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 "clang/AST/APValue.h" 36 #include "clang/AST/ASTContext.h" 37 #include "clang/AST/ASTDiagnostic.h" 38 #include "clang/AST/ASTLambda.h" 39 #include "clang/AST/CharUnits.h" 40 #include "clang/AST/CurrentSourceLocExprScope.h" 41 #include "clang/AST/CXXInheritance.h" 42 #include "clang/AST/Expr.h" 43 #include "clang/AST/OSLog.h" 44 #include "clang/AST/RecordLayout.h" 45 #include "clang/AST/StmtVisitor.h" 46 #include "clang/AST/TypeLoc.h" 47 #include "clang/Basic/Builtins.h" 48 #include "clang/Basic/FixedPoint.h" 49 #include "clang/Basic/TargetInfo.h" 50 #include "llvm/ADT/Optional.h" 51 #include "llvm/ADT/SmallBitVector.h" 52 #include "llvm/Support/SaveAndRestore.h" 53 #include "llvm/Support/raw_ostream.h" 54 #include <cstring> 55 #include <functional> 56 57 #define DEBUG_TYPE "exprconstant" 58 59 using namespace clang; 60 using llvm::APInt; 61 using llvm::APSInt; 62 using llvm::APFloat; 63 using llvm::Optional; 64 65 static bool IsGlobalLValue(APValue::LValueBase B); 66 67 namespace { 68 struct LValue; 69 struct CallStackFrame; 70 struct EvalInfo; 71 72 using SourceLocExprScopeGuard = 73 CurrentSourceLocExprScope::SourceLocExprScopeGuard; 74 75 static QualType getType(APValue::LValueBase B) { 76 if (!B) return QualType(); 77 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { 78 // FIXME: It's unclear where we're supposed to take the type from, and 79 // this actually matters for arrays of unknown bound. Eg: 80 // 81 // extern int arr[]; void f() { extern int arr[3]; }; 82 // constexpr int *p = &arr[1]; // valid? 83 // 84 // For now, we take the array bound from the most recent declaration. 85 for (auto *Redecl = cast<ValueDecl>(D->getMostRecentDecl()); Redecl; 86 Redecl = cast_or_null<ValueDecl>(Redecl->getPreviousDecl())) { 87 QualType T = Redecl->getType(); 88 if (!T->isIncompleteArrayType()) 89 return T; 90 } 91 return D->getType(); 92 } 93 94 if (B.is<TypeInfoLValue>()) 95 return B.getTypeInfoType(); 96 97 const Expr *Base = B.get<const Expr*>(); 98 99 // For a materialized temporary, the type of the temporary we materialized 100 // may not be the type of the expression. 101 if (const MaterializeTemporaryExpr *MTE = 102 dyn_cast<MaterializeTemporaryExpr>(Base)) { 103 SmallVector<const Expr *, 2> CommaLHSs; 104 SmallVector<SubobjectAdjustment, 2> Adjustments; 105 const Expr *Temp = MTE->GetTemporaryExpr(); 106 const Expr *Inner = Temp->skipRValueSubobjectAdjustments(CommaLHSs, 107 Adjustments); 108 // Keep any cv-qualifiers from the reference if we generated a temporary 109 // for it directly. Otherwise use the type after adjustment. 110 if (!Adjustments.empty()) 111 return Inner->getType(); 112 } 113 114 return Base->getType(); 115 } 116 117 /// Get an LValue path entry, which is known to not be an array index, as a 118 /// field declaration. 119 static const FieldDecl *getAsField(APValue::LValuePathEntry E) { 120 return dyn_cast_or_null<FieldDecl>(E.getAsBaseOrMember().getPointer()); 121 } 122 /// Get an LValue path entry, which is known to not be an array index, as a 123 /// base class declaration. 124 static const CXXRecordDecl *getAsBaseClass(APValue::LValuePathEntry E) { 125 return dyn_cast_or_null<CXXRecordDecl>(E.getAsBaseOrMember().getPointer()); 126 } 127 /// Determine whether this LValue path entry for a base class names a virtual 128 /// base class. 129 static bool isVirtualBaseClass(APValue::LValuePathEntry E) { 130 return E.getAsBaseOrMember().getInt(); 131 } 132 133 /// Given a CallExpr, try to get the alloc_size attribute. May return null. 134 static const AllocSizeAttr *getAllocSizeAttr(const CallExpr *CE) { 135 const FunctionDecl *Callee = CE->getDirectCallee(); 136 return Callee ? Callee->getAttr<AllocSizeAttr>() : nullptr; 137 } 138 139 /// Attempts to unwrap a CallExpr (with an alloc_size attribute) from an Expr. 140 /// This will look through a single cast. 141 /// 142 /// Returns null if we couldn't unwrap a function with alloc_size. 143 static const CallExpr *tryUnwrapAllocSizeCall(const Expr *E) { 144 if (!E->getType()->isPointerType()) 145 return nullptr; 146 147 E = E->IgnoreParens(); 148 // If we're doing a variable assignment from e.g. malloc(N), there will 149 // probably be a cast of some kind. In exotic cases, we might also see a 150 // top-level ExprWithCleanups. Ignore them either way. 151 if (const auto *FE = dyn_cast<FullExpr>(E)) 152 E = FE->getSubExpr()->IgnoreParens(); 153 154 if (const auto *Cast = dyn_cast<CastExpr>(E)) 155 E = Cast->getSubExpr()->IgnoreParens(); 156 157 if (const auto *CE = dyn_cast<CallExpr>(E)) 158 return getAllocSizeAttr(CE) ? CE : nullptr; 159 return nullptr; 160 } 161 162 /// Determines whether or not the given Base contains a call to a function 163 /// with the alloc_size attribute. 164 static bool isBaseAnAllocSizeCall(APValue::LValueBase Base) { 165 const auto *E = Base.dyn_cast<const Expr *>(); 166 return E && E->getType()->isPointerType() && tryUnwrapAllocSizeCall(E); 167 } 168 169 /// The bound to claim that an array of unknown bound has. 170 /// The value in MostDerivedArraySize is undefined in this case. So, set it 171 /// to an arbitrary value that's likely to loudly break things if it's used. 172 static const uint64_t AssumedSizeForUnsizedArray = 173 std::numeric_limits<uint64_t>::max() / 2; 174 175 /// Determines if an LValue with the given LValueBase will have an unsized 176 /// array in its designator. 177 /// Find the path length and type of the most-derived subobject in the given 178 /// path, and find the size of the containing array, if any. 179 static unsigned 180 findMostDerivedSubobject(ASTContext &Ctx, APValue::LValueBase Base, 181 ArrayRef<APValue::LValuePathEntry> Path, 182 uint64_t &ArraySize, QualType &Type, bool &IsArray, 183 bool &FirstEntryIsUnsizedArray) { 184 // This only accepts LValueBases from APValues, and APValues don't support 185 // arrays that lack size info. 186 assert(!isBaseAnAllocSizeCall(Base) && 187 "Unsized arrays shouldn't appear here"); 188 unsigned MostDerivedLength = 0; 189 Type = getType(Base); 190 191 for (unsigned I = 0, N = Path.size(); I != N; ++I) { 192 if (Type->isArrayType()) { 193 const ArrayType *AT = Ctx.getAsArrayType(Type); 194 Type = AT->getElementType(); 195 MostDerivedLength = I + 1; 196 IsArray = true; 197 198 if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) { 199 ArraySize = CAT->getSize().getZExtValue(); 200 } else { 201 assert(I == 0 && "unexpected unsized array designator"); 202 FirstEntryIsUnsizedArray = true; 203 ArraySize = AssumedSizeForUnsizedArray; 204 } 205 } else if (Type->isAnyComplexType()) { 206 const ComplexType *CT = Type->castAs<ComplexType>(); 207 Type = CT->getElementType(); 208 ArraySize = 2; 209 MostDerivedLength = I + 1; 210 IsArray = true; 211 } else if (const FieldDecl *FD = getAsField(Path[I])) { 212 Type = FD->getType(); 213 ArraySize = 0; 214 MostDerivedLength = I + 1; 215 IsArray = false; 216 } else { 217 // Path[I] describes a base class. 218 ArraySize = 0; 219 IsArray = false; 220 } 221 } 222 return MostDerivedLength; 223 } 224 225 // The order of this enum is important for diagnostics. 226 enum CheckSubobjectKind { 227 CSK_Base, CSK_Derived, CSK_Field, CSK_ArrayToPointer, CSK_ArrayIndex, 228 CSK_Real, CSK_Imag 229 }; 230 231 /// A path from a glvalue to a subobject of that glvalue. 232 struct SubobjectDesignator { 233 /// True if the subobject was named in a manner not supported by C++11. Such 234 /// lvalues can still be folded, but they are not core constant expressions 235 /// and we cannot perform lvalue-to-rvalue conversions on them. 236 unsigned Invalid : 1; 237 238 /// Is this a pointer one past the end of an object? 239 unsigned IsOnePastTheEnd : 1; 240 241 /// Indicator of whether the first entry is an unsized array. 242 unsigned FirstEntryIsAnUnsizedArray : 1; 243 244 /// Indicator of whether the most-derived object is an array element. 245 unsigned MostDerivedIsArrayElement : 1; 246 247 /// The length of the path to the most-derived object of which this is a 248 /// subobject. 249 unsigned MostDerivedPathLength : 28; 250 251 /// The size of the array of which the most-derived object is an element. 252 /// This will always be 0 if the most-derived object is not an array 253 /// element. 0 is not an indicator of whether or not the most-derived object 254 /// is an array, however, because 0-length arrays are allowed. 255 /// 256 /// If the current array is an unsized array, the value of this is 257 /// undefined. 258 uint64_t MostDerivedArraySize; 259 260 /// The type of the most derived object referred to by this address. 261 QualType MostDerivedType; 262 263 typedef APValue::LValuePathEntry PathEntry; 264 265 /// The entries on the path from the glvalue to the designated subobject. 266 SmallVector<PathEntry, 8> Entries; 267 268 SubobjectDesignator() : Invalid(true) {} 269 270 explicit SubobjectDesignator(QualType T) 271 : Invalid(false), IsOnePastTheEnd(false), 272 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false), 273 MostDerivedPathLength(0), MostDerivedArraySize(0), 274 MostDerivedType(T) {} 275 276 SubobjectDesignator(ASTContext &Ctx, const APValue &V) 277 : Invalid(!V.isLValue() || !V.hasLValuePath()), IsOnePastTheEnd(false), 278 FirstEntryIsAnUnsizedArray(false), MostDerivedIsArrayElement(false), 279 MostDerivedPathLength(0), MostDerivedArraySize(0) { 280 assert(V.isLValue() && "Non-LValue used to make an LValue designator?"); 281 if (!Invalid) { 282 IsOnePastTheEnd = V.isLValueOnePastTheEnd(); 283 ArrayRef<PathEntry> VEntries = V.getLValuePath(); 284 Entries.insert(Entries.end(), VEntries.begin(), VEntries.end()); 285 if (V.getLValueBase()) { 286 bool IsArray = false; 287 bool FirstIsUnsizedArray = false; 288 MostDerivedPathLength = findMostDerivedSubobject( 289 Ctx, V.getLValueBase(), V.getLValuePath(), MostDerivedArraySize, 290 MostDerivedType, IsArray, FirstIsUnsizedArray); 291 MostDerivedIsArrayElement = IsArray; 292 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray; 293 } 294 } 295 } 296 297 void truncate(ASTContext &Ctx, APValue::LValueBase Base, 298 unsigned NewLength) { 299 if (Invalid) 300 return; 301 302 assert(Base && "cannot truncate path for null pointer"); 303 assert(NewLength <= Entries.size() && "not a truncation"); 304 305 if (NewLength == Entries.size()) 306 return; 307 Entries.resize(NewLength); 308 309 bool IsArray = false; 310 bool FirstIsUnsizedArray = false; 311 MostDerivedPathLength = findMostDerivedSubobject( 312 Ctx, Base, Entries, MostDerivedArraySize, MostDerivedType, IsArray, 313 FirstIsUnsizedArray); 314 MostDerivedIsArrayElement = IsArray; 315 FirstEntryIsAnUnsizedArray = FirstIsUnsizedArray; 316 } 317 318 void setInvalid() { 319 Invalid = true; 320 Entries.clear(); 321 } 322 323 /// Determine whether the most derived subobject is an array without a 324 /// known bound. 325 bool isMostDerivedAnUnsizedArray() const { 326 assert(!Invalid && "Calling this makes no sense on invalid designators"); 327 return Entries.size() == 1 && FirstEntryIsAnUnsizedArray; 328 } 329 330 /// Determine what the most derived array's size is. Results in an assertion 331 /// failure if the most derived array lacks a size. 332 uint64_t getMostDerivedArraySize() const { 333 assert(!isMostDerivedAnUnsizedArray() && "Unsized array has no size"); 334 return MostDerivedArraySize; 335 } 336 337 /// Determine whether this is a one-past-the-end pointer. 338 bool isOnePastTheEnd() const { 339 assert(!Invalid); 340 if (IsOnePastTheEnd) 341 return true; 342 if (!isMostDerivedAnUnsizedArray() && MostDerivedIsArrayElement && 343 Entries[MostDerivedPathLength - 1].getAsArrayIndex() == 344 MostDerivedArraySize) 345 return true; 346 return false; 347 } 348 349 /// Get the range of valid index adjustments in the form 350 /// {maximum value that can be subtracted from this pointer, 351 /// maximum value that can be added to this pointer} 352 std::pair<uint64_t, uint64_t> validIndexAdjustments() { 353 if (Invalid || isMostDerivedAnUnsizedArray()) 354 return {0, 0}; 355 356 // [expr.add]p4: For the purposes of these operators, a pointer to a 357 // nonarray object behaves the same as a pointer to the first element of 358 // an array of length one with the type of the object as its element type. 359 bool IsArray = MostDerivedPathLength == Entries.size() && 360 MostDerivedIsArrayElement; 361 uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex() 362 : (uint64_t)IsOnePastTheEnd; 363 uint64_t ArraySize = 364 IsArray ? getMostDerivedArraySize() : (uint64_t)1; 365 return {ArrayIndex, ArraySize - ArrayIndex}; 366 } 367 368 /// Check that this refers to a valid subobject. 369 bool isValidSubobject() const { 370 if (Invalid) 371 return false; 372 return !isOnePastTheEnd(); 373 } 374 /// Check that this refers to a valid subobject, and if not, produce a 375 /// relevant diagnostic and set the designator as invalid. 376 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK); 377 378 /// Get the type of the designated object. 379 QualType getType(ASTContext &Ctx) const { 380 assert(!Invalid && "invalid designator has no subobject type"); 381 return MostDerivedPathLength == Entries.size() 382 ? MostDerivedType 383 : Ctx.getRecordType(getAsBaseClass(Entries.back())); 384 } 385 386 /// Update this designator to refer to the first element within this array. 387 void addArrayUnchecked(const ConstantArrayType *CAT) { 388 Entries.push_back(PathEntry::ArrayIndex(0)); 389 390 // This is a most-derived object. 391 MostDerivedType = CAT->getElementType(); 392 MostDerivedIsArrayElement = true; 393 MostDerivedArraySize = CAT->getSize().getZExtValue(); 394 MostDerivedPathLength = Entries.size(); 395 } 396 /// Update this designator to refer to the first element within the array of 397 /// elements of type T. This is an array of unknown size. 398 void addUnsizedArrayUnchecked(QualType ElemTy) { 399 Entries.push_back(PathEntry::ArrayIndex(0)); 400 401 MostDerivedType = ElemTy; 402 MostDerivedIsArrayElement = true; 403 // The value in MostDerivedArraySize is undefined in this case. So, set it 404 // to an arbitrary value that's likely to loudly break things if it's 405 // used. 406 MostDerivedArraySize = AssumedSizeForUnsizedArray; 407 MostDerivedPathLength = Entries.size(); 408 } 409 /// Update this designator to refer to the given base or member of this 410 /// object. 411 void addDeclUnchecked(const Decl *D, bool Virtual = false) { 412 Entries.push_back(APValue::BaseOrMemberType(D, Virtual)); 413 414 // If this isn't a base class, it's a new most-derived object. 415 if (const FieldDecl *FD = dyn_cast<FieldDecl>(D)) { 416 MostDerivedType = FD->getType(); 417 MostDerivedIsArrayElement = false; 418 MostDerivedArraySize = 0; 419 MostDerivedPathLength = Entries.size(); 420 } 421 } 422 /// Update this designator to refer to the given complex component. 423 void addComplexUnchecked(QualType EltTy, bool Imag) { 424 Entries.push_back(PathEntry::ArrayIndex(Imag)); 425 426 // This is technically a most-derived object, though in practice this 427 // is unlikely to matter. 428 MostDerivedType = EltTy; 429 MostDerivedIsArrayElement = true; 430 MostDerivedArraySize = 2; 431 MostDerivedPathLength = Entries.size(); 432 } 433 void diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, const Expr *E); 434 void diagnosePointerArithmetic(EvalInfo &Info, const Expr *E, 435 const APSInt &N); 436 /// Add N to the address of this subobject. 437 void adjustIndex(EvalInfo &Info, const Expr *E, APSInt N) { 438 if (Invalid || !N) return; 439 uint64_t TruncatedN = N.extOrTrunc(64).getZExtValue(); 440 if (isMostDerivedAnUnsizedArray()) { 441 diagnoseUnsizedArrayPointerArithmetic(Info, E); 442 // Can't verify -- trust that the user is doing the right thing (or if 443 // not, trust that the caller will catch the bad behavior). 444 // FIXME: Should we reject if this overflows, at least? 445 Entries.back() = PathEntry::ArrayIndex( 446 Entries.back().getAsArrayIndex() + TruncatedN); 447 return; 448 } 449 450 // [expr.add]p4: For the purposes of these operators, a pointer to a 451 // nonarray object behaves the same as a pointer to the first element of 452 // an array of length one with the type of the object as its element type. 453 bool IsArray = MostDerivedPathLength == Entries.size() && 454 MostDerivedIsArrayElement; 455 uint64_t ArrayIndex = IsArray ? Entries.back().getAsArrayIndex() 456 : (uint64_t)IsOnePastTheEnd; 457 uint64_t ArraySize = 458 IsArray ? getMostDerivedArraySize() : (uint64_t)1; 459 460 if (N < -(int64_t)ArrayIndex || N > ArraySize - ArrayIndex) { 461 // Calculate the actual index in a wide enough type, so we can include 462 // it in the note. 463 N = N.extend(std::max<unsigned>(N.getBitWidth() + 1, 65)); 464 (llvm::APInt&)N += ArrayIndex; 465 assert(N.ugt(ArraySize) && "bounds check failed for in-bounds index"); 466 diagnosePointerArithmetic(Info, E, N); 467 setInvalid(); 468 return; 469 } 470 471 ArrayIndex += TruncatedN; 472 assert(ArrayIndex <= ArraySize && 473 "bounds check succeeded for out-of-bounds index"); 474 475 if (IsArray) 476 Entries.back() = PathEntry::ArrayIndex(ArrayIndex); 477 else 478 IsOnePastTheEnd = (ArrayIndex != 0); 479 } 480 }; 481 482 /// A stack frame in the constexpr call stack. 483 struct CallStackFrame { 484 EvalInfo &Info; 485 486 /// Parent - The caller of this stack frame. 487 CallStackFrame *Caller; 488 489 /// Callee - The function which was called. 490 const FunctionDecl *Callee; 491 492 /// This - The binding for the this pointer in this call, if any. 493 const LValue *This; 494 495 /// Arguments - Parameter bindings for this function call, indexed by 496 /// parameters' function scope indices. 497 APValue *Arguments; 498 499 /// Source location information about the default argument or default 500 /// initializer expression we're evaluating, if any. 501 CurrentSourceLocExprScope CurSourceLocExprScope; 502 503 // Note that we intentionally use std::map here so that references to 504 // values are stable. 505 typedef std::pair<const void *, unsigned> MapKeyTy; 506 typedef std::map<MapKeyTy, APValue> MapTy; 507 /// Temporaries - Temporary lvalues materialized within this stack frame. 508 MapTy Temporaries; 509 510 /// CallLoc - The location of the call expression for this call. 511 SourceLocation CallLoc; 512 513 /// Index - The call index of this call. 514 unsigned Index; 515 516 /// The stack of integers for tracking version numbers for temporaries. 517 SmallVector<unsigned, 2> TempVersionStack = {1}; 518 unsigned CurTempVersion = TempVersionStack.back(); 519 520 unsigned getTempVersion() const { return TempVersionStack.back(); } 521 522 void pushTempVersion() { 523 TempVersionStack.push_back(++CurTempVersion); 524 } 525 526 void popTempVersion() { 527 TempVersionStack.pop_back(); 528 } 529 530 // FIXME: Adding this to every 'CallStackFrame' may have a nontrivial impact 531 // on the overall stack usage of deeply-recursing constexpr evaluations. 532 // (We should cache this map rather than recomputing it repeatedly.) 533 // But let's try this and see how it goes; we can look into caching the map 534 // as a later change. 535 536 /// LambdaCaptureFields - Mapping from captured variables/this to 537 /// corresponding data members in the closure class. 538 llvm::DenseMap<const VarDecl *, FieldDecl *> LambdaCaptureFields; 539 FieldDecl *LambdaThisCaptureField; 540 541 CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, 542 const FunctionDecl *Callee, const LValue *This, 543 APValue *Arguments); 544 ~CallStackFrame(); 545 546 // Return the temporary for Key whose version number is Version. 547 APValue *getTemporary(const void *Key, unsigned Version) { 548 MapKeyTy KV(Key, Version); 549 auto LB = Temporaries.lower_bound(KV); 550 if (LB != Temporaries.end() && LB->first == KV) 551 return &LB->second; 552 // Pair (Key,Version) wasn't found in the map. Check that no elements 553 // in the map have 'Key' as their key. 554 assert((LB == Temporaries.end() || LB->first.first != Key) && 555 (LB == Temporaries.begin() || std::prev(LB)->first.first != Key) && 556 "Element with key 'Key' found in map"); 557 return nullptr; 558 } 559 560 // Return the current temporary for Key in the map. 561 APValue *getCurrentTemporary(const void *Key) { 562 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX)); 563 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key) 564 return &std::prev(UB)->second; 565 return nullptr; 566 } 567 568 // Return the version number of the current temporary for Key. 569 unsigned getCurrentTemporaryVersion(const void *Key) const { 570 auto UB = Temporaries.upper_bound(MapKeyTy(Key, UINT_MAX)); 571 if (UB != Temporaries.begin() && std::prev(UB)->first.first == Key) 572 return std::prev(UB)->first.second; 573 return 0; 574 } 575 576 APValue &createTemporary(const void *Key, bool IsLifetimeExtended); 577 }; 578 579 /// Temporarily override 'this'. 580 class ThisOverrideRAII { 581 public: 582 ThisOverrideRAII(CallStackFrame &Frame, const LValue *NewThis, bool Enable) 583 : Frame(Frame), OldThis(Frame.This) { 584 if (Enable) 585 Frame.This = NewThis; 586 } 587 ~ThisOverrideRAII() { 588 Frame.This = OldThis; 589 } 590 private: 591 CallStackFrame &Frame; 592 const LValue *OldThis; 593 }; 594 595 /// A partial diagnostic which we might know in advance that we are not going 596 /// to emit. 597 class OptionalDiagnostic { 598 PartialDiagnostic *Diag; 599 600 public: 601 explicit OptionalDiagnostic(PartialDiagnostic *Diag = nullptr) 602 : Diag(Diag) {} 603 604 template<typename T> 605 OptionalDiagnostic &operator<<(const T &v) { 606 if (Diag) 607 *Diag << v; 608 return *this; 609 } 610 611 OptionalDiagnostic &operator<<(const APSInt &I) { 612 if (Diag) { 613 SmallVector<char, 32> Buffer; 614 I.toString(Buffer); 615 *Diag << StringRef(Buffer.data(), Buffer.size()); 616 } 617 return *this; 618 } 619 620 OptionalDiagnostic &operator<<(const APFloat &F) { 621 if (Diag) { 622 // FIXME: Force the precision of the source value down so we don't 623 // print digits which are usually useless (we don't really care here if 624 // we truncate a digit by accident in edge cases). Ideally, 625 // APFloat::toString would automatically print the shortest 626 // representation which rounds to the correct value, but it's a bit 627 // tricky to implement. 628 unsigned precision = 629 llvm::APFloat::semanticsPrecision(F.getSemantics()); 630 precision = (precision * 59 + 195) / 196; 631 SmallVector<char, 32> Buffer; 632 F.toString(Buffer, precision); 633 *Diag << StringRef(Buffer.data(), Buffer.size()); 634 } 635 return *this; 636 } 637 638 OptionalDiagnostic &operator<<(const APFixedPoint &FX) { 639 if (Diag) { 640 SmallVector<char, 32> Buffer; 641 FX.toString(Buffer); 642 *Diag << StringRef(Buffer.data(), Buffer.size()); 643 } 644 return *this; 645 } 646 }; 647 648 /// A cleanup, and a flag indicating whether it is lifetime-extended. 649 class Cleanup { 650 llvm::PointerIntPair<APValue*, 1, bool> Value; 651 652 public: 653 Cleanup(APValue *Val, bool IsLifetimeExtended) 654 : Value(Val, IsLifetimeExtended) {} 655 656 bool isLifetimeExtended() const { return Value.getInt(); } 657 void endLifetime() { 658 *Value.getPointer() = APValue(); 659 } 660 }; 661 662 /// A reference to an object whose construction we are currently evaluating. 663 struct ObjectUnderConstruction { 664 APValue::LValueBase Base; 665 ArrayRef<APValue::LValuePathEntry> Path; 666 friend bool operator==(const ObjectUnderConstruction &LHS, 667 const ObjectUnderConstruction &RHS) { 668 return LHS.Base == RHS.Base && LHS.Path == RHS.Path; 669 } 670 friend llvm::hash_code hash_value(const ObjectUnderConstruction &Obj) { 671 return llvm::hash_combine(Obj.Base, Obj.Path); 672 } 673 }; 674 enum class ConstructionPhase { None, Bases, AfterBases }; 675 } 676 677 namespace llvm { 678 template<> struct DenseMapInfo<ObjectUnderConstruction> { 679 using Base = DenseMapInfo<APValue::LValueBase>; 680 static ObjectUnderConstruction getEmptyKey() { 681 return {Base::getEmptyKey(), {}}; } 682 static ObjectUnderConstruction getTombstoneKey() { 683 return {Base::getTombstoneKey(), {}}; 684 } 685 static unsigned getHashValue(const ObjectUnderConstruction &Object) { 686 return hash_value(Object); 687 } 688 static bool isEqual(const ObjectUnderConstruction &LHS, 689 const ObjectUnderConstruction &RHS) { 690 return LHS == RHS; 691 } 692 }; 693 } 694 695 namespace { 696 /// EvalInfo - This is a private struct used by the evaluator to capture 697 /// information about a subexpression as it is folded. It retains information 698 /// about the AST context, but also maintains information about the folded 699 /// expression. 700 /// 701 /// If an expression could be evaluated, it is still possible it is not a C 702 /// "integer constant expression" or constant expression. If not, this struct 703 /// captures information about how and why not. 704 /// 705 /// One bit of information passed *into* the request for constant folding 706 /// indicates whether the subexpression is "evaluated" or not according to C 707 /// rules. For example, the RHS of (0 && foo()) is not evaluated. We can 708 /// evaluate the expression regardless of what the RHS is, but C only allows 709 /// certain things in certain situations. 710 struct EvalInfo { 711 ASTContext &Ctx; 712 713 /// EvalStatus - Contains information about the evaluation. 714 Expr::EvalStatus &EvalStatus; 715 716 /// CurrentCall - The top of the constexpr call stack. 717 CallStackFrame *CurrentCall; 718 719 /// CallStackDepth - The number of calls in the call stack right now. 720 unsigned CallStackDepth; 721 722 /// NextCallIndex - The next call index to assign. 723 unsigned NextCallIndex; 724 725 /// StepsLeft - The remaining number of evaluation steps we're permitted 726 /// to perform. This is essentially a limit for the number of statements 727 /// we will evaluate. 728 unsigned StepsLeft; 729 730 /// BottomFrame - The frame in which evaluation started. This must be 731 /// initialized after CurrentCall and CallStackDepth. 732 CallStackFrame BottomFrame; 733 734 /// A stack of values whose lifetimes end at the end of some surrounding 735 /// evaluation frame. 736 llvm::SmallVector<Cleanup, 16> CleanupStack; 737 738 /// EvaluatingDecl - This is the declaration whose initializer is being 739 /// evaluated, if any. 740 APValue::LValueBase EvaluatingDecl; 741 742 /// EvaluatingDeclValue - This is the value being constructed for the 743 /// declaration whose initializer is being evaluated, if any. 744 APValue *EvaluatingDeclValue; 745 746 /// Set of objects that are currently being constructed. 747 llvm::DenseMap<ObjectUnderConstruction, ConstructionPhase> 748 ObjectsUnderConstruction; 749 750 struct EvaluatingConstructorRAII { 751 EvalInfo &EI; 752 ObjectUnderConstruction Object; 753 bool DidInsert; 754 EvaluatingConstructorRAII(EvalInfo &EI, ObjectUnderConstruction Object, 755 bool HasBases) 756 : EI(EI), Object(Object) { 757 DidInsert = 758 EI.ObjectsUnderConstruction 759 .insert({Object, HasBases ? ConstructionPhase::Bases 760 : ConstructionPhase::AfterBases}) 761 .second; 762 } 763 void finishedConstructingBases() { 764 EI.ObjectsUnderConstruction[Object] = ConstructionPhase::AfterBases; 765 } 766 ~EvaluatingConstructorRAII() { 767 if (DidInsert) EI.ObjectsUnderConstruction.erase(Object); 768 } 769 }; 770 771 ConstructionPhase 772 isEvaluatingConstructor(APValue::LValueBase Base, 773 ArrayRef<APValue::LValuePathEntry> Path) { 774 return ObjectsUnderConstruction.lookup({Base, Path}); 775 } 776 777 /// If we're currently speculatively evaluating, the outermost call stack 778 /// depth at which we can mutate state, otherwise 0. 779 unsigned SpeculativeEvaluationDepth = 0; 780 781 /// The current array initialization index, if we're performing array 782 /// initialization. 783 uint64_t ArrayInitIndex = -1; 784 785 /// HasActiveDiagnostic - Was the previous diagnostic stored? If so, further 786 /// notes attached to it will also be stored, otherwise they will not be. 787 bool HasActiveDiagnostic; 788 789 /// Have we emitted a diagnostic explaining why we couldn't constant 790 /// fold (not just why it's not strictly a constant expression)? 791 bool HasFoldFailureDiagnostic; 792 793 /// Whether or not we're in a context where the front end requires a 794 /// constant value. 795 bool InConstantContext; 796 797 /// Whether we're checking that an expression is a potential constant 798 /// expression. If so, do not fail on constructs that could become constant 799 /// later on (such as a use of an undefined global). 800 bool CheckingPotentialConstantExpression = false; 801 802 /// Whether we're checking for an expression that has undefined behavior. 803 /// If so, we will produce warnings if we encounter an operation that is 804 /// always undefined. 805 bool CheckingForUndefinedBehavior = false; 806 807 enum EvaluationMode { 808 /// Evaluate as a constant expression. Stop if we find that the expression 809 /// is not a constant expression. 810 EM_ConstantExpression, 811 812 /// Evaluate as a constant expression. Stop if we find that the expression 813 /// is not a constant expression. Some expressions can be retried in the 814 /// optimizer if we don't constant fold them here, but in an unevaluated 815 /// context we try to fold them immediately since the optimizer never 816 /// gets a chance to look at it. 817 EM_ConstantExpressionUnevaluated, 818 819 /// Fold the expression to a constant. Stop if we hit a side-effect that 820 /// we can't model. 821 EM_ConstantFold, 822 823 /// Evaluate in any way we know how. Don't worry about side-effects that 824 /// can't be modeled. 825 EM_IgnoreSideEffects, 826 } EvalMode; 827 828 /// Are we checking whether the expression is a potential constant 829 /// expression? 830 bool checkingPotentialConstantExpression() const { 831 return CheckingPotentialConstantExpression; 832 } 833 834 /// Are we checking an expression for overflow? 835 // FIXME: We should check for any kind of undefined or suspicious behavior 836 // in such constructs, not just overflow. 837 bool checkingForUndefinedBehavior() { return CheckingForUndefinedBehavior; } 838 839 EvalInfo(const ASTContext &C, Expr::EvalStatus &S, EvaluationMode Mode) 840 : Ctx(const_cast<ASTContext &>(C)), EvalStatus(S), CurrentCall(nullptr), 841 CallStackDepth(0), NextCallIndex(1), 842 StepsLeft(getLangOpts().ConstexprStepLimit), 843 BottomFrame(*this, SourceLocation(), nullptr, nullptr, nullptr), 844 EvaluatingDecl((const ValueDecl *)nullptr), 845 EvaluatingDeclValue(nullptr), HasActiveDiagnostic(false), 846 HasFoldFailureDiagnostic(false), 847 InConstantContext(false), EvalMode(Mode) {} 848 849 void setEvaluatingDecl(APValue::LValueBase Base, APValue &Value) { 850 EvaluatingDecl = Base; 851 EvaluatingDeclValue = &Value; 852 } 853 854 const LangOptions &getLangOpts() const { return Ctx.getLangOpts(); } 855 856 bool CheckCallLimit(SourceLocation Loc) { 857 // Don't perform any constexpr calls (other than the call we're checking) 858 // when checking a potential constant expression. 859 if (checkingPotentialConstantExpression() && CallStackDepth > 1) 860 return false; 861 if (NextCallIndex == 0) { 862 // NextCallIndex has wrapped around. 863 FFDiag(Loc, diag::note_constexpr_call_limit_exceeded); 864 return false; 865 } 866 if (CallStackDepth <= getLangOpts().ConstexprCallDepth) 867 return true; 868 FFDiag(Loc, diag::note_constexpr_depth_limit_exceeded) 869 << getLangOpts().ConstexprCallDepth; 870 return false; 871 } 872 873 std::pair<CallStackFrame *, unsigned> 874 getCallFrameAndDepth(unsigned CallIndex) { 875 assert(CallIndex && "no call index in getCallFrameAndDepth"); 876 // We will eventually hit BottomFrame, which has Index 1, so Frame can't 877 // be null in this loop. 878 unsigned Depth = CallStackDepth; 879 CallStackFrame *Frame = CurrentCall; 880 while (Frame->Index > CallIndex) { 881 Frame = Frame->Caller; 882 --Depth; 883 } 884 if (Frame->Index == CallIndex) 885 return {Frame, Depth}; 886 return {nullptr, 0}; 887 } 888 889 bool nextStep(const Stmt *S) { 890 if (!StepsLeft) { 891 FFDiag(S->getBeginLoc(), diag::note_constexpr_step_limit_exceeded); 892 return false; 893 } 894 --StepsLeft; 895 return true; 896 } 897 898 private: 899 /// Add a diagnostic to the diagnostics list. 900 PartialDiagnostic &addDiag(SourceLocation Loc, diag::kind DiagId) { 901 PartialDiagnostic PD(DiagId, Ctx.getDiagAllocator()); 902 EvalStatus.Diag->push_back(std::make_pair(Loc, PD)); 903 return EvalStatus.Diag->back().second; 904 } 905 906 /// Add notes containing a call stack to the current point of evaluation. 907 void addCallStack(unsigned Limit); 908 909 private: 910 OptionalDiagnostic Diag(SourceLocation Loc, diag::kind DiagId, 911 unsigned ExtraNotes, bool IsCCEDiag) { 912 913 if (EvalStatus.Diag) { 914 // If we have a prior diagnostic, it will be noting that the expression 915 // isn't a constant expression. This diagnostic is more important, 916 // unless we require this evaluation to produce a constant expression. 917 // 918 // FIXME: We might want to show both diagnostics to the user in 919 // EM_ConstantFold mode. 920 if (!EvalStatus.Diag->empty()) { 921 switch (EvalMode) { 922 case EM_ConstantFold: 923 case EM_IgnoreSideEffects: 924 if (!HasFoldFailureDiagnostic) 925 break; 926 // We've already failed to fold something. Keep that diagnostic. 927 LLVM_FALLTHROUGH; 928 case EM_ConstantExpression: 929 case EM_ConstantExpressionUnevaluated: 930 HasActiveDiagnostic = false; 931 return OptionalDiagnostic(); 932 } 933 } 934 935 unsigned CallStackNotes = CallStackDepth - 1; 936 unsigned Limit = Ctx.getDiagnostics().getConstexprBacktraceLimit(); 937 if (Limit) 938 CallStackNotes = std::min(CallStackNotes, Limit + 1); 939 if (checkingPotentialConstantExpression()) 940 CallStackNotes = 0; 941 942 HasActiveDiagnostic = true; 943 HasFoldFailureDiagnostic = !IsCCEDiag; 944 EvalStatus.Diag->clear(); 945 EvalStatus.Diag->reserve(1 + ExtraNotes + CallStackNotes); 946 addDiag(Loc, DiagId); 947 if (!checkingPotentialConstantExpression()) 948 addCallStack(Limit); 949 return OptionalDiagnostic(&(*EvalStatus.Diag)[0].second); 950 } 951 HasActiveDiagnostic = false; 952 return OptionalDiagnostic(); 953 } 954 public: 955 // Diagnose that the evaluation could not be folded (FF => FoldFailure) 956 OptionalDiagnostic 957 FFDiag(SourceLocation Loc, 958 diag::kind DiagId = diag::note_invalid_subexpr_in_const_expr, 959 unsigned ExtraNotes = 0) { 960 return Diag(Loc, DiagId, ExtraNotes, false); 961 } 962 963 OptionalDiagnostic FFDiag(const Expr *E, diag::kind DiagId 964 = diag::note_invalid_subexpr_in_const_expr, 965 unsigned ExtraNotes = 0) { 966 if (EvalStatus.Diag) 967 return Diag(E->getExprLoc(), DiagId, ExtraNotes, /*IsCCEDiag*/false); 968 HasActiveDiagnostic = false; 969 return OptionalDiagnostic(); 970 } 971 972 /// Diagnose that the evaluation does not produce a C++11 core constant 973 /// expression. 974 /// 975 /// FIXME: Stop evaluating if we're in EM_ConstantExpression mode 976 /// and we produce one of these. 977 OptionalDiagnostic CCEDiag(SourceLocation Loc, diag::kind DiagId 978 = diag::note_invalid_subexpr_in_const_expr, 979 unsigned ExtraNotes = 0) { 980 // Don't override a previous diagnostic. Don't bother collecting 981 // diagnostics if we're evaluating for overflow. 982 if (!EvalStatus.Diag || !EvalStatus.Diag->empty()) { 983 HasActiveDiagnostic = false; 984 return OptionalDiagnostic(); 985 } 986 return Diag(Loc, DiagId, ExtraNotes, true); 987 } 988 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind DiagId 989 = diag::note_invalid_subexpr_in_const_expr, 990 unsigned ExtraNotes = 0) { 991 return CCEDiag(E->getExprLoc(), DiagId, ExtraNotes); 992 } 993 /// Add a note to a prior diagnostic. 994 OptionalDiagnostic Note(SourceLocation Loc, diag::kind DiagId) { 995 if (!HasActiveDiagnostic) 996 return OptionalDiagnostic(); 997 return OptionalDiagnostic(&addDiag(Loc, DiagId)); 998 } 999 1000 /// Add a stack of notes to a prior diagnostic. 1001 void addNotes(ArrayRef<PartialDiagnosticAt> Diags) { 1002 if (HasActiveDiagnostic) { 1003 EvalStatus.Diag->insert(EvalStatus.Diag->end(), 1004 Diags.begin(), Diags.end()); 1005 } 1006 } 1007 1008 /// Should we continue evaluation after encountering a side-effect that we 1009 /// couldn't model? 1010 bool keepEvaluatingAfterSideEffect() { 1011 switch (EvalMode) { 1012 case EM_IgnoreSideEffects: 1013 return true; 1014 1015 case EM_ConstantExpression: 1016 case EM_ConstantExpressionUnevaluated: 1017 case EM_ConstantFold: 1018 // By default, assume any side effect might be valid in some other 1019 // evaluation of this expression from a different context. 1020 return checkingPotentialConstantExpression() || 1021 checkingForUndefinedBehavior(); 1022 } 1023 llvm_unreachable("Missed EvalMode case"); 1024 } 1025 1026 /// Note that we have had a side-effect, and determine whether we should 1027 /// keep evaluating. 1028 bool noteSideEffect() { 1029 EvalStatus.HasSideEffects = true; 1030 return keepEvaluatingAfterSideEffect(); 1031 } 1032 1033 /// Should we continue evaluation after encountering undefined behavior? 1034 bool keepEvaluatingAfterUndefinedBehavior() { 1035 switch (EvalMode) { 1036 case EM_IgnoreSideEffects: 1037 case EM_ConstantFold: 1038 return true; 1039 1040 case EM_ConstantExpression: 1041 case EM_ConstantExpressionUnevaluated: 1042 return checkingForUndefinedBehavior(); 1043 } 1044 llvm_unreachable("Missed EvalMode case"); 1045 } 1046 1047 /// Note that we hit something that was technically undefined behavior, but 1048 /// that we can evaluate past it (such as signed overflow or floating-point 1049 /// division by zero.) 1050 bool noteUndefinedBehavior() { 1051 EvalStatus.HasUndefinedBehavior = true; 1052 return keepEvaluatingAfterUndefinedBehavior(); 1053 } 1054 1055 /// Should we continue evaluation as much as possible after encountering a 1056 /// construct which can't be reduced to a value? 1057 bool keepEvaluatingAfterFailure() { 1058 if (!StepsLeft) 1059 return false; 1060 1061 switch (EvalMode) { 1062 case EM_ConstantExpression: 1063 case EM_ConstantExpressionUnevaluated: 1064 case EM_ConstantFold: 1065 case EM_IgnoreSideEffects: 1066 return checkingPotentialConstantExpression() || 1067 checkingForUndefinedBehavior(); 1068 } 1069 llvm_unreachable("Missed EvalMode case"); 1070 } 1071 1072 /// Notes that we failed to evaluate an expression that other expressions 1073 /// directly depend on, and determine if we should keep evaluating. This 1074 /// should only be called if we actually intend to keep evaluating. 1075 /// 1076 /// Call noteSideEffect() instead if we may be able to ignore the value that 1077 /// we failed to evaluate, e.g. if we failed to evaluate Foo() in: 1078 /// 1079 /// (Foo(), 1) // use noteSideEffect 1080 /// (Foo() || true) // use noteSideEffect 1081 /// Foo() + 1 // use noteFailure 1082 LLVM_NODISCARD bool noteFailure() { 1083 // Failure when evaluating some expression often means there is some 1084 // subexpression whose evaluation was skipped. Therefore, (because we 1085 // don't track whether we skipped an expression when unwinding after an 1086 // evaluation failure) every evaluation failure that bubbles up from a 1087 // subexpression implies that a side-effect has potentially happened. We 1088 // skip setting the HasSideEffects flag to true until we decide to 1089 // continue evaluating after that point, which happens here. 1090 bool KeepGoing = keepEvaluatingAfterFailure(); 1091 EvalStatus.HasSideEffects |= KeepGoing; 1092 return KeepGoing; 1093 } 1094 1095 class ArrayInitLoopIndex { 1096 EvalInfo &Info; 1097 uint64_t OuterIndex; 1098 1099 public: 1100 ArrayInitLoopIndex(EvalInfo &Info) 1101 : Info(Info), OuterIndex(Info.ArrayInitIndex) { 1102 Info.ArrayInitIndex = 0; 1103 } 1104 ~ArrayInitLoopIndex() { Info.ArrayInitIndex = OuterIndex; } 1105 1106 operator uint64_t&() { return Info.ArrayInitIndex; } 1107 }; 1108 }; 1109 1110 /// Object used to treat all foldable expressions as constant expressions. 1111 struct FoldConstant { 1112 EvalInfo &Info; 1113 bool Enabled; 1114 bool HadNoPriorDiags; 1115 EvalInfo::EvaluationMode OldMode; 1116 1117 explicit FoldConstant(EvalInfo &Info, bool Enabled) 1118 : Info(Info), 1119 Enabled(Enabled), 1120 HadNoPriorDiags(Info.EvalStatus.Diag && 1121 Info.EvalStatus.Diag->empty() && 1122 !Info.EvalStatus.HasSideEffects), 1123 OldMode(Info.EvalMode) { 1124 if (Enabled) 1125 Info.EvalMode = EvalInfo::EM_ConstantFold; 1126 } 1127 void keepDiagnostics() { Enabled = false; } 1128 ~FoldConstant() { 1129 if (Enabled && HadNoPriorDiags && !Info.EvalStatus.Diag->empty() && 1130 !Info.EvalStatus.HasSideEffects) 1131 Info.EvalStatus.Diag->clear(); 1132 Info.EvalMode = OldMode; 1133 } 1134 }; 1135 1136 /// RAII object used to set the current evaluation mode to ignore 1137 /// side-effects. 1138 struct IgnoreSideEffectsRAII { 1139 EvalInfo &Info; 1140 EvalInfo::EvaluationMode OldMode; 1141 explicit IgnoreSideEffectsRAII(EvalInfo &Info) 1142 : Info(Info), OldMode(Info.EvalMode) { 1143 Info.EvalMode = EvalInfo::EM_IgnoreSideEffects; 1144 } 1145 1146 ~IgnoreSideEffectsRAII() { Info.EvalMode = OldMode; } 1147 }; 1148 1149 /// RAII object used to optionally suppress diagnostics and side-effects from 1150 /// a speculative evaluation. 1151 class SpeculativeEvaluationRAII { 1152 EvalInfo *Info = nullptr; 1153 Expr::EvalStatus OldStatus; 1154 unsigned OldSpeculativeEvaluationDepth; 1155 1156 void moveFromAndCancel(SpeculativeEvaluationRAII &&Other) { 1157 Info = Other.Info; 1158 OldStatus = Other.OldStatus; 1159 OldSpeculativeEvaluationDepth = Other.OldSpeculativeEvaluationDepth; 1160 Other.Info = nullptr; 1161 } 1162 1163 void maybeRestoreState() { 1164 if (!Info) 1165 return; 1166 1167 Info->EvalStatus = OldStatus; 1168 Info->SpeculativeEvaluationDepth = OldSpeculativeEvaluationDepth; 1169 } 1170 1171 public: 1172 SpeculativeEvaluationRAII() = default; 1173 1174 SpeculativeEvaluationRAII( 1175 EvalInfo &Info, SmallVectorImpl<PartialDiagnosticAt> *NewDiag = nullptr) 1176 : Info(&Info), OldStatus(Info.EvalStatus), 1177 OldSpeculativeEvaluationDepth(Info.SpeculativeEvaluationDepth) { 1178 Info.EvalStatus.Diag = NewDiag; 1179 Info.SpeculativeEvaluationDepth = Info.CallStackDepth + 1; 1180 } 1181 1182 SpeculativeEvaluationRAII(const SpeculativeEvaluationRAII &Other) = delete; 1183 SpeculativeEvaluationRAII(SpeculativeEvaluationRAII &&Other) { 1184 moveFromAndCancel(std::move(Other)); 1185 } 1186 1187 SpeculativeEvaluationRAII &operator=(SpeculativeEvaluationRAII &&Other) { 1188 maybeRestoreState(); 1189 moveFromAndCancel(std::move(Other)); 1190 return *this; 1191 } 1192 1193 ~SpeculativeEvaluationRAII() { maybeRestoreState(); } 1194 }; 1195 1196 /// RAII object wrapping a full-expression or block scope, and handling 1197 /// the ending of the lifetime of temporaries created within it. 1198 template<bool IsFullExpression> 1199 class ScopeRAII { 1200 EvalInfo &Info; 1201 unsigned OldStackSize; 1202 public: 1203 ScopeRAII(EvalInfo &Info) 1204 : Info(Info), OldStackSize(Info.CleanupStack.size()) { 1205 // Push a new temporary version. This is needed to distinguish between 1206 // temporaries created in different iterations of a loop. 1207 Info.CurrentCall->pushTempVersion(); 1208 } 1209 ~ScopeRAII() { 1210 // Body moved to a static method to encourage the compiler to inline away 1211 // instances of this class. 1212 cleanup(Info, OldStackSize); 1213 Info.CurrentCall->popTempVersion(); 1214 } 1215 private: 1216 static void cleanup(EvalInfo &Info, unsigned OldStackSize) { 1217 unsigned NewEnd = OldStackSize; 1218 for (unsigned I = OldStackSize, N = Info.CleanupStack.size(); 1219 I != N; ++I) { 1220 if (IsFullExpression && Info.CleanupStack[I].isLifetimeExtended()) { 1221 // Full-expression cleanup of a lifetime-extended temporary: nothing 1222 // to do, just move this cleanup to the right place in the stack. 1223 std::swap(Info.CleanupStack[I], Info.CleanupStack[NewEnd]); 1224 ++NewEnd; 1225 } else { 1226 // End the lifetime of the object. 1227 Info.CleanupStack[I].endLifetime(); 1228 } 1229 } 1230 Info.CleanupStack.erase(Info.CleanupStack.begin() + NewEnd, 1231 Info.CleanupStack.end()); 1232 } 1233 }; 1234 typedef ScopeRAII<false> BlockScopeRAII; 1235 typedef ScopeRAII<true> FullExpressionRAII; 1236 } 1237 1238 bool SubobjectDesignator::checkSubobject(EvalInfo &Info, const Expr *E, 1239 CheckSubobjectKind CSK) { 1240 if (Invalid) 1241 return false; 1242 if (isOnePastTheEnd()) { 1243 Info.CCEDiag(E, diag::note_constexpr_past_end_subobject) 1244 << CSK; 1245 setInvalid(); 1246 return false; 1247 } 1248 // Note, we do not diagnose if isMostDerivedAnUnsizedArray(), because there 1249 // must actually be at least one array element; even a VLA cannot have a 1250 // bound of zero. And if our index is nonzero, we already had a CCEDiag. 1251 return true; 1252 } 1253 1254 void SubobjectDesignator::diagnoseUnsizedArrayPointerArithmetic(EvalInfo &Info, 1255 const Expr *E) { 1256 Info.CCEDiag(E, diag::note_constexpr_unsized_array_indexed); 1257 // Do not set the designator as invalid: we can represent this situation, 1258 // and correct handling of __builtin_object_size requires us to do so. 1259 } 1260 1261 void SubobjectDesignator::diagnosePointerArithmetic(EvalInfo &Info, 1262 const Expr *E, 1263 const APSInt &N) { 1264 // If we're complaining, we must be able to statically determine the size of 1265 // the most derived array. 1266 if (MostDerivedPathLength == Entries.size() && MostDerivedIsArrayElement) 1267 Info.CCEDiag(E, diag::note_constexpr_array_index) 1268 << N << /*array*/ 0 1269 << static_cast<unsigned>(getMostDerivedArraySize()); 1270 else 1271 Info.CCEDiag(E, diag::note_constexpr_array_index) 1272 << N << /*non-array*/ 1; 1273 setInvalid(); 1274 } 1275 1276 CallStackFrame::CallStackFrame(EvalInfo &Info, SourceLocation CallLoc, 1277 const FunctionDecl *Callee, const LValue *This, 1278 APValue *Arguments) 1279 : Info(Info), Caller(Info.CurrentCall), Callee(Callee), This(This), 1280 Arguments(Arguments), CallLoc(CallLoc), Index(Info.NextCallIndex++) { 1281 Info.CurrentCall = this; 1282 ++Info.CallStackDepth; 1283 } 1284 1285 CallStackFrame::~CallStackFrame() { 1286 assert(Info.CurrentCall == this && "calls retired out of order"); 1287 --Info.CallStackDepth; 1288 Info.CurrentCall = Caller; 1289 } 1290 1291 APValue &CallStackFrame::createTemporary(const void *Key, 1292 bool IsLifetimeExtended) { 1293 unsigned Version = Info.CurrentCall->getTempVersion(); 1294 APValue &Result = Temporaries[MapKeyTy(Key, Version)]; 1295 assert(Result.isAbsent() && "temporary created multiple times"); 1296 Info.CleanupStack.push_back(Cleanup(&Result, IsLifetimeExtended)); 1297 return Result; 1298 } 1299 1300 static void describeCall(CallStackFrame *Frame, raw_ostream &Out); 1301 1302 void EvalInfo::addCallStack(unsigned Limit) { 1303 // Determine which calls to skip, if any. 1304 unsigned ActiveCalls = CallStackDepth - 1; 1305 unsigned SkipStart = ActiveCalls, SkipEnd = SkipStart; 1306 if (Limit && Limit < ActiveCalls) { 1307 SkipStart = Limit / 2 + Limit % 2; 1308 SkipEnd = ActiveCalls - Limit / 2; 1309 } 1310 1311 // Walk the call stack and add the diagnostics. 1312 unsigned CallIdx = 0; 1313 for (CallStackFrame *Frame = CurrentCall; Frame != &BottomFrame; 1314 Frame = Frame->Caller, ++CallIdx) { 1315 // Skip this call? 1316 if (CallIdx >= SkipStart && CallIdx < SkipEnd) { 1317 if (CallIdx == SkipStart) { 1318 // Note that we're skipping calls. 1319 addDiag(Frame->CallLoc, diag::note_constexpr_calls_suppressed) 1320 << unsigned(ActiveCalls - Limit); 1321 } 1322 continue; 1323 } 1324 1325 // Use a different note for an inheriting constructor, because from the 1326 // user's perspective it's not really a function at all. 1327 if (auto *CD = dyn_cast_or_null<CXXConstructorDecl>(Frame->Callee)) { 1328 if (CD->isInheritingConstructor()) { 1329 addDiag(Frame->CallLoc, diag::note_constexpr_inherited_ctor_call_here) 1330 << CD->getParent(); 1331 continue; 1332 } 1333 } 1334 1335 SmallVector<char, 128> Buffer; 1336 llvm::raw_svector_ostream Out(Buffer); 1337 describeCall(Frame, Out); 1338 addDiag(Frame->CallLoc, diag::note_constexpr_call_here) << Out.str(); 1339 } 1340 } 1341 1342 /// Kinds of access we can perform on an object, for diagnostics. Note that 1343 /// we consider a member function call to be a kind of access, even though 1344 /// it is not formally an access of the object, because it has (largely) the 1345 /// same set of semantic restrictions. 1346 enum AccessKinds { 1347 AK_Read, 1348 AK_Assign, 1349 AK_Increment, 1350 AK_Decrement, 1351 AK_MemberCall, 1352 AK_DynamicCast, 1353 AK_TypeId, 1354 }; 1355 1356 static bool isModification(AccessKinds AK) { 1357 switch (AK) { 1358 case AK_Read: 1359 case AK_MemberCall: 1360 case AK_DynamicCast: 1361 case AK_TypeId: 1362 return false; 1363 case AK_Assign: 1364 case AK_Increment: 1365 case AK_Decrement: 1366 return true; 1367 } 1368 llvm_unreachable("unknown access kind"); 1369 } 1370 1371 /// Is this an access per the C++ definition? 1372 static bool isFormalAccess(AccessKinds AK) { 1373 return AK == AK_Read || isModification(AK); 1374 } 1375 1376 namespace { 1377 struct ComplexValue { 1378 private: 1379 bool IsInt; 1380 1381 public: 1382 APSInt IntReal, IntImag; 1383 APFloat FloatReal, FloatImag; 1384 1385 ComplexValue() : FloatReal(APFloat::Bogus()), FloatImag(APFloat::Bogus()) {} 1386 1387 void makeComplexFloat() { IsInt = false; } 1388 bool isComplexFloat() const { return !IsInt; } 1389 APFloat &getComplexFloatReal() { return FloatReal; } 1390 APFloat &getComplexFloatImag() { return FloatImag; } 1391 1392 void makeComplexInt() { IsInt = true; } 1393 bool isComplexInt() const { return IsInt; } 1394 APSInt &getComplexIntReal() { return IntReal; } 1395 APSInt &getComplexIntImag() { return IntImag; } 1396 1397 void moveInto(APValue &v) const { 1398 if (isComplexFloat()) 1399 v = APValue(FloatReal, FloatImag); 1400 else 1401 v = APValue(IntReal, IntImag); 1402 } 1403 void setFrom(const APValue &v) { 1404 assert(v.isComplexFloat() || v.isComplexInt()); 1405 if (v.isComplexFloat()) { 1406 makeComplexFloat(); 1407 FloatReal = v.getComplexFloatReal(); 1408 FloatImag = v.getComplexFloatImag(); 1409 } else { 1410 makeComplexInt(); 1411 IntReal = v.getComplexIntReal(); 1412 IntImag = v.getComplexIntImag(); 1413 } 1414 } 1415 }; 1416 1417 struct LValue { 1418 APValue::LValueBase Base; 1419 CharUnits Offset; 1420 SubobjectDesignator Designator; 1421 bool IsNullPtr : 1; 1422 bool InvalidBase : 1; 1423 1424 const APValue::LValueBase getLValueBase() const { return Base; } 1425 CharUnits &getLValueOffset() { return Offset; } 1426 const CharUnits &getLValueOffset() const { return Offset; } 1427 SubobjectDesignator &getLValueDesignator() { return Designator; } 1428 const SubobjectDesignator &getLValueDesignator() const { return Designator;} 1429 bool isNullPointer() const { return IsNullPtr;} 1430 1431 unsigned getLValueCallIndex() const { return Base.getCallIndex(); } 1432 unsigned getLValueVersion() const { return Base.getVersion(); } 1433 1434 void moveInto(APValue &V) const { 1435 if (Designator.Invalid) 1436 V = APValue(Base, Offset, APValue::NoLValuePath(), IsNullPtr); 1437 else { 1438 assert(!InvalidBase && "APValues can't handle invalid LValue bases"); 1439 V = APValue(Base, Offset, Designator.Entries, 1440 Designator.IsOnePastTheEnd, IsNullPtr); 1441 } 1442 } 1443 void setFrom(ASTContext &Ctx, const APValue &V) { 1444 assert(V.isLValue() && "Setting LValue from a non-LValue?"); 1445 Base = V.getLValueBase(); 1446 Offset = V.getLValueOffset(); 1447 InvalidBase = false; 1448 Designator = SubobjectDesignator(Ctx, V); 1449 IsNullPtr = V.isNullPointer(); 1450 } 1451 1452 void set(APValue::LValueBase B, bool BInvalid = false) { 1453 #ifndef NDEBUG 1454 // We only allow a few types of invalid bases. Enforce that here. 1455 if (BInvalid) { 1456 const auto *E = B.get<const Expr *>(); 1457 assert((isa<MemberExpr>(E) || tryUnwrapAllocSizeCall(E)) && 1458 "Unexpected type of invalid base"); 1459 } 1460 #endif 1461 1462 Base = B; 1463 Offset = CharUnits::fromQuantity(0); 1464 InvalidBase = BInvalid; 1465 Designator = SubobjectDesignator(getType(B)); 1466 IsNullPtr = false; 1467 } 1468 1469 void setNull(QualType PointerTy, uint64_t TargetVal) { 1470 Base = (Expr *)nullptr; 1471 Offset = CharUnits::fromQuantity(TargetVal); 1472 InvalidBase = false; 1473 Designator = SubobjectDesignator(PointerTy->getPointeeType()); 1474 IsNullPtr = true; 1475 } 1476 1477 void setInvalid(APValue::LValueBase B, unsigned I = 0) { 1478 set(B, true); 1479 } 1480 1481 private: 1482 // Check that this LValue is not based on a null pointer. If it is, produce 1483 // a diagnostic and mark the designator as invalid. 1484 template <typename GenDiagType> 1485 bool checkNullPointerDiagnosingWith(const GenDiagType &GenDiag) { 1486 if (Designator.Invalid) 1487 return false; 1488 if (IsNullPtr) { 1489 GenDiag(); 1490 Designator.setInvalid(); 1491 return false; 1492 } 1493 return true; 1494 } 1495 1496 public: 1497 bool checkNullPointer(EvalInfo &Info, const Expr *E, 1498 CheckSubobjectKind CSK) { 1499 return checkNullPointerDiagnosingWith([&Info, E, CSK] { 1500 Info.CCEDiag(E, diag::note_constexpr_null_subobject) << CSK; 1501 }); 1502 } 1503 1504 bool checkNullPointerForFoldAccess(EvalInfo &Info, const Expr *E, 1505 AccessKinds AK) { 1506 return checkNullPointerDiagnosingWith([&Info, E, AK] { 1507 Info.FFDiag(E, diag::note_constexpr_access_null) << AK; 1508 }); 1509 } 1510 1511 // Check this LValue refers to an object. If not, set the designator to be 1512 // invalid and emit a diagnostic. 1513 bool checkSubobject(EvalInfo &Info, const Expr *E, CheckSubobjectKind CSK) { 1514 return (CSK == CSK_ArrayToPointer || checkNullPointer(Info, E, CSK)) && 1515 Designator.checkSubobject(Info, E, CSK); 1516 } 1517 1518 void addDecl(EvalInfo &Info, const Expr *E, 1519 const Decl *D, bool Virtual = false) { 1520 if (checkSubobject(Info, E, isa<FieldDecl>(D) ? CSK_Field : CSK_Base)) 1521 Designator.addDeclUnchecked(D, Virtual); 1522 } 1523 void addUnsizedArray(EvalInfo &Info, const Expr *E, QualType ElemTy) { 1524 if (!Designator.Entries.empty()) { 1525 Info.CCEDiag(E, diag::note_constexpr_unsupported_unsized_array); 1526 Designator.setInvalid(); 1527 return; 1528 } 1529 if (checkSubobject(Info, E, CSK_ArrayToPointer)) { 1530 assert(getType(Base)->isPointerType() || getType(Base)->isArrayType()); 1531 Designator.FirstEntryIsAnUnsizedArray = true; 1532 Designator.addUnsizedArrayUnchecked(ElemTy); 1533 } 1534 } 1535 void addArray(EvalInfo &Info, const Expr *E, const ConstantArrayType *CAT) { 1536 if (checkSubobject(Info, E, CSK_ArrayToPointer)) 1537 Designator.addArrayUnchecked(CAT); 1538 } 1539 void addComplex(EvalInfo &Info, const Expr *E, QualType EltTy, bool Imag) { 1540 if (checkSubobject(Info, E, Imag ? CSK_Imag : CSK_Real)) 1541 Designator.addComplexUnchecked(EltTy, Imag); 1542 } 1543 void clearIsNullPointer() { 1544 IsNullPtr = false; 1545 } 1546 void adjustOffsetAndIndex(EvalInfo &Info, const Expr *E, 1547 const APSInt &Index, CharUnits ElementSize) { 1548 // An index of 0 has no effect. (In C, adding 0 to a null pointer is UB, 1549 // but we're not required to diagnose it and it's valid in C++.) 1550 if (!Index) 1551 return; 1552 1553 // Compute the new offset in the appropriate width, wrapping at 64 bits. 1554 // FIXME: When compiling for a 32-bit target, we should use 32-bit 1555 // offsets. 1556 uint64_t Offset64 = Offset.getQuantity(); 1557 uint64_t ElemSize64 = ElementSize.getQuantity(); 1558 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue(); 1559 Offset = CharUnits::fromQuantity(Offset64 + ElemSize64 * Index64); 1560 1561 if (checkNullPointer(Info, E, CSK_ArrayIndex)) 1562 Designator.adjustIndex(Info, E, Index); 1563 clearIsNullPointer(); 1564 } 1565 void adjustOffset(CharUnits N) { 1566 Offset += N; 1567 if (N.getQuantity()) 1568 clearIsNullPointer(); 1569 } 1570 }; 1571 1572 struct MemberPtr { 1573 MemberPtr() {} 1574 explicit MemberPtr(const ValueDecl *Decl) : 1575 DeclAndIsDerivedMember(Decl, false), Path() {} 1576 1577 /// The member or (direct or indirect) field referred to by this member 1578 /// pointer, or 0 if this is a null member pointer. 1579 const ValueDecl *getDecl() const { 1580 return DeclAndIsDerivedMember.getPointer(); 1581 } 1582 /// Is this actually a member of some type derived from the relevant class? 1583 bool isDerivedMember() const { 1584 return DeclAndIsDerivedMember.getInt(); 1585 } 1586 /// Get the class which the declaration actually lives in. 1587 const CXXRecordDecl *getContainingRecord() const { 1588 return cast<CXXRecordDecl>( 1589 DeclAndIsDerivedMember.getPointer()->getDeclContext()); 1590 } 1591 1592 void moveInto(APValue &V) const { 1593 V = APValue(getDecl(), isDerivedMember(), Path); 1594 } 1595 void setFrom(const APValue &V) { 1596 assert(V.isMemberPointer()); 1597 DeclAndIsDerivedMember.setPointer(V.getMemberPointerDecl()); 1598 DeclAndIsDerivedMember.setInt(V.isMemberPointerToDerivedMember()); 1599 Path.clear(); 1600 ArrayRef<const CXXRecordDecl*> P = V.getMemberPointerPath(); 1601 Path.insert(Path.end(), P.begin(), P.end()); 1602 } 1603 1604 /// DeclAndIsDerivedMember - The member declaration, and a flag indicating 1605 /// whether the member is a member of some class derived from the class type 1606 /// of the member pointer. 1607 llvm::PointerIntPair<const ValueDecl*, 1, bool> DeclAndIsDerivedMember; 1608 /// Path - The path of base/derived classes from the member declaration's 1609 /// class (exclusive) to the class type of the member pointer (inclusive). 1610 SmallVector<const CXXRecordDecl*, 4> Path; 1611 1612 /// Perform a cast towards the class of the Decl (either up or down the 1613 /// hierarchy). 1614 bool castBack(const CXXRecordDecl *Class) { 1615 assert(!Path.empty()); 1616 const CXXRecordDecl *Expected; 1617 if (Path.size() >= 2) 1618 Expected = Path[Path.size() - 2]; 1619 else 1620 Expected = getContainingRecord(); 1621 if (Expected->getCanonicalDecl() != Class->getCanonicalDecl()) { 1622 // C++11 [expr.static.cast]p12: In a conversion from (D::*) to (B::*), 1623 // if B does not contain the original member and is not a base or 1624 // derived class of the class containing the original member, the result 1625 // of the cast is undefined. 1626 // C++11 [conv.mem]p2 does not cover this case for a cast from (B::*) to 1627 // (D::*). We consider that to be a language defect. 1628 return false; 1629 } 1630 Path.pop_back(); 1631 return true; 1632 } 1633 /// Perform a base-to-derived member pointer cast. 1634 bool castToDerived(const CXXRecordDecl *Derived) { 1635 if (!getDecl()) 1636 return true; 1637 if (!isDerivedMember()) { 1638 Path.push_back(Derived); 1639 return true; 1640 } 1641 if (!castBack(Derived)) 1642 return false; 1643 if (Path.empty()) 1644 DeclAndIsDerivedMember.setInt(false); 1645 return true; 1646 } 1647 /// Perform a derived-to-base member pointer cast. 1648 bool castToBase(const CXXRecordDecl *Base) { 1649 if (!getDecl()) 1650 return true; 1651 if (Path.empty()) 1652 DeclAndIsDerivedMember.setInt(true); 1653 if (isDerivedMember()) { 1654 Path.push_back(Base); 1655 return true; 1656 } 1657 return castBack(Base); 1658 } 1659 }; 1660 1661 /// Compare two member pointers, which are assumed to be of the same type. 1662 static bool operator==(const MemberPtr &LHS, const MemberPtr &RHS) { 1663 if (!LHS.getDecl() || !RHS.getDecl()) 1664 return !LHS.getDecl() && !RHS.getDecl(); 1665 if (LHS.getDecl()->getCanonicalDecl() != RHS.getDecl()->getCanonicalDecl()) 1666 return false; 1667 return LHS.Path == RHS.Path; 1668 } 1669 } 1670 1671 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E); 1672 static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, 1673 const LValue &This, const Expr *E, 1674 bool AllowNonLiteralTypes = false); 1675 static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info, 1676 bool InvalidBaseOK = false); 1677 static bool EvaluatePointer(const Expr *E, LValue &Result, EvalInfo &Info, 1678 bool InvalidBaseOK = false); 1679 static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, 1680 EvalInfo &Info); 1681 static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info); 1682 static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info); 1683 static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, 1684 EvalInfo &Info); 1685 static bool EvaluateFloat(const Expr *E, APFloat &Result, EvalInfo &Info); 1686 static bool EvaluateComplex(const Expr *E, ComplexValue &Res, EvalInfo &Info); 1687 static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result, 1688 EvalInfo &Info); 1689 static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result); 1690 1691 /// Evaluate an integer or fixed point expression into an APResult. 