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 VisitLambdaExpr(LambdaExpr *E);
179 void VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E);
180 void VisitExprWithCleanups(ExprWithCleanups *E);
181 void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E);
182 void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
183 void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E);
184 void VisitOpaqueValueExpr(OpaqueValueExpr *E);
186 void VisitPseudoObjectExpr(PseudoObjectExpr *E) {
187 if (E->isGLValue()) {
188 LValue LV = CGF.EmitPseudoObjectLValue(E);
189 return EmitFinalDestCopy(E->getType(), LV);
192 CGF.EmitPseudoObjectRValue(E, EnsureSlot(E->getType()));
195 void VisitVAArgExpr(VAArgExpr *E);
197 void EmitInitializationToLValue(Expr *E, LValue Address);
198 void EmitNullInitializationToLValue(LValue Address);
199 // case Expr::ChooseExprClass:
200 void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); }
201 void VisitAtomicExpr(AtomicExpr *E) {
202 RValue Res = CGF.EmitAtomicExpr(E);
203 EmitFinalDestCopy(E->getType(), Res);
206 } // end anonymous namespace.
208 //===----------------------------------------------------------------------===//
210 //===----------------------------------------------------------------------===//
212 /// EmitAggLoadOfLValue - Given an expression with aggregate type that
213 /// represents a value lvalue, this method emits the address of the lvalue,
214 /// then loads the result into DestPtr.
215 void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
216 LValue LV = CGF.EmitLValue(E);
218 // If the type of the l-value is atomic, then do an atomic load.
219 if (LV.getType()->isAtomicType() || CGF.LValueIsSuitableForInlineAtomic(LV)) {
220 CGF.EmitAtomicLoad(LV, E->getExprLoc(), Dest);
224 EmitFinalDestCopy(E->getType(), LV);
227 /// \brief True if the given aggregate type requires special GC API calls.
228 bool AggExprEmitter::TypeRequiresGCollection(QualType T) {
229 // Only record types have members that might require garbage collection.
230 const RecordType *RecordTy = T->getAs<RecordType>();
231 if (!RecordTy) return false;
233 // Don't mess with non-trivial C++ types.
234 RecordDecl *Record = RecordTy->getDecl();
235 if (isa<CXXRecordDecl>(Record) &&
236 (cast<CXXRecordDecl>(Record)->hasNonTrivialCopyConstructor() ||
237 !cast<CXXRecordDecl>(Record)->hasTrivialDestructor()))
240 // Check whether the type has an object member.
241 return Record->hasObjectMember();
244 /// \brief Perform the final move to DestPtr if for some reason
245 /// getReturnValueSlot() didn't use it directly.
247 /// The idea is that you do something like this:
248 /// RValue Result = EmitSomething(..., getReturnValueSlot());
249 /// EmitMoveFromReturnSlot(E, Result);
251 /// If nothing interferes, this will cause the result to be emitted
252 /// directly into the return value slot. Otherwise, a final move
253 /// will be performed.
254 void AggExprEmitter::EmitMoveFromReturnSlot(const Expr *E, RValue src) {
255 if (shouldUseDestForReturnSlot()) {
256 // Logically, Dest.getAddr() should equal Src.getAggregateAddr().
257 // The possibility of undef rvalues complicates that a lot,
258 // though, so we can't really assert.
262 // Otherwise, copy from there to the destination.
263 assert(Dest.getPointer() != src.getAggregatePointer());
264 EmitFinalDestCopy(E->getType(), src);
267 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
268 void AggExprEmitter::EmitFinalDestCopy(QualType type, RValue src) {
269 assert(src.isAggregate() && "value must be aggregate value!");
270 LValue srcLV = CGF.MakeAddrLValue(src.getAggregateAddress(), type);
271 EmitFinalDestCopy(type, srcLV);
274 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
275 void AggExprEmitter::EmitFinalDestCopy(QualType type, const LValue &src) {
276 // If Dest is ignored, then we're evaluating an aggregate expression
277 // in a context that doesn't care about the result. Note that loads
278 // from volatile l-values force the existence of a non-ignored
280 if (Dest.isIgnored())
283 AggValueSlot srcAgg =
284 AggValueSlot::forLValue(src, AggValueSlot::IsDestructed,
285 needsGC(type), AggValueSlot::IsAliased);
286 EmitCopy(type, Dest, srcAgg);
289 /// Perform a copy from the source into the destination.
