1 //===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate Expressions --------===// 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 contains code to emit Aggregate Expr nodes as LLVM code. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "CGCXXABI.h" 14 #include "CGObjCRuntime.h" 15 #include "CodeGenFunction.h" 16 #include "CodeGenModule.h" 17 #include "ConstantEmitter.h" 18 #include "TargetInfo.h" 19 #include "clang/AST/ASTContext.h" 20 #include "clang/AST/Attr.h" 21 #include "clang/AST/DeclCXX.h" 22 #include "clang/AST/DeclTemplate.h" 23 #include "clang/AST/StmtVisitor.h" 24 #include "llvm/IR/Constants.h" 25 #include "llvm/IR/Function.h" 26 #include "llvm/IR/GlobalVariable.h" 27 #include "llvm/IR/IntrinsicInst.h" 28 #include "llvm/IR/Intrinsics.h" 29 using namespace clang; 30 using namespace CodeGen; 31 32 //===----------------------------------------------------------------------===// 33 // Aggregate Expression Emitter 34 //===----------------------------------------------------------------------===// 35 36 namespace { 37 class AggExprEmitter : public StmtVisitor<AggExprEmitter> { 38 CodeGenFunction &CGF; 39 CGBuilderTy &Builder; 40 AggValueSlot Dest; 41 bool IsResultUnused; 42 43 AggValueSlot EnsureSlot(QualType T) { 44 if (!Dest.isIgnored()) return Dest; 45 return CGF.CreateAggTemp(T, "agg.tmp.ensured"); 46 } 47 void EnsureDest(QualType T) { 48 if (!Dest.isIgnored()) return; 49 Dest = CGF.CreateAggTemp(T, "agg.tmp.ensured"); 50 } 51 52 // Calls `Fn` with a valid return value slot, potentially creating a temporary 53 // to do so. If a temporary is created, an appropriate copy into `Dest` will 54 // be emitted, as will lifetime markers. 55 // 56 // The given function should take a ReturnValueSlot, and return an RValue that 57 // points to said slot. 58 void withReturnValueSlot(const Expr *E, 59 llvm::function_ref<RValue(ReturnValueSlot)> Fn); 60 61 public: 62 AggExprEmitter(CodeGenFunction &cgf, AggValueSlot Dest, bool IsResultUnused) 63 : CGF(cgf), Builder(CGF.Builder), Dest(Dest), 64 IsResultUnused(IsResultUnused) { } 65 66 //===--------------------------------------------------------------------===// 67 // Utilities 68 //===--------------------------------------------------------------------===// 69 70 /// EmitAggLoadOfLValue - Given an expression with aggregate type that 71 /// represents a value lvalue, this method emits the address of the lvalue, 72 /// then loads the result into DestPtr. 73 void EmitAggLoadOfLValue(const Expr *E); 74 75 enum ExprValueKind { 76 EVK_RValue, 77 EVK_NonRValue 78 }; 79 80 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. 81 /// SrcIsRValue is true if source comes from an RValue. 82 void EmitFinalDestCopy(QualType type, const LValue &src, 83 ExprValueKind SrcValueKind = EVK_NonRValue); 84 void EmitFinalDestCopy(QualType type, RValue src); 85 void EmitCopy(QualType type, const AggValueSlot &dest, 86 const AggValueSlot &src); 87 88 void EmitMoveFromReturnSlot(const Expr *E, RValue Src); 89 90 void EmitArrayInit(Address DestPtr, llvm::ArrayType *AType, 91 QualType ArrayQTy, InitListExpr *E); 92 93 AggValueSlot::NeedsGCBarriers_t needsGC(QualType T) { 94 if (CGF.getLangOpts().getGC() && TypeRequiresGCollection(T)) 95 return AggValueSlot::NeedsGCBarriers; 96 return AggValueSlot::DoesNotNeedGCBarriers; 97 } 98 99 bool TypeRequiresGCollection(QualType T); 100 101 //===--------------------------------------------------------------------===// 102 // Visitor Methods 103 //===--------------------------------------------------------------------===// 104 105 void Visit(Expr *E) { 106 ApplyDebugLocation DL(CGF, E); 107 StmtVisitor<AggExprEmitter>::Visit(E); 108 } 109 110 void VisitStmt(Stmt *S) { 111 CGF.ErrorUnsupported(S, "aggregate expression"); 112 } 113 void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); } 114 void VisitGenericSelectionExpr(GenericSelectionExpr *GE) { 115 Visit(GE->getResultExpr()); 116 } 117 void VisitCoawaitExpr(CoawaitExpr *E) { 118 CGF.EmitCoawaitExpr(*E, Dest, IsResultUnused); 119 } 120 void VisitCoyieldExpr(CoyieldExpr *E) { 121 CGF.EmitCoyieldExpr(*E, Dest, IsResultUnused); 122 } 123 void VisitUnaryCoawait(UnaryOperator *E) { Visit(E->getSubExpr()); } 124 void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); } 125 void VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) { 126 return Visit(E->getReplacement()); 127 } 128 129 void VisitConstantExpr(ConstantExpr *E) { 130 if (llvm::Value *Result = ConstantEmitter(CGF).tryEmitConstantExpr(E)) { 131 CGF.EmitAggregateStore(Result, Dest.getAddress(), 132 E->getType().isVolatileQualified()); 133 return; 134 } 135 return Visit(E->getSubExpr()); 136 } 137 138 // l-values. 139 void VisitDeclRefExpr(DeclRefExpr *E) { EmitAggLoadOfLValue(E); } 140 void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); } 141 void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); } 142 void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); } 143 void VisitCompoundLiteralExpr(CompoundLiteralExpr *E); 144 void VisitArraySubscriptExpr(ArraySubscriptExpr *E) { 145 EmitAggLoadOfLValue(E); 146 } 147 void VisitPredefinedExpr(const PredefinedExpr *E) { 148 EmitAggLoadOfLValue(E); 149 } 150 151 // Operators. 152 void VisitCastExpr(CastExpr *E); 153 void VisitCallExpr(const CallExpr *E); 154 void VisitStmtExpr(const StmtExpr *E); 155 void VisitBinaryOperator(const BinaryOperator *BO); 156 void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO); 157 void VisitBinAssign(const BinaryOperator *E); 158 void VisitBinComma(const BinaryOperator *E); 159 void VisitBinCmp(const BinaryOperator *E); 160 void VisitCXXRewrittenBinaryOperator(CXXRewrittenBinaryOperator *E) { 161 Visit(E->getSemanticForm()); 162 } 163 164 void VisitObjCMessageExpr(ObjCMessageExpr *E); 165 void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) { 166 EmitAggLoadOfLValue(E); 167 } 168 169 void VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E); 170 void VisitAbstractConditionalOperator(const AbstractConditionalOperator *CO); 171 void VisitChooseExpr(const ChooseExpr *CE); 172 void VisitInitListExpr(InitListExpr *E); 173 void VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E, 174 llvm::Value *outerBegin = nullptr); 175 void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E); 176 void VisitNoInitExpr(NoInitExpr *E) { } // Do nothing. 177 void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { 178 CodeGenFunction::CXXDefaultArgExprScope Scope(CGF, DAE); 179 Visit(DAE->getExpr()); 180 } 181 void VisitCXXDefaultInitExpr(CXXDefaultInitExpr *DIE) { 182 CodeGenFunction::CXXDefaultInitExprScope Scope(CGF, DIE); 183 Visit(DIE->getExpr()); 184 } 185 void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E); 186 void VisitCXXConstructExpr(const CXXConstructExpr *E); 187 void VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E); 188 void VisitLambdaExpr(LambdaExpr *E); 189 void VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E); 190 void VisitExprWithCleanups(ExprWithCleanups *E); 191 void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E); 192 void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); } 193 void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E); 194 void VisitOpaqueValueExpr(OpaqueValueExpr *E); 195 196 void VisitPseudoObjectExpr(PseudoObjectExpr *E) { 197 if (E->isGLValue()) { 198 LValue LV = CGF.EmitPseudoObjectLValue(E); 199 return EmitFinalDestCopy(E->getType(), LV); 200 } 201 202 CGF.EmitPseudoObjectRValue(E, EnsureSlot(E->getType())); 203 } 204 205 void VisitVAArgExpr(VAArgExpr *E); 206 207 void EmitInitializationToLValue(Expr *E, LValue Address); 208 void EmitNullInitializationToLValue(LValue Address); 209 // case Expr::ChooseExprClass: 210 void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); } 211 void VisitAtomicExpr(AtomicExpr *E) { 212 RValue Res = CGF.EmitAtomicExpr(E); 213 EmitFinalDestCopy(E->getType(), Res); 214 } 215 }; 216 } // end anonymous namespace. 217 218 //===----------------------------------------------------------------------===// 219 // Utilities 220 //===----------------------------------------------------------------------===// 221 222 /// EmitAggLoadOfLValue - Given an expression with aggregate type that 223 /// represents a value lvalue, this method emits the address of the lvalue, 224 /// then loads the result into DestPtr. 225 void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) { 226 LValue LV = CGF.EmitLValue(E); 227 228 // If the type of the l-value is atomic, then do an atomic load. 229 if (LV.getType()->isAtomicType() || CGF.LValueIsSuitableForInlineAtomic(LV)) { 230 CGF.EmitAtomicLoad(LV, E->getExprLoc(), Dest); 231 return; 232 } 233 234 EmitFinalDestCopy(E->getType(), LV); 235 } 236 237 /// True if the given aggregate type requires special GC API calls. 238 bool AggExprEmitter::TypeRequiresGCollection(QualType T) { 239 // Only record types have members that might require garbage collection. 240 const RecordType *RecordTy = T->getAs<RecordType>(); 241 if (!RecordTy) return false; 242 243 // Don't mess with non-trivial C++ types. 244 RecordDecl *Record = RecordTy->getDecl(); 245 if (isa<CXXRecordDecl>(Record) && 246 (cast<CXXRecordDecl>(Record)->hasNonTrivialCopyConstructor() || 247 !cast<CXXRecordDecl>(Record)->hasTrivialDestructor())) 248 return false; 249 250 // Check whether the type has an object member. 251 return Record->hasObjectMember(); 252 } 253 254 void AggExprEmitter::withReturnValueSlot( 255 const Expr *E, llvm::function_ref<RValue(ReturnValueSlot)> EmitCall) { 256 QualType RetTy = E->getType(); 257 bool RequiresDestruction = 258 !Dest.isExternallyDestructed() && 259 RetTy.isDestructedType() == QualType::DK_nontrivial_c_struct; 260 261 // If it makes no observable difference, save a memcpy + temporary. 