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"
15 #include "CGObjCRuntime.h"
16 #include "CodeGenModule.h"
17 #include "clang/AST/ASTContext.h"
18 #include "clang/AST/DeclCXX.h"
19 #include "clang/AST/DeclTemplate.h"
20 #include "clang/AST/StmtVisitor.h"
21 #include "llvm/IR/Constants.h"
22 #include "llvm/IR/Function.h"
23 #include "llvm/IR/GlobalVariable.h"
24 #include "llvm/IR/Intrinsics.h"
25 using namespace clang;
26 using namespace CodeGen;
28 //===----------------------------------------------------------------------===//
29 // Aggregate Expression Emitter
30 //===----------------------------------------------------------------------===//
33 class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
39 /// We want to use 'dest' as the return slot except under two
41 /// - The destination slot requires garbage collection, so we
42 /// need to use the GC API.
43 /// - The destination slot is potentially aliased.
44 bool shouldUseDestForReturnSlot() const {
45 return !(Dest.requiresGCollection() || Dest.isPotentiallyAliased());
48 ReturnValueSlot getReturnValueSlot() const {
49 if (!shouldUseDestForReturnSlot())
50 return ReturnValueSlot();
52 return ReturnValueSlot(Dest.getAddress(), Dest.isVolatile(),
56 AggValueSlot EnsureSlot(QualType T) {
57 if (!Dest.isIgnored()) return Dest;
58 return CGF.CreateAggTemp(T, "agg.tmp.ensured");
60 void EnsureDest(QualType T) {
61 if (!Dest.isIgnored()) return;
62 Dest = CGF.CreateAggTemp(T, "agg.tmp.ensured");
66 AggExprEmitter(CodeGenFunction &cgf, AggValueSlot Dest, bool IsResultUnused)
67 : CGF(cgf), Builder(CGF.Builder), Dest(Dest),
68 IsResultUnused(IsResultUnused) { }
70 //===--------------------------------------------------------------------===//
72 //===--------------------------------------------------------------------===//
74 /// EmitAggLoadOfLValue - Given an expression with aggregate type that
75 /// represents a value lvalue, this method emits the address of the lvalue,
76 /// then loads the result into DestPtr.
77 void EmitAggLoadOfLValue(const Expr *E);
79 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
80 void EmitFinalDestCopy(QualType type, const LValue &src);
81 void EmitFinalDestCopy(QualType type, RValue src);
82 void EmitCopy(QualType type, const AggValueSlot &dest,
83 const AggValueSlot &src);
85 void EmitMoveFromReturnSlot(const Expr *E, RValue Src);
87 void EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
88 QualType elementType, InitListExpr *E);
90 AggValueSlot::NeedsGCBarriers_t needsGC(QualType T) {
91 if (CGF.getLangOpts().getGC() && TypeRequiresGCollection(T))
92 return AggValueSlot::NeedsGCBarriers;
93 return AggValueSlot::DoesNotNeedGCBarriers;
96 bool TypeRequiresGCollection(QualType T);
98 //===--------------------------------------------------------------------===//
100 //===--------------------------------------------------------------------===//
102 void Visit(Expr *E) {
103 ApplyDebugLocation DL(CGF, E);
104 StmtVisitor<AggExprEmitter>::Visit(E);
107 void VisitStmt(Stmt *S) {
108 CGF.ErrorUnsupported(S, "aggregate expression");
110 void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }
111 void VisitGenericSelectionExpr(GenericSelectionExpr *GE) {
112 Visit(GE->getResultExpr());
114 void VisitCoawaitExpr(CoawaitExpr *E) {
115 CGF.EmitCoawaitExpr(*E, Dest, IsResultUnused);
117 void VisitCoyieldExpr(CoyieldExpr *E) {
118 CGF.EmitCoyieldExpr(*E, Dest, IsResultUnused);
120 void VisitUnaryCoawait(UnaryOperator *E) { Visit(E->getSubExpr()); }
121 void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); }
122 void VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) {
123 return Visit(E->getReplacement());
127 void VisitDeclRefExpr(DeclRefExpr *E) { EmitAggLoadOfLValue(E); }
128 void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
129 void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
130 void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
131 void VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
132 void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
133 EmitAggLoadOfLValue(E);
135 void VisitPredefinedExpr(const PredefinedExpr *E) {
136 EmitAggLoadOfLValue(E);
140 void VisitCastExpr(CastExpr *E);
141 void VisitCallExpr(const CallExpr *E);
142 void VisitStmtExpr(const StmtExpr *E);
143 void VisitBinaryOperator(const BinaryOperator *BO);
144 void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO);
145 void VisitBinAssign(const BinaryOperator *E);
146 void VisitBinComma(const BinaryOperator *E);
148 void VisitObjCMessageExpr(ObjCMessageExpr *E);
149 void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
150 EmitAggLoadOfLValue(E);
153 void VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E);
154 void VisitAbstractConditionalOperator(const AbstractConditionalOperator *CO);
155 void VisitChooseExpr(const ChooseExpr *CE);
156 void VisitInitListExpr(InitListExpr *E);
157 void VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E,
158 llvm::Value *outerBegin = nullptr);
159 void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E);
160 void VisitNoInitExpr(NoInitExpr *E) { } // Do nothing.
161 void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
162 Visit(DAE->getExpr());
164 void VisitCXXDefaultInitExpr(CXXDefaultInitExpr *DIE) {
165 CodeGenFunction::CXXDefaultInitExprScope Scope(CGF);
166 Visit(DIE->getExpr());
168 void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
169 void VisitCXXConstructExpr(const CXXConstructExpr *E);
170 void VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E);
171 void VisitLambdaExpr(LambdaExpr *E);
172 void VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E);
173 void VisitExprWithCleanups(ExprWithCleanups *E);
174 void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E);
175 void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
176 void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E);
177 void VisitOpaqueValueExpr(OpaqueValueExpr *E);
179 void VisitPseudoObjectExpr(PseudoObjectExpr *E) {
180 if (E->isGLValue()) {
181 LValue LV = CGF.EmitPseudoObjectLValue(E);
182 return EmitFinalDestCopy(E->getType(), LV);
185 CGF.EmitPseudoObjectRValue(E, EnsureSlot(E->getType()));
188 void VisitVAArgExpr(VAArgExpr *E);
190 void EmitInitializationToLValue(Expr *E, LValue Address);
191 void EmitNullInitializationToLValue(LValue Address);
192 // case Expr::ChooseExprClass:
193 void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); }
194 void VisitAtomicExpr(AtomicExpr *E) {
195 RValue Res = CGF.EmitAtomicExpr(E);
196 EmitFinalDestCopy(E->getType(), Res);
199 } // end anonymous namespace.
201 //===----------------------------------------------------------------------===//
203 //===----------------------------------------------------------------------===//
205 /// EmitAggLoadOfLValue - Given an expression with aggregate type that
206 /// represents a value lvalue, this method emits the address of the lvalue,
207 /// then loads the result into DestPtr.
208 void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
209 LValue LV = CGF.EmitLValue(E);
211 // If the type of the l-value is atomic, then do an atomic load.
212 if (LV.getType()->isAtomicType() || CGF.LValueIsSuitableForInlineAtomic(LV)) {
213 CGF.EmitAtomicLoad(LV, E->getExprLoc(), Dest);
217 EmitFinalDestCopy(E->getType(), LV);
220 /// \brief True if the given aggregate type requires special GC API calls.
221 bool AggExprEmitter::TypeRequiresGCollection(QualType T) {
222 // Only record types have members that might require garbage collection.
223 const RecordType *RecordTy = T->getAs<RecordType>();
224 if (!RecordTy) return false;
226 // Don't mess with non-trivial C++ types.
