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 VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); }
115 void VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) {
116 return Visit(E->getReplacement());
120 void VisitDeclRefExpr(DeclRefExpr *E) {
121 // For aggregates, we should always be able to emit the variable
122 // as an l-value unless it's a reference. This is due to the fact
123 // that we can't actually ever see a normal l2r conversion on an
124 // aggregate in C++, and in C there's no language standard
125 // actively preventing us from listing variables in the captures
127 if (E->getDecl()->getType()->isReferenceType()) {
128 if (CodeGenFunction::ConstantEmission result
129 = CGF.tryEmitAsConstant(E)) {
130 EmitFinalDestCopy(E->getType(), result.getReferenceLValue(CGF, E));
135 EmitAggLoadOfLValue(E);
138 void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
139 void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
140 void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
141 void VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
142 void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
143 EmitAggLoadOfLValue(E);
145 void VisitPredefinedExpr(const PredefinedExpr *E) {
146 EmitAggLoadOfLValue(E);
150 void VisitCastExpr(CastExpr *E);
151 void VisitCallExpr(const CallExpr *E);
152 void VisitStmtExpr(const StmtExpr *E);
153 void VisitBinaryOperator(const BinaryOperator *BO);
154 void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO);
155 void VisitBinAssign(const BinaryOperator *E);
156 void VisitBinComma(const BinaryOperator *E);
158 void VisitObjCMessageExpr(ObjCMessageExpr *E);
159 void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
160 EmitAggLoadOfLValue(E);
163 void VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E);
164 void VisitAbstractConditionalOperator(const AbstractConditionalOperator *CO);
165 void VisitChooseExpr(const ChooseExpr *CE);
166 void VisitInitListExpr(InitListExpr *E);
167 void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E);
168 void VisitNoInitExpr(NoInitExpr *E) { } // Do nothing.
169 void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
170 Visit(DAE->getExpr());
172 void VisitCXXDefaultInitExpr(CXXDefaultInitExpr *DIE) {
173 CodeGenFunction::CXXDefaultInitExprScope Scope(CGF);
174 Visit(DIE->getExpr());
176 void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
177 void VisitCXXConstructExpr(const CXXConstructExpr *E);
178 void VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E);
179 void VisitLambdaExpr(LambdaExpr *E);
180 void VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E);
181 void VisitExprWithCleanups(ExprWithCleanups *E);
182 void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E);
183 void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
184 void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E);
185 void VisitOpaqueValueExpr(OpaqueValueExpr *E);
187 void VisitPseudoObjectExpr(PseudoObjectExpr *E) {
188 if (E->isGLValue()) {
189 LValue LV = CGF.EmitPseudoObjectLValue(E);
190 return EmitFinalDestCopy(E->getType(), LV);
193 CGF.EmitPseudoObjectRValue(E, EnsureSlot(E->getType()));
196 void VisitVAArgExpr(VAArgExpr *E);
198 void EmitInitializationToLValue(Expr *E, LValue Address);
199 void EmitNullInitializationToLValue(LValue Address);
200 // case Expr::ChooseExprClass:
201 void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); }
202 void VisitAtomicExpr(AtomicExpr *E) {
203 RValue Res = CGF.EmitAtomicExpr(E);
204 EmitFinalDestCopy(E->getType(), Res);
207 } // end anonymous namespace.
209 //===----------------------------------------------------------------------===//
211 //===----------------------------------------------------------------------===//
213 /// EmitAggLoadOfLValue - Given an expression with aggregate type that
214 /// represents a value lvalue, this method emits the address of the lvalue,
215 /// then loads the result into DestPtr.
216 void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
217 LValue LV = CGF.EmitLValue(E);
219 // If the type of the l-value is atomic, then do an atomic load.
220 if (LV.getType()->isAtomicType() || CGF.LValueIsSuitableForInlineAtomic(LV)) {
221 CGF.EmitAtomicLoad(LV, E->getExprLoc(), Dest);
225 EmitFinalDestCopy(E->getType(), LV);
228 /// \brief True if the given aggregate type requires special GC API calls.
229 bool AggExprEmitter::TypeRequiresGCollection(QualType T) {
230 // Only record types have members that might require garbage collection.
231 const RecordType *RecordTy = T->getAs<RecordType>();
232 if (!RecordTy) return false;
234 // Don't mess with non-trivial C++ types.
235 RecordDecl *Record = RecordTy->getDecl();
236 if (isa<CXXRecordDecl>(Record) &&
237 (cast<CXXRecordDecl>(Record)->hasNonTrivialCopyConstructor() ||
238 !cast<CXXRecordDecl>(Record)->hasTrivialDestructor()))
241 // Check whether the type has an object member.
242 return Record->hasObjectMember();
245 /// \brief Perform the final move to DestPtr if for some reason
246 /// getReturnValueSlot() didn't use it directly.
248 /// The idea is that you do something like this:
249 /// RValue Result = EmitSomething(..., getReturnValueSlot());
250 /// EmitMoveFromReturnSlot(E, Result);
252 /// If nothing interferes, this will cause the result to be emitted
253 /// directly into the return value slot. Otherwise, a final move
254 /// will be performed.
255 void AggExprEmitter::EmitMoveFromReturnSlot(const Expr *E, RValue src) {
256 if (shouldUseDestForReturnSlot()) {
257 // Logically, Dest.getAddr() should equal Src.getAggregateAddr().
258 // The possibility of undef rvalues complicates that a lot,
259 // though, so we can't really assert.
263 // Otherwise, copy from there to the destination.