262 // 263 // We need to always provide our own temporary if destruction is required. 264 // Otherwise, EmitCall will emit its own, notice that it's "unused", and end 265 // its lifetime before we have the chance to emit a proper destructor call. 266 bool UseTemp = Dest.isPotentiallyAliased() || Dest.requiresGCollection() || 267 (RequiresDestruction && !Dest.getAddress().isValid()); 268 269 Address RetAddr = Address::invalid(); 270 Address RetAllocaAddr = Address::invalid(); 271 272 EHScopeStack::stable_iterator LifetimeEndBlock; 273 llvm::Value *LifetimeSizePtr = nullptr; 274 llvm::IntrinsicInst *LifetimeStartInst = nullptr; 275 if (!UseTemp) { 276 RetAddr = Dest.getAddress(); 277 } else { 278 RetAddr = CGF.CreateMemTemp(RetTy, "tmp", &RetAllocaAddr); 279 uint64_t Size = 280 CGF.CGM.getDataLayout().getTypeAllocSize(CGF.ConvertTypeForMem(RetTy)); 281 LifetimeSizePtr = CGF.EmitLifetimeStart(Size, RetAllocaAddr.getPointer()); 282 if (LifetimeSizePtr) { 283 LifetimeStartInst = 284 cast<llvm::IntrinsicInst>(std::prev(Builder.GetInsertPoint())); 285 assert(LifetimeStartInst->getIntrinsicID() == 286 llvm::Intrinsic::lifetime_start && 287 "Last insertion wasn't a lifetime.start?"); 288 289 CGF.pushFullExprCleanup<CodeGenFunction::CallLifetimeEnd>( 290 NormalEHLifetimeMarker, RetAllocaAddr, LifetimeSizePtr); 291 LifetimeEndBlock = CGF.EHStack.stable_begin(); 292 } 293 } 294 295 RValue Src = 296 EmitCall(ReturnValueSlot(RetAddr, Dest.isVolatile(), IsResultUnused, 297 Dest.isExternallyDestructed())); 298 299 if (!UseTemp) 300 return; 301 302 assert(Dest.getPointer() != Src.getAggregatePointer()); 303 EmitFinalDestCopy(E->getType(), Src); 304 305 if (!RequiresDestruction && LifetimeStartInst) { 306 // If there's no dtor to run, the copy was the last use of our temporary. 307 // Since we're not guaranteed to be in an ExprWithCleanups, clean up 308 // eagerly. 309 CGF.DeactivateCleanupBlock(LifetimeEndBlock, LifetimeStartInst); 310 CGF.EmitLifetimeEnd(LifetimeSizePtr, RetAllocaAddr.getPointer()); 311 } 312 } 313 314 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. 315 void AggExprEmitter::EmitFinalDestCopy(QualType type, RValue src) { 316 assert(src.isAggregate() && "value must be aggregate value!"); 317 LValue srcLV = CGF.MakeAddrLValue(src.getAggregateAddress(), type); 318 EmitFinalDestCopy(type, srcLV, EVK_RValue); 319 } 320 321 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. 322 void AggExprEmitter::EmitFinalDestCopy(QualType type, const LValue &src, 323 ExprValueKind SrcValueKind) { 324 // If Dest is ignored, then we're evaluating an aggregate expression 325 // in a context that doesn't care about the result. Note that loads 326 // from volatile l-values force the existence of a non-ignored 327 // destination. 328 if (Dest.isIgnored()) 329 return; 330 331 // Copy non-trivial C structs here. 332 LValue DstLV = CGF.MakeAddrLValue( 333 Dest.getAddress(), Dest.isVolatile() ? type.withVolatile() : type); 334 335 if (SrcValueKind == EVK_RValue) { 336 if (type.isNonTrivialToPrimitiveDestructiveMove() == QualType::PCK_Struct) { 337 if (Dest.isPotentiallyAliased()) 338 CGF.callCStructMoveAssignmentOperator(DstLV, src); 339 else 340 CGF.callCStructMoveConstructor(DstLV, src); 341 return; 342 } 343 } else { 344 if (type.isNonTrivialToPrimitiveCopy() == QualType::PCK_Struct) { 345 if (Dest.isPotentiallyAliased()) 346 CGF.callCStructCopyAssignmentOperator(DstLV, src); 347 else 348 CGF.callCStructCopyConstructor(DstLV, src); 349 return; 350 } 351 } 352 353 AggValueSlot srcAgg = AggValueSlot::forLValue( 354 src, CGF, AggValueSlot::IsDestructed, needsGC(type), 355 AggValueSlot::IsAliased, AggValueSlot::MayOverlap); 356 EmitCopy(type, Dest, srcAgg); 357 } 358 359 /// Perform a copy from the source into the destination. 360 /// 361 /// \param type - the type of the aggregate being copied; qualifiers are 362 /// ignored 363 void AggExprEmitter::EmitCopy(QualType type, const AggValueSlot &dest, 364 const AggValueSlot &src) { 365 if (dest.requiresGCollection()) { 366 CharUnits sz = dest.getPreferredSize(CGF.getContext(), type); 367 llvm::Value *size = llvm::ConstantInt::get(CGF.SizeTy, sz.getQuantity()); 368 CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF, 369 dest.getAddress(), 370 src.getAddress(), 371 size); 372 return; 373 } 374 375 // If the result of the assignment is used, copy the LHS there also. 376 // It's volatile if either side is. Use the minimum alignment of 377 // the two sides. 378 LValue DestLV = CGF.MakeAddrLValue(dest.getAddress(), type); 379 LValue SrcLV = CGF.MakeAddrLValue(src.getAddress(), type); 380 CGF.EmitAggregateCopy(DestLV, SrcLV, type, dest.mayOverlap(), 381 dest.isVolatile() || src.isVolatile()); 382 } 383 384 /// Emit the initializer for a std::initializer_list initialized with a 385 /// real initializer list. 386 void 387 AggExprEmitter::VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E) { 388 // Emit an array containing the elements. The array is externally destructed 389 // if the std::initializer_list object is. 390 ASTContext &Ctx = CGF.getContext(); 391 LValue Array = CGF.EmitLValue(E->getSubExpr()); 392 assert(Array.isSimple() && "initializer_list array not a simple lvalue"); 393 Address ArrayPtr = Array.getAddress(CGF); 394 395 const ConstantArrayType *ArrayType = 396 Ctx.getAsConstantArrayType(E->getSubExpr()->getType()); 397 assert(ArrayType && "std::initializer_list constructed from non-array"); 398 399 // FIXME: Perform the checks on the field types in SemaInit. 400 RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl(); 401 RecordDecl::field_iterator Field = Record->field_begin(); 402 if (Field == Record->field_end()) { 403 CGF.ErrorUnsupported(E, "weird std::initializer_list"); 404 return; 405 } 406 407 // Start pointer. 408 if (!Field->getType()->isPointerType() || 409 !Ctx.hasSameType(Field->getType()->getPointeeType(), 410 ArrayType->getElementType())) { 411 CGF.ErrorUnsupported(E, "weird std::initializer_list"); 412 return; 413 } 414 415 AggValueSlot Dest = EnsureSlot(E->getType()); 416 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType()); 417 LValue Start = CGF.EmitLValueForFieldInitialization(DestLV, *Field); 418 llvm::Value *Zero = llvm::ConstantInt::get(CGF.PtrDiffTy, 0); 419 llvm::Value *IdxStart[] = { Zero, Zero }; 420 llvm::Value *ArrayStart = 421 Builder.CreateInBoundsGEP(ArrayPtr.getPointer(), IdxStart, "arraystart"); 422 CGF.EmitStoreThroughLValue(RValue::get(ArrayStart), Start); 423 ++Field; 424 425 if (Field == Record->field_end()) { 426 CGF.ErrorUnsupported(E, "weird std::initializer_list"); 427 return; 428 } 429 430 llvm::Value *Size = Builder.getInt(ArrayType->getSize()); 431 LValue EndOrLength = CGF.EmitLValueForFieldInitialization(DestLV, *Field); 432 if (Field->getType()->isPointerType() && 433 Ctx.hasSameType(Field->getType()->getPointeeType(), 434 ArrayType->getElementType())) { 435 // End pointer. 436 llvm::Value *IdxEnd[] = { Zero, Size }; 437 llvm::Value *ArrayEnd = 438 Builder.CreateInBoundsGEP(ArrayPtr.getPointer(), IdxEnd, "arrayend"); 439 CGF.EmitStoreThroughLValue(RValue::get(ArrayEnd), EndOrLength); 440 } else if (Ctx.hasSameType(Field->getType(), Ctx.getSizeType())) { 441 // Length. 442 CGF.EmitStoreThroughLValue(RValue::get(Size), EndOrLength); 443 } else { 444 CGF.ErrorUnsupported(E, "weird std::initializer_list"); 445 return; 446 } 447 } 448 449 /// Determine if E is a trivial array filler, that is, one that is 450 /// equivalent to zero-initialization. 451 static bool isTrivialFiller(Expr *E) { 452 if (!E) 453 return true; 454 455 if (isa<ImplicitValueInitExpr>(E)) 456 return true; 457 458 if (auto *ILE = dyn_cast<InitListExpr>(E)) { 459 if (ILE->getNumInits()) 460 return false; 461 return isTrivialFiller(ILE->getArrayFiller()); 462 } 463 464 if (auto *Cons = dyn_cast_or_null<CXXConstructExpr>(E)) 465 return Cons->getConstructor()->isDefaultConstructor() && 466 Cons->getConstructor()->isTrivial(); 467 468 // FIXME: Are there other cases where we can avoid emitting an initializer? 469 return false; 470 } 471 472 /// Emit initialization of an array from an initializer list. 473 void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType, 474 QualType ArrayQTy, InitListExpr *E) { 475 uint64_t NumInitElements = E->getNumInits(); 476 477 uint64_t NumArrayElements = AType->getNumElements(); 478 assert(NumInitElements <= NumArrayElements); 479 480 QualType elementType = 481 CGF.getContext().getAsArrayType(ArrayQTy)->getElementType(); 482 483 // DestPtr is an array*. Construct an elementType* by drilling 484 // down a level. 485 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0); 486 llvm::Value *indices[] = { zero, zero }; 487 llvm::Value *begin = 488 Builder.CreateInBoundsGEP(DestPtr.getPointer(), indices, "arrayinit.begin"); 489 490 CharUnits elementSize = CGF.getContext().getTypeSizeInChars(elementType); 491 CharUnits elementAlign = 492 DestPtr.getAlignment().alignmentOfArrayElement(elementSize); 493 494 // Consider initializing the array by copying from a global. For this to be 495 // more efficient than per-element initialization, the size of the elements 496 // with explicit initializers should be large enough. 497 if (NumInitElements * elementSize.getQuantity() > 16 && 498 elementType.isTriviallyCopyableType(CGF.getContext())) { 499 CodeGen::CodeGenModule &CGM = CGF.CGM; 500 ConstantEmitter Emitter(CGF); 501 LangAS AS = ArrayQTy.getAddressSpace(); 502 if (llvm::Constant *C = Emitter.tryEmitForInitializer(E, AS, ArrayQTy)) { 503 auto GV = new llvm::GlobalVariable( 504 CGM.getModule(), C->getType(), 505 CGM.isTypeConstant(ArrayQTy, /* ExcludeCtorDtor= */ true), 506 llvm::GlobalValue::PrivateLinkage, C, "constinit", 507 /* InsertBefore= */ nullptr, llvm::GlobalVariable::NotThreadLocal, 508 CGM.getContext().getTargetAddressSpace(AS)); 509 Emitter.finalize(GV); 510 CharUnits Align = CGM.getContext().getTypeAlignInChars(ArrayQTy); 511 GV->setAlignment(Align.getAsAlign()); 512 EmitFinalDestCopy(ArrayQTy, CGF.MakeAddrLValue(GV, ArrayQTy, Align)); 513 return; 514 } 515 } 516 517 // Exception safety requires us to destroy all the 518 // already-constructed members if an initializer throws. 