227 RecordDecl *Record = RecordTy->getDecl();
228 if (isa<CXXRecordDecl>(Record) &&
229 (cast<CXXRecordDecl>(Record)->hasNonTrivialCopyConstructor() ||
230 !cast<CXXRecordDecl>(Record)->hasTrivialDestructor()))
233 // Check whether the type has an object member.
234 return Record->hasObjectMember();
237 /// \brief Perform the final move to DestPtr if for some reason
238 /// getReturnValueSlot() didn't use it directly.
240 /// The idea is that you do something like this:
241 /// RValue Result = EmitSomething(..., getReturnValueSlot());
242 /// EmitMoveFromReturnSlot(E, Result);
244 /// If nothing interferes, this will cause the result to be emitted
245 /// directly into the return value slot. Otherwise, a final move
246 /// will be performed.
247 void AggExprEmitter::EmitMoveFromReturnSlot(const Expr *E, RValue src) {
248 if (shouldUseDestForReturnSlot()) {
249 // Logically, Dest.getAddr() should equal Src.getAggregateAddr().
250 // The possibility of undef rvalues complicates that a lot,
251 // though, so we can't really assert.
255 // Otherwise, copy from there to the destination.
256 assert(Dest.getPointer() != src.getAggregatePointer());
257 EmitFinalDestCopy(E->getType(), src);
260 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
261 void AggExprEmitter::EmitFinalDestCopy(QualType type, RValue src) {
262 assert(src.isAggregate() && "value must be aggregate value!");
263 LValue srcLV = CGF.MakeAddrLValue(src.getAggregateAddress(), type);
264 EmitFinalDestCopy(type, srcLV);
267 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
268 void AggExprEmitter::EmitFinalDestCopy(QualType type, const LValue &src) {
269 // If Dest is ignored, then we're evaluating an aggregate expression
270 // in a context that doesn't care about the result. Note that loads
271 // from volatile l-values force the existence of a non-ignored
273 if (Dest.isIgnored())
276 AggValueSlot srcAgg =
277 AggValueSlot::forLValue(src, AggValueSlot::IsDestructed,
278 needsGC(type), AggValueSlot::IsAliased);
279 EmitCopy(type, Dest, srcAgg);
282 /// Perform a copy from the source into the destination.
284 /// \param type - the type of the aggregate being copied; qualifiers are
286 void AggExprEmitter::EmitCopy(QualType type, const AggValueSlot &dest,
287 const AggValueSlot &src) {
288 if (dest.requiresGCollection()) {
289 CharUnits sz = CGF.getContext().getTypeSizeInChars(type);
290 llvm::Value *size = llvm::ConstantInt::get(CGF.SizeTy, sz.getQuantity());
291 CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
298 // If the result of the assignment is used, copy the LHS there also.
299 // It's volatile if either side is. Use the minimum alignment of
301 CGF.EmitAggregateCopy(dest.getAddress(), src.getAddress(), type,
302 dest.isVolatile() || src.isVolatile());
305 /// \brief Emit the initializer for a std::initializer_list initialized with a
306 /// real initializer list.
308 AggExprEmitter::VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E) {
309 // Emit an array containing the elements. The array is externally destructed
310 // if the std::initializer_list object is.
311 ASTContext &Ctx = CGF.getContext();
312 LValue Array = CGF.EmitLValue(E->getSubExpr());
313 assert(Array.isSimple() && "initializer_list array not a simple lvalue");
314 Address ArrayPtr = Array.getAddress();
316 const ConstantArrayType *ArrayType =
317 Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
318 assert(ArrayType && "std::initializer_list constructed from non-array");
320 // FIXME: Perform the checks on the field types in SemaInit.
321 RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
322 RecordDecl::field_iterator Field = Record->field_begin();
323 if (Field == Record->field_end()) {
324 CGF.ErrorUnsupported(E, "weird std::initializer_list");
329 if (!Field->getType()->isPointerType() ||
330 !Ctx.hasSameType(Field->getType()->getPointeeType(),
331 ArrayType->getElementType())) {
332 CGF.ErrorUnsupported(E, "weird std::initializer_list");
336 AggValueSlot Dest = EnsureSlot(E->getType());
337 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
338 LValue Start = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
339 llvm::Value *Zero = llvm::ConstantInt::get(CGF.PtrDiffTy, 0);
340 llvm::Value *IdxStart[] = { Zero, Zero };
341 llvm::Value *ArrayStart =
342 Builder.CreateInBoundsGEP(ArrayPtr.getPointer(), IdxStart, "arraystart");
343 CGF.EmitStoreThroughLValue(RValue::get(ArrayStart), Start);
346 if (Field == Record->field_end()) {
347 CGF.ErrorUnsupported(E, "weird std::initializer_list");
351 llvm::Value *Size = Builder.getInt(ArrayType->getSize());
352 LValue EndOrLength = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
353 if (Field->getType()->isPointerType() &&
354 Ctx.hasSameType(Field->getType()->getPointeeType(),
355 ArrayType->getElementType())) {
357 llvm::Value *IdxEnd[] = { Zero, Size };
358 llvm::Value *ArrayEnd =
359 Builder.CreateInBoundsGEP(ArrayPtr.getPointer(), IdxEnd, "arrayend");
360 CGF.EmitStoreThroughLValue(RValue::get(ArrayEnd), EndOrLength);
361 } else if (Ctx.hasSameType(Field->getType(), Ctx.getSizeType())) {
363 CGF.EmitStoreThroughLValue(RValue::get(Size), EndOrLength);
365 CGF.ErrorUnsupported(E, "weird std::initializer_list");
370 /// \brief Determine if E is a trivial array filler, that is, one that is
371 /// equivalent to zero-initialization.
372 static bool isTrivialFiller(Expr *E) {
376 if (isa<ImplicitValueInitExpr>(E))
379 if (auto *ILE = dyn_cast<InitListExpr>(E)) {
380 if (ILE->getNumInits())
382 return isTrivialFiller(ILE->getArrayFiller());
385 if (auto *Cons = dyn_cast_or_null<CXXConstructExpr>(E))
386 return Cons->getConstructor()->isDefaultConstructor() &&
387 Cons->getConstructor()->isTrivial();
389 // FIXME: Are there other cases where we can avoid emitting an initializer?
393 /// \brief Emit initialization of an array from an initializer list.
394 void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
395 QualType elementType, InitListExpr *E) {
396 uint64_t NumInitElements = E->getNumInits();
398 uint64_t NumArrayElements = AType->getNumElements();
399 assert(NumInitElements <= NumArrayElements);
401 // DestPtr is an array*. Construct an elementType* by drilling
403 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
404 llvm::Value *indices[] = { zero, zero };
406 Builder.CreateInBoundsGEP(DestPtr.getPointer(), indices, "arrayinit.begin");
408 CharUnits elementSize = CGF.getContext().getTypeSizeInChars(elementType);
409 CharUnits elementAlign =
410 DestPtr.getAlignment().alignmentOfArrayElement(elementSize);
412 // Exception safety requires us to destroy all the
413 // already-constructed members if an initializer throws.
414 // For that, we'll need an EH cleanup.
415 QualType::DestructionKind dtorKind = elementType.isDestructedType();
416 Address endOfInit = Address::invalid();
417 EHScopeStack::stable_iterator cleanup;
418 llvm::Instruction *cleanupDominator = nullptr;
419 if (CGF.needsEHCleanup(dtorKind)) {
420 // In principle we could tell the cleanup where we are more
421 // directly, but the control flow can get so varied here that it
422 // would actually be quite complex. Therefore we go through an
424 endOfInit = CGF.CreateTempAlloca(begin->getType(), CGF.getPointerAlign(),
425 "arrayinit.endOfInit");
426 cleanupDominator = Builder.CreateStore(begin, endOfInit);
427 CGF.pushIrregularPartialArrayCleanup(begin, endOfInit, elementType,
429 CGF.getDestroyer(dtorKind));
430 cleanup = CGF.EHStack.stable_begin();
432 // Otherwise, remember that we didn't need a cleanup.
