitializedElt(I), Kind, 2358 SubobjectLoc, CheckedTemps)) 2359 return false; 2360 } 2361 if (!Value.hasArrayFiller()) 2362 return true; 2363 return CheckEvaluationResult(CERK, Info, DiagLoc, EltTy, 2364 Value.getArrayFiller(), Kind, SubobjectLoc, 2365 CheckedTemps); 2366 } 2367 if (Value.isUnion() && Value.getUnionField()) { 2368 return CheckEvaluationResult( 2369 CERK, Info, DiagLoc, Value.getUnionField()->getType(), 2370 Value.getUnionValue(), Kind, Value.getUnionField()->getLocation(), 2371 CheckedTemps); 2372 } 2373 if (Value.isStruct()) { 2374 RecordDecl *RD = Type->castAs<RecordType>()->getDecl(); 2375 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) { 2376 unsigned BaseIndex = 0; 2377 for (const CXXBaseSpecifier &BS : CD->bases()) { 2378 if (!CheckEvaluationResult(CERK, Info, DiagLoc, BS.getType(), 2379 Value.getStructBase(BaseIndex), Kind, 2380 BS.getBeginLoc(), CheckedTemps)) 2381 return false; 2382 ++BaseIndex; 2383 } 2384 } 2385 for (const auto *I : RD->fields()) { 2386 if (I->isUnnamedBitfield()) 2387 continue; 2388 2389 if (!CheckEvaluationResult(CERK, Info, DiagLoc, I->getType(), 2390 Value.getStructField(I->getFieldIndex()), 2391 Kind, I->getLocation(), CheckedTemps)) 2392 return false; 2393 } 2394 } 2395 2396 if (Value.isLValue() && 2397 CERK == CheckEvaluationResultKind::ConstantExpression) { 2398 LValue LVal; 2399 LVal.setFrom(Info.Ctx, Value); 2400 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Kind, 2401 CheckedTemps); 2402 } 2403 2404 if (Value.isMemberPointer() && 2405 CERK == CheckEvaluationResultKind::ConstantExpression) 2406 return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Kind); 2407 2408 // Everything else is fine. 2409 return true; 2410 } 2411 2412 /// Check that this core constant expression value is a valid value for a 2413 /// constant expression. If not, report an appropriate diagnostic. Does not 2414 /// check that the expression is of literal type. 2415 static bool CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc, 2416 QualType Type, const APValue &Value, 2417 ConstantExprKind Kind) { 2418 // Nothing to check for a constant expression of type 'cv void'. 2419 if (Type->isVoidType()) 2420 return true; 2421 2422 CheckedTemporaries CheckedTemps; 2423 return CheckEvaluationResult(CheckEvaluationResultKind::ConstantExpression, 2424 Info, DiagLoc, Type, Value, Kind, 2425 SourceLocation(), CheckedTemps); 2426 } 2427 2428 /// Check that this evaluated value is fully-initialized and can be loaded by 2429 /// an lvalue-to-rvalue conversion. 2430 static bool CheckFullyInitialized(EvalInfo &Info, SourceLocation DiagLoc, 2431 QualType Type, const APValue &Value) { 2432 CheckedTemporaries CheckedTemps; 2433 return CheckEvaluationResult( 2434 CheckEvaluationResultKind::FullyInitialized, Info, DiagLoc, Type, Value, 2435 ConstantExprKind::Normal, SourceLocation(), CheckedTemps); 2436 } 2437 2438 /// Enforce C++2a [expr.const]/4.17, which disallows new-expressions unless 2439 /// "the allocated storage is deallocated within the evaluation". 2440 static bool CheckMemoryLeaks(EvalInfo &Info) { 2441 if (!Info.HeapAllocs.empty()) { 2442 // We can still fold to a constant despite a compile-time memory leak, 2443 // so long as the heap allocation isn't referenced in the result (we check 2444 // that in CheckConstantExpression). 2445 Info.CCEDiag(Info.HeapAllocs.begin()->second.AllocExpr, 2446 diag::note_constexpr_memory_leak) 2447 << unsigned(Info.HeapAllocs.size() - 1); 2448 } 2449 return true; 2450 } 2451 2452 static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) { 2453 // A null base expression indicates a null pointer. These are always 2454 // evaluatable, and they are false unless the offset is zero. 2455 if (!Value.getLValueBase()) { 2456 Result = !Value.getLValueOffset().isZero(); 2457 return true; 2458 } 2459 2460 // We have a non-null base. These are generally known to be true, but if it's 2461 // a weak declaration it can be null at runtime. 2462 Result = true; 2463 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>(); 2464 return !Decl || !Decl->isWeak(); 2465 } 2466 2467 static bool HandleConversionToBool(const APValue &Val, bool &Result) { 2468 switch (Val.getKind()) { 2469 case APValue::None: 2470 case APValue::Indeterminate: 2471 return false; 2472 case APValue::Int: 2473 Result = Val.getInt().getBoolValue(); 2474 return true; 2475 case APValue::FixedPoint: 2476 Result = Val.getFixedPoint().getBoolValue(); 2477 return true; 2478 case APValue::Float: 2479 Result = !Val.getFloat().isZero(); 2480 return true; 2481 case APValue::ComplexInt: 2482 Result = Val.getComplexIntReal().getBoolValue() || 2483 Val.getComplexIntImag().getBoolValue(); 2484 return true; 2485 case APValue::ComplexFloat: 2486 Result = !Val.getComplexFloatReal().isZero() || 2487 !Val.getComplexFloatImag().isZero(); 2488 return true; 2489 case APValue::LValue: 2490 return EvalPointerValueAsBool(Val, Result); 2491 case APValue::MemberPointer: 2492 Result = Val.getMemberPointerDecl(); 2493 return true; 2494 case APValue::Vector: 2495 case APValue::Array: 2496 case APValue::Struct: 2497 case APValue::Union: 2498 case APValue::AddrLabelDiff: 2499 return false; 2500 } 2501 2502 llvm_unreachable("unknown APValue kind"); 2503 } 2504 2505 static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result, 2506 EvalInfo &Info) { 2507 assert(!E->isValueDependent()); 2508 assert(E->isPRValue() && "missing lvalue-to-rvalue conv in bool condition"); 2509 APValue Val; 2510 if (!Evaluate(Val, Info, E)) 2511 return false; 2512 return HandleConversionToBool(Val, Result); 2513 } 2514 2515 template<typename T> 2516 static bool HandleOverflow(EvalInfo &Info, const Expr *E, 2517 const T &SrcValue, QualType DestType) { 2518 Info.CCEDiag(E, diag::note_constexpr_overflow) 2519 << SrcValue << DestType; 2520 return Info.noteUndefinedBehavior(); 2521 } 2522 2523 static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E, 2524 QualType SrcType, const APFloat &Value, 2525 QualType DestType, APSInt &Result) { 2526 unsigned DestWidth = Info.Ctx.getIntWidth(DestType); 2527 // Determine whether we are converting to unsigned or signed. 2528 bool DestSigned = DestType->isSignedIntegerOrEnumerationType(); 2529 2530 Result = APSInt(DestWidth, !DestSigned); 2531 bool ignored; 2532 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored) 2533 & APFloat::opInvalidOp) 2534 return HandleOverflow(Info, E, Value, DestType); 2535 return true; 2536 } 2537 2538 /// Get rounding mode used for evaluation of the specified expression. 2539 /// \param[out] DynamicRM Is set to true is the requested rounding mode is 2540 /// dynamic. 2541 /// If rounding mode is unknown at compile time, still try to evaluate the 2542 /// expression. If the result is exact, it does not depend on rounding mode. 2543 /// So return "tonearest" mode instead of "dynamic". 2544 static llvm::RoundingMode getActiveRoundingMode(EvalInfo &Info, const Expr *E, 2545 bool &DynamicRM) { 2546 llvm::RoundingMode RM = 2547 E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).getRoundingMode(); 2548 DynamicRM = (RM == llvm::RoundingMode::Dynamic); 2549 if (DynamicRM) 2550 RM = llvm::RoundingMode::NearestTiesToEven; 2551 return RM; 2552 } 2553 2554 /// Check if the given evaluation result is allowed for constant evaluation. 2555 static bool checkFloatingPointResult(EvalInfo &Info, const Expr *E, 2556 APFloat::opStatus St) { 2557 // In a constant context, assume that any dynamic rounding mode or FP 2558 // exception state matches the default floating-point environment. 2559 if (Info.InConstantContext) 2560 return true; 2561 2562 FPOptions FPO = E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()); 2563 if ((St & APFloat::opInexact) && 2564 FPO.getRoundingMode() == llvm::RoundingMode::Dynamic) { 2565 // Inexact result means that it depends on rounding mode. If the requested 2566 // mode is dynamic, the evaluation cannot be made in compile time. 2567 Info.FFDiag(E, diag::note_constexpr_dynamic_rounding); 2568 return false; 2569 } 2570 2571 if ((St != APFloat::opOK) && 2572 (FPO.getRoundingMode() == llvm::RoundingMode::Dynamic || 2573 FPO.getFPExceptionMode() != LangOptions::FPE_Ignore || 2574 FPO.getAllowFEnvAccess())) { 2575 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict); 2576 return false; 2577 } 2578 2579 if ((St & APFloat::opStatus::opInvalidOp) && 2580 FPO.getFPExceptionMode() != LangOptions::FPE_Ignore) { 2581 // There is no usefully definable result. 2582 Info.FFDiag(E); 2583 return false; 2584 } 2585 2586 // FIXME: if: 2587 // - evaluation triggered other FP exception, and 2588 // - exception mode is not "ignore", and 2589 // - the expression being evaluated is not a part of global variable 2590 // initializer, 2591 // the evaluation probably need to be rejected. 2592 return true; 2593 } 2594 2595 static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E, 2596 QualType SrcType, QualType DestType, 2597 APFloat &Result) { 2598 assert(isa<CastExpr>(E) || isa<CompoundAssignOperator>(E)); 2599 bool DynamicRM; 2600 llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM); 2601 APFloat::opStatus St; 2602 APFloat Value = Result; 2603 bool ignored; 2604 St = Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), RM, &ignored); 2605 return checkFloatingPointResult(Info, E, St); 2606 } 2607 2608 static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E, 2609 QualType DestType, QualType SrcType, 2610 const APSInt &Value) { 2611 unsigned DestWidth = Info.Ctx.getIntWidth(DestType); 2612 // Figure out if this is a truncate, extend or noop cast. 2613 // If the input is signed, do a sign extend, noop, or truncate. 2614 APSInt Result = Value.extOrTrunc(DestWidth); 2615 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType()); 2616 if (DestType->isBooleanType()) 2617 Result = Value.getBoolValue(); 2618 return Result; 2619 } 2620 2621 static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E, 2622 const FPOptions FPO, 2623 QualType SrcType, const APSInt &Value, 2624 QualType DestType, APFloat &Result) { 2625 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1); 2626 APFloat::opStatus St = Result.convertFromAPInt(Value, Value.isSigned(), 2627 APFloat::rmNearestTiesToEven); 2628 if (!Info.InConstantContext && St != llvm::APFloatBase::opOK && 2629 FPO.isFPConstrained()) { 2630 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict); 2631 return false; 2632 } 2633 return true; 2634 } 2635 2636 static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E, 2637 APValue &Value, const FieldDecl *FD) { 2638 assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield"); 2639 2640 if (!Value.isInt()) { 2641 // Trying to store a pointer-cast-to-integer into a bitfield. 2642 // FIXME: In this case, we should provide the diagnostic for casting 2643 // a pointer to an integer. 2644 assert(Value.isLValue() && "integral value neither int nor lvalue?"); 2645 Info.FFDiag(E); 2646 return false; 2647 } 2648 2649 APSInt &Int = Value.getInt(); 2650 unsigned OldBitWidth = Int.getBitWidth(); 2651 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx); 2652 if (NewBitWidth < OldBitWidth) 2653 Int = Int.trunc(NewBitWidth).extend(OldBitWidth); 2654 return true; 2655 } 2656 2657 static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E, 2658 llvm::APInt &Res) { 2659 APValue SVal; 2660 if (!Evaluate(SVal, Info, E)) 2661 return false; 2662 if (SVal.isInt()) { 2663 Res = SVal.getInt(); 2664 return true; 2665 } 2666 if (SVal.isFloat()) { 2667 Res = SVal.getFloat().bitcastToAPInt(); 2668 return true; 2669 } 2670 if (SVal.isVector()) { 2671 QualType VecTy = E->getType(); 2672 unsigned VecSize = Info.Ctx.getTypeSize(VecTy); 2673 QualType EltTy = VecTy->castAs<VectorType>()->getElementType(); 2674 unsigned EltSize = Info.Ctx.getTypeSize(EltTy); 2675 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); 2676 Res = llvm::APInt::getNullValue(VecSize); 2677 for (unsigned i = 0; i < SVal.getVectorLength(); i++) { 2678 APValue &Elt = SVal.getVectorElt(i); 2679 llvm::APInt EltAsInt; 2680 if (Elt.isInt()) { 2681 EltAsInt = Elt.getInt(); 2682 } else if (Elt.isFloat()) { 2683 EltAsInt = Elt.getFloat().bitcastToAPInt(); 2684 } else { 2685 // Don't try to handle vectors of anything other than int or float 2686 // (not sure if it's possible to hit this case). 2687 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 2688 return false; 2689 } 2690 unsigned BaseEltSize = EltAsInt.getBitWidth(); 2691 if (BigEndian) 2692 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize); 2693 else 2694 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize); 2695 } 2696 return true; 2697 } 2698 // Give up if the input isn't an int, float, or vector. For example, we 2699 // reject "(v4i16)(intptr_t)&a". 2700 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 2701 return false; 2702 } 2703 2704 /// Perform the given integer operation, which is known to need at most BitWidth 2705 /// bits, and check for overflow in the original type (if that type was not an 2706 /// unsigned type). 2707 template<typename Operation> 2708 static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E, 2709 const APSInt &LHS, const APSInt &RHS, 2710 unsigned BitWidth, Operation Op, 2711 APSInt &Result) { 2712 if (LHS.isUnsigned()) { 2713 Result = Op(LHS, RHS); 2714 return true; 2715 } 2716 2717 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false); 2718 Result = Value.trunc(LHS.getBitWidth()); 2719 if (Result.extend(BitWidth) != Value) { 2720 if (Info.checkingForUndefinedBehavior()) 2721 Info.Ctx.getDiagnostics().Report(E->getExprLoc(), 2722 diag::warn_integer_constant_overflow) 2723 << toString(Result, 10) << E->getType(); 2724 return HandleOverflow(Info, E, Value, E->getType()); 2725 } 2726 return true; 2727 } 2728 2729 /// Perform the given binary integer operation. 2730 static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS, 2731 BinaryOperatorKind Opcode, APSInt RHS, 2732 APSInt &Result) { 2733 switch (Opcode) { 2734 default: 2735 Info.FFDiag(E); 2736 return false; 2737 case BO_Mul: 2738 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2, 2739 std::multiplies<APSInt>(), Result); 2740 case BO_Add: 2741 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, 2742 std::plus<APSInt>(), Result); 2743 case BO_Sub: 2744 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, 2745 std::minus<APSInt>(), Result); 2746 case BO_And: Result = LHS & RHS; return true; 2747 case BO_Xor: Result = LHS ^ RHS; return true; 2748 case BO_Or: Result = LHS | RHS; return true; 2749 case BO_Div: 2750 case BO_Rem: 2751 if (RHS == 0) { 2752 Info.FFDiag(E, diag::note_expr_divide_by_zero); 2753 return false; 2754 } 2755 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS); 2756 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports 2757 // this operation and gives the two's complement result. 2758 if (RHS.isNegative() && RHS.isAllOnesValue() && 2759 LHS.isSigned() && LHS.isMinSignedValue()) 2760 return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), 2761 E->getType()); 2762 return true; 2763 case BO_Shl: { 2764 if (Info.getLangOpts().OpenCL) 2765 // OpenCL 6.3j: shift values are effectively % word size of LHS. 2766 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), 2767 static_cast<uint64_t>(LHS.getBitWidth() - 1)), 2768 RHS.isUnsigned()); 2769 else if (RHS.isSigned() && RHS.isNegative()) { 2770 // During constant-folding, a negative shift is an opposite shift. Such 2771 // a shift is not a constant expression. 2772 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; 2773 RHS = -RHS; 2774 goto shift_right; 2775 } 2776 shift_left: 2777 // C++11 [expr.shift]p1: Shift width must be less than the bit width of 2778 // the shifted type. 2779 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); 2780 if (SA != RHS) { 2781 Info.CCEDiag(E, diag::note_constexpr_large_shift) 2782 << RHS << E->getType() << LHS.getBitWidth(); 2783 } else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus20) { 2784 // C++11 [expr.shift]p2: A signed left shift must have a non-negative 2785 // operand, and must not overflow the corresponding unsigned type. 2786 // C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to 2787 // E1 x 2^E2 module 2^N. 2788 if (LHS.isNegative()) 2789 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS; 2790 else if (LHS.countLeadingZeros() < SA) 2791 Info.CCEDiag(E, diag::note_constexpr_lshift_discards); 2792 } 2793 Result = LHS << SA; 2794 return true; 2795 } 2796 case BO_Shr: { 2797 if (Info.getLangOpts().OpenCL) 2798 // OpenCL 6.3j: shift values are effectively % word size of LHS. 2799 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), 2800 static_cast<uint64_t>(LHS.getBitWidth() - 1)), 2801 RHS.isUnsigned()); 2802 else if (RHS.isSigned() && RHS.isNegative()) { 2803 // During constant-folding, a negative shift is an opposite shift. Such a 2804 // shift is not a constant expression. 2805 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; 2806 RHS = -RHS; 2807 goto shift_left; 2808 } 2809 shift_right: 2810 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the 2811 // shifted type. 2812 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); 2813 if (SA != RHS) 2814 Info.CCEDiag(E, diag::note_constexpr_large_shift) 2815 << RHS << E->getType() << LHS.getBitWidth(); 2816 Result = LHS >> SA; 2817 return true; 2818 } 2819 2820 case BO_LT: Result = LHS < RHS; return true; 2821 case BO_GT: Result = LHS > RHS; return true; 2822 case BO_LE: Result = LHS <= RHS; return true; 2823 case BO_GE: Result = LHS >= RHS; return true; 2824 case BO_EQ: Result = LHS == RHS; return true; 2825 case BO_NE: Result = LHS != RHS; return true; 2826 case BO_Cmp: 2827 llvm_unreachable("BO_Cmp should be handled elsewhere"); 2828 } 2829 } 2830 2831 /// Perform the given binary floating-point operation, in-place, on LHS. 2832 static bool handleFloatFloatBinOp(EvalInfo &Info, const BinaryOperator *E, 2833 APFloat &LHS, BinaryOperatorKind Opcode, 2834 const APFloat &RHS) { 2835 bool DynamicRM; 2836 llvm::RoundingMode RM = getActiveRoundingMode(Info, E, DynamicRM); 2837 APFloat::opStatus St; 2838 switch (Opcode) { 2839 default: 2840 Info.FFDiag(E); 2841 return false; 2842 case BO_Mul: 2843 St = LHS.multiply(RHS, RM); 2844 break; 2845 case BO_Add: 2846 St = LHS.add(RHS, RM); 2847 break; 2848 case BO_Sub: 2849 St = LHS.subtract(RHS, RM); 2850 break; 2851 case BO_Div: 2852 // [expr.mul]p4: 2853 // If the second operand of / or % is zero the behavior is undefined. 2854 if (RHS.isZero()) 2855 Info.CCEDiag(E, diag::note_expr_divide_by_zero); 2856 St = LHS.divide(RHS, RM); 2857 break; 2858 } 2859 2860 // [expr.pre]p4: 2861 // If during the evaluation of an expression, the result is not 2862 // mathematically defined [...], the behavior is undefined. 2863 // FIXME: C++ rules require us to not conform to IEEE 754 here. 2864 if (LHS.isNaN()) { 2865 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN(); 2866 return Info.noteUndefinedBehavior(); 2867 } 2868 2869 return checkFloatingPointResult(Info, E, St); 2870 } 2871 2872 static bool handleLogicalOpForVector(const APInt &LHSValue, 2873 BinaryOperatorKind Opcode, 2874 const APInt &RHSValue, APInt &Result) { 2875 bool LHS = (LHSValue != 0); 2876 bool RHS = (RHSValue != 0); 2877 2878 if (Opcode == BO_LAnd) 2879 Result = LHS && RHS; 2880 else 2881 Result = LHS || RHS; 2882 return true; 2883 } 2884 static bool handleLogicalOpForVector(const APFloat &LHSValue, 2885 BinaryOperatorKind Opcode, 2886 const APFloat &RHSValue, APInt &Result) { 2887 bool LHS = !LHSValue.isZero(); 2888 bool RHS = !RHSValue.isZero(); 2889 2890 if (Opcode == BO_LAnd) 2891 Result = LHS && RHS; 2892 else 2893 Result = LHS || RHS; 2894 return true; 2895 } 2896 2897 static bool handleLogicalOpForVector(const APValue &LHSValue, 2898 BinaryOperatorKind Opcode, 2899 const APValue &RHSValue, APInt &Result) { 2900 // The result is always an int type, however operands match the first. 2901 if (LHSValue.getKind() == APValue::Int) 2902 return handleLogicalOpForVector(LHSValue.getInt(), Opcode, 2903 RHSValue.getInt(), Result); 2904 assert(LHSValue.getKind() == APValue::Float && "Should be no other options"); 2905 return handleLogicalOpForVector(LHSValue.getFloat(), Opcode, 2906 RHSValue.getFloat(), Result); 2907 } 2908 2909 template <typename APTy> 2910 static bool 2911 handleCompareOpForVectorHelper(const APTy &LHSValue, BinaryOperatorKind Opcode, 2912 const APTy &RHSValue, APInt &Result) { 2913 switch (Opcode) { 2914 default: 2915 llvm_unreachable("unsupported binary operator"); 2916 case BO_EQ: 2917 Result = (LHSValue == RHSValue); 2918 break; 2919 case BO_NE: 2920 Result = (LHSValue != RHSValue); 2921 break; 2922 case BO_LT: 2923 Result = (LHSValue < RHSValue); 2924 break; 2925 case BO_GT: 2926 Result = (LHSValue > RHSValue); 2927 break; 2928 case BO_LE: 2929 Result = (LHSValue <= RHSValue); 2930 break; 2931 case BO_GE: 2932 Result = (LHSValue >= RHSValue); 2933 break; 2934 } 2935 2936 return true; 2937 } 2938 2939 static bool handleCompareOpForVector(const APValue &LHSValue, 2940 BinaryOperatorKind Opcode, 2941 const APValue &RHSValue, APInt &Result) { 2942 // The result is always an int type, however operands match the first. 2943 if (LHSValue.getKind() == APValue::Int) 2944 return handleCompareOpForVectorHelper(LHSValue.getInt(), Opcode, 2945 RHSValue.getInt(), Result); 2946 assert(LHSValue.getKind() == APValue::Float && "Should be no other options"); 2947 return handleCompareOpForVectorHelper(LHSValue.getFloat(), Opcode, 2948 RHSValue.getFloat(), Result); 2949 } 2950 2951 // Perform binary operations for vector types, in place on the LHS. 2952 static bool handleVectorVectorBinOp(EvalInfo &Info, const BinaryOperator *E, 2953 BinaryOperatorKind Opcode, 2954 APValue &LHSValue, 2955 const APValue &RHSValue) { 2956 assert(Opcode != BO_PtrMemD && Opcode != BO_PtrMemI && 2957 "Operation not supported on vector types"); 2958 2959 const auto *VT = E->getType()->castAs<VectorType>(); 2960 unsigned NumElements = VT->getNumElements(); 2961 QualType EltTy = VT->getElementType(); 2962 2963 // In the cases (typically C as I've observed) where we aren't evaluating 2964 // constexpr but are checking for cases where the LHS isn't yet evaluatable, 2965 // just give up. 2966 if (!LHSValue.isVector()) { 2967 assert(LHSValue.isLValue() && 2968 "A vector result that isn't a vector OR uncalculated LValue"); 2969 Info.FFDiag(E); 2970 return false; 2971 } 2972 2973 assert(LHSValue.getVectorLength() == NumElements && 2974 RHSValue.getVectorLength() == NumElements && "Different vector sizes"); 2975 2976 SmallVector<APValue, 4> ResultElements; 2977 2978 for (unsigned EltNum = 0; EltNum < NumElements; ++EltNum) { 2979 APValue LHSElt = LHSValue.getVectorElt(EltNum); 2980 APValue RHSElt = RHSValue.getVectorElt(EltNum); 2981 2982 if (EltTy->isIntegerType()) { 2983 APSInt EltResult{Info.Ctx.getIntWidth(EltTy), 2984 EltTy->isUnsignedIntegerType()}; 2985 bool Success = true; 2986 2987 if (BinaryOperator::isLogicalOp(Opcode)) 2988 Success = handleLogicalOpForVector(LHSElt, Opcode, RHSElt, EltResult); 2989 else if (BinaryOperator::isComparisonOp(Opcode)) 2990 Success = handleCompareOpForVector(LHSElt, Opcode, RHSElt, EltResult); 2991 else 2992 Success = handleIntIntBinOp(Info, E, LHSElt.getInt(), Opcode, 2993 RHSElt.getInt(), EltResult); 2994 2995 if (!Success) { 2996 Info.FFDiag(E); 2997 return false; 2998 } 2999 ResultElements.emplace_back(EltResult); 3000 3001 } else if (EltTy->isFloatingType()) { 3002 assert(LHSElt.getKind() == APValue::Float && 3003 RHSElt.getKind() == APValue::Float && 3004 "Mismatched LHS/RHS/Result Type"); 3005 APFloat LHSFloat = LHSElt.getFloat(); 3006 3007 if (!handleFloatFloatBinOp(Info, E, LHSFloat, Opcode, 3008 RHSElt.getFloat())) { 3009 Info.FFDiag(E); 3010 return false; 3011 } 3012 3013 ResultElements.emplace_back(LHSFloat); 3014 } 3015 } 3016 3017 LHSValue = APValue(ResultElements.data(), ResultElements.size()); 3018 return true; 3019 } 3020 3021 /// Cast an lvalue referring to a base subobject to a derived class, by 3022 /// truncating the lvalue's path to the given length. 3023 static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result, 3024 const RecordDecl *TruncatedType, 3025 unsigned TruncatedElements) { 3026 SubobjectDesignator &D = Result.Designator; 3027 3028 // Check we actually point to a derived class object. 3029 if (TruncatedElements == D.Entries.size()) 3030 return true; 3031 assert(TruncatedElements >= D.MostDerivedPathLength && 3032 "not casting to a derived class"); 3033 if (!Result.checkSubobject(Info, E, CSK_Derived)) 3034 return false; 3035 3036 // Truncate the path to the subobject, and remove any derived-to-base offsets. 3037 const RecordDecl *RD = TruncatedType; 3038 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) { 3039 if (RD->isInvalidDecl()) return false; 3040 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 3041 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]); 3042 if (isVirtualBaseClass(D.Entries[I])) 3043 Result.Offset -= Layout.getVBaseClassOffset(Base); 3044 else 3045 Result.Offset -= Layout.getBaseClassOffset(Base); 3046 RD = Base; 3047 } 3048 D.Entries.resize(TruncatedElements); 3049 return true; 3050 } 3051 3052 static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj, 3053 const CXXRecordDecl *Derived, 3054 const CXXRecordDecl *Base, 3055 const ASTRecordLayout *RL = nullptr) { 3056 if (!RL) { 3057 if (Derived->isInvalidDecl()) return false; 3058 RL = &Info.Ctx.getASTRecordLayout(Derived); 3059 } 3060 3061 Obj.getLValueOffset() += RL->getBaseClassOffset(Base); 3062 Obj.addDecl(Info, E, Base, /*Virtual*/ false); 3063 return true; 3064 } 3065 3066 static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj, 3067 const CXXRecordDecl *DerivedDecl, 3068 const CXXBaseSpecifier *Base) { 3069 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl(); 3070 3071 if (!Base->isVirtual()) 3072 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl); 3073 3074 SubobjectDesignator &D = Obj.Designator; 3075 if (D.Invalid) 3076 return false; 3077 3078 // Extract most-derived object and corresponding type. 3079 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl(); 3080 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength)) 3081 return false; 3082 3083 // Find the virtual base class. 3084 if (DerivedDecl->isInvalidDecl()) return false; 3085 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl); 3086 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl); 3087 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true); 3088 return true; 3089 } 3090 3091 static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E, 3092 QualType Type, LValue &Result) { 3093 for (CastExpr::path_const_iterator PathI = E->path_begin(), 3094 PathE = E->path_end(); 3095 PathI != PathE; ++PathI) { 3096 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(), 3097 *PathI)) 3098 return false; 3099 Type = (*PathI)->getType(); 3100 } 3101 return true; 3102 } 3103 3104 /// Cast an lvalue referring to a derived class to a known base subobject. 3105 static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result, 3106 const CXXRecordDecl *DerivedRD, 3107 const CXXRecordDecl *BaseRD) { 3108 CXXBasePaths Paths(/*FindAmbiguities=*/false, 3109 /*RecordPaths=*/true, /*DetectVirtual=*/false); 3110 if (!DerivedRD->isDerivedFrom(BaseRD, Paths)) 3111 llvm_unreachable("Class must be derived from the passed in base class!"); 3112 3113 for (CXXBasePathElement &Elem : Paths.front()) 3114 if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base)) 3115 return false; 3116 return true; 3117 } 3118 3119 /// Update LVal to refer to the given field, which must be a member of the type 3120 /// currently described by LVal. 3121 static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal, 3122 const FieldDecl *FD, 3123 const ASTRecordLayout *RL = nullptr) { 3124 if (!RL) { 3125 if (FD->getParent()->isInvalidDecl()) return false; 3126 RL = &Info.Ctx.getASTRecordLayout(FD->getParent()); 3127 } 3128 3129 unsigned I = FD->getFieldIndex(); 3130 LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I))); 3131 LVal.addDecl(Info, E, FD); 3132 return true; 3133 } 3134 3135 /// Update LVal to refer to the given indirect field. 3136 static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E, 3137 LValue &LVal, 3138 const IndirectFieldDecl *IFD) { 3139 for (const auto *C : IFD->chain()) 3140 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C))) 3141 return false; 3142 return true; 3143 } 3144 3145 /// Get the size of the given type in char units. 3146 static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc, 3147 QualType Type, CharUnits &Size) { 3148 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc 3149 // extension. 3150 if (Type->isVoidType() || Type->isFunctionType()) { 3151 Size = CharUnits::One(); 3152 return true; 3153 } 3154 3155 if (Type->isDependentType()) { 3156 Info.FFDiag(Loc); 3157 return false; 3158 } 3159 3160 if (!Type->isConstantSizeType()) { 3161 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2. 3162 // FIXME: Better diagnostic. 3163 Info.FFDiag(Loc); 3164 return false; 3165 } 3166 3167 Size = Info.Ctx.getTypeSizeInChars(Type); 3168 return true; 3169 } 3170 3171 /// Update a pointer value to model pointer arithmetic. 3172 /// \param Info - Information about the ongoing evaluation. 3173 /// \param E - The expression being evaluated, for diagnostic purposes. 3174 /// \param LVal - The pointer value to be updated. 3175 /// \param EltTy - The pointee type represented by LVal. 3176 /// \param Adjustment - The adjustment, in objects of type EltTy, to add. 3177 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E, 3178 LValue &LVal, QualType EltTy, 3179 APSInt Adjustment) { 3180 CharUnits SizeOfPointee; 3181 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee)) 3182 return false; 3183 3184 LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee); 3185 return true; 3186 } 3187 3188 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E, 3189 LValue &LVal, QualType EltTy, 3190 int64_t Adjustment) { 3191 return HandleLValueArrayAdjustment(Info, E, LVal, EltTy, 3192 APSInt::get(Adjustment)); 3193 } 3194 3195 /// Update an lvalue to refer to a component of a complex number. 3196 /// \param Info - Information about the ongoing evaluation. 3197 /// \param LVal - The lvalue to be updated. 3198 /// \param EltTy - The complex number's component type. 3199 /// \param Imag - False for the real component, true for the imaginary. 3200 static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E, 3201 LValue &LVal, QualType EltTy, 3202 bool Imag) { 3203 if (Imag) { 3204 CharUnits SizeOfComponent; 3205 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent)) 3206 return false; 3207 LVal.Offset += SizeOfComponent; 3208 } 3209 LVal.addComplex(Info, E, EltTy, Imag); 3210 return true; 3211 } 3212 3213 /// Try to evaluate the initializer for a variable declaration. 3214 /// 3215 /// \param Info Information about the ongoing evaluation. 3216 /// \param E An expression to be used when printing diagnostics. 3217 /// \param VD The variable whose initializer should be obtained. 3218 /// \param Version The version of the variable within the frame. 3219 /// \param Frame The frame in which the variable was created. Must be null 3220 /// if this variable is not local to the evaluation. 3221 /// \param Result Filled in with a pointer to the value of the variable. 3222 static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E, 3223 const VarDecl *VD, CallStackFrame *Frame, 3224 unsigned Version, APValue *&Result) { 3225 APValue::LValueBase Base(VD, Frame ? Frame->Index : 0, Version); 3226 3227 // If this is a local variable, dig out its value. 3228 if (Frame) { 3229 Result = Frame->getTemporary(VD, Version); 3230 if (Result) 3231 return true; 3232 3233 if (!isa<ParmVarDecl>(VD)) { 3234 // Assume variables referenced within a lambda's call operator that were 3235 // not declared within the call operator are captures and during checking 3236 // of a potential constant expression, assume they are unknown constant 3237 // expressions. 3238 assert(isLambdaCallOperator(Frame->Callee) && 3239 (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && 3240 "missing value for local variable"); 3241 if (Info.checkingPotentialConstantExpression()) 3242 return false; 3243 // FIXME: This diagnostic is bogus; we do support captures. Is this code 3244 // still reachable at all? 3245 Info.FFDiag(E->getBeginLoc(), 3246 diag::note_unimplemented_constexpr_lambda_feature_ast) 3247 << "captures not currently allowed"; 3248 return false; 3249 } 3250 } 3251 3252 // If we're currently evaluating the initializer of this declaration, use that 3253 // in-flight value. 3254 if (Info.EvaluatingDecl == Base) { 3255 Result = Info.EvaluatingDeclValue; 3256 return true; 3257 } 3258 3259 if (isa<ParmVarDecl>(VD)) { 3260 // Assume parameters of a potential constant expression are usable in 3261 // constant expressions. 3262 if (!Info.checkingPotentialConstantExpression() || 3263 !Info.CurrentCall->Callee || 3264 !Info.CurrentCall->Callee->Equals(VD->getDeclContext())) { 3265 if (Info.getLangOpts().CPlusPlus11) { 3266 Info.FFDiag(E, diag::note_constexpr_function_param_value_unknown) 3267 << VD; 3268 NoteLValueLocation(Info, Base); 3269 } else { 3270 Info.FFDiag(E); 3271 } 3272 } 3273 return false; 3274 } 3275 3276 // Dig out the initializer, and use the declaration which it's attached to. 3277 // FIXME: We should eventually check whether the variable has a reachable 3278 // initializing declaration. 3279 const Expr *Init = VD->getAnyInitializer(VD); 3280 if (!Init) { 3281 // Don't diagnose during potential constant expression checking; an 3282 // initializer might be added later. 3283 if (!Info.checkingPotentialConstantExpression()) { 3284 Info.FFDiag(E, diag::note_constexpr_var_init_unknown, 1) 3285 << VD; 3286 NoteLValueLocation(Info, Base); 3287 } 3288 return false; 3289 } 3290 3291 if (Init->isValueDependent()) { 3292 // The DeclRefExpr is not value-dependent, but the variable it refers to 3293 // has a value-dependent initializer. This should only happen in 3294 // constant-folding cases, where the variable is not actually of a suitable 3295 // type for use in a constant expression (otherwise the DeclRefExpr would 3296 // have been value-dependent too), so diagnose that. 3297 assert(!VD->mightBeUsableInConstantExpressions(Info.Ctx)); 3298 if (!Info.checkingPotentialConstantExpression()) { 3299 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11 3300 ? diag::note_constexpr_ltor_non_constexpr 3301 : diag::note_constexpr_ltor_non_integral, 1) 3302 << VD << VD->getType(); 3303 NoteLValueLocation(Info, Base); 3304 } 3305 return false; 3306 } 3307 3308 // Check that we can fold the initializer. In C++, we will have already done 3309 // this in the cases where it matters for conformance. 3310 SmallVector<PartialDiagnosticAt, 8> Notes; 3311 if (!VD->evaluateValue(Notes)) { 3312 Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, 3313 Notes.size() + 1) << VD; 3314 NoteLValueLocation(Info, Base); 3315 Info.addNotes(Notes); 3316 return false; 3317 } 3318 3319 // Check that the variable is actually usable in constant expressions. For a 3320 // const integral variable or a reference, we might have a non-constant 3321 // initializer that we can nonetheless evaluate the initializer for. Such 3322 // variables are not usable in constant expressions. In C++98, the 3323 // initializer also syntactically needs to be an ICE. 3324 // 3325 // FIXME: We don't diagnose cases that aren't potentially usable in constant 3326 // expressions here; doing so would regress diagnostics for things like 3327 // reading from a volatile constexpr variable. 3328 if ((Info.getLangOpts().CPlusPlus && !VD->hasConstantInitialization() && 3329 VD->mightBeUsableInConstantExpressions(Info.Ctx)) || 3330 ((Info.getLangOpts().CPlusPlus || Info.getLangOpts().OpenCL) && 3331 !Info.getLangOpts().CPlusPlus11 && !VD->hasICEInitializer(Info.Ctx))) { 3332 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 1) << VD; 3333 NoteLValueLocation(Info, Base); 3334 } 3335 3336 // Never use the initializer of a weak variable, not even for constant 3337 // folding. We can't be sure that this is the definition that will be used. 3338 if (VD->isWeak()) { 3339 Info.FFDiag(E, diag::note_constexpr_var_init_weak) << VD; 3340 NoteLValueLocation(Info, Base); 3341 return false; 3342 } 3343 3344 Result = VD->getEvaluatedValue(); 3345 return true; 3346 } 3347 3348 /// Get the base index of the given base class within an APValue representing 3349 /// the given derived class. 3350 static unsigned getBaseIndex(const CXXRecordDecl *Derived, 3351 const CXXRecordDecl *Base) { 3352 Base = Base->getCanonicalDecl(); 3353 unsigned Index = 0; 3354 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(), 3355 E = Derived->bases_end(); I != E; ++I, ++Index) { 3356 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base) 3357 return Index; 3358 } 3359 3360 llvm_unreachable("base class missing from derived class's bases list"); 3361 } 3362 3363 /// Extract the value of a character from a string literal. 3364 static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit, 3365 uint64_t Index) { 3366 assert(!isa<SourceLocExpr>(Lit) && 3367 "SourceLocExpr should have already been converted to a StringLiteral"); 3368 3369 // FIXME: Support MakeStringConstant 3370 if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) { 3371 std::string Str; 3372 Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str); 3373 assert(Index <= Str.size() && "Index too large"); 3374 return APSInt::getUnsigned(Str.c_str()[Index]); 3375 } 3376 3377 if (auto PE = dyn_cast<PredefinedExpr>(Lit)) 3378 Lit = PE->getFunctionName(); 3379 const StringLiteral *S = cast<StringLiteral>(Lit); 3380 const ConstantArrayType *CAT = 3381 Info.Ctx.getAsConstantArrayType(S->getType()); 3382 assert(CAT && "string literal isn't an array"); 3383 QualType CharType = CAT->getElementType(); 3384 assert(CharType->isIntegerType() && "unexpected character type"); 3385 3386 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), 3387 CharType->isUnsignedIntegerType()); 3388 if (Index < S->getLength()) 3389 Value = S->getCodeUnit(Index); 3390 return Value; 3391 } 3392 3393 // Expand a string literal into an array of characters. 3394 // 3395 // FIXME: This is inefficient; we should probably introduce something similar 3396 // to the LLVM ConstantDataArray to make this cheaper. 3397 static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S, 3398 APValue &Result, 3399 QualType AllocType = QualType()) { 3400 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType( 3401 AllocType.isNull() ? S->getType() : AllocType); 3402 assert(CAT && "string literal isn't an array"); 3403 QualType CharType = CAT->getElementType(); 3404 assert(CharType->isIntegerType() && "unexpected character type"); 3405 3406 unsigned Elts = CAT->getSize().getZExtValue(); 3407 Result = APValue(APValue::UninitArray(), 3408 std::min(S->getLength(), Elts), Elts); 3409 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), 3410 CharType->isUnsignedIntegerType()); 3411 if (Result.hasArrayFiller()) 3412 Result.getArrayFiller() = APValue(Value); 3413 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) { 3414 Value = S->getCodeUnit(I); 3415 Result.getArrayInitializedElt(I) = APValue(Value); 3416 } 3417 } 3418 3419 // Expand an array so that it has more than Index filled elements. 3420 static void expandArray(APValue &Array, unsigned Index) { 3421 unsigned Size = Array.getArraySize(); 3422 assert(Index < Size); 3423 3424 // Always at least double the number of elements for which we store a value. 3425 unsigned OldElts = Array.getArrayInitializedElts(); 3426 unsigned NewElts = std::max(Index+1, OldElts * 2); 3427 NewElts = std::min(Size, std::max(NewElts, 8u)); 3428 3429 // Copy the data across. 3430 APValue NewValue(APValue::UninitArray(), NewElts, Size); 3431 for (unsigned I = 0; I != OldElts; ++I) 3432 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I)); 3433 for (unsigned I = OldElts; I != NewElts; ++I) 3434 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller(); 3435 if (NewValue.hasArrayFiller()) 3436 NewValue.getArrayFiller() = Array.getArrayFiller(); 3437 Array.swap(NewValue); 3438 } 3439 3440 /// Determine whether a type would actually be read by an lvalue-to-rvalue 3441 /// conversion. If it's of class type, we may assume that the copy operation 3442 /// is trivial. Note that this is never true for a union type with fields 3443 /// (because the copy always "reads" the active member) and always true for 3444 /// a non-class type. 3445 static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD); 3446 static bool isReadByLvalueToRvalueConversion(QualType T) { 3447 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); 3448 return !RD || isReadByLvalueToRvalueConversion(RD); 3449 } 3450 static bool isReadByLvalueToRvalueConversion(const CXXRecordDecl *RD) { 3451 // FIXME: A trivial copy of a union copies the object representation, even if 3452 // the union is empty. 3453 if (RD->isUnion()) 3454 return !RD->field_empty(); 3455 if (RD->isEmpty()) 3456 return false; 3457 3458 for (auto *Field : RD->fields()) 3459 if (!Field->isUnnamedBitfield() && 3460 isReadByLvalueToRvalueConversion(Field->getType())) 3461 return true; 3462 3463 for (auto &BaseSpec : RD->bases()) 3464 if (isReadByLvalueToRvalueConversion(BaseSpec.getType())) 3465 return true; 3466 3467 return false; 3468 } 3469 3470 /// Diagnose an attempt to read from any unreadable field within the specified 3471 /// type, which might be a class type. 3472 static bool diagnoseMutableFields(EvalInfo &Info, const Expr *E, AccessKinds AK, 3473 QualType T) { 3474 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); 3475 if (!RD) 3476 return false; 3477 3478 if (!RD->hasMutableFields()) 3479 return false; 3480 3481 for (auto *Field : RD->fields()) { 3482 // If we're actually going to read this field in some way, then it can't 3483 // be mutable. If we're in a union, then assigning to a mutable field 3484 // (even an empty one) can change the active member, so that's not OK. 3485 // FIXME: Add core issue number for the union case. 3486 if (Field->isMutable() && 3487 (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) { 3488 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) << AK << Field; 3489 Info.Note(Field->getLocation(), diag::note_declared_at); 3490 return true; 3491 } 3492 3493 if (diagnoseMutableFields(Info, E, AK, Field->getType())) 3494 return true; 3495 } 3496 3497 for (auto &BaseSpec : RD->bases()) 3498 if (diagnoseMutableFields(Info, E, AK, BaseSpec.getType())) 3499 return true; 3500 3501 // All mutable fields were empty, and thus not actually read. 3502 return false; 3503 } 3504 3505 static bool lifetimeStartedInEvaluation(EvalInfo &Info, 3506 APValue::LValueBase Base, 3507 bool MutableSubobject = false) { 3508 // A temporary or transient heap allocation we created. 3509 if (Base.getCallIndex() || Base.is<DynamicAllocLValue>()) 3510 return true; 3511 3512 switch (Info.IsEvaluatingDecl) { 3513 case EvalInfo::EvaluatingDeclKind::None: 3514 return false; 3515 3516 case EvalInfo::EvaluatingDeclKind::Ctor: 3517 // The variable whose initializer we're evaluating. 3518 if (Info.EvaluatingDecl == Base) 3519 return true; 3520 3521 // A temporary lifetime-extended by the variable whose initializer we're 3522 // evaluating. 3523 if (auto *BaseE = Base.dyn_cast<const Expr *>()) 3524 if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE)) 3525 return Info.EvaluatingDecl == BaseMTE->getExtendingDecl(); 3526 return false; 3527 3528 case EvalInfo::EvaluatingDeclKind::Dtor: 3529 // C++2a [expr.const]p6: 3530 // [during constant destruction] the lifetime of a and its non-mutable 3531 // subobjects (but not its mutable subobjects) [are] considered to start 3532 // within e. 3533 if (MutableSubobject || Base != Info.EvaluatingDecl) 3534 return false; 3535 // FIXME: We can meaningfully extend this to cover non-const objects, but 3536 // we will need special handling: we should be able to access only 3537 // subobjects of such objects that are themselves declared const. 3538 QualType T = getType(Base); 3539 return T.isConstQualified() || T->isReferenceType(); 3540 } 3541 3542 llvm_unreachable("unknown evaluating decl kind"); 3543 } 3544 3545 namespace { 3546 /// A handle to a complete object (an object that is not a subobject of 3547 /// another object). 3548 struct CompleteObject { 3549 /// The identity of the object. 3550 APValue::LValueBase Base; 3551 /// The value of the complete object. 3552 APValue *Value; 3553 /// The type of the complete object. 3554 QualType Type; 3555 3556 CompleteObject() : Value(nullptr) {} 3557 CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type) 3558 : Base(Base), Value(Value), Type(Type) {} 3559 3560 bool mayAccessMutableMembers(EvalInfo &Info, AccessKinds AK) const { 3561 // If this isn't a "real" access (eg, if it's just accessing the type 3562 // info), allow it. We assume the type doesn't change dynamically for 3563 // subobjects of constexpr objects (even though we'd hit UB here if it 3564 // did). FIXME: Is this right? 3565 if (!isAnyAccess(AK)) 3566 return true; 3567 3568 // In C++14 onwards, it is permitted to read a mutable member whose 3569 // lifetime began within the evaluation. 3570 // FIXME: Should we also allow this in C++11? 3571 if (!Info.getLangOpts().CPlusPlus14) 3572 return false; 3573 return lifetimeStartedInEvaluation(Info, Base, /*MutableSubobject*/true); 3574 } 3575 3576 explicit operator bool() const { return !Type.isNull(); } 3577 }; 3578 } // end anonymous namespace 3579 3580 static QualType getSubobjectType(QualType ObjType, QualType SubobjType, 3581 bool IsMutable = false) { 3582 // C++ [basic.type.qualifier]p1: 3583 // - A const object is an object of type const T or a non-mutable subobject 3584 // of a const object. 3585 if (ObjType.isConstQualified() && !IsMutable) 3586 SubobjType.addConst(); 3587 // - A volatile object is an object of type const T or a subobject of a 3588 // volatile object. 3589 if (ObjType.isVolatileQualified()) 3590 SubobjType.addVolatile(); 3591 return SubobjType; 3592 } 3593 3594 /// Find the designated sub-object of an rvalue. 3595 template<typename SubobjectHandler> 3596 typename SubobjectHandler::result_type 3597 findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj, 3598 const SubobjectDesignator &Sub, SubobjectHandler &handler) { 3599 if (Sub.Invalid) 3600 // A diagnostic will have already been produced. 3601 return handler.failed(); 3602 if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) { 3603 if (Info.getLangOpts().CPlusPlus11) 3604 Info.FFDiag(E, Sub.isOnePastTheEnd() 3605 ? diag::note_constexpr_access_past_end 3606 : diag::note_constexpr_access_unsized_array) 3607 << handler.AccessKind; 3608 else 3609 Info.FFDiag(E); 3610 return handler.failed(); 3611 } 3612 3613 APValue *O = Obj.Value; 3614 QualType ObjType = Obj.Type; 3615 const FieldDecl *LastField = nullptr; 3616 const FieldDecl *VolatileField = nullptr; 3617 3618 // Walk the designator's path to find the subobject. 3619 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) { 3620 // Reading an indeterminate value is undefined, but assigning over one is OK. 3621 if ((O->isAbsent() && !(handler.AccessKind == AK_Construct && I == N)) || 3622 (O->isIndeterminate() && 3623 !isValidIndeterminateAccess(handler.AccessKind))) { 3624 if (!Info.checkingPotentialConstantExpression()) 3625 Info.FFDiag(E, diag::note_constexpr_access_uninit) 3626 << handler.AccessKind << O->isIndeterminate(); 3627 return handler.failed(); 3628 } 3629 3630 // C++ [class.ctor]p5, C++ [class.dtor]p5: 3631 // const and volatile semantics are not applied on an object under 3632 // {con,de}struction. 3633 if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) && 3634 ObjType->isRecordType() && 3635 Info.isEvaluatingCtorDtor( 3636 Obj.Base, llvm::makeArrayRef(Sub.Entries.begin(), 3637 Sub.Entries.begin() + I)) != 3638 ConstructionPhase::None) { 3639 ObjType = Info.Ctx.getCanonicalType(ObjType); 3640 ObjType.removeLocalConst(); 3641 ObjType.removeLocalVolatile(); 3642 } 3643 3644 // If this is our last pass, check that the final object type is OK. 3645 if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) { 3646 // Accesses to volatile objects are prohibited. 3647 if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) { 3648 if (Info.getLangOpts().CPlusPlus) { 3649 int DiagKind; 3650 SourceLocation Loc; 3651 const NamedDecl *Decl = nullptr; 3652 if (VolatileField) { 3653 DiagKind = 2; 3654 Loc = VolatileField->getLocation(); 3655 Decl = VolatileField; 3656 } else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) { 3657 DiagKind = 1; 3658 Loc = VD->getLocation(); 3659 Decl = VD; 3660 } else { 3661 DiagKind = 0; 3662 if (auto *E = Obj.Base.dyn_cast<const Expr *>()) 3663 Loc = E->getExprLoc(); 3664 } 3665 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1) 3666 << handler.AccessKind << DiagKind << Decl; 3667 Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind; 3668 } else { 3669 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 3670 } 3671 return handler.failed(); 3672 } 3673 3674 // If we are reading an object of class type, there may still be more 3675 // things we need to check: if there are any mutable subobjects, we 3676 // cannot perform this read. (This only happens when performing a trivial 3677 // copy or assignment.) 3678 if (ObjType->isRecordType() && 3679 !Obj.mayAccessMutableMembers(Info, handler.AccessKind) && 3680 diagnoseMutableFields(Info, E, handler.AccessKind, ObjType)) 3681 return handler.failed(); 3682 } 3683 3684 if (I == N) { 3685 if (!handler.found(*O, ObjType)) 3686 return false; 3687 3688 // If we modified a bit-field, truncate it to the right width. 3689 if (isModification(handler.AccessKind) && 3690 LastField && LastField->isBitField() && 3691 !truncateBitfieldValue(Info, E, *O, LastField)) 3692 return false; 3693 3694 return true; 3695 } 3696 3697 LastField = nullptr; 3698 if (ObjType->isArrayType()) { 3699 // Next subobject is an array element. 3700 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType); 3701 assert(CAT && "vla in literal type?"); 3702 uint64_t Index = Sub.Entries[I].getAsArrayIndex(); 3703 if (CAT->getSize().ule(Index)) { 3704 // Note, it should not be possible to form a pointer with a valid 3705 // designator which points more than one past the end of the array. 3706 if (Info.getLangOpts().CPlusPlus11) 3707 Info.FFDiag(E, diag::note_constexpr_access_past_end) 3708 << handler.AccessKind; 3709 else 3710 Info.FFDiag(E); 3711 return handler.failed(); 3712 } 3713 3714 ObjType = CAT->getElementType(); 3715 3716 if (O->getArrayInitializedElts() > Index) 3717 O = &O->getArrayInitializedElt(Index); 3718 else if (!isRead(handler.AccessKind)) { 3719 expandArray(*O, Index); 3720 O = &O->getArrayInitializedElt(Index); 3721 } else 3722 O = &O->getArrayFiller(); 3723 } else if (ObjType->isAnyComplexType()) { 3724 // Next subobject is a complex number. 3725 uint64_t Index = Sub.Entries[I].getAsArrayIndex(); 3726 if (Index > 1) { 3727 if (Info.getLangOpts().CPlusPlus11) 3728 Info.FFDiag(E, diag::note_constexpr_access_past_end) 3729 << handler.AccessKind; 3730 else 3731 Info.FFDiag(E); 3732 return handler.failed(); 3733 } 3734 3735 ObjType = getSubobjectType( 3736 ObjType, ObjType->castAs<ComplexType>()->getElementType()); 3737 3738 assert(I == N - 1 && "extracting subobject of scalar?"); 3739 if (O->isComplexInt()) { 3740 return handler.found(Index ? O->getComplexIntImag() 3741 : O->getComplexIntReal(), ObjType); 3742 } else { 3743 assert(O->isComplexFloat()); 3744 return handler.found(Index ? O->getComplexFloatImag() 3745 : O->getComplexFloatReal(), ObjType); 3746 } 3747 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) { 3748 if (Field->isMutable() && 3749 !Obj.mayAccessMutableMembers(Info, handler.AccessKind)) { 3750 Info.FFDiag(E, diag::note_constexpr_access_mutable, 1) 3751 << handler.AccessKind << Field; 3752 Info.Note(Field->getLocation(), diag::note_declared_at); 3753 return handler.failed(); 3754 } 3755 3756 // Next subobject is a class, struct or union field. 3757 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl(); 3758 if (RD->isUnion()) { 3759 const FieldDecl *UnionField = O->getUnionField(); 3760 if (!UnionField || 3761 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) { 3762 if (I == N - 1 && handler.AccessKind == AK_Construct) { 3763 // Placement new onto an inactive union member makes it active. 3764 O->setUnion(Field, APValue()); 3765 } else { 3766 // FIXME: If O->getUnionValue() is absent, report that there's no 3767 // active union member rather than reporting the prior active union 3768 // member. We'll need to fix nullptr_t to not use APValue() as its 3769 // representation first. 3770 Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member) 3771 << handler.AccessKind << Field << !UnionField << UnionField; 3772 return handler.failed(); 3773 } 3774 } 3775 O = &O->getUnionValue(); 3776 } else 3777 O = &O->getStructField(Field->getFieldIndex()); 3778 3779 ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable()); 3780 LastField = Field; 3781 if (Field->getType().isVolatileQualified()) 3782 VolatileField = Field; 3783 } else { 3784 // Next subobject is a base class. 3785 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl(); 3786 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]); 3787 O = &O->getStructBase(getBaseIndex(Derived, Base)); 3788 3789 ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base)); 3790 } 3791 } 3792 } 3793 3794 namespace { 3795 struct ExtractSubobjectHandler { 3796 EvalInfo &Info; 3797 const Expr *E; 3798 APValue &Result; 3799 const AccessKinds AccessKind; 3800 3801 typedef bool result_type; 3802 bool failed() { return false; } 3803 bool found(APValue &Subobj, QualType SubobjType) { 3804 Result = Subobj; 3805 if (AccessKind == AK_ReadObjectRepresentation) 3806 return true; 3807 return CheckFullyInitialized(Info, E->getExprLoc(), SubobjType, Result); 3808 } 3809 bool found(APSInt &Value, QualType SubobjType) { 3810 Result = APValue(Value); 3811 return true; 3812 } 3813 bool found(APFloat &Value, QualType SubobjType) { 3814 Result = APValue(Value); 3815 return true; 3816 } 3817 }; 3818 } // end anonymous namespace 3819 3820 /// Extract the designated sub-object of an rvalue. 3821 static bool extractSubobject(EvalInfo &Info, const Expr *E, 3822 const CompleteObject &Obj, 3823 const SubobjectDesignator &Sub, APValue &Result, 3824 AccessKinds AK = AK_Read) { 3825 assert(AK == AK_Read || AK == AK_ReadObjectRepresentation); 3826 ExtractSubobjectHandler Handler = {Info, E, Result, AK}; 3827 return findSubobject(Info, E, Obj, Sub, Handler); 3828 } 3829 3830 namespace { 3831 struct ModifySubobjectHandler { 3832 EvalInfo &Info; 3833 APValue &NewVal; 3834 const Expr *E; 3835 3836 typedef bool result_type; 3837 static const AccessKinds AccessKind = AK_Assign; 3838 3839 bool checkConst(QualType QT) { 3840 // Assigning to a const object has undefined behavior. 3841 if (QT.isConstQualified()) { 3842 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; 3843 return false; 3844 } 3845 return true; 3846 } 3847 3848 bool failed() { return false; } 3849 bool found(APValue &Subobj, QualType SubobjType) { 3850 if (!checkConst(SubobjType)) 3851 return false; 3852 // We've been given ownership of NewVal, so just swap it in. 3853 Subobj.swap(NewVal); 3854 return true; 3855 } 3856 bool found(APSInt &Value, QualType SubobjType) { 3857 if (!checkConst(SubobjType)) 3858 return false; 3859 if (!NewVal.isInt()) { 3860 // Maybe trying to write a cast pointer value into a complex? 3861 Info.FFDiag(E); 3862 return false; 3863 } 3864 Value = NewVal.getInt(); 3865 return true; 3866 } 3867 bool found(APFloat &Value, QualType SubobjType) { 3868 if (!checkConst(SubobjType)) 3869 return false; 3870 Value = NewVal.getFloat(); 3871 return true; 3872 } 3873 }; 3874 } // end anonymous namespace 3875 3876 const AccessKinds ModifySubobjectHandler::AccessKind; 3877 3878 /// Update the designated sub-object of an rvalue to the given value. 3879 static bool modifySubobject(EvalInfo &Info, const Expr *E, 3880 const CompleteObject &Obj, 3881 const SubobjectDesignator &Sub, 3882 APValue &NewVal) { 3883 ModifySubobjectHandler Handler = { Info, NewVal, E }; 3884 return findSubobject(Info, E, Obj, Sub, Handler); 3885 } 3886 3887 /// Find the position where two subobject designators diverge, or equivalently 3888 /// the length of the common initial subsequence. 3889 static unsigned FindDesignatorMismatch(QualType ObjType, 3890 const SubobjectDesignator &A, 3891 const SubobjectDesignator &B, 3892 bool &WasArrayIndex) { 3893 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size()); 3894 for (/**/; I != N; ++I) { 3895 if (!ObjType.isNull() && 3896 (ObjType->isArrayType() || ObjType->isAnyComplexType())) { 3897 // Next subobject is an array element. 3898 if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) { 3899 WasArrayIndex = true; 3900 return I; 3901 } 3902 if (ObjType->isAnyComplexType()) 3903 ObjType = ObjType->castAs<ComplexType>()->getElementType(); 3904 else 3905 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType(); 3906 } else { 3907 if (A.Entries[I].getAsBaseOrMember() != 3908 B.Entries[I].getAsBaseOrMember()) { 3909 WasArrayIndex = false; 3910 return I; 3911 } 3912 if (const FieldDecl *FD = getAsField(A.Entries[I])) 3913 // Next subobject is a field. 3914 ObjType = FD->getType(); 3915 else 3916 // Next subobject is a base class. 3917 ObjType = QualType(); 3918 } 3919 } 3920 WasArrayIndex = false; 3921 return I; 3922 } 3923 3924 /// Determine whether the given subobject designators refer to elements of the 3925 /// same array object. 3926 static bool AreElementsOfSameArray(QualType ObjType, 3927 const SubobjectDesignator &A, 3928 const SubobjectDesignator &B) { 3929 if (A.Entries.size() != B.Entries.size()) 3930 return false; 3931 3932 bool IsArray = A.MostDerivedIsArrayElement; 3933 if (IsArray && A.MostDerivedPathLength != A.Entries.size()) 3934 // A is a subobject of the array element. 3935 return false; 3936 3937 // If A (and B) designates an array element, the last entry will be the array 3938 // index. That doesn't have to match. Otherwise, we're in the 'implicit array 3939 // of length 1' case, and the entire path must match. 3940 bool WasArrayIndex; 3941 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex); 3942 return CommonLength >= A.Entries.size() - IsArray; 3943 } 3944 3945 /// Find the complete object to which an LValue refers. 3946 static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E, 3947 AccessKinds AK, const LValue &LVal, 3948 QualType LValType) { 3949 if (LVal.InvalidBase) { 3950 Info.FFDiag(E); 3951 return CompleteObject(); 3952 } 3953 3954 if (!LVal.Base) { 3955 Info.FFDiag(E, diag::note_constexpr_access_null) << AK; 3956 return CompleteObject(); 3957 } 3958 3959 CallStackFrame *Frame = nullptr; 3960 unsigned Depth = 0; 3961 if (LVal.getLValueCallIndex()) { 3962 std::tie(Frame, Depth) = 3963 Info.getCallFrameAndDepth(LVal.getLValueCallIndex()); 3964 if (!Frame) { 3965 Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1) 3966 << AK << LVal.Base.is<const ValueDecl*>(); 3967 NoteLValueLocation(Info, LVal.Base); 3968 return CompleteObject(); 3969 } 3970 } 3971 3972 bool IsAccess = isAnyAccess(AK); 3973 3974 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type 3975 // is not a constant expression (even if the object is non-volatile). We also 3976 // apply this rule to C++98, in order to conform to the expected 'volatile' 3977 // semantics. 3978 if (isFormalAccess(AK) && LValType.isVolatileQualified()) { 3979 if (Info.getLangOpts().CPlusPlus) 3980 Info.FFDiag(E, diag::note_constexpr_access_volatile_type) 3981 << AK << LValType; 3982 else 3983 Info.FFDiag(E); 3984 return CompleteObject(); 3985 } 3986 3987 // Compute value storage location and type of base object. 3988 APValue *BaseVal = nullptr; 3989 QualType BaseType = getType(LVal.Base); 3990 3991 if (Info.getLangOpts().CPlusPlus14 && LVal.Base == Info.EvaluatingDecl && 3992 lifetimeStartedInEvaluation(Info, LVal.Base)) { 3993 // This is the object whose initializer we're evaluating, so its lifetime 3994 // started in the current evaluation. 3995 BaseVal = Info.EvaluatingDeclValue; 3996 } else if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl *>()) { 3997 // Allow reading from a GUID declaration. 3998 if (auto *GD = dyn_cast<MSGuidDecl>(D)) { 3999 if (isModification(AK)) { 4000 // All the remaining cases do not permit modification of the object. 4001 Info.FFDiag(E, diag::note_constexpr_modify_global); 4002 return CompleteObject(); 4003 } 4004 APValue &V = GD->getAsAPValue(); 4005 if (V.isAbsent()) { 4006 Info.FFDiag(E, diag::note_constexpr_unsupported_layout) 4007 << GD->getType(); 4008 return CompleteObject(); 4009 } 4010 return CompleteObject(LVal.Base, &V, GD->getType()); 4011 } 4012 4013 // Allow reading from template parameter objects. 