519 // For that, we'll need an EH cleanup. 520 QualType::DestructionKind dtorKind = elementType.isDestructedType(); 521 Address endOfInit = Address::invalid(); 522 EHScopeStack::stable_iterator cleanup; 523 llvm::Instruction *cleanupDominator = nullptr; 524 if (CGF.needsEHCleanup(dtorKind)) { 525 // In principle we could tell the cleanup where we are more 526 // directly, but the control flow can get so varied here that it 527 // would actually be quite complex. Therefore we go through an 528 // alloca. 529 endOfInit = CGF.CreateTempAlloca(begin->getType(), CGF.getPointerAlign(), 530 "arrayinit.endOfInit"); 531 cleanupDominator = Builder.CreateStore(begin, endOfInit); 532 CGF.pushIrregularPartialArrayCleanup(begin, endOfInit, elementType, 533 elementAlign, 534 CGF.getDestroyer(dtorKind)); 535 cleanup = CGF.EHStack.stable_begin(); 536 537 // Otherwise, remember that we didn't need a cleanup. 538 } else { 539 dtorKind = QualType::DK_none; 540 } 541 542 llvm::Value *one = llvm::ConstantInt::get(CGF.SizeTy, 1); 543 544 // The 'current element to initialize'. The invariants on this 545 // variable are complicated. Essentially, after each iteration of 546 // the loop, it points to the last initialized element, except 547 // that it points to the beginning of the array before any 548 // elements have been initialized. 549 llvm::Value *element = begin; 550 551 // Emit the explicit initializers. 552 for (uint64_t i = 0; i != NumInitElements; ++i) { 553 // Advance to the next element. 554 if (i > 0) { 555 element = Builder.CreateInBoundsGEP(element, one, "arrayinit.element"); 556 557 // Tell the cleanup that it needs to destroy up to this 558 // element. TODO: some of these stores can be trivially 559 // observed to be unnecessary. 560 if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit); 561 } 562 563 LValue elementLV = 564 CGF.MakeAddrLValue(Address(element, elementAlign), elementType); 565 EmitInitializationToLValue(E->getInit(i), elementLV); 566 } 567 568 // Check whether there's a non-trivial array-fill expression. 569 Expr *filler = E->getArrayFiller(); 570 bool hasTrivialFiller = isTrivialFiller(filler); 571 572 // Any remaining elements need to be zero-initialized, possibly 573 // using the filler expression. We can skip this if the we're 574 // emitting to zeroed memory. 575 if (NumInitElements != NumArrayElements && 576 !(Dest.isZeroed() && hasTrivialFiller && 577 CGF.getTypes().isZeroInitializable(elementType))) { 578 579 // Use an actual loop. This is basically 580 // do { *array++ = filler; } while (array != end); 581 582 // Advance to the start of the rest of the array. 583 if (NumInitElements) { 584 element = Builder.CreateInBoundsGEP(element, one, "arrayinit.start"); 585 if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit); 586 } 587 588 // Compute the end of the array. 589 llvm::Value *end = Builder.CreateInBoundsGEP(begin, 590 llvm::ConstantInt::get(CGF.SizeTy, NumArrayElements), 591 "arrayinit.end"); 592 593 llvm::BasicBlock *entryBB = Builder.GetInsertBlock(); 594 llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body"); 595 596 // Jump into the body. 597 CGF.EmitBlock(bodyBB); 598 llvm::PHINode *currentElement = 599 Builder.CreatePHI(element->getType(), 2, "arrayinit.cur"); 600 currentElement->addIncoming(element, entryBB); 601 602 // Emit the actual filler expression. 603 { 604 // C++1z [class.temporary]p5: 605 // when a default constructor is called to initialize an element of 606 // an array with no corresponding initializer [...] the destruction of 607 // every temporary created in a default argument is sequenced before 608 // the construction of the next array element, if any 609 CodeGenFunction::RunCleanupsScope CleanupsScope(CGF); 610 LValue elementLV = 611 CGF.MakeAddrLValue(Address(currentElement, elementAlign), elementType); 612 if (filler) 613 EmitInitializationToLValue(filler, elementLV); 614 else 615 EmitNullInitializationToLValue(elementLV); 616 } 617 618 // Move on to the next element. 619 llvm::Value *nextElement = 620 Builder.CreateInBoundsGEP(currentElement, one, "arrayinit.next"); 621 622 // Tell the EH cleanup that we finished with the last element. 623 if (endOfInit.isValid()) Builder.CreateStore(nextElement, endOfInit); 624 625 // Leave the loop if we're done. 626 llvm::Value *done = Builder.CreateICmpEQ(nextElement, end, 627 "arrayinit.done"); 628 llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end"); 629 Builder.CreateCondBr(done, endBB, bodyBB); 630 currentElement->addIncoming(nextElement, Builder.GetInsertBlock()); 631 632 CGF.EmitBlock(endBB); 633 } 634 635 // Leave the partial-array cleanup if we entered one. 636 if (dtorKind) CGF.DeactivateCleanupBlock(cleanup, cleanupDominator); 637 } 638 639 //===----------------------------------------------------------------------===// 640 // Visitor Methods 641 //===----------------------------------------------------------------------===// 642 643 void AggExprEmitter::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E){ 644 Visit(E->getSubExpr()); 645 } 646 647 void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) { 648 // If this is a unique OVE, just visit its source expression. 649 if (e->isUnique()) 650 Visit(e->getSourceExpr()); 651 else 652 EmitFinalDestCopy(e->getType(), CGF.getOrCreateOpaqueLValueMapping(e)); 653 } 654 655 void 656 AggExprEmitter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { 657 if (Dest.isPotentiallyAliased() && 658 E->getType().isPODType(CGF.getContext())) { 659 // For a POD type, just emit a load of the lvalue + a copy, because our 660 // compound literal might alias the destination. 661 EmitAggLoadOfLValue(E); 662 return; 663 } 664 665 AggValueSlot Slot = EnsureSlot(E->getType()); 666 667 // Block-scope compound literals are destroyed at the end of the enclosing 668 // scope in C. 669 bool Destruct = 670 !CGF.getLangOpts().CPlusPlus && !Slot.isExternallyDestructed(); 671 if (Destruct) 672 Slot.setExternallyDestructed(); 673 674 CGF.EmitAggExpr(E->getInitializer(), Slot); 675 676 if (Destruct) 677 if (QualType::DestructionKind DtorKind = E->getType().isDestructedType()) 678 CGF.pushLifetimeExtendedDestroy( 679 CGF.getCleanupKind(DtorKind), Slot.getAddress(), E->getType(), 680 CGF.getDestroyer(DtorKind), DtorKind & EHCleanup); 681 } 682 683 /// Attempt to look through various unimportant expressions to find a 684 /// cast of the given kind. 685 static Expr *findPeephole(Expr *op, CastKind kind, const ASTContext &ctx) { 686 op = op->IgnoreParenNoopCasts(ctx); 687 if (auto castE = dyn_cast<CastExpr>(op)) { 688 if (castE->getCastKind() == kind) 689 return castE->getSubExpr(); 690 } 691 return nullptr; 692 } 693 694 void AggExprEmitter::VisitCastExpr(CastExpr *E) { 695 if (const auto *ECE = dyn_cast<ExplicitCastExpr>(E)) 696 CGF.CGM.EmitExplicitCastExprType(ECE, &CGF); 697 switch (E->getCastKind()) { 698 case CK_Dynamic: { 699 // FIXME: Can this actually happen? We have no test coverage for it. 700 assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?"); 701 LValue LV = CGF.EmitCheckedLValue(E->getSubExpr(), 702 CodeGenFunction::TCK_Load); 703 // FIXME: Do we also need to handle property references here? 704 if (LV.isSimple()) 705 CGF.EmitDynamicCast(LV.getAddress(CGF), cast<CXXDynamicCastExpr>(E)); 706 else 707 CGF.CGM.ErrorUnsupported(E, "non-simple lvalue dynamic_cast"); 708 709 if (!Dest.isIgnored()) 710 CGF.CGM.ErrorUnsupported(E, "lvalue dynamic_cast with a destination"); 711 break; 712 } 713 714 case CK_ToUnion: { 715 // Evaluate even if the destination is ignored. 716 if (Dest.isIgnored()) { 717 CGF.EmitAnyExpr(E->getSubExpr(), AggValueSlot::ignored(), 718 /*ignoreResult=*/true); 719 break; 720 } 721 722 // GCC union extension 723 QualType Ty = E->getSubExpr()->getType(); 724 Address CastPtr = 725 Builder.CreateElementBitCast(Dest.getAddress(), CGF.ConvertType(Ty)); 726 EmitInitializationToLValue(E->getSubExpr(), 727 CGF.MakeAddrLValue(CastPtr, Ty)); 728 break; 729 } 730 731 case CK_LValueToRValueBitCast: { 732 if (Dest.isIgnored()) { 733 CGF.EmitAnyExpr(E->getSubExpr(), AggValueSlot::ignored(), 734 /*ignoreResult=*/true); 735 break; 736 } 737 738 LValue SourceLV = CGF.EmitLValue(E->getSubExpr()); 739 Address SourceAddress = 740 Builder.CreateElementBitCast(SourceLV.getAddress(CGF), CGF.Int8Ty); 741 Address DestAddress = 742 Builder.CreateElementBitCast(Dest.getAddress(), CGF.Int8Ty); 743 llvm::Value *SizeVal = llvm::ConstantInt::get( 744 CGF.SizeTy, 745 CGF.getContext().getTypeSizeInChars(E->getType()).getQuantity()); 746 Builder.CreateMemCpy(DestAddress, SourceAddress, SizeVal); 747 break; 748 } 749 750 case CK_DerivedToBase: 751 case CK_BaseToDerived: 752 case CK_UncheckedDerivedToBase: { 753 llvm_unreachable("cannot perform hierarchy conversion in EmitAggExpr: " 754 "should have been unpacked before we got here"); 755 } 756 757 case CK_NonAtomicToAtomic: 758 case CK_AtomicToNonAtomic: { 759 bool isToAtomic = (E->getCastKind() == CK_NonAtomicToAtomic); 760 761 // Determine the atomic and value types. 762 QualType atomicType = E->getSubExpr()->getType(); 763 QualType valueType = E->getType(); 764 if (isToAtomic) std::swap(atomicType, valueType); 765 766 assert(atomicType->isAtomicType()); 767 assert(CGF.getContext().hasSameUnqualifiedType(valueType, 768 atomicType->castAs<AtomicType>()->getValueType())); 769 770 // Just recurse normally if we're ignoring the result or the 771 // atomic type doesn't change representation. 