264 assert(Dest.getPointer() != src.getAggregatePointer());
265 EmitFinalDestCopy(E->getType(), src);
268 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
269 void AggExprEmitter::EmitFinalDestCopy(QualType type, RValue src) {
270 assert(src.isAggregate() && "value must be aggregate value!");
271 LValue srcLV = CGF.MakeAddrLValue(src.getAggregateAddress(), type);
272 EmitFinalDestCopy(type, srcLV);
275 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
276 void AggExprEmitter::EmitFinalDestCopy(QualType type, const LValue &src) {
277 // If Dest is ignored, then we're evaluating an aggregate expression
278 // in a context that doesn't care about the result. Note that loads
279 // from volatile l-values force the existence of a non-ignored
281 if (Dest.isIgnored())
284 AggValueSlot srcAgg =
285 AggValueSlot::forLValue(src, AggValueSlot::IsDestructed,
286 needsGC(type), AggValueSlot::IsAliased);
287 EmitCopy(type, Dest, srcAgg);
290 /// Perform a copy from the source into the destination.
292 /// \param type - the type of the aggregate being copied; qualifiers are
294 void AggExprEmitter::EmitCopy(QualType type, const AggValueSlot &dest,
295 const AggValueSlot &src) {
296 if (dest.requiresGCollection()) {
297 CharUnits sz = CGF.getContext().getTypeSizeInChars(type);
298 llvm::Value *size = llvm::ConstantInt::get(CGF.SizeTy, sz.getQuantity());
299 CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
306 // If the result of the assignment is used, copy the LHS there also.
307 // It's volatile if either side is. Use the minimum alignment of
309 CGF.EmitAggregateCopy(dest.getAddress(), src.getAddress(), type,
310 dest.isVolatile() || src.isVolatile());
313 /// \brief Emit the initializer for a std::initializer_list initialized with a
314 /// real initializer list.
316 AggExprEmitter::VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E) {
317 // Emit an array containing the elements. The array is externally destructed
318 // if the std::initializer_list object is.
319 ASTContext &Ctx = CGF.getContext();
320 LValue Array = CGF.EmitLValue(E->getSubExpr());
321 assert(Array.isSimple() && "initializer_list array not a simple lvalue");
322 Address ArrayPtr = Array.getAddress();
324 const ConstantArrayType *ArrayType =
325 Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
326 assert(ArrayType && "std::initializer_list constructed from non-array");
328 // FIXME: Perform the checks on the field types in SemaInit.
329 RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
330 RecordDecl::field_iterator Field = Record->field_begin();
331 if (Field == Record->field_end()) {
332 CGF.ErrorUnsupported(E, "weird std::initializer_list");
337 if (!Field->getType()->isPointerType() ||
338 !Ctx.hasSameType(Field->getType()->getPointeeType(),
339 ArrayType->getElementType())) {
340 CGF.ErrorUnsupported(E, "weird std::initializer_list");
344 AggValueSlot Dest = EnsureSlot(E->getType());
345 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
346 LValue Start = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
347 llvm::Value *Zero = llvm::ConstantInt::get(CGF.PtrDiffTy, 0);
348 llvm::Value *IdxStart[] = { Zero, Zero };
349 llvm::Value *ArrayStart =
350 Builder.CreateInBoundsGEP(ArrayPtr.getPointer(), IdxStart, "arraystart");
351 CGF.EmitStoreThroughLValue(RValue::get(ArrayStart), Start);
354 if (Field == Record->field_end()) {
355 CGF.ErrorUnsupported(E, "weird std::initializer_list");
359 llvm::Value *Size = Builder.getInt(ArrayType->getSize());
360 LValue EndOrLength = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
361 if (Field->getType()->isPointerType() &&
362 Ctx.hasSameType(Field->getType()->getPointeeType(),
363 ArrayType->getElementType())) {
365 llvm::Value *IdxEnd[] = { Zero, Size };
366 llvm::Value *ArrayEnd =
367 Builder.CreateInBoundsGEP(ArrayPtr.getPointer(), IdxEnd, "arrayend");
368 CGF.EmitStoreThroughLValue(RValue::get(ArrayEnd), EndOrLength);
369 } else if (Ctx.hasSameType(Field->getType(), Ctx.getSizeType())) {
371 CGF.EmitStoreThroughLValue(RValue::get(Size), EndOrLength);
373 CGF.ErrorUnsupported(E, "weird std::initializer_list");
378 /// \brief Determine if E is a trivial array filler, that is, one that is
379 /// equivalent to zero-initialization.
380 static bool isTrivialFiller(Expr *E) {
384 if (isa<ImplicitValueInitExpr>(E))
387 if (auto *ILE = dyn_cast<InitListExpr>(E)) {
388 if (ILE->getNumInits())
390 return isTrivialFiller(ILE->getArrayFiller());
393 if (auto *Cons = dyn_cast_or_null<CXXConstructExpr>(E))
394 return Cons->getConstructor()->isDefaultConstructor() &&
395 Cons->getConstructor()->isTrivial();
397 // FIXME: Are there other cases where we can avoid emitting an initializer?
401 /// \brief Emit initialization of an array from an initializer list.
402 void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
403 QualType elementType, InitListExpr *E) {
404 uint64_t NumInitElements = E->getNumInits();
406 uint64_t NumArrayElements = AType->getNumElements();
407 assert(NumInitElements <= NumArrayElements);
409 // DestPtr is an array*. Construct an elementType* by drilling
411 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
412 llvm::Value *indices[] = { zero, zero };
414 Builder.CreateInBoundsGEP(DestPtr.getPointer(), indices, "arrayinit.begin");
416 CharUnits elementSize = CGF.getContext().getTypeSizeInChars(elementType);
417 CharUnits elementAlign =
418 DestPtr.getAlignment().alignmentOfArrayElement(elementSize);
420 // Exception safety requires us to destroy all the
421 // already-constructed members if an initializer throws.