1692 static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result, 1693 EvalInfo &Info); 1694 1695 /// Evaluate only a fixed point expression into an APResult. 1696 static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result, 1697 EvalInfo &Info); 1698 1699 //===----------------------------------------------------------------------===// 1700 // Misc utilities 1701 //===----------------------------------------------------------------------===// 1702 1703 /// A helper function to create a temporary and set an LValue. 1704 template <class KeyTy> 1705 static APValue &createTemporary(const KeyTy *Key, bool IsLifetimeExtended, 1706 LValue &LV, CallStackFrame &Frame) { 1707 LV.set({Key, Frame.Info.CurrentCall->Index, 1708 Frame.Info.CurrentCall->getTempVersion()}); 1709 return Frame.createTemporary(Key, IsLifetimeExtended); 1710 } 1711 1712 /// Negate an APSInt in place, converting it to a signed form if necessary, and 1713 /// preserving its value (by extending by up to one bit as needed). 1714 static void negateAsSigned(APSInt &Int) { 1715 if (Int.isUnsigned() || Int.isMinSignedValue()) { 1716 Int = Int.extend(Int.getBitWidth() + 1); 1717 Int.setIsSigned(true); 1718 } 1719 Int = -Int; 1720 } 1721 1722 /// Produce a string describing the given constexpr call. 1723 static void describeCall(CallStackFrame *Frame, raw_ostream &Out) { 1724 unsigned ArgIndex = 0; 1725 bool IsMemberCall = isa<CXXMethodDecl>(Frame->Callee) && 1726 !isa<CXXConstructorDecl>(Frame->Callee) && 1727 cast<CXXMethodDecl>(Frame->Callee)->isInstance(); 1728 1729 if (!IsMemberCall) 1730 Out << *Frame->Callee << '('; 1731 1732 if (Frame->This && IsMemberCall) { 1733 APValue Val; 1734 Frame->This->moveInto(Val); 1735 Val.printPretty(Out, Frame->Info.Ctx, 1736 Frame->This->Designator.MostDerivedType); 1737 // FIXME: Add parens around Val if needed. 1738 Out << "->" << *Frame->Callee << '('; 1739 IsMemberCall = false; 1740 } 1741 1742 for (FunctionDecl::param_const_iterator I = Frame->Callee->param_begin(), 1743 E = Frame->Callee->param_end(); I != E; ++I, ++ArgIndex) { 1744 if (ArgIndex > (unsigned)IsMemberCall) 1745 Out << ", "; 1746 1747 const ParmVarDecl *Param = *I; 1748 const APValue &Arg = Frame->Arguments[ArgIndex]; 1749 Arg.printPretty(Out, Frame->Info.Ctx, Param->getType()); 1750 1751 if (ArgIndex == 0 && IsMemberCall) 1752 Out << "->" << *Frame->Callee << '('; 1753 } 1754 1755 Out << ')'; 1756 } 1757 1758 /// Evaluate an expression to see if it had side-effects, and discard its 1759 /// result. 1760 /// \return \c true if the caller should keep evaluating. 1761 static bool EvaluateIgnoredValue(EvalInfo &Info, const Expr *E) { 1762 APValue Scratch; 1763 if (!Evaluate(Scratch, Info, E)) 1764 // We don't need the value, but we might have skipped a side effect here. 1765 return Info.noteSideEffect(); 1766 return true; 1767 } 1768 1769 /// Should this call expression be treated as a string literal? 1770 static bool IsStringLiteralCall(const CallExpr *E) { 1771 unsigned Builtin = E->getBuiltinCallee(); 1772 return (Builtin == Builtin::BI__builtin___CFStringMakeConstantString || 1773 Builtin == Builtin::BI__builtin___NSStringMakeConstantString); 1774 } 1775 1776 static bool IsGlobalLValue(APValue::LValueBase B) { 1777 // C++11 [expr.const]p3 An address constant expression is a prvalue core 1778 // constant expression of pointer type that evaluates to... 1779 1780 // ... a null pointer value, or a prvalue core constant expression of type 1781 // std::nullptr_t. 1782 if (!B) return true; 1783 1784 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { 1785 // ... the address of an object with static storage duration, 1786 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 1787 return VD->hasGlobalStorage(); 1788 // ... the address of a function, 1789 return isa<FunctionDecl>(D); 1790 } 1791 1792 if (B.is<TypeInfoLValue>()) 1793 return true; 1794 1795 const Expr *E = B.get<const Expr*>(); 1796 switch (E->getStmtClass()) { 1797 default: 1798 return false; 1799 case Expr::CompoundLiteralExprClass: { 1800 const CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); 1801 return CLE->isFileScope() && CLE->isLValue(); 1802 } 1803 case Expr::MaterializeTemporaryExprClass: 1804 // A materialized temporary might have been lifetime-extended to static 1805 // storage duration. 1806 return cast<MaterializeTemporaryExpr>(E)->getStorageDuration() == SD_Static; 1807 // A string literal has static storage duration. 1808 case Expr::StringLiteralClass: 1809 case Expr::PredefinedExprClass: 1810 case Expr::ObjCStringLiteralClass: 1811 case Expr::ObjCEncodeExprClass: 1812 case Expr::CXXUuidofExprClass: 1813 return true; 1814 case Expr::ObjCBoxedExprClass: 1815 return cast<ObjCBoxedExpr>(E)->isExpressibleAsConstantInitializer(); 1816 case Expr::CallExprClass: 1817 return IsStringLiteralCall(cast<CallExpr>(E)); 1818 // For GCC compatibility, &&label has static storage duration. 1819 case Expr::AddrLabelExprClass: 1820 return true; 1821 // A Block literal expression may be used as the initialization value for 1822 // Block variables at global or local static scope. 1823 case Expr::BlockExprClass: 1824 return !cast<BlockExpr>(E)->getBlockDecl()->hasCaptures(); 1825 case Expr::ImplicitValueInitExprClass: 1826 // FIXME: 1827 // We can never form an lvalue with an implicit value initialization as its 1828 // base through expression evaluation, so these only appear in one case: the 1829 // implicit variable declaration we invent when checking whether a constexpr 1830 // constructor can produce a constant expression. We must assume that such 1831 // an expression might be a global lvalue. 1832 return true; 1833 } 1834 } 1835 1836 static const ValueDecl *GetLValueBaseDecl(const LValue &LVal) { 1837 return LVal.Base.dyn_cast<const ValueDecl*>(); 1838 } 1839 1840 static bool IsLiteralLValue(const LValue &Value) { 1841 if (Value.getLValueCallIndex()) 1842 return false; 1843 const Expr *E = Value.Base.dyn_cast<const Expr*>(); 1844 return E && !isa<MaterializeTemporaryExpr>(E); 1845 } 1846 1847 static bool IsWeakLValue(const LValue &Value) { 1848 const ValueDecl *Decl = GetLValueBaseDecl(Value); 1849 return Decl && Decl->isWeak(); 1850 } 1851 1852 static bool isZeroSized(const LValue &Value) { 1853 const ValueDecl *Decl = GetLValueBaseDecl(Value); 1854 if (Decl && isa<VarDecl>(Decl)) { 1855 QualType Ty = Decl->getType(); 1856 if (Ty->isArrayType()) 1857 return Ty->isIncompleteType() || 1858 Decl->getASTContext().getTypeSize(Ty) == 0; 1859 } 1860 return false; 1861 } 1862 1863 static bool HasSameBase(const LValue &A, const LValue &B) { 1864 if (!A.getLValueBase()) 1865 return !B.getLValueBase(); 1866 if (!B.getLValueBase()) 1867 return false; 1868 1869 if (A.getLValueBase().getOpaqueValue() != 1870 B.getLValueBase().getOpaqueValue()) { 1871 const Decl *ADecl = GetLValueBaseDecl(A); 1872 if (!ADecl) 1873 return false; 1874 const Decl *BDecl = GetLValueBaseDecl(B); 1875 if (!BDecl || ADecl->getCanonicalDecl() != BDecl->getCanonicalDecl()) 1876 return false; 1877 } 1878 1879 return IsGlobalLValue(A.getLValueBase()) || 1880 (A.getLValueCallIndex() == B.getLValueCallIndex() && 1881 A.getLValueVersion() == B.getLValueVersion()); 1882 } 1883 1884 static void NoteLValueLocation(EvalInfo &Info, APValue::LValueBase Base) { 1885 assert(Base && "no location for a null lvalue"); 1886 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 1887 if (VD) 1888 Info.Note(VD->getLocation(), diag::note_declared_at); 1889 else if (const Expr *E = Base.dyn_cast<const Expr*>()) 1890 Info.Note(E->getExprLoc(), diag::note_constexpr_temporary_here); 1891 // We have no information to show for a typeid(T) object. 1892 } 1893 1894 /// Check that this reference or pointer core constant expression is a valid 1895 /// value for an address or reference constant expression. Return true if we 1896 /// can fold this expression, whether or not it's a constant expression. 1897 static bool CheckLValueConstantExpression(EvalInfo &Info, SourceLocation Loc, 1898 QualType Type, const LValue &LVal, 1899 Expr::ConstExprUsage Usage) { 1900 bool IsReferenceType = Type->isReferenceType(); 1901 1902 APValue::LValueBase Base = LVal.getLValueBase(); 1903 const SubobjectDesignator &Designator = LVal.getLValueDesignator(); 1904 1905 // Check that the object is a global. Note that the fake 'this' object we 1906 // manufacture when checking potential constant expressions is conservatively 1907 // assumed to be global here. 1908 if (!IsGlobalLValue(Base)) { 1909 if (Info.getLangOpts().CPlusPlus11) { 1910 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 1911 Info.FFDiag(Loc, diag::note_constexpr_non_global, 1) 1912 << IsReferenceType << !Designator.Entries.empty() 1913 << !!VD << VD; 1914 NoteLValueLocation(Info, Base); 1915 } else { 1916 Info.FFDiag(Loc); 1917 } 1918 // Don't allow references to temporaries to escape. 1919 return false; 1920 } 1921 assert((Info.checkingPotentialConstantExpression() || 1922 LVal.getLValueCallIndex() == 0) && 1923 "have call index for global lvalue"); 1924 1925 if (const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>()) { 1926 if (const VarDecl *Var = dyn_cast<const VarDecl>(VD)) { 1927 // Check if this is a thread-local variable. 1928 if (Var->getTLSKind()) 1929 return false; 1930 1931 // A dllimport variable never acts like a constant. 1932 if (Usage == Expr::EvaluateForCodeGen && Var->hasAttr<DLLImportAttr>()) 1933 return false; 1934 } 1935 if (const auto *FD = dyn_cast<const FunctionDecl>(VD)) { 1936 // __declspec(dllimport) must be handled very carefully: 1937 // We must never initialize an expression with the thunk in C++. 1938 // Doing otherwise would allow the same id-expression to yield 1939 // different addresses for the same function in different translation 1940 // units. However, this means that we must dynamically initialize the 1941 // expression with the contents of the import address table at runtime. 1942 // 1943 // The C language has no notion of ODR; furthermore, it has no notion of 1944 // dynamic initialization. This means that we are permitted to 1945 // perform initialization with the address of the thunk. 1946 if (Info.getLangOpts().CPlusPlus && Usage == Expr::EvaluateForCodeGen && 1947 FD->hasAttr<DLLImportAttr>()) 1948 return false; 1949 } 1950 } 1951 1952 // Allow address constant expressions to be past-the-end pointers. This is 1953 // an extension: the standard requires them to point to an object. 1954 if (!IsReferenceType) 1955 return true; 1956 1957 // A reference constant expression must refer to an object. 1958 if (!Base) { 1959 // FIXME: diagnostic 1960 Info.CCEDiag(Loc); 1961 return true; 1962 } 1963 1964 // Does this refer one past the end of some object? 1965 if (!Designator.Invalid && Designator.isOnePastTheEnd()) { 1966 const ValueDecl *VD = Base.dyn_cast<const ValueDecl*>(); 1967 Info.FFDiag(Loc, diag::note_constexpr_past_end, 1) 1968 << !Designator.Entries.empty() << !!VD << VD; 1969 NoteLValueLocation(Info, Base); 1970 } 1971 1972 return true; 1973 } 1974 1975 /// Member pointers are constant expressions unless they point to a 1976 /// non-virtual dllimport member function. 1977 static bool CheckMemberPointerConstantExpression(EvalInfo &Info, 1978 SourceLocation Loc, 1979 QualType Type, 1980 const APValue &Value, 1981 Expr::ConstExprUsage Usage) { 1982 const ValueDecl *Member = Value.getMemberPointerDecl(); 1983 const auto *FD = dyn_cast_or_null<CXXMethodDecl>(Member); 1984 if (!FD) 1985 return true; 1986 return Usage == Expr::EvaluateForMangling || FD->isVirtual() || 1987 !FD->hasAttr<DLLImportAttr>(); 1988 } 1989 1990 /// Check that this core constant expression is of literal type, and if not, 1991 /// produce an appropriate diagnostic. 1992 static bool CheckLiteralType(EvalInfo &Info, const Expr *E, 1993 const LValue *This = nullptr) { 1994 if (!E->isRValue() || E->getType()->isLiteralType(Info.Ctx)) 1995 return true; 1996 1997 // C++1y: A constant initializer for an object o [...] may also invoke 1998 // constexpr constructors for o and its subobjects even if those objects 1999 // are of non-literal class types. 2000 // 2001 // C++11 missed this detail for aggregates, so classes like this: 2002 // struct foo_t { union { int i; volatile int j; } u; }; 2003 // are not (obviously) initializable like so: 2004 // __attribute__((__require_constant_initialization__)) 2005 // static const foo_t x = {{0}}; 2006 // because "i" is a subobject with non-literal initialization (due to the 2007 // volatile member of the union). See: 2008 // http://www.open-std.org/jtc1/sc22/wg21/docs/cwg_active.html#1677 2009 // Therefore, we use the C++1y behavior. 2010 if (This && Info.EvaluatingDecl == This->getLValueBase()) 2011 return true; 2012 2013 // Prvalue constant expressions must be of literal types. 2014 if (Info.getLangOpts().CPlusPlus11) 2015 Info.FFDiag(E, diag::note_constexpr_nonliteral) 2016 << E->getType(); 2017 else 2018 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 2019 return false; 2020 } 2021 2022 /// Check that this core constant expression value is a valid value for a 2023 /// constant expression. If not, report an appropriate diagnostic. Does not 2024 /// check that the expression is of literal type. 2025 static bool 2026 CheckConstantExpression(EvalInfo &Info, SourceLocation DiagLoc, QualType Type, 2027 const APValue &Value, 2028 Expr::ConstExprUsage Usage = Expr::EvaluateForCodeGen, 2029 SourceLocation SubobjectLoc = SourceLocation()) { 2030 if (!Value.hasValue()) { 2031 Info.FFDiag(DiagLoc, diag::note_constexpr_uninitialized) 2032 << true << Type; 2033 if (SubobjectLoc.isValid()) 2034 Info.Note(SubobjectLoc, diag::note_constexpr_subobject_declared_here); 2035 return false; 2036 } 2037 2038 // We allow _Atomic(T) to be initialized from anything that T can be 2039 // initialized from. 2040 if (const AtomicType *AT = Type->getAs<AtomicType>()) 2041 Type = AT->getValueType(); 2042 2043 // Core issue 1454: For a literal constant expression of array or class type, 2044 // each subobject of its value shall have been initialized by a constant 2045 // expression. 2046 if (Value.isArray()) { 2047 QualType EltTy = Type->castAsArrayTypeUnsafe()->getElementType(); 2048 for (unsigned I = 0, N = Value.getArrayInitializedElts(); I != N; ++I) { 2049 if (!CheckConstantExpression(Info, DiagLoc, EltTy, 2050 Value.getArrayInitializedElt(I), Usage, 2051 SubobjectLoc)) 2052 return false; 2053 } 2054 if (!Value.hasArrayFiller()) 2055 return true; 2056 return CheckConstantExpression(Info, DiagLoc, EltTy, Value.getArrayFiller(), 2057 Usage, SubobjectLoc); 2058 } 2059 if (Value.isUnion() && Value.getUnionField()) { 2060 return CheckConstantExpression(Info, DiagLoc, 2061 Value.getUnionField()->getType(), 2062 Value.getUnionValue(), Usage, 2063 Value.getUnionField()->getLocation()); 2064 } 2065 if (Value.isStruct()) { 2066 RecordDecl *RD = Type->castAs<RecordType>()->getDecl(); 2067 if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) { 2068 unsigned BaseIndex = 0; 2069 for (const CXXBaseSpecifier &BS : CD->bases()) { 2070 if (!CheckConstantExpression(Info, DiagLoc, BS.getType(), 2071 Value.getStructBase(BaseIndex), Usage, 2072 BS.getBeginLoc())) 2073 return false; 2074 ++BaseIndex; 2075 } 2076 } 2077 for (const auto *I : RD->fields()) { 2078 if (I->isUnnamedBitfield()) 2079 continue; 2080 2081 if (!CheckConstantExpression(Info, DiagLoc, I->getType(), 2082 Value.getStructField(I->getFieldIndex()), 2083 Usage, I->getLocation())) 2084 return false; 2085 } 2086 } 2087 2088 if (Value.isLValue()) { 2089 LValue LVal; 2090 LVal.setFrom(Info.Ctx, Value); 2091 return CheckLValueConstantExpression(Info, DiagLoc, Type, LVal, Usage); 2092 } 2093 2094 if (Value.isMemberPointer()) 2095 return CheckMemberPointerConstantExpression(Info, DiagLoc, Type, Value, Usage); 2096 2097 // Everything else is fine. 2098 return true; 2099 } 2100 2101 static bool EvalPointerValueAsBool(const APValue &Value, bool &Result) { 2102 // A null base expression indicates a null pointer. These are always 2103 // evaluatable, and they are false unless the offset is zero. 2104 if (!Value.getLValueBase()) { 2105 Result = !Value.getLValueOffset().isZero(); 2106 return true; 2107 } 2108 2109 // We have a non-null base. These are generally known to be true, but if it's 2110 // a weak declaration it can be null at runtime. 2111 Result = true; 2112 const ValueDecl *Decl = Value.getLValueBase().dyn_cast<const ValueDecl*>(); 2113 return !Decl || !Decl->isWeak(); 2114 } 2115 2116 static bool HandleConversionToBool(const APValue &Val, bool &Result) { 2117 switch (Val.getKind()) { 2118 case APValue::None: 2119 case APValue::Indeterminate: 2120 return false; 2121 case APValue::Int: 2122 Result = Val.getInt().getBoolValue(); 2123 return true; 2124 case APValue::FixedPoint: 2125 Result = Val.getFixedPoint().getBoolValue(); 2126 return true; 2127 case APValue::Float: 2128 Result = !Val.getFloat().isZero(); 2129 return true; 2130 case APValue::ComplexInt: 2131 Result = Val.getComplexIntReal().getBoolValue() || 2132 Val.getComplexIntImag().getBoolValue(); 2133 return true; 2134 case APValue::ComplexFloat: 2135 Result = !Val.getComplexFloatReal().isZero() || 2136 !Val.getComplexFloatImag().isZero(); 2137 return true; 2138 case APValue::LValue: 2139 return EvalPointerValueAsBool(Val, Result); 2140 case APValue::MemberPointer: 2141 Result = Val.getMemberPointerDecl(); 2142 return true; 2143 case APValue::Vector: 2144 case APValue::Array: 2145 case APValue::Struct: 2146 case APValue::Union: 2147 case APValue::AddrLabelDiff: 2148 return false; 2149 } 2150 2151 llvm_unreachable("unknown APValue kind"); 2152 } 2153 2154 static bool EvaluateAsBooleanCondition(const Expr *E, bool &Result, 2155 EvalInfo &Info) { 2156 assert(E->isRValue() && "missing lvalue-to-rvalue conv in bool condition"); 2157 APValue Val; 2158 if (!Evaluate(Val, Info, E)) 2159 return false; 2160 return HandleConversionToBool(Val, Result); 2161 } 2162 2163 template<typename T> 2164 static bool HandleOverflow(EvalInfo &Info, const Expr *E, 2165 const T &SrcValue, QualType DestType) { 2166 Info.CCEDiag(E, diag::note_constexpr_overflow) 2167 << SrcValue << DestType; 2168 return Info.noteUndefinedBehavior(); 2169 } 2170 2171 static bool HandleFloatToIntCast(EvalInfo &Info, const Expr *E, 2172 QualType SrcType, const APFloat &Value, 2173 QualType DestType, APSInt &Result) { 2174 unsigned DestWidth = Info.Ctx.getIntWidth(DestType); 2175 // Determine whether we are converting to unsigned or signed. 2176 bool DestSigned = DestType->isSignedIntegerOrEnumerationType(); 2177 2178 Result = APSInt(DestWidth, !DestSigned); 2179 bool ignored; 2180 if (Value.convertToInteger(Result, llvm::APFloat::rmTowardZero, &ignored) 2181 & APFloat::opInvalidOp) 2182 return HandleOverflow(Info, E, Value, DestType); 2183 return true; 2184 } 2185 2186 static bool HandleFloatToFloatCast(EvalInfo &Info, const Expr *E, 2187 QualType SrcType, QualType DestType, 2188 APFloat &Result) { 2189 APFloat Value = Result; 2190 bool ignored; 2191 Result.convert(Info.Ctx.getFloatTypeSemantics(DestType), 2192 APFloat::rmNearestTiesToEven, &ignored); 2193 return true; 2194 } 2195 2196 static APSInt HandleIntToIntCast(EvalInfo &Info, const Expr *E, 2197 QualType DestType, QualType SrcType, 2198 const APSInt &Value) { 2199 unsigned DestWidth = Info.Ctx.getIntWidth(DestType); 2200 // Figure out if this is a truncate, extend or noop cast. 2201 // If the input is signed, do a sign extend, noop, or truncate. 2202 APSInt Result = Value.extOrTrunc(DestWidth); 2203 Result.setIsUnsigned(DestType->isUnsignedIntegerOrEnumerationType()); 2204 if (DestType->isBooleanType()) 2205 Result = Value.getBoolValue(); 2206 return Result; 2207 } 2208 2209 static bool HandleIntToFloatCast(EvalInfo &Info, const Expr *E, 2210 QualType SrcType, const APSInt &Value, 2211 QualType DestType, APFloat &Result) { 2212 Result = APFloat(Info.Ctx.getFloatTypeSemantics(DestType), 1); 2213 Result.convertFromAPInt(Value, Value.isSigned(), 2214 APFloat::rmNearestTiesToEven); 2215 return true; 2216 } 2217 2218 static bool truncateBitfieldValue(EvalInfo &Info, const Expr *E, 2219 APValue &Value, const FieldDecl *FD) { 2220 assert(FD->isBitField() && "truncateBitfieldValue on non-bitfield"); 2221 2222 if (!Value.isInt()) { 2223 // Trying to store a pointer-cast-to-integer into a bitfield. 2224 // FIXME: In this case, we should provide the diagnostic for casting 2225 // a pointer to an integer. 2226 assert(Value.isLValue() && "integral value neither int nor lvalue?"); 2227 Info.FFDiag(E); 2228 return false; 2229 } 2230 2231 APSInt &Int = Value.getInt(); 2232 unsigned OldBitWidth = Int.getBitWidth(); 2233 unsigned NewBitWidth = FD->getBitWidthValue(Info.Ctx); 2234 if (NewBitWidth < OldBitWidth) 2235 Int = Int.trunc(NewBitWidth).extend(OldBitWidth); 2236 return true; 2237 } 2238 2239 static bool EvalAndBitcastToAPInt(EvalInfo &Info, const Expr *E, 2240 llvm::APInt &Res) { 2241 APValue SVal; 2242 if (!Evaluate(SVal, Info, E)) 2243 return false; 2244 if (SVal.isInt()) { 2245 Res = SVal.getInt(); 2246 return true; 2247 } 2248 if (SVal.isFloat()) { 2249 Res = SVal.getFloat().bitcastToAPInt(); 2250 return true; 2251 } 2252 if (SVal.isVector()) { 2253 QualType VecTy = E->getType(); 2254 unsigned VecSize = Info.Ctx.getTypeSize(VecTy); 2255 QualType EltTy = VecTy->castAs<VectorType>()->getElementType(); 2256 unsigned EltSize = Info.Ctx.getTypeSize(EltTy); 2257 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); 2258 Res = llvm::APInt::getNullValue(VecSize); 2259 for (unsigned i = 0; i < SVal.getVectorLength(); i++) { 2260 APValue &Elt = SVal.getVectorElt(i); 2261 llvm::APInt EltAsInt; 2262 if (Elt.isInt()) { 2263 EltAsInt = Elt.getInt(); 2264 } else if (Elt.isFloat()) { 2265 EltAsInt = Elt.getFloat().bitcastToAPInt(); 2266 } else { 2267 // Don't try to handle vectors of anything other than int or float 2268 // (not sure if it's possible to hit this case). 2269 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 2270 return false; 2271 } 2272 unsigned BaseEltSize = EltAsInt.getBitWidth(); 2273 if (BigEndian) 2274 Res |= EltAsInt.zextOrTrunc(VecSize).rotr(i*EltSize+BaseEltSize); 2275 else 2276 Res |= EltAsInt.zextOrTrunc(VecSize).rotl(i*EltSize); 2277 } 2278 return true; 2279 } 2280 // Give up if the input isn't an int, float, or vector. For example, we 2281 // reject "(v4i16)(intptr_t)&a". 2282 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 2283 return false; 2284 } 2285 2286 /// Perform the given integer operation, which is known to need at most BitWidth 2287 /// bits, and check for overflow in the original type (if that type was not an 2288 /// unsigned type). 2289 template<typename Operation> 2290 static bool CheckedIntArithmetic(EvalInfo &Info, const Expr *E, 2291 const APSInt &LHS, const APSInt &RHS, 2292 unsigned BitWidth, Operation Op, 2293 APSInt &Result) { 2294 if (LHS.isUnsigned()) { 2295 Result = Op(LHS, RHS); 2296 return true; 2297 } 2298 2299 APSInt Value(Op(LHS.extend(BitWidth), RHS.extend(BitWidth)), false); 2300 Result = Value.trunc(LHS.getBitWidth()); 2301 if (Result.extend(BitWidth) != Value) { 2302 if (Info.checkingForUndefinedBehavior()) 2303 Info.Ctx.getDiagnostics().Report(E->getExprLoc(), 2304 diag::warn_integer_constant_overflow) 2305 << Result.toString(10) << E->getType(); 2306 else 2307 return HandleOverflow(Info, E, Value, E->getType()); 2308 } 2309 return true; 2310 } 2311 2312 /// Perform the given binary integer operation. 2313 static bool handleIntIntBinOp(EvalInfo &Info, const Expr *E, const APSInt &LHS, 2314 BinaryOperatorKind Opcode, APSInt RHS, 2315 APSInt &Result) { 2316 switch (Opcode) { 2317 default: 2318 Info.FFDiag(E); 2319 return false; 2320 case BO_Mul: 2321 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() * 2, 2322 std::multiplies<APSInt>(), Result); 2323 case BO_Add: 2324 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, 2325 std::plus<APSInt>(), Result); 2326 case BO_Sub: 2327 return CheckedIntArithmetic(Info, E, LHS, RHS, LHS.getBitWidth() + 1, 2328 std::minus<APSInt>(), Result); 2329 case BO_And: Result = LHS & RHS; return true; 2330 case BO_Xor: Result = LHS ^ RHS; return true; 2331 case BO_Or: Result = LHS | RHS; return true; 2332 case BO_Div: 2333 case BO_Rem: 2334 if (RHS == 0) { 2335 Info.FFDiag(E, diag::note_expr_divide_by_zero); 2336 return false; 2337 } 2338 Result = (Opcode == BO_Rem ? LHS % RHS : LHS / RHS); 2339 // Check for overflow case: INT_MIN / -1 or INT_MIN % -1. APSInt supports 2340 // this operation and gives the two's complement result. 2341 if (RHS.isNegative() && RHS.isAllOnesValue() && 2342 LHS.isSigned() && LHS.isMinSignedValue()) 2343 return HandleOverflow(Info, E, -LHS.extend(LHS.getBitWidth() + 1), 2344 E->getType()); 2345 return true; 2346 case BO_Shl: { 2347 if (Info.getLangOpts().OpenCL) 2348 // OpenCL 6.3j: shift values are effectively % word size of LHS. 2349 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), 2350 static_cast<uint64_t>(LHS.getBitWidth() - 1)), 2351 RHS.isUnsigned()); 2352 else if (RHS.isSigned() && RHS.isNegative()) { 2353 // During constant-folding, a negative shift is an opposite shift. Such 2354 // a shift is not a constant expression. 2355 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; 2356 RHS = -RHS; 2357 goto shift_right; 2358 } 2359 shift_left: 2360 // C++11 [expr.shift]p1: Shift width must be less than the bit width of 2361 // the shifted type. 2362 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); 2363 if (SA != RHS) { 2364 Info.CCEDiag(E, diag::note_constexpr_large_shift) 2365 << RHS << E->getType() << LHS.getBitWidth(); 2366 } else if (LHS.isSigned() && !Info.getLangOpts().CPlusPlus2a) { 2367 // C++11 [expr.shift]p2: A signed left shift must have a non-negative 2368 // operand, and must not overflow the corresponding unsigned type. 2369 // C++2a [expr.shift]p2: E1 << E2 is the unique value congruent to 2370 // E1 x 2^E2 module 2^N. 2371 if (LHS.isNegative()) 2372 Info.CCEDiag(E, diag::note_constexpr_lshift_of_negative) << LHS; 2373 else if (LHS.countLeadingZeros() < SA) 2374 Info.CCEDiag(E, diag::note_constexpr_lshift_discards); 2375 } 2376 Result = LHS << SA; 2377 return true; 2378 } 2379 case BO_Shr: { 2380 if (Info.getLangOpts().OpenCL) 2381 // OpenCL 6.3j: shift values are effectively % word size of LHS. 2382 RHS &= APSInt(llvm::APInt(RHS.getBitWidth(), 2383 static_cast<uint64_t>(LHS.getBitWidth() - 1)), 2384 RHS.isUnsigned()); 2385 else if (RHS.isSigned() && RHS.isNegative()) { 2386 // During constant-folding, a negative shift is an opposite shift. Such a 2387 // shift is not a constant expression. 2388 Info.CCEDiag(E, diag::note_constexpr_negative_shift) << RHS; 2389 RHS = -RHS; 2390 goto shift_left; 2391 } 2392 shift_right: 2393 // C++11 [expr.shift]p1: Shift width must be less than the bit width of the 2394 // shifted type. 2395 unsigned SA = (unsigned) RHS.getLimitedValue(LHS.getBitWidth()-1); 2396 if (SA != RHS) 2397 Info.CCEDiag(E, diag::note_constexpr_large_shift) 2398 << RHS << E->getType() << LHS.getBitWidth(); 2399 Result = LHS >> SA; 2400 return true; 2401 } 2402 2403 case BO_LT: Result = LHS < RHS; return true; 2404 case BO_GT: Result = LHS > RHS; return true; 2405 case BO_LE: Result = LHS <= RHS; return true; 2406 case BO_GE: Result = LHS >= RHS; return true; 2407 case BO_EQ: Result = LHS == RHS; return true; 2408 case BO_NE: Result = LHS != RHS; return true; 2409 case BO_Cmp: 2410 llvm_unreachable("BO_Cmp should be handled elsewhere"); 2411 } 2412 } 2413 2414 /// Perform the given binary floating-point operation, in-place, on LHS. 2415 static bool handleFloatFloatBinOp(EvalInfo &Info, const Expr *E, 2416 APFloat &LHS, BinaryOperatorKind Opcode, 2417 const APFloat &RHS) { 2418 switch (Opcode) { 2419 default: 2420 Info.FFDiag(E); 2421 return false; 2422 case BO_Mul: 2423 LHS.multiply(RHS, APFloat::rmNearestTiesToEven); 2424 break; 2425 case BO_Add: 2426 LHS.add(RHS, APFloat::rmNearestTiesToEven); 2427 break; 2428 case BO_Sub: 2429 LHS.subtract(RHS, APFloat::rmNearestTiesToEven); 2430 break; 2431 case BO_Div: 2432 // [expr.mul]p4: 2433 // If the second operand of / or % is zero the behavior is undefined. 2434 if (RHS.isZero()) 2435 Info.CCEDiag(E, diag::note_expr_divide_by_zero); 2436 LHS.divide(RHS, APFloat::rmNearestTiesToEven); 2437 break; 2438 } 2439 2440 // [expr.pre]p4: 2441 // If during the evaluation of an expression, the result is not 2442 // mathematically defined [...], the behavior is undefined. 2443 // FIXME: C++ rules require us to not conform to IEEE 754 here. 2444 if (LHS.isNaN()) { 2445 Info.CCEDiag(E, diag::note_constexpr_float_arithmetic) << LHS.isNaN(); 2446 return Info.noteUndefinedBehavior(); 2447 } 2448 return true; 2449 } 2450 2451 /// Cast an lvalue referring to a base subobject to a derived class, by 2452 /// truncating the lvalue's path to the given length. 2453 static bool CastToDerivedClass(EvalInfo &Info, const Expr *E, LValue &Result, 2454 const RecordDecl *TruncatedType, 2455 unsigned TruncatedElements) { 2456 SubobjectDesignator &D = Result.Designator; 2457 2458 // Check we actually point to a derived class object. 2459 if (TruncatedElements == D.Entries.size()) 2460 return true; 2461 assert(TruncatedElements >= D.MostDerivedPathLength && 2462 "not casting to a derived class"); 2463 if (!Result.checkSubobject(Info, E, CSK_Derived)) 2464 return false; 2465 2466 // Truncate the path to the subobject, and remove any derived-to-base offsets. 2467 const RecordDecl *RD = TruncatedType; 2468 for (unsigned I = TruncatedElements, N = D.Entries.size(); I != N; ++I) { 2469 if (RD->isInvalidDecl()) return false; 2470 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 2471 const CXXRecordDecl *Base = getAsBaseClass(D.Entries[I]); 2472 if (isVirtualBaseClass(D.Entries[I])) 2473 Result.Offset -= Layout.getVBaseClassOffset(Base); 2474 else 2475 Result.Offset -= Layout.getBaseClassOffset(Base); 2476 RD = Base; 2477 } 2478 D.Entries.resize(TruncatedElements); 2479 return true; 2480 } 2481 2482 static bool HandleLValueDirectBase(EvalInfo &Info, const Expr *E, LValue &Obj, 2483 const CXXRecordDecl *Derived, 2484 const CXXRecordDecl *Base, 2485 const ASTRecordLayout *RL = nullptr) { 2486 if (!RL) { 2487 if (Derived->isInvalidDecl()) return false; 2488 RL = &Info.Ctx.getASTRecordLayout(Derived); 2489 } 2490 2491 Obj.getLValueOffset() += RL->getBaseClassOffset(Base); 2492 Obj.addDecl(Info, E, Base, /*Virtual*/ false); 2493 return true; 2494 } 2495 2496 static bool HandleLValueBase(EvalInfo &Info, const Expr *E, LValue &Obj, 2497 const CXXRecordDecl *DerivedDecl, 2498 const CXXBaseSpecifier *Base) { 2499 const CXXRecordDecl *BaseDecl = Base->getType()->getAsCXXRecordDecl(); 2500 2501 if (!Base->isVirtual()) 2502 return HandleLValueDirectBase(Info, E, Obj, DerivedDecl, BaseDecl); 2503 2504 SubobjectDesignator &D = Obj.Designator; 2505 if (D.Invalid) 2506 return false; 2507 2508 // Extract most-derived object and corresponding type. 2509 DerivedDecl = D.MostDerivedType->getAsCXXRecordDecl(); 2510 if (!CastToDerivedClass(Info, E, Obj, DerivedDecl, D.MostDerivedPathLength)) 2511 return false; 2512 2513 // Find the virtual base class. 2514 if (DerivedDecl->isInvalidDecl()) return false; 2515 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(DerivedDecl); 2516 Obj.getLValueOffset() += Layout.getVBaseClassOffset(BaseDecl); 2517 Obj.addDecl(Info, E, BaseDecl, /*Virtual*/ true); 2518 return true; 2519 } 2520 2521 static bool HandleLValueBasePath(EvalInfo &Info, const CastExpr *E, 2522 QualType Type, LValue &Result) { 2523 for (CastExpr::path_const_iterator PathI = E->path_begin(), 2524 PathE = E->path_end(); 2525 PathI != PathE; ++PathI) { 2526 if (!HandleLValueBase(Info, E, Result, Type->getAsCXXRecordDecl(), 2527 *PathI)) 2528 return false; 2529 Type = (*PathI)->getType(); 2530 } 2531 return true; 2532 } 2533 2534 /// Cast an lvalue referring to a derived class to a known base subobject. 2535 static bool CastToBaseClass(EvalInfo &Info, const Expr *E, LValue &Result, 2536 const CXXRecordDecl *DerivedRD, 2537 const CXXRecordDecl *BaseRD) { 2538 CXXBasePaths Paths(/*FindAmbiguities=*/false, 2539 /*RecordPaths=*/true, /*DetectVirtual=*/false); 2540 if (!DerivedRD->isDerivedFrom(BaseRD, Paths)) 2541 llvm_unreachable("Class must be derived from the passed in base class!"); 2542 2543 for (CXXBasePathElement &Elem : Paths.front()) 2544 if (!HandleLValueBase(Info, E, Result, Elem.Class, Elem.Base)) 2545 return false; 2546 return true; 2547 } 2548 2549 /// Update LVal to refer to the given field, which must be a member of the type 2550 /// currently described by LVal. 2551 static bool HandleLValueMember(EvalInfo &Info, const Expr *E, LValue &LVal, 2552 const FieldDecl *FD, 2553 const ASTRecordLayout *RL = nullptr) { 2554 if (!RL) { 2555 if (FD->getParent()->isInvalidDecl()) return false; 2556 RL = &Info.Ctx.getASTRecordLayout(FD->getParent()); 2557 } 2558 2559 unsigned I = FD->getFieldIndex(); 2560 LVal.adjustOffset(Info.Ctx.toCharUnitsFromBits(RL->getFieldOffset(I))); 2561 LVal.addDecl(Info, E, FD); 2562 return true; 2563 } 2564 2565 /// Update LVal to refer to the given indirect field. 2566 static bool HandleLValueIndirectMember(EvalInfo &Info, const Expr *E, 2567 LValue &LVal, 2568 const IndirectFieldDecl *IFD) { 2569 for (const auto *C : IFD->chain()) 2570 if (!HandleLValueMember(Info, E, LVal, cast<FieldDecl>(C))) 2571 return false; 2572 return true; 2573 } 2574 2575 /// Get the size of the given type in char units. 2576 static bool HandleSizeof(EvalInfo &Info, SourceLocation Loc, 2577 QualType Type, CharUnits &Size) { 2578 // sizeof(void), __alignof__(void), sizeof(function) = 1 as a gcc 2579 // extension. 2580 if (Type->isVoidType() || Type->isFunctionType()) { 2581 Size = CharUnits::One(); 2582 return true; 2583 } 2584 2585 if (Type->isDependentType()) { 2586 Info.FFDiag(Loc); 2587 return false; 2588 } 2589 2590 if (!Type->isConstantSizeType()) { 2591 // sizeof(vla) is not a constantexpr: C99 6.5.3.4p2. 2592 // FIXME: Better diagnostic. 2593 Info.FFDiag(Loc); 2594 return false; 2595 } 2596 2597 Size = Info.Ctx.getTypeSizeInChars(Type); 2598 return true; 2599 } 2600 2601 /// Update a pointer value to model pointer arithmetic. 2602 /// \param Info - Information about the ongoing evaluation. 2603 /// \param E - The expression being evaluated, for diagnostic purposes. 2604 /// \param LVal - The pointer value to be updated. 2605 /// \param EltTy - The pointee type represented by LVal. 2606 /// \param Adjustment - The adjustment, in objects of type EltTy, to add. 2607 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E, 2608 LValue &LVal, QualType EltTy, 2609 APSInt Adjustment) { 2610 CharUnits SizeOfPointee; 2611 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfPointee)) 2612 return false; 2613 2614 LVal.adjustOffsetAndIndex(Info, E, Adjustment, SizeOfPointee); 2615 return true; 2616 } 2617 2618 static bool HandleLValueArrayAdjustment(EvalInfo &Info, const Expr *E, 2619 LValue &LVal, QualType EltTy, 2620 int64_t Adjustment) { 2621 return HandleLValueArrayAdjustment(Info, E, LVal, EltTy, 2622 APSInt::get(Adjustment)); 2623 } 2624 2625 /// Update an lvalue to refer to a component of a complex number. 2626 /// \param Info - Information about the ongoing evaluation. 2627 /// \param LVal - The lvalue to be updated. 2628 /// \param EltTy - The complex number's component type. 2629 /// \param Imag - False for the real component, true for the imaginary. 2630 static bool HandleLValueComplexElement(EvalInfo &Info, const Expr *E, 2631 LValue &LVal, QualType EltTy, 2632 bool Imag) { 2633 if (Imag) { 2634 CharUnits SizeOfComponent; 2635 if (!HandleSizeof(Info, E->getExprLoc(), EltTy, SizeOfComponent)) 2636 return false; 2637 LVal.Offset += SizeOfComponent; 2638 } 2639 LVal.addComplex(Info, E, EltTy, Imag); 2640 return true; 2641 } 2642 2643 /// Try to evaluate the initializer for a variable declaration. 2644 /// 2645 /// \param Info Information about the ongoing evaluation. 2646 /// \param E An expression to be used when printing diagnostics. 2647 /// \param VD The variable whose initializer should be obtained. 2648 /// \param Frame The frame in which the variable was created. Must be null 2649 /// if this variable is not local to the evaluation. 2650 /// \param Result Filled in with a pointer to the value of the variable. 2651 static bool evaluateVarDeclInit(EvalInfo &Info, const Expr *E, 2652 const VarDecl *VD, CallStackFrame *Frame, 2653 APValue *&Result, const LValue *LVal) { 2654 2655 // If this is a parameter to an active constexpr function call, perform 2656 // argument substitution. 2657 if (const ParmVarDecl *PVD = dyn_cast<ParmVarDecl>(VD)) { 2658 // Assume arguments of a potential constant expression are unknown 2659 // constant expressions. 2660 if (Info.checkingPotentialConstantExpression()) 2661 return false; 2662 if (!Frame || !Frame->Arguments) { 2663 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 2664 return false; 2665 } 2666 Result = &Frame->Arguments[PVD->getFunctionScopeIndex()]; 2667 return true; 2668 } 2669 2670 // If this is a local variable, dig out its value. 2671 if (Frame) { 2672 Result = LVal ? Frame->getTemporary(VD, LVal->getLValueVersion()) 2673 : Frame->getCurrentTemporary(VD); 2674 if (!Result) { 2675 // Assume variables referenced within a lambda's call operator that were 2676 // not declared within the call operator are captures and during checking 2677 // of a potential constant expression, assume they are unknown constant 2678 // expressions. 2679 assert(isLambdaCallOperator(Frame->Callee) && 2680 (VD->getDeclContext() != Frame->Callee || VD->isInitCapture()) && 2681 "missing value for local variable"); 2682 if (Info.checkingPotentialConstantExpression()) 2683 return false; 2684 // FIXME: implement capture evaluation during constant expr evaluation. 2685 Info.FFDiag(E->getBeginLoc(), 2686 diag::note_unimplemented_constexpr_lambda_feature_ast) 2687 << "captures not currently allowed"; 2688 return false; 2689 } 2690 return true; 2691 } 2692 2693 // Dig out the initializer, and use the declaration which it's attached to. 2694 const Expr *Init = VD->getAnyInitializer(VD); 2695 if (!Init || Init->isValueDependent()) { 2696 // If we're checking a potential constant expression, the variable could be 2697 // initialized later. 2698 if (!Info.checkingPotentialConstantExpression()) 2699 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 2700 return false; 2701 } 2702 2703 // If we're currently evaluating the initializer of this declaration, use that 2704 // in-flight value. 2705 if (Info.EvaluatingDecl.dyn_cast<const ValueDecl*>() == VD) { 2706 Result = Info.EvaluatingDeclValue; 2707 return true; 2708 } 2709 2710 // Never evaluate the initializer of a weak variable. We can't be sure that 2711 // this is the definition which will be used. 2712 if (VD->isWeak()) { 2713 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 2714 return false; 2715 } 2716 2717 // Check that we can fold the initializer. In C++, we will have already done 2718 // this in the cases where it matters for conformance. 2719 SmallVector<PartialDiagnosticAt, 8> Notes; 2720 if (!VD->evaluateValue(Notes)) { 2721 Info.FFDiag(E, diag::note_constexpr_var_init_non_constant, 2722 Notes.size() + 1) << VD; 2723 Info.Note(VD->getLocation(), diag::note_declared_at); 2724 Info.addNotes(Notes); 2725 return false; 2726 } else if (!VD->checkInitIsICE()) { 2727 Info.CCEDiag(E, diag::note_constexpr_var_init_non_constant, 2728 Notes.size() + 1) << VD; 2729 Info.Note(VD->getLocation(), diag::note_declared_at); 2730 Info.addNotes(Notes); 2731 } 2732 2733 Result = VD->getEvaluatedValue(); 2734 return true; 2735 } 2736 2737 static bool IsConstNonVolatile(QualType T) { 2738 Qualifiers Quals = T.getQualifiers(); 2739 return Quals.hasConst() && !Quals.hasVolatile(); 2740 } 2741 2742 /// Get the base index of the given base class within an APValue representing 2743 /// the given derived class. 2744 static unsigned getBaseIndex(const CXXRecordDecl *Derived, 2745 const CXXRecordDecl *Base) { 2746 Base = Base->getCanonicalDecl(); 2747 unsigned Index = 0; 2748 for (CXXRecordDecl::base_class_const_iterator I = Derived->bases_begin(), 2749 E = Derived->bases_end(); I != E; ++I, ++Index) { 2750 if (I->getType()->getAsCXXRecordDecl()->getCanonicalDecl() == Base) 2751 return Index; 2752 } 2753 2754 llvm_unreachable("base class missing from derived class's bases list"); 2755 } 2756 2757 /// Extract the value of a character from a string literal. 2758 static APSInt extractStringLiteralCharacter(EvalInfo &Info, const Expr *Lit, 2759 uint64_t Index) { 2760 assert(!isa<SourceLocExpr>(Lit) && 2761 "SourceLocExpr should have already been converted to a StringLiteral"); 2762 2763 // FIXME: Support MakeStringConstant 2764 if (const auto *ObjCEnc = dyn_cast<ObjCEncodeExpr>(Lit)) { 2765 std::string Str; 2766 Info.Ctx.getObjCEncodingForType(ObjCEnc->getEncodedType(), Str); 2767 assert(Index <= Str.size() && "Index too large"); 2768 return APSInt::getUnsigned(Str.c_str()[Index]); 2769 } 2770 2771 if (auto PE = dyn_cast<PredefinedExpr>(Lit)) 2772 Lit = PE->getFunctionName(); 2773 const StringLiteral *S = cast<StringLiteral>(Lit); 2774 const ConstantArrayType *CAT = 2775 Info.Ctx.getAsConstantArrayType(S->getType()); 2776 assert(CAT && "string literal isn't an array"); 2777 QualType CharType = CAT->getElementType(); 2778 assert(CharType->isIntegerType() && "unexpected character type"); 2779 2780 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), 2781 CharType->isUnsignedIntegerType()); 2782 if (Index < S->getLength()) 2783 Value = S->getCodeUnit(Index); 2784 return Value; 2785 } 2786 2787 // Expand a string literal into an array of characters. 2788 // 2789 // FIXME: This is inefficient; we should probably introduce something similar 2790 // to the LLVM ConstantDataArray to make this cheaper. 2791 static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S, 2792 APValue &Result) { 2793 const ConstantArrayType *CAT = 2794 Info.Ctx.getAsConstantArrayType(S->getType()); 2795 assert(CAT && "string literal isn't an array"); 2796 QualType CharType = CAT->getElementType(); 2797 assert(CharType->isIntegerType() && "unexpected character type"); 2798 2799 unsigned Elts = CAT->getSize().getZExtValue(); 2800 Result = APValue(APValue::UninitArray(), 2801 std::min(S->getLength(), Elts), Elts); 2802 APSInt Value(S->getCharByteWidth() * Info.Ctx.getCharWidth(), 2803 CharType->isUnsignedIntegerType()); 2804 if (Result.hasArrayFiller()) 2805 Result.getArrayFiller() = APValue(Value); 2806 for (unsigned I = 0, N = Result.getArrayInitializedElts(); I != N; ++I) { 2807 Value = S->getCodeUnit(I); 2808 Result.getArrayInitializedElt(I) = APValue(Value); 2809 } 2810 } 2811 2812 // Expand an array so that it has more than Index filled elements. 2813 static void expandArray(APValue &Array, unsigned Index) { 2814 unsigned Size = Array.getArraySize(); 2815 assert(Index < Size); 2816 2817 // Always at least double the number of elements for which we store a value. 2818 unsigned OldElts = Array.getArrayInitializedElts(); 2819 unsigned NewElts = std::max(Index+1, OldElts * 2); 2820 NewElts = std::min(Size, std::max(NewElts, 8u)); 2821 2822 // Copy the data across. 2823 APValue NewValue(APValue::UninitArray(), NewElts, Size); 2824 for (unsigned I = 0; I != OldElts; ++I) 2825 NewValue.getArrayInitializedElt(I).swap(Array.getArrayInitializedElt(I)); 2826 for (unsigned I = OldElts; I != NewElts; ++I) 2827 NewValue.getArrayInitializedElt(I) = Array.getArrayFiller(); 2828 if (NewValue.hasArrayFiller()) 2829 NewValue.getArrayFiller() = Array.getArrayFiller(); 2830 Array.swap(NewValue); 2831 } 2832 2833 /// Determine whether a type would actually be read by an lvalue-to-rvalue 2834 /// conversion. If it's of class type, we may assume that the copy operation 2835 /// is trivial. Note that this is never true for a union type with fields 2836 /// (because the copy always "reads" the active member) and always true for 2837 /// a non-class type. 2838 static bool isReadByLvalueToRvalueConversion(QualType T) { 2839 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); 2840 if (!RD || (RD->isUnion() && !RD->field_empty())) 2841 return true; 2842 if (RD->isEmpty()) 2843 return false; 2844 2845 for (auto *Field : RD->fields()) 2846 if (isReadByLvalueToRvalueConversion(Field->getType())) 2847 return true; 2848 2849 for (auto &BaseSpec : RD->bases()) 2850 if (isReadByLvalueToRvalueConversion(BaseSpec.getType())) 2851 return true; 2852 2853 return false; 2854 } 2855 2856 /// Diagnose an attempt to read from any unreadable field within the specified 2857 /// type, which might be a class type. 2858 static bool diagnoseUnreadableFields(EvalInfo &Info, const Expr *E, 2859 QualType T) { 2860 CXXRecordDecl *RD = T->getBaseElementTypeUnsafe()->getAsCXXRecordDecl(); 2861 if (!RD) 2862 return false; 2863 2864 if (!RD->hasMutableFields()) 2865 return false; 2866 2867 for (auto *Field : RD->fields()) { 2868 // If we're actually going to read this field in some way, then it can't 2869 // be mutable. If we're in a union, then assigning to a mutable field 2870 // (even an empty one) can change the active member, so that's not OK. 2871 // FIXME: Add core issue number for the union case. 2872 if (Field->isMutable() && 2873 (RD->isUnion() || isReadByLvalueToRvalueConversion(Field->getType()))) { 2874 Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1) << Field; 2875 Info.Note(Field->getLocation(), diag::note_declared_at); 2876 return true; 2877 } 2878 2879 if (diagnoseUnreadableFields(Info, E, Field->getType())) 2880 return true; 2881 } 2882 2883 for (auto &BaseSpec : RD->bases()) 2884 if (diagnoseUnreadableFields(Info, E, BaseSpec.getType())) 2885 return true; 2886 2887 // All mutable fields were empty, and thus not actually read. 2888 return false; 2889 } 2890 2891 static bool lifetimeStartedInEvaluation(EvalInfo &Info, 2892 APValue::LValueBase Base) { 2893 // A temporary we created. 2894 if (Base.getCallIndex()) 2895 return true; 2896 2897 auto *Evaluating = Info.EvaluatingDecl.dyn_cast<const ValueDecl*>(); 2898 if (!Evaluating) 2899 return false; 2900 2901 // The variable whose initializer we're evaluating. 2902 if (auto *BaseD = Base.dyn_cast<const ValueDecl*>()) 2903 if (declaresSameEntity(Evaluating, BaseD)) 2904 return true; 2905 2906 // A temporary lifetime-extended by the variable whose initializer we're 2907 // evaluating. 2908 if (auto *BaseE = Base.dyn_cast<const Expr *>()) 2909 if (auto *BaseMTE = dyn_cast<MaterializeTemporaryExpr>(BaseE)) 2910 if (declaresSameEntity(BaseMTE->getExtendingDecl(), Evaluating)) 2911 return true; 2912 2913 return false; 2914 } 2915 2916 namespace { 2917 /// A handle to a complete object (an object that is not a subobject of 2918 /// another object). 2919 struct CompleteObject { 2920 /// The identity of the object. 2921 APValue::LValueBase Base; 2922 /// The value of the complete object. 2923 APValue *Value; 2924 /// The type of the complete object. 2925 QualType Type; 2926 2927 CompleteObject() : Value(nullptr) {} 2928 CompleteObject(APValue::LValueBase Base, APValue *Value, QualType Type) 2929 : Base(Base), Value(Value), Type(Type) {} 2930 2931 bool mayReadMutableMembers(EvalInfo &Info) const { 2932 // In C++14 onwards, it is permitted to read a mutable member whose 2933 // lifetime began within the evaluation. 2934 // FIXME: Should we also allow this in C++11? 2935 if (!Info.getLangOpts().CPlusPlus14) 2936 return false; 2937 return lifetimeStartedInEvaluation(Info, Base); 2938 } 2939 2940 explicit operator bool() const { return !Type.isNull(); } 2941 }; 2942 } // end anonymous namespace 2943 2944 static QualType getSubobjectType(QualType ObjType, QualType SubobjType, 2945 bool IsMutable = false) { 2946 // C++ [basic.type.qualifier]p1: 2947 // - A const object is an object of type const T or a non-mutable subobject 2948 // of a const object. 2949 if (ObjType.isConstQualified() && !IsMutable) 2950 SubobjType.addConst(); 2951 // - A volatile object is an object of type const T or a subobject of a 2952 // volatile object. 2953 if (ObjType.isVolatileQualified()) 2954 SubobjType.addVolatile(); 2955 return SubobjType; 2956 } 2957 2958 /// Find the designated sub-object of an rvalue. 2959 template<typename SubobjectHandler> 2960 typename SubobjectHandler::result_type 2961 findSubobject(EvalInfo &Info, const Expr *E, const CompleteObject &Obj, 2962 const SubobjectDesignator &Sub, SubobjectHandler &handler) { 2963 if (Sub.Invalid) 2964 // A diagnostic will have already been produced. 2965 return handler.failed(); 2966 if (Sub.isOnePastTheEnd() || Sub.isMostDerivedAnUnsizedArray()) { 2967 if (Info.getLangOpts().CPlusPlus11) 2968 Info.FFDiag(E, Sub.isOnePastTheEnd() 2969 ? diag::note_constexpr_access_past_end 2970 : diag::note_constexpr_access_unsized_array) 2971 << handler.AccessKind; 2972 else 2973 Info.FFDiag(E); 2974 return handler.failed(); 2975 } 2976 2977 APValue *O = Obj.Value; 2978 QualType ObjType = Obj.Type; 2979 const FieldDecl *LastField = nullptr; 2980 const FieldDecl *VolatileField = nullptr; 2981 2982 // Walk the designator's path to find the subobject. 2983 for (unsigned I = 0, N = Sub.Entries.size(); /**/; ++I) { 2984 // Reading an indeterminate value is undefined, but assigning over one is OK. 2985 if (O->isAbsent() || (O->isIndeterminate() && handler.AccessKind != AK_Assign)) { 2986 if (!Info.checkingPotentialConstantExpression()) 2987 Info.FFDiag(E, diag::note_constexpr_access_uninit) 2988 << handler.AccessKind << O->isIndeterminate(); 2989 return handler.failed(); 2990 } 2991 2992 // C++ [class.ctor]p5: 2993 // const and volatile semantics are not applied on an object under 2994 // construction. 2995 if ((ObjType.isConstQualified() || ObjType.isVolatileQualified()) && 2996 ObjType->isRecordType() && 2997 Info.isEvaluatingConstructor( 2998 Obj.Base, llvm::makeArrayRef(Sub.Entries.begin(), 2999 Sub.Entries.begin() + I)) != 3000 ConstructionPhase::None) { 3001 ObjType = Info.Ctx.getCanonicalType(ObjType); 3002 ObjType.removeLocalConst(); 3003 ObjType.removeLocalVolatile(); 3004 } 3005 3006 // If this is our last pass, check that the final object type is OK. 3007 if (I == N || (I == N - 1 && ObjType->isAnyComplexType())) { 3008 // Accesses to volatile objects are prohibited. 3009 if (ObjType.isVolatileQualified() && isFormalAccess(handler.AccessKind)) { 3010 if (Info.getLangOpts().CPlusPlus) { 3011 int DiagKind; 3012 SourceLocation Loc; 3013 const NamedDecl *Decl = nullptr; 3014 if (VolatileField) { 3015 DiagKind = 2; 3016 Loc = VolatileField->getLocation(); 3017 Decl = VolatileField; 3018 } else if (auto *VD = Obj.Base.dyn_cast<const ValueDecl*>()) { 3019 DiagKind = 1; 3020 Loc = VD->getLocation(); 3021 Decl = VD; 3022 } else { 3023 DiagKind = 0; 3024 if (auto *E = Obj.Base.dyn_cast<const Expr *>()) 3025 Loc = E->getExprLoc(); 3026 } 3027 Info.FFDiag(E, diag::note_constexpr_access_volatile_obj, 1) 3028 << handler.AccessKind << DiagKind << Decl; 3029 Info.Note(Loc, diag::note_constexpr_volatile_here) << DiagKind; 3030 } else { 3031 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 3032 } 3033 return handler.failed(); 3034 } 3035 3036 // If we are reading an object of class type, there may still be more 3037 // things we need to check: if there are any mutable subobjects, we 3038 // cannot perform this read. (This only happens when performing a trivial 3039 // copy or assignment.) 3040 if (ObjType->isRecordType() && handler.AccessKind == AK_Read && 3041 !Obj.mayReadMutableMembers(Info) && 3042 diagnoseUnreadableFields(Info, E, ObjType)) 3043 return handler.failed(); 3044 } 3045 3046 if (I == N) { 3047 if (!handler.found(*O, ObjType)) 3048 return false; 3049 3050 // If we modified a bit-field, truncate it to the right width. 3051 if (isModification(handler.AccessKind) && 3052 LastField && LastField->isBitField() && 3053 !truncateBitfieldValue(Info, E, *O, LastField)) 3054 return false; 3055 3056 return true; 3057 } 3058 3059 LastField = nullptr; 3060 if (ObjType->isArrayType()) { 3061 // Next subobject is an array element. 3062 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(ObjType); 3063 assert(CAT && "vla in literal type?"); 3064 uint64_t Index = Sub.Entries[I].getAsArrayIndex(); 3065 if (CAT->getSize().ule(Index)) { 3066 // Note, it should not be possible to form a pointer with a valid 3067 // designator which points more than one past the end of the array. 3068 if (Info.getLangOpts().CPlusPlus11) 3069 Info.FFDiag(E, diag::note_constexpr_access_past_end) 3070 << handler.AccessKind; 3071 else 3072 Info.FFDiag(E); 3073 return handler.failed(); 3074 } 3075 3076 ObjType = CAT->getElementType(); 3077 3078 if (O->getArrayInitializedElts() > Index) 3079 O = &O->getArrayInitializedElt(Index); 3080 else if (handler.AccessKind != AK_Read) { 3081 expandArray(*O, Index); 3082 O = &O->getArrayInitializedElt(Index); 3083 } else 3084 O = &O->getArrayFiller(); 3085 } else if (ObjType->isAnyComplexType()) { 3086 // Next subobject is a complex number. 3087 uint64_t Index = Sub.Entries[I].getAsArrayIndex(); 3088 if (Index > 1) { 3089 if (Info.getLangOpts().CPlusPlus11) 3090 Info.FFDiag(E, diag::note_constexpr_access_past_end) 3091 << handler.AccessKind; 3092 else 3093 Info.FFDiag(E); 3094 return handler.failed(); 3095 } 3096 3097 ObjType = getSubobjectType( 3098 ObjType, ObjType->castAs<ComplexType>()->getElementType()); 3099 3100 assert(I == N - 1 && "extracting subobject of scalar?"); 3101 if (O->isComplexInt()) { 3102 return handler.found(Index ? O->getComplexIntImag() 3103 : O->getComplexIntReal(), ObjType); 3104 } else { 3105 assert(O->isComplexFloat()); 3106 return handler.found(Index ? O->getComplexFloatImag() 3107 : O->getComplexFloatReal(), ObjType); 3108 } 3109 } else if (const FieldDecl *Field = getAsField(Sub.Entries[I])) { 3110 if (Field->isMutable() && handler.AccessKind == AK_Read && 3111 !Obj.mayReadMutableMembers(Info)) { 3112 Info.FFDiag(E, diag::note_constexpr_ltor_mutable, 1) 3113 << Field; 3114 Info.Note(Field->getLocation(), diag::note_declared_at); 3115 return handler.failed(); 3116 } 3117 3118 // Next subobject is a class, struct or union field. 3119 RecordDecl *RD = ObjType->castAs<RecordType>()->getDecl(); 3120 if (RD->isUnion()) { 3121 const FieldDecl *UnionField = O->getUnionField(); 3122 if (!UnionField || 3123 UnionField->getCanonicalDecl() != Field->getCanonicalDecl()) { 3124 Info.FFDiag(E, diag::note_constexpr_access_inactive_union_member) 3125 << handler.AccessKind << Field << !UnionField << UnionField; 3126 return handler.failed(); 3127 } 3128 O = &O->getUnionValue(); 3129 } else 3130 O = &O->getStructField(Field->getFieldIndex()); 3131 3132 ObjType = getSubobjectType(ObjType, Field->getType(), Field->isMutable()); 3133 LastField = Field; 3134 if (Field->getType().isVolatileQualified()) 3135 VolatileField = Field; 3136 } else { 3137 // Next subobject is a base class. 3138 const CXXRecordDecl *Derived = ObjType->getAsCXXRecordDecl(); 3139 const CXXRecordDecl *Base = getAsBaseClass(Sub.Entries[I]); 3140 O = &O->getStructBase(getBaseIndex(Derived, Base)); 3141 3142 ObjType = getSubobjectType(ObjType, Info.Ctx.getRecordType(Base)); 3143 } 3144 } 3145 } 3146 3147 namespace { 3148 struct ExtractSubobjectHandler { 3149 EvalInfo &Info; 3150 APValue &Result; 3151 3152 static const AccessKinds AccessKind = AK_Read; 3153 3154 typedef bool result_type; 3155 bool failed() { return false; } 3156 bool found(APValue &Subobj, QualType SubobjType) { 3157 Result = Subobj; 3158 return true; 3159 } 3160 bool found(APSInt &Value, QualType SubobjType) { 3161 Result = APValue(Value); 3162 return true; 3163 } 3164 bool found(APFloat &Value, QualType SubobjType) { 3165 Result = APValue(Value); 3166 return true; 3167 } 3168 }; 3169 } // end anonymous namespace 3170 3171 const AccessKinds ExtractSubobjectHandler::AccessKind; 3172 3173 /// Extract the designated sub-object of an rvalue. 3174 static bool extractSubobject(EvalInfo &Info, const Expr *E, 3175 const CompleteObject &Obj, 3176 const SubobjectDesignator &Sub, 3177 APValue &Result) { 3178 ExtractSubobjectHandler Handler = { Info, Result }; 3179 return findSubobject(Info, E, Obj, Sub, Handler); 3180 } 3181 3182 namespace { 3183 struct ModifySubobjectHandler { 3184 EvalInfo &Info; 3185 APValue &NewVal; 3186 const Expr *E; 3187 3188 typedef bool result_type; 3189 static const AccessKinds AccessKind = AK_Assign; 3190 3191 bool checkConst(QualType QT) { 3192 // Assigning to a const object has undefined behavior. 3193 if (QT.isConstQualified()) { 3194 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; 3195 return false; 3196 } 3197 return true; 3198 } 3199 3200 bool failed() { return false; } 3201 bool found(APValue &Subobj, QualType SubobjType) { 3202 if (!checkConst(SubobjType)) 3203 return false; 3204 // We've been given ownership of NewVal, so just swap it in. 3205 Subobj.swap(NewVal); 3206 return true; 3207 } 3208 bool found(APSInt &Value, QualType SubobjType) { 3209 if (!checkConst(SubobjType)) 3210 return false; 3211 if (!NewVal.isInt()) { 3212 // Maybe trying to write a cast pointer value into a complex? 3213 Info.FFDiag(E); 3214 return false; 3215 } 3216 Value = NewVal.getInt(); 3217 return true; 3218 } 3219 bool found(APFloat &Value, QualType SubobjType) { 3220 if (!checkConst(SubobjType)) 3221 return false; 3222 Value = NewVal.getFloat(); 3223 return true; 3224 } 3225 }; 3226 } // end anonymous namespace 3227 3228 const AccessKinds ModifySubobjectHandler::AccessKind; 3229 3230 /// Update the designated sub-object of an rvalue to the given value. 3231 static bool modifySubobject(EvalInfo &Info, const Expr *E, 3232 const CompleteObject &Obj, 3233 const SubobjectDesignator &Sub, 3234 APValue &NewVal) { 3235 ModifySubobjectHandler Handler = { Info, NewVal, E }; 3236 return findSubobject(Info, E, Obj, Sub, Handler); 3237 } 3238 3239 /// Find the position where two subobject designators diverge, or equivalently 3240 /// the length of the common initial subsequence. 3241 static unsigned FindDesignatorMismatch(QualType ObjType, 3242 const SubobjectDesignator &A, 3243 const SubobjectDesignator &B, 3244 bool &WasArrayIndex) { 3245 unsigned I = 0, N = std::min(A.Entries.size(), B.Entries.size()); 3246 for (/**/; I != N; ++I) { 3247 if (!ObjType.isNull() && 3248 (ObjType->isArrayType() || ObjType->isAnyComplexType())) { 3249 // Next subobject is an array element. 3250 if (A.Entries[I].getAsArrayIndex() != B.Entries[I].getAsArrayIndex()) { 3251 WasArrayIndex = true; 3252 return I; 3253 } 3254 if (ObjType->isAnyComplexType()) 3255 ObjType = ObjType->castAs<ComplexType>()->getElementType(); 3256 else 3257 ObjType = ObjType->castAsArrayTypeUnsafe()->getElementType(); 3258 } else { 3259 if (A.Entries[I].getAsBaseOrMember() != 3260 B.Entries[I].getAsBaseOrMember()) { 3261 WasArrayIndex = false; 3262 return I; 3263 } 3264 if (const FieldDecl *FD = getAsField(A.Entries[I])) 3265 // Next subobject is a field. 3266 ObjType = FD->getType(); 3267 else 3268 // Next subobject is a base class. 3269 ObjType = QualType(); 3270 } 3271 } 3272 WasArrayIndex = false; 3273 return I; 3274 } 3275 3276 /// Determine whether the given subobject designators refer to elements of the 3277 /// same array object. 3278 static bool AreElementsOfSameArray(QualType ObjType, 3279 const SubobjectDesignator &A, 3280 const SubobjectDesignator &B) { 3281 if (A.Entries.size() != B.Entries.size()) 3282 return false; 3283 3284 bool IsArray = A.MostDerivedIsArrayElement; 3285 if (IsArray && A.MostDerivedPathLength != A.Entries.size()) 3286 // A is a subobject of the array element. 3287 return false; 3288 3289 // If A (and B) designates an array element, the last entry will be the array 3290 // index. That doesn't have to match. Otherwise, we're in the 'implicit array 3291 // of length 1' case, and the entire path must match. 3292 bool WasArrayIndex; 3293 unsigned CommonLength = FindDesignatorMismatch(ObjType, A, B, WasArrayIndex); 3294 return CommonLength >= A.Entries.size() - IsArray; 3295 } 3296 3297 /// Find the complete object to which an LValue refers. 