1 //===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate Expressions --------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This contains code to emit Aggregate Expr nodes as LLVM code.
12 //===----------------------------------------------------------------------===//
14 #include "CodeGenFunction.h"
16 #include "CGObjCRuntime.h"
17 #include "CodeGenModule.h"
18 #include "ConstantEmitter.h"
19 #include "clang/AST/ASTContext.h"
20 #include "clang/AST/DeclCXX.h"
21 #include "clang/AST/DeclTemplate.h"
22 #include "clang/AST/StmtVisitor.h"
23 #include "llvm/IR/Constants.h"
24 #include "llvm/IR/Function.h"
25 #include "llvm/IR/GlobalVariable.h"
26 #include "llvm/IR/Intrinsics.h"
27 #include "llvm/IR/IntrinsicInst.h"
28 using namespace clang;
29 using namespace CodeGen;
31 //===----------------------------------------------------------------------===//
32 // Aggregate Expression Emitter
33 //===----------------------------------------------------------------------===//
36 class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
42 AggValueSlot EnsureSlot(QualType T) {
43 if (!Dest.isIgnored()) return Dest;
44 return CGF.CreateAggTemp(T, "agg.tmp.ensured");
46 void EnsureDest(QualType T) {
47 if (!Dest.isIgnored()) return;
48 Dest = CGF.CreateAggTemp(T, "agg.tmp.ensured");
51 // Calls `Fn` with a valid return value slot, potentially creating a temporary
52 // to do so. If a temporary is created, an appropriate copy into `Dest` will
53 // be emitted, as will lifetime markers.
55 // The given function should take a ReturnValueSlot, and return an RValue that
56 // points to said slot.
57 void withReturnValueSlot(const Expr *E,
58 llvm::function_ref<RValue(ReturnValueSlot)> Fn);
61 AggExprEmitter(CodeGenFunction &cgf, AggValueSlot Dest, bool IsResultUnused)
62 : CGF(cgf), Builder(CGF.Builder), Dest(Dest),
63 IsResultUnused(IsResultUnused) { }
65 //===--------------------------------------------------------------------===//
67 //===--------------------------------------------------------------------===//
69 /// EmitAggLoadOfLValue - Given an expression with aggregate type that
70 /// represents a value lvalue, this method emits the address of the lvalue,
71 /// then loads the result into DestPtr.
72 void EmitAggLoadOfLValue(const Expr *E);
79 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
80 /// SrcIsRValue is true if source comes from an RValue.
81 void EmitFinalDestCopy(QualType type, const LValue &src,
82 ExprValueKind SrcValueKind = EVK_NonRValue);
83 void EmitFinalDestCopy(QualType type, RValue src);
84 void EmitCopy(QualType type, const AggValueSlot &dest,
85 const AggValueSlot &src);
87 void EmitMoveFromReturnSlot(const Expr *E, RValue Src);
89 void EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
90 QualType ArrayQTy, InitListExpr *E);
92 AggValueSlot::NeedsGCBarriers_t needsGC(QualType T) {
93 if (CGF.getLangOpts().getGC() && TypeRequiresGCollection(T))
94 return AggValueSlot::NeedsGCBarriers;
95 return AggValueSlot::DoesNotNeedGCBarriers;
98 bool TypeRequiresGCollection(QualType T);
100 //===--------------------------------------------------------------------===//
102 //===--------------------------------------------------------------------===//
104 void Visit(Expr *E) {
105 ApplyDebugLocation DL(CGF, E);
106 StmtVisitor<AggExprEmitter>::Visit(E);
109 void VisitStmt(Stmt *S) {
110 CGF.ErrorUnsupported(S, "aggregate expression");
112 void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }
113 void VisitGenericSelectionExpr(GenericSelectionExpr *GE) {
114 Visit(GE->getResultExpr());
116 void VisitCoawaitExpr(CoawaitExpr *E) {
117 CGF.EmitCoawaitExpr(*E, Dest, IsResultUnused);
119 void VisitCoyieldExpr(CoyieldExpr *E) {
120 CGF.EmitCoyieldExpr(*E, Dest, IsResultUnused);
122 void VisitUnaryCoawait(UnaryOperator *E) { Visit(E->getSubExpr()); }
123 void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); }
124 void VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) {
125 return Visit(E->getReplacement());
128 void VisitConstantExpr(ConstantExpr *E) {
129 return Visit(E->getSubExpr());
133 void VisitDeclRefExpr(DeclRefExpr *E) { EmitAggLoadOfLValue(E); }
134 void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
135 void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
136 void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
137 void VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
138 void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
139 EmitAggLoadOfLValue(E);
141 void VisitPredefinedExpr(const PredefinedExpr *E) {
142 EmitAggLoadOfLValue(E);
146 void VisitCastExpr(CastExpr *E);
147 void VisitCallExpr(const CallExpr *E);
148 void VisitStmtExpr(const StmtExpr *E);
149 void VisitBinaryOperator(const BinaryOperator *BO);
150 void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO);
151 void VisitBinAssign(const BinaryOperator *E);
152 void VisitBinComma(const BinaryOperator *E);
153 void VisitBinCmp(const BinaryOperator *E);
155 void VisitObjCMessageExpr(ObjCMessageExpr *E);
156 void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
157 EmitAggLoadOfLValue(E);
160 void VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E);
161 void VisitAbstractConditionalOperator(const AbstractConditionalOperator *CO);
162 void VisitChooseExpr(const ChooseExpr *CE);
163 void VisitInitListExpr(InitListExpr *E);
164 void VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E,
165 llvm::Value *outerBegin = nullptr);
166 void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E);
167 void VisitNoInitExpr(NoInitExpr *E) { } // Do nothing.
168 void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
169 Visit(DAE->getExpr());
171 void VisitCXXDefaultInitExpr(CXXDefaultInitExpr *DIE) {
172 CodeGenFunction::CXXDefaultInitExprScope Scope(CGF);
173 Visit(DIE->getExpr());
175 void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
176 void VisitCXXConstructExpr(const CXXConstructExpr *E);
177 void VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E);
178 void VisitLambdaExpr(LambdaExpr *E);
179 void VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E);
180 void VisitExprWithCleanups(ExprWithCleanups *E);
181 void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E);
182 void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
183 void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E);
184 void VisitOpaqueValueExpr(OpaqueValueExpr *E);
186 void VisitPseudoObjectExpr(PseudoObjectExpr *E) {
187 if (E->isGLValue()) {
188 LValue LV = CGF.EmitPseudoObjectLValue(E);
189 return EmitFinalDestCopy(E->getType(), LV);
192 CGF.EmitPseudoObjectRValue(E, EnsureSlot(E->getType()));
195 void VisitVAArgExpr(VAArgExpr *E);
197 void EmitInitializationToLValue(Expr *E, LValue Address);
198 void EmitNullInitializationToLValue(LValue Address);
199 // case Expr::ChooseExprClass:
200 void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); }
201 void VisitAtomicExpr(AtomicExpr *E) {
202 RValue Res = CGF.EmitAtomicExpr(E);
203 EmitFinalDestCopy(E->getType(), Res);
206 } // end anonymous namespace.
208 //===----------------------------------------------------------------------===//
210 //===----------------------------------------------------------------------===//
212 /// EmitAggLoadOfLValue - Given an expression with aggregate type that
213 /// represents a value lvalue, this method emits the address of the lvalue,
214 /// then loads the result into DestPtr.
215 void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
216 LValue LV = CGF.EmitLValue(E);
218 // If the type of the l-value is atomic, then do an atomic load.
219 if (LV.getType()->isAtomicType() || CGF.LValueIsSuitableForInlineAtomic(LV)) {
220 CGF.EmitAtomicLoad(LV, E->getExprLoc(), Dest);
224 EmitFinalDestCopy(E->getType(), LV);
227 /// True if the given aggregate type requires special GC API calls.
228 bool AggExprEmitter::TypeRequiresGCollection(QualType T) {
229 // Only record types have members that might require garbage collection.
230 const RecordType *RecordTy = T->getAs<RecordType>();
231 if (!RecordTy) return false;
233 // Don't mess with non-trivial C++ types.
234 RecordDecl *Record = RecordTy->getDecl();
235 if (isa<CXXRecordDecl>(Record) &&
236 (cast<CXXRecordDecl>(Record)->hasNonTrivialCopyConstructor() ||
237 !cast<CXXRecordDecl>(Record)->hasTrivialDestructor()))
240 // Check whether the type has an object member.
241 return Record->hasObjectMember();
244 void AggExprEmitter::withReturnValueSlot(
245 const Expr *E, llvm::function_ref<RValue(ReturnValueSlot)> EmitCall) {
246 QualType RetTy = E->getType();
247 bool RequiresDestruction =
249 RetTy.isDestructedType() == QualType::DK_nontrivial_c_struct;
251 // If it makes no observable difference, save a memcpy + temporary.
253 // We need to always provide our own temporary if destruction is required.
254 // Otherwise, EmitCall will emit its own, notice that it's "unused", and end
255 // its lifetime before we have the chance to emit a proper destructor call.