772 if (Dest.isIgnored() || !CGF.CGM.isPaddedAtomicType(atomicType)) { 773 return Visit(E->getSubExpr()); 774 } 775 776 CastKind peepholeTarget = 777 (isToAtomic ? CK_AtomicToNonAtomic : CK_NonAtomicToAtomic); 778 779 // These two cases are reverses of each other; try to peephole them. 780 if (Expr *op = 781 findPeephole(E->getSubExpr(), peepholeTarget, CGF.getContext())) { 782 assert(CGF.getContext().hasSameUnqualifiedType(op->getType(), 783 E->getType()) && 784 "peephole significantly changed types?"); 785 return Visit(op); 786 } 787 788 // If we're converting an r-value of non-atomic type to an r-value 789 // of atomic type, just emit directly into the relevant sub-object. 790 if (isToAtomic) { 791 AggValueSlot valueDest = Dest; 792 if (!valueDest.isIgnored() && CGF.CGM.isPaddedAtomicType(atomicType)) { 793 // Zero-initialize. (Strictly speaking, we only need to initialize 794 // the padding at the end, but this is simpler.) 795 if (!Dest.isZeroed()) 796 CGF.EmitNullInitialization(Dest.getAddress(), atomicType); 797 798 // Build a GEP to refer to the subobject. 799 Address valueAddr = 800 CGF.Builder.CreateStructGEP(valueDest.getAddress(), 0); 801 valueDest = AggValueSlot::forAddr(valueAddr, 802 valueDest.getQualifiers(), 803 valueDest.isExternallyDestructed(), 804 valueDest.requiresGCollection(), 805 valueDest.isPotentiallyAliased(), 806 AggValueSlot::DoesNotOverlap, 807 AggValueSlot::IsZeroed); 808 } 809 810 CGF.EmitAggExpr(E->getSubExpr(), valueDest); 811 return; 812 } 813 814 // Otherwise, we're converting an atomic type to a non-atomic type. 815 // Make an atomic temporary, emit into that, and then copy the value out. 816 AggValueSlot atomicSlot = 817 CGF.CreateAggTemp(atomicType, "atomic-to-nonatomic.temp"); 818 CGF.EmitAggExpr(E->getSubExpr(), atomicSlot); 819 820 Address valueAddr = Builder.CreateStructGEP(atomicSlot.getAddress(), 0); 821 RValue rvalue = RValue::getAggregate(valueAddr, atomicSlot.isVolatile()); 822 return EmitFinalDestCopy(valueType, rvalue); 823 } 824 case CK_AddressSpaceConversion: 825 return Visit(E->getSubExpr()); 826 827 case CK_LValueToRValue: 828 // If we're loading from a volatile type, force the destination 829 // into existence. 830 if (E->getSubExpr()->getType().isVolatileQualified()) { 831 bool Destruct = 832 !Dest.isExternallyDestructed() && 833 E->getType().isDestructedType() == QualType::DK_nontrivial_c_struct; 834 if (Destruct) 835 Dest.setExternallyDestructed(); 836 EnsureDest(E->getType()); 837 Visit(E->getSubExpr()); 838 839 if (Destruct) 840 CGF.pushDestroy(QualType::DK_nontrivial_c_struct, Dest.getAddress(), 841 E->getType()); 842 843 return; 844 } 845 846 LLVM_FALLTHROUGH; 847 848 849 case CK_NoOp: 850 case CK_UserDefinedConversion: 851 case CK_ConstructorConversion: 852 assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(), 853 E->getType()) && 854 "Implicit cast types must be compatible"); 855 Visit(E->getSubExpr()); 856 break; 857 858 case CK_LValueBitCast: 859 llvm_unreachable("should not be emitting lvalue bitcast as rvalue"); 860 861 case CK_Dependent: 862 case CK_BitCast: 863 case CK_ArrayToPointerDecay: 864 case CK_FunctionToPointerDecay: 865 case CK_NullToPointer: 866 case CK_NullToMemberPointer: 867 case CK_BaseToDerivedMemberPointer: 868 case CK_DerivedToBaseMemberPointer: 869 case CK_MemberPointerToBoolean: 870 case CK_ReinterpretMemberPointer: 871 case CK_IntegralToPointer: 872 case CK_PointerToIntegral: 873 case CK_PointerToBoolean: 874 case CK_ToVoid: 875 case CK_VectorSplat: 876 case CK_IntegralCast: 877 case CK_BooleanToSignedIntegral: 878 case CK_IntegralToBoolean: 879 case CK_IntegralToFloating: 880 case CK_FloatingToIntegral: 881 case CK_FloatingToBoolean: 882 case CK_FloatingCast: 883 case CK_CPointerToObjCPointerCast: 884 case CK_BlockPointerToObjCPointerCast: 885 case CK_AnyPointerToBlockPointerCast: 886 case CK_ObjCObjectLValueCast: 887 case CK_FloatingRealToComplex: 888 case CK_FloatingComplexToReal: 889 case CK_FloatingComplexToBoolean: 890 case CK_FloatingComplexCast: 891 case CK_FloatingComplexToIntegralComplex: 892 case CK_IntegralRealToComplex: 893 case CK_IntegralComplexToReal: 894 case CK_IntegralComplexToBoolean: 895 case CK_IntegralComplexCast: 896 case CK_IntegralComplexToFloatingComplex: 897 case CK_ARCProduceObject: 898 case CK_ARCConsumeObject: 899 case CK_ARCReclaimReturnedObject: 900 case CK_ARCExtendBlockObject: 901 case CK_CopyAndAutoreleaseBlockObject: 902 case CK_BuiltinFnToFnPtr: 903 case CK_ZeroToOCLOpaqueType: 904 905 case CK_IntToOCLSampler: 906 case CK_FixedPointCast: 907 case CK_FixedPointToBoolean: 908 case CK_FixedPointToIntegral: 909 case CK_IntegralToFixedPoint: 910 llvm_unreachable("cast kind invalid for aggregate types"); 911 } 912 } 913 914 void AggExprEmitter::VisitCallExpr(const CallExpr *E) { 915 if (E->getCallReturnType(CGF.getContext())->isReferenceType()) { 916 EmitAggLoadOfLValue(E); 917 return; 918 } 919 920 withReturnValueSlot(E, [&](ReturnValueSlot Slot) { 921 return CGF.EmitCallExpr(E, Slot); 922 }); 923 } 924 925 void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) { 926 withReturnValueSlot(E, [&](ReturnValueSlot Slot) { 927 return CGF.EmitObjCMessageExpr(E, Slot); 928 }); 929 } 930 931 void AggExprEmitter::VisitBinComma(const BinaryOperator *E) { 932 CGF.EmitIgnoredExpr(E->getLHS()); 933 Visit(E->getRHS()); 934 } 935 936 void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) { 937 CodeGenFunction::StmtExprEvaluation eval(CGF); 938 CGF.EmitCompoundStmt(*E->getSubStmt(), true, Dest); 939 } 940 941 enum CompareKind { 942 CK_Less, 943 CK_Greater, 944 CK_Equal, 945 }; 946 947 static llvm::Value *EmitCompare(CGBuilderTy &Builder, CodeGenFunction &CGF, 948 const BinaryOperator *E, llvm::Value *LHS, 949 llvm::Value *RHS, CompareKind Kind, 950 const char *NameSuffix = "") { 951 QualType ArgTy = E->getLHS()->getType(); 952 if (const ComplexType *CT = ArgTy->getAs<ComplexType>()) 953 ArgTy = CT->getElementType(); 954 955 if (const auto *MPT = ArgTy->getAs<MemberPointerType>()) { 956 assert(Kind == CK_Equal && 957 "member pointers may only be compared for equality"); 958 return CGF.CGM.getCXXABI().EmitMemberPointerComparison( 959 CGF, LHS, RHS, MPT, /*IsInequality*/ false); 960 } 961 962 // Compute the comparison instructions for the specified comparison kind. 963 struct CmpInstInfo { 964 const char *Name; 965 llvm::CmpInst::Predicate FCmp; 966 llvm::CmpInst::Predicate SCmp; 967 llvm::CmpInst::Predicate UCmp; 968 }; 969 CmpInstInfo InstInfo = [&]() -> CmpInstInfo { 970 using FI = llvm::FCmpInst; 971 using II = llvm::ICmpInst; 972 switch (Kind) { 973 case CK_Less: 974 return {"cmp.lt", FI::FCMP_OLT, II::ICMP_SLT, II::ICMP_ULT}; 975 case CK_Greater: 976 return {"cmp.gt", FI::FCMP_OGT, II::ICMP_SGT, II::ICMP_UGT}; 977 case CK_Equal: 978 return {"cmp.eq", FI::FCMP_OEQ, II::ICMP_EQ, II::ICMP_EQ}; 979 } 980 llvm_unreachable("Unrecognised CompareKind enum"); 981 }(); 982 983 if (ArgTy->hasFloatingRepresentation()) 984 return Builder.CreateFCmp(InstInfo.FCmp, LHS, RHS, 985 llvm::Twine(InstInfo.Name) + NameSuffix); 986 if (ArgTy->isIntegralOrEnumerationType() || ArgTy->isPointerType()) { 987 auto Inst = 988 ArgTy->hasSignedIntegerRepresentation() ? InstInfo.SCmp : InstInfo.UCmp; 989 return Builder.CreateICmp(Inst, LHS, RHS, 990 llvm::Twine(InstInfo.Name) + NameSuffix); 991 } 992 993 llvm_unreachable("unsupported aggregate binary expression should have " 994 "already been handled"); 995 } 996 997 void AggExprEmitter::VisitBinCmp(const BinaryOperator *E) { 998 using llvm::BasicBlock; 999 using llvm::PHINode; 1000 using llvm::Value; 1001 assert(CGF.getContext().hasSameType(E->getLHS()->getType(), 1002 E->getRHS()->getType())); 1003 const ComparisonCategoryInfo &CmpInfo = 1004 CGF.getContext().CompCategories.getInfoForType(E->getType()); 1005 assert(CmpInfo.Record->isTriviallyCopyable() && 1006 "cannot copy non-trivially copyable aggregate"); 1007 1008 QualType ArgTy = E->getLHS()->getType(); 1009 1010 if (!ArgTy->isIntegralOrEnumerationType() && !ArgTy->isRealFloatingType() && 1011 !ArgTy->isNullPtrType() && !ArgTy->isPointerType() && 1012 !ArgTy->isMemberPointerType() && !ArgTy->isAnyComplexType()) { 1013 return CGF.ErrorUnsupported(E, "aggregate three-way comparison"); 1014 } 1015 bool IsComplex = ArgTy->isAnyComplexType(); 1016 1017 // Evaluate the operands to the expression and extract their values. 1018 auto EmitOperand = [&](Expr *E) -> std::pair<Value *, Value *> { 1019 RValue RV = CGF.EmitAnyExpr(E); 1020 if (RV.isScalar()) 1021 return {RV.getScalarVal(), nullptr}; 1022 if (RV.isAggregate()) 1023 return {RV.getAggregatePointer(), nullptr}; 1024 assert(RV.isComplex()); 1025 return RV.getComplexVal(); 1026 }; 1027 auto LHSValues = EmitOperand(E->getLHS()), 1028 RHSValues = EmitOperand(E->getRHS()); 1029 1030 auto EmitCmp = [&](CompareKind K) { 1031 Value *Cmp = EmitCompare(Builder, CGF, E, LHSValues.first, RHSValues.first, 1032 K, IsComplex ? ".r" : ""); 1033 if (!IsComplex) 1034 return Cmp; 1035 assert(K == CompareKind::CK_Equal); 1036 Value *CmpImag = EmitCompare(Builder, CGF, E, LHSValues.second, 1037 RHSValues.second, K, ".i"); 1038 return Builder.CreateAnd(Cmp, CmpImag, "and.eq"); 1039 }; 1040 auto EmitCmpRes = [&](const ComparisonCategoryInfo::ValueInfo *VInfo) { 1041 return Builder.getInt(VInfo->getIntValue()); 1042 }; 1043 1044 Value *Select; 1045 if (ArgTy->isNullPtrType()) { 1046 Select = EmitCmpRes(CmpInfo.getEqualOrEquiv()); 1047 } else if (!CmpInfo.isPartial()) { 1048 Value *SelectOne = 1049 Builder.CreateSelect(EmitCmp(CK_Less), EmitCmpRes(CmpInfo.getLess()), 1050 EmitCmpRes(CmpInfo.getGreater()), "sel.lt"); 1051 Select = Builder.CreateSelect(EmitCmp(CK_Equal), 1052 EmitCmpRes(CmpInfo.getEqualOrEquiv()), 1053 SelectOne, "sel.eq"); 1054 } else { 1055 Value *SelectEq = Builder.CreateSelect( 1056 EmitCmp(CK_Equal), EmitCmpRes(CmpInfo.getEqualOrEquiv()), 1057 EmitCmpRes(CmpInfo.getUnordered()), "sel.eq"); 1058 Value *SelectGT = Builder.CreateSelect(EmitCmp(CK_Greater), 1059 EmitCmpRes(CmpInfo.getGreater()), 1060 SelectEq, "sel.gt"); 1061 Select = Builder.CreateSelect( 1062 EmitCmp(CK_Less), EmitCmpRes(CmpInfo.getLess()), SelectGT, "sel.lt"); 1063 } 1064 // Create the return value in the destination slot. 1065 EnsureDest(E->getType()); 1066 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType()); 1067 1068 // Emit the address of the first (and only) field in the comparison category 1069 // type, and initialize it from the constant integer value selected above. 