3298 static CompleteObject findCompleteObject(EvalInfo &Info, const Expr *E, 3299 AccessKinds AK, const LValue &LVal, 3300 QualType LValType) { 3301 if (LVal.InvalidBase) { 3302 Info.FFDiag(E); 3303 return CompleteObject(); 3304 } 3305 3306 if (!LVal.Base) { 3307 Info.FFDiag(E, diag::note_constexpr_access_null) << AK; 3308 return CompleteObject(); 3309 } 3310 3311 CallStackFrame *Frame = nullptr; 3312 unsigned Depth = 0; 3313 if (LVal.getLValueCallIndex()) { 3314 std::tie(Frame, Depth) = 3315 Info.getCallFrameAndDepth(LVal.getLValueCallIndex()); 3316 if (!Frame) { 3317 Info.FFDiag(E, diag::note_constexpr_lifetime_ended, 1) 3318 << AK << LVal.Base.is<const ValueDecl*>(); 3319 NoteLValueLocation(Info, LVal.Base); 3320 return CompleteObject(); 3321 } 3322 } 3323 3324 bool IsAccess = isFormalAccess(AK); 3325 3326 // C++11 DR1311: An lvalue-to-rvalue conversion on a volatile-qualified type 3327 // is not a constant expression (even if the object is non-volatile). We also 3328 // apply this rule to C++98, in order to conform to the expected 'volatile' 3329 // semantics. 3330 if (IsAccess && LValType.isVolatileQualified()) { 3331 if (Info.getLangOpts().CPlusPlus) 3332 Info.FFDiag(E, diag::note_constexpr_access_volatile_type) 3333 << AK << LValType; 3334 else 3335 Info.FFDiag(E); 3336 return CompleteObject(); 3337 } 3338 3339 // Compute value storage location and type of base object. 3340 APValue *BaseVal = nullptr; 3341 QualType BaseType = getType(LVal.Base); 3342 3343 if (const ValueDecl *D = LVal.Base.dyn_cast<const ValueDecl*>()) { 3344 // In C++98, const, non-volatile integers initialized with ICEs are ICEs. 3345 // In C++11, constexpr, non-volatile variables initialized with constant 3346 // expressions are constant expressions too. Inside constexpr functions, 3347 // parameters are constant expressions even if they're non-const. 3348 // In C++1y, objects local to a constant expression (those with a Frame) are 3349 // both readable and writable inside constant expressions. 3350 // In C, such things can also be folded, although they are not ICEs. 3351 const VarDecl *VD = dyn_cast<VarDecl>(D); 3352 if (VD) { 3353 if (const VarDecl *VDef = VD->getDefinition(Info.Ctx)) 3354 VD = VDef; 3355 } 3356 if (!VD || VD->isInvalidDecl()) { 3357 Info.FFDiag(E); 3358 return CompleteObject(); 3359 } 3360 3361 // Unless we're looking at a local variable or argument in a constexpr call, 3362 // the variable we're reading must be const. 3363 if (!Frame) { 3364 if (Info.getLangOpts().CPlusPlus14 && 3365 declaresSameEntity( 3366 VD, Info.EvaluatingDecl.dyn_cast<const ValueDecl *>())) { 3367 // OK, we can read and modify an object if we're in the process of 3368 // evaluating its initializer, because its lifetime began in this 3369 // evaluation. 3370 } else if (isModification(AK)) { 3371 // All the remaining cases do not permit modification of the object. 3372 Info.FFDiag(E, diag::note_constexpr_modify_global); 3373 return CompleteObject(); 3374 } else if (VD->isConstexpr()) { 3375 // OK, we can read this variable. 3376 } else if (BaseType->isIntegralOrEnumerationType()) { 3377 // In OpenCL if a variable is in constant address space it is a const 3378 // value. 3379 if (!(BaseType.isConstQualified() || 3380 (Info.getLangOpts().OpenCL && 3381 BaseType.getAddressSpace() == LangAS::opencl_constant))) { 3382 if (!IsAccess) 3383 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); 3384 if (Info.getLangOpts().CPlusPlus) { 3385 Info.FFDiag(E, diag::note_constexpr_ltor_non_const_int, 1) << VD; 3386 Info.Note(VD->getLocation(), diag::note_declared_at); 3387 } else { 3388 Info.FFDiag(E); 3389 } 3390 return CompleteObject(); 3391 } 3392 } else if (!IsAccess) { 3393 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); 3394 } else if (BaseType->isFloatingType() && BaseType.isConstQualified()) { 3395 // We support folding of const floating-point types, in order to make 3396 // static const data members of such types (supported as an extension) 3397 // more useful. 3398 if (Info.getLangOpts().CPlusPlus11) { 3399 Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; 3400 Info.Note(VD->getLocation(), diag::note_declared_at); 3401 } else { 3402 Info.CCEDiag(E); 3403 } 3404 } else if (BaseType.isConstQualified() && VD->hasDefinition(Info.Ctx)) { 3405 Info.CCEDiag(E, diag::note_constexpr_ltor_non_constexpr) << VD; 3406 // Keep evaluating to see what we can do. 3407 } else { 3408 // FIXME: Allow folding of values of any literal type in all languages. 3409 if (Info.checkingPotentialConstantExpression() && 3410 VD->getType().isConstQualified() && !VD->hasDefinition(Info.Ctx)) { 3411 // The definition of this variable could be constexpr. We can't 3412 // access it right now, but may be able to in future. 3413 } else if (Info.getLangOpts().CPlusPlus11) { 3414 Info.FFDiag(E, diag::note_constexpr_ltor_non_constexpr, 1) << VD; 3415 Info.Note(VD->getLocation(), diag::note_declared_at); 3416 } else { 3417 Info.FFDiag(E); 3418 } 3419 return CompleteObject(); 3420 } 3421 } 3422 3423 if (!evaluateVarDeclInit(Info, E, VD, Frame, BaseVal, &LVal)) 3424 return CompleteObject(); 3425 } else { 3426 const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); 3427 3428 if (!Frame) { 3429 if (const MaterializeTemporaryExpr *MTE = 3430 dyn_cast_or_null<MaterializeTemporaryExpr>(Base)) { 3431 assert(MTE->getStorageDuration() == SD_Static && 3432 "should have a frame for a non-global materialized temporary"); 3433 3434 // Per C++1y [expr.const]p2: 3435 // an lvalue-to-rvalue conversion [is not allowed unless it applies to] 3436 // - a [...] glvalue of integral or enumeration type that refers to 3437 // a non-volatile const object [...] 3438 // [...] 3439 // - a [...] glvalue of literal type that refers to a non-volatile 3440 // object whose lifetime began within the evaluation of e. 3441 // 3442 // C++11 misses the 'began within the evaluation of e' check and 3443 // instead allows all temporaries, including things like: 3444 // int &&r = 1; 3445 // int x = ++r; 3446 // constexpr int k = r; 3447 // Therefore we use the C++14 rules in C++11 too. 3448 const ValueDecl *VD = Info.EvaluatingDecl.dyn_cast<const ValueDecl*>(); 3449 const ValueDecl *ED = MTE->getExtendingDecl(); 3450 if (!(BaseType.isConstQualified() && 3451 BaseType->isIntegralOrEnumerationType()) && 3452 !(VD && VD->getCanonicalDecl() == ED->getCanonicalDecl())) { 3453 if (!IsAccess) 3454 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); 3455 Info.FFDiag(E, diag::note_constexpr_access_static_temporary, 1) << AK; 3456 Info.Note(MTE->getExprLoc(), diag::note_constexpr_temporary_here); 3457 return CompleteObject(); 3458 } 3459 3460 BaseVal = Info.Ctx.getMaterializedTemporaryValue(MTE, false); 3461 assert(BaseVal && "got reference to unevaluated temporary"); 3462 } else { 3463 if (!IsAccess) 3464 return CompleteObject(LVal.getLValueBase(), nullptr, BaseType); 3465 APValue Val; 3466 LVal.moveInto(Val); 3467 Info.FFDiag(E, diag::note_constexpr_access_unreadable_object) 3468 << AK 3469 << Val.getAsString(Info.Ctx, 3470 Info.Ctx.getLValueReferenceType(LValType)); 3471 NoteLValueLocation(Info, LVal.Base); 3472 return CompleteObject(); 3473 } 3474 } else { 3475 BaseVal = Frame->getTemporary(Base, LVal.Base.getVersion()); 3476 assert(BaseVal && "missing value for temporary"); 3477 } 3478 } 3479 3480 // In C++14, we can't safely access any mutable state when we might be 3481 // evaluating after an unmodeled side effect. 3482 // 3483 // FIXME: Not all local state is mutable. Allow local constant subobjects 3484 // to be read here (but take care with 'mutable' fields). 3485 if ((Frame && Info.getLangOpts().CPlusPlus14 && 3486 Info.EvalStatus.HasSideEffects) || 3487 (isModification(AK) && Depth < Info.SpeculativeEvaluationDepth)) 3488 return CompleteObject(); 3489 3490 return CompleteObject(LVal.getLValueBase(), BaseVal, BaseType); 3491 } 3492 3493 /// Perform an lvalue-to-rvalue conversion on the given glvalue. This 3494 /// can also be used for 'lvalue-to-lvalue' conversions for looking up the 3495 /// glvalue referred to by an entity of reference type. 3496 /// 3497 /// \param Info - Information about the ongoing evaluation. 3498 /// \param Conv - The expression for which we are performing the conversion. 3499 /// Used for diagnostics. 3500 /// \param Type - The type of the glvalue (before stripping cv-qualifiers in the 3501 /// case of a non-class type). 3502 /// \param LVal - The glvalue on which we are attempting to perform this action. 3503 /// \param RVal - The produced value will be placed here. 3504 static bool handleLValueToRValueConversion(EvalInfo &Info, const Expr *Conv, 3505 QualType Type, 3506 const LValue &LVal, APValue &RVal) { 3507 if (LVal.Designator.Invalid) 3508 return false; 3509 3510 // Check for special cases where there is no existing APValue to look at. 3511 const Expr *Base = LVal.Base.dyn_cast<const Expr*>(); 3512 3513 if (Base && !LVal.getLValueCallIndex() && !Type.isVolatileQualified()) { 3514 if (const CompoundLiteralExpr *CLE = dyn_cast<CompoundLiteralExpr>(Base)) { 3515 // In C99, a CompoundLiteralExpr is an lvalue, and we defer evaluating the 3516 // initializer until now for such expressions. Such an expression can't be 3517 // an ICE in C, so this only matters for fold. 3518 if (Type.isVolatileQualified()) { 3519 Info.FFDiag(Conv); 3520 return false; 3521 } 3522 APValue Lit; 3523 if (!Evaluate(Lit, Info, CLE->getInitializer())) 3524 return false; 3525 CompleteObject LitObj(LVal.Base, &Lit, Base->getType()); 3526 return extractSubobject(Info, Conv, LitObj, LVal.Designator, RVal); 3527 } else if (isa<StringLiteral>(Base) || isa<PredefinedExpr>(Base)) { 3528 // Special-case character extraction so we don't have to construct an 3529 // APValue for the whole string. 3530 assert(LVal.Designator.Entries.size() <= 1 && 3531 "Can only read characters from string literals"); 3532 if (LVal.Designator.Entries.empty()) { 3533 // Fail for now for LValue to RValue conversion of an array. 3534 // (This shouldn't show up in C/C++, but it could be triggered by a 3535 // weird EvaluateAsRValue call from a tool.) 3536 Info.FFDiag(Conv); 3537 return false; 3538 } 3539 if (LVal.Designator.isOnePastTheEnd()) { 3540 if (Info.getLangOpts().CPlusPlus11) 3541 Info.FFDiag(Conv, diag::note_constexpr_access_past_end) << AK_Read; 3542 else 3543 Info.FFDiag(Conv); 3544 return false; 3545 } 3546 uint64_t CharIndex = LVal.Designator.Entries[0].getAsArrayIndex(); 3547 RVal = APValue(extractStringLiteralCharacter(Info, Base, CharIndex)); 3548 return true; 3549 } 3550 } 3551 3552 CompleteObject Obj = findCompleteObject(Info, Conv, AK_Read, LVal, Type); 3553 return Obj && extractSubobject(Info, Conv, Obj, LVal.Designator, RVal); 3554 } 3555 3556 /// Perform an assignment of Val to LVal. Takes ownership of Val. 3557 static bool handleAssignment(EvalInfo &Info, const Expr *E, const LValue &LVal, 3558 QualType LValType, APValue &Val) { 3559 if (LVal.Designator.Invalid) 3560 return false; 3561 3562 if (!Info.getLangOpts().CPlusPlus14) { 3563 Info.FFDiag(E); 3564 return false; 3565 } 3566 3567 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); 3568 return Obj && modifySubobject(Info, E, Obj, LVal.Designator, Val); 3569 } 3570 3571 namespace { 3572 struct CompoundAssignSubobjectHandler { 3573 EvalInfo &Info; 3574 const Expr *E; 3575 QualType PromotedLHSType; 3576 BinaryOperatorKind Opcode; 3577 const APValue &RHS; 3578 3579 static const AccessKinds AccessKind = AK_Assign; 3580 3581 typedef bool result_type; 3582 3583 bool checkConst(QualType QT) { 3584 // Assigning to a const object has undefined behavior. 3585 if (QT.isConstQualified()) { 3586 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; 3587 return false; 3588 } 3589 return true; 3590 } 3591 3592 bool failed() { return false; } 3593 bool found(APValue &Subobj, QualType SubobjType) { 3594 switch (Subobj.getKind()) { 3595 case APValue::Int: 3596 return found(Subobj.getInt(), SubobjType); 3597 case APValue::Float: 3598 return found(Subobj.getFloat(), SubobjType); 3599 case APValue::ComplexInt: 3600 case APValue::ComplexFloat: 3601 // FIXME: Implement complex compound assignment. 3602 Info.FFDiag(E); 3603 return false; 3604 case APValue::LValue: 3605 return foundPointer(Subobj, SubobjType); 3606 default: 3607 // FIXME: can this happen? 3608 Info.FFDiag(E); 3609 return false; 3610 } 3611 } 3612 bool found(APSInt &Value, QualType SubobjType) { 3613 if (!checkConst(SubobjType)) 3614 return false; 3615 3616 if (!SubobjType->isIntegerType()) { 3617 // We don't support compound assignment on integer-cast-to-pointer 3618 // values. 3619 Info.FFDiag(E); 3620 return false; 3621 } 3622 3623 if (RHS.isInt()) { 3624 APSInt LHS = 3625 HandleIntToIntCast(Info, E, PromotedLHSType, SubobjType, Value); 3626 if (!handleIntIntBinOp(Info, E, LHS, Opcode, RHS.getInt(), LHS)) 3627 return false; 3628 Value = HandleIntToIntCast(Info, E, SubobjType, PromotedLHSType, LHS); 3629 return true; 3630 } else if (RHS.isFloat()) { 3631 APFloat FValue(0.0); 3632 return HandleIntToFloatCast(Info, E, SubobjType, Value, PromotedLHSType, 3633 FValue) && 3634 handleFloatFloatBinOp(Info, E, FValue, Opcode, RHS.getFloat()) && 3635 HandleFloatToIntCast(Info, E, PromotedLHSType, FValue, SubobjType, 3636 Value); 3637 } 3638 3639 Info.FFDiag(E); 3640 return false; 3641 } 3642 bool found(APFloat &Value, QualType SubobjType) { 3643 return checkConst(SubobjType) && 3644 HandleFloatToFloatCast(Info, E, SubobjType, PromotedLHSType, 3645 Value) && 3646 handleFloatFloatBinOp(Info, E, Value, Opcode, RHS.getFloat()) && 3647 HandleFloatToFloatCast(Info, E, PromotedLHSType, SubobjType, Value); 3648 } 3649 bool foundPointer(APValue &Subobj, QualType SubobjType) { 3650 if (!checkConst(SubobjType)) 3651 return false; 3652 3653 QualType PointeeType; 3654 if (const PointerType *PT = SubobjType->getAs<PointerType>()) 3655 PointeeType = PT->getPointeeType(); 3656 3657 if (PointeeType.isNull() || !RHS.isInt() || 3658 (Opcode != BO_Add && Opcode != BO_Sub)) { 3659 Info.FFDiag(E); 3660 return false; 3661 } 3662 3663 APSInt Offset = RHS.getInt(); 3664 if (Opcode == BO_Sub) 3665 negateAsSigned(Offset); 3666 3667 LValue LVal; 3668 LVal.setFrom(Info.Ctx, Subobj); 3669 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, Offset)) 3670 return false; 3671 LVal.moveInto(Subobj); 3672 return true; 3673 } 3674 }; 3675 } // end anonymous namespace 3676 3677 const AccessKinds CompoundAssignSubobjectHandler::AccessKind; 3678 3679 /// Perform a compound assignment of LVal <op>= RVal. 3680 static bool handleCompoundAssignment( 3681 EvalInfo &Info, const Expr *E, 3682 const LValue &LVal, QualType LValType, QualType PromotedLValType, 3683 BinaryOperatorKind Opcode, const APValue &RVal) { 3684 if (LVal.Designator.Invalid) 3685 return false; 3686 3687 if (!Info.getLangOpts().CPlusPlus14) { 3688 Info.FFDiag(E); 3689 return false; 3690 } 3691 3692 CompleteObject Obj = findCompleteObject(Info, E, AK_Assign, LVal, LValType); 3693 CompoundAssignSubobjectHandler Handler = { Info, E, PromotedLValType, Opcode, 3694 RVal }; 3695 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); 3696 } 3697 3698 namespace { 3699 struct IncDecSubobjectHandler { 3700 EvalInfo &Info; 3701 const UnaryOperator *E; 3702 AccessKinds AccessKind; 3703 APValue *Old; 3704 3705 typedef bool result_type; 3706 3707 bool checkConst(QualType QT) { 3708 // Assigning to a const object has undefined behavior. 3709 if (QT.isConstQualified()) { 3710 Info.FFDiag(E, diag::note_constexpr_modify_const_type) << QT; 3711 return false; 3712 } 3713 return true; 3714 } 3715 3716 bool failed() { return false; } 3717 bool found(APValue &Subobj, QualType SubobjType) { 3718 // Stash the old value. Also clear Old, so we don't clobber it later 3719 // if we're post-incrementing a complex. 3720 if (Old) { 3721 *Old = Subobj; 3722 Old = nullptr; 3723 } 3724 3725 switch (Subobj.getKind()) { 3726 case APValue::Int: 3727 return found(Subobj.getInt(), SubobjType); 3728 case APValue::Float: 3729 return found(Subobj.getFloat(), SubobjType); 3730 case APValue::ComplexInt: 3731 return found(Subobj.getComplexIntReal(), 3732 SubobjType->castAs<ComplexType>()->getElementType() 3733 .withCVRQualifiers(SubobjType.getCVRQualifiers())); 3734 case APValue::ComplexFloat: 3735 return found(Subobj.getComplexFloatReal(), 3736 SubobjType->castAs<ComplexType>()->getElementType() 3737 .withCVRQualifiers(SubobjType.getCVRQualifiers())); 3738 case APValue::LValue: 3739 return foundPointer(Subobj, SubobjType); 3740 default: 3741 // FIXME: can this happen? 3742 Info.FFDiag(E); 3743 return false; 3744 } 3745 } 3746 bool found(APSInt &Value, QualType SubobjType) { 3747 if (!checkConst(SubobjType)) 3748 return false; 3749 3750 if (!SubobjType->isIntegerType()) { 3751 // We don't support increment / decrement on integer-cast-to-pointer 3752 // values. 3753 Info.FFDiag(E); 3754 return false; 3755 } 3756 3757 if (Old) *Old = APValue(Value); 3758 3759 // bool arithmetic promotes to int, and the conversion back to bool 3760 // doesn't reduce mod 2^n, so special-case it. 3761 if (SubobjType->isBooleanType()) { 3762 if (AccessKind == AK_Increment) 3763 Value = 1; 3764 else 3765 Value = !Value; 3766 return true; 3767 } 3768 3769 bool WasNegative = Value.isNegative(); 3770 if (AccessKind == AK_Increment) { 3771 ++Value; 3772 3773 if (!WasNegative && Value.isNegative() && E->canOverflow()) { 3774 APSInt ActualValue(Value, /*IsUnsigned*/true); 3775 return HandleOverflow(Info, E, ActualValue, SubobjType); 3776 } 3777 } else { 3778 --Value; 3779 3780 if (WasNegative && !Value.isNegative() && E->canOverflow()) { 3781 unsigned BitWidth = Value.getBitWidth(); 3782 APSInt ActualValue(Value.sext(BitWidth + 1), /*IsUnsigned*/false); 3783 ActualValue.setBit(BitWidth); 3784 return HandleOverflow(Info, E, ActualValue, SubobjType); 3785 } 3786 } 3787 return true; 3788 } 3789 bool found(APFloat &Value, QualType SubobjType) { 3790 if (!checkConst(SubobjType)) 3791 return false; 3792 3793 if (Old) *Old = APValue(Value); 3794 3795 APFloat One(Value.getSemantics(), 1); 3796 if (AccessKind == AK_Increment) 3797 Value.add(One, APFloat::rmNearestTiesToEven); 3798 else 3799 Value.subtract(One, APFloat::rmNearestTiesToEven); 3800 return true; 3801 } 3802 bool foundPointer(APValue &Subobj, QualType SubobjType) { 3803 if (!checkConst(SubobjType)) 3804 return false; 3805 3806 QualType PointeeType; 3807 if (const PointerType *PT = SubobjType->getAs<PointerType>()) 3808 PointeeType = PT->getPointeeType(); 3809 else { 3810 Info.FFDiag(E); 3811 return false; 3812 } 3813 3814 LValue LVal; 3815 LVal.setFrom(Info.Ctx, Subobj); 3816 if (!HandleLValueArrayAdjustment(Info, E, LVal, PointeeType, 3817 AccessKind == AK_Increment ? 1 : -1)) 3818 return false; 3819 LVal.moveInto(Subobj); 3820 return true; 3821 } 3822 }; 3823 } // end anonymous namespace 3824 3825 /// Perform an increment or decrement on LVal. 3826 static bool handleIncDec(EvalInfo &Info, const Expr *E, const LValue &LVal, 3827 QualType LValType, bool IsIncrement, APValue *Old) { 3828 if (LVal.Designator.Invalid) 3829 return false; 3830 3831 if (!Info.getLangOpts().CPlusPlus14) { 3832 Info.FFDiag(E); 3833 return false; 3834 } 3835 3836 AccessKinds AK = IsIncrement ? AK_Increment : AK_Decrement; 3837 CompleteObject Obj = findCompleteObject(Info, E, AK, LVal, LValType); 3838 IncDecSubobjectHandler Handler = {Info, cast<UnaryOperator>(E), AK, Old}; 3839 return Obj && findSubobject(Info, E, Obj, LVal.Designator, Handler); 3840 } 3841 3842 /// Build an lvalue for the object argument of a member function call. 3843 static bool EvaluateObjectArgument(EvalInfo &Info, const Expr *Object, 3844 LValue &This) { 3845 if (Object->getType()->isPointerType()) 3846 return EvaluatePointer(Object, This, Info); 3847 3848 if (Object->isGLValue()) 3849 return EvaluateLValue(Object, This, Info); 3850 3851 if (Object->getType()->isLiteralType(Info.Ctx)) 3852 return EvaluateTemporary(Object, This, Info); 3853 3854 Info.FFDiag(Object, diag::note_constexpr_nonliteral) << Object->getType(); 3855 return false; 3856 } 3857 3858 /// HandleMemberPointerAccess - Evaluate a member access operation and build an 3859 /// lvalue referring to the result. 3860 /// 3861 /// \param Info - Information about the ongoing evaluation. 3862 /// \param LV - An lvalue referring to the base of the member pointer. 3863 /// \param RHS - The member pointer expression. 3864 /// \param IncludeMember - Specifies whether the member itself is included in 3865 /// the resulting LValue subobject designator. This is not possible when 3866 /// creating a bound member function. 3867 /// \return The field or method declaration to which the member pointer refers, 3868 /// or 0 if evaluation fails. 3869 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, 3870 QualType LVType, 3871 LValue &LV, 3872 const Expr *RHS, 3873 bool IncludeMember = true) { 3874 MemberPtr MemPtr; 3875 if (!EvaluateMemberPointer(RHS, MemPtr, Info)) 3876 return nullptr; 3877 3878 // C++11 [expr.mptr.oper]p6: If the second operand is the null pointer to 3879 // member value, the behavior is undefined. 3880 if (!MemPtr.getDecl()) { 3881 // FIXME: Specific diagnostic. 3882 Info.FFDiag(RHS); 3883 return nullptr; 3884 } 3885 3886 if (MemPtr.isDerivedMember()) { 3887 // This is a member of some derived class. Truncate LV appropriately. 3888 // The end of the derived-to-base path for the base object must match the 3889 // derived-to-base path for the member pointer. 3890 if (LV.Designator.MostDerivedPathLength + MemPtr.Path.size() > 3891 LV.Designator.Entries.size()) { 3892 Info.FFDiag(RHS); 3893 return nullptr; 3894 } 3895 unsigned PathLengthToMember = 3896 LV.Designator.Entries.size() - MemPtr.Path.size(); 3897 for (unsigned I = 0, N = MemPtr.Path.size(); I != N; ++I) { 3898 const CXXRecordDecl *LVDecl = getAsBaseClass( 3899 LV.Designator.Entries[PathLengthToMember + I]); 3900 const CXXRecordDecl *MPDecl = MemPtr.Path[I]; 3901 if (LVDecl->getCanonicalDecl() != MPDecl->getCanonicalDecl()) { 3902 Info.FFDiag(RHS); 3903 return nullptr; 3904 } 3905 } 3906 3907 // Truncate the lvalue to the appropriate derived class. 3908 if (!CastToDerivedClass(Info, RHS, LV, MemPtr.getContainingRecord(), 3909 PathLengthToMember)) 3910 return nullptr; 3911 } else if (!MemPtr.Path.empty()) { 3912 // Extend the LValue path with the member pointer's path. 3913 LV.Designator.Entries.reserve(LV.Designator.Entries.size() + 3914 MemPtr.Path.size() + IncludeMember); 3915 3916 // Walk down to the appropriate base class. 3917 if (const PointerType *PT = LVType->getAs<PointerType>()) 3918 LVType = PT->getPointeeType(); 3919 const CXXRecordDecl *RD = LVType->getAsCXXRecordDecl(); 3920 assert(RD && "member pointer access on non-class-type expression"); 3921 // The first class in the path is that of the lvalue. 3922 for (unsigned I = 1, N = MemPtr.Path.size(); I != N; ++I) { 3923 const CXXRecordDecl *Base = MemPtr.Path[N - I - 1]; 3924 if (!HandleLValueDirectBase(Info, RHS, LV, RD, Base)) 3925 return nullptr; 3926 RD = Base; 3927 } 3928 // Finally cast to the class containing the member. 3929 if (!HandleLValueDirectBase(Info, RHS, LV, RD, 3930 MemPtr.getContainingRecord())) 3931 return nullptr; 3932 } 3933 3934 // Add the member. Note that we cannot build bound member functions here. 3935 if (IncludeMember) { 3936 if (const FieldDecl *FD = dyn_cast<FieldDecl>(MemPtr.getDecl())) { 3937 if (!HandleLValueMember(Info, RHS, LV, FD)) 3938 return nullptr; 3939 } else if (const IndirectFieldDecl *IFD = 3940 dyn_cast<IndirectFieldDecl>(MemPtr.getDecl())) { 3941 if (!HandleLValueIndirectMember(Info, RHS, LV, IFD)) 3942 return nullptr; 3943 } else { 3944 llvm_unreachable("can't construct reference to bound member function"); 3945 } 3946 } 3947 3948 return MemPtr.getDecl(); 3949 } 3950 3951 static const ValueDecl *HandleMemberPointerAccess(EvalInfo &Info, 3952 const BinaryOperator *BO, 3953 LValue &LV, 3954 bool IncludeMember = true) { 3955 assert(BO->getOpcode() == BO_PtrMemD || BO->getOpcode() == BO_PtrMemI); 3956 3957 if (!EvaluateObjectArgument(Info, BO->getLHS(), LV)) { 3958 if (Info.noteFailure()) { 3959 MemberPtr MemPtr; 3960 EvaluateMemberPointer(BO->getRHS(), MemPtr, Info); 3961 } 3962 return nullptr; 3963 } 3964 3965 return HandleMemberPointerAccess(Info, BO->getLHS()->getType(), LV, 3966 BO->getRHS(), IncludeMember); 3967 } 3968 3969 /// HandleBaseToDerivedCast - Apply the given base-to-derived cast operation on 3970 /// the provided lvalue, which currently refers to the base object. 3971 static bool HandleBaseToDerivedCast(EvalInfo &Info, const CastExpr *E, 3972 LValue &Result) { 3973 SubobjectDesignator &D = Result.Designator; 3974 if (D.Invalid || !Result.checkNullPointer(Info, E, CSK_Derived)) 3975 return false; 3976 3977 QualType TargetQT = E->getType(); 3978 if (const PointerType *PT = TargetQT->getAs<PointerType>()) 3979 TargetQT = PT->getPointeeType(); 3980 3981 // Check this cast lands within the final derived-to-base subobject path. 3982 if (D.MostDerivedPathLength + E->path_size() > D.Entries.size()) { 3983 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) 3984 << D.MostDerivedType << TargetQT; 3985 return false; 3986 } 3987 3988 // Check the type of the final cast. We don't need to check the path, 3989 // since a cast can only be formed if the path is unique. 3990 unsigned NewEntriesSize = D.Entries.size() - E->path_size(); 3991 const CXXRecordDecl *TargetType = TargetQT->getAsCXXRecordDecl(); 3992 const CXXRecordDecl *FinalType; 3993 if (NewEntriesSize == D.MostDerivedPathLength) 3994 FinalType = D.MostDerivedType->getAsCXXRecordDecl(); 3995 else 3996 FinalType = getAsBaseClass(D.Entries[NewEntriesSize - 1]); 3997 if (FinalType->getCanonicalDecl() != TargetType->getCanonicalDecl()) { 3998 Info.CCEDiag(E, diag::note_constexpr_invalid_downcast) 3999 << D.MostDerivedType << TargetQT; 4000 return false; 4001 } 4002 4003 // Truncate the lvalue to the appropriate derived class. 4004 return CastToDerivedClass(Info, E, Result, TargetType, NewEntriesSize); 4005 } 4006 4007 namespace { 4008 enum EvalStmtResult { 4009 /// Evaluation failed. 4010 ESR_Failed, 4011 /// Hit a 'return' statement. 4012 ESR_Returned, 4013 /// Evaluation succeeded. 4014 ESR_Succeeded, 4015 /// Hit a 'continue' statement. 4016 ESR_Continue, 4017 /// Hit a 'break' statement. 4018 ESR_Break, 4019 /// Still scanning for 'case' or 'default' statement. 4020 ESR_CaseNotFound 4021 }; 4022 } 4023 4024 static bool EvaluateVarDecl(EvalInfo &Info, const VarDecl *VD) { 4025 // We don't need to evaluate the initializer for a static local. 4026 if (!VD->hasLocalStorage()) 4027 return true; 4028 4029 LValue Result; 4030 APValue &Val = createTemporary(VD, true, Result, *Info.CurrentCall); 4031 4032 const Expr *InitE = VD->getInit(); 4033 if (!InitE) { 4034 Info.FFDiag(VD->getBeginLoc(), diag::note_constexpr_uninitialized) 4035 << false << VD->getType(); 4036 Val = APValue(); 4037 return false; 4038 } 4039 4040 if (InitE->isValueDependent()) 4041 return false; 4042 4043 if (!EvaluateInPlace(Val, Info, Result, InitE)) { 4044 // Wipe out any partially-computed value, to allow tracking that this 4045 // evaluation failed. 4046 Val = APValue(); 4047 return false; 4048 } 4049 4050 return true; 4051 } 4052 4053 static bool EvaluateDecl(EvalInfo &Info, const Decl *D) { 4054 bool OK = true; 4055 4056 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 4057 OK &= EvaluateVarDecl(Info, VD); 4058 4059 if (const DecompositionDecl *DD = dyn_cast<DecompositionDecl>(D)) 4060 for (auto *BD : DD->bindings()) 4061 if (auto *VD = BD->getHoldingVar()) 4062 OK &= EvaluateDecl(Info, VD); 4063 4064 return OK; 4065 } 4066 4067 4068 /// Evaluate a condition (either a variable declaration or an expression). 4069 static bool EvaluateCond(EvalInfo &Info, const VarDecl *CondDecl, 4070 const Expr *Cond, bool &Result) { 4071 FullExpressionRAII Scope(Info); 4072 if (CondDecl && !EvaluateDecl(Info, CondDecl)) 4073 return false; 4074 return EvaluateAsBooleanCondition(Cond, Result, Info); 4075 } 4076 4077 namespace { 4078 /// A location where the result (returned value) of evaluating a 4079 /// statement should be stored. 4080 struct StmtResult { 4081 /// The APValue that should be filled in with the returned value. 4082 APValue &Value; 4083 /// The location containing the result, if any (used to support RVO). 4084 const LValue *Slot; 4085 }; 4086 4087 struct TempVersionRAII { 4088 CallStackFrame &Frame; 4089 4090 TempVersionRAII(CallStackFrame &Frame) : Frame(Frame) { 4091 Frame.pushTempVersion(); 4092 } 4093 4094 ~TempVersionRAII() { 4095 Frame.popTempVersion(); 4096 } 4097 }; 4098 4099 } 4100 4101 static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info, 4102 const Stmt *S, 4103 const SwitchCase *SC = nullptr); 4104 4105 /// Evaluate the body of a loop, and translate the result as appropriate. 4106 static EvalStmtResult EvaluateLoopBody(StmtResult &Result, EvalInfo &Info, 4107 const Stmt *Body, 4108 const SwitchCase *Case = nullptr) { 4109 BlockScopeRAII Scope(Info); 4110 switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, Body, Case)) { 4111 case ESR_Break: 4112 return ESR_Succeeded; 4113 case ESR_Succeeded: 4114 case ESR_Continue: 4115 return ESR_Continue; 4116 case ESR_Failed: 4117 case ESR_Returned: 4118 case ESR_CaseNotFound: 4119 return ESR; 4120 } 4121 llvm_unreachable("Invalid EvalStmtResult!"); 4122 } 4123 4124 /// Evaluate a switch statement. 4125 static EvalStmtResult EvaluateSwitch(StmtResult &Result, EvalInfo &Info, 4126 const SwitchStmt *SS) { 4127 BlockScopeRAII Scope(Info); 4128 4129 // Evaluate the switch condition. 4130 APSInt Value; 4131 { 4132 FullExpressionRAII Scope(Info); 4133 if (const Stmt *Init = SS->getInit()) { 4134 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init); 4135 if (ESR != ESR_Succeeded) 4136 return ESR; 4137 } 4138 if (SS->getConditionVariable() && 4139 !EvaluateDecl(Info, SS->getConditionVariable())) 4140 return ESR_Failed; 4141 if (!EvaluateInteger(SS->getCond(), Value, Info)) 4142 return ESR_Failed; 4143 } 4144 4145 // Find the switch case corresponding to the value of the condition. 4146 // FIXME: Cache this lookup. 4147 const SwitchCase *Found = nullptr; 4148 for (const SwitchCase *SC = SS->getSwitchCaseList(); SC; 4149 SC = SC->getNextSwitchCase()) { 4150 if (isa<DefaultStmt>(SC)) { 4151 Found = SC; 4152 continue; 4153 } 4154 4155 const CaseStmt *CS = cast<CaseStmt>(SC); 4156 APSInt LHS = CS->getLHS()->EvaluateKnownConstInt(Info.Ctx); 4157 APSInt RHS = CS->getRHS() ? CS->getRHS()->EvaluateKnownConstInt(Info.Ctx) 4158 : LHS; 4159 if (LHS <= Value && Value <= RHS) { 4160 Found = SC; 4161 break; 4162 } 4163 } 4164 4165 if (!Found) 4166 return ESR_Succeeded; 4167 4168 // Search the switch body for the switch case and evaluate it from there. 4169 switch (EvalStmtResult ESR = EvaluateStmt(Result, Info, SS->getBody(), Found)) { 4170 case ESR_Break: 4171 return ESR_Succeeded; 4172 case ESR_Succeeded: 4173 case ESR_Continue: 4174 case ESR_Failed: 4175 case ESR_Returned: 4176 return ESR; 4177 case ESR_CaseNotFound: 4178 // This can only happen if the switch case is nested within a statement 4179 // expression. We have no intention of supporting that. 4180 Info.FFDiag(Found->getBeginLoc(), 4181 diag::note_constexpr_stmt_expr_unsupported); 4182 return ESR_Failed; 4183 } 4184 llvm_unreachable("Invalid EvalStmtResult!"); 4185 } 4186 4187 // Evaluate a statement. 4188 static EvalStmtResult EvaluateStmt(StmtResult &Result, EvalInfo &Info, 4189 const Stmt *S, const SwitchCase *Case) { 4190 if (!Info.nextStep(S)) 4191 return ESR_Failed; 4192 4193 // If we're hunting down a 'case' or 'default' label, recurse through 4194 // substatements until we hit the label. 4195 if (Case) { 4196 // FIXME: We don't start the lifetime of objects whose initialization we 4197 // jump over. However, such objects must be of class type with a trivial 4198 // default constructor that initialize all subobjects, so must be empty, 4199 // so this almost never matters. 4200 switch (S->getStmtClass()) { 4201 case Stmt::CompoundStmtClass: 4202 // FIXME: Precompute which substatement of a compound statement we 4203 // would jump to, and go straight there rather than performing a 4204 // linear scan each time. 4205 case Stmt::LabelStmtClass: 4206 case Stmt::AttributedStmtClass: 4207 case Stmt::DoStmtClass: 4208 break; 4209 4210 case Stmt::CaseStmtClass: 4211 case Stmt::DefaultStmtClass: 4212 if (Case == S) 4213 Case = nullptr; 4214 break; 4215 4216 case Stmt::IfStmtClass: { 4217 // FIXME: Precompute which side of an 'if' we would jump to, and go 4218 // straight there rather than scanning both sides. 4219 const IfStmt *IS = cast<IfStmt>(S); 4220 4221 // Wrap the evaluation in a block scope, in case it's a DeclStmt 4222 // preceded by our switch label. 4223 BlockScopeRAII Scope(Info); 4224 4225 EvalStmtResult ESR = EvaluateStmt(Result, Info, IS->getThen(), Case); 4226 if (ESR != ESR_CaseNotFound || !IS->getElse()) 4227 return ESR; 4228 return EvaluateStmt(Result, Info, IS->getElse(), Case); 4229 } 4230 4231 case Stmt::WhileStmtClass: { 4232 EvalStmtResult ESR = 4233 EvaluateLoopBody(Result, Info, cast<WhileStmt>(S)->getBody(), Case); 4234 if (ESR != ESR_Continue) 4235 return ESR; 4236 break; 4237 } 4238 4239 case Stmt::ForStmtClass: { 4240 const ForStmt *FS = cast<ForStmt>(S); 4241 EvalStmtResult ESR = 4242 EvaluateLoopBody(Result, Info, FS->getBody(), Case); 4243 if (ESR != ESR_Continue) 4244 return ESR; 4245 if (FS->getInc()) { 4246 FullExpressionRAII IncScope(Info); 4247 if (!EvaluateIgnoredValue(Info, FS->getInc())) 4248 return ESR_Failed; 4249 } 4250 break; 4251 } 4252 4253 case Stmt::DeclStmtClass: 4254 // FIXME: If the variable has initialization that can't be jumped over, 4255 // bail out of any immediately-surrounding compound-statement too. 4256 default: 4257 return ESR_CaseNotFound; 4258 } 4259 } 4260 4261 switch (S->getStmtClass()) { 4262 default: 4263 if (const Expr *E = dyn_cast<Expr>(S)) { 4264 // Don't bother evaluating beyond an expression-statement which couldn't 4265 // be evaluated. 4266 FullExpressionRAII Scope(Info); 4267 if (!EvaluateIgnoredValue(Info, E)) 4268 return ESR_Failed; 4269 return ESR_Succeeded; 4270 } 4271 4272 Info.FFDiag(S->getBeginLoc()); 4273 return ESR_Failed; 4274 4275 case Stmt::NullStmtClass: 4276 return ESR_Succeeded; 4277 4278 case Stmt::DeclStmtClass: { 4279 const DeclStmt *DS = cast<DeclStmt>(S); 4280 for (const auto *DclIt : DS->decls()) { 4281 // Each declaration initialization is its own full-expression. 4282 // FIXME: This isn't quite right; if we're performing aggregate 4283 // initialization, each braced subexpression is its own full-expression. 4284 FullExpressionRAII Scope(Info); 4285 if (!EvaluateDecl(Info, DclIt) && !Info.noteFailure()) 4286 return ESR_Failed; 4287 } 4288 return ESR_Succeeded; 4289 } 4290 4291 case Stmt::ReturnStmtClass: { 4292 const Expr *RetExpr = cast<ReturnStmt>(S)->getRetValue(); 4293 FullExpressionRAII Scope(Info); 4294 if (RetExpr && 4295 !(Result.Slot 4296 ? EvaluateInPlace(Result.Value, Info, *Result.Slot, RetExpr) 4297 : Evaluate(Result.Value, Info, RetExpr))) 4298 return ESR_Failed; 4299 return ESR_Returned; 4300 } 4301 4302 case Stmt::CompoundStmtClass: { 4303 BlockScopeRAII Scope(Info); 4304 4305 const CompoundStmt *CS = cast<CompoundStmt>(S); 4306 for (const auto *BI : CS->body()) { 4307 EvalStmtResult ESR = EvaluateStmt(Result, Info, BI, Case); 4308 if (ESR == ESR_Succeeded) 4309 Case = nullptr; 4310 else if (ESR != ESR_CaseNotFound) 4311 return ESR; 4312 } 4313 return Case ? ESR_CaseNotFound : ESR_Succeeded; 4314 } 4315 4316 case Stmt::IfStmtClass: { 4317 const IfStmt *IS = cast<IfStmt>(S); 4318 4319 // Evaluate the condition, as either a var decl or as an expression. 4320 BlockScopeRAII Scope(Info); 4321 if (const Stmt *Init = IS->getInit()) { 4322 EvalStmtResult ESR = EvaluateStmt(Result, Info, Init); 4323 if (ESR != ESR_Succeeded) 4324 return ESR; 4325 } 4326 bool Cond; 4327 if (!EvaluateCond(Info, IS->getConditionVariable(), IS->getCond(), Cond)) 4328 return ESR_Failed; 4329 4330 if (const Stmt *SubStmt = Cond ? IS->getThen() : IS->getElse()) { 4331 EvalStmtResult ESR = EvaluateStmt(Result, Info, SubStmt); 4332 if (ESR != ESR_Succeeded) 4333 return ESR; 4334 } 4335 return ESR_Succeeded; 4336 } 4337 4338 case Stmt::WhileStmtClass: { 4339 const WhileStmt *WS = cast<WhileStmt>(S); 4340 while (true) { 4341 BlockScopeRAII Scope(Info); 4342 bool Continue; 4343 if (!EvaluateCond(Info, WS->getConditionVariable(), WS->getCond(), 4344 Continue)) 4345 return ESR_Failed; 4346 if (!Continue) 4347 break; 4348 4349 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, WS->getBody()); 4350 if (ESR != ESR_Continue) 4351 return ESR; 4352 } 4353 return ESR_Succeeded; 4354 } 4355 4356 case Stmt::DoStmtClass: { 4357 const DoStmt *DS = cast<DoStmt>(S); 4358 bool Continue; 4359 do { 4360 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, DS->getBody(), Case); 4361 if (ESR != ESR_Continue) 4362 return ESR; 4363 Case = nullptr; 4364 4365 FullExpressionRAII CondScope(Info); 4366 if (!EvaluateAsBooleanCondition(DS->getCond(), Continue, Info)) 4367 return ESR_Failed; 4368 } while (Continue); 4369 return ESR_Succeeded; 4370 } 4371 4372 case Stmt::ForStmtClass: { 4373 const ForStmt *FS = cast<ForStmt>(S); 4374 BlockScopeRAII Scope(Info); 4375 if (FS->getInit()) { 4376 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit()); 4377 if (ESR != ESR_Succeeded) 4378 return ESR; 4379 } 4380 while (true) { 4381 BlockScopeRAII Scope(Info); 4382 bool Continue = true; 4383 if (FS->getCond() && !EvaluateCond(Info, FS->getConditionVariable(), 4384 FS->getCond(), Continue)) 4385 return ESR_Failed; 4386 if (!Continue) 4387 break; 4388 4389 EvalStmtResult ESR = EvaluateLoopBody(Result, Info, FS->getBody()); 4390 if (ESR != ESR_Continue) 4391 return ESR; 4392 4393 if (FS->getInc()) { 4394 FullExpressionRAII IncScope(Info); 4395 if (!EvaluateIgnoredValue(Info, FS->getInc())) 4396 return ESR_Failed; 4397 } 4398 } 4399 return ESR_Succeeded; 4400 } 4401 4402 case Stmt::CXXForRangeStmtClass: { 4403 const CXXForRangeStmt *FS = cast<CXXForRangeStmt>(S); 4404 BlockScopeRAII Scope(Info); 4405 4406 // Evaluate the init-statement if present. 4407 if (FS->getInit()) { 4408 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getInit()); 4409 if (ESR != ESR_Succeeded) 4410 return ESR; 4411 } 4412 4413 // Initialize the __range variable. 4414 EvalStmtResult ESR = EvaluateStmt(Result, Info, FS->getRangeStmt()); 4415 if (ESR != ESR_Succeeded) 4416 return ESR; 4417 4418 // Create the __begin and __end iterators. 4419 ESR = EvaluateStmt(Result, Info, FS->getBeginStmt()); 4420 if (ESR != ESR_Succeeded) 4421 return ESR; 4422 ESR = EvaluateStmt(Result, Info, FS->getEndStmt()); 4423 if (ESR != ESR_Succeeded) 4424 return ESR; 4425 4426 while (true) { 4427 // Condition: __begin != __end. 4428 { 4429 bool Continue = true; 4430 FullExpressionRAII CondExpr(Info); 4431 if (!EvaluateAsBooleanCondition(FS->getCond(), Continue, Info)) 4432 return ESR_Failed; 4433 if (!Continue) 4434 break; 4435 } 4436 4437 // User's variable declaration, initialized by *__begin. 4438 BlockScopeRAII InnerScope(Info); 4439 ESR = EvaluateStmt(Result, Info, FS->getLoopVarStmt()); 4440 if (ESR != ESR_Succeeded) 4441 return ESR; 4442 4443 // Loop body. 4444 ESR = EvaluateLoopBody(Result, Info, FS->getBody()); 4445 if (ESR != ESR_Continue) 4446 return ESR; 4447 4448 // Increment: ++__begin 4449 if (!EvaluateIgnoredValue(Info, FS->getInc())) 4450 return ESR_Failed; 4451 } 4452 4453 return ESR_Succeeded; 4454 } 4455 4456 case Stmt::SwitchStmtClass: 4457 return EvaluateSwitch(Result, Info, cast<SwitchStmt>(S)); 4458 4459 case Stmt::ContinueStmtClass: 4460 return ESR_Continue; 4461 4462 case Stmt::BreakStmtClass: 4463 return ESR_Break; 4464 4465 case Stmt::LabelStmtClass: 4466 return EvaluateStmt(Result, Info, cast<LabelStmt>(S)->getSubStmt(), Case); 4467 4468 case Stmt::AttributedStmtClass: 4469 // As a general principle, C++11 attributes can be ignored without 4470 // any semantic impact. 4471 return EvaluateStmt(Result, Info, cast<AttributedStmt>(S)->getSubStmt(), 4472 Case); 4473 4474 case Stmt::CaseStmtClass: 4475 case Stmt::DefaultStmtClass: 4476 return EvaluateStmt(Result, Info, cast<SwitchCase>(S)->getSubStmt(), Case); 4477 case Stmt::CXXTryStmtClass: 4478 // Evaluate try blocks by evaluating all sub statements. 4479 return EvaluateStmt(Result, Info, cast<CXXTryStmt>(S)->getTryBlock(), Case); 4480 } 4481 } 4482 4483 /// CheckTrivialDefaultConstructor - Check whether a constructor is a trivial 4484 /// default constructor. If so, we'll fold it whether or not it's marked as 4485 /// constexpr. If it is marked as constexpr, we will never implicitly define it, 4486 /// so we need special handling. 4487 static bool CheckTrivialDefaultConstructor(EvalInfo &Info, SourceLocation Loc, 4488 const CXXConstructorDecl *CD, 4489 bool IsValueInitialization) { 4490 if (!CD->isTrivial() || !CD->isDefaultConstructor()) 4491 return false; 4492 4493 // Value-initialization does not call a trivial default constructor, so such a 4494 // call is a core constant expression whether or not the constructor is 4495 // constexpr. 4496 if (!CD->isConstexpr() && !IsValueInitialization) { 4497 if (Info.getLangOpts().CPlusPlus11) { 4498 // FIXME: If DiagDecl is an implicitly-declared special member function, 4499 // we should be much more explicit about why it's not constexpr. 4500 Info.CCEDiag(Loc, diag::note_constexpr_invalid_function, 1) 4501 << /*IsConstexpr*/0 << /*IsConstructor*/1 << CD; 4502 Info.Note(CD->getLocation(), diag::note_declared_at); 4503 } else { 4504 Info.CCEDiag(Loc, diag::note_invalid_subexpr_in_const_expr); 4505 } 4506 } 4507 return true; 4508 } 4509 4510 /// CheckConstexprFunction - Check that a function can be called in a constant 4511 /// expression. 4512 static bool CheckConstexprFunction(EvalInfo &Info, SourceLocation CallLoc, 4513 const FunctionDecl *Declaration, 4514 const FunctionDecl *Definition, 4515 const Stmt *Body) { 4516 // Potential constant expressions can contain calls to declared, but not yet 4517 // defined, constexpr functions. 4518 if (Info.checkingPotentialConstantExpression() && !Definition && 4519 Declaration->isConstexpr()) 4520 return false; 4521 4522 // Bail out if the function declaration itself is invalid. We will 4523 // have produced a relevant diagnostic while parsing it, so just 4524 // note the problematic sub-expression. 4525 if (Declaration->isInvalidDecl()) { 4526 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); 4527 return false; 4528 } 4529 4530 // DR1872: An instantiated virtual constexpr function can't be called in a 4531 // constant expression (prior to C++20). We can still constant-fold such a 4532 // call. 4533 if (!Info.Ctx.getLangOpts().CPlusPlus2a && isa<CXXMethodDecl>(Declaration) && 4534 cast<CXXMethodDecl>(Declaration)->isVirtual()) 4535 Info.CCEDiag(CallLoc, diag::note_constexpr_virtual_call); 4536 4537 if (Definition && Definition->isInvalidDecl()) { 4538 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); 4539 return false; 4540 } 4541 4542 // Can we evaluate this function call? 4543 if (Definition && Definition->isConstexpr() && Body) 4544 return true; 4545 4546 if (Info.getLangOpts().CPlusPlus11) { 4547 const FunctionDecl *DiagDecl = Definition ? Definition : Declaration; 4548 4549 // If this function is not constexpr because it is an inherited 4550 // non-constexpr constructor, diagnose that directly. 4551 auto *CD = dyn_cast<CXXConstructorDecl>(DiagDecl); 4552 if (CD && CD->isInheritingConstructor()) { 4553 auto *Inherited = CD->getInheritedConstructor().getConstructor(); 4554 if (!Inherited->isConstexpr()) 4555 DiagDecl = CD = Inherited; 4556 } 4557 4558 // FIXME: If DiagDecl is an implicitly-declared special member function 4559 // or an inheriting constructor, we should be much more explicit about why 4560 // it's not constexpr. 4561 if (CD && CD->isInheritingConstructor()) 4562 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_inhctor, 1) 4563 << CD->getInheritedConstructor().getConstructor()->getParent(); 4564 else 4565 Info.FFDiag(CallLoc, diag::note_constexpr_invalid_function, 1) 4566 << DiagDecl->isConstexpr() << (bool)CD << DiagDecl; 4567 Info.Note(DiagDecl->getLocation(), diag::note_declared_at); 4568 } else { 4569 Info.FFDiag(CallLoc, diag::note_invalid_subexpr_in_const_expr); 4570 } 4571 return false; 4572 } 4573 4574 namespace { 4575 struct CheckDynamicTypeHandler { 4576 AccessKinds AccessKind; 4577 typedef bool result_type; 4578 bool failed() { return false; } 4579 bool found(APValue &Subobj, QualType SubobjType) { return true; } 4580 bool found(APSInt &Value, QualType SubobjType) { return true; } 4581 bool found(APFloat &Value, QualType SubobjType) { return true; } 4582 }; 4583 } // end anonymous namespace 4584 4585 /// Check that we can access the notional vptr of an object / determine its 4586 /// dynamic type. 4587 static bool checkDynamicType(EvalInfo &Info, const Expr *E, const LValue &This, 4588 AccessKinds AK, bool Polymorphic) { 4589 if (This.Designator.Invalid) 4590 return false; 4591 4592 CompleteObject Obj = findCompleteObject(Info, E, AK, This, QualType()); 4593 4594 if (!Obj) 4595 return false; 4596 4597 if (!Obj.Value) { 4598 // The object is not usable in constant expressions, so we can't inspect 4599 // its value to see if it's in-lifetime or what the active union members 4600 // are. We can still check for a one-past-the-end lvalue. 4601 if (This.Designator.isOnePastTheEnd() || 4602 This.Designator.isMostDerivedAnUnsizedArray()) { 4603 Info.FFDiag(E, This.Designator.isOnePastTheEnd() 4604 ? diag::note_constexpr_access_past_end 4605 : diag::note_constexpr_access_unsized_array) 4606 << AK; 4607 return false; 4608 } else if (Polymorphic) { 4609 // Conservatively refuse to perform a polymorphic operation if we would 4610 // not be able to read a notional 'vptr' value. 4611 APValue Val; 4612 This.moveInto(Val); 4613 QualType StarThisType = 4614 Info.Ctx.getLValueReferenceType(This.Designator.getType(Info.Ctx)); 4615 Info.FFDiag(E, diag::note_constexpr_polymorphic_unknown_dynamic_type) 4616 << AK << Val.getAsString(Info.Ctx, StarThisType); 4617 return false; 4618 } 4619 return true; 4620 } 4621 4622 CheckDynamicTypeHandler Handler{AK}; 4623 return Obj && findSubobject(Info, E, Obj, This.Designator, Handler); 4624 } 4625 4626 /// Check that the pointee of the 'this' pointer in a member function call is 4627 /// either within its lifetime or in its period of construction or destruction. 4628 static bool checkNonVirtualMemberCallThisPointer(EvalInfo &Info, const Expr *E, 4629 const LValue &This) { 4630 return checkDynamicType(Info, E, This, AK_MemberCall, false); 4631 } 4632 4633 struct DynamicType { 4634 /// The dynamic class type of the object. 4635 const CXXRecordDecl *Type; 4636 /// The corresponding path length in the lvalue. 4637 unsigned PathLength; 4638 }; 4639 4640 static const CXXRecordDecl *getBaseClassType(SubobjectDesignator &Designator, 4641 unsigned PathLength) { 4642 assert(PathLength >= Designator.MostDerivedPathLength && PathLength <= 4643 Designator.Entries.size() && "invalid path length"); 4644 return (PathLength == Designator.MostDerivedPathLength) 4645 ? Designator.MostDerivedType->getAsCXXRecordDecl() 4646 : getAsBaseClass(Designator.Entries[PathLength - 1]); 4647 } 4648 4649 /// Determine the dynamic type of an object. 4650 static Optional<DynamicType> ComputeDynamicType(EvalInfo &Info, const Expr *E, 4651 LValue &This, AccessKinds AK) { 4652 // If we don't have an lvalue denoting an object of class type, there is no 4653 // meaningful dynamic type. (We consider objects of non-class type to have no 4654 // dynamic type.) 4655 if (!checkDynamicType(Info, E, This, AK, true)) 4656 return None; 4657 4658 // Refuse to compute a dynamic type in the presence of virtual bases. This 4659 // shouldn't happen other than in constant-folding situations, since literal 4660 // types can't have virtual bases. 4661 // 4662 // Note that consumers of DynamicType assume that the type has no virtual 4663 // bases, and will need modifications if this restriction is relaxed. 4664 const CXXRecordDecl *Class = 4665 This.Designator.MostDerivedType->getAsCXXRecordDecl(); 4666 if (!Class || Class->getNumVBases()) { 4667 Info.FFDiag(E); 4668 return None; 4669 } 4670 4671 // FIXME: For very deep class hierarchies, it might be beneficial to use a 4672 // binary search here instead. But the overwhelmingly common case is that 4673 // we're not in the middle of a constructor, so it probably doesn't matter 4674 // in practice. 4675 ArrayRef<APValue::LValuePathEntry> Path = This.Designator.Entries; 4676 for (unsigned PathLength = This.Designator.MostDerivedPathLength; 4677 PathLength <= Path.size(); ++PathLength) { 4678 switch (Info.isEvaluatingConstructor(This.getLValueBase(), 4679 Path.slice(0, PathLength))) { 4680 case ConstructionPhase::Bases: 4681 // We're constructing a base class. This is not the dynamic type. 4682 break; 4683 4684 case ConstructionPhase::None: 4685 case ConstructionPhase::AfterBases: 4686 // We've finished constructing the base classes, so this is the dynamic 4687 // type. 4688 return DynamicType{getBaseClassType(This.Designator, PathLength), 4689 PathLength}; 4690 } 4691 } 4692 4693 // CWG issue 1517: we're constructing a base class of the object described by 4694 // 'This', so that object has not yet begun its period of construction and 4695 // any polymorphic operation on it results in undefined behavior. 4696 Info.FFDiag(E); 4697 return None; 4698 } 4699 4700 /// Perform virtual dispatch. 4701 static const CXXMethodDecl *HandleVirtualDispatch( 4702 EvalInfo &Info, const Expr *E, LValue &This, const CXXMethodDecl *Found, 4703 llvm::SmallVectorImpl<QualType> &CovariantAdjustmentPath) { 4704 Optional<DynamicType> DynType = 4705 ComputeDynamicType(Info, E, This, AK_MemberCall); 4706 if (!DynType) 4707 return nullptr; 4708 4709 // Find the final overrider. It must be declared in one of the classes on the 4710 // path from the dynamic type to the static type. 4711 // FIXME: If we ever allow literal types to have virtual base classes, that 4712 // won't be true. 4713 const CXXMethodDecl *Callee = Found; 4714 unsigned PathLength = DynType->PathLength; 4715 for (/**/; PathLength <= This.Designator.Entries.size(); ++PathLength) { 4716 const CXXRecordDecl *Class = getBaseClassType(This.Designator, PathLength); 4717 const CXXMethodDecl *Overrider = 4718 Found->getCorrespondingMethodDeclaredInClass(Class, false); 4719 if (Overrider) { 4720 Callee = Overrider; 4721 break; 4722 } 4723 } 4724 4725 // C++2a [class.abstract]p6: 4726 // the effect of making a virtual call to a pure virtual function [...] is 4727 // undefined 4728 if (Callee->isPure()) { 4729 Info.FFDiag(E, diag::note_constexpr_pure_virtual_call, 1) << Callee; 4730 Info.Note(Callee->getLocation(), diag::note_declared_at); 4731 return nullptr; 4732 } 4733 4734 // If necessary, walk the rest of the path to determine the sequence of 4735 // covariant adjustment steps to apply. 4736 if (!Info.Ctx.hasSameUnqualifiedType(Callee->getReturnType(), 4737 Found->getReturnType())) { 4738 CovariantAdjustmentPath.push_back(Callee->getReturnType()); 4739 for (unsigned CovariantPathLength = PathLength + 1; 4740 CovariantPathLength != This.Designator.Entries.size(); 4741 ++CovariantPathLength) { 4742 const CXXRecordDecl *NextClass = 4743 getBaseClassType(This.Designator, CovariantPathLength); 4744 const CXXMethodDecl *Next = 4745 Found->getCorrespondingMethodDeclaredInClass(NextClass, false); 4746 if (Next && !Info.Ctx.hasSameUnqualifiedType( 4747 Next->getReturnType(), CovariantAdjustmentPath.back())) 4748 CovariantAdjustmentPath.push_back(Next->getReturnType()); 4749 } 4750 if (!Info.Ctx.hasSameUnqualifiedType(Found->getReturnType(), 4751 CovariantAdjustmentPath.back())) 4752 CovariantAdjustmentPath.push_back(Found->getReturnType()); 4753 } 4754 4755 // Perform 'this' adjustment. 4756 if (!CastToDerivedClass(Info, E, This, Callee->getParent(), PathLength)) 4757 return nullptr; 4758 4759 return Callee; 4760 } 4761 4762 /// Perform the adjustment from a value returned by a virtual function to 4763 /// a value of the statically expected type, which may be a pointer or 4764 /// reference to a base class of the returned type. 4765 static bool HandleCovariantReturnAdjustment(EvalInfo &Info, const Expr *E, 4766 APValue &Result, 4767 ArrayRef<QualType> Path) { 4768 assert(Result.isLValue() && 4769 "unexpected kind of APValue for covariant return"); 4770 if (Result.isNullPointer()) 4771 return true; 4772 4773 LValue LVal; 4774 LVal.setFrom(Info.Ctx, Result); 4775 4776 const CXXRecordDecl *OldClass = Path[0]->getPointeeCXXRecordDecl(); 4777 for (unsigned I = 1; I != Path.size(); ++I) { 4778 const CXXRecordDecl *NewClass = Path[I]->getPointeeCXXRecordDecl(); 4779 assert(OldClass && NewClass && "unexpected kind of covariant return"); 4780 if (OldClass != NewClass && 4781 !CastToBaseClass(Info, E, LVal, OldClass, NewClass)) 4782 return false; 4783 OldClass = NewClass; 4784 } 4785 4786 LVal.moveInto(Result); 4787 return true; 4788 } 4789 4790 /// Determine whether \p Base, which is known to be a direct base class of 4791 /// \p Derived, is a public base class. 4792 static bool isBaseClassPublic(const CXXRecordDecl *Derived, 4793 const CXXRecordDecl *Base) { 4794 for (const CXXBaseSpecifier &BaseSpec : Derived->bases()) { 4795 auto *BaseClass = BaseSpec.getType()->getAsCXXRecordDecl(); 4796 if (BaseClass && declaresSameEntity(BaseClass, Base)) 4797 return BaseSpec.getAccessSpecifier() == AS_public; 4798 } 4799 llvm_unreachable("Base is not a direct base of Derived"); 4800 } 4801 4802 /// Apply the given dynamic cast operation on the provided lvalue. 4803 /// 4804 /// This implements the hard case of dynamic_cast, requiring a "runtime check" 4805 /// to find a suitable target subobject. 4806 static bool HandleDynamicCast(EvalInfo &Info, const ExplicitCastExpr *E, 4807 LValue &Ptr) { 4808 // We can't do anything with a non-symbolic pointer value. 4809 SubobjectDesignator &D = Ptr.Designator; 4810 if (D.Invalid) 4811 return false; 4812 4813 // C++ [expr.dynamic.cast]p6: 4814 // If v is a null pointer value, the result is a null pointer value. 4815 if (Ptr.isNullPointer() && !E->isGLValue()) 4816 return true; 4817 4818 // For all the other cases, we need the pointer to point to an object within 4819 // its lifetime / period of construction / destruction, and we need to know 4820 // its dynamic type. 4821 Optional<DynamicType> DynType = 4822 ComputeDynamicType(Info, E, Ptr, AK_DynamicCast); 4823 if (!DynType) 4824 return false; 4825 4826 // C++ [expr.dynamic.cast]p7: 4827 // If T is "pointer to cv void", then the result is a pointer to the most 4828 // derived object 4829 if (E->getType()->isVoidPointerType()) 4830 return CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength); 4831 4832 const CXXRecordDecl *C = E->getTypeAsWritten()->getPointeeCXXRecordDecl(); 4833 assert(C && "dynamic_cast target is not void pointer nor class"); 4834 CanQualType CQT = Info.Ctx.getCanonicalType(Info.Ctx.getRecordType(C)); 4835 4836 auto RuntimeCheckFailed = [&] (CXXBasePaths *Paths) { 4837 // C++ [expr.dynamic.cast]p9: 4838 if (!E->isGLValue()) { 4839 // The value of a failed cast to pointer type is the null pointer value 4840 // of the required result type. 4841 auto TargetVal = Info.Ctx.getTargetNullPointerValue(E->getType()); 4842 Ptr.setNull(E->getType(), TargetVal); 4843 return true; 4844 } 4845 4846 // A failed cast to reference type throws [...] std::bad_cast. 4847 unsigned DiagKind; 4848 if (!Paths && (declaresSameEntity(DynType->Type, C) || 4849 DynType->Type->isDerivedFrom(C))) 4850 DiagKind = 0; 4851 else if (!Paths || Paths->begin() == Paths->end()) 4852 DiagKind = 1; 4853 else if (Paths->isAmbiguous(CQT)) 4854 DiagKind = 2; 4855 else { 4856 assert(Paths->front().Access != AS_public && "why did the cast fail?"); 4857 DiagKind = 3; 4858 } 4859 Info.FFDiag(E, diag::note_constexpr_dynamic_cast_to_reference_failed) 4860 << DiagKind << Ptr.Designator.getType(Info.Ctx) 4861 << Info.Ctx.getRecordType(DynType->Type) 4862 << E->getType().getUnqualifiedType(); 4863 return false; 4864 }; 4865 4866 // Runtime check, phase 1: 4867 // Walk from the base subobject towards the derived object looking for the 4868 // target type. 4869 for (int PathLength = Ptr.Designator.Entries.size(); 4870 PathLength >= (int)DynType->PathLength; --PathLength) { 4871 const CXXRecordDecl *Class = getBaseClassType(Ptr.Designator, PathLength); 4872 if (declaresSameEntity(Class, C)) 4873 return CastToDerivedClass(Info, E, Ptr, Class, PathLength); 4874 // We can only walk across public inheritance edges. 4875 if (PathLength > (int)DynType->PathLength && 4876 !isBaseClassPublic(getBaseClassType(Ptr.Designator, PathLength - 1), 4877 Class)) 4878 return RuntimeCheckFailed(nullptr); 4879 } 4880 4881 // Runtime check, phase 2: 4882 // Search the dynamic type for an unambiguous public base of type C. 4883 CXXBasePaths Paths(/*FindAmbiguities=*/true, 4884 /*RecordPaths=*/true, /*DetectVirtual=*/false); 4885 if (DynType->Type->isDerivedFrom(C, Paths) && !Paths.isAmbiguous(CQT) && 4886 Paths.front().Access == AS_public) { 4887 // Downcast to the dynamic type... 4888 if (!CastToDerivedClass(Info, E, Ptr, DynType->Type, DynType->PathLength)) 4889 return false; 4890 // ... then upcast to the chosen base class subobject. 4891 for (CXXBasePathElement &Elem : Paths.front()) 4892 if (!HandleLValueBase(Info, E, Ptr, Elem.Class, Elem.Base)) 4893 return false; 4894 return true; 4895 } 4896 4897 // Otherwise, the runtime check fails. 4898 return RuntimeCheckFailed(&Paths); 4899 } 4900 4901 namespace { 4902 struct StartLifetimeOfUnionMemberHandler { 4903 const FieldDecl *Field; 4904 4905 static const AccessKinds AccessKind = AK_Assign; 4906 4907 APValue getDefaultInitValue(QualType SubobjType) { 4908 if (auto *RD = SubobjType->getAsCXXRecordDecl()) { 4909 if (RD->isUnion()) 4910 return APValue((const FieldDecl*)nullptr); 4911 4912 APValue Struct(APValue::UninitStruct(), RD->getNumBases(), 4913 std::distance(RD->field_begin(), RD->field_end())); 4914 4915 unsigned Index = 0; 4916 for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), 4917 End = RD->bases_end(); I != End; ++I, ++Index) 4918 Struct.getStructBase(Index) = getDefaultInitValue(I->getType()); 4919 4920 for (const auto *I : RD->fields()) { 4921 if (I->isUnnamedBitfield()) 4922 continue; 4923 Struct.getStructField(I->getFieldIndex()) = 4924 getDefaultInitValue(I->getType()); 4925 } 4926 return Struct; 4927 } 4928 4929 if (auto *AT = dyn_cast_or_null<ConstantArrayType>( 4930 SubobjType->getAsArrayTypeUnsafe())) { 4931 APValue Array(APValue::UninitArray(), 0, AT->getSize().getZExtValue()); 4932 if (Array.hasArrayFiller()) 4933 Array.getArrayFiller() = getDefaultInitValue(AT->getElementType()); 4934 return Array; 4935 } 4936 4937 return APValue::IndeterminateValue(); 4938 } 4939 4940 typedef bool result_type; 4941 bool failed() { return false; } 4942 bool found(APValue &Subobj, QualType SubobjType) { 4943 // We are supposed to perform no initialization but begin the lifetime of 4944 // the object. We interpret that as meaning to do what default 4945 // initialization of the object would do if all constructors involved were 4946 // trivial: 4947 // * All base, non-variant member, and array element subobjects' lifetimes 4948 // begin 4949 // * No variant members' lifetimes begin 4950 // * All scalar subobjects whose lifetimes begin have indeterminate values 4951 assert(SubobjType->isUnionType()); 4952 if (!declaresSameEntity(Subobj.getUnionField(), Field)) 4953 Subobj.setUnion(Field, getDefaultInitValue(Field->getType())); 4954 return true; 4955 } 4956 bool found(APSInt &Value, QualType SubobjType) { 4957 llvm_unreachable("wrong value kind for union object"); 4958 } 4959 bool found(APFloat &Value, QualType SubobjType) { 4960 llvm_unreachable("wrong value kind for union object"); 4961 } 4962 }; 4963 } // end anonymous namespace 4964 4965 const AccessKinds StartLifetimeOfUnionMemberHandler::AccessKind; 4966 4967 /// Handle a builtin simple-assignment or a call to a trivial assignment 4968 /// operator whose left-hand side might involve a union member access. If it 4969 /// does, implicitly start the lifetime of any accessed union elements per 4970 /// C++20 [class.union]5. 