256 bool UseTemp = Dest.isPotentiallyAliased() || Dest.requiresGCollection() ||
257 (RequiresDestruction && !Dest.getAddress().isValid());
259 Address RetAddr = Address::invalid();
260 Address RetAllocaAddr = Address::invalid();
262 EHScopeStack::stable_iterator LifetimeEndBlock;
263 llvm::Value *LifetimeSizePtr = nullptr;
264 llvm::IntrinsicInst *LifetimeStartInst = nullptr;
266 RetAddr = Dest.getAddress();
268 RetAddr = CGF.CreateMemTemp(RetTy, "tmp", &RetAllocaAddr);
270 CGF.CGM.getDataLayout().getTypeAllocSize(CGF.ConvertTypeForMem(RetTy));
271 LifetimeSizePtr = CGF.EmitLifetimeStart(Size, RetAllocaAddr.getPointer());
272 if (LifetimeSizePtr) {
274 cast<llvm::IntrinsicInst>(std::prev(Builder.GetInsertPoint()));
275 assert(LifetimeStartInst->getIntrinsicID() ==
276 llvm::Intrinsic::lifetime_start &&
277 "Last insertion wasn't a lifetime.start?");
279 CGF.pushFullExprCleanup<CodeGenFunction::CallLifetimeEnd>(
280 NormalEHLifetimeMarker, RetAllocaAddr, LifetimeSizePtr);
281 LifetimeEndBlock = CGF.EHStack.stable_begin();
286 EmitCall(ReturnValueSlot(RetAddr, Dest.isVolatile(), IsResultUnused));
288 if (RequiresDestruction)
289 CGF.pushDestroy(RetTy.isDestructedType(), Src.getAggregateAddress(), RetTy);
294 assert(Dest.getPointer() != Src.getAggregatePointer());
295 EmitFinalDestCopy(E->getType(), Src);
297 if (!RequiresDestruction && LifetimeStartInst) {
298 // If there's no dtor to run, the copy was the last use of our temporary.
299 // Since we're not guaranteed to be in an ExprWithCleanups, clean up
301 CGF.DeactivateCleanupBlock(LifetimeEndBlock, LifetimeStartInst);
302 CGF.EmitLifetimeEnd(LifetimeSizePtr, RetAllocaAddr.getPointer());
306 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
307 void AggExprEmitter::EmitFinalDestCopy(QualType type, RValue src) {
308 assert(src.isAggregate() && "value must be aggregate value!");
309 LValue srcLV = CGF.MakeAddrLValue(src.getAggregateAddress(), type);
310 EmitFinalDestCopy(type, srcLV, EVK_RValue);
313 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
314 void AggExprEmitter::EmitFinalDestCopy(QualType type, const LValue &src,
315 ExprValueKind SrcValueKind) {
316 // If Dest is ignored, then we're evaluating an aggregate expression
317 // in a context that doesn't care about the result. Note that loads
318 // from volatile l-values force the existence of a non-ignored
320 if (Dest.isIgnored())
323 // Copy non-trivial C structs here.
324 LValue DstLV = CGF.MakeAddrLValue(
325 Dest.getAddress(), Dest.isVolatile() ? type.withVolatile() : type);
327 if (SrcValueKind == EVK_RValue) {
328 if (type.isNonTrivialToPrimitiveDestructiveMove() == QualType::PCK_Struct) {
329 if (Dest.isPotentiallyAliased())
330 CGF.callCStructMoveAssignmentOperator(DstLV, src);
332 CGF.callCStructMoveConstructor(DstLV, src);
336 if (type.isNonTrivialToPrimitiveCopy() == QualType::PCK_Struct) {
337 if (Dest.isPotentiallyAliased())
338 CGF.callCStructCopyAssignmentOperator(DstLV, src);
340 CGF.callCStructCopyConstructor(DstLV, src);
345 AggValueSlot srcAgg =
346 AggValueSlot::forLValue(src, AggValueSlot::IsDestructed,
347 needsGC(type), AggValueSlot::IsAliased,
348 AggValueSlot::MayOverlap);
349 EmitCopy(type, Dest, srcAgg);
352 /// Perform a copy from the source into the destination.
354 /// \param type - the type of the aggregate being copied; qualifiers are
356 void AggExprEmitter::EmitCopy(QualType type, const AggValueSlot &dest,
357 const AggValueSlot &src) {
358 if (dest.requiresGCollection()) {
359 CharUnits sz = dest.getPreferredSize(CGF.getContext(), type);
360 llvm::Value *size = llvm::ConstantInt::get(CGF.SizeTy, sz.getQuantity());
361 CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
368 // If the result of the assignment is used, copy the LHS there also.
369 // It's volatile if either side is. Use the minimum alignment of
371 LValue DestLV = CGF.MakeAddrLValue(dest.getAddress(), type);
372 LValue SrcLV = CGF.MakeAddrLValue(src.getAddress(), type);
373 CGF.EmitAggregateCopy(DestLV, SrcLV, type, dest.mayOverlap(),
374 dest.isVolatile() || src.isVolatile());
377 /// Emit the initializer for a std::initializer_list initialized with a
378 /// real initializer list.
380 AggExprEmitter::VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E) {
381 // Emit an array containing the elements. The array is externally destructed
382 // if the std::initializer_list object is.
383 ASTContext &Ctx = CGF.getContext();
384 LValue Array = CGF.EmitLValue(E->getSubExpr());
385 assert(Array.isSimple() && "initializer_list array not a simple lvalue");
386 Address ArrayPtr = Array.getAddress();
388 const ConstantArrayType *ArrayType =
389 Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
390 assert(ArrayType && "std::initializer_list constructed from non-array");
392 // FIXME: Perform the checks on the field types in SemaInit.
393 RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
394 RecordDecl::field_iterator Field = Record->field_begin();
395 if (Field == Record->field_end()) {
396 CGF.ErrorUnsupported(E, "weird std::initializer_list");
401 if (!Field->getType()->isPointerType() ||
402 !Ctx.hasSameType(Field->getType()->getPointeeType(),
403 ArrayType->getElementType())) {
404 CGF.ErrorUnsupported(E, "weird std::initializer_list");
408 AggValueSlot Dest = EnsureSlot(E->getType());
409 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
410 LValue Start = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
411 llvm::Value *Zero = llvm::ConstantInt::get(CGF.PtrDiffTy, 0);
412 llvm::Value *IdxStart[] = { Zero, Zero };
413 llvm::Value *ArrayStart =
414 Builder.CreateInBoundsGEP(ArrayPtr.getPointer(), IdxStart, "arraystart");
415 CGF.EmitStoreThroughLValue(RValue::get(ArrayStart), Start);
418 if (Field == Record->field_end()) {
419 CGF.ErrorUnsupported(E, "weird std::initializer_list");
423 llvm::Value *Size = Builder.getInt(ArrayType->getSize());
424 LValue EndOrLength = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
425 if (Field->getType()->isPointerType() &&
426 Ctx.hasSameType(Field->getType()->getPointeeType(),
427 ArrayType->getElementType())) {
429 llvm::Value *IdxEnd[] = { Zero, Size };
430 llvm::Value *ArrayEnd =
431 Builder.CreateInBoundsGEP(ArrayPtr.getPointer(), IdxEnd, "arrayend");
432 CGF.EmitStoreThroughLValue(RValue::get(ArrayEnd), EndOrLength);
433 } else if (Ctx.hasSameType(Field->getType(), Ctx.getSizeType())) {
435 CGF.EmitStoreThroughLValue(RValue::get(Size), EndOrLength);
437 CGF.ErrorUnsupported(E, "weird std::initializer_list");
442 /// Determine if E is a trivial array filler, that is, one that is
443 /// equivalent to zero-initialization.
444 static bool isTrivialFiller(Expr *E) {
448 if (isa<ImplicitValueInitExpr>(E))
451 if (auto *ILE = dyn_cast<InitListExpr>(E)) {
452 if (ILE->getNumInits())
454 return isTrivialFiller(ILE->getArrayFiller());
457 if (auto *Cons = dyn_cast_or_null<CXXConstructExpr>(E))
458 return Cons->getConstructor()->isDefaultConstructor() &&
459 Cons->getConstructor()->isTrivial();
461 // FIXME: Are there other cases where we can avoid emitting an initializer?
465 /// Emit initialization of an array from an initializer list.
466 void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
467 QualType ArrayQTy, InitListExpr *E) {
468 uint64_t NumInitElements = E->getNumInits();
470 uint64_t NumArrayElements = AType->getNumElements();
471 assert(NumInitElements <= NumArrayElements);
473 QualType elementType =
474 CGF.getContext().getAsArrayType(ArrayQTy)->getElementType();
476 // DestPtr is an array*. Construct an elementType* by drilling
478 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
479 llvm::Value *indices[] = { zero, zero };
481 Builder.CreateInBoundsGEP(DestPtr.getPointer(), indices, "arrayinit.begin");
483 CharUnits elementSize = CGF.getContext().getTypeSizeInChars(elementType);
484 CharUnits elementAlign =
485 DestPtr.getAlignment().alignmentOfArrayElement(elementSize);
487 // Consider initializing the array by copying from a global. For this to be
488 // more efficient than per-element initialization, the size of the elements
489 // with explicit initializers should be large enough.