434 dtorKind = QualType::DK_none;
437 llvm::Value *one = llvm::ConstantInt::get(CGF.SizeTy, 1);
439 // The 'current element to initialize'. The invariants on this
440 // variable are complicated. Essentially, after each iteration of
441 // the loop, it points to the last initialized element, except
442 // that it points to the beginning of the array before any
443 // elements have been initialized.
444 llvm::Value *element = begin;
446 // Emit the explicit initializers.
447 for (uint64_t i = 0; i != NumInitElements; ++i) {
448 // Advance to the next element.
450 element = Builder.CreateInBoundsGEP(element, one, "arrayinit.element");
452 // Tell the cleanup that it needs to destroy up to this
453 // element. TODO: some of these stores can be trivially
454 // observed to be unnecessary.
455 if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit);
459 CGF.MakeAddrLValue(Address(element, elementAlign), elementType);
460 EmitInitializationToLValue(E->getInit(i), elementLV);
463 // Check whether there's a non-trivial array-fill expression.
464 Expr *filler = E->getArrayFiller();
465 bool hasTrivialFiller = isTrivialFiller(filler);
467 // Any remaining elements need to be zero-initialized, possibly
468 // using the filler expression. We can skip this if the we're
469 // emitting to zeroed memory.
470 if (NumInitElements != NumArrayElements &&
471 !(Dest.isZeroed() && hasTrivialFiller &&
472 CGF.getTypes().isZeroInitializable(elementType))) {
474 // Use an actual loop. This is basically
475 // do { *array++ = filler; } while (array != end);
477 // Advance to the start of the rest of the array.
478 if (NumInitElements) {
479 element = Builder.CreateInBoundsGEP(element, one, "arrayinit.start");
480 if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit);
483 // Compute the end of the array.
484 llvm::Value *end = Builder.CreateInBoundsGEP(begin,
485 llvm::ConstantInt::get(CGF.SizeTy, NumArrayElements),
488 llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
489 llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body");
491 // Jump into the body.
492 CGF.EmitBlock(bodyBB);
493 llvm::PHINode *currentElement =
494 Builder.CreatePHI(element->getType(), 2, "arrayinit.cur");
495 currentElement->addIncoming(element, entryBB);
497 // Emit the actual filler expression.
499 // C++1z [class.temporary]p5:
500 // when a default constructor is called to initialize an element of
501 // an array with no corresponding initializer [...] the destruction of
502 // every temporary created in a default argument is sequenced before
503 // the construction of the next array element, if any
504 CodeGenFunction::RunCleanupsScope CleanupsScope(CGF);
506 CGF.MakeAddrLValue(Address(currentElement, elementAlign), elementType);
508 EmitInitializationToLValue(filler, elementLV);
510 EmitNullInitializationToLValue(elementLV);
513 // Move on to the next element.
514 llvm::Value *nextElement =
515 Builder.CreateInBoundsGEP(currentElement, one, "arrayinit.next");
517 // Tell the EH cleanup that we finished with the last element.
518 if (endOfInit.isValid()) Builder.CreateStore(nextElement, endOfInit);
520 // Leave the loop if we're done.
521 llvm::Value *done = Builder.CreateICmpEQ(nextElement, end,
523 llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end");
524 Builder.CreateCondBr(done, endBB, bodyBB);
525 currentElement->addIncoming(nextElement, Builder.GetInsertBlock());
527 CGF.EmitBlock(endBB);
530 // Leave the partial-array cleanup if we entered one.
531 if (dtorKind) CGF.DeactivateCleanupBlock(cleanup, cleanupDominator);
534 //===----------------------------------------------------------------------===//
536 //===----------------------------------------------------------------------===//
538 void AggExprEmitter::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E){
539 Visit(E->GetTemporaryExpr());
542 void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) {
543 EmitFinalDestCopy(e->getType(), CGF.getOpaqueLValueMapping(e));
547 AggExprEmitter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
548 if (Dest.isPotentiallyAliased() &&
549 E->getType().isPODType(CGF.getContext())) {
550 // For a POD type, just emit a load of the lvalue + a copy, because our
551 // compound literal might alias the destination.
552 EmitAggLoadOfLValue(E);
556 AggValueSlot Slot = EnsureSlot(E->getType());
557 CGF.EmitAggExpr(E->getInitializer(), Slot);
560 /// Attempt to look through various unimportant expressions to find a
561 /// cast of the given kind.
562 static Expr *findPeephole(Expr *op, CastKind kind) {
564 op = op->IgnoreParens();
565 if (CastExpr *castE = dyn_cast<CastExpr>(op)) {
566 if (castE->getCastKind() == kind)
567 return castE->getSubExpr();
568 if (castE->getCastKind() == CK_NoOp)
575 void AggExprEmitter::VisitCastExpr(CastExpr *E) {
576 if (const auto *ECE = dyn_cast<ExplicitCastExpr>(E))
577 CGF.CGM.EmitExplicitCastExprType(ECE, &CGF);
578 switch (E->getCastKind()) {
580 // FIXME: Can this actually happen? We have no test coverage for it.
581 assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?");
582 LValue LV = CGF.EmitCheckedLValue(E->getSubExpr(),
583 CodeGenFunction::TCK_Load);
584 // FIXME: Do we also need to handle property references here?
586 CGF.EmitDynamicCast(LV.getAddress(), cast<CXXDynamicCastExpr>(E));
588 CGF.CGM.ErrorUnsupported(E, "non-simple lvalue dynamic_cast");
590 if (!Dest.isIgnored())
591 CGF.CGM.ErrorUnsupported(E, "lvalue dynamic_cast with a destination");
596 // Evaluate even if the destination is ignored.
597 if (Dest.isIgnored()) {
598 CGF.EmitAnyExpr(E->getSubExpr(), AggValueSlot::ignored(),
599 /*ignoreResult=*/true);
603 // GCC union extension
604 QualType Ty = E->getSubExpr()->getType();
606 Builder.CreateElementBitCast(Dest.getAddress(), CGF.ConvertType(Ty));
607 EmitInitializationToLValue(E->getSubExpr(),
608 CGF.MakeAddrLValue(CastPtr, Ty));
612 case CK_DerivedToBase:
613 case CK_BaseToDerived:
614 case CK_UncheckedDerivedToBase: {
615 llvm_unreachable("cannot perform hierarchy conversion in EmitAggExpr: "
616 "should have been unpacked before we got here");
619 case CK_NonAtomicToAtomic:
620 case CK_AtomicToNonAtomic: {
621 bool isToAtomic = (E->getCastKind() == CK_NonAtomicToAtomic);
623 // Determine the atomic and value types.
624 QualType atomicType = E->getSubExpr()->getType();
625 QualType valueType = E->getType();
626 if (isToAtomic) std::swap(atomicType, valueType);
628 assert(atomicType->isAtomicType());
629 assert(CGF.getContext().hasSameUnqualifiedType(valueType,
630 atomicType->castAs<AtomicType>()->getValueType()));
632 // Just recurse normally if we're ignoring the result or the
633 // atomic type doesn't change representation.