4971 static bool HandleUnionActiveMemberChange(EvalInfo &Info, const Expr *LHSExpr, 4972 const LValue &LHS) { 4973 if (LHS.InvalidBase || LHS.Designator.Invalid) 4974 return false; 4975 4976 llvm::SmallVector<std::pair<unsigned, const FieldDecl*>, 4> UnionPathLengths; 4977 // C++ [class.union]p5: 4978 // define the set S(E) of subexpressions of E as follows: 4979 unsigned PathLength = LHS.Designator.Entries.size(); 4980 for (const Expr *E = LHSExpr; E != nullptr;) { 4981 // -- If E is of the form A.B, S(E) contains the elements of S(A)... 4982 if (auto *ME = dyn_cast<MemberExpr>(E)) { 4983 auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl()); 4984 if (!FD) 4985 break; 4986 4987 // ... and also contains A.B if B names a union member 4988 if (FD->getParent()->isUnion()) 4989 UnionPathLengths.push_back({PathLength - 1, FD}); 4990 4991 E = ME->getBase(); 4992 --PathLength; 4993 assert(declaresSameEntity(FD, 4994 LHS.Designator.Entries[PathLength] 4995 .getAsBaseOrMember().getPointer())); 4996 4997 // -- If E is of the form A[B] and is interpreted as a built-in array 4998 // subscripting operator, S(E) is [S(the array operand, if any)]. 4999 } else if (auto *ASE = dyn_cast<ArraySubscriptExpr>(E)) { 5000 // Step over an ArrayToPointerDecay implicit cast. 5001 auto *Base = ASE->getBase()->IgnoreImplicit(); 5002 if (!Base->getType()->isArrayType()) 5003 break; 5004 5005 E = Base; 5006 --PathLength; 5007 5008 } else if (auto *ICE = dyn_cast<ImplicitCastExpr>(E)) { 5009 // Step over a derived-to-base conversion. 5010 E = ICE->getSubExpr(); 5011 if (ICE->getCastKind() == CK_NoOp) 5012 continue; 5013 if (ICE->getCastKind() != CK_DerivedToBase && 5014 ICE->getCastKind() != CK_UncheckedDerivedToBase) 5015 break; 5016 // Walk path backwards as we walk up from the base to the derived class. 5017 for (const CXXBaseSpecifier *Elt : llvm::reverse(ICE->path())) { 5018 --PathLength; 5019 (void)Elt; 5020 assert(declaresSameEntity(Elt->getType()->getAsCXXRecordDecl(), 5021 LHS.Designator.Entries[PathLength] 5022 .getAsBaseOrMember().getPointer())); 5023 } 5024 5025 // -- Otherwise, S(E) is empty. 5026 } else { 5027 break; 5028 } 5029 } 5030 5031 // Common case: no unions' lifetimes are started. 5032 if (UnionPathLengths.empty()) 5033 return true; 5034 5035 // if modification of X [would access an inactive union member], an object 5036 // of the type of X is implicitly created 5037 CompleteObject Obj = 5038 findCompleteObject(Info, LHSExpr, AK_Assign, LHS, LHSExpr->getType()); 5039 if (!Obj) 5040 return false; 5041 for (std::pair<unsigned, const FieldDecl *> LengthAndField : 5042 llvm::reverse(UnionPathLengths)) { 5043 // Form a designator for the union object. 5044 SubobjectDesignator D = LHS.Designator; 5045 D.truncate(Info.Ctx, LHS.Base, LengthAndField.first); 5046 5047 StartLifetimeOfUnionMemberHandler StartLifetime{LengthAndField.second}; 5048 if (!findSubobject(Info, LHSExpr, Obj, D, StartLifetime)) 5049 return false; 5050 } 5051 5052 return true; 5053 } 5054 5055 /// Determine if a class has any fields that might need to be copied by a 5056 /// trivial copy or move operation. 5057 static bool hasFields(const CXXRecordDecl *RD) { 5058 if (!RD || RD->isEmpty()) 5059 return false; 5060 for (auto *FD : RD->fields()) { 5061 if (FD->isUnnamedBitfield()) 5062 continue; 5063 return true; 5064 } 5065 for (auto &Base : RD->bases()) 5066 if (hasFields(Base.getType()->getAsCXXRecordDecl())) 5067 return true; 5068 return false; 5069 } 5070 5071 namespace { 5072 typedef SmallVector<APValue, 8> ArgVector; 5073 } 5074 5075 /// EvaluateArgs - Evaluate the arguments to a function call. 5076 static bool EvaluateArgs(ArrayRef<const Expr *> Args, ArgVector &ArgValues, 5077 EvalInfo &Info, const FunctionDecl *Callee) { 5078 bool Success = true; 5079 llvm::SmallBitVector ForbiddenNullArgs; 5080 if (Callee->hasAttr<NonNullAttr>()) { 5081 ForbiddenNullArgs.resize(Args.size()); 5082 for (const auto *Attr : Callee->specific_attrs<NonNullAttr>()) { 5083 if (!Attr->args_size()) { 5084 ForbiddenNullArgs.set(); 5085 break; 5086 } else 5087 for (auto Idx : Attr->args()) { 5088 unsigned ASTIdx = Idx.getASTIndex(); 5089 if (ASTIdx >= Args.size()) 5090 continue; 5091 ForbiddenNullArgs[ASTIdx] = 1; 5092 } 5093 } 5094 } 5095 for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end(); 5096 I != E; ++I) { 5097 if (!Evaluate(ArgValues[I - Args.begin()], Info, *I)) { 5098 // If we're checking for a potential constant expression, evaluate all 5099 // initializers even if some of them fail. 5100 if (!Info.noteFailure()) 5101 return false; 5102 Success = false; 5103 } else if (!ForbiddenNullArgs.empty() && 5104 ForbiddenNullArgs[I - Args.begin()] && 5105 ArgValues[I - Args.begin()].isNullPointer()) { 5106 Info.CCEDiag(*I, diag::note_non_null_attribute_failed); 5107 if (!Info.noteFailure()) 5108 return false; 5109 Success = false; 5110 } 5111 } 5112 return Success; 5113 } 5114 5115 /// Evaluate a function call. 5116 static bool HandleFunctionCall(SourceLocation CallLoc, 5117 const FunctionDecl *Callee, const LValue *This, 5118 ArrayRef<const Expr*> Args, const Stmt *Body, 5119 EvalInfo &Info, APValue &Result, 5120 const LValue *ResultSlot) { 5121 ArgVector ArgValues(Args.size()); 5122 if (!EvaluateArgs(Args, ArgValues, Info, Callee)) 5123 return false; 5124 5125 if (!Info.CheckCallLimit(CallLoc)) 5126 return false; 5127 5128 CallStackFrame Frame(Info, CallLoc, Callee, This, ArgValues.data()); 5129 5130 // For a trivial copy or move assignment, perform an APValue copy. This is 5131 // essential for unions, where the operations performed by the assignment 5132 // operator cannot be represented as statements. 5133 // 5134 // Skip this for non-union classes with no fields; in that case, the defaulted 5135 // copy/move does not actually read the object. 5136 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(Callee); 5137 if (MD && MD->isDefaulted() && 5138 (MD->getParent()->isUnion() || 5139 (MD->isTrivial() && hasFields(MD->getParent())))) { 5140 assert(This && 5141 (MD->isCopyAssignmentOperator() || MD->isMoveAssignmentOperator())); 5142 LValue RHS; 5143 RHS.setFrom(Info.Ctx, ArgValues[0]); 5144 APValue RHSValue; 5145 if (!handleLValueToRValueConversion(Info, Args[0], Args[0]->getType(), 5146 RHS, RHSValue)) 5147 return false; 5148 if (Info.getLangOpts().CPlusPlus2a && MD->isTrivial() && 5149 !HandleUnionActiveMemberChange(Info, Args[0], *This)) 5150 return false; 5151 if (!handleAssignment(Info, Args[0], *This, MD->getThisType(), 5152 RHSValue)) 5153 return false; 5154 This->moveInto(Result); 5155 return true; 5156 } else if (MD && isLambdaCallOperator(MD)) { 5157 // We're in a lambda; determine the lambda capture field maps unless we're 5158 // just constexpr checking a lambda's call operator. constexpr checking is 5159 // done before the captures have been added to the closure object (unless 5160 // we're inferring constexpr-ness), so we don't have access to them in this 5161 // case. But since we don't need the captures to constexpr check, we can 5162 // just ignore them. 5163 if (!Info.checkingPotentialConstantExpression()) 5164 MD->getParent()->getCaptureFields(Frame.LambdaCaptureFields, 5165 Frame.LambdaThisCaptureField); 5166 } 5167 5168 StmtResult Ret = {Result, ResultSlot}; 5169 EvalStmtResult ESR = EvaluateStmt(Ret, Info, Body); 5170 if (ESR == ESR_Succeeded) { 5171 if (Callee->getReturnType()->isVoidType()) 5172 return true; 5173 Info.FFDiag(Callee->getEndLoc(), diag::note_constexpr_no_return); 5174 } 5175 return ESR == ESR_Returned; 5176 } 5177 5178 /// Evaluate a constructor call. 5179 static bool HandleConstructorCall(const Expr *E, const LValue &This, 5180 APValue *ArgValues, 5181 const CXXConstructorDecl *Definition, 5182 EvalInfo &Info, APValue &Result) { 5183 SourceLocation CallLoc = E->getExprLoc(); 5184 if (!Info.CheckCallLimit(CallLoc)) 5185 return false; 5186 5187 const CXXRecordDecl *RD = Definition->getParent(); 5188 if (RD->getNumVBases()) { 5189 Info.FFDiag(CallLoc, diag::note_constexpr_virtual_base) << RD; 5190 return false; 5191 } 5192 5193 EvalInfo::EvaluatingConstructorRAII EvalObj( 5194 Info, 5195 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries}, 5196 RD->getNumBases()); 5197 CallStackFrame Frame(Info, CallLoc, Definition, &This, ArgValues); 5198 5199 // FIXME: Creating an APValue just to hold a nonexistent return value is 5200 // wasteful. 5201 APValue RetVal; 5202 StmtResult Ret = {RetVal, nullptr}; 5203 5204 // If it's a delegating constructor, delegate. 5205 if (Definition->isDelegatingConstructor()) { 5206 CXXConstructorDecl::init_const_iterator I = Definition->init_begin(); 5207 { 5208 FullExpressionRAII InitScope(Info); 5209 if (!EvaluateInPlace(Result, Info, This, (*I)->getInit())) 5210 return false; 5211 } 5212 return EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed; 5213 } 5214 5215 // For a trivial copy or move constructor, perform an APValue copy. This is 5216 // essential for unions (or classes with anonymous union members), where the 5217 // operations performed by the constructor cannot be represented by 5218 // ctor-initializers. 5219 // 5220 // Skip this for empty non-union classes; we should not perform an 5221 // lvalue-to-rvalue conversion on them because their copy constructor does not 5222 // actually read them. 5223 if (Definition->isDefaulted() && Definition->isCopyOrMoveConstructor() && 5224 (Definition->getParent()->isUnion() || 5225 (Definition->isTrivial() && hasFields(Definition->getParent())))) { 5226 LValue RHS; 5227 RHS.setFrom(Info.Ctx, ArgValues[0]); 5228 return handleLValueToRValueConversion( 5229 Info, E, Definition->getParamDecl(0)->getType().getNonReferenceType(), 5230 RHS, Result); 5231 } 5232 5233 // Reserve space for the struct members. 5234 if (!RD->isUnion() && !Result.hasValue()) 5235 Result = APValue(APValue::UninitStruct(), RD->getNumBases(), 5236 std::distance(RD->field_begin(), RD->field_end())); 5237 5238 if (RD->isInvalidDecl()) return false; 5239 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 5240 5241 // A scope for temporaries lifetime-extended by reference members. 5242 BlockScopeRAII LifetimeExtendedScope(Info); 5243 5244 bool Success = true; 5245 unsigned BasesSeen = 0; 5246 #ifndef NDEBUG 5247 CXXRecordDecl::base_class_const_iterator BaseIt = RD->bases_begin(); 5248 #endif 5249 for (const auto *I : Definition->inits()) { 5250 LValue Subobject = This; 5251 LValue SubobjectParent = This; 5252 APValue *Value = &Result; 5253 5254 // Determine the subobject to initialize. 5255 FieldDecl *FD = nullptr; 5256 if (I->isBaseInitializer()) { 5257 QualType BaseType(I->getBaseClass(), 0); 5258 #ifndef NDEBUG 5259 // Non-virtual base classes are initialized in the order in the class 5260 // definition. We have already checked for virtual base classes. 5261 assert(!BaseIt->isVirtual() && "virtual base for literal type"); 5262 assert(Info.Ctx.hasSameType(BaseIt->getType(), BaseType) && 5263 "base class initializers not in expected order"); 5264 ++BaseIt; 5265 #endif 5266 if (!HandleLValueDirectBase(Info, I->getInit(), Subobject, RD, 5267 BaseType->getAsCXXRecordDecl(), &Layout)) 5268 return false; 5269 Value = &Result.getStructBase(BasesSeen++); 5270 } else if ((FD = I->getMember())) { 5271 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD, &Layout)) 5272 return false; 5273 if (RD->isUnion()) { 5274 Result = APValue(FD); 5275 Value = &Result.getUnionValue(); 5276 } else { 5277 Value = &Result.getStructField(FD->getFieldIndex()); 5278 } 5279 } else if (IndirectFieldDecl *IFD = I->getIndirectMember()) { 5280 // Walk the indirect field decl's chain to find the object to initialize, 5281 // and make sure we've initialized every step along it. 5282 auto IndirectFieldChain = IFD->chain(); 5283 for (auto *C : IndirectFieldChain) { 5284 FD = cast<FieldDecl>(C); 5285 CXXRecordDecl *CD = cast<CXXRecordDecl>(FD->getParent()); 5286 // Switch the union field if it differs. This happens if we had 5287 // preceding zero-initialization, and we're now initializing a union 5288 // subobject other than the first. 5289 // FIXME: In this case, the values of the other subobjects are 5290 // specified, since zero-initialization sets all padding bits to zero. 5291 if (!Value->hasValue() || 5292 (Value->isUnion() && Value->getUnionField() != FD)) { 5293 if (CD->isUnion()) 5294 *Value = APValue(FD); 5295 else 5296 *Value = APValue(APValue::UninitStruct(), CD->getNumBases(), 5297 std::distance(CD->field_begin(), CD->field_end())); 5298 } 5299 // Store Subobject as its parent before updating it for the last element 5300 // in the chain. 5301 if (C == IndirectFieldChain.back()) 5302 SubobjectParent = Subobject; 5303 if (!HandleLValueMember(Info, I->getInit(), Subobject, FD)) 5304 return false; 5305 if (CD->isUnion()) 5306 Value = &Value->getUnionValue(); 5307 else 5308 Value = &Value->getStructField(FD->getFieldIndex()); 5309 } 5310 } else { 5311 llvm_unreachable("unknown base initializer kind"); 5312 } 5313 5314 // Need to override This for implicit field initializers as in this case 5315 // This refers to innermost anonymous struct/union containing initializer, 5316 // not to currently constructed class. 5317 const Expr *Init = I->getInit(); 5318 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &SubobjectParent, 5319 isa<CXXDefaultInitExpr>(Init)); 5320 FullExpressionRAII InitScope(Info); 5321 if (!EvaluateInPlace(*Value, Info, Subobject, Init) || 5322 (FD && FD->isBitField() && 5323 !truncateBitfieldValue(Info, Init, *Value, FD))) { 5324 // If we're checking for a potential constant expression, evaluate all 5325 // initializers even if some of them fail. 5326 if (!Info.noteFailure()) 5327 return false; 5328 Success = false; 5329 } 5330 5331 // This is the point at which the dynamic type of the object becomes this 5332 // class type. 5333 if (I->isBaseInitializer() && BasesSeen == RD->getNumBases()) 5334 EvalObj.finishedConstructingBases(); 5335 } 5336 5337 return Success && 5338 EvaluateStmt(Ret, Info, Definition->getBody()) != ESR_Failed; 5339 } 5340 5341 static bool HandleConstructorCall(const Expr *E, const LValue &This, 5342 ArrayRef<const Expr*> Args, 5343 const CXXConstructorDecl *Definition, 5344 EvalInfo &Info, APValue &Result) { 5345 ArgVector ArgValues(Args.size()); 5346 if (!EvaluateArgs(Args, ArgValues, Info, Definition)) 5347 return false; 5348 5349 return HandleConstructorCall(E, This, ArgValues.data(), Definition, 5350 Info, Result); 5351 } 5352 5353 //===----------------------------------------------------------------------===// 5354 // Generic Evaluation 5355 //===----------------------------------------------------------------------===// 5356 namespace { 5357 5358 class BitCastBuffer { 5359 // FIXME: We're going to need bit-level granularity when we support 5360 // bit-fields. 5361 // FIXME: Its possible under the C++ standard for 'char' to not be 8 bits, but 5362 // we don't support a host or target where that is the case. Still, we should 5363 // use a more generic type in case we ever do. 5364 SmallVector<Optional<unsigned char>, 32> Bytes; 5365 5366 static_assert(std::numeric_limits<unsigned char>::digits >= 8, 5367 "Need at least 8 bit unsigned char"); 5368 5369 bool TargetIsLittleEndian; 5370 5371 public: 5372 BitCastBuffer(CharUnits Width, bool TargetIsLittleEndian) 5373 : Bytes(Width.getQuantity()), 5374 TargetIsLittleEndian(TargetIsLittleEndian) {} 5375 5376 LLVM_NODISCARD 5377 bool readObject(CharUnits Offset, CharUnits Width, 5378 SmallVectorImpl<unsigned char> &Output) const { 5379 for (CharUnits I = Offset, E = Offset + Width; I != E; ++I) { 5380 // If a byte of an integer is uninitialized, then the whole integer is 5381 // uninitalized. 5382 if (!Bytes[I.getQuantity()]) 5383 return false; 5384 Output.push_back(*Bytes[I.getQuantity()]); 5385 } 5386 if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian) 5387 std::reverse(Output.begin(), Output.end()); 5388 return true; 5389 } 5390 5391 void writeObject(CharUnits Offset, SmallVectorImpl<unsigned char> &Input) { 5392 if (llvm::sys::IsLittleEndianHost != TargetIsLittleEndian) 5393 std::reverse(Input.begin(), Input.end()); 5394 5395 size_t Index = 0; 5396 for (unsigned char Byte : Input) { 5397 assert(!Bytes[Offset.getQuantity() + Index] && "overwriting a byte?"); 5398 Bytes[Offset.getQuantity() + Index] = Byte; 5399 ++Index; 5400 } 5401 } 5402 5403 size_t size() { return Bytes.size(); } 5404 }; 5405 5406 /// Traverse an APValue to produce an BitCastBuffer, emulating how the current 5407 /// target would represent the value at runtime. 5408 class APValueToBufferConverter { 5409 EvalInfo &Info; 5410 BitCastBuffer Buffer; 5411 const CastExpr *BCE; 5412 5413 APValueToBufferConverter(EvalInfo &Info, CharUnits ObjectWidth, 5414 const CastExpr *BCE) 5415 : Info(Info), 5416 Buffer(ObjectWidth, Info.Ctx.getTargetInfo().isLittleEndian()), 5417 BCE(BCE) {} 5418 5419 bool visit(const APValue &Val, QualType Ty) { 5420 return visit(Val, Ty, CharUnits::fromQuantity(0)); 5421 } 5422 5423 // Write out Val with type Ty into Buffer starting at Offset. 5424 bool visit(const APValue &Val, QualType Ty, CharUnits Offset) { 5425 assert((size_t)Offset.getQuantity() <= Buffer.size()); 5426 5427 // As a special case, nullptr_t has an indeterminate value. 5428 if (Ty->isNullPtrType()) 5429 return true; 5430 5431 // Dig through Src to find the byte at SrcOffset. 5432 switch (Val.getKind()) { 5433 case APValue::Indeterminate: 5434 case APValue::None: 5435 return true; 5436 5437 case APValue::Int: 5438 return visitInt(Val.getInt(), Ty, Offset); 5439 case APValue::Float: 5440 return visitFloat(Val.getFloat(), Ty, Offset); 5441 case APValue::Array: 5442 return visitArray(Val, Ty, Offset); 5443 case APValue::Struct: 5444 return visitRecord(Val, Ty, Offset); 5445 5446 case APValue::ComplexInt: 5447 case APValue::ComplexFloat: 5448 case APValue::Vector: 5449 case APValue::FixedPoint: 5450 // FIXME: We should support these. 5451 5452 case APValue::Union: 5453 case APValue::MemberPointer: 5454 case APValue::AddrLabelDiff: { 5455 Info.FFDiag(BCE->getBeginLoc(), 5456 diag::note_constexpr_bit_cast_unsupported_type) 5457 << Ty; 5458 return false; 5459 } 5460 5461 case APValue::LValue: 5462 llvm_unreachable("LValue subobject in bit_cast?"); 5463 } 5464 llvm_unreachable("Unhandled APValue::ValueKind"); 5465 } 5466 5467 bool visitRecord(const APValue &Val, QualType Ty, CharUnits Offset) { 5468 const RecordDecl *RD = Ty->getAsRecordDecl(); 5469 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 5470 5471 // Visit the base classes. 5472 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) { 5473 for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) { 5474 const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I]; 5475 CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl(); 5476 5477 if (!visitRecord(Val.getStructBase(I), BS.getType(), 5478 Layout.getBaseClassOffset(BaseDecl) + Offset)) 5479 return false; 5480 } 5481 } 5482 5483 // Visit the fields. 5484 unsigned FieldIdx = 0; 5485 for (FieldDecl *FD : RD->fields()) { 5486 if (FD->isBitField()) { 5487 Info.FFDiag(BCE->getBeginLoc(), 5488 diag::note_constexpr_bit_cast_unsupported_bitfield); 5489 return false; 5490 } 5491 5492 uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx); 5493 5494 assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0 && 5495 "only bit-fields can have sub-char alignment"); 5496 CharUnits FieldOffset = 5497 Info.Ctx.toCharUnitsFromBits(FieldOffsetBits) + Offset; 5498 QualType FieldTy = FD->getType(); 5499 if (!visit(Val.getStructField(FieldIdx), FieldTy, FieldOffset)) 5500 return false; 5501 ++FieldIdx; 5502 } 5503 5504 return true; 5505 } 5506 5507 bool visitArray(const APValue &Val, QualType Ty, CharUnits Offset) { 5508 const auto *CAT = 5509 dyn_cast_or_null<ConstantArrayType>(Ty->getAsArrayTypeUnsafe()); 5510 if (!CAT) 5511 return false; 5512 5513 CharUnits ElemWidth = Info.Ctx.getTypeSizeInChars(CAT->getElementType()); 5514 unsigned NumInitializedElts = Val.getArrayInitializedElts(); 5515 unsigned ArraySize = Val.getArraySize(); 5516 // First, initialize the initialized elements. 5517 for (unsigned I = 0; I != NumInitializedElts; ++I) { 5518 const APValue &SubObj = Val.getArrayInitializedElt(I); 5519 if (!visit(SubObj, CAT->getElementType(), Offset + I * ElemWidth)) 5520 return false; 5521 } 5522 5523 // Next, initialize the rest of the array using the filler. 5524 if (Val.hasArrayFiller()) { 5525 const APValue &Filler = Val.getArrayFiller(); 5526 for (unsigned I = NumInitializedElts; I != ArraySize; ++I) { 5527 if (!visit(Filler, CAT->getElementType(), Offset + I * ElemWidth)) 5528 return false; 5529 } 5530 } 5531 5532 return true; 5533 } 5534 5535 bool visitInt(const APSInt &Val, QualType Ty, CharUnits Offset) { 5536 CharUnits Width = Info.Ctx.getTypeSizeInChars(Ty); 5537 SmallVector<unsigned char, 8> Bytes(Width.getQuantity()); 5538 llvm::StoreIntToMemory(Val, &*Bytes.begin(), Width.getQuantity()); 5539 Buffer.writeObject(Offset, Bytes); 5540 return true; 5541 } 5542 5543 bool visitFloat(const APFloat &Val, QualType Ty, CharUnits Offset) { 5544 APSInt AsInt(Val.bitcastToAPInt()); 5545 return visitInt(AsInt, Ty, Offset); 5546 } 5547 5548 public: 5549 static Optional<BitCastBuffer> convert(EvalInfo &Info, const APValue &Src, 5550 const CastExpr *BCE) { 5551 CharUnits DstSize = Info.Ctx.getTypeSizeInChars(BCE->getType()); 5552 APValueToBufferConverter Converter(Info, DstSize, BCE); 5553 if (!Converter.visit(Src, BCE->getSubExpr()->getType())) 5554 return None; 5555 return Converter.Buffer; 5556 } 5557 }; 5558 5559 /// Write an BitCastBuffer into an APValue. 5560 class BufferToAPValueConverter { 5561 EvalInfo &Info; 5562 const BitCastBuffer &Buffer; 5563 const CastExpr *BCE; 5564 5565 BufferToAPValueConverter(EvalInfo &Info, const BitCastBuffer &Buffer, 5566 const CastExpr *BCE) 5567 : Info(Info), Buffer(Buffer), BCE(BCE) {} 5568 5569 // Emit an unsupported bit_cast type error. Sema refuses to build a bit_cast 5570 // with an invalid type, so anything left is a deficiency on our part (FIXME). 5571 // Ideally this will be unreachable. 5572 llvm::NoneType unsupportedType(QualType Ty) { 5573 Info.FFDiag(BCE->getBeginLoc(), 5574 diag::note_constexpr_bit_cast_unsupported_type) 5575 << Ty; 5576 return None; 5577 } 5578 5579 Optional<APValue> visit(const BuiltinType *T, CharUnits Offset, 5580 const EnumType *EnumSugar = nullptr) { 5581 if (T->isNullPtrType()) { 5582 uint64_t NullValue = Info.Ctx.getTargetNullPointerValue(QualType(T, 0)); 5583 return APValue((Expr *)nullptr, 5584 /*Offset=*/CharUnits::fromQuantity(NullValue), 5585 APValue::NoLValuePath{}, /*IsNullPtr=*/true); 5586 } 5587 5588 CharUnits SizeOf = Info.Ctx.getTypeSizeInChars(T); 5589 SmallVector<uint8_t, 8> Bytes; 5590 if (!Buffer.readObject(Offset, SizeOf, Bytes)) { 5591 // If this is std::byte or unsigned char, then its okay to store an 5592 // indeterminate value. 5593 bool IsStdByte = EnumSugar && EnumSugar->isStdByteType(); 5594 bool IsUChar = 5595 !EnumSugar && (T->isSpecificBuiltinType(BuiltinType::UChar) || 5596 T->isSpecificBuiltinType(BuiltinType::Char_U)); 5597 if (!IsStdByte && !IsUChar) { 5598 QualType DisplayType(EnumSugar ? (const Type *)EnumSugar : T, 0); 5599 Info.FFDiag(BCE->getExprLoc(), 5600 diag::note_constexpr_bit_cast_indet_dest) 5601 << DisplayType << Info.Ctx.getLangOpts().CharIsSigned; 5602 return None; 5603 } 5604 5605 return APValue::IndeterminateValue(); 5606 } 5607 5608 APSInt Val(SizeOf.getQuantity() * Info.Ctx.getCharWidth(), true); 5609 llvm::LoadIntFromMemory(Val, &*Bytes.begin(), Bytes.size()); 5610 5611 if (T->isIntegralOrEnumerationType()) { 5612 Val.setIsSigned(T->isSignedIntegerOrEnumerationType()); 5613 return APValue(Val); 5614 } 5615 5616 if (T->isRealFloatingType()) { 5617 const llvm::fltSemantics &Semantics = 5618 Info.Ctx.getFloatTypeSemantics(QualType(T, 0)); 5619 return APValue(APFloat(Semantics, Val)); 5620 } 5621 5622 return unsupportedType(QualType(T, 0)); 5623 } 5624 5625 Optional<APValue> visit(const RecordType *RTy, CharUnits Offset) { 5626 const RecordDecl *RD = RTy->getAsRecordDecl(); 5627 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 5628 5629 unsigned NumBases = 0; 5630 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) 5631 NumBases = CXXRD->getNumBases(); 5632 5633 APValue ResultVal(APValue::UninitStruct(), NumBases, 5634 std::distance(RD->field_begin(), RD->field_end())); 5635 5636 // Visit the base classes. 5637 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) { 5638 for (size_t I = 0, E = CXXRD->getNumBases(); I != E; ++I) { 5639 const CXXBaseSpecifier &BS = CXXRD->bases_begin()[I]; 5640 CXXRecordDecl *BaseDecl = BS.getType()->getAsCXXRecordDecl(); 5641 if (BaseDecl->isEmpty() || 5642 Info.Ctx.getASTRecordLayout(BaseDecl).getNonVirtualSize().isZero()) 5643 continue; 5644 5645 Optional<APValue> SubObj = visitType( 5646 BS.getType(), Layout.getBaseClassOffset(BaseDecl) + Offset); 5647 if (!SubObj) 5648 return None; 5649 ResultVal.getStructBase(I) = *SubObj; 5650 } 5651 } 5652 5653 // Visit the fields. 5654 unsigned FieldIdx = 0; 5655 for (FieldDecl *FD : RD->fields()) { 5656 // FIXME: We don't currently support bit-fields. A lot of the logic for 5657 // this is in CodeGen, so we need to factor it around. 5658 if (FD->isBitField()) { 5659 Info.FFDiag(BCE->getBeginLoc(), 5660 diag::note_constexpr_bit_cast_unsupported_bitfield); 5661 return None; 5662 } 5663 5664 uint64_t FieldOffsetBits = Layout.getFieldOffset(FieldIdx); 5665 assert(FieldOffsetBits % Info.Ctx.getCharWidth() == 0); 5666 5667 CharUnits FieldOffset = 5668 CharUnits::fromQuantity(FieldOffsetBits / Info.Ctx.getCharWidth()) + 5669 Offset; 5670 QualType FieldTy = FD->getType(); 5671 Optional<APValue> SubObj = visitType(FieldTy, FieldOffset); 5672 if (!SubObj) 5673 return None; 5674 ResultVal.getStructField(FieldIdx) = *SubObj; 5675 ++FieldIdx; 5676 } 5677 5678 return ResultVal; 5679 } 5680 5681 Optional<APValue> visit(const EnumType *Ty, CharUnits Offset) { 5682 QualType RepresentationType = Ty->getDecl()->getIntegerType(); 5683 assert(!RepresentationType.isNull() && 5684 "enum forward decl should be caught by Sema"); 5685 const BuiltinType *AsBuiltin = 5686 RepresentationType.getCanonicalType()->getAs<BuiltinType>(); 5687 assert(AsBuiltin && "non-integral enum underlying type?"); 5688 // Recurse into the underlying type. Treat std::byte transparently as 5689 // unsigned char. 5690 return visit(AsBuiltin, Offset, /*EnumTy=*/Ty); 5691 } 5692 5693 Optional<APValue> visit(const ConstantArrayType *Ty, CharUnits Offset) { 5694 size_t Size = Ty->getSize().getLimitedValue(); 5695 CharUnits ElementWidth = Info.Ctx.getTypeSizeInChars(Ty->getElementType()); 5696 5697 APValue ArrayValue(APValue::UninitArray(), Size, Size); 5698 for (size_t I = 0; I != Size; ++I) { 5699 Optional<APValue> ElementValue = 5700 visitType(Ty->getElementType(), Offset + I * ElementWidth); 5701 if (!ElementValue) 5702 return None; 5703 ArrayValue.getArrayInitializedElt(I) = std::move(*ElementValue); 5704 } 5705 5706 return ArrayValue; 5707 } 5708 5709 Optional<APValue> visit(const Type *Ty, CharUnits Offset) { 5710 return unsupportedType(QualType(Ty, 0)); 5711 } 5712 5713 Optional<APValue> visitType(QualType Ty, CharUnits Offset) { 5714 QualType Can = Ty.getCanonicalType(); 5715 5716 switch (Can->getTypeClass()) { 5717 #define TYPE(Class, Base) \ 5718 case Type::Class: \ 5719 return visit(cast<Class##Type>(Can.getTypePtr()), Offset); 5720 #define ABSTRACT_TYPE(Class, Base) 5721 #define NON_CANONICAL_TYPE(Class, Base) \ 5722 case Type::Class: \ 5723 llvm_unreachable("non-canonical type should be impossible!"); 5724 #define DEPENDENT_TYPE(Class, Base) \ 5725 case Type::Class: \ 5726 llvm_unreachable( \ 5727 "dependent types aren't supported in the constant evaluator!"); 5728 #define NON_CANONICAL_UNLESS_DEPENDENT(Class, Base) \ 5729 case Type::Class: \ 5730 llvm_unreachable("either dependent or not canonical!"); 5731 #include "clang/AST/TypeNodes.def" 5732 } 5733 llvm_unreachable("Unhandled Type::TypeClass"); 5734 } 5735 5736 public: 5737 // Pull out a full value of type DstType. 5738 static Optional<APValue> convert(EvalInfo &Info, BitCastBuffer &Buffer, 5739 const CastExpr *BCE) { 5740 BufferToAPValueConverter Converter(Info, Buffer, BCE); 5741 return Converter.visitType(BCE->getType(), CharUnits::fromQuantity(0)); 5742 } 5743 }; 5744 5745 static bool checkBitCastConstexprEligibilityType(SourceLocation Loc, 5746 QualType Ty, EvalInfo *Info, 5747 const ASTContext &Ctx, 5748 bool CheckingDest) { 5749 Ty = Ty.getCanonicalType(); 5750 5751 auto diag = [&](int Reason) { 5752 if (Info) 5753 Info->FFDiag(Loc, diag::note_constexpr_bit_cast_invalid_type) 5754 << CheckingDest << (Reason == 4) << Reason; 5755 return false; 5756 }; 5757 auto note = [&](int Construct, QualType NoteTy, SourceLocation NoteLoc) { 5758 if (Info) 5759 Info->Note(NoteLoc, diag::note_constexpr_bit_cast_invalid_subtype) 5760 << NoteTy << Construct << Ty; 5761 return false; 5762 }; 5763 5764 if (Ty->isUnionType()) 5765 return diag(0); 5766 if (Ty->isPointerType()) 5767 return diag(1); 5768 if (Ty->isMemberPointerType()) 5769 return diag(2); 5770 if (Ty.isVolatileQualified()) 5771 return diag(3); 5772 5773 if (RecordDecl *Record = Ty->getAsRecordDecl()) { 5774 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(Record)) { 5775 for (CXXBaseSpecifier &BS : CXXRD->bases()) 5776 if (!checkBitCastConstexprEligibilityType(Loc, BS.getType(), Info, Ctx, 5777 CheckingDest)) 5778 return note(1, BS.getType(), BS.getBeginLoc()); 5779 } 5780 for (FieldDecl *FD : Record->fields()) { 5781 if (FD->getType()->isReferenceType()) 5782 return diag(4); 5783 if (!checkBitCastConstexprEligibilityType(Loc, FD->getType(), Info, Ctx, 5784 CheckingDest)) 5785 return note(0, FD->getType(), FD->getBeginLoc()); 5786 } 5787 } 5788 5789 if (Ty->isArrayType() && 5790 !checkBitCastConstexprEligibilityType(Loc, Ctx.getBaseElementType(Ty), 5791 Info, Ctx, CheckingDest)) 5792 return false; 5793 5794 return true; 5795 } 5796 5797 static bool checkBitCastConstexprEligibility(EvalInfo *Info, 5798 const ASTContext &Ctx, 5799 const CastExpr *BCE) { 5800 bool DestOK = checkBitCastConstexprEligibilityType( 5801 BCE->getBeginLoc(), BCE->getType(), Info, Ctx, true); 5802 bool SourceOK = DestOK && checkBitCastConstexprEligibilityType( 5803 BCE->getBeginLoc(), 5804 BCE->getSubExpr()->getType(), Info, Ctx, false); 5805 return SourceOK; 5806 } 5807 5808 static bool handleLValueToRValueBitCast(EvalInfo &Info, APValue &DestValue, 5809 APValue &SourceValue, 5810 const CastExpr *BCE) { 5811 assert(CHAR_BIT == 8 && Info.Ctx.getTargetInfo().getCharWidth() == 8 && 5812 "no host or target supports non 8-bit chars"); 5813 assert(SourceValue.isLValue() && 5814 "LValueToRValueBitcast requires an lvalue operand!"); 5815 5816 if (!checkBitCastConstexprEligibility(&Info, Info.Ctx, BCE)) 5817 return false; 5818 5819 LValue SourceLValue; 5820 APValue SourceRValue; 5821 SourceLValue.setFrom(Info.Ctx, SourceValue); 5822 if (!handleLValueToRValueConversion(Info, BCE, 5823 BCE->getSubExpr()->getType().withConst(), 5824 SourceLValue, SourceRValue)) 5825 return false; 5826 5827 // Read out SourceValue into a char buffer. 5828 Optional<BitCastBuffer> Buffer = 5829 APValueToBufferConverter::convert(Info, SourceRValue, BCE); 5830 if (!Buffer) 5831 return false; 5832 5833 // Write out the buffer into a new APValue. 5834 Optional<APValue> MaybeDestValue = 5835 BufferToAPValueConverter::convert(Info, *Buffer, BCE); 5836 if (!MaybeDestValue) 5837 return false; 5838 5839 DestValue = std::move(*MaybeDestValue); 5840 return true; 5841 } 5842 5843 template <class Derived> 5844 class ExprEvaluatorBase 5845 : public ConstStmtVisitor<Derived, bool> { 5846 private: 5847 Derived &getDerived() { return static_cast<Derived&>(*this); } 5848 bool DerivedSuccess(const APValue &V, const Expr *E) { 5849 return getDerived().Success(V, E); 5850 } 5851 bool DerivedZeroInitialization(const Expr *E) { 5852 return getDerived().ZeroInitialization(E); 5853 } 5854 5855 // Check whether a conditional operator with a non-constant condition is a 5856 // potential constant expression. If neither arm is a potential constant 5857 // expression, then the conditional operator is not either. 5858 template<typename ConditionalOperator> 5859 void CheckPotentialConstantConditional(const ConditionalOperator *E) { 5860 assert(Info.checkingPotentialConstantExpression()); 5861 5862 // Speculatively evaluate both arms. 5863 SmallVector<PartialDiagnosticAt, 8> Diag; 5864 { 5865 SpeculativeEvaluationRAII Speculate(Info, &Diag); 5866 StmtVisitorTy::Visit(E->getFalseExpr()); 5867 if (Diag.empty()) 5868 return; 5869 } 5870 5871 { 5872 SpeculativeEvaluationRAII Speculate(Info, &Diag); 5873 Diag.clear(); 5874 StmtVisitorTy::Visit(E->getTrueExpr()); 5875 if (Diag.empty()) 5876 return; 5877 } 5878 5879 Error(E, diag::note_constexpr_conditional_never_const); 5880 } 5881 5882 5883 template<typename ConditionalOperator> 5884 bool HandleConditionalOperator(const ConditionalOperator *E) { 5885 bool BoolResult; 5886 if (!EvaluateAsBooleanCondition(E->getCond(), BoolResult, Info)) { 5887 if (Info.checkingPotentialConstantExpression() && Info.noteFailure()) { 5888 CheckPotentialConstantConditional(E); 5889 return false; 5890 } 5891 if (Info.noteFailure()) { 5892 StmtVisitorTy::Visit(E->getTrueExpr()); 5893 StmtVisitorTy::Visit(E->getFalseExpr()); 5894 } 5895 return false; 5896 } 5897 5898 Expr *EvalExpr = BoolResult ? E->getTrueExpr() : E->getFalseExpr(); 5899 return StmtVisitorTy::Visit(EvalExpr); 5900 } 5901 5902 protected: 5903 EvalInfo &Info; 5904 typedef ConstStmtVisitor<Derived, bool> StmtVisitorTy; 5905 typedef ExprEvaluatorBase ExprEvaluatorBaseTy; 5906 5907 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { 5908 return Info.CCEDiag(E, D); 5909 } 5910 5911 bool ZeroInitialization(const Expr *E) { return Error(E); } 5912 5913 public: 5914 ExprEvaluatorBase(EvalInfo &Info) : Info(Info) {} 5915 5916 EvalInfo &getEvalInfo() { return Info; } 5917 5918 /// Report an evaluation error. This should only be called when an error is 5919 /// first discovered. When propagating an error, just return false. 5920 bool Error(const Expr *E, diag::kind D) { 5921 Info.FFDiag(E, D); 5922 return false; 5923 } 5924 bool Error(const Expr *E) { 5925 return Error(E, diag::note_invalid_subexpr_in_const_expr); 5926 } 5927 5928 bool VisitStmt(const Stmt *) { 5929 llvm_unreachable("Expression evaluator should not be called on stmts"); 5930 } 5931 bool VisitExpr(const Expr *E) { 5932 return Error(E); 5933 } 5934 5935 bool VisitConstantExpr(const ConstantExpr *E) 5936 { return StmtVisitorTy::Visit(E->getSubExpr()); } 5937 bool VisitParenExpr(const ParenExpr *E) 5938 { return StmtVisitorTy::Visit(E->getSubExpr()); } 5939 bool VisitUnaryExtension(const UnaryOperator *E) 5940 { return StmtVisitorTy::Visit(E->getSubExpr()); } 5941 bool VisitUnaryPlus(const UnaryOperator *E) 5942 { return StmtVisitorTy::Visit(E->getSubExpr()); } 5943 bool VisitChooseExpr(const ChooseExpr *E) 5944 { return StmtVisitorTy::Visit(E->getChosenSubExpr()); } 5945 bool VisitGenericSelectionExpr(const GenericSelectionExpr *E) 5946 { return StmtVisitorTy::Visit(E->getResultExpr()); } 5947 bool VisitSubstNonTypeTemplateParmExpr(const SubstNonTypeTemplateParmExpr *E) 5948 { return StmtVisitorTy::Visit(E->getReplacement()); } 5949 bool VisitCXXDefaultArgExpr(const CXXDefaultArgExpr *E) { 5950 TempVersionRAII RAII(*Info.CurrentCall); 5951 SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope); 5952 return StmtVisitorTy::Visit(E->getExpr()); 5953 } 5954 bool VisitCXXDefaultInitExpr(const CXXDefaultInitExpr *E) { 5955 TempVersionRAII RAII(*Info.CurrentCall); 5956 // The initializer may not have been parsed yet, or might be erroneous. 5957 if (!E->getExpr()) 5958 return Error(E); 5959 SourceLocExprScopeGuard Guard(E, Info.CurrentCall->CurSourceLocExprScope); 5960 return StmtVisitorTy::Visit(E->getExpr()); 5961 } 5962 5963 // We cannot create any objects for which cleanups are required, so there is 5964 // nothing to do here; all cleanups must come from unevaluated subexpressions. 5965 bool VisitExprWithCleanups(const ExprWithCleanups *E) 5966 { return StmtVisitorTy::Visit(E->getSubExpr()); } 5967 5968 bool VisitCXXReinterpretCastExpr(const CXXReinterpretCastExpr *E) { 5969 CCEDiag(E, diag::note_constexpr_invalid_cast) << 0; 5970 return static_cast<Derived*>(this)->VisitCastExpr(E); 5971 } 5972 bool VisitCXXDynamicCastExpr(const CXXDynamicCastExpr *E) { 5973 if (!Info.Ctx.getLangOpts().CPlusPlus2a) 5974 CCEDiag(E, diag::note_constexpr_invalid_cast) << 1; 5975 return static_cast<Derived*>(this)->VisitCastExpr(E); 5976 } 5977 bool VisitBuiltinBitCastExpr(const BuiltinBitCastExpr *E) { 5978 return static_cast<Derived*>(this)->VisitCastExpr(E); 5979 } 5980 5981 bool VisitBinaryOperator(const BinaryOperator *E) { 5982 switch (E->getOpcode()) { 5983 default: 5984 return Error(E); 5985 5986 case BO_Comma: 5987 VisitIgnoredValue(E->getLHS()); 5988 return StmtVisitorTy::Visit(E->getRHS()); 5989 5990 case BO_PtrMemD: 5991 case BO_PtrMemI: { 5992 LValue Obj; 5993 if (!HandleMemberPointerAccess(Info, E, Obj)) 5994 return false; 5995 APValue Result; 5996 if (!handleLValueToRValueConversion(Info, E, E->getType(), Obj, Result)) 5997 return false; 5998 return DerivedSuccess(Result, E); 5999 } 6000 } 6001 } 6002 6003 bool VisitBinaryConditionalOperator(const BinaryConditionalOperator *E) { 6004 // Evaluate and cache the common expression. We treat it as a temporary, 6005 // even though it's not quite the same thing. 6006 if (!Evaluate(Info.CurrentCall->createTemporary(E->getOpaqueValue(), false), 6007 Info, E->getCommon())) 6008 return false; 6009 6010 return HandleConditionalOperator(E); 6011 } 6012 6013 bool VisitConditionalOperator(const ConditionalOperator *E) { 6014 bool IsBcpCall = false; 6015 // If the condition (ignoring parens) is a __builtin_constant_p call, 6016 // the result is a constant expression if it can be folded without 6017 // side-effects. This is an important GNU extension. See GCC PR38377 6018 // for discussion. 6019 if (const CallExpr *CallCE = 6020 dyn_cast<CallExpr>(E->getCond()->IgnoreParenCasts())) 6021 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p) 6022 IsBcpCall = true; 6023 6024 // Always assume __builtin_constant_p(...) ? ... : ... is a potential 6025 // constant expression; we can't check whether it's potentially foldable. 6026 // FIXME: We should instead treat __builtin_constant_p as non-constant if 6027 // it would return 'false' in this mode. 6028 if (Info.checkingPotentialConstantExpression() && IsBcpCall) 6029 return false; 6030 6031 FoldConstant Fold(Info, IsBcpCall); 6032 if (!HandleConditionalOperator(E)) { 6033 Fold.keepDiagnostics(); 6034 return false; 6035 } 6036 6037 return true; 6038 } 6039 6040 bool VisitOpaqueValueExpr(const OpaqueValueExpr *E) { 6041 if (APValue *Value = Info.CurrentCall->getCurrentTemporary(E)) 6042 return DerivedSuccess(*Value, E); 6043 6044 const Expr *Source = E->getSourceExpr(); 6045 if (!Source) 6046 return Error(E); 6047 if (Source == E) { // sanity checking. 6048 assert(0 && "OpaqueValueExpr recursively refers to itself"); 6049 return Error(E); 6050 } 6051 return StmtVisitorTy::Visit(Source); 6052 } 6053 6054 bool VisitCallExpr(const CallExpr *E) { 6055 APValue Result; 6056 if (!handleCallExpr(E, Result, nullptr)) 6057 return false; 6058 return DerivedSuccess(Result, E); 6059 } 6060 6061 bool handleCallExpr(const CallExpr *E, APValue &Result, 6062 const LValue *ResultSlot) { 6063 const Expr *Callee = E->getCallee()->IgnoreParens(); 6064 QualType CalleeType = Callee->getType(); 6065 6066 const FunctionDecl *FD = nullptr; 6067 LValue *This = nullptr, ThisVal; 6068 auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs()); 6069 bool HasQualifier = false; 6070 6071 // Extract function decl and 'this' pointer from the callee. 6072 if (CalleeType->isSpecificBuiltinType(BuiltinType::BoundMember)) { 6073 const CXXMethodDecl *Member = nullptr; 6074 if (const MemberExpr *ME = dyn_cast<MemberExpr>(Callee)) { 6075 // Explicit bound member calls, such as x.f() or p->g(); 6076 if (!EvaluateObjectArgument(Info, ME->getBase(), ThisVal)) 6077 return false; 6078 Member = dyn_cast<CXXMethodDecl>(ME->getMemberDecl()); 6079 if (!Member) 6080 return Error(Callee); 6081 This = &ThisVal; 6082 HasQualifier = ME->hasQualifier(); 6083 } else if (const BinaryOperator *BE = dyn_cast<BinaryOperator>(Callee)) { 6084 // Indirect bound member calls ('.*' or '->*'). 6085 Member = dyn_cast_or_null<CXXMethodDecl>( 6086 HandleMemberPointerAccess(Info, BE, ThisVal, false)); 6087 if (!Member) 6088 return Error(Callee); 6089 This = &ThisVal; 6090 } else 6091 return Error(Callee); 6092 FD = Member; 6093 } else if (CalleeType->isFunctionPointerType()) { 6094 LValue Call; 6095 if (!EvaluatePointer(Callee, Call, Info)) 6096 return false; 6097 6098 if (!Call.getLValueOffset().isZero()) 6099 return Error(Callee); 6100 FD = dyn_cast_or_null<FunctionDecl>( 6101 Call.getLValueBase().dyn_cast<const ValueDecl*>()); 6102 if (!FD) 6103 return Error(Callee); 6104 // Don't call function pointers which have been cast to some other type. 6105 // Per DR (no number yet), the caller and callee can differ in noexcept. 6106 if (!Info.Ctx.hasSameFunctionTypeIgnoringExceptionSpec( 6107 CalleeType->getPointeeType(), FD->getType())) { 6108 return Error(E); 6109 } 6110 6111 // Overloaded operator calls to member functions are represented as normal 6112 // calls with '*this' as the first argument. 6113 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); 6114 if (MD && !MD->isStatic()) { 6115 // FIXME: When selecting an implicit conversion for an overloaded 6116 // operator delete, we sometimes try to evaluate calls to conversion 6117 // operators without a 'this' parameter! 6118 if (Args.empty()) 6119 return Error(E); 6120 6121 if (!EvaluateObjectArgument(Info, Args[0], ThisVal)) 6122 return false; 6123 This = &ThisVal; 6124 Args = Args.slice(1); 6125 } else if (MD && MD->isLambdaStaticInvoker()) { 6126 // Map the static invoker for the lambda back to the call operator. 6127 // Conveniently, we don't have to slice out the 'this' argument (as is 6128 // being done for the non-static case), since a static member function 6129 // doesn't have an implicit argument passed in. 6130 const CXXRecordDecl *ClosureClass = MD->getParent(); 6131 assert( 6132 ClosureClass->captures_begin() == ClosureClass->captures_end() && 6133 "Number of captures must be zero for conversion to function-ptr"); 6134 6135 const CXXMethodDecl *LambdaCallOp = 6136 ClosureClass->getLambdaCallOperator(); 6137 6138 // Set 'FD', the function that will be called below, to the call 6139 // operator. If the closure object represents a generic lambda, find 6140 // the corresponding specialization of the call operator. 6141 6142 if (ClosureClass->isGenericLambda()) { 6143 assert(MD->isFunctionTemplateSpecialization() && 6144 "A generic lambda's static-invoker function must be a " 6145 "template specialization"); 6146 const TemplateArgumentList *TAL = MD->getTemplateSpecializationArgs(); 6147 FunctionTemplateDecl *CallOpTemplate = 6148 LambdaCallOp->getDescribedFunctionTemplate(); 6149 void *InsertPos = nullptr; 6150 FunctionDecl *CorrespondingCallOpSpecialization = 6151 CallOpTemplate->findSpecialization(TAL->asArray(), InsertPos); 6152 assert(CorrespondingCallOpSpecialization && 6153 "We must always have a function call operator specialization " 6154 "that corresponds to our static invoker specialization"); 6155 FD = cast<CXXMethodDecl>(CorrespondingCallOpSpecialization); 6156 } else 6157 FD = LambdaCallOp; 6158 } 6159 } else 6160 return Error(E); 6161 6162 SmallVector<QualType, 4> CovariantAdjustmentPath; 6163 if (This) { 6164 auto *NamedMember = dyn_cast<CXXMethodDecl>(FD); 6165 if (NamedMember && NamedMember->isVirtual() && !HasQualifier) { 6166 // Perform virtual dispatch, if necessary. 6167 FD = HandleVirtualDispatch(Info, E, *This, NamedMember, 6168 CovariantAdjustmentPath); 6169 if (!FD) 6170 return false; 6171 } else { 6172 // Check that the 'this' pointer points to an object of the right type. 6173 if (!checkNonVirtualMemberCallThisPointer(Info, E, *This)) 6174 return false; 6175 } 6176 } 6177 6178 const FunctionDecl *Definition = nullptr; 6179 Stmt *Body = FD->getBody(Definition); 6180 6181 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body) || 6182 !HandleFunctionCall(E->getExprLoc(), Definition, This, Args, Body, Info, 6183 Result, ResultSlot)) 6184 return false; 6185 6186 if (!CovariantAdjustmentPath.empty() && 6187 !HandleCovariantReturnAdjustment(Info, E, Result, 6188 CovariantAdjustmentPath)) 6189 return false; 6190 6191 return true; 6192 } 6193 6194 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { 6195 return StmtVisitorTy::Visit(E->getInitializer()); 6196 } 6197 bool VisitInitListExpr(const InitListExpr *E) { 6198 if (E->getNumInits() == 0) 6199 return DerivedZeroInitialization(E); 6200 if (E->getNumInits() == 1) 6201 return StmtVisitorTy::Visit(E->getInit(0)); 6202 return Error(E); 6203 } 6204 bool VisitImplicitValueInitExpr(const ImplicitValueInitExpr *E) { 6205 return DerivedZeroInitialization(E); 6206 } 6207 bool VisitCXXScalarValueInitExpr(const CXXScalarValueInitExpr *E) { 6208 return DerivedZeroInitialization(E); 6209 } 6210 bool VisitCXXNullPtrLiteralExpr(const CXXNullPtrLiteralExpr *E) { 6211 return DerivedZeroInitialization(E); 6212 } 6213 6214 /// A member expression where the object is a prvalue is itself a prvalue. 6215 bool VisitMemberExpr(const MemberExpr *E) { 6216 assert(!Info.Ctx.getLangOpts().CPlusPlus11 && 6217 "missing temporary materialization conversion"); 6218 assert(!E->isArrow() && "missing call to bound member function?"); 6219 6220 APValue Val; 6221 if (!Evaluate(Val, Info, E->getBase())) 6222 return false; 6223 6224 QualType BaseTy = E->getBase()->getType(); 6225 6226 const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl()); 6227 if (!FD) return Error(E); 6228 assert(!FD->getType()->isReferenceType() && "prvalue reference?"); 6229 assert(BaseTy->castAs<RecordType>()->getDecl()->getCanonicalDecl() == 6230 FD->getParent()->getCanonicalDecl() && "record / field mismatch"); 6231 6232 // Note: there is no lvalue base here. But this case should only ever 6233 // happen in C or in C++98, where we cannot be evaluating a constexpr 6234 // constructor, which is the only case the base matters. 6235 CompleteObject Obj(APValue::LValueBase(), &Val, BaseTy); 6236 SubobjectDesignator Designator(BaseTy); 6237 Designator.addDeclUnchecked(FD); 6238 6239 APValue Result; 6240 return extractSubobject(Info, E, Obj, Designator, Result) && 6241 DerivedSuccess(Result, E); 6242 } 6243 6244 bool VisitCastExpr(const CastExpr *E) { 6245 switch (E->getCastKind()) { 6246 default: 6247 break; 6248 6249 case CK_AtomicToNonAtomic: { 6250 APValue AtomicVal; 6251 // This does not need to be done in place even for class/array types: 6252 // atomic-to-non-atomic conversion implies copying the object 6253 // representation. 6254 if (!Evaluate(AtomicVal, Info, E->getSubExpr())) 6255 return false; 6256 return DerivedSuccess(AtomicVal, E); 6257 } 6258 6259 case CK_NoOp: 6260 case CK_UserDefinedConversion: 6261 return StmtVisitorTy::Visit(E->getSubExpr()); 6262 6263 case CK_LValueToRValue: { 6264 LValue LVal; 6265 if (!EvaluateLValue(E->getSubExpr(), LVal, Info)) 6266 return false; 6267 APValue RVal; 6268 // Note, we use the subexpression's type in order to retain cv-qualifiers. 6269 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(), 6270 LVal, RVal)) 6271 return false; 6272 return DerivedSuccess(RVal, E); 6273 } 6274 case CK_LValueToRValueBitCast: { 6275 APValue DestValue, SourceValue; 6276 if (!Evaluate(SourceValue, Info, E->getSubExpr())) 6277 return false; 6278 if (!handleLValueToRValueBitCast(Info, DestValue, SourceValue, E)) 6279 return false; 6280 return DerivedSuccess(DestValue, E); 6281 } 6282 } 6283 6284 return Error(E); 6285 } 6286 6287 bool VisitUnaryPostInc(const UnaryOperator *UO) { 6288 return VisitUnaryPostIncDec(UO); 6289 } 6290 bool VisitUnaryPostDec(const UnaryOperator *UO) { 6291 return VisitUnaryPostIncDec(UO); 6292 } 6293 bool VisitUnaryPostIncDec(const UnaryOperator *UO) { 6294 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) 6295 return Error(UO); 6296 6297 LValue LVal; 6298 if (!EvaluateLValue(UO->getSubExpr(), LVal, Info)) 6299 return false; 6300 APValue RVal; 6301 if (!handleIncDec(this->Info, UO, LVal, UO->getSubExpr()->getType(), 6302 UO->isIncrementOp(), &RVal)) 6303 return false; 6304 return DerivedSuccess(RVal, UO); 6305 } 6306 6307 bool VisitStmtExpr(const StmtExpr *E) { 6308 // We will have checked the full-expressions inside the statement expression 6309 // when they were completed, and don't need to check them again now. 6310 if (Info.checkingForUndefinedBehavior()) 6311 return Error(E); 6312 6313 BlockScopeRAII Scope(Info); 6314 const CompoundStmt *CS = E->getSubStmt(); 6315 if (CS->body_empty()) 6316 return true; 6317 6318 for (CompoundStmt::const_body_iterator BI = CS->body_begin(), 6319 BE = CS->body_end(); 6320 /**/; ++BI) { 6321 if (BI + 1 == BE) { 6322 const Expr *FinalExpr = dyn_cast<Expr>(*BI); 6323 if (!FinalExpr) { 6324 Info.FFDiag((*BI)->getBeginLoc(), 6325 diag::note_constexpr_stmt_expr_unsupported); 6326 return false; 6327 } 6328 return this->Visit(FinalExpr); 6329 } 6330 6331 APValue ReturnValue; 6332 StmtResult Result = { ReturnValue, nullptr }; 6333 EvalStmtResult ESR = EvaluateStmt(Result, Info, *BI); 6334 if (ESR != ESR_Succeeded) { 6335 // FIXME: If the statement-expression terminated due to 'return', 6336 // 'break', or 'continue', it would be nice to propagate that to 6337 // the outer statement evaluation rather than bailing out. 6338 if (ESR != ESR_Failed) 6339 Info.FFDiag((*BI)->getBeginLoc(), 6340 diag::note_constexpr_stmt_expr_unsupported); 6341 return false; 6342 } 6343 } 6344 6345 llvm_unreachable("Return from function from the loop above."); 6346 } 6347 6348 /// Visit a value which is evaluated, but whose value is ignored. 6349 void VisitIgnoredValue(const Expr *E) { 6350 EvaluateIgnoredValue(Info, E); 6351 } 6352 6353 /// Potentially visit a MemberExpr's base expression. 6354 void VisitIgnoredBaseExpression(const Expr *E) { 6355 // While MSVC doesn't evaluate the base expression, it does diagnose the 6356 // presence of side-effecting behavior. 6357 if (Info.getLangOpts().MSVCCompat && !E->HasSideEffects(Info.Ctx)) 6358 return; 6359 VisitIgnoredValue(E); 6360 } 6361 }; 6362 6363 } // namespace 6364 6365 //===----------------------------------------------------------------------===// 6366 // Common base class for lvalue and temporary evaluation. 6367 //===----------------------------------------------------------------------===// 6368 namespace { 6369 template<class Derived> 6370 class LValueExprEvaluatorBase 6371 : public ExprEvaluatorBase<Derived> { 6372 protected: 6373 LValue &Result; 6374 bool InvalidBaseOK; 6375 typedef LValueExprEvaluatorBase LValueExprEvaluatorBaseTy; 6376 typedef ExprEvaluatorBase<Derived> ExprEvaluatorBaseTy; 6377 6378 bool Success(APValue::LValueBase B) { 6379 Result.set(B); 6380 return true; 6381 } 6382 6383 bool evaluatePointer(const Expr *E, LValue &Result) { 6384 return EvaluatePointer(E, Result, this->Info, InvalidBaseOK); 6385 } 6386 6387 public: 6388 LValueExprEvaluatorBase(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) 6389 : ExprEvaluatorBaseTy(Info), Result(Result), 6390 InvalidBaseOK(InvalidBaseOK) {} 6391 6392 bool Success(const APValue &V, const Expr *E) { 6393 Result.setFrom(this->Info.Ctx, V); 6394 return true; 6395 } 6396 6397 bool VisitMemberExpr(const MemberExpr *E) { 6398 // Handle non-static data members. 6399 QualType BaseTy; 6400 bool EvalOK; 6401 if (E->isArrow()) { 6402 EvalOK = evaluatePointer(E->getBase(), Result); 6403 BaseTy = E->getBase()->getType()->castAs<PointerType>()->getPointeeType(); 6404 } else if (E->getBase()->isRValue()) { 6405 assert(E->getBase()->getType()->isRecordType()); 6406 EvalOK = EvaluateTemporary(E->getBase(), Result, this->Info); 6407 BaseTy = E->getBase()->getType(); 6408 } else { 6409 EvalOK = this->Visit(E->getBase()); 6410 BaseTy = E->getBase()->getType(); 6411 } 6412 if (!EvalOK) { 6413 if (!InvalidBaseOK) 6414 return false; 6415 Result.setInvalid(E); 6416 return true; 6417 } 6418 6419 const ValueDecl *MD = E->getMemberDecl(); 6420 if (const FieldDecl *FD = dyn_cast<FieldDecl>(E->getMemberDecl())) { 6421 assert(BaseTy->getAs<RecordType>()->getDecl()->getCanonicalDecl() == 6422 FD->getParent()->getCanonicalDecl() && "record / field mismatch"); 6423 (void)BaseTy; 6424 if (!HandleLValueMember(this->Info, E, Result, FD)) 6425 return false; 6426 } else if (const IndirectFieldDecl *IFD = dyn_cast<IndirectFieldDecl>(MD)) { 6427 if (!HandleLValueIndirectMember(this->Info, E, Result, IFD)) 6428 return false; 6429 } else 6430 return this->Error(E); 6431 6432 if (MD->getType()->isReferenceType()) { 6433 APValue RefValue; 6434 if (!handleLValueToRValueConversion(this->Info, E, MD->getType(), Result, 6435 RefValue)) 6436 return false; 6437 return Success(RefValue, E); 6438 } 6439 return true; 6440 } 6441 6442 bool VisitBinaryOperator(const BinaryOperator *E) { 6443 switch (E->getOpcode()) { 6444 default: 6445 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 6446 6447 case BO_PtrMemD: 6448 case BO_PtrMemI: 6449 return HandleMemberPointerAccess(this->Info, E, Result); 6450 } 6451 } 6452 6453 bool VisitCastExpr(const CastExpr *E) { 6454 switch (E->getCastKind()) { 6455 default: 6456 return ExprEvaluatorBaseTy::VisitCastExpr(E); 6457 6458 case CK_DerivedToBase: 6459 case CK_UncheckedDerivedToBase: 6460 if (!this->Visit(E->getSubExpr())) 6461 return false; 6462 6463 // Now figure out the necessary offset to add to the base LV to get from 6464 // the derived class to the base class. 6465 return HandleLValueBasePath(this->Info, E, E->getSubExpr()->getType(), 6466 Result); 6467 } 6468 } 6469 }; 6470 } 6471 6472 //===----------------------------------------------------------------------===// 6473 // LValue Evaluation 6474 // 6475 // This is used for evaluating lvalues (in C and C++), xvalues (in C++11), 6476 // function designators (in C), decl references to void objects (in C), and 6477 // temporaries (if building with -Wno-address-of-temporary). 6478 // 6479 // LValue evaluation produces values comprising a base expression of one of the 6480 // following types: 6481 // - Declarations 6482 // * VarDecl 6483 // * FunctionDecl 6484 // - Literals 6485 // * CompoundLiteralExpr in C (and in global scope in C++) 6486 // * StringLiteral 6487 // * PredefinedExpr 6488 // * ObjCStringLiteralExpr 6489 // * ObjCEncodeExpr 6490 // * AddrLabelExpr 6491 // * BlockExpr 6492 // * CallExpr for a MakeStringConstant builtin 6493 // - typeid(T) expressions, as TypeInfoLValues 6494 // - Locals and temporaries 6495 // * MaterializeTemporaryExpr 6496 // * Any Expr, with a CallIndex indicating the function in which the temporary 6497 // was evaluated, for cases where the MaterializeTemporaryExpr is missing 6498 // from the AST (FIXME). 6499 // * A MaterializeTemporaryExpr that has static storage duration, with no 6500 // CallIndex, for a lifetime-extended temporary. 6501 // plus an offset in bytes. 6502 //===----------------------------------------------------------------------===// 6503 namespace { 6504 class LValueExprEvaluator 6505 : public LValueExprEvaluatorBase<LValueExprEvaluator> { 6506 public: 6507 LValueExprEvaluator(EvalInfo &Info, LValue &Result, bool InvalidBaseOK) : 6508 LValueExprEvaluatorBaseTy(Info, Result, InvalidBaseOK) {} 6509 6510 bool VisitVarDecl(const Expr *E, const VarDecl *VD); 6511 bool VisitUnaryPreIncDec(const UnaryOperator *UO); 6512 6513 bool VisitDeclRefExpr(const DeclRefExpr *E); 6514 bool VisitPredefinedExpr(const PredefinedExpr *E) { return Success(E); } 6515 bool VisitMaterializeTemporaryExpr(const MaterializeTemporaryExpr *E); 6516 bool VisitCompoundLiteralExpr(const CompoundLiteralExpr *E); 6517 bool VisitMemberExpr(const MemberExpr *E); 6518 bool VisitStringLiteral(const StringLiteral *E) { return Success(E); } 6519 bool VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { return Success(E); } 6520 bool VisitCXXTypeidExpr(const CXXTypeidExpr *E); 6521 bool VisitCXXUuidofExpr(const CXXUuidofExpr *E); 6522 bool VisitArraySubscriptExpr(const ArraySubscriptExpr *E); 6523 bool VisitUnaryDeref(const UnaryOperator *E); 6524 bool VisitUnaryReal(const UnaryOperator *E); 6525 bool VisitUnaryImag(const UnaryOperator *E); 6526 bool VisitUnaryPreInc(const UnaryOperator *UO) { 6527 return VisitUnaryPreIncDec(UO); 6528 } 6529 bool VisitUnaryPreDec(const UnaryOperator *UO) { 6530 return VisitUnaryPreIncDec(UO); 6531 } 6532 bool VisitBinAssign(const BinaryOperator *BO); 6533 bool VisitCompoundAssignOperator(const CompoundAssignOperator *CAO); 6534 6535 bool VisitCastExpr(const CastExpr *E) { 6536 switch (E->getCastKind()) { 6537 default: 6538 return LValueExprEvaluatorBaseTy::VisitCastExpr(E); 6539 6540 case CK_LValueBitCast: 6541 this->CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 6542 if (!Visit(E->getSubExpr())) 6543 return false; 6544 Result.Designator.setInvalid(); 6545 return true; 6546 6547 case CK_BaseToDerived: 6548 if (!Visit(E->getSubExpr())) 6549 return false; 6550 return HandleBaseToDerivedCast(Info, E, Result); 6551 6552 case CK_Dynamic: 6553 if (!Visit(E->getSubExpr())) 6554 return false; 6555 return HandleDynamicCast(Info, cast<ExplicitCastExpr>(E), Result); 6556 } 6557 } 6558 }; 6559 } // end anonymous namespace 6560 6561 /// Evaluate an expression as an lvalue. This can be legitimately called on 6562 /// expressions which are not glvalues, in three cases: 6563 /// * function designators in C, and 6564 /// * "extern void" objects 6565 /// * @selector() expressions in Objective-C 6566 static bool EvaluateLValue(const Expr *E, LValue &Result, EvalInfo &Info, 6567 bool InvalidBaseOK) { 6568 assert(E->isGLValue() || E->getType()->isFunctionType() || 6569 E->getType()->isVoidType() || isa<ObjCSelectorExpr>(E)); 6570 return LValueExprEvaluator(Info, Result, InvalidBaseOK).Visit(E); 6571 } 6572 6573 bool LValueExprEvaluator::VisitDeclRefExpr(const DeclRefExpr *E) { 6574 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(E->getDecl())) 6575 return Success(FD); 6576 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getDecl())) 6577 return VisitVarDecl(E, VD); 6578 if (const BindingDecl *BD = dyn_cast<BindingDecl>(E->getDecl())) 6579 return Visit(BD->getBinding()); 6580 return Error(E); 6581 } 6582 6583 6584 bool LValueExprEvaluator::VisitVarDecl(const Expr *E, const VarDecl *VD) { 6585 6586 // If we are within a lambda's call operator, check whether the 'VD' referred 6587 // to within 'E' actually represents a lambda-capture that maps to a 6588 // data-member/field within the closure object, and if so, evaluate to the 6589 // field or what the field refers to. 6590 if (Info.CurrentCall && isLambdaCallOperator(Info.CurrentCall->Callee) && 6591 isa<DeclRefExpr>(E) && 6592 cast<DeclRefExpr>(E)->refersToEnclosingVariableOrCapture()) { 6593 // We don't always have a complete capture-map when checking or inferring if 6594 // the function call operator meets the requirements of a constexpr function 6595 // - but we don't need to evaluate the captures to determine constexprness 6596 // (dcl.constexpr C++17). 6597 if (Info.checkingPotentialConstantExpression()) 6598 return false; 6599 6600 if (auto *FD = Info.CurrentCall->LambdaCaptureFields.lookup(VD)) { 6601 // Start with 'Result' referring to the complete closure object... 6602 Result = *Info.CurrentCall->This; 6603 // ... then update it to refer to the field of the closure object 6604 // that represents the capture. 6605 if (!HandleLValueMember(Info, E, Result, FD)) 6606 return false; 6607 // And if the field is of reference type, update 'Result' to refer to what 6608 // the field refers to. 6609 if (FD->getType()->isReferenceType()) { 6610 APValue RVal; 6611 if (!handleLValueToRValueConversion(Info, E, FD->getType(), Result, 6612 RVal)) 6613 return false; 6614 Result.setFrom(Info.Ctx, RVal); 6615 } 6616 return true; 6617 } 6618 } 6619 CallStackFrame *Frame = nullptr; 6620 if (VD->hasLocalStorage() && Info.CurrentCall->Index > 1) { 6621 // Only if a local variable was declared in the function currently being 6622 // evaluated, do we expect to be able to find its value in the current 6623 // frame. (Otherwise it was likely declared in an enclosing context and 6624 // could either have a valid evaluatable value (for e.g. a constexpr 6625 // variable) or be ill-formed (and trigger an appropriate evaluation 6626 // diagnostic)). 