490 if (NumInitElements * elementSize.getQuantity() > 16 &&
491 elementType.isTriviallyCopyableType(CGF.getContext())) {
492 CodeGen::CodeGenModule &CGM = CGF.CGM;
493 ConstantEmitter Emitter(CGM);
494 LangAS AS = ArrayQTy.getAddressSpace();
495 if (llvm::Constant *C = Emitter.tryEmitForInitializer(E, AS, ArrayQTy)) {
496 auto GV = new llvm::GlobalVariable(
497 CGM.getModule(), C->getType(),
498 CGM.isTypeConstant(ArrayQTy, /* ExcludeCtorDtor= */ true),
499 llvm::GlobalValue::PrivateLinkage, C, "constinit",
500 /* InsertBefore= */ nullptr, llvm::GlobalVariable::NotThreadLocal,
501 CGM.getContext().getTargetAddressSpace(AS));
502 Emitter.finalize(GV);
503 CharUnits Align = CGM.getContext().getTypeAlignInChars(ArrayQTy);
504 GV->setAlignment(Align.getQuantity());
505 EmitFinalDestCopy(ArrayQTy, CGF.MakeAddrLValue(GV, ArrayQTy, Align));
510 // Exception safety requires us to destroy all the
511 // already-constructed members if an initializer throws.
512 // For that, we'll need an EH cleanup.
513 QualType::DestructionKind dtorKind = elementType.isDestructedType();
514 Address endOfInit = Address::invalid();
515 EHScopeStack::stable_iterator cleanup;
516 llvm::Instruction *cleanupDominator = nullptr;
517 if (CGF.needsEHCleanup(dtorKind)) {
518 // In principle we could tell the cleanup where we are more
519 // directly, but the control flow can get so varied here that it
520 // would actually be quite complex. Therefore we go through an
522 endOfInit = CGF.CreateTempAlloca(begin->getType(), CGF.getPointerAlign(),
523 "arrayinit.endOfInit");
524 cleanupDominator = Builder.CreateStore(begin, endOfInit);
525 CGF.pushIrregularPartialArrayCleanup(begin, endOfInit, elementType,
527 CGF.getDestroyer(dtorKind));
528 cleanup = CGF.EHStack.stable_begin();
530 // Otherwise, remember that we didn't need a cleanup.
532 dtorKind = QualType::DK_none;
535 llvm::Value *one = llvm::ConstantInt::get(CGF.SizeTy, 1);
537 // The 'current element to initialize'. The invariants on this
538 // variable are complicated. Essentially, after each iteration of
539 // the loop, it points to the last initialized element, except
540 // that it points to the beginning of the array before any
541 // elements have been initialized.
542 llvm::Value *element = begin;
544 // Emit the explicit initializers.
545 for (uint64_t i = 0; i != NumInitElements; ++i) {
546 // Advance to the next element.
548 element = Builder.CreateInBoundsGEP(element, one, "arrayinit.element");
550 // Tell the cleanup that it needs to destroy up to this
551 // element. TODO: some of these stores can be trivially
552 // observed to be unnecessary.
553 if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit);
557 CGF.MakeAddrLValue(Address(element, elementAlign), elementType);
558 EmitInitializationToLValue(E->getInit(i), elementLV);
561 // Check whether there's a non-trivial array-fill expression.
562 Expr *filler = E->getArrayFiller();
563 bool hasTrivialFiller = isTrivialFiller(filler);
565 // Any remaining elements need to be zero-initialized, possibly
566 // using the filler expression. We can skip this if the we're
567 // emitting to zeroed memory.
568 if (NumInitElements != NumArrayElements &&
569 !(Dest.isZeroed() && hasTrivialFiller &&
570 CGF.getTypes().isZeroInitializable(elementType))) {
572 // Use an actual loop. This is basically
573 // do { *array++ = filler; } while (array != end);
575 // Advance to the start of the rest of the array.
576 if (NumInitElements) {
577 element = Builder.CreateInBoundsGEP(element, one, "arrayinit.start");
578 if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit);
581 // Compute the end of the array.
582 llvm::Value *end = Builder.CreateInBoundsGEP(begin,
583 llvm::ConstantInt::get(CGF.SizeTy, NumArrayElements),
586 llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
587 llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body");
589 // Jump into the body.
590 CGF.EmitBlock(bodyBB);
591 llvm::PHINode *currentElement =
592 Builder.CreatePHI(element->getType(), 2, "arrayinit.cur");
593 currentElement->addIncoming(element, entryBB);
595 // Emit the actual filler expression.
597 // C++1z [class.temporary]p5:
598 // when a default constructor is called to initialize an element of
599 // an array with no corresponding initializer [...] the destruction of
600 // every temporary created in a default argument is sequenced before
601 // the construction of the next array element, if any
602 CodeGenFunction::RunCleanupsScope CleanupsScope(CGF);
604 CGF.MakeAddrLValue(Address(currentElement, elementAlign), elementType);
606 EmitInitializationToLValue(filler, elementLV);
608 EmitNullInitializationToLValue(elementLV);
611 // Move on to the next element.
612 llvm::Value *nextElement =
613 Builder.CreateInBoundsGEP(currentElement, one, "arrayinit.next");
615 // Tell the EH cleanup that we finished with the last element.
616 if (endOfInit.isValid()) Builder.CreateStore(nextElement, endOfInit);
618 // Leave the loop if we're done.
619 llvm::Value *done = Builder.CreateICmpEQ(nextElement, end,
621 llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end");
622 Builder.CreateCondBr(done, endBB, bodyBB);
623 currentElement->addIncoming(nextElement, Builder.GetInsertBlock());
625 CGF.EmitBlock(endBB);
628 // Leave the partial-array cleanup if we entered one.
629 if (dtorKind) CGF.DeactivateCleanupBlock(cleanup, cleanupDominator);
632 //===----------------------------------------------------------------------===//
634 //===----------------------------------------------------------------------===//
636 void AggExprEmitter::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E){
637 Visit(E->GetTemporaryExpr());
640 void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) {
641 // If this is a unique OVE, just visit its source expression.
643 Visit(e->getSourceExpr());
645 EmitFinalDestCopy(e->getType(), CGF.getOrCreateOpaqueLValueMapping(e));
649 AggExprEmitter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
650 if (Dest.isPotentiallyAliased() &&
651 E->getType().isPODType(CGF.getContext())) {
652 // For a POD type, just emit a load of the lvalue + a copy, because our
653 // compound literal might alias the destination.
654 EmitAggLoadOfLValue(E);
658 AggValueSlot Slot = EnsureSlot(E->getType());
659 CGF.EmitAggExpr(E->getInitializer(), Slot);
662 /// Attempt to look through various unimportant expressions to find a
663 /// cast of the given kind.
664 static Expr *findPeephole(Expr *op, CastKind kind) {
666 op = op->IgnoreParens();
667 if (CastExpr *castE = dyn_cast<CastExpr>(op)) {
668 if (castE->getCastKind() == kind)
669 return castE->getSubExpr();
670 if (castE->getCastKind() == CK_NoOp)
677 void AggExprEmitter::VisitCastExpr(CastExpr *E) {
678 if (const auto *ECE = dyn_cast<ExplicitCastExpr>(E))
679 CGF.CGM.EmitExplicitCastExprType(ECE, &CGF);
680 switch (E->getCastKind()) {
682 // FIXME: Can this actually happen? We have no test coverage for it.
683 assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?");
684 LValue LV = CGF.EmitCheckedLValue(E->getSubExpr(),
685 CodeGenFunction::TCK_Load);
686 // FIXME: Do we also need to handle property references here?
688 CGF.EmitDynamicCast(LV.getAddress(), cast<CXXDynamicCastExpr>(E));
690 CGF.CGM.ErrorUnsupported(E, "non-simple lvalue dynamic_cast");
692 if (!Dest.isIgnored())
693 CGF.CGM.ErrorUnsupported(E, "lvalue dynamic_cast with a destination");
698 // Evaluate even if the destination is ignored.
699 if (Dest.isIgnored()) {
700 CGF.EmitAnyExpr(E->getSubExpr(), AggValueSlot::ignored(),
701 /*ignoreResult=*/true);
705 // GCC union extension
706 QualType Ty = E->getSubExpr()->getType();
708 Builder.CreateElementBitCast(Dest.getAddress(), CGF.ConvertType(Ty));
709 EmitInitializationToLValue(E->getSubExpr(),
710 CGF.MakeAddrLValue(CastPtr, Ty));
714 case CK_DerivedToBase:
715 case CK_BaseToDerived:
716 case CK_UncheckedDerivedToBase: {
717 llvm_unreachable("cannot perform hierarchy conversion in EmitAggExpr: "
718 "should have been unpacked before we got here");
721 case CK_NonAtomicToAtomic:
722 case CK_AtomicToNonAtomic: {
723 bool isToAtomic = (E->getCastKind() == CK_NonAtomicToAtomic);
725 // Determine the atomic and value types.
726 QualType atomicType = E->getSubExpr()->getType();
727 QualType valueType = E->getType();
728 if (isToAtomic) std::swap(atomicType, valueType);
730 assert(atomicType->isAtomicType());
731 assert(CGF.getContext().hasSameUnqualifiedType(valueType,
732 atomicType->castAs<AtomicType>()->getValueType()));
734 // Just recurse normally if we're ignoring the result or the
735 // atomic type doesn't change representation.
736 if (Dest.isIgnored() || !CGF.CGM.isPaddedAtomicType(atomicType)) {
737 return Visit(E->getSubExpr());
740 CastKind peepholeTarget =
741 (isToAtomic ? CK_AtomicToNonAtomic : CK_NonAtomicToAtomic);
743 // These two cases are reverses of each other; try to peephole them.