422 // For that, we'll need an EH cleanup.
423 QualType::DestructionKind dtorKind = elementType.isDestructedType();
424 Address endOfInit = Address::invalid();
425 EHScopeStack::stable_iterator cleanup;
426 llvm::Instruction *cleanupDominator = nullptr;
427 if (CGF.needsEHCleanup(dtorKind)) {
428 // In principle we could tell the cleanup where we are more
429 // directly, but the control flow can get so varied here that it
430 // would actually be quite complex. Therefore we go through an
432 endOfInit = CGF.CreateTempAlloca(begin->getType(), CGF.getPointerAlign(),
433 "arrayinit.endOfInit");
434 cleanupDominator = Builder.CreateStore(begin, endOfInit);
435 CGF.pushIrregularPartialArrayCleanup(begin, endOfInit, elementType,
437 CGF.getDestroyer(dtorKind));
438 cleanup = CGF.EHStack.stable_begin();
440 // Otherwise, remember that we didn't need a cleanup.
442 dtorKind = QualType::DK_none;
445 llvm::Value *one = llvm::ConstantInt::get(CGF.SizeTy, 1);
447 // The 'current element to initialize'. The invariants on this
448 // variable are complicated. Essentially, after each iteration of
449 // the loop, it points to the last initialized element, except
450 // that it points to the beginning of the array before any
451 // elements have been initialized.
452 llvm::Value *element = begin;
454 // Emit the explicit initializers.
455 for (uint64_t i = 0; i != NumInitElements; ++i) {
456 // Advance to the next element.
458 element = Builder.CreateInBoundsGEP(element, one, "arrayinit.element");
460 // Tell the cleanup that it needs to destroy up to this
461 // element. TODO: some of these stores can be trivially
462 // observed to be unnecessary.
463 if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit);
467 CGF.MakeAddrLValue(Address(element, elementAlign), elementType);
468 EmitInitializationToLValue(E->getInit(i), elementLV);
471 // Check whether there's a non-trivial array-fill expression.
472 Expr *filler = E->getArrayFiller();
473 bool hasTrivialFiller = isTrivialFiller(filler);
475 // Any remaining elements need to be zero-initialized, possibly
476 // using the filler expression. We can skip this if the we're
477 // emitting to zeroed memory.
478 if (NumInitElements != NumArrayElements &&
479 !(Dest.isZeroed() && hasTrivialFiller &&
480 CGF.getTypes().isZeroInitializable(elementType))) {
482 // Use an actual loop. This is basically
483 // do { *array++ = filler; } while (array != end);
485 // Advance to the start of the rest of the array.
486 if (NumInitElements) {
487 element = Builder.CreateInBoundsGEP(element, one, "arrayinit.start");
488 if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit);
491 // Compute the end of the array.
492 llvm::Value *end = Builder.CreateInBoundsGEP(begin,
493 llvm::ConstantInt::get(CGF.SizeTy, NumArrayElements),
496 llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
497 llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body");
499 // Jump into the body.
500 CGF.EmitBlock(bodyBB);
501 llvm::PHINode *currentElement =
502 Builder.CreatePHI(element->getType(), 2, "arrayinit.cur");
503 currentElement->addIncoming(element, entryBB);
505 // Emit the actual filler expression.
507 CGF.MakeAddrLValue(Address(currentElement, elementAlign), elementType);
509 EmitInitializationToLValue(filler, elementLV);
511 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_AddressSpaceConversion:
753 llvm_unreachable("cast kind invalid for aggregate types");
757 void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
758 if (E->getCallReturnType(CGF.getContext())->isReferenceType()) {
759 EmitAggLoadOfLValue(E);
763 RValue RV = CGF.EmitCallExpr(E, getReturnValueSlot());
764 EmitMoveFromReturnSlot(E, RV);
767 void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
768 RValue RV = CGF.EmitObjCMessageExpr(E, getReturnValueSlot());
769 EmitMoveFromReturnSlot(E, RV);
772 void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
773 CGF.EmitIgnoredExpr(E->getLHS());
777 void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
778 CodeGenFunction::StmtExprEvaluation eval(CGF);
779 CGF.EmitCompoundStmt(*E->getSubStmt(), true, Dest);
782 void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
783 if (E->getOpcode() == BO_PtrMemD || E->getOpcode() == BO_PtrMemI)
784 VisitPointerToDataMemberBinaryOperator(E);
786 CGF.ErrorUnsupported(E, "aggregate binary expression");
789 void AggExprEmitter::VisitPointerToDataMemberBinaryOperator(
790 const BinaryOperator *E) {
791 LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E);
792 EmitFinalDestCopy(E->getType(), LV);
795 /// Is the value of the given expression possibly a reference to or
796 /// into a __block variable?
797 static bool isBlockVarRef(const Expr *E) {
798 // Make sure we look through parens.
799 E = E->IgnoreParens();
801 // Check for a direct reference to a __block variable.
802 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
803 const VarDecl *var = dyn_cast<VarDecl>(DRE->getDecl());
804 return (var && var->hasAttr<BlocksAttr>());
807 // More complicated stuff.
810 if (const BinaryOperator *op = dyn_cast<BinaryOperator>(E)) {
811 // For an assignment or pointer-to-member operation, just care
813 if (op->isAssignmentOp() || op->isPtrMemOp())
814 return isBlockVarRef(op->getLHS());
816 // For a comma, just care about the RHS.
817 if (op->getOpcode() == BO_Comma)
818 return isBlockVarRef(op->getRHS());
820 // FIXME: pointer arithmetic?