4014 if (auto *TPO = dyn_cast<TemplateParamObjectDecl>(D)) { 4015 if (isModification(AK)) { 4016 Info.FFDiag(E, diag::note_constexpr_modify_global); 4017 return CompleteObject(); 4018 } 4019 return CompleteObject(LVal.Base, const_cast<APValue *>(&TPO->getValue()), 4020 TPO->getType()); 4021 } 4022 4023 // In C++98, const, non-volatile integers initialized with ICEs are ICEs. 4024 // In C++11, constexpr, non-volatile variables initialized with constant 4025 // expressions are constant expressions too. Inside constexpr functions, 4026 // parameters are constant expressions even if they're non-const. 4027 // In C++1y, objects local to a constant expression (those with a Frame) are 4028 // both readable and writable inside constant expressions. 4029 // In C, such things can also be folded, although they are not ICEs. 4030 const VarDecl *VD = dyn_cast<VarDecl>(D); 4031 if (VD) { 4032 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx)) 4033 VD = VDef; 4034 } 4035 if (!VD || VD->isInvalidDecl()) { 4036 Info.FFDiag(E); 4037 return CompleteObject(); 4038 } 4039 4040 bool IsConstant = BaseType.isConstant(Info.Ctx); 4041 4042 // Unless we're looking at a local variable or argument in a constexpr call, 4043 // the variable we're reading must be const. 4044 if (!Frame) { 4045 if (IsAccess && isa<ParmVarDecl>(VD)) { 4046 // Access of a parameter that's not associated with a frame isn't going 4047 // to work out, but we can leave it to evaluateVarDeclInit to provide a 4048 // suitable diagnostic. 4049 } else if (Info.getLangOpts().CPlusPlus14 && 4050 lifetimeStartedInEvaluation(Info, LVal.Base)) { 4051 // OK, we can read and modify an object if we're in the process of 4052 // evaluating its initializer, because its lifetime began in this 4053 // evaluation. 4054 } else if (isModification(AK)) { 4055 // All the remaining cases do not permit modification of the object. 4056 Info.FFDiag(E, diag::note_constexpr_modify_global); 4057 return CompleteObject(); 4058 } else if (VD->isConstexpr()) { 4059 // OK, we can read this variable. 4060 } else if (BaseType->isIntegralOrEnumerationType()) { 4061 if (!IsConstant) { 4062 if (!IsAccess) 4063 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); 4064 if (Info.getLangOpts().CPlusPlus) { 4065 Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD; 4066 Info.Note(VD->getLocation(), diag::note_declared_at); 4067 } else { 4068 Info.FFDiag(E); 4069 } 4070 return CompleteObject(); 4071 } 4072 } else if (!IsAccess) { 4073 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); 4074 } else if (IsConstant && Info.checkingPotentialConstantExpression() && 4075 BaseType->isLiteralType(Info.Ctx) && !VD->hasDefinition()) { 4076 // This variable might end up being constexpr. Don't diagnose it yet. 4077 } else if (IsConstant) { 4078 // Keep evaluating to see what we can do. In particular, we support 4079 // folding of const floating-point types, in order to make static const 4080 // data members of such types (supported as an extension) more useful. 4081 if (Info.getLangOpts().CPlusPlus) { 4082 Info.CCEDiag(E, Info.getLangOpts().CPlusPlus11 4083 ? diag::note_constexpr_ltor_non_constexpr 4084 : diag::note_constexpr_ltor_non_integral, 1) 4085 << VD << BaseType; 4086 Info.Note(VD->getLocation(), diag::note_declared_at); 4087 } else { 4088 Info.CCEDiag(E); 4089 } 4090 } else { 4091 // Never allow reading a non-const value. 4092 if (Info.getLangOpts().CPlusPlus) { 4093 Info.FFDiag(E, Info.getLangOpts().CPlusPlus11 4094 ? diag::note_constexpr_ltor_non_constexpr 4095 : diag::note_constexpr_ltor_non_integral, 1) 4096 << VD << BaseType; 4097 Info.Note(VD->getLocation(), diag::note_declared_at); 4098 } else { 4099 Info.FFDiag(E); 4100 } 4101 return CompleteObject(); 4102 } 4103 } 4104 4105 if (!evaluateVarDeclInit(Info, E, VD, Frame, LVal.getLValueVersion(), BaseVal)) 4106 return CompleteObject(); 4107 } else if (DynamicAllocLValue DA = LVal.Base.dyn_cast<DynamicAllocLValue>()) { 4108 Optional<DynAlloc*> Alloc = Info.lookupDynamicAlloc(DA); 4109 if (!Alloc) { 4110 Info.FFDiag(E, diag::note_constexpr_access_deleted_object) << AK; 4111 return CompleteObject(); 4112 } 4113 return CompleteObject(LVal.Base, &(*Alloc)->Value, 4114 LVal.Base.getDynamicAllocType()); 4115 } else { 4116 const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); 4117 4118 if (!Frame) { 4119 if (const MaterializeTemporaryExpr *MTE = 4120 dyn_cast_or_null<MaterializeTemporaryExpr>(Base)) { 4121 assert(MTE->getStorageDuration() == SD_Static && 4122 "should have a frame for a non-global materialized temporary"); 4123 4124 // C++20 [expr.const]p4: [DR2126] 4125 // An object or reference is usable in constant expressions if it is 4126 // - a temporary object of non-volatile const-qualified literal type 4127 // whose lifetime is extended to that of a variable that is usable 4128 // in constant expressions 4129 // 4130 // C++20 [expr.const]p5: 4131 // an lvalue-to-rvalue conversion [is not allowed unless it applies to] 4132 // - a non-volatile glvalue that refers to an object that is usable 4133 // in constant expressions, or 4134 // - a non-volatile glvalue of literal type that refers to a 4135 // non-volatile object whose lifetime began within the evaluation 4136 // of E; 4137 // 4138 // C++11 misses the 'began within the evaluation of e' check and 4139 // instead allows all temporaries, including things like: 4140 // int &&r = 1; 4141 // int x = ++r; 4142 // constexpr int k = r; 4143 // Therefore we use the C++14-onwards rules in C++11 too. 4144 // 4145 // Note that temporaries whose lifetimes began while evaluating a 4146 // variable's constructor are not usable while evaluating the 4147 // corresponding destructor, not even if they're of const-qualified 4148 // types. 4149 if (!MTE->isUsableInConstantExpressions(Info.Ctx) && 4150 !lifetimeStartedInEvaluation(Info, LVal.Base)) { 4151 if (!IsAccess) 4152 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); 4153 Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK; 4154 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here); 4155 return CompleteObject(); 4156 } 4157 4158 BaseVal = MTE->getOrCreateValue(false); 4159 assert(BaseVal && "got reference to unevaluated temporary"); 4160 } else { 4161 if (!IsAccess) 4162 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); 4163 APValue Val; 4164 LVal.moveInto(Val); 4165 Info.FFDiag(E, diag::note_constexpr_access_unreadable_object) 4166 << AK 4167 << Val.getAsString(Info.Ctx, 4168 Info.Ctx.getLValueReferenceType(LValType)); 4169 NoteLValueLocation(Info, LVal.Base); 4170 return CompleteObject(); 4171 } 4172 } else { 4173 BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion()); 4174 assert(BaseVal && "missing value for temporary"); 4175 } 4176 } 4177 4178 // In C++14, we can't safely access any mutable state when we might be 4179 // evaluating after an unmodeled side effect. Parameters are modeled as state 4180 // in the caller, but aren't visible once the call returns, so they can be 4181 // modified in a speculatively-evaluated call. 4182 // 4183 // FIXME: Not all local state is mutable. Allow local constant subobjects 4184 // to be read here (but take care with 'mutable' fields). 4185 unsigned VisibleDepth = Depth; 4186 if (llvm::isa_and_nonnull<ParmVarDecl>( 4187 LVal.Base.dyn_cast<const ValueDecl *>())) 4188 ++VisibleDepth; 4189 if ((Frame && Info.getLangOpts().CPlusPlus14 && 4190 Info.EvalStatus.HasSideEffects) || 4191 (isModification(AK) && VisibleDepth < Info.SpeculativeEvaluationDepth)) 4192 return CompleteObject(); 4193 4194 return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType); 4195 } 4196 4197 /// Perform an lvalue-to-rvalue conversion on the given glvalue. This 4198 /// can also be used for 'lvalue-to-lvalue' conversions for looking up the 4199 /// glvalue referred to by an entity of reference type. 4200 /// 4201 /// \param Info - Information about the ongoing evaluation. 4202 /// \param Conv - The expression for which we are performing the conversion. 4203 /// Used for diagnostics. 4204 /// \param Type - The type of the glvalue (before stripping cv-qualifiers in the 4205 /// case of a non-class type). 4206 /// \param LVal - The glvalue on which we are attempting to perform this action. 4207 /// \param RVal - The produced value will be placed here. 4208 /// \param WantObjectRepresentation - If true, we're looking for the object 4209 /// representation rather than the value, and in particular, 4210 /// there is no requirement that the result be fully initialized. 4211 static bool 4212 handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, QualType Type, 4213 const LValue &LVal, APValue &RVal, 4214 bool WantObjectRepresentation = false) { 4215 if (LVal.Designator.Invalid) 4216 return false; 4217 4218 // Check for special cases where there is no existing APValue to look at. 4219 const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); 4220 4221 AccessKinds AK = 4222 WantObjectRepresentation ? AK_ReadObjectRepresentation : AK_Read; 4223 4224 if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) { 4225 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) { 4226 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the 4227 // initializer until now for such expressions. Such an expression can't be 4228 // an ICE in C, so this only matters for fold. 4229 if (Type.isVolatileQualified()) { 4230 Info.FFDiag(Conv); 4231 return false; 4232 } 4233 APValue Lit; 4234 if (!Evaluate(Lit, Info, CLE->getInitializer())) 4235 return false; 4236 CompleteObject LitObj(LVal.Base, &Lit, Base->getType()); 4237 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal, AK); 4238 } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) { 4239 // Special-case character extraction so we don't have to construct an 4240 // APValue for the whole string. 4241 assert(LVal.Designator.Entries.size() <= 1 && 4242 "Can only read characters from string literals"); 4243 if (LVal.Designator.Entries.empty()) { 4244 // Fail for now for LValue to RValue conversion of an array. 4245 // (This shouldn't show up in C/C++, but it could be triggered by a 4246 // weird EvaluateAsRValue call from a tool.) 4247 Info.FFDiag(Conv); 4248 return false; 4249 } 4250 if (LVal.Designator.isOnePastTheEnd()) { 4251 if (Info.getLangOpts().CPlusPlus11) 4252 Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK; 4253 else 4254 Info.FFDiag(Conv); 4255 return false; 4256 } 4257 uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex(); 4258 RVal = APValue(extractStringLiteralCharacter(Info, Base, CharIndex)); 4259 return true; 4260 } 4261 } 4262 4263 CompleteObject Obj = findCompleteObject(Info, Conv, AK, LVal, Type); 4264 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal, AK); 4265 } 4266 4267 /// Perform an assignment of Val to LVal. Takes ownership of Val. 4268 static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal, 4269 QualType LValType, APValue &Val) { 4270 if (LVal.Designator.Invalid) 4271 return false; 4272 4273 if (!Info.getLangOpts().CPlusPlus14) { 4274 Info.FFDiag(E); 4275 return false; 4276 } 4277 4278 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); 4279 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val); 4280 } 4281 4282 namespace { 4283 struct CompoundAssignSubobjectHandler { 4284 EvalInfo &Info; 4285 const CompoundAssignOperator *E; 4286 QualType PromotedLHSType; 4287 BinaryOperatorKind Opcode; 4288 const APValue &RHS; 4289 4290 static const AccessKinds AccessKind = AK_Assign; 4291 4292 typedef bool result_type; 4293 4294 bool checkConst(QualType QT) { 4295 // Assigning to a const object has undefined behavior. 4296 if (QT.isConstQualified()) { 4297 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; 4298 return false; 4299 } 4300 return true; 4301 } 4302 4303 bool failed() { return false; } 4304 bool found(APValue &Subobj, QualType SubobjType) { 4305 switch (Subobj.getKind()) { 4306 case APValue::Int: 4307 return found(Subobj.getInt(), SubobjType); 4308 case APValue::Float: 4309 return found(Subobj.getFloat(), SubobjType); 4310 case APValue::ComplexInt: 4311 case APValue::ComplexFloat: 4312 // FIXME: Implement complex compound assignment. 4313 Info.FFDiag(E); 4314 return false; 4315 case APValue::LValue: 4316 return foundPointer(Subobj, SubobjType); 4317 case APValue::Vector: 4318 return foundVector(Subobj, SubobjType); 4319 default: 4320 // FIXME: can this happen? 4321 Info.FFDiag(E); 4322 return false; 4323 } 4324 } 4325 4326 bool foundVector(APValue &Value, QualType SubobjType) { 4327 if (!checkConst(SubobjType)) 4328 return false; 4329 4330 if (!SubobjType->isVectorType()) { 4331 Info.FFDiag(E); 4332 return false; 4333 } 4334 return handleVectorVectorBinOp(Info, E, Opcode, Value, RHS); 4335 } 4336 4337 bool found(APSInt &Value, QualType SubobjType) { 4338 if (!checkConst(SubobjType)) 4339 return false; 4340 4341 if (!SubobjType->isIntegerType()) { 4342 // We don't support compound assignment on integer-cast-to-pointer 4343 // values. 4344 Info.FFDiag(E); 4345 return false; 4346 } 4347 4348 if (RHS.isInt()) { 4349 APSInt LHS = 4350 HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value); 4351 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS)) 4352 return false; 4353 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS); 4354 return true; 4355 } else if (RHS.isFloat()) { 4356 const FPOptions FPO = E->getFPFeaturesInEffect( 4357 Info.Ctx.getLangOpts()); 4358 APFloat FValue(0.0); 4359 return HandleIntToFloatCast(Info, E, FPO, SubobjType, Value, 4360 PromotedLHSType, FValue) && 4361 handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) && 4362 HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType, 4363 Value); 4364 } 4365 4366 Info.FFDiag(E); 4367 return false; 4368 } 4369 bool found(APFloat &Value, QualType SubobjType) { 4370 return checkConst(SubobjType) && 4371 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType, 4372 Value) && 4373 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) && 4374 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value); 4375 } 4376 bool foundPointer(APValue &Subobj, QualType SubobjType) { 4377 if (!checkConst(SubobjType)) 4378 return false; 4379 4380 QualType PointeeType; 4381 if (const PointerType *PT = SubobjType->getAs<PointerType>()) 4382 PointeeType = PT->getPointeeType(); 4383 4384 if (PointeeType.isNull() || !RHS.isInt() || 4385 (Opcode != BO_Add && Opcode != BO_Sub)) { 4386 Info.FFDiag(E); 4387 return false; 4388 } 4389 4390 APSInt Offset = RHS.getInt(); 4391 if (Opcode == BO_Sub) 4392 negateAsSigned(Offset); 4393 4394 LValue LVal; 4395 LVal.setFrom(Info.Ctx, Subobj); 4396 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset)) 4397 return false; 4398 LVal.moveInto(Subobj); 4399 return true; 4400 } 4401 }; 4402 } // end anonymous namespace 4403 4404 const AccessKinds CompoundAssignSubobjectHandler::AccessKind; 4405 4406 /// Perform a compound assignment of LVal <op>= RVal. 4407 static bool handleCompoundAssignment(EvalInfo &Info, 4408 const CompoundAssignOperator *E, 4409 const LValue &LVal, QualType LValType, 4410 QualType PromotedLValType, 4411 BinaryOperatorKind Opcode, 4412 const APValue &RVal) { 4413 if (LVal.Designator.Invalid) 4414 return false; 4415 4416 if (!Info.getLangOpts().CPlusPlus14) { 4417 Info.FFDiag(E); 4418 return false; 4419 } 4420 4421 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); 4422 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode, 4423 RVal }; 4424 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); 4425 } 4426 4427 namespace { 4428 struct IncDecSubobjectHandler { 4429 EvalInfo &Info; 4430 const UnaryOperator *E; 4431 AccessKinds AccessKind; 4432 APValue *Old; 4433 4434 typedef bool result_type; 4435 4436 bool checkConst(QualType QT) { 4437 // Assigning to a const object has undefined behavior. 4438 if (QT.isConstQualified()) { 4439 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; 4440 return false; 4441 } 4442 return true; 4443 } 4444 4445 bool failed() { return false; } 4446 bool found(APValue &Subobj, QualType SubobjType) { 4447 // Stash the old value. Also clear Old, so we don't clobber it later 4448 // if we're post-incrementing a complex. 4449 if (Old) { 4450 *Old = Subobj; 4451 Old = nullptr; 4452 } 4453 4454 switch (Subobj.getKind()) { 4455 case APValue::Int: 4456 return found(Subobj.getInt(), SubobjType); 4457 case APValue::Float: 4458 return found(Subobj.getFloat(), SubobjType); 4459 case APValue::ComplexInt: 4460 return found(Subobj.getComplexIntReal(), 4461 SubobjType->castAs<ComplexType>()->getElementType() 4462 .withCVRQualifiers(SubobjType.getCVRQualifiers())); 4463 case APValue::ComplexFloat: 4464 return found(Subobj.getComplexFloatReal(), 4465 SubobjType->castAs<ComplexType>()->getElementType() 4466 .withCVRQualifiers(SubobjType.getCVRQualifiers())); 4467 case APValue::LValue: 4468 return foundPointer(Subobj, SubobjType); 4469 default: 4470 // FIXME: can this happen? 4471 Info.FFDiag(E); 4472 return false; 4473 } 4474 } 4475 bool found(APSInt &Value, QualType SubobjType) { 4476 if (!checkConst(SubobjType)) 4477 return false; 4478 4479 if (!SubobjType->isIntegerType()) { 4480 // We don't support increment / decrement on integer-cast-to-pointer 4481 // values. 4482 Info.FFDiag(E); 4483 return false; 4484 } 4485 4486 if (Old) *Old = APValue(Value); 4487 4488 // bool arithmetic promotes to int, and the conversion back to bool 4489 // doesn't reduce mod 2^n, so special-case it. 4490 if (SubobjType->isBooleanType()) { 4491 if (AccessKind == AK_Increment) 4492 Value = 1; 4493 else 4494 Value = !Value; 4495 return true; 4496 } 4497 4498 bool WasNegative = Value.isNegative(); 4499 if (AccessKind == AK_Increment) { 4500 ++Value; 4501 4502 if (!WasNegative && Value.isNegative() && E->canOverflow()) { 4503 APSInt ActualValue(Value, /*IsUnsigned*/true); 4504 return HandleOverflow(Info, E, ActualValue, SubobjType); 4505 } 4506 } else { 4507 --Value; 4508 4509 if (WasNegative && !Value.isNegative() && E->canOverflow()) { 4510 unsigned BitWidth = Value.getBitWidth(); 4511 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false); 4512 ActualValue.setBit(BitWidth); 4513 return HandleOverflow(Info, E, ActualValue, SubobjType); 4514 } 4515 } 4516 return true; 4517 } 4518 bool found(APFloat &Value, QualType SubobjType) { 4519 if (!checkConst(SubobjType)) 4520 return false; 4521 4522 if (Old) *Old = APValue(Value); 4523 4524 APFloat One(Value.getSemantics(), 1); 4525 if (AccessKind == AK_Increment) 4526 Value.add(One, APFloat::rmNearestTiesToEven); 4527 else 4528 Value.subtract(One, APFloat::rmNearestTiesToEven); 4529 return true; 4530 } 4531 bool foundPointer(APValue &Subobj, QualType SubobjType) { 4532 if (!checkConst(SubobjType)) 4533 return false; 4534 4535 QualType PointeeType; 4536 if (const PointerType *PT = SubobjType->getAs<PointerType>()) 4537 PointeeType = PT->getPointeeType(); 4538 else { 4539 Info.FFDiag(E); 4540 return false; 4541 } 4542 4543 LValue LVal; 4544 LVal.setFrom(Info.Ctx, Subobj); 4545 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, 4546 AccessKind == AK_Increment ? 1 : -1)) 4547 return false; 4548 LVal.moveInto(Subobj); 4549 return true; 4550 } 4551 }; 4552 } // end anonymous namespace 4553 4554 /// Perform an increment or decrement on LVal. 4555 static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal, 4556 QualType LValType, bool IsIncrement, APValue *Old) { 4557 if (LVal.Designator.Invalid) 4558 return false; 4559 4560 if (!Info.getLangOpts().CPlusPlus14) { 4561 Info.FFDiag(E); 4562 return false; 4563 } 4564 4565 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement; 4566 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType); 4567 IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old}; 4568 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); 4569 } 4570 4571 /// Build an lvalue for the object argument of a member function call. 4572 static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object, 4573 LValue &This) { 4574 if (Object->getType()->isPointerType() && Object->isPRValue()) 4575 return EvaluatePointer(Object, This, Info); 4576 4577 if (Object->isGLValue()) 4578 return EvaluateLValue(Object, This, Info); 4579 4580 if (Object->getType()->isLiteralType(Info.Ctx)) 4581 return EvaluateTemporary(Object, This, Info); 4582 4583 Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType(); 4584 return false; 4585 } 4586 4587 /// HandleMemberPointerAccess - Evaluate a member access operation and build an 4588 /// lvalue referring to the result. 4589 /// 4590 /// \param Info - Information about the ongoing evaluation. 4591 /// \param LV - An lvalue referring to the base of the member pointer. 4592 /// \param RHS - The member pointer expression. 4593 /// \param IncludeMember - Specifies whether the member itself is included in 4594 /// the resulting LValue subobject designator. This is not possible when 4595 /// creating a bound member function. 4596 /// \return The field or method declaration to which the member pointer refers, 4597 /// or 0 if evaluation fails. 4598 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, 4599 QualType LVType, 4600 LValue &LV, 4601 const Expr *RHS, 4602 bool IncludeMember = true) { 4603 MemberPtr MemPtr; 4604 if (!EvaluateMemberPointer(RHS, MemPtr, Info)) 4605 return nullptr; 4606 4607 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to 4608 // member value, the behavior is undefined. 4609 if (!MemPtr.getDecl()) { 4610 // FIXME: Specific diagnostic. 4611 Info.FFDiag(RHS); 4612 return nullptr; 4613 } 4614 4615 if (MemPtr.isDerivedMember()) { 4616 // This is a member of some derived class. Truncate LV appropriately. 4617 // The end of the derived-to-base path for the base object must match the 4618 // derived-to-base path for the member pointer. 4619 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() > 4620 LV.Designator.Entries.size()) { 4621 Info.FFDiag(RHS); 4622 return nullptr; 4623 } 4624 unsigned PathLengthToMember = 4625 LV.Designator.Entries.size() - MemPtr.Path.size(); 4626 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) { 4627 const CXXRecordDecl *LVDecl = getAsBaseClass( 4628 LV.Designator.Entries[PathLengthToMember + I]); 4629 const CXXRecordDecl *MPDecl = MemPtr.Path[I]; 4630 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) { 4631 Info.FFDiag(RHS); 4632 return nullptr; 4633 } 4634 } 4635 4636 // Truncate the lvalue to the appropriate derived class. 4637 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(), 4638 PathLengthToMember)) 4639 return nullptr; 4640 } else if (!MemPtr.Path.empty()) { 4641 // Extend the LValue path with the member pointer's path. 4642 LV.Designator.Entries.reserve(LV.Designator.Entries.size() + 4643 MemPtr.Path.size() + IncludeMember); 4644 4645 // Walk down to the appropriate base class. 4646 if (const PointerType *PT = LVType->getAs<PointerType>()) 4647 LVType = PT->getPointeeType(); 4648 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl(); 4649 assert(RD && "member pointer access on non-class-type expression"); 4650 // The first class in the path is that of the lvalue. 4651 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) { 4652 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1]; 4653 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base)) 4654 return nullptr; 4655 RD = Base; 4656 } 4657 // Finally cast to the class containing the member. 4658 if (!HandleLValueDirectBase(Info, RHS, LV, RD, 4659 MemPtr.getContainingRecord())) 4660 return nullptr; 4661 } 4662 4663 // Add the member. Note that we cannot build bound member functions here. 4664 if (IncludeMember) { 4665 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) { 4666 if (!HandleLValueMember(Info, RHS, LV, FD)) 4667 return nullptr; 4668 } else if (const IndirectFieldDecl *IFD = 4669 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) { 4670 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD)) 4671 return nullptr; 4672 } else { 4673 llvm_unreachable("can't construct reference to bound member function"); 4674 } 4675 } 4676 4677 return MemPtr.getDecl(); 4678 } 4679 4680 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, 4681 const BinaryOperator *BO, 4682 LValue &LV, 4683 bool IncludeMember = true) { 4684 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI); 4685 4686 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) { 4687 if (Info.noteFailure()) { 4688 MemberPtr MemPtr; 4689 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info); 4690 } 4691 return nullptr; 4692 } 4693 4694 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV, 4695 BO->getRHS(), IncludeMember); 4696 } 4697 4698 /// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on 4699 /// the provided lvalue, which currently refers to the base object. 4700 static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E, 4701 LValue &Result) { 4702 SubobjectDesignator &D = Result.Designator; 4703 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived)) 4704 return false; 4705 4706 QualType TargetQT = E->getType(); 4707 if (const PointerType *PT = TargetQT->getAs<PointerType>()) 4708 TargetQT = PT->getPointeeType(); 4709 4710 // Check this cast lands within the final derived-to-base subobject path. 4711 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) { 4712 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) 4713 << D.MostDerivedType << TargetQT; 4714 return false; 4715 } 4716 4717 // Check the type of the final cast. We don't need to check the path, 4718 // since a cast can only be formed if the path is unique. 4719 unsigned NewEntriesSize = D.Entries.size() - E->path_size(); 4720 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl(); 4721 const CXXRecordDecl *FinalType; 4722 if (NewEntriesSize == D.MostDerivedPathLength) 4723 FinalType = D.MostDerivedType->getAsCXXRecordDecl(); 4724 else 4725 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]); 4726 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) { 4727 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) 4728 << D.MostDerivedType << TargetQT; 4729 return false; 4730 } 4731 4732 // Truncate the lvalue to the appropriate derived class. 4733 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize); 4734 } 4735 4736 /// Get the value to use for a default-initialized object of type T. 4737 /// Return false if it encounters something invalid. 4738 static bool getDefaultInitValue(QualType T, APValue &Result) { 4739 bool Success = true; 4740 if (auto *RD = T->getAsCXXRecordDecl()) { 4741 if (RD->isInvalidDecl()) { 4742 Result = APValue(); 4743 return false; 4744 } 4745 if (RD->isUnion()) { 4746 Result = APValue((const FieldDecl *)nullptr); 4747 return true; 4748 } 4749 Result = APValue(APValue::UninitStruct(), RD->getNumBases(), 4750 std::distance(RD->field_begin(), RD->field_end())); 4751 4752 unsigned Index = 0; 4753 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 4754 End = RD->bases_end(); 4755 I != End; ++I, ++Index) 4756 Success &= getDefaultInitValue(I->getType(), Result.getStructBase(Index)); 4757 4758 for (const auto *I : RD->fields()) { 4759 if (I->isUnnamedBitfield()) 4760 continue; 4761 Success &= getDefaultInitValue(I->getType(), 4762 Result.getStructField(I->getFieldIndex())); 4763 } 4764 return Success; 4765 } 4766 4767 if (auto *AT = 4768 dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) { 4769 Result = APValue(APValue::UninitArray(), 0, AT->getSize().getZExtValue()); 4770 if (Result.hasArrayFiller()) 4771 Success &= 4772 getDefaultInitValue(AT->getElementType(), Result.getArrayFiller()); 4773 4774 return Success; 4775 } 4776 4777 Result = APValue::IndeterminateValue(); 4778 return true; 4779 } 4780 4781 namespace { 4782 enum EvalStmtResult { 4783 /// Evaluation failed. 4784 ESR_Failed, 4785 /// Hit a 'return' statement. 4786 ESR_Returned, 4787 /// Evaluation succeeded. 4788 ESR_Succeeded, 4789 /// Hit a 'continue' statement. 4790 ESR_Continue, 4791 /// Hit a 'break' statement. 4792 ESR_Break, 4793 /// Still scanning for 'case' or 'default' statement. 4794 ESR_CaseNotFound 4795 }; 4796 } 4797 4798 static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) { 4799 // We don't need to evaluate the initializer for a static local. 4800 if (!VD->hasLocalStorage()) 4801 return true; 4802 4803 LValue Result; 4804 APValue &Val = Info.CurrentCall->createTemporary(VD, VD->getType(), 4805 ScopeKind::Block, Result); 4806 4807 const Expr *InitE = VD->getInit(); 4808 if (!InitE) { 4809 if (VD->getType()->isDependentType()) 4810 return Info.noteSideEffect(); 4811 return getDefaultInitValue(VD->getType(), Val); 4812 } 4813 if (InitE->isValueDependent()) 4814 return false; 4815 4816 if (!EvaluateInPlace(Val, Info, Result, InitE)) { 4817 // Wipe out any partially-computed value, to allow tracking that this 4818 // evaluation failed. 4819 Val = APValue(); 4820 return false; 4821 } 4822 4823 return true; 4824 } 4825 4826 static bool EvaluateDecl(EvalInfo &Info, const Decl *D) { 4827 bool OK = true; 4828 4829 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 4830 OK &= EvaluateVarDecl(Info, VD); 4831 4832 if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D)) 4833 for (auto *BD : DD->bindings()) 4834 if (auto *VD = BD->getHoldingVar()) 4835 OK &= EvaluateDecl(Info, VD); 4836 4837 return OK; 4838 } 4839 4840 static bool EvaluateDependentExpr(const Expr *E, EvalInfo &Info) { 4841 assert(E->isValueDependent()); 4842 if (Info.noteSideEffect()) 4843 return true; 4844 assert(E->containsErrors() && "valid value-dependent expression should never " 4845 "reach invalid code path."); 4846 return false; 4847 } 4848 4849 /// Evaluate a condition (either a variable declaration or an expression). 4850 static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl, 4851 const Expr *Cond, bool &Result) { 4852 if (Cond->isValueDependent()) 4853 return false; 4854 FullExpressionRAII Scope(Info); 4855 if (CondDecl && !EvaluateDecl(Info, CondDecl)) 4856 return false; 4857 if (!EvaluateAsBooleanCondition(Cond, Result, Info)) 4858 return false; 4859 return Scope.destroy(); 4860 } 4861 4862 namespace { 4863 /// A location where the result (returned value) of evaluating a 4864 /// statement should be stored. 4865 struct StmtResult { 4866 /// The APValue that should be filled in with the returned value. 4867 APValue &Value; 4868 /// The location containing the result, if any (used to support RVO). 4869 const LValue *Slot; 4870 }; 4871 4872 struct TempVersionRAII { 4873 CallStackFrame &Frame; 4874 4875 TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) { 4876 Frame.pushTempVersion(); 4877 } 4878 4879 ~TempVersionRAII() { 4880 Frame.popTempVersion(); 4881 } 4882 }; 4883 4884 } 4885 4886 static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info, 4887 const Stmt *S, 4888 const SwitchCase *SC = nullptr); 4889 4890 /// Evaluate the body of a loop, and translate the result as appropriate. 4891 static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info, 4892 const Stmt *Body, 4893 const SwitchCase *Case = nullptr) { 4894 BlockScopeRAII Scope(Info); 4895 4896 EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case); 4897 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy()) 4898 ESR = ESR_Failed; 4899 4900 switch (ESR) { 4901 case ESR_Break: 4902 return ESR_Succeeded; 4903 case ESR_Succeeded: 4904 case ESR_Continue: 4905 return ESR_Continue; 4906 case ESR_Failed: 4907 case ESR_Returned: 4908 case ESR_CaseNotFound: 4909 return ESR; 4910 } 4911 llvm_unreachable("Invalid EvalStmtResult!"); 4912 } 4913 4914 /// Evaluate a switch statement. 4915 static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info, 4916 const SwitchStmt *SS) { 4917 BlockScopeRAII Scope(Info); 4918 4919 // Evaluate the switch condition. 4920 APSInt Value; 4921 { 4922 if (const Stmt *Init = SS->getInit()) { 4923 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init); 4924 if (ESR != ESR_Succeeded) { 4925 if (ESR != ESR_Failed && !Scope.destroy()) 4926 ESR = ESR_Failed; 4927 return ESR; 4928 } 4929 } 4930 4931 FullExpressionRAII CondScope(Info); 4932 if (SS->getConditionVariable() && 4933 !EvaluateDecl(Info, SS->getConditionVariable())) 4934 return ESR_Failed; 4935 if (!EvaluateInteger(SS->getCond(), Value, Info)) 4936 return ESR_Failed; 4937 if (!CondScope.destroy()) 4938 return ESR_Failed; 4939 } 4940 4941 // Find the switch case corresponding to the value of the condition. 4942 // FIXME: Cache this lookup. 4943 const SwitchCase *Found = nullptr; 4944 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC; 4945 SC = SC->getNextSwitchCase()) { 4946 if (isa<DefaultStmt>(SC)) { 4947 Found = SC; 4948 continue; 4949 } 4950 4951 const CaseStmt *CS = cast<CaseStmt>(SC); 4952 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx); 4953 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx) 4954 : LHS; 4955 if (LHS <= Value && Value <= RHS) { 4956 Found = SC; 4957 break; 4958 } 4959 } 4960 4961 if (!Found) 4962 return Scope.destroy() ? ESR_Succeeded : ESR_Failed; 4963 4964 // Search the switch body for the switch case and evaluate it from there. 4965 EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found); 4966 if (ESR != ESR_Failed && ESR != ESR_CaseNotFound && !Scope.destroy()) 4967 return ESR_Failed; 4968 4969 switch (ESR) { 4970 case ESR_Break: 4971 return ESR_Succeeded; 4972 case ESR_Succeeded: 4973 case ESR_Continue: 4974 case ESR_Failed: 4975 case ESR_Returned: 4976 return ESR; 4977 case ESR_CaseNotFound: 4978 // This can only happen if the switch case is nested within a statement 4979 // expression. We have no intention of supporting that. 4980 Info.FFDiag(Found->getBeginLoc(), 4981 diag::note_constexpr_stmt_expr_unsupported); 4982 return ESR_Failed; 4983 } 4984 llvm_unreachable("Invalid EvalStmtResult!"); 4985 } 4986 4987 // Evaluate a statement. 4988 static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info, 4989 const Stmt *S, const SwitchCase *Case) { 4990 if (!Info.nextStep(S)) 4991 return ESR_Failed; 4992 4993 // If we're hunting down a 'case' or 'default' label, recurse through 4994 // substatements until we hit the label. 4995 if (Case) { 4996 switch (S->getStmtClass()) { 4997 case Stmt::CompoundStmtClass: 4998 // FIXME: Precompute which substatement of a compound statement we 4999 // would jump to, and go straight there rather than performing a 5000 // linear scan each time. 5001 case Stmt::LabelStmtClass: 5002 case Stmt::AttributedStmtClass: 5003 case Stmt::DoStmtClass: 5004 break; 5005 5006 case Stmt::CaseStmtClass: 5007 case Stmt::DefaultStmtClass: 5008 if (Case == S) 5009 Case = nullptr; 5010 break; 5011 5012 case Stmt::IfStmtClass: { 5013 // FIXME: Precompute which side of an 'if' we would jump to, and go 5014 // straight there rather than scanning both sides. 5015 const IfStmt *IS = cast<IfStmt>(S); 5016 5017 // Wrap the evaluation in a block scope, in case it's a DeclStmt 5018 // preceded by our switch label. 5019 BlockScopeRAII Scope(Info); 5020 5021 // Step into the init statement in case it brings an (uninitialized) 5022 // variable into scope. 5023 if (const Stmt *Init = IS->getInit()) { 5024 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case); 5025 if (ESR != ESR_CaseNotFound) { 5026 assert(ESR != ESR_Succeeded); 5027 return ESR; 5028 } 5029 } 5030 5031 // Condition variable must be initialized if it exists. 5032 // FIXME: We can skip evaluating the body if there's a condition 5033 // variable, as there can't be any case labels within it. 5034 // (The same is true for 'for' statements.) 5035 5036 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case); 5037 if (ESR == ESR_Failed) 5038 return ESR; 5039 if (ESR != ESR_CaseNotFound) 5040 return Scope.destroy() ? ESR : ESR_Failed; 5041 if (!IS->getElse()) 5042 return ESR_CaseNotFound; 5043 5044 ESR = EvaluateStmt(Result, Info, IS->getElse(), Case); 5045 if (ESR == ESR_Failed) 5046 return ESR; 5047 if (ESR != ESR_CaseNotFound) 5048 return Scope.destroy() ? ESR : ESR_Failed; 5049 return ESR_CaseNotFound; 5050 } 5051 5052 case Stmt::WhileStmtClass: { 5053 EvalStmtResult ESR = 5054 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case); 5055 if (ESR != ESR_Continue) 5056 return ESR; 5057 break; 5058 } 5059 5060 case Stmt::ForStmtClass: { 5061 const ForStmt *FS = cast<ForStmt>(S); 5062 BlockScopeRAII Scope(Info); 5063 5064 // Step into the init statement in case it brings an (uninitialized) 5065 // variable into scope. 5066 if (const Stmt *Init = FS->getInit()) { 5067 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init, Case); 5068 if (ESR != ESR_CaseNotFound) { 5069 assert(ESR != ESR_Succeeded); 5070 return ESR; 5071 } 5072 } 5073 5074 EvalStmtResult ESR = 5075 EvaluateLoopBody(Result, Info, FS->getBody(), Case); 5076 if (ESR != ESR_Continue) 5077 return ESR; 5078 if (const auto *Inc = FS->getInc()) { 5079 if (Inc->isValueDependent()) { 5080 if (!EvaluateDependentExpr(Inc, Info)) 5081 return ESR_Failed; 5082 } else { 5083 FullExpressionRAII IncScope(Info); 5084 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy()) 5085 return ESR_Failed; 5086 } 5087 } 5088 break; 5089 } 5090 5091 case Stmt::DeclStmtClass: { 5092 // Start the lifetime of any uninitialized variables we encounter. They 5093 // might be used by the selected branch of the switch. 5094 const DeclStmt *DS = cast<DeclStmt>(S); 5095 for (const auto *D : DS->decls()) { 5096 if (const auto *VD = dyn_cast<VarDecl>(D)) { 5097 if (VD->hasLocalStorage() && !VD->getInit()) 5098 if (!EvaluateVarDecl(Info, VD)) 5099 return ESR_Failed; 5100 // FIXME: If the variable has initialization that can't be jumped 5101 // over, bail out of any immediately-surrounding compound-statement 5102 // too. There can't be any case labels here. 5103 } 5104 } 5105 return ESR_CaseNotFound; 5106 } 5107 5108 default: 5109 return ESR_CaseNotFound; 5110 } 5111 } 5112 5113 switch (S->getStmtClass()) { 5114 default: 5115 if (const Expr *E = dyn_cast<Expr>(S)) { 5116 if (E->isValueDependent()) { 5117 if (!EvaluateDependentExpr(E, Info)) 5118 return ESR_Failed; 5119 } else { 5120 // Don't bother evaluating beyond an expression-statement which couldn't 5121 // be evaluated. 5122 // FIXME: Do we need the FullExpressionRAII object here? 5123 // VisitExprWithCleanups should create one when necessary. 5124 FullExpressionRAII Scope(Info); 5125 if (!EvaluateIgnoredValue(Info, E) || !Scope.destroy()) 5126 return ESR_Failed; 5127 } 5128 return ESR_Succeeded; 5129 } 5130 5131 Info.FFDiag(S->getBeginLoc()); 5132 return ESR_Failed; 5133 5134 case Stmt::NullStmtClass: 5135 return ESR_Succeeded; 5136 5137 case Stmt::DeclStmtClass: { 5138 const DeclStmt *DS = cast<DeclStmt>(S); 5139 for (const auto *D : DS->decls()) { 5140 // Each declaration initialization is its own full-expression. 5141 FullExpressionRAII Scope(Info); 5142 if (!EvaluateDecl(Info, D) && !Info.noteFailure()) 5143 return ESR_Failed; 5144 if (!Scope.destroy()) 5145 return ESR_Failed; 5146 } 5147 return ESR_Succeeded; 5148 } 5149 5150 case Stmt::ReturnStmtClass: { 5151 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue(); 5152 FullExpressionRAII Scope(Info); 5153 if (RetExpr && RetExpr->isValueDependent()) { 5154 EvaluateDependentExpr(RetExpr, Info); 5155 // We know we returned, but we don't know what the value is. 5156 return ESR_Failed; 5157 } 5158 if (RetExpr && 5159 !(Result.Slot 5160 ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr) 5161 : Evaluate(Result.Value, Info, RetExpr))) 5162 return ESR_Failed; 5163 return Scope.destroy() ? ESR_Returned : ESR_Failed; 5164 } 5165 5166 case Stmt::CompoundStmtClass: { 5167 BlockScopeRAII Scope(Info); 5168 5169 const CompoundStmt *CS = cast<CompoundStmt>(S); 5170 for (const auto *BI : CS->body()) { 5171 EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case); 5172 if (ESR == ESR_Succeeded) 5173 Case = nullptr; 5174 else if (ESR != ESR_CaseNotFound) { 5175 if (ESR != ESR_Failed && !Scope.destroy()) 5176 return ESR_Failed; 5177 return ESR; 5178 } 5179 } 5180 if (Case) 5181 return ESR_CaseNotFound; 5182 return Scope.destroy() ? ESR_Succeeded : ESR_Failed; 5183 } 5184 5185 case Stmt::IfStmtClass: { 5186 const IfStmt *IS = cast<IfStmt>(S); 5187 5188 // Evaluate the condition, as either a var decl or as an expression. 5189 BlockScopeRAII Scope(Info); 5190 if (const Stmt *Init = IS->getInit()) { 5191 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init); 5192 if (ESR != ESR_Succeeded) { 5193 if (ESR != ESR_Failed && !Scope.destroy()) 5194 return ESR_Failed; 5195 return ESR; 5196 } 5197 } 5198 bool Cond; 5199 if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond)) 5200 return ESR_Failed; 5201 5202 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) { 5203 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt); 5204 if (ESR != ESR_Succeeded) { 5205 if (ESR != ESR_Failed && !Scope.destroy()) 5206 return ESR_Failed; 5207 return ESR; 5208 } 5209 } 5210 return Scope.destroy() ? ESR_Succeeded : ESR_Failed; 5211 } 5212 5213 case Stmt::WhileStmtClass: { 5214 const WhileStmt *WS = cast<WhileStmt>(S); 5215 while (true) { 5216 BlockScopeRAII Scope(Info); 5217 bool Continue; 5218 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(), 5219 Continue)) 5220 return ESR_Failed; 5221 if (!Continue) 5222 break; 5223 5224 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody()); 5225 if (ESR != ESR_Continue) { 5226 if (ESR != ESR_Failed && !Scope.destroy()) 5227 return ESR_Failed; 5228 return ESR; 5229 } 5230 if (!Scope.destroy()) 5231 return ESR_Failed; 5232 } 5233 return ESR_Succeeded; 5234 } 5235 5236 case Stmt::DoStmtClass: { 5237 const DoStmt *DS = cast<DoStmt>(S); 5238 bool Continue; 5239 do { 5240 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case); 5241 if (ESR != ESR_Continue) 5242 return ESR; 5243 Case = nullptr; 5244 5245 if (DS->getCond()->isValueDependent()) { 5246 EvaluateDependentExpr(DS->getCond(), Info); 5247 // Bailout as we don't know whether to keep going or terminate the loop. 5248 return ESR_Failed; 5249 } 5250 FullExpressionRAII CondScope(Info); 5251 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info) || 5252 !CondScope.destroy()) 5253 return ESR_Failed; 5254 } while (Continue); 5255 return ESR_Succeeded; 5256 } 5257 5258 case Stmt::ForStmtClass: { 5259 const ForStmt *FS = cast<ForStmt>(S); 5260 BlockScopeRAII ForScope(Info); 5261 if (FS->getInit()) { 5262 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit()); 5263 if (ESR != ESR_Succeeded) { 5264 if (ESR != ESR_Failed && !ForScope.destroy()) 5265 return ESR_Failed; 5266 return ESR; 5267 } 5268 } 5269 while (true) { 5270 BlockScopeRAII IterScope(Info); 5271 bool Continue = true; 5272 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(), 5273 FS->getCond(), Continue)) 5274 return ESR_Failed; 5275 if (!Continue) 5276 break; 5277 5278 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody()); 5279 if (ESR != ESR_Continue) { 5280 if (ESR != ESR_Failed && (!IterScope.destroy() || !ForScope.destroy())) 5281 return ESR_Failed; 5282 return ESR; 5283 } 5284 5285 if (const auto *Inc = FS->getInc()) { 5286 if (Inc->isValueDependent()) { 5287 if (!EvaluateDependentExpr(Inc, Info)) 5288 return ESR_Failed; 5289 } else { 5290 FullExpressionRAII IncScope(Info); 5291 if (!EvaluateIgnoredValue(Info, Inc) || !IncScope.destroy()) 5292 return ESR_Failed; 5293 } 5294 } 5295 5296 if (!IterScope.destroy()) 5297 return ESR_Failed; 5298 } 5299 return ForScope.destroy() ? ESR_Succeeded : ESR_Failed; 5300 } 5301 5302 case Stmt::CXXForRangeStmtClass: { 5303 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S); 5304 BlockScopeRAII Scope(Info); 5305 5306 // Evaluate the init-statement if present. 5307 if (FS->getInit()) { 5308 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit()); 5309 if (ESR != ESR_Succeeded) { 5310 if (ESR != ESR_Failed && !Scope.destroy()) 5311 return ESR_Failed; 5312 return ESR; 5313 } 5314 } 5315 5316 // Initialize the __range variable. 5317 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt()); 5318 if (ESR != ESR_Succeeded) { 5319 if (ESR != ESR_Failed && !Scope.destroy()) 5320 return ESR_Failed; 5321 return ESR; 5322 } 5323 5324 // Create the __begin and __end iterators. 5325 ESR = EvaluateStmt(Result, Info, FS->getBeginStmt()); 5326 if (ESR != ESR_Succeeded) { 5327 if (ESR != ESR_Failed && !Scope.destroy()) 5328 return ESR_Failed; 5329 return ESR; 5330 } 5331 ESR = EvaluateStmt(Result, Info, FS->getEndStmt()); 5332 if (ESR != ESR_Succeeded) { 5333 if (ESR != ESR_Failed && !Scope.destroy()) 5334 return ESR_Failed; 5335 return ESR; 5336 } 5337 5338 while (true) { 5339 // Condition: __begin != __end. 5340 { 5341 if (FS->getCond()->isValueDependent()) { 5342 EvaluateDependentExpr(FS->getCond(), Info); 5343 // We don't know whether to keep going or terminate the loop. 5344 return ESR_Failed; 5345 } 5346 bool Continue = true; 5347 FullExpressionRAII CondExpr(Info); 5348 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info)) 5349 return ESR_Failed; 5350 if (!Continue) 5351 break; 5352 } 5353 5354 // User's variable declaration, initialized by *__begin. 5355 BlockScopeRAII InnerScope(Info); 5356 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt()); 5357 if (ESR != ESR_Succeeded) { 5358 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy())) 5359 return ESR_Failed; 5360 return ESR; 5361 } 5362 5363 // Loop body. 5364 ESR = EvaluateLoopBody(Result, Info, FS->getBody()); 5365 if (ESR != ESR_Continue) { 5366 if (ESR != ESR_Failed && (!InnerScope.destroy() || !Scope.destroy())) 5367 return ESR_Failed; 5368 return ESR; 5369 } 5370 if (FS->getInc()->isValueDependent()) { 5371 if (!EvaluateDependentExpr(FS->getInc(), Info)) 5372 return ESR_Failed; 5373 } else { 5374 // Increment: ++__begin 5375 if (!EvaluateIgnoredValue(Info, FS->getInc())) 5376 return ESR_Failed; 5377 } 5378 5379 if (!InnerScope.destroy()) 5380 return ESR_Failed; 5381 } 5382 5383 return Scope.destroy() ? ESR_Succeeded : ESR_Failed; 5384 } 5385 5386 case Stmt::SwitchStmtClass: 5387 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S)); 5388 5389 case Stmt::ContinueStmtClass: 5390 return ESR_Continue; 5391 5392 case Stmt::BreakStmtClass: 5393 return ESR_Break; 5394 5395 case Stmt::LabelStmtClass: 5396 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case); 5397 5398 case Stmt::AttributedStmtClass: 5399 // As a general principle, C++11 attributes can be ignored without 5400 // any semantic impact. 5401 return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(), 5402 Case); 5403 5404 case Stmt::CaseStmtClass: 5405 case Stmt::DefaultStmtClass: 5406 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case); 5407 case Stmt::CXXTryStmtClass: 5408 // Evaluate try blocks by evaluating all sub statements. 5409 return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case); 5410 } 5411 } 5412 5413 /// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial 5414 /// default constructor. If so, we'll fold it whether or not it's marked as 5415 /// constexpr. If it is marked as constexpr, we will never implicitly define it, 5416 /// so we need special handling. 5417 static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc, 5418 const CXXConstructorDecl *CD, 5419 bool IsValueInitialization) { 5420 if (!CD->isTrivial() || !CD->isDefaultConstructor()) 5421 return false; 5422 5423 // Value-initialization does not call a trivial default constructor, so such a 5424 // call is a core constant expression whether or not the constructor is 5425 // constexpr. 5426 if (!CD->isConstexpr() && !IsValueInitialization) { 5427 if (Info.getLangOpts().CPlusPlus11) { 5428 // FIXME: If DiagDecl is an implicitly-declared special member function, 5429 // we should be much more explicit about why it's not constexpr. 5430 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1) 5431 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD; 5432 Info.Note(CD->getLocation(), diag::note_declared_at); 5433 } else { 5434 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr); 5435 } 5436 } 5437 return true; 5438 } 5439 5440 /// CheckConstexprFunction - Check that a function can be called in a constant 5441 /// expression. 5442 static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc, 5443 const FunctionDecl *Declaration, 5444 const FunctionDecl *Definition, 5445 const Stmt *Body) { 5446 // Potential constant expressions can contain calls to declared, but not yet 5447 // defined, constexpr functions. 5448 if (Info.checkingPotentialConstantExpression() && !Definition && 5449 Declaration->isConstexpr()) 5450 return false; 5451 5452 // Bail out if the function declaration itself is invalid. We will 5453 // have produced a relevant diagnostic while parsing it, so just 5454 // note the problematic sub-expression. 5455 if (Declaration->isInvalidDecl()) { 5456 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); 5457 return false; 5458 } 5459 5460 // DR1872: An instantiated virtual constexpr function can't be called in a 5461 // constant expression (prior to C++20). We can still constant-fold such a 5462 // call. 5463 if (!Info.Ctx.getLangOpts().CPlusPlus20 && isa<CXXMethodDecl>(Declaration) && 5464 cast<CXXMethodDecl>(Declaration)->isVirtual()) 5465 Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call); 5466 5467 if (Definition && Definition->isInvalidDecl()) { 5468 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); 5469 return false; 5470 } 5471 5472 // Can we evaluate this function call? 5473 if (Definition && Definition->isConstexpr() && Body) 5474 return true; 5475 5476 if (Info.getLangOpts().CPlusPlus11) { 5477 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration; 5478 5479 // If this function is not constexpr because it is an inherited 5480 // non-constexpr constructor, diagnose that directly. 5481 auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl); 5482 if (CD && CD->isInheritingConstructor()) { 5483 auto *Inherited = CD->getInheritedConstructor().getConstructor(); 5484 if (!Inherited->isConstexpr()) 5485 DiagDecl = CD = Inherited; 5486 } 5487 5488 // FIXME: If DiagDecl is an implicitly-declared special member function 5489 // or an inheriting constructor, we should be much more explicit about why 5490 // it's not constexpr. 5491 if (CD && CD->isInheritingConstructor()) 5492 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1) 5493 << CD->getInheritedConstructor().getConstructor()->getParent(); 5494 else 5495 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1) 5496 << DiagDecl->isConstexpr() << (bool)CD << DiagDecl; 5497 Info.Note(DiagDecl->getLocation(), diag::note_declared_at); 5498 } else { 5499 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); 5500 } 5501 return false; 5502 } 5503 5504 namespace { 5505 struct CheckDynamicTypeHandler { 5506 AccessKinds AccessKind; 5507 typedef bool result_type; 5508 bool failed() { return false; } 5509 bool found(APValue &Subobj, QualType SubobjType) { return true; } 5510 bool found(APSInt &Value, QualType SubobjType) { return true; } 5511 bool found(APFloat &Value, QualType SubobjType) { return true; } 5512 }; 5513 } // end anonymous namespace 5514 5515 /// Check that we can access the notional vptr of an object / determine its 5516 /// dynamic type. 5517 static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This, 5518 AccessKinds AK, bool Polymorphic) { 5519 if (This.Designator.Invalid) 5520 return false; 5521 5522 CompleteObject Obj = findCompleteObject(Info, E, AK, This, QualType()); 5523 5524 if (!Obj) 5525 return false; 5526 5527 if (!Obj.Value) { 5528 // The object is not usable in constant expressions, so we can't inspect 5529 // its value to see if it's in-lifetime or what the active union members 5530 // are. We can still check for a one-past-the-end lvalue. 5531 if (This.Designator.isOnePastTheEnd() || 5532 This.Designator.isMostDerivedAnUnsizedArray()) { 5533 Info.FFDiag(E, This.Designator.isOnePastTheEnd() 5534 ? diag::note_constexpr_access_past_end 5535 : diag::note_constexpr_access_unsized_array) 5536 << AK; 5537 return false; 5538 } else if (Polymorphic) { 5539 // Conservatively refuse to perform a polymorphic operation if we would 5540 // not be able to read a notional 'vptr' value. 5541 APValue Val; 5542 This.moveInto(Val); 5543 QualType StarThisType = 5544 Info.Ctx.getLValueReferenceType(This.Designator.getType(Info.Ctx)); 5545 Info.FFDiag(E, diag::note_constexpr_polymorphic_unknown_dynamic_type) 5546 << AK << Val.getAsString(Info.Ctx, StarThisType); 5547 return false; 5548 } 5549 return true; 5550 } 5551 5552 CheckDynamicTypeHandler Handler{AK}; 5553 return Obj && findSubobject(Info, E, Obj, This.Designator, Handler); 5554 } 5555 5556 /// Check that the pointee of the 'this' pointer in a member function call is 5557 /// either within its lifetime or in its period of construction or destruction. 5558 static bool 5559 checkNonVirtualMemberCallThisPointer(EvalInfo &Info, const Expr *E, 5560 const LValue &This, 5561 const CXXMethodDecl *NamedMember) { 5562 return checkDynamicType( 5563 Info, E, This, 5564 isa<CXXDestructorDecl>(NamedMember) ? AK_Destroy : AK_MemberCall, false); 5565 } 5566 5567 struct DynamicType { 5568 /// The dynamic class type of the object. 5569 const CXXRecordDecl *Type; 5570 /// The corresponding path length in the lvalue. 5571 unsigned PathLength; 5572 }; 5573 5574 static const CXXRecordDecl *getBaseClassType(SubobjectDesignator &Designator, 5575 unsigned PathLength) { 5576 assert(PathLength >= Designator.MostDerivedPathLength && PathLength <= 5577 Designator.Entries.size() && "invalid path length"); 5578 return (PathLength == Designator.MostDerivedPathLength) 5579 ? Designator.MostDerivedType->getAsCXXRecordDecl() 5580 : getAsBaseClass(Designator.Entries[PathLength - 1]); 5581 } 5582 5583 /// Determine the dynamic type of an object. 5584 static Optional<DynamicType> ComputeDynamicType(EvalInfo &Info, const Expr *E, 5585 LValue &This, AccessKinds AK) { 5586 // If we don't have an lvalue denoting an object of class type, there is no 5587 // meaningful dynamic type. (We consider objects of non-class type to have no 5588 // dynamic type.) 5589 if (!checkDynamicType(Info, E, This, AK, true)) 5590 return None; 5591 5592 // Refuse to compute a dynamic type in the presence of virtual bases. This 5593 // shouldn't happen other than in constant-folding situations, since literal 5594 // types can't have virtual bases. 5595 // 5596 // Note that consumers of DynamicType assume that the type has no virtual 5597 // bases, and will need modifications if this restriction is relaxed. 5598 const CXXRecordDecl *Class = 5599 This.Designator.MostDerivedType->getAsCXXRecordDecl(); 5600 if (!Class || Class->getNumVBases()) { 5601 Info.FFDiag(E); 5602 return None; 5603 } 5604 5605 // FIXME: For very deep class hierarchies, it might be beneficial to use a 5606 // binary search here instead. But the overwhelmingly common case is that 5607 // we're not in the middle of a constructor, so it probably doesn't matter 5608 // in practice. 5609 ArrayRef<APValue::LValuePathEntry> Path = This.Designator.Entries; 5610 for (unsigned PathLength = This.Designator.MostDerivedPathLength; 5611 PathLength <= Path.size(); ++PathLength) { 5612 switch (Info.isEvaluatingCtorDtor(This.getLValueBase(), 5613 Path.slice(0, PathLength))) { 5614 case ConstructionPhase::Bases: 5615 case ConstructionPhase::DestroyingBases: 5616 // We're constructing or destroying a base class. This is not the dynamic 5617 // type. 5618 break; 5619 5620 case ConstructionPhase::None: 5621 case ConstructionPhase::AfterBases: 5622 case ConstructionPhase::AfterFields: 5623 case ConstructionPhase::Destroying: 5624 // We've finished constructing the base classes and not yet started 5625 // destroying them again, so this is the dynamic type. 5626 return DynamicType{getBaseClassType(This.Designator, PathLength), 5627 PathLength}; 5628 } 5629 } 5630 5631 // CWG issue 1517: we're constructing a base class of the object described by 5632 // 'This', so that object has not yet begun its period of construction and 5633 // any polymorphic operation on it results in undefined behavior. 5634 Info.FFDiag(E); 5635 return None; 5636 } 5637 5638 /// Perform virtual dispatch. 5639 static const CXXMethodDecl *HandleVirtualDispatch( 5640 EvalInfo &Info, const Expr *E, LValue &This, const CXXMethodDecl *Found, 5641 llvm::SmallVectorImpl<QualType> &CovariantAdjustmentPath) { 5642 Optional<DynamicType> DynType = ComputeDynamicType( 5643 Info, E, This, 5644 isa<CXXDestructorDecl>(Found) ? AK_Destroy : AK_MemberCall); 5645 if (!DynType) 5646 return nullptr; 5647 5648 // Find the final overrider. It must be declared in one of the classes on the 5649 // path from the dynamic type to the static type. 5650 // FIXME: If we ever allow literal types to have virtual base classes, that 5651 // won't be true. 5652 const CXXMethodDecl *Callee = Found; 5653 unsigned PathLength = DynType->PathLength; 5654 for (/**/; PathLength <= This.Designator.Entries.size(); ++PathLength) { 5655 const CXXRecordDecl *Class = getBaseClassType(This.Designator, PathLength); 5656 const CXXMethodDecl *Overrider = 5657 Found->getCorrespondingMethodDeclaredInClass(Class, false); 5658 if (Overrider) { 5659 Callee = Overrider; 5660 break; 5661 } 5662 } 5663 5664 // C++2a [class.abstract]p6: 5665 // the effect of making a virtual call to a pure virtual function [...] is 5666 // undefined 5667 if (Callee->isPure()) { 5668 Info.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << Callee; 5669 Info.Note(Callee->getLocation(), diag::note_declared_at); 5670 return nullptr; 5671 } 5672 5673 // If necessary, walk the rest of the path to determine the sequence of 5674 // covariant adjustment steps to apply. 5675 if (!Info.Ctx.hasSameUnqualifiedType(Callee->getReturnType(), 5676 Found->getReturnType())) { 5677 CovariantAdjustmentPath.push_back(Callee->getReturnType()); 5678 for (unsigned CovariantPathLength = PathLength + 1; 5679 CovariantPathLength != This.Designator.Entries.size(); 5680 ++CovariantPathLength) { 5681 const CXXRecordDecl *NextClass = 5682 getBaseClassType(This.Designator, CovariantPathLength); 5683 const CXXMethodDecl *Next = 5684 Found->getCorrespondingMethodDeclaredInClass(NextClass, false); 5685 if (Next && !Info.Ctx.hasSameUnqualifiedType( 5686 Next->getReturnType(), CovariantAdjustmentPath.back())) 5687 CovariantAdjustmentPath.push_back(Next->getReturnType()); 5688 } 5689 if (!Info.Ctx.hasSameUnqualifiedType(Found->getReturnType(), 5690 CovariantAdjustmentPath.back())) 5691 CovariantAdjustmentPath.push_back(Found->getReturnType()); 5692 } 5693 5694 // Perform 'this' adjustment. 5695 if (!CastToDerivedClass(Info, E, This, Callee->getParent(), PathLength)) 5696 return nullptr; 5697 5698 return Callee; 5699 } 5700 5701 /// Perform the adjustment from a value returned by a virtual function to 5702 /// a value of the statically expected type, which may be a pointer or 5703 /// reference to a base class of the returned type. 5704 static bool HandleCovariantReturnAdjustment(EvalInfo &Info, const Expr *E, 5705 APValue &Result, 5706 ArrayRef<QualType> Path) { 5707 assert(Result.isLValue() && 5708 "unexpected kind of APValue for covariant return"); 5709 if (Result.isNullPointer()) 5710 return true; 5711 5712 LValue LVal; 5713 LVal.setFrom(Info.Ctx, Result); 5714 5715 const CXXRecordDecl *OldClass = Path[0]->getPointeeCXXRecordDecl(); 5716 for (unsigned I = 1; I != Path.size(); ++I) { 5717 const CXXRecordDecl *NewClass = Path[I]->getPointeeCXXRecordDecl(); 5718 assert(OldClass && NewClass && "unexpected kind of covariant return"); 5719 if (OldClass != NewClass && 5720 !CastToBaseClass(Info, E, LVal, OldClass, NewClass)) 5721 return false; 5722 OldClass = NewClass; 5723 } 5724 5725 LVal.moveInto(Result); 5726 return true; 5727 } 5728 5729 /// Determine whether \p Base, which is known to be a direct base class of 5730 /// \p Derived, is a public base class. 5731 static bool isBaseClassPublic(const CXXRecordDecl *Derived, 5732 const CXXRecordDecl *Base) { 5733 for (const CXXBaseSpecifier &BaseSpec : Derived->bases()) { 5734 auto *BaseClass = BaseSpec.getType()->getAsCXXRecordDecl(); 5735 if (BaseClass && declaresSameEntity(BaseClass, Base)) 5736 return BaseSpec.getAccessSpecifier() == AS_public; 5737 } 5738 llvm_unreachable("Base is not a direct base of Derived"); 5739 } 5740 5741 /// Apply the given dynamic cast operation on the provided lvalue. 5742 /// 5743 /// This implements the hard case of dynamic_cast, requiring a "runtime check" 5744 /// to find a suitable target subobject. 5745 static bool HandleDynamicCast(EvalInfo &Info, const ExplicitCastExpr *E, 5746 LValue &Ptr) { 5747 // We can't do anything with a non-symbolic pointer value. 5748 SubobjectDesignator &D = Ptr.Designator; 5749 if (D.Invalid) 5750 return false; 5751 5752 // C++ [expr.dynamic.cast]p6: 5753 // If v is a null pointer value, the result is a null pointer value. 