291 /// \param type - the type of the aggregate being copied; qualifiers are
293 void AggExprEmitter::EmitCopy(QualType type, const AggValueSlot &dest,
294 const AggValueSlot &src) {
295 if (dest.requiresGCollection()) {
296 CharUnits sz = CGF.getContext().getTypeSizeInChars(type);
297 llvm::Value *size = llvm::ConstantInt::get(CGF.SizeTy, sz.getQuantity());
298 CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
305 // If the result of the assignment is used, copy the LHS there also.
306 // It's volatile if either side is. Use the minimum alignment of
308 CGF.EmitAggregateCopy(dest.getAddress(), src.getAddress(), type,
309 dest.isVolatile() || src.isVolatile());
312 /// \brief Emit the initializer for a std::initializer_list initialized with a
313 /// real initializer list.
315 AggExprEmitter::VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E) {
316 // Emit an array containing the elements. The array is externally destructed
317 // if the std::initializer_list object is.
318 ASTContext &Ctx = CGF.getContext();
319 LValue Array = CGF.EmitLValue(E->getSubExpr());
320 assert(Array.isSimple() && "initializer_list array not a simple lvalue");
321 Address ArrayPtr = Array.getAddress();
323 const ConstantArrayType *ArrayType =
324 Ctx.getAsConstantArrayType(E->getSubExpr()->getType());
325 assert(ArrayType && "std::initializer_list constructed from non-array");
327 // FIXME: Perform the checks on the field types in SemaInit.
328 RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl();
329 RecordDecl::field_iterator Field = Record->field_begin();
330 if (Field == Record->field_end()) {
331 CGF.ErrorUnsupported(E, "weird std::initializer_list");
336 if (!Field->getType()->isPointerType() ||
337 !Ctx.hasSameType(Field->getType()->getPointeeType(),
338 ArrayType->getElementType())) {
339 CGF.ErrorUnsupported(E, "weird std::initializer_list");
343 AggValueSlot Dest = EnsureSlot(E->getType());
344 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
345 LValue Start = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
346 llvm::Value *Zero = llvm::ConstantInt::get(CGF.PtrDiffTy, 0);
347 llvm::Value *IdxStart[] = { Zero, Zero };
348 llvm::Value *ArrayStart =
349 Builder.CreateInBoundsGEP(ArrayPtr.getPointer(), IdxStart, "arraystart");
350 CGF.EmitStoreThroughLValue(RValue::get(ArrayStart), Start);
353 if (Field == Record->field_end()) {
354 CGF.ErrorUnsupported(E, "weird std::initializer_list");
358 llvm::Value *Size = Builder.getInt(ArrayType->getSize());
359 LValue EndOrLength = CGF.EmitLValueForFieldInitialization(DestLV, *Field);
360 if (Field->getType()->isPointerType() &&
361 Ctx.hasSameType(Field->getType()->getPointeeType(),
362 ArrayType->getElementType())) {
364 llvm::Value *IdxEnd[] = { Zero, Size };
365 llvm::Value *ArrayEnd =
366 Builder.CreateInBoundsGEP(ArrayPtr.getPointer(), IdxEnd, "arrayend");
367 CGF.EmitStoreThroughLValue(RValue::get(ArrayEnd), EndOrLength);
368 } else if (Ctx.hasSameType(Field->getType(), Ctx.getSizeType())) {
370 CGF.EmitStoreThroughLValue(RValue::get(Size), EndOrLength);
372 CGF.ErrorUnsupported(E, "weird std::initializer_list");
377 /// \brief Determine if E is a trivial array filler, that is, one that is
378 /// equivalent to zero-initialization.