634 if (Dest.isIgnored() || !CGF.CGM.isPaddedAtomicType(atomicType)) {
635 return Visit(E->getSubExpr());
638 CastKind peepholeTarget =
639 (isToAtomic ? CK_AtomicToNonAtomic : CK_NonAtomicToAtomic);
641 // These two cases are reverses of each other; try to peephole them.
642 if (Expr *op = findPeephole(E->getSubExpr(), peepholeTarget)) {
643 assert(CGF.getContext().hasSameUnqualifiedType(op->getType(),
645 "peephole significantly changed types?");
649 // If we're converting an r-value of non-atomic type to an r-value
650 // of atomic type, just emit directly into the relevant sub-object.
652 AggValueSlot valueDest = Dest;
653 if (!valueDest.isIgnored() && CGF.CGM.isPaddedAtomicType(atomicType)) {
654 // Zero-initialize. (Strictly speaking, we only need to intialize
655 // the padding at the end, but this is simpler.)
656 if (!Dest.isZeroed())
657 CGF.EmitNullInitialization(Dest.getAddress(), atomicType);
659 // Build a GEP to refer to the subobject.
661 CGF.Builder.CreateStructGEP(valueDest.getAddress(), 0,
663 valueDest = AggValueSlot::forAddr(valueAddr,
664 valueDest.getQualifiers(),
665 valueDest.isExternallyDestructed(),
666 valueDest.requiresGCollection(),
667 valueDest.isPotentiallyAliased(),
668 AggValueSlot::IsZeroed);
671 CGF.EmitAggExpr(E->getSubExpr(), valueDest);
675 // Otherwise, we're converting an atomic type to a non-atomic type.
676 // Make an atomic temporary, emit into that, and then copy the value out.
677 AggValueSlot atomicSlot =
678 CGF.CreateAggTemp(atomicType, "atomic-to-nonatomic.temp");
679 CGF.EmitAggExpr(E->getSubExpr(), atomicSlot);
682 Builder.CreateStructGEP(atomicSlot.getAddress(), 0, CharUnits());
683 RValue rvalue = RValue::getAggregate(valueAddr, atomicSlot.isVolatile());
684 return EmitFinalDestCopy(valueType, rvalue);
687 case CK_LValueToRValue:
688 // If we're loading from a volatile type, force the destination
690 if (E->getSubExpr()->getType().isVolatileQualified()) {
691 EnsureDest(E->getType());
692 return Visit(E->getSubExpr());
698 case CK_UserDefinedConversion:
699 case CK_ConstructorConversion:
700 assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
702 "Implicit cast types must be compatible");
703 Visit(E->getSubExpr());
706 case CK_LValueBitCast:
707 llvm_unreachable("should not be emitting lvalue bitcast as rvalue");
711 case CK_ArrayToPointerDecay:
712 case CK_FunctionToPointerDecay:
713 case CK_NullToPointer:
714 case CK_NullToMemberPointer:
715 case CK_BaseToDerivedMemberPointer:
716 case CK_DerivedToBaseMemberPointer:
717 case CK_MemberPointerToBoolean:
718 case CK_ReinterpretMemberPointer:
719 case CK_IntegralToPointer:
720 case CK_PointerToIntegral:
721 case CK_PointerToBoolean:
724 case CK_IntegralCast:
725 case CK_BooleanToSignedIntegral:
726 case CK_IntegralToBoolean:
727 case CK_IntegralToFloating:
728 case CK_FloatingToIntegral:
729 case CK_FloatingToBoolean:
730 case CK_FloatingCast:
731 case CK_CPointerToObjCPointerCast:
732 case CK_BlockPointerToObjCPointerCast:
733 case CK_AnyPointerToBlockPointerCast:
734 case CK_ObjCObjectLValueCast:
735 case CK_FloatingRealToComplex:
736 case CK_FloatingComplexToReal:
737 case CK_FloatingComplexToBoolean:
738 case CK_FloatingComplexCast:
739 case CK_FloatingComplexToIntegralComplex:
740 case CK_IntegralRealToComplex:
741 case CK_IntegralComplexToReal:
742 case CK_IntegralComplexToBoolean:
743 case CK_IntegralComplexCast:
744 case CK_IntegralComplexToFloatingComplex:
745 case CK_ARCProduceObject:
746 case CK_ARCConsumeObject:
747 case CK_ARCReclaimReturnedObject:
748 case CK_ARCExtendBlockObject:
749 case CK_CopyAndAutoreleaseBlockObject:
750 case CK_BuiltinFnToFnPtr:
751 case CK_ZeroToOCLEvent:
752 case CK_ZeroToOCLQueue:
753 case CK_AddressSpaceConversion:
754 case CK_IntToOCLSampler:
755 llvm_unreachable("cast kind invalid for aggregate types");
759 void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
760 if (E->getCallReturnType(CGF.getContext())->isReferenceType()) {
761 EmitAggLoadOfLValue(E);
765 RValue RV = CGF.EmitCallExpr(E, getReturnValueSlot());
766 EmitMoveFromReturnSlot(E, RV);
769 void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
770 RValue RV = CGF.EmitObjCMessageExpr(E, getReturnValueSlot());
771 EmitMoveFromReturnSlot(E, RV);
774 void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
775 CGF.EmitIgnoredExpr(E->getLHS());
779 void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
780 CodeGenFunction::StmtExprEvaluation eval(CGF);
781 CGF.EmitCompoundStmt(*E->getSubStmt(), true, Dest);
784 void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
785 if (E->getOpcode() == BO_PtrMemD || E->getOpcode() == BO_PtrMemI)
786 VisitPointerToDataMemberBinaryOperator(E);
788 CGF.ErrorUnsupported(E, "aggregate binary expression");
791 void AggExprEmitter::VisitPointerToDataMemberBinaryOperator(
792 const BinaryOperator *E) {
793 LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E);
794 EmitFinalDestCopy(E->getType(), LV);
797 /// Is the value of the given expression possibly a reference to or
798 /// into a __block variable?
799 static bool isBlockVarRef(const Expr *E) {
800 // Make sure we look through parens.
801 E = E->IgnoreParens();
803 // Check for a direct reference to a __block variable.
804 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
805 const VarDecl *var = dyn_cast<VarDecl>(DRE->getDecl());
806 return (var && var->hasAttr<BlocksAttr>());
809 // More complicated stuff.
812 if (const BinaryOperator *op = dyn_cast<BinaryOperator>(E)) {
813 // For an assignment or pointer-to-member operation, just care
815 if (op->isAssignmentOp() || op->isPtrMemOp())
816 return isBlockVarRef(op->getLHS());
818 // For a comma, just care about the RHS.
819 if (op->getOpcode() == BO_Comma)
820 return isBlockVarRef(op->getRHS());
822 // FIXME: pointer arithmetic?
825 // Check both sides of a conditional operator.
826 } else if (const AbstractConditionalOperator *op
827 = dyn_cast<AbstractConditionalOperator>(E)) {
828 return isBlockVarRef(op->getTrueExpr())
829 || isBlockVarRef(op->getFalseExpr());
831 // OVEs are required to support BinaryConditionalOperators.
832 } else if (const OpaqueValueExpr *op
833 = dyn_cast<OpaqueValueExpr>(E)) {
834 if (const Expr *src = op->getSourceExpr())
835 return isBlockVarRef(src);
837 // Casts are necessary to get things like (*(int*)&var) = foo().
838 // We don't really care about the kind of cast here, except
839 // we don't want to look through l2r casts, because it's okay
840 // to get the *value* in a __block variable.
841 } else if (const CastExpr *cast = dyn_cast<CastExpr>(E)) {
842 if (cast->getCastKind() == CK_LValueToRValue)
844 return isBlockVarRef(cast->getSubExpr());
846 // Handle unary operators. Again, just aggressively look through
847 // it, ignoring the operation.