6627 if (Info.CurrentCall->Callee && 6628 Info.CurrentCall->Callee->Equals(VD->getDeclContext())) { 6629 Frame = Info.CurrentCall; 6630 } 6631 } 6632 6633 if (!VD->getType()->isReferenceType()) { 6634 if (Frame) { 6635 Result.set({VD, Frame->Index, 6636 Info.CurrentCall->getCurrentTemporaryVersion(VD)}); 6637 return true; 6638 } 6639 return Success(VD); 6640 } 6641 6642 APValue *V; 6643 if (!evaluateVarDeclInit(Info, E, VD, Frame, V, nullptr)) 6644 return false; 6645 if (!V->hasValue()) { 6646 // FIXME: Is it possible for V to be indeterminate here? If so, we should 6647 // adjust the diagnostic to say that. 6648 if (!Info.checkingPotentialConstantExpression()) 6649 Info.FFDiag(E, diag::note_constexpr_use_uninit_reference); 6650 return false; 6651 } 6652 return Success(*V, E); 6653 } 6654 6655 bool LValueExprEvaluator::VisitMaterializeTemporaryExpr( 6656 const MaterializeTemporaryExpr *E) { 6657 // Walk through the expression to find the materialized temporary itself. 6658 SmallVector<const Expr *, 2> CommaLHSs; 6659 SmallVector<SubobjectAdjustment, 2> Adjustments; 6660 const Expr *Inner = E->GetTemporaryExpr()-> 6661 skipRValueSubobjectAdjustments(CommaLHSs, Adjustments); 6662 6663 // If we passed any comma operators, evaluate their LHSs. 6664 for (unsigned I = 0, N = CommaLHSs.size(); I != N; ++I) 6665 if (!EvaluateIgnoredValue(Info, CommaLHSs[I])) 6666 return false; 6667 6668 // A materialized temporary with static storage duration can appear within the 6669 // result of a constant expression evaluation, so we need to preserve its 6670 // value for use outside this evaluation. 6671 APValue *Value; 6672 if (E->getStorageDuration() == SD_Static) { 6673 Value = Info.Ctx.getMaterializedTemporaryValue(E, true); 6674 *Value = APValue(); 6675 Result.set(E); 6676 } else { 6677 Value = &createTemporary(E, E->getStorageDuration() == SD_Automatic, Result, 6678 *Info.CurrentCall); 6679 } 6680 6681 QualType Type = Inner->getType(); 6682 6683 // Materialize the temporary itself. 6684 if (!EvaluateInPlace(*Value, Info, Result, Inner) || 6685 (E->getStorageDuration() == SD_Static && 6686 !CheckConstantExpression(Info, E->getExprLoc(), Type, *Value))) { 6687 *Value = APValue(); 6688 return false; 6689 } 6690 6691 // Adjust our lvalue to refer to the desired subobject. 6692 for (unsigned I = Adjustments.size(); I != 0; /**/) { 6693 --I; 6694 switch (Adjustments[I].Kind) { 6695 case SubobjectAdjustment::DerivedToBaseAdjustment: 6696 if (!HandleLValueBasePath(Info, Adjustments[I].DerivedToBase.BasePath, 6697 Type, Result)) 6698 return false; 6699 Type = Adjustments[I].DerivedToBase.BasePath->getType(); 6700 break; 6701 6702 case SubobjectAdjustment::FieldAdjustment: 6703 if (!HandleLValueMember(Info, E, Result, Adjustments[I].Field)) 6704 return false; 6705 Type = Adjustments[I].Field->getType(); 6706 break; 6707 6708 case SubobjectAdjustment::MemberPointerAdjustment: 6709 if (!HandleMemberPointerAccess(this->Info, Type, Result, 6710 Adjustments[I].Ptr.RHS)) 6711 return false; 6712 Type = Adjustments[I].Ptr.MPT->getPointeeType(); 6713 break; 6714 } 6715 } 6716 6717 return true; 6718 } 6719 6720 bool 6721 LValueExprEvaluator::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { 6722 assert((!Info.getLangOpts().CPlusPlus || E->isFileScope()) && 6723 "lvalue compound literal in c++?"); 6724 // Defer visiting the literal until the lvalue-to-rvalue conversion. We can 6725 // only see this when folding in C, so there's no standard to follow here. 6726 return Success(E); 6727 } 6728 6729 bool LValueExprEvaluator::VisitCXXTypeidExpr(const CXXTypeidExpr *E) { 6730 TypeInfoLValue TypeInfo; 6731 6732 if (!E->isPotentiallyEvaluated()) { 6733 if (E->isTypeOperand()) 6734 TypeInfo = TypeInfoLValue(E->getTypeOperand(Info.Ctx).getTypePtr()); 6735 else 6736 TypeInfo = TypeInfoLValue(E->getExprOperand()->getType().getTypePtr()); 6737 } else { 6738 if (!Info.Ctx.getLangOpts().CPlusPlus2a) { 6739 Info.CCEDiag(E, diag::note_constexpr_typeid_polymorphic) 6740 << E->getExprOperand()->getType() 6741 << E->getExprOperand()->getSourceRange(); 6742 } 6743 6744 if (!Visit(E->getExprOperand())) 6745 return false; 6746 6747 Optional<DynamicType> DynType = 6748 ComputeDynamicType(Info, E, Result, AK_TypeId); 6749 if (!DynType) 6750 return false; 6751 6752 TypeInfo = 6753 TypeInfoLValue(Info.Ctx.getRecordType(DynType->Type).getTypePtr()); 6754 } 6755 6756 return Success(APValue::LValueBase::getTypeInfo(TypeInfo, E->getType())); 6757 } 6758 6759 bool LValueExprEvaluator::VisitCXXUuidofExpr(const CXXUuidofExpr *E) { 6760 return Success(E); 6761 } 6762 6763 bool LValueExprEvaluator::VisitMemberExpr(const MemberExpr *E) { 6764 // Handle static data members. 6765 if (const VarDecl *VD = dyn_cast<VarDecl>(E->getMemberDecl())) { 6766 VisitIgnoredBaseExpression(E->getBase()); 6767 return VisitVarDecl(E, VD); 6768 } 6769 6770 // Handle static member functions. 6771 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(E->getMemberDecl())) { 6772 if (MD->isStatic()) { 6773 VisitIgnoredBaseExpression(E->getBase()); 6774 return Success(MD); 6775 } 6776 } 6777 6778 // Handle non-static data members. 6779 return LValueExprEvaluatorBaseTy::VisitMemberExpr(E); 6780 } 6781 6782 bool LValueExprEvaluator::VisitArraySubscriptExpr(const ArraySubscriptExpr *E) { 6783 // FIXME: Deal with vectors as array subscript bases. 6784 if (E->getBase()->getType()->isVectorType()) 6785 return Error(E); 6786 6787 bool Success = true; 6788 if (!evaluatePointer(E->getBase(), Result)) { 6789 if (!Info.noteFailure()) 6790 return false; 6791 Success = false; 6792 } 6793 6794 APSInt Index; 6795 if (!EvaluateInteger(E->getIdx(), Index, Info)) 6796 return false; 6797 6798 return Success && 6799 HandleLValueArrayAdjustment(Info, E, Result, E->getType(), Index); 6800 } 6801 6802 bool LValueExprEvaluator::VisitUnaryDeref(const UnaryOperator *E) { 6803 return evaluatePointer(E->getSubExpr(), Result); 6804 } 6805 6806 bool LValueExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 6807 if (!Visit(E->getSubExpr())) 6808 return false; 6809 // __real is a no-op on scalar lvalues. 6810 if (E->getSubExpr()->getType()->isAnyComplexType()) 6811 HandleLValueComplexElement(Info, E, Result, E->getType(), false); 6812 return true; 6813 } 6814 6815 bool LValueExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 6816 assert(E->getSubExpr()->getType()->isAnyComplexType() && 6817 "lvalue __imag__ on scalar?"); 6818 if (!Visit(E->getSubExpr())) 6819 return false; 6820 HandleLValueComplexElement(Info, E, Result, E->getType(), true); 6821 return true; 6822 } 6823 6824 bool LValueExprEvaluator::VisitUnaryPreIncDec(const UnaryOperator *UO) { 6825 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) 6826 return Error(UO); 6827 6828 if (!this->Visit(UO->getSubExpr())) 6829 return false; 6830 6831 return handleIncDec( 6832 this->Info, UO, Result, UO->getSubExpr()->getType(), 6833 UO->isIncrementOp(), nullptr); 6834 } 6835 6836 bool LValueExprEvaluator::VisitCompoundAssignOperator( 6837 const CompoundAssignOperator *CAO) { 6838 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) 6839 return Error(CAO); 6840 6841 APValue RHS; 6842 6843 // The overall lvalue result is the result of evaluating the LHS. 6844 if (!this->Visit(CAO->getLHS())) { 6845 if (Info.noteFailure()) 6846 Evaluate(RHS, this->Info, CAO->getRHS()); 6847 return false; 6848 } 6849 6850 if (!Evaluate(RHS, this->Info, CAO->getRHS())) 6851 return false; 6852 6853 return handleCompoundAssignment( 6854 this->Info, CAO, 6855 Result, CAO->getLHS()->getType(), CAO->getComputationLHSType(), 6856 CAO->getOpForCompoundAssignment(CAO->getOpcode()), RHS); 6857 } 6858 6859 bool LValueExprEvaluator::VisitBinAssign(const BinaryOperator *E) { 6860 if (!Info.getLangOpts().CPlusPlus14 && !Info.keepEvaluatingAfterFailure()) 6861 return Error(E); 6862 6863 APValue NewVal; 6864 6865 if (!this->Visit(E->getLHS())) { 6866 if (Info.noteFailure()) 6867 Evaluate(NewVal, this->Info, E->getRHS()); 6868 return false; 6869 } 6870 6871 if (!Evaluate(NewVal, this->Info, E->getRHS())) 6872 return false; 6873 6874 if (Info.getLangOpts().CPlusPlus2a && 6875 !HandleUnionActiveMemberChange(Info, E->getLHS(), Result)) 6876 return false; 6877 6878 return handleAssignment(this->Info, E, Result, E->getLHS()->getType(), 6879 NewVal); 6880 } 6881 6882 //===----------------------------------------------------------------------===// 6883 // Pointer Evaluation 6884 //===----------------------------------------------------------------------===// 6885 6886 /// Attempts to compute the number of bytes available at the pointer 6887 /// returned by a function with the alloc_size attribute. Returns true if we 6888 /// were successful. Places an unsigned number into `Result`. 6889 /// 6890 /// This expects the given CallExpr to be a call to a function with an 6891 /// alloc_size attribute. 6892 static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx, 6893 const CallExpr *Call, 6894 llvm::APInt &Result) { 6895 const AllocSizeAttr *AllocSize = getAllocSizeAttr(Call); 6896 6897 assert(AllocSize && AllocSize->getElemSizeParam().isValid()); 6898 unsigned SizeArgNo = AllocSize->getElemSizeParam().getASTIndex(); 6899 unsigned BitsInSizeT = Ctx.getTypeSize(Ctx.getSizeType()); 6900 if (Call->getNumArgs() <= SizeArgNo) 6901 return false; 6902 6903 auto EvaluateAsSizeT = [&](const Expr *E, APSInt &Into) { 6904 Expr::EvalResult ExprResult; 6905 if (!E->EvaluateAsInt(ExprResult, Ctx, Expr::SE_AllowSideEffects)) 6906 return false; 6907 Into = ExprResult.Val.getInt(); 6908 if (Into.isNegative() || !Into.isIntN(BitsInSizeT)) 6909 return false; 6910 Into = Into.zextOrSelf(BitsInSizeT); 6911 return true; 6912 }; 6913 6914 APSInt SizeOfElem; 6915 if (!EvaluateAsSizeT(Call->getArg(SizeArgNo), SizeOfElem)) 6916 return false; 6917 6918 if (!AllocSize->getNumElemsParam().isValid()) { 6919 Result = std::move(SizeOfElem); 6920 return true; 6921 } 6922 6923 APSInt NumberOfElems; 6924 unsigned NumArgNo = AllocSize->getNumElemsParam().getASTIndex(); 6925 if (!EvaluateAsSizeT(Call->getArg(NumArgNo), NumberOfElems)) 6926 return false; 6927 6928 bool Overflow; 6929 llvm::APInt BytesAvailable = SizeOfElem.umul_ov(NumberOfElems, Overflow); 6930 if (Overflow) 6931 return false; 6932 6933 Result = std::move(BytesAvailable); 6934 return true; 6935 } 6936 6937 /// Convenience function. LVal's base must be a call to an alloc_size 6938 /// function. 6939 static bool getBytesReturnedByAllocSizeCall(const ASTContext &Ctx, 6940 const LValue &LVal, 6941 llvm::APInt &Result) { 6942 assert(isBaseAnAllocSizeCall(LVal.getLValueBase()) && 6943 "Can't get the size of a non alloc_size function"); 6944 const auto *Base = LVal.getLValueBase().get<const Expr *>(); 6945 const CallExpr *CE = tryUnwrapAllocSizeCall(Base); 6946 return getBytesReturnedByAllocSizeCall(Ctx, CE, Result); 6947 } 6948 6949 /// Attempts to evaluate the given LValueBase as the result of a call to 6950 /// a function with the alloc_size attribute. If it was possible to do so, this 6951 /// function will return true, make Result's Base point to said function call, 6952 /// and mark Result's Base as invalid. 6953 static bool evaluateLValueAsAllocSize(EvalInfo &Info, APValue::LValueBase Base, 6954 LValue &Result) { 6955 if (Base.isNull()) 6956 return false; 6957 6958 // Because we do no form of static analysis, we only support const variables. 6959 // 6960 // Additionally, we can't support parameters, nor can we support static 6961 // variables (in the latter case, use-before-assign isn't UB; in the former, 6962 // we have no clue what they'll be assigned to). 6963 const auto *VD = 6964 dyn_cast_or_null<VarDecl>(Base.dyn_cast<const ValueDecl *>()); 6965 if (!VD || !VD->isLocalVarDecl() || !VD->getType().isConstQualified()) 6966 return false; 6967 6968 const Expr *Init = VD->getAnyInitializer(); 6969 if (!Init) 6970 return false; 6971 6972 const Expr *E = Init->IgnoreParens(); 6973 if (!tryUnwrapAllocSizeCall(E)) 6974 return false; 6975 6976 // Store E instead of E unwrapped so that the type of the LValue's base is 6977 // what the user wanted. 6978 Result.setInvalid(E); 6979 6980 QualType Pointee = E->getType()->castAs<PointerType>()->getPointeeType(); 6981 Result.addUnsizedArray(Info, E, Pointee); 6982 return true; 6983 } 6984 6985 namespace { 6986 class PointerExprEvaluator 6987 : public ExprEvaluatorBase<PointerExprEvaluator> { 6988 LValue &Result; 6989 bool InvalidBaseOK; 6990 6991 bool Success(const Expr *E) { 6992 Result.set(E); 6993 return true; 6994 } 6995 6996 bool evaluateLValue(const Expr *E, LValue &Result) { 6997 return EvaluateLValue(E, Result, Info, InvalidBaseOK); 6998 } 6999 7000 bool evaluatePointer(const Expr *E, LValue &Result) { 7001 return EvaluatePointer(E, Result, Info, InvalidBaseOK); 7002 } 7003 7004 bool visitNonBuiltinCallExpr(const CallExpr *E); 7005 public: 7006 7007 PointerExprEvaluator(EvalInfo &info, LValue &Result, bool InvalidBaseOK) 7008 : ExprEvaluatorBaseTy(info), Result(Result), 7009 InvalidBaseOK(InvalidBaseOK) {} 7010 7011 bool Success(const APValue &V, const Expr *E) { 7012 Result.setFrom(Info.Ctx, V); 7013 return true; 7014 } 7015 bool ZeroInitialization(const Expr *E) { 7016 auto TargetVal = Info.Ctx.getTargetNullPointerValue(E->getType()); 7017 Result.setNull(E->getType(), TargetVal); 7018 return true; 7019 } 7020 7021 bool VisitBinaryOperator(const BinaryOperator *E); 7022 bool VisitCastExpr(const CastExpr* E); 7023 bool VisitUnaryAddrOf(const UnaryOperator *E); 7024 bool VisitObjCStringLiteral(const ObjCStringLiteral *E) 7025 { return Success(E); } 7026 bool VisitObjCBoxedExpr(const ObjCBoxedExpr *E) { 7027 if (E->isExpressibleAsConstantInitializer()) 7028 return Success(E); 7029 if (Info.noteFailure()) 7030 EvaluateIgnoredValue(Info, E->getSubExpr()); 7031 return Error(E); 7032 } 7033 bool VisitAddrLabelExpr(const AddrLabelExpr *E) 7034 { return Success(E); } 7035 bool VisitCallExpr(const CallExpr *E); 7036 bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp); 7037 bool VisitBlockExpr(const BlockExpr *E) { 7038 if (!E->getBlockDecl()->hasCaptures()) 7039 return Success(E); 7040 return Error(E); 7041 } 7042 bool VisitCXXThisExpr(const CXXThisExpr *E) { 7043 // Can't look at 'this' when checking a potential constant expression. 7044 if (Info.checkingPotentialConstantExpression()) 7045 return false; 7046 if (!Info.CurrentCall->This) { 7047 if (Info.getLangOpts().CPlusPlus11) 7048 Info.FFDiag(E, diag::note_constexpr_this) << E->isImplicit(); 7049 else 7050 Info.FFDiag(E); 7051 return false; 7052 } 7053 Result = *Info.CurrentCall->This; 7054 // If we are inside a lambda's call operator, the 'this' expression refers 7055 // to the enclosing '*this' object (either by value or reference) which is 7056 // either copied into the closure object's field that represents the '*this' 7057 // or refers to '*this'. 7058 if (isLambdaCallOperator(Info.CurrentCall->Callee)) { 7059 // Update 'Result' to refer to the data member/field of the closure object 7060 // that represents the '*this' capture. 7061 if (!HandleLValueMember(Info, E, Result, 7062 Info.CurrentCall->LambdaThisCaptureField)) 7063 return false; 7064 // If we captured '*this' by reference, replace the field with its referent. 7065 if (Info.CurrentCall->LambdaThisCaptureField->getType() 7066 ->isPointerType()) { 7067 APValue RVal; 7068 if (!handleLValueToRValueConversion(Info, E, E->getType(), Result, 7069 RVal)) 7070 return false; 7071 7072 Result.setFrom(Info.Ctx, RVal); 7073 } 7074 } 7075 return true; 7076 } 7077 7078 bool VisitSourceLocExpr(const SourceLocExpr *E) { 7079 assert(E->isStringType() && "SourceLocExpr isn't a pointer type?"); 7080 APValue LValResult = E->EvaluateInContext( 7081 Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr()); 7082 Result.setFrom(Info.Ctx, LValResult); 7083 return true; 7084 } 7085 7086 // FIXME: Missing: @protocol, @selector 7087 }; 7088 } // end anonymous namespace 7089 7090 static bool EvaluatePointer(const Expr* E, LValue& Result, EvalInfo &Info, 7091 bool InvalidBaseOK) { 7092 assert(E->isRValue() && E->getType()->hasPointerRepresentation()); 7093 return PointerExprEvaluator(Info, Result, InvalidBaseOK).Visit(E); 7094 } 7095 7096 bool PointerExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 7097 if (E->getOpcode() != BO_Add && 7098 E->getOpcode() != BO_Sub) 7099 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 7100 7101 const Expr *PExp = E->getLHS(); 7102 const Expr *IExp = E->getRHS(); 7103 if (IExp->getType()->isPointerType()) 7104 std::swap(PExp, IExp); 7105 7106 bool EvalPtrOK = evaluatePointer(PExp, Result); 7107 if (!EvalPtrOK && !Info.noteFailure()) 7108 return false; 7109 7110 llvm::APSInt Offset; 7111 if (!EvaluateInteger(IExp, Offset, Info) || !EvalPtrOK) 7112 return false; 7113 7114 if (E->getOpcode() == BO_Sub) 7115 negateAsSigned(Offset); 7116 7117 QualType Pointee = PExp->getType()->castAs<PointerType>()->getPointeeType(); 7118 return HandleLValueArrayAdjustment(Info, E, Result, Pointee, Offset); 7119 } 7120 7121 bool PointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { 7122 return evaluateLValue(E->getSubExpr(), Result); 7123 } 7124 7125 bool PointerExprEvaluator::VisitCastExpr(const CastExpr *E) { 7126 const Expr *SubExpr = E->getSubExpr(); 7127 7128 switch (E->getCastKind()) { 7129 default: 7130 break; 7131 case CK_BitCast: 7132 case CK_CPointerToObjCPointerCast: 7133 case CK_BlockPointerToObjCPointerCast: 7134 case CK_AnyPointerToBlockPointerCast: 7135 case CK_AddressSpaceConversion: 7136 if (!Visit(SubExpr)) 7137 return false; 7138 // Bitcasts to cv void* are static_casts, not reinterpret_casts, so are 7139 // permitted in constant expressions in C++11. Bitcasts from cv void* are 7140 // also static_casts, but we disallow them as a resolution to DR1312. 7141 if (!E->getType()->isVoidPointerType()) { 7142 Result.Designator.setInvalid(); 7143 if (SubExpr->getType()->isVoidPointerType()) 7144 CCEDiag(E, diag::note_constexpr_invalid_cast) 7145 << 3 << SubExpr->getType(); 7146 else 7147 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 7148 } 7149 if (E->getCastKind() == CK_AddressSpaceConversion && Result.IsNullPtr) 7150 ZeroInitialization(E); 7151 return true; 7152 7153 case CK_DerivedToBase: 7154 case CK_UncheckedDerivedToBase: 7155 if (!evaluatePointer(E->getSubExpr(), Result)) 7156 return false; 7157 if (!Result.Base && Result.Offset.isZero()) 7158 return true; 7159 7160 // Now figure out the necessary offset to add to the base LV to get from 7161 // the derived class to the base class. 7162 return HandleLValueBasePath(Info, E, E->getSubExpr()->getType()-> 7163 castAs<PointerType>()->getPointeeType(), 7164 Result); 7165 7166 case CK_BaseToDerived: 7167 if (!Visit(E->getSubExpr())) 7168 return false; 7169 if (!Result.Base && Result.Offset.isZero()) 7170 return true; 7171 return HandleBaseToDerivedCast(Info, E, Result); 7172 7173 case CK_Dynamic: 7174 if (!Visit(E->getSubExpr())) 7175 return false; 7176 return HandleDynamicCast(Info, cast<ExplicitCastExpr>(E), Result); 7177 7178 case CK_NullToPointer: 7179 VisitIgnoredValue(E->getSubExpr()); 7180 return ZeroInitialization(E); 7181 7182 case CK_IntegralToPointer: { 7183 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 7184 7185 APValue Value; 7186 if (!EvaluateIntegerOrLValue(SubExpr, Value, Info)) 7187 break; 7188 7189 if (Value.isInt()) { 7190 unsigned Size = Info.Ctx.getTypeSize(E->getType()); 7191 uint64_t N = Value.getInt().extOrTrunc(Size).getZExtValue(); 7192 Result.Base = (Expr*)nullptr; 7193 Result.InvalidBase = false; 7194 Result.Offset = CharUnits::fromQuantity(N); 7195 Result.Designator.setInvalid(); 7196 Result.IsNullPtr = false; 7197 return true; 7198 } else { 7199 // Cast is of an lvalue, no need to change value. 7200 Result.setFrom(Info.Ctx, Value); 7201 return true; 7202 } 7203 } 7204 7205 case CK_ArrayToPointerDecay: { 7206 if (SubExpr->isGLValue()) { 7207 if (!evaluateLValue(SubExpr, Result)) 7208 return false; 7209 } else { 7210 APValue &Value = createTemporary(SubExpr, false, Result, 7211 *Info.CurrentCall); 7212 if (!EvaluateInPlace(Value, Info, Result, SubExpr)) 7213 return false; 7214 } 7215 // The result is a pointer to the first element of the array. 7216 auto *AT = Info.Ctx.getAsArrayType(SubExpr->getType()); 7217 if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) 7218 Result.addArray(Info, E, CAT); 7219 else 7220 Result.addUnsizedArray(Info, E, AT->getElementType()); 7221 return true; 7222 } 7223 7224 case CK_FunctionToPointerDecay: 7225 return evaluateLValue(SubExpr, Result); 7226 7227 case CK_LValueToRValue: { 7228 LValue LVal; 7229 if (!evaluateLValue(E->getSubExpr(), LVal)) 7230 return false; 7231 7232 APValue RVal; 7233 // Note, we use the subexpression's type in order to retain cv-qualifiers. 7234 if (!handleLValueToRValueConversion(Info, E, E->getSubExpr()->getType(), 7235 LVal, RVal)) 7236 return InvalidBaseOK && 7237 evaluateLValueAsAllocSize(Info, LVal.Base, Result); 7238 return Success(RVal, E); 7239 } 7240 } 7241 7242 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7243 } 7244 7245 static CharUnits GetAlignOfType(EvalInfo &Info, QualType T, 7246 UnaryExprOrTypeTrait ExprKind) { 7247 // C++ [expr.alignof]p3: 7248 // When alignof is applied to a reference type, the result is the 7249 // alignment of the referenced type. 7250 if (const ReferenceType *Ref = T->getAs<ReferenceType>()) 7251 T = Ref->getPointeeType(); 7252 7253 if (T.getQualifiers().hasUnaligned()) 7254 return CharUnits::One(); 7255 7256 const bool AlignOfReturnsPreferred = 7257 Info.Ctx.getLangOpts().getClangABICompat() <= LangOptions::ClangABI::Ver7; 7258 7259 // __alignof is defined to return the preferred alignment. 7260 // Before 8, clang returned the preferred alignment for alignof and _Alignof 7261 // as well. 7262 if (ExprKind == UETT_PreferredAlignOf || AlignOfReturnsPreferred) 7263 return Info.Ctx.toCharUnitsFromBits( 7264 Info.Ctx.getPreferredTypeAlign(T.getTypePtr())); 7265 // alignof and _Alignof are defined to return the ABI alignment. 7266 else if (ExprKind == UETT_AlignOf) 7267 return Info.Ctx.getTypeAlignInChars(T.getTypePtr()); 7268 else 7269 llvm_unreachable("GetAlignOfType on a non-alignment ExprKind"); 7270 } 7271 7272 static CharUnits GetAlignOfExpr(EvalInfo &Info, const Expr *E, 7273 UnaryExprOrTypeTrait ExprKind) { 7274 E = E->IgnoreParens(); 7275 7276 // The kinds of expressions that we have special-case logic here for 7277 // should be kept up to date with the special checks for those 7278 // expressions in Sema. 7279 7280 // alignof decl is always accepted, even if it doesn't make sense: we default 7281 // to 1 in those cases. 7282 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) 7283 return Info.Ctx.getDeclAlign(DRE->getDecl(), 7284 /*RefAsPointee*/true); 7285 7286 if (const MemberExpr *ME = dyn_cast<MemberExpr>(E)) 7287 return Info.Ctx.getDeclAlign(ME->getMemberDecl(), 7288 /*RefAsPointee*/true); 7289 7290 return GetAlignOfType(Info, E->getType(), ExprKind); 7291 } 7292 7293 // To be clear: this happily visits unsupported builtins. Better name welcomed. 7294 bool PointerExprEvaluator::visitNonBuiltinCallExpr(const CallExpr *E) { 7295 if (ExprEvaluatorBaseTy::VisitCallExpr(E)) 7296 return true; 7297 7298 if (!(InvalidBaseOK && getAllocSizeAttr(E))) 7299 return false; 7300 7301 Result.setInvalid(E); 7302 QualType PointeeTy = E->getType()->castAs<PointerType>()->getPointeeType(); 7303 Result.addUnsizedArray(Info, E, PointeeTy); 7304 return true; 7305 } 7306 7307 bool PointerExprEvaluator::VisitCallExpr(const CallExpr *E) { 7308 if (IsStringLiteralCall(E)) 7309 return Success(E); 7310 7311 if (unsigned BuiltinOp = E->getBuiltinCallee()) 7312 return VisitBuiltinCallExpr(E, BuiltinOp); 7313 7314 return visitNonBuiltinCallExpr(E); 7315 } 7316 7317 bool PointerExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E, 7318 unsigned BuiltinOp) { 7319 switch (BuiltinOp) { 7320 case Builtin::BI__builtin_addressof: 7321 return evaluateLValue(E->getArg(0), Result); 7322 case Builtin::BI__builtin_assume_aligned: { 7323 // We need to be very careful here because: if the pointer does not have the 7324 // asserted alignment, then the behavior is undefined, and undefined 7325 // behavior is non-constant. 7326 if (!evaluatePointer(E->getArg(0), Result)) 7327 return false; 7328 7329 LValue OffsetResult(Result); 7330 APSInt Alignment; 7331 if (!EvaluateInteger(E->getArg(1), Alignment, Info)) 7332 return false; 7333 CharUnits Align = CharUnits::fromQuantity(Alignment.getZExtValue()); 7334 7335 if (E->getNumArgs() > 2) { 7336 APSInt Offset; 7337 if (!EvaluateInteger(E->getArg(2), Offset, Info)) 7338 return false; 7339 7340 int64_t AdditionalOffset = -Offset.getZExtValue(); 7341 OffsetResult.Offset += CharUnits::fromQuantity(AdditionalOffset); 7342 } 7343 7344 // If there is a base object, then it must have the correct alignment. 7345 if (OffsetResult.Base) { 7346 CharUnits BaseAlignment; 7347 if (const ValueDecl *VD = 7348 OffsetResult.Base.dyn_cast<const ValueDecl*>()) { 7349 BaseAlignment = Info.Ctx.getDeclAlign(VD); 7350 } else if (const Expr *E = OffsetResult.Base.dyn_cast<const Expr *>()) { 7351 BaseAlignment = GetAlignOfExpr(Info, E, UETT_AlignOf); 7352 } else { 7353 BaseAlignment = GetAlignOfType( 7354 Info, OffsetResult.Base.getTypeInfoType(), UETT_AlignOf); 7355 } 7356 7357 if (BaseAlignment < Align) { 7358 Result.Designator.setInvalid(); 7359 // FIXME: Add support to Diagnostic for long / long long. 7360 CCEDiag(E->getArg(0), 7361 diag::note_constexpr_baa_insufficient_alignment) << 0 7362 << (unsigned)BaseAlignment.getQuantity() 7363 << (unsigned)Align.getQuantity(); 7364 return false; 7365 } 7366 } 7367 7368 // The offset must also have the correct alignment. 7369 if (OffsetResult.Offset.alignTo(Align) != OffsetResult.Offset) { 7370 Result.Designator.setInvalid(); 7371 7372 (OffsetResult.Base 7373 ? CCEDiag(E->getArg(0), 7374 diag::note_constexpr_baa_insufficient_alignment) << 1 7375 : CCEDiag(E->getArg(0), 7376 diag::note_constexpr_baa_value_insufficient_alignment)) 7377 << (int)OffsetResult.Offset.getQuantity() 7378 << (unsigned)Align.getQuantity(); 7379 return false; 7380 } 7381 7382 return true; 7383 } 7384 case Builtin::BI__builtin_launder: 7385 return evaluatePointer(E->getArg(0), Result); 7386 case Builtin::BIstrchr: 7387 case Builtin::BIwcschr: 7388 case Builtin::BImemchr: 7389 case Builtin::BIwmemchr: 7390 if (Info.getLangOpts().CPlusPlus11) 7391 Info.CCEDiag(E, diag::note_constexpr_invalid_function) 7392 << /*isConstexpr*/0 << /*isConstructor*/0 7393 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'"); 7394 else 7395 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); 7396 LLVM_FALLTHROUGH; 7397 case Builtin::BI__builtin_strchr: 7398 case Builtin::BI__builtin_wcschr: 7399 case Builtin::BI__builtin_memchr: 7400 case Builtin::BI__builtin_char_memchr: 7401 case Builtin::BI__builtin_wmemchr: { 7402 if (!Visit(E->getArg(0))) 7403 return false; 7404 APSInt Desired; 7405 if (!EvaluateInteger(E->getArg(1), Desired, Info)) 7406 return false; 7407 uint64_t MaxLength = uint64_t(-1); 7408 if (BuiltinOp != Builtin::BIstrchr && 7409 BuiltinOp != Builtin::BIwcschr && 7410 BuiltinOp != Builtin::BI__builtin_strchr && 7411 BuiltinOp != Builtin::BI__builtin_wcschr) { 7412 APSInt N; 7413 if (!EvaluateInteger(E->getArg(2), N, Info)) 7414 return false; 7415 MaxLength = N.getExtValue(); 7416 } 7417 // We cannot find the value if there are no candidates to match against. 7418 if (MaxLength == 0u) 7419 return ZeroInitialization(E); 7420 if (!Result.checkNullPointerForFoldAccess(Info, E, AK_Read) || 7421 Result.Designator.Invalid) 7422 return false; 7423 QualType CharTy = Result.Designator.getType(Info.Ctx); 7424 bool IsRawByte = BuiltinOp == Builtin::BImemchr || 7425 BuiltinOp == Builtin::BI__builtin_memchr; 7426 assert(IsRawByte || 7427 Info.Ctx.hasSameUnqualifiedType( 7428 CharTy, E->getArg(0)->getType()->getPointeeType())); 7429 // Pointers to const void may point to objects of incomplete type. 7430 if (IsRawByte && CharTy->isIncompleteType()) { 7431 Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) << CharTy; 7432 return false; 7433 } 7434 // Give up on byte-oriented matching against multibyte elements. 7435 // FIXME: We can compare the bytes in the correct order. 7436 if (IsRawByte && Info.Ctx.getTypeSizeInChars(CharTy) != CharUnits::One()) 7437 return false; 7438 // Figure out what value we're actually looking for (after converting to 7439 // the corresponding unsigned type if necessary). 7440 uint64_t DesiredVal; 7441 bool StopAtNull = false; 7442 switch (BuiltinOp) { 7443 case Builtin::BIstrchr: 7444 case Builtin::BI__builtin_strchr: 7445 // strchr compares directly to the passed integer, and therefore 7446 // always fails if given an int that is not a char. 7447 if (!APSInt::isSameValue(HandleIntToIntCast(Info, E, CharTy, 7448 E->getArg(1)->getType(), 7449 Desired), 7450 Desired)) 7451 return ZeroInitialization(E); 7452 StopAtNull = true; 7453 LLVM_FALLTHROUGH; 7454 case Builtin::BImemchr: 7455 case Builtin::BI__builtin_memchr: 7456 case Builtin::BI__builtin_char_memchr: 7457 // memchr compares by converting both sides to unsigned char. That's also 7458 // correct for strchr if we get this far (to cope with plain char being 7459 // unsigned in the strchr case). 7460 DesiredVal = Desired.trunc(Info.Ctx.getCharWidth()).getZExtValue(); 7461 break; 7462 7463 case Builtin::BIwcschr: 7464 case Builtin::BI__builtin_wcschr: 7465 StopAtNull = true; 7466 LLVM_FALLTHROUGH; 7467 case Builtin::BIwmemchr: 7468 case Builtin::BI__builtin_wmemchr: 7469 // wcschr and wmemchr are given a wchar_t to look for. Just use it. 7470 DesiredVal = Desired.getZExtValue(); 7471 break; 7472 } 7473 7474 for (; MaxLength; --MaxLength) { 7475 APValue Char; 7476 if (!handleLValueToRValueConversion(Info, E, CharTy, Result, Char) || 7477 !Char.isInt()) 7478 return false; 7479 if (Char.getInt().getZExtValue() == DesiredVal) 7480 return true; 7481 if (StopAtNull && !Char.getInt()) 7482 break; 7483 if (!HandleLValueArrayAdjustment(Info, E, Result, CharTy, 1)) 7484 return false; 7485 } 7486 // Not found: return nullptr. 7487 return ZeroInitialization(E); 7488 } 7489 7490 case Builtin::BImemcpy: 7491 case Builtin::BImemmove: 7492 case Builtin::BIwmemcpy: 7493 case Builtin::BIwmemmove: 7494 if (Info.getLangOpts().CPlusPlus11) 7495 Info.CCEDiag(E, diag::note_constexpr_invalid_function) 7496 << /*isConstexpr*/0 << /*isConstructor*/0 7497 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'"); 7498 else 7499 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); 7500 LLVM_FALLTHROUGH; 7501 case Builtin::BI__builtin_memcpy: 7502 case Builtin::BI__builtin_memmove: 7503 case Builtin::BI__builtin_wmemcpy: 7504 case Builtin::BI__builtin_wmemmove: { 7505 bool WChar = BuiltinOp == Builtin::BIwmemcpy || 7506 BuiltinOp == Builtin::BIwmemmove || 7507 BuiltinOp == Builtin::BI__builtin_wmemcpy || 7508 BuiltinOp == Builtin::BI__builtin_wmemmove; 7509 bool Move = BuiltinOp == Builtin::BImemmove || 7510 BuiltinOp == Builtin::BIwmemmove || 7511 BuiltinOp == Builtin::BI__builtin_memmove || 7512 BuiltinOp == Builtin::BI__builtin_wmemmove; 7513 7514 // The result of mem* is the first argument. 7515 if (!Visit(E->getArg(0))) 7516 return false; 7517 LValue Dest = Result; 7518 7519 LValue Src; 7520 if (!EvaluatePointer(E->getArg(1), Src, Info)) 7521 return false; 7522 7523 APSInt N; 7524 if (!EvaluateInteger(E->getArg(2), N, Info)) 7525 return false; 7526 assert(!N.isSigned() && "memcpy and friends take an unsigned size"); 7527 7528 // If the size is zero, we treat this as always being a valid no-op. 7529 // (Even if one of the src and dest pointers is null.) 7530 if (!N) 7531 return true; 7532 7533 // Otherwise, if either of the operands is null, we can't proceed. Don't 7534 // try to determine the type of the copied objects, because there aren't 7535 // any. 7536 if (!Src.Base || !Dest.Base) { 7537 APValue Val; 7538 (!Src.Base ? Src : Dest).moveInto(Val); 7539 Info.FFDiag(E, diag::note_constexpr_memcpy_null) 7540 << Move << WChar << !!Src.Base 7541 << Val.getAsString(Info.Ctx, E->getArg(0)->getType()); 7542 return false; 7543 } 7544 if (Src.Designator.Invalid || Dest.Designator.Invalid) 7545 return false; 7546 7547 // We require that Src and Dest are both pointers to arrays of 7548 // trivially-copyable type. (For the wide version, the designator will be 7549 // invalid if the designated object is not a wchar_t.) 7550 QualType T = Dest.Designator.getType(Info.Ctx); 7551 QualType SrcT = Src.Designator.getType(Info.Ctx); 7552 if (!Info.Ctx.hasSameUnqualifiedType(T, SrcT)) { 7553 Info.FFDiag(E, diag::note_constexpr_memcpy_type_pun) << Move << SrcT << T; 7554 return false; 7555 } 7556 if (T->isIncompleteType()) { 7557 Info.FFDiag(E, diag::note_constexpr_memcpy_incomplete_type) << Move << T; 7558 return false; 7559 } 7560 if (!T.isTriviallyCopyableType(Info.Ctx)) { 7561 Info.FFDiag(E, diag::note_constexpr_memcpy_nontrivial) << Move << T; 7562 return false; 7563 } 7564 7565 // Figure out how many T's we're copying. 7566 uint64_t TSize = Info.Ctx.getTypeSizeInChars(T).getQuantity(); 7567 if (!WChar) { 7568 uint64_t Remainder; 7569 llvm::APInt OrigN = N; 7570 llvm::APInt::udivrem(OrigN, TSize, N, Remainder); 7571 if (Remainder) { 7572 Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported) 7573 << Move << WChar << 0 << T << OrigN.toString(10, /*Signed*/false) 7574 << (unsigned)TSize; 7575 return false; 7576 } 7577 } 7578 7579 // Check that the copying will remain within the arrays, just so that we 7580 // can give a more meaningful diagnostic. This implicitly also checks that 7581 // N fits into 64 bits. 7582 uint64_t RemainingSrcSize = Src.Designator.validIndexAdjustments().second; 7583 uint64_t RemainingDestSize = Dest.Designator.validIndexAdjustments().second; 7584 if (N.ugt(RemainingSrcSize) || N.ugt(RemainingDestSize)) { 7585 Info.FFDiag(E, diag::note_constexpr_memcpy_unsupported) 7586 << Move << WChar << (N.ugt(RemainingSrcSize) ? 1 : 2) << T 7587 << N.toString(10, /*Signed*/false); 7588 return false; 7589 } 7590 uint64_t NElems = N.getZExtValue(); 7591 uint64_t NBytes = NElems * TSize; 7592 7593 // Check for overlap. 7594 int Direction = 1; 7595 if (HasSameBase(Src, Dest)) { 7596 uint64_t SrcOffset = Src.getLValueOffset().getQuantity(); 7597 uint64_t DestOffset = Dest.getLValueOffset().getQuantity(); 7598 if (DestOffset >= SrcOffset && DestOffset - SrcOffset < NBytes) { 7599 // Dest is inside the source region. 7600 if (!Move) { 7601 Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar; 7602 return false; 7603 } 7604 // For memmove and friends, copy backwards. 7605 if (!HandleLValueArrayAdjustment(Info, E, Src, T, NElems - 1) || 7606 !HandleLValueArrayAdjustment(Info, E, Dest, T, NElems - 1)) 7607 return false; 7608 Direction = -1; 7609 } else if (!Move && SrcOffset >= DestOffset && 7610 SrcOffset - DestOffset < NBytes) { 7611 // Src is inside the destination region for memcpy: invalid. 7612 Info.FFDiag(E, diag::note_constexpr_memcpy_overlap) << WChar; 7613 return false; 7614 } 7615 } 7616 7617 while (true) { 7618 APValue Val; 7619 if (!handleLValueToRValueConversion(Info, E, T, Src, Val) || 7620 !handleAssignment(Info, E, Dest, T, Val)) 7621 return false; 7622 // Do not iterate past the last element; if we're copying backwards, that 7623 // might take us off the start of the array. 7624 if (--NElems == 0) 7625 return true; 7626 if (!HandleLValueArrayAdjustment(Info, E, Src, T, Direction) || 7627 !HandleLValueArrayAdjustment(Info, E, Dest, T, Direction)) 7628 return false; 7629 } 7630 } 7631 7632 default: 7633 return visitNonBuiltinCallExpr(E); 7634 } 7635 } 7636 7637 //===----------------------------------------------------------------------===// 7638 // Member Pointer Evaluation 7639 //===----------------------------------------------------------------------===// 7640 7641 namespace { 7642 class MemberPointerExprEvaluator 7643 : public ExprEvaluatorBase<MemberPointerExprEvaluator> { 7644 MemberPtr &Result; 7645 7646 bool Success(const ValueDecl *D) { 7647 Result = MemberPtr(D); 7648 return true; 7649 } 7650 public: 7651 7652 MemberPointerExprEvaluator(EvalInfo &Info, MemberPtr &Result) 7653 : ExprEvaluatorBaseTy(Info), Result(Result) {} 7654 7655 bool Success(const APValue &V, const Expr *E) { 7656 Result.setFrom(V); 7657 return true; 7658 } 7659 bool ZeroInitialization(const Expr *E) { 7660 return Success((const ValueDecl*)nullptr); 7661 } 7662 7663 bool VisitCastExpr(const CastExpr *E); 7664 bool VisitUnaryAddrOf(const UnaryOperator *E); 7665 }; 7666 } // end anonymous namespace 7667 7668 static bool EvaluateMemberPointer(const Expr *E, MemberPtr &Result, 7669 EvalInfo &Info) { 7670 assert(E->isRValue() && E->getType()->isMemberPointerType()); 7671 return MemberPointerExprEvaluator(Info, Result).Visit(E); 7672 } 7673 7674 bool MemberPointerExprEvaluator::VisitCastExpr(const CastExpr *E) { 7675 switch (E->getCastKind()) { 7676 default: 7677 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7678 7679 case CK_NullToMemberPointer: 7680 VisitIgnoredValue(E->getSubExpr()); 7681 return ZeroInitialization(E); 7682 7683 case CK_BaseToDerivedMemberPointer: { 7684 if (!Visit(E->getSubExpr())) 7685 return false; 7686 if (E->path_empty()) 7687 return true; 7688 // Base-to-derived member pointer casts store the path in derived-to-base 7689 // order, so iterate backwards. The CXXBaseSpecifier also provides us with 7690 // the wrong end of the derived->base arc, so stagger the path by one class. 7691 typedef std::reverse_iterator<CastExpr::path_const_iterator> ReverseIter; 7692 for (ReverseIter PathI(E->path_end() - 1), PathE(E->path_begin()); 7693 PathI != PathE; ++PathI) { 7694 assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); 7695 const CXXRecordDecl *Derived = (*PathI)->getType()->getAsCXXRecordDecl(); 7696 if (!Result.castToDerived(Derived)) 7697 return Error(E); 7698 } 7699 const Type *FinalTy = E->getType()->castAs<MemberPointerType>()->getClass(); 7700 if (!Result.castToDerived(FinalTy->getAsCXXRecordDecl())) 7701 return Error(E); 7702 return true; 7703 } 7704 7705 case CK_DerivedToBaseMemberPointer: 7706 if (!Visit(E->getSubExpr())) 7707 return false; 7708 for (CastExpr::path_const_iterator PathI = E->path_begin(), 7709 PathE = E->path_end(); PathI != PathE; ++PathI) { 7710 assert(!(*PathI)->isVirtual() && "memptr cast through vbase"); 7711 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); 7712 if (!Result.castToBase(Base)) 7713 return Error(E); 7714 } 7715 return true; 7716 } 7717 } 7718 7719 bool MemberPointerExprEvaluator::VisitUnaryAddrOf(const UnaryOperator *E) { 7720 // C++11 [expr.unary.op]p3 has very strict rules on how the address of a 7721 // member can be formed. 7722 return Success(cast<DeclRefExpr>(E->getSubExpr())->getDecl()); 7723 } 7724 7725 //===----------------------------------------------------------------------===// 7726 // Record Evaluation 7727 //===----------------------------------------------------------------------===// 7728 7729 namespace { 7730 class RecordExprEvaluator 7731 : public ExprEvaluatorBase<RecordExprEvaluator> { 7732 const LValue &This; 7733 APValue &Result; 7734 public: 7735 7736 RecordExprEvaluator(EvalInfo &info, const LValue &This, APValue &Result) 7737 : ExprEvaluatorBaseTy(info), This(This), Result(Result) {} 7738 7739 bool Success(const APValue &V, const Expr *E) { 7740 Result = V; 7741 return true; 7742 } 7743 bool ZeroInitialization(const Expr *E) { 7744 return ZeroInitialization(E, E->getType()); 7745 } 7746 bool ZeroInitialization(const Expr *E, QualType T); 7747 7748 bool VisitCallExpr(const CallExpr *E) { 7749 return handleCallExpr(E, Result, &This); 7750 } 7751 bool VisitCastExpr(const CastExpr *E); 7752 bool VisitInitListExpr(const InitListExpr *E); 7753 bool VisitCXXConstructExpr(const CXXConstructExpr *E) { 7754 return VisitCXXConstructExpr(E, E->getType()); 7755 } 7756 bool VisitLambdaExpr(const LambdaExpr *E); 7757 bool VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E); 7758 bool VisitCXXConstructExpr(const CXXConstructExpr *E, QualType T); 7759 bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E); 7760 7761 bool VisitBinCmp(const BinaryOperator *E); 7762 }; 7763 } 7764 7765 /// Perform zero-initialization on an object of non-union class type. 7766 /// C++11 [dcl.init]p5: 7767 /// To zero-initialize an object or reference of type T means: 7768 /// [...] 7769 /// -- if T is a (possibly cv-qualified) non-union class type, 7770 /// each non-static data member and each base-class subobject is 7771 /// zero-initialized 7772 static bool HandleClassZeroInitialization(EvalInfo &Info, const Expr *E, 7773 const RecordDecl *RD, 7774 const LValue &This, APValue &Result) { 7775 assert(!RD->isUnion() && "Expected non-union class type"); 7776 const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD); 7777 Result = APValue(APValue::UninitStruct(), CD ? CD->getNumBases() : 0, 7778 std::distance(RD->field_begin(), RD->field_end())); 7779 7780 if (RD->isInvalidDecl()) return false; 7781 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 7782 7783 if (CD) { 7784 unsigned Index = 0; 7785 for (CXXRecordDecl::base_class_const_iterator I = CD->bases_begin(), 7786 End = CD->bases_end(); I != End; ++I, ++Index) { 7787 const CXXRecordDecl *Base = I->getType()->getAsCXXRecordDecl(); 7788 LValue Subobject = This; 7789 if (!HandleLValueDirectBase(Info, E, Subobject, CD, Base, &Layout)) 7790 return false; 7791 if (!HandleClassZeroInitialization(Info, E, Base, Subobject, 7792 Result.getStructBase(Index))) 7793 return false; 7794 } 7795 } 7796 7797 for (const auto *I : RD->fields()) { 7798 // -- if T is a reference type, no initialization is performed. 7799 if (I->getType()->isReferenceType()) 7800 continue; 7801 7802 LValue Subobject = This; 7803 if (!HandleLValueMember(Info, E, Subobject, I, &Layout)) 7804 return false; 7805 7806 ImplicitValueInitExpr VIE(I->getType()); 7807 if (!EvaluateInPlace( 7808 Result.getStructField(I->getFieldIndex()), Info, Subobject, &VIE)) 7809 return false; 7810 } 7811 7812 return true; 7813 } 7814 7815 bool RecordExprEvaluator::ZeroInitialization(const Expr *E, QualType T) { 7816 const RecordDecl *RD = T->castAs<RecordType>()->getDecl(); 7817 if (RD->isInvalidDecl()) return false; 7818 if (RD->isUnion()) { 7819 // C++11 [dcl.init]p5: If T is a (possibly cv-qualified) union type, the 7820 // object's first non-static named data member is zero-initialized 7821 RecordDecl::field_iterator I = RD->field_begin(); 7822 if (I == RD->field_end()) { 7823 Result = APValue((const FieldDecl*)nullptr); 7824 return true; 7825 } 7826 7827 LValue Subobject = This; 7828 if (!HandleLValueMember(Info, E, Subobject, *I)) 7829 return false; 7830 Result = APValue(*I); 7831 ImplicitValueInitExpr VIE(I->getType()); 7832 return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, &VIE); 7833 } 7834 7835 if (isa<CXXRecordDecl>(RD) && cast<CXXRecordDecl>(RD)->getNumVBases()) { 7836 Info.FFDiag(E, diag::note_constexpr_virtual_base) << RD; 7837 return false; 7838 } 7839 7840 return HandleClassZeroInitialization(Info, E, RD, This, Result); 7841 } 7842 7843 bool RecordExprEvaluator::VisitCastExpr(const CastExpr *E) { 7844 switch (E->getCastKind()) { 7845 default: 7846 return ExprEvaluatorBaseTy::VisitCastExpr(E); 7847 7848 case CK_ConstructorConversion: 7849 return Visit(E->getSubExpr()); 7850 7851 case CK_DerivedToBase: 7852 case CK_UncheckedDerivedToBase: { 7853 APValue DerivedObject; 7854 if (!Evaluate(DerivedObject, Info, E->getSubExpr())) 7855 return false; 7856 if (!DerivedObject.isStruct()) 7857 return Error(E->getSubExpr()); 7858 7859 // Derived-to-base rvalue conversion: just slice off the derived part. 7860 APValue *Value = &DerivedObject; 7861 const CXXRecordDecl *RD = E->getSubExpr()->getType()->getAsCXXRecordDecl(); 7862 for (CastExpr::path_const_iterator PathI = E->path_begin(), 7863 PathE = E->path_end(); PathI != PathE; ++PathI) { 7864 assert(!(*PathI)->isVirtual() && "record rvalue with virtual base"); 7865 const CXXRecordDecl *Base = (*PathI)->getType()->getAsCXXRecordDecl(); 7866 Value = &Value->getStructBase(getBaseIndex(RD, Base)); 7867 RD = Base; 7868 } 7869 Result = *Value; 7870 return true; 7871 } 7872 } 7873 } 7874 7875 bool RecordExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 7876 if (E->isTransparent()) 7877 return Visit(E->getInit(0)); 7878 7879 const RecordDecl *RD = E->getType()->castAs<RecordType>()->getDecl(); 7880 if (RD->isInvalidDecl()) return false; 7881 const ASTRecordLayout &Layout = Info.Ctx.getASTRecordLayout(RD); 7882 auto *CXXRD = dyn_cast<CXXRecordDecl>(RD); 7883 7884 EvalInfo::EvaluatingConstructorRAII EvalObj( 7885 Info, 7886 ObjectUnderConstruction{This.getLValueBase(), This.Designator.Entries}, 7887 CXXRD && CXXRD->getNumBases()); 7888 7889 if (RD->isUnion()) { 7890 const FieldDecl *Field = E->getInitializedFieldInUnion(); 7891 Result = APValue(Field); 7892 if (!Field) 7893 return true; 7894 7895 // If the initializer list for a union does not contain any elements, the 7896 // first element of the union is value-initialized. 7897 // FIXME: The element should be initialized from an initializer list. 7898 // Is this difference ever observable for initializer lists which 7899 // we don't build? 7900 ImplicitValueInitExpr VIE(Field->getType()); 7901 const Expr *InitExpr = E->getNumInits() ? E->getInit(0) : &VIE; 7902 7903 LValue Subobject = This; 7904 if (!HandleLValueMember(Info, InitExpr, Subobject, Field, &Layout)) 7905 return false; 7906 7907 // Temporarily override This, in case there's a CXXDefaultInitExpr in here. 7908 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, 7909 isa<CXXDefaultInitExpr>(InitExpr)); 7910 7911 return EvaluateInPlace(Result.getUnionValue(), Info, Subobject, InitExpr); 7912 } 7913 7914 if (!Result.hasValue()) 7915 Result = APValue(APValue::UninitStruct(), CXXRD ? CXXRD->getNumBases() : 0, 7916 std::distance(RD->field_begin(), RD->field_end())); 7917 unsigned ElementNo = 0; 7918 bool Success = true; 7919 7920 // Initialize base classes. 7921 if (CXXRD && CXXRD->getNumBases()) { 7922 for (const auto &Base : CXXRD->bases()) { 7923 assert(ElementNo < E->getNumInits() && "missing init for base class"); 7924 const Expr *Init = E->getInit(ElementNo); 7925 7926 LValue Subobject = This; 7927 if (!HandleLValueBase(Info, Init, Subobject, CXXRD, &Base)) 7928 return false; 7929 7930 APValue &FieldVal = Result.getStructBase(ElementNo); 7931 if (!EvaluateInPlace(FieldVal, Info, Subobject, Init)) { 7932 if (!Info.noteFailure()) 7933 return false; 7934 Success = false; 7935 } 7936 ++ElementNo; 7937 } 7938 7939 EvalObj.finishedConstructingBases(); 7940 } 7941 7942 // Initialize members. 7943 for (const auto *Field : RD->fields()) { 7944 // Anonymous bit-fields are not considered members of the class for 7945 // purposes of aggregate initialization. 7946 if (Field->isUnnamedBitfield()) 7947 continue; 7948 7949 LValue Subobject = This; 7950 7951 bool HaveInit = ElementNo < E->getNumInits(); 7952 7953 // FIXME: Diagnostics here should point to the end of the initializer 7954 // list, not the start. 7955 if (!HandleLValueMember(Info, HaveInit ? E->getInit(ElementNo) : E, 7956 Subobject, Field, &Layout)) 7957 return false; 7958 7959 // Perform an implicit value-initialization for members beyond the end of 7960 // the initializer list. 7961 ImplicitValueInitExpr VIE(HaveInit ? Info.Ctx.IntTy : Field->getType()); 7962 const Expr *Init = HaveInit ? E->getInit(ElementNo++) : &VIE; 7963 7964 // Temporarily override This, in case there's a CXXDefaultInitExpr in here. 7965 ThisOverrideRAII ThisOverride(*Info.CurrentCall, &This, 7966 isa<CXXDefaultInitExpr>(Init)); 7967 7968 APValue &FieldVal = Result.getStructField(Field->getFieldIndex()); 7969 if (!EvaluateInPlace(FieldVal, Info, Subobject, Init) || 7970 (Field->isBitField() && !truncateBitfieldValue(Info, Init, 7971 FieldVal, Field))) { 7972 if (!Info.noteFailure()) 7973 return false; 7974 Success = false; 7975 } 7976 } 7977 7978 return Success; 7979 } 7980 7981 bool RecordExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E, 7982 QualType T) { 7983 // Note that E's type is not necessarily the type of our class here; we might 7984 // be initializing an array element instead. 7985 const CXXConstructorDecl *FD = E->getConstructor(); 7986 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) return false; 7987 7988 bool ZeroInit = E->requiresZeroInitialization(); 7989 if (CheckTrivialDefaultConstructor(Info, E->getExprLoc(), FD, ZeroInit)) { 7990 // If we've already performed zero-initialization, we're already done. 7991 if (Result.hasValue()) 7992 return true; 7993 7994 // We can get here in two different ways: 7995 // 1) We're performing value-initialization, and should zero-initialize 7996 // the object, or 7997 // 2) We're performing default-initialization of an object with a trivial 7998 // constexpr default constructor, in which case we should start the 7999 // lifetimes of all the base subobjects (there can be no data member 8000 // subobjects in this case) per [basic.life]p1. 8001 // Either way, ZeroInitialization is appropriate. 8002 return ZeroInitialization(E, T); 8003 } 8004 8005 const FunctionDecl *Definition = nullptr; 8006 auto Body = FD->getBody(Definition); 8007 8008 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body)) 8009 return false; 8010 8011 // Avoid materializing a temporary for an elidable copy/move constructor. 8012 if (E->isElidable() && !ZeroInit) 8013 if (const MaterializeTemporaryExpr *ME 8014 = dyn_cast<MaterializeTemporaryExpr>(E->getArg(0))) 8015 return Visit(ME->GetTemporaryExpr()); 8016 8017 if (ZeroInit && !ZeroInitialization(E, T)) 8018 return false; 8019 8020 auto Args = llvm::makeArrayRef(E->getArgs(), E->getNumArgs()); 8021 return HandleConstructorCall(E, This, Args, 8022 cast<CXXConstructorDecl>(Definition), Info, 8023 Result); 8024 } 8025 8026 bool RecordExprEvaluator::VisitCXXInheritedCtorInitExpr( 8027 const CXXInheritedCtorInitExpr *E) { 8028 if (!Info.CurrentCall) { 8029 assert(Info.checkingPotentialConstantExpression()); 8030 return false; 8031 } 8032 8033 const CXXConstructorDecl *FD = E->getConstructor(); 8034 if (FD->isInvalidDecl() || FD->getParent()->isInvalidDecl()) 8035 return false; 8036 8037 const FunctionDecl *Definition = nullptr; 8038 auto Body = FD->getBody(Definition); 8039 8040 if (!CheckConstexprFunction(Info, E->getExprLoc(), FD, Definition, Body)) 8041 return false; 8042 8043 return HandleConstructorCall(E, This, Info.CurrentCall->Arguments, 8044 cast<CXXConstructorDecl>(Definition), Info, 8045 Result); 8046 } 8047 8048 bool RecordExprEvaluator::VisitCXXStdInitializerListExpr( 8049 const CXXStdInitializerListExpr *E) { 8050 const ConstantArrayType *ArrayType = 8051 Info.Ctx.getAsConstantArrayType(E->getSubExpr()->getType()); 8052 8053 LValue Array; 8054 if (!EvaluateLValue(E->getSubExpr(), Array, Info)) 8055 return false; 8056 8057 // Get a pointer to the first element of the array. 8058 Array.addArray(Info, E, ArrayType); 8059 8060 // FIXME: Perform the checks on the field types in SemaInit. 8061 RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl(); 8062 RecordDecl::field_iterator Field = Record->field_begin(); 8063 if (Field == Record->field_end()) 8064 return Error(E); 8065 8066 // Start pointer. 8067 if (!Field->getType()->isPointerType() || 8068 !Info.Ctx.hasSameType(Field->getType()->getPointeeType(), 8069 ArrayType->getElementType())) 8070 return Error(E); 8071 8072 // FIXME: What if the initializer_list type has base classes, etc? 8073 Result = APValue(APValue::UninitStruct(), 0, 2); 8074 Array.moveInto(Result.getStructField(0)); 8075 8076 if (++Field == Record->field_end()) 8077 return Error(E); 8078 8079 if (Field->getType()->isPointerType() && 8080 Info.Ctx.hasSameType(Field->getType()->getPointeeType(), 8081 ArrayType->getElementType())) { 8082 // End pointer. 8083 if (!HandleLValueArrayAdjustment(Info, E, Array, 8084 ArrayType->getElementType(), 8085 ArrayType->getSize().getZExtValue())) 8086 return false; 8087 Array.moveInto(Result.getStructField(1)); 8088 } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType())) 8089 // Length. 8090 Result.getStructField(1) = APValue(APSInt(ArrayType->getSize())); 8091 else 8092 return Error(E); 8093 8094 if (++Field != Record->field_end()) 8095 return Error(E); 8096 8097 return true; 8098 } 8099 8100 bool RecordExprEvaluator::VisitLambdaExpr(const LambdaExpr *E) { 8101 const CXXRecordDecl *ClosureClass = E->getLambdaClass(); 8102 if (ClosureClass->isInvalidDecl()) return false; 8103 8104 if (Info.checkingPotentialConstantExpression()) return true; 8105 8106 const size_t NumFields = 8107 std::distance(ClosureClass->field_begin(), ClosureClass->field_end()); 8108 8109 assert(NumFields == (size_t)std::distance(E->capture_init_begin(), 8110 E->capture_init_end()) && 8111 "The number of lambda capture initializers should equal the number of " 8112 "fields within the closure type"); 8113 8114 Result = APValue(APValue::UninitStruct(), /*NumBases*/0, NumFields); 8115 // Iterate through all the lambda's closure object's fields and initialize 8116 // them. 8117 auto *CaptureInitIt = E->capture_init_begin(); 8118 const LambdaCapture *CaptureIt = ClosureClass->captures_begin(); 8119 bool Success = true; 8120 for (const auto *Field : ClosureClass->fields()) { 8121 assert(CaptureInitIt != E->capture_init_end()); 8122 // Get the initializer for this field 8123 Expr *const CurFieldInit = *CaptureInitIt++; 8124 8125 // If there is no initializer, either this is a VLA or an error has 8126 // occurred. 8127 if (!CurFieldInit) 8128 return Error(E); 8129 8130 APValue &FieldVal = Result.getStructField(Field->getFieldIndex()); 8131 if (!EvaluateInPlace(FieldVal, Info, This, CurFieldInit)) { 8132 if (!Info.keepEvaluatingAfterFailure()) 8133 return false; 8134 Success = false; 8135 } 8136 ++CaptureIt; 8137 } 8138 return Success; 8139 } 8140 8141 static bool EvaluateRecord(const Expr *E, const LValue &This, 8142 APValue &Result, EvalInfo &Info) { 8143 assert(E->isRValue() && E->getType()->isRecordType() && 8144 "can't evaluate expression as a record rvalue"); 8145 return RecordExprEvaluator(Info, This, Result).Visit(E); 8146 } 8147 8148 //===----------------------------------------------------------------------===// 8149 // Temporary Evaluation 8150 // 8151 // Temporaries are represented in the AST as rvalues, but generally behave like 8152 // lvalues. The full-object of which the temporary is a subobject is implicitly 8153 // materialized so that a reference can bind to it. 8154 //===----------------------------------------------------------------------===// 8155 namespace { 8156 class TemporaryExprEvaluator 8157 : public LValueExprEvaluatorBase<TemporaryExprEvaluator> { 8158 public: 8159 TemporaryExprEvaluator(EvalInfo &Info, LValue &Result) : 8160 LValueExprEvaluatorBaseTy(Info, Result, false) {} 8161 8162 /// Visit an expression which constructs the value of this temporary. 8163 bool VisitConstructExpr(const Expr *E) { 8164 APValue &Value = createTemporary(E, false, Result, *Info.CurrentCall); 8165 return EvaluateInPlace(Value, Info, Result, E); 8166 } 8167 8168 bool VisitCastExpr(const CastExpr *E) { 8169 switch (E->getCastKind()) { 8170 default: 8171 return LValueExprEvaluatorBaseTy::VisitCastExpr(E); 8172 8173 case CK_ConstructorConversion: 8174 return VisitConstructExpr(E->getSubExpr()); 8175 } 8176 } 8177 bool VisitInitListExpr(const InitListExpr *E) { 8178 return VisitConstructExpr(E); 8179 } 8180 bool VisitCXXConstructExpr(const CXXConstructExpr *E) { 8181 return VisitConstructExpr(E); 8182 } 8183 bool VisitCallExpr(const CallExpr *E) { 8184 return VisitConstructExpr(E); 8185 } 8186 bool VisitCXXStdInitializerListExpr(const CXXStdInitializerListExpr *E) { 8187 return VisitConstructExpr(E); 8188 } 8189 bool VisitLambdaExpr(const LambdaExpr *E) { 8190 return VisitConstructExpr(E); 8191 } 8192 }; 8193 } // end anonymous namespace 8194 8195 /// Evaluate an expression of record type as a temporary. 8196 static bool EvaluateTemporary(const Expr *E, LValue &Result, EvalInfo &Info) { 8197 assert(E->isRValue() && E->getType()->isRecordType()); 8198 return TemporaryExprEvaluator(Info, Result).Visit(E); 8199 } 8200 8201 //===----------------------------------------------------------------------===// 8202 // Vector Evaluation 8203 //===----------------------------------------------------------------------===// 8204 8205 namespace { 8206 class VectorExprEvaluator 8207 : public ExprEvaluatorBase<VectorExprEvaluator> { 8208 APValue &Result; 8209 public: 8210 8211 VectorExprEvaluator(EvalInfo &info, APValue &Result) 8212 : ExprEvaluatorBaseTy(info), Result(Result) {} 8213 8214 bool Success(ArrayRef<APValue> V, const Expr *E) { 8215 assert(V.size() == E->getType()->castAs<VectorType>()->getNumElements()); 8216 // FIXME: remove this APValue copy. 8217 Result = APValue(V.data(), V.size()); 8218 return true; 8219 } 8220 bool Success(const APValue &V, const Expr *E) { 8221 assert(V.isVector()); 8222 Result = V; 8223 return true; 8224 } 8225 bool ZeroInitialization(const Expr *E); 8226 8227 bool VisitUnaryReal(const UnaryOperator *E) 8228 { return Visit(E->getSubExpr()); } 8229 bool VisitCastExpr(const CastExpr* E); 8230 bool VisitInitListExpr(const InitListExpr *E); 8231 bool VisitUnaryImag(const UnaryOperator *E); 8232 // FIXME: Missing: unary -, unary ~, binary add/sub/mul/div, 8233 // binary comparisons, binary and/or/xor, 8234 // shufflevector, ExtVectorElementExpr 8235 }; 8236 } // end anonymous namespace 8237 8238 static bool EvaluateVector(const Expr* E, APValue& Result, EvalInfo &Info) { 8239 assert(E->isRValue() && E->getType()->isVectorType() &&"not a vector rvalue"); 8240 return VectorExprEvaluator(Info, Result).Visit(E); 8241 } 8242 8243 bool VectorExprEvaluator::VisitCastExpr(const CastExpr *E) { 8244 const VectorType *VTy = E->getType()->castAs<VectorType>(); 8245 unsigned NElts = VTy->getNumElements(); 8246 8247 const Expr *SE = E->getSubExpr(); 8248 QualType SETy = SE->getType(); 8249 8250 switch (E->getCastKind()) { 8251 case CK_VectorSplat: { 8252 APValue Val = APValue(); 8253 if (SETy->isIntegerType()) { 8254 APSInt IntResult; 8255 if (!EvaluateInteger(SE, IntResult, Info)) 8256 return false; 8257 Val = APValue(std::move(IntResult)); 8258 } else if (SETy->isRealFloatingType()) { 8259 APFloat FloatResult(0.0); 8260 if (!EvaluateFloat(SE, FloatResult, Info)) 8261 return false; 8262 Val = APValue(std::move(FloatResult)); 8263 } else { 8264 return Error(E); 8265 } 8266 8267 // Splat and create vector APValue. 8268 SmallVector<APValue, 4> Elts(NElts, Val); 8269 return Success(Elts, E); 8270 } 8271 case CK_BitCast: { 8272 // Evaluate the operand into an APInt we can extract from. 8273 llvm::APInt SValInt; 8274 if (!EvalAndBitcastToAPInt(Info, SE, SValInt)) 8275 return false; 8276 // Extract the elements 8277 QualType EltTy = VTy->getElementType(); 8278 unsigned EltSize = Info.Ctx.getTypeSize(EltTy); 8279 bool BigEndian = Info.Ctx.getTargetInfo().isBigEndian(); 8280 SmallVector<APValue, 4> Elts; 8281 if (EltTy->isRealFloatingType()) { 8282 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(EltTy); 8283 unsigned FloatEltSize = EltSize; 8284 if (&Sem == &APFloat::x87DoubleExtended()) 8285 FloatEltSize = 80; 8286 for (unsigned i = 0; i < NElts; i++) { 8287 llvm::APInt Elt; 8288 if (BigEndian) 8289 Elt = SValInt.rotl(i*EltSize+FloatEltSize).trunc(FloatEltSize); 8290 else 8291 Elt = SValInt.rotr(i*EltSize).trunc(FloatEltSize); 8292 Elts.push_back(APValue(APFloat(Sem, Elt))); 8293 } 8294 } else if (EltTy->isIntegerType()) { 8295 for (unsigned i = 0; i < NElts; i++) { 8296 llvm::APInt Elt; 8297 if (BigEndian) 8298 Elt = SValInt.rotl(i*EltSize+EltSize).zextOrTrunc(EltSize); 8299 else 8300 Elt = SValInt.rotr(i*EltSize).zextOrTrunc(EltSize); 8301 Elts.push_back(APValue(APSInt(Elt, EltTy->isSignedIntegerType()))); 8302 } 8303 } else { 8304 return Error(E); 8305 } 8306 return Success(Elts, E); 8307 } 8308 default: 8309 return ExprEvaluatorBaseTy::VisitCastExpr(E); 8310 } 8311 } 8312 8313 bool 8314 VectorExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 8315 const VectorType *VT = E->getType()->castAs<VectorType>(); 8316 unsigned NumInits = E->getNumInits(); 8317 unsigned NumElements = VT->getNumElements(); 8318 8319 QualType EltTy = VT->getElementType(); 8320 SmallVector<APValue, 4> Elements; 8321 8322 // The number of initializers can be less than the number of 8323 // vector elements. For OpenCL, this can be due to nested vector 8324 // initialization. For GCC compatibility, missing trailing elements 8325 // should be initialized with zeroes. 