5754 if (Ptr.isNullPointer() && !E->isGLValue()) 5755 return true; 5756 5757 // For all the other cases, we need the pointer to point to an object within 5758 // its lifetime / period of construction / destruction, and we need to know 5759 // its dynamic type. 5760 Optional<DynamicType> DynType = 5761 ComputeDynamicType(Info, E, Ptr, AK_DynamicCast); 5762 if (!DynType) 5763 return false; 5764 5765 // C++ [expr.dynamic.cast]p7: 5766 // If T is "pointer to cv void", then the result is a pointer to the most 5767 // derived object 5768 if (E->getType()->isVoidPointerType()) 5769 return CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength); 5770 5771 const CXXRecordDecl *C = E->getTypeAsWritten()->getPointeeCXXRecordDecl(); 5772 assert(C && "dynamic_cast target is not void pointer nor class"); 5773 CanQualType CQT = Info.Ctx.getCanonicalType(Info.Ctx.getRecordType(C)); 5774 5775 auto RuntimeCheckFailed = [&] (CXXBasePaths *Paths) { 5776 // C++ [expr.dynamic.cast]p9: 5777 if (!E->isGLValue()) { 5778 // The value of a failed cast to pointer type is the null pointer value 5779 // of the required result type. 5780 Ptr.setNull(Info.Ctx, E->getType()); 5781 return true; 5782 } 5783 5784 // A failed cast to reference type throws [...] std::bad_cast. 5785 unsigned DiagKind; 5786 if (!Paths && (declaresSameEntity(DynType->Type, C) || 5787 DynType->Type->isDerivedFrom(C))) 5788 DiagKind = 0; 5789 else if (!Paths || Paths->begin() == Paths->end()) 5790 DiagKind = 1; 5791 else if (Paths->isAmbiguous(CQT)) 5792 DiagKind = 2; 5793 else { 5794 assert(Paths->front().Access != AS_public && "why did the cast fail?"); 5795 DiagKind = 3; 5796 } 5797 Info.FFDiag(E, diag::note_constexpr_dynamic_cast_to_reference_failed) 5798 << DiagKind << Ptr.Designator.getType(Info.Ctx) 5799 << Info.Ctx.getRecordType(DynType->Type) 5800 << E->getType().getUnqualifiedType(); 5801 return false; 5802 }; 5803 5804 // Runtime check, phase 1: 5805 // Walk from the base subobject towards the derived object looking for the 5806 // target type. 5807 for (int PathLength = Ptr.Designator.Entries.size(); 5808 PathLength >= (int)DynType->PathLength; --PathLength) { 5809 const CXXRecordDecl *Class = getBaseClassType(Ptr.Designator, PathLength); 5810 if (declaresSameEntity(Class, C)) 5811 return CastToDerivedClass(Info, E, Ptr, Class, PathLength); 5812 // We can only walk across public inheritance edges. 5813 if (PathLength > (int)DynType->PathLength && 5814 !isBaseClassPublic(getBaseClassType(Ptr.Designator, PathLength - 1), 5815 Class)) 5816 return RuntimeCheckFailed(nullptr); 5817 } 5818 5819 // Runtime check, phase 2: 5820 // Search the dynamic type for an unambiguous public base of type C. 5821 CXXBasePaths Paths(/*FindAmbiguities=*/true, 5822 /*RecordPaths=*/true, /*DetectVirtual=*/false); 5823 if (DynType->Type->isDerivedFrom(C, Paths) && !Paths.isAmbiguous(CQT) && 5824 Paths.front().Access == AS_public) { 5825 // Downcast to the dynamic type... 5826 if (!CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength)) 5827 return false; 5828 // ... then upcast to the chosen base class subobject. 5829 for (CXXBasePathElement &Elem : Paths.front()) 5830 if (!HandleLValueBase(Info, E, Ptr, Elem.Class, Elem.Base)) 5831 return false; 5832 return true; 5833 } 5834 5835 // Otherwise, the runtime check fails. 5836 return RuntimeCheckFailed(&Paths); 5837 } 5838 5839 namespace { 5840 struct StartLifetimeOfUnionMemberHandler { 5841 EvalInfo &Info; 5842 const Expr *LHSExpr; 5843 const FieldDecl *Field; 5844 bool DuringInit; 5845 bool Failed = false; 5846 static const AccessKinds AccessKind = AK_Assign; 5847 5848 typedef bool result_type; 5849 bool failed() { return Failed; } 5850 bool found(APValue &Subobj, QualType SubobjType) { 5851 // We are supposed to perform no initialization but begin the lifetime of 5852 // the object. We interpret that as meaning to do what default 5853 // initialization of the object would do if all constructors involved were 5854 // trivial: 5855 // * All base, non-variant member, and array element subobjects' lifetimes 5856 // begin 5857 // * No variant members' lifetimes begin 5858 // * All scalar subobjects whose lifetimes begin have indeterminate values 5859 assert(SubobjType->isUnionType()); 5860 if (declaresSameEntity(Subobj.getUnionField(), Field)) { 5861 // This union member is already active. If it's also in-lifetime, there's 5862 // nothing to do. 5863 if (Subobj.getUnionValue().hasValue()) 5864 return true; 5865 } else if (DuringInit) { 5866 // We're currently in the process of initializing a different union 5867 // member. If we carried on, that initialization would attempt to 5868 // store to an inactive union member, resulting in undefined behavior. 5869 Info.FFDiag(LHSExpr, 5870 diag::note_constexpr_union_member_change_during_init); 5871 return false; 5872 } 5873 APValue Result; 5874 Failed = !getDefaultInitValue(Field->getType(), Result); 5875 Subobj.setUnion(Field, Result); 5876 return true; 5877 } 5878 bool found(APSInt &Value, QualType SubobjType) { 5879 llvm_unreachable("wrong value kind for union object"); 5880 } 5881 bool found(APFloat &Value, QualType SubobjType) { 5882 llvm_unreachable("wrong value kind for union object"); 5883 } 5884 }; 5885 } // end anonymous namespace 5886 5887 const AccessKinds StartLifetimeOfUnionMemberHandler::AccessKind; 5888 5889 /// Handle a builtin simple-assignment or a call to a trivial assignment 5890 /// operator whose left-hand side might involve a union member access. If it 5891 /// does, implicitly start the lifetime of any accessed union elements per 5892 /// C++20 [class.union]5. 5893 static bool HandleUnionActiveMemberChange(EvalInfo &Info, const Expr *LHSExpr, 5894 const LValue &LHS) { 5895 if (LHS.InvalidBase || LHS.Designator.Invalid) 5896 return false; 5897 5898 llvm::SmallVector<std::pair<unsigned, const FieldDecl*>, 4> UnionPathLengths; 5899 // C++ [class.union]p5: 5900 // define the set S(E) of subexpressions of E as follows: 5901 unsigned PathLength = LHS.Designator.Entries.size(); 5902 for (const Expr *E = LHSExpr; E != nullptr;) { 5903 // -- If E is of the form A.B, S(E) contains the elements of S(A)... 5904 if (auto *ME = dyn_cast<MemberExpr>(E)) { 5905 auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl()); 5906 // Note that we can't implicitly start the lifetime of a reference, 5907 // so we don't need to proceed any further if we reach one. 5908 if (!FD || FD->getType()->isReferenceType()) 5909 break; 5910 5911 // ... and also contains A.B if B names a union member ... 5912 if (FD->getParent()->isUnion()) { 5913 // ... of a non-class, non-array type, or of a class type with a 5914 // trivial default constructor that is not deleted, or an array of 5915 // such types. 5916 auto *RD = 5917 FD->getType()->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); 5918 if (!RD || RD->hasTrivialDefaultConstructor()) 5919 UnionPathLengths.push_back({PathLength - 1, FD}); 5920 } 5921 5922 E = ME->getBase(); 5923 --PathLength; 5924 assert(declaresSameEntity(FD, 5925 LHS.Designator.Entries[PathLength] 5926 .getAsBaseOrMember().getPointer())); 5927 5928 // -- If E is of the form A[B] and is interpreted as a built-in array 5929 // subscripting operator, S(E) is [S(the array operand, if any)]. 5930 } else if (auto *ASE = dyn_cast<ArraySubscriptExpr>(E)) { 5931 // Step over an ArrayToPointerDecay implicit cast. 5932 auto *Base = ASE->getBase()->IgnoreImplicit(); 5933 if (!Base->getType()->isArrayType()) 5934 break; 5935 5936 E = Base; 5937 --PathLength; 5938 5939 } else if (auto *ICE = dyn_cast<ImplicitCastExpr>(E)) { 5940 // Step over a derived-to-base conversion. 5941 E = ICE->getSubExpr(); 5942 if (ICE->getCastKind() == CK_NoOp) 5943 continue; 5944 if (ICE->getCastKind() != CK_DerivedToBase && 5945 ICE->getCastKind() != CK_UncheckedDerivedToBase) 5946 break; 5947 // Walk path backwards as we walk up from the base to the derived class. 5948 for (const CXXBaseSpecifier *Elt : llvm::reverse(ICE->path())) { 5949 --PathLength; 5950 (void)Elt; 5951 assert(declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(), 5952 LHS.Designator.Entries[PathLength] 5953 .getAsBaseOrMember().getPointer())); 5954 } 5955 5956 // -- Otherwise, S(E) is empty. 5957 } else { 5958 break; 5959 } 5960 } 5961 5962 // Common case: no unions' lifetimes are started. 5963 if (UnionPathLengths.empty()) 5964 return true; 5965 5966 // if modification of X [would access an inactive union member], an object 5967 // of the type of X is implicitly created 5968 CompleteObject Obj = 5969 findCompleteObject(Info, LHSExpr, AK_Assign, LHS, LHSExpr->getType()); 5970 if (!Obj) 5971 return false; 5972 for (std::pair<unsigned, const FieldDecl *> LengthAndField : 5973 llvm::reverse(UnionPathLengths)) { 5974 // Form a designator for the union object. 5975 SubobjectDesignator D = LHS.Designator; 5976 D.truncate(Info.Ctx, LHS.Base, LengthAndField.first); 5977 5978 bool DuringInit = Info.isEvaluatingCtorDtor(LHS.Base, D.Entries) == 5979 ConstructionPhase::AfterBases; 5980 StartLifetimeOfUnionMemberHandler StartLifetime{ 5981 Info, LHSExpr, LengthAndField.second, DuringInit}; 5982 if (!findSubobject(Info, LHSExpr, Obj, D, StartLifetime)) 5983 return false; 5984 } 5985 5986 return true; 5987 } 5988 5989 static bool EvaluateCallArg(const ParmVarDecl *PVD, const Expr *Arg, 5990 CallRef Call, EvalInfo &Info, 5991 bool NonNull = false) { 5992 LValue LV; 5993 // Create the parameter slot and register its destruction. For a vararg 5994 // argument, create a temporary. 5995 // FIXME: For calling conventions that destroy parameters in the callee, 5996 // should we consider performing destruction when the function returns 5997 // instead? 5998 APValue &V = PVD ? Info.CurrentCall->createParam(Call, PVD, LV) 5999 : Info.CurrentCall->createTemporary(Arg, Arg->getType(), 6000 ScopeKind::Call, LV); 6001 if (!EvaluateInPlace(V, Info, LV, Arg)) 6002 return false; 6003 6004 // Passing a null pointer to an __attribute__((nonnull)) parameter results in 6005 // undefined behavior, so is non-constant. 6006 if (NonNull && V.isLValue() && V.isNullPointer()) { 6007 Info.CCEDiag(Arg, diag::note_non_null_attribute_failed); 6008 return false; 6009 } 6010 6011 return true; 6012 } 6013 6014 /// Evaluate the arguments to a function call. 6015 static bool EvaluateArgs(ArrayRef<const Expr *> Args, CallRef Call, 6016 EvalInfo &Info, const FunctionDecl *Callee, 6017 bool RightToLeft = false) { 6018 bool Success = true; 6019 llvm::SmallBitVector ForbiddenNullArgs; 6020 if (Callee->hasAttr<NonNullAttr>()) { 6021 ForbiddenNullArgs.resize(Args.size()); 6022 for (const auto *Attr : Callee->specific_attrs<NonNullAttr>()) { 6023 if (!Attr->args_size()) { 6024 ForbiddenNullArgs.set(); 6025 break; 6026 } else 6027 for (auto Idx : Attr->args()) { 6028 unsigned ASTIdx = Idx.getASTIndex(); 6029 if (ASTIdx >= Args.size()) 6030 continue; 6031 ForbiddenNullArgs[ASTIdx] = 1; 6032 } 6033 } 6034 } 6035 for (unsigned I = 0; I < Args.size(); I++) { 6036 unsigned Idx = RightToLeft ? Args.size() - I - 1 : I; 6037 const ParmVarDecl *PVD = 6038 Idx < Callee->getNumParams() ? Callee->getParamDecl(Idx) : nullptr; 6039 bool NonNull = !ForbiddenNullArgs.empty() && ForbiddenNullArgs[Idx]; 6040 if (!EvaluateCallArg(PVD, Args[Idx], Call, Info, NonNull)) { 6041 // If we're checking for a potential constant expression, evaluate all 6042 // initializers even if some of them fail. 6043 if (!Info.noteFailure()) 6044 return false; 6045 Success = false; 6046 } 6047 } 6048 return Success; 6049 } 6050 6051 /// Perform a trivial copy from Param, which is the parameter of a copy or move 6052 /// constructor or assignment operator. 6053 static bool handleTrivialCopy(EvalInfo &Info, const ParmVarDecl *Param, 6054 const Expr *E, APValue &Result, 6055 bool CopyObjectRepresentation) { 6056 // Find the reference argument. 6057 CallStackFrame *Frame = Info.CurrentCall; 6058 APValue *RefValue = Info.getParamSlot(Frame->Arguments, Param); 6059 if (!RefValue) { 6060 Info.FFDiag(E); 6061 return false; 6062 } 6063 6064 // Copy out the contents of the RHS object. 6065 LValue RefLValue; 6066 RefLValue.setFrom(Info.Ctx, *RefValue); 6067 return handleLValueToRValueConversion( 6068 Info, E, Param->getType().getNonReferenceType(), RefLValue, Result, 6069 CopyObjectRepresentation); 6070 } 6071 6072 /// Evaluate a function call. 6073 static bool HandleFunctionCall(SourceLocation CallLoc, 6074 const FunctionDecl *Callee, const LValue *This, 6075 ArrayRef<const Expr *> Args, CallRef Call, 6076 const Stmt *Body, EvalInfo &Info, 6077 APValue &Result, const LValue *ResultSlot) { 6078 if (!Info.CheckCallLimit(CallLoc)) 6079 return false; 6080 6081 CallStackFrame Frame(Info, CallLoc, Callee, This, Call); 6082 6083 // For a trivial copy or move assignment, perform an APValue copy. This is 6084 // essential for unions, where the operations performed by the assignment 6085 // operator cannot be represented as statements. 6086 // 6087 // Skip this for non-union classes with no fields; in that case, the defaulted 6088 // copy/move does not actually read the object. 6089 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee); 6090 if (MD && MD->isDefaulted() && 6091 (MD->getParent()->isUnion() || 6092 (MD->isTrivial() && 6093 isReadByLvalueToRvalueConversion(MD->getParent())))) { 6094 assert(This && 6095 (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())); 6096 APValue RHSValue; 6097 if (!handleTrivialCopy(Info, MD->getParamDecl(0), Args[0], RHSValue, 6098 MD->getParent()->isUnion())) 6099 return false; 6100 if (Info.getLangOpts().CPlusPlus20 && MD->isTrivial() && 6101 !HandleUnionActiveMemberChange(Info, Args[0], *This)) 6102 return false; 6103 if (!handleAssignment(Info, Args[0], *This, MD->getThisType(), 6104 RHSValue)) 6105 return false; 6106 This->moveInto(Result); 6107 return true; 6108 } else if (MD && isLambdaCallOperator(MD)) { 6109 // We're in a lambda; determine the lambda capture field maps unless we're 6110 // just constexpr checking a lambda's call operator. constexpr checking is 6111 // done before the captures have been added to the closure object (unless 6112 // we're inferring constexpr-ness), so we don't have access to them in this 6113 // case. But since we don't need the captures to constexpr check, we can 6114 // just ignore them. 6115 if (!Info.checkingPotentialConstantExpression()) 6116 MD->getParent()->getCaptureFields(Frame.LambdaCaptureFields, 6117 Frame.LambdaThisCaptureField); 6118 } 6119 6120 StmtResult Ret = {Result, ResultSlot}; 6121 EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body); 6122 if (ESR == ESR_Succeeded) { 6123 if (Callee->getReturnType()->isVoidType()) 6124 return true; 6125 Info.FFDiag(Callee->getEndLoc(), diag::note_constexpr_no_return); 6126 } 6127 return ESR == ESR_Returned; 6128 } 6129 6130 /// Evaluate a constructor call. 6131 static bool HandleConstructorCall(const Expr *E, const LValue &This, 6132 CallRef Call, 6133 const CXXConstructorDecl *Definition, 6134 EvalInfo &Info, APValue &Result) { 6135 SourceLocation CallLoc = E->getExprLoc(); 6136 if (!Info.CheckCallLimit(CallLoc)) 6137 return false; 6138 6139 const CXXRecordDecl *RD = Definition->getParent(); 6140 if (RD->getNumVBases()) { 6141 Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD; 6142 return false; 6143 } 6144 6145 EvalInfo::EvaluatingConstructorRAII EvalObj( 6146 Info, 6147 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries}, 6148 RD->getNumBases()); 6149 CallStackFrame Frame(Info, CallLoc, Definition, &This, Call); 6150 6151 // FIXME: Creating an APValue just to hold a nonexistent return value is 6152 // wasteful. 6153 APValue RetVal; 6154 StmtResult Ret = {RetVal, nullptr}; 6155 6156 // If it's a delegating constructor, delegate. 6157 if (Definition->isDelegatingConstructor()) { 6158 CXXConstructorDecl::init_const_iterator I = Definition->init_begin(); 6159 if ((*I)->getInit()->isValueDependent()) { 6160 if (!EvaluateDependentExpr((*I)->getInit(), Info)) 6161 return false; 6162 } else { 6163 FullExpressionRAII InitScope(Info); 6164 if (!EvaluateInPlace(Result, Info, This, (*I)->getInit()) || 6165 !InitScope.destroy()) 6166 return false; 6167 } 6168 return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed; 6169 } 6170 6171 // For a trivial copy or move constructor, perform an APValue copy. This is 6172 // essential for unions (or classes with anonymous union members), where the 6173 // operations performed by the constructor cannot be represented by 6174 // ctor-initializers. 6175 // 6176 // Skip this for empty non-union classes; we should not perform an 6177 // lvalue-to-rvalue conversion on them because their copy constructor does not 6178 // actually read them. 6179 if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() && 6180 (Definition->getParent()->isUnion() || 6181 (Definition->isTrivial() && 6182 isReadByLvalueToRvalueConversion(Definition->getParent())))) { 6183 return handleTrivialCopy(Info, Definition->getParamDecl(0), E, Result, 6184 Definition->getParent()->isUnion()); 6185 } 6186 6187 // Reserve space for the struct members. 6188 if (!Result.hasValue()) { 6189 if (!RD->isUnion()) 6190 Result = APValue(APValue::UninitStruct(), RD->getNumBases(), 6191 std::distance(RD->field_begin(), RD->field_end())); 6192 else 6193 // A union starts with no active member. 6194 Result = APValue((const FieldDecl*)nullptr); 6195 } 6196 6197 if (RD->isInvalidDecl()) return false; 6198 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 6199 6200 // A scope for temporaries lifetime-extended by reference members. 6201 BlockScopeRAII LifetimeExtendedScope(Info); 6202 6203 bool Success = true; 6204 unsigned BasesSeen = 0; 6205 #ifndef NDEBUG 6206 CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin(); 6207 #endif 6208 CXXRecordDecl::field_iterator FieldIt = RD->field_begin(); 6209 auto SkipToField = [&](FieldDecl *FD, bool Indirect) { 6210 // We might be initializing the same field again if this is an indirect 6211 // field initialization. 6212 if (FieldIt == RD->field_end() || 6213 FieldIt->getFieldIndex() > FD->getFieldIndex()) { 6214 assert(Indirect && "fields out of order?"); 6215 return; 6216 } 6217 6218 // Default-initialize any fields with no explicit initializer. 6219 for (; !declaresSameEntity(*FieldIt, FD); ++FieldIt) { 6220 assert(FieldIt != RD->field_end() && "missing field?"); 6221 if (!FieldIt->isUnnamedBitfield()) 6222 Success &= getDefaultInitValue( 6223 FieldIt->getType(), 6224 Result.getStructField(FieldIt->getFieldIndex())); 6225 } 6226 ++FieldIt; 6227 }; 6228 for (const auto *I : Definition->inits()) { 6229 LValue Subobject = This; 6230 LValue SubobjectParent = This; 6231 APValue *Value = &Result; 6232 6233 // Determine the subobject to initialize. 6234 FieldDecl *FD = nullptr; 6235 if (I->isBaseInitializer()) { 6236 QualType BaseType(I->getBaseClass(), 0); 6237 #ifndef NDEBUG 6238 // Non-virtual base classes are initialized in the order in the class 6239 // definition. We have already checked for virtual base classes. 6240 assert(!BaseIt->isVirtual() && "virtual base for literal type"); 6241 assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && 6242 "base class initializers not in expected order"); 6243 ++BaseIt; 6244 #endif 6245 if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD, 6246 BaseType->getAsCXXRecordDecl(), &Layout)) 6247 return false; 6248 Value = &Result.getStructBase(BasesSeen++); 6249 } else if ((FD = I->getMember())) { 6250 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout)) 6251 return false; 6252 if (RD->isUnion()) { 6253 Result = APValue(FD); 6254 Value = &Result.getUnionValue(); 6255 } else { 6256 SkipToField(FD, false); 6257 Value = &Result.getStructField(FD->getFieldIndex()); 6258 } 6259 } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) { 6260 // Walk the indirect field decl's chain to find the object to initialize, 6261 // and make sure we've initialized every step along it. 6262 auto IndirectFieldChain = IFD->chain(); 6263 for (auto *C : IndirectFieldChain) { 6264 FD = cast<FieldDecl>(C); 6265 CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent()); 6266 // Switch the union field if it differs. This happens if we had 6267 // preceding zero-initialization, and we're now initializing a union 6268 // subobject other than the first. 6269 // FIXME: In this case, the values of the other subobjects are 6270 // specified, since zero-initialization sets all padding bits to zero. 6271 if (!Value->hasValue() || 6272 (Value->isUnion() && Value->getUnionField() != FD)) { 6273 if (CD->isUnion()) 6274 *Value = APValue(FD); 6275 else 6276 // FIXME: This immediately starts the lifetime of all members of 6277 // an anonymous struct. It would be preferable to strictly start 6278 // member lifetime in initialization order. 6279 Success &= getDefaultInitValue(Info.Ctx.getRecordType(CD), *Value); 6280 } 6281 // Store Subobject as its parent before updating it for the last element 6282 // in the chain. 6283 if (C == IndirectFieldChain.back()) 6284 SubobjectParent = Subobject; 6285 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD)) 6286 return false; 6287 if (CD->isUnion()) 6288 Value = &Value->getUnionValue(); 6289 else { 6290 if (C == IndirectFieldChain.front() && !RD->isUnion()) 6291 SkipToField(FD, true); 6292 Value = &Value->getStructField(FD->getFieldIndex()); 6293 } 6294 } 6295 } else { 6296 llvm_unreachable("unknown base initializer kind"); 6297 } 6298 6299 // Need to override This for implicit field initializers as in this case 6300 // This refers to innermost anonymous struct/union containing initializer, 6301 // not to currently constructed class. 6302 const Expr *Init = I->getInit(); 6303 if (Init->isValueDependent()) { 6304 if (!EvaluateDependentExpr(Init, Info)) 6305 return false; 6306 } else { 6307 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &SubobjectParent, 6308 isa<CXXDefaultInitExpr>(Init)); 6309 FullExpressionRAII InitScope(Info); 6310 if (!EvaluateInPlace(*Value, Info, Subobject, Init) || 6311 (FD && FD->isBitField() && 6312 !truncateBitfieldValue(Info, Init, *Value, FD))) { 6313 // If we're checking for a potential constant expression, evaluate all 6314 // initializers even if some of them fail. 6315 if (!Info.noteFailure()) 6316 return false; 6317 Success = false; 6318 } 6319 } 6320 6321 // This is the point at which the dynamic type of the object becomes this 6322 // class type. 6323 if (I->isBaseInitializer() && BasesSeen == RD->getNumBases()) 6324 EvalObj.finishedConstructingBases(); 6325 } 6326 6327 // Default-initialize any remaining fields. 6328 if (!RD->isUnion()) { 6329 for (; FieldIt != RD->field_end(); ++FieldIt) { 6330 if (!FieldIt->isUnnamedBitfield()) 6331 Success &= getDefaultInitValue( 6332 FieldIt->getType(), 6333 Result.getStructField(FieldIt->getFieldIndex())); 6334 } 6335 } 6336 6337 EvalObj.finishedConstructingFields(); 6338 6339 return Success && 6340 EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed && 6341 LifetimeExtendedScope.destroy(); 6342 } 6343 6344 static bool HandleConstructorCall(const Expr *E, const LValue &This, 6345 ArrayRef<const Expr*> Args, 6346 const CXXConstructorDecl *Definition, 6347 EvalInfo &Info, APValue &Result) { 6348 CallScopeRAII CallScope(Info); 6349 CallRef Call = Info.CurrentCall->createCall(Definition); 6350 if (!EvaluateArgs(Args, Call, Info, Definition)) 6351 return false; 6352 6353 return HandleConstructorCall(E, This, Call, Definition, Info, Result) && 6354 CallScope.destroy(); 6355 } 6356 6357 static bool HandleDestructionImpl(EvalInfo &Info, SourceLocation CallLoc, 6358 const LValue &This, APValue &Value, 6359 QualType T) { 6360 // Objects can only be destroyed while they're within their lifetimes. 6361 // FIXME: We have no representation for whether an object of type nullptr_t 6362 // is in its lifetime; it usually doesn't matter. Perhaps we should model it 6363 // as indeterminate instead? 6364 if (Value.isAbsent() && !T->isNullPtrType()) { 6365 APValue Printable; 6366 This.moveInto(Printable); 6367 Info.FFDiag(CallLoc, diag::note_constexpr_destroy_out_of_lifetime) 6368 << Printable.getAsString(Info.Ctx, Info.Ctx.getLValueReferenceType(T)); 6369 return false; 6370 } 6371 6372 // Invent an expression for location purposes. 6373 // FIXME: We shouldn't need to do this. 6374 OpaqueValueExpr LocE(CallLoc, Info.Ctx.IntTy, VK_PRValue); 6375 6376 // For arrays, destroy elements right-to-left. 6377 if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(T)) { 6378 uint64_t Size = CAT->getSize().getZExtValue(); 6379 QualType ElemT = CAT->getElementType(); 6380 6381 LValue ElemLV = This; 6382 ElemLV.addArray(Info, &LocE, CAT); 6383 if (!HandleLValueArrayAdjustment(Info, &LocE, ElemLV, ElemT, Size)) 6384 return false; 6385 6386 // Ensure that we have actual array elements available to destroy; the 6387 // destructors might mutate the value, so we can't run them on the array 6388 // filler. 6389 if (Size && Size > Value.getArrayInitializedElts()) 6390 expandArray(Value, Value.getArraySize() - 1); 6391 6392 for (; Size != 0; --Size) { 6393 APValue &Elem = Value.getArrayInitializedElt(Size - 1); 6394 if (!HandleLValueArrayAdjustment(Info, &LocE, ElemLV, ElemT, -1) || 6395 !HandleDestructionImpl(Info, CallLoc, ElemLV, Elem, ElemT)) 6396 return false; 6397 } 6398 6399 // End the lifetime of this array now. 6400 Value = APValue(); 6401 return true; 6402 } 6403 6404 const CXXRecordDecl *RD = T->getAsCXXRecordDecl(); 6405 if (!RD) { 6406 if (T.isDestructedType()) { 6407 Info.FFDiag(CallLoc, diag::note_constexpr_unsupported_destruction) << T; 6408 return false; 6409 } 6410 6411 Value = APValue(); 6412 return true; 6413 } 6414 6415 if (RD->getNumVBases()) { 6416 Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD; 6417 return false; 6418 } 6419 6420 const CXXDestructorDecl *DD = RD->getDestructor(); 6421 if (!DD && !RD->hasTrivialDestructor()) { 6422 Info.FFDiag(CallLoc); 6423 return false; 6424 } 6425 6426 if (!DD || DD->isTrivial() || 6427 (RD->isAnonymousStructOrUnion() && RD->isUnion())) { 6428 // A trivial destructor just ends the lifetime of the object. Check for 6429 // this case before checking for a body, because we might not bother 6430 // building a body for a trivial destructor. Note that it doesn't matter 6431 // whether the destructor is constexpr in this case; all trivial 6432 // destructors are constexpr. 6433 // 6434 // If an anonymous union would be destroyed, some enclosing destructor must 6435 // have been explicitly defined, and the anonymous union destruction should 6436 // have no effect. 6437 Value = APValue(); 6438 return true; 6439 } 6440 6441 if (!Info.CheckCallLimit(CallLoc)) 6442 return false; 6443 6444 const FunctionDecl *Definition = nullptr; 6445 const Stmt *Body = DD->getBody(Definition); 6446 6447 if (!CheckConstexprFunction(Info, CallLoc, DD, Definition, Body)) 6448 return false; 6449 6450 CallStackFrame Frame(Info, CallLoc, Definition, &This, CallRef()); 6451 6452 // We're now in the period of destruction of this object. 6453 unsigned BasesLeft = RD->getNumBases(); 6454 EvalInfo::EvaluatingDestructorRAII EvalObj( 6455 Info, 6456 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries}); 6457 if (!EvalObj.DidInsert) { 6458 // C++2a [class.dtor]p19: 6459 // the behavior is undefined if the destructor is invoked for an object 6460 // whose lifetime has ended 6461 // (Note that formally the lifetime ends when the period of destruction 6462 // begins, even though certain uses of the object remain valid until the 6463 // period of destruction ends.) 6464 Info.FFDiag(CallLoc, diag::note_constexpr_double_destroy); 6465 return false; 6466 } 6467 6468 // FIXME: Creating an APValue just to hold a nonexistent return value is 6469 // wasteful. 6470 APValue RetVal; 6471 StmtResult Ret = {RetVal, nullptr}; 6472 if (EvaluateStmt(Ret, Info, Definition->getBody()) == ESR_Failed) 6473 return false; 6474 6475 // A union destructor does not implicitly destroy its members. 6476 if (RD->isUnion()) 6477 return true; 6478 6479 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 6480 6481 // We don't have a good way to iterate fields in reverse, so collect all the 6482 // fields first and then walk them backwards. 6483 SmallVector<FieldDecl*, 16> Fields(RD->field_begin(), RD->field_end()); 6484 for (const FieldDecl *FD : llvm::reverse(Fields)) { 6485 if (FD->isUnnamedBitfield()) 6486 continue; 6487 6488 LValue Subobject = This; 6489 if (!HandleLValueMember(Info, &LocE, Subobject, FD, &Layout)) 6490 return false; 6491 6492 APValue *SubobjectValue = &Value.getStructField(FD->getFieldIndex()); 6493 if (!HandleDestructionImpl(Info, CallLoc, Subobject, *SubobjectValue, 6494 FD->getType())) 6495 return false; 6496 } 6497 6498 if (BasesLeft != 0) 6499 EvalObj.startedDestroyingBases(); 6500 6501 // Destroy base classes in reverse order. 6502 for (const CXXBaseSpecifier &Base : llvm::reverse(RD->bases())) { 6503 --BasesLeft; 6504 6505 QualType BaseType = Base.getType(); 6506 LValue Subobject = This; 6507 if (!HandleLValueDirectBase(Info, &LocE, Subobject, RD, 6508 BaseType->getAsCXXRecordDecl(), &Layout)) 6509 return false; 6510 6511 APValue *SubobjectValue = &Value.getStructBase(BasesLeft); 6512 if (!HandleDestructionImpl(Info, CallLoc, Subobject, *SubobjectValue, 6513 BaseType)) 6514 return false; 6515 } 6516 assert(BasesLeft == 0 && "NumBases was wrong?"); 6517 6518 // The period of destruction ends now. The object is gone. 6519 Value = APValue(); 6520 return true; 6521 } 6522 6523 namespace { 6524 struct DestroyObjectHandler { 6525 EvalInfo &Info; 6526 const Expr *E; 6527 const LValue &This; 6528 const AccessKinds AccessKind; 6529 6530 typedef bool result_type; 6531 bool failed() { return false; } 6532 bool found(APValue &Subobj, QualType SubobjType) { 6533 return HandleDestructionImpl(Info, E->getExprLoc(), This, Subobj, 6534 SubobjType); 6535 } 6536 bool found(APSInt &Value, QualType SubobjType) { 6537 Info.FFDiag(E, diag::note_constexpr_destroy_complex_elem); 6538 return false; 6539 } 6540 bool found(APFloat &Value, QualType SubobjType) { 6541 Info.FFDiag(E, diag::note_constexpr_destroy_complex_elem); 6542 return false; 6543 } 6544 }; 6545 } 6546 6547 /// Perform a destructor or pseudo-destructor call on the given object, which 6548 /// might in general not be a complete object. 6549 static bool HandleDestruction(EvalInfo &Info, const Expr *E, 6550 const LValue &This, QualType ThisType) { 6551 CompleteObject Obj = findCompleteObject(Info, E, AK_Destroy, This, ThisType); 6552 DestroyObjectHandler Handler = {Info, E, This, AK_Destroy}; 6553 return Obj && findSubobject(Info, E, Obj, This.Designator, Handler); 6554 } 6555 6556 /// Destroy and end the lifetime of the given complete object. 6557 static bool HandleDestruction(EvalInfo &Info, SourceLocation Loc, 6558 APValue::LValueBase LVBase, APValue &Value, 6559 QualType T) { 6560 // If we've had an unmodeled side-effect, we can't rely on mutable state 6561 // (such as the object we're about to destroy) being correct. 6562 if (Info.EvalStatus.HasSideEffects) 6563 return false; 6564 6565 LValue LV; 6566 LV.set({LVBase}); 6567 return HandleDestructionImpl(Info, Loc, LV, Value, T); 6568 } 6569 6570 /// Perform a call to 'perator new' or to `__builtin_operator_new'. 6571 static bool HandleOperatorNewCall(EvalInfo &Info, const CallExpr *E, 6572 LValue &Result) { 6573 if (Info.checkingPotentialConstantExpression() || 6574 Info.SpeculativeEvaluationDepth) 6575 return false; 6576 6577 // This is permitted only within a call to std::allocator<T>::allocate. 6578 auto Caller = Info.getStdAllocatorCaller("allocate"); 6579 if (!Caller) { 6580 Info.FFDiag(E->getExprLoc(), Info.getLangOpts().CPlusPlus20 6581 ? diag::note_constexpr_new_untyped 6582 : diag::note_constexpr_new); 6583 return false; 6584 } 6585 6586 QualType ElemType = Caller.ElemType; 6587 if (ElemType->isIncompleteType() || ElemType->isFunctionType()) { 6588 Info.FFDiag(E->getExprLoc(), 6589 diag::note_constexpr_new_not_complete_object_type) 6590 << (ElemType->isIncompleteType() ? 0 : 1) << ElemType; 6591 return false; 6592 } 6593 6594 APSInt ByteSize; 6595 if (!EvaluateInteger(E->getArg(0), ByteSize, Info)) 6596 return false; 6597 bool IsNothrow = false; 6598 for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I) { 6599 EvaluateIgnoredValue(Info, E->getArg(I)); 6600 IsNothrow |= E->getType()->isNothrowT(); 6601 } 6602 6603 CharUnits ElemSize; 6604 if (!HandleSizeof(Info, E->getExprLoc(), ElemType, ElemSize)) 6605 return false; 6606 APInt Size, Remainder; 6607 APInt ElemSizeAP(ByteSize.getBitWidth(), ElemSize.getQuantity()); 6608 APInt::udivrem(ByteSize, ElemSizeAP, Size, Remainder); 6609 if (Remainder != 0) { 6610 // This likely indicates a bug in the implementation of 'std::allocator'. 6611 Info.FFDiag(E->getExprLoc(), diag::note_constexpr_operator_new_bad_size) 6612 << ByteSize << APSInt(ElemSizeAP, true) << ElemType; 6613 return false; 6614 } 6615 6616 if (ByteSize.getActiveBits() > ConstantArrayType::getMaxSizeBits(Info.Ctx)) { 6617 if (IsNothrow) { 6618 Result.setNull(Info.Ctx, E->getType()); 6619 return true; 6620 } 6621 6622 Info.FFDiag(E, diag::note_constexpr_new_too_large) << APSInt(Size, true); 6623 return false; 6624 } 6625 6626 QualType AllocType = Info.Ctx.getConstantArrayType(ElemType, Size, nullptr, 6627 ArrayType::Normal, 0); 6628 APValue *Val = Info.createHeapAlloc(E, AllocType, Result); 6629 *Val = APValue(APValue::UninitArray(), 0, Size.getZExtValue()); 6630 Result.addArray(Info, E, cast<ConstantArrayType>(AllocType)); 6631 return true; 6632 } 6633 6634 static bool hasVirtualDestructor(QualType T) { 6635 if (CXXRecordDecl *RD = T->getAsCXXRecordDecl()) 6636 if (CXXDestructorDecl *DD = RD->getDestructor()) 6637 return DD->isVirtual(); 6638 return false; 6639 } 6640 6641 static const FunctionDecl *getVirtualOperatorDelete(QualType T) { 6642 if (CXXRecordDecl *RD = T->getAsCXXRecordDecl()) 6643 if (CXXDestructorDecl *DD = RD->getDestructor()) 6644 return DD->isVirtual() ? DD->getOperatorDelete() : nullptr; 6645 return nullptr; 6646 } 6647 6648 /// Check that the given object is a suitable pointer to a heap allocation that 6649 /// still exists and is of the right kind for the purpose of a deletion. 6650 /// 6651 /// On success, returns the heap allocation to deallocate. On failure, produces 6652 /// a diagnostic and returns None. 6653 static Optional<DynAlloc *> CheckDeleteKind(EvalInfo &Info, const Expr *E, 6654 const LValue &Pointer, 6655 DynAlloc::Kind DeallocKind) { 6656 auto PointerAsString = [&] { 6657 return Pointer.toString(Info.Ctx, Info.Ctx.VoidPtrTy); 6658 }; 6659 6660 DynamicAllocLValue DA = Pointer.Base.dyn_cast<DynamicAllocLValue>(); 6661 if (!DA) { 6662 Info.FFDiag(E, diag::note_constexpr_delete_not_heap_alloc) 6663 << PointerAsString(); 6664 if (Pointer.Base) 6665 NoteLValueLocation(Info, Pointer.Base); 6666 return None; 6667 } 6668 6669 Optional<DynAlloc *> Alloc = Info.lookupDynamicAlloc(DA); 6670 if (!Alloc) { 6671 Info.FFDiag(E, diag::note_constexpr_double_delete); 6672 return None; 6673 } 6674 6675 QualType AllocType = Pointer.Base.getDynamicAllocType(); 6676 if (DeallocKind != (*Alloc)->getKind()) { 6677 Info.FFDiag(E, diag::note_constexpr_new_delete_mismatch) 6678 << DeallocKind << (*Alloc)->getKind() << AllocType; 6679 NoteLValueLocation(Info, Pointer.Base); 6680 return None; 6681 } 6682 6683 bool Subobject = false; 6684 if (DeallocKind == DynAlloc::New) { 6685 Subobject = Pointer.Designator.MostDerivedPathLength != 0 || 6686 Pointer.Designator.isOnePastTheEnd(); 6687 } else { 6688 Subobject = Pointer.Designator.Entries.size() != 1 || 6689 Pointer.Designator.Entries[0].getAsArrayIndex() != 0; 6690 } 6691 if (Subobject) { 6692 Info.FFDiag(E, diag::note_constexpr_delete_subobject) 6693 << PointerAsString() << Pointer.Designator.isOnePastTheEnd(); 6694 return None; 6695 } 6696 6697 return Alloc; 6698 } 6699 6700 // Perform a call to 'operator delete' or '__builtin_operator_delete'. 6701 bool HandleOperatorDeleteCall(EvalInfo &Info, const CallExpr *E) { 6702 if (Info.checkingPotentialConstantExpression() || 6703 Info.SpeculativeEvaluationDepth) 6704 return false; 6705 6706 // This is permitted only within a call to std::allocator<T>::deallocate. 6707 if (!Info.getStdAllocatorCaller("deallocate")) { 6708 Info.FFDiag(E->getExprLoc()); 6709 return true; 6710 } 6711 6712 LValue Pointer; 6713 if (!EvaluatePointer(E->getArg(0), Pointer, Info)) 6714 return false; 6715 for (unsigned I = 1, N = E->getNumArgs(); I != N; ++I) 6716 EvaluateIgnoredValue(Info, E->getArg(I)); 6717 6718 if (Pointer.Designator.Invalid) 6719 return false; 6720 6721 // Deleting a null pointer would have no effect, but it's not permitted by 6722 // std::allocator<T>::deallocate's contract. 6723 if (Pointer.isNullPointer()) { 6724 Info.CCEDiag(E->getExprLoc(), diag::note_constexpr_deallocate_null); 6725 return true; 6726 } 6727 6728 if (!CheckDeleteKind(Info, E, Pointer, DynAlloc::StdAllocator)) 6729 return false; 6730 6731 Info.HeapAllocs.erase(Pointer.Base.get<DynamicAllocLValue>()); 6732 return true; 6733 } 6734 6735 //===----------------------------------------------------------------------===// 6736 // Generic Evaluation 6737 //===----------------------------------------------------------------------===// 6738 namespace { 6739 6740 class BitCastBuffer { 6741 // FIXME: We're going to need bit-level granularity when we support 6742 // bit-fields. 6743 // FIXME: Its possible under the C++ standard for 'char' to not be 8 bits, but 6744 // we don't support a host or target where that is the case. Still, we should 6745 // use a more generic type in case we ever do. 6746 SmallVector<Optional<unsigned char>, 32> Bytes; 6747 6748 static_assert(std::numeric_limits<unsigned char>::digits >= 8, 6749 "Need at least 8 bit unsigned char"); 6750 6751 bool TargetIsLittleEndian; 6752 6753 public: 6754 BitCastBuffer(CharUnits Width, bool TargetIsLittleEndian) 6755 : Bytes(Width.getQuantity()), 6756 TargetIsLittleEndian(TargetIsLittleEndian) {} 6757 6758 LLVM_NODISCARD 6759 bool readObject(CharUnits Offset, CharUnits Width, 6760 SmallVectorImpl<unsigned char> &Output) const { 6761 for (CharUnits I = Offset, E = Offset + Width; I != E; ++I) { 6762 // If a byte of an integer is uninitialized, then the whole integer is 6763 // uninitalized. 6764 if (!Bytes[I.getQuantity()]) 6765 return false; 6766 Output.push_back(*Bytes[I.getQuantity()]); 6767 } 6768 if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian) 6769 std::reverse(Output.begin(), Output.end()); 6770 return true; 6771 } 6772 6773 void writeObject(CharUnits Offset, SmallVectorImpl<unsigned char> &Input) { 6774 if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian) 6775 std::reverse(Input.begin(), Input.end()); 6776 6777 size_t Index = 0; 6778 for (unsigned char Byte : Input) { 6779 assert(!Bytes[Offset.getQuantity() + Index] && "overwriting a byte?"); 6780 Bytes[Offset.getQuantity() + Index] = Byte; 6781 ++Index; 6782 } 6783 } 6784 6785 size_t size() { return Bytes.size(); } 6786 }; 6787 6788 /// Traverse an APValue to produce an BitCastBuffer, emulating how the current 6789 /// target would represent the value at runtime. 6790 class APValueToBufferConverter { 6791 EvalInfo &Info; 6792 BitCastBuffer Buffer; 6793 const CastExpr *BCE; 6794 6795 APValueToBufferConverter(EvalInfo &Info, CharUnits ObjectWidth, 6796 const CastExpr *BCE) 6797 : Info(Info), 6798 Buffer(ObjectWidth, Info.Ctx.getTargetInfo().isLittleEndian()), 6799 BCE(BCE) {} 6800 6801 bool visit(const APValue &Val, QualType Ty) { 6802 return visit(Val, Ty, CharUnits::fromQuantity(0)); 6803 } 6804 6805 // Write out Val with type Ty into Buffer starting at Offset. 6806 bool visit(const APValue &Val, QualType Ty, CharUnits Offset) { 6807 assert((size_t)Offset.getQuantity() <= Buffer.size()); 6808 6809 // As a special case, nullptr_t has an indeterminate value. 6810 if (Ty->isNullPtrType()) 6811 return true; 6812 6813 // Dig through Src to find the byte at SrcOffset. 6814 switch (Val.getKind()) { 6815 case APValue::Indeterminate: 6816 case APValue::None: 6817 return true; 6818 6819 case APValue::Int: 6820 return visitInt(Val.getInt(), Ty, Offset); 6821 case APValue::Float: 6822 return visitFloat(Val.getFloat(), Ty, Offset); 6823 case APValue::Array: 6824 return visitArray(Val, Ty, Offset); 6825 case APValue::Struct: 6826 return visitRecord(Val, Ty, Offset); 6827 6828 case APValue::ComplexInt: 6829 case APValue::ComplexFloat: 6830 case APValue::Vector: 6831 case APValue::FixedPoint: 6832 // FIXME: We should support these. 6833 6834 case APValue::Union: 6835 case APValue::MemberPointer: 6836 case APValue::AddrLabelDiff: { 6837 Info.FFDiag(BCE->getBeginLoc(), 6838 diag::note_constexpr_bit_cast_unsupported_type) 6839 << Ty; 6840 return false; 6841 } 6842 6843 case APValue::LValue: 6844 llvm_unreachable("LValue subobject in bit_cast?"); 6845 } 6846 llvm_unreachable("Unhandled APValue::ValueKind"); 6847 } 6848 6849 bool visitRecord(const APValue &Val, QualType Ty, CharUnits Offset) { 6850 const RecordDecl *RD = Ty->getAsRecordDecl(); 6851 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 6852 6853 // Visit the base classes. 6854 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) { 6855 for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) { 6856 const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I]; 6857 CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl(); 6858 6859 if (!visitRecord(Val.getStructBase(I), BS.getType(), 6860 Layout.getBaseClassOffset(BaseDecl) + Offset)) 6861 return false; 6862 } 6863 } 6864 6865 // Visit the fields. 6866 unsigned FieldIdx = 0; 6867 for (FieldDecl *FD : RD->fields()) { 6868 if (FD->isBitField()) { 6869 Info.FFDiag(BCE->getBeginLoc(), 6870 diag::note_constexpr_bit_cast_unsupported_bitfield); 6871 return false; 6872 } 6873 6874 uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx); 6875 6876 assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0 && 6877 "only bit-fields can have sub-char alignment"); 6878 CharUnits FieldOffset = 6879 Info.Ctx.toCharUnitsFromBits(FieldOffsetBits) + Offset; 6880 QualType FieldTy = FD->getType(); 6881 if (!visit(Val.getStructField(FieldIdx), FieldTy, FieldOffset)) 6882 return false; 6883 ++FieldIdx; 6884 } 6885 6886 return true; 6887 } 6888 6889 bool visitArray(const APValue &Val, QualType Ty, CharUnits Offset) { 6890 const auto *CAT = 6891 dyn_cast_or_null<ConstantArrayType>(Ty->getAsArrayTypeUnsafe()); 6892 if (!CAT) 6893 return false; 6894 6895 CharUnits ElemWidth = Info.Ctx.getTypeSizeInChars(CAT->getElementType()); 6896 unsigned NumInitializedElts = Val.getArrayInitializedElts(); 6897 unsigned ArraySize = Val.getArraySize(); 6898 // First, initialize the initialized elements. 6899 for (unsigned I = 0; I != NumInitializedElts; ++I) { 6900 const APValue &SubObj = Val.getArrayInitializedElt(I); 6901 if (!visit(SubObj, CAT->getElementType(), Offset + I * ElemWidth)) 6902 return false; 6903 } 6904 6905 // Next, initialize the rest of the array using the filler. 6906 if (Val.hasArrayFiller()) { 6907 const APValue &Filler = Val.getArrayFiller(); 6908 for (unsigned I = NumInitializedElts; I != ArraySize; ++I) { 6909 if (!visit(Filler, CAT->getElementType(), Offset + I * ElemWidth)) 6910 return false; 6911 } 6912 } 6913 6914 return true; 6915 } 6916 6917 bool visitInt(const APSInt &Val, QualType Ty, CharUnits Offset) { 6918 APSInt AdjustedVal = Val; 6919 unsigned Width = AdjustedVal.getBitWidth(); 6920 if (Ty->isBooleanType()) { 6921 Width = Info.Ctx.getTypeSize(Ty); 6922 AdjustedVal = AdjustedVal.extend(Width); 6923 } 6924 6925 SmallVector<unsigned char, 8> Bytes(Width / 8); 6926 llvm::StoreIntToMemory(AdjustedVal, &*Bytes.begin(), Width / 8); 6927 Buffer.writeObject(Offset, Bytes); 6928 return true; 6929 } 6930 6931 bool visitFloat(const APFloat &Val, QualType Ty, CharUnits Offset) { 6932 APSInt AsInt(Val.bitcastToAPInt()); 6933 return visitInt(AsInt, Ty, Offset); 6934 } 6935 6936 public: 6937 static Optional<BitCastBuffer> convert(EvalInfo &Info, const APValue &Src, 6938 const CastExpr *BCE) { 6939 CharUnits DstSize = Info.Ctx.getTypeSizeInChars(BCE->getType()); 6940 APValueToBufferConverter Converter(Info, DstSize, BCE); 6941 if (!Converter.visit(Src, BCE->getSubExpr()->getType())) 6942 return None; 6943 return Converter.Buffer; 6944 } 6945 }; 6946 6947 /// Write an BitCastBuffer into an APValue. 6948 class BufferToAPValueConverter { 6949 EvalInfo &Info; 6950 const BitCastBuffer &Buffer; 6951 const CastExpr *BCE; 6952 6953 BufferToAPValueConverter(EvalInfo &Info, const BitCastBuffer &Buffer, 6954 const CastExpr *BCE) 6955 : Info(Info), Buffer(Buffer), BCE(BCE) {} 6956 6957 // Emit an unsupported bit_cast type error. Sema refuses to build a bit_cast 6958 // with an invalid type, so anything left is a deficiency on our part (FIXME). 6959 // Ideally this will be unreachable. 6960 llvm::NoneType unsupportedType(QualType Ty) { 6961 Info.FFDiag(BCE->getBeginLoc(), 6962 diag::note_constexpr_bit_cast_unsupported_type) 6963 << Ty; 6964 return None; 6965 } 6966 6967 llvm::NoneType unrepresentableValue(QualType Ty, const APSInt &Val) { 6968 Info.FFDiag(BCE->getBeginLoc(), 6969 diag::note_constexpr_bit_cast_unrepresentable_value) 6970 << Ty << toString(Val, /*Radix=*/10); 6971 return None; 6972 } 6973 6974 Optional<APValue> visit(const BuiltinType *T, CharUnits Offset, 6975 const EnumType *EnumSugar = nullptr) { 6976 if (T->isNullPtrType()) { 6977 uint64_t NullValue = Info.Ctx.getTargetNullPointerValue(QualType(T, 0)); 6978 return APValue((Expr *)nullptr, 6979 /*Offset=*/CharUnits::fromQuantity(NullValue), 6980 APValue::NoLValuePath{}, /*IsNullPtr=*/true); 6981 } 6982 6983 CharUnits SizeOf = Info.Ctx.getTypeSizeInChars(T); 6984 6985 // Work around floating point types that contain unused padding bytes. This 6986 // is really just `long double` on x86, which is the only fundamental type 6987 // with padding bytes. 6988 if (T->isRealFloatingType()) { 6989 const llvm::fltSemantics &Semantics = 6990 Info.Ctx.getFloatTypeSemantics(QualType(T, 0)); 6991 unsigned NumBits = llvm::APFloatBase::getSizeInBits(Semantics); 6992 assert(NumBits % 8 == 0); 6993 CharUnits NumBytes = CharUnits::fromQuantity(NumBits / 8); 6994 if (NumBytes != SizeOf) 6995 SizeOf = NumBytes; 6996 } 6997 6998 SmallVector<uint8_t, 8> Bytes; 6999 if (!Buffer.readObject(Offset, SizeOf, Bytes)) { 7000 // If this is std::byte or unsigned char, then its okay to store an 7001 // indeterminate value. 7002 bool IsStdByte = EnumSugar && EnumSugar->isStdByteType(); 7003 bool IsUChar = 7004 !EnumSugar && (T->isSpecificBuiltinType(BuiltinType::UChar) || 7005 T->isSpecificBuiltinType(BuiltinType::Char_U)); 7006 if (!IsStdByte && !IsUChar) { 7007 QualType DisplayType(EnumSugar ? (const Type *)EnumSugar : T, 0); 7008 Info.FFDiag(BCE->getExprLoc(), 7009 diag::note_constexpr_bit_cast_indet_dest) 7010 << DisplayType << Info.Ctx.getLangOpts().CharIsSigned; 7011 return None; 7012 } 7013 7014 return APValue::IndeterminateValue(); 7015 } 7016 7017 APSInt Val(SizeOf.getQuantity() * Info.Ctx.getCharWidth(), true); 7018 llvm::LoadIntFromMemory(Val, &*Bytes.begin(), Bytes.size()); 7019 7020 if (T->isIntegralOrEnumerationType()) { 7021 Val.setIsSigned(T->isSignedIntegerOrEnumerationType()); 7022 7023 unsigned IntWidth = Info.Ctx.getIntWidth(QualType(T, 0)); 7024 if (IntWidth != Val.getBitWidth()) { 7025 APSInt Truncated = Val.trunc(IntWidth); 7026 if (Truncated.extend(Val.getBitWidth()) != Val) 7027 return unrepresentableValue(QualType(T, 0), Val); 7028 Val = Truncated; 7029 } 7030 7031 return APValue(Val); 7032 } 7033 7034 if (T->isRealFloatingType()) { 7035 const llvm::fltSemantics &Semantics = 7036 Info.Ctx.getFloatTypeSemantics(QualType(T, 0)); 7037 return APValue(APFloat(Semantics, Val)); 7038 } 7039 7040 return unsupportedType(QualType(T, 0)); 7041 } 7042 7043 Optional<APValue> visit(const RecordType *RTy, CharUnits Offset) { 7044 const RecordDecl *RD = RTy->getAsRecordDecl(); 7045 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 7046 7047 unsigned NumBases = 0; 7048 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) 7049 NumBases = CXXRD->getNumBases(); 7050 7051 APValue ResultVal(APValue::UninitStruct(), NumBases, 7052 std::distance(RD->field_begin(), RD->field_end())); 7053 7054 // Visit the base classes. 7055 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) { 7056 for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) { 7057 const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I]; 7058 CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl(); 7059 if (BaseDecl->isEmpty() || 7060 Info.Ctx.getASTRecordLayout(BaseDecl).getNonVirtualSize().isZero()) 7061 continue; 7062 7063 Optional<APValue> SubObj = visitType( 7064 BS.getType(), Layout.getBaseClassOffset(BaseDecl) + Offset); 7065 if (!SubObj) 7066 return None; 7067 ResultVal.getStructBase(I) = *SubObj; 7068 } 7069 } 7070 7071 // Visit the fields. 7072 unsigned FieldIdx = 0; 7073 for (FieldDecl *FD : RD->fields()) { 7074 // FIXME: We don't currently support bit-fields. A lot of the logic for 7075 // this is in CodeGen, so we need to factor it around. 7076 if (FD->isBitField()) { 7077 Info.FFDiag(BCE->getBeginLoc(), 7078 diag::note_constexpr_bit_cast_unsupported_bitfield); 7079 return None; 7080 } 7081 7082 uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx); 7083 assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0); 7084 7085 CharUnits FieldOffset = 7086 CharUnits::fromQuantity(FieldOffsetBits / Info.Ctx.getCharWidth()) + 7087 Offset; 7088 QualType FieldTy = FD->getType(); 7089 Optional<APValue> SubObj = visitType(FieldTy, FieldOffset); 7090 if (!SubObj) 7091 return None; 7092 ResultVal.getStructField(FieldIdx) = *SubObj; 7093 ++FieldIdx; 7094 } 7095 7096 return ResultVal; 7097 } 7098 7099 Optional<APValue> visit(const EnumType *Ty, CharUnits Offset) { 7100 QualType RepresentationType = Ty->getDecl()->getIntegerType(); 7101 assert(!RepresentationType.isNull() && 7102 "enum forward decl should be caught by Sema"); 7103 const auto *AsBuiltin = 7104 RepresentationType.getCanonicalType()->castAs<BuiltinType>(); 7105 // Recurse into the underlying type. Treat std::byte transparently as 7106 // unsigned char. 7107 return visit(AsBuiltin, Offset, /*EnumTy=*/Ty); 7108 } 7109 7110 Optional<APValue> visit(const ConstantArrayType *Ty, CharUnits Offset) { 7111 size_t Size = Ty->getSize().getLimitedValue(); 7112 CharUnits ElementWidth = Info.Ctx.getTypeSizeInChars(Ty->getElementType()); 7113 7114 APValue ArrayValue(APValue::UninitArray(), Size, Size); 7115 for (size_t I = 0; I != Size; ++I) { 7116 Optional<APValue> ElementValue = 7117 visitType(Ty->getElementType(), Offset + I * ElementWidth); 7118 if (!ElementValue) 7119 return None; 7120 ArrayValue.getArrayInitializedElt(I) = std::move(*ElementValue); 7121 } 7122 7123 return ArrayValue; 7124 } 7125 7126 Optional<APValue> visit(const Type *Ty, CharUnits Offset) { 7127 return unsupportedType(QualType(Ty, 0)); 7128 } 7129 7130 Optional<APValue> visitType(QualType Ty, CharUnits Offset) { 7131 QualType Can = Ty.getCanonicalType(); 7132 7133 switch (Can->getTypeClass()) { 7134 #define TYPE(Class, Base) \ 7135 case Type::Class: \ 7136 return visit(cast<Class##Type>(Can.getTypePtr()), Offset); 7137 #define ABSTRACT_TYPE(Class, Base) 7138 #define NON_CANONICAL_TYPE(Class, Base) \ 7139 case Type::Class: \ 7140 llvm_unreachable("non-canonical type should be impossible!"); 7141 #define DEPENDENT_TYPE(Class, Base) \ 7142 case Type::Class: \ 7143 llvm_unreachable( \ 7144 "dependent types aren't supported in the constant evaluator!"); 7145 #define NON_CANONICAL_UNLESS_DEPENDENT(Class, Base) \ 7146 case Type::Class: \ 7147 llvm_unreachable("either dependent or not canonical!"); 7148 #include "clang/AST/TypeNodes.inc" 7149 } 7150 llvm_unreachable("Unhandled Type::TypeClass"); 7151 } 7152 7153 public: 7154 // Pull out a full value of type DstType. 7155 static Optional<APValue> convert(EvalInfo &Info, BitCastBuffer &Buffer, 7156 const CastExpr *BCE) { 7157 BufferToAPValueConverter Converter(Info, Buffer, BCE); 7158 return Converter.visitType(BCE->getType(), CharUnits::fromQuantity(0)); 7159 } 7160 }; 7161 7162 static bool checkBitCastConstexprEligibilityType(SourceLocation Loc, 7163 QualType Ty, EvalInfo *Info, 7164 const ASTContext &Ctx, 7165 bool CheckingDest) { 7166 Ty = Ty.getCanonicalType(); 7167 7168 auto diag = [&](int Reason) { 7169 if (Info) 7170 Info->FFDiag(Loc, diag::note_constexpr_bit_cast_invalid_type) 7171 << CheckingDest << (Reason == 4) << Reason; 7172 return false; 7173 }; 7174 auto note = [&](int Construct, QualType NoteTy, SourceLocation NoteLoc) { 7175 if (Info) 7176 Info->Note(NoteLoc, diag::note_constexpr_bit_cast_invalid_subtype) 7177 << NoteTy << Construct << Ty; 7178 return false; 7179 }; 7180 7181 if (Ty->isUnionType()) 7182 return diag(0); 7183 if (Ty->isPointerType()) 7184 return diag(1); 7185 if (Ty->isMemberPointerType()) 7186 return diag(2); 7187 if (Ty.isVolatileQualified()) 7188 return diag(3); 7189 7190 if (RecordDecl *Record = Ty->getAsRecordDecl()) { 7191 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(Record)) { 7192 for (CXXBaseSpecifier &BS : CXXRD->bases()) 7193 if (!checkBitCastConstexprEligibilityType(Loc, BS.getType(), Info, Ctx, 7194 CheckingDest)) 7195 return note(1, BS.getType(), BS.getBeginLoc()); 7196 } 7197 for (FieldDecl *FD : Record->fields()) { 7198 if (FD->getType()->isReferenceType()) 7199 return diag(4); 7200 if (!checkBitCastConstexprEligibilityType(Loc, FD->getType(), Info, Ctx, 7201 CheckingDest)) 7202 return note(0, FD->getType(), FD->getBeginLoc()); 7203 } 7204 } 7205 7206 if (Ty->isArrayType() && 7207 !checkBitCastConstexprEligibilityType(Loc, Ctx.getBaseElementType(Ty), 7208 Info, Ctx, CheckingDest)) 7209 return false; 7210 7211 return true; 7212 } 7213 7214 static bool checkBitCastConstexprEligibility(EvalInfo *Info, 7215 const ASTContext &Ctx, 7216 const CastExpr *BCE) { 7217 bool DestOK = checkBitCastConstexprEligibilityType( 7218 BCE->getBeginLoc(), BCE->getType(), Info, Ctx, true); 7219 bool SourceOK = DestOK && checkBitCastConstexprEligibilityType( 7220 BCE->getBeginLoc(), 7221 BCE->getSubExpr()->getType(), Info, Ctx, false); 7222 return SourceOK; 7223 } 7224 7225 static bool handleLValueToRValueBitCast(EvalInfo &Info, APValue &DestValue, 7226 APValue &SourceValue, 7227 const CastExpr *BCE) { 7228 assert(CHAR_BIT == 8 && Info.Ctx.getTargetInfo().getCharWidth() == 8 && 7229 "no host or target supports non 8-bit chars"); 7230 assert(SourceValue.isLValue() && 7231 "LValueToRValueBitcast requires an lvalue operand!"); 7232 7233 if (!checkBitCastConstexprEligibility(&Info, Info.Ctx, BCE)) 7234 return false; 7235 7236 LValue SourceLValue; 7237 APValue SourceRValue; 7238 SourceLValue.setFrom(Info.Ctx, SourceValue); 7239 if (!handleLValueToRValueConversion( 7240 Info, BCE, BCE->getSubExpr()->getType().withConst(), SourceLValue, 7241 SourceRValue, /*WantObjectRepresentation=*/true)) 7242 return false; 7243 7244 // Read out SourceValue into a char buffer. 7245 Optional<BitCastBuffer> Buffer = 7246 APValueToBufferConverter::convert(Info, SourceRValue, BCE); 7247 if (!Buffer) 7248 return false; 7249 7250 // Write out the buffer into a new APValue. 7251 Optional<APValue> MaybeDestValue = 7252 BufferToAPValueConverter::convert(Info, *Buffer, BCE); 7253 if (!MaybeDestValue) 7254 return false; 7255 7256 DestValue = std::move(*MaybeDestValue); 7257 return true; 7258 } 7259 7260 template <class Derived> 7261 class ExprEvaluatorBase 7262 : public ConstStmtVisitor<Derived, bool> { 7263 private: 7264 Derived &getDerived() { return static_cast<Derived&>(*this); } 7265 bool DerivedSuccess(const APValue &V, const Expr *E) { 7266 return getDerived().Success(V, E); 7267 } 7268 bool DerivedZeroInitialization(const Expr *E) { 7269 return getDerived().ZeroInitialization(E); 7270 } 7271 7272 // Check whether a conditional operator with a non-constant condition is a 7273 // potential constant expression. If neither arm is a potential constant 7274 // expression, then the conditional operator is not either. 7275 template<typename ConditionalOperator> 7276 void CheckPotentialConstantConditional(const ConditionalOperator *E) { 7277 assert(Info.checkingPotentialConstantExpression()); 7278 7279 // Speculatively evaluate both arms. 7280 SmallVector<PartialDiagnosticAt, 8> Diag; 7281 { 7282 SpeculativeEvaluationRAII Speculate(Info, &Diag); 7283 StmtVisitorTy::Visit(E->getFalseExpr()); 7284 if (Diag.empty()) 7285 return; 7286 } 7287 7288 { 7289 SpeculativeEvaluationRAII Speculate(Info, &Diag); 7290 Diag.clear(); 7291 StmtVisitorTy::Visit(E->getTrueExpr()); 7292 if (Diag.empty()) 7293 return; 7294 } 7295 7296 Error(E, diag::note_constexpr_conditional_never_const); 7297 } 7298 7299 7300 template<typename ConditionalOperator> 7301 bool HandleConditionalOperator(const ConditionalOperator *E) { 7302 bool BoolResult; 7303 if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) { 7304 if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) { 7305 CheckPotentialConstantConditional(E); 7306 return false; 7307 } 7308 if (Info.noteFailure()) { 7309 StmtVisitorTy::Visit(E->getTrueExpr()); 7310 StmtVisitorTy::Visit(E->getFalseExpr()); 7311 } 7312 return false; 7313 } 7314 7315 Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr(); 7316 return StmtVisitorTy::Visit(EvalExpr); 7317 } 7318 7319 protected: 7320 EvalInfo &Info; 7321 typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy; 7322 typedef ExprEvaluatorBase ExprEvaluatorBaseTy; 7323 7324 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { 7325 return Info.CCEDiag(E, D); 7326 } 7327 7328 bool ZeroInitialization(const Expr *E) { return Error(E); } 7329 7330 public: 7331 ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {} 7332 7333 EvalInfo &getEvalInfo() { return Info; } 7334 7335 /// Report an evaluation error. This should only be called when an error is 7336 /// first discovered. When propagating an error, just return false. 7337 bool Error(const Expr *E, diag::kind D) { 7338 Info.FFDiag(E, D); 7339 return false; 7340 } 7341 bool Error(const Expr *E) { 7342 return Error(E, diag::note_invalid_subexpr_in_const_expr); 7343 } 7344 7345 bool VisitStmt(const Stmt *) { 7346 llvm_unreachable("Expression evaluator should not be called on stmts"); 7347 } 7348 bool VisitExpr(const Expr *E) { 7349 return Error(E); 7350 } 7351 7352 bool VisitConstantExpr(const ConstantExpr *E) { 7353 if (E->hasAPValueResult()) 7354 return DerivedSuccess(E->getAPValueResult(), E); 7355 7356 return StmtVisitorTy::Visit(E->getSubExpr()); 7357 } 7358 7359 bool VisitParenExpr(const ParenExpr *E) 7360 { return StmtVisitorTy::Visit(E->getSubExpr()); } 7361 bool VisitUnaryExtension(const UnaryOperator *E) 7362 { return StmtVisitorTy::Visit(E->getSubExpr()); } 7363 bool VisitUnaryPlus(const UnaryOperator *E) 7364 { return StmtVisitorTy::Visit(E->getSubExpr()); } 7365 bool VisitChooseExpr(const ChooseExpr *E) 7366 { return StmtVisitorTy::Visit(E->getChosenSubExpr()); } 7367 bool VisitGenericSelectionExpr(const GenericSelectionExpr *E) 7368 { return StmtVisitorTy::Visit(E->getResultExpr()); } 7369 bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E) 7370 { return StmtVisitorTy::Visit(E->getReplacement()); } 7371 bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) { 7372 TempVersionRAII RAII(*Info.CurrentCall); 7373 SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope); 7374 return StmtVisitorTy::Visit(E->getExpr()); 7375 } 7376 bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) { 7377 TempVersionRAII RAII(*Info.CurrentCall); 7378 // The initializer may not have been parsed yet, or might be erroneous. 7379 if (!E->getExpr()) 7380 return Error(E); 7381 SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope); 7382 return StmtVisitorTy::Visit(E->getExpr()); 7383 } 7384 7385 bool VisitExprWithCleanups(const ExprWithCleanups *E) { 7386 FullExpressionRAII Scope(Info); 7387 return StmtVisitorTy::Visit(E->getSubExpr()) && Scope.destroy(); 7388 } 7389 7390 // Temporaries are registered when created, so we don't care about 7391 // CXXBindTemporaryExpr. 7392 bool VisitCXXBindTemporaryExpr(const CXXBindTemporaryExpr *E) { 7393 return StmtVisitorTy::Visit(E->getSubExpr()); 7394 } 7395 7396 bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) { 7397 CCEDiag(E, diag::note_constexpr_invalid_cast) << 0; 7398 return static_cast<Derived*>(this)->VisitCastExpr(E); 7399 } 7400 bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) { 7401 if (!Info.Ctx.getLangOpts().CPlusPlus20) 7402 CCEDiag(E, diag::note_constexpr_invalid_cast) << 1; 7403 return static_cast<Derived*>(this)->VisitCastExpr(E); 7404 } 7405 bool VisitBuiltinBitCastExpr(const BuiltinBitCastExpr *E) { 7406 return static_cast<Derived*>(this)->VisitCastExpr(E); 7407 } 7408 7409 bool VisitBinaryOperator(const BinaryOperator *E) { 7410 switch (E->getOpcode()) { 7411 default: 7412 return Error(E); 7413 7414 case BO_Comma: 7415 VisitIgnoredValue(E->getLHS()); 7416 return StmtVisitorTy::Visit(E->getRHS()); 7417 7418 case BO_PtrMemD: 7419 case BO_PtrMemI: { 7420 LValue Obj; 7421 if (!HandleMemberPointerAccess(Info, E, Obj)) 7422 return false; 7423 APValue Result; 7424 if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result)) 7425 return false; 7426 return DerivedSuccess(Result, E); 7427 } 7428 } 7429 } 7430 7431 bool VisitCXXRewrittenBinaryOperator(const CXXRewrittenBinaryOperator *E) { 7432 return StmtVisitorTy::Visit(E->getSemanticForm()); 7433 } 7434 7435 bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) { 7436 // Evaluate and cache the common expression. We treat it as a temporary, 7437 // even though it's not quite the same thing. 