848 } else if (const UnaryOperator *uop = dyn_cast<UnaryOperator>(E)) {
849 return isBlockVarRef(uop->getSubExpr());
851 // Look into the base of a field access.
852 } else if (const MemberExpr *mem = dyn_cast<MemberExpr>(E)) {
853 return isBlockVarRef(mem->getBase());
855 // Look into the base of a subscript.
856 } else if (const ArraySubscriptExpr *sub = dyn_cast<ArraySubscriptExpr>(E)) {
857 return isBlockVarRef(sub->getBase());
863 void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
864 // For an assignment to work, the value on the right has
865 // to be compatible with the value on the left.
866 assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(),
867 E->getRHS()->getType())
868 && "Invalid assignment");
870 // If the LHS might be a __block variable, and the RHS can
871 // potentially cause a block copy, we need to evaluate the RHS first
872 // so that the assignment goes the right place.
873 // This is pretty semantically fragile.
874 if (isBlockVarRef(E->getLHS()) &&
875 E->getRHS()->HasSideEffects(CGF.getContext())) {
876 // Ensure that we have a destination, and evaluate the RHS into that.
877 EnsureDest(E->getRHS()->getType());
880 // Now emit the LHS and copy into it.
881 LValue LHS = CGF.EmitCheckedLValue(E->getLHS(), CodeGenFunction::TCK_Store);
883 // That copy is an atomic copy if the LHS is atomic.
884 if (LHS.getType()->isAtomicType() ||
885 CGF.LValueIsSuitableForInlineAtomic(LHS)) {
886 CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false);
890 EmitCopy(E->getLHS()->getType(),
891 AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
892 needsGC(E->getLHS()->getType()),
893 AggValueSlot::IsAliased),
898 LValue LHS = CGF.EmitLValue(E->getLHS());
900 // If we have an atomic type, evaluate into the destination and then
901 // do an atomic copy.
902 if (LHS.getType()->isAtomicType() ||
903 CGF.LValueIsSuitableForInlineAtomic(LHS)) {
904 EnsureDest(E->getRHS()->getType());
906 CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false);
910 // Codegen the RHS so that it stores directly into the LHS.
911 AggValueSlot LHSSlot =
912 AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
913 needsGC(E->getLHS()->getType()),
914 AggValueSlot::IsAliased);
915 // A non-volatile aggregate destination might have volatile member.
916 if (!LHSSlot.isVolatile() &&
917 CGF.hasVolatileMember(E->getLHS()->getType()))
918 LHSSlot.setVolatile(true);
920 CGF.EmitAggExpr(E->getRHS(), LHSSlot);
922 // Copy into the destination if the assignment isn't ignored.
923 EmitFinalDestCopy(E->getType(), LHS);
926 void AggExprEmitter::
927 VisitAbstractConditionalOperator(const AbstractConditionalOperator *E) {
928 llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
929 llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
930 llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
932 // Bind the common expression if necessary.
933 CodeGenFunction::OpaqueValueMapping binding(CGF, E);
935 CodeGenFunction::ConditionalEvaluation eval(CGF);
936 CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock,
937 CGF.getProfileCount(E));
939 // Save whether the destination's lifetime is externally managed.
940 bool isExternallyDestructed = Dest.isExternallyDestructed();
943 CGF.EmitBlock(LHSBlock);
944 CGF.incrementProfileCounter(E);
945 Visit(E->getTrueExpr());
948 assert(CGF.HaveInsertPoint() && "expression evaluation ended with no IP!");
949 CGF.Builder.CreateBr(ContBlock);
951 // If the result of an agg expression is unused, then the emission
952 // of the LHS might need to create a destination slot. That's fine
953 // with us, and we can safely emit the RHS into the same slot, but
954 // we shouldn't claim that it's already being destructed.
955 Dest.setExternallyDestructed(isExternallyDestructed);
958 CGF.EmitBlock(RHSBlock);
959 Visit(E->getFalseExpr());
962 CGF.EmitBlock(ContBlock);
965 void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
966 Visit(CE->getChosenSubExpr());
969 void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
970 Address ArgValue = Address::invalid();
971 Address ArgPtr = CGF.EmitVAArg(VE, ArgValue);
973 // If EmitVAArg fails, emit an error.
974 if (!ArgPtr.isValid()) {
975 CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
979 EmitFinalDestCopy(VE->getType(), CGF.MakeAddrLValue(ArgPtr, VE->getType()));
982 void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
983 // Ensure that we have a slot, but if we already do, remember
984 // whether it was externally destructed.
985 bool wasExternallyDestructed = Dest.isExternallyDestructed();
986 EnsureDest(E->getType());
988 // We're going to push a destructor if there isn't already one.
989 Dest.setExternallyDestructed();
991 Visit(E->getSubExpr());
993 // Push that destructor we promised.
994 if (!wasExternallyDestructed)
995 CGF.EmitCXXTemporary(E->getTemporary(), E->getType(), Dest.getAddress());
999 AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
1000 AggValueSlot Slot = EnsureSlot(E->getType());
1001 CGF.EmitCXXConstructExpr(E, Slot);
1004 void AggExprEmitter::VisitCXXInheritedCtorInitExpr(
1005 const CXXInheritedCtorInitExpr *E) {
1006 AggValueSlot Slot = EnsureSlot(E->getType());
1007 CGF.EmitInheritedCXXConstructorCall(
1008 E->getConstructor(), E->constructsVBase(), Slot.getAddress(),
1009 E->inheritedFromVBase(), E);
1013 AggExprEmitter::VisitLambdaExpr(LambdaExpr *E) {
1014 AggValueSlot Slot = EnsureSlot(E->getType());
1015 CGF.EmitLambdaExpr(E, Slot);
1018 void AggExprEmitter::VisitExprWithCleanups(ExprWithCleanups *E) {
1019 CGF.enterFullExpression(E);
1020 CodeGenFunction::RunCleanupsScope cleanups(CGF);
1021 Visit(E->getSubExpr());
1024 void AggExprEmitter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) {
1025 QualType T = E->getType();
1026 AggValueSlot Slot = EnsureSlot(T);
1027 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddress(), T));
1030 void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
1031 QualType T = E->getType();
1032 AggValueSlot Slot = EnsureSlot(T);
1033 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddress(), T));
1036 /// isSimpleZero - If emitting this value will obviously just cause a store of
1037 /// zero to memory, return true. This can return false if uncertain, so it just
1038 /// handles simple cases.
1039 static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) {
1040 E = E->IgnoreParens();
1043 if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E))
1044 return IL->getValue() == 0;
1046 if (const FloatingLiteral *FL = dyn_cast<FloatingLiteral>(E))
1047 return FL->getValue().isPosZero();
1049 if ((isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) &&
1050 CGF.getTypes().isZeroInitializable(E->getType()))
1052 // (int*)0 - Null pointer expressions.
1053 if (const CastExpr *ICE = dyn_cast<CastExpr>(E))
1054 return ICE->getCastKind() == CK_NullToPointer &&
1055 CGF.getTypes().isPointerZeroInitializable(E->getType());
1057 if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E))
1058 return CL->getValue() == 0;
1060 // Otherwise, hard case: conservatively return false.
1066 AggExprEmitter::EmitInitializationToLValue(Expr *E, LValue LV) {
1067 QualType type = LV.getType();
1068 // FIXME: Ignore result?
1069 // FIXME: Are initializers affected by volatile?
1070 if (Dest.isZeroed() && isSimpleZero(E, CGF)) {
1071 // Storing "i32 0" to a zero'd memory location is a noop.