1070 LValue FieldLV = CGF.EmitLValueForFieldInitialization( 1071 DestLV, *CmpInfo.Record->field_begin()); 1072 CGF.EmitStoreThroughLValue(RValue::get(Select), FieldLV, /*IsInit*/ true); 1073 1074 // All done! The result is in the Dest slot. 1075 } 1076 1077 void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) { 1078 if (E->getOpcode() == BO_PtrMemD || E->getOpcode() == BO_PtrMemI) 1079 VisitPointerToDataMemberBinaryOperator(E); 1080 else 1081 CGF.ErrorUnsupported(E, "aggregate binary expression"); 1082 } 1083 1084 void AggExprEmitter::VisitPointerToDataMemberBinaryOperator( 1085 const BinaryOperator *E) { 1086 LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E); 1087 EmitFinalDestCopy(E->getType(), LV); 1088 } 1089 1090 /// Is the value of the given expression possibly a reference to or 1091 /// into a __block variable? 1092 static bool isBlockVarRef(const Expr *E) { 1093 // Make sure we look through parens. 1094 E = E->IgnoreParens(); 1095 1096 // Check for a direct reference to a __block variable. 1097 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) { 1098 const VarDecl *var = dyn_cast<VarDecl>(DRE->getDecl()); 1099 return (var && var->hasAttr<BlocksAttr>()); 1100 } 1101 1102 // More complicated stuff. 1103 1104 // Binary operators. 1105 if (const BinaryOperator *op = dyn_cast<BinaryOperator>(E)) { 1106 // For an assignment or pointer-to-member operation, just care 1107 // about the LHS. 1108 if (op->isAssignmentOp() || op->isPtrMemOp()) 1109 return isBlockVarRef(op->getLHS()); 1110 1111 // For a comma, just care about the RHS. 1112 if (op->getOpcode() == BO_Comma) 1113 return isBlockVarRef(op->getRHS()); 1114 1115 // FIXME: pointer arithmetic? 1116 return false; 1117 1118 // Check both sides of a conditional operator. 1119 } else if (const AbstractConditionalOperator *op 1120 = dyn_cast<AbstractConditionalOperator>(E)) { 1121 return isBlockVarRef(op->getTrueExpr()) 1122 || isBlockVarRef(op->getFalseExpr()); 1123 1124 // OVEs are required to support BinaryConditionalOperators. 1125 } else if (const OpaqueValueExpr *op 1126 = dyn_cast<OpaqueValueExpr>(E)) { 1127 if (const Expr *src = op->getSourceExpr()) 1128 return isBlockVarRef(src); 1129 1130 // Casts are necessary to get things like (*(int*)&var) = foo(). 1131 // We don't really care about the kind of cast here, except 1132 // we don't want to look through l2r casts, because it's okay 1133 // to get the *value* in a __block variable. 1134 } else if (const CastExpr *cast = dyn_cast<CastExpr>(E)) { 1135 if (cast->getCastKind() == CK_LValueToRValue) 1136 return false; 1137 return isBlockVarRef(cast->getSubExpr()); 1138 1139 // Handle unary operators. Again, just aggressively look through 1140 // it, ignoring the operation. 1141 } else if (const UnaryOperator *uop = dyn_cast<UnaryOperator>(E)) { 1142 return isBlockVarRef(uop->getSubExpr()); 1143 1144 // Look into the base of a field access. 1145 } else if (const MemberExpr *mem = dyn_cast<MemberExpr>(E)) { 1146 return isBlockVarRef(mem->getBase()); 1147 1148 // Look into the base of a subscript. 1149 } else if (const ArraySubscriptExpr *sub = dyn_cast<ArraySubscriptExpr>(E)) { 1150 return isBlockVarRef(sub->getBase()); 1151 } 1152 1153 return false; 1154 } 1155 1156 void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) { 1157 // For an assignment to work, the value on the right has 1158 // to be compatible with the value on the left. 1159 assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(), 1160 E->getRHS()->getType()) 1161 && "Invalid assignment"); 1162 1163 // If the LHS might be a __block variable, and the RHS can 1164 // potentially cause a block copy, we need to evaluate the RHS first 1165 // so that the assignment goes the right place. 1166 // This is pretty semantically fragile. 1167 if (isBlockVarRef(E->getLHS()) && 1168 E->getRHS()->HasSideEffects(CGF.getContext())) { 1169 // Ensure that we have a destination, and evaluate the RHS into that. 1170 EnsureDest(E->getRHS()->getType()); 1171 Visit(E->getRHS()); 1172 1173 // Now emit the LHS and copy into it. 1174 LValue LHS = CGF.EmitCheckedLValue(E->getLHS(), CodeGenFunction::TCK_Store); 1175 1176 // That copy is an atomic copy if the LHS is atomic. 1177 if (LHS.getType()->isAtomicType() || 1178 CGF.LValueIsSuitableForInlineAtomic(LHS)) { 1179 CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false); 1180 return; 1181 } 1182 1183 EmitCopy(E->getLHS()->getType(), 1184 AggValueSlot::forLValue(LHS, CGF, AggValueSlot::IsDestructed, 1185 needsGC(E->getLHS()->getType()), 1186 AggValueSlot::IsAliased, 1187 AggValueSlot::MayOverlap), 1188 Dest); 1189 return; 1190 } 1191 1192 LValue LHS = CGF.EmitLValue(E->getLHS()); 1193 1194 // If we have an atomic type, evaluate into the destination and then 1195 // do an atomic copy. 1196 if (LHS.getType()->isAtomicType() || 1197 CGF.LValueIsSuitableForInlineAtomic(LHS)) { 1198 EnsureDest(E->getRHS()->getType()); 1199 Visit(E->getRHS()); 1200 CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false); 1201 return; 1202 } 1203 1204 // Codegen the RHS so that it stores directly into the LHS. 1205 AggValueSlot LHSSlot = AggValueSlot::forLValue( 1206 LHS, CGF, AggValueSlot::IsDestructed, needsGC(E->getLHS()->getType()), 1207 AggValueSlot::IsAliased, AggValueSlot::MayOverlap); 1208 // A non-volatile aggregate destination might have volatile member. 1209 if (!LHSSlot.isVolatile() && 1210 CGF.hasVolatileMember(E->getLHS()->getType())) 1211 LHSSlot.setVolatile(true); 1212 1213 CGF.EmitAggExpr(E->getRHS(), LHSSlot); 1214 1215 // Copy into the destination if the assignment isn't ignored. 1216 EmitFinalDestCopy(E->getType(), LHS); 1217 } 1218 1219 void AggExprEmitter:: 1220 VisitAbstractConditionalOperator(const AbstractConditionalOperator *E) { 1221 llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true"); 1222 llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false"); 1223 llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end"); 1224 1225 // Bind the common expression if necessary. 1226 CodeGenFunction::OpaqueValueMapping binding(CGF, E); 1227 1228 CodeGenFunction::ConditionalEvaluation eval(CGF); 1229 CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock, 1230 CGF.getProfileCount(E)); 1231 1232 // Save whether the destination's lifetime is externally managed. 1233 bool isExternallyDestructed = Dest.isExternallyDestructed(); 1234 1235 eval.begin(CGF); 1236 CGF.EmitBlock(LHSBlock); 1237 CGF.incrementProfileCounter(E); 1238 Visit(E->getTrueExpr()); 1239 eval.end(CGF); 1240 1241 assert(CGF.HaveInsertPoint() && "expression evaluation ended with no IP!"); 1242 CGF.Builder.CreateBr(ContBlock); 1243 1244 // If the result of an agg expression is unused, then the emission 1245 // of the LHS might need to create a destination slot. That's fine 1246 // with us, and we can safely emit the RHS into the same slot, but 1247 // we shouldn't claim that it's already being destructed. 1248 Dest.setExternallyDestructed(isExternallyDestructed); 1249 1250 eval.begin(CGF); 1251 CGF.EmitBlock(RHSBlock); 1252 Visit(E->getFalseExpr()); 1253 eval.end(CGF); 1254 1255 CGF.EmitBlock(ContBlock); 1256 } 1257 1258 void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) { 1259 Visit(CE->getChosenSubExpr()); 1260 } 1261 1262 void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) { 1263 Address ArgValue = Address::invalid(); 1264 Address ArgPtr = CGF.EmitVAArg(VE, ArgValue); 1265 1266 // If EmitVAArg fails, emit an error. 1267 if (!ArgPtr.isValid()) { 1268 CGF.ErrorUnsupported(VE, "aggregate va_arg expression"); 1269 return; 1270 } 1271 1272 EmitFinalDestCopy(VE->getType(), CGF.MakeAddrLValue(ArgPtr, VE->getType())); 1273 } 1274 1275 void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) { 1276 // Ensure that we have a slot, but if we already do, remember 1277 // whether it was externally destructed. 1278 bool wasExternallyDestructed = Dest.isExternallyDestructed(); 1279 EnsureDest(E->getType()); 1280 1281 // We're going to push a destructor if there isn't already one. 1282 Dest.setExternallyDestructed(); 1283 1284 Visit(E->getSubExpr()); 1285 1286 // Push that destructor we promised. 1287 if (!wasExternallyDestructed) 1288 CGF.EmitCXXTemporary(E->getTemporary(), E->getType(), Dest.getAddress()); 1289 } 1290 1291 void 1292 AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) { 1293 AggValueSlot Slot = EnsureSlot(E->getType()); 1294 CGF.EmitCXXConstructExpr(E, Slot); 1295 } 1296 1297 void AggExprEmitter::VisitCXXInheritedCtorInitExpr( 1298 const CXXInheritedCtorInitExpr *E) { 1299 AggValueSlot Slot = EnsureSlot(E->getType()); 1300 CGF.EmitInheritedCXXConstructorCall( 1301 E->getConstructor(), E->constructsVBase(), Slot.getAddress(), 1302 E->inheritedFromVBase(), E); 1303 } 1304 1305 void 1306 AggExprEmitter::VisitLambdaExpr(LambdaExpr *E) { 1307 AggValueSlot Slot = EnsureSlot(E->getType()); 1308 LValue SlotLV = CGF.MakeAddrLValue(Slot.getAddress(), E->getType()); 1309 1310 // We'll need to enter cleanup scopes in case any of the element 1311 // initializers throws an exception. 