823 // Check both sides of a conditional operator.
824 } else if (const AbstractConditionalOperator *op
825 = dyn_cast<AbstractConditionalOperator>(E)) {
826 return isBlockVarRef(op->getTrueExpr())
827 || isBlockVarRef(op->getFalseExpr());
829 // OVEs are required to support BinaryConditionalOperators.
830 } else if (const OpaqueValueExpr *op
831 = dyn_cast<OpaqueValueExpr>(E)) {
832 if (const Expr *src = op->getSourceExpr())
833 return isBlockVarRef(src);
835 // Casts are necessary to get things like (*(int*)&var) = foo().
836 // We don't really care about the kind of cast here, except
837 // we don't want to look through l2r casts, because it's okay
838 // to get the *value* in a __block variable.
839 } else if (const CastExpr *cast = dyn_cast<CastExpr>(E)) {
840 if (cast->getCastKind() == CK_LValueToRValue)
842 return isBlockVarRef(cast->getSubExpr());
844 // Handle unary operators. Again, just aggressively look through
845 // it, ignoring the operation.
846 } else if (const UnaryOperator *uop = dyn_cast<UnaryOperator>(E)) {
847 return isBlockVarRef(uop->getSubExpr());
849 // Look into the base of a field access.
850 } else if (const MemberExpr *mem = dyn_cast<MemberExpr>(E)) {
851 return isBlockVarRef(mem->getBase());
853 // Look into the base of a subscript.
854 } else if (const ArraySubscriptExpr *sub = dyn_cast<ArraySubscriptExpr>(E)) {
855 return isBlockVarRef(sub->getBase());
861 void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
862 // For an assignment to work, the value on the right has
863 // to be compatible with the value on the left.
864 assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(),
865 E->getRHS()->getType())
866 && "Invalid assignment");
868 // If the LHS might be a __block variable, and the RHS can
869 // potentially cause a block copy, we need to evaluate the RHS first
870 // so that the assignment goes the right place.
871 // This is pretty semantically fragile.
872 if (isBlockVarRef(E->getLHS()) &&
873 E->getRHS()->HasSideEffects(CGF.getContext())) {
874 // Ensure that we have a destination, and evaluate the RHS into that.
875 EnsureDest(E->getRHS()->getType());
878 // Now emit the LHS and copy into it.
879 LValue LHS = CGF.EmitCheckedLValue(E->getLHS(), CodeGenFunction::TCK_Store);
881 // That copy is an atomic copy if the LHS is atomic.
882 if (LHS.getType()->isAtomicType() ||
883 CGF.LValueIsSuitableForInlineAtomic(LHS)) {
884 CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false);
888 EmitCopy(E->getLHS()->getType(),
889 AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
890 needsGC(E->getLHS()->getType()),
891 AggValueSlot::IsAliased),
896 LValue LHS = CGF.EmitLValue(E->getLHS());
898 // If we have an atomic type, evaluate into the destination and then
899 // do an atomic copy.
900 if (LHS.getType()->isAtomicType() ||
901 CGF.LValueIsSuitableForInlineAtomic(LHS)) {
902 EnsureDest(E->getRHS()->getType());
904 CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false);
908 // Codegen the RHS so that it stores directly into the LHS.
909 AggValueSlot LHSSlot =
910 AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
911 needsGC(E->getLHS()->getType()),
912 AggValueSlot::IsAliased);
913 // A non-volatile aggregate destination might have volatile member.
914 if (!LHSSlot.isVolatile() &&
915 CGF.hasVolatileMember(E->getLHS()->getType()))
916 LHSSlot.setVolatile(true);
918 CGF.EmitAggExpr(E->getRHS(), LHSSlot);
920 // Copy into the destination if the assignment isn't ignored.
921 EmitFinalDestCopy(E->getType(), LHS);
924 void AggExprEmitter::
925 VisitAbstractConditionalOperator(const AbstractConditionalOperator *E) {
926 llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
927 llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
928 llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
930 // Bind the common expression if necessary.
931 CodeGenFunction::OpaqueValueMapping binding(CGF, E);
933 CodeGenFunction::ConditionalEvaluation eval(CGF);
934 CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock,
935 CGF.getProfileCount(E));
937 // Save whether the destination's lifetime is externally managed.
938 bool isExternallyDestructed = Dest.isExternallyDestructed();
941 CGF.EmitBlock(LHSBlock);
942 CGF.incrementProfileCounter(E);
943 Visit(E->getTrueExpr());
946 assert(CGF.HaveInsertPoint() && "expression evaluation ended with no IP!");
947 CGF.Builder.CreateBr(ContBlock);
949 // If the result of an agg expression is unused, then the emission
950 // of the LHS might need to create a destination slot. That's fine
951 // with us, and we can safely emit the RHS into the same slot, but
952 // we shouldn't claim that it's already being destructed.
953 Dest.setExternallyDestructed(isExternallyDestructed);
956 CGF.EmitBlock(RHSBlock);
957 Visit(E->getFalseExpr());
960 CGF.EmitBlock(ContBlock);
963 void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
964 Visit(CE->getChosenSubExpr());
967 void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
968 Address ArgValue = Address::invalid();
969 Address ArgPtr = CGF.EmitVAArg(VE, ArgValue);
971 // If EmitVAArg fails, emit an error.
972 if (!ArgPtr.isValid()) {
973 CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
977 EmitFinalDestCopy(VE->getType(), CGF.MakeAddrLValue(ArgPtr, VE->getType()));
980 void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
981 // Ensure that we have a slot, but if we already do, remember
982 // whether it was externally destructed.