1073 } else if (isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) {
1074 return EmitNullInitializationToLValue(LV);
1075 } else if (isa<NoInitExpr>(E)) {
1078 } else if (type->isReferenceType()) {
1079 RValue RV = CGF.EmitReferenceBindingToExpr(E);
1080 return CGF.EmitStoreThroughLValue(RV, LV);
1083 switch (CGF.getEvaluationKind(type)) {
1085 CGF.EmitComplexExprIntoLValue(E, LV, /*isInit*/ true);
1088 CGF.EmitAggExpr(E, AggValueSlot::forLValue(LV,
1089 AggValueSlot::IsDestructed,
1090 AggValueSlot::DoesNotNeedGCBarriers,
1091 AggValueSlot::IsNotAliased,
1095 if (LV.isSimple()) {
1096 CGF.EmitScalarInit(E, /*D=*/nullptr, LV, /*Captured=*/false);
1098 CGF.EmitStoreThroughLValue(RValue::get(CGF.EmitScalarExpr(E)), LV);
1102 llvm_unreachable("bad evaluation kind");
1105 void AggExprEmitter::EmitNullInitializationToLValue(LValue lv) {
1106 QualType type = lv.getType();
1108 // If the destination slot is already zeroed out before the aggregate is
1109 // copied into it, we don't have to emit any zeros here.
1110 if (Dest.isZeroed() && CGF.getTypes().isZeroInitializable(type))
1113 if (CGF.hasScalarEvaluationKind(type)) {
1114 // For non-aggregates, we can store the appropriate null constant.
1115 llvm::Value *null = CGF.CGM.EmitNullConstant(type);
1116 // Note that the following is not equivalent to
1117 // EmitStoreThroughBitfieldLValue for ARC types.
1118 if (lv.isBitField()) {
1119 CGF.EmitStoreThroughBitfieldLValue(RValue::get(null), lv);
1121 assert(lv.isSimple());
1122 CGF.EmitStoreOfScalar(null, lv, /* isInitialization */ true);
1125 // There's a potential optimization opportunity in combining
1126 // memsets; that would be easy for arrays, but relatively
1127 // difficult for structures with the current code.
1128 CGF.EmitNullInitialization(lv.getAddress(), lv.getType());
1132 void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
1134 // FIXME: Assess perf here? Figure out what cases are worth optimizing here
1135 // (Length of globals? Chunks of zeroed-out space?).
1137 // If we can, prefer a copy from a global; this is a lot less code for long
1138 // globals, and it's easier for the current optimizers to analyze.
1139 if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
1140 llvm::GlobalVariable* GV =
1141 new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
1142 llvm::GlobalValue::InternalLinkage, C, "");
1143 EmitFinalDestCopy(E->getType(), CGF.MakeAddrLValue(GV, E->getType()));
1147 if (E->hadArrayRangeDesignator())
1148 CGF.ErrorUnsupported(E, "GNU array range designator extension");
1150 if (E->isTransparent())
1151 return Visit(E->getInit(0));
1153 AggValueSlot Dest = EnsureSlot(E->getType());
1155 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
1157 // Handle initialization of an array.
1158 if (E->getType()->isArrayType()) {
1159 QualType elementType =
1160 CGF.getContext().getAsArrayType(E->getType())->getElementType();
1162 auto AType = cast<llvm::ArrayType>(Dest.getAddress().getElementType());
1163 EmitArrayInit(Dest.getAddress(), AType, elementType, E);
1167 assert(E->getType()->isRecordType() && "Only support structs/unions here!");
1169 // Do struct initialization; this code just sets each individual member
1170 // to the approprate value. This makes bitfield support automatic;
1171 // the disadvantage is that the generated code is more difficult for
1172 // the optimizer, especially with bitfields.
1173 unsigned NumInitElements = E->getNumInits();
1174 RecordDecl *record = E->getType()->castAs<RecordType>()->getDecl();
1176 // We'll need to enter cleanup scopes in case any of the element
1177 // initializers throws an exception.
1178 SmallVector<EHScopeStack::stable_iterator, 16> cleanups;
1179 llvm::Instruction *cleanupDominator = nullptr;
1181 unsigned curInitIndex = 0;
1183 // Emit initialization of base classes.
1184 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(record)) {
1185 assert(E->getNumInits() >= CXXRD->getNumBases() &&
1186 "missing initializer for base class");
1187 for (auto &Base : CXXRD->bases()) {
1188 assert(!Base.isVirtual() && "should not see vbases here");
1189 auto *BaseRD = Base.getType()->getAsCXXRecordDecl();
1190 Address V = CGF.GetAddressOfDirectBaseInCompleteClass(
1191 Dest.getAddress(), CXXRD, BaseRD,
1192 /*isBaseVirtual*/ false);
1193 AggValueSlot AggSlot =
1194 AggValueSlot::forAddr(V, Qualifiers(),
1195 AggValueSlot::IsDestructed,
1196 AggValueSlot::DoesNotNeedGCBarriers,
1197 AggValueSlot::IsNotAliased);
1198 CGF.EmitAggExpr(E->getInit(curInitIndex++), AggSlot);
1200 if (QualType::DestructionKind dtorKind =
1201 Base.getType().isDestructedType()) {
1202 CGF.pushDestroy(dtorKind, V, Base.getType());
1203 cleanups.push_back(CGF.EHStack.stable_begin());
1208 // Prepare a 'this' for CXXDefaultInitExprs.
1209 CodeGenFunction::FieldConstructionScope FCS(CGF, Dest.getAddress());
1211 if (record->isUnion()) {
1212 // Only initialize one field of a union. The field itself is
1213 // specified by the initializer list.
1214 if (!E->getInitializedFieldInUnion()) {
1215 // Empty union; we have nothing to do.
1218 // Make sure that it's really an empty and not a failure of
1219 // semantic analysis.
1220 for (const auto *Field : record->fields())
1221 assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
1226 // FIXME: volatility
1227 FieldDecl *Field = E->getInitializedFieldInUnion();
1229 LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestLV, Field);
1230 if (NumInitElements) {
1231 // Store the initializer into the field
1232 EmitInitializationToLValue(E->getInit(0), FieldLoc);
1234 // Default-initialize to null.
1235 EmitNullInitializationToLValue(FieldLoc);
1241 // Here we iterate over the fields; this makes it simpler to both
1242 // default-initialize fields and skip over unnamed fields.
1243 for (const auto *field : record->fields()) {
1244 // We're done once we hit the flexible array member.
1245 if (field->getType()->isIncompleteArrayType())
1248 // Always skip anonymous bitfields.
1249 if (field->isUnnamedBitfield())
1252 // We're done if we reach the end of the explicit initializers, we
1253 // have a zeroed object, and the rest of the fields are
1254 // zero-initializable.
1255 if (curInitIndex == NumInitElements && Dest.isZeroed() &&
1256 CGF.getTypes().isZeroInitializable(E->getType()))
1260 LValue LV = CGF.EmitLValueForFieldInitialization(DestLV, field);
1261 // We never generate write-barries for initialized fields.
1264 if (curInitIndex < NumInitElements) {
1265 // Store the initializer into the field.
1266 EmitInitializationToLValue(E->getInit(curInitIndex++), LV);
1268 // We're out of initializers; default-initialize to null
1269 EmitNullInitializationToLValue(LV);
1272 // Push a destructor if necessary.
1273 // FIXME: if we have an array of structures, all explicitly
1274 // initialized, we can end up pushing a linear number of cleanups.