1312 SmallVector<EHScopeStack::stable_iterator, 16> Cleanups; 1313 llvm::Instruction *CleanupDominator = nullptr; 1314 1315 CXXRecordDecl::field_iterator CurField = E->getLambdaClass()->field_begin(); 1316 for (LambdaExpr::const_capture_init_iterator i = E->capture_init_begin(), 1317 e = E->capture_init_end(); 1318 i != e; ++i, ++CurField) { 1319 // Emit initialization 1320 LValue LV = CGF.EmitLValueForFieldInitialization(SlotLV, *CurField); 1321 if (CurField->hasCapturedVLAType()) { 1322 CGF.EmitLambdaVLACapture(CurField->getCapturedVLAType(), LV); 1323 continue; 1324 } 1325 1326 EmitInitializationToLValue(*i, LV); 1327 1328 // Push a destructor if necessary. 1329 if (QualType::DestructionKind DtorKind = 1330 CurField->getType().isDestructedType()) { 1331 assert(LV.isSimple()); 1332 if (CGF.needsEHCleanup(DtorKind)) { 1333 if (!CleanupDominator) 1334 CleanupDominator = CGF.Builder.CreateAlignedLoad( 1335 CGF.Int8Ty, 1336 llvm::Constant::getNullValue(CGF.Int8PtrTy), 1337 CharUnits::One()); // placeholder 1338 1339 CGF.pushDestroy(EHCleanup, LV.getAddress(CGF), CurField->getType(), 1340 CGF.getDestroyer(DtorKind), false); 1341 Cleanups.push_back(CGF.EHStack.stable_begin()); 1342 } 1343 } 1344 } 1345 1346 // Deactivate all the partial cleanups in reverse order, which 1347 // generally means popping them. 1348 for (unsigned i = Cleanups.size(); i != 0; --i) 1349 CGF.DeactivateCleanupBlock(Cleanups[i-1], CleanupDominator); 1350 1351 // Destroy the placeholder if we made one. 1352 if (CleanupDominator) 1353 CleanupDominator->eraseFromParent(); 1354 } 1355 1356 void AggExprEmitter::VisitExprWithCleanups(ExprWithCleanups *E) { 1357 CodeGenFunction::RunCleanupsScope cleanups(CGF); 1358 Visit(E->getSubExpr()); 1359 } 1360 1361 void AggExprEmitter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) { 1362 QualType T = E->getType(); 1363 AggValueSlot Slot = EnsureSlot(T); 1364 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddress(), T)); 1365 } 1366 1367 void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) { 1368 QualType T = E->getType(); 1369 AggValueSlot Slot = EnsureSlot(T); 1370 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddress(), T)); 1371 } 1372 1373 /// isSimpleZero - If emitting this value will obviously just cause a store of 1374 /// zero to memory, return true. This can return false if uncertain, so it just 1375 /// handles simple cases. 1376 static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) { 1377 E = E->IgnoreParens(); 1378 1379 // 0 1380 if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E)) 1381 return IL->getValue() == 0; 1382 // +0.0 1383 if (const FloatingLiteral *FL = dyn_cast<FloatingLiteral>(E)) 1384 return FL->getValue().isPosZero(); 1385 // int() 1386 if ((isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) && 1387 CGF.getTypes().isZeroInitializable(E->getType())) 1388 return true; 1389 // (int*)0 - Null pointer expressions. 1390 if (const CastExpr *ICE = dyn_cast<CastExpr>(E)) 1391 return ICE->getCastKind() == CK_NullToPointer && 1392 CGF.getTypes().isPointerZeroInitializable(E->getType()) && 1393 !E->HasSideEffects(CGF.getContext()); 1394 // '\0' 1395 if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E)) 1396 return CL->getValue() == 0; 1397 1398 // Otherwise, hard case: conservatively return false. 1399 return false; 1400 } 1401 1402 1403 void 1404 AggExprEmitter::EmitInitializationToLValue(Expr *E, LValue LV) { 1405 QualType type = LV.getType(); 1406 // FIXME: Ignore result? 1407 // FIXME: Are initializers affected by volatile? 1408 if (Dest.isZeroed() && isSimpleZero(E, CGF)) { 1409 // Storing "i32 0" to a zero'd memory location is a noop. 1410 return; 1411 } else if (isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) { 1412 return EmitNullInitializationToLValue(LV); 1413 } else if (isa<NoInitExpr>(E)) { 1414 // Do nothing. 1415 return; 1416 } else if (type->isReferenceType()) { 1417 RValue RV = CGF.EmitReferenceBindingToExpr(E); 1418 return CGF.EmitStoreThroughLValue(RV, LV); 1419 } 1420 1421 switch (CGF.getEvaluationKind(type)) { 1422 case TEK_Complex: 1423 CGF.EmitComplexExprIntoLValue(E, LV, /*isInit*/ true); 1424 return; 1425 case TEK_Aggregate: 1426 CGF.EmitAggExpr( 1427 E, AggValueSlot::forLValue(LV, CGF, AggValueSlot::IsDestructed, 1428 AggValueSlot::DoesNotNeedGCBarriers, 1429 AggValueSlot::IsNotAliased, 1430 AggValueSlot::MayOverlap, Dest.isZeroed())); 1431 return; 1432 case TEK_Scalar: 1433 if (LV.isSimple()) { 1434 CGF.EmitScalarInit(E, /*D=*/nullptr, LV, /*Captured=*/false); 1435 } else { 1436 CGF.EmitStoreThroughLValue(RValue::get(CGF.EmitScalarExpr(E)), LV); 1437 } 1438 return; 1439 } 1440 llvm_unreachable("bad evaluation kind"); 1441 } 1442 1443 void AggExprEmitter::EmitNullInitializationToLValue(LValue lv) { 1444 QualType type = lv.getType(); 1445 1446 // If the destination slot is already zeroed out before the aggregate is 1447 // copied into it, we don't have to emit any zeros here. 1448 if (Dest.isZeroed() && CGF.getTypes().isZeroInitializable(type)) 1449 return; 1450 1451 if (CGF.hasScalarEvaluationKind(type)) { 1452 // For non-aggregates, we can store the appropriate null constant. 1453 llvm::Value *null = CGF.CGM.EmitNullConstant(type); 1454 // Note that the following is not equivalent to 1455 // EmitStoreThroughBitfieldLValue for ARC types. 1456 if (lv.isBitField()) { 1457 CGF.EmitStoreThroughBitfieldLValue(RValue::get(null), lv); 1458 } else { 1459 assert(lv.isSimple()); 1460 CGF.EmitStoreOfScalar(null, lv, /* isInitialization */ true); 1461 } 1462 } else { 1463 // There's a potential optimization opportunity in combining 1464 // memsets; that would be easy for arrays, but relatively 1465 // difficult for structures with the current code. 1466 CGF.EmitNullInitialization(lv.getAddress(CGF), lv.getType()); 1467 } 1468 } 1469 1470 void AggExprEmitter::VisitInitListExpr(InitListExpr *E) { 1471 #if 0 1472 // FIXME: Assess perf here? Figure out what cases are worth optimizing here 1473 // (Length of globals? Chunks of zeroed-out space?). 1474 // 1475 // If we can, prefer a copy from a global; this is a lot less code for long 1476 // globals, and it's easier for the current optimizers to analyze. 1477 if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) { 1478 llvm::GlobalVariable* GV = 1479 new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true, 1480 llvm::GlobalValue::InternalLinkage, C, ""); 1481 EmitFinalDestCopy(E->getType(), CGF.MakeAddrLValue(GV, E->getType())); 1482 return; 1483 } 1484 #endif 1485 if (E->hadArrayRangeDesignator()) 1486 CGF.ErrorUnsupported(E, "GNU array range designator extension"); 1487 1488 if (E->isTransparent()) 1489 return Visit(E->getInit(0)); 1490 1491 AggValueSlot Dest = EnsureSlot(E->getType()); 1492 1493 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType()); 1494 1495 // Handle initialization of an array. 1496 if (E->getType()->isArrayType()) { 1497 auto AType = cast<llvm::ArrayType>(Dest.getAddress().getElementType()); 1498 EmitArrayInit(Dest.getAddress(), AType, E->getType(), E); 1499 return; 1500 } 1501 1502 assert(E->getType()->isRecordType() && "Only support structs/unions here!"); 1503 1504 // Do struct initialization; this code just sets each individual member 1505 // to the approprate value. This makes bitfield support automatic; 1506 // the disadvantage is that the generated code is more difficult for 1507 // the optimizer, especially with bitfields. 1508 unsigned NumInitElements = E->getNumInits(); 1509 RecordDecl *record = E->getType()->castAs<RecordType>()->getDecl(); 1510 1511 // We'll need to enter cleanup scopes in case any of the element 1512 // initializers throws an exception. 1513 SmallVector<EHScopeStack::stable_iterator, 16> cleanups; 1514 llvm::Instruction *cleanupDominator = nullptr; 1515 auto addCleanup = [&](const EHScopeStack::stable_iterator &cleanup) { 1516 cleanups.push_back(cleanup); 1517 if (!cleanupDominator) // create placeholder once needed 1518 cleanupDominator = CGF.Builder.CreateAlignedLoad( 1519 CGF.Int8Ty, llvm::Constant::getNullValue(CGF.Int8PtrTy), 1520 CharUnits::One()); 1521 }; 1522 1523 unsigned curInitIndex = 0; 1524 1525 // Emit initialization of base classes. 1526 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(record)) { 1527 assert(E->getNumInits() >= CXXRD->getNumBases() && 1528 "missing initializer for base class"); 1529 for (auto &Base : CXXRD->bases()) { 1530 assert(!Base.isVirtual() && "should not see vbases here"); 1531 auto *BaseRD = Base.getType()->getAsCXXRecordDecl(); 1532 Address V = CGF.GetAddressOfDirectBaseInCompleteClass( 1533 Dest.getAddress(), CXXRD, BaseRD, 1534 /*isBaseVirtual*/ false); 1535 AggValueSlot AggSlot = AggValueSlot::forAddr( 1536 V, Qualifiers(), 1537 AggValueSlot::IsDestructed, 1538 AggValueSlot::DoesNotNeedGCBarriers, 1539 AggValueSlot::IsNotAliased, 1540 CGF.getOverlapForBaseInit(CXXRD, BaseRD, Base.isVirtual())); 1541 CGF.EmitAggExpr(E->getInit(curInitIndex++), AggSlot); 1542 1543 if (QualType::DestructionKind dtorKind = 1544 Base.getType().isDestructedType()) { 1545 CGF.pushDestroy(dtorKind, V, Base.getType()); 1546 addCleanup(CGF.EHStack.stable_begin()); 1547 } 1548 } 1549 } 1550 1551 // Prepare a 'this' for CXXDefaultInitExprs. 1552 CodeGenFunction::FieldConstructionScope FCS(CGF, Dest.getAddress()); 1553 1554 if (record->isUnion()) { 1555 // Only initialize one field of a union. The field itself is 1556 // specified by the initializer list. 1557 if (!E->getInitializedFieldInUnion()) { 1558 // Empty union; we have nothing to do. 1559 1560 #ifndef NDEBUG 1561 // Make sure that it's really an empty and not a failure of 1562 // semantic analysis. 