8326 unsigned CountInits = 0, CountElts = 0; 8327 while (CountElts < NumElements) { 8328 // Handle nested vector initialization. 8329 if (CountInits < NumInits 8330 && E->getInit(CountInits)->getType()->isVectorType()) { 8331 APValue v; 8332 if (!EvaluateVector(E->getInit(CountInits), v, Info)) 8333 return Error(E); 8334 unsigned vlen = v.getVectorLength(); 8335 for (unsigned j = 0; j < vlen; j++) 8336 Elements.push_back(v.getVectorElt(j)); 8337 CountElts += vlen; 8338 } else if (EltTy->isIntegerType()) { 8339 llvm::APSInt sInt(32); 8340 if (CountInits < NumInits) { 8341 if (!EvaluateInteger(E->getInit(CountInits), sInt, Info)) 8342 return false; 8343 } else // trailing integer zero. 8344 sInt = Info.Ctx.MakeIntValue(0, EltTy); 8345 Elements.push_back(APValue(sInt)); 8346 CountElts++; 8347 } else { 8348 llvm::APFloat f(0.0); 8349 if (CountInits < NumInits) { 8350 if (!EvaluateFloat(E->getInit(CountInits), f, Info)) 8351 return false; 8352 } else // trailing float zero. 8353 f = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy)); 8354 Elements.push_back(APValue(f)); 8355 CountElts++; 8356 } 8357 CountInits++; 8358 } 8359 return Success(Elements, E); 8360 } 8361 8362 bool 8363 VectorExprEvaluator::ZeroInitialization(const Expr *E) { 8364 const VectorType *VT = E->getType()->getAs<VectorType>(); 8365 QualType EltTy = VT->getElementType(); 8366 APValue ZeroElement; 8367 if (EltTy->isIntegerType()) 8368 ZeroElement = APValue(Info.Ctx.MakeIntValue(0, EltTy)); 8369 else 8370 ZeroElement = 8371 APValue(APFloat::getZero(Info.Ctx.getFloatTypeSemantics(EltTy))); 8372 8373 SmallVector<APValue, 4> Elements(VT->getNumElements(), ZeroElement); 8374 return Success(Elements, E); 8375 } 8376 8377 bool VectorExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 8378 VisitIgnoredValue(E->getSubExpr()); 8379 return ZeroInitialization(E); 8380 } 8381 8382 //===----------------------------------------------------------------------===// 8383 // Array Evaluation 8384 //===----------------------------------------------------------------------===// 8385 8386 namespace { 8387 class ArrayExprEvaluator 8388 : public ExprEvaluatorBase<ArrayExprEvaluator> { 8389 const LValue &This; 8390 APValue &Result; 8391 public: 8392 8393 ArrayExprEvaluator(EvalInfo &Info, const LValue &This, APValue &Result) 8394 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {} 8395 8396 bool Success(const APValue &V, const Expr *E) { 8397 assert(V.isArray() && "expected array"); 8398 Result = V; 8399 return true; 8400 } 8401 8402 bool ZeroInitialization(const Expr *E) { 8403 const ConstantArrayType *CAT = 8404 Info.Ctx.getAsConstantArrayType(E->getType()); 8405 if (!CAT) 8406 return Error(E); 8407 8408 Result = APValue(APValue::UninitArray(), 0, 8409 CAT->getSize().getZExtValue()); 8410 if (!Result.hasArrayFiller()) return true; 8411 8412 // Zero-initialize all elements. 8413 LValue Subobject = This; 8414 Subobject.addArray(Info, E, CAT); 8415 ImplicitValueInitExpr VIE(CAT->getElementType()); 8416 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, &VIE); 8417 } 8418 8419 bool VisitCallExpr(const CallExpr *E) { 8420 return handleCallExpr(E, Result, &This); 8421 } 8422 bool VisitInitListExpr(const InitListExpr *E); 8423 bool VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E); 8424 bool VisitCXXConstructExpr(const CXXConstructExpr *E); 8425 bool VisitCXXConstructExpr(const CXXConstructExpr *E, 8426 const LValue &Subobject, 8427 APValue *Value, QualType Type); 8428 bool VisitStringLiteral(const StringLiteral *E) { 8429 expandStringLiteral(Info, E, Result); 8430 return true; 8431 } 8432 }; 8433 } // end anonymous namespace 8434 8435 static bool EvaluateArray(const Expr *E, const LValue &This, 8436 APValue &Result, EvalInfo &Info) { 8437 assert(E->isRValue() && E->getType()->isArrayType() && "not an array rvalue"); 8438 return ArrayExprEvaluator(Info, This, Result).Visit(E); 8439 } 8440 8441 // Return true iff the given array filler may depend on the element index. 8442 static bool MaybeElementDependentArrayFiller(const Expr *FillerExpr) { 8443 // For now, just whitelist non-class value-initialization and initialization 8444 // lists comprised of them. 8445 if (isa<ImplicitValueInitExpr>(FillerExpr)) 8446 return false; 8447 if (const InitListExpr *ILE = dyn_cast<InitListExpr>(FillerExpr)) { 8448 for (unsigned I = 0, E = ILE->getNumInits(); I != E; ++I) { 8449 if (MaybeElementDependentArrayFiller(ILE->getInit(I))) 8450 return true; 8451 } 8452 return false; 8453 } 8454 return true; 8455 } 8456 8457 bool ArrayExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 8458 const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(E->getType()); 8459 if (!CAT) 8460 return Error(E); 8461 8462 // C++11 [dcl.init.string]p1: A char array [...] can be initialized by [...] 8463 // an appropriately-typed string literal enclosed in braces. 8464 if (E->isStringLiteralInit()) 8465 return Visit(E->getInit(0)); 8466 8467 bool Success = true; 8468 8469 assert((!Result.isArray() || Result.getArrayInitializedElts() == 0) && 8470 "zero-initialized array shouldn't have any initialized elts"); 8471 APValue Filler; 8472 if (Result.isArray() && Result.hasArrayFiller()) 8473 Filler = Result.getArrayFiller(); 8474 8475 unsigned NumEltsToInit = E->getNumInits(); 8476 unsigned NumElts = CAT->getSize().getZExtValue(); 8477 const Expr *FillerExpr = E->hasArrayFiller() ? E->getArrayFiller() : nullptr; 8478 8479 // If the initializer might depend on the array index, run it for each 8480 // array element. 8481 if (NumEltsToInit != NumElts && MaybeElementDependentArrayFiller(FillerExpr)) 8482 NumEltsToInit = NumElts; 8483 8484 LLVM_DEBUG(llvm::dbgs() << "The number of elements to initialize: " 8485 << NumEltsToInit << ".\n"); 8486 8487 Result = APValue(APValue::UninitArray(), NumEltsToInit, NumElts); 8488 8489 // If the array was previously zero-initialized, preserve the 8490 // zero-initialized values. 8491 if (Filler.hasValue()) { 8492 for (unsigned I = 0, E = Result.getArrayInitializedElts(); I != E; ++I) 8493 Result.getArrayInitializedElt(I) = Filler; 8494 if (Result.hasArrayFiller()) 8495 Result.getArrayFiller() = Filler; 8496 } 8497 8498 LValue Subobject = This; 8499 Subobject.addArray(Info, E, CAT); 8500 for (unsigned Index = 0; Index != NumEltsToInit; ++Index) { 8501 const Expr *Init = 8502 Index < E->getNumInits() ? E->getInit(Index) : FillerExpr; 8503 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index), 8504 Info, Subobject, Init) || 8505 !HandleLValueArrayAdjustment(Info, Init, Subobject, 8506 CAT->getElementType(), 1)) { 8507 if (!Info.noteFailure()) 8508 return false; 8509 Success = false; 8510 } 8511 } 8512 8513 if (!Result.hasArrayFiller()) 8514 return Success; 8515 8516 // If we get here, we have a trivial filler, which we can just evaluate 8517 // once and splat over the rest of the array elements. 8518 assert(FillerExpr && "no array filler for incomplete init list"); 8519 return EvaluateInPlace(Result.getArrayFiller(), Info, Subobject, 8520 FillerExpr) && Success; 8521 } 8522 8523 bool ArrayExprEvaluator::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E) { 8524 if (E->getCommonExpr() && 8525 !Evaluate(Info.CurrentCall->createTemporary(E->getCommonExpr(), false), 8526 Info, E->getCommonExpr()->getSourceExpr())) 8527 return false; 8528 8529 auto *CAT = cast<ConstantArrayType>(E->getType()->castAsArrayTypeUnsafe()); 8530 8531 uint64_t Elements = CAT->getSize().getZExtValue(); 8532 Result = APValue(APValue::UninitArray(), Elements, Elements); 8533 8534 LValue Subobject = This; 8535 Subobject.addArray(Info, E, CAT); 8536 8537 bool Success = true; 8538 for (EvalInfo::ArrayInitLoopIndex Index(Info); Index != Elements; ++Index) { 8539 if (!EvaluateInPlace(Result.getArrayInitializedElt(Index), 8540 Info, Subobject, E->getSubExpr()) || 8541 !HandleLValueArrayAdjustment(Info, E, Subobject, 8542 CAT->getElementType(), 1)) { 8543 if (!Info.noteFailure()) 8544 return false; 8545 Success = false; 8546 } 8547 } 8548 8549 return Success; 8550 } 8551 8552 bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E) { 8553 return VisitCXXConstructExpr(E, This, &Result, E->getType()); 8554 } 8555 8556 bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E, 8557 const LValue &Subobject, 8558 APValue *Value, 8559 QualType Type) { 8560 bool HadZeroInit = Value->hasValue(); 8561 8562 if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) { 8563 unsigned N = CAT->getSize().getZExtValue(); 8564 8565 // Preserve the array filler if we had prior zero-initialization. 8566 APValue Filler = 8567 HadZeroInit && Value->hasArrayFiller() ? Value->getArrayFiller() 8568 : APValue(); 8569 8570 *Value = APValue(APValue::UninitArray(), N, N); 8571 8572 if (HadZeroInit) 8573 for (unsigned I = 0; I != N; ++I) 8574 Value->getArrayInitializedElt(I) = Filler; 8575 8576 // Initialize the elements. 8577 LValue ArrayElt = Subobject; 8578 ArrayElt.addArray(Info, E, CAT); 8579 for (unsigned I = 0; I != N; ++I) 8580 if (!VisitCXXConstructExpr(E, ArrayElt, &Value->getArrayInitializedElt(I), 8581 CAT->getElementType()) || 8582 !HandleLValueArrayAdjustment(Info, E, ArrayElt, 8583 CAT->getElementType(), 1)) 8584 return false; 8585 8586 return true; 8587 } 8588 8589 if (!Type->isRecordType()) 8590 return Error(E); 8591 8592 return RecordExprEvaluator(Info, Subobject, *Value) 8593 .VisitCXXConstructExpr(E, Type); 8594 } 8595 8596 //===----------------------------------------------------------------------===// 8597 // Integer Evaluation 8598 // 8599 // As a GNU extension, we support casting pointers to sufficiently-wide integer 8600 // types and back in constant folding. Integer values are thus represented 8601 // either as an integer-valued APValue, or as an lvalue-valued APValue. 8602 //===----------------------------------------------------------------------===// 8603 8604 namespace { 8605 class IntExprEvaluator 8606 : public ExprEvaluatorBase<IntExprEvaluator> { 8607 APValue &Result; 8608 public: 8609 IntExprEvaluator(EvalInfo &info, APValue &result) 8610 : ExprEvaluatorBaseTy(info), Result(result) {} 8611 8612 bool Success(const llvm::APSInt &SI, const Expr *E, APValue &Result) { 8613 assert(E->getType()->isIntegralOrEnumerationType() && 8614 "Invalid evaluation result."); 8615 assert(SI.isSigned() == E->getType()->isSignedIntegerOrEnumerationType() && 8616 "Invalid evaluation result."); 8617 assert(SI.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && 8618 "Invalid evaluation result."); 8619 Result = APValue(SI); 8620 return true; 8621 } 8622 bool Success(const llvm::APSInt &SI, const Expr *E) { 8623 return Success(SI, E, Result); 8624 } 8625 8626 bool Success(const llvm::APInt &I, const Expr *E, APValue &Result) { 8627 assert(E->getType()->isIntegralOrEnumerationType() && 8628 "Invalid evaluation result."); 8629 assert(I.getBitWidth() == Info.Ctx.getIntWidth(E->getType()) && 8630 "Invalid evaluation result."); 8631 Result = APValue(APSInt(I)); 8632 Result.getInt().setIsUnsigned( 8633 E->getType()->isUnsignedIntegerOrEnumerationType()); 8634 return true; 8635 } 8636 bool Success(const llvm::APInt &I, const Expr *E) { 8637 return Success(I, E, Result); 8638 } 8639 8640 bool Success(uint64_t Value, const Expr *E, APValue &Result) { 8641 assert(E->getType()->isIntegralOrEnumerationType() && 8642 "Invalid evaluation result."); 8643 Result = APValue(Info.Ctx.MakeIntValue(Value, E->getType())); 8644 return true; 8645 } 8646 bool Success(uint64_t Value, const Expr *E) { 8647 return Success(Value, E, Result); 8648 } 8649 8650 bool Success(CharUnits Size, const Expr *E) { 8651 return Success(Size.getQuantity(), E); 8652 } 8653 8654 bool Success(const APValue &V, const Expr *E) { 8655 if (V.isLValue() || V.isAddrLabelDiff() || V.isIndeterminate()) { 8656 Result = V; 8657 return true; 8658 } 8659 return Success(V.getInt(), E); 8660 } 8661 8662 bool ZeroInitialization(const Expr *E) { return Success(0, E); } 8663 8664 //===--------------------------------------------------------------------===// 8665 // Visitor Methods 8666 //===--------------------------------------------------------------------===// 8667 8668 bool VisitConstantExpr(const ConstantExpr *E); 8669 8670 bool VisitIntegerLiteral(const IntegerLiteral *E) { 8671 return Success(E->getValue(), E); 8672 } 8673 bool VisitCharacterLiteral(const CharacterLiteral *E) { 8674 return Success(E->getValue(), E); 8675 } 8676 8677 bool CheckReferencedDecl(const Expr *E, const Decl *D); 8678 bool VisitDeclRefExpr(const DeclRefExpr *E) { 8679 if (CheckReferencedDecl(E, E->getDecl())) 8680 return true; 8681 8682 return ExprEvaluatorBaseTy::VisitDeclRefExpr(E); 8683 } 8684 bool VisitMemberExpr(const MemberExpr *E) { 8685 if (CheckReferencedDecl(E, E->getMemberDecl())) { 8686 VisitIgnoredBaseExpression(E->getBase()); 8687 return true; 8688 } 8689 8690 return ExprEvaluatorBaseTy::VisitMemberExpr(E); 8691 } 8692 8693 bool VisitCallExpr(const CallExpr *E); 8694 bool VisitBuiltinCallExpr(const CallExpr *E, unsigned BuiltinOp); 8695 bool VisitBinaryOperator(const BinaryOperator *E); 8696 bool VisitOffsetOfExpr(const OffsetOfExpr *E); 8697 bool VisitUnaryOperator(const UnaryOperator *E); 8698 8699 bool VisitCastExpr(const CastExpr* E); 8700 bool VisitUnaryExprOrTypeTraitExpr(const UnaryExprOrTypeTraitExpr *E); 8701 8702 bool VisitCXXBoolLiteralExpr(const CXXBoolLiteralExpr *E) { 8703 return Success(E->getValue(), E); 8704 } 8705 8706 bool VisitObjCBoolLiteralExpr(const ObjCBoolLiteralExpr *E) { 8707 return Success(E->getValue(), E); 8708 } 8709 8710 bool VisitArrayInitIndexExpr(const ArrayInitIndexExpr *E) { 8711 if (Info.ArrayInitIndex == uint64_t(-1)) { 8712 // We were asked to evaluate this subexpression independent of the 8713 // enclosing ArrayInitLoopExpr. We can't do that. 8714 Info.FFDiag(E); 8715 return false; 8716 } 8717 return Success(Info.ArrayInitIndex, E); 8718 } 8719 8720 // Note, GNU defines __null as an integer, not a pointer. 8721 bool VisitGNUNullExpr(const GNUNullExpr *E) { 8722 return ZeroInitialization(E); 8723 } 8724 8725 bool VisitTypeTraitExpr(const TypeTraitExpr *E) { 8726 return Success(E->getValue(), E); 8727 } 8728 8729 bool VisitArrayTypeTraitExpr(const ArrayTypeTraitExpr *E) { 8730 return Success(E->getValue(), E); 8731 } 8732 8733 bool VisitExpressionTraitExpr(const ExpressionTraitExpr *E) { 8734 return Success(E->getValue(), E); 8735 } 8736 8737 bool VisitUnaryReal(const UnaryOperator *E); 8738 bool VisitUnaryImag(const UnaryOperator *E); 8739 8740 bool VisitCXXNoexceptExpr(const CXXNoexceptExpr *E); 8741 bool VisitSizeOfPackExpr(const SizeOfPackExpr *E); 8742 bool VisitSourceLocExpr(const SourceLocExpr *E); 8743 // FIXME: Missing: array subscript of vector, member of vector 8744 }; 8745 8746 class FixedPointExprEvaluator 8747 : public ExprEvaluatorBase<FixedPointExprEvaluator> { 8748 APValue &Result; 8749 8750 public: 8751 FixedPointExprEvaluator(EvalInfo &info, APValue &result) 8752 : ExprEvaluatorBaseTy(info), Result(result) {} 8753 8754 bool Success(const llvm::APInt &I, const Expr *E) { 8755 return Success( 8756 APFixedPoint(I, Info.Ctx.getFixedPointSemantics(E->getType())), E); 8757 } 8758 8759 bool Success(uint64_t Value, const Expr *E) { 8760 return Success( 8761 APFixedPoint(Value, Info.Ctx.getFixedPointSemantics(E->getType())), E); 8762 } 8763 8764 bool Success(const APValue &V, const Expr *E) { 8765 return Success(V.getFixedPoint(), E); 8766 } 8767 8768 bool Success(const APFixedPoint &V, const Expr *E) { 8769 assert(E->getType()->isFixedPointType() && "Invalid evaluation result."); 8770 assert(V.getWidth() == Info.Ctx.getIntWidth(E->getType()) && 8771 "Invalid evaluation result."); 8772 Result = APValue(V); 8773 return true; 8774 } 8775 8776 //===--------------------------------------------------------------------===// 8777 // Visitor Methods 8778 //===--------------------------------------------------------------------===// 8779 8780 bool VisitFixedPointLiteral(const FixedPointLiteral *E) { 8781 return Success(E->getValue(), E); 8782 } 8783 8784 bool VisitCastExpr(const CastExpr *E); 8785 bool VisitUnaryOperator(const UnaryOperator *E); 8786 bool VisitBinaryOperator(const BinaryOperator *E); 8787 }; 8788 } // end anonymous namespace 8789 8790 /// EvaluateIntegerOrLValue - Evaluate an rvalue integral-typed expression, and 8791 /// produce either the integer value or a pointer. 8792 /// 8793 /// GCC has a heinous extension which folds casts between pointer types and 8794 /// pointer-sized integral types. We support this by allowing the evaluation of 8795 /// an integer rvalue to produce a pointer (represented as an lvalue) instead. 8796 /// Some simple arithmetic on such values is supported (they are treated much 8797 /// like char*). 8798 static bool EvaluateIntegerOrLValue(const Expr *E, APValue &Result, 8799 EvalInfo &Info) { 8800 assert(E->isRValue() && E->getType()->isIntegralOrEnumerationType()); 8801 return IntExprEvaluator(Info, Result).Visit(E); 8802 } 8803 8804 static bool EvaluateInteger(const Expr *E, APSInt &Result, EvalInfo &Info) { 8805 APValue Val; 8806 if (!EvaluateIntegerOrLValue(E, Val, Info)) 8807 return false; 8808 if (!Val.isInt()) { 8809 // FIXME: It would be better to produce the diagnostic for casting 8810 // a pointer to an integer. 8811 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 8812 return false; 8813 } 8814 Result = Val.getInt(); 8815 return true; 8816 } 8817 8818 bool IntExprEvaluator::VisitSourceLocExpr(const SourceLocExpr *E) { 8819 APValue Evaluated = E->EvaluateInContext( 8820 Info.Ctx, Info.CurrentCall->CurSourceLocExprScope.getDefaultExpr()); 8821 return Success(Evaluated, E); 8822 } 8823 8824 static bool EvaluateFixedPoint(const Expr *E, APFixedPoint &Result, 8825 EvalInfo &Info) { 8826 if (E->getType()->isFixedPointType()) { 8827 APValue Val; 8828 if (!FixedPointExprEvaluator(Info, Val).Visit(E)) 8829 return false; 8830 if (!Val.isFixedPoint()) 8831 return false; 8832 8833 Result = Val.getFixedPoint(); 8834 return true; 8835 } 8836 return false; 8837 } 8838 8839 static bool EvaluateFixedPointOrInteger(const Expr *E, APFixedPoint &Result, 8840 EvalInfo &Info) { 8841 if (E->getType()->isIntegerType()) { 8842 auto FXSema = Info.Ctx.getFixedPointSemantics(E->getType()); 8843 APSInt Val; 8844 if (!EvaluateInteger(E, Val, Info)) 8845 return false; 8846 Result = APFixedPoint(Val, FXSema); 8847 return true; 8848 } else if (E->getType()->isFixedPointType()) { 8849 return EvaluateFixedPoint(E, Result, Info); 8850 } 8851 return false; 8852 } 8853 8854 /// Check whether the given declaration can be directly converted to an integral 8855 /// rvalue. If not, no diagnostic is produced; there are other things we can 8856 /// try. 8857 bool IntExprEvaluator::CheckReferencedDecl(const Expr* E, const Decl* D) { 8858 // Enums are integer constant exprs. 8859 if (const EnumConstantDecl *ECD = dyn_cast<EnumConstantDecl>(D)) { 8860 // Check for signedness/width mismatches between E type and ECD value. 8861 bool SameSign = (ECD->getInitVal().isSigned() 8862 == E->getType()->isSignedIntegerOrEnumerationType()); 8863 bool SameWidth = (ECD->getInitVal().getBitWidth() 8864 == Info.Ctx.getIntWidth(E->getType())); 8865 if (SameSign && SameWidth) 8866 return Success(ECD->getInitVal(), E); 8867 else { 8868 // Get rid of mismatch (otherwise Success assertions will fail) 8869 // by computing a new value matching the type of E. 8870 llvm::APSInt Val = ECD->getInitVal(); 8871 if (!SameSign) 8872 Val.setIsSigned(!ECD->getInitVal().isSigned()); 8873 if (!SameWidth) 8874 Val = Val.extOrTrunc(Info.Ctx.getIntWidth(E->getType())); 8875 return Success(Val, E); 8876 } 8877 } 8878 return false; 8879 } 8880 8881 /// Values returned by __builtin_classify_type, chosen to match the values 8882 /// produced by GCC's builtin. 8883 enum class GCCTypeClass { 8884 None = -1, 8885 Void = 0, 8886 Integer = 1, 8887 // GCC reserves 2 for character types, but instead classifies them as 8888 // integers. 8889 Enum = 3, 8890 Bool = 4, 8891 Pointer = 5, 8892 // GCC reserves 6 for references, but appears to never use it (because 8893 // expressions never have reference type, presumably). 8894 PointerToDataMember = 7, 8895 RealFloat = 8, 8896 Complex = 9, 8897 // GCC reserves 10 for functions, but does not use it since GCC version 6 due 8898 // to decay to pointer. (Prior to version 6 it was only used in C++ mode). 8899 // GCC claims to reserve 11 for pointers to member functions, but *actually* 8900 // uses 12 for that purpose, same as for a class or struct. Maybe it 8901 // internally implements a pointer to member as a struct? Who knows. 8902 PointerToMemberFunction = 12, // Not a bug, see above. 8903 ClassOrStruct = 12, 8904 Union = 13, 8905 // GCC reserves 14 for arrays, but does not use it since GCC version 6 due to 8906 // decay to pointer. (Prior to version 6 it was only used in C++ mode). 8907 // GCC reserves 15 for strings, but actually uses 5 (pointer) for string 8908 // literals. 8909 }; 8910 8911 /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way 8912 /// as GCC. 8913 static GCCTypeClass 8914 EvaluateBuiltinClassifyType(QualType T, const LangOptions &LangOpts) { 8915 assert(!T->isDependentType() && "unexpected dependent type"); 8916 8917 QualType CanTy = T.getCanonicalType(); 8918 const BuiltinType *BT = dyn_cast<BuiltinType>(CanTy); 8919 8920 switch (CanTy->getTypeClass()) { 8921 #define TYPE(ID, BASE) 8922 #define DEPENDENT_TYPE(ID, BASE) case Type::ID: 8923 #define NON_CANONICAL_TYPE(ID, BASE) case Type::ID: 8924 #define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(ID, BASE) case Type::ID: 8925 #include "clang/AST/TypeNodes.def" 8926 case Type::Auto: 8927 case Type::DeducedTemplateSpecialization: 8928 llvm_unreachable("unexpected non-canonical or dependent type"); 8929 8930 case Type::Builtin: 8931 switch (BT->getKind()) { 8932 #define BUILTIN_TYPE(ID, SINGLETON_ID) 8933 #define SIGNED_TYPE(ID, SINGLETON_ID) \ 8934 case BuiltinType::ID: return GCCTypeClass::Integer; 8935 #define FLOATING_TYPE(ID, SINGLETON_ID) \ 8936 case BuiltinType::ID: return GCCTypeClass::RealFloat; 8937 #define PLACEHOLDER_TYPE(ID, SINGLETON_ID) \ 8938 case BuiltinType::ID: break; 8939 #include "clang/AST/BuiltinTypes.def" 8940 case BuiltinType::Void: 8941 return GCCTypeClass::Void; 8942 8943 case BuiltinType::Bool: 8944 return GCCTypeClass::Bool; 8945 8946 case BuiltinType::Char_U: 8947 case BuiltinType::UChar: 8948 case BuiltinType::WChar_U: 8949 case BuiltinType::Char8: 8950 case BuiltinType::Char16: 8951 case BuiltinType::Char32: 8952 case BuiltinType::UShort: 8953 case BuiltinType::UInt: 8954 case BuiltinType::ULong: 8955 case BuiltinType::ULongLong: 8956 case BuiltinType::UInt128: 8957 return GCCTypeClass::Integer; 8958 8959 case BuiltinType::UShortAccum: 8960 case BuiltinType::UAccum: 8961 case BuiltinType::ULongAccum: 8962 case BuiltinType::UShortFract: 8963 case BuiltinType::UFract: 8964 case BuiltinType::ULongFract: 8965 case BuiltinType::SatUShortAccum: 8966 case BuiltinType::SatUAccum: 8967 case BuiltinType::SatULongAccum: 8968 case BuiltinType::SatUShortFract: 8969 case BuiltinType::SatUFract: 8970 case BuiltinType::SatULongFract: 8971 return GCCTypeClass::None; 8972 8973 case BuiltinType::NullPtr: 8974 8975 case BuiltinType::ObjCId: 8976 case BuiltinType::ObjCClass: 8977 case BuiltinType::ObjCSel: 8978 #define IMAGE_TYPE(ImgType, Id, SingletonId, Access, Suffix) \ 8979 case BuiltinType::Id: 8980 #include "clang/Basic/OpenCLImageTypes.def" 8981 #define EXT_OPAQUE_TYPE(ExtType, Id, Ext) \ 8982 case BuiltinType::Id: 8983 #include "clang/Basic/OpenCLExtensionTypes.def" 8984 case BuiltinType::OCLSampler: 8985 case BuiltinType::OCLEvent: 8986 case BuiltinType::OCLClkEvent: 8987 case BuiltinType::OCLQueue: 8988 case BuiltinType::OCLReserveID: 8989 return GCCTypeClass::None; 8990 8991 case BuiltinType::Dependent: 8992 llvm_unreachable("unexpected dependent type"); 8993 }; 8994 llvm_unreachable("unexpected placeholder type"); 8995 8996 case Type::Enum: 8997 return LangOpts.CPlusPlus ? GCCTypeClass::Enum : GCCTypeClass::Integer; 8998 8999 case Type::Pointer: 9000 case Type::ConstantArray: 9001 case Type::VariableArray: 9002 case Type::IncompleteArray: 9003 case Type::FunctionNoProto: 9004 case Type::FunctionProto: 9005 return GCCTypeClass::Pointer; 9006 9007 case Type::MemberPointer: 9008 return CanTy->isMemberDataPointerType() 9009 ? GCCTypeClass::PointerToDataMember 9010 : GCCTypeClass::PointerToMemberFunction; 9011 9012 case Type::Complex: 9013 return GCCTypeClass::Complex; 9014 9015 case Type::Record: 9016 return CanTy->isUnionType() ? GCCTypeClass::Union 9017 : GCCTypeClass::ClassOrStruct; 9018 9019 case Type::Atomic: 9020 // GCC classifies _Atomic T the same as T. 9021 return EvaluateBuiltinClassifyType( 9022 CanTy->castAs<AtomicType>()->getValueType(), LangOpts); 9023 9024 case Type::BlockPointer: 9025 case Type::Vector: 9026 case Type::ExtVector: 9027 case Type::ObjCObject: 9028 case Type::ObjCInterface: 9029 case Type::ObjCObjectPointer: 9030 case Type::Pipe: 9031 // GCC classifies vectors as None. We follow its lead and classify all 9032 // other types that don't fit into the regular classification the same way. 9033 return GCCTypeClass::None; 9034 9035 case Type::LValueReference: 9036 case Type::RValueReference: 9037 llvm_unreachable("invalid type for expression"); 9038 } 9039 9040 llvm_unreachable("unexpected type class"); 9041 } 9042 9043 /// EvaluateBuiltinClassifyType - Evaluate __builtin_classify_type the same way 9044 /// as GCC. 9045 static GCCTypeClass 9046 EvaluateBuiltinClassifyType(const CallExpr *E, const LangOptions &LangOpts) { 9047 // If no argument was supplied, default to None. This isn't 9048 // ideal, however it is what gcc does. 9049 if (E->getNumArgs() == 0) 9050 return GCCTypeClass::None; 9051 9052 // FIXME: Bizarrely, GCC treats a call with more than one argument as not 9053 // being an ICE, but still folds it to a constant using the type of the first 9054 // argument. 9055 return EvaluateBuiltinClassifyType(E->getArg(0)->getType(), LangOpts); 9056 } 9057 9058 /// EvaluateBuiltinConstantPForLValue - Determine the result of 9059 /// __builtin_constant_p when applied to the given pointer. 9060 /// 9061 /// A pointer is only "constant" if it is null (or a pointer cast to integer) 9062 /// or it points to the first character of a string literal. 9063 static bool EvaluateBuiltinConstantPForLValue(const APValue &LV) { 9064 APValue::LValueBase Base = LV.getLValueBase(); 9065 if (Base.isNull()) { 9066 // A null base is acceptable. 9067 return true; 9068 } else if (const Expr *E = Base.dyn_cast<const Expr *>()) { 9069 if (!isa<StringLiteral>(E)) 9070 return false; 9071 return LV.getLValueOffset().isZero(); 9072 } else if (Base.is<TypeInfoLValue>()) { 9073 // Surprisingly, GCC considers __builtin_constant_p(&typeid(int)) to 9074 // evaluate to true. 9075 return true; 9076 } else { 9077 // Any other base is not constant enough for GCC. 9078 return false; 9079 } 9080 } 9081 9082 /// EvaluateBuiltinConstantP - Evaluate __builtin_constant_p as similarly to 9083 /// GCC as we can manage. 9084 static bool EvaluateBuiltinConstantP(EvalInfo &Info, const Expr *Arg) { 9085 // This evaluation is not permitted to have side-effects, so evaluate it in 9086 // a speculative evaluation context. 9087 SpeculativeEvaluationRAII SpeculativeEval(Info); 9088 9089 // Constant-folding is always enabled for the operand of __builtin_constant_p 9090 // (even when the enclosing evaluation context otherwise requires a strict 9091 // language-specific constant expression). 9092 FoldConstant Fold(Info, true); 9093 9094 QualType ArgType = Arg->getType(); 9095 9096 // __builtin_constant_p always has one operand. The rules which gcc follows 9097 // are not precisely documented, but are as follows: 9098 // 9099 // - If the operand is of integral, floating, complex or enumeration type, 9100 // and can be folded to a known value of that type, it returns 1. 9101 // - If the operand can be folded to a pointer to the first character 9102 // of a string literal (or such a pointer cast to an integral type) 9103 // or to a null pointer or an integer cast to a pointer, it returns 1. 9104 // 9105 // Otherwise, it returns 0. 9106 // 9107 // FIXME: GCC also intends to return 1 for literals of aggregate types, but 9108 // its support for this did not work prior to GCC 9 and is not yet well 9109 // understood. 9110 if (ArgType->isIntegralOrEnumerationType() || ArgType->isFloatingType() || 9111 ArgType->isAnyComplexType() || ArgType->isPointerType() || 9112 ArgType->isNullPtrType()) { 9113 APValue V; 9114 if (!::EvaluateAsRValue(Info, Arg, V)) { 9115 Fold.keepDiagnostics(); 9116 return false; 9117 } 9118 9119 // For a pointer (possibly cast to integer), there are special rules. 9120 if (V.getKind() == APValue::LValue) 9121 return EvaluateBuiltinConstantPForLValue(V); 9122 9123 // Otherwise, any constant value is good enough. 9124 return V.hasValue(); 9125 } 9126 9127 // Anything else isn't considered to be sufficiently constant. 9128 return false; 9129 } 9130 9131 /// Retrieves the "underlying object type" of the given expression, 9132 /// as used by __builtin_object_size. 9133 static QualType getObjectType(APValue::LValueBase B) { 9134 if (const ValueDecl *D = B.dyn_cast<const ValueDecl*>()) { 9135 if (const VarDecl *VD = dyn_cast<VarDecl>(D)) 9136 return VD->getType(); 9137 } else if (const Expr *E = B.get<const Expr*>()) { 9138 if (isa<CompoundLiteralExpr>(E)) 9139 return E->getType(); 9140 } else if (B.is<TypeInfoLValue>()) { 9141 return B.getTypeInfoType(); 9142 } 9143 9144 return QualType(); 9145 } 9146 9147 /// A more selective version of E->IgnoreParenCasts for 9148 /// tryEvaluateBuiltinObjectSize. This ignores some casts/parens that serve only 9149 /// to change the type of E. 9150 /// Ex. For E = `(short*)((char*)(&foo))`, returns `&foo` 9151 /// 9152 /// Always returns an RValue with a pointer representation. 9153 static const Expr *ignorePointerCastsAndParens(const Expr *E) { 9154 assert(E->isRValue() && E->getType()->hasPointerRepresentation()); 9155 9156 auto *NoParens = E->IgnoreParens(); 9157 auto *Cast = dyn_cast<CastExpr>(NoParens); 9158 if (Cast == nullptr) 9159 return NoParens; 9160 9161 // We only conservatively allow a few kinds of casts, because this code is 9162 // inherently a simple solution that seeks to support the common case. 9163 auto CastKind = Cast->getCastKind(); 9164 if (CastKind != CK_NoOp && CastKind != CK_BitCast && 9165 CastKind != CK_AddressSpaceConversion) 9166 return NoParens; 9167 9168 auto *SubExpr = Cast->getSubExpr(); 9169 if (!SubExpr->getType()->hasPointerRepresentation() || !SubExpr->isRValue()) 9170 return NoParens; 9171 return ignorePointerCastsAndParens(SubExpr); 9172 } 9173 9174 /// Checks to see if the given LValue's Designator is at the end of the LValue's 9175 /// record layout. e.g. 9176 /// struct { struct { int a, b; } fst, snd; } obj; 9177 /// obj.fst // no 9178 /// obj.snd // yes 9179 /// obj.fst.a // no 9180 /// obj.fst.b // no 9181 /// obj.snd.a // no 9182 /// obj.snd.b // yes 9183 /// 9184 /// Please note: this function is specialized for how __builtin_object_size 9185 /// views "objects". 9186 /// 9187 /// If this encounters an invalid RecordDecl or otherwise cannot determine the 9188 /// correct result, it will always return true. 9189 static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) { 9190 assert(!LVal.Designator.Invalid); 9191 9192 auto IsLastOrInvalidFieldDecl = [&Ctx](const FieldDecl *FD, bool &Invalid) { 9193 const RecordDecl *Parent = FD->getParent(); 9194 Invalid = Parent->isInvalidDecl(); 9195 if (Invalid || Parent->isUnion()) 9196 return true; 9197 const ASTRecordLayout &Layout = Ctx.getASTRecordLayout(Parent); 9198 return FD->getFieldIndex() + 1 == Layout.getFieldCount(); 9199 }; 9200 9201 auto &Base = LVal.getLValueBase(); 9202 if (auto *ME = dyn_cast_or_null<MemberExpr>(Base.dyn_cast<const Expr *>())) { 9203 if (auto *FD = dyn_cast<FieldDecl>(ME->getMemberDecl())) { 9204 bool Invalid; 9205 if (!IsLastOrInvalidFieldDecl(FD, Invalid)) 9206 return Invalid; 9207 } else if (auto *IFD = dyn_cast<IndirectFieldDecl>(ME->getMemberDecl())) { 9208 for (auto *FD : IFD->chain()) { 9209 bool Invalid; 9210 if (!IsLastOrInvalidFieldDecl(cast<FieldDecl>(FD), Invalid)) 9211 return Invalid; 9212 } 9213 } 9214 } 9215 9216 unsigned I = 0; 9217 QualType BaseType = getType(Base); 9218 if (LVal.Designator.FirstEntryIsAnUnsizedArray) { 9219 // If we don't know the array bound, conservatively assume we're looking at 9220 // the final array element. 9221 ++I; 9222 if (BaseType->isIncompleteArrayType()) 9223 BaseType = Ctx.getAsArrayType(BaseType)->getElementType(); 9224 else 9225 BaseType = BaseType->castAs<PointerType>()->getPointeeType(); 9226 } 9227 9228 for (unsigned E = LVal.Designator.Entries.size(); I != E; ++I) { 9229 const auto &Entry = LVal.Designator.Entries[I]; 9230 if (BaseType->isArrayType()) { 9231 // Because __builtin_object_size treats arrays as objects, we can ignore 9232 // the index iff this is the last array in the Designator. 9233 if (I + 1 == E) 9234 return true; 9235 const auto *CAT = cast<ConstantArrayType>(Ctx.getAsArrayType(BaseType)); 9236 uint64_t Index = Entry.getAsArrayIndex(); 9237 if (Index + 1 != CAT->getSize()) 9238 return false; 9239 BaseType = CAT->getElementType(); 9240 } else if (BaseType->isAnyComplexType()) { 9241 const auto *CT = BaseType->castAs<ComplexType>(); 9242 uint64_t Index = Entry.getAsArrayIndex(); 9243 if (Index != 1) 9244 return false; 9245 BaseType = CT->getElementType(); 9246 } else if (auto *FD = getAsField(Entry)) { 9247 bool Invalid; 9248 if (!IsLastOrInvalidFieldDecl(FD, Invalid)) 9249 return Invalid; 9250 BaseType = FD->getType(); 9251 } else { 9252 assert(getAsBaseClass(Entry) && "Expecting cast to a base class"); 9253 return false; 9254 } 9255 } 9256 return true; 9257 } 9258 9259 /// Tests to see if the LValue has a user-specified designator (that isn't 9260 /// necessarily valid). Note that this always returns 'true' if the LValue has 9261 /// an unsized array as its first designator entry, because there's currently no 9262 /// way to tell if the user typed *foo or foo[0]. 9263 static bool refersToCompleteObject(const LValue &LVal) { 9264 if (LVal.Designator.Invalid) 9265 return false; 9266 9267 if (!LVal.Designator.Entries.empty()) 9268 return LVal.Designator.isMostDerivedAnUnsizedArray(); 9269 9270 if (!LVal.InvalidBase) 9271 return true; 9272 9273 // If `E` is a MemberExpr, then the first part of the designator is hiding in 9274 // the LValueBase. 9275 const auto *E = LVal.Base.dyn_cast<const Expr *>(); 9276 return !E || !isa<MemberExpr>(E); 9277 } 9278 9279 /// Attempts to detect a user writing into a piece of memory that's impossible 9280 /// to figure out the size of by just using types. 9281 static bool isUserWritingOffTheEnd(const ASTContext &Ctx, const LValue &LVal) { 9282 const SubobjectDesignator &Designator = LVal.Designator; 9283 // Notes: 9284 // - Users can only write off of the end when we have an invalid base. Invalid 9285 // bases imply we don't know where the memory came from. 9286 // - We used to be a bit more aggressive here; we'd only be conservative if 9287 // the array at the end was flexible, or if it had 0 or 1 elements. This 9288 // broke some common standard library extensions (PR30346), but was 9289 // otherwise seemingly fine. It may be useful to reintroduce this behavior 9290 // with some sort of whitelist. OTOH, it seems that GCC is always 9291 // conservative with the last element in structs (if it's an array), so our 9292 // current behavior is more compatible than a whitelisting approach would 9293 // be. 9294 return LVal.InvalidBase && 9295 Designator.Entries.size() == Designator.MostDerivedPathLength && 9296 Designator.MostDerivedIsArrayElement && 9297 isDesignatorAtObjectEnd(Ctx, LVal); 9298 } 9299 9300 /// Converts the given APInt to CharUnits, assuming the APInt is unsigned. 9301 /// Fails if the conversion would cause loss of precision. 9302 static bool convertUnsignedAPIntToCharUnits(const llvm::APInt &Int, 9303 CharUnits &Result) { 9304 auto CharUnitsMax = std::numeric_limits<CharUnits::QuantityType>::max(); 9305 if (Int.ugt(CharUnitsMax)) 9306 return false; 9307 Result = CharUnits::fromQuantity(Int.getZExtValue()); 9308 return true; 9309 } 9310 9311 /// Helper for tryEvaluateBuiltinObjectSize -- Given an LValue, this will 9312 /// determine how many bytes exist from the beginning of the object to either 9313 /// the end of the current subobject, or the end of the object itself, depending 9314 /// on what the LValue looks like + the value of Type. 9315 /// 9316 /// If this returns false, the value of Result is undefined. 9317 static bool determineEndOffset(EvalInfo &Info, SourceLocation ExprLoc, 9318 unsigned Type, const LValue &LVal, 9319 CharUnits &EndOffset) { 9320 bool DetermineForCompleteObject = refersToCompleteObject(LVal); 9321 9322 auto CheckedHandleSizeof = [&](QualType Ty, CharUnits &Result) { 9323 if (Ty.isNull() || Ty->isIncompleteType() || Ty->isFunctionType()) 9324 return false; 9325 return HandleSizeof(Info, ExprLoc, Ty, Result); 9326 }; 9327 9328 // We want to evaluate the size of the entire object. This is a valid fallback 9329 // for when Type=1 and the designator is invalid, because we're asked for an 9330 // upper-bound. 9331 if (!(Type & 1) || LVal.Designator.Invalid || DetermineForCompleteObject) { 9332 // Type=3 wants a lower bound, so we can't fall back to this. 9333 if (Type == 3 && !DetermineForCompleteObject) 9334 return false; 9335 9336 llvm::APInt APEndOffset; 9337 if (isBaseAnAllocSizeCall(LVal.getLValueBase()) && 9338 getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset)) 9339 return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset); 9340 9341 if (LVal.InvalidBase) 9342 return false; 9343 9344 QualType BaseTy = getObjectType(LVal.getLValueBase()); 9345 return CheckedHandleSizeof(BaseTy, EndOffset); 9346 } 9347 9348 // We want to evaluate the size of a subobject. 9349 const SubobjectDesignator &Designator = LVal.Designator; 9350 9351 // The following is a moderately common idiom in C: 9352 // 9353 // struct Foo { int a; char c[1]; }; 9354 // struct Foo *F = (struct Foo *)malloc(sizeof(struct Foo) + strlen(Bar)); 9355 // strcpy(&F->c[0], Bar); 9356 // 9357 // In order to not break too much legacy code, we need to support it. 9358 if (isUserWritingOffTheEnd(Info.Ctx, LVal)) { 9359 // If we can resolve this to an alloc_size call, we can hand that back, 9360 // because we know for certain how many bytes there are to write to. 9361 llvm::APInt APEndOffset; 9362 if (isBaseAnAllocSizeCall(LVal.getLValueBase()) && 9363 getBytesReturnedByAllocSizeCall(Info.Ctx, LVal, APEndOffset)) 9364 return convertUnsignedAPIntToCharUnits(APEndOffset, EndOffset); 9365 9366 // If we cannot determine the size of the initial allocation, then we can't 9367 // given an accurate upper-bound. However, we are still able to give 9368 // conservative lower-bounds for Type=3. 9369 if (Type == 1) 9370 return false; 9371 } 9372 9373 CharUnits BytesPerElem; 9374 if (!CheckedHandleSizeof(Designator.MostDerivedType, BytesPerElem)) 9375 return false; 9376 9377 // According to the GCC documentation, we want the size of the subobject 9378 // denoted by the pointer. But that's not quite right -- what we actually 9379 // want is the size of the immediately-enclosing array, if there is one. 9380 int64_t ElemsRemaining; 9381 if (Designator.MostDerivedIsArrayElement && 9382 Designator.Entries.size() == Designator.MostDerivedPathLength) { 9383 uint64_t ArraySize = Designator.getMostDerivedArraySize(); 9384 uint64_t ArrayIndex = Designator.Entries.back().getAsArrayIndex(); 9385 ElemsRemaining = ArraySize <= ArrayIndex ? 0 : ArraySize - ArrayIndex; 9386 } else { 9387 ElemsRemaining = Designator.isOnePastTheEnd() ? 0 : 1; 9388 } 9389 9390 EndOffset = LVal.getLValueOffset() + BytesPerElem * ElemsRemaining; 9391 return true; 9392 } 9393 9394 /// Tries to evaluate the __builtin_object_size for @p E. If successful, 9395 /// returns true and stores the result in @p Size. 9396 /// 9397 /// If @p WasError is non-null, this will report whether the failure to evaluate 9398 /// is to be treated as an Error in IntExprEvaluator. 9399 static bool tryEvaluateBuiltinObjectSize(const Expr *E, unsigned Type, 9400 EvalInfo &Info, uint64_t &Size) { 9401 // Determine the denoted object. 9402 LValue LVal; 9403 { 9404 // The operand of __builtin_object_size is never evaluated for side-effects. 9405 // If there are any, but we can determine the pointed-to object anyway, then 9406 // ignore the side-effects. 9407 SpeculativeEvaluationRAII SpeculativeEval(Info); 9408 IgnoreSideEffectsRAII Fold(Info); 9409 9410 if (E->isGLValue()) { 9411 // It's possible for us to be given GLValues if we're called via 9412 // Expr::tryEvaluateObjectSize. 9413 APValue RVal; 9414 if (!EvaluateAsRValue(Info, E, RVal)) 9415 return false; 9416 LVal.setFrom(Info.Ctx, RVal); 9417 } else if (!EvaluatePointer(ignorePointerCastsAndParens(E), LVal, Info, 9418 /*InvalidBaseOK=*/true)) 9419 return false; 9420 } 9421 9422 // If we point to before the start of the object, there are no accessible 9423 // bytes. 9424 if (LVal.getLValueOffset().isNegative()) { 9425 Size = 0; 9426 return true; 9427 } 9428 9429 CharUnits EndOffset; 9430 if (!determineEndOffset(Info, E->getExprLoc(), Type, LVal, EndOffset)) 9431 return false; 9432 9433 // If we've fallen outside of the end offset, just pretend there's nothing to 9434 // write to/read from. 9435 if (EndOffset <= LVal.getLValueOffset()) 9436 Size = 0; 9437 else 9438 Size = (EndOffset - LVal.getLValueOffset()).getQuantity(); 9439 return true; 9440 } 9441 9442 bool IntExprEvaluator::VisitConstantExpr(const ConstantExpr *E) { 9443 llvm::SaveAndRestore<bool> InConstantContext(Info.InConstantContext, true); 9444 if (E->getResultAPValueKind() != APValue::None) 9445 return Success(E->getAPValueResult(), E); 9446 return ExprEvaluatorBaseTy::VisitConstantExpr(E); 9447 } 9448 9449 bool IntExprEvaluator::VisitCallExpr(const CallExpr *E) { 9450 if (unsigned BuiltinOp = E->getBuiltinCallee()) 9451 return VisitBuiltinCallExpr(E, BuiltinOp); 9452 9453 return ExprEvaluatorBaseTy::VisitCallExpr(E); 9454 } 9455 9456 bool IntExprEvaluator::VisitBuiltinCallExpr(const CallExpr *E, 9457 unsigned BuiltinOp) { 9458 switch (unsigned BuiltinOp = E->getBuiltinCallee()) { 9459 default: 9460 return ExprEvaluatorBaseTy::VisitCallExpr(E); 9461 9462 case Builtin::BI__builtin_dynamic_object_size: 9463 case Builtin::BI__builtin_object_size: { 9464 // The type was checked when we built the expression. 9465 unsigned Type = 9466 E->getArg(1)->EvaluateKnownConstInt(Info.Ctx).getZExtValue(); 9467 assert(Type <= 3 && "unexpected type"); 9468 9469 uint64_t Size; 9470 if (tryEvaluateBuiltinObjectSize(E->getArg(0), Type, Info, Size)) 9471 return Success(Size, E); 9472 9473 if (E->getArg(0)->HasSideEffects(Info.Ctx)) 9474 return Success((Type & 2) ? 0 : -1, E); 9475 9476 // Expression had no side effects, but we couldn't statically determine the 9477 // size of the referenced object. 9478 switch (Info.EvalMode) { 9479 case EvalInfo::EM_ConstantExpression: 9480 case EvalInfo::EM_ConstantFold: 9481 case EvalInfo::EM_IgnoreSideEffects: 9482 // Leave it to IR generation. 9483 return Error(E); 9484 case EvalInfo::EM_ConstantExpressionUnevaluated: 9485 // Reduce it to a constant now. 9486 return Success((Type & 2) ? 0 : -1, E); 9487 } 9488 9489 llvm_unreachable("unexpected EvalMode"); 9490 } 9491 9492 case Builtin::BI__builtin_os_log_format_buffer_size: { 9493 analyze_os_log::OSLogBufferLayout Layout; 9494 analyze_os_log::computeOSLogBufferLayout(Info.Ctx, E, Layout); 9495 return Success(Layout.size().getQuantity(), E); 9496 } 9497 9498 case Builtin::BI__builtin_bswap16: 9499 case Builtin::BI__builtin_bswap32: 9500 case Builtin::BI__builtin_bswap64: { 9501 APSInt Val; 9502 if (!EvaluateInteger(E->getArg(0), Val, Info)) 9503 return false; 9504 9505 return Success(Val.byteSwap(), E); 9506 } 9507 9508 case Builtin::BI__builtin_classify_type: 9509 return Success((int)EvaluateBuiltinClassifyType(E, Info.getLangOpts()), E); 9510 9511 case Builtin::BI__builtin_clrsb: 9512 case Builtin::BI__builtin_clrsbl: 9513 case Builtin::BI__builtin_clrsbll: { 9514 APSInt Val; 9515 if (!EvaluateInteger(E->getArg(0), Val, Info)) 9516 return false; 9517 9518 return Success(Val.getBitWidth() - Val.getMinSignedBits(), E); 9519 } 9520 9521 case Builtin::BI__builtin_clz: 9522 case Builtin::BI__builtin_clzl: 9523 case Builtin::BI__builtin_clzll: 9524 case Builtin::BI__builtin_clzs: { 9525 APSInt Val; 9526 if (!EvaluateInteger(E->getArg(0), Val, Info)) 9527 return false; 9528 if (!Val) 9529 return Error(E); 9530 9531 return Success(Val.countLeadingZeros(), E); 9532 } 9533 9534 case Builtin::BI__builtin_constant_p: { 9535 const Expr *Arg = E->getArg(0); 9536 if (EvaluateBuiltinConstantP(Info, Arg)) 9537 return Success(true, E); 9538 if (Info.InConstantContext || Arg->HasSideEffects(Info.Ctx)) { 9539 // Outside a constant context, eagerly evaluate to false in the presence 9540 // of side-effects in order to avoid -Wunsequenced false-positives in 9541 // a branch on __builtin_constant_p(expr). 9542 return Success(false, E); 9543 } 9544 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 9545 return false; 9546 } 9547 9548 case Builtin::BI__builtin_is_constant_evaluated: 9549 return Success(Info.InConstantContext, E); 9550 9551 case Builtin::BI__builtin_ctz: 9552 case Builtin::BI__builtin_ctzl: 9553 case Builtin::BI__builtin_ctzll: 9554 case Builtin::BI__builtin_ctzs: { 9555 APSInt Val; 9556 if (!EvaluateInteger(E->getArg(0), Val, Info)) 9557 return false; 9558 if (!Val) 9559 return Error(E); 9560 9561 return Success(Val.countTrailingZeros(), E); 9562 } 9563 9564 case Builtin::BI__builtin_eh_return_data_regno: { 9565 int Operand = E->getArg(0)->EvaluateKnownConstInt(Info.Ctx).getZExtValue(); 9566 Operand = Info.Ctx.getTargetInfo().getEHDataRegisterNumber(Operand); 9567 return Success(Operand, E); 9568 } 9569 9570 case Builtin::BI__builtin_expect: 9571 return Visit(E->getArg(0)); 9572 9573 case Builtin::BI__builtin_ffs: 9574 case Builtin::BI__builtin_ffsl: 9575 case Builtin::BI__builtin_ffsll: { 9576 APSInt Val; 9577 if (!EvaluateInteger(E->getArg(0), Val, Info)) 9578 return false; 9579 9580 unsigned N = Val.countTrailingZeros(); 9581 return Success(N == Val.getBitWidth() ? 0 : N + 1, E); 9582 } 9583 9584 case Builtin::BI__builtin_fpclassify: { 9585 APFloat Val(0.0); 9586 if (!EvaluateFloat(E->getArg(5), Val, Info)) 9587 return false; 9588 unsigned Arg; 9589 switch (Val.getCategory()) { 9590 case APFloat::fcNaN: Arg = 0; break; 9591 case APFloat::fcInfinity: Arg = 1; break; 9592 case APFloat::fcNormal: Arg = Val.isDenormal() ? 3 : 2; break; 9593 case APFloat::fcZero: Arg = 4; break; 9594 } 9595 return Visit(E->getArg(Arg)); 9596 } 9597 9598 case Builtin::BI__builtin_isinf_sign: { 9599 APFloat Val(0.0); 9600 return EvaluateFloat(E->getArg(0), Val, Info) && 9601 Success(Val.isInfinity() ? (Val.isNegative() ? -1 : 1) : 0, E); 9602 } 9603 9604 case Builtin::BI__builtin_isinf: { 9605 APFloat Val(0.0); 9606 return EvaluateFloat(E->getArg(0), Val, Info) && 9607 Success(Val.isInfinity() ? 1 : 0, E); 9608 } 9609 9610 case Builtin::BI__builtin_isfinite: { 9611 APFloat Val(0.0); 9612 return EvaluateFloat(E->getArg(0), Val, Info) && 9613 Success(Val.isFinite() ? 1 : 0, E); 9614 } 9615 9616 case Builtin::BI__builtin_isnan: { 9617 APFloat Val(0.0); 9618 return EvaluateFloat(E->getArg(0), Val, Info) && 9619 Success(Val.isNaN() ? 1 : 0, E); 9620 } 9621 9622 case Builtin::BI__builtin_isnormal: { 9623 APFloat Val(0.0); 9624 return EvaluateFloat(E->getArg(0), Val, Info) && 9625 Success(Val.isNormal() ? 1 : 0, E); 9626 } 9627 9628 case Builtin::BI__builtin_parity: 9629 case Builtin::BI__builtin_parityl: 9630 case Builtin::BI__builtin_parityll: { 9631 APSInt Val; 9632 if (!EvaluateInteger(E->getArg(0), Val, Info)) 9633 return false; 9634 9635 return Success(Val.countPopulation() % 2, E); 9636 } 9637 9638 case Builtin::BI__builtin_popcount: 9639 case Builtin::BI__builtin_popcountl: 9640 case Builtin::BI__builtin_popcountll: { 9641 APSInt Val; 9642 if (!EvaluateInteger(E->getArg(0), Val, Info)) 9643 return false; 9644 9645 return Success(Val.countPopulation(), E); 9646 } 9647 9648 case Builtin::BIstrlen: 9649 case Builtin::BIwcslen: 9650 // A call to strlen is not a constant expression. 9651 if (Info.getLangOpts().CPlusPlus11) 9652 Info.CCEDiag(E, diag::note_constexpr_invalid_function) 9653 << /*isConstexpr*/0 << /*isConstructor*/0 9654 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'"); 9655 else 9656 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); 9657 LLVM_FALLTHROUGH; 9658 case Builtin::BI__builtin_strlen: 9659 case Builtin::BI__builtin_wcslen: { 9660 // As an extension, we support __builtin_strlen() as a constant expression, 9661 // and support folding strlen() to a constant. 9662 LValue String; 9663 if (!EvaluatePointer(E->getArg(0), String, Info)) 9664 return false; 9665 9666 QualType CharTy = E->getArg(0)->getType()->getPointeeType(); 9667 9668 // Fast path: if it's a string literal, search the string value. 9669 if (const StringLiteral *S = dyn_cast_or_null<StringLiteral>( 9670 String.getLValueBase().dyn_cast<const Expr *>())) { 9671 // The string literal may have embedded null characters. Find the first 9672 // one and truncate there. 9673 StringRef Str = S->getBytes(); 9674 int64_t Off = String.Offset.getQuantity(); 9675 if (Off >= 0 && (uint64_t)Off <= (uint64_t)Str.size() && 9676 S->getCharByteWidth() == 1 && 9677 // FIXME: Add fast-path for wchar_t too. 9678 Info.Ctx.hasSameUnqualifiedType(CharTy, Info.Ctx.CharTy)) { 9679 Str = Str.substr(Off); 9680 9681 StringRef::size_type Pos = Str.find(0); 9682 if (Pos != StringRef::npos) 9683 Str = Str.substr(0, Pos); 9684 9685 return Success(Str.size(), E); 9686 } 9687 9688 // Fall through to slow path to issue appropriate diagnostic. 9689 } 9690 9691 // Slow path: scan the bytes of the string looking for the terminating 0. 9692 for (uint64_t Strlen = 0; /**/; ++Strlen) { 9693 APValue Char; 9694 if (!handleLValueToRValueConversion(Info, E, CharTy, String, Char) || 9695 !Char.isInt()) 9696 return false; 9697 if (!Char.getInt()) 9698 return Success(Strlen, E); 9699 if (!HandleLValueArrayAdjustment(Info, E, String, CharTy, 1)) 9700 return false; 9701 } 9702 } 9703 9704 case Builtin::BIstrcmp: 9705 case Builtin::BIwcscmp: 9706 case Builtin::BIstrncmp: 9707 case Builtin::BIwcsncmp: 9708 case Builtin::BImemcmp: 9709 case Builtin::BIbcmp: 9710 case Builtin::BIwmemcmp: 9711 // A call to strlen is not a constant expression. 9712 if (Info.getLangOpts().CPlusPlus11) 9713 Info.CCEDiag(E, diag::note_constexpr_invalid_function) 9714 << /*isConstexpr*/0 << /*isConstructor*/0 9715 << (std::string("'") + Info.Ctx.BuiltinInfo.getName(BuiltinOp) + "'"); 9716 else 9717 Info.CCEDiag(E, diag::note_invalid_subexpr_in_const_expr); 9718 LLVM_FALLTHROUGH; 9719 case Builtin::BI__builtin_strcmp: 9720 case Builtin::BI__builtin_wcscmp: 9721 case Builtin::BI__builtin_strncmp: 9722 case Builtin::BI__builtin_wcsncmp: 9723 case Builtin::BI__builtin_memcmp: 9724 case Builtin::BI__builtin_bcmp: 9725 case Builtin::BI__builtin_wmemcmp: { 9726 LValue String1, String2; 9727 if (!EvaluatePointer(E->getArg(0), String1, Info) || 9728 !EvaluatePointer(E->getArg(1), String2, Info)) 9729 return false; 9730 9731 uint64_t MaxLength = uint64_t(-1); 9732 if (BuiltinOp != Builtin::BIstrcmp && 9733 BuiltinOp != Builtin::BIwcscmp && 9734 BuiltinOp != Builtin::BI__builtin_strcmp && 9735 BuiltinOp != Builtin::BI__builtin_wcscmp) { 9736 APSInt N; 9737 if (!EvaluateInteger(E->getArg(2), N, Info)) 9738 return false; 9739 MaxLength = N.getExtValue(); 9740 } 9741 9742 // Empty substrings compare equal by definition. 9743 if (MaxLength == 0u) 9744 return Success(0, E); 9745 9746 if (!String1.checkNullPointerForFoldAccess(Info, E, AK_Read) || 9747 !String2.checkNullPointerForFoldAccess(Info, E, AK_Read) || 9748 String1.Designator.Invalid || String2.Designator.Invalid) 9749 return false; 9750 9751 QualType CharTy1 = String1.Designator.getType(Info.Ctx); 9752 QualType CharTy2 = String2.Designator.getType(Info.Ctx); 9753 9754 bool IsRawByte = BuiltinOp == Builtin::BImemcmp || 9755 BuiltinOp == Builtin::BIbcmp || 9756 BuiltinOp == Builtin::BI__builtin_memcmp || 9757 BuiltinOp == Builtin::BI__builtin_bcmp; 9758 9759 assert(IsRawByte || 9760 (Info.Ctx.hasSameUnqualifiedType( 9761 CharTy1, E->getArg(0)->getType()->getPointeeType()) && 9762 Info.Ctx.hasSameUnqualifiedType(CharTy1, CharTy2))); 9763 9764 const auto &ReadCurElems = [&](APValue &Char1, APValue &Char2) { 9765 return handleLValueToRValueConversion(Info, E, CharTy1, String1, Char1) && 9766 handleLValueToRValueConversion(Info, E, CharTy2, String2, Char2) && 9767 Char1.isInt() && Char2.isInt(); 9768 }; 9769 const auto &AdvanceElems = [&] { 9770 return HandleLValueArrayAdjustment(Info, E, String1, CharTy1, 1) && 9771 HandleLValueArrayAdjustment(Info, E, String2, CharTy2, 1); 9772 }; 9773 9774 if (IsRawByte) { 9775 uint64_t BytesRemaining = MaxLength; 9776 // Pointers to const void may point to objects of incomplete type. 9777 if (CharTy1->isIncompleteType()) { 9778 Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) << CharTy1; 9779 return false; 9780 } 9781 if (CharTy2->isIncompleteType()) { 9782 Info.FFDiag(E, diag::note_constexpr_ltor_incomplete_type) << CharTy2; 9783 return false; 9784 } 9785 uint64_t CharTy1Width{Info.Ctx.getTypeSize(CharTy1)}; 9786 CharUnits CharTy1Size = Info.Ctx.toCharUnitsFromBits(CharTy1Width); 9787 // Give up on comparing between elements with disparate widths. 9788 if (CharTy1Size != Info.Ctx.getTypeSizeInChars(CharTy2)) 9789 return false; 9790 uint64_t BytesPerElement = CharTy1Size.getQuantity(); 9791 assert(BytesRemaining && "BytesRemaining should not be zero: the " 9792 "following loop considers at least one element"); 9793 while (true) { 9794 APValue Char1, Char2; 9795 if (!ReadCurElems(Char1, Char2)) 9796 return false; 9797 // We have compatible in-memory widths, but a possible type and 9798 // (for `bool`) internal representation mismatch. 9799 // Assuming two's complement representation, including 0 for `false` and 9800 // 1 for `true`, we can check an appropriate number of elements for 9801 // equality even if they are not byte-sized. 9802 APSInt Char1InMem = Char1.getInt().extOrTrunc(CharTy1Width); 9803 APSInt Char2InMem = Char2.getInt().extOrTrunc(CharTy1Width); 9804 if (Char1InMem.ne(Char2InMem)) { 9805 // If the elements are byte-sized, then we can produce a three-way 9806 // comparison result in a straightforward manner. 9807 if (BytesPerElement == 1u) { 9808 // memcmp always compares unsigned chars. 9809 return Success(Char1InMem.ult(Char2InMem) ? -1 : 1, E); 9810 } 9811 // The result is byte-order sensitive, and we have multibyte elements. 9812 // FIXME: We can compare the remaining bytes in the correct order. 9813 return false; 9814 } 9815 if (!AdvanceElems()) 9816 return false; 9817 if (BytesRemaining <= BytesPerElement) 9818 break; 9819 BytesRemaining -= BytesPerElement; 9820 } 9821 // Enough elements are equal to account for the memcmp limit. 9822 return Success(0, E); 9823 } 9824 9825 bool StopAtNull = 9826 (BuiltinOp != Builtin::BImemcmp && BuiltinOp != Builtin::BIbcmp && 9827 BuiltinOp != Builtin::BIwmemcmp && 9828 BuiltinOp != Builtin::BI__builtin_memcmp && 9829 BuiltinOp != Builtin::BI__builtin_bcmp && 9830 BuiltinOp != Builtin::BI__builtin_wmemcmp); 9831 bool IsWide = BuiltinOp == Builtin::BIwcscmp || 9832 BuiltinOp == Builtin::BIwcsncmp || 9833 BuiltinOp == Builtin::BIwmemcmp || 9834 BuiltinOp == Builtin::BI__builtin_wcscmp || 9835 BuiltinOp == Builtin::BI__builtin_wcsncmp || 9836 BuiltinOp == Builtin::BI__builtin_wmemcmp; 9837 9838 for (; MaxLength; --MaxLength) { 9839 APValue Char1, Char2; 9840 if (!ReadCurElems(Char1, Char2)) 9841 return false; 9842 if (Char1.getInt() != Char2.getInt()) { 9843 if (IsWide) // wmemcmp compares with wchar_t signedness. 9844 return Success(Char1.getInt() < Char2.getInt() ? -1 : 1, E); 9845 // memcmp always compares unsigned chars. 9846 return Success(Char1.getInt().ult(Char2.getInt()) ? -1 : 1, E); 9847 } 9848 if (StopAtNull && !Char1.getInt()) 9849 return Success(0, E); 9850 assert(!(StopAtNull && !Char2.getInt())); 9851 if (!AdvanceElems()) 9852 return false; 9853 } 9854 // We hit the strncmp / memcmp limit. 9855 return Success(0, E); 9856 } 9857 9858 case Builtin::BI__atomic_always_lock_free: 9859 case Builtin::BI__atomic_is_lock_free: 9860 case Builtin::BI__c11_atomic_is_lock_free: { 9861 APSInt SizeVal; 9862 if (!EvaluateInteger(E->getArg(0), SizeVal, Info)) 9863 return false; 9864 9865 // For __atomic_is_lock_free(sizeof(_Atomic(T))), if the size is a power 9866 // of two less than the maximum inline atomic width, we know it is 9867 // lock-free. If the size isn't a power of two, or greater than the 9868 // maximum alignment where we promote atomics, we know it is not lock-free 9869 // (at least not in the sense of atomic_is_lock_free). Otherwise, 9870 // the answer can only be determined at runtime; for example, 16-byte 9871 // atomics have lock-free implementations on some, but not all, 9872 // x86-64 processors. 9873 9874 // Check power-of-two. 9875 CharUnits Size = CharUnits::fromQuantity(SizeVal.getZExtValue()); 9876 if (Size.isPowerOfTwo()) { 9877 // Check against inlining width. 9878 unsigned InlineWidthBits = 9879 Info.Ctx.getTargetInfo().getMaxAtomicInlineWidth(); 9880 if (Size <= Info.Ctx.toCharUnitsFromBits(InlineWidthBits)) { 9881 if (BuiltinOp == Builtin::BI__c11_atomic_is_lock_free || 9882 Size == CharUnits::One() || 9883 E->getArg(1)->isNullPointerConstant(Info.Ctx, 9884 Expr::NPC_NeverValueDependent)) 9885 // OK, we will inline appropriately-aligned operations of this size, 9886 // and _Atomic(T) is appropriately-aligned. 9887 return Success(1, E); 9888 9889 QualType PointeeType = E->getArg(1)->IgnoreImpCasts()->getType()-> 9890 castAs<PointerType>()->getPointeeType(); 9891 if (!PointeeType->isIncompleteType() && 9892 Info.Ctx.getTypeAlignInChars(PointeeType) >= Size) { 9893 // OK, we will inline operations on this object. 9894 return Success(1, E); 9895 } 9896 } 9897 } 9898 9899 // Avoid emiting call for runtime decision on PowerPC 32-bit 9900 // The lock free possibilities on this platform are covered by the lines 9901 // above and we know in advance other cases require lock 9902 if (Info.Ctx.getTargetInfo().getTriple().getArch() == llvm::Triple::ppc) { 9903 return Success(0, E); 9904 } 9905 9906 return BuiltinOp == Builtin::BI__atomic_always_lock_free ? 9907 Success(0, E) : Error(E); 9908 } 9909 case Builtin::BIomp_is_initial_device: 9910 // We can decide statically which value the runtime would return if called. 9911 return Success(Info.getLangOpts().OpenMPIsDevice ? 0 : 1, E); 9912 case Builtin::BI__builtin_add_overflow: 9913 case Builtin::BI__builtin_sub_overflow: 9914 case Builtin::BI__builtin_mul_overflow: 9915 case Builtin::BI__builtin_sadd_overflow: 9916 case Builtin::BI__builtin_uadd_overflow: 9917 case Builtin::BI__builtin_uaddl_overflow: 9918 case Builtin::BI__builtin_uaddll_overflow: 9919 case Builtin::BI__builtin_usub_overflow: 9920 case Builtin::BI__builtin_usubl_overflow: 9921 case Builtin::BI__builtin_usubll_overflow: 9922 case Builtin::BI__builtin_umul_overflow: 9923 case Builtin::BI__builtin_umull_overflow: 9924 case Builtin::BI__builtin_umulll_overflow: 9925 case Builtin::BI__builtin_saddl_overflow: 9926 case Builtin::BI__builtin_saddll_overflow: 9927 case Builtin::BI__builtin_ssub_overflow: 9928 case Builtin::BI__builtin_ssubl_overflow: 9929 case Builtin::BI__builtin_ssubll_overflow: 9930 case Builtin::BI__builtin_smul_overflow: 9931 case Builtin::BI__builtin_smull_overflow: 9932 case Builtin::BI__builtin_smulll_overflow: { 9933 LValue ResultLValue; 9934 APSInt LHS, RHS; 9935 9936 QualType ResultType = E->getArg(2)->getType()->getPointeeType(); 9937 if (!EvaluateInteger(E->getArg(0), LHS, Info) || 9938 !EvaluateInteger(E->getArg(1), RHS, Info) || 9939 !EvaluatePointer(E->getArg(2), ResultLValue, Info)) 9940 return false; 9941 9942 APSInt Result; 9943 bool DidOverflow = false; 9944 9945 // If the types don't have to match, enlarge all 3 to the largest of them. 9946 if (BuiltinOp == Builtin::BI__builtin_add_overflow || 9947 BuiltinOp == Builtin::BI__builtin_sub_overflow || 9948 BuiltinOp == Builtin::BI__builtin_mul_overflow) { 9949 bool IsSigned = LHS.isSigned() || RHS.isSigned() || 9950 ResultType->isSignedIntegerOrEnumerationType(); 9951 bool AllSigned = LHS.isSigned() && RHS.isSigned() && 9952 ResultType->isSignedIntegerOrEnumerationType(); 9953 uint64_t LHSSize = LHS.getBitWidth(); 9954 uint64_t RHSSize = RHS.getBitWidth(); 9955 uint64_t ResultSize = Info.Ctx.getTypeSize(ResultType); 9956 uint64_t MaxBits = std::max(std::max(LHSSize, RHSSize), ResultSize); 9957 9958 // Add an additional bit if the signedness isn't uniformly agreed to. We 9959 // could do this ONLY if there is a signed and an unsigned that both have 9960 // MaxBits, but the code to check that is pretty nasty. The issue will be 9961 // caught in the shrink-to-result later anyway. 