379 static bool isTrivialFiller(Expr *E) {
383 if (isa<ImplicitValueInitExpr>(E))
386 if (auto *ILE = dyn_cast<InitListExpr>(E)) {
387 if (ILE->getNumInits())
389 return isTrivialFiller(ILE->getArrayFiller());
392 if (auto *Cons = dyn_cast_or_null<CXXConstructExpr>(E))
393 return Cons->getConstructor()->isDefaultConstructor() &&
394 Cons->getConstructor()->isTrivial();
396 // FIXME: Are there other cases where we can avoid emitting an initializer?
400 /// \brief Emit initialization of an array from an initializer list.
401 void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType,
402 QualType elementType, InitListExpr *E) {
403 uint64_t NumInitElements = E->getNumInits();
405 uint64_t NumArrayElements = AType->getNumElements();
406 assert(NumInitElements <= NumArrayElements);
408 // DestPtr is an array*. Construct an elementType* by drilling
410 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
411 llvm::Value *indices[] = { zero, zero };
413 Builder.CreateInBoundsGEP(DestPtr.getPointer(), indices, "arrayinit.begin");
415 CharUnits elementSize = CGF.getContext().getTypeSizeInChars(elementType);
416 CharUnits elementAlign =
417 DestPtr.getAlignment().alignmentOfArrayElement(elementSize);
419 // Exception safety requires us to destroy all the
420 // already-constructed members if an initializer throws.
421 // For that, we'll need an EH cleanup.
422 QualType::DestructionKind dtorKind = elementType.isDestructedType();
423 Address endOfInit = Address::invalid();
424 EHScopeStack::stable_iterator cleanup;
425 llvm::Instruction *cleanupDominator = nullptr;
426 if (CGF.needsEHCleanup(dtorKind)) {
427 // In principle we could tell the cleanup where we are more
428 // directly, but the control flow can get so varied here that it
429 // would actually be quite complex. Therefore we go through an
431 endOfInit = CGF.CreateTempAlloca(begin->getType(), CGF.getPointerAlign(),
432 "arrayinit.endOfInit");
433 cleanupDominator = Builder.CreateStore(begin, endOfInit);
434 CGF.pushIrregularPartialArrayCleanup(begin, endOfInit, elementType,
436 CGF.getDestroyer(dtorKind));
437 cleanup = CGF.EHStack.stable_begin();
439 // Otherwise, remember that we didn't need a cleanup.
441 dtorKind = QualType::DK_none;
444 llvm::Value *one = llvm::ConstantInt::get(CGF.SizeTy, 1);
446 // The 'current element to initialize'. The invariants on this
447 // variable are complicated. Essentially, after each iteration of
448 // the loop, it points to the last initialized element, except
449 // that it points to the beginning of the array before any
450 // elements have been initialized.
451 llvm::Value *element = begin;
453 // Emit the explicit initializers.
454 for (uint64_t i = 0; i != NumInitElements; ++i) {
455 // Advance to the next element.
457 element = Builder.CreateInBoundsGEP(element, one, "arrayinit.element");
459 // Tell the cleanup that it needs to destroy up to this
460 // element. TODO: some of these stores can be trivially
461 // observed to be unnecessary.
462 if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit);
466 CGF.MakeAddrLValue(Address(element, elementAlign), elementType);
467 EmitInitializationToLValue(E->getInit(i), elementLV);
470 // Check whether there's a non-trivial array-fill expression.
471 Expr *filler = E->getArrayFiller();
472 bool hasTrivialFiller = isTrivialFiller(filler);
474 // Any remaining elements need to be zero-initialized, possibly
475 // using the filler expression. We can skip this if the we're
476 // emitting to zeroed memory.