744 if (Expr *op = findPeephole(E->getSubExpr(), peepholeTarget)) {
745 assert(CGF.getContext().hasSameUnqualifiedType(op->getType(),
747 "peephole significantly changed types?");
751 // If we're converting an r-value of non-atomic type to an r-value
752 // of atomic type, just emit directly into the relevant sub-object.
754 AggValueSlot valueDest = Dest;
755 if (!valueDest.isIgnored() && CGF.CGM.isPaddedAtomicType(atomicType)) {
756 // Zero-initialize. (Strictly speaking, we only need to initialize
757 // the padding at the end, but this is simpler.)
758 if (!Dest.isZeroed())
759 CGF.EmitNullInitialization(Dest.getAddress(), atomicType);
761 // Build a GEP to refer to the subobject.
763 CGF.Builder.CreateStructGEP(valueDest.getAddress(), 0,
765 valueDest = AggValueSlot::forAddr(valueAddr,
766 valueDest.getQualifiers(),
767 valueDest.isExternallyDestructed(),
768 valueDest.requiresGCollection(),
769 valueDest.isPotentiallyAliased(),
770 AggValueSlot::DoesNotOverlap,
771 AggValueSlot::IsZeroed);
774 CGF.EmitAggExpr(E->getSubExpr(), valueDest);
778 // Otherwise, we're converting an atomic type to a non-atomic type.
779 // Make an atomic temporary, emit into that, and then copy the value out.
780 AggValueSlot atomicSlot =
781 CGF.CreateAggTemp(atomicType, "atomic-to-nonatomic.temp");
782 CGF.EmitAggExpr(E->getSubExpr(), atomicSlot);
785 Builder.CreateStructGEP(atomicSlot.getAddress(), 0, CharUnits());
786 RValue rvalue = RValue::getAggregate(valueAddr, atomicSlot.isVolatile());
787 return EmitFinalDestCopy(valueType, rvalue);
790 case CK_LValueToRValue:
791 // If we're loading from a volatile type, force the destination
793 if (E->getSubExpr()->getType().isVolatileQualified()) {
794 EnsureDest(E->getType());
795 return Visit(E->getSubExpr());
801 case CK_UserDefinedConversion:
802 case CK_ConstructorConversion:
803 assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
805 "Implicit cast types must be compatible");
806 Visit(E->getSubExpr());
809 case CK_LValueBitCast:
810 llvm_unreachable("should not be emitting lvalue bitcast as rvalue");
814 case CK_ArrayToPointerDecay:
815 case CK_FunctionToPointerDecay:
816 case CK_NullToPointer:
817 case CK_NullToMemberPointer:
818 case CK_BaseToDerivedMemberPointer:
819 case CK_DerivedToBaseMemberPointer:
820 case CK_MemberPointerToBoolean:
821 case CK_ReinterpretMemberPointer:
822 case CK_IntegralToPointer:
823 case CK_PointerToIntegral:
824 case CK_PointerToBoolean:
827 case CK_IntegralCast:
828 case CK_BooleanToSignedIntegral:
829 case CK_IntegralToBoolean:
830 case CK_IntegralToFloating:
831 case CK_FloatingToIntegral:
832 case CK_FloatingToBoolean:
833 case CK_FloatingCast:
834 case CK_CPointerToObjCPointerCast:
835 case CK_BlockPointerToObjCPointerCast:
836 case CK_AnyPointerToBlockPointerCast:
837 case CK_ObjCObjectLValueCast:
838 case CK_FloatingRealToComplex:
839 case CK_FloatingComplexToReal:
840 case CK_FloatingComplexToBoolean:
841 case CK_FloatingComplexCast:
842 case CK_FloatingComplexToIntegralComplex:
843 case CK_IntegralRealToComplex:
844 case CK_IntegralComplexToReal:
845 case CK_IntegralComplexToBoolean:
846 case CK_IntegralComplexCast:
847 case CK_IntegralComplexToFloatingComplex:
848 case CK_ARCProduceObject:
849 case CK_ARCConsumeObject:
850 case CK_ARCReclaimReturnedObject:
851 case CK_ARCExtendBlockObject:
852 case CK_CopyAndAutoreleaseBlockObject:
853 case CK_BuiltinFnToFnPtr:
854 case CK_ZeroToOCLOpaqueType:
855 case CK_AddressSpaceConversion:
856 case CK_IntToOCLSampler:
857 case CK_FixedPointCast:
858 case CK_FixedPointToBoolean:
859 llvm_unreachable("cast kind invalid for aggregate types");
863 void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
864 if (E->getCallReturnType(CGF.getContext())->isReferenceType()) {
865 EmitAggLoadOfLValue(E);
869 withReturnValueSlot(E, [&](ReturnValueSlot Slot) {
870 return CGF.EmitCallExpr(E, Slot);
874 void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
875 withReturnValueSlot(E, [&](ReturnValueSlot Slot) {
876 return CGF.EmitObjCMessageExpr(E, Slot);
880 void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
881 CGF.EmitIgnoredExpr(E->getLHS());
885 void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
886 CodeGenFunction::StmtExprEvaluation eval(CGF);
887 CGF.EmitCompoundStmt(*E->getSubStmt(), true, Dest);
896 static llvm::Value *EmitCompare(CGBuilderTy &Builder, CodeGenFunction &CGF,
897 const BinaryOperator *E, llvm::Value *LHS,
898 llvm::Value *RHS, CompareKind Kind,
899 const char *NameSuffix = "") {
900 QualType ArgTy = E->getLHS()->getType();
901 if (const ComplexType *CT = ArgTy->getAs<ComplexType>())
902 ArgTy = CT->getElementType();
904 if (const auto *MPT = ArgTy->getAs<MemberPointerType>()) {
905 assert(Kind == CK_Equal &&
906 "member pointers may only be compared for equality");
907 return CGF.CGM.getCXXABI().EmitMemberPointerComparison(
908 CGF, LHS, RHS, MPT, /*IsInequality*/ false);
911 // Compute the comparison instructions for the specified comparison kind.
914 llvm::CmpInst::Predicate FCmp;
915 llvm::CmpInst::Predicate SCmp;
916 llvm::CmpInst::Predicate UCmp;
918 CmpInstInfo InstInfo = [&]() -> CmpInstInfo {
919 using FI = llvm::FCmpInst;
920 using II = llvm::ICmpInst;
923 return {"cmp.lt", FI::FCMP_OLT, II::ICMP_SLT, II::ICMP_ULT};
925 return {"cmp.gt", FI::FCMP_OGT, II::ICMP_SGT, II::ICMP_UGT};
927 return {"cmp.eq", FI::FCMP_OEQ, II::ICMP_EQ, II::ICMP_EQ};
929 llvm_unreachable("Unrecognised CompareKind enum");
932 if (ArgTy->hasFloatingRepresentation())
933 return Builder.CreateFCmp(InstInfo.FCmp, LHS, RHS,
934 llvm::Twine(InstInfo.Name) + NameSuffix);
935 if (ArgTy->isIntegralOrEnumerationType() || ArgTy->isPointerType()) {
937 ArgTy->hasSignedIntegerRepresentation() ? InstInfo.SCmp : InstInfo.UCmp;
938 return Builder.CreateICmp(Inst, LHS, RHS,
939 llvm::Twine(InstInfo.Name) + NameSuffix);
942 llvm_unreachable("unsupported aggregate binary expression should have "
943 "already been handled");
946 void AggExprEmitter::VisitBinCmp(const BinaryOperator *E) {
947 using llvm::BasicBlock;
950 assert(CGF.getContext().hasSameType(E->getLHS()->getType(),
951 E->getRHS()->getType()));
952 const ComparisonCategoryInfo &CmpInfo =
953 CGF.getContext().CompCategories.getInfoForType(E->getType());
954 assert(CmpInfo.Record->isTriviallyCopyable() &&
955 "cannot copy non-trivially copyable aggregate");
957 QualType ArgTy = E->getLHS()->getType();
959 // TODO: Handle comparing these types.
960 if (ArgTy->isVectorType())
961 return CGF.ErrorUnsupported(
962 E, "aggregate three-way comparison with vector arguments");
963 if (!ArgTy->isIntegralOrEnumerationType() && !ArgTy->isRealFloatingType() &&
964 !ArgTy->isNullPtrType() && !ArgTy->isPointerType() &&
965 !ArgTy->isMemberPointerType() && !ArgTy->isAnyComplexType()) {
966 return CGF.ErrorUnsupported(E, "aggregate three-way comparison");
968 bool IsComplex = ArgTy->isAnyComplexType();
970 // Evaluate the operands to the expression and extract their values.