983 bool wasExternallyDestructed = Dest.isExternallyDestructed();
984 EnsureDest(E->getType());
986 // We're going to push a destructor if there isn't already one.
987 Dest.setExternallyDestructed();
989 Visit(E->getSubExpr());
991 // Push that destructor we promised.
992 if (!wasExternallyDestructed)
993 CGF.EmitCXXTemporary(E->getTemporary(), E->getType(), Dest.getAddress());
997 AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
998 AggValueSlot Slot = EnsureSlot(E->getType());
999 CGF.EmitCXXConstructExpr(E, Slot);
1002 void AggExprEmitter::VisitCXXInheritedCtorInitExpr(
1003 const CXXInheritedCtorInitExpr *E) {
1004 AggValueSlot Slot = EnsureSlot(E->getType());
1005 CGF.EmitInheritedCXXConstructorCall(
1006 E->getConstructor(), E->constructsVBase(), Slot.getAddress(),
1007 E->inheritedFromVBase(), E);
1011 AggExprEmitter::VisitLambdaExpr(LambdaExpr *E) {
1012 AggValueSlot Slot = EnsureSlot(E->getType());
1013 CGF.EmitLambdaExpr(E, Slot);
1016 void AggExprEmitter::VisitExprWithCleanups(ExprWithCleanups *E) {
1017 CGF.enterFullExpression(E);
1018 CodeGenFunction::RunCleanupsScope cleanups(CGF);
1019 Visit(E->getSubExpr());
1022 void AggExprEmitter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) {
1023 QualType T = E->getType();
1024 AggValueSlot Slot = EnsureSlot(T);
1025 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddress(), T));
1028 void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
1029 QualType T = E->getType();
1030 AggValueSlot Slot = EnsureSlot(T);
1031 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddress(), T));
1034 /// isSimpleZero - If emitting this value will obviously just cause a store of
1035 /// zero to memory, return true. This can return false if uncertain, so it just
1036 /// handles simple cases.
1037 static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) {
1038 E = E->IgnoreParens();
1041 if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E))
1042 return IL->getValue() == 0;
1044 if (const FloatingLiteral *FL = dyn_cast<FloatingLiteral>(E))
1045 return FL->getValue().isPosZero();
1047 if ((isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) &&
1048 CGF.getTypes().isZeroInitializable(E->getType()))
1050 // (int*)0 - Null pointer expressions.
1051 if (const CastExpr *ICE = dyn_cast<CastExpr>(E))
1052 return ICE->getCastKind() == CK_NullToPointer;
1054 if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E))
1055 return CL->getValue() == 0;
1057 // Otherwise, hard case: conservatively return false.
1063 AggExprEmitter::EmitInitializationToLValue(Expr *E, LValue LV) {
1064 QualType type = LV.getType();
1065 // FIXME: Ignore result?
1066 // FIXME: Are initializers affected by volatile?
1067 if (Dest.isZeroed() && isSimpleZero(E, CGF)) {
1068 // Storing "i32 0" to a zero'd memory location is a noop.
1070 } else if (isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) {
1071 return EmitNullInitializationToLValue(LV);
1072 } else if (isa<NoInitExpr>(E)) {
1075 } else if (type->isReferenceType()) {
1076 RValue RV = CGF.EmitReferenceBindingToExpr(E);
1077 return CGF.EmitStoreThroughLValue(RV, LV);
1080 switch (CGF.getEvaluationKind(type)) {
1082 CGF.EmitComplexExprIntoLValue(E, LV, /*isInit*/ true);
1085 CGF.EmitAggExpr(E, AggValueSlot::forLValue(LV,
1086 AggValueSlot::IsDestructed,
1087 AggValueSlot::DoesNotNeedGCBarriers,
1088 AggValueSlot::IsNotAliased,
1092 if (LV.isSimple()) {
1093 CGF.EmitScalarInit(E, /*D=*/nullptr, LV, /*Captured=*/false);
1095 CGF.EmitStoreThroughLValue(RValue::get(CGF.EmitScalarExpr(E)), LV);
1099 llvm_unreachable("bad evaluation kind");
1102 void AggExprEmitter::EmitNullInitializationToLValue(LValue lv) {
1103 QualType type = lv.getType();
1105 // If the destination slot is already zeroed out before the aggregate is
1106 // copied into it, we don't have to emit any zeros here.
1107 if (Dest.isZeroed() && CGF.getTypes().isZeroInitializable(type))
1110 if (CGF.hasScalarEvaluationKind(type)) {
1111 // For non-aggregates, we can store the appropriate null constant.
1112 llvm::Value *null = CGF.CGM.EmitNullConstant(type);
1113 // Note that the following is not equivalent to
1114 // EmitStoreThroughBitfieldLValue for ARC types.
1115 if (lv.isBitField()) {
1116 CGF.EmitStoreThroughBitfieldLValue(RValue::get(null), lv);
1118 assert(lv.isSimple());
1119 CGF.EmitStoreOfScalar(null, lv, /* isInitialization */ true);
1122 // There's a potential optimization opportunity in combining
1123 // memsets; that would be easy for arrays, but relatively
1124 // difficult for structures with the current code.
1125 CGF.EmitNullInitialization(lv.getAddress(), lv.getType());
1129 void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
1131 // FIXME: Assess perf here? Figure out what cases are worth optimizing here
1132 // (Length of globals? Chunks of zeroed-out space?).
1134 // If we can, prefer a copy from a global; this is a lot less code for long
1135 // globals, and it's easier for the current optimizers to analyze.