477 if (NumInitElements != NumArrayElements &&
478 !(Dest.isZeroed() && hasTrivialFiller &&
479 CGF.getTypes().isZeroInitializable(elementType))) {
481 // Use an actual loop. This is basically
482 // do { *array++ = filler; } while (array != end);
484 // Advance to the start of the rest of the array.
485 if (NumInitElements) {
486 element = Builder.CreateInBoundsGEP(element, one, "arrayinit.start");
487 if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit);
490 // Compute the end of the array.
491 llvm::Value *end = Builder.CreateInBoundsGEP(begin,
492 llvm::ConstantInt::get(CGF.SizeTy, NumArrayElements),
495 llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
496 llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body");
498 // Jump into the body.
499 CGF.EmitBlock(bodyBB);
500 llvm::PHINode *currentElement =
501 Builder.CreatePHI(element->getType(), 2, "arrayinit.cur");
502 currentElement->addIncoming(element, entryBB);
504 // Emit the actual filler expression.
506 CGF.MakeAddrLValue(Address(currentElement, elementAlign), elementType);
508 EmitInitializationToLValue(filler, elementLV);
510 EmitNullInitializationToLValue(elementLV);
512 // Move on to the next element.
513 llvm::Value *nextElement =
514 Builder.CreateInBoundsGEP(currentElement, one, "arrayinit.next");
516 // Tell the EH cleanup that we finished with the last element.
517 if (endOfInit.isValid()) Builder.CreateStore(nextElement, endOfInit);
519 // Leave the loop if we're done.
520 llvm::Value *done = Builder.CreateICmpEQ(nextElement, end,
522 llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end");
523 Builder.CreateCondBr(done, endBB, bodyBB);
524 currentElement->addIncoming(nextElement, Builder.GetInsertBlock());
526 CGF.EmitBlock(endBB);
529 // Leave the partial-array cleanup if we entered one.
530 if (dtorKind) CGF.DeactivateCleanupBlock(cleanup, cleanupDominator);
533 //===----------------------------------------------------------------------===//
535 //===----------------------------------------------------------------------===//
537 void AggExprEmitter::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E){
538 Visit(E->GetTemporaryExpr());
541 void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) {
542 EmitFinalDestCopy(e->getType(), CGF.getOpaqueLValueMapping(e));
546 AggExprEmitter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
547 if (Dest.isPotentiallyAliased() &&
548 E->getType().isPODType(CGF.getContext())) {
549 // For a POD type, just emit a load of the lvalue + a copy, because our
550 // compound literal might alias the destination.
551 EmitAggLoadOfLValue(E);
555 AggValueSlot Slot = EnsureSlot(E->getType());
556 CGF.EmitAggExpr(E->getInitializer(), Slot);
559 /// Attempt to look through various unimportant expressions to find a
560 /// cast of the given kind.
561 static Expr *findPeephole(Expr *op, CastKind kind) {
563 op = op->IgnoreParens();
564 if (CastExpr *castE = dyn_cast<CastExpr>(op)) {
565 if (castE->getCastKind() == kind)
566 return castE->getSubExpr();
567 if (castE->getCastKind() == CK_NoOp)
574 void AggExprEmitter::VisitCastExpr(CastExpr *E) {
575 if (const auto *ECE = dyn_cast<ExplicitCastExpr>(E))
576 CGF.CGM.EmitExplicitCastExprType(ECE, &CGF);
577 switch (E->getCastKind()) {
579 // FIXME: Can this actually happen? We have no test coverage for it.
580 assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?");
581 LValue LV = CGF.EmitCheckedLValue(E->getSubExpr(),
582 CodeGenFunction::TCK_Load);
583 // FIXME: Do we also need to handle property references here?
585 CGF.EmitDynamicCast(LV.getAddress(), cast<CXXDynamicCastExpr>(E));
587 CGF.CGM.ErrorUnsupported(E, "non-simple lvalue dynamic_cast");
589 if (!Dest.isIgnored())
590 CGF.CGM.ErrorUnsupported(E, "lvalue dynamic_cast with a destination");
595 // Evaluate even if the destination is ignored.