971 auto EmitOperand = [&](Expr *E) -> std::pair<Value *, Value *> {
972 RValue RV = CGF.EmitAnyExpr(E);
974 return {RV.getScalarVal(), nullptr};
975 if (RV.isAggregate())
976 return {RV.getAggregatePointer(), nullptr};
977 assert(RV.isComplex());
978 return RV.getComplexVal();
980 auto LHSValues = EmitOperand(E->getLHS()),
981 RHSValues = EmitOperand(E->getRHS());
983 auto EmitCmp = [&](CompareKind K) {
984 Value *Cmp = EmitCompare(Builder, CGF, E, LHSValues.first, RHSValues.first,
985 K, IsComplex ? ".r" : "");
988 assert(K == CompareKind::CK_Equal);
989 Value *CmpImag = EmitCompare(Builder, CGF, E, LHSValues.second,
990 RHSValues.second, K, ".i");
991 return Builder.CreateAnd(Cmp, CmpImag, "and.eq");
993 auto EmitCmpRes = [&](const ComparisonCategoryInfo::ValueInfo *VInfo) {
994 return Builder.getInt(VInfo->getIntValue());
998 if (ArgTy->isNullPtrType()) {
999 Select = EmitCmpRes(CmpInfo.getEqualOrEquiv());
1000 } else if (CmpInfo.isEquality()) {
1001 Select = Builder.CreateSelect(
1002 EmitCmp(CK_Equal), EmitCmpRes(CmpInfo.getEqualOrEquiv()),
1003 EmitCmpRes(CmpInfo.getNonequalOrNonequiv()), "sel.eq");
1004 } else if (!CmpInfo.isPartial()) {
1006 Builder.CreateSelect(EmitCmp(CK_Less), EmitCmpRes(CmpInfo.getLess()),
1007 EmitCmpRes(CmpInfo.getGreater()), "sel.lt");
1008 Select = Builder.CreateSelect(EmitCmp(CK_Equal),
1009 EmitCmpRes(CmpInfo.getEqualOrEquiv()),
1010 SelectOne, "sel.eq");
1012 Value *SelectEq = Builder.CreateSelect(
1013 EmitCmp(CK_Equal), EmitCmpRes(CmpInfo.getEqualOrEquiv()),
1014 EmitCmpRes(CmpInfo.getUnordered()), "sel.eq");
1015 Value *SelectGT = Builder.CreateSelect(EmitCmp(CK_Greater),
1016 EmitCmpRes(CmpInfo.getGreater()),
1017 SelectEq, "sel.gt");
1018 Select = Builder.CreateSelect(
1019 EmitCmp(CK_Less), EmitCmpRes(CmpInfo.getLess()), SelectGT, "sel.lt");
1021 // Create the return value in the destination slot.
1022 EnsureDest(E->getType());
1023 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
1025 // Emit the address of the first (and only) field in the comparison category
1026 // type, and initialize it from the constant integer value selected above.
1027 LValue FieldLV = CGF.EmitLValueForFieldInitialization(
1028 DestLV, *CmpInfo.Record->field_begin());
1029 CGF.EmitStoreThroughLValue(RValue::get(Select), FieldLV, /*IsInit*/ true);
1031 // All done! The result is in the Dest slot.
1034 void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
1035 if (E->getOpcode() == BO_PtrMemD || E->getOpcode() == BO_PtrMemI)
1036 VisitPointerToDataMemberBinaryOperator(E);
1038 CGF.ErrorUnsupported(E, "aggregate binary expression");
1041 void AggExprEmitter::VisitPointerToDataMemberBinaryOperator(
1042 const BinaryOperator *E) {
1043 LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E);
1044 EmitFinalDestCopy(E->getType(), LV);
1047 /// Is the value of the given expression possibly a reference to or
1048 /// into a __block variable?
1049 static bool isBlockVarRef(const Expr *E) {
1050 // Make sure we look through parens.
1051 E = E->IgnoreParens();
1053 // Check for a direct reference to a __block variable.
1054 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
1055 const VarDecl *var = dyn_cast<VarDecl>(DRE->getDecl());
1056 return (var && var->hasAttr<BlocksAttr>());
1059 // More complicated stuff.
1061 // Binary operators.
1062 if (const BinaryOperator *op = dyn_cast<BinaryOperator>(E)) {
1063 // For an assignment or pointer-to-member operation, just care
1065 if (op->isAssignmentOp() || op->isPtrMemOp())
1066 return isBlockVarRef(op->getLHS());
1068 // For a comma, just care about the RHS.
1069 if (op->getOpcode() == BO_Comma)
1070 return isBlockVarRef(op->getRHS());
1072 // FIXME: pointer arithmetic?
1075 // Check both sides of a conditional operator.
1076 } else if (const AbstractConditionalOperator *op
1077 = dyn_cast<AbstractConditionalOperator>(E)) {
1078 return isBlockVarRef(op->getTrueExpr())
1079 || isBlockVarRef(op->getFalseExpr());
1081 // OVEs are required to support BinaryConditionalOperators.
1082 } else if (const OpaqueValueExpr *op
1083 = dyn_cast<OpaqueValueExpr>(E)) {
1084 if (const Expr *src = op->getSourceExpr())
1085 return isBlockVarRef(src);
1087 // Casts are necessary to get things like (*(int*)&var) = foo().
1088 // We don't really care about the kind of cast here, except
1089 // we don't want to look through l2r casts, because it's okay
1090 // to get the *value* in a __block variable.
1091 } else if (const CastExpr *cast = dyn_cast<CastExpr>(E)) {
1092 if (cast->getCastKind() == CK_LValueToRValue)
1094 return isBlockVarRef(cast->getSubExpr());
1096 // Handle unary operators. Again, just aggressively look through
1097 // it, ignoring the operation.
1098 } else if (const UnaryOperator *uop = dyn_cast<UnaryOperator>(E)) {
1099 return isBlockVarRef(uop->getSubExpr());
1101 // Look into the base of a field access.
1102 } else if (const MemberExpr *mem = dyn_cast<MemberExpr>(E)) {
1103 return isBlockVarRef(mem->getBase());
1105 // Look into the base of a subscript.
1106 } else if (const ArraySubscriptExpr *sub = dyn_cast<ArraySubscriptExpr>(E)) {
1107 return isBlockVarRef(sub->getBase());
1113 void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
1114 // For an assignment to work, the value on the right has
1115 // to be compatible with the value on the left.
1116 assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(),
1117 E->getRHS()->getType())
1118 && "Invalid assignment");
1120 // If the LHS might be a __block variable, and the RHS can
1121 // potentially cause a block copy, we need to evaluate the RHS first
1122 // so that the assignment goes the right place.
1123 // This is pretty semantically fragile.
1124 if (isBlockVarRef(E->getLHS()) &&
1125 E->getRHS()->HasSideEffects(CGF.getContext())) {
1126 // Ensure that we have a destination, and evaluate the RHS into that.
1127 EnsureDest(E->getRHS()->getType());
1130 // Now emit the LHS and copy into it.
1131 LValue LHS = CGF.EmitCheckedLValue(E->getLHS(), CodeGenFunction::TCK_Store);
1133 // That copy is an atomic copy if the LHS is atomic.
1134 if (LHS.getType()->isAtomicType() ||
1135 CGF.LValueIsSuitableForInlineAtomic(LHS)) {
1136 CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false);
1140 EmitCopy(E->getLHS()->getType(),
1141 AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
1142 needsGC(E->getLHS()->getType()),
1143 AggValueSlot::IsAliased,
1144 AggValueSlot::MayOverlap),
1149 LValue LHS = CGF.EmitLValue(E->getLHS());
1151 // If we have an atomic type, evaluate into the destination and then
1152 // do an atomic copy.
1153 if (LHS.getType()->isAtomicType() ||
1154 CGF.LValueIsSuitableForInlineAtomic(LHS)) {
1155 EnsureDest(E->getRHS()->getType());
1157 CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false);
1161 // Codegen the RHS so that it stores directly into the LHS.
1162 AggValueSlot LHSSlot =
1163 AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
1164 needsGC(E->getLHS()->getType()),
1165 AggValueSlot::IsAliased,
1166 AggValueSlot::MayOverlap);
1167 // A non-volatile aggregate destination might have volatile member.
1168 if (!LHSSlot.isVolatile() &&
1169 CGF.hasVolatileMember(E->getLHS()->getType()))
1170 LHSSlot.setVolatile(true);
1172 CGF.EmitAggExpr(E->getRHS(), LHSSlot);
1174 // Copy into the destination if the assignment isn't ignored.
1175 EmitFinalDestCopy(E->getType(), LHS);
1178 void AggExprEmitter::
1179 VisitAbstractConditionalOperator(const AbstractConditionalOperator *E) {
1180 llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
1181 llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
1182 llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
1184 // Bind the common expression if necessary.
1185 CodeGenFunction::OpaqueValueMapping binding(CGF, E);
1187 CodeGenFunction::ConditionalEvaluation eval(CGF);
1188 CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock,
1189 CGF.getProfileCount(E));
1191 // Save whether the destination's lifetime is externally managed.
1192 bool isExternallyDestructed = Dest.isExternallyDestructed();
1195 CGF.EmitBlock(LHSBlock);
1196 CGF.incrementProfileCounter(E);
1197 Visit(E->getTrueExpr());
1200 assert(CGF.HaveInsertPoint() && "expression evaluation ended with no IP!");
1201 CGF.Builder.CreateBr(ContBlock);
1203 // If the result of an agg expression is unused, then the emission
1204 // of the LHS might need to create a destination slot. That's fine
1205 // with us, and we can safely emit the RHS into the same slot, but
1206 // we shouldn't claim that it's already being destructed.