1136 if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
1137 llvm::GlobalVariable* GV =
1138 new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
1139 llvm::GlobalValue::InternalLinkage, C, "");
1140 EmitFinalDestCopy(E->getType(), CGF.MakeAddrLValue(GV, E->getType()));
1144 if (E->hadArrayRangeDesignator())
1145 CGF.ErrorUnsupported(E, "GNU array range designator extension");
1147 AggValueSlot Dest = EnsureSlot(E->getType());
1149 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
1151 // Handle initialization of an array.
1152 if (E->getType()->isArrayType()) {
1153 if (E->isStringLiteralInit())
1154 return Visit(E->getInit(0));
1156 QualType elementType =
1157 CGF.getContext().getAsArrayType(E->getType())->getElementType();
1159 auto AType = cast<llvm::ArrayType>(Dest.getAddress().getElementType());
1160 EmitArrayInit(Dest.getAddress(), AType, elementType, E);
1164 if (E->getType()->isAtomicType()) {
1165 // An _Atomic(T) object can be list-initialized from an expression
1166 // of the same type.
1167 assert(E->getNumInits() == 1 &&
1168 CGF.getContext().hasSameUnqualifiedType(E->getInit(0)->getType(),
1170 "unexpected list initialization for atomic object");
1171 return Visit(E->getInit(0));
1174 assert(E->getType()->isRecordType() && "Only support structs/unions here!");
1176 // Do struct initialization; this code just sets each individual member
1177 // to the approprate value. This makes bitfield support automatic;
1178 // the disadvantage is that the generated code is more difficult for
1179 // the optimizer, especially with bitfields.
1180 unsigned NumInitElements = E->getNumInits();
1181 RecordDecl *record = E->getType()->castAs<RecordType>()->getDecl();
1183 // We'll need to enter cleanup scopes in case any of the element
1184 // initializers throws an exception.
1185 SmallVector<EHScopeStack::stable_iterator, 16> cleanups;
1186 llvm::Instruction *cleanupDominator = nullptr;
1188 unsigned curInitIndex = 0;
1190 // Emit initialization of base classes.
1191 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(record)) {
1192 assert(E->getNumInits() >= CXXRD->getNumBases() &&
1193 "missing initializer for base class");
1194 for (auto &Base : CXXRD->bases()) {
1195 assert(!Base.isVirtual() && "should not see vbases here");
1196 auto *BaseRD = Base.getType()->getAsCXXRecordDecl();
1197 Address V = CGF.GetAddressOfDirectBaseInCompleteClass(
1198 Dest.getAddress(), CXXRD, BaseRD,
1199 /*isBaseVirtual*/ false);
1200 AggValueSlot AggSlot =
1201 AggValueSlot::forAddr(V, Qualifiers(),
1202 AggValueSlot::IsDestructed,
1203 AggValueSlot::DoesNotNeedGCBarriers,
1204 AggValueSlot::IsNotAliased);
1205 CGF.EmitAggExpr(E->getInit(curInitIndex++), AggSlot);
1207 if (QualType::DestructionKind dtorKind =
1208 Base.getType().isDestructedType()) {
1209 CGF.pushDestroy(dtorKind, V, Base.getType());
1210 cleanups.push_back(CGF.EHStack.stable_begin());
1215 // Prepare a 'this' for CXXDefaultInitExprs.
1216 CodeGenFunction::FieldConstructionScope FCS(CGF, Dest.getAddress());
1218 if (record->isUnion()) {
1219 // Only initialize one field of a union. The field itself is
1220 // specified by the initializer list.
1221 if (!E->getInitializedFieldInUnion()) {
1222 // Empty union; we have nothing to do.
1225 // Make sure that it's really an empty and not a failure of
1226 // semantic analysis.
1227 for (const auto *Field : record->fields())
1228 assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
1233 // FIXME: volatility
1234 FieldDecl *Field = E->getInitializedFieldInUnion();
1236 LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestLV, Field);
1237 if (NumInitElements) {
1238 // Store the initializer into the field
1239 EmitInitializationToLValue(E->getInit(0), FieldLoc);
1241 // Default-initialize to null.
1242 EmitNullInitializationToLValue(FieldLoc);
1248 // Here we iterate over the fields; this makes it simpler to both
1249 // default-initialize fields and skip over unnamed fields.
1250 for (const auto *field : record->fields()) {
1251 // We're done once we hit the flexible array member.
1252 if (field->getType()->isIncompleteArrayType())
1255 // Always skip anonymous bitfields.
1256 if (field->isUnnamedBitfield())
1259 // We're done if we reach the end of the explicit initializers, we
1260 // have a zeroed object, and the rest of the fields are
1261 // zero-initializable.
1262 if (curInitIndex == NumInitElements && Dest.isZeroed() &&
1263 CGF.getTypes().isZeroInitializable(E->getType()))
1267 LValue LV = CGF.EmitLValueForFieldInitialization(DestLV, field);
1268 // We never generate write-barries for initialized fields.
1271 if (curInitIndex < NumInitElements) {
1272 // Store the initializer into the field.
1273 EmitInitializationToLValue(E->getInit(curInitIndex++), LV);
1275 // We're out of initalizers; default-initialize to null
1276 EmitNullInitializationToLValue(LV);
1279 // Push a destructor if necessary.
1280 // FIXME: if we have an array of structures, all explicitly
1281 // initialized, we can end up pushing a linear number of cleanups.
1282 bool pushedCleanup = false;
1283 if (QualType::DestructionKind dtorKind
1284 = field->getType().isDestructedType()) {
1285 assert(LV.isSimple());
1286 if (CGF.needsEHCleanup(dtorKind)) {
1287 if (!cleanupDominator)
1288 cleanupDominator = CGF.Builder.CreateAlignedLoad(
1290 llvm::Constant::getNullValue(CGF.Int8PtrTy),
1291 CharUnits::One()); // placeholder
1293 CGF.pushDestroy(EHCleanup, LV.getAddress(), field->getType(),
1294 CGF.getDestroyer(dtorKind), false);
1295 cleanups.push_back(CGF.EHStack.stable_begin());
1296 pushedCleanup = true;
1300 // If the GEP didn't get used because of a dead zero init or something
1301 // else, clean it up for -O0 builds and general tidiness.