1275 bool pushedCleanup = false;
1276 if (QualType::DestructionKind dtorKind
1277 = field->getType().isDestructedType()) {
1278 assert(LV.isSimple());
1279 if (CGF.needsEHCleanup(dtorKind)) {
1280 if (!cleanupDominator)
1281 cleanupDominator = CGF.Builder.CreateAlignedLoad(
1283 llvm::Constant::getNullValue(CGF.Int8PtrTy),
1284 CharUnits::One()); // placeholder
1286 CGF.pushDestroy(EHCleanup, LV.getAddress(), field->getType(),
1287 CGF.getDestroyer(dtorKind), false);
1288 cleanups.push_back(CGF.EHStack.stable_begin());
1289 pushedCleanup = true;
1293 // If the GEP didn't get used because of a dead zero init or something
1294 // else, clean it up for -O0 builds and general tidiness.
1295 if (!pushedCleanup && LV.isSimple())
1296 if (llvm::GetElementPtrInst *GEP =
1297 dyn_cast<llvm::GetElementPtrInst>(LV.getPointer()))
1298 if (GEP->use_empty())
1299 GEP->eraseFromParent();
1302 // Deactivate all the partial cleanups in reverse order, which
1303 // generally means popping them.
1304 for (unsigned i = cleanups.size(); i != 0; --i)
1305 CGF.DeactivateCleanupBlock(cleanups[i-1], cleanupDominator);
1307 // Destroy the placeholder if we made one.
1308 if (cleanupDominator)
1309 cleanupDominator->eraseFromParent();
1312 void AggExprEmitter::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E,
1313 llvm::Value *outerBegin) {
1314 // Emit the common subexpression.
1315 CodeGenFunction::OpaqueValueMapping binding(CGF, E->getCommonExpr());
1317 Address destPtr = EnsureSlot(E->getType()).getAddress();
1318 uint64_t numElements = E->getArraySize().getZExtValue();
1323 // destPtr is an array*. Construct an elementType* by drilling down a level.
1324 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
1325 llvm::Value *indices[] = {zero, zero};
1326 llvm::Value *begin = Builder.CreateInBoundsGEP(destPtr.getPointer(), indices,
1329 // Prepare to special-case multidimensional array initialization: we avoid
1330 // emitting multiple destructor loops in that case.
1333 ArrayInitLoopExpr *InnerLoop = dyn_cast<ArrayInitLoopExpr>(E->getSubExpr());
1335 QualType elementType =
1336 CGF.getContext().getAsArrayType(E->getType())->getElementType();
1337 CharUnits elementSize = CGF.getContext().getTypeSizeInChars(elementType);
1338 CharUnits elementAlign =
1339 destPtr.getAlignment().alignmentOfArrayElement(elementSize);
1341 llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
1342 llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body");
1344 // Jump into the body.
1345 CGF.EmitBlock(bodyBB);
1346 llvm::PHINode *index =
1347 Builder.CreatePHI(zero->getType(), 2, "arrayinit.index");
1348 index->addIncoming(zero, entryBB);
1349 llvm::Value *element = Builder.CreateInBoundsGEP(begin, index);
1351 // Prepare for a cleanup.
1352 QualType::DestructionKind dtorKind = elementType.isDestructedType();
1353 EHScopeStack::stable_iterator cleanup;
1354 if (CGF.needsEHCleanup(dtorKind) && !InnerLoop) {
1355 if (outerBegin->getType() != element->getType())
1356 outerBegin = Builder.CreateBitCast(outerBegin, element->getType());
1357 CGF.pushRegularPartialArrayCleanup(outerBegin, element, elementType,
1359 CGF.getDestroyer(dtorKind));
1360 cleanup = CGF.EHStack.stable_begin();
1362 dtorKind = QualType::DK_none;
1365 // Emit the actual filler expression.
1367 // Temporaries created in an array initialization loop are destroyed
1368 // at the end of each iteration.
1369 CodeGenFunction::RunCleanupsScope CleanupsScope(CGF);
1370 CodeGenFunction::ArrayInitLoopExprScope Scope(CGF, index);
1372 CGF.MakeAddrLValue(Address(element, elementAlign), elementType);
1375 // If the subexpression is an ArrayInitLoopExpr, share its cleanup.
1376 auto elementSlot = AggValueSlot::forLValue(
1377 elementLV, AggValueSlot::IsDestructed,
1378 AggValueSlot::DoesNotNeedGCBarriers, AggValueSlot::IsNotAliased);
1379 AggExprEmitter(CGF, elementSlot, false)
1380 .VisitArrayInitLoopExpr(InnerLoop, outerBegin);
1382 EmitInitializationToLValue(E->getSubExpr(), elementLV);
1385 // Move on to the next element.
1386 llvm::Value *nextIndex = Builder.CreateNUWAdd(
1387 index, llvm::ConstantInt::get(CGF.SizeTy, 1), "arrayinit.next");
1388 index->addIncoming(nextIndex, Builder.GetInsertBlock());
1390 // Leave the loop if we're done.
1391 llvm::Value *done = Builder.CreateICmpEQ(
1392 nextIndex, llvm::ConstantInt::get(CGF.SizeTy, numElements),
1394 llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end");
1395 Builder.CreateCondBr(done, endBB, bodyBB);
1397 CGF.EmitBlock(endBB);
1399 // Leave the partial-array cleanup if we entered one.
1401 CGF.DeactivateCleanupBlock(cleanup, index);
1404 void AggExprEmitter::VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E) {
1405 AggValueSlot Dest = EnsureSlot(E->getType());
1407 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
1408 EmitInitializationToLValue(E->getBase(), DestLV);
1409 VisitInitListExpr(E->getUpdater());
1412 //===----------------------------------------------------------------------===//
1413 // Entry Points into this File
1414 //===----------------------------------------------------------------------===//
1416 /// GetNumNonZeroBytesInInit - Get an approximate count of the number of
1417 /// non-zero bytes that will be stored when outputting the initializer for the
1418 /// specified initializer expression.
1419 static CharUnits GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) {
1420 E = E->IgnoreParens();
1422 // 0 and 0.0 won't require any non-zero stores!
1423 if (isSimpleZero(E, CGF)) return CharUnits::Zero();
1425 // If this is an initlist expr, sum up the size of sizes of the (present)
1426 // elements. If this is something weird, assume the whole thing is non-zero.
1427 const InitListExpr *ILE = dyn_cast<InitListExpr>(E);
1428 if (!ILE || !CGF.getTypes().isZeroInitializable(ILE->getType()))
1429 return CGF.getContext().getTypeSizeInChars(E->getType());
1431 // InitListExprs for structs have to be handled carefully. If there are
1432 // reference members, we need to consider the size of the reference, not the
1433 // referencee. InitListExprs for unions and arrays can't have references.
1434 if (const RecordType *RT = E->getType()->getAs<RecordType>()) {
1435 if (!RT->isUnionType()) {
1436 RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
1437 CharUnits NumNonZeroBytes = CharUnits::Zero();
1439 unsigned ILEElement = 0;
1440 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(SD))
1441 while (ILEElement != CXXRD->getNumBases())
1443 GetNumNonZeroBytesInInit(ILE->getInit(ILEElement++), CGF);
1444 for (const auto *Field : SD->fields()) {
1445 // We're done once we hit the flexible array member or run out of
1446 // InitListExpr elements.
1447 if (Field->getType()->isIncompleteArrayType() ||
1448 ILEElement == ILE->getNumInits())
1450 if (Field->isUnnamedBitfield())
1453 const Expr *E = ILE->getInit(ILEElement++);
1455 // Reference values are always non-null and have the width of a pointer.