596 if (Dest.isIgnored()) {
597 CGF.EmitAnyExpr(E->getSubExpr(), AggValueSlot::ignored(),
598 /*ignoreResult=*/true);
602 // GCC union extension
603 QualType Ty = E->getSubExpr()->getType();
605 Builder.CreateElementBitCast(Dest.getAddress(), CGF.ConvertType(Ty));
606 EmitInitializationToLValue(E->getSubExpr(),
607 CGF.MakeAddrLValue(CastPtr, Ty));
611 case CK_DerivedToBase:
612 case CK_BaseToDerived:
613 case CK_UncheckedDerivedToBase: {
614 llvm_unreachable("cannot perform hierarchy conversion in EmitAggExpr: "
615 "should have been unpacked before we got here");
618 case CK_NonAtomicToAtomic:
619 case CK_AtomicToNonAtomic: {
620 bool isToAtomic = (E->getCastKind() == CK_NonAtomicToAtomic);
622 // Determine the atomic and value types.
623 QualType atomicType = E->getSubExpr()->getType();
624 QualType valueType = E->getType();
625 if (isToAtomic) std::swap(atomicType, valueType);
627 assert(atomicType->isAtomicType());
628 assert(CGF.getContext().hasSameUnqualifiedType(valueType,
629 atomicType->castAs<AtomicType>()->getValueType()));
631 // Just recurse normally if we're ignoring the result or the
632 // atomic type doesn't change representation.
633 if (Dest.isIgnored() || !CGF.CGM.isPaddedAtomicType(atomicType)) {
634 return Visit(E->getSubExpr());
637 CastKind peepholeTarget =
638 (isToAtomic ? CK_AtomicToNonAtomic : CK_NonAtomicToAtomic);
640 // These two cases are reverses of each other; try to peephole them.
641 if (Expr *op = findPeephole(E->getSubExpr(), peepholeTarget)) {
642 assert(CGF.getContext().hasSameUnqualifiedType(op->getType(),
644 "peephole significantly changed types?");
648 // If we're converting an r-value of non-atomic type to an r-value
649 // of atomic type, just emit directly into the relevant sub-object.
651 AggValueSlot valueDest = Dest;
652 if (!valueDest.isIgnored() && CGF.CGM.isPaddedAtomicType(atomicType)) {
653 // Zero-initialize. (Strictly speaking, we only need to intialize
654 // the padding at the end, but this is simpler.)
655 if (!Dest.isZeroed())
656 CGF.EmitNullInitialization(Dest.getAddress(), atomicType);
658 // Build a GEP to refer to the subobject.
660 CGF.Builder.CreateStructGEP(valueDest.getAddress(), 0,
662 valueDest = AggValueSlot::forAddr(valueAddr,
663 valueDest.getQualifiers(),
664 valueDest.isExternallyDestructed(),
665 valueDest.requiresGCollection(),
666 valueDest.isPotentiallyAliased(),
667 AggValueSlot::IsZeroed);
670 CGF.EmitAggExpr(E->getSubExpr(), valueDest);
674 // Otherwise, we're converting an atomic type to a non-atomic type.
675 // Make an atomic temporary, emit into that, and then copy the value out.