1302 if (!pushedCleanup && LV.isSimple())
1303 if (llvm::GetElementPtrInst *GEP =
1304 dyn_cast<llvm::GetElementPtrInst>(LV.getPointer()))
1305 if (GEP->use_empty())
1306 GEP->eraseFromParent();
1309 // Deactivate all the partial cleanups in reverse order, which
1310 // generally means popping them.
1311 for (unsigned i = cleanups.size(); i != 0; --i)
1312 CGF.DeactivateCleanupBlock(cleanups[i-1], cleanupDominator);
1314 // Destroy the placeholder if we made one.
1315 if (cleanupDominator)
1316 cleanupDominator->eraseFromParent();
1319 void AggExprEmitter::VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E) {
1320 AggValueSlot Dest = EnsureSlot(E->getType());
1322 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
1323 EmitInitializationToLValue(E->getBase(), DestLV);
1324 VisitInitListExpr(E->getUpdater());
1327 //===----------------------------------------------------------------------===//
1328 // Entry Points into this File
1329 //===----------------------------------------------------------------------===//
1331 /// GetNumNonZeroBytesInInit - Get an approximate count of the number of
1332 /// non-zero bytes that will be stored when outputting the initializer for the
1333 /// specified initializer expression.
1334 static CharUnits GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) {
1335 E = E->IgnoreParens();
1337 // 0 and 0.0 won't require any non-zero stores!
1338 if (isSimpleZero(E, CGF)) return CharUnits::Zero();
1340 // If this is an initlist expr, sum up the size of sizes of the (present)
1341 // elements. If this is something weird, assume the whole thing is non-zero.
1342 const InitListExpr *ILE = dyn_cast<InitListExpr>(E);
1343 if (!ILE || !CGF.getTypes().isZeroInitializable(ILE->getType()))
1344 return CGF.getContext().getTypeSizeInChars(E->getType());
1346 // InitListExprs for structs have to be handled carefully. If there are
1347 // reference members, we need to consider the size of the reference, not the
1348 // referencee. InitListExprs for unions and arrays can't have references.
1349 if (const RecordType *RT = E->getType()->getAs<RecordType>()) {
1350 if (!RT->isUnionType()) {
1351 RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
1352 CharUnits NumNonZeroBytes = CharUnits::Zero();
1354 unsigned ILEElement = 0;
1355 if (auto *CXXRD = dyn_cast<CXXRecordDecl>(SD))
1356 while (ILEElement != CXXRD->getNumBases())
1358 GetNumNonZeroBytesInInit(ILE->getInit(ILEElement++), CGF);
1359 for (const auto *Field : SD->fields()) {
1360 // We're done once we hit the flexible array member or run out of
1361 // InitListExpr elements.
1362 if (Field->getType()->isIncompleteArrayType() ||
1363 ILEElement == ILE->getNumInits())
1365 if (Field->isUnnamedBitfield())
1368 const Expr *E = ILE->getInit(ILEElement++);
1370 // Reference values are always non-null and have the width of a pointer.
1371 if (Field->getType()->isReferenceType())
1372 NumNonZeroBytes += CGF.getContext().toCharUnitsFromBits(
1373 CGF.getTarget().getPointerWidth(0));
1375 NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF);
1378 return NumNonZeroBytes;
1383 CharUnits NumNonZeroBytes = CharUnits::Zero();
1384 for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i)
1385 NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF);
1386 return NumNonZeroBytes;
1389 /// CheckAggExprForMemSetUse - If the initializer is large and has a lot of
1390 /// zeros in it, emit a memset and avoid storing the individual zeros.
1392 static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E,
1393 CodeGenFunction &CGF) {
1394 // If the slot is already known to be zeroed, nothing to do. Don't mess with
1396 if (Slot.isZeroed() || Slot.isVolatile() || !Slot.getAddress().isValid())
1399 // C++ objects with a user-declared constructor don't need zero'ing.
1400 if (CGF.getLangOpts().CPlusPlus)
1401 if (const RecordType *RT = CGF.getContext()
1402 .getBaseElementType(E->getType())->getAs<RecordType>()) {
1403 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1404 if (RD->hasUserDeclaredConstructor())
1408 // If the type is 16-bytes or smaller, prefer individual stores over memset.
1409 CharUnits Size = CGF.getContext().getTypeSizeInChars(E->getType());
1410 if (Size <= CharUnits::fromQuantity(16))
1413 // Check to see if over 3/4 of the initializer are known to be zero. If so,
1414 // we prefer to emit memset + individual stores for the rest.
1415 CharUnits NumNonZeroBytes = GetNumNonZeroBytesInInit(E, CGF);
1416 if (NumNonZeroBytes*4 > Size)
1419 // Okay, it seems like a good idea to use an initial memset, emit the call.
1420 llvm::Constant *SizeVal = CGF.Builder.getInt64(Size.getQuantity());
1422 Address Loc = Slot.getAddress();
1423 Loc = CGF.Builder.CreateElementBitCast(Loc, CGF.Int8Ty);
1424 CGF.Builder.CreateMemSet(Loc, CGF.Builder.getInt8(0), SizeVal, false);
1426 // Tell the AggExprEmitter that the slot is known zero.