1207 Dest.setExternallyDestructed(isExternallyDestructed);
1210 CGF.EmitBlock(RHSBlock);
1211 Visit(E->getFalseExpr());
1214 CGF.EmitBlock(ContBlock);
1217 void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
1218 Visit(CE->getChosenSubExpr());
1221 void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
1222 Address ArgValue = Address::invalid();
1223 Address ArgPtr = CGF.EmitVAArg(VE, ArgValue);
1225 // If EmitVAArg fails, emit an error.
1226 if (!ArgPtr.isValid()) {
1227 CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
1231 EmitFinalDestCopy(VE->getType(), CGF.MakeAddrLValue(ArgPtr, VE->getType()));
1234 void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
1235 // Ensure that we have a slot, but if we already do, remember
1236 // whether it was externally destructed.
1237 bool wasExternallyDestructed = Dest.isExternallyDestructed();
1238 EnsureDest(E->getType());
1240 // We're going to push a destructor if there isn't already one.
1241 Dest.setExternallyDestructed();
1243 Visit(E->getSubExpr());
1245 // Push that destructor we promised.
1246 if (!wasExternallyDestructed)
1247 CGF.EmitCXXTemporary(E->getTemporary(), E->getType(), Dest.getAddress());
1251 AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
1252 AggValueSlot Slot = EnsureSlot(E->getType());
1253 CGF.EmitCXXConstructExpr(E, Slot);
1256 void AggExprEmitter::VisitCXXInheritedCtorInitExpr(
1257 const CXXInheritedCtorInitExpr *E) {
1258 AggValueSlot Slot = EnsureSlot(E->getType());
1259 CGF.EmitInheritedCXXConstructorCall(
1260 E->getConstructor(), E->constructsVBase(), Slot.getAddress(),
1261 E->inheritedFromVBase(), E);
1265 AggExprEmitter::VisitLambdaExpr(LambdaExpr *E) {
1266 AggValueSlot Slot = EnsureSlot(E->getType());
1267 CGF.EmitLambdaExpr(E, Slot);
1270 void AggExprEmitter::VisitExprWithCleanups(ExprWithCleanups *E) {
1271 CGF.enterFullExpression(E);
1272 CodeGenFunction::RunCleanupsScope cleanups(CGF);
1273 Visit(E->getSubExpr());
1276 void AggExprEmitter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) {
1277 QualType T = E->getType();
1278 AggValueSlot Slot = EnsureSlot(T);
1279 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddress(), T));
1282 void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
1283 QualType T = E->getType();
1284 AggValueSlot Slot = EnsureSlot(T);
1285 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddress(), T));
1288 /// isSimpleZero - If emitting this value will obviously just cause a store of
1289 /// zero to memory, return true. This can return false if uncertain, so it just
1290 /// handles simple cases.
1291 static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) {
1292 E = E->IgnoreParens();
1295 if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E))
1296 return IL->getValue() == 0;
1298 if (const FloatingLiteral *FL = dyn_cast<FloatingLiteral>(E))
1299 return FL->getValue().isPosZero();
1301 if ((isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) &&
1302 CGF.getTypes().isZeroInitializable(E->getType()))
1304 // (int*)0 - Null pointer expressions.
1305 if (const CastExpr *ICE = dyn_cast<CastExpr>(E))
1306 return ICE->getCastKind() == CK_NullToPointer &&
1307 CGF.getTypes().isPointerZeroInitializable(E->getType());
1309 if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E))
1310 return CL->getValue() == 0;
1312 // Otherwise, hard case: conservatively return false.
1318 AggExprEmitter::EmitInitializationToLValue(Expr *E, LValue LV) {
1319 QualType type = LV.getType();
1320 // FIXME: Ignore result?
1321 // FIXME: Are initializers affected by volatile?
1322 if (Dest.isZeroed() && isSimpleZero(E, CGF)) {
1323 // Storing "i32 0" to a zero'd memory location is a noop.
1325 } else if (isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) {
1326 return EmitNullInitializationToLValue(LV);
1327 } else if (isa<NoInitExpr>(E)) {
1330 } else if (type->isReferenceType()) {
1331 RValue RV = CGF.EmitReferenceBindingToExpr(E);
1332 return CGF.EmitStoreThroughLValue(RV, LV);
1335 switch (CGF.getEvaluationKind(type)) {
1337 CGF.EmitComplexExprIntoLValue(E, LV, /*isInit*/ true);
1340 CGF.EmitAggExpr(E, AggValueSlot::forLValue(LV,
1341 AggValueSlot::IsDestructed,
1342 AggValueSlot::DoesNotNeedGCBarriers,
1343 AggValueSlot::IsNotAliased,
1344 AggValueSlot::MayOverlap,
1348 if (LV.isSimple()) {
1349 CGF.EmitScalarInit(E, /*D=*/nullptr, LV, /*Captured=*/false);
1351 CGF.EmitStoreThroughLValue(RValue::get(CGF.EmitScalarExpr(E)), LV);
1355 llvm_unreachable("bad evaluation kind");
1358 void AggExprEmitter::EmitNullInitializationToLValue(LValue lv) {
1359 QualType type = lv.getType();
1361 // If the destination slot is already zeroed out before the aggregate is
1362 // copied into it, we don't have to emit any zeros here.
1363 if (Dest.isZeroed() && CGF.getTypes().isZeroInitializable(type))
1366 if (CGF.hasScalarEvaluationKind(type)) {
1367 // For non-aggregates, we can store the appropriate null constant.
1368 llvm::Value *null = CGF.CGM.EmitNullConstant(type);
1369 // Note that the following is not equivalent to
1370 // EmitStoreThroughBitfieldLValue for ARC types.
1371 if (lv.isBitField()) {
1372 CGF.EmitStoreThroughBitfieldLValue(RValue::get(null), lv);
1374 assert(lv.isSimple());
1375 CGF.EmitStoreOfScalar(null, lv, /* isInitialization */ true);
1378 // There's a potential optimization opportunity in combining
1379 // memsets; that would be easy for arrays, but relatively
1380 // difficult for structures with the current code.
1381 CGF.EmitNullInitialization(lv.getAddress(), lv.getType());
1385 void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
1387 // FIXME: Assess perf here? Figure out what cases are worth optimizing here
1388 // (Length of globals? Chunks of zeroed-out space?).
1390 // If we can, prefer a copy from a global; this is a lot less code for long
1391 // globals, and it's easier for the current optimizers to analyze.
1392 if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
1393 llvm::GlobalVariable* GV =
1394 new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
1395 llvm::GlobalValue::InternalLinkage, C, "");
1396 EmitFinalDestCopy(E->getType(), CGF.MakeAddrLValue(GV, E->getType()));
1400 if (E->hadArrayRangeDesignator())
1401 CGF.ErrorUnsupported(E, "GNU array range designator extension");
1403 if (E->isTransparent())
1404 return Visit(E->getInit(0));
1406 AggValueSlot Dest = EnsureSlot(E->getType());
1408 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
1410 // Handle initialization of an array.
1411 if (E->getType()->isArrayType()) {
1412 auto AType = cast<llvm::ArrayType>(Dest.getAddress().getElementType());
1413 EmitArrayInit(Dest.getAddress(), AType, E->getType(), E);
1417 assert(E->getType()->isRecordType() && "Only support structs/unions here!");
1419 // Do struct initialization; this code just sets each individual member
1420 // to the approprate value. This makes bitfield support automatic;
1421 // the disadvantage is that the generated code is more difficult for
1422 // the optimizer, especially with bitfields.
1423 unsigned NumInitElements = E->getNumInits();
1424 RecordDecl *record = E->getType()->castAs<RecordType>()->getDecl();
1426 // We'll need to enter cleanup scopes in case any of the element
1427 // initializers throws an exception.
1428 SmallVector<EHScopeStack::stable_iterator, 16> cleanups;
1429 llvm::Instruction *cleanupDominator = nullptr;
1431 unsigned curInitIndex = 0;
1433 // Emit initialization of base classes.
1434 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(record)) {
1435 assert(E->getNumInits() >= CXXRD->getNumBases() &&
1436 "missing initializer for base class");
1437 for (auto &Base : CXXRD->bases()) {
1438 assert(!Base.isVirtual() && "should not see vbases here");
1439 auto *BaseRD = Base.getType()->getAsCXXRecordDecl();
1440 Address V = CGF.GetAddressOfDirectBaseInCompleteClass(
1441 Dest.getAddress(), CXXRD, BaseRD,
1442 /*isBaseVirtual*/ false);
1443 AggValueSlot AggSlot = AggValueSlot::forAddr(
1445 AggValueSlot::IsDestructed,
1446 AggValueSlot::DoesNotNeedGCBarriers,
1447 AggValueSlot::IsNotAliased,
1448 CGF.overlapForBaseInit(CXXRD, BaseRD, Base.isVirtual()));
1449 CGF.EmitAggExpr(E->getInit(curInitIndex++), AggSlot);
1451 if (QualType::DestructionKind dtorKind =
1452 Base.getType().isDestructedType()) {
1453 CGF.pushDestroy(dtorKind, V, Base.getType());
1454 cleanups.push_back(CGF.EHStack.stable_begin());
1459 // Prepare a 'this' for CXXDefaultInitExprs.
1460 CodeGenFunction::FieldConstructionScope FCS(CGF, Dest.getAddress());
1462 if (record->isUnion()) {
1463 // Only initialize one field of a union. The field itself is
1464 // specified by the initializer list.