676 AggValueSlot atomicSlot =
677 CGF.CreateAggTemp(atomicType, "atomic-to-nonatomic.temp");
678 CGF.EmitAggExpr(E->getSubExpr(), atomicSlot);
681 Builder.CreateStructGEP(atomicSlot.getAddress(), 0, CharUnits());
682 RValue rvalue = RValue::getAggregate(valueAddr, atomicSlot.isVolatile());
683 return EmitFinalDestCopy(valueType, rvalue);
686 case CK_LValueToRValue:
687 // If we're loading from a volatile type, force the destination
689 if (E->getSubExpr()->getType().isVolatileQualified()) {
690 EnsureDest(E->getType());
691 return Visit(E->getSubExpr());
697 case CK_UserDefinedConversion:
698 case CK_ConstructorConversion:
699 assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
701 "Implicit cast types must be compatible");
702 Visit(E->getSubExpr());
705 case CK_LValueBitCast:
706 llvm_unreachable("should not be emitting lvalue bitcast as rvalue");
710 case CK_ArrayToPointerDecay:
711 case CK_FunctionToPointerDecay:
712 case CK_NullToPointer:
713 case CK_NullToMemberPointer:
714 case CK_BaseToDerivedMemberPointer:
715 case CK_DerivedToBaseMemberPointer:
716 case CK_MemberPointerToBoolean:
717 case CK_ReinterpretMemberPointer:
718 case CK_IntegralToPointer:
719 case CK_PointerToIntegral:
720 case CK_PointerToBoolean:
723 case CK_IntegralCast:
724 case CK_BooleanToSignedIntegral:
725 case CK_IntegralToBoolean:
726 case CK_IntegralToFloating:
727 case CK_FloatingToIntegral:
728 case CK_FloatingToBoolean:
729 case CK_FloatingCast:
730 case CK_CPointerToObjCPointerCast:
731 case CK_BlockPointerToObjCPointerCast:
732 case CK_AnyPointerToBlockPointerCast:
733 case CK_ObjCObjectLValueCast:
734 case CK_FloatingRealToComplex:
735 case CK_FloatingComplexToReal:
736 case CK_FloatingComplexToBoolean:
737 case CK_FloatingComplexCast:
738 case CK_FloatingComplexToIntegralComplex:
739 case CK_IntegralRealToComplex:
740 case CK_IntegralComplexToReal:
741 case CK_IntegralComplexToBoolean:
742 case CK_IntegralComplexCast:
743 case CK_IntegralComplexToFloatingComplex:
744 case CK_ARCProduceObject:
745 case CK_ARCConsumeObject:
746 case CK_ARCReclaimReturnedObject:
747 case CK_ARCExtendBlockObject:
748 case CK_CopyAndAutoreleaseBlockObject:
749 case CK_BuiltinFnToFnPtr:
750 case CK_ZeroToOCLEvent:
751 case CK_AddressSpaceConversion:
752 llvm_unreachable("cast kind invalid for aggregate types");
756 void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
757 if (E->getCallReturnType(CGF.getContext())->isReferenceType()) {
758 EmitAggLoadOfLValue(E);
762 RValue RV = CGF.EmitCallExpr(E, getReturnValueSlot());
763 EmitMoveFromReturnSlot(E, RV);
766 void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
767 RValue RV = CGF.EmitObjCMessageExpr(E, getReturnValueSlot());
768 EmitMoveFromReturnSlot(E, RV);
771 void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
772 CGF.EmitIgnoredExpr(E->getLHS());
776 void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
777 CodeGenFunction::StmtExprEvaluation eval(CGF);
778 CGF.EmitCompoundStmt(*E->getSubStmt(), true, Dest);
781 void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
782 if (E->getOpcode() == BO_PtrMemD || E->getOpcode() == BO_PtrMemI)
783 VisitPointerToDataMemberBinaryOperator(E);
785 CGF.ErrorUnsupported(E, "aggregate binary expression");
788 void AggExprEmitter::VisitPointerToDataMemberBinaryOperator(
789 const BinaryOperator *E) {
790 LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E);
791 EmitFinalDestCopy(E->getType(), LV);
794 /// Is the value of the given expression possibly a reference to or
795 /// into a __block variable?
796 static bool isBlockVarRef(const Expr *E) {
797 // Make sure we look through parens.
798 E = E->IgnoreParens();
800 // Check for a direct reference to a __block variable.
801 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) {
802 const VarDecl *var = dyn_cast<VarDecl>(DRE->getDecl());
803 return (var && var->hasAttr<BlocksAttr>());
806 // More complicated stuff.