1456 if (Field->getType()->isReferenceType())
1457 NumNonZeroBytes += CGF.getContext().toCharUnitsFromBits(
1458 CGF.getTarget().getPointerWidth(0));
1460 NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF);
1463 return NumNonZeroBytes;
1468 CharUnits NumNonZeroBytes = CharUnits::Zero();
1469 for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i)
1470 NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF);
1471 return NumNonZeroBytes;
1474 /// CheckAggExprForMemSetUse - If the initializer is large and has a lot of
1475 /// zeros in it, emit a memset and avoid storing the individual zeros.
1477 static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E,
1478 CodeGenFunction &CGF) {
1479 // If the slot is already known to be zeroed, nothing to do. Don't mess with
1481 if (Slot.isZeroed() || Slot.isVolatile() || !Slot.getAddress().isValid())
1484 // C++ objects with a user-declared constructor don't need zero'ing.
1485 if (CGF.getLangOpts().CPlusPlus)
1486 if (const RecordType *RT = CGF.getContext()
1487 .getBaseElementType(E->getType())->getAs<RecordType>()) {
1488 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1489 if (RD->hasUserDeclaredConstructor())
1493 // If the type is 16-bytes or smaller, prefer individual stores over memset.
1494 CharUnits Size = CGF.getContext().getTypeSizeInChars(E->getType());
1495 if (Size <= CharUnits::fromQuantity(16))
1498 // Check to see if over 3/4 of the initializer are known to be zero. If so,
1499 // we prefer to emit memset + individual stores for the rest.
1500 CharUnits NumNonZeroBytes = GetNumNonZeroBytesInInit(E, CGF);
1501 if (NumNonZeroBytes*4 > Size)
1504 // Okay, it seems like a good idea to use an initial memset, emit the call.
1505 llvm::Constant *SizeVal = CGF.Builder.getInt64(Size.getQuantity());
1507 Address Loc = Slot.getAddress();
1508 Loc = CGF.Builder.CreateElementBitCast(Loc, CGF.Int8Ty);
1509 CGF.Builder.CreateMemSet(Loc, CGF.Builder.getInt8(0), SizeVal, false);
1511 // Tell the AggExprEmitter that the slot is known zero.
1518 /// EmitAggExpr - Emit the computation of the specified expression of aggregate
1519 /// type. The result is computed into DestPtr. Note that if DestPtr is null,
1520 /// the value of the aggregate expression is not needed. If VolatileDest is
1521 /// true, DestPtr cannot be 0.
1522 void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot) {
1523 assert(E && hasAggregateEvaluationKind(E->getType()) &&
1524 "Invalid aggregate expression to emit");
1525 assert((Slot.getAddress().isValid() || Slot.isIgnored()) &&
1526 "slot has bits but no address");
1528 // Optimize the slot if possible.
1529 CheckAggExprForMemSetUse(Slot, E, *this);
1531 AggExprEmitter(*this, Slot, Slot.isIgnored()).Visit(const_cast<Expr*>(E));
1534 LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) {
1535 assert(hasAggregateEvaluationKind(E->getType()) && "Invalid argument!");
1536 Address Temp = CreateMemTemp(E->getType());
1537 LValue LV = MakeAddrLValue(Temp, E->getType());
1538 EmitAggExpr(E, AggValueSlot::forLValue(LV, AggValueSlot::IsNotDestructed,
1539 AggValueSlot::DoesNotNeedGCBarriers,
1540 AggValueSlot::IsNotAliased));
1544 void CodeGenFunction::EmitAggregateCopy(Address DestPtr,
1545 Address SrcPtr, QualType Ty,
1547 bool isAssignment) {
1548 assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
1550 if (getLangOpts().CPlusPlus) {
1551 if (const RecordType *RT = Ty->getAs<RecordType>()) {
1552 CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl());
1553 assert((Record->hasTrivialCopyConstructor() ||
1554 Record->hasTrivialCopyAssignment() ||
1555 Record->hasTrivialMoveConstructor() ||
1556 Record->hasTrivialMoveAssignment() ||
1557 Record->isUnion()) &&
1558 "Trying to aggregate-copy a type without a trivial copy/move "
1559 "constructor or assignment operator");
1560 // Ignore empty classes in C++.
1561 if (Record->isEmpty())
1566 // Aggregate assignment turns into llvm.memcpy. This is almost valid per
1567 // C99 6.5.16.1p3, which states "If the value being stored in an object is
1568 // read from another object that overlaps in anyway the storage of the first
1569 // object, then the overlap shall be exact and the two objects shall have
1570 // qualified or unqualified versions of a compatible type."
1572 // memcpy is not defined if the source and destination pointers are exactly
1573 // equal, but other compilers do this optimization, and almost every memcpy
1574 // implementation handles this case safely. If there is a libc that does not
1575 // safely handle this, we can add a target hook.
1577 // Get data size info for this aggregate. If this is an assignment,
1578 // don't copy the tail padding, because we might be assigning into a
1579 // base subobject where the tail padding is claimed. Otherwise,
1580 // copying it is fine.
1581 std::pair<CharUnits, CharUnits> TypeInfo;
1583 TypeInfo = getContext().getTypeInfoDataSizeInChars(Ty);
1585 TypeInfo = getContext().getTypeInfoInChars(Ty);
1587 llvm::Value *SizeVal = nullptr;
1588 if (TypeInfo.first.isZero()) {
1589 // But note that getTypeInfo returns 0 for a VLA.
1590 if (auto *VAT = dyn_cast_or_null<VariableArrayType>(
1591 getContext().getAsArrayType(Ty))) {
1593 SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
1594 TypeInfo = getContext().getTypeInfoDataSizeInChars(BaseEltTy);
1595 std::pair<CharUnits, CharUnits> LastElementTypeInfo;
1597 LastElementTypeInfo = getContext().getTypeInfoInChars(BaseEltTy);
1598 assert(!TypeInfo.first.isZero());
1599 SizeVal = Builder.CreateNUWMul(
1601 llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity()));
1602 if (!isAssignment) {
1603 SizeVal = Builder.CreateNUWSub(
1605 llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity()));
1606 SizeVal = Builder.CreateNUWAdd(
1607 SizeVal, llvm::ConstantInt::get(
1608 SizeTy, LastElementTypeInfo.first.getQuantity()));
1613 SizeVal = llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity());
1616 // FIXME: If we have a volatile struct, the optimizer can remove what might
1617 // appear to be `extra' memory ops:
1619 // volatile struct { int i; } a, b;
1626 // we need to use a different call here. We use isVolatile to indicate when
1627 // either the source or the destination is volatile.
1629 DestPtr = Builder.CreateElementBitCast(DestPtr, Int8Ty);
1630 SrcPtr = Builder.CreateElementBitCast(SrcPtr, Int8Ty);
1632 // Don't do any of the memmove_collectable tests if GC isn't set.
1633 if (CGM.getLangOpts().getGC() == LangOptions::NonGC) {
1635 } else if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
1636 RecordDecl *Record = RecordTy->getDecl();
1637 if (Record->hasObjectMember()) {
1638 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1642 } else if (Ty->isArrayType()) {
1643 QualType BaseType = getContext().getBaseElementType(Ty);
1644 if (const RecordType *RecordTy = BaseType->getAs<RecordType>()) {
1645 if (RecordTy->getDecl()->hasObjectMember()) {
1646 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1653 auto Inst = Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, isVolatile);
1655 // Determine the metadata to describe the position of any padding in this
1656 // memcpy, as well as the TBAA tags for the members of the struct, in case
1657 // the optimizer wishes to expand it in to scalar memory operations.
1658 if (llvm::MDNode *TBAAStructTag = CGM.getTBAAStructInfo(Ty))
1659 Inst->setMetadata(llvm::LLVMContext::MD_tbaa_struct, TBAAStructTag);