1465 if (!E->getInitializedFieldInUnion()) {
1466 // Empty union; we have nothing to do.
1469 // Make sure that it's really an empty and not a failure of
1470 // semantic analysis.
1471 for (const auto *Field : record->fields())
1472 assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
1477 // FIXME: volatility
1478 FieldDecl *Field = E->getInitializedFieldInUnion();
1480 LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestLV, Field);
1481 if (NumInitElements) {
1482 // Store the initializer into the field
1483 EmitInitializationToLValue(E->getInit(0), FieldLoc);
1485 // Default-initialize to null.
1486 EmitNullInitializationToLValue(FieldLoc);
1492 // Here we iterate over the fields; this makes it simpler to both
1493 // default-initialize fields and skip over unnamed fields.
1494 for (const auto *field : record->fields()) {
1495 // We're done once we hit the flexible array member.
1496 if (field->getType()->isIncompleteArrayType())
1499 // Always skip anonymous bitfields.
1500 if (field->isUnnamedBitfield())
1503 // We're done if we reach the end of the explicit initializers, we
1504 // have a zeroed object, and the rest of the fields are
1505 // zero-initializable.
1506 if (curInitIndex == NumInitElements && Dest.isZeroed() &&
1507 CGF.getTypes().isZeroInitializable(E->getType()))
1511 LValue LV = CGF.EmitLValueForFieldInitialization(DestLV, field);
1512 // We never generate write-barries for initialized fields.
1515 if (curInitIndex < NumInitElements) {
1516 // Store the initializer into the field.
1517 EmitInitializationToLValue(E->getInit(curInitIndex++), LV);
1519 // We're out of initializers; default-initialize to null
1520 EmitNullInitializationToLValue(LV);
1523 // Push a destructor if necessary.
1524 // FIXME: if we have an array of structures, all explicitly
1525 // initialized, we can end up pushing a linear number of cleanups.
1526 bool pushedCleanup = false;
1527 if (QualType::DestructionKind dtorKind
1528 = field->getType().isDestructedType()) {
1529 assert(LV.isSimple());
1530 if (CGF.needsEHCleanup(dtorKind)) {
1531 if (!cleanupDominator)
1532 cleanupDominator = CGF.Builder.CreateAlignedLoad(
1534 llvm::Constant::getNullValue(CGF.Int8PtrTy),
1535 CharUnits::One()); // placeholder
1537 CGF.pushDestroy(EHCleanup, LV.getAddress(), field->getType(),
1538 CGF.getDestroyer(dtorKind), false);
1539 cleanups.push_back(CGF.EHStack.stable_begin());
1540 pushedCleanup = true;
1544 // If the GEP didn't get used because of a dead zero init or something
1545 // else, clean it up for -O0 builds and general tidiness.
1546 if (!pushedCleanup && LV.isSimple())
1547 if (llvm::GetElementPtrInst *GEP =
1548 dyn_cast<llvm::GetElementPtrInst>(LV.getPointer()))
1549 if (GEP->use_empty())
1550 GEP->eraseFromParent();
1553 // Deactivate all the partial cleanups in reverse order, which
1554 // generally means popping them.
1555 for (unsigned i = cleanups.size(); i != 0; --i)
1556 CGF.DeactivateCleanupBlock(cleanups[i-1], cleanupDominator);
1558 // Destroy the placeholder if we made one.
1559 if (cleanupDominator)
1560 cleanupDominator->eraseFromParent();
1563 void AggExprEmitter::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E,
1564 llvm::Value *outerBegin) {
1565 // Emit the common subexpression.
1566 CodeGenFunction::OpaqueValueMapping binding(CGF, E->getCommonExpr());
1568 Address destPtr = EnsureSlot(E->getType()).getAddress();
1569 uint64_t numElements = E->getArraySize().getZExtValue();
1574 // destPtr is an array*. Construct an elementType* by drilling down a level.
1575 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
1576 llvm::Value *indices[] = {zero, zero};
1577 llvm::Value *begin = Builder.CreateInBoundsGEP(destPtr.getPointer(), indices,
1580 // Prepare to special-case multidimensional array initialization: we avoid
1581 // emitting multiple destructor loops in that case.
1584 ArrayInitLoopExpr *InnerLoop = dyn_cast<ArrayInitLoopExpr>(E->getSubExpr());
1586 QualType elementType =
1587 CGF.getContext().getAsArrayType(E->getType())->getElementType();
1588 CharUnits elementSize = CGF.getContext().getTypeSizeInChars(elementType);
1589 CharUnits elementAlign =
1590 destPtr.getAlignment().alignmentOfArrayElement(elementSize);
1592 llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1593 llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body");
1595 // Jump into the body.
1596 CGF.EmitBlock(bodyBB);
1597 llvm::PHINode *index =
1598 Builder.CreatePHI(zero->getType(), 2, "arrayinit.index");
1599 index->addIncoming(zero, entryBB);
1600 llvm::Value *element = Builder.CreateInBoundsGEP(begin, index);
1602 // Prepare for a cleanup.
1603 QualType::DestructionKind dtorKind = elementType.isDestructedType();
1604 EHScopeStack::stable_iterator cleanup;
1605 if (CGF.needsEHCleanup(dtorKind) && !InnerLoop) {
1606 if (outerBegin->getType() != element->getType())
1607 outerBegin = Builder.CreateBitCast(outerBegin, element->getType());
1608 CGF.pushRegularPartialArrayCleanup(outerBegin, element, elementType,
1610 CGF.getDestroyer(dtorKind));
1611 cleanup = CGF.EHStack.stable_begin();
1613 dtorKind = QualType::DK_none;
1616 // Emit the actual filler expression.
1618 // Temporaries created in an array initialization loop are destroyed
1619 // at the end of each iteration.
1620 CodeGenFunction::RunCleanupsScope CleanupsScope(CGF);
1621 CodeGenFunction::ArrayInitLoopExprScope Scope(CGF, index);
1623 CGF.MakeAddrLValue(Address(element, elementAlign), elementType);
1626 // If the subexpression is an ArrayInitLoopExpr, share its cleanup.
1627 auto elementSlot = AggValueSlot::forLValue(
1628 elementLV, AggValueSlot::IsDestructed,
1629 AggValueSlot::DoesNotNeedGCBarriers,
1630 AggValueSlot::IsNotAliased,
1631 AggValueSlot::DoesNotOverlap);
1632 AggExprEmitter(CGF, elementSlot, false)
1633 .VisitArrayInitLoopExpr(InnerLoop, outerBegin);
1635 EmitInitializationToLValue(E->getSubExpr(), elementLV);
1638 // Move on to the next element.
1639 llvm::Value *nextIndex = Builder.CreateNUWAdd(
1640 index, llvm::ConstantInt::get(CGF.SizeTy, 1), "arrayinit.next");
1641 index->addIncoming(nextIndex, Builder.GetInsertBlock());
1643 // Leave the loop if we're done.
1644 llvm::Value *done = Builder.CreateICmpEQ(
1645 nextIndex, llvm::ConstantInt::get(CGF.SizeTy, numElements),
1647 llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end");
1648 Builder.CreateCondBr(done, endBB, bodyBB);
1650 CGF.EmitBlock(endBB);
1652 // Leave the partial-array cleanup if we entered one.
1654 CGF.DeactivateCleanupBlock(cleanup, index);
1657 void AggExprEmitter::VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E) {
1658 AggValueSlot Dest = EnsureSlot(E->getType());
1660 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
1661 EmitInitializationToLValue(E->getBase(), DestLV);
1662 VisitInitListExpr(E->getUpdater());
1665 //===----------------------------------------------------------------------===//
1666 // Entry Points into this File
1667 //===----------------------------------------------------------------------===//
1669 /// GetNumNonZeroBytesInInit - Get an approximate count of the number of
1670 /// non-zero bytes that will be stored when outputting the initializer for the
1671 /// specified initializer expression.
1672 static CharUnits GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) {
1673 E = E->IgnoreParens();
1675 // 0 and 0.0 won't require any non-zero stores!
1676 if (isSimpleZero(E, CGF)) return CharUnits::Zero();
1678 // If this is an initlist expr, sum up the size of sizes of the (present)
1679 // elements. If this is something weird, assume the whole thing is non-zero.
1680 const InitListExpr *ILE = dyn_cast<InitListExpr>(E);
1681 while (ILE && ILE->isTransparent())
1682 ILE = dyn_cast<InitListExpr>(ILE->getInit(0));
1683 if (!ILE || !CGF.getTypes().isZeroInitializable(ILE->getType()))
1684 return CGF.getContext().getTypeSizeInChars(E->getType());
1686 // InitListExprs for structs have to be handled carefully. If there are
1687 // reference members, we need to consider the size of the reference, not the
1688 // referencee. InitListExprs for unions and arrays can't have references.
1689 if (const RecordType *RT = E->getType()->getAs<RecordType>()) {
1690 if (!RT->isUnionType()) {
1691 RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
1692 CharUnits NumNonZeroBytes = CharUnits::Zero();
1694 unsigned ILEElement = 0;
1695 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(SD))
1696 while (ILEElement != CXXRD->getNumBases())
1698 GetNumNonZeroBytesInInit(ILE->getInit(ILEElement++), CGF);
1699 for (const auto *Field : SD->fields()) {
1700 // We're done once we hit the flexible array member or run out of
1701 // InitListExpr elements.