809 if (const BinaryOperator *op = dyn_cast<BinaryOperator>(E)) {
810 // For an assignment or pointer-to-member operation, just care
812 if (op->isAssignmentOp() || op->isPtrMemOp())
813 return isBlockVarRef(op->getLHS());
815 // For a comma, just care about the RHS.
816 if (op->getOpcode() == BO_Comma)
817 return isBlockVarRef(op->getRHS());
819 // FIXME: pointer arithmetic?
822 // Check both sides of a conditional operator.
823 } else if (const AbstractConditionalOperator *op
824 = dyn_cast<AbstractConditionalOperator>(E)) {
825 return isBlockVarRef(op->getTrueExpr())
826 || isBlockVarRef(op->getFalseExpr());
828 // OVEs are required to support BinaryConditionalOperators.
829 } else if (const OpaqueValueExpr *op
830 = dyn_cast<OpaqueValueExpr>(E)) {
831 if (const Expr *src = op->getSourceExpr())
832 return isBlockVarRef(src);
834 // Casts are necessary to get things like (*(int*)&var) = foo().
835 // We don't really care about the kind of cast here, except
836 // we don't want to look through l2r casts, because it's okay
837 // to get the *value* in a __block variable.
838 } else if (const CastExpr *cast = dyn_cast<CastExpr>(E)) {
839 if (cast->getCastKind() == CK_LValueToRValue)
841 return isBlockVarRef(cast->getSubExpr());
843 // Handle unary operators. Again, just aggressively look through
844 // it, ignoring the operation.
845 } else if (const UnaryOperator *uop = dyn_cast<UnaryOperator>(E)) {
846 return isBlockVarRef(uop->getSubExpr());
848 // Look into the base of a field access.
849 } else if (const MemberExpr *mem = dyn_cast<MemberExpr>(E)) {
850 return isBlockVarRef(mem->getBase());
852 // Look into the base of a subscript.
853 } else if (const ArraySubscriptExpr *sub = dyn_cast<ArraySubscriptExpr>(E)) {
854 return isBlockVarRef(sub->getBase());
860 void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
861 // For an assignment to work, the value on the right has
862 // to be compatible with the value on the left.
863 assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(),
864 E->getRHS()->getType())
865 && "Invalid assignment");
867 // If the LHS might be a __block variable, and the RHS can
868 // potentially cause a block copy, we need to evaluate the RHS first
869 // so that the assignment goes the right place.
870 // This is pretty semantically fragile.
871 if (isBlockVarRef(E->getLHS()) &&
872 E->getRHS()->HasSideEffects(CGF.getContext())) {
873 // Ensure that we have a destination, and evaluate the RHS into that.
874 EnsureDest(E->getRHS()->getType());
877 // Now emit the LHS and copy into it.
878 LValue LHS = CGF.EmitCheckedLValue(E->getLHS(), CodeGenFunction::TCK_Store);
880 // That copy is an atomic copy if the LHS is atomic.
881 if (LHS.getType()->isAtomicType() ||
882 CGF.LValueIsSuitableForInlineAtomic(LHS)) {
883 CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false);
887 EmitCopy(E->getLHS()->getType(),
888 AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
889 needsGC(E->getLHS()->getType()),
890 AggValueSlot::IsAliased),
895 LValue LHS = CGF.EmitLValue(E->getLHS());
897 // If we have an atomic type, evaluate into the destination and then
898 // do an atomic copy.
899 if (LHS.getType()->isAtomicType() ||
900 CGF.LValueIsSuitableForInlineAtomic(LHS)) {
901 EnsureDest(E->getRHS()->getType());
903 CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false);
907 // Codegen the RHS so that it stores directly into the LHS.
908 AggValueSlot LHSSlot =
909 AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
910 needsGC(E->getLHS()->getType()),
911 AggValueSlot::IsAliased);
912 // A non-volatile aggregate destination might have volatile member.
913 if (!LHSSlot.isVolatile() &&
914 CGF.hasVolatileMember(E->getLHS()->getType()))
915 LHSSlot.setVolatile(true);
917 CGF.EmitAggExpr(E->getRHS(), LHSSlot);
919 // Copy into the destination if the assignment isn't ignored.