9962 if (IsSigned && !AllSigned) 9963 ++MaxBits; 9964 9965 LHS = APSInt(LHS.extOrTrunc(MaxBits), !IsSigned); 9966 RHS = APSInt(RHS.extOrTrunc(MaxBits), !IsSigned); 9967 Result = APSInt(MaxBits, !IsSigned); 9968 } 9969 9970 // Find largest int. 9971 switch (BuiltinOp) { 9972 default: 9973 llvm_unreachable("Invalid value for BuiltinOp"); 9974 case Builtin::BI__builtin_add_overflow: 9975 case Builtin::BI__builtin_sadd_overflow: 9976 case Builtin::BI__builtin_saddl_overflow: 9977 case Builtin::BI__builtin_saddll_overflow: 9978 case Builtin::BI__builtin_uadd_overflow: 9979 case Builtin::BI__builtin_uaddl_overflow: 9980 case Builtin::BI__builtin_uaddll_overflow: 9981 Result = LHS.isSigned() ? LHS.sadd_ov(RHS, DidOverflow) 9982 : LHS.uadd_ov(RHS, DidOverflow); 9983 break; 9984 case Builtin::BI__builtin_sub_overflow: 9985 case Builtin::BI__builtin_ssub_overflow: 9986 case Builtin::BI__builtin_ssubl_overflow: 9987 case Builtin::BI__builtin_ssubll_overflow: 9988 case Builtin::BI__builtin_usub_overflow: 9989 case Builtin::BI__builtin_usubl_overflow: 9990 case Builtin::BI__builtin_usubll_overflow: 9991 Result = LHS.isSigned() ? LHS.ssub_ov(RHS, DidOverflow) 9992 : LHS.usub_ov(RHS, DidOverflow); 9993 break; 9994 case Builtin::BI__builtin_mul_overflow: 9995 case Builtin::BI__builtin_smul_overflow: 9996 case Builtin::BI__builtin_smull_overflow: 9997 case Builtin::BI__builtin_smulll_overflow: 9998 case Builtin::BI__builtin_umul_overflow: 9999 case Builtin::BI__builtin_umull_overflow: 10000 case Builtin::BI__builtin_umulll_overflow: 10001 Result = LHS.isSigned() ? LHS.smul_ov(RHS, DidOverflow) 10002 : LHS.umul_ov(RHS, DidOverflow); 10003 break; 10004 } 10005 10006 // In the case where multiple sizes are allowed, truncate and see if 10007 // the values are the same. 10008 if (BuiltinOp == Builtin::BI__builtin_add_overflow || 10009 BuiltinOp == Builtin::BI__builtin_sub_overflow || 10010 BuiltinOp == Builtin::BI__builtin_mul_overflow) { 10011 // APSInt doesn't have a TruncOrSelf, so we use extOrTrunc instead, 10012 // since it will give us the behavior of a TruncOrSelf in the case where 10013 // its parameter <= its size. We previously set Result to be at least the 10014 // type-size of the result, so getTypeSize(ResultType) <= Result.BitWidth 10015 // will work exactly like TruncOrSelf. 10016 APSInt Temp = Result.extOrTrunc(Info.Ctx.getTypeSize(ResultType)); 10017 Temp.setIsSigned(ResultType->isSignedIntegerOrEnumerationType()); 10018 10019 if (!APSInt::isSameValue(Temp, Result)) 10020 DidOverflow = true; 10021 Result = Temp; 10022 } 10023 10024 APValue APV{Result}; 10025 if (!handleAssignment(Info, E, ResultLValue, ResultType, APV)) 10026 return false; 10027 return Success(DidOverflow, E); 10028 } 10029 } 10030 } 10031 10032 /// Determine whether this is a pointer past the end of the complete 10033 /// object referred to by the lvalue. 10034 static bool isOnePastTheEndOfCompleteObject(const ASTContext &Ctx, 10035 const LValue &LV) { 10036 // A null pointer can be viewed as being "past the end" but we don't 10037 // choose to look at it that way here. 10038 if (!LV.getLValueBase()) 10039 return false; 10040 10041 // If the designator is valid and refers to a subobject, we're not pointing 10042 // past the end. 10043 if (!LV.getLValueDesignator().Invalid && 10044 !LV.getLValueDesignator().isOnePastTheEnd()) 10045 return false; 10046 10047 // A pointer to an incomplete type might be past-the-end if the type's size is 10048 // zero. We cannot tell because the type is incomplete. 10049 QualType Ty = getType(LV.getLValueBase()); 10050 if (Ty->isIncompleteType()) 10051 return true; 10052 10053 // We're a past-the-end pointer if we point to the byte after the object, 10054 // no matter what our type or path is. 10055 auto Size = Ctx.getTypeSizeInChars(Ty); 10056 return LV.getLValueOffset() == Size; 10057 } 10058 10059 namespace { 10060 10061 /// Data recursive integer evaluator of certain binary operators. 10062 /// 10063 /// We use a data recursive algorithm for binary operators so that we are able 10064 /// to handle extreme cases of chained binary operators without causing stack 10065 /// overflow. 10066 class DataRecursiveIntBinOpEvaluator { 10067 struct EvalResult { 10068 APValue Val; 10069 bool Failed; 10070 10071 EvalResult() : Failed(false) { } 10072 10073 void swap(EvalResult &RHS) { 10074 Val.swap(RHS.Val); 10075 Failed = RHS.Failed; 10076 RHS.Failed = false; 10077 } 10078 }; 10079 10080 struct Job { 10081 const Expr *E; 10082 EvalResult LHSResult; // meaningful only for binary operator expression. 10083 enum { AnyExprKind, BinOpKind, BinOpVisitedLHSKind } Kind; 10084 10085 Job() = default; 10086 Job(Job &&) = default; 10087 10088 void startSpeculativeEval(EvalInfo &Info) { 10089 SpecEvalRAII = SpeculativeEvaluationRAII(Info); 10090 } 10091 10092 private: 10093 SpeculativeEvaluationRAII SpecEvalRAII; 10094 }; 10095 10096 SmallVector<Job, 16> Queue; 10097 10098 IntExprEvaluator &IntEval; 10099 EvalInfo &Info; 10100 APValue &FinalResult; 10101 10102 public: 10103 DataRecursiveIntBinOpEvaluator(IntExprEvaluator &IntEval, APValue &Result) 10104 : IntEval(IntEval), Info(IntEval.getEvalInfo()), FinalResult(Result) { } 10105 10106 /// True if \param E is a binary operator that we are going to handle 10107 /// data recursively. 10108 /// We handle binary operators that are comma, logical, or that have operands 10109 /// with integral or enumeration type. 10110 static bool shouldEnqueue(const BinaryOperator *E) { 10111 return E->getOpcode() == BO_Comma || E->isLogicalOp() || 10112 (E->isRValue() && E->getType()->isIntegralOrEnumerationType() && 10113 E->getLHS()->getType()->isIntegralOrEnumerationType() && 10114 E->getRHS()->getType()->isIntegralOrEnumerationType()); 10115 } 10116 10117 bool Traverse(const BinaryOperator *E) { 10118 enqueue(E); 10119 EvalResult PrevResult; 10120 while (!Queue.empty()) 10121 process(PrevResult); 10122 10123 if (PrevResult.Failed) return false; 10124 10125 FinalResult.swap(PrevResult.Val); 10126 return true; 10127 } 10128 10129 private: 10130 bool Success(uint64_t Value, const Expr *E, APValue &Result) { 10131 return IntEval.Success(Value, E, Result); 10132 } 10133 bool Success(const APSInt &Value, const Expr *E, APValue &Result) { 10134 return IntEval.Success(Value, E, Result); 10135 } 10136 bool Error(const Expr *E) { 10137 return IntEval.Error(E); 10138 } 10139 bool Error(const Expr *E, diag::kind D) { 10140 return IntEval.Error(E, D); 10141 } 10142 10143 OptionalDiagnostic CCEDiag(const Expr *E, diag::kind D) { 10144 return Info.CCEDiag(E, D); 10145 } 10146 10147 // Returns true if visiting the RHS is necessary, false otherwise. 10148 bool VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, 10149 bool &SuppressRHSDiags); 10150 10151 bool VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, 10152 const BinaryOperator *E, APValue &Result); 10153 10154 void EvaluateExpr(const Expr *E, EvalResult &Result) { 10155 Result.Failed = !Evaluate(Result.Val, Info, E); 10156 if (Result.Failed) 10157 Result.Val = APValue(); 10158 } 10159 10160 void process(EvalResult &Result); 10161 10162 void enqueue(const Expr *E) { 10163 E = E->IgnoreParens(); 10164 Queue.resize(Queue.size()+1); 10165 Queue.back().E = E; 10166 Queue.back().Kind = Job::AnyExprKind; 10167 } 10168 }; 10169 10170 } 10171 10172 bool DataRecursiveIntBinOpEvaluator:: 10173 VisitBinOpLHSOnly(EvalResult &LHSResult, const BinaryOperator *E, 10174 bool &SuppressRHSDiags) { 10175 if (E->getOpcode() == BO_Comma) { 10176 // Ignore LHS but note if we could not evaluate it. 10177 if (LHSResult.Failed) 10178 return Info.noteSideEffect(); 10179 return true; 10180 } 10181 10182 if (E->isLogicalOp()) { 10183 bool LHSAsBool; 10184 if (!LHSResult.Failed && HandleConversionToBool(LHSResult.Val, LHSAsBool)) { 10185 // We were able to evaluate the LHS, see if we can get away with not 10186 // evaluating the RHS: 0 && X -> 0, 1 || X -> 1 10187 if (LHSAsBool == (E->getOpcode() == BO_LOr)) { 10188 Success(LHSAsBool, E, LHSResult.Val); 10189 return false; // Ignore RHS 10190 } 10191 } else { 10192 LHSResult.Failed = true; 10193 10194 // Since we weren't able to evaluate the left hand side, it 10195 // might have had side effects. 10196 if (!Info.noteSideEffect()) 10197 return false; 10198 10199 // We can't evaluate the LHS; however, sometimes the result 10200 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. 10201 // Don't ignore RHS and suppress diagnostics from this arm. 10202 SuppressRHSDiags = true; 10203 } 10204 10205 return true; 10206 } 10207 10208 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && 10209 E->getRHS()->getType()->isIntegralOrEnumerationType()); 10210 10211 if (LHSResult.Failed && !Info.noteFailure()) 10212 return false; // Ignore RHS; 10213 10214 return true; 10215 } 10216 10217 static void addOrSubLValueAsInteger(APValue &LVal, const APSInt &Index, 10218 bool IsSub) { 10219 // Compute the new offset in the appropriate width, wrapping at 64 bits. 10220 // FIXME: When compiling for a 32-bit target, we should use 32-bit 10221 // offsets. 10222 assert(!LVal.hasLValuePath() && "have designator for integer lvalue"); 10223 CharUnits &Offset = LVal.getLValueOffset(); 10224 uint64_t Offset64 = Offset.getQuantity(); 10225 uint64_t Index64 = Index.extOrTrunc(64).getZExtValue(); 10226 Offset = CharUnits::fromQuantity(IsSub ? Offset64 - Index64 10227 : Offset64 + Index64); 10228 } 10229 10230 bool DataRecursiveIntBinOpEvaluator:: 10231 VisitBinOp(const EvalResult &LHSResult, const EvalResult &RHSResult, 10232 const BinaryOperator *E, APValue &Result) { 10233 if (E->getOpcode() == BO_Comma) { 10234 if (RHSResult.Failed) 10235 return false; 10236 Result = RHSResult.Val; 10237 return true; 10238 } 10239 10240 if (E->isLogicalOp()) { 10241 bool lhsResult, rhsResult; 10242 bool LHSIsOK = HandleConversionToBool(LHSResult.Val, lhsResult); 10243 bool RHSIsOK = HandleConversionToBool(RHSResult.Val, rhsResult); 10244 10245 if (LHSIsOK) { 10246 if (RHSIsOK) { 10247 if (E->getOpcode() == BO_LOr) 10248 return Success(lhsResult || rhsResult, E, Result); 10249 else 10250 return Success(lhsResult && rhsResult, E, Result); 10251 } 10252 } else { 10253 if (RHSIsOK) { 10254 // We can't evaluate the LHS; however, sometimes the result 10255 // is determined by the RHS: X && 0 -> 0, X || 1 -> 1. 10256 if (rhsResult == (E->getOpcode() == BO_LOr)) 10257 return Success(rhsResult, E, Result); 10258 } 10259 } 10260 10261 return false; 10262 } 10263 10264 assert(E->getLHS()->getType()->isIntegralOrEnumerationType() && 10265 E->getRHS()->getType()->isIntegralOrEnumerationType()); 10266 10267 if (LHSResult.Failed || RHSResult.Failed) 10268 return false; 10269 10270 const APValue &LHSVal = LHSResult.Val; 10271 const APValue &RHSVal = RHSResult.Val; 10272 10273 // Handle cases like (unsigned long)&a + 4. 10274 if (E->isAdditiveOp() && LHSVal.isLValue() && RHSVal.isInt()) { 10275 Result = LHSVal; 10276 addOrSubLValueAsInteger(Result, RHSVal.getInt(), E->getOpcode() == BO_Sub); 10277 return true; 10278 } 10279 10280 // Handle cases like 4 + (unsigned long)&a 10281 if (E->getOpcode() == BO_Add && 10282 RHSVal.isLValue() && LHSVal.isInt()) { 10283 Result = RHSVal; 10284 addOrSubLValueAsInteger(Result, LHSVal.getInt(), /*IsSub*/false); 10285 return true; 10286 } 10287 10288 if (E->getOpcode() == BO_Sub && LHSVal.isLValue() && RHSVal.isLValue()) { 10289 // Handle (intptr_t)&&A - (intptr_t)&&B. 10290 if (!LHSVal.getLValueOffset().isZero() || 10291 !RHSVal.getLValueOffset().isZero()) 10292 return false; 10293 const Expr *LHSExpr = LHSVal.getLValueBase().dyn_cast<const Expr*>(); 10294 const Expr *RHSExpr = RHSVal.getLValueBase().dyn_cast<const Expr*>(); 10295 if (!LHSExpr || !RHSExpr) 10296 return false; 10297 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); 10298 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); 10299 if (!LHSAddrExpr || !RHSAddrExpr) 10300 return false; 10301 // Make sure both labels come from the same function. 10302 if (LHSAddrExpr->getLabel()->getDeclContext() != 10303 RHSAddrExpr->getLabel()->getDeclContext()) 10304 return false; 10305 Result = APValue(LHSAddrExpr, RHSAddrExpr); 10306 return true; 10307 } 10308 10309 // All the remaining cases expect both operands to be an integer 10310 if (!LHSVal.isInt() || !RHSVal.isInt()) 10311 return Error(E); 10312 10313 // Set up the width and signedness manually, in case it can't be deduced 10314 // from the operation we're performing. 10315 // FIXME: Don't do this in the cases where we can deduce it. 10316 APSInt Value(Info.Ctx.getIntWidth(E->getType()), 10317 E->getType()->isUnsignedIntegerOrEnumerationType()); 10318 if (!handleIntIntBinOp(Info, E, LHSVal.getInt(), E->getOpcode(), 10319 RHSVal.getInt(), Value)) 10320 return false; 10321 return Success(Value, E, Result); 10322 } 10323 10324 void DataRecursiveIntBinOpEvaluator::process(EvalResult &Result) { 10325 Job &job = Queue.back(); 10326 10327 switch (job.Kind) { 10328 case Job::AnyExprKind: { 10329 if (const BinaryOperator *Bop = dyn_cast<BinaryOperator>(job.E)) { 10330 if (shouldEnqueue(Bop)) { 10331 job.Kind = Job::BinOpKind; 10332 enqueue(Bop->getLHS()); 10333 return; 10334 } 10335 } 10336 10337 EvaluateExpr(job.E, Result); 10338 Queue.pop_back(); 10339 return; 10340 } 10341 10342 case Job::BinOpKind: { 10343 const BinaryOperator *Bop = cast<BinaryOperator>(job.E); 10344 bool SuppressRHSDiags = false; 10345 if (!VisitBinOpLHSOnly(Result, Bop, SuppressRHSDiags)) { 10346 Queue.pop_back(); 10347 return; 10348 } 10349 if (SuppressRHSDiags) 10350 job.startSpeculativeEval(Info); 10351 job.LHSResult.swap(Result); 10352 job.Kind = Job::BinOpVisitedLHSKind; 10353 enqueue(Bop->getRHS()); 10354 return; 10355 } 10356 10357 case Job::BinOpVisitedLHSKind: { 10358 const BinaryOperator *Bop = cast<BinaryOperator>(job.E); 10359 EvalResult RHS; 10360 RHS.swap(Result); 10361 Result.Failed = !VisitBinOp(job.LHSResult, RHS, Bop, Result.Val); 10362 Queue.pop_back(); 10363 return; 10364 } 10365 } 10366 10367 llvm_unreachable("Invalid Job::Kind!"); 10368 } 10369 10370 namespace { 10371 /// Used when we determine that we should fail, but can keep evaluating prior to 10372 /// noting that we had a failure. 10373 class DelayedNoteFailureRAII { 10374 EvalInfo &Info; 10375 bool NoteFailure; 10376 10377 public: 10378 DelayedNoteFailureRAII(EvalInfo &Info, bool NoteFailure = true) 10379 : Info(Info), NoteFailure(NoteFailure) {} 10380 ~DelayedNoteFailureRAII() { 10381 if (NoteFailure) { 10382 bool ContinueAfterFailure = Info.noteFailure(); 10383 (void)ContinueAfterFailure; 10384 assert(ContinueAfterFailure && 10385 "Shouldn't have kept evaluating on failure."); 10386 } 10387 } 10388 }; 10389 } 10390 10391 template <class SuccessCB, class AfterCB> 10392 static bool 10393 EvaluateComparisonBinaryOperator(EvalInfo &Info, const BinaryOperator *E, 10394 SuccessCB &&Success, AfterCB &&DoAfter) { 10395 assert(E->isComparisonOp() && "expected comparison operator"); 10396 assert((E->getOpcode() == BO_Cmp || 10397 E->getType()->isIntegralOrEnumerationType()) && 10398 "unsupported binary expression evaluation"); 10399 auto Error = [&](const Expr *E) { 10400 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 10401 return false; 10402 }; 10403 10404 using CCR = ComparisonCategoryResult; 10405 bool IsRelational = E->isRelationalOp(); 10406 bool IsEquality = E->isEqualityOp(); 10407 if (E->getOpcode() == BO_Cmp) { 10408 const ComparisonCategoryInfo &CmpInfo = 10409 Info.Ctx.CompCategories.getInfoForType(E->getType()); 10410 IsRelational = CmpInfo.isOrdered(); 10411 IsEquality = CmpInfo.isEquality(); 10412 } 10413 10414 QualType LHSTy = E->getLHS()->getType(); 10415 QualType RHSTy = E->getRHS()->getType(); 10416 10417 if (LHSTy->isIntegralOrEnumerationType() && 10418 RHSTy->isIntegralOrEnumerationType()) { 10419 APSInt LHS, RHS; 10420 bool LHSOK = EvaluateInteger(E->getLHS(), LHS, Info); 10421 if (!LHSOK && !Info.noteFailure()) 10422 return false; 10423 if (!EvaluateInteger(E->getRHS(), RHS, Info) || !LHSOK) 10424 return false; 10425 if (LHS < RHS) 10426 return Success(CCR::Less, E); 10427 if (LHS > RHS) 10428 return Success(CCR::Greater, E); 10429 return Success(CCR::Equal, E); 10430 } 10431 10432 if (LHSTy->isFixedPointType() || RHSTy->isFixedPointType()) { 10433 APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHSTy)); 10434 APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHSTy)); 10435 10436 bool LHSOK = EvaluateFixedPointOrInteger(E->getLHS(), LHSFX, Info); 10437 if (!LHSOK && !Info.noteFailure()) 10438 return false; 10439 if (!EvaluateFixedPointOrInteger(E->getRHS(), RHSFX, Info) || !LHSOK) 10440 return false; 10441 if (LHSFX < RHSFX) 10442 return Success(CCR::Less, E); 10443 if (LHSFX > RHSFX) 10444 return Success(CCR::Greater, E); 10445 return Success(CCR::Equal, E); 10446 } 10447 10448 if (LHSTy->isAnyComplexType() || RHSTy->isAnyComplexType()) { 10449 ComplexValue LHS, RHS; 10450 bool LHSOK; 10451 if (E->isAssignmentOp()) { 10452 LValue LV; 10453 EvaluateLValue(E->getLHS(), LV, Info); 10454 LHSOK = false; 10455 } else if (LHSTy->isRealFloatingType()) { 10456 LHSOK = EvaluateFloat(E->getLHS(), LHS.FloatReal, Info); 10457 if (LHSOK) { 10458 LHS.makeComplexFloat(); 10459 LHS.FloatImag = APFloat(LHS.FloatReal.getSemantics()); 10460 } 10461 } else { 10462 LHSOK = EvaluateComplex(E->getLHS(), LHS, Info); 10463 } 10464 if (!LHSOK && !Info.noteFailure()) 10465 return false; 10466 10467 if (E->getRHS()->getType()->isRealFloatingType()) { 10468 if (!EvaluateFloat(E->getRHS(), RHS.FloatReal, Info) || !LHSOK) 10469 return false; 10470 RHS.makeComplexFloat(); 10471 RHS.FloatImag = APFloat(RHS.FloatReal.getSemantics()); 10472 } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) 10473 return false; 10474 10475 if (LHS.isComplexFloat()) { 10476 APFloat::cmpResult CR_r = 10477 LHS.getComplexFloatReal().compare(RHS.getComplexFloatReal()); 10478 APFloat::cmpResult CR_i = 10479 LHS.getComplexFloatImag().compare(RHS.getComplexFloatImag()); 10480 bool IsEqual = CR_r == APFloat::cmpEqual && CR_i == APFloat::cmpEqual; 10481 return Success(IsEqual ? CCR::Equal : CCR::Nonequal, E); 10482 } else { 10483 assert(IsEquality && "invalid complex comparison"); 10484 bool IsEqual = LHS.getComplexIntReal() == RHS.getComplexIntReal() && 10485 LHS.getComplexIntImag() == RHS.getComplexIntImag(); 10486 return Success(IsEqual ? CCR::Equal : CCR::Nonequal, E); 10487 } 10488 } 10489 10490 if (LHSTy->isRealFloatingType() && 10491 RHSTy->isRealFloatingType()) { 10492 APFloat RHS(0.0), LHS(0.0); 10493 10494 bool LHSOK = EvaluateFloat(E->getRHS(), RHS, Info); 10495 if (!LHSOK && !Info.noteFailure()) 10496 return false; 10497 10498 if (!EvaluateFloat(E->getLHS(), LHS, Info) || !LHSOK) 10499 return false; 10500 10501 assert(E->isComparisonOp() && "Invalid binary operator!"); 10502 auto GetCmpRes = [&]() { 10503 switch (LHS.compare(RHS)) { 10504 case APFloat::cmpEqual: 10505 return CCR::Equal; 10506 case APFloat::cmpLessThan: 10507 return CCR::Less; 10508 case APFloat::cmpGreaterThan: 10509 return CCR::Greater; 10510 case APFloat::cmpUnordered: 10511 return CCR::Unordered; 10512 } 10513 llvm_unreachable("Unrecognised APFloat::cmpResult enum"); 10514 }; 10515 return Success(GetCmpRes(), E); 10516 } 10517 10518 if (LHSTy->isPointerType() && RHSTy->isPointerType()) { 10519 LValue LHSValue, RHSValue; 10520 10521 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info); 10522 if (!LHSOK && !Info.noteFailure()) 10523 return false; 10524 10525 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK) 10526 return false; 10527 10528 // Reject differing bases from the normal codepath; we special-case 10529 // comparisons to null. 10530 if (!HasSameBase(LHSValue, RHSValue)) { 10531 // Inequalities and subtractions between unrelated pointers have 10532 // unspecified or undefined behavior. 10533 if (!IsEquality) 10534 return Error(E); 10535 // A constant address may compare equal to the address of a symbol. 10536 // The one exception is that address of an object cannot compare equal 10537 // to a null pointer constant. 10538 if ((!LHSValue.Base && !LHSValue.Offset.isZero()) || 10539 (!RHSValue.Base && !RHSValue.Offset.isZero())) 10540 return Error(E); 10541 // It's implementation-defined whether distinct literals will have 10542 // distinct addresses. In clang, the result of such a comparison is 10543 // unspecified, so it is not a constant expression. However, we do know 10544 // that the address of a literal will be non-null. 10545 if ((IsLiteralLValue(LHSValue) || IsLiteralLValue(RHSValue)) && 10546 LHSValue.Base && RHSValue.Base) 10547 return Error(E); 10548 // We can't tell whether weak symbols will end up pointing to the same 10549 // object. 10550 if (IsWeakLValue(LHSValue) || IsWeakLValue(RHSValue)) 10551 return Error(E); 10552 // We can't compare the address of the start of one object with the 10553 // past-the-end address of another object, per C++ DR1652. 10554 if ((LHSValue.Base && LHSValue.Offset.isZero() && 10555 isOnePastTheEndOfCompleteObject(Info.Ctx, RHSValue)) || 10556 (RHSValue.Base && RHSValue.Offset.isZero() && 10557 isOnePastTheEndOfCompleteObject(Info.Ctx, LHSValue))) 10558 return Error(E); 10559 // We can't tell whether an object is at the same address as another 10560 // zero sized object. 10561 if ((RHSValue.Base && isZeroSized(LHSValue)) || 10562 (LHSValue.Base && isZeroSized(RHSValue))) 10563 return Error(E); 10564 return Success(CCR::Nonequal, E); 10565 } 10566 10567 const CharUnits &LHSOffset = LHSValue.getLValueOffset(); 10568 const CharUnits &RHSOffset = RHSValue.getLValueOffset(); 10569 10570 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator(); 10571 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator(); 10572 10573 // C++11 [expr.rel]p3: 10574 // Pointers to void (after pointer conversions) can be compared, with a 10575 // result defined as follows: If both pointers represent the same 10576 // address or are both the null pointer value, the result is true if the 10577 // operator is <= or >= and false otherwise; otherwise the result is 10578 // unspecified. 10579 // We interpret this as applying to pointers to *cv* void. 10580 if (LHSTy->isVoidPointerType() && LHSOffset != RHSOffset && IsRelational) 10581 Info.CCEDiag(E, diag::note_constexpr_void_comparison); 10582 10583 // C++11 [expr.rel]p2: 10584 // - If two pointers point to non-static data members of the same object, 10585 // or to subobjects or array elements fo such members, recursively, the 10586 // pointer to the later declared member compares greater provided the 10587 // two members have the same access control and provided their class is 10588 // not a union. 10589 // [...] 10590 // - Otherwise pointer comparisons are unspecified. 10591 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && IsRelational) { 10592 bool WasArrayIndex; 10593 unsigned Mismatch = FindDesignatorMismatch( 10594 getType(LHSValue.Base), LHSDesignator, RHSDesignator, WasArrayIndex); 10595 // At the point where the designators diverge, the comparison has a 10596 // specified value if: 10597 // - we are comparing array indices 10598 // - we are comparing fields of a union, or fields with the same access 10599 // Otherwise, the result is unspecified and thus the comparison is not a 10600 // constant expression. 10601 if (!WasArrayIndex && Mismatch < LHSDesignator.Entries.size() && 10602 Mismatch < RHSDesignator.Entries.size()) { 10603 const FieldDecl *LF = getAsField(LHSDesignator.Entries[Mismatch]); 10604 const FieldDecl *RF = getAsField(RHSDesignator.Entries[Mismatch]); 10605 if (!LF && !RF) 10606 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_classes); 10607 else if (!LF) 10608 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) 10609 << getAsBaseClass(LHSDesignator.Entries[Mismatch]) 10610 << RF->getParent() << RF; 10611 else if (!RF) 10612 Info.CCEDiag(E, diag::note_constexpr_pointer_comparison_base_field) 10613 << getAsBaseClass(RHSDesignator.Entries[Mismatch]) 10614 << LF->getParent() << LF; 10615 else if (!LF->getParent()->isUnion() && 10616 LF->getAccess() != RF->getAccess()) 10617 Info.CCEDiag(E, 10618 diag::note_constexpr_pointer_comparison_differing_access) 10619 << LF << LF->getAccess() << RF << RF->getAccess() 10620 << LF->getParent(); 10621 } 10622 } 10623 10624 // The comparison here must be unsigned, and performed with the same 10625 // width as the pointer. 10626 unsigned PtrSize = Info.Ctx.getTypeSize(LHSTy); 10627 uint64_t CompareLHS = LHSOffset.getQuantity(); 10628 uint64_t CompareRHS = RHSOffset.getQuantity(); 10629 assert(PtrSize <= 64 && "Unexpected pointer width"); 10630 uint64_t Mask = ~0ULL >> (64 - PtrSize); 10631 CompareLHS &= Mask; 10632 CompareRHS &= Mask; 10633 10634 // If there is a base and this is a relational operator, we can only 10635 // compare pointers within the object in question; otherwise, the result 10636 // depends on where the object is located in memory. 10637 if (!LHSValue.Base.isNull() && IsRelational) { 10638 QualType BaseTy = getType(LHSValue.Base); 10639 if (BaseTy->isIncompleteType()) 10640 return Error(E); 10641 CharUnits Size = Info.Ctx.getTypeSizeInChars(BaseTy); 10642 uint64_t OffsetLimit = Size.getQuantity(); 10643 if (CompareLHS > OffsetLimit || CompareRHS > OffsetLimit) 10644 return Error(E); 10645 } 10646 10647 if (CompareLHS < CompareRHS) 10648 return Success(CCR::Less, E); 10649 if (CompareLHS > CompareRHS) 10650 return Success(CCR::Greater, E); 10651 return Success(CCR::Equal, E); 10652 } 10653 10654 if (LHSTy->isMemberPointerType()) { 10655 assert(IsEquality && "unexpected member pointer operation"); 10656 assert(RHSTy->isMemberPointerType() && "invalid comparison"); 10657 10658 MemberPtr LHSValue, RHSValue; 10659 10660 bool LHSOK = EvaluateMemberPointer(E->getLHS(), LHSValue, Info); 10661 if (!LHSOK && !Info.noteFailure()) 10662 return false; 10663 10664 if (!EvaluateMemberPointer(E->getRHS(), RHSValue, Info) || !LHSOK) 10665 return false; 10666 10667 // C++11 [expr.eq]p2: 10668 // If both operands are null, they compare equal. Otherwise if only one is 10669 // null, they compare unequal. 10670 if (!LHSValue.getDecl() || !RHSValue.getDecl()) { 10671 bool Equal = !LHSValue.getDecl() && !RHSValue.getDecl(); 10672 return Success(Equal ? CCR::Equal : CCR::Nonequal, E); 10673 } 10674 10675 // Otherwise if either is a pointer to a virtual member function, the 10676 // result is unspecified. 10677 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(LHSValue.getDecl())) 10678 if (MD->isVirtual()) 10679 Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; 10680 if (const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(RHSValue.getDecl())) 10681 if (MD->isVirtual()) 10682 Info.CCEDiag(E, diag::note_constexpr_compare_virtual_mem_ptr) << MD; 10683 10684 // Otherwise they compare equal if and only if they would refer to the 10685 // same member of the same most derived object or the same subobject if 10686 // they were dereferenced with a hypothetical object of the associated 10687 // class type. 10688 bool Equal = LHSValue == RHSValue; 10689 return Success(Equal ? CCR::Equal : CCR::Nonequal, E); 10690 } 10691 10692 if (LHSTy->isNullPtrType()) { 10693 assert(E->isComparisonOp() && "unexpected nullptr operation"); 10694 assert(RHSTy->isNullPtrType() && "missing pointer conversion"); 10695 // C++11 [expr.rel]p4, [expr.eq]p3: If two operands of type std::nullptr_t 10696 // are compared, the result is true of the operator is <=, >= or ==, and 10697 // false otherwise. 10698 return Success(CCR::Equal, E); 10699 } 10700 10701 return DoAfter(); 10702 } 10703 10704 bool RecordExprEvaluator::VisitBinCmp(const BinaryOperator *E) { 10705 if (!CheckLiteralType(Info, E)) 10706 return false; 10707 10708 auto OnSuccess = [&](ComparisonCategoryResult ResKind, 10709 const BinaryOperator *E) { 10710 // Evaluation succeeded. Lookup the information for the comparison category 10711 // type and fetch the VarDecl for the result. 10712 const ComparisonCategoryInfo &CmpInfo = 10713 Info.Ctx.CompCategories.getInfoForType(E->getType()); 10714 const VarDecl *VD = 10715 CmpInfo.getValueInfo(CmpInfo.makeWeakResult(ResKind))->VD; 10716 // Check and evaluate the result as a constant expression. 10717 LValue LV; 10718 LV.set(VD); 10719 if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result)) 10720 return false; 10721 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result); 10722 }; 10723 return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() { 10724 return ExprEvaluatorBaseTy::VisitBinCmp(E); 10725 }); 10726 } 10727 10728 bool IntExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 10729 // We don't call noteFailure immediately because the assignment happens after 10730 // we evaluate LHS and RHS. 10731 if (!Info.keepEvaluatingAfterFailure() && E->isAssignmentOp()) 10732 return Error(E); 10733 10734 DelayedNoteFailureRAII MaybeNoteFailureLater(Info, E->isAssignmentOp()); 10735 if (DataRecursiveIntBinOpEvaluator::shouldEnqueue(E)) 10736 return DataRecursiveIntBinOpEvaluator(*this, Result).Traverse(E); 10737 10738 assert((!E->getLHS()->getType()->isIntegralOrEnumerationType() || 10739 !E->getRHS()->getType()->isIntegralOrEnumerationType()) && 10740 "DataRecursiveIntBinOpEvaluator should have handled integral types"); 10741 10742 if (E->isComparisonOp()) { 10743 // Evaluate builtin binary comparisons by evaluating them as C++2a three-way 10744 // comparisons and then translating the result. 10745 auto OnSuccess = [&](ComparisonCategoryResult ResKind, 10746 const BinaryOperator *E) { 10747 using CCR = ComparisonCategoryResult; 10748 bool IsEqual = ResKind == CCR::Equal, 10749 IsLess = ResKind == CCR::Less, 10750 IsGreater = ResKind == CCR::Greater; 10751 auto Op = E->getOpcode(); 10752 switch (Op) { 10753 default: 10754 llvm_unreachable("unsupported binary operator"); 10755 case BO_EQ: 10756 case BO_NE: 10757 return Success(IsEqual == (Op == BO_EQ), E); 10758 case BO_LT: return Success(IsLess, E); 10759 case BO_GT: return Success(IsGreater, E); 10760 case BO_LE: return Success(IsEqual || IsLess, E); 10761 case BO_GE: return Success(IsEqual || IsGreater, E); 10762 } 10763 }; 10764 return EvaluateComparisonBinaryOperator(Info, E, OnSuccess, [&]() { 10765 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 10766 }); 10767 } 10768 10769 QualType LHSTy = E->getLHS()->getType(); 10770 QualType RHSTy = E->getRHS()->getType(); 10771 10772 if (LHSTy->isPointerType() && RHSTy->isPointerType() && 10773 E->getOpcode() == BO_Sub) { 10774 LValue LHSValue, RHSValue; 10775 10776 bool LHSOK = EvaluatePointer(E->getLHS(), LHSValue, Info); 10777 if (!LHSOK && !Info.noteFailure()) 10778 return false; 10779 10780 if (!EvaluatePointer(E->getRHS(), RHSValue, Info) || !LHSOK) 10781 return false; 10782 10783 // Reject differing bases from the normal codepath; we special-case 10784 // comparisons to null. 10785 if (!HasSameBase(LHSValue, RHSValue)) { 10786 // Handle &&A - &&B. 10787 if (!LHSValue.Offset.isZero() || !RHSValue.Offset.isZero()) 10788 return Error(E); 10789 const Expr *LHSExpr = LHSValue.Base.dyn_cast<const Expr *>(); 10790 const Expr *RHSExpr = RHSValue.Base.dyn_cast<const Expr *>(); 10791 if (!LHSExpr || !RHSExpr) 10792 return Error(E); 10793 const AddrLabelExpr *LHSAddrExpr = dyn_cast<AddrLabelExpr>(LHSExpr); 10794 const AddrLabelExpr *RHSAddrExpr = dyn_cast<AddrLabelExpr>(RHSExpr); 10795 if (!LHSAddrExpr || !RHSAddrExpr) 10796 return Error(E); 10797 // Make sure both labels come from the same function. 10798 if (LHSAddrExpr->getLabel()->getDeclContext() != 10799 RHSAddrExpr->getLabel()->getDeclContext()) 10800 return Error(E); 10801 return Success(APValue(LHSAddrExpr, RHSAddrExpr), E); 10802 } 10803 const CharUnits &LHSOffset = LHSValue.getLValueOffset(); 10804 const CharUnits &RHSOffset = RHSValue.getLValueOffset(); 10805 10806 SubobjectDesignator &LHSDesignator = LHSValue.getLValueDesignator(); 10807 SubobjectDesignator &RHSDesignator = RHSValue.getLValueDesignator(); 10808 10809 // C++11 [expr.add]p6: 10810 // Unless both pointers point to elements of the same array object, or 10811 // one past the last element of the array object, the behavior is 10812 // undefined. 10813 if (!LHSDesignator.Invalid && !RHSDesignator.Invalid && 10814 !AreElementsOfSameArray(getType(LHSValue.Base), LHSDesignator, 10815 RHSDesignator)) 10816 Info.CCEDiag(E, diag::note_constexpr_pointer_subtraction_not_same_array); 10817 10818 QualType Type = E->getLHS()->getType(); 10819 QualType ElementType = Type->getAs<PointerType>()->getPointeeType(); 10820 10821 CharUnits ElementSize; 10822 if (!HandleSizeof(Info, E->getExprLoc(), ElementType, ElementSize)) 10823 return false; 10824 10825 // As an extension, a type may have zero size (empty struct or union in 10826 // C, array of zero length). Pointer subtraction in such cases has 10827 // undefined behavior, so is not constant. 10828 if (ElementSize.isZero()) { 10829 Info.FFDiag(E, diag::note_constexpr_pointer_subtraction_zero_size) 10830 << ElementType; 10831 return false; 10832 } 10833 10834 // FIXME: LLVM and GCC both compute LHSOffset - RHSOffset at runtime, 10835 // and produce incorrect results when it overflows. Such behavior 10836 // appears to be non-conforming, but is common, so perhaps we should 10837 // assume the standard intended for such cases to be undefined behavior 10838 // and check for them. 10839 10840 // Compute (LHSOffset - RHSOffset) / Size carefully, checking for 10841 // overflow in the final conversion to ptrdiff_t. 10842 APSInt LHS(llvm::APInt(65, (int64_t)LHSOffset.getQuantity(), true), false); 10843 APSInt RHS(llvm::APInt(65, (int64_t)RHSOffset.getQuantity(), true), false); 10844 APSInt ElemSize(llvm::APInt(65, (int64_t)ElementSize.getQuantity(), true), 10845 false); 10846 APSInt TrueResult = (LHS - RHS) / ElemSize; 10847 APSInt Result = TrueResult.trunc(Info.Ctx.getIntWidth(E->getType())); 10848 10849 if (Result.extend(65) != TrueResult && 10850 !HandleOverflow(Info, E, TrueResult, E->getType())) 10851 return false; 10852 return Success(Result, E); 10853 } 10854 10855 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 10856 } 10857 10858 /// VisitUnaryExprOrTypeTraitExpr - Evaluate a sizeof, alignof or vec_step with 10859 /// a result as the expression's type. 10860 bool IntExprEvaluator::VisitUnaryExprOrTypeTraitExpr( 10861 const UnaryExprOrTypeTraitExpr *E) { 10862 switch(E->getKind()) { 10863 case UETT_PreferredAlignOf: 10864 case UETT_AlignOf: { 10865 if (E->isArgumentType()) 10866 return Success(GetAlignOfType(Info, E->getArgumentType(), E->getKind()), 10867 E); 10868 else 10869 return Success(GetAlignOfExpr(Info, E->getArgumentExpr(), E->getKind()), 10870 E); 10871 } 10872 10873 case UETT_VecStep: { 10874 QualType Ty = E->getTypeOfArgument(); 10875 10876 if (Ty->isVectorType()) { 10877 unsigned n = Ty->castAs<VectorType>()->getNumElements(); 10878 10879 // The vec_step built-in functions that take a 3-component 10880 // vector return 4. (OpenCL 1.1 spec 6.11.12) 10881 if (n == 3) 10882 n = 4; 10883 10884 return Success(n, E); 10885 } else 10886 return Success(1, E); 10887 } 10888 10889 case UETT_SizeOf: { 10890 QualType SrcTy = E->getTypeOfArgument(); 10891 // C++ [expr.sizeof]p2: "When applied to a reference or a reference type, 10892 // the result is the size of the referenced type." 10893 if (const ReferenceType *Ref = SrcTy->getAs<ReferenceType>()) 10894 SrcTy = Ref->getPointeeType(); 10895 10896 CharUnits Sizeof; 10897 if (!HandleSizeof(Info, E->getExprLoc(), SrcTy, Sizeof)) 10898 return false; 10899 return Success(Sizeof, E); 10900 } 10901 case UETT_OpenMPRequiredSimdAlign: 10902 assert(E->isArgumentType()); 10903 return Success( 10904 Info.Ctx.toCharUnitsFromBits( 10905 Info.Ctx.getOpenMPDefaultSimdAlign(E->getArgumentType())) 10906 .getQuantity(), 10907 E); 10908 } 10909 10910 llvm_unreachable("unknown expr/type trait"); 10911 } 10912 10913 bool IntExprEvaluator::VisitOffsetOfExpr(const OffsetOfExpr *OOE) { 10914 CharUnits Result; 10915 unsigned n = OOE->getNumComponents(); 10916 if (n == 0) 10917 return Error(OOE); 10918 QualType CurrentType = OOE->getTypeSourceInfo()->getType(); 10919 for (unsigned i = 0; i != n; ++i) { 10920 OffsetOfNode ON = OOE->getComponent(i); 10921 switch (ON.getKind()) { 10922 case OffsetOfNode::Array: { 10923 const Expr *Idx = OOE->getIndexExpr(ON.getArrayExprIndex()); 10924 APSInt IdxResult; 10925 if (!EvaluateInteger(Idx, IdxResult, Info)) 10926 return false; 10927 const ArrayType *AT = Info.Ctx.getAsArrayType(CurrentType); 10928 if (!AT) 10929 return Error(OOE); 10930 CurrentType = AT->getElementType(); 10931 CharUnits ElementSize = Info.Ctx.getTypeSizeInChars(CurrentType); 10932 Result += IdxResult.getSExtValue() * ElementSize; 10933 break; 10934 } 10935 10936 case OffsetOfNode::Field: { 10937 FieldDecl *MemberDecl = ON.getField(); 10938 const RecordType *RT = CurrentType->getAs<RecordType>(); 10939 if (!RT) 10940 return Error(OOE); 10941 RecordDecl *RD = RT->getDecl(); 10942 if (RD->isInvalidDecl()) return false; 10943 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); 10944 unsigned i = MemberDecl->getFieldIndex(); 10945 assert(i < RL.getFieldCount() && "offsetof field in wrong type"); 10946 Result += Info.Ctx.toCharUnitsFromBits(RL.getFieldOffset(i)); 10947 CurrentType = MemberDecl->getType().getNonReferenceType(); 10948 break; 10949 } 10950 10951 case OffsetOfNode::Identifier: 10952 llvm_unreachable("dependent __builtin_offsetof"); 10953 10954 case OffsetOfNode::Base: { 10955 CXXBaseSpecifier *BaseSpec = ON.getBase(); 10956 if (BaseSpec->isVirtual()) 10957 return Error(OOE); 10958 10959 // Find the layout of the class whose base we are looking into. 10960 const RecordType *RT = CurrentType->getAs<RecordType>(); 10961 if (!RT) 10962 return Error(OOE); 10963 RecordDecl *RD = RT->getDecl(); 10964 if (RD->isInvalidDecl()) return false; 10965 const ASTRecordLayout &RL = Info.Ctx.getASTRecordLayout(RD); 10966 10967 // Find the base class itself. 10968 CurrentType = BaseSpec->getType(); 10969 const RecordType *BaseRT = CurrentType->getAs<RecordType>(); 10970 if (!BaseRT) 10971 return Error(OOE); 10972 10973 // Add the offset to the base. 10974 Result += RL.getBaseClassOffset(cast<CXXRecordDecl>(BaseRT->getDecl())); 10975 break; 10976 } 10977 } 10978 } 10979 return Success(Result, OOE); 10980 } 10981 10982 bool IntExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 10983 switch (E->getOpcode()) { 10984 default: 10985 // Address, indirect, pre/post inc/dec, etc are not valid constant exprs. 10986 // See C99 6.6p3. 10987 return Error(E); 10988 case UO_Extension: 10989 // FIXME: Should extension allow i-c-e extension expressions in its scope? 10990 // If so, we could clear the diagnostic ID. 10991 return Visit(E->getSubExpr()); 10992 case UO_Plus: 10993 // The result is just the value. 10994 return Visit(E->getSubExpr()); 10995 case UO_Minus: { 10996 if (!Visit(E->getSubExpr())) 10997 return false; 10998 if (!Result.isInt()) return Error(E); 10999 const APSInt &Value = Result.getInt(); 11000 if (Value.isSigned() && Value.isMinSignedValue() && E->canOverflow() && 11001 !HandleOverflow(Info, E, -Value.extend(Value.getBitWidth() + 1), 11002 E->getType())) 11003 return false; 11004 return Success(-Value, E); 11005 } 11006 case UO_Not: { 11007 if (!Visit(E->getSubExpr())) 11008 return false; 11009 if (!Result.isInt()) return Error(E); 11010 return Success(~Result.getInt(), E); 11011 } 11012 case UO_LNot: { 11013 bool bres; 11014 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info)) 11015 return false; 11016 return Success(!bres, E); 11017 } 11018 } 11019 } 11020 11021 /// HandleCast - This is used to evaluate implicit or explicit casts where the 11022 /// result type is integer. 11023 bool IntExprEvaluator::VisitCastExpr(const CastExpr *E) { 11024 const Expr *SubExpr = E->getSubExpr(); 11025 QualType DestType = E->getType(); 11026 QualType SrcType = SubExpr->getType(); 11027 11028 switch (E->getCastKind()) { 11029 case CK_BaseToDerived: 11030 case CK_DerivedToBase: 11031 case CK_UncheckedDerivedToBase: 11032 case CK_Dynamic: 11033 case CK_ToUnion: 11034 case CK_ArrayToPointerDecay: 11035 case CK_FunctionToPointerDecay: 11036 case CK_NullToPointer: 11037 case CK_NullToMemberPointer: 11038 case CK_BaseToDerivedMemberPointer: 11039 case CK_DerivedToBaseMemberPointer: 11040 case CK_ReinterpretMemberPointer: 11041 case CK_ConstructorConversion: 11042 case CK_IntegralToPointer: 11043 case CK_ToVoid: 11044 case CK_VectorSplat: 11045 case CK_IntegralToFloating: 11046 case CK_FloatingCast: 11047 case CK_CPointerToObjCPointerCast: 11048 case CK_BlockPointerToObjCPointerCast: 11049 case CK_AnyPointerToBlockPointerCast: 11050 case CK_ObjCObjectLValueCast: 11051 case CK_FloatingRealToComplex: 11052 case CK_FloatingComplexToReal: 11053 case CK_FloatingComplexCast: 11054 case CK_FloatingComplexToIntegralComplex: 11055 case CK_IntegralRealToComplex: 11056 case CK_IntegralComplexCast: 11057 case CK_IntegralComplexToFloatingComplex: 11058 case CK_BuiltinFnToFnPtr: 11059 case CK_ZeroToOCLOpaqueType: 11060 case CK_NonAtomicToAtomic: 11061 case CK_AddressSpaceConversion: 11062 case CK_IntToOCLSampler: 11063 case CK_FixedPointCast: 11064 case CK_IntegralToFixedPoint: 11065 llvm_unreachable("invalid cast kind for integral value"); 11066 11067 case CK_BitCast: 11068 case CK_Dependent: 11069 case CK_LValueBitCast: 11070 case CK_ARCProduceObject: 11071 case CK_ARCConsumeObject: 11072 case CK_ARCReclaimReturnedObject: 11073 case CK_ARCExtendBlockObject: 11074 case CK_CopyAndAutoreleaseBlockObject: 11075 return Error(E); 11076 11077 case CK_UserDefinedConversion: 11078 case CK_LValueToRValue: 11079 case CK_AtomicToNonAtomic: 11080 case CK_NoOp: 11081 case CK_LValueToRValueBitCast: 11082 return ExprEvaluatorBaseTy::VisitCastExpr(E); 11083 11084 case CK_MemberPointerToBoolean: 11085 case CK_PointerToBoolean: 11086 case CK_IntegralToBoolean: 11087 case CK_FloatingToBoolean: 11088 case CK_BooleanToSignedIntegral: 11089 case CK_FloatingComplexToBoolean: 11090 case CK_IntegralComplexToBoolean: { 11091 bool BoolResult; 11092 if (!EvaluateAsBooleanCondition(SubExpr, BoolResult, Info)) 11093 return false; 11094 uint64_t IntResult = BoolResult; 11095 if (BoolResult && E->getCastKind() == CK_BooleanToSignedIntegral) 11096 IntResult = (uint64_t)-1; 11097 return Success(IntResult, E); 11098 } 11099 11100 case CK_FixedPointToIntegral: { 11101 APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SrcType)); 11102 if (!EvaluateFixedPoint(SubExpr, Src, Info)) 11103 return false; 11104 bool Overflowed; 11105 llvm::APSInt Result = Src.convertToInt( 11106 Info.Ctx.getIntWidth(DestType), 11107 DestType->isSignedIntegerOrEnumerationType(), &Overflowed); 11108 if (Overflowed && !HandleOverflow(Info, E, Result, DestType)) 11109 return false; 11110 return Success(Result, E); 11111 } 11112 11113 case CK_FixedPointToBoolean: { 11114 // Unsigned padding does not affect this. 11115 APValue Val; 11116 if (!Evaluate(Val, Info, SubExpr)) 11117 return false; 11118 return Success(Val.getFixedPoint().getBoolValue(), E); 11119 } 11120 11121 case CK_IntegralCast: { 11122 if (!Visit(SubExpr)) 11123 return false; 11124 11125 if (!Result.isInt()) { 11126 // Allow casts of address-of-label differences if they are no-ops 11127 // or narrowing. (The narrowing case isn't actually guaranteed to 11128 // be constant-evaluatable except in some narrow cases which are hard 11129 // to detect here. We let it through on the assumption the user knows 11130 // what they are doing.) 11131 if (Result.isAddrLabelDiff()) 11132 return Info.Ctx.getTypeSize(DestType) <= Info.Ctx.getTypeSize(SrcType); 11133 // Only allow casts of lvalues if they are lossless. 11134 return Info.Ctx.getTypeSize(DestType) == Info.Ctx.getTypeSize(SrcType); 11135 } 11136 11137 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, 11138 Result.getInt()), E); 11139 } 11140 11141 case CK_PointerToIntegral: { 11142 CCEDiag(E, diag::note_constexpr_invalid_cast) << 2; 11143 11144 LValue LV; 11145 if (!EvaluatePointer(SubExpr, LV, Info)) 11146 return false; 11147 11148 if (LV.getLValueBase()) { 11149 // Only allow based lvalue casts if they are lossless. 11150 // FIXME: Allow a larger integer size than the pointer size, and allow 11151 // narrowing back down to pointer width in subsequent integral casts. 11152 // FIXME: Check integer type's active bits, not its type size. 11153 if (Info.Ctx.getTypeSize(DestType) != Info.Ctx.getTypeSize(SrcType)) 11154 return Error(E); 11155 11156 LV.Designator.setInvalid(); 11157 LV.moveInto(Result); 11158 return true; 11159 } 11160 11161 APSInt AsInt; 11162 APValue V; 11163 LV.moveInto(V); 11164 if (!V.toIntegralConstant(AsInt, SrcType, Info.Ctx)) 11165 llvm_unreachable("Can't cast this!"); 11166 11167 return Success(HandleIntToIntCast(Info, E, DestType, SrcType, AsInt), E); 11168 } 11169 11170 case CK_IntegralComplexToReal: { 11171 ComplexValue C; 11172 if (!EvaluateComplex(SubExpr, C, Info)) 11173 return false; 11174 return Success(C.getComplexIntReal(), E); 11175 } 11176 11177 case CK_FloatingToIntegral: { 11178 APFloat F(0.0); 11179 if (!EvaluateFloat(SubExpr, F, Info)) 11180 return false; 11181 11182 APSInt Value; 11183 if (!HandleFloatToIntCast(Info, E, SrcType, F, DestType, Value)) 11184 return false; 11185 return Success(Value, E); 11186 } 11187 } 11188 11189 llvm_unreachable("unknown cast resulting in integral value"); 11190 } 11191 11192 bool IntExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 11193 if (E->getSubExpr()->getType()->isAnyComplexType()) { 11194 ComplexValue LV; 11195 if (!EvaluateComplex(E->getSubExpr(), LV, Info)) 11196 return false; 11197 if (!LV.isComplexInt()) 11198 return Error(E); 11199 return Success(LV.getComplexIntReal(), E); 11200 } 11201 11202 return Visit(E->getSubExpr()); 11203 } 11204 11205 bool IntExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 11206 if (E->getSubExpr()->getType()->isComplexIntegerType()) { 11207 ComplexValue LV; 11208 if (!EvaluateComplex(E->getSubExpr(), LV, Info)) 11209 return false; 11210 if (!LV.isComplexInt()) 11211 return Error(E); 11212 return Success(LV.getComplexIntImag(), E); 11213 } 11214 11215 VisitIgnoredValue(E->getSubExpr()); 11216 return Success(0, E); 11217 } 11218 11219 bool IntExprEvaluator::VisitSizeOfPackExpr(const SizeOfPackExpr *E) { 11220 return Success(E->getPackLength(), E); 11221 } 11222 11223 bool IntExprEvaluator::VisitCXXNoexceptExpr(const CXXNoexceptExpr *E) { 11224 return Success(E->getValue(), E); 11225 } 11226 11227 bool FixedPointExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 11228 switch (E->getOpcode()) { 11229 default: 11230 // Invalid unary operators 11231 return Error(E); 11232 case UO_Plus: 11233 // The result is just the value. 11234 return Visit(E->getSubExpr()); 11235 case UO_Minus: { 11236 if (!Visit(E->getSubExpr())) return false; 11237 if (!Result.isFixedPoint()) 11238 return Error(E); 11239 bool Overflowed; 11240 APFixedPoint Negated = Result.getFixedPoint().negate(&Overflowed); 11241 if (Overflowed && !HandleOverflow(Info, E, Negated, E->getType())) 11242 return false; 11243 return Success(Negated, E); 11244 } 11245 case UO_LNot: { 11246 bool bres; 11247 if (!EvaluateAsBooleanCondition(E->getSubExpr(), bres, Info)) 11248 return false; 11249 return Success(!bres, E); 11250 } 11251 } 11252 } 11253 11254 bool FixedPointExprEvaluator::VisitCastExpr(const CastExpr *E) { 11255 const Expr *SubExpr = E->getSubExpr(); 11256 QualType DestType = E->getType(); 11257 assert(DestType->isFixedPointType() && 11258 "Expected destination type to be a fixed point type"); 11259 auto DestFXSema = Info.Ctx.getFixedPointSemantics(DestType); 11260 11261 switch (E->getCastKind()) { 11262 case CK_FixedPointCast: { 11263 APFixedPoint Src(Info.Ctx.getFixedPointSemantics(SubExpr->getType())); 11264 if (!EvaluateFixedPoint(SubExpr, Src, Info)) 11265 return false; 11266 bool Overflowed; 11267 APFixedPoint Result = Src.convert(DestFXSema, &Overflowed); 11268 if (Overflowed && !HandleOverflow(Info, E, Result, DestType)) 11269 return false; 11270 return Success(Result, E); 11271 } 11272 case CK_IntegralToFixedPoint: { 11273 APSInt Src; 11274 if (!EvaluateInteger(SubExpr, Src, Info)) 11275 return false; 11276 11277 bool Overflowed; 11278 APFixedPoint IntResult = APFixedPoint::getFromIntValue( 11279 Src, Info.Ctx.getFixedPointSemantics(DestType), &Overflowed); 11280 11281 if (Overflowed && !HandleOverflow(Info, E, IntResult, DestType)) 11282 return false; 11283 11284 return Success(IntResult, E); 11285 } 11286 case CK_NoOp: 11287 case CK_LValueToRValue: 11288 return ExprEvaluatorBaseTy::VisitCastExpr(E); 11289 default: 11290 return Error(E); 11291 } 11292 } 11293 11294 bool FixedPointExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 11295 const Expr *LHS = E->getLHS(); 11296 const Expr *RHS = E->getRHS(); 11297 FixedPointSemantics ResultFXSema = 11298 Info.Ctx.getFixedPointSemantics(E->getType()); 11299 11300 APFixedPoint LHSFX(Info.Ctx.getFixedPointSemantics(LHS->getType())); 11301 if (!EvaluateFixedPointOrInteger(LHS, LHSFX, Info)) 11302 return false; 11303 APFixedPoint RHSFX(Info.Ctx.getFixedPointSemantics(RHS->getType())); 11304 if (!EvaluateFixedPointOrInteger(RHS, RHSFX, Info)) 11305 return false; 11306 11307 switch (E->getOpcode()) { 11308 case BO_Add: { 11309 bool AddOverflow, ConversionOverflow; 11310 APFixedPoint Result = LHSFX.add(RHSFX, &AddOverflow) 11311 .convert(ResultFXSema, &ConversionOverflow); 11312 if ((AddOverflow || ConversionOverflow) && 11313 !HandleOverflow(Info, E, Result, E->getType())) 11314 return false; 11315 return Success(Result, E); 11316 } 11317 default: 11318 return false; 11319 } 11320 llvm_unreachable("Should've exited before this"); 11321 } 11322 11323 //===----------------------------------------------------------------------===// 11324 // Float Evaluation 11325 //===----------------------------------------------------------------------===// 11326 11327 namespace { 11328 class FloatExprEvaluator 11329 : public ExprEvaluatorBase<FloatExprEvaluator> { 11330 APFloat &Result; 11331 public: 11332 FloatExprEvaluator(EvalInfo &info, APFloat &result) 11333 : ExprEvaluatorBaseTy(info), Result(result) {} 11334 11335 bool Success(const APValue &V, const Expr *e) { 11336 Result = V.getFloat(); 11337 return true; 11338 } 11339 11340 bool ZeroInitialization(const Expr *E) { 11341 Result = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(E->getType())); 11342 return true; 11343 } 11344 11345 bool VisitCallExpr(const CallExpr *E); 11346 11347 bool VisitUnaryOperator(const UnaryOperator *E); 11348 bool VisitBinaryOperator(const BinaryOperator *E); 11349 bool VisitFloatingLiteral(const FloatingLiteral *E); 11350 bool VisitCastExpr(const CastExpr *E); 11351 11352 bool VisitUnaryReal(const UnaryOperator *E); 11353 bool VisitUnaryImag(const UnaryOperator *E); 11354 11355 // FIXME: Missing: array subscript of vector, member of vector 11356 }; 11357 } // end anonymous namespace 11358 11359 static bool EvaluateFloat(const Expr* E, APFloat& Result, EvalInfo &Info) { 11360 assert(E->isRValue() && E->getType()->isRealFloatingType()); 11361 return FloatExprEvaluator(Info, Result).Visit(E); 11362 } 11363 11364 static bool TryEvaluateBuiltinNaN(const ASTContext &Context, 11365 QualType ResultTy, 11366 const Expr *Arg, 11367 bool SNaN, 11368 llvm::APFloat &Result) { 11369 const StringLiteral *S = dyn_cast<StringLiteral>(Arg->IgnoreParenCasts()); 11370 if (!S) return false; 11371 11372 const llvm::fltSemantics &Sem = Context.getFloatTypeSemantics(ResultTy); 11373 11374 llvm::APInt fill; 11375 11376 // Treat empty strings as if they were zero. 11377 if (S->getString().empty()) 11378 fill = llvm::APInt(32, 0); 11379 else if (S->getString().getAsInteger(0, fill)) 11380 return false; 11381 11382 if (Context.getTargetInfo().isNan2008()) { 11383 if (SNaN) 11384 Result = llvm::APFloat::getSNaN(Sem, false, &fill); 11385 else 11386 Result = llvm::APFloat::getQNaN(Sem, false, &fill); 11387 } else { 11388 // Prior to IEEE 754-2008, architectures were allowed to choose whether 11389 // the first bit of their significand was set for qNaN or sNaN. MIPS chose 11390 // a different encoding to what became a standard in 2008, and for pre- 11391 // 2008 revisions, MIPS interpreted sNaN-2008 as qNan and qNaN-2008 as 11392 // sNaN. This is now known as "legacy NaN" encoding. 11393 if (SNaN) 11394 Result = llvm::APFloat::getQNaN(Sem, false, &fill); 11395 else 11396 Result = llvm::APFloat::getSNaN(Sem, false, &fill); 11397 } 11398 11399 return true; 11400 } 11401 11402 bool FloatExprEvaluator::VisitCallExpr(const CallExpr *E) { 11403 switch (E->getBuiltinCallee()) { 11404 default: 11405 return ExprEvaluatorBaseTy::VisitCallExpr(E); 11406 11407 case Builtin::BI__builtin_huge_val: 11408 case Builtin::BI__builtin_huge_valf: 11409 case Builtin::BI__builtin_huge_vall: 11410 case Builtin::BI__builtin_huge_valf128: 11411 case Builtin::BI__builtin_inf: 11412 case Builtin::BI__builtin_inff: 11413 case Builtin::BI__builtin_infl: 11414 case Builtin::BI__builtin_inff128: { 11415 const llvm::fltSemantics &Sem = 11416 Info.Ctx.getFloatTypeSemantics(E->getType()); 11417 Result = llvm::APFloat::getInf(Sem); 11418 return true; 11419 } 11420 11421 case Builtin::BI__builtin_nans: 11422 case Builtin::BI__builtin_nansf: 11423 case Builtin::BI__builtin_nansl: 11424 case Builtin::BI__builtin_nansf128: 11425 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), 11426 true, Result)) 11427 return Error(E); 11428 return true; 11429 11430 case Builtin::BI__builtin_nan: 11431 case Builtin::BI__builtin_nanf: 11432 case Builtin::BI__builtin_nanl: 11433 case Builtin::BI__builtin_nanf128: 11434 // If this is __builtin_nan() turn this into a nan, otherwise we 11435 // can't constant fold it. 11436 if (!TryEvaluateBuiltinNaN(Info.Ctx, E->getType(), E->getArg(0), 11437 false, Result)) 11438 return Error(E); 11439 return true; 11440 11441 case Builtin::BI__builtin_fabs: 11442 case Builtin::BI__builtin_fabsf: 11443 case Builtin::BI__builtin_fabsl: 11444 case Builtin::BI__builtin_fabsf128: 11445 if (!EvaluateFloat(E->getArg(0), Result, Info)) 11446 return false; 11447 11448 if (Result.isNegative()) 11449 Result.changeSign(); 11450 return true; 11451 11452 // FIXME: Builtin::BI__builtin_powi 11453 // FIXME: Builtin::BI__builtin_powif 11454 // FIXME: Builtin::BI__builtin_powil 11455 11456 case Builtin::BI__builtin_copysign: 11457 case Builtin::BI__builtin_copysignf: 11458 case Builtin::BI__builtin_copysignl: 11459 case Builtin::BI__builtin_copysignf128: { 11460 APFloat RHS(0.); 11461 if (!EvaluateFloat(E->getArg(0), Result, Info) || 11462 !EvaluateFloat(E->getArg(1), RHS, Info)) 11463 return false; 11464 Result.copySign(RHS); 11465 return true; 11466 } 11467 } 11468 } 11469 11470 bool FloatExprEvaluator::VisitUnaryReal(const UnaryOperator *E) { 11471 if (E->getSubExpr()->getType()->isAnyComplexType()) { 11472 ComplexValue CV; 11473 if (!EvaluateComplex(E->getSubExpr(), CV, Info)) 11474 return false; 11475 Result = CV.FloatReal; 11476 return true; 11477 } 11478 11479 return Visit(E->getSubExpr()); 11480 } 11481 11482 bool FloatExprEvaluator::VisitUnaryImag(const UnaryOperator *E) { 11483 if (E->getSubExpr()->getType()->isAnyComplexType()) { 11484 ComplexValue CV; 11485 if (!EvaluateComplex(E->getSubExpr(), CV, Info)) 11486 return false; 11487 Result = CV.FloatImag; 11488 return true; 11489 } 11490 11491 VisitIgnoredValue(E->getSubExpr()); 11492 const llvm::fltSemantics &Sem = Info.Ctx.getFloatTypeSemantics(E->getType()); 11493 Result = llvm::APFloat::getZero(Sem); 11494 return true; 11495 } 11496 11497 bool FloatExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 11498 switch (E->getOpcode()) { 11499 default: return Error(E); 11500 case UO_Plus: 11501 return EvaluateFloat(E->getSubExpr(), Result, Info); 11502 case UO_Minus: 11503 if (!EvaluateFloat(E->getSubExpr(), Result, Info)) 11504 return false; 11505 Result.changeSign(); 11506 return true; 11507 } 11508 } 11509 11510 bool FloatExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 11511 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) 11512 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 11513 11514 APFloat RHS(0.0); 11515 bool LHSOK = EvaluateFloat(E->getLHS(), Result, Info); 11516 if (!LHSOK && !Info.noteFailure()) 11517 return false; 11518 return EvaluateFloat(E->getRHS(), RHS, Info) && LHSOK && 11519 handleFloatFloatBinOp(Info, E, Result, E->getOpcode(), RHS); 11520 } 11521 11522 bool FloatExprEvaluator::VisitFloatingLiteral(const FloatingLiteral *E) { 11523 Result = E->getValue(); 11524 return true; 11525 } 11526 11527 bool FloatExprEvaluator::VisitCastExpr(const CastExpr *E) { 11528 const Expr* SubExpr = E->getSubExpr(); 11529 11530 switch (E->getCastKind()) { 11531 default: 11532 return ExprEvaluatorBaseTy::VisitCastExpr(E); 11533 11534 case CK_IntegralToFloating: { 11535 APSInt IntResult; 11536 return EvaluateInteger(SubExpr, IntResult, Info) && 11537 HandleIntToFloatCast(Info, E, SubExpr->getType(), IntResult, 11538 E->getType(), Result); 11539 } 11540 11541 case CK_FloatingCast: { 11542 if (!Visit(SubExpr)) 11543 return false; 11544 return HandleFloatToFloatCast(Info, E, SubExpr->getType(), E->getType(), 11545 Result); 11546 } 11547 11548 case CK_FloatingComplexToReal: { 11549 ComplexValue V; 11550 if (!EvaluateComplex(SubExpr, V, Info)) 11551 return false; 11552 Result = V.getComplexFloatReal(); 11553 return true; 11554 } 11555 } 11556 } 11557 11558 //===----------------------------------------------------------------------===// 11559 // Complex Evaluation (for float and integer) 11560 //===----------------------------------------------------------------------===// 11561 11562 namespace { 11563 class ComplexExprEvaluator 11564 : public ExprEvaluatorBase<ComplexExprEvaluator> { 11565 ComplexValue &Result; 11566 11567 public: 11568 ComplexExprEvaluator(EvalInfo &info, ComplexValue &Result) 11569 : ExprEvaluatorBaseTy(info), Result(Result) {} 11570 11571 bool Success(const APValue &V, const Expr *e) { 11572 Result.setFrom(V); 11573 return true; 11574 } 11575 11576 bool ZeroInitialization(const Expr *E); 11577 11578 //===--------------------------------------------------------------------===// 11579 // Visitor Methods 11580 //===--------------------------------------------------------------------===// 11581 11582 bool VisitImaginaryLiteral(const ImaginaryLiteral *E); 11583 bool VisitCastExpr(const CastExpr *E); 11584 bool VisitBinaryOperator(const BinaryOperator *E); 11585 bool VisitUnaryOperator(const UnaryOperator *E); 11586 bool VisitInitListExpr(const InitListExpr *E); 11587 }; 11588 } // end anonymous namespace 11589 11590 static bool EvaluateComplex(const Expr *E, ComplexValue &Result, 11591 EvalInfo &Info) { 11592 assert(E->isRValue() && E->getType()->isAnyComplexType()); 11593 return ComplexExprEvaluator(Info, Result).Visit(E); 11594 } 11595 11596 bool ComplexExprEvaluator::ZeroInitialization(const Expr *E) { 11597 QualType ElemTy = E->getType()->castAs<ComplexType>()->getElementType(); 11598 if (ElemTy->isRealFloatingType()) { 11599 Result.makeComplexFloat(); 11600 APFloat Zero = APFloat::getZero(Info.Ctx.getFloatTypeSemantics(ElemTy)); 11601 Result.FloatReal = Zero; 11602 Result.FloatImag = Zero; 11603 } else { 11604 Result.makeComplexInt(); 11605 APSInt Zero = Info.Ctx.MakeIntValue(0, ElemTy); 11606 Result.IntReal = Zero; 11607 Result.IntImag = Zero; 11608 } 11609 return true; 11610 } 11611 11612 bool ComplexExprEvaluator::VisitImaginaryLiteral(const ImaginaryLiteral *E) { 11613 const Expr* SubExpr = E->getSubExpr(); 11614 11615 if (SubExpr->getType()->isRealFloatingType()) { 11616 Result.makeComplexFloat(); 11617 APFloat &Imag = Result.FloatImag; 11618 if (!EvaluateFloat(SubExpr, Imag, Info)) 11619 return false; 11620 11621 Result.FloatReal = APFloat(Imag.getSemantics()); 11622 return true; 11623 } else { 11624 assert(SubExpr->getType()->isIntegerType() && 11625 "Unexpected imaginary literal."); 11626 11627 Result.makeComplexInt(); 11628 APSInt &Imag = Result.IntImag; 11629 if (!EvaluateInteger(SubExpr, Imag, Info)) 11630 return false; 11631 11632 Result.IntReal = APSInt(Imag.getBitWidth(), !Imag.isSigned()); 11633 return true; 11634 } 11635 } 11636 11637 bool ComplexExprEvaluator::VisitCastExpr(const CastExpr *E) { 11638 11639 switch (E->getCastKind()) { 11640 case CK_BitCast: 11641 case CK_BaseToDerived: 11642 case CK_DerivedToBase: 11643 case CK_UncheckedDerivedToBase: 11644 case CK_Dynamic: 11645 case CK_ToUnion: 11646 case CK_ArrayToPointerDecay: 11647 case CK_FunctionToPointerDecay: 11648 case CK_NullToPointer: 11649 case CK_NullToMemberPointer: 11650 case CK_BaseToDerivedMemberPointer: 11651 case CK_DerivedToBaseMemberPointer: 11652 case CK_MemberPointerToBoolean: 11653 case CK_ReinterpretMemberPointer: 11654 case CK_ConstructorConversion: 11655 case CK_IntegralToPointer: 11656 case CK_PointerToIntegral: 11657 case CK_PointerToBoolean: 11658 case CK_ToVoid: 11659 case CK_VectorSplat: 11660 case CK_IntegralCast: 11661 case CK_BooleanToSignedIntegral: 11662 case CK_IntegralToBoolean: 11663 case CK_IntegralToFloating: 11664 case CK_FloatingToIntegral: 11665 case CK_FloatingToBoolean: 11666 case CK_FloatingCast: 11667 case CK_CPointerToObjCPointerCast: 11668 case CK_BlockPointerToObjCPointerCast: 11669 case CK_AnyPointerToBlockPointerCast: 11670 case CK_ObjCObjectLValueCast: 11671 case CK_FloatingComplexToReal: 11672 case CK_FloatingComplexToBoolean: 11673 case CK_IntegralComplexToReal: 11674 case CK_IntegralComplexToBoolean: 11675 case CK_ARCProduceObject: 11676 case CK_ARCConsumeObject: 11677 case CK_ARCReclaimReturnedObject: 11678 case CK_ARCExtendBlockObject: 11679 case CK_CopyAndAutoreleaseBlockObject: 11680 case CK_BuiltinFnToFnPtr: 11681 case CK_ZeroToOCLOpaqueType: 11682 case CK_NonAtomicToAtomic: 11683 case CK_AddressSpaceConversion: 11684 case CK_IntToOCLSampler: 11685 case CK_FixedPointCast: 11686 case CK_FixedPointToBoolean: 11687 case CK_FixedPointToIntegral: 11688 case CK_IntegralToFixedPoint: 11689 llvm_unreachable("invalid cast kind for complex value"); 11690 11691 case CK_LValueToRValue: 11692 case CK_AtomicToNonAtomic: 11693 case CK_NoOp: 11694 case CK_LValueToRValueBitCast: 11695 return ExprEvaluatorBaseTy::VisitCastExpr(E); 11696 11697 case CK_Dependent: 11698 case CK_LValueBitCast: 11699 case CK_UserDefinedConversion: 11700 return Error(E); 11701 11702 case CK_FloatingRealToComplex: { 11703 APFloat &Real = Result.FloatReal; 11704 if (!EvaluateFloat(E->getSubExpr(), Real, Info)) 11705 return false; 11706 11707 Result.makeComplexFloat(); 11708 Result.FloatImag = APFloat(Real.getSemantics()); 11709 return true; 11710 } 11711 11712 case CK_FloatingComplexCast: { 11713 if (!Visit(E->getSubExpr())) 11714 return false; 11715 11716 QualType To = E->getType()->getAs<ComplexType>()->getElementType(); 11717 QualType From 11718 = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); 11719 11720 return HandleFloatToFloatCast(Info, E, From, To, Result.FloatReal) && 11721 HandleFloatToFloatCast(Info, E, From, To, Result.FloatImag); 11722 } 11723 11724 case CK_FloatingComplexToIntegralComplex: { 11725 if (!Visit(E->getSubExpr())) 11726 return false; 11727 11728 QualType To = E->getType()->getAs<ComplexType>()->getElementType(); 11729 QualType From 11730 = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); 11731 Result.makeComplexInt(); 11732 return HandleFloatToIntCast(Info, E, From, Result.FloatReal, 11733 To, Result.IntReal) && 11734 HandleFloatToIntCast(Info, E, From, Result.FloatImag, 11735 To, Result.IntImag); 11736 } 11737 11738 case CK_IntegralRealToComplex: { 11739 APSInt &Real = Result.IntReal; 11740 if (!EvaluateInteger(E->getSubExpr(), Real, Info)) 11741 return false; 11742 11743 Result.makeComplexInt(); 11744 Result.IntImag = APSInt(Real.getBitWidth(), !Real.isSigned()); 11745 return true; 11746 } 11747 11748 case CK_IntegralComplexCast: { 11749 if (!Visit(E->getSubExpr())) 11750 return false; 11751 11752 QualType To = E->getType()->getAs<ComplexType>()->getElementType(); 11753 QualType From 11754 = E->getSubExpr()->getType()->getAs<ComplexType>()->getElementType(); 11755 11756 Result.IntReal = HandleIntToIntCast(Info, E, To, From, Result.IntReal); 11757 Result.IntImag = HandleIntToIntCast(Info, E, To, From, Result.IntImag); 11758 return true; 11759 } 11760 11761 case CK_IntegralComplexToFloatingComplex: { 11762 if (!Visit(E->getSubExpr())) 11763 return false; 11764 11765 QualType To = E->getType()->castAs<ComplexType>()->getElementType(); 11766 QualType From 11767 = E->getSubExpr()->getType()->castAs<ComplexType>()->getElementType(); 11768 Result.makeComplexFloat(); 11769 return HandleIntToFloatCast(Info, E, From, Result.IntReal, 11770 To, Result.FloatReal) && 11771 HandleIntToFloatCast(Info, E, From, Result.IntImag, 11772 To, Result.FloatImag); 11773 } 11774 } 11775 11776 llvm_unreachable("unknown cast resulting in complex value"); 11777 } 11778 11779 bool ComplexExprEvaluator::VisitBinaryOperator(const BinaryOperator *E) { 11780 if (E->isPtrMemOp() || E->isAssignmentOp() || E->getOpcode() == BO_Comma) 11781 return ExprEvaluatorBaseTy::VisitBinaryOperator(E); 11782 11783 // Track whether the LHS or RHS is real at the type system level. When this is 11784 // the case we can simplify our evaluation strategy. 