7438 LValue CommonLV; 7439 if (!Evaluate(Info.CurrentCall->createTemporary( 7440 E->getOpaqueValue(), 7441 getStorageType(Info.Ctx, E->getOpaqueValue()), 7442 ScopeKind::FullExpression, CommonLV), 7443 Info, E->getCommon())) 7444 return false; 7445 7446 return HandleConditionalOperator(E); 7447 } 7448 7449 bool VisitConditionalOperator(const ConditionalOperator *E) { 7450 bool IsBcpCall = false; 7451 // If the condition (ignoring parens) is a __builtin_constant_p call, 7452 // the result is a constant expression if it can be folded without 7453 // side-effects. This is an important GNU extension. See GCC PR38377 7454 // for discussion. 7455 if (const CallExpr *CallCE = 7456 dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts())) 7457 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p) 7458 IsBcpCall = true; 7459 7460 // Always assume __builtin_constant_p(...) ? ... : ... is a potential 7461 // constant expression; we can't check whether it's potentially foldable. 7462 // FIXME: We should instead treat __builtin_constant_p as non-constant if 7463 // it would return 'false' in this mode. 7464 if (Info.checkingPotentialConstantExpression() && IsBcpCall) 7465 return false; 7466 7467 FoldConstant Fold(Info, IsBcpCall); 7468 if (!HandleConditionalOperator(E)) { 7469 Fold.keepDiagnostics(); 7470 return false; 7471 } 7472 7473 return true; 7474 } 7475 7476 bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) { 7477 if (APValue *Value = Info.CurrentCall->getCurrentTemporary(E)) 7478 return DerivedSuccess(*Value, E); 7479 7480 const Expr *Source = E->getSourceExpr(); 7481 if (!Source) 7482 return Error(E); 7483 if (Source == E) { // sanity checking. 7484 assert(0 && "OpaqueValueExpr recursively refers to itself"); 7485 return Error(E); 7486 } 7487 return StmtVisitorTy::Visit(Source); 7488 } 7489 7490 bool VisitPseudoObjectExpr(const PseudoObjectExpr *E) { 7491 for (const Expr *SemE : E->semantics()) { 7492 if (auto *OVE = dyn_cast<OpaqueValueExpr>(SemE)) { 7493 // FIXME: We can't handle the case where an OpaqueValueExpr is also the 7494 // result expression: there could be two different LValues that would 7495 // refer to the same object in that case, and we can't model that. 7496 if (SemE == E->getResultExpr()) 7497 return Error(E); 7498 7499 // Unique OVEs get evaluated if and when we encounter them when 7500 // emitting the rest of the semantic form, rather than eagerly. 7501 if (OVE->isUnique()) 7502 continue; 7503 7504 LValue LV; 7505 if (!Evaluate(Info.CurrentCall->createTemporary( 7506 OVE, getStorageType(Info.Ctx, OVE), 7507 ScopeKind::FullExpression, LV), 7508 Info, OVE->getSourceExpr())) 7509 return false; 7510 } else if (SemE == E->getResultExpr()) { 7511 if (!StmtVisitorTy::Visit(SemE)) 7512 return false; 7513 } else { 7514 if (!EvaluateIgnoredValue(Info, SemE)) 7515 return false; 7516 } 7517 } 7518 return true; 7519 } 7520 7521 bool VisitCallExpr(const CallExpr *E) { 7522 APValue Result; 7523 if (!handleCallExpr(E, Result, nullptr)) 7524 return false; 7525 return DerivedSuccess(Result, E); 7526 } 7527 7528 bool handleCallExpr(const CallExpr *E, APValue &Result, 7529 const LValue *ResultSlot) { 7530 CallScopeRAII CallScope(Info); 7531 7532 const Expr *Callee = E->getCallee()->IgnoreParens(); 7533 QualType CalleeType = Callee->getType(); 7534 7535 const FunctionDecl *FD = nullptr; 7536 LValue *This = nullptr, ThisVal; 7537 auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs()); 7538 bool HasQualifier = false; 7539 7540 CallRef Call; 7541 7542 // Extract function decl and 'this' pointer from the callee. 7543 if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) { 7544 const CXXMethodDecl *Member = nullptr; 7545 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) { 7546 // Explicit bound member calls, such as x.f() or p->g(); 7547 if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal)) 7548 return false; 7549 Member = dyn_cast<CXXMethodDecl>(ME->getMemberDecl()); 7550 if (!Member) 7551 return Error(Callee); 7552 This = &ThisVal; 7553 HasQualifier = ME->hasQualifier(); 7554 } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) { 7555 // Indirect bound member calls ('.*' or '->*'). 7556 const ValueDecl *D = 7557 HandleMemberPointerAccess(Info, BE, ThisVal, false); 7558 if (!D) 7559 return false; 7560 Member = dyn_cast<CXXMethodDecl>(D); 7561 if (!Member) 7562 return Error(Callee); 7563 This = &ThisVal; 7564 } else if (const auto *PDE = dyn_cast<CXXPseudoDestructorExpr>(Callee)) { 7565 if (!Info.getLangOpts().CPlusPlus20) 7566 Info.CCEDiag(PDE, diag::note_constexpr_pseudo_destructor); 7567 return EvaluateObjectArgument(Info, PDE->getBase(), ThisVal) && 7568 HandleDestruction(Info, PDE, ThisVal, PDE->getDestroyedType()); 7569 } else 7570 return Error(Callee); 7571 FD = Member; 7572 } else if (CalleeType->isFunctionPointerType()) { 7573 LValue CalleeLV; 7574 if (!EvaluatePointer(Callee, CalleeLV, Info)) 7575 return false; 7576 7577 if (!CalleeLV.getLValueOffset().isZero()) 7578 return Error(Callee); 7579 FD = dyn_cast_or_null<FunctionDecl>( 7580 CalleeLV.getLValueBase().dyn_cast<const ValueDecl *>()); 7581 if (!FD) 7582 return Error(Callee); 7583 // Don't call function pointers which have been cast to some other type. 7584 // Per DR (no number yet), the caller and callee can differ in noexcept. 7585 if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec( 7586 CalleeType->getPointeeType(), FD->getType())) { 7587 return Error(E); 7588 } 7589 7590 // For an (overloaded) assignment expression, evaluate the RHS before the 7591 // LHS. 7592 auto *OCE = dyn_cast<CXXOperatorCallExpr>(E); 7593 if (OCE && OCE->isAssignmentOp()) { 7594 assert(Args.size() == 2 && "wrong number of arguments in assignment"); 7595 Call = Info.CurrentCall->createCall(FD); 7596 if (!EvaluateArgs(isa<CXXMethodDecl>(FD) ? Args.slice(1) : Args, Call, 7597 Info, FD, /*RightToLeft=*/true)) 7598 return false; 7599 } 7600 7601 // Overloaded operator calls to member functions are represented as normal 7602 // calls with '*this' as the first argument. 7603 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); 7604 if (MD && !MD->isStatic()) { 7605 // FIXME: When selecting an implicit conversion for an overloaded 7606 // operator delete, we sometimes try to evaluate calls to conversion 7607 // operators without a 'this' parameter! 7608 if (Args.empty()) 7609 return Error(E); 7610 7611 if (!EvaluateObjectArgument(Info, Args[0], ThisVal)) 7612 return false; 7613 This = &ThisVal; 7614 Args = Args.slice(1); 7615 } else if (MD && MD->isLambdaStaticInvoker()) { 7616 // Map the static invoker for the lambda back to the call operator. 7617 // Conveniently, we don't have to slice out the 'this' argument (as is 7618 // being done for the non-static case), since a static member function 7619 // doesn't have an implicit argument passed in. 7620 const CXXRecordDecl *ClosureClass = MD->getParent(); 7621 assert( 7622 ClosureClass->captures_begin() == ClosureClass->captures_end() && 7623 "Number of captures must be zero for conversion to function-ptr"); 7624 7625 const CXXMethodDecl *LambdaCallOp = 7626 ClosureClass->getLambdaCallOperator(); 7627 7628 // Set 'FD', the function that will be called below, to the call 7629 // operator. If the closure object represents a generic lambda, find 7630 // the corresponding specialization of the call operator. 7631 7632 if (ClosureClass->isGenericLambda()) { 7633 assert(MD->isFunctionTemplateSpecialization() && 7634 "A generic lambda's static-invoker function must be a " 7635 "template specialization"); 7636 const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs(); 7637 FunctionTemplateDecl *CallOpTemplate = 7638 LambdaCallOp->getDescribedFunctionTemplate(); 7639 void *InsertPos = nullptr; 7640 FunctionDecl *CorrespondingCallOpSpecialization = 7641 CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos); 7642 assert(CorrespondingCallOpSpecialization && 7643 "We must always have a function call operator specialization " 7644 "that corresponds to our static invoker specialization"); 7645 FD = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization); 7646 } else 7647 FD = LambdaCallOp; 7648 } else if (FD->isReplaceableGlobalAllocationFunction()) { 7649 if (FD->getDeclName().getCXXOverloadedOperator() == OO_New || 7650 FD->getDeclName().getCXXOverloadedOperator() == OO_Array_New) { 7651 LValue Ptr; 7652 if (!HandleOperatorNewCall(Info, E, Ptr)) 7653 return false; 7654 Ptr.moveInto(Result); 7655 return CallScope.destroy(); 7656 } else { 7657 return HandleOperatorDeleteCall(Info, E) && CallScope.destroy(); 7658 } 7659 } 7660 } else 7661 return Error(E); 7662 7663 // Evaluate the arguments now if we've not already done so. 7664 if (!Call) { 7665 Call = Info.CurrentCall->createCall(FD); 7666 if (!EvaluateArgs(Args, Call, Info, FD)) 7667 return false; 7668 } 7669 7670 SmallVector<QualType, 4> CovariantAdjustmentPath; 7671 if (This) { 7672 auto *NamedMember = dyn_cast<CXXMethodDecl>(FD); 7673 if (NamedMember && NamedMember->isVirtual() && !HasQualifier) { 7674 // Perform virtual dispatch, if necessary. 7675 FD = HandleVirtualDispatch(Info, E, *This, NamedMember, 7676 CovariantAdjustmentPath); 7677 if (!FD) 7678 return false; 7679 } else { 7680 // Check that the 'this' pointer points to an object of the right type. 7681 // FIXME: If this is an assignment operator call, we may need to change 7682 // the active union member before we check this. 7683 if (!checkNonVirtualMemberCallThisPointer(Info, E, *This, NamedMember)) 7684 return false; 7685 } 7686 } 7687 7688 // Destructor calls are different enough that they have their own codepath. 7689 if (auto *DD = dyn_cast<CXXDestructorDecl>(FD)) { 7690 assert(This && "no 'this' pointer for destructor call"); 7691 return HandleDestruction(Info, E, *This, 7692 Info.Ctx.getRecordType(DD->getParent())) && 7693 CallScope.destroy(); 7694 } 7695 7696 const FunctionDecl *Definition = nullptr; 7697 Stmt *Body = FD->getBody(Definition); 7698 7699 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body) || 7700 !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Call, 7701 Body, Info, Result, ResultSlot)) 7702 return false; 7703 7704 if (!CovariantAdjustmentPath.empty() && 7705 !HandleCovariantReturnAdjustment(Info, E, Result, 7706 CovariantAdjustmentPath)) 7707 return false; 7708 7709 return CallScope.destroy(); 7710 } 7711 7712 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { 7713 return StmtVisitorTy::Visit(E->getInitializer()); 7714 } 7715 bool VisitInitListExpr(const InitListExpr *E) { 7716 if (E->getNumInits() == 0) 7717 return DerivedZeroInitialization(E); 7718 if (E->getNumInits() == 1) 7719 return StmtVisitorTy::Visit(E->getInit(0)); 7720 return Error(E); 7721 } 7722 bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) { 7723 return DerivedZeroInitialization(E); 7724 } 7725 bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) { 7726 return DerivedZeroInitialization(E); 7727 } 7728 bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) { 7729 return DerivedZeroInitialization(E); 7730 } 7731 7732 /// A member expression where the object is a prvalue is itself a prvalue. 7733 bool VisitMemberExpr(const MemberExpr *E) { 7734 assert(!Info.Ctx.getLangOpts().CPlusPlus11 && 7735 "missing temporary materialization conversion"); 7736 assert(!E->isArrow() && "missing call to bound member function?"); 7737 7738 APValue Val; 7739 if (!Evaluate(Val, Info, E->getBase())) 7740 return false; 7741 7742 QualType BaseTy = E->getBase()->getType(); 7743 7744 const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl()); 7745 if (!FD) return Error(E); 7746 assert(!FD->getType()->isReferenceType() && "prvalue reference?"); 7747 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() == 7748 FD->getParent()->getCanonicalDecl() && "record / field mismatch"); 7749 7750 // Note: there is no lvalue base here. But this case should only ever 7751 // happen in C or in C++98, where we cannot be evaluating a constexpr 7752 // constructor, which is the only case the base matters. 7753 CompleteObject Obj(APValue::LValueBase(), &Val, BaseTy); 7754 SubobjectDesignator Designator(BaseTy); 7755 Designator.addDeclUnchecked(FD); 7756 7757 APValue Result; 7758 return extractSubobject(Info, E, Obj, Designator, Result) && 7759 DerivedSuccess(Result, E); 7760 } 7761 7762 bool VisitExtVectorElementExpr(const ExtVectorElementExpr *E) { 7763 APValue Val; 7764 if (!Evaluate(Val, Info, E->getBase())) 7765 return false; 7766 7767 if (Val.isVector()) { 7768 SmallVector<uint32_t, 4> Indices; 7769 E->getEncodedElementAccess(Indices); 7770 if (Indices.size() == 1) { 7771 // Return scalar. 7772 return DerivedSuccess(Val.getVectorElt(Indices[0]), E); 7773 } else { 7774 // Construct new APValue vector. 7775 SmallVector<APValue, 4> Elts; 7776 for (unsigned I = 0; I < Indices.size(); ++I) { 7777 Elts.push_back(Val.getVectorElt(Indices[I])); 7778 } 7779 APValue VecResult(Elts.data(), Indices.size()); 7780 return DerivedSuccess(VecResult, E); 7781 } 7782 } 7783 7784 return false; 7785 } 7786 7787 bool VisitCastExpr(const CastExpr *E) { 7788 switch (E->getCastKind()) { 7789 default: 7790 break; 7791 7792 case CK_AtomicToNonAtomic: { 7793 APValue AtomicVal; 7794 // This does not need to be done in place even for class/array types: 7795 // atomic-to-non-atomic conversion implies copying the object 7796 // representation. 7797 if (!Evaluate(AtomicVal, Info, E->getSubExpr())) 7798 return false; 7799 return DerivedSuccess(AtomicVal, E); 7800 } 7801 7802 case CK_NoOp: 7803 case CK_UserDefinedConversion: 7804 return StmtVisitorTy::Visit(E->getSubExpr()); 7805 7806 case CK_LValueToRValue: { 7807 LValue LVal; 7808 if (!EvaluateLValue(E->getSubExpr(), LVal, Info)) 7809 return false; 7810 APValue RVal; 7811 // Note, we use the subexpression's type in order to retain cv-qualifiers. 7812 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(), 7813 LVal, RVal)) 7814 return false; 7815 return DerivedSuccess(RVal, E); 7816 } 7817 case CK_LValueToRValueBitCast: { 7818 APValue DestValue, SourceValue; 7819 if (!Evaluate(SourceValue, Info, E->getSubExpr())) 7820 return false; 7821 if (!handleLValueToRValueBitCast(Info, DestValue, SourceValue, E)) 7822 return false; 7823 return DerivedSuccess(DestValue, E); 7824 } 7825 7826 case CK_AddressSpaceConversion: { 7827 APValue Value; 7828 if (!Evaluate(Value, Info, E->getSubExpr())) 7829 return false; 7830 return DerivedSuccess(Value, E); 7831 } 7832 } 7833 7834 return Error(E); 7835 } 7836 7837 bool VisitUnaryPostInc(const UnaryOperator *UO) { 7838 return VisitUnaryPostIncDec(UO); 7839 } 7840 bool VisitUnaryPostDec(const UnaryOperator *UO) { 7841 return VisitUnaryPostIncDec(UO); 7842 } 7843 bool VisitUnaryPostIncDec(const UnaryOperator *UO) { 7844 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) 7845 return Error(UO); 7846 7847 LValue LVal; 7848 if (!EvaluateLValue(UO->getSubExpr(), LVal, Info)) 7849 return false; 7850 APValue RVal; 7851 if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(), 7852 UO->isIncrementOp(), &RVal)) 7853 return false; 7854 return DerivedSuccess(RVal, UO); 7855 } 7856 7857 bool VisitStmtExpr(const StmtExpr *E) { 7858 // We will have checked the full-expressions inside the statement expression 7859 // when they were completed, and don't need to check them again now. 7860 llvm::SaveAndRestore<bool> NotCheckingForUB( 7861 Info.CheckingForUndefinedBehavior, false); 7862 7863 const CompoundStmt *CS = E->getSubStmt(); 7864 if (CS->body_empty()) 7865 return true; 7866 7867 BlockScopeRAII Scope(Info); 7868 for (CompoundStmt::const_body_iterator BI = CS->body_begin(), 7869 BE = CS->body_end(); 7870 /**/; ++BI) { 7871 if (BI + 1 == BE) { 7872 const Expr *FinalExpr = dyn_cast<Expr>(*BI); 7873 if (!FinalExpr) { 7874 Info.FFDiag((*BI)->getBeginLoc(), 7875 diag::note_constexpr_stmt_expr_unsupported); 7876 return false; 7877 } 7878 return this->Visit(FinalExpr) && Scope.destroy(); 7879 } 7880 7881 APValue ReturnValue; 7882 StmtResult Result = { ReturnValue, nullptr }; 7883 EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI); 7884 if (ESR != ESR_Succeeded) { 7885 // FIXME: If the statement-expression terminated due to 'return', 7886 // 'break', or 'continue', it would be nice to propagate that to 7887 // the outer statement evaluation rather than bailing out. 7888 if (ESR != ESR_Failed) 7889 Info.FFDiag((*BI)->getBeginLoc(), 7890 diag::note_constexpr_stmt_expr_unsupported); 7891 return false; 7892 } 7893 } 7894 7895 llvm_unreachable("Return from function from the loop above."); 7896 } 7897 7898 /// Visit a value which is evaluated, but whose value is ignored. 7899 void VisitIgnoredValue(const Expr *E) { 7900 EvaluateIgnoredValue(Info, E); 7901 } 7902 7903 /// Potentially visit a MemberExpr's base expression. 7904 void VisitIgnoredBaseExpression(const Expr *E) { 7905 // While MSVC doesn't evaluate the base expression, it does diagnose the 7906 // presence of side-effecting behavior. 7907 if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Info.Ctx)) 7908 return; 7909 VisitIgnoredValue(E); 7910 } 7911 }; 7912 7913 } // namespace 7914 7915 //===----------------------------------------------------------------------===// 7916 // Common base class for lvalue and temporary evaluation. 7917 //===----------------------------------------------------------------------===// 7918 namespace { 7919 template<class Derived> 7920 class LValueExprEvaluatorBase 7921 : public ExprEvaluatorBase<Derived> { 7922 protected: 7923 LValue &Result; 7924 bool InvalidBaseOK; 7925 typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy; 7926 typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy; 7927 7928 bool Success(APValue::LValueBase B) { 7929 Result.set(B); 7930 return true; 7931 } 7932 7933 bool evaluatePointer(const Expr *E, LValue &Result) { 7934 return EvaluatePointer(E, Result, this->Info, InvalidBaseOK); 7935 } 7936 7937 public: 7938 LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) 7939 : ExprEvaluatorBaseTy(Info), Result(Result), 7940 InvalidBaseOK(InvalidBaseOK) {} 7941 7942 bool Success(const APValue &V, const Expr *E) { 7943 Result.setFrom(this->Info.Ctx, V); 7944 return true; 7945 } 7946 7947 bool VisitMemberExpr(const MemberExpr *E) { 7948 // Handle non-static data members. 7949 QualType BaseTy; 7950 bool EvalOK; 7951 if (E->isArrow()) { 7952 EvalOK = evaluatePointer(E->getBase(), Result); 7953 BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType(); 7954 } else if (E->getBase()->isPRValue()) { 7955 assert(E->getBase()->getType()->isRecordType()); 7956 EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info); 7957 BaseTy = E->getBase()->getType(); 7958 } else { 7959 EvalOK = this->Visit(E->getBase()); 7960 BaseTy = E->getBase()->getType(); 7961 } 7962 if (!EvalOK) { 7963 if (!InvalidBaseOK) 7964 return false; 7965 Result.setInvalid(E); 7966 return true; 7967 } 7968 7969 const ValueDecl *MD = E->getMemberDecl(); 7970 if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) { 7971 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() == 7972 FD->getParent()->getCanonicalDecl() && "record / field mismatch"); 7973 (void)BaseTy; 7974 if (!HandleLValueMember(this->Info, E, Result, FD)) 7975 return false; 7976 } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) { 7977 if (!HandleLValueIndirectMember(this->Info, E, Result, IFD)) 7978 return false; 7979 } else 7980 return this->Error(E); 7981 7982 if (MD->getType()->isReferenceType()) { 7983 APValue RefValue; 7984 if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result, 7985 RefValue)) 7986 return false; 7987 return Success(RefValue, E); 7988 } 7989 return true; 7990 } 7991 7992 bool VisitBinaryOperator(const BinaryOperator *E) { 7993 switch (E->getOpcode()) { 7994 default: 7995 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 7996 7997 case BO_PtrMemD: 7998 case BO_PtrMemI: 7999 return HandleMemberPointerAccess(this->Info, E, Result); 8000 } 8001 } 8002 8003 bool VisitCastExpr(const CastExpr *E) { 8004 switch (E->getCastKind()) { 8005 default: 8006 return ExprEvaluatorBaseTy::VisitCastExpr(E); 8007 8008 case CK_DerivedToBase: 8009 case CK_UncheckedDerivedToBase: 8010 if (!this->Visit(E->getSubExpr())) 8011 return false; 8012 8013 // Now figure out the necessary offset to add to the base LV to get from 8014 // the derived class to the base class. 8015 return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(), 8016 Result); 8017 } 8018 } 8019 }; 8020 } 8021 8022 //===----------------------------------------------------------------------===// 8023 // LValue Evaluation 8024 // 8025 // This is used for evaluating lvalues (in C and C++), xvalues (in C++11), 8026 // function designators (in C), decl references to void objects (in C), and 8027 // temporaries (if building with -Wno-address-of-temporary). 8028 // 8029 // LValue evaluation produces values comprising a base expression of one of the 8030 // following types: 8031 // - Declarations 8032 // * VarDecl 8033 // * FunctionDecl 8034 // - Literals 8035 // * CompoundLiteralExpr in C (and in global scope in C++) 8036 // * StringLiteral 8037 // * PredefinedExpr 8038 // * ObjCStringLiteralExpr 8039 // * ObjCEncodeExpr 8040 // * AddrLabelExpr 8041 // * BlockExpr 8042 // * CallExpr for a MakeStringConstant builtin 8043 // - typeid(T) expressions, as TypeInfoLValues 8044 // - Locals and temporaries 8045 // * MaterializeTemporaryExpr 8046 // * Any Expr, with a CallIndex indicating the function in which the temporary 8047 // was evaluated, for cases where the MaterializeTemporaryExpr is missing 8048 // from the AST (FIXME). 8049 // * A MaterializeTemporaryExpr that has static storage duration, with no 8050 // CallIndex, for a lifetime-extended temporary. 8051 // * The ConstantExpr that is currently being evaluated during evaluation of an 8052 // immediate invocation. 8053 // plus an offset in bytes. 8054 //===----------------------------------------------------------------------===// 8055 namespace { 8056 class LValueExprEvaluator 8057 : public LValueExprEvaluatorBase<LValueExprEvaluator> { 8058 public: 8059 LValueExprEvaluator(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) : 8060 LValueExprEvaluatorBaseTy(Info, Result, InvalidBaseOK) {} 8061 8062 bool VisitVarDecl(const Expr *E, const VarDecl *VD); 8063 bool VisitUnaryPreIncDec(const UnaryOperator *UO); 8064 8065 bool VisitDeclRefExpr(const DeclRefExpr *E); 8066 bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); } 8067 bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E); 8068 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E); 8069 bool VisitMemberExpr(const MemberExpr *E); 8070 bool VisitStringLiteral(const StringLiteral *E) { return Success(E); } 8071 bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); } 8072 bool VisitCXXTypeidExpr(const CXXTypeidExpr *E); 8073 bool VisitCXXUuidofExpr(const CXXUuidofExpr *E); 8074 bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E); 8075 bool VisitUnaryDeref(const UnaryOperator *E); 8076 bool VisitUnaryReal(const UnaryOperator *E); 8077 bool VisitUnaryImag(const UnaryOperator *E); 8078 bool VisitUnaryPreInc(const UnaryOperator *UO) { 8079 return VisitUnaryPreIncDec(UO); 8080 } 8081 bool VisitUnaryPreDec(const UnaryOperator *UO) { 8082 return VisitUnaryPreIncDec(UO); 8083 } 8084 bool VisitBinAssign(const BinaryOperator *BO); 8085 bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO); 8086 8087 bool VisitCastExpr(const CastExpr *E) { 8088 switch (E->getCastKind()) { 8089 default: 8090 return LValueExprEvaluatorBaseTy::VisitCastExpr(E); 8091 8092 case CK_LValueBitCast: 8093 this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 8094 if (!Visit(E->getSubExpr())) 8095 return false; 8096 Result.Designator.setInvalid(); 8097 return true; 8098 8099 case CK_BaseToDerived: 8100 if (!Visit(E->getSubExpr())) 8101 return false; 8102 return HandleBaseToDerivedCast(Info, E, Result); 8103 8104 case CK_Dynamic: 8105 if (!Visit(E->getSubExpr())) 8106 return false; 8107 return HandleDynamicCast(Info, cast<ExplicitCastExpr>(E), Result); 8108 } 8109 } 8110 }; 8111 } // end anonymous namespace 8112 8113 /// Evaluate an expression as an lvalue. This can be legitimately called on 8114 /// expressions which are not glvalues, in three cases: 8115 /// * function designators in C, and 8116 /// * "extern void" objects 8117 /// * @selector() expressions in Objective-C 8118 static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info, 8119 bool InvalidBaseOK) { 8120 assert(!E->isValueDependent()); 8121 assert(E->isGLValue() || E->getType()->isFunctionType() || 8122 E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E)); 8123 return LValueExprEvaluator(Info, Result, InvalidBaseOK).Visit(E); 8124 } 8125 8126 bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) { 8127 const NamedDecl *D = E->getDecl(); 8128 if (isa<FunctionDecl, MSGuidDecl, TemplateParamObjectDecl>(D)) 8129 return Success(cast<ValueDecl>(D)); 8130 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 8131 return VisitVarDecl(E, VD); 8132 if (const BindingDecl *BD = dyn_cast<BindingDecl>(D)) 8133 return Visit(BD->getBinding()); 8134 return Error(E); 8135 } 8136 8137 8138 bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) { 8139 8140 // If we are within a lambda's call operator, check whether the 'VD' referred 8141 // to within 'E' actually represents a lambda-capture that maps to a 8142 // data-member/field within the closure object, and if so, evaluate to the 8143 // field or what the field refers to. 8144 if (Info.CurrentCall && isLambdaCallOperator(Info.CurrentCall->Callee) && 8145 isa<DeclRefExpr>(E) && 8146 cast<DeclRefExpr>(E)->refersToEnclosingVariableOrCapture()) { 8147 // We don't always have a complete capture-map when checking or inferring if 8148 // the function call operator meets the requirements of a constexpr function 8149 // - but we don't need to evaluate the captures to determine constexprness 8150 // (dcl.constexpr C++17). 8151 if (Info.checkingPotentialConstantExpression()) 8152 return false; 8153 8154 if (auto *FD = Info.CurrentCall->LambdaCaptureFields.lookup(VD)) { 8155 // Start with 'Result' referring to the complete closure object... 8156 Result = *Info.CurrentCall->This; 8157 // ... then update it to refer to the field of the closure object 8158 // that represents the capture. 8159 if (!HandleLValueMember(Info, E, Result, FD)) 8160 return false; 8161 // And if the field is of reference type, update 'Result' to refer to what 8162 // the field refers to. 8163 if (FD->getType()->isReferenceType()) { 8164 APValue RVal; 8165 if (!handleLValueToRValueConversion(Info, E, FD->getType(), Result, 8166 RVal)) 8167 return false; 8168 Result.setFrom(Info.Ctx, RVal); 8169 } 8170 return true; 8171 } 8172 } 8173 8174 CallStackFrame *Frame = nullptr; 8175 unsigned Version = 0; 8176 if (VD->hasLocalStorage()) { 8177 // Only if a local variable was declared in the function currently being 8178 // evaluated, do we expect to be able to find its value in the current 8179 // frame. (Otherwise it was likely declared in an enclosing context and 8180 // could either have a valid evaluatable value (for e.g. a constexpr 8181 // variable) or be ill-formed (and trigger an appropriate evaluation 8182 // diagnostic)). 8183 CallStackFrame *CurrFrame = Info.CurrentCall; 8184 if (CurrFrame->Callee && CurrFrame->Callee->Equals(VD->getDeclContext())) { 8185 // Function parameters are stored in some caller's frame. (Usually the 8186 // immediate caller, but for an inherited constructor they may be more 8187 // distant.) 8188 if (auto *PVD = dyn_cast<ParmVarDecl>(VD)) { 8189 if (CurrFrame->Arguments) { 8190 VD = CurrFrame->Arguments.getOrigParam(PVD); 8191 Frame = 8192 Info.getCallFrameAndDepth(CurrFrame->Arguments.CallIndex).first; 8193 Version = CurrFrame->Arguments.Version; 8194 } 8195 } else { 8196 Frame = CurrFrame; 8197 Version = CurrFrame->getCurrentTemporaryVersion(VD); 8198 } 8199 } 8200 } 8201 8202 if (!VD->getType()->isReferenceType()) { 8203 if (Frame) { 8204 Result.set({VD, Frame->Index, Version}); 8205 return true; 8206 } 8207 return Success(VD); 8208 } 8209 8210 if (!Info.getLangOpts().CPlusPlus11) { 8211 Info.CCEDiag(E, diag::note_constexpr_ltor_non_integral, 1) 8212 << VD << VD->getType(); 8213 Info.Note(VD->getLocation(), diag::note_declared_at); 8214 } 8215 8216 APValue *V; 8217 if (!evaluateVarDeclInit(Info, E, VD, Frame, Version, V)) 8218 return false; 8219 if (!V->hasValue()) { 8220 // FIXME: Is it possible for V to be indeterminate here? If so, we should 8221 // adjust the diagnostic to say that. 8222 if (!Info.checkingPotentialConstantExpression()) 8223 Info.FFDiag(E, diag::note_constexpr_use_uninit_reference); 8224 return false; 8225 } 8226 return Success(*V, E); 8227 } 8228 8229 bool LValueExprEvaluator::VisitMaterializeTemporaryExpr( 8230 const MaterializeTemporaryExpr *E) { 8231 // Walk through the expression to find the materialized temporary itself. 8232 SmallVector<const Expr *, 2> CommaLHSs; 8233 SmallVector<SubobjectAdjustment, 2> Adjustments; 8234 const Expr *Inner = 8235 E->getSubExpr()->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments); 8236 8237 // If we passed any comma operators, evaluate their LHSs. 8238 for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I) 8239 if (!EvaluateIgnoredValue(Info, CommaLHSs[I])) 8240 return false; 8241 8242 // A materialized temporary with static storage duration can appear within the 8243 // result of a constant expression evaluation, so we need to preserve its 8244 // value for use outside this evaluation. 8245 APValue *Value; 8246 if (E->getStorageDuration() == SD_Static) { 8247 // FIXME: What about SD_Thread? 8248 Value = E->getOrCreateValue(true); 8249 *Value = APValue(); 8250 Result.set(E); 8251 } else { 8252 Value = &Info.CurrentCall->createTemporary( 8253 E, E->getType(), 8254 E->getStorageDuration() == SD_FullExpression ? ScopeKind::FullExpression 8255 : ScopeKind::Block, 8256 Result); 8257 } 8258 8259 QualType Type = Inner->getType(); 8260 8261 // Materialize the temporary itself. 8262 if (!EvaluateInPlace(*Value, Info, Result, Inner)) { 8263 *Value = APValue(); 8264 return false; 8265 } 8266 8267 // Adjust our lvalue to refer to the desired subobject. 8268 for (unsigned I = Adjustments.size(); I != 0; /**/) { 8269 --I; 8270 switch (Adjustments[I].Kind) { 8271 case SubobjectAdjustment::DerivedToBaseAdjustment: 8272 if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath, 8273 Type, Result)) 8274 return false; 8275 Type = Adjustments[I].DerivedToBase.BasePath->getType(); 8276 break; 8277 8278 case SubobjectAdjustment::FieldAdjustment: 8279 if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field)) 8280 return false; 8281 Type = Adjustments[I].Field->getType(); 8282 break; 8283 8284 case SubobjectAdjustment::MemberPointerAdjustment: 8285 if (!HandleMemberPointerAccess(this->Info, Type, Result, 8286 Adjustments[I].Ptr.RHS)) 8287 return false; 8288 Type = Adjustments[I].Ptr.MPT->getPointeeType(); 8289 break; 8290 } 8291 } 8292 8293 return true; 8294 } 8295 8296 bool 8297 LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { 8298 assert((!Info.getLangOpts().CPlusPlus || E->isFileScope()) && 8299 "lvalue compound literal in c++?"); 8300 // Defer visiting the literal until the lvalue-to-rvalue conversion. We can 8301 // only see this when folding in C, so there's no standard to follow here. 8302 return Success(E); 8303 } 8304 8305 bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) { 8306 TypeInfoLValue TypeInfo; 8307 8308 if (!E->isPotentiallyEvaluated()) { 8309 if (E->isTypeOperand()) 8310 TypeInfo = TypeInfoLValue(E->getTypeOperand(Info.Ctx).getTypePtr()); 8311 else 8312 TypeInfo = TypeInfoLValue(E->getExprOperand()->getType().getTypePtr()); 8313 } else { 8314 if (!Info.Ctx.getLangOpts().CPlusPlus20) { 8315 Info.CCEDiag(E, diag::note_constexpr_typeid_polymorphic) 8316 << E->getExprOperand()->getType() 8317 << E->getExprOperand()->getSourceRange(); 8318 } 8319 8320 if (!Visit(E->getExprOperand())) 8321 return false; 8322 8323 Optional<DynamicType> DynType = 8324 ComputeDynamicType(Info, E, Result, AK_TypeId); 8325 if (!DynType) 8326 return false; 8327 8328 TypeInfo = 8329 TypeInfoLValue(Info.Ctx.getRecordType(DynType->Type).getTypePtr()); 8330 } 8331 8332 return Success(APValue::LValueBase::getTypeInfo(TypeInfo, E->getType())); 8333 } 8334 8335 bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) { 8336 return Success(E->getGuidDecl()); 8337 } 8338 8339 bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) { 8340 // Handle static data members. 8341 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) { 8342 VisitIgnoredBaseExpression(E->getBase()); 8343 return VisitVarDecl(E, VD); 8344 } 8345 8346 // Handle static member functions. 8347 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) { 8348 if (MD->isStatic()) { 8349 VisitIgnoredBaseExpression(E->getBase()); 8350 return Success(MD); 8351 } 8352 } 8353 8354 // Handle non-static data members. 8355 return LValueExprEvaluatorBaseTy::VisitMemberExpr(E); 8356 } 8357 8358 bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) { 8359 // FIXME: Deal with vectors as array subscript bases. 8360 if (E->getBase()->getType()->isVectorType()) 8361 return Error(E); 8362 8363 APSInt Index; 8364 bool Success = true; 8365 8366 // C++17's rules require us to evaluate the LHS first, regardless of which 8367 // side is the base. 8368 for (const Expr *SubExpr : {E->getLHS(), E->getRHS()}) { 8369 if (SubExpr == E->getBase() ? !evaluatePointer(SubExpr, Result) 8370 : !EvaluateInteger(SubExpr, Index, Info)) { 8371 if (!Info.noteFailure()) 8372 return false; 8373 Success = false; 8374 } 8375 } 8376 8377 return Success && 8378 HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Index); 8379 } 8380 8381 bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) { 8382 return evaluatePointer(E->getSubExpr(), Result); 8383 } 8384 8385 bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 8386 if (!Visit(E->getSubExpr())) 8387 return false; 8388 // __real is a no-op on scalar lvalues. 8389 if (E->getSubExpr()->getType()->isAnyComplexType()) 8390 HandleLValueComplexElement(Info, E, Result, E->getType(), false); 8391 return true; 8392 } 8393 8394 bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 8395 assert(E->getSubExpr()->getType()->isAnyComplexType() && 8396 "lvalue __imag__ on scalar?"); 8397 if (!Visit(E->getSubExpr())) 8398 return false; 8399 HandleLValueComplexElement(Info, E, Result, E->getType(), true); 8400 return true; 8401 } 8402 8403 bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) { 8404 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) 8405 return Error(UO); 8406 8407 if (!this->Visit(UO->getSubExpr())) 8408 return false; 8409 8410 return handleIncDec( 8411 this->Info, UO, Result, UO->getSubExpr()->getType(), 8412 UO->isIncrementOp(), nullptr); 8413 } 8414 8415 bool LValueExprEvaluator::VisitCompoundAssignOperator( 8416 const CompoundAssignOperator *CAO) { 8417 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) 8418 return Error(CAO); 8419 8420 bool Success = true; 8421 8422 // C++17 onwards require that we evaluate the RHS first. 8423 APValue RHS; 8424 if (!Evaluate(RHS, this->Info, CAO->getRHS())) { 8425 if (!Info.noteFailure()) 8426 return false; 8427 Success = false; 8428 } 8429 8430 // The overall lvalue result is the result of evaluating the LHS. 8431 if (!this->Visit(CAO->getLHS()) || !Success) 8432 return false; 8433 8434 return handleCompoundAssignment( 8435 this->Info, CAO, 8436 Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(), 8437 CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS); 8438 } 8439 8440 bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) { 8441 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) 8442 return Error(E); 8443 8444 bool Success = true; 8445 8446 // C++17 onwards require that we evaluate the RHS first. 8447 APValue NewVal; 8448 if (!Evaluate(NewVal, this->Info, E->getRHS())) { 8449 if (!Info.noteFailure()) 8450 return false; 8451 Success = false; 8452 } 8453 8454 if (!this->Visit(E->getLHS()) || !Success) 8455 return false; 8456 8457 if (Info.getLangOpts().CPlusPlus20 && 8458 !HandleUnionActiveMemberChange(Info, E->getLHS(), Result)) 8459 return false; 8460 8461 return handleAssignment(this->Info, E, Result, E->getLHS()->getType(), 8462 NewVal); 8463 } 8464 8465 //===----------------------------------------------------------------------===// 8466 // Pointer Evaluation 8467 //===----------------------------------------------------------------------===// 8468 8469 /// Attempts to compute the number of bytes available at the pointer 8470 /// returned by a function with the alloc_size attribute. Returns true if we 8471 /// were successful. Places an unsigned number into `Result`. 8472 /// 8473 /// This expects the given CallExpr to be a call to a function with an 8474 /// alloc_size attribute. 8475 static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx, 8476 const CallExpr *Call, 8477 llvm::APInt &Result) { 8478 const AllocSizeAttr *AllocSize = getAllocSizeAttr(Call); 8479 8480 assert(AllocSize && AllocSize->getElemSizeParam().isValid()); 8481 unsigned SizeArgNo = AllocSize->getElemSizeParam().getASTIndex(); 8482 unsigned BitsInSizeT = Ctx.getTypeSize(Ctx.getSizeType()); 8483 if (Call->getNumArgs() <= SizeArgNo) 8484 return false; 8485 8486 auto EvaluateAsSizeT = [&](const Expr *E, APSInt &Into) { 8487 Expr::EvalResult ExprResult; 8488 if (!E->EvaluateAsInt(ExprResult, Ctx, Expr::SE_AllowSideEffects)) 8489 return false; 8490 Into = ExprResult.Val.getInt(); 8491 if (Into.isNegative() || !Into.isIntN(BitsInSizeT)) 8492 return false; 8493 Into = Into.zextOrSelf(BitsInSizeT); 8494 return true; 8495 }; 8496 8497 APSInt SizeOfElem; 8498 if (!EvaluateAsSizeT(Call->getArg(SizeArgNo), SizeOfElem)) 8499 return false; 8500 8501 if (!AllocSize->getNumElemsParam().isValid()) { 8502 Result = std::move(SizeOfElem); 8503 return true; 8504 } 8505 8506 APSInt NumberOfElems; 8507 unsigned NumArgNo = AllocSize->getNumElemsParam().getASTIndex(); 8508 if (!EvaluateAsSizeT(Call->getArg(NumArgNo), NumberOfElems)) 8509 return false; 8510 8511 bool Overflow; 8512 llvm::APInt BytesAvailable = SizeOfElem.umul_ov(NumberOfElems, Overflow); 8513 if (Overflow) 8514 return false; 8515 8516 Result = std::move(BytesAvailable); 8517 return true; 8518 } 8519 8520 /// Convenience function. LVal's base must be a call to an alloc_size 8521 /// function. 8522 static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx, 8523 const LValue &LVal, 8524 llvm::APInt &Result) { 8525 assert(isBaseAnAllocSizeCall(LVal.getLValueBase()) && 8526 "Can't get the size of a non alloc_size function"); 8527 const auto *Base = LVal.getLValueBase().get<const Expr *>(); 8528 const CallExpr *CE = tryUnwrapAllocSizeCall(Base); 8529 return getBytesReturnedByAllocSizeCall(Ctx, CE, Result); 8530 } 8531 8532 /// Attempts to evaluate the given LValueBase as the result of a call to 8533 /// a function with the alloc_size attribute. If it was possible to do so, this 8534 /// function will return true, make Result's Base point to said function call, 8535 /// and mark Result's Base as invalid. 8536 static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base, 8537 LValue &Result) { 8538 if (Base.isNull()) 8539 return false; 8540 8541 // Because we do no form of static analysis, we only support const variables. 8542 // 8543 // Additionally, we can't support parameters, nor can we support static 8544 // variables (in the latter case, use-before-assign isn't UB; in the former, 8545 // we have no clue what they'll be assigned to). 8546 const auto *VD = 8547 dyn_cast_or_null<VarDecl>(Base.dyn_cast<const ValueDecl *>()); 8548 if (!VD || !VD->isLocalVarDecl() || !VD->getType().isConstQualified()) 8549 return false; 8550 8551 const Expr *Init = VD->getAnyInitializer(); 8552 if (!Init) 8553 return false; 8554 8555 const Expr *E = Init->IgnoreParens(); 8556 if (!tryUnwrapAllocSizeCall(E)) 8557 return false; 8558 8559 // Store E instead of E unwrapped so that the type of the LValue's base is 8560 // what the user wanted. 8561 Result.setInvalid(E); 8562 8563 QualType Pointee = E->getType()->castAs<PointerType>()->getPointeeType(); 8564 Result.addUnsizedArray(Info, E, Pointee); 8565 return true; 8566 } 8567 8568 namespace { 8569 class PointerExprEvaluator 8570 : public ExprEvaluatorBase<PointerExprEvaluator> { 8571 LValue &Result; 8572 bool InvalidBaseOK; 8573 8574 bool Success(const Expr *E) { 8575 Result.set(E); 8576 return true; 8577 } 8578 8579 bool evaluateLValue(const Expr *E, LValue &Result) { 8580 return EvaluateLValue(E, Result, Info, InvalidBaseOK); 8581 } 8582 8583 bool evaluatePointer(const Expr *E, LValue &Result) { 8584 return EvaluatePointer(E, Result, Info, InvalidBaseOK); 8585 } 8586 8587 bool visitNonBuiltinCallExpr(const CallExpr *E); 8588 public: 8589 8590 PointerExprEvaluator(EvalInfo &info, LValue &Result, bool InvalidBaseOK) 8591 : ExprEvaluatorBaseTy(info), Result(Result), 8592 InvalidBaseOK(InvalidBaseOK) {} 8593 8594 bool Success(const APValue &V, const Expr *E) { 8595 Result.setFrom(Info.Ctx, V); 8596 return true; 8597 } 8598 bool ZeroInitialization(const Expr *E) { 8599 Result.setNull(Info.Ctx, E->getType()); 8600 return true; 8601 } 8602 8603 bool VisitBinaryOperator(const BinaryOperator *E); 8604 bool VisitCastExpr(const CastExpr* E); 8605 bool VisitUnaryAddrOf(const UnaryOperator *E); 8606 bool VisitObjCStringLiteral(const ObjCStringLiteral *E) 8607 { return Success(E); } 8608 bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) { 8609 if (E->isExpressibleAsConstantInitializer()) 8610 return Success(E); 8611 if (Info.noteFailure()) 8612 EvaluateIgnoredValue(Info, E->getSubExpr()); 8613 return Error(E); 8614 } 8615 bool VisitAddrLabelExpr(const AddrLabelExpr *E) 8616 { return Success(E); } 8617 bool VisitCallExpr(const CallExpr *E); 8618 bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp); 8619 bool VisitBlockExpr(const BlockExpr *E) { 8620 if (!E->getBlockDecl()->hasCaptures()) 8621 return Success(E); 8622 return Error(E); 8623 } 8624 bool VisitCXXThisExpr(const CXXThisExpr *E) { 8625 // Can't look at 'this' when checking a potential constant expression. 8626 if (Info.checkingPotentialConstantExpression()) 8627 return false; 8628 if (!Info.CurrentCall->This) { 8629 if (Info.getLangOpts().CPlusPlus11) 8630 Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit(); 8631 else 8632 Info.FFDiag(E); 8633 return false; 8634 } 8635 Result = *Info.CurrentCall->This; 8636 // If we are inside a lambda's call operator, the 'this' expression refers 8637 // to the enclosing '*this' object (either by value or reference) which is 8638 // either copied into the closure object's field that represents the '*this' 8639 // or refers to '*this'. 8640 if (isLambdaCallOperator(Info.CurrentCall->Callee)) { 8641 // Ensure we actually have captured 'this'. (an error will have 8642 // been previously reported if not). 8643 if (!Info.CurrentCall->LambdaThisCaptureField) 8644 return false; 8645 8646 // Update 'Result' to refer to the data member/field of the closure object 8647 // that represents the '*this' capture. 8648 if (!HandleLValueMember(Info, E, Result, 8649 Info.CurrentCall->LambdaThisCaptureField)) 8650 return false; 8651 // If we captured '*this' by reference, replace the field with its referent. 8652 if (Info.CurrentCall->LambdaThisCaptureField->getType() 8653 ->isPointerType()) { 8654 APValue RVal; 8655 if (!handleLValueToRValueConversion(Info, E, E->getType(), Result, 8656 RVal)) 8657 return false; 8658 8659 Result.setFrom(Info.Ctx, RVal); 8660 } 8661 } 8662 return true; 8663 } 8664 8665 bool VisitCXXNewExpr(const CXXNewExpr *E); 8666 8667 bool VisitSourceLocExpr(const SourceLocExpr *E) { 8668 assert(E->isStringType() && "SourceLocExpr isn't a pointer type?"); 8669 APValue LValResult = E->EvaluateInContext( 8670 Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr()); 8671 Result.setFrom(Info.Ctx, LValResult); 8672 return true; 8673 } 8674 8675 bool VisitSYCLUniqueStableNameExpr(const SYCLUniqueStableNameExpr *E) { 8676 std::string ResultStr = E->ComputeName(Info.Ctx); 8677 8678 Info.Ctx.SYCLUniqueStableNameEvaluatedValues[E] = ResultStr; 8679 8680 QualType CharTy = Info.Ctx.CharTy.withConst(); 8681 APInt Size(Info.Ctx.getTypeSize(Info.Ctx.getSizeType()), 8682 ResultStr.size() + 1); 8683 QualType ArrayTy = Info.Ctx.getConstantArrayType(CharTy, Size, nullptr, 8684 ArrayType::Normal, 0); 8685 8686 StringLiteral *SL = 8687 StringLiteral::Create(Info.Ctx, ResultStr, StringLiteral::Ascii, 8688 /*Pascal*/ false, ArrayTy, E->getLocation()); 8689 8690 evaluateLValue(SL, Result); 8691 Result.addArray(Info, E, cast<ConstantArrayType>(ArrayTy)); 8692 return true; 8693 } 8694 8695 // FIXME: Missing: @protocol, @selector 8696 }; 8697 } // end anonymous namespace 8698 8699 static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info, 8700 bool InvalidBaseOK) { 8701 assert(!E->isValueDependent()); 8702 assert(E->isPRValue() && E->getType()->hasPointerRepresentation()); 8703 return PointerExprEvaluator(Info, Result, InvalidBaseOK).Visit(E); 8704 } 8705 8706 bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 8707 if (E->getOpcode() != BO_Add && 8708 E->getOpcode() != BO_Sub) 8709 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 8710 8711 const Expr *PExp = E->getLHS(); 8712 const Expr *IExp = E->getRHS(); 8713 if (IExp->getType()->isPointerType()) 8714 std::swap(PExp, IExp); 8715 8716 bool EvalPtrOK = evaluatePointer(PExp, Result); 8717 if (!EvalPtrOK && !Info.noteFailure()) 8718 return false; 8719 8720 llvm::APSInt Offset; 8721 if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK) 8722 return false; 8723 8724 if (E->getOpcode() == BO_Sub) 8725 negateAsSigned(Offset); 8726 8727 QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType(); 8728 return HandleLValueArrayAdjustment(Info, E, Result, Pointee, Offset); 8729 } 8730 8731 bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { 8732 return evaluateLValue(E->getSubExpr(), Result); 8733 } 8734 8735 bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) { 8736 const Expr *SubExpr = E->getSubExpr(); 8737 8738 switch (E->getCastKind()) { 8739 default: 8740 break; 8741 case CK_BitCast: 8742 case CK_CPointerToObjCPointerCast: 8743 case CK_BlockPointerToObjCPointerCast: 8744 case CK_AnyPointerToBlockPointerCast: 8745 case CK_AddressSpaceConversion: 8746 if (!Visit(SubExpr)) 8747 return false; 8748 // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are 8749 // permitted in constant expressions in C++11. Bitcasts from cv void* are 8750 // also static_casts, but we disallow them as a resolution to DR1312. 8751 if (!E->getType()->isVoidPointerType()) { 8752 if (!Result.InvalidBase && !Result.Designator.Invalid && 8753 !Result.IsNullPtr && 8754 Info.Ctx.hasSameUnqualifiedType(Result.Designator.getType(Info.Ctx), 8755 E->getType()->getPointeeType()) && 8756 Info.getStdAllocatorCaller("allocate")) { 8757 // Inside a call to std::allocator::allocate and friends, we permit 8758 // casting from void* back to cv1 T* for a pointer that points to a 8759 // cv2 T. 8760 } else { 8761 Result.Designator.setInvalid(); 8762 if (SubExpr->getType()->isVoidPointerType()) 8763 CCEDiag(E, diag::note_constexpr_invalid_cast) 8764 << 3 << SubExpr->getType(); 8765 else 8766 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 8767 } 8768 } 8769 if (E->getCastKind() == CK_AddressSpaceConversion && Result.IsNullPtr) 8770 ZeroInitialization(E); 8771 return true; 8772 8773 case CK_DerivedToBase: 8774 case CK_UncheckedDerivedToBase: 8775 if (!evaluatePointer(E->getSubExpr(), Result)) 8776 return false; 8777 if (!Result.Base && Result.Offset.isZero()) 8778 return true; 8779 8780 // Now figure out the necessary offset to add to the base LV to get from 8781 // the derived class to the base class. 8782 return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()-> 8783 castAs<PointerType>()->getPointeeType(), 8784 Result); 8785 8786 case CK_BaseToDerived: 8787 if (!Visit(E->getSubExpr())) 8788 return false; 8789 if (!Result.Base && Result.Offset.isZero()) 8790 return true; 8791 return HandleBaseToDerivedCast(Info, E, Result); 8792 8793 case CK_Dynamic: 8794 if (!Visit(E->getSubExpr())) 8795 return false; 8796 return HandleDynamicCast(Info, cast<ExplicitCastExpr>(E), Result); 8797 8798 case CK_NullToPointer: 8799 VisitIgnoredValue(E->getSubExpr()); 8800 return ZeroInitialization(E); 8801 8802 case CK_IntegralToPointer: { 8803 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 8804 8805 APValue Value; 8806 if (!EvaluateIntegerOrLValue(SubExpr, Value, Info)) 8807 break; 8808 8809 if (Value.isInt()) { 8810 unsigned Size = Info.Ctx.getTypeSize(E->getType()); 8811 uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue(); 8812 Result.Base = (Expr*)nullptr; 8813 Result.InvalidBase = false; 8814 Result.Offset = CharUnits::fromQuantity(N); 8815 Result.Designator.setInvalid(); 8816 Result.IsNullPtr = false; 8817 return true; 8818 } else { 8819 // Cast is of an lvalue, no need to change value. 8820 Result.setFrom(Info.Ctx, Value); 8821 return true; 8822 } 8823 } 8824 8825 case CK_ArrayToPointerDecay: { 8826 if (SubExpr->isGLValue()) { 8827 if (!evaluateLValue(SubExpr, Result)) 8828 return false; 8829 } else { 8830 APValue &Value = Info.CurrentCall->createTemporary( 8831 SubExpr, SubExpr->getType(), ScopeKind::FullExpression, Result); 8832 if (!EvaluateInPlace(Value, Info, Result, SubExpr)) 8833 return false; 8834 } 8835 // The result is a pointer to the first element of the array. 8836 auto *AT = Info.Ctx.getAsArrayType(SubExpr->getType()); 8837 if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) 8838 Result.addArray(Info, E, CAT); 8839 else 8840 Result.addUnsizedArray(Info, E, AT->getElementType()); 8841 return true; 8842 } 8843 8844 case CK_FunctionToPointerDecay: 8845 return evaluateLValue(SubExpr, Result); 8846 8847 case CK_LValueToRValue: { 8848 LValue LVal; 8849 if (!evaluateLValue(E->getSubExpr(), LVal)) 8850 return false; 8851 8852 APValue RVal; 8853 // Note, we use the subexpression's type in order to retain cv-qualifiers. 8854 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(), 8855 LVal, RVal)) 8856 return InvalidBaseOK && 8857 evaluateLValueAsAllocSize(Info, LVal.Base, Result); 8858 return Success(RVal, E); 8859 } 8860 } 8861 8862 return ExprEvaluatorBaseTy::VisitCastExpr(E); 8863 } 8864 8865 static CharUnits GetAlignOfType(EvalInfo &Info, QualType T, 8866 UnaryExprOrTypeTrait ExprKind) { 8867 // C++ [expr.alignof]p3: 8868 // When alignof is applied to a reference type, the result is the 8869 // alignment of the referenced type. 8870 if (const ReferenceType *Ref = T->getAs<ReferenceType>()) 8871 T = Ref->getPointeeType(); 8872 8873 if (T.getQualifiers().hasUnaligned()) 8874 return CharUnits::One(); 8875 8876 const bool AlignOfReturnsPreferred = 8877 Info.Ctx.getLangOpts().getClangABICompat() <= LangOptions::ClangABI::Ver7; 8878 8879 // __alignof is defined to return the preferred alignment. 8880 // Before 8, clang returned the preferred alignment for alignof and _Alignof 8881 // as well. 8882 if (ExprKind == UETT_PreferredAlignOf || AlignOfReturnsPreferred) 8883 return Info.Ctx.toCharUnitsFromBits( 8884 Info.Ctx.getPreferredTypeAlign(T.getTypePtr())); 8885 // alignof and _Alignof are defined to return the ABI alignment. 8886 else if (ExprKind == UETT_AlignOf) 8887 return Info.Ctx.getTypeAlignInChars(T.getTypePtr()); 8888 else 8889 llvm_unreachable("GetAlignOfType on a non-alignment ExprKind"); 8890 } 8891 8892 static CharUnits GetAlignOfExpr(EvalInfo &Info, const Expr *E, 8893 UnaryExprOrTypeTrait ExprKind) { 8894 E = E->IgnoreParens(); 8895 8896 // The kinds of expressions that we have special-case logic here for 8897 // should be kept up to date with the special checks for those 8898 // expressions in Sema. 8899 8900 // alignof decl is always accepted, even if it doesn't make sense: we default 8901 // to 1 in those cases. 8902 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) 8903 return Info.Ctx.getDeclAlign(DRE->getDecl(), 8904 /*RefAsPointee*/true); 8905 8906 if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) 8907 return Info.Ctx.getDeclAlign(ME->getMemberDecl(), 8908 /*RefAsPointee*/true); 8909 8910 return GetAlignOfType(Info, E->getType(), ExprKind); 8911 } 8912 8913 static CharUnits getBaseAlignment(EvalInfo &Info, const LValue &Value) { 8914 if (const auto *VD = Value.Base.dyn_cast<const ValueDecl *>()) 8915 return Info.Ctx.getDeclAlign(VD); 8916 if (const auto *E = Value.Base.dyn_cast<const Expr *>()) 8917 return GetAlignOfExpr(Info, E, UETT_AlignOf); 8918 return GetAlignOfType(Info, Value.Base.getTypeInfoType(), UETT_AlignOf); 8919 } 8920 8921 /// Evaluate the value of the alignment argument to __builtin_align_{up,down}, 8922 /// __builtin_is_aligned and __builtin_assume_aligned. 8923 static bool getAlignmentArgument(const Expr *E, QualType ForType, 8924 EvalInfo &Info, APSInt &Alignment) { 8925 if (!EvaluateInteger(E, Alignment, Info)) 8926 return false; 8927 if (Alignment < 0 || !Alignment.isPowerOf2()) { 8928 Info.FFDiag(E, diag::note_constexpr_invalid_alignment) << Alignment; 8929 return false; 8930 } 8931 unsigned SrcWidth = Info.Ctx.getIntWidth(ForType); 8932 APSInt MaxValue(APInt::getOneBitSet(SrcWidth, SrcWidth - 1)); 8933 if (APSInt::compareValues(Alignment, MaxValue) > 0) { 8934 Info.FFDiag(E, diag::note_constexpr_alignment_too_big) 8935 << MaxValue << ForType << Alignment; 8936 return false; 8937 } 8938 // Ensure both alignment and source value have the same bit width so that we 8939 // don't assert when computing the resulting value. 8940 APSInt ExtAlignment = 8941 APSInt(Alignment.zextOrTrunc(SrcWidth), /*isUnsigned=*/true); 8942 assert(APSInt::compareValues(Alignment, ExtAlignment) == 0 && 8943 "Alignment should not be changed by ext/trunc"); 8944 Alignment = ExtAlignment; 8945 assert(Alignment.getBitWidth() == SrcWidth); 8946 return true; 8947 } 8948 8949 // To be clear: this happily visits unsupported builtins. Better name welcomed. 8950 bool PointerExprEvaluator::visitNonBuiltinCallExpr(const CallExpr *E) { 8951 if (ExprEvaluatorBaseTy::VisitCallExpr(E)) 8952 return true; 8953 8954 if (!(InvalidBaseOK && getAllocSizeAttr(E))) 8955 return false; 8956 8957 Result.setInvalid(E); 8958 QualType PointeeTy = E->getType()->castAs<PointerType>()->getPointeeType(); 8959 Result.addUnsizedArray(Info, E, PointeeTy); 8960 return true; 8961 } 8962 8963 bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) { 8964 if (IsStringLiteralCall(E)) 8965 return Success(E); 8966 8967 if (unsigned BuiltinOp = E->getBuiltinCallee()) 8968 return VisitBuiltinCallExpr(E, BuiltinOp); 8969 8970 return visitNonBuiltinCallExpr(E); 8971 } 8972 8973 // Determine if T is a character type for which we guarantee that 8974 // sizeof(T) == 1. 8975 static bool isOneByteCharacterType(QualType T) { 8976 return T->isCharType() || T->isChar8Type(); 8977 } 8978 8979 bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E, 8980 unsigned BuiltinOp) { 8981 switch (BuiltinOp) { 8982 case Builtin::BI__builtin_addressof: 8983 return evaluateLValue(E->getArg(0), Result); 8984 case Builtin::BI__builtin_assume_aligned: { 8985 // We need to be very careful here because: if the pointer does not have the 8986 // asserted alignment, then the behavior is undefined, and undefined 8987 // behavior is non-constant. 8988 if (!evaluatePointer(E->getArg(0), Result)) 8989 return false; 8990 8991 LValue OffsetResult(Result); 8992 APSInt Alignment; 8993 if (!getAlignmentArgument(E->getArg(1), E->getArg(0)->getType(), Info, 8994 Alignment)) 8995 return false; 8996 CharUnits Align = CharUnits::fromQuantity(Alignment.getZExtValue()); 8997 8998 if (E->getNumArgs() > 2) { 8999 APSInt Offset; 9000 if (!EvaluateInteger(E->getArg(2), Offset, Info)) 9001 return false; 9002 9003 int64_t AdditionalOffset = -Offset.getZExtValue(); 9004 OffsetResult.Offset += CharUnits::fromQuantity(AdditionalOffset); 9005 } 9006 9007 // If there is a base object, then it must have the correct alignment. 9008 if (OffsetResult.Base) { 9009 CharUnits BaseAlignment = getBaseAlignment(Info, OffsetResult); 9010 9011 if (BaseAlignment < Align) { 9012 Result.Designator.setInvalid(); 9013 // FIXME: Add support to Diagnostic for long / long long. 9014 CCEDiag(E->getArg(0), 9015 diag::note_constexpr_baa_insufficient_alignment) << 0 9016 << (unsigned)BaseAlignment.getQuantity() 9017 << (unsigned)Align.getQuantity(); 9018 return false; 9019 } 9020 } 9021 9022 // The offset must also have the correct alignment. 9023 if (OffsetResult.Offset.alignTo(Align) != OffsetResult.Offset) { 9024 Result.Designator.setInvalid(); 9025 9026 (OffsetResult.Base 9027 ? CCEDiag(E->getArg(0), 9028 diag::note_constexpr_baa_insufficient_alignment) << 1 9029 : CCEDiag(E->getArg(0), 9030 diag::note_constexpr_baa_value_insufficient_alignment)) 9031 << (int)OffsetResult.Offset.getQuantity() 9032 << (unsigned)Align.getQuantity(); 9033 return false; 9034 } 9035 9036 return true; 9037 } 9038 case Builtin::BI__builtin_align_up: 9039 case Builtin::BI__builtin_align_down: { 9040 if (!evaluatePointer(E->getArg(0), Result)) 9041 return false; 9042 APSInt Alignment; 9043 if (!getAlignmentArgument(E->getArg(1), E->getArg(0)->getType(), Info, 9044 Alignment)) 9045 return false; 9046 CharUnits BaseAlignment = getBaseAlignment(Info, Result); 9047 CharUnits PtrAlign = BaseAlignment.alignmentAtOffset(Result.Offset); 9048 // For align_up/align_down, we can return the same value if the alignment 9049 // is known to be greater or equal to the requested value. 9050 if (PtrAlign.getQuantity() >= Alignment) 9051 return true; 9052 9053 // The alignment could be greater than the minimum at run-time, so we cannot 9054 // infer much about the resulting pointer value. One case is possible: 9055 // For `_Alignas(32) char buf[N]; __builtin_align_down(&buf[idx], 32)` we 9056 // can infer the correct index if the requested alignment is smaller than 9057 // the base alignment so we can perform the computation on the offset. 9058 if (BaseAlignment.getQuantity() >= Alignment) { 9059 assert(Alignment.getBitWidth() <= 64 && 9060 "Cannot handle > 64-bit address-space"); 9061 uint64_t Alignment64 = Alignment.getZExtValue(); 9062 CharUnits NewOffset = CharUnits::fromQuantity( 9063 BuiltinOp == Builtin::BI__builtin_align_down 9064 ? llvm::alignDown(Result.Offset.getQuantity(), Alignment64) 9065 : llvm::alignTo(Result.Offset.getQuantity(), Alignment64)); 9066 Result.adjustOffset(NewOffset - Result.Offset); 9067 // TODO: diagnose out-of-bounds values/only allow for arrays? 9068 return true; 9069 } 9070 // Otherwise, we cannot constant-evaluate the result. 9071 Info.FFDiag(E->getArg(0), diag::note_constexpr_alignment_adjust) 9072 << Alignment; 9073 return false; 9074 } 9075 case Builtin::BI__builtin_operator_new: 9076 return HandleOperatorNewCall(Info, E, Result); 9077 case Builtin::BI__builtin_launder: 9078 return evaluatePointer(E->getArg(0), Result); 9079 case Builtin::BIstrchr: 9080 case Builtin::BIwcschr: 9081 case Builtin::BImemchr: 9082 case Builtin::BIwmemchr: 9083 if (Info.getLangOpts().CPlusPlus11) 9084 Info.CCEDiag(E, diag::note_constexpr_invalid_function) 9085 << /*isConstexpr*/0 << /*isConstructor*/0 9086 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'"); 9087 else 9088 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); 9089 LLVM_FALLTHROUGH; 9090 case Builtin::BI__builtin_strchr: 9091 case Builtin::BI__builtin_wcschr: 9092 case Builtin::BI__builtin_memchr: 9093 case Builtin::BI__builtin_char_memchr: 9094 case Builtin::BI__builtin_wmemchr: { 9095 if (!Visit(E->getArg(0))) 9096 return false; 9097 APSInt Desired; 9098 if (!EvaluateInteger(E->getArg(1), Desired, Info)) 9099 return false; 9100 uint64_t MaxLength = uint64_t(-1); 9101 if (BuiltinOp != Builtin::BIstrchr && 9102 BuiltinOp != Builtin::BIwcschr && 9103 BuiltinOp != Builtin::BI__builtin_strchr && 9104 BuiltinOp != Builtin::BI__builtin_wcschr) { 9105 APSInt N; 9106 if (!EvaluateInteger(E->getArg(2), N, Info)) 9107 return false; 9108 MaxLength = N.getExtValue(); 9109 } 9110 // We cannot find the value if there are no candidates to match against. 