1433 /// EmitAggExpr - Emit the computation of the specified expression of aggregate
1434 /// type. The result is computed into DestPtr. Note that if DestPtr is null,
1435 /// the value of the aggregate expression is not needed. If VolatileDest is
1436 /// true, DestPtr cannot be 0.
1437 void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot) {
1438 assert(E && hasAggregateEvaluationKind(E->getType()) &&
1439 "Invalid aggregate expression to emit");
1440 assert((Slot.getAddress().isValid() || Slot.isIgnored()) &&
1441 "slot has bits but no address");
1443 // Optimize the slot if possible.
1444 CheckAggExprForMemSetUse(Slot, E, *this);
1446 AggExprEmitter(*this, Slot, Slot.isIgnored()).Visit(const_cast<Expr*>(E));
1449 LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) {
1450 assert(hasAggregateEvaluationKind(E->getType()) && "Invalid argument!");
1451 Address Temp = CreateMemTemp(E->getType());
1452 LValue LV = MakeAddrLValue(Temp, E->getType());
1453 EmitAggExpr(E, AggValueSlot::forLValue(LV, AggValueSlot::IsNotDestructed,
1454 AggValueSlot::DoesNotNeedGCBarriers,
1455 AggValueSlot::IsNotAliased));
1459 void CodeGenFunction::EmitAggregateCopy(Address DestPtr,
1460 Address SrcPtr, QualType Ty,
1462 bool isAssignment) {
1463 assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
1465 if (getLangOpts().CPlusPlus) {
1466 if (const RecordType *RT = Ty->getAs<RecordType>()) {
1467 CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl());
1468 assert((Record->hasTrivialCopyConstructor() ||
1469 Record->hasTrivialCopyAssignment() ||
1470 Record->hasTrivialMoveConstructor() ||
1471 Record->hasTrivialMoveAssignment() ||
1472 Record->isUnion()) &&
1473 "Trying to aggregate-copy a type without a trivial copy/move "
1474 "constructor or assignment operator");
1475 // Ignore empty classes in C++.
1476 if (Record->isEmpty())
1481 // Aggregate assignment turns into llvm.memcpy. This is almost valid per
1482 // C99 6.5.16.1p3, which states "If the value being stored in an object is
1483 // read from another object that overlaps in anyway the storage of the first
1484 // object, then the overlap shall be exact and the two objects shall have
1485 // qualified or unqualified versions of a compatible type."
1487 // memcpy is not defined if the source and destination pointers are exactly
1488 // equal, but other compilers do this optimization, and almost every memcpy
1489 // implementation handles this case safely. If there is a libc that does not
1490 // safely handle this, we can add a target hook.
1492 // Get data size info for this aggregate. If this is an assignment,
1493 // don't copy the tail padding, because we might be assigning into a
1494 // base subobject where the tail padding is claimed. Otherwise,
1495 // copying it is fine.
1496 std::pair<CharUnits, CharUnits> TypeInfo;
1498 TypeInfo = getContext().getTypeInfoDataSizeInChars(Ty);
1500 TypeInfo = getContext().getTypeInfoInChars(Ty);
1502 llvm::Value *SizeVal = nullptr;
1503 if (TypeInfo.first.isZero()) {
1504 // But note that getTypeInfo returns 0 for a VLA.
1505 if (auto *VAT = dyn_cast_or_null<VariableArrayType>(
1506 getContext().getAsArrayType(Ty))) {
1508 SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
1509 TypeInfo = getContext().getTypeInfoDataSizeInChars(BaseEltTy);
1510 std::pair<CharUnits, CharUnits> LastElementTypeInfo;
1512 LastElementTypeInfo = getContext().getTypeInfoInChars(BaseEltTy);
1513 assert(!TypeInfo.first.isZero());
1514 SizeVal = Builder.CreateNUWMul(
1516 llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity()));
1517 if (!isAssignment) {
1518 SizeVal = Builder.CreateNUWSub(
1520 llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity()));
1521 SizeVal = Builder.CreateNUWAdd(
1522 SizeVal, llvm::ConstantInt::get(
1523 SizeTy, LastElementTypeInfo.first.getQuantity()));
1528 SizeVal = llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity());
1531 // FIXME: If we have a volatile struct, the optimizer can remove what might
1532 // appear to be `extra' memory ops:
1534 // volatile struct { int i; } a, b;
1541 // we need to use a different call here. We use isVolatile to indicate when
1542 // either the source or the destination is volatile.
1544 DestPtr = Builder.CreateElementBitCast(DestPtr, Int8Ty);
1545 SrcPtr = Builder.CreateElementBitCast(SrcPtr, Int8Ty);
1547 // Don't do any of the memmove_collectable tests if GC isn't set.
1548 if (CGM.getLangOpts().getGC() == LangOptions::NonGC) {
1550 } else if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
1551 RecordDecl *Record = RecordTy->getDecl();
1552 if (Record->hasObjectMember()) {
1553 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1557 } else if (Ty->isArrayType()) {
1558 QualType BaseType = getContext().getBaseElementType(Ty);
1559 if (const RecordType *RecordTy = BaseType->getAs<RecordType>()) {
1560 if (RecordTy->getDecl()->hasObjectMember()) {
1561 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1568 auto Inst = Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, isVolatile);
1570 // Determine the metadata to describe the position of any padding in this
1571 // memcpy, as well as the TBAA tags for the members of the struct, in case
1572 // the optimizer wishes to expand it in to scalar memory operations.
1573 if (llvm::MDNode *TBAAStructTag = CGM.getTBAAStructInfo(Ty))
1574 Inst->setMetadata(llvm::LLVMContext::MD_tbaa_struct, TBAAStructTag);