1563 for (const auto *Field : record->fields()) 1564 assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed"); 1565 #endif 1566 return; 1567 } 1568 1569 // FIXME: volatility 1570 FieldDecl *Field = E->getInitializedFieldInUnion(); 1571 1572 LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestLV, Field); 1573 if (NumInitElements) { 1574 // Store the initializer into the field 1575 EmitInitializationToLValue(E->getInit(0), FieldLoc); 1576 } else { 1577 // Default-initialize to null. 1578 EmitNullInitializationToLValue(FieldLoc); 1579 } 1580 1581 return; 1582 } 1583 1584 // Here we iterate over the fields; this makes it simpler to both 1585 // default-initialize fields and skip over unnamed fields. 1586 for (const auto *field : record->fields()) { 1587 // We're done once we hit the flexible array member. 1588 if (field->getType()->isIncompleteArrayType()) 1589 break; 1590 1591 // Always skip anonymous bitfields. 1592 if (field->isUnnamedBitfield()) 1593 continue; 1594 1595 // We're done if we reach the end of the explicit initializers, we 1596 // have a zeroed object, and the rest of the fields are 1597 // zero-initializable. 1598 if (curInitIndex == NumInitElements && Dest.isZeroed() && 1599 CGF.getTypes().isZeroInitializable(E->getType())) 1600 break; 1601 1602 1603 LValue LV = CGF.EmitLValueForFieldInitialization(DestLV, field); 1604 // We never generate write-barries for initialized fields. 1605 LV.setNonGC(true); 1606 1607 if (curInitIndex < NumInitElements) { 1608 // Store the initializer into the field. 1609 EmitInitializationToLValue(E->getInit(curInitIndex++), LV); 1610 } else { 1611 // We're out of initializers; default-initialize to null 1612 EmitNullInitializationToLValue(LV); 1613 } 1614 1615 // Push a destructor if necessary. 1616 // FIXME: if we have an array of structures, all explicitly 1617 // initialized, we can end up pushing a linear number of cleanups. 1618 bool pushedCleanup = false; 1619 if (QualType::DestructionKind dtorKind 1620 = field->getType().isDestructedType()) { 1621 assert(LV.isSimple()); 1622 if (CGF.needsEHCleanup(dtorKind)) { 1623 CGF.pushDestroy(EHCleanup, LV.getAddress(CGF), field->getType(), 1624 CGF.getDestroyer(dtorKind), false); 1625 addCleanup(CGF.EHStack.stable_begin()); 1626 pushedCleanup = true; 1627 } 1628 } 1629 1630 // If the GEP didn't get used because of a dead zero init or something 1631 // else, clean it up for -O0 builds and general tidiness. 1632 if (!pushedCleanup && LV.isSimple()) 1633 if (llvm::GetElementPtrInst *GEP = 1634 dyn_cast<llvm::GetElementPtrInst>(LV.getPointer(CGF))) 1635 if (GEP->use_empty()) 1636 GEP->eraseFromParent(); 1637 } 1638 1639 // Deactivate all the partial cleanups in reverse order, which 1640 // generally means popping them. 1641 assert((cleanupDominator || cleanups.empty()) && 1642 "Missing cleanupDominator before deactivating cleanup blocks"); 1643 for (unsigned i = cleanups.size(); i != 0; --i) 1644 CGF.DeactivateCleanupBlock(cleanups[i-1], cleanupDominator); 1645 1646 // Destroy the placeholder if we made one. 1647 if (cleanupDominator) 1648 cleanupDominator->eraseFromParent(); 1649 } 1650 1651 void AggExprEmitter::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E, 1652 llvm::Value *outerBegin) { 1653 // Emit the common subexpression. 1654 CodeGenFunction::OpaqueValueMapping binding(CGF, E->getCommonExpr()); 1655 1656 Address destPtr = EnsureSlot(E->getType()).getAddress(); 1657 uint64_t numElements = E->getArraySize().getZExtValue(); 1658 1659 if (!numElements) 1660 return; 1661 1662 // destPtr is an array*. Construct an elementType* by drilling down a level. 1663 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0); 1664 llvm::Value *indices[] = {zero, zero}; 1665 llvm::Value *begin = Builder.CreateInBoundsGEP(destPtr.getPointer(), indices, 1666 "arrayinit.begin"); 1667 1668 // Prepare to special-case multidimensional array initialization: we avoid 1669 // emitting multiple destructor loops in that case. 1670 if (!outerBegin) 1671 outerBegin = begin; 1672 ArrayInitLoopExpr *InnerLoop = dyn_cast<ArrayInitLoopExpr>(E->getSubExpr()); 1673 1674 QualType elementType = 1675 CGF.getContext().getAsArrayType(E->getType())->getElementType(); 1676 CharUnits elementSize = CGF.getContext().getTypeSizeInChars(elementType); 1677 CharUnits elementAlign = 1678 destPtr.getAlignment().alignmentOfArrayElement(elementSize); 1679 1680 llvm::BasicBlock *entryBB = Builder.GetInsertBlock(); 1681 llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body"); 1682 1683 // Jump into the body. 1684 CGF.EmitBlock(bodyBB); 1685 llvm::PHINode *index = 1686 Builder.CreatePHI(zero->getType(), 2, "arrayinit.index"); 1687 index->addIncoming(zero, entryBB); 1688 llvm::Value *element = Builder.CreateInBoundsGEP(begin, index); 1689 1690 // Prepare for a cleanup. 1691 QualType::DestructionKind dtorKind = elementType.isDestructedType(); 1692 EHScopeStack::stable_iterator cleanup; 1693 if (CGF.needsEHCleanup(dtorKind) && !InnerLoop) { 1694 if (outerBegin->getType() != element->getType()) 1695 outerBegin = Builder.CreateBitCast(outerBegin, element->getType()); 1696 CGF.pushRegularPartialArrayCleanup(outerBegin, element, elementType, 1697 elementAlign, 1698 CGF.getDestroyer(dtorKind)); 1699 cleanup = CGF.EHStack.stable_begin(); 1700 } else { 1701 dtorKind = QualType::DK_none; 1702 } 1703 1704 // Emit the actual filler expression. 1705 { 1706 // Temporaries created in an array initialization loop are destroyed 1707 // at the end of each iteration. 1708 CodeGenFunction::RunCleanupsScope CleanupsScope(CGF); 1709 CodeGenFunction::ArrayInitLoopExprScope Scope(CGF, index); 1710 LValue elementLV = 1711 CGF.MakeAddrLValue(Address(element, elementAlign), elementType); 1712 1713 if (InnerLoop) { 1714 // If the subexpression is an ArrayInitLoopExpr, share its cleanup. 1715 auto elementSlot = AggValueSlot::forLValue( 1716 elementLV, CGF, AggValueSlot::IsDestructed, 1717 AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased, 1718 AggValueSlot::DoesNotOverlap); 1719 AggExprEmitter(CGF, elementSlot, false) 1720 .VisitArrayInitLoopExpr(InnerLoop, outerBegin); 1721 } else 1722 EmitInitializationToLValue(E->getSubExpr(), elementLV); 1723 } 1724 1725 // Move on to the next element. 1726 llvm::Value *nextIndex = Builder.CreateNUWAdd( 1727 index, llvm::ConstantInt::get(CGF.SizeTy, 1), "arrayinit.next"); 1728 index->addIncoming(nextIndex, Builder.GetInsertBlock()); 1729 1730 // Leave the loop if we're done. 1731 llvm::Value *done = Builder.CreateICmpEQ( 1732 nextIndex, llvm::ConstantInt::get(CGF.SizeTy, numElements), 1733 "arrayinit.done"); 1734 llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end"); 1735 Builder.CreateCondBr(done, endBB, bodyBB); 1736 1737 CGF.EmitBlock(endBB); 1738 1739 // Leave the partial-array cleanup if we entered one. 1740 if (dtorKind) 1741 CGF.DeactivateCleanupBlock(cleanup, index); 1742 } 1743 1744 void AggExprEmitter::VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E) { 1745 AggValueSlot Dest = EnsureSlot(E->getType()); 1746 1747 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType()); 1748 EmitInitializationToLValue(E->getBase(), DestLV); 1749 VisitInitListExpr(E->getUpdater()); 1750 } 1751 1752 //===----------------------------------------------------------------------===// 1753 // Entry Points into this File 1754 //===----------------------------------------------------------------------===// 1755 1756 /// GetNumNonZeroBytesInInit - Get an approximate count of the number of 1757 /// non-zero bytes that will be stored when outputting the initializer for the 1758 /// specified initializer expression. 1759 static CharUnits GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) { 1760 E = E->IgnoreParens(); 1761 1762 // 0 and 0.0 won't require any non-zero stores! 1763 if (isSimpleZero(E, CGF)) return CharUnits::Zero(); 1764 1765 // If this is an initlist expr, sum up the size of sizes of the (present) 1766 // elements. If this is something weird, assume the whole thing is non-zero. 1767 const InitListExpr *ILE = dyn_cast<InitListExpr>(E); 1768 while (ILE && ILE->isTransparent()) 1769 ILE = dyn_cast<InitListExpr>(ILE->getInit(0)); 1770 if (!ILE || !CGF.getTypes().isZeroInitializable(ILE->getType())) 1771 return CGF.getContext().getTypeSizeInChars(E->getType()); 1772 1773 // InitListExprs for structs have to be handled carefully. If there are 1774 // reference members, we need to consider the size of the reference, not the 1775 // referencee. InitListExprs for unions and arrays can't have references. 1776 if (const RecordType *RT = E->getType()->getAs<RecordType>()) { 1777 if (!RT->isUnionType()) { 1778 RecordDecl *SD = RT->getDecl(); 1779 CharUnits NumNonZeroBytes = CharUnits::Zero(); 1780 1781 unsigned ILEElement = 0; 1782 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(SD)) 1783 while (ILEElement != CXXRD->getNumBases()) 1784 NumNonZeroBytes += 1785 GetNumNonZeroBytesInInit(ILE->getInit(ILEElement++), CGF); 1786 for (const auto *Field : SD->fields()) { 1787 // We're done once we hit the flexible array member or run out of 1788 // InitListExpr elements. 1789 if (Field->getType()->isIncompleteArrayType() || 1790 ILEElement == ILE->getNumInits()) 1791 break; 1792 if (Field->isUnnamedBitfield()) 1793 continue; 1794 1795 const Expr *E = ILE->getInit(ILEElement++); 1796 1797 // Reference values are always non-null and have the width of a pointer. 1798 if (Field->getType()->isReferenceType()) 1799 NumNonZeroBytes += CGF.getContext().toCharUnitsFromBits( 1800 CGF.getTarget().getPointerWidth(0)); 1801 else 1802 NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF); 1803 } 1804 1805 return NumNonZeroBytes; 1806 } 1807 } 1808 1809 1810 CharUnits NumNonZeroBytes = CharUnits::Zero(); 1811 for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i) 1812 NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF); 1813 return NumNonZeroBytes; 1814 } 1815 1816 /// CheckAggExprForMemSetUse - If the initializer is large and has a lot of 1817 /// zeros in it, emit a memset and avoid storing the individual zeros. 