9111 if (MaxLength == 0u) 9112 return ZeroInitialization(E); 9113 if (!Result.checkNullPointerForFoldAccess(Info, E, AK_Read) || 9114 Result.Designator.Invalid) 9115 return false; 9116 QualType CharTy = Result.Designator.getType(Info.Ctx); 9117 bool IsRawByte = BuiltinOp == Builtin::BImemchr || 9118 BuiltinOp == Builtin::BI__builtin_memchr; 9119 assert(IsRawByte || 9120 Info.Ctx.hasSameUnqualifiedType( 9121 CharTy, E->getArg(0)->getType()->getPointeeType())); 9122 // Pointers to const void may point to objects of incomplete type. 9123 if (IsRawByte && CharTy->isIncompleteType()) { 9124 Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) << CharTy; 9125 return false; 9126 } 9127 // Give up on byte-oriented matching against multibyte elements. 9128 // FIXME: We can compare the bytes in the correct order. 9129 if (IsRawByte && !isOneByteCharacterType(CharTy)) { 9130 Info.FFDiag(E, diag::note_constexpr_memchr_unsupported) 9131 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'") 9132 << CharTy; 9133 return false; 9134 } 9135 // Figure out what value we're actually looking for (after converting to 9136 // the corresponding unsigned type if necessary). 9137 uint64_t DesiredVal; 9138 bool StopAtNull = false; 9139 switch (BuiltinOp) { 9140 case Builtin::BIstrchr: 9141 case Builtin::BI__builtin_strchr: 9142 // strchr compares directly to the passed integer, and therefore 9143 // always fails if given an int that is not a char. 9144 if (!APSInt::isSameValue(HandleIntToIntCast(Info, E, CharTy, 9145 E->getArg(1)->getType(), 9146 Desired), 9147 Desired)) 9148 return ZeroInitialization(E); 9149 StopAtNull = true; 9150 LLVM_FALLTHROUGH; 9151 case Builtin::BImemchr: 9152 case Builtin::BI__builtin_memchr: 9153 case Builtin::BI__builtin_char_memchr: 9154 // memchr compares by converting both sides to unsigned char. That's also 9155 // correct for strchr if we get this far (to cope with plain char being 9156 // unsigned in the strchr case). 9157 DesiredVal = Desired.trunc(Info.Ctx.getCharWidth()).getZExtValue(); 9158 break; 9159 9160 case Builtin::BIwcschr: 9161 case Builtin::BI__builtin_wcschr: 9162 StopAtNull = true; 9163 LLVM_FALLTHROUGH; 9164 case Builtin::BIwmemchr: 9165 case Builtin::BI__builtin_wmemchr: 9166 // wcschr and wmemchr are given a wchar_t to look for. Just use it. 9167 DesiredVal = Desired.getZExtValue(); 9168 break; 9169 } 9170 9171 for (; MaxLength; --MaxLength) { 9172 APValue Char; 9173 if (!handleLValueToRValueConversion(Info, E, CharTy, Result, Char) || 9174 !Char.isInt()) 9175 return false; 9176 if (Char.getInt().getZExtValue() == DesiredVal) 9177 return true; 9178 if (StopAtNull && !Char.getInt()) 9179 break; 9180 if (!HandleLValueArrayAdjustment(Info, E, Result, CharTy, 1)) 9181 return false; 9182 } 9183 // Not found: return nullptr. 9184 return ZeroInitialization(E); 9185 } 9186 9187 case Builtin::BImemcpy: 9188 case Builtin::BImemmove: 9189 case Builtin::BIwmemcpy: 9190 case Builtin::BIwmemmove: 9191 if (Info.getLangOpts().CPlusPlus11) 9192 Info.CCEDiag(E, diag::note_constexpr_invalid_function) 9193 << /*isConstexpr*/0 << /*isConstructor*/0 9194 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'"); 9195 else 9196 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); 9197 LLVM_FALLTHROUGH; 9198 case Builtin::BI__builtin_memcpy: 9199 case Builtin::BI__builtin_memmove: 9200 case Builtin::BI__builtin_wmemcpy: 9201 case Builtin::BI__builtin_wmemmove: { 9202 bool WChar = BuiltinOp == Builtin::BIwmemcpy || 9203 BuiltinOp == Builtin::BIwmemmove || 9204 BuiltinOp == Builtin::BI__builtin_wmemcpy || 9205 BuiltinOp == Builtin::BI__builtin_wmemmove; 9206 bool Move = BuiltinOp == Builtin::BImemmove || 9207 BuiltinOp == Builtin::BIwmemmove || 9208 BuiltinOp == Builtin::BI__builtin_memmove || 9209 BuiltinOp == Builtin::BI__builtin_wmemmove; 9210 9211 // The result of mem* is the first argument. 9212 if (!Visit(E->getArg(0))) 9213 return false; 9214 LValue Dest = Result; 9215 9216 LValue Src; 9217 if (!EvaluatePointer(E->getArg(1), Src, Info)) 9218 return false; 9219 9220 APSInt N; 9221 if (!EvaluateInteger(E->getArg(2), N, Info)) 9222 return false; 9223 assert(!N.isSigned() && "memcpy and friends take an unsigned size"); 9224 9225 // If the size is zero, we treat this as always being a valid no-op. 9226 // (Even if one of the src and dest pointers is null.) 9227 if (!N) 9228 return true; 9229 9230 // Otherwise, if either of the operands is null, we can't proceed. Don't 9231 // try to determine the type of the copied objects, because there aren't 9232 // any. 9233 if (!Src.Base || !Dest.Base) { 9234 APValue Val; 9235 (!Src.Base ? Src : Dest).moveInto(Val); 9236 Info.FFDiag(E, diag::note_constexpr_memcpy_null) 9237 << Move << WChar << !!Src.Base 9238 << Val.getAsString(Info.Ctx, E->getArg(0)->getType()); 9239 return false; 9240 } 9241 if (Src.Designator.Invalid || Dest.Designator.Invalid) 9242 return false; 9243 9244 // We require that Src and Dest are both pointers to arrays of 9245 // trivially-copyable type. (For the wide version, the designator will be 9246 // invalid if the designated object is not a wchar_t.) 9247 QualType T = Dest.Designator.getType(Info.Ctx); 9248 QualType SrcT = Src.Designator.getType(Info.Ctx); 9249 if (!Info.Ctx.hasSameUnqualifiedType(T, SrcT)) { 9250 // FIXME: Consider using our bit_cast implementation to support this. 9251 Info.FFDiag(E, diag::note_constexpr_memcpy_type_pun) << Move << SrcT << T; 9252 return false; 9253 } 9254 if (T->isIncompleteType()) { 9255 Info.FFDiag(E, diag::note_constexpr_memcpy_incomplete_type) << Move << T; 9256 return false; 9257 } 9258 if (!T.isTriviallyCopyableType(Info.Ctx)) { 9259 Info.FFDiag(E, diag::note_constexpr_memcpy_nontrivial) << Move << T; 9260 return false; 9261 } 9262 9263 // Figure out how many T's we're copying. 9264 uint64_t TSize = Info.Ctx.getTypeSizeInChars(T).getQuantity(); 9265 if (!WChar) { 9266 uint64_t Remainder; 9267 llvm::APInt OrigN = N; 9268 llvm::APInt::udivrem(OrigN, TSize, N, Remainder); 9269 if (Remainder) { 9270 Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported) 9271 << Move << WChar << 0 << T << toString(OrigN, 10, /*Signed*/false) 9272 << (unsigned)TSize; 9273 return false; 9274 } 9275 } 9276 9277 // Check that the copying will remain within the arrays, just so that we 9278 // can give a more meaningful diagnostic. This implicitly also checks that 9279 // N fits into 64 bits. 9280 uint64_t RemainingSrcSize = Src.Designator.validIndexAdjustments().second; 9281 uint64_t RemainingDestSize = Dest.Designator.validIndexAdjustments().second; 9282 if (N.ugt(RemainingSrcSize) || N.ugt(RemainingDestSize)) { 9283 Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported) 9284 << Move << WChar << (N.ugt(RemainingSrcSize) ? 1 : 2) << T 9285 << toString(N, 10, /*Signed*/false); 9286 return false; 9287 } 9288 uint64_t NElems = N.getZExtValue(); 9289 uint64_t NBytes = NElems * TSize; 9290 9291 // Check for overlap. 9292 int Direction = 1; 9293 if (HasSameBase(Src, Dest)) { 9294 uint64_t SrcOffset = Src.getLValueOffset().getQuantity(); 9295 uint64_t DestOffset = Dest.getLValueOffset().getQuantity(); 9296 if (DestOffset >= SrcOffset && DestOffset - SrcOffset < NBytes) { 9297 // Dest is inside the source region. 9298 if (!Move) { 9299 Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar; 9300 return false; 9301 } 9302 // For memmove and friends, copy backwards. 9303 if (!HandleLValueArrayAdjustment(Info, E, Src, T, NElems - 1) || 9304 !HandleLValueArrayAdjustment(Info, E, Dest, T, NElems - 1)) 9305 return false; 9306 Direction = -1; 9307 } else if (!Move && SrcOffset >= DestOffset && 9308 SrcOffset - DestOffset < NBytes) { 9309 // Src is inside the destination region for memcpy: invalid. 9310 Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar; 9311 return false; 9312 } 9313 } 9314 9315 while (true) { 9316 APValue Val; 9317 // FIXME: Set WantObjectRepresentation to true if we're copying a 9318 // char-like type? 9319 if (!handleLValueToRValueConversion(Info, E, T, Src, Val) || 9320 !handleAssignment(Info, E, Dest, T, Val)) 9321 return false; 9322 // Do not iterate past the last element; if we're copying backwards, that 9323 // might take us off the start of the array. 9324 if (--NElems == 0) 9325 return true; 9326 if (!HandleLValueArrayAdjustment(Info, E, Src, T, Direction) || 9327 !HandleLValueArrayAdjustment(Info, E, Dest, T, Direction)) 9328 return false; 9329 } 9330 } 9331 9332 default: 9333 break; 9334 } 9335 9336 return visitNonBuiltinCallExpr(E); 9337 } 9338 9339 static bool EvaluateArrayNewInitList(EvalInfo &Info, LValue &This, 9340 APValue &Result, const InitListExpr *ILE, 9341 QualType AllocType); 9342 static bool EvaluateArrayNewConstructExpr(EvalInfo &Info, LValue &This, 9343 APValue &Result, 9344 const CXXConstructExpr *CCE, 9345 QualType AllocType); 9346 9347 bool PointerExprEvaluator::VisitCXXNewExpr(const CXXNewExpr *E) { 9348 if (!Info.getLangOpts().CPlusPlus20) 9349 Info.CCEDiag(E, diag::note_constexpr_new); 9350 9351 // We cannot speculatively evaluate a delete expression. 9352 if (Info.SpeculativeEvaluationDepth) 9353 return false; 9354 9355 FunctionDecl *OperatorNew = E->getOperatorNew(); 9356 9357 bool IsNothrow = false; 9358 bool IsPlacement = false; 9359 if (OperatorNew->isReservedGlobalPlacementOperator() && 9360 Info.CurrentCall->isStdFunction() && !E->isArray()) { 9361 // FIXME Support array placement new. 9362 assert(E->getNumPlacementArgs() == 1); 9363 if (!EvaluatePointer(E->getPlacementArg(0), Result, Info)) 9364 return false; 9365 if (Result.Designator.Invalid) 9366 return false; 9367 IsPlacement = true; 9368 } else if (!OperatorNew->isReplaceableGlobalAllocationFunction()) { 9369 Info.FFDiag(E, diag::note_constexpr_new_non_replaceable) 9370 << isa<CXXMethodDecl>(OperatorNew) << OperatorNew; 9371 return false; 9372 } else if (E->getNumPlacementArgs()) { 9373 // The only new-placement list we support is of the form (std::nothrow). 9374 // 9375 // FIXME: There is no restriction on this, but it's not clear that any 9376 // other form makes any sense. We get here for cases such as: 9377 // 9378 // new (std::align_val_t{N}) X(int) 9379 // 9380 // (which should presumably be valid only if N is a multiple of 9381 // alignof(int), and in any case can't be deallocated unless N is 9382 // alignof(X) and X has new-extended alignment). 9383 if (E->getNumPlacementArgs() != 1 || 9384 !E->getPlacementArg(0)->getType()->isNothrowT()) 9385 return Error(E, diag::note_constexpr_new_placement); 9386 9387 LValue Nothrow; 9388 if (!EvaluateLValue(E->getPlacementArg(0), Nothrow, Info)) 9389 return false; 9390 IsNothrow = true; 9391 } 9392 9393 const Expr *Init = E->getInitializer(); 9394 const InitListExpr *ResizedArrayILE = nullptr; 9395 const CXXConstructExpr *ResizedArrayCCE = nullptr; 9396 bool ValueInit = false; 9397 9398 QualType AllocType = E->getAllocatedType(); 9399 if (Optional<const Expr*> ArraySize = E->getArraySize()) { 9400 const Expr *Stripped = *ArraySize; 9401 for (; auto *ICE = dyn_cast<ImplicitCastExpr>(Stripped); 9402 Stripped = ICE->getSubExpr()) 9403 if (ICE->getCastKind() != CK_NoOp && 9404 ICE->getCastKind() != CK_IntegralCast) 9405 break; 9406 9407 llvm::APSInt ArrayBound; 9408 if (!EvaluateInteger(Stripped, ArrayBound, Info)) 9409 return false; 9410 9411 // C++ [expr.new]p9: 9412 // The expression is erroneous if: 9413 // -- [...] its value before converting to size_t [or] applying the 9414 // second standard conversion sequence is less than zero 9415 if (ArrayBound.isSigned() && ArrayBound.isNegative()) { 9416 if (IsNothrow) 9417 return ZeroInitialization(E); 9418 9419 Info.FFDiag(*ArraySize, diag::note_constexpr_new_negative) 9420 << ArrayBound << (*ArraySize)->getSourceRange(); 9421 return false; 9422 } 9423 9424 // -- its value is such that the size of the allocated object would 9425 // exceed the implementation-defined limit 9426 if (ConstantArrayType::getNumAddressingBits(Info.Ctx, AllocType, 9427 ArrayBound) > 9428 ConstantArrayType::getMaxSizeBits(Info.Ctx)) { 9429 if (IsNothrow) 9430 return ZeroInitialization(E); 9431 9432 Info.FFDiag(*ArraySize, diag::note_constexpr_new_too_large) 9433 << ArrayBound << (*ArraySize)->getSourceRange(); 9434 return false; 9435 } 9436 9437 // -- the new-initializer is a braced-init-list and the number of 9438 // array elements for which initializers are provided [...] 9439 // exceeds the number of elements to initialize 9440 if (!Init) { 9441 // No initialization is performed. 9442 } else if (isa<CXXScalarValueInitExpr>(Init) || 9443 isa<ImplicitValueInitExpr>(Init)) { 9444 ValueInit = true; 9445 } else if (auto *CCE = dyn_cast<CXXConstructExpr>(Init)) { 9446 ResizedArrayCCE = CCE; 9447 } else { 9448 auto *CAT = Info.Ctx.getAsConstantArrayType(Init->getType()); 9449 assert(CAT && "unexpected type for array initializer"); 9450 9451 unsigned Bits = 9452 std::max(CAT->getSize().getBitWidth(), ArrayBound.getBitWidth()); 9453 llvm::APInt InitBound = CAT->getSize().zextOrSelf(Bits); 9454 llvm::APInt AllocBound = ArrayBound.zextOrSelf(Bits); 9455 if (InitBound.ugt(AllocBound)) { 9456 if (IsNothrow) 9457 return ZeroInitialization(E); 9458 9459 Info.FFDiag(*ArraySize, diag::note_constexpr_new_too_small) 9460 << toString(AllocBound, 10, /*Signed=*/false) 9461 << toString(InitBound, 10, /*Signed=*/false) 9462 << (*ArraySize)->getSourceRange(); 9463 return false; 9464 } 9465 9466 // If the sizes differ, we must have an initializer list, and we need 9467 // special handling for this case when we initialize. 9468 if (InitBound != AllocBound) 9469 ResizedArrayILE = cast<InitListExpr>(Init); 9470 } 9471 9472 AllocType = Info.Ctx.getConstantArrayType(AllocType, ArrayBound, nullptr, 9473 ArrayType::Normal, 0); 9474 } else { 9475 assert(!AllocType->isArrayType() && 9476 "array allocation with non-array new"); 9477 } 9478 9479 APValue *Val; 9480 if (IsPlacement) { 9481 AccessKinds AK = AK_Construct; 9482 struct FindObjectHandler { 9483 EvalInfo &Info; 9484 const Expr *E; 9485 QualType AllocType; 9486 const AccessKinds AccessKind; 9487 APValue *Value; 9488 9489 typedef bool result_type; 9490 bool failed() { return false; } 9491 bool found(APValue &Subobj, QualType SubobjType) { 9492 // FIXME: Reject the cases where [basic.life]p8 would not permit the 9493 // old name of the object to be used to name the new object. 9494 if (!Info.Ctx.hasSameUnqualifiedType(SubobjType, AllocType)) { 9495 Info.FFDiag(E, diag::note_constexpr_placement_new_wrong_type) << 9496 SubobjType << AllocType; 9497 return false; 9498 } 9499 Value = &Subobj; 9500 return true; 9501 } 9502 bool found(APSInt &Value, QualType SubobjType) { 9503 Info.FFDiag(E, diag::note_constexpr_construct_complex_elem); 9504 return false; 9505 } 9506 bool found(APFloat &Value, QualType SubobjType) { 9507 Info.FFDiag(E, diag::note_constexpr_construct_complex_elem); 9508 return false; 9509 } 9510 } Handler = {Info, E, AllocType, AK, nullptr}; 9511 9512 CompleteObject Obj = findCompleteObject(Info, E, AK, Result, AllocType); 9513 if (!Obj || !findSubobject(Info, E, Obj, Result.Designator, Handler)) 9514 return false; 9515 9516 Val = Handler.Value; 9517 9518 // [basic.life]p1: 9519 // The lifetime of an object o of type T ends when [...] the storage 9520 // which the object occupies is [...] reused by an object that is not 9521 // nested within o (6.6.2). 9522 *Val = APValue(); 9523 } else { 9524 // Perform the allocation and obtain a pointer to the resulting object. 9525 Val = Info.createHeapAlloc(E, AllocType, Result); 9526 if (!Val) 9527 return false; 9528 } 9529 9530 if (ValueInit) { 9531 ImplicitValueInitExpr VIE(AllocType); 9532 if (!EvaluateInPlace(*Val, Info, Result, &VIE)) 9533 return false; 9534 } else if (ResizedArrayILE) { 9535 if (!EvaluateArrayNewInitList(Info, Result, *Val, ResizedArrayILE, 9536 AllocType)) 9537 return false; 9538 } else if (ResizedArrayCCE) { 9539 if (!EvaluateArrayNewConstructExpr(Info, Result, *Val, ResizedArrayCCE, 9540 AllocType)) 9541 return false; 9542 } else if (Init) { 9543 if (!EvaluateInPlace(*Val, Info, Result, Init)) 9544 return false; 9545 } else if (!getDefaultInitValue(AllocType, *Val)) { 9546 return false; 9547 } 9548 9549 // Array new returns a pointer to the first element, not a pointer to the 9550 // array. 9551 if (auto *AT = AllocType->getAsArrayTypeUnsafe()) 9552 Result.addArray(Info, E, cast<ConstantArrayType>(AT)); 9553 9554 return true; 9555 } 9556 //===----------------------------------------------------------------------===// 9557 // Member Pointer Evaluation 9558 //===----------------------------------------------------------------------===// 9559 9560 namespace { 9561 class MemberPointerExprEvaluator 9562 : public ExprEvaluatorBase<MemberPointerExprEvaluator> { 9563 MemberPtr &Result; 9564 9565 bool Success(const ValueDecl *D) { 9566 Result = MemberPtr(D); 9567 return true; 9568 } 9569 public: 9570 9571 MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result) 9572 : ExprEvaluatorBaseTy(Info), Result(Result) {} 9573 9574 bool Success(const APValue &V, const Expr *E) { 9575 Result.setFrom(V); 9576 return true; 9577 } 9578 bool ZeroInitialization(const Expr *E) { 9579 return Success((const ValueDecl*)nullptr); 9580 } 9581 9582 bool VisitCastExpr(const CastExpr *E); 9583 bool VisitUnaryAddrOf(const UnaryOperator *E); 9584 }; 9585 } // end anonymous namespace 9586 9587 static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, 9588 EvalInfo &Info) { 9589 assert(!E->isValueDependent()); 9590 assert(E->isPRValue() && E->getType()->isMemberPointerType()); 9591 return MemberPointerExprEvaluator(Info, Result).Visit(E); 9592 } 9593 9594 bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) { 9595 switch (E->getCastKind()) { 9596 default: 9597 return ExprEvaluatorBaseTy::VisitCastExpr(E); 9598 9599 case CK_NullToMemberPointer: 9600 VisitIgnoredValue(E->getSubExpr()); 9601 return ZeroInitialization(E); 9602 9603 case CK_BaseToDerivedMemberPointer: { 9604 if (!Visit(E->getSubExpr())) 9605 return false; 9606 if (E->path_empty()) 9607 return true; 9608 // Base-to-derived member pointer casts store the path in derived-to-base 9609 // order, so iterate backwards. The CXXBaseSpecifier also provides us with 9610 // the wrong end of the derived->base arc, so stagger the path by one class. 9611 typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter; 9612 for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin()); 9613 PathI != PathE; ++PathI) { 9614 assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); 9615 const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl(); 9616 if (!Result.castToDerived(Derived)) 9617 return Error(E); 9618 } 9619 const Type *FinalTy = E->getType()->castAs<MemberPointerType>()->getClass(); 9620 if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl())) 9621 return Error(E); 9622 return true; 9623 } 9624 9625 case CK_DerivedToBaseMemberPointer: 9626 if (!Visit(E->getSubExpr())) 9627 return false; 9628 for (CastExpr::path_const_iterator PathI = E->path_begin(), 9629 PathE = E->path_end(); PathI != PathE; ++PathI) { 9630 assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); 9631 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); 9632 if (!Result.castToBase(Base)) 9633 return Error(E); 9634 } 9635 return true; 9636 } 9637 } 9638 9639 bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { 9640 // C++11 [expr.unary.op]p3 has very strict rules on how the address of a 9641 // member can be formed. 9642 return Success(cast<DeclRefExpr>(E->getSubExpr())->getDecl()); 9643 } 9644 9645 //===----------------------------------------------------------------------===// 9646 // Record Evaluation 9647 //===----------------------------------------------------------------------===// 9648 9649 namespace { 9650 class RecordExprEvaluator 9651 : public ExprEvaluatorBase<RecordExprEvaluator> { 9652 const LValue &This; 9653 APValue &Result; 9654 public: 9655 9656 RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result) 9657 : ExprEvaluatorBaseTy(info), This(This), Result(Result) {} 9658 9659 bool Success(const APValue &V, const Expr *E) { 9660 Result = V; 9661 return true; 9662 } 9663 bool ZeroInitialization(const Expr *E) { 9664 return ZeroInitialization(E, E->getType()); 9665 } 9666 bool ZeroInitialization(const Expr *E, QualType T); 9667 9668 bool VisitCallExpr(const CallExpr *E) { 9669 return handleCallExpr(E, Result, &This); 9670 } 9671 bool VisitCastExpr(const CastExpr *E); 9672 bool VisitInitListExpr(const InitListExpr *E); 9673 bool VisitCXXConstructExpr(const CXXConstructExpr *E) { 9674 return VisitCXXConstructExpr(E, E->getType()); 9675 } 9676 bool VisitLambdaExpr(const LambdaExpr *E); 9677 bool VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E); 9678 bool VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T); 9679 bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E); 9680 bool VisitBinCmp(const BinaryOperator *E); 9681 }; 9682 } 9683 9684 /// Perform zero-initialization on an object of non-union class type. 9685 /// C++11 [dcl.init]p5: 9686 /// To zero-initialize an object or reference of type T means: 9687 /// [...] 9688 /// -- if T is a (possibly cv-qualified) non-union class type, 9689 /// each non-static data member and each base-class subobject is 9690 /// zero-initialized 9691 static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E, 9692 const RecordDecl *RD, 9693 const LValue &This, APValue &Result) { 9694 assert(!RD->isUnion() && "Expected non-union class type"); 9695 const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD); 9696 Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0, 9697 std::distance(RD->field_begin(), RD->field_end())); 9698 9699 if (RD->isInvalidDecl()) return false; 9700 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 9701 9702 if (CD) { 9703 unsigned Index = 0; 9704 for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), 9705 End = CD->bases_end(); I != End; ++I, ++Index) { 9706 const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl(); 9707 LValue Subobject = This; 9708 if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout)) 9709 return false; 9710 if (!HandleClassZeroInitialization(Info, E, Base, Subobject, 9711 Result.getStructBase(Index))) 9712 return false; 9713 } 9714 } 9715 9716 for (const auto *I : RD->fields()) { 9717 // -- if T is a reference type, no initialization is performed. 9718 if (I->isUnnamedBitfield() || I->getType()->isReferenceType()) 9719 continue; 9720 9721 LValue Subobject = This; 9722 if (!HandleLValueMember(Info, E, Subobject, I, &Layout)) 9723 return false; 9724 9725 ImplicitValueInitExpr VIE(I->getType()); 9726 if (!EvaluateInPlace( 9727 Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE)) 9728 return false; 9729 } 9730 9731 return true; 9732 } 9733 9734 bool RecordExprEvaluator::ZeroInitialization(const Expr *E, QualType T) { 9735 const RecordDecl *RD = T->castAs<RecordType>()->getDecl(); 9736 if (RD->isInvalidDecl()) return false; 9737 if (RD->isUnion()) { 9738 // C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the 9739 // object's first non-static named data member is zero-initialized 9740 RecordDecl::field_iterator I = RD->field_begin(); 9741 while (I != RD->field_end() && (*I)->isUnnamedBitfield()) 9742 ++I; 9743 if (I == RD->field_end()) { 9744 Result = APValue((const FieldDecl*)nullptr); 9745 return true; 9746 } 9747 9748 LValue Subobject = This; 9749 if (!HandleLValueMember(Info, E, Subobject, *I)) 9750 return false; 9751 Result = APValue(*I); 9752 ImplicitValueInitExpr VIE(I->getType()); 9753 return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE); 9754 } 9755 9756 if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) { 9757 Info.FFDiag(E, diag::note_constexpr_virtual_base) << RD; 9758 return false; 9759 } 9760 9761 return HandleClassZeroInitialization(Info, E, RD, This, Result); 9762 } 9763 9764 bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) { 9765 switch (E->getCastKind()) { 9766 default: 9767 return ExprEvaluatorBaseTy::VisitCastExpr(E); 9768 9769 case CK_ConstructorConversion: 9770 return Visit(E->getSubExpr()); 9771 9772 case CK_DerivedToBase: 9773 case CK_UncheckedDerivedToBase: { 9774 APValue DerivedObject; 9775 if (!Evaluate(DerivedObject, Info, E->getSubExpr())) 9776 return false; 9777 if (!DerivedObject.isStruct()) 9778 return Error(E->getSubExpr()); 9779 9780 // Derived-to-base rvalue conversion: just slice off the derived part. 9781 APValue *Value = &DerivedObject; 9782 const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl(); 9783 for (CastExpr::path_const_iterator PathI = E->path_begin(), 9784 PathE = E->path_end(); PathI != PathE; ++PathI) { 9785 assert(!(*PathI)->isVirtual() && "record rvalue with virtual base"); 9786 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); 9787 Value = &Value->getStructBase(getBaseIndex(RD, Base)); 9788 RD = Base; 9789 } 9790 Result = *Value; 9791 return true; 9792 } 9793 } 9794 } 9795 9796 bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 9797 if (E->isTransparent()) 9798 return Visit(E->getInit(0)); 9799 9800 const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl(); 9801 if (RD->isInvalidDecl()) return false; 9802 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 9803 auto *CXXRD = dyn_cast<CXXRecordDecl>(RD); 9804 9805 EvalInfo::EvaluatingConstructorRAII EvalObj( 9806 Info, 9807 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries}, 9808 CXXRD && CXXRD->getNumBases()); 9809 9810 if (RD->isUnion()) { 9811 const FieldDecl *Field = E->getInitializedFieldInUnion(); 9812 Result = APValue(Field); 9813 if (!Field) 9814 return true; 9815 9816 // If the initializer list for a union does not contain any elements, the 9817 // first element of the union is value-initialized. 9818 // FIXME: The element should be initialized from an initializer list. 9819 // Is this difference ever observable for initializer lists which 9820 // we don't build? 9821 ImplicitValueInitExpr VIE(Field->getType()); 9822 const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE; 9823 9824 LValue Subobject = This; 9825 if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout)) 9826 return false; 9827 9828 // Temporarily override This, in case there's a CXXDefaultInitExpr in here. 9829 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, 9830 isa<CXXDefaultInitExpr>(InitExpr)); 9831 9832 if (EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr)) { 9833 if (Field->isBitField()) 9834 return truncateBitfieldValue(Info, InitExpr, Result.getUnionValue(), 9835 Field); 9836 return true; 9837 } 9838 9839 return false; 9840 } 9841 9842 if (!Result.hasValue()) 9843 Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0, 9844 std::distance(RD->field_begin(), RD->field_end())); 9845 unsigned ElementNo = 0; 9846 bool Success = true; 9847 9848 // Initialize base classes. 9849 if (CXXRD && CXXRD->getNumBases()) { 9850 for (const auto &Base : CXXRD->bases()) { 9851 assert(ElementNo < E->getNumInits() && "missing init for base class"); 9852 const Expr *Init = E->getInit(ElementNo); 9853 9854 LValue Subobject = This; 9855 if (!HandleLValueBase(Info, Init, Subobject, CXXRD, &Base)) 9856 return false; 9857 9858 APValue &FieldVal = Result.getStructBase(ElementNo); 9859 if (!EvaluateInPlace(FieldVal, Info, Subobject, Init)) { 9860 if (!Info.noteFailure()) 9861 return false; 9862 Success = false; 9863 } 9864 ++ElementNo; 9865 } 9866 9867 EvalObj.finishedConstructingBases(); 9868 } 9869 9870 // Initialize members. 9871 for (const auto *Field : RD->fields()) { 9872 // Anonymous bit-fields are not considered members of the class for 9873 // purposes of aggregate initialization. 9874 if (Field->isUnnamedBitfield()) 9875 continue; 9876 9877 LValue Subobject = This; 9878 9879 bool HaveInit = ElementNo < E->getNumInits(); 9880 9881 // FIXME: Diagnostics here should point to the end of the initializer 9882 // list, not the start. 9883 if (!HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E, 9884 Subobject, Field, &Layout)) 9885 return false; 9886 9887 // Perform an implicit value-initialization for members beyond the end of 9888 // the initializer list. 9889 ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType()); 9890 const Expr *Init = HaveInit ? E->getInit(ElementNo++) : &VIE; 9891 9892 // Temporarily override This, in case there's a CXXDefaultInitExpr in here. 9893 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, 9894 isa<CXXDefaultInitExpr>(Init)); 9895 9896 APValue &FieldVal = Result.getStructField(Field->getFieldIndex()); 9897 if (!EvaluateInPlace(FieldVal, Info, Subobject, Init) || 9898 (Field->isBitField() && !truncateBitfieldValue(Info, Init, 9899 FieldVal, Field))) { 9900 if (!Info.noteFailure()) 9901 return false; 9902 Success = false; 9903 } 9904 } 9905 9906 EvalObj.finishedConstructingFields(); 9907 9908 return Success; 9909 } 9910 9911 bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E, 9912 QualType T) { 9913 // Note that E's type is not necessarily the type of our class here; we might 9914 // be initializing an array element instead. 9915 const CXXConstructorDecl *FD = E->getConstructor(); 9916 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false; 9917 9918 bool ZeroInit = E->requiresZeroInitialization(); 9919 if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { 9920 // If we've already performed zero-initialization, we're already done. 9921 if (Result.hasValue()) 9922 return true; 9923 9924 if (ZeroInit) 9925 return ZeroInitialization(E, T); 9926 9927 return getDefaultInitValue(T, Result); 9928 } 9929 9930 const FunctionDecl *Definition = nullptr; 9931 auto Body = FD->getBody(Definition); 9932 9933 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body)) 9934 return false; 9935 9936 // Avoid materializing a temporary for an elidable copy/move constructor. 9937 if (E->isElidable() && !ZeroInit) { 9938 // FIXME: This only handles the simplest case, where the source object 9939 // is passed directly as the first argument to the constructor. 9940 // This should also handle stepping though implicit casts and 9941 // and conversion sequences which involve two steps, with a 9942 // conversion operator followed by a converting constructor. 9943 const Expr *SrcObj = E->getArg(0); 9944 assert(SrcObj->isTemporaryObject(Info.Ctx, FD->getParent())); 9945 assert(Info.Ctx.hasSameUnqualifiedType(E->getType(), SrcObj->getType())); 9946 if (const MaterializeTemporaryExpr *ME = 9947 dyn_cast<MaterializeTemporaryExpr>(SrcObj)) 9948 return Visit(ME->getSubExpr()); 9949 } 9950 9951 if (ZeroInit && !ZeroInitialization(E, T)) 9952 return false; 9953 9954 auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs()); 9955 return HandleConstructorCall(E, This, Args, 9956 cast<CXXConstructorDecl>(Definition), Info, 9957 Result); 9958 } 9959 9960 bool RecordExprEvaluator::VisitCXXInheritedCtorInitExpr( 9961 const CXXInheritedCtorInitExpr *E) { 9962 if (!Info.CurrentCall) { 9963 assert(Info.checkingPotentialConstantExpression()); 9964 return false; 9965 } 9966 9967 const CXXConstructorDecl *FD = E->getConstructor(); 9968 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) 9969 return false; 9970 9971 const FunctionDecl *Definition = nullptr; 9972 auto Body = FD->getBody(Definition); 9973 9974 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body)) 9975 return false; 9976 9977 return HandleConstructorCall(E, This, Info.CurrentCall->Arguments, 9978 cast<CXXConstructorDecl>(Definition), Info, 9979 Result); 9980 } 9981 9982 bool RecordExprEvaluator::VisitCXXStdInitializerListExpr( 9983 const CXXStdInitializerListExpr *E) { 9984 const ConstantArrayType *ArrayType = 9985 Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType()); 9986 9987 LValue Array; 9988 if (!EvaluateLValue(E->getSubExpr(), Array, Info)) 9989 return false; 9990 9991 // Get a pointer to the first element of the array. 9992 Array.addArray(Info, E, ArrayType); 9993 9994 auto InvalidType = [&] { 9995 Info.FFDiag(E, diag::note_constexpr_unsupported_layout) 9996 << E->getType(); 9997 return false; 9998 }; 9999 10000 // FIXME: Perform the checks on the field types in SemaInit. 10001 RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl(); 10002 RecordDecl::field_iterator Field = Record->field_begin(); 10003 if (Field == Record->field_end()) 10004 return InvalidType(); 10005 10006 // Start pointer. 10007 if (!Field->getType()->isPointerType() || 10008 !Info.Ctx.hasSameType(Field->getType()->getPointeeType(), 10009 ArrayType->getElementType())) 10010 return InvalidType(); 10011 10012 // FIXME: What if the initializer_list type has base classes, etc? 10013 Result = APValue(APValue::UninitStruct(), 0, 2); 10014 Array.moveInto(Result.getStructField(0)); 10015 10016 if (++Field == Record->field_end()) 10017 return InvalidType(); 10018 10019 if (Field->getType()->isPointerType() && 10020 Info.Ctx.hasSameType(Field->getType()->getPointeeType(), 10021 ArrayType->getElementType())) { 10022 // End pointer. 10023 if (!HandleLValueArrayAdjustment(Info, E, Array, 10024 ArrayType->getElementType(), 10025 ArrayType->getSize().getZExtValue())) 10026 return false; 10027 Array.moveInto(Result.getStructField(1)); 10028 } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType())) 10029 // Length. 10030 Result.getStructField(1) = APValue(APSInt(ArrayType->getSize())); 10031 else 10032 return InvalidType(); 10033 10034 if (++Field != Record->field_end()) 10035 return InvalidType(); 10036 10037 return true; 10038 } 10039 10040 bool RecordExprEvaluator::VisitLambdaExpr(const LambdaExpr *E) { 10041 const CXXRecordDecl *ClosureClass = E->getLambdaClass(); 10042 if (ClosureClass->isInvalidDecl()) 10043 return false; 10044 10045 const size_t NumFields = 10046 std::distance(ClosureClass->field_begin(), ClosureClass->field_end()); 10047 10048 assert(NumFields == (size_t)std::distance(E->capture_init_begin(), 10049 E->capture_init_end()) && 10050 "The number of lambda capture initializers should equal the number of " 10051 "fields within the closure type"); 10052 10053 Result = APValue(APValue::UninitStruct(), /*NumBases*/0, NumFields); 10054 // Iterate through all the lambda's closure object's fields and initialize 10055 // them. 10056 auto *CaptureInitIt = E->capture_init_begin(); 10057 const LambdaCapture *CaptureIt = ClosureClass->captures_begin(); 10058 bool Success = true; 10059 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(ClosureClass); 10060 for (const auto *Field : ClosureClass->fields()) { 10061 assert(CaptureInitIt != E->capture_init_end()); 10062 // Get the initializer for this field 10063 Expr *const CurFieldInit = *CaptureInitIt++; 10064 10065 // If there is no initializer, either this is a VLA or an error has 10066 // occurred. 10067 if (!CurFieldInit) 10068 return Error(E); 10069 10070 LValue Subobject = This; 10071 10072 if (!HandleLValueMember(Info, E, Subobject, Field, &Layout)) 10073 return false; 10074 10075 APValue &FieldVal = Result.getStructField(Field->getFieldIndex()); 10076 if (!EvaluateInPlace(FieldVal, Info, Subobject, CurFieldInit)) { 10077 if (!Info.keepEvaluatingAfterFailure()) 10078 return false; 10079 Success = false; 10080 } 10081 ++CaptureIt; 10082 } 10083 return Success; 10084 } 10085 10086 static bool EvaluateRecord(const Expr *E, const LValue &This, 10087 APValue &Result, EvalInfo &Info) { 10088 assert(!E->isValueDependent()); 10089 assert(E->isPRValue() && E->getType()->isRecordType() && 10090 "can't evaluate expression as a record rvalue"); 10091 return RecordExprEvaluator(Info, This, Result).Visit(E); 10092 } 10093 10094 //===----------------------------------------------------------------------===// 10095 // Temporary Evaluation 10096 // 10097 // Temporaries are represented in the AST as rvalues, but generally behave like 10098 // lvalues. The full-object of which the temporary is a subobject is implicitly 10099 // materialized so that a reference can bind to it. 10100 //===----------------------------------------------------------------------===// 10101 namespace { 10102 class TemporaryExprEvaluator 10103 : public LValueExprEvaluatorBase<TemporaryExprEvaluator> { 10104 public: 10105 TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) : 10106 LValueExprEvaluatorBaseTy(Info, Result, false) {} 10107 10108 /// Visit an expression which constructs the value of this temporary. 10109 bool VisitConstructExpr(const Expr *E) { 10110 APValue &Value = Info.CurrentCall->createTemporary( 10111 E, E->getType(), ScopeKind::FullExpression, Result); 10112 return EvaluateInPlace(Value, Info, Result, E); 10113 } 10114 10115 bool VisitCastExpr(const CastExpr *E) { 10116 switch (E->getCastKind()) { 10117 default: 10118 return LValueExprEvaluatorBaseTy::VisitCastExpr(E); 10119 10120 case CK_ConstructorConversion: 10121 return VisitConstructExpr(E->getSubExpr()); 10122 } 10123 } 10124 bool VisitInitListExpr(const InitListExpr *E) { 10125 return VisitConstructExpr(E); 10126 } 10127 bool VisitCXXConstructExpr(const CXXConstructExpr *E) { 10128 return VisitConstructExpr(E); 10129 } 10130 bool VisitCallExpr(const CallExpr *E) { 10131 return VisitConstructExpr(E); 10132 } 10133 bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E) { 10134 return VisitConstructExpr(E); 10135 } 10136 bool VisitLambdaExpr(const LambdaExpr *E) { 10137 return VisitConstructExpr(E); 10138 } 10139 }; 10140 } // end anonymous namespace 10141 10142 /// Evaluate an expression of record type as a temporary. 10143 static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) { 10144 assert(!E->isValueDependent()); 10145 assert(E->isPRValue() && E->getType()->isRecordType()); 10146 return TemporaryExprEvaluator(Info, Result).Visit(E); 10147 } 10148 10149 //===----------------------------------------------------------------------===// 10150 // Vector Evaluation 10151 //===----------------------------------------------------------------------===// 10152 10153 namespace { 10154 class VectorExprEvaluator 10155 : public ExprEvaluatorBase<VectorExprEvaluator> { 10156 APValue &Result; 10157 public: 10158 10159 VectorExprEvaluator(EvalInfo &info, APValue &Result) 10160 : ExprEvaluatorBaseTy(info), Result(Result) {} 10161 10162 bool Success(ArrayRef<APValue> V, const Expr *E) { 10163 assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements()); 10164 // FIXME: remove this APValue copy. 10165 Result = APValue(V.data(), V.size()); 10166 return true; 10167 } 10168 bool Success(const APValue &V, const Expr *E) { 10169 assert(V.isVector()); 10170 Result = V; 10171 return true; 10172 } 10173 bool ZeroInitialization(const Expr *E); 10174 10175 bool VisitUnaryReal(const UnaryOperator *E) 10176 { return Visit(E->getSubExpr()); } 10177 bool VisitCastExpr(const CastExpr* E); 10178 bool VisitInitListExpr(const InitListExpr *E); 10179 bool VisitUnaryImag(const UnaryOperator *E); 10180 bool VisitBinaryOperator(const BinaryOperator *E); 10181 // FIXME: Missing: unary -, unary ~, conditional operator (for GNU 10182 // conditional select), shufflevector, ExtVectorElementExpr 10183 }; 10184 } // end anonymous namespace 10185 10186 static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) { 10187 assert(E->isPRValue() && E->getType()->isVectorType() && 10188 "not a vector prvalue"); 10189 return VectorExprEvaluator(Info, Result).Visit(E); 10190 } 10191 10192 bool VectorExprEvaluator::VisitCastExpr(const CastExpr *E) { 10193 const VectorType *VTy = E->getType()->castAs<VectorType>(); 10194 unsigned NElts = VTy->getNumElements(); 10195 10196 const Expr *SE = E->getSubExpr(); 10197 QualType SETy = SE->getType(); 10198 10199 switch (E->getCastKind()) { 10200 case CK_VectorSplat: { 10201 APValue Val = APValue(); 10202 if (SETy->isIntegerType()) { 10203 APSInt IntResult; 10204 if (!EvaluateInteger(SE, IntResult, Info)) 10205 return false; 10206 Val = APValue(std::move(IntResult)); 10207 } else if (SETy->isRealFloatingType()) { 10208 APFloat FloatResult(0.0); 10209 if (!EvaluateFloat(SE, FloatResult, Info)) 10210 return false; 10211 Val = APValue(std::move(FloatResult)); 10212 } else { 10213 return Error(E); 10214 } 10215 10216 // Splat and create vector APValue. 10217 SmallVector<APValue, 4> Elts(NElts, Val); 10218 return Success(Elts, E); 10219 } 10220 case CK_BitCast: { 10221 // Evaluate the operand into an APInt we can extract from. 10222 llvm::APInt SValInt; 10223 if (!EvalAndBitcastToAPInt(Info, SE, SValInt)) 10224 return false; 10225 // Extract the elements 10226 QualType EltTy = VTy->getElementType(); 10227 unsigned EltSize = Info.Ctx.getTypeSize(EltTy); 10228 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); 10229 SmallVector<APValue, 4> Elts; 10230 if (EltTy->isRealFloatingType()) { 10231 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(EltTy); 10232 unsigned FloatEltSize = EltSize; 10233 if (&Sem == &APFloat::x87DoubleExtended()) 10234 FloatEltSize = 80; 10235 for (unsigned i = 0; i < NElts; i++) { 10236 llvm::APInt Elt; 10237 if (BigEndian) 10238 Elt = SValInt.rotl(i*EltSize+FloatEltSize).trunc(FloatEltSize); 10239 else 10240 Elt = SValInt.rotr(i*EltSize).trunc(FloatEltSize); 10241 Elts.push_back(APValue(APFloat(Sem, Elt))); 10242 } 10243 } else if (EltTy->isIntegerType()) { 10244 for (unsigned i = 0; i < NElts; i++) { 10245 llvm::APInt Elt; 10246 if (BigEndian) 10247 Elt = SValInt.rotl(i*EltSize+EltSize).zextOrTrunc(EltSize); 10248 else 10249 Elt = SValInt.rotr(i*EltSize).zextOrTrunc(EltSize); 10250 Elts.push_back(APValue(APSInt(Elt, !EltTy->isSignedIntegerType()))); 10251 } 10252 } else { 10253 return Error(E); 10254 } 10255 return Success(Elts, E); 10256 } 10257 default: 10258 return ExprEvaluatorBaseTy::VisitCastExpr(E); 10259 } 10260 } 10261 10262 bool 10263 VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 10264 const VectorType *VT = E->getType()->castAs<VectorType>(); 10265 unsigned NumInits = E->getNumInits(); 10266 unsigned NumElements = VT->getNumElements(); 10267 10268 QualType EltTy = VT->getElementType(); 10269 SmallVector<APValue, 4> Elements; 10270 10271 // The number of initializers can be less than the number of 10272 // vector elements. For OpenCL, this can be due to nested vector 10273 // initialization. For GCC compatibility, missing trailing elements 10274 // should be initialized with zeroes. 10275 unsigned CountInits = 0, CountElts = 0; 10276 while (CountElts < NumElements) { 10277 // Handle nested vector initialization. 10278 if (CountInits < NumInits 10279 && E->getInit(CountInits)->getType()->isVectorType()) { 10280 APValue v; 10281 if (!EvaluateVector(E->getInit(CountInits), v, Info)) 10282 return Error(E); 10283 unsigned vlen = v.getVectorLength(); 10284 for (unsigned j = 0; j < vlen; j++) 10285 Elements.push_back(v.getVectorElt(j)); 10286 CountElts += vlen; 10287 } else if (EltTy->isIntegerType()) { 10288 llvm::APSInt sInt(32); 10289 if (CountInits < NumInits) { 10290 if (!EvaluateInteger(E->getInit(CountInits), sInt, Info)) 10291 return false; 10292 } else // trailing integer zero. 10293 sInt = Info.Ctx.MakeIntValue(0, EltTy); 10294 Elements.push_back(APValue(sInt)); 10295 CountElts++; 10296 } else { 10297 llvm::APFloat f(0.0); 10298 if (CountInits < NumInits) { 10299 if (!EvaluateFloat(E->getInit(CountInits), f, Info)) 10300 return false; 10301 } else // trailing float zero. 10302 f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)); 10303 Elements.push_back(APValue(f)); 10304 CountElts++; 10305 } 10306 CountInits++; 10307 } 10308 return Success(Elements, E); 10309 } 10310 10311 bool 10312 VectorExprEvaluator::ZeroInitialization(const Expr *E) { 10313 const auto *VT = E->getType()->castAs<VectorType>(); 10314 QualType EltTy = VT->getElementType(); 10315 APValue ZeroElement; 10316 if (EltTy->isIntegerType()) 10317 ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy)); 10318 else 10319 ZeroElement = 10320 APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy))); 10321 10322 SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement); 10323 return Success(Elements, E); 10324 } 10325 10326 bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 10327 VisitIgnoredValue(E->getSubExpr()); 10328 return ZeroInitialization(E); 10329 } 10330 10331 bool VectorExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 10332 BinaryOperatorKind Op = E->getOpcode(); 10333 assert(Op != BO_PtrMemD && Op != BO_PtrMemI && Op != BO_Cmp && 10334 "Operation not supported on vector types"); 10335 10336 if (Op == BO_Comma) 10337 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 10338 10339 Expr *LHS = E->getLHS(); 10340 Expr *RHS = E->getRHS(); 10341 10342 assert(LHS->getType()->isVectorType() && RHS->getType()->isVectorType() && 10343 "Must both be vector types"); 10344 // Checking JUST the types are the same would be fine, except shifts don't 10345 // need to have their types be the same (since you always shift by an int). 10346 assert(LHS->getType()->castAs<VectorType>()->getNumElements() == 10347 E->getType()->castAs<VectorType>()->getNumElements() && 10348 RHS->getType()->castAs<VectorType>()->getNumElements() == 10349 E->getType()->castAs<VectorType>()->getNumElements() && 10350 "All operands must be the same size."); 10351 10352 APValue LHSValue; 10353 APValue RHSValue; 10354 bool LHSOK = Evaluate(LHSValue, Info, LHS); 10355 if (!LHSOK && !Info.noteFailure()) 10356 return false; 10357 if (!Evaluate(RHSValue, Info, RHS) || !LHSOK) 10358 return false; 10359 10360 if (!handleVectorVectorBinOp(Info, E, Op, LHSValue, RHSValue)) 10361 return false; 10362 10363 return Success(LHSValue, E); 10364 } 10365 10366 //===----------------------------------------------------------------------===// 10367 // Array Evaluation 10368 //===----------------------------------------------------------------------===// 10369 10370 namespace { 10371 class ArrayExprEvaluator 10372 : public ExprEvaluatorBase<ArrayExprEvaluator> { 10373 const LValue &This; 10374 APValue &Result; 10375 public: 10376 10377 ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result) 10378 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {} 10379 10380 bool Success(const APValue &V, const Expr *E) { 10381 assert(V.isArray() && "expected array"); 10382 Result = V; 10383 return true; 10384 } 10385 10386 bool ZeroInitialization(const Expr *E) { 10387 const ConstantArrayType *CAT = 10388 Info.Ctx.getAsConstantArrayType(E->getType()); 10389 if (!CAT) { 10390 if (E->getType()->isIncompleteArrayType()) { 10391 // We can be asked to zero-initialize a flexible array member; this 10392 // is represented as an ImplicitValueInitExpr of incomplete array 10393 // type. In this case, the array has zero elements. 10394 Result = APValue(APValue::UninitArray(), 0, 0); 10395 return true; 10396 } 10397 // FIXME: We could handle VLAs here. 10398 return Error(E); 10399 } 10400 10401 Result = APValue(APValue::UninitArray(), 0, 10402 CAT->getSize().getZExtValue()); 10403 if (!Result.hasArrayFiller()) 10404 return true; 10405 10406 // Zero-initialize all elements. 10407 LValue Subobject = This; 10408 Subobject.addArray(Info, E, CAT); 10409 ImplicitValueInitExpr VIE(CAT->getElementType()); 10410 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE); 10411 } 10412 10413 bool VisitCallExpr(const CallExpr *E) { 10414 return handleCallExpr(E, Result, &This); 10415 } 10416 bool VisitInitListExpr(const InitListExpr *E, 10417 QualType AllocType = QualType()); 10418 bool VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E); 10419 bool VisitCXXConstructExpr(const CXXConstructExpr *E); 10420 bool VisitCXXConstructExpr(const CXXConstructExpr *E, 10421 const LValue &Subobject, 10422 APValue *Value, QualType Type); 10423 bool VisitStringLiteral(const StringLiteral *E, 10424 QualType AllocType = QualType()) { 10425 expandStringLiteral(Info, E, Result, AllocType); 10426 return true; 10427 } 10428 }; 10429 } // end anonymous namespace 10430 10431 static bool EvaluateArray(const Expr *E, const LValue &This, 10432 APValue &Result, EvalInfo &Info) { 10433 assert(!E->isValueDependent()); 10434 assert(E->isPRValue() && E->getType()->isArrayType() && 10435 "not an array prvalue"); 10436 return ArrayExprEvaluator(Info, This, Result).Visit(E); 10437 } 10438 10439 static bool EvaluateArrayNewInitList(EvalInfo &Info, LValue &This, 10440 APValue &Result, const InitListExpr *ILE, 10441 QualType AllocType) { 10442 assert(!ILE->isValueDependent()); 10443 assert(ILE->isPRValue() && ILE->getType()->isArrayType() && 10444 "not an array prvalue"); 10445 return ArrayExprEvaluator(Info, This, Result) 10446 .VisitInitListExpr(ILE, AllocType); 10447 } 10448 10449 static bool EvaluateArrayNewConstructExpr(EvalInfo &Info, LValue &This, 10450 APValue &Result, 10451 const CXXConstructExpr *CCE, 10452 QualType AllocType) { 10453 assert(!CCE->isValueDependent()); 10454 assert(CCE->isPRValue() && CCE->getType()->isArrayType() && 10455 "not an array prvalue"); 10456 return ArrayExprEvaluator(Info, This, Result) 10457 .VisitCXXConstructExpr(CCE, This, &Result, AllocType); 10458 } 10459 10460 // Return true iff the given array filler may depend on the element index. 10461 static bool MaybeElementDependentArrayFiller(const Expr *FillerExpr) { 10462 // For now, just allow non-class value-initialization and initialization 10463 // lists comprised of them. 10464 if (isa<ImplicitValueInitExpr>(FillerExpr)) 10465 return false; 10466 if (const InitListExpr *ILE = dyn_cast<InitListExpr>(FillerExpr)) { 10467 for (unsigned I = 0, E = ILE->getNumInits(); I != E; ++I) { 10468 if (MaybeElementDependentArrayFiller(ILE->getInit(I))) 10469 return true; 10470 } 10471 return false; 10472 } 10473 return true; 10474 } 10475 10476 bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E, 10477 QualType AllocType) { 10478 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType( 10479 AllocType.isNull() ? E->getType() : AllocType); 10480 if (!CAT) 10481 return Error(E); 10482 10483 // C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...] 10484 // an appropriately-typed string literal enclosed in braces. 10485 if (E->isStringLiteralInit()) { 10486 auto *SL = dyn_cast<StringLiteral>(E->getInit(0)->IgnoreParens()); 10487 // FIXME: Support ObjCEncodeExpr here once we support it in 10488 // ArrayExprEvaluator generally. 10489 if (!SL) 10490 return Error(E); 10491 return VisitStringLiteral(SL, AllocType); 10492 } 10493 10494 bool Success = true; 10495 10496 assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) && 10497 "zero-initialized array shouldn't have any initialized elts"); 10498 APValue Filler; 10499 if (Result.isArray() && Result.hasArrayFiller()) 10500 Filler = Result.getArrayFiller(); 10501 10502 unsigned NumEltsToInit = E->getNumInits(); 10503 unsigned NumElts = CAT->getSize().getZExtValue(); 10504 const Expr *FillerExpr = E->hasArrayFiller() ? E->getArrayFiller() : nullptr; 10505 10506 // If the initializer might depend on the array index, run it for each 10507 // array element. 10508 if (NumEltsToInit != NumElts && MaybeElementDependentArrayFiller(FillerExpr)) 10509 NumEltsToInit = NumElts; 10510 10511 LLVM_DEBUG(llvm::dbgs() << "The number of elements to initialize: " 10512 << NumEltsToInit << ".\n"); 10513 10514 Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts); 10515 10516 // If the array was previously zero-initialized, preserve the 10517 // zero-initialized values. 10518 if (Filler.hasValue()) { 10519 for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I) 10520 Result.getArrayInitializedElt(I) = Filler; 10521 if (Result.hasArrayFiller()) 10522 Result.getArrayFiller() = Filler; 10523 } 10524 10525 LValue Subobject = This; 10526 Subobject.addArray(Info, E, CAT); 10527 for (unsigned Index = 0; Index != NumEltsToInit; ++Index) { 10528 const Expr *Init = 10529 Index < E->getNumInits() ? E->getInit(Index) : FillerExpr; 10530 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index), 10531 Info, Subobject, Init) || 10532 !HandleLValueArrayAdjustment(Info, Init, Subobject, 10533 CAT->getElementType(), 1)) { 10534 if (!Info.noteFailure()) 10535 return false; 10536 Success = false; 10537 } 10538 } 10539 10540 if (!Result.hasArrayFiller()) 10541 return Success; 10542 10543 // If we get here, we have a trivial filler, which we can just evaluate 10544 // once and splat over the rest of the array elements. 10545 assert(FillerExpr && "no array filler for incomplete init list"); 10546 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, 10547 FillerExpr) && Success; 10548 } 10549 10550 bool ArrayExprEvaluator::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E) { 10551 LValue CommonLV; 10552 if (E->getCommonExpr() && 10553 !Evaluate(Info.CurrentCall->createTemporary( 10554 E->getCommonExpr(), 10555 getStorageType(Info.Ctx, E->getCommonExpr()), 10556 ScopeKind::FullExpression, CommonLV), 10557 Info, E->getCommonExpr()->getSourceExpr())) 10558 return false; 10559 10560 auto *CAT = cast<ConstantArrayType>(E->getType()->castAsArrayTypeUnsafe()); 10561 10562 uint64_t Elements = CAT->getSize().getZExtValue(); 10563 Result = APValue(APValue::UninitArray(), Elements, Elements); 10564 10565 LValue Subobject = This; 10566 Subobject.addArray(Info, E, CAT); 10567 10568 bool Success = true; 10569 for (EvalInfo::ArrayInitLoopIndex Index(Info); Index != Elements; ++Index) { 10570 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index), 10571 Info, Subobject, E->getSubExpr()) || 10572 !HandleLValueArrayAdjustment(Info, E, Subobject, 10573 CAT->getElementType(), 1)) { 10574 if (!Info.noteFailure()) 10575 return false; 10576 Success = false; 10577 } 10578 } 10579 10580 return Success; 10581 } 10582 10583 bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { 10584 return VisitCXXConstructExpr(E, This, &Result, E->getType()); 10585 } 10586 10587 bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E, 10588 const LValue &Subobject, 10589 APValue *Value, 10590 QualType Type) { 10591 bool HadZeroInit = Value->hasValue(); 10592 10593 if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) { 10594 unsigned N = CAT->getSize().getZExtValue(); 10595 10596 // Preserve the array filler if we had prior zero-initialization. 10597 APValue Filler = 10598 HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller() 10599 : APValue(); 10600 10601 *Value = APValue(APValue::UninitArray(), N, N); 10602 10603 if (HadZeroInit) 10604 for (unsigned I = 0; I != N; ++I) 10605 Value->getArrayInitializedElt(I) = Filler; 10606 10607 // Initialize the elements. 10608 LValue ArrayElt = Subobject; 10609 ArrayElt.addArray(Info, E, CAT); 10610 for (unsigned I = 0; I != N; ++I) 10611 if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I), 10612 CAT->getElementType()) || 10613 !HandleLValueArrayAdjustment(Info, E, ArrayElt, 10614 CAT->getElementType(), 1)) 10615 return false; 10616 10617 return true; 10618 } 10619 10620 if (!Type->isRecordType()) 10621 return Error(E); 10622 10623 return RecordExprEvaluator(Info, Subobject, *Value) 10624 .VisitCXXConstructExpr(E, Type); 10625 } 10626 10627 //===----------------------------------------------------------------------===// 10628 // Integer Evaluation 10629 // 10630 // As a GNU extension, we support casting pointers to sufficiently-wide integer 10631 // types and back in constant folding. Integer values are thus represented 10632 // either as an integer-valued APValue, or as an lvalue-valued APValue. 10633 //===----------------------------------------------------------------------===// 10634 10635 namespace { 10636 class IntExprEvaluator 10637 : public ExprEvaluatorBase<IntExprEvaluator> { 10638 APValue &Result; 10639 public: 10640 IntExprEvaluator(EvalInfo &info, APValue &result) 10641 : ExprEvaluatorBaseTy(info), Result(result) {} 10642 10643 bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) { 10644 assert(E->getType()->isIntegralOrEnumerationType() && 10645 "Invalid evaluation result."); 10646 assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() && 10647 "Invalid evaluation result."); 10648 assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && 10649 "Invalid evaluation result."); 10650 Result = APValue(SI); 10651 return true; 10652 } 10653 bool Success(const llvm::APSInt &SI, const Expr *E) { 10654 return Success(SI, E, Result); 10655 } 10656 10657 bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) { 10658 assert(E->getType()->isIntegralOrEnumerationType() && 10659 "Invalid evaluation result."); 10660 assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && 10661 "Invalid evaluation result."); 10662 Result = APValue(APSInt(I)); 10663 Result.getInt().setIsUnsigned( 10664 E->getType()->isUnsignedIntegerOrEnumerationType()); 10665 return true; 10666 } 10667 bool Success(const llvm::APInt &I, const Expr *E) { 10668 return Success(I, E, Result); 10669 } 10670 10671 bool Success(uint64_t Value, const Expr *E, APValue &Result) { 10672 assert(E->getType()->isIntegralOrEnumerationType() && 10673 "Invalid evaluation result."); 10674 Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType())); 10675 return true; 10676 } 10677 bool Success(uint64_t Value, const Expr *E) { 10678 return Success(Value, E, Result); 10679 } 10680 10681 bool Success(CharUnits Size, const Expr *E) { 10682 return Success(Size.getQuantity(), E); 10683 } 10684 10685 bool Success(const APValue &V, const Expr *E) { 10686 if (V.isLValue() || V.isAddrLabelDiff() || V.isIndeterminate()) { 10687 Result = V; 10688 return true; 10689 } 10690 return Success(V.getInt(), E); 10691 } 10692 10693 bool ZeroInitialization(const Expr *E) { return Success(0, E); } 10694 10695 //===--------------------------------------------------------------------===// 10696 // Visitor Methods 10697 //===--------------------------------------------------------------------===// 10698 10699 bool VisitIntegerLiteral(const IntegerLiteral *E) { 10700 return Success(E->getValue(), E); 10701 } 10702 bool VisitCharacterLiteral(const CharacterLiteral *E) { 10703 return Success(E->getValue(), E); 10704 } 10705 10706 bool CheckReferencedDecl(const Expr *E, const Decl *D); 10707 bool VisitDeclRefExpr(const DeclRefExpr *E) { 10708 if (CheckReferencedDecl(E, E->getDecl())) 10709 return true; 10710 10711 return ExprEvaluatorBaseTy::VisitDeclRefExpr(E); 10712 } 10713 bool VisitMemberExpr(const MemberExpr *E) { 10714 if (CheckReferencedDecl(E, E->getMemberDecl())) { 10715 VisitIgnoredBaseExpression(E->getBase()); 10716 return true; 10717 } 10718 10719 return ExprEvaluatorBaseTy::VisitMemberExpr(E); 10720 } 10721 10722 bool VisitCallExpr(const CallExpr *E); 10723 bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp); 10724 bool VisitBinaryOperator(const BinaryOperator *E); 10725 bool VisitOffsetOfExpr(const OffsetOfExpr *E); 10726 bool VisitUnaryOperator(const UnaryOperator *E); 10727 10728 bool VisitCastExpr(const CastExpr* E); 10729 bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E); 10730 10731 bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) { 10732 return Success(E->getValue(), E); 10733 } 10734 10735 bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) { 10736 return Success(E->getValue(), E); 10737 } 10738 10739 bool VisitArrayInitIndexExpr(const ArrayInitIndexExpr *E) { 10740 if (Info.ArrayInitIndex == uint64_t(-1)) { 10741 // We were asked to evaluate this subexpression independent of the 10742 // enclosing ArrayInitLoopExpr. We can't do that. 10743 Info.FFDiag(E); 10744 return false; 10745 } 10746 return Success(Info.ArrayInitIndex, E); 10747 } 10748 10749 // Note, GNU defines __null as an integer, not a pointer. 10750 bool VisitGNUNullExpr(const GNUNullExpr *E) { 10751 return ZeroInitialization(E); 10752 } 10753 10754 bool VisitTypeTraitExpr(const TypeTraitExpr *E) { 10755 return Success(E->getValue(), E); 10756 } 10757 10758 bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) { 10759 return Success(E->getValue(), E); 10760 } 10761 10762 bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) { 10763 return Success(E->getValue(), E); 10764 } 10765 10766 bool VisitUnaryReal(const UnaryOperator *E); 10767 bool VisitUnaryImag(const UnaryOperator *E); 10768 10769 bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E); 10770 bool VisitSizeOfPackExpr(const SizeOfPackExpr *E); 10771 bool VisitSourceLocExpr(const SourceLocExpr *E); 10772 bool VisitConceptSpecializationExpr(const ConceptSpecializationExpr *E); 10773 bool VisitRequiresExpr(const RequiresExpr *E); 10774 // FIXME: Missing: array subscript of vector, member of vector 10775 }; 10776 10777 class FixedPointExprEvaluator 10778 : public ExprEvaluatorBase<FixedPointExprEvaluator> { 10779 APValue &Result; 10780 10781 public: 10782 FixedPointExprEvaluator(EvalInfo &info, APValue &result) 10783 : ExprEvaluatorBaseTy(info), Result(result) {} 10784 10785 bool Success(const llvm::APInt &I, const Expr *E) { 10786 return Success( 10787 APFixedPoint(I, Info.Ctx.getFixedPointSemantics(E->getType())), E); 10788 } 10789 10790 bool Success(uint64_t Value, const Expr *E) { 10791 return Success( 10792 APFixedPoint(Value, Info.Ctx.getFixedPointSemantics(E->getType())), E); 10793 } 10794 10795 bool Success(const APValue &V, const Expr *E) { 10796 return Success(V.getFixedPoint(), E); 10797 } 10798 10799 bool Success(const APFixedPoint &V, const Expr *E) { 10800 assert(E->getType()->isFixedPointType() && "Invalid evaluation result."); 10801 assert(V.getWidth() == Info.Ctx.getIntWidth(E->getType()) && 10802 "Invalid evaluation result."); 10803 Result = APValue(V); 10804 return true; 10805 } 10806 10807 //===--------------------------------------------------------------------===// 10808 // Visitor Methods 10809 //===--------------------------------------------------------------------===// 10810 10811 bool VisitFixedPointLiteral(const FixedPointLiteral *E) { 10812 return Success(E->getValue(), E); 10813 } 10814 10815 bool VisitCastExpr(const CastExpr *E); 10816 bool VisitUnaryOperator(const UnaryOperator *E); 10817 bool VisitBinaryOperator(const BinaryOperator *E); 10818 }; 10819 } // end anonymous namespace 10820 10821 /// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and 10822 /// produce either the integer value or a pointer. 