11785 bool LHSReal = false, RHSReal = false; 11786 11787 bool LHSOK; 11788 if (E->getLHS()->getType()->isRealFloatingType()) { 11789 LHSReal = true; 11790 APFloat &Real = Result.FloatReal; 11791 LHSOK = EvaluateFloat(E->getLHS(), Real, Info); 11792 if (LHSOK) { 11793 Result.makeComplexFloat(); 11794 Result.FloatImag = APFloat(Real.getSemantics()); 11795 } 11796 } else { 11797 LHSOK = Visit(E->getLHS()); 11798 } 11799 if (!LHSOK && !Info.noteFailure()) 11800 return false; 11801 11802 ComplexValue RHS; 11803 if (E->getRHS()->getType()->isRealFloatingType()) { 11804 RHSReal = true; 11805 APFloat &Real = RHS.FloatReal; 11806 if (!EvaluateFloat(E->getRHS(), Real, Info) || !LHSOK) 11807 return false; 11808 RHS.makeComplexFloat(); 11809 RHS.FloatImag = APFloat(Real.getSemantics()); 11810 } else if (!EvaluateComplex(E->getRHS(), RHS, Info) || !LHSOK) 11811 return false; 11812 11813 assert(!(LHSReal && RHSReal) && 11814 "Cannot have both operands of a complex operation be real."); 11815 switch (E->getOpcode()) { 11816 default: return Error(E); 11817 case BO_Add: 11818 if (Result.isComplexFloat()) { 11819 Result.getComplexFloatReal().add(RHS.getComplexFloatReal(), 11820 APFloat::rmNearestTiesToEven); 11821 if (LHSReal) 11822 Result.getComplexFloatImag() = RHS.getComplexFloatImag(); 11823 else if (!RHSReal) 11824 Result.getComplexFloatImag().add(RHS.getComplexFloatImag(), 11825 APFloat::rmNearestTiesToEven); 11826 } else { 11827 Result.getComplexIntReal() += RHS.getComplexIntReal(); 11828 Result.getComplexIntImag() += RHS.getComplexIntImag(); 11829 } 11830 break; 11831 case BO_Sub: 11832 if (Result.isComplexFloat()) { 11833 Result.getComplexFloatReal().subtract(RHS.getComplexFloatReal(), 11834 APFloat::rmNearestTiesToEven); 11835 if (LHSReal) { 11836 Result.getComplexFloatImag() = RHS.getComplexFloatImag(); 11837 Result.getComplexFloatImag().changeSign(); 11838 } else if (!RHSReal) { 11839 Result.getComplexFloatImag().subtract(RHS.getComplexFloatImag(), 11840 APFloat::rmNearestTiesToEven); 11841 } 11842 } else { 11843 Result.getComplexIntReal() -= RHS.getComplexIntReal(); 11844 Result.getComplexIntImag() -= RHS.getComplexIntImag(); 11845 } 11846 break; 11847 case BO_Mul: 11848 if (Result.isComplexFloat()) { 11849 // This is an implementation of complex multiplication according to the 11850 // constraints laid out in C11 Annex G. The implementation uses the 11851 // following naming scheme: 11852 // (a + ib) * (c + id) 11853 ComplexValue LHS = Result; 11854 APFloat &A = LHS.getComplexFloatReal(); 11855 APFloat &B = LHS.getComplexFloatImag(); 11856 APFloat &C = RHS.getComplexFloatReal(); 11857 APFloat &D = RHS.getComplexFloatImag(); 11858 APFloat &ResR = Result.getComplexFloatReal(); 11859 APFloat &ResI = Result.getComplexFloatImag(); 11860 if (LHSReal) { 11861 assert(!RHSReal && "Cannot have two real operands for a complex op!"); 11862 ResR = A * C; 11863 ResI = A * D; 11864 } else if (RHSReal) { 11865 ResR = C * A; 11866 ResI = C * B; 11867 } else { 11868 // In the fully general case, we need to handle NaNs and infinities 11869 // robustly. 11870 APFloat AC = A * C; 11871 APFloat BD = B * D; 11872 APFloat AD = A * D; 11873 APFloat BC = B * C; 11874 ResR = AC - BD; 11875 ResI = AD + BC; 11876 if (ResR.isNaN() && ResI.isNaN()) { 11877 bool Recalc = false; 11878 if (A.isInfinity() || B.isInfinity()) { 11879 A = APFloat::copySign( 11880 APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A); 11881 B = APFloat::copySign( 11882 APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B); 11883 if (C.isNaN()) 11884 C = APFloat::copySign(APFloat(C.getSemantics()), C); 11885 if (D.isNaN()) 11886 D = APFloat::copySign(APFloat(D.getSemantics()), D); 11887 Recalc = true; 11888 } 11889 if (C.isInfinity() || D.isInfinity()) { 11890 C = APFloat::copySign( 11891 APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C); 11892 D = APFloat::copySign( 11893 APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D); 11894 if (A.isNaN()) 11895 A = APFloat::copySign(APFloat(A.getSemantics()), A); 11896 if (B.isNaN()) 11897 B = APFloat::copySign(APFloat(B.getSemantics()), B); 11898 Recalc = true; 11899 } 11900 if (!Recalc && (AC.isInfinity() || BD.isInfinity() || 11901 AD.isInfinity() || BC.isInfinity())) { 11902 if (A.isNaN()) 11903 A = APFloat::copySign(APFloat(A.getSemantics()), A); 11904 if (B.isNaN()) 11905 B = APFloat::copySign(APFloat(B.getSemantics()), B); 11906 if (C.isNaN()) 11907 C = APFloat::copySign(APFloat(C.getSemantics()), C); 11908 if (D.isNaN()) 11909 D = APFloat::copySign(APFloat(D.getSemantics()), D); 11910 Recalc = true; 11911 } 11912 if (Recalc) { 11913 ResR = APFloat::getInf(A.getSemantics()) * (A * C - B * D); 11914 ResI = APFloat::getInf(A.getSemantics()) * (A * D + B * C); 11915 } 11916 } 11917 } 11918 } else { 11919 ComplexValue LHS = Result; 11920 Result.getComplexIntReal() = 11921 (LHS.getComplexIntReal() * RHS.getComplexIntReal() - 11922 LHS.getComplexIntImag() * RHS.getComplexIntImag()); 11923 Result.getComplexIntImag() = 11924 (LHS.getComplexIntReal() * RHS.getComplexIntImag() + 11925 LHS.getComplexIntImag() * RHS.getComplexIntReal()); 11926 } 11927 break; 11928 case BO_Div: 11929 if (Result.isComplexFloat()) { 11930 // This is an implementation of complex division according to the 11931 // constraints laid out in C11 Annex G. The implementation uses the 11932 // following naming scheme: 11933 // (a + ib) / (c + id) 11934 ComplexValue LHS = Result; 11935 APFloat &A = LHS.getComplexFloatReal(); 11936 APFloat &B = LHS.getComplexFloatImag(); 11937 APFloat &C = RHS.getComplexFloatReal(); 11938 APFloat &D = RHS.getComplexFloatImag(); 11939 APFloat &ResR = Result.getComplexFloatReal(); 11940 APFloat &ResI = Result.getComplexFloatImag(); 11941 if (RHSReal) { 11942 ResR = A / C; 11943 ResI = B / C; 11944 } else { 11945 if (LHSReal) { 11946 // No real optimizations we can do here, stub out with zero. 11947 B = APFloat::getZero(A.getSemantics()); 11948 } 11949 int DenomLogB = 0; 11950 APFloat MaxCD = maxnum(abs(C), abs(D)); 11951 if (MaxCD.isFinite()) { 11952 DenomLogB = ilogb(MaxCD); 11953 C = scalbn(C, -DenomLogB, APFloat::rmNearestTiesToEven); 11954 D = scalbn(D, -DenomLogB, APFloat::rmNearestTiesToEven); 11955 } 11956 APFloat Denom = C * C + D * D; 11957 ResR = scalbn((A * C + B * D) / Denom, -DenomLogB, 11958 APFloat::rmNearestTiesToEven); 11959 ResI = scalbn((B * C - A * D) / Denom, -DenomLogB, 11960 APFloat::rmNearestTiesToEven); 11961 if (ResR.isNaN() && ResI.isNaN()) { 11962 if (Denom.isPosZero() && (!A.isNaN() || !B.isNaN())) { 11963 ResR = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * A; 11964 ResI = APFloat::getInf(ResR.getSemantics(), C.isNegative()) * B; 11965 } else if ((A.isInfinity() || B.isInfinity()) && C.isFinite() && 11966 D.isFinite()) { 11967 A = APFloat::copySign( 11968 APFloat(A.getSemantics(), A.isInfinity() ? 1 : 0), A); 11969 B = APFloat::copySign( 11970 APFloat(B.getSemantics(), B.isInfinity() ? 1 : 0), B); 11971 ResR = APFloat::getInf(ResR.getSemantics()) * (A * C + B * D); 11972 ResI = APFloat::getInf(ResI.getSemantics()) * (B * C - A * D); 11973 } else if (MaxCD.isInfinity() && A.isFinite() && B.isFinite()) { 11974 C = APFloat::copySign( 11975 APFloat(C.getSemantics(), C.isInfinity() ? 1 : 0), C); 11976 D = APFloat::copySign( 11977 APFloat(D.getSemantics(), D.isInfinity() ? 1 : 0), D); 11978 ResR = APFloat::getZero(ResR.getSemantics()) * (A * C + B * D); 11979 ResI = APFloat::getZero(ResI.getSemantics()) * (B * C - A * D); 11980 } 11981 } 11982 } 11983 } else { 11984 if (RHS.getComplexIntReal() == 0 && RHS.getComplexIntImag() == 0) 11985 return Error(E, diag::note_expr_divide_by_zero); 11986 11987 ComplexValue LHS = Result; 11988 APSInt Den = RHS.getComplexIntReal() * RHS.getComplexIntReal() + 11989 RHS.getComplexIntImag() * RHS.getComplexIntImag(); 11990 Result.getComplexIntReal() = 11991 (LHS.getComplexIntReal() * RHS.getComplexIntReal() + 11992 LHS.getComplexIntImag() * RHS.getComplexIntImag()) / Den; 11993 Result.getComplexIntImag() = 11994 (LHS.getComplexIntImag() * RHS.getComplexIntReal() - 11995 LHS.getComplexIntReal() * RHS.getComplexIntImag()) / Den; 11996 } 11997 break; 11998 } 11999 12000 return true; 12001 } 12002 12003 bool ComplexExprEvaluator::VisitUnaryOperator(const UnaryOperator *E) { 12004 // Get the operand value into 'Result'. 12005 if (!Visit(E->getSubExpr())) 12006 return false; 12007 12008 switch (E->getOpcode()) { 12009 default: 12010 return Error(E); 12011 case UO_Extension: 12012 return true; 12013 case UO_Plus: 12014 // The result is always just the subexpr. 12015 return true; 12016 case UO_Minus: 12017 if (Result.isComplexFloat()) { 12018 Result.getComplexFloatReal().changeSign(); 12019 Result.getComplexFloatImag().changeSign(); 12020 } 12021 else { 12022 Result.getComplexIntReal() = -Result.getComplexIntReal(); 12023 Result.getComplexIntImag() = -Result.getComplexIntImag(); 12024 } 12025 return true; 12026 case UO_Not: 12027 if (Result.isComplexFloat()) 12028 Result.getComplexFloatImag().changeSign(); 12029 else 12030 Result.getComplexIntImag() = -Result.getComplexIntImag(); 12031 return true; 12032 } 12033 } 12034 12035 bool ComplexExprEvaluator::VisitInitListExpr(const InitListExpr *E) { 12036 if (E->getNumInits() == 2) { 12037 if (E->getType()->isComplexType()) { 12038 Result.makeComplexFloat(); 12039 if (!EvaluateFloat(E->getInit(0), Result.FloatReal, Info)) 12040 return false; 12041 if (!EvaluateFloat(E->getInit(1), Result.FloatImag, Info)) 12042 return false; 12043 } else { 12044 Result.makeComplexInt(); 12045 if (!EvaluateInteger(E->getInit(0), Result.IntReal, Info)) 12046 return false; 12047 if (!EvaluateInteger(E->getInit(1), Result.IntImag, Info)) 12048 return false; 12049 } 12050 return true; 12051 } 12052 return ExprEvaluatorBaseTy::VisitInitListExpr(E); 12053 } 12054 12055 //===----------------------------------------------------------------------===// 12056 // Atomic expression evaluation, essentially just handling the NonAtomicToAtomic 12057 // implicit conversion. 12058 //===----------------------------------------------------------------------===// 12059 12060 namespace { 12061 class AtomicExprEvaluator : 12062 public ExprEvaluatorBase<AtomicExprEvaluator> { 12063 const LValue *This; 12064 APValue &Result; 12065 public: 12066 AtomicExprEvaluator(EvalInfo &Info, const LValue *This, APValue &Result) 12067 : ExprEvaluatorBaseTy(Info), This(This), Result(Result) {} 12068 12069 bool Success(const APValue &V, const Expr *E) { 12070 Result = V; 12071 return true; 12072 } 12073 12074 bool ZeroInitialization(const Expr *E) { 12075 ImplicitValueInitExpr VIE( 12076 E->getType()->castAs<AtomicType>()->getValueType()); 12077 // For atomic-qualified class (and array) types in C++, initialize the 12078 // _Atomic-wrapped subobject directly, in-place. 12079 return This ? EvaluateInPlace(Result, Info, *This, &VIE) 12080 : Evaluate(Result, Info, &VIE); 12081 } 12082 12083 bool VisitCastExpr(const CastExpr *E) { 12084 switch (E->getCastKind()) { 12085 default: 12086 return ExprEvaluatorBaseTy::VisitCastExpr(E); 12087 case CK_NonAtomicToAtomic: 12088 return This ? EvaluateInPlace(Result, Info, *This, E->getSubExpr()) 12089 : Evaluate(Result, Info, E->getSubExpr()); 12090 } 12091 } 12092 }; 12093 } // end anonymous namespace 12094 12095 static bool EvaluateAtomic(const Expr *E, const LValue *This, APValue &Result, 12096 EvalInfo &Info) { 12097 assert(E->isRValue() && E->getType()->isAtomicType()); 12098 return AtomicExprEvaluator(Info, This, Result).Visit(E); 12099 } 12100 12101 //===----------------------------------------------------------------------===// 12102 // Void expression evaluation, primarily for a cast to void on the LHS of a 12103 // comma operator 12104 //===----------------------------------------------------------------------===// 12105 12106 namespace { 12107 class VoidExprEvaluator 12108 : public ExprEvaluatorBase<VoidExprEvaluator> { 12109 public: 12110 VoidExprEvaluator(EvalInfo &Info) : ExprEvaluatorBaseTy(Info) {} 12111 12112 bool Success(const APValue &V, const Expr *e) { return true; } 12113 12114 bool ZeroInitialization(const Expr *E) { return true; } 12115 12116 bool VisitCastExpr(const CastExpr *E) { 12117 switch (E->getCastKind()) { 12118 default: 12119 return ExprEvaluatorBaseTy::VisitCastExpr(E); 12120 case CK_ToVoid: 12121 VisitIgnoredValue(E->getSubExpr()); 12122 return true; 12123 } 12124 } 12125 12126 bool VisitCallExpr(const CallExpr *E) { 12127 switch (E->getBuiltinCallee()) { 12128 default: 12129 return ExprEvaluatorBaseTy::VisitCallExpr(E); 12130 case Builtin::BI__assume: 12131 case Builtin::BI__builtin_assume: 12132 // The argument is not evaluated! 12133 return true; 12134 } 12135 } 12136 }; 12137 } // end anonymous namespace 12138 12139 static bool EvaluateVoid(const Expr *E, EvalInfo &Info) { 12140 assert(E->isRValue() && E->getType()->isVoidType()); 12141 return VoidExprEvaluator(Info).Visit(E); 12142 } 12143 12144 //===----------------------------------------------------------------------===// 12145 // Top level Expr::EvaluateAsRValue method. 12146 //===----------------------------------------------------------------------===// 12147 12148 static bool Evaluate(APValue &Result, EvalInfo &Info, const Expr *E) { 12149 // In C, function designators are not lvalues, but we evaluate them as if they 12150 // are. 12151 QualType T = E->getType(); 12152 if (E->isGLValue() || T->isFunctionType()) { 12153 LValue LV; 12154 if (!EvaluateLValue(E, LV, Info)) 12155 return false; 12156 LV.moveInto(Result); 12157 } else if (T->isVectorType()) { 12158 if (!EvaluateVector(E, Result, Info)) 12159 return false; 12160 } else if (T->isIntegralOrEnumerationType()) { 12161 if (!IntExprEvaluator(Info, Result).Visit(E)) 12162 return false; 12163 } else if (T->hasPointerRepresentation()) { 12164 LValue LV; 12165 if (!EvaluatePointer(E, LV, Info)) 12166 return false; 12167 LV.moveInto(Result); 12168 } else if (T->isRealFloatingType()) { 12169 llvm::APFloat F(0.0); 12170 if (!EvaluateFloat(E, F, Info)) 12171 return false; 12172 Result = APValue(F); 12173 } else if (T->isAnyComplexType()) { 12174 ComplexValue C; 12175 if (!EvaluateComplex(E, C, Info)) 12176 return false; 12177 C.moveInto(Result); 12178 } else if (T->isFixedPointType()) { 12179 if (!FixedPointExprEvaluator(Info, Result).Visit(E)) return false; 12180 } else if (T->isMemberPointerType()) { 12181 MemberPtr P; 12182 if (!EvaluateMemberPointer(E, P, Info)) 12183 return false; 12184 P.moveInto(Result); 12185 return true; 12186 } else if (T->isArrayType()) { 12187 LValue LV; 12188 APValue &Value = createTemporary(E, false, LV, *Info.CurrentCall); 12189 if (!EvaluateArray(E, LV, Value, Info)) 12190 return false; 12191 Result = Value; 12192 } else if (T->isRecordType()) { 12193 LValue LV; 12194 APValue &Value = createTemporary(E, false, LV, *Info.CurrentCall); 12195 if (!EvaluateRecord(E, LV, Value, Info)) 12196 return false; 12197 Result = Value; 12198 } else if (T->isVoidType()) { 12199 if (!Info.getLangOpts().CPlusPlus11) 12200 Info.CCEDiag(E, diag::note_constexpr_nonliteral) 12201 << E->getType(); 12202 if (!EvaluateVoid(E, Info)) 12203 return false; 12204 } else if (T->isAtomicType()) { 12205 QualType Unqual = T.getAtomicUnqualifiedType(); 12206 if (Unqual->isArrayType() || Unqual->isRecordType()) { 12207 LValue LV; 12208 APValue &Value = createTemporary(E, false, LV, *Info.CurrentCall); 12209 if (!EvaluateAtomic(E, &LV, Value, Info)) 12210 return false; 12211 } else { 12212 if (!EvaluateAtomic(E, nullptr, Result, Info)) 12213 return false; 12214 } 12215 } else if (Info.getLangOpts().CPlusPlus11) { 12216 Info.FFDiag(E, diag::note_constexpr_nonliteral) << E->getType(); 12217 return false; 12218 } else { 12219 Info.FFDiag(E, diag::note_invalid_subexpr_in_const_expr); 12220 return false; 12221 } 12222 12223 return true; 12224 } 12225 12226 /// EvaluateInPlace - Evaluate an expression in-place in an APValue. In some 12227 /// cases, the in-place evaluation is essential, since later initializers for 12228 /// an object can indirectly refer to subobjects which were initialized earlier. 12229 static bool EvaluateInPlace(APValue &Result, EvalInfo &Info, const LValue &This, 12230 const Expr *E, bool AllowNonLiteralTypes) { 12231 assert(!E->isValueDependent()); 12232 12233 if (!AllowNonLiteralTypes && !CheckLiteralType(Info, E, &This)) 12234 return false; 12235 12236 if (E->isRValue()) { 12237 // Evaluate arrays and record types in-place, so that later initializers can 12238 // refer to earlier-initialized members of the object. 12239 QualType T = E->getType(); 12240 if (T->isArrayType()) 12241 return EvaluateArray(E, This, Result, Info); 12242 else if (T->isRecordType()) 12243 return EvaluateRecord(E, This, Result, Info); 12244 else if (T->isAtomicType()) { 12245 QualType Unqual = T.getAtomicUnqualifiedType(); 12246 if (Unqual->isArrayType() || Unqual->isRecordType()) 12247 return EvaluateAtomic(E, &This, Result, Info); 12248 } 12249 } 12250 12251 // For any other type, in-place evaluation is unimportant. 12252 return Evaluate(Result, Info, E); 12253 } 12254 12255 /// EvaluateAsRValue - Try to evaluate this expression, performing an implicit 12256 /// lvalue-to-rvalue cast if it is an lvalue. 12257 static bool EvaluateAsRValue(EvalInfo &Info, const Expr *E, APValue &Result) { 12258 if (E->getType().isNull()) 12259 return false; 12260 12261 if (!CheckLiteralType(Info, E)) 12262 return false; 12263 12264 if (!::Evaluate(Result, Info, E)) 12265 return false; 12266 12267 if (E->isGLValue()) { 12268 LValue LV; 12269 LV.setFrom(Info.Ctx, Result); 12270 if (!handleLValueToRValueConversion(Info, E, E->getType(), LV, Result)) 12271 return false; 12272 } 12273 12274 // Check this core constant expression is a constant expression. 12275 return CheckConstantExpression(Info, E->getExprLoc(), E->getType(), Result); 12276 } 12277 12278 static bool FastEvaluateAsRValue(const Expr *Exp, Expr::EvalResult &Result, 12279 const ASTContext &Ctx, bool &IsConst) { 12280 // Fast-path evaluations of integer literals, since we sometimes see files 12281 // containing vast quantities of these. 12282 if (const IntegerLiteral *L = dyn_cast<IntegerLiteral>(Exp)) { 12283 Result.Val = APValue(APSInt(L->getValue(), 12284 L->getType()->isUnsignedIntegerType())); 12285 IsConst = true; 12286 return true; 12287 } 12288 12289 // This case should be rare, but we need to check it before we check on 12290 // the type below. 12291 if (Exp->getType().isNull()) { 12292 IsConst = false; 12293 return true; 12294 } 12295 12296 // FIXME: Evaluating values of large array and record types can cause 12297 // performance problems. Only do so in C++11 for now. 12298 if (Exp->isRValue() && (Exp->getType()->isArrayType() || 12299 Exp->getType()->isRecordType()) && 12300 !Ctx.getLangOpts().CPlusPlus11) { 12301 IsConst = false; 12302 return true; 12303 } 12304 return false; 12305 } 12306 12307 static bool hasUnacceptableSideEffect(Expr::EvalStatus &Result, 12308 Expr::SideEffectsKind SEK) { 12309 return (SEK < Expr::SE_AllowSideEffects && Result.HasSideEffects) || 12310 (SEK < Expr::SE_AllowUndefinedBehavior && Result.HasUndefinedBehavior); 12311 } 12312 12313 static bool EvaluateAsRValue(const Expr *E, Expr::EvalResult &Result, 12314 const ASTContext &Ctx, EvalInfo &Info) { 12315 bool IsConst; 12316 if (FastEvaluateAsRValue(E, Result, Ctx, IsConst)) 12317 return IsConst; 12318 12319 return EvaluateAsRValue(Info, E, Result.Val); 12320 } 12321 12322 static bool EvaluateAsInt(const Expr *E, Expr::EvalResult &ExprResult, 12323 const ASTContext &Ctx, 12324 Expr::SideEffectsKind AllowSideEffects, 12325 EvalInfo &Info) { 12326 if (!E->getType()->isIntegralOrEnumerationType()) 12327 return false; 12328 12329 if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info) || 12330 !ExprResult.Val.isInt() || 12331 hasUnacceptableSideEffect(ExprResult, AllowSideEffects)) 12332 return false; 12333 12334 return true; 12335 } 12336 12337 static bool EvaluateAsFixedPoint(const Expr *E, Expr::EvalResult &ExprResult, 12338 const ASTContext &Ctx, 12339 Expr::SideEffectsKind AllowSideEffects, 12340 EvalInfo &Info) { 12341 if (!E->getType()->isFixedPointType()) 12342 return false; 12343 12344 if (!::EvaluateAsRValue(E, ExprResult, Ctx, Info)) 12345 return false; 12346 12347 if (!ExprResult.Val.isFixedPoint() || 12348 hasUnacceptableSideEffect(ExprResult, AllowSideEffects)) 12349 return false; 12350 12351 return true; 12352 } 12353 12354 /// EvaluateAsRValue - Return true if this is a constant which we can fold using 12355 /// any crazy technique (that has nothing to do with language standards) that 12356 /// we want to. If this function returns true, it returns the folded constant 12357 /// in Result. If this expression is a glvalue, an lvalue-to-rvalue conversion 12358 /// will be applied to the result. 12359 bool Expr::EvaluateAsRValue(EvalResult &Result, const ASTContext &Ctx, 12360 bool InConstantContext) const { 12361 assert(!isValueDependent() && 12362 "Expression evaluator can't be called on a dependent expression."); 12363 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); 12364 Info.InConstantContext = InConstantContext; 12365 return ::EvaluateAsRValue(this, Result, Ctx, Info); 12366 } 12367 12368 bool Expr::EvaluateAsBooleanCondition(bool &Result, const ASTContext &Ctx, 12369 bool InConstantContext) const { 12370 assert(!isValueDependent() && 12371 "Expression evaluator can't be called on a dependent expression."); 12372 EvalResult Scratch; 12373 return EvaluateAsRValue(Scratch, Ctx, InConstantContext) && 12374 HandleConversionToBool(Scratch.Val, Result); 12375 } 12376 12377 bool Expr::EvaluateAsInt(EvalResult &Result, const ASTContext &Ctx, 12378 SideEffectsKind AllowSideEffects, 12379 bool InConstantContext) const { 12380 assert(!isValueDependent() && 12381 "Expression evaluator can't be called on a dependent expression."); 12382 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); 12383 Info.InConstantContext = InConstantContext; 12384 return ::EvaluateAsInt(this, Result, Ctx, AllowSideEffects, Info); 12385 } 12386 12387 bool Expr::EvaluateAsFixedPoint(EvalResult &Result, const ASTContext &Ctx, 12388 SideEffectsKind AllowSideEffects, 12389 bool InConstantContext) const { 12390 assert(!isValueDependent() && 12391 "Expression evaluator can't be called on a dependent expression."); 12392 EvalInfo Info(Ctx, Result, EvalInfo::EM_IgnoreSideEffects); 12393 Info.InConstantContext = InConstantContext; 12394 return ::EvaluateAsFixedPoint(this, Result, Ctx, AllowSideEffects, Info); 12395 } 12396 12397 bool Expr::EvaluateAsFloat(APFloat &Result, const ASTContext &Ctx, 12398 SideEffectsKind AllowSideEffects, 12399 bool InConstantContext) const { 12400 assert(!isValueDependent() && 12401 "Expression evaluator can't be called on a dependent expression."); 12402 12403 if (!getType()->isRealFloatingType()) 12404 return false; 12405 12406 EvalResult ExprResult; 12407 if (!EvaluateAsRValue(ExprResult, Ctx, InConstantContext) || 12408 !ExprResult.Val.isFloat() || 12409 hasUnacceptableSideEffect(ExprResult, AllowSideEffects)) 12410 return false; 12411 12412 Result = ExprResult.Val.getFloat(); 12413 return true; 12414 } 12415 12416 bool Expr::EvaluateAsLValue(EvalResult &Result, const ASTContext &Ctx, 12417 bool InConstantContext) const { 12418 assert(!isValueDependent() && 12419 "Expression evaluator can't be called on a dependent expression."); 12420 12421 EvalInfo Info(Ctx, Result, EvalInfo::EM_ConstantFold); 12422 Info.InConstantContext = InConstantContext; 12423 LValue LV; 12424 if (!EvaluateLValue(this, LV, Info) || Result.HasSideEffects || 12425 !CheckLValueConstantExpression(Info, getExprLoc(), 12426 Ctx.getLValueReferenceType(getType()), LV, 12427 Expr::EvaluateForCodeGen)) 12428 return false; 12429 12430 LV.moveInto(Result.Val); 12431 return true; 12432 } 12433 12434 bool Expr::EvaluateAsConstantExpr(EvalResult &Result, ConstExprUsage Usage, 12435 const ASTContext &Ctx) const { 12436 assert(!isValueDependent() && 12437 "Expression evaluator can't be called on a dependent expression."); 12438 12439 EvalInfo::EvaluationMode EM = EvalInfo::EM_ConstantExpression; 12440 EvalInfo Info(Ctx, Result, EM); 12441 Info.InConstantContext = true; 12442 12443 if (!::Evaluate(Result.Val, Info, this)) 12444 return false; 12445 12446 return CheckConstantExpression(Info, getExprLoc(), getType(), Result.Val, 12447 Usage); 12448 } 12449 12450 bool Expr::EvaluateAsInitializer(APValue &Value, const ASTContext &Ctx, 12451 const VarDecl *VD, 12452 SmallVectorImpl<PartialDiagnosticAt> &Notes) const { 12453 assert(!isValueDependent() && 12454 "Expression evaluator can't be called on a dependent expression."); 12455 12456 // FIXME: Evaluating initializers for large array and record types can cause 12457 // performance problems. Only do so in C++11 for now. 12458 if (isRValue() && (getType()->isArrayType() || getType()->isRecordType()) && 12459 !Ctx.getLangOpts().CPlusPlus11) 12460 return false; 12461 12462 Expr::EvalStatus EStatus; 12463 EStatus.Diag = &Notes; 12464 12465 EvalInfo InitInfo(Ctx, EStatus, VD->isConstexpr() 12466 ? EvalInfo::EM_ConstantExpression 12467 : EvalInfo::EM_ConstantFold); 12468 InitInfo.setEvaluatingDecl(VD, Value); 12469 InitInfo.InConstantContext = true; 12470 12471 LValue LVal; 12472 LVal.set(VD); 12473 12474 // C++11 [basic.start.init]p2: 12475 // Variables with static storage duration or thread storage duration shall be 12476 // zero-initialized before any other initialization takes place. 12477 // This behavior is not present in C. 12478 if (Ctx.getLangOpts().CPlusPlus && !VD->hasLocalStorage() && 12479 !VD->getType()->isReferenceType()) { 12480 ImplicitValueInitExpr VIE(VD->getType()); 12481 if (!EvaluateInPlace(Value, InitInfo, LVal, &VIE, 12482 /*AllowNonLiteralTypes=*/true)) 12483 return false; 12484 } 12485 12486 if (!EvaluateInPlace(Value, InitInfo, LVal, this, 12487 /*AllowNonLiteralTypes=*/true) || 12488 EStatus.HasSideEffects) 12489 return false; 12490 12491 return CheckConstantExpression(InitInfo, VD->getLocation(), VD->getType(), 12492 Value); 12493 } 12494 12495 /// isEvaluatable - Call EvaluateAsRValue to see if this expression can be 12496 /// constant folded, but discard the result. 12497 bool Expr::isEvaluatable(const ASTContext &Ctx, SideEffectsKind SEK) const { 12498 assert(!isValueDependent() && 12499 "Expression evaluator can't be called on a dependent expression."); 12500 12501 EvalResult Result; 12502 return EvaluateAsRValue(Result, Ctx, /* in constant context */ true) && 12503 !hasUnacceptableSideEffect(Result, SEK); 12504 } 12505 12506 APSInt Expr::EvaluateKnownConstInt(const ASTContext &Ctx, 12507 SmallVectorImpl<PartialDiagnosticAt> *Diag) const { 12508 assert(!isValueDependent() && 12509 "Expression evaluator can't be called on a dependent expression."); 12510 12511 EvalResult EVResult; 12512 EVResult.Diag = Diag; 12513 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects); 12514 Info.InConstantContext = true; 12515 12516 bool Result = ::EvaluateAsRValue(this, EVResult, Ctx, Info); 12517 (void)Result; 12518 assert(Result && "Could not evaluate expression"); 12519 assert(EVResult.Val.isInt() && "Expression did not evaluate to integer"); 12520 12521 return EVResult.Val.getInt(); 12522 } 12523 12524 APSInt Expr::EvaluateKnownConstIntCheckOverflow( 12525 const ASTContext &Ctx, SmallVectorImpl<PartialDiagnosticAt> *Diag) const { 12526 assert(!isValueDependent() && 12527 "Expression evaluator can't be called on a dependent expression."); 12528 12529 EvalResult EVResult; 12530 EVResult.Diag = Diag; 12531 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects); 12532 Info.InConstantContext = true; 12533 Info.CheckingForUndefinedBehavior = true; 12534 12535 bool Result = ::EvaluateAsRValue(Info, this, EVResult.Val); 12536 (void)Result; 12537 assert(Result && "Could not evaluate expression"); 12538 assert(EVResult.Val.isInt() && "Expression did not evaluate to integer"); 12539 12540 return EVResult.Val.getInt(); 12541 } 12542 12543 void Expr::EvaluateForOverflow(const ASTContext &Ctx) const { 12544 assert(!isValueDependent() && 12545 "Expression evaluator can't be called on a dependent expression."); 12546 12547 bool IsConst; 12548 EvalResult EVResult; 12549 if (!FastEvaluateAsRValue(this, EVResult, Ctx, IsConst)) { 12550 EvalInfo Info(Ctx, EVResult, EvalInfo::EM_IgnoreSideEffects); 12551 Info.CheckingForUndefinedBehavior = true; 12552 (void)::EvaluateAsRValue(Info, this, EVResult.Val); 12553 } 12554 } 12555 12556 bool Expr::EvalResult::isGlobalLValue() const { 12557 assert(Val.isLValue()); 12558 return IsGlobalLValue(Val.getLValueBase()); 12559 } 12560 12561 12562 /// isIntegerConstantExpr - this recursive routine will test if an expression is 12563 /// an integer constant expression. 12564 12565 /// FIXME: Pass up a reason why! Invalid operation in i-c-e, division by zero, 12566 /// comma, etc 12567 12568 // CheckICE - This function does the fundamental ICE checking: the returned 12569 // ICEDiag contains an ICEKind indicating whether the expression is an ICE, 12570 // and a (possibly null) SourceLocation indicating the location of the problem. 12571 // 12572 // Note that to reduce code duplication, this helper does no evaluation 12573 // itself; the caller checks whether the expression is evaluatable, and 12574 // in the rare cases where CheckICE actually cares about the evaluated 12575 // value, it calls into Evaluate. 12576 12577 namespace { 12578 12579 enum ICEKind { 12580 /// This expression is an ICE. 12581 IK_ICE, 12582 /// This expression is not an ICE, but if it isn't evaluated, it's 12583 /// a legal subexpression for an ICE. This return value is used to handle 12584 /// the comma operator in C99 mode, and non-constant subexpressions. 12585 IK_ICEIfUnevaluated, 12586 /// This expression is not an ICE, and is not a legal subexpression for one. 12587 IK_NotICE 12588 }; 12589 12590 struct ICEDiag { 12591 ICEKind Kind; 12592 SourceLocation Loc; 12593 12594 ICEDiag(ICEKind IK, SourceLocation l) : Kind(IK), Loc(l) {} 12595 }; 12596 12597 } 12598 12599 static ICEDiag NoDiag() { return ICEDiag(IK_ICE, SourceLocation()); } 12600 12601 static ICEDiag Worst(ICEDiag A, ICEDiag B) { return A.Kind >= B.Kind ? A : B; } 12602 12603 static ICEDiag CheckEvalInICE(const Expr* E, const ASTContext &Ctx) { 12604 Expr::EvalResult EVResult; 12605 Expr::EvalStatus Status; 12606 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression); 12607 12608 Info.InConstantContext = true; 12609 if (!::EvaluateAsRValue(E, EVResult, Ctx, Info) || EVResult.HasSideEffects || 12610 !EVResult.Val.isInt()) 12611 return ICEDiag(IK_NotICE, E->getBeginLoc()); 12612 12613 return NoDiag(); 12614 } 12615 12616 static ICEDiag CheckICE(const Expr* E, const ASTContext &Ctx) { 12617 assert(!E->isValueDependent() && "Should not see value dependent exprs!"); 12618 if (!E->getType()->isIntegralOrEnumerationType()) 12619 return ICEDiag(IK_NotICE, E->getBeginLoc()); 12620 12621 switch (E->getStmtClass()) { 12622 #define ABSTRACT_STMT(Node) 12623 #define STMT(Node, Base) case Expr::Node##Class: 12624 #define EXPR(Node, Base) 12625 #include "clang/AST/StmtNodes.inc" 12626 case Expr::PredefinedExprClass: 12627 case Expr::FloatingLiteralClass: 12628 case Expr::ImaginaryLiteralClass: 12629 case Expr::StringLiteralClass: 12630 case Expr::ArraySubscriptExprClass: 12631 case Expr::OMPArraySectionExprClass: 12632 case Expr::MemberExprClass: 12633 case Expr::CompoundAssignOperatorClass: 12634 case Expr::CompoundLiteralExprClass: 12635 case Expr::ExtVectorElementExprClass: 12636 case Expr::DesignatedInitExprClass: 12637 case Expr::ArrayInitLoopExprClass: 12638 case Expr::ArrayInitIndexExprClass: 12639 case Expr::NoInitExprClass: 12640 case Expr::DesignatedInitUpdateExprClass: 12641 case Expr::ImplicitValueInitExprClass: 12642 case Expr::ParenListExprClass: 12643 case Expr::VAArgExprClass: 12644 case Expr::AddrLabelExprClass: 12645 case Expr::StmtExprClass: 12646 case Expr::CXXMemberCallExprClass: 12647 case Expr::CUDAKernelCallExprClass: 12648 case Expr::CXXDynamicCastExprClass: 12649 case Expr::CXXTypeidExprClass: 12650 case Expr::CXXUuidofExprClass: 12651 case Expr::MSPropertyRefExprClass: 12652 case Expr::MSPropertySubscriptExprClass: 12653 case Expr::CXXNullPtrLiteralExprClass: 12654 case Expr::UserDefinedLiteralClass: 12655 case Expr::CXXThisExprClass: 12656 case Expr::CXXThrowExprClass: 12657 case Expr::CXXNewExprClass: 12658 case Expr::CXXDeleteExprClass: 12659 case Expr::CXXPseudoDestructorExprClass: 12660 case Expr::UnresolvedLookupExprClass: 12661 case Expr::TypoExprClass: 12662 case Expr::DependentScopeDeclRefExprClass: 12663 case Expr::CXXConstructExprClass: 12664 case Expr::CXXInheritedCtorInitExprClass: 12665 case Expr::CXXStdInitializerListExprClass: 12666 case Expr::CXXBindTemporaryExprClass: 12667 case Expr::ExprWithCleanupsClass: 12668 case Expr::CXXTemporaryObjectExprClass: 12669 case Expr::CXXUnresolvedConstructExprClass: 12670 case Expr::CXXDependentScopeMemberExprClass: 12671 case Expr::UnresolvedMemberExprClass: 12672 case Expr::ObjCStringLiteralClass: 12673 case Expr::ObjCBoxedExprClass: 12674 case Expr::ObjCArrayLiteralClass: 12675 case Expr::ObjCDictionaryLiteralClass: 12676 case Expr::ObjCEncodeExprClass: 12677 case Expr::ObjCMessageExprClass: 12678 case Expr::ObjCSelectorExprClass: 12679 case Expr::ObjCProtocolExprClass: 12680 case Expr::ObjCIvarRefExprClass: 12681 case Expr::ObjCPropertyRefExprClass: 12682 case Expr::ObjCSubscriptRefExprClass: 12683 case Expr::ObjCIsaExprClass: 12684 case Expr::ObjCAvailabilityCheckExprClass: 12685 case Expr::ShuffleVectorExprClass: 12686 case Expr::ConvertVectorExprClass: 12687 case Expr::BlockExprClass: 12688 case Expr::NoStmtClass: 12689 case Expr::OpaqueValueExprClass: 12690 case Expr::PackExpansionExprClass: 12691 case Expr::SubstNonTypeTemplateParmPackExprClass: 12692 case Expr::FunctionParmPackExprClass: 12693 case Expr::AsTypeExprClass: 12694 case Expr::ObjCIndirectCopyRestoreExprClass: 12695 case Expr::MaterializeTemporaryExprClass: 12696 case Expr::PseudoObjectExprClass: 12697 case Expr::AtomicExprClass: 12698 case Expr::LambdaExprClass: 12699 case Expr::CXXFoldExprClass: 12700 case Expr::CoawaitExprClass: 12701 case Expr::DependentCoawaitExprClass: 12702 case Expr::CoyieldExprClass: 12703 return ICEDiag(IK_NotICE, E->getBeginLoc()); 12704 12705 case Expr::InitListExprClass: { 12706 // C++03 [dcl.init]p13: If T is a scalar type, then a declaration of the 12707 // form "T x = { a };" is equivalent to "T x = a;". 12708 // Unless we're initializing a reference, T is a scalar as it is known to be 12709 // of integral or enumeration type. 12710 if (E->isRValue()) 12711 if (cast<InitListExpr>(E)->getNumInits() == 1) 12712 return CheckICE(cast<InitListExpr>(E)->getInit(0), Ctx); 12713 return ICEDiag(IK_NotICE, E->getBeginLoc()); 12714 } 12715 12716 case Expr::SizeOfPackExprClass: 12717 case Expr::GNUNullExprClass: 12718 case Expr::SourceLocExprClass: 12719 return NoDiag(); 12720 12721 case Expr::SubstNonTypeTemplateParmExprClass: 12722 return 12723 CheckICE(cast<SubstNonTypeTemplateParmExpr>(E)->getReplacement(), Ctx); 12724 12725 case Expr::ConstantExprClass: 12726 return CheckICE(cast<ConstantExpr>(E)->getSubExpr(), Ctx); 12727 12728 case Expr::ParenExprClass: 12729 return CheckICE(cast<ParenExpr>(E)->getSubExpr(), Ctx); 12730 case Expr::GenericSelectionExprClass: 12731 return CheckICE(cast<GenericSelectionExpr>(E)->getResultExpr(), Ctx); 12732 case Expr::IntegerLiteralClass: 12733 case Expr::FixedPointLiteralClass: 12734 case Expr::CharacterLiteralClass: 12735 case Expr::ObjCBoolLiteralExprClass: 12736 case Expr::CXXBoolLiteralExprClass: 12737 case Expr::CXXScalarValueInitExprClass: 12738 case Expr::TypeTraitExprClass: 12739 case Expr::ArrayTypeTraitExprClass: 12740 case Expr::ExpressionTraitExprClass: 12741 case Expr::CXXNoexceptExprClass: 12742 return NoDiag(); 12743 case Expr::CallExprClass: 12744 case Expr::CXXOperatorCallExprClass: { 12745 // C99 6.6/3 allows function calls within unevaluated subexpressions of 12746 // constant expressions, but they can never be ICEs because an ICE cannot 12747 // contain an operand of (pointer to) function type. 12748 const CallExpr *CE = cast<CallExpr>(E); 12749 if (CE->getBuiltinCallee()) 12750 return CheckEvalInICE(E, Ctx); 12751 return ICEDiag(IK_NotICE, E->getBeginLoc()); 12752 } 12753 case Expr::DeclRefExprClass: { 12754 if (isa<EnumConstantDecl>(cast<DeclRefExpr>(E)->getDecl())) 12755 return NoDiag(); 12756 const ValueDecl *D = cast<DeclRefExpr>(E)->getDecl(); 12757 if (Ctx.getLangOpts().CPlusPlus && 12758 D && IsConstNonVolatile(D->getType())) { 12759 // Parameter variables are never constants. Without this check, 12760 // getAnyInitializer() can find a default argument, which leads 12761 // to chaos. 12762 if (isa<ParmVarDecl>(D)) 12763 return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); 12764 12765 // C++ 7.1.5.1p2 12766 // A variable of non-volatile const-qualified integral or enumeration 12767 // type initialized by an ICE can be used in ICEs. 12768 if (const VarDecl *Dcl = dyn_cast<VarDecl>(D)) { 12769 if (!Dcl->getType()->isIntegralOrEnumerationType()) 12770 return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); 12771 12772 const VarDecl *VD; 12773 // Look for a declaration of this variable that has an initializer, and 12774 // check whether it is an ICE. 12775 if (Dcl->getAnyInitializer(VD) && VD->checkInitIsICE()) 12776 return NoDiag(); 12777 else 12778 return ICEDiag(IK_NotICE, cast<DeclRefExpr>(E)->getLocation()); 12779 } 12780 } 12781 return ICEDiag(IK_NotICE, E->getBeginLoc()); 12782 } 12783 case Expr::UnaryOperatorClass: { 12784 const UnaryOperator *Exp = cast<UnaryOperator>(E); 12785 switch (Exp->getOpcode()) { 12786 case UO_PostInc: 12787 case UO_PostDec: 12788 case UO_PreInc: 12789 case UO_PreDec: 12790 case UO_AddrOf: 12791 case UO_Deref: 12792 case UO_Coawait: 12793 // C99 6.6/3 allows increment and decrement within unevaluated 12794 // subexpressions of constant expressions, but they can never be ICEs 12795 // because an ICE cannot contain an lvalue operand. 12796 return ICEDiag(IK_NotICE, E->getBeginLoc()); 12797 case UO_Extension: 12798 case UO_LNot: 12799 case UO_Plus: 12800 case UO_Minus: 12801 case UO_Not: 12802 case UO_Real: 12803 case UO_Imag: 12804 return CheckICE(Exp->getSubExpr(), Ctx); 12805 } 12806 llvm_unreachable("invalid unary operator class"); 12807 } 12808 case Expr::OffsetOfExprClass: { 12809 // Note that per C99, offsetof must be an ICE. And AFAIK, using 12810 // EvaluateAsRValue matches the proposed gcc behavior for cases like 12811 // "offsetof(struct s{int x[4];}, x[1.0])". This doesn't affect 12812 // compliance: we should warn earlier for offsetof expressions with 12813 // array subscripts that aren't ICEs, and if the array subscripts 12814 // are ICEs, the value of the offsetof must be an integer constant. 12815 return CheckEvalInICE(E, Ctx); 12816 } 12817 case Expr::UnaryExprOrTypeTraitExprClass: { 12818 const UnaryExprOrTypeTraitExpr *Exp = cast<UnaryExprOrTypeTraitExpr>(E); 12819 if ((Exp->getKind() == UETT_SizeOf) && 12820 Exp->getTypeOfArgument()->isVariableArrayType()) 12821 return ICEDiag(IK_NotICE, E->getBeginLoc()); 12822 return NoDiag(); 12823 } 12824 case Expr::BinaryOperatorClass: { 12825 const BinaryOperator *Exp = cast<BinaryOperator>(E); 12826 switch (Exp->getOpcode()) { 12827 case BO_PtrMemD: 12828 case BO_PtrMemI: 12829 case BO_Assign: 12830 case BO_MulAssign: 12831 case BO_DivAssign: 12832 case BO_RemAssign: 12833 case BO_AddAssign: 12834 case BO_SubAssign: 12835 case BO_ShlAssign: 12836 case BO_ShrAssign: 12837 case BO_AndAssign: 12838 case BO_XorAssign: 12839 case BO_OrAssign: 12840 // C99 6.6/3 allows assignments within unevaluated subexpressions of 12841 // constant expressions, but they can never be ICEs because an ICE cannot 12842 // contain an lvalue operand. 12843 return ICEDiag(IK_NotICE, E->getBeginLoc()); 12844 12845 case BO_Mul: 12846 case BO_Div: 12847 case BO_Rem: 12848 case BO_Add: 12849 case BO_Sub: 12850 case BO_Shl: 12851 case BO_Shr: 12852 case BO_LT: 12853 case BO_GT: 12854 case BO_LE: 12855 case BO_GE: 12856 case BO_EQ: 12857 case BO_NE: 12858 case BO_And: 12859 case BO_Xor: 12860 case BO_Or: 12861 case BO_Comma: 12862 case BO_Cmp: { 12863 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); 12864 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); 12865 if (Exp->getOpcode() == BO_Div || 12866 Exp->getOpcode() == BO_Rem) { 12867 // EvaluateAsRValue gives an error for undefined Div/Rem, so make sure 12868 // we don't evaluate one. 12869 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) { 12870 llvm::APSInt REval = Exp->getRHS()->EvaluateKnownConstInt(Ctx); 12871 if (REval == 0) 12872 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc()); 12873 if (REval.isSigned() && REval.isAllOnesValue()) { 12874 llvm::APSInt LEval = Exp->getLHS()->EvaluateKnownConstInt(Ctx); 12875 if (LEval.isMinSignedValue()) 12876 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc()); 12877 } 12878 } 12879 } 12880 if (Exp->getOpcode() == BO_Comma) { 12881 if (Ctx.getLangOpts().C99) { 12882 // C99 6.6p3 introduces a strange edge case: comma can be in an ICE 12883 // if it isn't evaluated. 12884 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICE) 12885 return ICEDiag(IK_ICEIfUnevaluated, E->getBeginLoc()); 12886 } else { 12887 // In both C89 and C++, commas in ICEs are illegal. 12888 return ICEDiag(IK_NotICE, E->getBeginLoc()); 12889 } 12890 } 12891 return Worst(LHSResult, RHSResult); 12892 } 12893 case BO_LAnd: 12894 case BO_LOr: { 12895 ICEDiag LHSResult = CheckICE(Exp->getLHS(), Ctx); 12896 ICEDiag RHSResult = CheckICE(Exp->getRHS(), Ctx); 12897 if (LHSResult.Kind == IK_ICE && RHSResult.Kind == IK_ICEIfUnevaluated) { 12898 // Rare case where the RHS has a comma "side-effect"; we need 12899 // to actually check the condition to see whether the side 12900 // with the comma is evaluated. 12901 if ((Exp->getOpcode() == BO_LAnd) != 12902 (Exp->getLHS()->EvaluateKnownConstInt(Ctx) == 0)) 12903 return RHSResult; 12904 return NoDiag(); 12905 } 12906 12907 return Worst(LHSResult, RHSResult); 12908 } 12909 } 12910 llvm_unreachable("invalid binary operator kind"); 12911 } 12912 case Expr::ImplicitCastExprClass: 12913 case Expr::CStyleCastExprClass: 12914 case Expr::CXXFunctionalCastExprClass: 12915 case Expr::CXXStaticCastExprClass: 12916 case Expr::CXXReinterpretCastExprClass: 12917 case Expr::CXXConstCastExprClass: 12918 case Expr::ObjCBridgedCastExprClass: { 12919 const Expr *SubExpr = cast<CastExpr>(E)->getSubExpr(); 12920 if (isa<ExplicitCastExpr>(E)) { 12921 if (const FloatingLiteral *FL 12922 = dyn_cast<FloatingLiteral>(SubExpr->IgnoreParenImpCasts())) { 12923 unsigned DestWidth = Ctx.getIntWidth(E->getType()); 12924 bool DestSigned = E->getType()->isSignedIntegerOrEnumerationType(); 12925 APSInt IgnoredVal(DestWidth, !DestSigned); 12926 bool Ignored; 12927 // If the value does not fit in the destination type, the behavior is 12928 // undefined, so we are not required to treat it as a constant 12929 // expression. 12930 if (FL->getValue().convertToInteger(IgnoredVal, 12931 llvm::APFloat::rmTowardZero, 12932 &Ignored) & APFloat::opInvalidOp) 12933 return ICEDiag(IK_NotICE, E->getBeginLoc()); 12934 return NoDiag(); 12935 } 12936 } 12937 switch (cast<CastExpr>(E)->getCastKind()) { 12938 case CK_LValueToRValue: 12939 case CK_AtomicToNonAtomic: 12940 case CK_NonAtomicToAtomic: 12941 case CK_NoOp: 12942 case CK_IntegralToBoolean: 12943 case CK_IntegralCast: 12944 return CheckICE(SubExpr, Ctx); 12945 default: 12946 return ICEDiag(IK_NotICE, E->getBeginLoc()); 12947 } 12948 } 12949 case Expr::BinaryConditionalOperatorClass: { 12950 const BinaryConditionalOperator *Exp = cast<BinaryConditionalOperator>(E); 12951 ICEDiag CommonResult = CheckICE(Exp->getCommon(), Ctx); 12952 if (CommonResult.Kind == IK_NotICE) return CommonResult; 12953 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); 12954 if (FalseResult.Kind == IK_NotICE) return FalseResult; 12955 if (CommonResult.Kind == IK_ICEIfUnevaluated) return CommonResult; 12956 if (FalseResult.Kind == IK_ICEIfUnevaluated && 12957 Exp->getCommon()->EvaluateKnownConstInt(Ctx) != 0) return NoDiag(); 12958 return FalseResult; 12959 } 12960 case Expr::ConditionalOperatorClass: { 12961 const ConditionalOperator *Exp = cast<ConditionalOperator>(E); 12962 // If the condition (ignoring parens) is a __builtin_constant_p call, 12963 // then only the true side is actually considered in an integer constant 12964 // expression, and it is fully evaluated. This is an important GNU 12965 // extension. See GCC PR38377 for discussion. 12966 if (const CallExpr *CallCE 12967 = dyn_cast<CallExpr>(Exp->getCond()->IgnoreParenCasts())) 12968 if (CallCE->getBuiltinCallee() == Builtin::BI__builtin_constant_p) 12969 return CheckEvalInICE(E, Ctx); 12970 ICEDiag CondResult = CheckICE(Exp->getCond(), Ctx); 12971 if (CondResult.Kind == IK_NotICE) 12972 return CondResult; 12973 12974 ICEDiag TrueResult = CheckICE(Exp->getTrueExpr(), Ctx); 12975 ICEDiag FalseResult = CheckICE(Exp->getFalseExpr(), Ctx); 12976 12977 if (TrueResult.Kind == IK_NotICE) 12978 return TrueResult; 12979 if (FalseResult.Kind == IK_NotICE) 12980 return FalseResult; 12981 if (CondResult.Kind == IK_ICEIfUnevaluated) 12982 return CondResult; 12983 if (TrueResult.Kind == IK_ICE && FalseResult.Kind == IK_ICE) 12984 return NoDiag(); 12985 // Rare case where the diagnostics depend on which side is evaluated 12986 // Note that if we get here, CondResult is 0, and at least one of 12987 // TrueResult and FalseResult is non-zero. 12988 if (Exp->getCond()->EvaluateKnownConstInt(Ctx) == 0) 12989 return FalseResult; 12990 return TrueResult; 12991 } 12992 case Expr::CXXDefaultArgExprClass: 12993 return CheckICE(cast<CXXDefaultArgExpr>(E)->getExpr(), Ctx); 12994 case Expr::CXXDefaultInitExprClass: 12995 return CheckICE(cast<CXXDefaultInitExpr>(E)->getExpr(), Ctx); 12996 case Expr::ChooseExprClass: { 12997 return CheckICE(cast<ChooseExpr>(E)->getChosenSubExpr(), Ctx); 12998 } 12999 case Expr::BuiltinBitCastExprClass: { 13000 if (!checkBitCastConstexprEligibility(nullptr, Ctx, cast<CastExpr>(E))) 13001 return ICEDiag(IK_NotICE, E->getBeginLoc()); 13002 return CheckICE(cast<CastExpr>(E)->getSubExpr(), Ctx); 13003 } 13004 } 13005 13006 llvm_unreachable("Invalid StmtClass!"); 13007 } 13008 13009 /// Evaluate an expression as a C++11 integral constant expression. 13010 static bool EvaluateCPlusPlus11IntegralConstantExpr(const ASTContext &Ctx, 13011 const Expr *E, 13012 llvm::APSInt *Value, 13013 SourceLocation *Loc) { 13014 if (!E->getType()->isIntegralOrUnscopedEnumerationType()) { 13015 if (Loc) *Loc = E->getExprLoc(); 13016 return false; 13017 } 13018 13019 APValue Result; 13020 if (!E->isCXX11ConstantExpr(Ctx, &Result, Loc)) 13021 return false; 13022 13023 if (!Result.isInt()) { 13024 if (Loc) *Loc = E->getExprLoc(); 13025 return false; 13026 } 13027 13028 if (Value) *Value = Result.getInt(); 13029 return true; 13030 } 13031 13032 bool Expr::isIntegerConstantExpr(const ASTContext &Ctx, 13033 SourceLocation *Loc) const { 13034 assert(!isValueDependent() && 13035 "Expression evaluator can't be called on a dependent expression."); 13036 13037 if (Ctx.getLangOpts().CPlusPlus11) 13038 return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, nullptr, Loc); 13039 13040 ICEDiag D = CheckICE(this, Ctx); 13041 if (D.Kind != IK_ICE) { 13042 if (Loc) *Loc = D.Loc; 13043 return false; 13044 } 13045 return true; 13046 } 13047 13048 bool Expr::isIntegerConstantExpr(llvm::APSInt &Value, const ASTContext &Ctx, 13049 SourceLocation *Loc, bool isEvaluated) const { 13050 assert(!isValueDependent() && 13051 "Expression evaluator can't be called on a dependent expression."); 13052 13053 if (Ctx.getLangOpts().CPlusPlus11) 13054 return EvaluateCPlusPlus11IntegralConstantExpr(Ctx, this, &Value, Loc); 13055 13056 if (!isIntegerConstantExpr(Ctx, Loc)) 13057 return false; 13058 13059 // The only possible side-effects here are due to UB discovered in the 13060 // evaluation (for instance, INT_MAX + 1). In such a case, we are still 13061 // required to treat the expression as an ICE, so we produce the folded 13062 // value. 13063 EvalResult ExprResult; 13064 Expr::EvalStatus Status; 13065 EvalInfo Info(Ctx, Status, EvalInfo::EM_IgnoreSideEffects); 13066 Info.InConstantContext = true; 13067 13068 if (!::EvaluateAsInt(this, ExprResult, Ctx, SE_AllowSideEffects, Info)) 13069 llvm_unreachable("ICE cannot be evaluated!"); 13070 13071 Value = ExprResult.Val.getInt(); 13072 return true; 13073 } 13074 13075 bool Expr::isCXX98IntegralConstantExpr(const ASTContext &Ctx) const { 13076 assert(!isValueDependent() && 13077 "Expression evaluator can't be called on a dependent expression."); 13078 13079 return CheckICE(this, Ctx).Kind == IK_ICE; 13080 } 13081 13082 bool Expr::isCXX11ConstantExpr(const ASTContext &Ctx, APValue *Result, 13083 SourceLocation *Loc) const { 13084 assert(!isValueDependent() && 13085 "Expression evaluator can't be called on a dependent expression."); 13086 13087 // We support this checking in C++98 mode in order to diagnose compatibility 13088 // issues. 13089 assert(Ctx.getLangOpts().CPlusPlus); 13090 13091 // Build evaluation settings. 13092 Expr::EvalStatus Status; 13093 SmallVector<PartialDiagnosticAt, 8> Diags; 13094 Status.Diag = &Diags; 13095 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpression); 13096 13097 APValue Scratch; 13098 bool IsConstExpr = ::EvaluateAsRValue(Info, this, Result ? *Result : Scratch); 13099 13100 if (!Diags.empty()) { 13101 IsConstExpr = false; 13102 if (Loc) *Loc = Diags[0].first; 13103 } else if (!IsConstExpr) { 13104 // FIXME: This shouldn't happen. 13105 if (Loc) *Loc = getExprLoc(); 13106 } 13107 13108 return IsConstExpr; 13109 } 13110 13111 bool Expr::EvaluateWithSubstitution(APValue &Value, ASTContext &Ctx, 13112 const FunctionDecl *Callee, 13113 ArrayRef<const Expr*> Args, 13114 const Expr *This) const { 13115 assert(!isValueDependent() && 13116 "Expression evaluator can't be called on a dependent expression."); 13117 13118 Expr::EvalStatus Status; 13119 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantExpressionUnevaluated); 13120 Info.InConstantContext = true; 13121 13122 LValue ThisVal; 13123 const LValue *ThisPtr = nullptr; 13124 if (This) { 13125 #ifndef NDEBUG 13126 auto *MD = dyn_cast<CXXMethodDecl>(Callee); 13127 assert(MD && "Don't provide `this` for non-methods."); 13128 assert(!MD->isStatic() && "Don't provide `this` for static methods."); 13129 #endif 13130 if (EvaluateObjectArgument(Info, This, ThisVal)) 13131 ThisPtr = &ThisVal; 13132 if (Info.EvalStatus.HasSideEffects) 13133 return false; 13134 } 13135 13136 ArgVector ArgValues(Args.size()); 13137 for (ArrayRef<const Expr*>::iterator I = Args.begin(), E = Args.end(); 13138 I != E; ++I) { 13139 if ((*I)->isValueDependent() || 13140 !Evaluate(ArgValues[I - Args.begin()], Info, *I)) 13141 // If evaluation fails, throw away the argument entirely. 13142 ArgValues[I - Args.begin()] = APValue(); 13143 if (Info.EvalStatus.HasSideEffects) 13144 return false; 13145 } 13146 13147 // Build fake call to Callee. 13148 CallStackFrame Frame(Info, Callee->getLocation(), Callee, ThisPtr, 13149 ArgValues.data()); 13150 return Evaluate(Value, Info, this) && !Info.EvalStatus.HasSideEffects; 13151 } 13152 13153 bool Expr::isPotentialConstantExpr(const FunctionDecl *FD, 13154 SmallVectorImpl< 13155 PartialDiagnosticAt> &Diags) { 13156 // FIXME: It would be useful to check constexpr function templates, but at the 13157 // moment the constant expression evaluator cannot cope with the non-rigorous 13158 // ASTs which we build for dependent expressions. 13159 if (FD->isDependentContext()) 13160 return true; 13161 13162 Expr::EvalStatus Status; 13163 Status.Diag = &Diags; 13164 13165 EvalInfo Info(FD->getASTContext(), Status, EvalInfo::EM_ConstantExpression); 13166 Info.InConstantContext = true; 13167 Info.CheckingPotentialConstantExpression = true; 13168 13169 const CXXMethodDecl *MD = dyn_cast<CXXMethodDecl>(FD); 13170 const CXXRecordDecl *RD = MD ? MD->getParent()->getCanonicalDecl() : nullptr; 13171 13172 // Fabricate an arbitrary expression on the stack and pretend that it 13173 // is a temporary being used as the 'this' pointer. 13174 LValue This; 13175 ImplicitValueInitExpr VIE(RD ? Info.Ctx.getRecordType(RD) : Info.Ctx.IntTy); 13176 This.set({&VIE, Info.CurrentCall->Index}); 13177 13178 ArrayRef<const Expr*> Args; 13179 13180 APValue Scratch; 13181 if (const CXXConstructorDecl *CD = dyn_cast<CXXConstructorDecl>(FD)) { 13182 // Evaluate the call as a constant initializer, to allow the construction 13183 // of objects of non-literal types. 13184 Info.setEvaluatingDecl(This.getLValueBase(), Scratch); 13185 HandleConstructorCall(&VIE, This, Args, CD, Info, Scratch); 13186 } else { 13187 SourceLocation Loc = FD->getLocation(); 13188 HandleFunctionCall(Loc, FD, (MD && MD->isInstance()) ? &This : nullptr, 13189 Args, FD->getBody(), Info, Scratch, nullptr); 13190 } 13191 13192 return Diags.empty(); 13193 } 13194 13195 bool Expr::isPotentialConstantExprUnevaluated(Expr *E, 13196 const FunctionDecl *FD, 13197 SmallVectorImpl< 13198 PartialDiagnosticAt> &Diags) { 13199 assert(!E->isValueDependent() && 13200 "Expression evaluator can't be called on a dependent expression."); 13201 13202 Expr::EvalStatus Status; 13203 Status.Diag = &Diags; 13204 13205 EvalInfo Info(FD->getASTContext(), Status, 13206 EvalInfo::EM_ConstantExpressionUnevaluated); 13207 Info.InConstantContext = true; 13208 Info.CheckingPotentialConstantExpression = true; 13209 13210 // Fabricate a call stack frame to give the arguments a plausible cover story. 13211 ArrayRef<const Expr*> Args; 13212 ArgVector ArgValues(0); 13213 bool Success = EvaluateArgs(Args, ArgValues, Info, FD); 13214 (void)Success; 13215 assert(Success && 13216 "Failed to set up arguments for potential constant evaluation"); 13217 CallStackFrame Frame(Info, SourceLocation(), FD, nullptr, ArgValues.data()); 13218 13219 APValue ResultScratch; 13220 Evaluate(ResultScratch, Info, E); 13221 return Diags.empty(); 13222 } 13223 13224 bool Expr::tryEvaluateObjectSize(uint64_t &Result, ASTContext &Ctx, 13225 unsigned Type) const { 13226 if (!getType()->isPointerType()) 13227 return false; 13228 13229 Expr::EvalStatus Status; 13230 EvalInfo Info(Ctx, Status, EvalInfo::EM_ConstantFold); 13231 return tryEvaluateBuiltinObjectSize(this, Type, Info, Result); 13232 } 13233