1702 if (Field->getType()->isIncompleteArrayType() ||
1703 ILEElement == ILE->getNumInits())
1705 if (Field->isUnnamedBitfield())
1708 const Expr *E = ILE->getInit(ILEElement++);
1710 // Reference values are always non-null and have the width of a pointer.
1711 if (Field->getType()->isReferenceType())
1712 NumNonZeroBytes += CGF.getContext().toCharUnitsFromBits(
1713 CGF.getTarget().getPointerWidth(0));
1715 NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF);
1718 return NumNonZeroBytes;
1723 CharUnits NumNonZeroBytes = CharUnits::Zero();
1724 for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i)
1725 NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF);
1726 return NumNonZeroBytes;
1729 /// CheckAggExprForMemSetUse - If the initializer is large and has a lot of
1730 /// zeros in it, emit a memset and avoid storing the individual zeros.
1732 static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E,
1733 CodeGenFunction &CGF) {
1734 // If the slot is already known to be zeroed, nothing to do. Don't mess with
1736 if (Slot.isZeroed() || Slot.isVolatile() || !Slot.getAddress().isValid())
1739 // C++ objects with a user-declared constructor don't need zero'ing.
1740 if (CGF.getLangOpts().CPlusPlus)
1741 if (const RecordType *RT = CGF.getContext()
1742 .getBaseElementType(E->getType())->getAs<RecordType>()) {
1743 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1744 if (RD->hasUserDeclaredConstructor())
1748 // If the type is 16-bytes or smaller, prefer individual stores over memset.
1749 CharUnits Size = Slot.getPreferredSize(CGF.getContext(), E->getType());
1750 if (Size <= CharUnits::fromQuantity(16))
1753 // Check to see if over 3/4 of the initializer are known to be zero. If so,
1754 // we prefer to emit memset + individual stores for the rest.
1755 CharUnits NumNonZeroBytes = GetNumNonZeroBytesInInit(E, CGF);
1756 if (NumNonZeroBytes*4 > Size)
1759 // Okay, it seems like a good idea to use an initial memset, emit the call.
1760 llvm::Constant *SizeVal = CGF.Builder.getInt64(Size.getQuantity());
1762 Address Loc = Slot.getAddress();
1763 Loc = CGF.Builder.CreateElementBitCast(Loc, CGF.Int8Ty);
1764 CGF.Builder.CreateMemSet(Loc, CGF.Builder.getInt8(0), SizeVal, false);
1766 // Tell the AggExprEmitter that the slot is known zero.
1773 /// EmitAggExpr - Emit the computation of the specified expression of aggregate
1774 /// type. The result is computed into DestPtr. Note that if DestPtr is null,
1775 /// the value of the aggregate expression is not needed. If VolatileDest is
1776 /// true, DestPtr cannot be 0.
1777 void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot) {
1778 assert(E && hasAggregateEvaluationKind(E->getType()) &&
1779 "Invalid aggregate expression to emit");
1780 assert((Slot.getAddress().isValid() || Slot.isIgnored()) &&
1781 "slot has bits but no address");
1783 // Optimize the slot if possible.
1784 CheckAggExprForMemSetUse(Slot, E, *this);
1786 AggExprEmitter(*this, Slot, Slot.isIgnored()).Visit(const_cast<Expr*>(E));
1789 LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) {
1790 assert(hasAggregateEvaluationKind(E->getType()) && "Invalid argument!");
1791 Address Temp = CreateMemTemp(E->getType());
1792 LValue LV = MakeAddrLValue(Temp, E->getType());
1793 EmitAggExpr(E, AggValueSlot::forLValue(LV, AggValueSlot::IsNotDestructed,
1794 AggValueSlot::DoesNotNeedGCBarriers,
1795 AggValueSlot::IsNotAliased,
1796 AggValueSlot::DoesNotOverlap));
1800 AggValueSlot::Overlap_t CodeGenFunction::overlapForBaseInit(
1801 const CXXRecordDecl *RD, const CXXRecordDecl *BaseRD, bool IsVirtual) {
1802 // Virtual bases are initialized first, in address order, so there's never
1803 // any overlap during their initialization.
1805 // FIXME: Under P0840, this is no longer true: the tail padding of a vbase
1806 // of a field could be reused by a vbase of a containing class.
1808 return AggValueSlot::DoesNotOverlap;
1810 // If the base class is laid out entirely within the nvsize of the derived
1811 // class, its tail padding cannot yet be initialized, so we can issue
1812 // stores at the full width of the base class.
1813 const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD);
1814 if (Layout.getBaseClassOffset(BaseRD) +
1815 getContext().getASTRecordLayout(BaseRD).getSize() <=
1816 Layout.getNonVirtualSize())
1817 return AggValueSlot::DoesNotOverlap;
1819 // The tail padding may contain values we need to preserve.
1820 return AggValueSlot::MayOverlap;
1823 void CodeGenFunction::EmitAggregateCopy(LValue Dest, LValue Src, QualType Ty,
1824 AggValueSlot::Overlap_t MayOverlap,
1826 assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
1828 Address DestPtr = Dest.getAddress();
1829 Address SrcPtr = Src.getAddress();
1831 if (getLangOpts().CPlusPlus) {
1832 if (const RecordType *RT = Ty->getAs<RecordType>()) {
1833 CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl());
1834 assert((Record->hasTrivialCopyConstructor() ||
1835 Record->hasTrivialCopyAssignment() ||
1836 Record->hasTrivialMoveConstructor() ||
1837 Record->hasTrivialMoveAssignment() ||
1838 Record->isUnion()) &&
1839 "Trying to aggregate-copy a type without a trivial copy/move "
1840 "constructor or assignment operator");
1841 // Ignore empty classes in C++.
1842 if (Record->isEmpty())
1847 // Aggregate assignment turns into llvm.memcpy. This is almost valid per
1848 // C99 6.5.16.1p3, which states "If the value being stored in an object is
1849 // read from another object that overlaps in anyway the storage of the first
1850 // object, then the overlap shall be exact and the two objects shall have
1851 // qualified or unqualified versions of a compatible type."
1853 // memcpy is not defined if the source and destination pointers are exactly
1854 // equal, but other compilers do this optimization, and almost every memcpy
1855 // implementation handles this case safely. If there is a libc that does not
1856 // safely handle this, we can add a target hook.
1858 // Get data size info for this aggregate. Don't copy the tail padding if this
1859 // might be a potentially-overlapping subobject, since the tail padding might
1860 // be occupied by a different object. Otherwise, copying it is fine.
1861 std::pair<CharUnits, CharUnits> TypeInfo;
1863 TypeInfo = getContext().getTypeInfoDataSizeInChars(Ty);
1865 TypeInfo = getContext().getTypeInfoInChars(Ty);
1867 llvm::Value *SizeVal = nullptr;
1868 if (TypeInfo.first.isZero()) {
1869 // But note that getTypeInfo returns 0 for a VLA.
1870 if (auto *VAT = dyn_cast_or_null<VariableArrayType>(
1871 getContext().getAsArrayType(Ty))) {
1873 SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
1874 TypeInfo = getContext().getTypeInfoInChars(BaseEltTy);
1875 assert(!TypeInfo.first.isZero());
1876 SizeVal = Builder.CreateNUWMul(
1878 llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity()));
1882 SizeVal = llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity());
1885 // FIXME: If we have a volatile struct, the optimizer can remove what might
1886 // appear to be `extra' memory ops:
1888 // volatile struct { int i; } a, b;
1895 // we need to use a different call here. We use isVolatile to indicate when
1896 // either the source or the destination is volatile.
1898 DestPtr = Builder.CreateElementBitCast(DestPtr, Int8Ty);
1899 SrcPtr = Builder.CreateElementBitCast(SrcPtr, Int8Ty);
1901 // Don't do any of the memmove_collectable tests if GC isn't set.
1902 if (CGM.getLangOpts().getGC() == LangOptions::NonGC) {
1904 } else if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
1905 RecordDecl *Record = RecordTy->getDecl();
1906 if (Record->hasObjectMember()) {
1907 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1911 } else if (Ty->isArrayType()) {
1912 QualType BaseType = getContext().getBaseElementType(Ty);
1913 if (const RecordType *RecordTy = BaseType->getAs<RecordType>()) {
1914 if (RecordTy->getDecl()->hasObjectMember()) {
1915 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1922 auto Inst = Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, isVolatile);
1924 // Determine the metadata to describe the position of any padding in this
1925 // memcpy, as well as the TBAA tags for the members of the struct, in case
1926 // the optimizer wishes to expand it in to scalar memory operations.
1927 if (llvm::MDNode *TBAAStructTag = CGM.getTBAAStructInfo(Ty))
1928 Inst->setMetadata(llvm::LLVMContext::MD_tbaa_struct, TBAAStructTag);
1930 if (CGM.getCodeGenOpts().NewStructPathTBAA) {
1931 TBAAAccessInfo TBAAInfo = CGM.mergeTBAAInfoForMemoryTransfer(
1932 Dest.getTBAAInfo(), Src.getTBAAInfo());
1933 CGM.DecorateInstructionWithTBAA(Inst, TBAAInfo);