10823 /// 10824 /// GCC has a heinous extension which folds casts between pointer types and 10825 /// pointer-sized integral types. We support this by allowing the evaluation of 10826 /// an integer rvalue to produce a pointer (represented as an lvalue) instead. 10827 /// Some simple arithmetic on such values is supported (they are treated much 10828 /// like char*). 10829 static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, 10830 EvalInfo &Info) { 10831 assert(!E->isValueDependent()); 10832 assert(E->isPRValue() && E->getType()->isIntegralOrEnumerationType()); 10833 return IntExprEvaluator(Info, Result).Visit(E); 10834 } 10835 10836 static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) { 10837 assert(!E->isValueDependent()); 10838 APValue Val; 10839 if (!EvaluateIntegerOrLValue(E, Val, Info)) 10840 return false; 10841 if (!Val.isInt()) { 10842 // FIXME: It would be better to produce the diagnostic for casting 10843 // a pointer to an integer. 10844 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 10845 return false; 10846 } 10847 Result = Val.getInt(); 10848 return true; 10849 } 10850 10851 bool IntExprEvaluator::VisitSourceLocExpr(const SourceLocExpr *E) { 10852 APValue Evaluated = E->EvaluateInContext( 10853 Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr()); 10854 return Success(Evaluated, E); 10855 } 10856 10857 static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result, 10858 EvalInfo &Info) { 10859 assert(!E->isValueDependent()); 10860 if (E->getType()->isFixedPointType()) { 10861 APValue Val; 10862 if (!FixedPointExprEvaluator(Info, Val).Visit(E)) 10863 return false; 10864 if (!Val.isFixedPoint()) 10865 return false; 10866 10867 Result = Val.getFixedPoint(); 10868 return true; 10869 } 10870 return false; 10871 } 10872 10873 static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result, 10874 EvalInfo &Info) { 10875 assert(!E->isValueDependent()); 10876 if (E->getType()->isIntegerType()) { 10877 auto FXSema = Info.Ctx.getFixedPointSemantics(E->getType()); 10878 APSInt Val; 10879 if (!EvaluateInteger(E, Val, Info)) 10880 return false; 10881 Result = APFixedPoint(Val, FXSema); 10882 return true; 10883 } else if (E->getType()->isFixedPointType()) { 10884 return EvaluateFixedPoint(E, Result, Info); 10885 } 10886 return false; 10887 } 10888 10889 /// Check whether the given declaration can be directly converted to an integral 10890 /// rvalue. If not, no diagnostic is produced; there are other things we can 10891 /// try. 10892 bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) { 10893 // Enums are integer constant exprs. 10894 if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) { 10895 // Check for signedness/width mismatches between E type and ECD value. 10896 bool SameSign = (ECD->getInitVal().isSigned() 10897 == E->getType()->isSignedIntegerOrEnumerationType()); 10898 bool SameWidth = (ECD->getInitVal().getBitWidth() 10899 == Info.Ctx.getIntWidth(E->getType())); 10900 if (SameSign && SameWidth) 10901 return Success(ECD->getInitVal(), E); 10902 else { 10903 // Get rid of mismatch (otherwise Success assertions will fail) 10904 // by computing a new value matching the type of E. 10905 llvm::APSInt Val = ECD->getInitVal(); 10906 if (!SameSign) 10907 Val.setIsSigned(!ECD->getInitVal().isSigned()); 10908 if (!SameWidth) 10909 Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType())); 10910 return Success(Val, E); 10911 } 10912 } 10913 return false; 10914 } 10915 10916 /// Values returned by __builtin_classify_type, chosen to match the values 10917 /// produced by GCC's builtin. 10918 enum class GCCTypeClass { 10919 None = -1, 10920 Void = 0, 10921 Integer = 1, 10922 // GCC reserves 2 for character types, but instead classifies them as 10923 // integers. 10924 Enum = 3, 10925 Bool = 4, 10926 Pointer = 5, 10927 // GCC reserves 6 for references, but appears to never use it (because 10928 // expressions never have reference type, presumably). 10929 PointerToDataMember = 7, 10930 RealFloat = 8, 10931 Complex = 9, 10932 // GCC reserves 10 for functions, but does not use it since GCC version 6 due 10933 // to decay to pointer. (Prior to version 6 it was only used in C++ mode). 10934 // GCC claims to reserve 11 for pointers to member functions, but *actually* 10935 // uses 12 for that purpose, same as for a class or struct. Maybe it 10936 // internally implements a pointer to member as a struct? Who knows. 10937 PointerToMemberFunction = 12, // Not a bug, see above. 10938 ClassOrStruct = 12, 10939 Union = 13, 10940 // GCC reserves 14 for arrays, but does not use it since GCC version 6 due to 10941 // decay to pointer. (Prior to version 6 it was only used in C++ mode). 10942 // GCC reserves 15 for strings, but actually uses 5 (pointer) for string 10943 // literals. 10944 }; 10945 10946 /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way 10947 /// as GCC. 10948 static GCCTypeClass 10949 EvaluateBuiltinClassifyType(QualType T, const LangOptions &LangOpts) { 10950 assert(!T->isDependentType() && "unexpected dependent type"); 10951 10952 QualType CanTy = T.getCanonicalType(); 10953 const BuiltinType *BT = dyn_cast<BuiltinType>(CanTy); 10954 10955 switch (CanTy->getTypeClass()) { 10956 #define TYPE(ID, BASE) 10957 #define DEPENDENT_TYPE(ID, BASE) case Type::ID: 10958 #define NON_CANONICAL_TYPE(ID, BASE) case Type::ID: 10959 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(ID, BASE) case Type::ID: 10960 #include "clang/AST/TypeNodes.inc" 10961 case Type::Auto: 10962 case Type::DeducedTemplateSpecialization: 10963 llvm_unreachable("unexpected non-canonical or dependent type"); 10964 10965 case Type::Builtin: 10966 switch (BT->getKind()) { 10967 #define BUILTIN_TYPE(ID, SINGLETON_ID) 10968 #define SIGNED_TYPE(ID, SINGLETON_ID) \ 10969 case BuiltinType::ID: return GCCTypeClass::Integer; 10970 #define FLOATING_TYPE(ID, SINGLETON_ID) \ 10971 case BuiltinType::ID: return GCCTypeClass::RealFloat; 10972 #define PLACEHOLDER_TYPE(ID, SINGLETON_ID) \ 10973 case BuiltinType::ID: break; 10974 #include "clang/AST/BuiltinTypes.def" 10975 case BuiltinType::Void: 10976 return GCCTypeClass::Void; 10977 10978 case BuiltinType::Bool: 10979 return GCCTypeClass::Bool; 10980 10981 case BuiltinType::Char_U: 10982 case BuiltinType::UChar: 10983 case BuiltinType::WChar_U: 10984 case BuiltinType::Char8: 10985 case BuiltinType::Char16: 10986 case BuiltinType::Char32: 10987 case BuiltinType::UShort: 10988 case BuiltinType::UInt: 10989 case BuiltinType::ULong: 10990 case BuiltinType::ULongLong: 10991 case BuiltinType::UInt128: 10992 return GCCTypeClass::Integer; 10993 10994 case BuiltinType::UShortAccum: 10995 case BuiltinType::UAccum: 10996 case BuiltinType::ULongAccum: 10997 case BuiltinType::UShortFract: 10998 case BuiltinType::UFract: 10999 case BuiltinType::ULongFract: 11000 case BuiltinType::SatUShortAccum: 11001 case BuiltinType::SatUAccum: 11002 case BuiltinType::SatULongAccum: 11003 case BuiltinType::SatUShortFract: 11004 case BuiltinType::SatUFract: 11005 case BuiltinType::SatULongFract: 11006 return GCCTypeClass::None; 11007 11008 case BuiltinType::NullPtr: 11009 11010 case BuiltinType::ObjCId: 11011 case BuiltinType::ObjCClass: 11012 case BuiltinType::ObjCSel: 11013 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \ 11014 case BuiltinType::Id: 11015 #include "clang/Basic/OpenCLImageTypes.def" 11016 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \ 11017 case BuiltinType::Id: 11018 #include "clang/Basic/OpenCLExtensionTypes.def" 11019 case BuiltinType::OCLSampler: 11020 case BuiltinType::OCLEvent: 11021 case BuiltinType::OCLClkEvent: 11022 case BuiltinType::OCLQueue: 11023 case BuiltinType::OCLReserveID: 11024 #define SVE_TYPE(Name, Id, SingletonId) \ 11025 case BuiltinType::Id: 11026 #include "clang/Basic/AArch64SVEACLETypes.def" 11027 #define PPC_VECTOR_TYPE(Name, Id, Size) \ 11028 case BuiltinType::Id: 11029 #include "clang/Basic/PPCTypes.def" 11030 #define RVV_TYPE(Name, Id, SingletonId) case BuiltinType::Id: 11031 #include "clang/Basic/RISCVVTypes.def" 11032 return GCCTypeClass::None; 11033 11034 case BuiltinType::Dependent: 11035 llvm_unreachable("unexpected dependent type"); 11036 }; 11037 llvm_unreachable("unexpected placeholder type"); 11038 11039 case Type::Enum: 11040 return LangOpts.CPlusPlus ? GCCTypeClass::Enum : GCCTypeClass::Integer; 11041 11042 case Type::Pointer: 11043 case Type::ConstantArray: 11044 case Type::VariableArray: 11045 case Type::IncompleteArray: 11046 case Type::FunctionNoProto: 11047 case Type::FunctionProto: 11048 return GCCTypeClass::Pointer; 11049 11050 case Type::MemberPointer: 11051 return CanTy->isMemberDataPointerType() 11052 ? GCCTypeClass::PointerToDataMember 11053 : GCCTypeClass::PointerToMemberFunction; 11054 11055 case Type::Complex: 11056 return GCCTypeClass::Complex; 11057 11058 case Type::Record: 11059 return CanTy->isUnionType() ? GCCTypeClass::Union 11060 : GCCTypeClass::ClassOrStruct; 11061 11062 case Type::Atomic: 11063 // GCC classifies _Atomic T the same as T. 11064 return EvaluateBuiltinClassifyType( 11065 CanTy->castAs<AtomicType>()->getValueType(), LangOpts); 11066 11067 case Type::BlockPointer: 11068 case Type::Vector: 11069 case Type::ExtVector: 11070 case Type::ConstantMatrix: 11071 case Type::ObjCObject: 11072 case Type::ObjCInterface: 11073 case Type::ObjCObjectPointer: 11074 case Type::Pipe: 11075 case Type::ExtInt: 11076 // GCC classifies vectors as None. We follow its lead and classify all 11077 // other types that don't fit into the regular classification the same way. 11078 return GCCTypeClass::None; 11079 11080 case Type::LValueReference: 11081 case Type::RValueReference: 11082 llvm_unreachable("invalid type for expression"); 11083 } 11084 11085 llvm_unreachable("unexpected type class"); 11086 } 11087 11088 /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way 11089 /// as GCC. 11090 static GCCTypeClass 11091 EvaluateBuiltinClassifyType(const CallExpr *E, const LangOptions &LangOpts) { 11092 // If no argument was supplied, default to None. This isn't 11093 // ideal, however it is what gcc does. 11094 if (E->getNumArgs() == 0) 11095 return GCCTypeClass::None; 11096 11097 // FIXME: Bizarrely, GCC treats a call with more than one argument as not 11098 // being an ICE, but still folds it to a constant using the type of the first 11099 // argument. 11100 return EvaluateBuiltinClassifyType(E->getArg(0)->getType(), LangOpts); 11101 } 11102 11103 /// EvaluateBuiltinConstantPForLValue - Determine the result of 11104 /// __builtin_constant_p when applied to the given pointer. 11105 /// 11106 /// A pointer is only "constant" if it is null (or a pointer cast to integer) 11107 /// or it points to the first character of a string literal. 11108 static bool EvaluateBuiltinConstantPForLValue(const APValue &LV) { 11109 APValue::LValueBase Base = LV.getLValueBase(); 11110 if (Base.isNull()) { 11111 // A null base is acceptable. 11112 return true; 11113 } else if (const Expr *E = Base.dyn_cast<const Expr *>()) { 11114 if (!isa<StringLiteral>(E)) 11115 return false; 11116 return LV.getLValueOffset().isZero(); 11117 } else if (Base.is<TypeInfoLValue>()) { 11118 // Surprisingly, GCC considers __builtin_constant_p(&typeid(int)) to 11119 // evaluate to true. 11120 return true; 11121 } else { 11122 // Any other base is not constant enough for GCC. 11123 return false; 11124 } 11125 } 11126 11127 /// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to 11128 /// GCC as we can manage. 11129 static bool EvaluateBuiltinConstantP(EvalInfo &Info, const Expr *Arg) { 11130 // This evaluation is not permitted to have side-effects, so evaluate it in 11131 // a speculative evaluation context. 11132 SpeculativeEvaluationRAII SpeculativeEval(Info); 11133 11134 // Constant-folding is always enabled for the operand of __builtin_constant_p 11135 // (even when the enclosing evaluation context otherwise requires a strict 11136 // language-specific constant expression). 11137 FoldConstant Fold(Info, true); 11138 11139 QualType ArgType = Arg->getType(); 11140 11141 // __builtin_constant_p always has one operand. The rules which gcc follows 11142 // are not precisely documented, but are as follows: 11143 // 11144 // - If the operand is of integral, floating, complex or enumeration type, 11145 // and can be folded to a known value of that type, it returns 1. 11146 // - If the operand can be folded to a pointer to the first character 11147 // of a string literal (or such a pointer cast to an integral type) 11148 // or to a null pointer or an integer cast to a pointer, it returns 1. 11149 // 11150 // Otherwise, it returns 0. 11151 // 11152 // FIXME: GCC also intends to return 1 for literals of aggregate types, but 11153 // its support for this did not work prior to GCC 9 and is not yet well 11154 // understood. 11155 if (ArgType->isIntegralOrEnumerationType() || ArgType->isFloatingType() || 11156 ArgType->isAnyComplexType() || ArgType->isPointerType() || 11157 ArgType->isNullPtrType()) { 11158 APValue V; 11159 if (!::EvaluateAsRValue(Info, Arg, V) || Info.EvalStatus.HasSideEffects) { 11160 Fold.keepDiagnostics(); 11161 return false; 11162 } 11163 11164 // For a pointer (possibly cast to integer), there are special rules. 11165 if (V.getKind() == APValue::LValue) 11166 return EvaluateBuiltinConstantPForLValue(V); 11167 11168 // Otherwise, any constant value is good enough. 11169 return V.hasValue(); 11170 } 11171 11172 // Anything else isn't considered to be sufficiently constant. 11173 return false; 11174 } 11175 11176 /// Retrieves the "underlying object type" of the given expression, 11177 /// as used by __builtin_object_size. 11178 static QualType getObjectType(APValue::LValueBase B) { 11179 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { 11180 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 11181 return VD->getType(); 11182 } else if (const Expr *E = B.dyn_cast<const Expr*>()) { 11183 if (isa<CompoundLiteralExpr>(E)) 11184 return E->getType(); 11185 } else if (B.is<TypeInfoLValue>()) { 11186 return B.getTypeInfoType(); 11187 } else if (B.is<DynamicAllocLValue>()) { 11188 return B.getDynamicAllocType(); 11189 } 11190 11191 return QualType(); 11192 } 11193 11194 /// A more selective version of E->IgnoreParenCasts for 11195 /// tryEvaluateBuiltinObjectSize. This ignores some casts/parens that serve only 11196 /// to change the type of E. 11197 /// Ex. For E = `(short*)((char*)(&foo))`, returns `&foo` 11198 /// 11199 /// Always returns an RValue with a pointer representation. 11200 static const Expr *ignorePointerCastsAndParens(const Expr *E) { 11201 assert(E->isPRValue() && E->getType()->hasPointerRepresentation()); 11202 11203 auto *NoParens = E->IgnoreParens(); 11204 auto *Cast = dyn_cast<CastExpr>(NoParens); 11205 if (Cast == nullptr) 11206 return NoParens; 11207 11208 // We only conservatively allow a few kinds of casts, because this code is 11209 // inherently a simple solution that seeks to support the common case. 11210 auto CastKind = Cast->getCastKind(); 11211 if (CastKind != CK_NoOp && CastKind != CK_BitCast && 11212 CastKind != CK_AddressSpaceConversion) 11213 return NoParens; 11214 11215 auto *SubExpr = Cast->getSubExpr(); 11216 if (!SubExpr->getType()->hasPointerRepresentation() || !SubExpr->isPRValue()) 11217 return NoParens; 11218 return ignorePointerCastsAndParens(SubExpr); 11219 } 11220 11221 /// Checks to see if the given LValue's Designator is at the end of the LValue's 11222 /// record layout. e.g. 11223 /// struct { struct { int a, b; } fst, snd; } obj; 11224 /// obj.fst // no 11225 /// obj.snd // yes 11226 /// obj.fst.a // no 11227 /// obj.fst.b // no 11228 /// obj.snd.a // no 11229 /// obj.snd.b // yes 11230 /// 11231 /// Please note: this function is specialized for how __builtin_object_size 11232 /// views "objects". 11233 /// 11234 /// If this encounters an invalid RecordDecl or otherwise cannot determine the 11235 /// correct result, it will always return true. 11236 static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) { 11237 assert(!LVal.Designator.Invalid); 11238 11239 auto IsLastOrInvalidFieldDecl = [&Ctx](const FieldDecl *FD, bool &Invalid) { 11240 const RecordDecl *Parent = FD->getParent(); 11241 Invalid = Parent->isInvalidDecl(); 11242 if (Invalid || Parent->isUnion()) 11243 return true; 11244 const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(Parent); 11245 return FD->getFieldIndex() + 1 == Layout.getFieldCount(); 11246 }; 11247 11248 auto &Base = LVal.getLValueBase(); 11249 if (auto *ME = dyn_cast_or_null<MemberExpr>(Base.dyn_cast<const Expr *>())) { 11250 if (auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl())) { 11251 bool Invalid; 11252 if (!IsLastOrInvalidFieldDecl(FD, Invalid)) 11253 return Invalid; 11254 } else if (auto *IFD = dyn_cast<IndirectFieldDecl>(ME->getMemberDecl())) { 11255 for (auto *FD : IFD->chain()) { 11256 bool Invalid; 11257 if (!IsLastOrInvalidFieldDecl(cast<FieldDecl>(FD), Invalid)) 11258 return Invalid; 11259 } 11260 } 11261 } 11262 11263 unsigned I = 0; 11264 QualType BaseType = getType(Base); 11265 if (LVal.Designator.FirstEntryIsAnUnsizedArray) { 11266 // If we don't know the array bound, conservatively assume we're looking at 11267 // the final array element. 11268 ++I; 11269 if (BaseType->isIncompleteArrayType()) 11270 BaseType = Ctx.getAsArrayType(BaseType)->getElementType(); 11271 else 11272 BaseType = BaseType->castAs<PointerType>()->getPointeeType(); 11273 } 11274 11275 for (unsigned E = LVal.Designator.Entries.size(); I != E; ++I) { 11276 const auto &Entry = LVal.Designator.Entries[I]; 11277 if (BaseType->isArrayType()) { 11278 // Because __builtin_object_size treats arrays as objects, we can ignore 11279 // the index iff this is the last array in the Designator. 11280 if (I + 1 == E) 11281 return true; 11282 const auto *CAT = cast<ConstantArrayType>(Ctx.getAsArrayType(BaseType)); 11283 uint64_t Index = Entry.getAsArrayIndex(); 11284 if (Index + 1 != CAT->getSize()) 11285 return false; 11286 BaseType = CAT->getElementType(); 11287 } else if (BaseType->isAnyComplexType()) { 11288 const auto *CT = BaseType->castAs<ComplexType>(); 11289 uint64_t Index = Entry.getAsArrayIndex(); 11290 if (Index != 1) 11291 return false; 11292 BaseType = CT->getElementType(); 11293 } else if (auto *FD = getAsField(Entry)) { 11294 bool Invalid; 11295 if (!IsLastOrInvalidFieldDecl(FD, Invalid)) 11296 return Invalid; 11297 BaseType = FD->getType(); 11298 } else { 11299 assert(getAsBaseClass(Entry) && "Expecting cast to a base class"); 11300 return false; 11301 } 11302 } 11303 return true; 11304 } 11305 11306 /// Tests to see if the LValue has a user-specified designator (that isn't 11307 /// necessarily valid). Note that this always returns 'true' if the LValue has 11308 /// an unsized array as its first designator entry, because there's currently no 11309 /// way to tell if the user typed *foo or foo[0]. 11310 static bool refersToCompleteObject(const LValue &LVal) { 11311 if (LVal.Designator.Invalid) 11312 return false; 11313 11314 if (!LVal.Designator.Entries.empty()) 11315 return LVal.Designator.isMostDerivedAnUnsizedArray(); 11316 11317 if (!LVal.InvalidBase) 11318 return true; 11319 11320 // If `E` is a MemberExpr, then the first part of the designator is hiding in 11321 // the LValueBase. 11322 const auto *E = LVal.Base.dyn_cast<const Expr *>(); 11323 return !E || !isa<MemberExpr>(E); 11324 } 11325 11326 /// Attempts to detect a user writing into a piece of memory that's impossible 11327 /// to figure out the size of by just using types. 11328 static bool isUserWritingOffTheEnd(const ASTContext &Ctx, const LValue &LVal) { 11329 const SubobjectDesignator &Designator = LVal.Designator; 11330 // Notes: 11331 // - Users can only write off of the end when we have an invalid base. Invalid 11332 // bases imply we don't know where the memory came from. 11333 // - We used to be a bit more aggressive here; we'd only be conservative if 11334 // the array at the end was flexible, or if it had 0 or 1 elements. This 11335 // broke some common standard library extensions (PR30346), but was 11336 // otherwise seemingly fine. It may be useful to reintroduce this behavior 11337 // with some sort of list. OTOH, it seems that GCC is always 11338 // conservative with the last element in structs (if it's an array), so our 11339 // current behavior is more compatible than an explicit list approach would 11340 // be. 11341 return LVal.InvalidBase && 11342 Designator.Entries.size() == Designator.MostDerivedPathLength && 11343 Designator.MostDerivedIsArrayElement && 11344 isDesignatorAtObjectEnd(Ctx, LVal); 11345 } 11346 11347 /// Converts the given APInt to CharUnits, assuming the APInt is unsigned. 11348 /// Fails if the conversion would cause loss of precision. 11349 static bool convertUnsignedAPIntToCharUnits(const llvm::APInt &Int, 11350 CharUnits &Result) { 11351 auto CharUnitsMax = std::numeric_limits<CharUnits::QuantityType>::max(); 11352 if (Int.ugt(CharUnitsMax)) 11353 return false; 11354 Result = CharUnits::fromQuantity(Int.getZExtValue()); 11355 return true; 11356 } 11357 11358 /// Helper for tryEvaluateBuiltinObjectSize -- Given an LValue, this will 11359 /// determine how many bytes exist from the beginning of the object to either 11360 /// the end of the current subobject, or the end of the object itself, depending 11361 /// on what the LValue looks like + the value of Type. 11362 /// 11363 /// If this returns false, the value of Result is undefined. 11364 static bool determineEndOffset(EvalInfo &Info, SourceLocation ExprLoc, 11365 unsigned Type, const LValue &LVal, 11366 CharUnits &EndOffset) { 11367 bool DetermineForCompleteObject = refersToCompleteObject(LVal); 11368 11369 auto CheckedHandleSizeof = [&](QualType Ty, CharUnits &Result) { 11370 if (Ty.isNull() || Ty->isIncompleteType() || Ty->isFunctionType()) 11371 return false; 11372 return HandleSizeof(Info, ExprLoc, Ty, Result); 11373 }; 11374 11375 // We want to evaluate the size of the entire object. This is a valid fallback 11376 // for when Type=1 and the designator is invalid, because we're asked for an 11377 // upper-bound. 11378 if (!(Type & 1) || LVal.Designator.Invalid || DetermineForCompleteObject) { 11379 // Type=3 wants a lower bound, so we can't fall back to this. 11380 if (Type == 3 && !DetermineForCompleteObject) 11381 return false; 11382 11383 llvm::APInt APEndOffset; 11384 if (isBaseAnAllocSizeCall(LVal.getLValueBase()) && 11385 getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset)) 11386 return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset); 11387 11388 if (LVal.InvalidBase) 11389 return false; 11390 11391 QualType BaseTy = getObjectType(LVal.getLValueBase()); 11392 return CheckedHandleSizeof(BaseTy, EndOffset); 11393 } 11394 11395 // We want to evaluate the size of a subobject. 11396 const SubobjectDesignator &Designator = LVal.Designator; 11397 11398 // The following is a moderately common idiom in C: 11399 // 11400 // struct Foo { int a; char c[1]; }; 11401 // struct Foo *F = (struct Foo *)malloc(sizeof(struct Foo) + strlen(Bar)); 11402 // strcpy(&F->c[0], Bar); 11403 // 11404 // In order to not break too much legacy code, we need to support it. 11405 if (isUserWritingOffTheEnd(Info.Ctx, LVal)) { 11406 // If we can resolve this to an alloc_size call, we can hand that back, 11407 // because we know for certain how many bytes there are to write to. 11408 llvm::APInt APEndOffset; 11409 if (isBaseAnAllocSizeCall(LVal.getLValueBase()) && 11410 getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset)) 11411 return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset); 11412 11413 // If we cannot determine the size of the initial allocation, then we can't 11414 // given an accurate upper-bound. However, we are still able to give 11415 // conservative lower-bounds for Type=3. 11416 if (Type == 1) 11417 return false; 11418 } 11419 11420 CharUnits BytesPerElem; 11421 if (!CheckedHandleSizeof(Designator.MostDerivedType, BytesPerElem)) 11422 return false; 11423 11424 // According to the GCC documentation, we want the size of the subobject 11425 // denoted by the pointer. But that's not quite right -- what we actually 11426 // want is the size of the immediately-enclosing array, if there is one. 11427 int64_t ElemsRemaining; 11428 if (Designator.MostDerivedIsArrayElement && 11429 Designator.Entries.size() == Designator.MostDerivedPathLength) { 11430 uint64_t ArraySize = Designator.getMostDerivedArraySize(); 11431 uint64_t ArrayIndex = Designator.Entries.back().getAsArrayIndex(); 11432 ElemsRemaining = ArraySize <= ArrayIndex ? 0 : ArraySize - ArrayIndex; 11433 } else { 11434 ElemsRemaining = Designator.isOnePastTheEnd() ? 0 : 1; 11435 } 11436 11437 EndOffset = LVal.getLValueOffset() + BytesPerElem * ElemsRemaining; 11438 return true; 11439 } 11440 11441 /// Tries to evaluate the __builtin_object_size for @p E. If successful, 11442 /// returns true and stores the result in @p Size. 11443 /// 11444 /// If @p WasError is non-null, this will report whether the failure to evaluate 11445 /// is to be treated as an Error in IntExprEvaluator. 11446 static bool tryEvaluateBuiltinObjectSize(const Expr *E, unsigned Type, 11447 EvalInfo &Info, uint64_t &Size) { 11448 // Determine the denoted object. 11449 LValue LVal; 11450 { 11451 // The operand of __builtin_object_size is never evaluated for side-effects. 11452 // If there are any, but we can determine the pointed-to object anyway, then 11453 // ignore the side-effects. 11454 SpeculativeEvaluationRAII SpeculativeEval(Info); 11455 IgnoreSideEffectsRAII Fold(Info); 11456 11457 if (E->isGLValue()) { 11458 // It's possible for us to be given GLValues if we're called via 11459 // Expr::tryEvaluateObjectSize. 11460 APValue RVal; 11461 if (!EvaluateAsRValue(Info, E, RVal)) 11462 return false; 11463 LVal.setFrom(Info.Ctx, RVal); 11464 } else if (!EvaluatePointer(ignorePointerCastsAndParens(E), LVal, Info, 11465 /*InvalidBaseOK=*/true)) 11466 return false; 11467 } 11468 11469 // If we point to before the start of the object, there are no accessible 11470 // bytes. 11471 if (LVal.getLValueOffset().isNegative()) { 11472 Size = 0; 11473 return true; 11474 } 11475 11476 CharUnits EndOffset; 11477 if (!determineEndOffset(Info, E->getExprLoc(), Type, LVal, EndOffset)) 11478 return false; 11479 11480 // If we've fallen outside of the end offset, just pretend there's nothing to 11481 // write to/read from. 11482 if (EndOffset <= LVal.getLValueOffset()) 11483 Size = 0; 11484 else 11485 Size = (EndOffset - LVal.getLValueOffset()).getQuantity(); 11486 return true; 11487 } 11488 11489 bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) { 11490 if (unsigned BuiltinOp = E->getBuiltinCallee()) 11491 return VisitBuiltinCallExpr(E, BuiltinOp); 11492 11493 return ExprEvaluatorBaseTy::VisitCallExpr(E); 11494 } 11495 11496 static bool getBuiltinAlignArguments(const CallExpr *E, EvalInfo &Info, 11497 APValue &Val, APSInt &Alignment) { 11498 QualType SrcTy = E->getArg(0)->getType(); 11499 if (!getAlignmentArgument(E->getArg(1), SrcTy, Info, Alignment)) 11500 return false; 11501 // Even though we are evaluating integer expressions we could get a pointer 11502 // argument for the __builtin_is_aligned() case. 11503 if (SrcTy->isPointerType()) { 11504 LValue Ptr; 11505 if (!EvaluatePointer(E->getArg(0), Ptr, Info)) 11506 return false; 11507 Ptr.moveInto(Val); 11508 } else if (!SrcTy->isIntegralOrEnumerationType()) { 11509 Info.FFDiag(E->getArg(0)); 11510 return false; 11511 } else { 11512 APSInt SrcInt; 11513 if (!EvaluateInteger(E->getArg(0), SrcInt, Info)) 11514 return false; 11515 assert(SrcInt.getBitWidth() >= Alignment.getBitWidth() && 11516 "Bit widths must be the same"); 11517 Val = APValue(SrcInt); 11518 } 11519 assert(Val.hasValue()); 11520 return true; 11521 } 11522 11523 bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E, 11524 unsigned BuiltinOp) { 11525 switch (BuiltinOp) { 11526 default: 11527 return ExprEvaluatorBaseTy::VisitCallExpr(E); 11528 11529 case Builtin::BI__builtin_dynamic_object_size: 11530 case Builtin::BI__builtin_object_size: { 11531 // The type was checked when we built the expression. 11532 unsigned Type = 11533 E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue(); 11534 assert(Type <= 3 && "unexpected type"); 11535 11536 uint64_t Size; 11537 if (tryEvaluateBuiltinObjectSize(E->getArg(0), Type, Info, Size)) 11538 return Success(Size, E); 11539 11540 if (E->getArg(0)->HasSideEffects(Info.Ctx)) 11541 return Success((Type & 2) ? 0 : -1, E); 11542 11543 // Expression had no side effects, but we couldn't statically determine the 11544 // size of the referenced object. 11545 switch (Info.EvalMode) { 11546 case EvalInfo::EM_ConstantExpression: 11547 case EvalInfo::EM_ConstantFold: 11548 case EvalInfo::EM_IgnoreSideEffects: 11549 // Leave it to IR generation. 11550 return Error(E); 11551 case EvalInfo::EM_ConstantExpressionUnevaluated: 11552 // Reduce it to a constant now. 11553 return Success((Type & 2) ? 0 : -1, E); 11554 } 11555 11556 llvm_unreachable("unexpected EvalMode"); 11557 } 11558 11559 case Builtin::BI__builtin_os_log_format_buffer_size: { 11560 analyze_os_log::OSLogBufferLayout Layout; 11561 analyze_os_log::computeOSLogBufferLayout(Info.Ctx, E, Layout); 11562 return Success(Layout.size().getQuantity(), E); 11563 } 11564 11565 case Builtin::BI__builtin_is_aligned: { 11566 APValue Src; 11567 APSInt Alignment; 11568 if (!getBuiltinAlignArguments(E, Info, Src, Alignment)) 11569 return false; 11570 if (Src.isLValue()) { 11571 // If we evaluated a pointer, check the minimum known alignment. 11572 LValue Ptr; 11573 Ptr.setFrom(Info.Ctx, Src); 11574 CharUnits BaseAlignment = getBaseAlignment(Info, Ptr); 11575 CharUnits PtrAlign = BaseAlignment.alignmentAtOffset(Ptr.Offset); 11576 // We can return true if the known alignment at the computed offset is 11577 // greater than the requested alignment. 11578 assert(PtrAlign.isPowerOfTwo()); 11579 assert(Alignment.isPowerOf2()); 11580 if (PtrAlign.getQuantity() >= Alignment) 11581 return Success(1, E); 11582 // If the alignment is not known to be sufficient, some cases could still 11583 // be aligned at run time. However, if the requested alignment is less or 11584 // equal to the base alignment and the offset is not aligned, we know that 11585 // the run-time value can never be aligned. 11586 if (BaseAlignment.getQuantity() >= Alignment && 11587 PtrAlign.getQuantity() < Alignment) 11588 return Success(0, E); 11589 // Otherwise we can't infer whether the value is sufficiently aligned. 11590 // TODO: __builtin_is_aligned(__builtin_align_{down,up{(expr, N), N) 11591 // in cases where we can't fully evaluate the pointer. 11592 Info.FFDiag(E->getArg(0), diag::note_constexpr_alignment_compute) 11593 << Alignment; 11594 return false; 11595 } 11596 assert(Src.isInt()); 11597 return Success((Src.getInt() & (Alignment - 1)) == 0 ? 1 : 0, E); 11598 } 11599 case Builtin::BI__builtin_align_up: { 11600 APValue Src; 11601 APSInt Alignment; 11602 if (!getBuiltinAlignArguments(E, Info, Src, Alignment)) 11603 return false; 11604 if (!Src.isInt()) 11605 return Error(E); 11606 APSInt AlignedVal = 11607 APSInt((Src.getInt() + (Alignment - 1)) & ~(Alignment - 1), 11608 Src.getInt().isUnsigned()); 11609 assert(AlignedVal.getBitWidth() == Src.getInt().getBitWidth()); 11610 return Success(AlignedVal, E); 11611 } 11612 case Builtin::BI__builtin_align_down: { 11613 APValue Src; 11614 APSInt Alignment; 11615 if (!getBuiltinAlignArguments(E, Info, Src, Alignment)) 11616 return false; 11617 if (!Src.isInt()) 11618 return Error(E); 11619 APSInt AlignedVal = 11620 APSInt(Src.getInt() & ~(Alignment - 1), Src.getInt().isUnsigned()); 11621 assert(AlignedVal.getBitWidth() == Src.getInt().getBitWidth()); 11622 return Success(AlignedVal, E); 11623 } 11624 11625 case Builtin::BI__builtin_bitreverse8: 11626 case Builtin::BI__builtin_bitreverse16: 11627 case Builtin::BI__builtin_bitreverse32: 11628 case Builtin::BI__builtin_bitreverse64: { 11629 APSInt Val; 11630 if (!EvaluateInteger(E->getArg(0), Val, Info)) 11631 return false; 11632 11633 return Success(Val.reverseBits(), E); 11634 } 11635 11636 case Builtin::BI__builtin_bswap16: 11637 case Builtin::BI__builtin_bswap32: 11638 case Builtin::BI__builtin_bswap64: { 11639 APSInt Val; 11640 if (!EvaluateInteger(E->getArg(0), Val, Info)) 11641 return false; 11642 11643 return Success(Val.byteSwap(), E); 11644 } 11645 11646 case Builtin::BI__builtin_classify_type: 11647 return Success((int)EvaluateBuiltinClassifyType(E, Info.getLangOpts()), E); 11648 11649 case Builtin::BI__builtin_clrsb: 11650 case Builtin::BI__builtin_clrsbl: 11651 case Builtin::BI__builtin_clrsbll: { 11652 APSInt Val; 11653 if (!EvaluateInteger(E->getArg(0), Val, Info)) 11654 return false; 11655 11656 return Success(Val.getBitWidth() - Val.getMinSignedBits(), E); 11657 } 11658 11659 case Builtin::BI__builtin_clz: 11660 case Builtin::BI__builtin_clzl: 11661 case Builtin::BI__builtin_clzll: 11662 case Builtin::BI__builtin_clzs: { 11663 APSInt Val; 11664 if (!EvaluateInteger(E->getArg(0), Val, Info)) 11665 return false; 11666 if (!Val) 11667 return Error(E); 11668 11669 return Success(Val.countLeadingZeros(), E); 11670 } 11671 11672 case Builtin::BI__builtin_constant_p: { 11673 const Expr *Arg = E->getArg(0); 11674 if (EvaluateBuiltinConstantP(Info, Arg)) 11675 return Success(true, E); 11676 if (Info.InConstantContext || Arg->HasSideEffects(Info.Ctx)) { 11677 // Outside a constant context, eagerly evaluate to false in the presence 11678 // of side-effects in order to avoid -Wunsequenced false-positives in 11679 // a branch on __builtin_constant_p(expr). 11680 return Success(false, E); 11681 } 11682 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 11683 return false; 11684 } 11685 11686 case Builtin::BI__builtin_is_constant_evaluated: { 11687 const auto *Callee = Info.CurrentCall->getCallee(); 11688 if (Info.InConstantContext && !Info.CheckingPotentialConstantExpression && 11689 (Info.CallStackDepth == 1 || 11690 (Info.CallStackDepth == 2 && Callee->isInStdNamespace() && 11691 Callee->getIdentifier() && 11692 Callee->getIdentifier()->isStr("is_constant_evaluated")))) { 11693 // FIXME: Find a better way to avoid duplicated diagnostics. 11694 if (Info.EvalStatus.Diag) 11695 Info.report((Info.CallStackDepth == 1) ? E->getExprLoc() 11696 : Info.CurrentCall->CallLoc, 11697 diag::warn_is_constant_evaluated_always_true_constexpr) 11698 << (Info.CallStackDepth == 1 ? "__builtin_is_constant_evaluated" 11699 : "std::is_constant_evaluated"); 11700 } 11701 11702 return Success(Info.InConstantContext, E); 11703 } 11704 11705 case Builtin::BI__builtin_ctz: 11706 case Builtin::BI__builtin_ctzl: 11707 case Builtin::BI__builtin_ctzll: 11708 case Builtin::BI__builtin_ctzs: { 11709 APSInt Val; 11710 if (!EvaluateInteger(E->getArg(0), Val, Info)) 11711 return false; 11712 if (!Val) 11713 return Error(E); 11714 11715 return Success(Val.countTrailingZeros(), E); 11716 } 11717 11718 case Builtin::BI__builtin_eh_return_data_regno: { 11719 int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue(); 11720 Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand); 11721 return Success(Operand, E); 11722 } 11723 11724 case Builtin::BI__builtin_expect: 11725 case Builtin::BI__builtin_expect_with_probability: 11726 return Visit(E->getArg(0)); 11727 11728 case Builtin::BI__builtin_ffs: 11729 case Builtin::BI__builtin_ffsl: 11730 case Builtin::BI__builtin_ffsll: { 11731 APSInt Val; 11732 if (!EvaluateInteger(E->getArg(0), Val, Info)) 11733 return false; 11734 11735 unsigned N = Val.countTrailingZeros(); 11736 return Success(N == Val.getBitWidth() ? 0 : N + 1, E); 11737 } 11738 11739 case Builtin::BI__builtin_fpclassify: { 11740 APFloat Val(0.0); 11741 if (!EvaluateFloat(E->getArg(5), Val, Info)) 11742 return false; 11743 unsigned Arg; 11744 switch (Val.getCategory()) { 11745 case APFloat::fcNaN: Arg = 0; break; 11746 case APFloat::fcInfinity: Arg = 1; break; 11747 case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break; 11748 case APFloat::fcZero: Arg = 4; break; 11749 } 11750 return Visit(E->getArg(Arg)); 11751 } 11752 11753 case Builtin::BI__builtin_isinf_sign: { 11754 APFloat Val(0.0); 11755 return EvaluateFloat(E->getArg(0), Val, Info) && 11756 Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E); 11757 } 11758 11759 case Builtin::BI__builtin_isinf: { 11760 APFloat Val(0.0); 11761 return EvaluateFloat(E->getArg(0), Val, Info) && 11762 Success(Val.isInfinity() ? 1 : 0, E); 11763 } 11764 11765 case Builtin::BI__builtin_isfinite: { 11766 APFloat Val(0.0); 11767 return EvaluateFloat(E->getArg(0), Val, Info) && 11768 Success(Val.isFinite() ? 1 : 0, E); 11769 } 11770 11771 case Builtin::BI__builtin_isnan: { 11772 APFloat Val(0.0); 11773 return EvaluateFloat(E->getArg(0), Val, Info) && 11774 Success(Val.isNaN() ? 1 : 0, E); 11775 } 11776 11777 case Builtin::BI__builtin_isnormal: { 11778 APFloat Val(0.0); 11779 return EvaluateFloat(E->getArg(0), Val, Info) && 11780 Success(Val.isNormal() ? 1 : 0, E); 11781 } 11782 11783 case Builtin::BI__builtin_parity: 11784 case Builtin::BI__builtin_parityl: 11785 case Builtin::BI__builtin_parityll: { 11786 APSInt Val; 11787 if (!EvaluateInteger(E->getArg(0), Val, Info)) 11788 return false; 11789 11790 return Success(Val.countPopulation() % 2, E); 11791 } 11792 11793 case Builtin::BI__builtin_popcount: 11794 case Builtin::BI__builtin_popcountl: 11795 case Builtin::BI__builtin_popcountll: { 11796 APSInt Val; 11797 if (!EvaluateInteger(E->getArg(0), Val, Info)) 11798 return false; 11799 11800 return Success(Val.countPopulation(), E); 11801 } 11802 11803 case Builtin::BI__builtin_rotateleft8: 11804 case Builtin::BI__builtin_rotateleft16: 11805 case Builtin::BI__builtin_rotateleft32: 11806 case Builtin::BI__builtin_rotateleft64: 11807 case Builtin::BI_rotl8: // Microsoft variants of rotate right 11808 case Builtin::BI_rotl16: 11809 case Builtin::BI_rotl: 11810 case Builtin::BI_lrotl: 11811 case Builtin::BI_rotl64: { 11812 APSInt Val, Amt; 11813 if (!EvaluateInteger(E->getArg(0), Val, Info) || 11814 !EvaluateInteger(E->getArg(1), Amt, Info)) 11815 return false; 11816 11817 return Success(Val.rotl(Amt.urem(Val.getBitWidth())), E); 11818 } 11819 11820 case Builtin::BI__builtin_rotateright8: 11821 case Builtin::BI__builtin_rotateright16: 11822 case Builtin::BI__builtin_rotateright32: 11823 case Builtin::BI__builtin_rotateright64: 11824 case Builtin::BI_rotr8: // Microsoft variants of rotate right 11825 case Builtin::BI_rotr16: 11826 case Builtin::BI_rotr: 11827 case Builtin::BI_lrotr: 11828 case Builtin::BI_rotr64: { 11829 APSInt Val, Amt; 11830 if (!EvaluateInteger(E->getArg(0), Val, Info) || 11831 !EvaluateInteger(E->getArg(1), Amt, Info)) 11832 return false; 11833 11834 return Success(Val.rotr(Amt.urem(Val.getBitWidth())), E); 11835 } 11836 11837 case Builtin::BIstrlen: 11838 case Builtin::BIwcslen: 11839 // A call to strlen is not a constant expression. 11840 if (Info.getLangOpts().CPlusPlus11) 11841 Info.CCEDiag(E, diag::note_constexpr_invalid_function) 11842 << /*isConstexpr*/0 << /*isConstructor*/0 11843 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'"); 11844 else 11845 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); 11846 LLVM_FALLTHROUGH; 11847 case Builtin::BI__builtin_strlen: 11848 case Builtin::BI__builtin_wcslen: { 11849 // As an extension, we support __builtin_strlen() as a constant expression, 11850 // and support folding strlen() to a constant. 11851 LValue String; 11852 if (!EvaluatePointer(E->getArg(0), String, Info)) 11853 return false; 11854 11855 QualType CharTy = E->getArg(0)->getType()->getPointeeType(); 11856 11857 // Fast path: if it's a string literal, search the string value. 11858 if (const StringLiteral *S = dyn_cast_or_null<StringLiteral>( 11859 String.getLValueBase().dyn_cast<const Expr *>())) { 11860 // The string literal may have embedded null characters. Find the first 11861 // one and truncate there. 11862 StringRef Str = S->getBytes(); 11863 int64_t Off = String.Offset.getQuantity(); 11864 if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() && 11865 S->getCharByteWidth() == 1 && 11866 // FIXME: Add fast-path for wchar_t too. 11867 Info.Ctx.hasSameUnqualifiedType(CharTy, Info.Ctx.CharTy)) { 11868 Str = Str.substr(Off); 11869 11870 StringRef::size_type Pos = Str.find(0); 11871 if (Pos != StringRef::npos) 11872 Str = Str.substr(0, Pos); 11873 11874 return Success(Str.size(), E); 11875 } 11876 11877 // Fall through to slow path to issue appropriate diagnostic. 11878 } 11879 11880 // Slow path: scan the bytes of the string looking for the terminating 0. 11881 for (uint64_t Strlen = 0; /**/; ++Strlen) { 11882 APValue Char; 11883 if (!handleLValueToRValueConversion(Info, E, CharTy, String, Char) || 11884 !Char.isInt()) 11885 return false; 11886 if (!Char.getInt()) 11887 return Success(Strlen, E); 11888 if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1)) 11889 return false; 11890 } 11891 } 11892 11893 case Builtin::BIstrcmp: 11894 case Builtin::BIwcscmp: 11895 case Builtin::BIstrncmp: 11896 case Builtin::BIwcsncmp: 11897 case Builtin::BImemcmp: 11898 case Builtin::BIbcmp: 11899 case Builtin::BIwmemcmp: 11900 // A call to strlen is not a constant expression. 11901 if (Info.getLangOpts().CPlusPlus11) 11902 Info.CCEDiag(E, diag::note_constexpr_invalid_function) 11903 << /*isConstexpr*/0 << /*isConstructor*/0 11904 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'"); 11905 else 11906 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); 11907 LLVM_FALLTHROUGH; 11908 case Builtin::BI__builtin_strcmp: 11909 case Builtin::BI__builtin_wcscmp: 11910 case Builtin::BI__builtin_strncmp: 11911 case Builtin::BI__builtin_wcsncmp: 11912 case Builtin::BI__builtin_memcmp: 11913 case Builtin::BI__builtin_bcmp: 11914 case Builtin::BI__builtin_wmemcmp: { 11915 LValue String1, String2; 11916 if (!EvaluatePointer(E->getArg(0), String1, Info) || 11917 !EvaluatePointer(E->getArg(1), String2, Info)) 11918 return false; 11919 11920 uint64_t MaxLength = uint64_t(-1); 11921 if (BuiltinOp != Builtin::BIstrcmp && 11922 BuiltinOp != Builtin::BIwcscmp && 11923 BuiltinOp != Builtin::BI__builtin_strcmp && 11924 BuiltinOp != Builtin::BI__builtin_wcscmp) { 11925 APSInt N; 11926 if (!EvaluateInteger(E->getArg(2), N, Info)) 11927 return false; 11928 MaxLength = N.getExtValue(); 11929 } 11930 11931 // Empty substrings compare equal by definition. 11932 if (MaxLength == 0u) 11933 return Success(0, E); 11934 11935 if (!String1.checkNullPointerForFoldAccess(Info, E, AK_Read) || 11936 !String2.checkNullPointerForFoldAccess(Info, E, AK_Read) || 11937 String1.Designator.Invalid || String2.Designator.Invalid) 11938 return false; 11939 11940 QualType CharTy1 = String1.Designator.getType(Info.Ctx); 11941 QualType CharTy2 = String2.Designator.getType(Info.Ctx); 11942 11943 bool IsRawByte = BuiltinOp == Builtin::BImemcmp || 11944 BuiltinOp == Builtin::BIbcmp || 11945 BuiltinOp == Builtin::BI__builtin_memcmp || 11946 BuiltinOp == Builtin::BI__builtin_bcmp; 11947 11948 assert(IsRawByte || 11949 (Info.Ctx.hasSameUnqualifiedType( 11950 CharTy1, E->getArg(0)->getType()->getPointeeType()) && 11951 Info.Ctx.hasSameUnqualifiedType(CharTy1, CharTy2))); 11952 11953 // For memcmp, allow comparing any arrays of '[[un]signed] char' or 11954 // 'char8_t', but no other types. 11955 if (IsRawByte && 11956 !(isOneByteCharacterType(CharTy1) && isOneByteCharacterType(CharTy2))) { 11957 // FIXME: Consider using our bit_cast implementation to support this. 11958 Info.FFDiag(E, diag::note_constexpr_memcmp_unsupported) 11959 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'") 11960 << CharTy1 << CharTy2; 11961 return false; 11962 } 11963 11964 const auto &ReadCurElems = [&](APValue &Char1, APValue &Char2) { 11965 return handleLValueToRValueConversion(Info, E, CharTy1, String1, Char1) && 11966 handleLValueToRValueConversion(Info, E, CharTy2, String2, Char2) && 11967 Char1.isInt() && Char2.isInt(); 11968 }; 11969 const auto &AdvanceElems = [&] { 11970 return HandleLValueArrayAdjustment(Info, E, String1, CharTy1, 1) && 11971 HandleLValueArrayAdjustment(Info, E, String2, CharTy2, 1); 11972 }; 11973 11974 bool StopAtNull = 11975 (BuiltinOp != Builtin::BImemcmp && BuiltinOp != Builtin::BIbcmp && 11976 BuiltinOp != Builtin::BIwmemcmp && 11977 BuiltinOp != Builtin::BI__builtin_memcmp && 11978 BuiltinOp != Builtin::BI__builtin_bcmp && 11979 BuiltinOp != Builtin::BI__builtin_wmemcmp); 11980 bool IsWide = BuiltinOp == Builtin::BIwcscmp || 11981 BuiltinOp == Builtin::BIwcsncmp || 11982 BuiltinOp == Builtin::BIwmemcmp || 11983 BuiltinOp == Builtin::BI__builtin_wcscmp || 11984 BuiltinOp == Builtin::BI__builtin_wcsncmp || 11985 BuiltinOp == Builtin::BI__builtin_wmemcmp; 11986 11987 for (; MaxLength; --MaxLength) { 11988 APValue Char1, Char2; 11989 if (!ReadCurElems(Char1, Char2)) 11990 return false; 11991 if (Char1.getInt().ne(Char2.getInt())) { 11992 if (IsWide) // wmemcmp compares with wchar_t signedness. 11993 return Success(Char1.getInt() < Char2.getInt() ? -1 : 1, E); 11994 // memcmp always compares unsigned chars. 11995 return Success(Char1.getInt().ult(Char2.getInt()) ? -1 : 1, E); 11996 } 11997 if (StopAtNull && !Char1.getInt()) 11998 return Success(0, E); 11999 assert(!(StopAtNull && !Char2.getInt())); 12000 if (!AdvanceElems()) 12001 return false; 12002 } 12003 // We hit the strncmp / memcmp limit. 12004 return Success(0, E); 12005 } 12006 12007 case Builtin::BI__atomic_always_lock_free: 12008 case Builtin::BI__atomic_is_lock_free: 12009 case Builtin::BI__c11_atomic_is_lock_free: { 12010 APSInt SizeVal; 12011 if (!EvaluateInteger(E->getArg(0), SizeVal, Info)) 12012 return false; 12013 12014 // For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power 12015 // of two less than or equal to the maximum inline atomic width, we know it 12016 // is lock-free. If the size isn't a power of two, or greater than the 12017 // maximum alignment where we promote atomics, we know it is not lock-free 12018 // (at least not in the sense of atomic_is_lock_free). Otherwise, 12019 // the answer can only be determined at runtime; for example, 16-byte 12020 // atomics have lock-free implementations on some, but not all, 12021 // x86-64 processors. 12022 12023 // Check power-of-two. 12024 CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue()); 12025 if (Size.isPowerOfTwo()) { 12026 // Check against inlining width. 12027 unsigned InlineWidthBits = 12028 Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth(); 12029 if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) { 12030 if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free || 12031 Size == CharUnits::One() || 12032 E->getArg(1)->isNullPointerConstant(Info.Ctx, 12033 Expr::NPC_NeverValueDependent)) 12034 // OK, we will inline appropriately-aligned operations of this size, 12035 // and _Atomic(T) is appropriately-aligned. 12036 return Success(1, E); 12037 12038 QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()-> 12039 castAs<PointerType>()->getPointeeType(); 12040 if (!PointeeType->isIncompleteType() && 12041 Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) { 12042 // OK, we will inline operations on this object. 12043 return Success(1, E); 12044 } 12045 } 12046 } 12047 12048 return BuiltinOp == Builtin::BI__atomic_always_lock_free ? 12049 Success(0, E) : Error(E); 12050 } 12051 case Builtin::BI__builtin_add_overflow: 12052 case Builtin::BI__builtin_sub_overflow: 12053 case Builtin::BI__builtin_mul_overflow: 12054 case Builtin::BI__builtin_sadd_overflow: 12055 case Builtin::BI__builtin_uadd_overflow: 12056 case Builtin::BI__builtin_uaddl_overflow: 12057 case Builtin::BI__builtin_uaddll_overflow: 12058 case Builtin::BI__builtin_usub_overflow: 12059 case Builtin::BI__builtin_usubl_overflow: 12060 case Builtin::BI__builtin_usubll_overflow: 12061 case Builtin::BI__builtin_umul_overflow: 12062 case Builtin::BI__builtin_umull_overflow: 12063 case Builtin::BI__builtin_umulll_overflow: 12064 case Builtin::BI__builtin_saddl_overflow: 12065 case Builtin::BI__builtin_saddll_overflow: 12066 case Builtin::BI__builtin_ssub_overflow: 12067 case Builtin::BI__builtin_ssubl_overflow: 12068 case Builtin::BI__builtin_ssubll_overflow: 12069 case Builtin::BI__builtin_smul_overflow: 12070 case Builtin::BI__builtin_smull_overflow: 12071 case Builtin::BI__builtin_smulll_overflow: { 12072 LValue ResultLValue; 12073 APSInt LHS, RHS; 12074 12075 QualType ResultType = E->getArg(2)->getType()->getPointeeType(); 12076 if (!EvaluateInteger(E->getArg(0), LHS, Info) || 12077 !EvaluateInteger(E->getArg(1), RHS, Info) || 12078 !EvaluatePointer(E->getArg(2), ResultLValue, Info)) 12079 return false; 12080 12081 APSInt Result; 12082 bool DidOverflow = false; 12083 12084 // If the types don't have to match, enlarge all 3 to the largest of them. 12085 if (BuiltinOp == Builtin::BI__builtin_add_overflow || 12086 BuiltinOp == Builtin::BI__builtin_sub_overflow || 12087 BuiltinOp == Builtin::BI__builtin_mul_overflow) { 12088 bool IsSigned = LHS.isSigned() || RHS.isSigned() || 12089 ResultType->isSignedIntegerOrEnumerationType(); 12090 bool AllSigned = LHS.isSigned() && RHS.isSigned() && 12091 ResultType->isSignedIntegerOrEnumerationType(); 12092 uint64_t LHSSize = LHS.getBitWidth(); 12093 uint64_t RHSSize = RHS.getBitWidth(); 12094 uint64_t ResultSize = Info.Ctx.getTypeSize(ResultType); 12095 uint64_t MaxBits = std::max(std::max(LHSSize, RHSSize), ResultSize); 12096 12097 // Add an additional bit if the signedness isn't uniformly agreed to. We 12098 // could do this ONLY if there is a signed and an unsigned that both have 12099 // MaxBits, but the code to check that is pretty nasty. The issue will be 12100 // caught in the shrink-to-result later anyway. 12101 if (IsSigned && !AllSigned) 12102 ++MaxBits; 12103 12104 LHS = APSInt(LHS.extOrTrunc(MaxBits), !IsSigned); 12105 RHS = APSInt(RHS.extOrTrunc(MaxBits), !IsSigned); 12106 Result = APSInt(MaxBits, !IsSigned); 12107 } 12108 12109 // Find largest int. 12110 switch (BuiltinOp) { 12111 default: 12112 llvm_unreachable("Invalid value for BuiltinOp"); 12113 case Builtin::BI__builtin_add_overflow: 12114 case Builtin::BI__builtin_sadd_overflow: 12115 case Builtin::BI__builtin_saddl_overflow: 12116 case Builtin::BI__builtin_saddll_overflow: 12117 case Builtin::BI__builtin_uadd_overflow: 12118 case Builtin::BI__builtin_uaddl_overflow: 12119 case Builtin::BI__builtin_uaddll_overflow: 12120 Result = LHS.isSigned() ? LHS.sadd_ov(RHS, DidOverflow) 12121 : LHS.uadd_ov(RHS, DidOverflow); 12122 break; 12123 case Builtin::BI__builtin_sub_overflow: 12124 case Builtin::BI__builtin_ssub_overflow: 12125 case Builtin::BI__builtin_ssubl_overflow: 12126 case Builtin::BI__builtin_ssubll_overflow: 12127 case Builtin::BI__builtin_usub_overflow: 12128 case Builtin::BI__builtin_usubl_overflow: 12129 case Builtin::BI__builtin_usubll_overflow: 12130 Result = LHS.isSigned() ? LHS.ssub_ov(RHS, DidOverflow) 12131 : LHS.usub_ov(RHS, DidOverflow); 12132 break; 12133 case Builtin::BI__builtin_mul_overflow: 12134 case Builtin::BI__builtin_smul_overflow: 12135 case Builtin::BI__builtin_smull_overflow: 12136 case Builtin::BI__builtin_smulll_overflow: 12137 case Builtin::BI__builtin_umul_overflow: 12138 case Builtin::BI__builtin_umull_overflow: 12139 case Builtin::BI__builtin_umulll_overflow: 12140 Result = LHS.isSigned() ? LHS.smul_ov(RHS, DidOverflow) 12141 : LHS.umul_ov(RHS, DidOverflow); 12142 break; 12143 } 12144 12145 // In the case where multiple sizes are allowed, truncate and see if 12146 // the values are the same. 12147 if (BuiltinOp == Builtin::BI__builtin_add_overflow || 12148 BuiltinOp == Builtin::BI__builtin_sub_overflow || 12149 BuiltinOp == Builtin::BI__builtin_mul_overflow) { 12150 // APSInt doesn't have a TruncOrSelf, so we use extOrTrunc instead, 12151 // since it will give us the behavior of a TruncOrSelf in the case where 12152 // its parameter <= its size. We previously set Result to be at least the 12153 // type-size of the result, so getTypeSize(ResultType) <= Result.BitWidth 12154 // will work exactly like TruncOrSelf. 12155 APSInt Temp = Result.extOrTrunc(Info.Ctx.getTypeSize(ResultType)); 12156 Temp.setIsSigned(ResultType->isSignedIntegerOrEnumerationType()); 12157 12158 if (!APSInt::isSameValue(Temp, Result)) 12159 DidOverflow = true; 12160 Result = Temp; 12161 } 12162 12163 APValue APV{Result}; 12164 if (!handleAssignment(Info, E, ResultLValue, ResultType, APV)) 12165 return false; 12166 return Success(DidOverflow, E); 12167 } 12168 } 12169 } 12170 12171 /// Determine whether this is a pointer past the end of the complete 12172 /// object referred to by the lvalue. 12173 static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx, 12174 const LValue &LV) { 12175 // A null pointer can be viewed as being "past the end" but we don't 12176 // choose to look at it that way here. 12177 if (!LV.getLValueBase()) 12178 return false; 12179 12180 // If the designator is valid and refers to a subobject, we're not pointing 12181 // past the end. 12182 if (!LV.getLValueDesignator().Invalid && 12183 !LV.getLValueDesignator().isOnePastTheEnd()) 12184 return false; 12185 12186 // A pointer to an incomplete type might be past-the-end if the type's size is 12187 // zero. We cannot tell because the type is incomplete. 12188 QualType Ty = getType(LV.getLValueBase()); 12189 if (Ty->isIncompleteType()) 12190 return true; 12191 12192 // We're a past-the-end pointer if we point to the byte after the object, 12193 // no matter what our type or path is. 12194 auto Size = Ctx.getTypeSizeInChars(Ty); 12195 return LV.getLValueOffset() == Size; 12196 } 12197 12198 namespace { 12199 12200 /// Data recursive integer evaluator of certain binary operators. 12201 /// 12202 /// We use a data recursive algorithm for binary operators so that we are able 12203 /// to handle extreme cases of chained binary operators without causing stack 12204 /// overflow. 12205 class DataRecursiveIntBinOpEvaluator { 12206 struct EvalResult { 12207 APValue Val; 12208 bool Failed; 12209 12210 EvalResult() : Failed(false) { } 12211 12212 void swap(EvalResult &RHS) { 12213 Val.swap(RHS.Val); 12214 Failed = RHS.Failed; 12215 RHS.Failed = false; 12216 } 12217 }; 12218 12219 struct Job { 12220 const Expr *E; 12221 EvalResult LHSResult; // meaningful only for binary operator expression. 12222 enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind; 12223 12224 Job() = default; 12225 Job(Job &&) = default; 12226 12227 void startSpeculativeEval(EvalInfo &Info) { 12228 SpecEvalRAII = SpeculativeEvaluationRAII(Info); 12229 } 12230 12231 private: 12232 SpeculativeEvaluationRAII SpecEvalRAII; 12233 }; 12234 12235 SmallVector<Job, 16> Queue; 12236 12237 IntExprEvaluator &IntEval; 12238 EvalInfo &Info; 12239 APValue &FinalResult; 12240 12241 public: 12242 DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result) 12243 : IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { } 12244 12245 /// True if \param E is a binary operator that we are going to handle 12246 /// data recursively. 12247 /// We handle binary operators that are comma, logical, or that have operands 12248 /// with integral or enumeration type. 12249 static bool shouldEnqueue(const BinaryOperator *E) { 12250 return E->getOpcode() == BO_Comma || E->isLogicalOp() || 12251 (E->isPRValue() && E->getType()->isIntegralOrEnumerationType() && 12252 E->getLHS()->getType()->isIntegralOrEnumerationType() && 12253 E->getRHS()->getType()->isIntegralOrEnumerationType()); 12254 } 12255 12256 bool Traverse(const BinaryOperator *E) { 12257 enqueue(E); 12258 EvalResult PrevResult; 12259 while (!Queue.empty()) 12260 process(PrevResult); 12261 12262 if (PrevResult.Failed) return false; 12263 12264 FinalResult.swap(PrevResult.Val); 12265 return true; 12266 } 12267 12268 private: 12269 bool Success(uint64_t Value, const Expr *E, APValue &Result) { 12270 return IntEval.Success(Value, E, Result); 12271 } 12272 bool Success(const APSInt &Value, const Expr *E, APValue &Result) { 12273 return IntEval.Success(Value, E, Result); 12274 } 12275 bool Error(const Expr *E) { 12276 return IntEval.Error(E); 12277 } 12278 bool Error(const Expr *E, diag::kind D) { 12279 return IntEval.Error(E, D); 12280 } 12281 12282 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { 12283 return Info.CCEDiag(E, D); 12284 } 12285 12286 // Returns true if visiting the RHS is necessary, false otherwise. 12287 bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, 12288 bool &SuppressRHSDiags); 12289 12290 bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, 12291 const BinaryOperator *E, APValue &Result); 12292 12293 void EvaluateExpr(const Expr *E, EvalResult &Result) { 12294 Result.Failed = !Evaluate(Result.Val, Info, E); 12295 if (Result.Failed) 12296 Result.Val = APValue(); 12297 } 12298 12299 void process(EvalResult &Result); 12300 12301 void enqueue(const Expr *E) { 12302 E = E->IgnoreParens(); 12303 Queue.resize(Queue.size()+1); 12304 Queue.back().E = E; 12305 Queue.back().Kind = Job::AnyExprKind; 12306 } 12307 }; 12308 12309 } 12310 12311 bool DataRecursiveIntBinOpEvaluator:: 12312 VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, 12313 bool &SuppressRHSDiags) { 12314 if (E->getOpcode() == BO_Comma) { 12315 // Ignore LHS but note if we could not evaluate it. 12316 if (LHSResult.Failed) 12317 return Info.noteSideEffect(); 12318 return true; 12319 } 12320 12321 if (E->isLogicalOp()) { 12322 bool LHSAsBool; 12323 if (!LHSResult.Failed && HandleConversionToBool(LHSResult.Val, LHSAsBool)) { 12324 // We were able to evaluate the LHS, see if we can get away with not 12325 // evaluating the RHS: 0 && X -> 0, 1 || X -> 1 12326 if (LHSAsBool == (E->getOpcode() == BO_LOr)) { 12327 Success(LHSAsBool, E, LHSResult.Val); 12328 return false; // Ignore RHS 12329 } 12330 } else { 12331 LHSResult.Failed = true; 12332 12333 // Since we weren't able to evaluate the left hand side, it 12334 // might have had side effects. 12335 if (!Info.noteSideEffect()) 12336 return false; 12337 12338 // We can't evaluate the LHS; however, sometimes the result 12339 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. 12340 // Don't ignore RHS and suppress diagnostics from this arm. 12341 SuppressRHSDiags = true; 12342 } 12343 12344 return true; 12345 } 12346 12347 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && 12348 E->getRHS()->getType()->isIntegralOrEnumerationType()); 12349 12350 if (LHSResult.Failed && !Info.noteFailure()) 12351 return false; // Ignore RHS; 12352 12353 return true; 12354 } 12355 12356 static void addOrSubLValueAsInteger(APValue &LVal, const APSInt &Index, 12357 bool IsSub) { 12358 // Compute the new offset in the appropriate width, wrapping at 64 bits. 12359 // FIXME: When compiling for a 32-bit target, we should use 32-bit 12360 // offsets. 12361 assert(!LVal.hasLValuePath() && "have designator for integer lvalue"); 12362 CharUnits &Offset = LVal.getLValueOffset(); 12363 uint64_t Offset64 = Offset.getQuantity(); 12364 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue(); 12365 Offset = CharUnits::fromQuantity(IsSub ? Offset64 - Index64 12366 : Offset64 + Index64); 12367 } 12368 12369 bool DataRecursiveIntBinOpEvaluator:: 12370 VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, 12371 const BinaryOperator *E, APValue &Result) { 12372 if (E->getOpcode() == BO_Comma) { 12373 if (RHSResult.Failed) 12374 return false; 12375 Result = RHSResult.Val; 12376 return true; 12377 } 12378 12379 if (E->isLogicalOp()) { 12380 bool lhsResult, rhsResult; 12381 bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult); 12382 bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult); 12383 12384 if (LHSIsOK) { 12385 if (RHSIsOK) { 12386 if (E->getOpcode() == BO_LOr) 12387 return Success(lhsResult || rhsResult, E, Result); 12388 else 12389 return Success(lhsResult && rhsResult, E, Result); 12390 } 12391 } else { 12392 if (RHSIsOK) { 12393 // We can't evaluate the LHS; however, sometimes the result 12394 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. 12395 if (rhsResult == (E->getOpcode() == BO_LOr)) 12396 return Success(rhsResult, E, Result); 12397 } 12398 } 12399 12400 return false; 12401 } 12402 12403 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && 12404 E->getRHS()->getType()->isIntegralOrEnumerationType()); 12405 12406 if (LHSResult.Failed || RHSResult.Failed) 12407 return false; 12408 12409 const APValue &LHSVal = LHSResult.Val; 12410 const APValue &RHSVal = RHSResult.Val; 12411 12412 // Handle cases like (unsigned long)&a + 4. 