1818 /// 1819 static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E, 1820 CodeGenFunction &CGF) { 1821 // If the slot is already known to be zeroed, nothing to do. Don't mess with 1822 // volatile stores. 1823 if (Slot.isZeroed() || Slot.isVolatile() || !Slot.getAddress().isValid()) 1824 return; 1825 1826 // C++ objects with a user-declared constructor don't need zero'ing. 1827 if (CGF.getLangOpts().CPlusPlus) 1828 if (const RecordType *RT = CGF.getContext() 1829 .getBaseElementType(E->getType())->getAs<RecordType>()) { 1830 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); 1831 if (RD->hasUserDeclaredConstructor()) 1832 return; 1833 } 1834 1835 // If the type is 16-bytes or smaller, prefer individual stores over memset. 1836 CharUnits Size = Slot.getPreferredSize(CGF.getContext(), E->getType()); 1837 if (Size <= CharUnits::fromQuantity(16)) 1838 return; 1839 1840 // Check to see if over 3/4 of the initializer are known to be zero. If so, 1841 // we prefer to emit memset + individual stores for the rest. 1842 CharUnits NumNonZeroBytes = GetNumNonZeroBytesInInit(E, CGF); 1843 if (NumNonZeroBytes*4 > Size) 1844 return; 1845 1846 // Okay, it seems like a good idea to use an initial memset, emit the call. 1847 llvm::Constant *SizeVal = CGF.Builder.getInt64(Size.getQuantity()); 1848 1849 Address Loc = Slot.getAddress(); 1850 Loc = CGF.Builder.CreateElementBitCast(Loc, CGF.Int8Ty); 1851 CGF.Builder.CreateMemSet(Loc, CGF.Builder.getInt8(0), SizeVal, false); 1852 1853 // Tell the AggExprEmitter that the slot is known zero. 1854 Slot.setZeroed(); 1855 } 1856 1857 1858 1859 1860 /// EmitAggExpr - Emit the computation of the specified expression of aggregate 1861 /// type. The result is computed into DestPtr. Note that if DestPtr is null, 1862 /// the value of the aggregate expression is not needed. If VolatileDest is 1863 /// true, DestPtr cannot be 0. 1864 void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot) { 1865 assert(E && hasAggregateEvaluationKind(E->getType()) && 1866 "Invalid aggregate expression to emit"); 1867 assert((Slot.getAddress().isValid() || Slot.isIgnored()) && 1868 "slot has bits but no address"); 1869 1870 // Optimize the slot if possible. 1871 CheckAggExprForMemSetUse(Slot, E, *this); 1872 1873 AggExprEmitter(*this, Slot, Slot.isIgnored()).Visit(const_cast<Expr*>(E)); 1874 } 1875 1876 LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) { 1877 assert(hasAggregateEvaluationKind(E->getType()) && "Invalid argument!"); 1878 Address Temp = CreateMemTemp(E->getType()); 1879 LValue LV = MakeAddrLValue(Temp, E->getType()); 1880 EmitAggExpr(E, AggValueSlot::forLValue( 1881 LV, *this, AggValueSlot::IsNotDestructed, 1882 AggValueSlot::DoesNotNeedGCBarriers, 1883 AggValueSlot::IsNotAliased, AggValueSlot::DoesNotOverlap)); 1884 return LV; 1885 } 1886 1887 AggValueSlot::Overlap_t 1888 CodeGenFunction::getOverlapForFieldInit(const FieldDecl *FD) { 1889 if (!FD->hasAttr<NoUniqueAddressAttr>() || !FD->getType()->isRecordType()) 1890 return AggValueSlot::DoesNotOverlap; 1891 1892 // If the field lies entirely within the enclosing class's nvsize, its tail 1893 // padding cannot overlap any already-initialized object. (The only subobjects 1894 // with greater addresses that might already be initialized are vbases.) 1895 const RecordDecl *ClassRD = FD->getParent(); 1896 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(ClassRD); 1897 if (Layout.getFieldOffset(FD->getFieldIndex()) + 1898 getContext().getTypeSize(FD->getType()) <= 1899 (uint64_t)getContext().toBits(Layout.getNonVirtualSize())) 1900 return AggValueSlot::DoesNotOverlap; 1901 1902 // The tail padding may contain values we need to preserve. 1903 return AggValueSlot::MayOverlap; 1904 } 1905 1906 AggValueSlot::Overlap_t CodeGenFunction::getOverlapForBaseInit( 1907 const CXXRecordDecl *RD, const CXXRecordDecl *BaseRD, bool IsVirtual) { 1908 // If the most-derived object is a field declared with [[no_unique_address]], 1909 // the tail padding of any virtual base could be reused for other subobjects 1910 // of that field's class. 1911 if (IsVirtual) 1912 return AggValueSlot::MayOverlap; 1913 1914 // If the base class is laid out entirely within the nvsize of the derived 1915 // class, its tail padding cannot yet be initialized, so we can issue 1916 // stores at the full width of the base class. 1917 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD); 1918 if (Layout.getBaseClassOffset(BaseRD) + 1919 getContext().getASTRecordLayout(BaseRD).getSize() <= 1920 Layout.getNonVirtualSize()) 1921 return AggValueSlot::DoesNotOverlap; 1922 1923 // The tail padding may contain values we need to preserve. 1924 return AggValueSlot::MayOverlap; 1925 } 1926 1927 void CodeGenFunction::EmitAggregateCopy(LValue Dest, LValue Src, QualType Ty, 1928 AggValueSlot::Overlap_t MayOverlap, 1929 bool isVolatile) { 1930 assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex"); 1931 1932 Address DestPtr = Dest.getAddress(*this); 1933 Address SrcPtr = Src.getAddress(*this); 1934 1935 if (getLangOpts().CPlusPlus) { 1936 if (const RecordType *RT = Ty->getAs<RecordType>()) { 1937 CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl()); 1938 assert((Record->hasTrivialCopyConstructor() || 1939 Record->hasTrivialCopyAssignment() || 1940 Record->hasTrivialMoveConstructor() || 1941 Record->hasTrivialMoveAssignment() || 1942 Record->isUnion()) && 1943 "Trying to aggregate-copy a type without a trivial copy/move " 1944 "constructor or assignment operator"); 1945 // Ignore empty classes in C++. 1946 if (Record->isEmpty()) 1947 return; 1948 } 1949 } 1950 1951 if (getLangOpts().CUDAIsDevice) { 1952 if (Ty->isCUDADeviceBuiltinSurfaceType()) { 1953 if (getTargetHooks().emitCUDADeviceBuiltinSurfaceDeviceCopy(*this, Dest, 1954 Src)) 1955 return; 1956 } else if (Ty->isCUDADeviceBuiltinTextureType()) { 1957 if (getTargetHooks().emitCUDADeviceBuiltinTextureDeviceCopy(*this, Dest, 1958 Src)) 1959 return; 1960 } 1961 } 1962 1963 // Aggregate assignment turns into llvm.memcpy. This is almost valid per 1964 // C99 6.5.16.1p3, which states "If the value being stored in an object is 1965 // read from another object that overlaps in anyway the storage of the first 1966 // object, then the overlap shall be exact and the two objects shall have 1967 // qualified or unqualified versions of a compatible type." 1968 // 1969 // memcpy is not defined if the source and destination pointers are exactly 1970 // equal, but other compilers do this optimization, and almost every memcpy 1971 // implementation handles this case safely. If there is a libc that does not 1972 // safely handle this, we can add a target hook. 1973 1974 // Get data size info for this aggregate. Don't copy the tail padding if this 1975 // might be a potentially-overlapping subobject, since the tail padding might 1976 // be occupied by a different object. Otherwise, copying it is fine. 1977 std::pair<CharUnits, CharUnits> TypeInfo; 1978 if (MayOverlap) 1979 TypeInfo = getContext().getTypeInfoDataSizeInChars(Ty); 1980 else 1981 TypeInfo = getContext().getTypeInfoInChars(Ty); 1982 1983 llvm::Value *SizeVal = nullptr; 1984 if (TypeInfo.first.isZero()) { 1985 // But note that getTypeInfo returns 0 for a VLA. 1986 if (auto *VAT = dyn_cast_or_null<VariableArrayType>( 1987 getContext().getAsArrayType(Ty))) { 1988 QualType BaseEltTy; 1989 SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr); 1990 TypeInfo = getContext().getTypeInfoInChars(BaseEltTy); 1991 assert(!TypeInfo.first.isZero()); 1992 SizeVal = Builder.CreateNUWMul( 1993 SizeVal, 1994 llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity())); 1995 } 1996 } 1997 if (!SizeVal) { 1998 SizeVal = llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity()); 1999 } 2000 2001 // FIXME: If we have a volatile struct, the optimizer can remove what might 2002 // appear to be `extra' memory ops: 2003 // 2004 // volatile struct { int i; } a, b; 2005 // 2006 // int main() { 2007 // a = b; 2008 // a = b; 2009 // } 2010 // 2011 // we need to use a different call here. We use isVolatile to indicate when 2012 // either the source or the destination is volatile. 2013 2014 DestPtr = Builder.CreateElementBitCast(DestPtr, Int8Ty); 2015 SrcPtr = Builder.CreateElementBitCast(SrcPtr, Int8Ty); 2016 2017 // Don't do any of the memmove_collectable tests if GC isn't set. 2018 if (CGM.getLangOpts().getGC() == LangOptions::NonGC) { 2019 // fall through 2020 } else if (const RecordType *RecordTy = Ty->getAs<RecordType>()) { 2021 RecordDecl *Record = RecordTy->getDecl(); 2022 if (Record->hasObjectMember()) { 2023 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr, 2024 SizeVal); 2025 return; 2026 } 2027 } else if (Ty->isArrayType()) { 2028 QualType BaseType = getContext().getBaseElementType(Ty); 2029 if (const RecordType *RecordTy = BaseType->getAs<RecordType>()) { 2030 if (RecordTy->getDecl()->hasObjectMember()) { 2031 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr, 2032 SizeVal); 2033 return; 2034 } 2035 } 2036 } 2037 2038 auto Inst = Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, isVolatile); 2039 2040 // Determine the metadata to describe the position of any padding in this 2041 // memcpy, as well as the TBAA tags for the members of the struct, in case 2042 // the optimizer wishes to expand it in to scalar memory operations. 2043 if (llvm::MDNode *TBAAStructTag = CGM.getTBAAStructInfo(Ty)) 2044 Inst->setMetadata(llvm::LLVMContext::MD_tbaa_struct, TBAAStructTag); 2045 2046 if (CGM.getCodeGenOpts().NewStructPathTBAA) { 2047 TBAAAccessInfo TBAAInfo = CGM.mergeTBAAInfoForMemoryTransfer( 2048 Dest.getTBAAInfo(), Src.getTBAAInfo()); 2049 CGM.DecorateInstructionWithTBAA(Inst, TBAAInfo); 2050 } 2051 } 2052