12413 if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) { 12414 Result = LHSVal; 12415 addOrSubLValueAsInteger(Result, RHSVal.getInt(), E->getOpcode() == BO_Sub); 12416 return true; 12417 } 12418 12419 // Handle cases like 4 + (unsigned long)&a 12420 if (E->getOpcode() == BO_Add && 12421 RHSVal.isLValue() && LHSVal.isInt()) { 12422 Result = RHSVal; 12423 addOrSubLValueAsInteger(Result, LHSVal.getInt(), /*IsSub*/false); 12424 return true; 12425 } 12426 12427 if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) { 12428 // Handle (intptr_t)&&A - (intptr_t)&&B. 12429 if (!LHSVal.getLValueOffset().isZero() || 12430 !RHSVal.getLValueOffset().isZero()) 12431 return false; 12432 const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>(); 12433 const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>(); 12434 if (!LHSExpr || !RHSExpr) 12435 return false; 12436 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); 12437 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); 12438 if (!LHSAddrExpr || !RHSAddrExpr) 12439 return false; 12440 // Make sure both labels come from the same function. 12441 if (LHSAddrExpr->getLabel()->getDeclContext() != 12442 RHSAddrExpr->getLabel()->getDeclContext()) 12443 return false; 12444 Result = APValue(LHSAddrExpr, RHSAddrExpr); 12445 return true; 12446 } 12447 12448 // All the remaining cases expect both operands to be an integer 12449 if (!LHSVal.isInt() || !RHSVal.isInt()) 12450 return Error(E); 12451 12452 // Set up the width and signedness manually, in case it can't be deduced 12453 // from the operation we're performing. 12454 // FIXME: Don't do this in the cases where we can deduce it. 12455 APSInt Value(Info.Ctx.getIntWidth(E->getType()), 12456 E->getType()->isUnsignedIntegerOrEnumerationType()); 12457 if (!handleIntIntBinOp(Info, E, LHSVal.getInt(), E->getOpcode(), 12458 RHSVal.getInt(), Value)) 12459 return false; 12460 return Success(Value, E, Result); 12461 } 12462 12463 void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) { 12464 Job &job = Queue.back(); 12465 12466 switch (job.Kind) { 12467 case Job::AnyExprKind: { 12468 if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(job.E)) { 12469 if (shouldEnqueue(Bop)) { 12470 job.Kind = Job::BinOpKind; 12471 enqueue(Bop->getLHS()); 12472 return; 12473 } 12474 } 12475 12476 EvaluateExpr(job.E, Result); 12477 Queue.pop_back(); 12478 return; 12479 } 12480 12481 case Job::BinOpKind: { 12482 const BinaryOperator *Bop = cast<BinaryOperator>(job.E); 12483 bool SuppressRHSDiags = false; 12484 if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) { 12485 Queue.pop_back(); 12486 return; 12487 } 12488 if (SuppressRHSDiags) 12489 job.startSpeculativeEval(Info); 12490 job.LHSResult.swap(Result); 12491 job.Kind = Job::BinOpVisitedLHSKind; 12492 enqueue(Bop->getRHS()); 12493 return; 12494 } 12495 12496 case Job::BinOpVisitedLHSKind: { 12497 const BinaryOperator *Bop = cast<BinaryOperator>(job.E); 12498 EvalResult RHS; 12499 RHS.swap(Result); 12500 Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val); 12501 Queue.pop_back(); 12502 return; 12503 } 12504 } 12505 12506 llvm_unreachable("Invalid Job::Kind!"); 12507 } 12508 12509 namespace { 12510 enum class CmpResult { 12511 Unequal, 12512 Less, 12513 Equal, 12514 Greater, 12515 Unordered, 12516 }; 12517 } 12518 12519 template <class SuccessCB, class AfterCB> 12520 static bool 12521 EvaluateComparisonBinaryOperator(EvalInfo &Info, const BinaryOperator *E, 12522 SuccessCB &&Success, AfterCB &&DoAfter) { 12523 assert(!E->isValueDependent()); 12524 assert(E->isComparisonOp() && "expected comparison operator"); 12525 assert((E->getOpcode() == BO_Cmp || 12526 E->getType()->isIntegralOrEnumerationType()) && 12527 "unsupported binary expression evaluation"); 12528 auto Error = [&](const Expr *E) { 12529 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 12530 return false; 12531 }; 12532 12533 bool IsRelational = E->isRelationalOp() || E->getOpcode() == BO_Cmp; 12534 bool IsEquality = E->isEqualityOp(); 12535 12536 QualType LHSTy = E->getLHS()->getType(); 12537 QualType RHSTy = E->getRHS()->getType(); 12538 12539 if (LHSTy->isIntegralOrEnumerationType() && 12540 RHSTy->isIntegralOrEnumerationType()) { 12541 APSInt LHS, RHS; 12542 bool LHSOK = EvaluateInteger(E->getLHS(), LHS, Info); 12543 if (!LHSOK && !Info.noteFailure()) 12544 return false; 12545 if (!EvaluateInteger(E->getRHS(), RHS, Info) || !LHSOK) 12546 return false; 12547 if (LHS < RHS) 12548 return Success(CmpResult::Less, E); 12549 if (LHS > RHS) 12550 return Success(CmpResult::Greater, E); 12551 return Success(CmpResult::Equal, E); 12552 } 12553 12554 if (LHSTy->isFixedPointType() || RHSTy->isFixedPointType()) { 12555 APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHSTy)); 12556 APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHSTy)); 12557 12558 bool LHSOK = EvaluateFixedPointOrInteger(E->getLHS(), LHSFX, Info); 12559 if (!LHSOK && !Info.noteFailure()) 12560 return false; 12561 if (!EvaluateFixedPointOrInteger(E->getRHS(), RHSFX, Info) || !LHSOK) 12562 return false; 12563 if (LHSFX < RHSFX) 12564 return Success(CmpResult::Less, E); 12565 if (LHSFX > RHSFX) 12566 return Success(CmpResult::Greater, E); 12567 return Success(CmpResult::Equal, E); 12568 } 12569 12570 if (LHSTy->isAnyComplexType() || RHSTy->isAnyComplexType()) { 12571 ComplexValue LHS, RHS; 12572 bool LHSOK; 12573 if (E->isAssignmentOp()) { 12574 LValue LV; 12575 EvaluateLValue(E->getLHS(), LV, Info); 12576 LHSOK = false; 12577 } else if (LHSTy->isRealFloatingType()) { 12578 LHSOK = EvaluateFloat(E->getLHS(), LHS.FloatReal, Info); 12579 if (LHSOK) { 12580 LHS.makeComplexFloat(); 12581 LHS.FloatImag = APFloat(LHS.FloatReal.getSemantics()); 12582 } 12583 } else { 12584 LHSOK = EvaluateComplex(E->getLHS(), LHS, Info); 12585 } 12586 if (!LHSOK && !Info.noteFailure()) 12587 return false; 12588 12589 if (E->getRHS()->getType()->isRealFloatingType()) { 12590 if (!EvaluateFloat(E->getRHS(), RHS.FloatReal, Info) || !LHSOK) 12591 return false; 12592 RHS.makeComplexFloat(); 12593 RHS.FloatImag = APFloat(RHS.FloatReal.getSemantics()); 12594 } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) 12595 return false; 12596 12597 if (LHS.isComplexFloat()) { 12598 APFloat::cmpResult CR_r = 12599 LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal()); 12600 APFloat::cmpResult CR_i = 12601 LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag()); 12602 bool IsEqual = CR_r == APFloat::cmpEqual && CR_i == APFloat::cmpEqual; 12603 return Success(IsEqual ? CmpResult::Equal : CmpResult::Unequal, E); 12604 } else { 12605 assert(IsEquality && "invalid complex comparison"); 12606 bool IsEqual = LHS.getComplexIntReal() == RHS.getComplexIntReal() && 12607 LHS.getComplexIntImag() == RHS.getComplexIntImag(); 12608 return Success(IsEqual ? CmpResult::Equal : CmpResult::Unequal, E); 12609 } 12610 } 12611 12612 if (LHSTy->isRealFloatingType() && 12613 RHSTy->isRealFloatingType()) { 12614 APFloat RHS(0.0), LHS(0.0); 12615 12616 bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info); 12617 if (!LHSOK && !Info.noteFailure()) 12618 return false; 12619 12620 if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK) 12621 return false; 12622 12623 assert(E->isComparisonOp() && "Invalid binary operator!"); 12624 llvm::APFloatBase::cmpResult APFloatCmpResult = LHS.compare(RHS); 12625 if (!Info.InConstantContext && 12626 APFloatCmpResult == APFloat::cmpUnordered && 12627 E->getFPFeaturesInEffect(Info.Ctx.getLangOpts()).isFPConstrained()) { 12628 // Note: Compares may raise invalid in some cases involving NaN or sNaN. 12629 Info.FFDiag(E, diag::note_constexpr_float_arithmetic_strict); 12630 return false; 12631 } 12632 auto GetCmpRes = [&]() { 12633 switch (APFloatCmpResult) { 12634 case APFloat::cmpEqual: 12635 return CmpResult::Equal; 12636 case APFloat::cmpLessThan: 12637 return CmpResult::Less; 12638 case APFloat::cmpGreaterThan: 12639 return CmpResult::Greater; 12640 case APFloat::cmpUnordered: 12641 return CmpResult::Unordered; 12642 } 12643 llvm_unreachable("Unrecognised APFloat::cmpResult enum"); 12644 }; 12645 return Success(GetCmpRes(), E); 12646 } 12647 12648 if (LHSTy->isPointerType() && RHSTy->isPointerType()) { 12649 LValue LHSValue, RHSValue; 12650 12651 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info); 12652 if (!LHSOK && !Info.noteFailure()) 12653 return false; 12654 12655 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK) 12656 return false; 12657 12658 // Reject differing bases from the normal codepath; we special-case 12659 // comparisons to null. 12660 if (!HasSameBase(LHSValue, RHSValue)) { 12661 // Inequalities and subtractions between unrelated pointers have 12662 // unspecified or undefined behavior. 12663 if (!IsEquality) { 12664 Info.FFDiag(E, diag::note_constexpr_pointer_comparison_unspecified); 12665 return false; 12666 } 12667 // A constant address may compare equal to the address of a symbol. 12668 // The one exception is that address of an object cannot compare equal 12669 // to a null pointer constant. 12670 if ((!LHSValue.Base && !LHSValue.Offset.isZero()) || 12671 (!RHSValue.Base && !RHSValue.Offset.isZero())) 12672 return Error(E); 12673 // It's implementation-defined whether distinct literals will have 12674 // distinct addresses. In clang, the result of such a comparison is 12675 // unspecified, so it is not a constant expression. However, we do know 12676 // that the address of a literal will be non-null. 12677 if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) && 12678 LHSValue.Base && RHSValue.Base) 12679 return Error(E); 12680 // We can't tell whether weak symbols will end up pointing to the same 12681 // object. 12682 if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue)) 12683 return Error(E); 12684 // We can't compare the address of the start of one object with the 12685 // past-the-end address of another object, per C++ DR1652. 12686 if ((LHSValue.Base && LHSValue.Offset.isZero() && 12687 isOnePastTheEndOfCompleteObject(Info.Ctx, RHSValue)) || 12688 (RHSValue.Base && RHSValue.Offset.isZero() && 12689 isOnePastTheEndOfCompleteObject(Info.Ctx, LHSValue))) 12690 return Error(E); 12691 // We can't tell whether an object is at the same address as another 12692 // zero sized object. 12693 if ((RHSValue.Base && isZeroSized(LHSValue)) || 12694 (LHSValue.Base && isZeroSized(RHSValue))) 12695 return Error(E); 12696 return Success(CmpResult::Unequal, E); 12697 } 12698 12699 const CharUnits &LHSOffset = LHSValue.getLValueOffset(); 12700 const CharUnits &RHSOffset = RHSValue.getLValueOffset(); 12701 12702 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator(); 12703 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator(); 12704 12705 // C++11 [expr.rel]p3: 12706 // Pointers to void (after pointer conversions) can be compared, with a 12707 // result defined as follows: If both pointers represent the same 12708 // address or are both the null pointer value, the result is true if the 12709 // operator is <= or >= and false otherwise; otherwise the result is 12710 // unspecified. 12711 // We interpret this as applying to pointers to *cv* void. 12712 if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset && IsRelational) 12713 Info.CCEDiag(E, diag::note_constexpr_void_comparison); 12714 12715 // C++11 [expr.rel]p2: 12716 // - If two pointers point to non-static data members of the same object, 12717 // or to subobjects or array elements fo such members, recursively, the 12718 // pointer to the later declared member compares greater provided the 12719 // two members have the same access control and provided their class is 12720 // not a union. 12721 // [...] 12722 // - Otherwise pointer comparisons are unspecified. 12723 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && IsRelational) { 12724 bool WasArrayIndex; 12725 unsigned Mismatch = FindDesignatorMismatch( 12726 getType(LHSValue.Base), LHSDesignator, RHSDesignator, WasArrayIndex); 12727 // At the point where the designators diverge, the comparison has a 12728 // specified value if: 12729 // - we are comparing array indices 12730 // - we are comparing fields of a union, or fields with the same access 12731 // Otherwise, the result is unspecified and thus the comparison is not a 12732 // constant expression. 12733 if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() && 12734 Mismatch < RHSDesignator.Entries.size()) { 12735 const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]); 12736 const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]); 12737 if (!LF && !RF) 12738 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes); 12739 else if (!LF) 12740 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) 12741 << getAsBaseClass(LHSDesignator.Entries[Mismatch]) 12742 << RF->getParent() << RF; 12743 else if (!RF) 12744 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) 12745 << getAsBaseClass(RHSDesignator.Entries[Mismatch]) 12746 << LF->getParent() << LF; 12747 else if (!LF->getParent()->isUnion() && 12748 LF->getAccess() != RF->getAccess()) 12749 Info.CCEDiag(E, 12750 diag::note_constexpr_pointer_comparison_differing_access) 12751 << LF << LF->getAccess() << RF << RF->getAccess() 12752 << LF->getParent(); 12753 } 12754 } 12755 12756 // The comparison here must be unsigned, and performed with the same 12757 // width as the pointer. 12758 unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy); 12759 uint64_t CompareLHS = LHSOffset.getQuantity(); 12760 uint64_t CompareRHS = RHSOffset.getQuantity(); 12761 assert(PtrSize <= 64 && "Unexpected pointer width"); 12762 uint64_t Mask = ~0ULL >> (64 - PtrSize); 12763 CompareLHS &= Mask; 12764 CompareRHS &= Mask; 12765 12766 // If there is a base and this is a relational operator, we can only 12767 // compare pointers within the object in question; otherwise, the result 12768 // depends on where the object is located in memory. 12769 if (!LHSValue.Base.isNull() && IsRelational) { 12770 QualType BaseTy = getType(LHSValue.Base); 12771 if (BaseTy->isIncompleteType()) 12772 return Error(E); 12773 CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy); 12774 uint64_t OffsetLimit = Size.getQuantity(); 12775 if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit) 12776 return Error(E); 12777 } 12778 12779 if (CompareLHS < CompareRHS) 12780 return Success(CmpResult::Less, E); 12781 if (CompareLHS > CompareRHS) 12782 return Success(CmpResult::Greater, E); 12783 return Success(CmpResult::Equal, E); 12784 } 12785 12786 if (LHSTy->isMemberPointerType()) { 12787 assert(IsEquality && "unexpected member pointer operation"); 12788 assert(RHSTy->isMemberPointerType() && "invalid comparison"); 12789 12790 MemberPtr LHSValue, RHSValue; 12791 12792 bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info); 12793 if (!LHSOK && !Info.noteFailure()) 12794 return false; 12795 12796 if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK) 12797 return false; 12798 12799 // C++11 [expr.eq]p2: 12800 // If both operands are null, they compare equal. Otherwise if only one is 12801 // null, they compare unequal. 12802 if (!LHSValue.getDecl() || !RHSValue.getDecl()) { 12803 bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl(); 12804 return Success(Equal ? CmpResult::Equal : CmpResult::Unequal, E); 12805 } 12806 12807 // Otherwise if either is a pointer to a virtual member function, the 12808 // result is unspecified. 12809 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl())) 12810 if (MD->isVirtual()) 12811 Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; 12812 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl())) 12813 if (MD->isVirtual()) 12814 Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; 12815 12816 // Otherwise they compare equal if and only if they would refer to the 12817 // same member of the same most derived object or the same subobject if 12818 // they were dereferenced with a hypothetical object of the associated 12819 // class type. 12820 bool Equal = LHSValue == RHSValue; 12821 return Success(Equal ? CmpResult::Equal : CmpResult::Unequal, E); 12822 } 12823 12824 if (LHSTy->isNullPtrType()) { 12825 assert(E->isComparisonOp() && "unexpected nullptr operation"); 12826 assert(RHSTy->isNullPtrType() && "missing pointer conversion"); 12827 // C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t 12828 // are compared, the result is true of the operator is <=, >= or ==, and 12829 // false otherwise. 12830 return Success(CmpResult::Equal, E); 12831 } 12832 12833 return DoAfter(); 12834 } 12835 12836 bool RecordExprEvaluator::VisitBinCmp(const BinaryOperator *E) { 12837 if (!CheckLiteralType(Info, E)) 12838 return false; 12839 12840 auto OnSuccess = [&](CmpResult CR, const BinaryOperator *E) { 12841 ComparisonCategoryResult CCR; 12842 switch (CR) { 12843 case CmpResult::Unequal: 12844 llvm_unreachable("should never produce Unequal for three-way comparison"); 12845 case CmpResult::Less: 12846 CCR = ComparisonCategoryResult::Less; 12847 break; 12848 case CmpResult::Equal: 12849 CCR = ComparisonCategoryResult::Equal; 12850 break; 12851 case CmpResult::Greater: 12852 CCR = ComparisonCategoryResult::Greater; 12853 break; 12854 case CmpResult::Unordered: 12855 CCR = ComparisonCategoryResult::Unordered; 12856 break; 12857 } 12858 // Evaluation succeeded. Lookup the information for the comparison category 12859 // type and fetch the VarDecl for the result. 12860 const ComparisonCategoryInfo &CmpInfo = 12861 Info.Ctx.CompCategories.getInfoForType(E->getType()); 12862 const VarDecl *VD = CmpInfo.getValueInfo(CmpInfo.makeWeakResult(CCR))->VD; 12863 // Check and evaluate the result as a constant expression. 12864 LValue LV; 12865 LV.set(VD); 12866 if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result)) 12867 return false; 12868 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result, 12869 ConstantExprKind::Normal); 12870 }; 12871 return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() { 12872 return ExprEvaluatorBaseTy::VisitBinCmp(E); 12873 }); 12874 } 12875 12876 bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 12877 // We don't support assignment in C. C++ assignments don't get here because 12878 // assignment is an lvalue in C++. 12879 if (E->isAssignmentOp()) { 12880 Error(E); 12881 if (!Info.noteFailure()) 12882 return false; 12883 } 12884 12885 if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E)) 12886 return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E); 12887 12888 assert((!E->getLHS()->getType()->isIntegralOrEnumerationType() || 12889 !E->getRHS()->getType()->isIntegralOrEnumerationType()) && 12890 "DataRecursiveIntBinOpEvaluator should have handled integral types"); 12891 12892 if (E->isComparisonOp()) { 12893 // Evaluate builtin binary comparisons by evaluating them as three-way 12894 // comparisons and then translating the result. 12895 auto OnSuccess = [&](CmpResult CR, const BinaryOperator *E) { 12896 assert((CR != CmpResult::Unequal || E->isEqualityOp()) && 12897 "should only produce Unequal for equality comparisons"); 12898 bool IsEqual = CR == CmpResult::Equal, 12899 IsLess = CR == CmpResult::Less, 12900 IsGreater = CR == CmpResult::Greater; 12901 auto Op = E->getOpcode(); 12902 switch (Op) { 12903 default: 12904 llvm_unreachable("unsupported binary operator"); 12905 case BO_EQ: 12906 case BO_NE: 12907 return Success(IsEqual == (Op == BO_EQ), E); 12908 case BO_LT: 12909 return Success(IsLess, E); 12910 case BO_GT: 12911 return Success(IsGreater, E); 12912 case BO_LE: 12913 return Success(IsEqual || IsLess, E); 12914 case BO_GE: 12915 return Success(IsEqual || IsGreater, E); 12916 } 12917 }; 12918 return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() { 12919 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 12920 }); 12921 } 12922 12923 QualType LHSTy = E->getLHS()->getType(); 12924 QualType RHSTy = E->getRHS()->getType(); 12925 12926 if (LHSTy->isPointerType() && RHSTy->isPointerType() && 12927 E->getOpcode() == BO_Sub) { 12928 LValue LHSValue, RHSValue; 12929 12930 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info); 12931 if (!LHSOK && !Info.noteFailure()) 12932 return false; 12933 12934 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK) 12935 return false; 12936 12937 // Reject differing bases from the normal codepath; we special-case 12938 // comparisons to null. 12939 if (!HasSameBase(LHSValue, RHSValue)) { 12940 // Handle &&A - &&B. 12941 if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero()) 12942 return Error(E); 12943 const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr *>(); 12944 const Expr *RHSExpr = RHSValue.Base.dyn_cast<const Expr *>(); 12945 if (!LHSExpr || !RHSExpr) 12946 return Error(E); 12947 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); 12948 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); 12949 if (!LHSAddrExpr || !RHSAddrExpr) 12950 return Error(E); 12951 // Make sure both labels come from the same function. 12952 if (LHSAddrExpr->getLabel()->getDeclContext() != 12953 RHSAddrExpr->getLabel()->getDeclContext()) 12954 return Error(E); 12955 return Success(APValue(LHSAddrExpr, RHSAddrExpr), E); 12956 } 12957 const CharUnits &LHSOffset = LHSValue.getLValueOffset(); 12958 const CharUnits &RHSOffset = RHSValue.getLValueOffset(); 12959 12960 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator(); 12961 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator(); 12962 12963 // C++11 [expr.add]p6: 12964 // Unless both pointers point to elements of the same array object, or 12965 // one past the last element of the array object, the behavior is 12966 // undefined. 12967 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && 12968 !AreElementsOfSameArray(getType(LHSValue.Base), LHSDesignator, 12969 RHSDesignator)) 12970 Info.CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array); 12971 12972 QualType Type = E->getLHS()->getType(); 12973 QualType ElementType = Type->castAs<PointerType>()->getPointeeType(); 12974 12975 CharUnits ElementSize; 12976 if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize)) 12977 return false; 12978 12979 // As an extension, a type may have zero size (empty struct or union in 12980 // C, array of zero length). Pointer subtraction in such cases has 12981 // undefined behavior, so is not constant. 12982 if (ElementSize.isZero()) { 12983 Info.FFDiag(E, diag::note_constexpr_pointer_subtraction_zero_size) 12984 << ElementType; 12985 return false; 12986 } 12987 12988 // FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime, 12989 // and produce incorrect results when it overflows. Such behavior 12990 // appears to be non-conforming, but is common, so perhaps we should 12991 // assume the standard intended for such cases to be undefined behavior 12992 // and check for them. 12993 12994 // Compute (LHSOffset - RHSOffset) / Size carefully, checking for 12995 // overflow in the final conversion to ptrdiff_t. 12996 APSInt LHS(llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false); 12997 APSInt RHS(llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false); 12998 APSInt ElemSize(llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true), 12999 false); 13000 APSInt TrueResult = (LHS - RHS) / ElemSize; 13001 APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType())); 13002 13003 if (Result.extend(65) != TrueResult && 13004 !HandleOverflow(Info, E, TrueResult, E->getType())) 13005 return false; 13006 return Success(Result, E); 13007 } 13008 13009 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 13010 } 13011 13012 /// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with 13013 /// a result as the expression's type. 13014 bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr( 13015 const UnaryExprOrTypeTraitExpr *E) { 13016 switch(E->getKind()) { 13017 case UETT_PreferredAlignOf: 13018 case UETT_AlignOf: { 13019 if (E->isArgumentType()) 13020 return Success(GetAlignOfType(Info, E->getArgumentType(), E->getKind()), 13021 E); 13022 else 13023 return Success(GetAlignOfExpr(Info, E->getArgumentExpr(), E->getKind()), 13024 E); 13025 } 13026 13027 case UETT_VecStep: { 13028 QualType Ty = E->getTypeOfArgument(); 13029 13030 if (Ty->isVectorType()) { 13031 unsigned n = Ty->castAs<VectorType>()->getNumElements(); 13032 13033 // The vec_step built-in functions that take a 3-component 13034 // vector return 4. (OpenCL 1.1 spec 6.11.12) 13035 if (n == 3) 13036 n = 4; 13037 13038 return Success(n, E); 13039 } else 13040 return Success(1, E); 13041 } 13042 13043 case UETT_SizeOf: { 13044 QualType SrcTy = E->getTypeOfArgument(); 13045 // C++ [expr.sizeof]p2: "When applied to a reference or a reference type, 13046 // the result is the size of the referenced type." 13047 if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>()) 13048 SrcTy = Ref->getPointeeType(); 13049 13050 CharUnits Sizeof; 13051 if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof)) 13052 return false; 13053 return Success(Sizeof, E); 13054 } 13055 case UETT_OpenMPRequiredSimdAlign: 13056 assert(E->isArgumentType()); 13057 return Success( 13058 Info.Ctx.toCharUnitsFromBits( 13059 Info.Ctx.getOpenMPDefaultSimdAlign(E->getArgumentType())) 13060 .getQuantity(), 13061 E); 13062 } 13063 13064 llvm_unreachable("unknown expr/type trait"); 13065 } 13066 13067 bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) { 13068 CharUnits Result; 13069 unsigned n = OOE->getNumComponents(); 13070 if (n == 0) 13071 return Error(OOE); 13072 QualType CurrentType = OOE->getTypeSourceInfo()->getType(); 13073 for (unsigned i = 0; i != n; ++i) { 13074 OffsetOfNode ON = OOE->getComponent(i); 13075 switch (ON.getKind()) { 13076 case OffsetOfNode::Array: { 13077 const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex()); 13078 APSInt IdxResult; 13079 if (!EvaluateInteger(Idx, IdxResult, Info)) 13080 return false; 13081 const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType); 13082 if (!AT) 13083 return Error(OOE); 13084 CurrentType = AT->getElementType(); 13085 CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType); 13086 Result += IdxResult.getSExtValue() * ElementSize; 13087 break; 13088 } 13089 13090 case OffsetOfNode::Field: { 13091 FieldDecl *MemberDecl = ON.getField(); 13092 const RecordType *RT = CurrentType->getAs<RecordType>(); 13093 if (!RT) 13094 return Error(OOE); 13095 RecordDecl *RD = RT->getDecl(); 13096 if (RD->isInvalidDecl()) return false; 13097 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); 13098 unsigned i = MemberDecl->getFieldIndex(); 13099 assert(i < RL.getFieldCount() && "offsetof field in wrong type"); 13100 Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i)); 13101 CurrentType = MemberDecl->getType().getNonReferenceType(); 13102 break; 13103 } 13104 13105 case OffsetOfNode::Identifier: 13106 llvm_unreachable("dependent __builtin_offsetof"); 13107 13108 case OffsetOfNode::Base: { 13109 CXXBaseSpecifier *BaseSpec = ON.getBase(); 13110 if (BaseSpec->isVirtual()) 13111 return Error(OOE); 13112 13113 // Find the layout of the class whose base we are looking into. 13114 const RecordType *RT = CurrentType->getAs<RecordType>(); 13115 if (!RT) 13116 return Error(OOE); 13117 RecordDecl *RD = RT->getDecl(); 13118 if (RD->isInvalidDecl()) return false; 13119 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); 13120 13121 // Find the base class itself. 13122 CurrentType = BaseSpec->getType(); 13123 const RecordType *BaseRT = CurrentType->getAs<RecordType>(); 13124 if (!BaseRT) 13125 return Error(OOE); 13126 13127 // Add the offset to the base. 13128 Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl())); 13129 break; 13130 } 13131 } 13132 } 13133 return Success(Result, OOE); 13134 } 13135 13136 bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 13137 switch (E->getOpcode()) { 13138 default: 13139 // Address, indirect, pre/post inc/dec, etc are not valid constant exprs. 13140 // See C99 6.6p3. 13141 return Error(E); 13142 case UO_Extension: 13143 // FIXME: Should extension allow i-c-e extension expressions in its scope? 13144 // If so, we could clear the diagnostic ID. 13145 return Visit(E->getSubExpr()); 13146 case UO_Plus: 13147 // The result is just the value. 13148 return Visit(E->getSubExpr()); 13149 case UO_Minus: { 13150 if (!Visit(E->getSubExpr())) 13151 return false; 13152 if (!Result.isInt()) return Error(E); 13153 const APSInt &Value = Result.getInt(); 13154 if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow() && 13155 !HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1), 13156 E->getType())) 13157 return false; 13158 return Success(-Value, E); 13159 } 13160 case UO_Not: { 13161 if (!Visit(E->getSubExpr())) 13162 return false; 13163 if (!Result.isInt()) return Error(E); 13164 return Success(~Result.getInt(), E); 13165 } 13166 case UO_LNot: { 13167 bool bres; 13168 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info)) 13169 return false; 13170 return Success(!bres, E); 13171 } 13172 } 13173 } 13174 13175 /// HandleCast - This is used to evaluate implicit or explicit casts where the 13176 /// result type is integer. 13177 bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) { 13178 const Expr *SubExpr = E->getSubExpr(); 13179 QualType DestType = E->getType(); 13180 QualType SrcType = SubExpr->getType(); 13181 13182 switch (E->getCastKind()) { 13183 case CK_BaseToDerived: 13184 case CK_DerivedToBase: 13185 case CK_UncheckedDerivedToBase: 13186 case CK_Dynamic: 13187 case CK_ToUnion: 13188 case CK_ArrayToPointerDecay: 13189 case CK_FunctionToPointerDecay: 13190 case CK_NullToPointer: 13191 case CK_NullToMemberPointer: 13192 case CK_BaseToDerivedMemberPointer: 13193 case CK_DerivedToBaseMemberPointer: 13194 case CK_ReinterpretMemberPointer: 13195 case CK_ConstructorConversion: 13196 case CK_IntegralToPointer: 13197 case CK_ToVoid: 13198 case CK_VectorSplat: 13199 case CK_IntegralToFloating: 13200 case CK_FloatingCast: 13201 case CK_CPointerToObjCPointerCast: 13202 case CK_BlockPointerToObjCPointerCast: 13203 case CK_AnyPointerToBlockPointerCast: 13204 case CK_ObjCObjectLValueCast: 13205 case CK_FloatingRealToComplex: 13206 case CK_FloatingComplexToReal: 13207 case CK_FloatingComplexCast: 13208 case CK_FloatingComplexToIntegralComplex: 13209 case CK_IntegralRealToComplex: 13210 case CK_IntegralComplexCast: 13211 case CK_IntegralComplexToFloatingComplex: 13212 case CK_BuiltinFnToFnPtr: 13213 case CK_ZeroToOCLOpaqueType: 13214 case CK_NonAtomicToAtomic: 13215 case CK_AddressSpaceConversion: 13216 case CK_IntToOCLSampler: 13217 case CK_FloatingToFixedPoint: 13218 case CK_FixedPointToFloating: 13219 case CK_FixedPointCast: 13220 case CK_IntegralToFixedPoint: 13221 case CK_MatrixCast: 13222 llvm_unreachable("invalid cast kind for integral value"); 13223 13224 case CK_BitCast: 13225 case CK_Dependent: 13226 case CK_LValueBitCast: 13227 case CK_ARCProduceObject: 13228 case CK_ARCConsumeObject: 13229 case CK_ARCReclaimReturnedObject: 13230 case CK_ARCExtendBlockObject: 13231 case CK_CopyAndAutoreleaseBlockObject: 13232 return Error(E); 13233 13234 case CK_UserDefinedConversion: 13235 case CK_LValueToRValue: 13236 case CK_AtomicToNonAtomic: 13237 case CK_NoOp: 13238 case CK_LValueToRValueBitCast: 13239 return ExprEvaluatorBaseTy::VisitCastExpr(E); 13240 13241 case CK_MemberPointerToBoolean: 13242 case CK_PointerToBoolean: 13243 case CK_IntegralToBoolean: 13244 case CK_FloatingToBoolean: 13245 case CK_BooleanToSignedIntegral: 13246 case CK_FloatingComplexToBoolean: 13247 case CK_IntegralComplexToBoolean: { 13248 bool BoolResult; 13249 if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info)) 13250 return false; 13251 uint64_t IntResult = BoolResult; 13252 if (BoolResult && E->getCastKind() == CK_BooleanToSignedIntegral) 13253 IntResult = (uint64_t)-1; 13254 return Success(IntResult, E); 13255 } 13256 13257 case CK_FixedPointToIntegral: { 13258 APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SrcType)); 13259 if (!EvaluateFixedPoint(SubExpr, Src, Info)) 13260 return false; 13261 bool Overflowed; 13262 llvm::APSInt Result = Src.convertToInt( 13263 Info.Ctx.getIntWidth(DestType), 13264 DestType->isSignedIntegerOrEnumerationType(), &Overflowed); 13265 if (Overflowed && !HandleOverflow(Info, E, Result, DestType)) 13266 return false; 13267 return Success(Result, E); 13268 } 13269 13270 case CK_FixedPointToBoolean: { 13271 // Unsigned padding does not affect this. 13272 APValue Val; 13273 if (!Evaluate(Val, Info, SubExpr)) 13274 return false; 13275 return Success(Val.getFixedPoint().getBoolValue(), E); 13276 } 13277 13278 case CK_IntegralCast: { 13279 if (!Visit(SubExpr)) 13280 return false; 13281 13282 if (!Result.isInt()) { 13283 // Allow casts of address-of-label differences if they are no-ops 13284 // or narrowing. (The narrowing case isn't actually guaranteed to 13285 // be constant-evaluatable except in some narrow cases which are hard 13286 // to detect here. We let it through on the assumption the user knows 13287 // what they are doing.) 13288 if (Result.isAddrLabelDiff()) 13289 return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType); 13290 // Only allow casts of lvalues if they are lossless. 13291 return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType); 13292 } 13293 13294 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, 13295 Result.getInt()), E); 13296 } 13297 13298 case CK_PointerToIntegral: { 13299 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 13300 13301 LValue LV; 13302 if (!EvaluatePointer(SubExpr, LV, Info)) 13303 return false; 13304 13305 if (LV.getLValueBase()) { 13306 // Only allow based lvalue casts if they are lossless. 13307 // FIXME: Allow a larger integer size than the pointer size, and allow 13308 // narrowing back down to pointer width in subsequent integral casts. 13309 // FIXME: Check integer type's active bits, not its type size. 13310 if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType)) 13311 return Error(E); 13312 13313 LV.Designator.setInvalid(); 13314 LV.moveInto(Result); 13315 return true; 13316 } 13317 13318 APSInt AsInt; 13319 APValue V; 13320 LV.moveInto(V); 13321 if (!V.toIntegralConstant(AsInt, SrcType, Info.Ctx)) 13322 llvm_unreachable("Can't cast this!"); 13323 13324 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E); 13325 } 13326 13327 case CK_IntegralComplexToReal: { 13328 ComplexValue C; 13329 if (!EvaluateComplex(SubExpr, C, Info)) 13330 return false; 13331 return Success(C.getComplexIntReal(), E); 13332 } 13333 13334 case CK_FloatingToIntegral: { 13335 APFloat F(0.0); 13336 if (!EvaluateFloat(SubExpr, F, Info)) 13337 return false; 13338 13339 APSInt Value; 13340 if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value)) 13341 return false; 13342 return Success(Value, E); 13343 } 13344 } 13345 13346 llvm_unreachable("unknown cast resulting in integral value"); 13347 } 13348 13349 bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 13350 if (E->getSubExpr()->getType()->isAnyComplexType()) { 13351 ComplexValue LV; 13352 if (!EvaluateComplex(E->getSubExpr(), LV, Info)) 13353 return false; 13354 if (!LV.isComplexInt()) 13355 return Error(E); 13356 return Success(LV.getComplexIntReal(), E); 13357 } 13358 13359 return Visit(E->getSubExpr()); 13360 } 13361 13362 bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 13363 if (E->getSubExpr()->getType()->isComplexIntegerType()) { 13364 ComplexValue LV; 13365 if (!EvaluateComplex(E->getSubExpr(), LV, Info)) 13366 return false; 13367 if (!LV.isComplexInt()) 13368 return Error(E); 13369 return Success(LV.getComplexIntImag(), E); 13370 } 13371 13372 VisitIgnoredValue(E->getSubExpr()); 13373 return Success(0, E); 13374 } 13375 13376 bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) { 13377 return Success(E->getPackLength(), E); 13378 } 13379 13380 bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) { 13381 return Success(E->getValue(), E); 13382 } 13383 13384 bool IntExprEvaluator::VisitConceptSpecializationExpr( 13385 const ConceptSpecializationExpr *E) { 13386 return Success(E->isSatisfied(), E); 13387 } 13388 13389 bool IntExprEvaluator::VisitRequiresExpr(const RequiresExpr *E) { 13390 return Success(E->isSatisfied(), E); 13391 } 13392 13393 bool FixedPointExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 13394 switch (E->getOpcode()) { 13395 default: 13396 // Invalid unary operators 13397 return Error(E); 13398 case UO_Plus: 13399 // The result is just the value. 13400 return Visit(E->getSubExpr()); 13401 case UO_Minus: { 13402 if (!Visit(E->getSubExpr())) return false; 13403 if (!Result.isFixedPoint()) 13404 return Error(E); 13405 bool Overflowed; 13406 APFixedPoint Negated = Result.getFixedPoint().negate(&Overflowed); 13407 if (Overflowed && !HandleOverflow(Info, E, Negated, E->getType())) 13408 return false; 13409 return Success(Negated, E); 13410 } 13411 case UO_LNot: { 13412 bool bres; 13413 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info)) 13414 return false; 13415 return Success(!bres, E); 13416 } 13417 } 13418 } 13419 13420 bool FixedPointExprEvaluator::VisitCastExpr(const CastExpr *E) { 13421 const Expr *SubExpr = E->getSubExpr(); 13422 QualType DestType = E->getType(); 13423 assert(DestType->isFixedPointType() && 13424 "Expected destination type to be a fixed point type"); 13425 auto DestFXSema = Info.Ctx.getFixedPointSemantics(DestType); 13426 13427 switch (E->getCastKind()) { 13428 case CK_FixedPointCast: { 13429 APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SubExpr->getType())); 13430 if (!EvaluateFixedPoint(SubExpr, Src, Info)) 13431 return false; 13432 bool Overflowed; 13433 APFixedPoint Result = Src.convert(DestFXSema, &Overflowed); 13434 if (Overflowed) { 13435 if (Info.checkingForUndefinedBehavior()) 13436 Info.Ctx.getDiagnostics().Report(E->getExprLoc(), 13437 diag::warn_fixedpoint_constant_overflow) 13438 << Result.toString() << E->getType(); 13439 if (!HandleOverflow(Info, E, Result, E->getType())) 13440 return false; 13441 } 13442 return Success(Result, E); 13443 } 13444 case CK_IntegralToFixedPoint: { 13445 APSInt Src; 13446 if (!EvaluateInteger(SubExpr, Src, Info)) 13447 return false; 13448 13449 bool Overflowed; 13450 APFixedPoint IntResult = APFixedPoint::getFromIntValue( 13451 Src, Info.Ctx.getFixedPointSemantics(DestType), &Overflowed); 13452 13453 if (Overflowed) { 13454 if (Info.checkingForUndefinedBehavior()) 13455 Info.Ctx.getDiagnostics().Report(E->getExprLoc(), 13456 diag::warn_fixedpoint_constant_overflow) 13457 << IntResult.toString() << E->getType(); 13458 if (!HandleOverflow(Info, E, IntResult, E->getType())) 13459 return false; 13460 } 13461 13462 return Success(IntResult, E); 13463 } 13464 case CK_FloatingToFixedPoint: { 13465 APFloat Src(0.0); 13466 if (!EvaluateFloat(SubExpr, Src, Info)) 13467 return false; 13468 13469 bool Overflowed; 13470 APFixedPoint Result = APFixedPoint::getFromFloatValue( 13471 Src, Info.Ctx.getFixedPointSemantics(DestType), &Overflowed); 13472 13473 if (Overflowed) { 13474 if (Info.checkingForUndefinedBehavior()) 13475 Info.Ctx.getDiagnostics().Report(E->getExprLoc(), 13476 diag::warn_fixedpoint_constant_overflow) 13477 << Result.toString() << E->getType(); 13478 if (!HandleOverflow(Info, E, Result, E->getType())) 13479 return false; 13480 } 13481 13482 return Success(Result, E); 13483 } 13484 case CK_NoOp: 13485 case CK_LValueToRValue: 13486 return ExprEvaluatorBaseTy::VisitCastExpr(E); 13487 default: 13488 return Error(E); 13489 } 13490 } 13491 13492 bool FixedPointExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 13493 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) 13494 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 13495 13496 const Expr *LHS = E->getLHS(); 13497 const Expr *RHS = E->getRHS(); 13498 FixedPointSemantics ResultFXSema = 13499 Info.Ctx.getFixedPointSemantics(E->getType()); 13500 13501 APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHS->getType())); 13502 if (!EvaluateFixedPointOrInteger(LHS, LHSFX, Info)) 13503 return false; 13504 APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHS->getType())); 13505 if (!EvaluateFixedPointOrInteger(RHS, RHSFX, Info)) 13506 return false; 13507 13508 bool OpOverflow = false, ConversionOverflow = false; 13509 APFixedPoint Result(LHSFX.getSemantics()); 13510 switch (E->getOpcode()) { 13511 case BO_Add: { 13512 Result = LHSFX.add(RHSFX, &OpOverflow) 13513 .convert(ResultFXSema, &ConversionOverflow); 13514 break; 13515 } 13516 case BO_Sub: { 13517 Result = LHSFX.sub(RHSFX, &OpOverflow) 13518 .convert(ResultFXSema, &ConversionOverflow); 13519 break; 13520 } 13521 case BO_Mul: { 13522 Result = LHSFX.mul(RHSFX, &OpOverflow) 13523 .convert(ResultFXSema, &ConversionOverflow); 13524 break; 13525 } 13526 case BO_Div: { 13527 if (RHSFX.getValue() == 0) { 13528 Info.FFDiag(E, diag::note_expr_divide_by_zero); 13529 return false; 13530 } 13531 Result = LHSFX.div(RHSFX, &OpOverflow) 13532 .convert(ResultFXSema, &ConversionOverflow); 13533 break; 13534 } 13535 case BO_Shl: 13536 case BO_Shr: { 13537 FixedPointSemantics LHSSema = LHSFX.getSemantics(); 13538 llvm::APSInt RHSVal = RHSFX.getValue(); 13539 13540 unsigned ShiftBW = 13541 LHSSema.getWidth() - (unsigned)LHSSema.hasUnsignedPadding(); 13542 unsigned Amt = RHSVal.getLimitedValue(ShiftBW - 1); 13543 // Embedded-C 4.1.6.2.2: 13544 // The right operand must be nonnegative and less than the total number 13545 // of (nonpadding) bits of the fixed-point operand ... 13546 if (RHSVal.isNegative()) 13547 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHSVal; 13548 else if (Amt != RHSVal) 13549 Info.CCEDiag(E, diag::note_constexpr_large_shift) 13550 << RHSVal << E->getType() << ShiftBW; 13551 13552 if (E->getOpcode() == BO_Shl) 13553 Result = LHSFX.shl(Amt, &OpOverflow); 13554 else 13555 Result = LHSFX.shr(Amt, &OpOverflow); 13556 break; 13557 } 13558 default: 13559 return false; 13560 } 13561 if (OpOverflow || ConversionOverflow) { 13562 if (Info.checkingForUndefinedBehavior()) 13563 Info.Ctx.getDiagnostics().Report(E->getExprLoc(), 13564 diag::warn_fixedpoint_constant_overflow) 13565 << Result.toString() << E->getType(); 13566 if (!HandleOverflow(Info, E, Result, E->getType())) 13567 return false; 13568 } 13569 return Success(Result, E); 13570 } 13571 13572 //===----------------------------------------------------------------------===// 13573 // Float Evaluation 13574 //===----------------------------------------------------------------------===// 13575 13576 namespace { 13577 class FloatExprEvaluator 13578 : public ExprEvaluatorBase<FloatExprEvaluator> { 13579 APFloat &Result; 13580 public: 13581 FloatExprEvaluator(EvalInfo &info, APFloat &result) 13582 : ExprEvaluatorBaseTy(info), Result(result) {} 13583 13584 bool Success(const APValue &V, const Expr *e) { 13585 Result = V.getFloat(); 13586 return true; 13587 } 13588 13589 bool ZeroInitialization(const Expr *E) { 13590 Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType())); 13591 return true; 13592 } 13593 13594 bool VisitCallExpr(const CallExpr *E); 13595 13596 bool VisitUnaryOperator(const UnaryOperator *E); 13597 bool VisitBinaryOperator(const BinaryOperator *E); 13598 bool VisitFloatingLiteral(const FloatingLiteral *E); 13599 bool VisitCastExpr(const CastExpr *E); 13600 13601 bool VisitUnaryReal(const UnaryOperator *E); 13602 bool VisitUnaryImag(const UnaryOperator *E); 13603 13604 // FIXME: Missing: array subscript of vector, member of vector 13605 }; 13606 } // end anonymous namespace 13607 13608 static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) { 13609 assert(!E->isValueDependent()); 13610 assert(E->isPRValue() && E->getType()->isRealFloatingType()); 13611 return FloatExprEvaluator(Info, Result).Visit(E); 13612 } 13613 13614 static bool TryEvaluateBuiltinNaN(const ASTContext &Context, 13615 QualType ResultTy, 13616 const Expr *Arg, 13617 bool SNaN, 13618 llvm::APFloat &Result) { 13619 const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts()); 13620 if (!S) return false; 13621 13622 const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy); 13623 13624 llvm::APInt fill; 13625 13626 // Treat empty strings as if they were zero. 13627 if (S->getString().empty()) 13628 fill = llvm::APInt(32, 0); 13629 else if (S->getString().getAsInteger(0, fill)) 13630 return false; 13631 13632 if (Context.getTargetInfo().isNan2008()) { 13633 if (SNaN) 13634 Result = llvm::APFloat::getSNaN(Sem, false, &fill); 13635 else 13636 Result = llvm::APFloat::getQNaN(Sem, false, &fill); 13637 } else { 13638 // Prior to IEEE 754-2008, architectures were allowed to choose whether 13639 // the first bit of their significand was set for qNaN or sNaN. MIPS chose 13640 // a different encoding to what became a standard in 2008, and for pre- 13641 // 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as 13642 // sNaN. This is now known as "legacy NaN" encoding. 13643 if (SNaN) 13644 Result = llvm::APFloat::getQNaN(Sem, false, &fill); 13645 else 13646 Result = llvm::APFloat::getSNaN(Sem, false, &fill); 13647 } 13648 13649 return true; 13650 } 13651 13652 bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) { 13653 switch (E->getBuiltinCallee()) { 13654 default: 13655 return ExprEvaluatorBaseTy::VisitCallExpr(E); 13656 13657 case Builtin::BI__builtin_huge_val: 13658 case Builtin::BI__builtin_huge_valf: 13659 case Builtin::BI__builtin_huge_vall: 13660 case Builtin::BI__builtin_huge_valf128: 13661 case Builtin::BI__builtin_inf: 13662 case Builtin::BI__builtin_inff: 13663 case Builtin::BI__builtin_infl: 13664 case Builtin::BI__builtin_inff128: { 13665 const llvm::fltSemantics &Sem = 13666 Info.Ctx.getFloatTypeSemantics(E->getType()); 13667 Result = llvm::APFloat::getInf(Sem); 13668 return true; 13669 } 13670 13671 case Builtin::BI__builtin_nans: 13672 case Builtin::BI__builtin_nansf: 13673 case Builtin::BI__builtin_nansl: 13674 case Builtin::BI__builtin_nansf128: 13675 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), 13676 true, Result)) 13677 return Error(E); 13678 return true; 13679 13680 case Builtin::BI__builtin_nan: 13681 case Builtin::BI__builtin_nanf: 13682 case Builtin::BI__builtin_nanl: 13683 case Builtin::BI__builtin_nanf128: 13684 // If this is __builtin_nan() turn this into a nan, otherwise we 13685 // can't constant fold it. 13686 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), 13687 false, Result)) 13688 return Error(E); 13689 return true; 13690 13691 case Builtin::BI__builtin_fabs: 13692 case Builtin::BI__builtin_fabsf: 13693 case Builtin::BI__builtin_fabsl: 13694 case Builtin::BI__builtin_fabsf128: 13695 // The C standard says "fabs raises no floating-point exceptions, 13696 // even if x is a signaling NaN. The returned value is independent of 13697 // the current rounding direction mode." Therefore constant folding can 13698 // proceed without regard to the floating point settings. 13699 // Reference, WG14 N2478 F.10.4.3 13700 if (!EvaluateFloat(E->getArg(0), Result, Info)) 13701 return false; 13702 13703 if (Result.isNegative()) 13704 Result.changeSign(); 13705 return true; 13706 13707 case Builtin::BI__arithmetic_fence: 13708 return EvaluateFloat(E->getArg(0), Result, Info); 13709 13710 // FIXME: Builtin::BI__builtin_powi 13711 // FIXME: Builtin::BI__builtin_powif 13712 // FIXME: Builtin::BI__builtin_powil 13713 13714 case Builtin::BI__builtin_copysign: 13715 case Builtin::BI__builtin_copysignf: 13716 case Builtin::BI__builtin_copysignl: 13717 case Builtin::BI__builtin_copysignf128: { 13718 APFloat RHS(0.); 13719 if (!EvaluateFloat(E->getArg(0), Result, Info) || 13720 !EvaluateFloat(E->getArg(1), RHS, Info)) 13721 return false; 13722 Result.copySign(RHS); 13723 return true; 13724 } 13725 } 13726 } 13727 13728 bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 13729 if (E->getSubExpr()->getType()->isAnyComplexType()) { 13730 ComplexValue CV; 13731 if (!EvaluateComplex(E->getSubExpr(), CV, Info)) 13732 return false; 13733 Result = CV.FloatReal; 13734 return true; 13735 } 13736 13737 return Visit(E->getSubExpr()); 13738 } 13739 13740 bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 13741 if (E->getSubExpr()->getType()->isAnyComplexType()) { 13742 ComplexValue CV; 13743 if (!EvaluateComplex(E->getSubExpr(), CV, Info)) 13744 return false; 13745 Result = CV.FloatImag; 13746 return true; 13747 } 13748 13749 VisitIgnoredValue(E->getSubExpr()); 13750 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType()); 13751 Result = llvm::APFloat::getZero(Sem); 13752 return true; 13753 } 13754 13755 bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 13756 switch (E->getOpcode()) { 13757 default: return Error(E); 13758 case UO_Plus: 13759 return EvaluateFloat(E->getSubExpr(), Result, Info); 13760 case UO_Minus: 13761 // In C standard, WG14 N2478 F.3 p4 13762 // "the unary - raises no floating point exceptions, 13763 // even if the operand is signalling." 13764 if (!EvaluateFloat(E->getSubExpr(), Result, Info)) 13765 return false; 13766 Result.changeSign(); 13767 return true; 13768 } 13769 } 13770 13771 bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 13772 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) 13773 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 13774 13775 APFloat RHS(0.0); 13776 bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info); 13777 if (!LHSOK && !Info.noteFailure()) 13778 return false; 13779 return EvaluateFloat(E->getRHS(), RHS, Info) && LHSOK && 13780 handleFloatFloatBinOp(Info, E, Result, E->getOpcode(), RHS); 13781 } 13782 13783 bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) { 13784 Result = E->getValue(); 13785 return true; 13786 } 13787 13788 bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) { 13789 const Expr* SubExpr = E->getSubExpr(); 13790 13791 switch (E->getCastKind()) { 13792 default: 13793 return ExprEvaluatorBaseTy::VisitCastExpr(E); 13794 13795 case CK_IntegralToFloating: { 13796 APSInt IntResult; 13797 const FPOptions FPO = E->getFPFeaturesInEffect( 13798 Info.Ctx.getLangOpts()); 13799 return EvaluateInteger(SubExpr, IntResult, Info) && 13800 HandleIntToFloatCast(Info, E, FPO, SubExpr->getType(), 13801 IntResult, E->getType(), Result); 13802 } 13803 13804 case CK_FixedPointToFloating: { 13805 APFixedPoint FixResult(Info.Ctx.getFixedPointSemantics(SubExpr->getType())); 13806 if (!EvaluateFixedPoint(SubExpr, FixResult, Info)) 13807 return false; 13808 Result = 13809 FixResult.convertToFloat(Info.Ctx.getFloatTypeSemantics(E->getType())); 13810 return true; 13811 } 13812 13813 case CK_FloatingCast: { 13814 if (!Visit(SubExpr)) 13815 return false; 13816 return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(), 13817 Result); 13818 } 13819 13820 case CK_FloatingComplexToReal: { 13821 ComplexValue V; 13822 if (!EvaluateComplex(SubExpr, V, Info)) 13823 return false; 13824 Result = V.getComplexFloatReal(); 13825 return true; 13826 } 13827 } 13828 } 13829 13830 //===----------------------------------------------------------------------===// 13831 // Complex Evaluation (for float and integer) 13832 //===----------------------------------------------------------------------===// 13833 13834 namespace { 13835 class ComplexExprEvaluator 13836 : public ExprEvaluatorBase<ComplexExprEvaluator> { 13837 ComplexValue &Result; 13838 13839 public: 13840 ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result) 13841 : ExprEvaluatorBaseTy(info), Result(Result) {} 13842 13843 bool Success(const APValue &V, const Expr *e) { 13844 Result.setFrom(V); 13845 return true; 13846 } 13847 13848 bool ZeroInitialization(const Expr *E); 13849 13850 //===--------------------------------------------------------------------===// 13851 // Visitor Methods 13852 //===--------------------------------------------------------------------===// 13853 13854 bool VisitImaginaryLiteral(const ImaginaryLiteral *E); 13855 bool VisitCastExpr(const CastExpr *E); 13856 bool VisitBinaryOperator(const BinaryOperator *E); 13857 bool VisitUnaryOperator(const UnaryOperator *E); 13858 bool VisitInitListExpr(const InitListExpr *E); 13859 bool VisitCallExpr(const CallExpr *E); 13860 }; 13861 } // end anonymous namespace 13862 13863 static bool EvaluateComplex(const Expr *E, ComplexValue &Result, 13864 EvalInfo &Info) { 13865 assert(!E->isValueDependent()); 13866 assert(E->isPRValue() && E->getType()->isAnyComplexType()); 13867 return ComplexExprEvaluator(Info, Result).Visit(E); 13868 } 13869 13870 bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) { 13871 QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType(); 13872 if (ElemTy->isRealFloatingType()) { 13873 Result.makeComplexFloat(); 13874 APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy)); 13875 Result.FloatReal = Zero; 13876 Result.FloatImag = Zero; 13877 } else { 13878 Result.makeComplexInt(); 13879 APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy); 13880 Result.IntReal = Zero; 13881 Result.IntImag = Zero; 13882 } 13883 return true; 13884 } 13885 13886 bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) { 13887 const Expr* SubExpr = E->getSubExpr(); 13888 13889 if (SubExpr->getType()->isRealFloatingType()) { 13890 Result.makeComplexFloat(); 13891 APFloat &Imag = Result.FloatImag; 13892 if (!EvaluateFloat(SubExpr, Imag, Info)) 13893 return false; 13894 13895 Result.FloatReal = APFloat(Imag.getSemantics()); 13896 return true; 13897 } else { 13898 assert(SubExpr->getType()->isIntegerType() && 13899 "Unexpected imaginary literal."); 13900 13901 Result.makeComplexInt(); 13902 APSInt &Imag = Result.IntImag; 13903 if (!EvaluateInteger(SubExpr, Imag, Info)) 13904 return false; 13905 13906 Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned()); 13907 return true; 13908 } 13909 } 13910 13911 bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) { 13912 13913 switch (E->getCastKind()) { 13914 case CK_BitCast: 13915 case CK_BaseToDerived: 13916 case CK_DerivedToBase: 13917 case CK_UncheckedDerivedToBase: 13918 case CK_Dynamic: 13919 case CK_ToUnion: 13920 case CK_ArrayToPointerDecay: 13921 case CK_FunctionToPointerDecay: 13922 case CK_NullToPointer: 13923 case CK_NullToMemberPointer: 13924 case CK_BaseToDerivedMemberPointer: 13925 case CK_DerivedToBaseMemberPointer: 13926 case CK_MemberPointerToBoolean: 13927 case CK_ReinterpretMemberPointer: 13928 case CK_ConstructorConversion: 13929 case CK_IntegralToPointer: 13930 case CK_PointerToIntegral: 13931 case CK_PointerToBoolean: 13932 case CK_ToVoid: 13933 case CK_VectorSplat: 13934 case CK_IntegralCast: 13935 case CK_BooleanToSignedIntegral: 13936 case CK_IntegralToBoolean: 13937 case CK_IntegralToFloating: 13938 case CK_FloatingToIntegral: 13939 case CK_FloatingToBoolean: 13940 case CK_FloatingCast: 13941 case CK_CPointerToObjCPointerCast: 13942 case CK_BlockPointerToObjCPointerCast: 13943 case CK_AnyPointerToBlockPointerCast: 13944 case CK_ObjCObjectLValueCast: 13945 case CK_FloatingComplexToReal: 13946 case CK_FloatingComplexToBoolean: 13947 case CK_IntegralComplexToReal: 13948 case CK_IntegralComplexToBoolean: 13949 case CK_ARCProduceObject: 13950 case CK_ARCConsumeObject: 13951 case CK_ARCReclaimReturnedObject: 13952 case CK_ARCExtendBlockObject: 13953 case CK_CopyAndAutoreleaseBlockObject: 13954 case CK_BuiltinFnToFnPtr: 13955 case CK_ZeroToOCLOpaqueType: 13956 case CK_NonAtomicToAtomic: 13957 case CK_AddressSpaceConversion: 13958 case CK_IntToOCLSampler: 13959 case CK_FloatingToFixedPoint: 13960 case CK_FixedPointToFloating: 13961 case CK_FixedPointCast: 13962 case CK_FixedPointToBoolean: 13963 case CK_FixedPointToIntegral: 13964 case CK_IntegralToFixedPoint: 13965 case CK_MatrixCast: 13966 llvm_unreachable("invalid cast kind for complex value"); 13967 13968 case CK_LValueToRValue: 13969 case CK_AtomicToNonAtomic: 13970 case CK_NoOp: 13971 case CK_LValueToRValueBitCast: 13972 return ExprEvaluatorBaseTy::VisitCastExpr(E); 13973 13974 case CK_Dependent: 13975 case CK_LValueBitCast: 13976 case CK_UserDefinedConversion: 13977 return Error(E); 13978 13979 case CK_FloatingRealToComplex: { 13980 APFloat &Real = Result.FloatReal; 13981 if (!EvaluateFloat(E->getSubExpr(), Real, Info)) 13982 return false; 13983 13984 Result.makeComplexFloat(); 13985 Result.FloatImag = APFloat(Real.getSemantics()); 13986 return true; 13987 } 13988 13989 case CK_FloatingComplexCast: { 13990 if (!Visit(E->getSubExpr())) 13991 return false; 13992 13993 QualType To = E->getType()->castAs<ComplexType>()->getElementType(); 13994 QualType From 13995 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType(); 13996 13997 return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) && 13998 HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag); 13999 } 14000 14001 case CK_FloatingComplexToIntegralComplex: { 14002 if (!Visit(E->getSubExpr())) 14003 return false; 14004 14005 QualType To = E->getType()->castAs<ComplexType>()->getElementType(); 14006 QualType From 14007 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType(); 14008 Result.makeComplexInt(); 14009 return HandleFloatToIntCast(Info, E, From, Result.FloatReal, 14010 To, Result.IntReal) && 14011 HandleFloatToIntCast(Info, E, From, Result.FloatImag, 14012 To, Result.IntImag); 14013 } 14014 14015 case CK_IntegralRealToComplex: { 14016 APSInt &Real = Result.IntReal; 14017 if (!EvaluateInteger(E->getSubExpr(), Real, Info)) 14018 return false; 14019 14020 Result.makeComplexInt(); 14021 Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned()); 14022 return true; 14023 } 14024 14025 case CK_IntegralComplexCast: { 14026 if (!Visit(E->getSubExpr())) 14027 return false; 14028 14029 QualType To = E->getType()->castAs<ComplexType>()->getElementType(); 14030 QualType From 14031 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType(); 14032 14033 Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal); 14034 Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag); 14035 return true; 14036 } 14037 14038 case CK_IntegralComplexToFloatingComplex: { 14039 if (!Visit(E->getSubExpr())) 14040 return false; 14041 14042 const FPOptions FPO = E->getFPFeaturesInEffect( 14043 Info.Ctx.getLangOpts()); 14044 QualType To = E->getType()->castAs<ComplexType>()->getElementType(); 14045 QualType From 14046 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType(); 14047 Result.makeComplexFloat(); 14048 return HandleIntToFloatCast(Info, E, FPO, From, Result.IntReal, 14049 To, Result.FloatReal) && 14050 HandleIntToFloatCast(Info, E, FPO, From, Result.IntImag, 14051 To, Result.FloatImag); 14052 } 14053 } 14054 14055 llvm_unreachable("unknown cast resulting in complex value"); 14056 } 14057 14058 bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 14059 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) 14060 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 14061 14062 // Track whether the LHS or RHS is real at the type system level. When this is 14063 // the case we can simplify our evaluation strategy. 14064 bool LHSReal = false, RHSReal = false; 14065 14066 bool LHSOK; 14067 if (E->getLHS()->getType()->isRealFloatingType()) { 14068 LHSReal = true; 14069 APFloat &Real = Result.FloatReal; 14070 LHSOK = EvaluateFloat(E->getLHS(), Real, Info); 14071 if (LHSOK) { 14072 Result.makeComplexFloat(); 14073 Result.FloatImag = APFloat(Real.getSemantics()); 14074 } 14075 } else { 14076 LHSOK = Visit(E->getLHS()); 14077 } 14078 if (!LHSOK && !Info.noteFailure()) 14079 return false; 14080 14081 ComplexValue RHS; 14082 if (E->getRHS()->getType()->isRealFloatingType()) { 14083 RHSReal = true; 14084 APFloat &Real = RHS.FloatReal; 14085 if (!EvaluateFloat(E->getRHS(), Real, Info) || !LHSOK) 14086 return false; 14087 RHS.makeComplexFloat(); 14088 RHS.FloatImag = APFloat(Real.getSemantics()); 14089 } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) 14090 return false; 14091 14092 assert(!(LHSReal && RHSReal) && 14093 "Cannot have both operands of a complex operation be real."); 14094 switch (E->getOpcode()) { 14095 default: return Error(E); 14096 case BO_Add: 14097 if (Result.isComplexFloat()) { 14098 Result.getComplexFloatReal().add(RHS.getComplexFloatReal(), 14099 APFloat::rmNearestTiesToEven); 14100 if (LHSReal) 14101 Result.getComplexFloatImag() = RHS.getComplexFloatImag(); 14102 else if (!RHSReal) 14103 Result.getComplexFloatImag().add(RHS.getComplexFloatImag(), 14104 APFloat::rmNearestTiesToEven); 14105 } else { 14106 Result.getComplexIntReal() += RHS.getComplexIntReal(); 14107 Result.getComplexIntImag() += RHS.getComplexIntImag(); 14108 } 14109 break; 14110 case BO_Sub: 14111 if (Result.isComplexFloat()) { 14112 Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(), 14113 APFloat::rmNearestTiesToEven); 14114 if (LHSReal) { 14115 Result.getComplexFloatImag() = RHS.getComplexFloatImag(); 14116 Result.getComplexFloatImag().changeSign(); 14117 } else if (!RHSReal) { 14118 Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(), 14119 APFloat::rmNearestTiesToEven); 14120 } 14121 } else { 14122 Result.getComplexIntReal() -= RHS.getComplexIntReal(); 14123 Result.getComplexIntImag() -= RHS.getComplexIntImag(); 14124 } 14125 break; 14126 case BO_Mul: 14127 if (Result.isComplexFloat()) { 14128 // This is an implementation of complex multiplication according to the 14129 // constraints laid out in C11 Annex G. The implementation uses the 14130 // following naming scheme: 14131 // (a + ib) * (c + id) 14132 ComplexValue LHS = Result; 14133 APFloat &A = LHS.getComplexFloatReal(); 14134 APFloat &B = LHS.getComplexFloatImag(); 14135 APFloat &C = RHS.getComplexFloatReal(); 14136 APFloat &D = RHS.getComplexFloatImag(); 14137 APFloat &ResR = Result.getComplexFloatReal(); 14138 APFloat &ResI = Result.getComplexFloatImag(); 14139 if (LHSReal) { 14140 assert(!RHSReal && "Cannot have two real operands for a complex op!"); 14141 ResR = A * C; 14142 ResI = A * D; 14143 } else if (RHSReal) { 14144 ResR = C * A; 14145 ResI = C * B; 14146 } else { 14147 // In the fully general case, we need to handle NaNs and infinities 14148 // robustly. 14149 APFloat AC = A * C; 14150 APFloat BD = B * D; 14151 APFloat AD = A * D; 14152 APFloat BC = B * C; 14153 ResR = AC - BD; 14154 ResI = AD + BC; 14155 if (ResR.isNaN() && ResI.isNaN()) { 14156 bool Recalc = false; 14157 if (A.isInfinity() || B.isInfinity()) { 14158 A = APFloat::copySign( 14159 APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A); 14160 B = APFloat::copySign( 14161 APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B); 14162 if (C.isNaN()) 14163 C = APFloat::copySign(APFloat(C.getSemantics()), C); 14164 if (D.isNaN()) 14165 D = APFloat::copySign(APFloat(D.getSemantics()), D); 14166 Recalc = true; 14167 } 14168 if (C.isInfinity() || D.isInfinity()) { 14169 C = APFloat::copySign( 14170 APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C); 14171 D = APFloat::copySign( 14172 APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D); 14173 if (A.isNaN()) 14174 A = APFloat::copySign(APFloat(A.getSemantics()), A); 14175 if (B.isNaN()) 14176 B = APFloat::copySign(APFloat(B.getSemantics()), B); 14177 Recalc = true; 14178 } 14179 if (!Recalc && (AC.isInfinity() || BD.isInfinity() || 14180 AD.isInfinity() || BC.isInfinity())) { 14181 if (A.isNaN()) 14182 A = APFloat::copySign(APFloat(A.getSemantics()), A); 14183 if (B.isNaN()) 14184 B = APFloat::copySign(APFloat(B.getSemantics()), B); 14185 if (C.isNaN()) 14186 C = APFloat::copySign(APFloat(C.getSemantics()), C); 14187 if (D.isNaN()) 14188 D = APFloat::copySign(APFloat(D.getSemantics()), D); 14189 Recalc = true; 14190 } 14191 if (Recalc) { 14192 ResR = APFloat::getInf(A.getSemantics()) * (A * C - B * D); 14193 ResI = APFloat::getInf(A.getSemantics()) * (A * D + B * C); 14194 } 14195 } 14196 } 14197 } else { 14198 ComplexValue LHS = Result; 14199 Result.getComplexIntReal() = 14200 (LHS.getComplexIntReal() * RHS.getComplexIntReal() - 14201 LHS.getComplexIntImag() * RHS.getComplexIntImag()); 14202 Result.getComplexIntImag() = 14203 (LHS.getComplexIntReal() * RHS.getComplexIntImag() + 14204 LHS.getComplexIntImag() * RHS.getComplexIntReal()); 14205 } 14206 break; 14207 case BO_Div: 14208 if (Result.isComplexFloat()) { 14209 // This is an implementation of complex division according to the 14210 // constraints laid out in C11 Annex G. The implementation uses the 14211 // following naming scheme: 14212 // (a + ib) / (c + id) 14213 ComplexValue LHS = Result; 14214 APFloat &A = LHS.getComplexFloatReal(); 14215 APFloat &B = LHS.getComplexFloatImag(); 14216 APFloat &C = RHS.getComplexFloatReal(); 14217 APFloat &D = RHS.getComplexFloatImag(); 14218 APFloat &ResR = Result.getComplexFloatReal(); 14219 APFloat &ResI = Result.getComplexFloatImag(); 14220 if (RHSReal) { 14221 ResR = A / C; 14222 ResI = B / C; 14223 } else { 14224 if (LHSReal) { 14225 // No real optimizations we can do here, stub out with zero. 14226 B = APFloat::getZero(A.getSemantics()); 14227 } 14228 int DenomLogB = 0; 14229 APFloat MaxCD = maxnum(abs(C), abs(D)); 14230 if (MaxCD.isFinite()) { 14231 DenomLogB = ilogb(MaxCD); 14232 C = scalbn(C, -DenomLogB, APFloat::rmNearestTiesToEven); 14233 D = scalbn(D, -DenomLogB, APFloat::rmNearestTiesToEven); 14234 } 14235 APFloat Denom = C * C + D * D; 14236 ResR = scalbn((A * C + B * D) / Denom, -DenomLogB, 14237 APFloat::rmNearestTiesToEven); 14238 ResI = scalbn((B * C - A * D) / Denom, -DenomLogB, 14239 APFloat::rmNearestTiesToEven); 14240 if (ResR.isNaN() && ResI.isNaN()) { 14241 if (Denom.isPosZero() && (!A.isNaN() || !B.isNaN())) { 14242 ResR = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * A; 14243 ResI = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * B; 14244 } else if ((A.isInfinity() || B.isInfinity()) && C.isFinite() && 14245 D.isFinite()) { 14246 A = APFloat::copySign( 14247 APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A); 14248 B = APFloat::copySign( 14249 APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B); 14250 ResR = APFloat::getInf(ResR.getSemantics()) * (A * C + B * D); 14251 ResI = APFloat::getInf(ResI.getSemantics()) * (B * C - A * D); 14252 } else if (MaxCD.isInfinity() && A.isFinite() && B.isFinite()) { 14253 C = APFloat::copySign( 14254 APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C); 14255 D = APFloat::copySign( 14256 APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D); 14257 ResR = APFloat::getZero(ResR.getSemantics()) * (A * C + B * D); 14258 ResI = APFloat::getZero(ResI.getSemantics()) * (B * C - A * D); 14259 } 14260 } 14261 } 14262 } else { 14263 if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0) 14264 return Error(E, diag::note_expr_divide_by_zero); 14265 14266 ComplexValue LHS = Result; 14267 APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() + 14268 RHS.getComplexIntImag() * RHS.getComplexIntImag(); 14269 Result.getComplexIntReal() = 14270 (LHS.getComplexIntReal() * RHS.getComplexIntReal() + 14271 LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den; 14272 Result.getComplexIntImag() = 14273 (LHS.getComplexIntImag() * RHS.getComplexIntReal() - 14274 LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den; 14275 } 14276 break; 14277 } 14278 14279 return true; 14280 } 14281 14282 bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 14283 // Get the operand value into 'Result'. 14284 if (!Visit(E->getSubExpr())) 14285 return false; 14286 14287 switch (E->getOpcode()) { 14288 default: 14289 return Error(E); 14290 case UO_Extension: 14291 return true; 14292 case UO_Plus: 14293 // The result is always just the subexpr. 14294 return true; 14295 case UO_Minus: 14296 if (Result.isComplexFloat()) { 14297 Result.getComplexFloatReal().changeSign(); 14298 Result.getComplexFloatImag().changeSign(); 14299 } 14300 else { 14301 Result.getComplexIntReal() = -Result.getComplexIntReal(); 14302 Result.getComplexIntImag() = -Result.getComplexIntImag(); 14303 } 14304 return true; 14305 case UO_Not: 14306 if (Result.isComplexFloat()) 14307 Result.getComplexFloatImag().changeSign(); 14308 else 14309 Result.getComplexIntImag() = -Result.getComplexIntImag(); 14310 return true; 14311 } 14312 } 14313 14314 bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 14315 if (E->getNumInits() == 2) { 14316 if (E->getType()->isComplexType()) { 14317 Result.makeComplexFloat(); 14318 if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info)) 14319 return false; 14320 if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info)) 14321 return false; 14322 } else { 14323 Result.makeComplexInt(); 14324 if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info)) 14325 return false; 14326 if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info)) 14327 return false; 14328 } 14329 return true; 14330 } 14331 return ExprEvaluatorBaseTy::VisitInitListExpr(E); 14332 } 14333 14334 bool ComplexExprEvaluator::VisitCallExpr(const CallExpr *E) { 14335 switch (E->getBuiltinCallee()) { 14336 case Builtin::BI__builtin_complex: 14337 Result.makeComplexFloat(); 14338 if (!EvaluateFloat(E->getArg(0), Result.FloatReal, Info)) 14339 return false; 14340 if (!EvaluateFloat(E->getArg(1), Result.FloatImag, Info)) 14341 return false; 14342 return true; 14343 14344 default: 14345 break; 14346 } 14347 14348 return ExprEvaluatorBaseTy::VisitCallExpr(E); 14349 } 14350 14351 //===----------------------------------------------------------------------===// 14352 // Atomic expression evaluation, essentially just handling the NonAtomicToAtomic 14353 // implicit conversion. 14354 //===----------------------------------------------------------------------===// 14355 14356 namespace { 14357 class AtomicExprEvaluator : 14358 public ExprEvaluatorBase<AtomicExprEvaluator> { 14359 const LValue *This; 14360 APValue &Result; 14361 public: 14362 AtomicExprEvaluator(EvalInfo &Info, const LValue *This, APValue &Result) 14363 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {} 14364 14365 bool Success(const APValue &V, const Expr *E) { 14366 Result = V; 14367 return true; 14368 } 14369 14370 bool ZeroInitialization(const Expr *E) { 14371 ImplicitValueInitExpr VIE( 14372 E->getType()->castAs<AtomicType>()->getValueType()); 14373 // For atomic-qualified class (and array) types in C++, initialize the 14374 // _Atomic-wrapped subobject directly, in-place. 14375 return This ? EvaluateInPlace(Result, Info, *This, &VIE) 14376 : Evaluate(Result, Info, &VIE); 14377 } 14378 14379 bool VisitCastExpr(const CastExpr *E) { 14380 switch (E->getCastKind()) { 14381 default: 14382 return ExprEvaluatorBaseTy::VisitCastExpr(E); 14383 case CK_NonAtomicToAtomic: 14384 return This ? EvaluateInPlace(Result, Info, *This, E->getSubExpr()) 14385 : Evaluate(Result, Info, E->getSubExpr()); 14386 } 14387 } 14388 }; 14389 } // end anonymous namespace 14390 14391 static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result, 14392 EvalInfo &Info) { 14393 assert(!E->isValueDependent()); 14394 assert(E->isPRValue() && E->getType()->isAtomicType()); 14395 return AtomicExprEvaluator(Info, This, Result).Visit(E); 14396 } 14397 14398 //===----------------------------------------------------------------------===// 14399 // Void expression evaluation, primarily for a cast to void on the LHS of a 14400 // comma operator 14401 //===----------------------------------------------------------------------===// 14402 14403 namespace { 14404 class VoidExprEvaluator 14405 : public ExprEvaluatorBase<VoidExprEvaluator> { 14406 public: 14407 VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {} 14408 14409 bool Success(const APValue &V, const Expr *e) { return true; } 14410 14411 bool ZeroInitialization(const Expr *E) { return true; } 14412 14413 bool VisitCastExpr(const CastExpr *E) { 14414 switch (E->getCastKind()) { 14415 default: 14416 return ExprEvaluatorBaseTy::VisitCastExpr(E); 14417 case CK_ToVoid: 14418 VisitIgnoredValue(E->getSubExpr()); 14419 return true; 14420 } 14421 } 14422 14423 bool VisitCallExpr(const CallExpr *E) { 14424 switch (E->getBuiltinCallee()) { 14425 case Builtin::BI__assume: 14426 case Builtin::BI__builtin_assume: 14427 // The argument is not evaluated! 14428 return true; 14429 14430 case Builtin::BI__builtin_operator_delete: 14431 return HandleOperatorDeleteCall(Info, E); 14432 14433 default: 14434 break; 14435 } 14436 14437 return ExprEvaluatorBaseTy::VisitCallExpr(E); 14438 } 14439 14440 bool VisitCXXDeleteExpr(const CXXDeleteExpr *E); 14441 }; 14442 } // end anonymous namespace 14443 14444 bool VoidExprEvaluator::VisitCXXDeleteExpr(const CXXDeleteExpr *E) { 14445 // We cannot speculatively evaluate a delete expression. 14446 if (Info.SpeculativeEvaluationDepth) 14447 return false; 14448 14449 FunctionDecl *OperatorDelete = E->getOperatorDelete(); 14450 if (!OperatorDelete->isReplaceableGlobalAllocationFunction()) { 14451 Info.FFDiag(E, diag::note_constexpr_new_non_replaceable) 14452 << isa<CXXMethodDecl>(OperatorDelete) << OperatorDelete; 14453 return false; 14454 } 14455 14456 const Expr *Arg = E->getArgument(); 14457 14458 LValue Pointer; 14459 if (!EvaluatePointer(Arg, Pointer, Info)) 14460 return false; 14461 if (Pointer.Designator.Invalid) 14462 return false; 14463 14464 // Deleting a null pointer has no effect. 14465 if (Pointer.isNullPointer()) { 14466 // This is the only case where we need to produce an extension warning: 14467 // the only other way we can succeed is if we find a dynamic allocation, 14468 // and we will have warned when we allocated it in that case. 14469 if (!Info.getLangOpts().CPlusPlus20) 14470 Info.CCEDiag(E, diag::note_constexpr_new); 14471 return true; 14472 } 14473 14474 Optional<DynAlloc *> Alloc = CheckDeleteKind( 14475 Info, E, Pointer, E->isArrayForm() ? DynAlloc::ArrayNew : DynAlloc::New); 14476 if (!Alloc) 14477 return false; 14478 QualType AllocType = Pointer.Base.getDynamicAllocType(); 14479 14480 // For the non-array case, the designator must be empty if the static type 14481 // does not have a virtual destructor. 14482 if (!E->isArrayForm() && Pointer.Designator.Entries.size() != 0 && 14483 !hasVirtualDestructor(Arg->getType()->getPointeeType())) { 14484 Info.FFDiag(E, diag::note_constexpr_delete_base_nonvirt_dtor) 14485 << Arg->getType()->getPointeeType() << AllocType; 14486 return false; 14487 } 14488 14489 // For a class type with a virtual destructor, the selected operator delete 14490 // is the one looked up when building the destructor. 14491 if (!E->isArrayForm() && !E->isGlobalDelete()) { 14492 const FunctionDecl *VirtualDelete = getVirtualOperatorDelete(AllocType); 14493 if (VirtualDelete && 14494 !VirtualDelete->isReplaceableGlobalAllocationFunction()) { 14495 Info.FFDiag(E, diag::note_constexpr_new_non_replaceable) 14496 << isa<CXXMethodDecl>(VirtualDelete) << VirtualDelete; 14497 return false; 14498 } 14499 } 14500 14501 if (!HandleDestruction(Info, E->getExprLoc(), Pointer.getLValueBase(), 14502 (*Alloc)->Value, AllocType)) 14503 return false; 14504 14505 if (!Info.HeapAllocs.erase(Pointer.Base.dyn_cast<DynamicAllocLValue>())) { 14506 // The element was already erased. This means the destructor call also 14507 // deleted the object. 14508 // FIXME: This probably results in undefined behavior before we get this 14509 // far, and should be diagnosed elsewhere first. 14510 Info.FFDiag(E, diag::note_constexpr_double_delete); 14511 return false; 14512 } 14513 14514 return true; 14515 } 14516 14517 static bool EvaluateVoid(const Expr *E, EvalInfo &Info) { 14518 assert(!E->isValueDependent()); 14519 assert(E->isPRValue() && E->getType()->isVoidType()); 14520 return VoidExprEvaluator(Info).Visit(E); 14521 } 14522 14523 //===----------------------------------------------------------------------===// 14524 // Top level Expr::EvaluateAsRValue method. 14525 //===----------------------------------------------------------------------===// 14526 14527 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) { 14528 assert(!E->isValueDependent()); 14529 // In C, function designators are not lvalues, but we evaluate them as if they 14530 // are. 14531 QualType T = E->getType(); 14532 if (E->isGLValue() || T->isFunctionType()) { 14533 LValue LV; 14534 if (!EvaluateLValue(E, LV, Info)) 14535 return false; 14536 LV.moveInto(Result); 14537 } else if (T->isVectorType()) { 14538 if (!EvaluateVector(E, Result, Info)) 14539 return false; 14540 } else if (T->isIntegralOrEnumerationType()) { 14541 if (!IntExprEvaluator(Info, Result).Visit(E)) 14542 return false; 14543 } else if (T->hasPointerRepresentation()) { 14544 LValue LV; 14545 if (!EvaluatePointer(E, LV, Info)) 14546 return false; 14547 LV.moveInto(Result); 14548 } else if (T->isRealFloatingType()) { 14549 llvm::APFloat F(0.0); 14550 if (!EvaluateFloat(E, F, Info)) 14551 return false; 14552 Result = APValue(F); 14553 } else if (T->isAnyComplexType()) { 14554 ComplexValue C; 14555 if (!EvaluateComplex(E, C, Info)) 14556 return false; 14557 C.moveInto(Result); 14558 } else if (T->isFixedPointType()) { 14559 if (!FixedPointExprEvaluator(Info, Result).Visit(E)) return false; 14560 } else if (T->isMemberPointerType()) { 14561 MemberPtr P; 14562 if (!EvaluateMemberPointer(E, P, Info)) 14563 return false; 14564 P.moveInto(Result); 14565 return true; 14566 } else if (T->isArrayType()) { 14567 LValue LV; 14568 APValue &Value = 14569 Info.CurrentCall->createTemporary(E, T, ScopeKind::FullExpression, LV); 14570 if (!EvaluateArray(E, LV, Value, Info)) 14571 return false; 14572 Result = Value; 14573 } else if (T->isRecordType()) { 14574 LValue LV; 14575 APValue &Value = 14576 Info.CurrentCall->createTemporary(E, T, ScopeKind::FullExpression, LV); 14577 if (!EvaluateRecord(E, LV, Value, Info)) 14578 return false; 14579 Result = Value; 14580 } else if (T->isVoidType()) { 14581 if (!Info.getLangOpts().CPlusPlus11) 14582 Info.CCEDiag(E, diag::note_constexpr_nonliteral) 14583 << E->getType(); 14584 if (!EvaluateVoid(E, Info)) 14585 return false; 14586 } else if (T->isAtomicType()) { 14587 QualType Unqual = T.getAtomicUnqualifiedType(); 14588 if (Unqual->isArrayType() || Unqual->isRecordType()) { 14589 LValue LV; 14590 APValue &Value = Info.CurrentCall->createTemporary( 14591 E, Unqual, ScopeKind::FullExpression, LV); 14592 if (!EvaluateAtomic(E, &LV, Value, Info)) 14593 return false; 14594 } else { 14595 if (!EvaluateAtomic(E, nullptr, Result, Info)) 14596 return false; 14597 } 14598 } else if (Info.getLangOpts().CPlusPlus11) { 14599 Info.FFDiag(E, diag::note_constexpr_nonliteral) << E->getType(); 14600 return false; 14601 } else { 14602 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 14603 return false; 14604 } 14605 14606 return true; 14607 } 14608 14609 /// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some 14610 /// cases, the in-place evaluation is essential, since later initializers for 14611 /// an object can indirectly refer to subobjects which were initialized earlier. 14612 static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This, 14613 const Expr *E, bool AllowNonLiteralTypes) { 14614 assert(!E->isValueDependent()); 14615 14616 if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, &This)) 14617 return false; 14618 14619 if (E->isPRValue()) { 14620 // Evaluate arrays and record types in-place, so that later initializers can 14621 // refer to earlier-initialized members of the object. 14622 QualType T = E->getType(); 14623 if (T->isArrayType()) 14624 return EvaluateArray(E, This, Result, Info); 14625 else if (T->isRecordType()) 14626 return EvaluateRecord(E, This, Result, Info); 14627 else if (T->isAtomicType()) { 14628 QualType Unqual = T.getAtomicUnqualifiedType(); 14629 if (Unqual->isArrayType() || Unqual->isRecordType()) 14630 return EvaluateAtomic(E, &This, Result, Info); 14631 } 14632 } 14633 14634 // For any other type, in-place evaluation is unimportant. 14635 return Evaluate(Result, Info, E); 14636 } 14637 14638 /// EvaluateAsRValue - Try to evaluate this expression, performing an implicit 14639 /// lvalue-to-rvalue cast if it is an lvalue. 14640 static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) { 14641 assert(!E->isValueDependent()); 14642 if (Info.EnableNewConstInterp) { 14643 if (!Info.Ctx.getInterpContext().evaluateAsRValue(Info, E, Result)) 14644 return false; 14645 } else { 14646 if (E->getType().isNull()) 14647 return false; 14648 14649 if (!CheckLiteralType(Info, E)) 14650 return false; 14651 14652 if (!::Evaluate(Result, Info, E)) 14653 return false; 14654 14655 if (E->isGLValue()) { 14656 LValue LV; 14657 LV.setFrom(Info.Ctx, Result); 14658 if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result)) 14659 return false; 14660 } 14661 } 14662 14663 // Check this core constant expression is a constant expression. 14664 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result, 14665 ConstantExprKind::Normal) && 14666 CheckMemoryLeaks(Info); 14667 } 14668 14669 static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result, 14670 const ASTContext &Ctx, bool &IsConst) { 14671 // Fast-path evaluations of integer literals, since we sometimes see files 14672 // containing vast quantities of these. 14673 if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(Exp)) { 14674 Result.Val = APValue(APSInt(L->getValue(), 14675 L->getType()->isUnsignedIntegerType())); 14676 IsConst = true; 14677 return true; 14678 } 14679 14680 // This case should be rare, but we need to check it before we check on 14681 // the type below. 14682 if (Exp->getType().isNull()) { 14683 IsConst = false; 14684 return true; 14685 } 14686 14687 // FIXME: Evaluating values of large array and record types can cause 14688 // performance problems. Only do so in C++11 for now. 14689 if (Exp->isPRValue() && 14690 (Exp->getType()->isArrayType() || Exp->getType()->isRecordType()) && 14691 !Ctx.getLangOpts().CPlusPlus11) { 14692 IsConst = false; 14693 return true; 14694 } 14695 return false; 14696 } 14697 14698 static bool hasUnacceptableSideEffect(Expr::EvalStatus &Result, 14699 Expr::SideEffectsKind SEK) { 14700 return (SEK < Expr::SE_AllowSideEffects && Result.HasSideEffects) || 14701 (SEK < Expr::SE_AllowUndefinedBehavior && Result.HasUndefinedBehavior); 14702 } 14703 14704 static bool EvaluateAsRValue(const Expr *E, Expr::EvalResult &Result, 14705 const ASTContext &Ctx, EvalInfo &Info) { 14706 assert(!E->isValueDependent()); 14707 bool IsConst; 14708 if (FastEvaluateAsRValue(E, Result, Ctx, IsConst)) 14709 return IsConst; 14710 14711 return EvaluateAsRValue(Info, E, Result.Val); 14712 } 14713 14714 static bool EvaluateAsInt(const Expr *E, Expr::EvalResult &ExprResult, 14715 const ASTContext &Ctx, 14716 Expr::SideEffectsKind AllowSideEffects, 14717 EvalInfo &Info) { 14718 assert(!E->isValueDependent()); 14719 if (!E->getType()->isIntegralOrEnumerationType()) 14720 return false; 14721 14722 if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info) || 14723 !ExprResult.Val.isInt() || 14724 hasUnacceptableSideEffect(ExprResult, AllowSideEffects)) 14725 return false; 14726 14727 return true; 14728 } 14729 14730 static bool EvaluateAsFixedPoint(const Expr *E, Expr::EvalResult &ExprResult, 14731 const ASTContext &Ctx, 14732 Expr::SideEffectsKind AllowSideEffects, 14733 EvalInfo &Info) { 14734 assert(!E->isValueDependent()); 14735 if (!E->getType()->isFixedPointType()) 14736 return false; 14737 14738 if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info)) 14739 return false; 14740 14741 if (!ExprResult.Val.isFixedPoint() || 14742 hasUnacceptableSideEffect(ExprResult, AllowSideEffects)) 14743 return false; 14744 14745 return true; 14746 } 14747 14748 /// EvaluateAsRValue - Return true if this is a constant which we can fold using 14749 /// any crazy technique (that has nothing to do with language standards) that 14750 /// we want to. If this function returns true, it returns the folded constant 14751 /// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion 14752 /// will be applied to the result. 14753 bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx, 14754 bool InConstantContext) const { 14755 assert(!isValueDependent() && 14756 "Expression evaluator can't be called on a dependent expression."); 14757 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); 14758 Info.InConstantContext = InConstantContext; 14759 return ::EvaluateAsRValue(this, Result, Ctx, Info); 14760 } 14761 14762 bool Expr::EvaluateAsBooleanCondition(bool &Result, const ASTContext &Ctx, 14763 bool InConstantContext) const { 14764 assert(!isValueDependent() && 14765 "Expression evaluator can't be called on a dependent expression."); 14766 EvalResult Scratch; 14767 return EvaluateAsRValue(Scratch, Ctx, InConstantContext) && 14768 HandleConversionToBool(Scratch.Val, Result); 14769 } 14770 14771 bool Expr::EvaluateAsInt(EvalResult &Result, const ASTContext &Ctx, 14772 SideEffectsKind AllowSideEffects, 14773 bool InConstantContext) const { 14774 assert(!isValueDependent() && 14775 "Expression evaluator can't be called on a dependent expression."); 14776 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); 14777 Info.InConstantContext = InConstantContext; 14778 return ::EvaluateAsInt(this, Result, Ctx, AllowSideEffects, Info); 14779 } 14780 14781 bool Expr::EvaluateAsFixedPoint(EvalResult &Result, const ASTContext &Ctx, 14782 SideEffectsKind AllowSideEffects, 14783 bool InConstantContext) const { 14784 assert(!isValueDependent() && 14785 "Expression evaluator can't be called on a dependent expression."); 14786 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); 14787 Info.InConstantContext = InConstantContext; 14788 return ::EvaluateAsFixedPoint(this, Result, Ctx, AllowSideEffects, Info); 14789 } 14790 14791 bool Expr::EvaluateAsFloat(APFloat &Result, const ASTContext &Ctx, 14792 SideEffectsKind AllowSideEffects, 14793 bool InConstantContext) const { 14794 assert(!isValueDependent() && 14795 "Expression evaluator can't be called on a dependent expression."); 14796 14797 if (!getType()->isRealFloatingType()) 14798 return false; 14799 14800 EvalResult ExprResult; 14801 if (!EvaluateAsRValue(ExprResult, Ctx, InConstantContext) || 14802 !ExprResult.Val.isFloat() || 14803 hasUnacceptableSideEffect(ExprResult, AllowSideEffects)) 14804 return false; 14805 14806 Result = ExprResult.Val.getFloat(); 14807 return true; 14808 } 14809 14810 bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx, 14811 bool InConstantContext) const { 14812 assert(!isValueDependent() && 14813 "Expression evaluator can't be called on a dependent expression."); 14814 14815 EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold); 14816 Info.InConstantContext = InConstantContext; 14817 LValue LV; 14818 CheckedTemporaries CheckedTemps; 14819 if (!EvaluateLValue(this, LV, Info) || !Info.discardCleanups() || 14820 Result.HasSideEffects || 14821 !CheckLValueConstantExpression(Info, getExprLoc(), 14822 Ctx.getLValueReferenceType(getType()), LV, 14823 ConstantExprKind::Normal, CheckedTemps)) 14824 return false; 14825 14826 LV.moveInto(Result.Val); 14827 return true; 14828 } 14829 14830 static bool EvaluateDestruction(const ASTContext &Ctx, APValue::LValueBase Base, 14831 APValue DestroyedValue, QualType Type, 14832 SourceLocation Loc, Expr::EvalStatus &EStatus, 14833 bool IsConstantDestruction) { 14834 EvalInfo Info(Ctx, EStatus, 14835 IsConstantDestruction ? EvalInfo::EM_ConstantExpression 14836 : EvalInfo::EM_ConstantFold); 14837 Info.setEvaluatingDecl(Base, DestroyedValue, 14838 EvalInfo::EvaluatingDeclKind::Dtor); 14839 Info.InConstantContext = IsConstantDestruction; 14840 14841 LValue LVal; 14842 LVal.set(Base); 14843 14844 if (!HandleDestruction(Info, Loc, Base, DestroyedValue, Type) || 14845 EStatus.HasSideEffects) 14846 return false; 14847 14848 if (!Info.discardCleanups()) 14849 llvm_unreachable("Unhandled cleanup; missing full expression marker?"); 14850 14851 return true; 14852 } 14853 14854 bool Expr::EvaluateAsConstantExpr(EvalResult &Result, const ASTContext &Ctx, 14855 ConstantExprKind Kind) const { 14856 assert(!isValueDependent() && 14857 "Expression evaluator can't be called on a dependent expression."); 14858 14859 EvalInfo::EvaluationMode EM = EvalInfo::EM_ConstantExpression; 14860 EvalInfo Info(Ctx, Result, EM); 14861 Info.InConstantContext = true; 14862 14863 // The type of the object we're initializing is 'const T' for a class NTTP. 14864 QualType T = getType(); 14865 if (Kind == ConstantExprKind::ClassTemplateArgument) 14866 T.addConst(); 14867 14868 // If we're evaluating a prvalue, fake up a MaterializeTemporaryExpr to 14869 // represent the result of the evaluation. CheckConstantExpression ensures 14870 // this doesn't escape. 14871 MaterializeTemporaryExpr BaseMTE(T, const_cast<Expr*>(this), true); 14872 APValue::LValueBase Base(&BaseMTE); 14873 14874 Info.setEvaluatingDecl(Base, Result.Val); 14875 LValue LVal; 14876 LVal.set(Base); 14877 14878 if (!::EvaluateInPlace(Result.Val, Info, LVal, this) || Result.HasSideEffects) 14879 return false; 14880 14881 if (!Info.discardCleanups()) 14882 llvm_unreachable("Unhandled cleanup; missing full expression marker?"); 14883 14884 if (!CheckConstantExpression(Info, getExprLoc(), getStorageType(Ctx, this), 14885 Result.Val, Kind)) 14886 return false; 14887 if (!CheckMemoryLeaks(Info)) 14888 return false; 14889 14890 // If this is a class template argument, it's required to have constant 14891 // destruction too. 14892 if (Kind == ConstantExprKind::ClassTemplateArgument && 14893 (!EvaluateDestruction(Ctx, Base, Result.Val, T, getBeginLoc(), Result, 14894 true) || 14895 Result.HasSideEffects)) { 14896 // FIXME: Prefix a note to indicate that the problem is lack of constant 14897 // destruction. 14898 return false; 14899 } 14900 14901 return true; 14902 } 14903 14904 bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx, 14905 const VarDecl *VD, 14906 SmallVectorImpl<PartialDiagnosticAt> &Notes) const { 14907 assert(!isValueDependent() && 14908 "Expression evaluator can't be called on a dependent expression."); 14909 14910 // FIXME: Evaluating initializers for large array and record types can cause 14911 // performance problems. Only do so in C++11 for now. 14912 if (isPRValue() && (getType()->isArrayType() || getType()->isRecordType()) && 14913 !Ctx.getLangOpts().CPlusPlus11) 14914 return false; 14915 14916 Expr::EvalStatus EStatus; 14917 EStatus.Diag = &Notes; 14918 14919 EvalInfo Info(Ctx, EStatus, VD->isConstexpr() 14920 ? EvalInfo::EM_ConstantExpression 14921 : EvalInfo::EM_ConstantFold); 14922 Info.setEvaluatingDecl(VD, Value); 14923 Info.InConstantContext = true; 14924 14925 SourceLocation DeclLoc = VD->getLocation(); 14926 QualType DeclTy = VD->getType(); 14927 14928 if (Info.EnableNewConstInterp) { 14929 auto &InterpCtx = const_cast<ASTContext &>(Ctx).getInterpContext(); 14930 if (!InterpCtx.evaluateAsInitializer(Info, VD, Value)) 14931 return false; 14932 } else { 14933 LValue LVal; 14934 LVal.set(VD); 14935 14936 if (!EvaluateInPlace(Value, Info, LVal, this, 14937 /*AllowNonLiteralTypes=*/true) || 14938 EStatus.HasSideEffects) 14939 return false; 14940 14941 // At this point, any lifetime-extended temporaries are completely 14942 // initialized. 14943 Info.performLifetimeExtension(); 14944 14945 if (!Info.discardCleanups()) 14946 llvm_unreachable("Unhandled cleanup; missing full expression marker?"); 14947 } 14948 return CheckConstantExpression(Info, DeclLoc, DeclTy, Value, 14949 ConstantExprKind::Normal) && 14950 CheckMemoryLeaks(Info); 14951 } 14952 14953 bool VarDecl::evaluateDestruction( 14954 SmallVectorImpl<PartialDiagnosticAt> &Notes) const { 14955 Expr::EvalStatus EStatus; 14956 EStatus.Diag = &Notes; 14957 14958 // Only treat the destruction as constant destruction if we formally have 14959 // constant initialization (or are usable in a constant expression). 14960 bool IsConstantDestruction = hasConstantInitialization(); 14961 14962 // Make a copy of the value for the destructor to mutate, if we know it. 14963 // Otherwise, treat the value as default-initialized; if the destructor works 14964 // anyway, then the destruction is constant (and must be essentially empty). 14965 APValue DestroyedValue; 14966 if (getEvaluatedValue() && !getEvaluatedValue()->isAbsent()) 14967 DestroyedValue = *getEvaluatedValue(); 14968 else if (!getDefaultInitValue(getType(), DestroyedValue)) 14969 return false; 14970 14971 if (!EvaluateDestruction(getASTContext(), this, std::move(DestroyedValue), 14972 getType(), getLocation(), EStatus, 14973 IsConstantDestruction) || 14974 EStatus.HasSideEffects) 14975 return false; 14976 14977 ensureEvaluatedStmt()->HasConstantDestruction = true; 14978 return true; 14979 } 14980 14981 /// isEvaluatable - Call EvaluateAsRValue to see if this expression can be 14982 /// constant folded, but discard the result. 14983 bool Expr::isEvaluatable(const ASTContext &Ctx, SideEffectsKind SEK) const { 14984 assert(!isValueDependent() && 14985 "Expression evaluator can't be called on a dependent expression."); 14986 14987 EvalResult Result; 14988 return EvaluateAsRValue(Result, Ctx, /* in constant context */ true) && 14989 !hasUnacceptableSideEffect(Result, SEK); 14990 } 14991 14992 APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx, 14993 SmallVectorImpl<PartialDiagnosticAt> *Diag) const { 14994 assert(!isValueDependent() && 14995 "Expression evaluator can't be called on a dependent expression."); 14996 14997 EvalResult EVResult; 14998 EVResult.Diag = Diag; 14999 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects); 15000 Info.InConstantContext = true; 15001 15002 bool Result = ::EvaluateAsRValue(this, EVResult, Ctx, Info); 15003 (void)Result; 15004 assert(Result && "Could not evaluate expression"); 15005 assert(EVResult.Val.isInt() && "Expression did not evaluate to integer"); 15006 15007 return EVResult.Val.getInt(); 15008 } 15009 15010 APSInt Expr::EvaluateKnownConstIntCheckOverflow( 15011 const ASTContext &Ctx, SmallVectorImpl<PartialDiagnosticAt> *Diag) const { 15012 assert(!isValueDependent() && 15013 "Expression evaluator can't be called on a dependent expression."); 15014 15015 EvalResult EVResult; 15016 EVResult.Diag = Diag; 15017 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects); 15018 Info.InConstantContext = true; 15019 Info.CheckingForUndefinedBehavior = true; 15020 15021 bool Result = ::EvaluateAsRValue(Info, this, EVResult.Val); 15022 (void)Result; 15023 assert(Result && "Could not evaluate expression"); 15024 assert(EVResult.Val.isInt() && "Expression did not evaluate to integer"); 15025 15026 return EVResult.Val.getInt(); 15027 } 15028 15029 void Expr::EvaluateForOverflow(const ASTContext &Ctx) const { 15030 assert(!isValueDependent() && 15031 "Expression evaluator can't be called on a dependent expression."); 15032 15033 bool IsConst; 15034 EvalResult EVResult; 15035 if (!FastEvaluateAsRValue(this, EVResult, Ctx, IsConst)) { 15036 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects); 15037 Info.CheckingForUndefinedBehavior = true; 15038 (void)::EvaluateAsRValue(Info, this, EVResult.Val); 15039 } 15040 } 15041 15042 bool Expr::EvalResult::isGlobalLValue() const { 15043 assert(Val.isLValue()); 15044 return IsGlobalLValue(Val.getLValueBase()); 15045 } 15046 15047 /// isIntegerConstantExpr - this recursive routine will test if an expression is 15048 /// an integer constant expression. 15049 15050 /// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero, 15051 /// comma, etc 15052 15053 // CheckICE - This function does the fundamental ICE checking: the returned 15054 // ICEDiag contains an ICEKind indicating whether the expression is an ICE, 15055 // and a (possibly null) SourceLocation indicating the location of the problem. 15056 // 15057 // Note that to reduce code duplication, this helper does no evaluation 15058 // itself; the caller checks whether the expression is evaluatable, and 15059 // in the rare cases where CheckICE actually cares about the evaluated 15060 // value, it calls into Evaluate. 15061 15062 namespace { 15063 15064 enum ICEKind { 15065 /// This expression is an ICE. 15066 IK_ICE, 15067 /// This expression is not an ICE, but if it isn't evaluated, it's 15068 /// a legal subexpression for an ICE. This return value is used to handle 15069 /// the comma operator in C99 mode, and non-constant subexpressions. 15070 IK_ICEIfUnevaluated, 15071 /// This expression is not an ICE, and is not a legal subexpression for one. 15072 IK_NotICE 15073 }; 15074 15075 struct ICEDiag { 15076 ICEKind Kind; 15077 SourceLocation Loc; 15078 15079 ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {} 15080 }; 15081 15082 } 15083 15084 static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); } 15085 15086 static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; } 15087 15088 static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) { 15089 Expr::EvalResult EVResult; 15090 Expr::EvalStatus Status; 15091 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression); 15092 15093 Info.InConstantContext = true; 15094 if (!::EvaluateAsRValue(E, EVResult, Ctx, Info) || EVResult.HasSideEffects || 15095 !EVResult.Val.isInt()) 15096 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15097 15098 return NoDiag(); 15099 } 15100 15101 static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) { 15102 assert(!E->isValueDependent() && "Should not see value dependent exprs!"); 15103 if (!E->getType()->isIntegralOrEnumerationType()) 15104 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15105 15106 switch (E->getStmtClass()) { 15107 #define ABSTRACT_STMT(Node) 15108 #define STMT(Node, Base) case Expr::Node##Class: 15109 #define EXPR(Node, Base) 15110 #include "clang/AST/StmtNodes.inc" 15111 case Expr::PredefinedExprClass: 15112 case Expr::FloatingLiteralClass: 15113 case Expr::ImaginaryLiteralClass: 15114 case Expr::StringLiteralClass: 15115 case Expr::ArraySubscriptExprClass: 15116 case Expr::MatrixSubscriptExprClass: 15117 case Expr::OMPArraySectionExprClass: 15118 case Expr::OMPArrayShapingExprClass: 15119 case Expr::OMPIteratorExprClass: 15120 case Expr::MemberExprClass: 15121 case Expr::CompoundAssignOperatorClass: 15122 case Expr::CompoundLiteralExprClass: 15123 case Expr::ExtVectorElementExprClass: 15124 case Expr::DesignatedInitExprClass: 15125 case Expr::ArrayInitLoopExprClass: 15126 case Expr::ArrayInitIndexExprClass: 15127 case Expr::NoInitExprClass: 15128 case Expr::DesignatedInitUpdateExprClass: 15129 case Expr::ImplicitValueInitExprClass: 15130 case Expr::ParenListExprClass: 15131 case Expr::VAArgExprClass: 15132 case Expr::AddrLabelExprClass: 15133 case Expr::StmtExprClass: 15134 case Expr::CXXMemberCallExprClass: 15135 case Expr::CUDAKernelCallExprClass: 15136 case Expr::CXXAddrspaceCastExprClass: 15137 case Expr::CXXDynamicCastExprClass: 15138 case Expr::CXXTypeidExprClass: 15139 case Expr::CXXUuidofExprClass: 15140 case Expr::MSPropertyRefExprClass: 15141 case Expr::MSPropertySubscriptExprClass: 15142 case Expr::CXXNullPtrLiteralExprClass: 15143 case Expr::UserDefinedLiteralClass: 15144 case Expr::CXXThisExprClass: 15145 case Expr::CXXThrowExprClass: 15146 case Expr::CXXNewExprClass: 15147 case Expr::CXXDeleteExprClass: 15148 case Expr::CXXPseudoDestructorExprClass: 15149 case Expr::UnresolvedLookupExprClass: 15150 case Expr::TypoExprClass: 15151 case Expr::RecoveryExprClass: 15152 case Expr::DependentScopeDeclRefExprClass: 15153 case Expr::CXXConstructExprClass: 15154 case Expr::CXXInheritedCtorInitExprClass: 15155 case Expr::CXXStdInitializerListExprClass: 15156 case Expr::CXXBindTemporaryExprClass: 15157 case Expr::ExprWithCleanupsClass: 15158 case Expr::CXXTemporaryObjectExprClass: 15159 case Expr::CXXUnresolvedConstructExprClass: 15160 case Expr::CXXDependentScopeMemberExprClass: 15161 case Expr::UnresolvedMemberExprClass: 15162 case Expr::ObjCStringLiteralClass: 15163 case Expr::ObjCBoxedExprClass: 15164 case Expr::ObjCArrayLiteralClass: 15165 case Expr::ObjCDictionaryLiteralClass: 15166 case Expr::ObjCEncodeExprClass: 15167 case Expr::ObjCMessageExprClass: 15168 case Expr::ObjCSelectorExprClass: 15169 case Expr::ObjCProtocolExprClass: 15170 case Expr::ObjCIvarRefExprClass: 15171 case Expr::ObjCPropertyRefExprClass: 15172 case Expr::ObjCSubscriptRefExprClass: 15173 case Expr::ObjCIsaExprClass: 15174 case Expr::ObjCAvailabilityCheckExprClass: 15175 case Expr::ShuffleVectorExprClass: 15176 case Expr::ConvertVectorExprClass: 15177 case Expr::BlockExprClass: 15178 case Expr::NoStmtClass: 15179 case Expr::OpaqueValueExprClass: 15180 case Expr::PackExpansionExprClass: 15181 case Expr::SubstNonTypeTemplateParmPackExprClass: 15182 case Expr::FunctionParmPackExprClass: 15183 case Expr::AsTypeExprClass: 15184 case Expr::ObjCIndirectCopyRestoreExprClass: 15185 case Expr::MaterializeTemporaryExprClass: 15186 case Expr::PseudoObjectExprClass: 15187 case Expr::AtomicExprClass: 15188 case Expr::LambdaExprClass: 15189 case Expr::CXXFoldExprClass: 15190 case Expr::CoawaitExprClass: 15191 case Expr::DependentCoawaitExprClass: 15192 case Expr::CoyieldExprClass: 15193 case Expr::SYCLUniqueStableNameExprClass: 15194 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15195 15196 case Expr::InitListExprClass: { 15197 // C++03 [dcl.init]p13: If T is a scalar type, then a declaration of the 15198 // form "T x = { a };" is equivalent to "T x = a;". 15199 // Unless we're initializing a reference, T is a scalar as it is known to be 15200 // of integral or enumeration type. 15201 if (E->isPRValue()) 15202 if (cast<InitListExpr>(E)->getNumInits() == 1) 15203 return CheckICE(cast<InitListExpr>(E)->getInit(0), Ctx); 15204 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15205 } 15206 15207 case Expr::SizeOfPackExprClass: 15208 case Expr::GNUNullExprClass: 15209 case Expr::SourceLocExprClass: 15210 return NoDiag(); 15211 15212 case Expr::SubstNonTypeTemplateParmExprClass: 15213 return 15214 CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx); 15215 15216 case Expr::ConstantExprClass: 15217 return CheckICE(cast<ConstantExpr>(E)->getSubExpr(), Ctx); 15218 15219 case Expr::ParenExprClass: 15220 return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx); 15221 case Expr::GenericSelectionExprClass: 15222 return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx); 15223 case Expr::IntegerLiteralClass: 15224 case Expr::FixedPointLiteralClass: 15225 case Expr::CharacterLiteralClass: 15226 case Expr::ObjCBoolLiteralExprClass: 15227 case Expr::CXXBoolLiteralExprClass: 15228 case Expr::CXXScalarValueInitExprClass: 15229 case Expr::TypeTraitExprClass: 15230 case Expr::ConceptSpecializationExprClass: 15231 case Expr::RequiresExprClass: 15232 case Expr::ArrayTypeTraitExprClass: 15233 case Expr::ExpressionTraitExprClass: 15234 case Expr::CXXNoexceptExprClass: 15235 return NoDiag(); 15236 case Expr::CallExprClass: 15237 case Expr::CXXOperatorCallExprClass: { 15238 // C99 6.6/3 allows function calls within unevaluated subexpressions of 15239 // constant expressions, but they can never be ICEs because an ICE cannot 15240 // contain an operand of (pointer to) function type. 15241 const CallExpr *CE = cast<CallExpr>(E); 15242 if (CE->getBuiltinCallee()) 15243 return CheckEvalInICE(E, Ctx); 15244 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15245 } 15246 case Expr::CXXRewrittenBinaryOperatorClass: 15247 return CheckICE(cast<CXXRewrittenBinaryOperator>(E)->getSemanticForm(), 15248 Ctx); 15249 case Expr::DeclRefExprClass: { 15250 const NamedDecl *D = cast<DeclRefExpr>(E)->getDecl(); 15251 if (isa<EnumConstantDecl>(D)) 15252 return NoDiag(); 15253 15254 // C++ and OpenCL (FIXME: spec reference?) allow reading const-qualified 15255 // integer variables in constant expressions: 15256 // 15257 // C++ 7.1.5.1p2 15258 // A variable of non-volatile const-qualified integral or enumeration 15259 // type initialized by an ICE can be used in ICEs. 15260 // 15261 // We sometimes use CheckICE to check the C++98 rules in C++11 mode. In 15262 // that mode, use of reference variables should not be allowed. 15263 const VarDecl *VD = dyn_cast<VarDecl>(D); 15264 if (VD && VD->isUsableInConstantExpressions(Ctx) && 15265 !VD->getType()->isReferenceType()) 15266 return NoDiag(); 15267 15268 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15269 } 15270 case Expr::UnaryOperatorClass: { 15271 const UnaryOperator *Exp = cast<UnaryOperator>(E); 15272 switch (Exp->getOpcode()) { 15273 case UO_PostInc: 15274 case UO_PostDec: 15275 case UO_PreInc: 15276 case UO_PreDec: 15277 case UO_AddrOf: 15278 case UO_Deref: 15279 case UO_Coawait: 15280 // C99 6.6/3 allows increment and decrement within unevaluated 15281 // subexpressions of constant expressions, but they can never be ICEs 15282 // because an ICE cannot contain an lvalue operand. 15283 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15284 case UO_Extension: 15285 case UO_LNot: 15286 case UO_Plus: 15287 case UO_Minus: 15288 case UO_Not: 15289 case UO_Real: 15290 case UO_Imag: 15291 return CheckICE(Exp->getSubExpr(), Ctx); 15292 } 15293 llvm_unreachable("invalid unary operator class"); 15294 } 15295 case Expr::OffsetOfExprClass: { 15296 // Note that per C99, offsetof must be an ICE. And AFAIK, using 15297 // EvaluateAsRValue matches the proposed gcc behavior for cases like 15298 // "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect 15299 // compliance: we should warn earlier for offsetof expressions with 15300 // array subscripts that aren't ICEs, and if the array subscripts 15301 // are ICEs, the value of the offsetof must be an integer constant. 15302 return CheckEvalInICE(E, Ctx); 15303 } 15304 case Expr::UnaryExprOrTypeTraitExprClass: { 15305 const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E); 15306 if ((Exp->getKind() == UETT_SizeOf) && 15307 Exp->getTypeOfArgument()->isVariableArrayType()) 15308 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15309 return NoDiag(); 15310 } 15311 case Expr::BinaryOperatorClass: { 15312 const BinaryOperator *Exp = cast<BinaryOperator>(E); 15313 switch (Exp->getOpcode()) { 15314 case BO_PtrMemD: 15315 case BO_PtrMemI: 15316 case BO_Assign: 15317 case BO_MulAssign: 15318 case BO_DivAssign: 15319 case BO_RemAssign: 15320 case BO_AddAssign: 15321 case BO_SubAssign: 15322 case BO_ShlAssign: 15323 case BO_ShrAssign: 15324 case BO_AndAssign: 15325 case BO_XorAssign: 15326 case BO_OrAssign: 15327 // C99 6.6/3 allows assignments within unevaluated subexpressions of 15328 // constant expressions, but they can never be ICEs because an ICE cannot 15329 // contain an lvalue operand. 15330 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15331 15332 case BO_Mul: 15333 case BO_Div: 15334 case BO_Rem: 15335 case BO_Add: 15336 case BO_Sub: 15337 case BO_Shl: 15338 case BO_Shr: 15339 case BO_LT: 15340 case BO_GT: 15341 case BO_LE: 15342 case BO_GE: 15343 case BO_EQ: 15344 case BO_NE: 15345 case BO_And: 15346 case BO_Xor: 15347 case BO_Or: 15348 case BO_Comma: 15349 case BO_Cmp: { 15350 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); 15351 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); 15352 if (Exp->getOpcode() == BO_Div || 15353 Exp->getOpcode() == BO_Rem) { 15354 // EvaluateAsRValue gives an error for undefined Div/Rem, so make sure 15355 // we don't evaluate one. 15356 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) { 15357 llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx); 15358 if (REval == 0) 15359 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc()); 15360 if (REval.isSigned() && REval.isAllOnesValue()) { 15361 llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx); 15362 if (LEval.isMinSignedValue()) 15363 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc()); 15364 } 15365 } 15366 } 15367 if (Exp->getOpcode() == BO_Comma) { 15368 if (Ctx.getLangOpts().C99) { 15369 // C99 6.6p3 introduces a strange edge case: comma can be in an ICE 15370 // if it isn't evaluated. 15371 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) 15372 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc()); 15373 } else { 15374 // In both C89 and C++, commas in ICEs are illegal. 15375 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15376 } 15377 } 15378 return Worst(LHSResult, RHSResult); 15379 } 15380 case BO_LAnd: 15381 case BO_LOr: { 15382 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); 15383 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); 15384 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) { 15385 // Rare case where the RHS has a comma "side-effect"; we need 15386 // to actually check the condition to see whether the side 15387 // with the comma is evaluated. 15388 if ((Exp->getOpcode() == BO_LAnd) != 15389 (Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0)) 15390 return RHSResult; 15391 return NoDiag(); 15392 } 15393 15394 return Worst(LHSResult, RHSResult); 15395 } 15396 } 15397 llvm_unreachable("invalid binary operator kind"); 15398 } 15399 case Expr::ImplicitCastExprClass: 15400 case Expr::CStyleCastExprClass: 15401 case Expr::CXXFunctionalCastExprClass: 15402 case Expr::CXXStaticCastExprClass: 15403 case Expr::CXXReinterpretCastExprClass: 15404 case Expr::CXXConstCastExprClass: 15405 case Expr::ObjCBridgedCastExprClass: { 15406 const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr(); 15407 if (isa<ExplicitCastExpr>(E)) { 15408 if (const FloatingLiteral *FL 15409 = dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) { 15410 unsigned DestWidth = Ctx.getIntWidth(E->getType()); 15411 bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType(); 15412 APSInt IgnoredVal(DestWidth, !DestSigned); 15413 bool Ignored; 15414 // If the value does not fit in the destination type, the behavior is 15415 // undefined, so we are not required to treat it as a constant 15416 // expression. 15417 if (FL->getValue().convertToInteger(IgnoredVal, 15418 llvm::APFloat::rmTowardZero, 15419 &Ignored) & APFloat::opInvalidOp) 15420 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15421 return NoDiag(); 15422 } 15423 } 15424 switch (cast<CastExpr>(E)->getCastKind()) { 15425 case CK_LValueToRValue: 15426 case CK_AtomicToNonAtomic: 15427 case CK_NonAtomicToAtomic: 15428 case CK_NoOp: 15429 case CK_IntegralToBoolean: 15430 case CK_IntegralCast: 15431 return CheckICE(SubExpr, Ctx); 15432 default: 15433 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15434 } 15435 } 15436 case Expr::BinaryConditionalOperatorClass: { 15437 const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E); 15438 ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx); 15439 if (CommonResult.Kind == IK_NotICE) return CommonResult; 15440 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); 15441 if (FalseResult.Kind == IK_NotICE) return FalseResult; 15442 if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult; 15443 if (FalseResult.Kind == IK_ICEIfUnevaluated && 15444 Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag(); 15445 return FalseResult; 15446 } 15447 case Expr::ConditionalOperatorClass: { 15448 const ConditionalOperator *Exp = cast<ConditionalOperator>(E); 15449 // If the condition (ignoring parens) is a __builtin_constant_p call, 15450 // then only the true side is actually considered in an integer constant 15451 // expression, and it is fully evaluated. This is an important GNU 15452 // extension. See GCC PR38377 for discussion. 15453 if (const CallExpr *CallCE 15454 = dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts())) 15455 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p) 15456 return CheckEvalInICE(E, Ctx); 15457 ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx); 15458 if (CondResult.Kind == IK_NotICE) 15459 return CondResult; 15460 15461 ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx); 15462 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); 15463 15464 if (TrueResult.Kind == IK_NotICE) 15465 return TrueResult; 15466 if (FalseResult.Kind == IK_NotICE) 15467 return FalseResult; 15468 if (CondResult.Kind == IK_ICEIfUnevaluated) 15469 return CondResult; 15470 if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE) 15471 return NoDiag(); 15472 // Rare case where the diagnostics depend on which side is evaluated 15473 // Note that if we get here, CondResult is 0, and at least one of 15474 // TrueResult and FalseResult is non-zero. 15475 if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0) 15476 return FalseResult; 15477 return TrueResult; 15478 } 15479 case Expr::CXXDefaultArgExprClass: 15480 return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx); 15481 case Expr::CXXDefaultInitExprClass: 15482 return CheckICE(cast<CXXDefaultInitExpr>(E)->getExpr(), Ctx); 15483 case Expr::ChooseExprClass: { 15484 return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(), Ctx); 15485 } 15486 case Expr::BuiltinBitCastExprClass: { 15487 if (!checkBitCastConstexprEligibility(nullptr, Ctx, cast<CastExpr>(E))) 15488 return ICEDiag(IK_NotICE, E->getBeginLoc()); 15489 return CheckICE(cast<CastExpr>(E)->getSubExpr(), Ctx); 15490 } 15491 } 15492 15493 llvm_unreachable("Invalid StmtClass!"); 15494 } 15495 15496 /// Evaluate an expression as a C++11 integral constant expression. 15497 static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx, 15498 const Expr *E, 15499 llvm::APSInt *Value, 15500 SourceLocation *Loc) { 15501 if (!E->getType()->isIntegralOrUnscopedEnumerationType()) { 15502 if (Loc) *Loc = E->getExprLoc(); 15503 return false; 15504 } 15505 15506 APValue Result; 15507 if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc)) 15508 return false; 15509 15510 if (!Result.isInt()) { 15511 if (Loc) *Loc = E->getExprLoc(); 15512 return false; 15513 } 15514 15515 if (Value) *Value = Result.getInt(); 15516 return true; 15517 } 15518 15519 bool Expr::isIntegerConstantExpr(const ASTContext &Ctx, 15520 SourceLocation *Loc) const { 15521 assert(!isValueDependent() && 15522 "Expression evaluator can't be called on a dependent expression."); 15523 15524 if (Ctx.getLangOpts().CPlusPlus11) 15525 return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, nullptr, Loc); 15526 15527 ICEDiag D = CheckICE(this, Ctx); 15528 if (D.Kind != IK_ICE) { 15529 if (Loc) *Loc = D.Loc; 15530 return false; 15531 } 15532 return true; 15533 } 15534 15535 Optional<llvm::APSInt> Expr::getIntegerConstantExpr(const ASTContext &Ctx, 15536 SourceLocation *Loc, 15537 bool isEvaluated) const { 15538 assert(!isValueDependent() && 15539 "Expression evaluator can't be called on a dependent expression."); 15540 15541 APSInt Value; 15542 15543 if (Ctx.getLangOpts().CPlusPlus11) { 15544 if (EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc)) 15545 return Value; 15546 return None; 15547 } 15548 15549 if (!isIntegerConstantExpr(Ctx, Loc)) 15550 return None; 15551 15552 // The only possible side-effects here are due to UB discovered in the 15553 // evaluation (for instance, INT_MAX + 1). In such a case, we are still 15554 // required to treat the expression as an ICE, so we produce the folded 15555 // value. 15556 EvalResult ExprResult; 15557 Expr::EvalStatus Status; 15558 EvalInfo Info(Ctx, Status, EvalInfo::EM_IgnoreSideEffects); 15559 Info.InConstantContext = true; 15560 15561 if (!::EvaluateAsInt(this, ExprResult, Ctx, SE_AllowSideEffects, Info)) 15562 llvm_unreachable("ICE cannot be evaluated!"); 15563 15564 return ExprResult.Val.getInt(); 15565 } 15566 15567 bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const { 15568 assert(!isValueDependent() && 15569 "Expression evaluator can't be called on a dependent expression."); 15570 15571 return CheckICE(this, Ctx).Kind == IK_ICE; 15572 } 15573 15574 bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result, 15575 SourceLocation *Loc) const { 15576 assert(!isValueDependent() && 15577 "Expression evaluator can't be called on a dependent expression."); 15578 15579 // We support this checking in C++98 mode in order to diagnose compatibility 15580 // issues. 15581 assert(Ctx.getLangOpts().CPlusPlus); 15582 15583 // Build evaluation settings. 15584 Expr::EvalStatus Status; 15585 SmallVector<PartialDiagnosticAt, 8> Diags; 15586 Status.Diag = &Diags; 15587 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression); 15588 15589 APValue Scratch; 15590 bool IsConstExpr = 15591 ::EvaluateAsRValue(Info, this, Result ? *Result : Scratch) && 15592 // FIXME: We don't produce a diagnostic for this, but the callers that 15593 // call us on arbitrary full-expressions should generally not care. 15594 Info.discardCleanups() && !Status.HasSideEffects; 15595 15596 if (!Diags.empty()) { 15597 IsConstExpr = false; 15598 if (Loc) *Loc = Diags[0].first; 15599 } else if (!IsConstExpr) { 15600 // FIXME: This shouldn't happen. 15601 if (Loc) *Loc = getExprLoc(); 15602 } 15603 15604 return IsConstExpr; 15605 } 15606 15607 bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx, 15608 const FunctionDecl *Callee, 15609 ArrayRef<const Expr*> Args, 15610 const Expr *This) const { 15611 assert(!isValueDependent() && 15612 "Expression evaluator can't be called on a dependent expression."); 15613 15614 Expr::EvalStatus Status; 15615 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated); 15616 Info.InConstantContext = true; 15617 15618 LValue ThisVal; 15619 const LValue *ThisPtr = nullptr; 15620 if (This) { 15621 #ifndef NDEBUG 15622 auto *MD = dyn_cast<CXXMethodDecl>(Callee); 15623 assert(MD && "Don't provide `this` for non-methods."); 15624 assert(!MD->isStatic() && "Don't provide `this` for static methods."); 15625 #endif 15626 if (!This->isValueDependent() && 15627 EvaluateObjectArgument(Info, This, ThisVal) && 15628 !Info.EvalStatus.HasSideEffects) 15629 ThisPtr = &ThisVal; 15630 15631 // Ignore any side-effects from a failed evaluation. This is safe because 15632 // they can't interfere with any other argument evaluation. 15633 Info.EvalStatus.HasSideEffects = false; 15634 } 15635 15636 CallRef Call = Info.CurrentCall->createCall(Callee); 15637 for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end(); 15638 I != E; ++I) { 15639 unsigned Idx = I - Args.begin(); 15640 if (Idx >= Callee->getNumParams()) 15641 break; 15642 const ParmVarDecl *PVD = Callee->getParamDecl(Idx); 15643 if ((*I)->isValueDependent() || 15644 !EvaluateCallArg(PVD, *I, Call, Info) || 15645 Info.EvalStatus.HasSideEffects) { 15646 // If evaluation fails, throw away the argument entirely. 15647 if (APValue *Slot = Info.getParamSlot(Call, PVD)) 15648 *Slot = APValue(); 15649 } 15650 15651 // Ignore any side-effects from a failed evaluation. This is safe because 15652 // they can't interfere with any other argument evaluation. 15653 Info.EvalStatus.HasSideEffects = false; 15654 } 15655 15656 // Parameter cleanups happen in the caller and are not part of this 15657 // evaluation. 15658 Info.discardCleanups(); 15659 Info.EvalStatus.HasSideEffects = false; 15660 15661 // Build fake call to Callee. 15662 CallStackFrame Frame(Info, Callee->getLocation(), Callee, ThisPtr, Call); 15663 // FIXME: Missing ExprWithCleanups in enable_if conditions? 15664 FullExpressionRAII Scope(Info); 15665 return Evaluate(Value, Info, this) && Scope.destroy() && 15666 !Info.EvalStatus.HasSideEffects; 15667 } 15668 15669 bool Expr::isPotentialConstantExpr(const FunctionDecl *FD, 15670 SmallVectorImpl< 15671 PartialDiagnosticAt> &Diags) { 15672 // FIXME: It would be useful to check constexpr function templates, but at the 15673 // moment the constant expression evaluator cannot cope with the non-rigorous 15674 // ASTs which we build for dependent expressions. 15675 if (FD->isDependentContext()) 15676 return true; 15677 15678 Expr::EvalStatus Status; 15679 Status.Diag = &Diags; 15680 15681 EvalInfo Info(FD->getASTContext(), Status, EvalInfo::EM_ConstantExpression); 15682 Info.InConstantContext = true; 15683 Info.CheckingPotentialConstantExpression = true; 15684 15685 // The constexpr VM attempts to compile all methods to bytecode here. 15686 if (Info.EnableNewConstInterp) { 15687 Info.Ctx.getInterpContext().isPotentialConstantExpr(Info, FD); 15688 return Diags.empty(); 15689 } 15690 15691 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); 15692 const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : nullptr; 15693 15694 // Fabricate an arbitrary expression on the stack and pretend that it 15695 // is a temporary being used as the 'this' pointer. 15696 LValue This; 15697 ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy); 15698 This.set({&VIE, Info.CurrentCall->Index}); 15699 15700 ArrayRef<const Expr*> Args; 15701 15702 APValue Scratch; 15703 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) { 15704 // Evaluate the call as a constant initializer, to allow the construction 15705 // of objects of non-literal types. 15706 Info.setEvaluatingDecl(This.getLValueBase(), Scratch); 15707 HandleConstructorCall(&VIE, This, Args, CD, Info, Scratch); 15708 } else { 15709 SourceLocation Loc = FD->getLocation(); 15710 HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : nullptr, 15711 Args, CallRef(), FD->getBody(), Info, Scratch, nullptr); 15712 } 15713 15714 return Diags.empty(); 15715 } 15716 15717 bool Expr::isPotentialConstantExprUnevaluated(Expr *E, 15718 const FunctionDecl *FD, 15719 SmallVectorImpl< 15720 PartialDiagnosticAt> &Diags) { 15721 assert(!E->isValueDependent() && 15722 "Expression evaluator can't be called on a dependent expression."); 15723 15724 Expr::EvalStatus Status; 15725 Status.Diag = &Diags; 15726 15727 EvalInfo Info(FD->getASTContext(), Status, 15728 EvalInfo::EM_ConstantExpressionUnevaluated); 15729 Info.InConstantContext = true; 15730 Info.CheckingPotentialConstantExpression = true; 15731 15732 // Fabricate a call stack frame to give the arguments a plausible cover story. 15733 CallStackFrame Frame(Info, SourceLocation(), FD, /*This*/ nullptr, CallRef()); 15734 15735 APValue ResultScratch; 15736 Evaluate(ResultScratch, Info, E); 15737 return Diags.empty(); 15738 } 15739 15740 bool Expr::tryEvaluateObjectSize(uint64_t &Result, ASTContext &Ctx, 15741 unsigned Type) const { 15742 if (!getType()->isPointerType()) 15743 return false; 15744 15745 Expr::EvalStatus Status; 15746 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold); 15747 return tryEvaluateBuiltinObjectSize(this, Type, Info, Result); 15748 } 15749