920 EmitFinalDestCopy(E->getType(), LHS);
923 void AggExprEmitter::
924 VisitAbstractConditionalOperator(const AbstractConditionalOperator *E) {
925 llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
926 llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
927 llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
929 // Bind the common expression if necessary.
930 CodeGenFunction::OpaqueValueMapping binding(CGF, E);
932 CodeGenFunction::ConditionalEvaluation eval(CGF);
933 CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock,
934 CGF.getProfileCount(E));
936 // Save whether the destination's lifetime is externally managed.
937 bool isExternallyDestructed = Dest.isExternallyDestructed();
940 CGF.EmitBlock(LHSBlock);
941 CGF.incrementProfileCounter(E);
942 Visit(E->getTrueExpr());
945 assert(CGF.HaveInsertPoint() && "expression evaluation ended with no IP!");
946 CGF.Builder.CreateBr(ContBlock);
948 // If the result of an agg expression is unused, then the emission
949 // of the LHS might need to create a destination slot. That's fine
950 // with us, and we can safely emit the RHS into the same slot, but
951 // we shouldn't claim that it's already being destructed.
952 Dest.setExternallyDestructed(isExternallyDestructed);
955 CGF.EmitBlock(RHSBlock);
956 Visit(E->getFalseExpr());
959 CGF.EmitBlock(ContBlock);
962 void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
963 Visit(CE->getChosenSubExpr());
966 void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
967 Address ArgValue = Address::invalid();
968 Address ArgPtr = CGF.EmitVAArg(VE, ArgValue);
970 if (!ArgPtr.isValid()) {
971 // If EmitVAArg fails, we fall back to the LLVM instruction.
972 llvm::Value *Val = Builder.CreateVAArg(ArgValue.getPointer(),
973 CGF.ConvertType(VE->getType()));
974 if (!Dest.isIgnored())
975 Builder.CreateStore(Val, Dest.getAddress());
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);
1005 AggExprEmitter::VisitLambdaExpr(LambdaExpr *E) {
1006 AggValueSlot Slot = EnsureSlot(E->getType());
1007 CGF.EmitLambdaExpr(E, Slot);
1010 void AggExprEmitter::VisitExprWithCleanups(ExprWithCleanups *E) {
1011 CGF.enterFullExpression(E);
1012 CodeGenFunction::RunCleanupsScope cleanups(CGF);
1013 Visit(E->getSubExpr());
1016 void AggExprEmitter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) {
1017 QualType T = E->getType();
1018 AggValueSlot Slot = EnsureSlot(T);
1019 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddress(), T));
1022 void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
1023 QualType T = E->getType();
1024 AggValueSlot Slot = EnsureSlot(T);
1025 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddress(), T));
1028 /// isSimpleZero - If emitting this value will obviously just cause a store of
1029 /// zero to memory, return true. This can return false if uncertain, so it just
1030 /// handles simple cases.
1031 static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) {
1032 E = E->IgnoreParens();
1035 if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E))
1036 return IL->getValue() == 0;
1038 if (const FloatingLiteral *FL = dyn_cast<FloatingLiteral>(E))
1039 return FL->getValue().isPosZero();
1041 if ((isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) &&
1042 CGF.getTypes().isZeroInitializable(E->getType()))
1044 // (int*)0 - Null pointer expressions.
1045 if (const CastExpr *ICE = dyn_cast<CastExpr>(E))
1046 return ICE->getCastKind() == CK_NullToPointer;
1048 if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E))
1049 return CL->getValue() == 0;
1051 // Otherwise, hard case: conservatively return false.
1057 AggExprEmitter::EmitInitializationToLValue(Expr *E, LValue LV) {
1058 QualType type = LV.getType();
1059 // FIXME: Ignore result?
1060 // FIXME: Are initializers affected by volatile?
1061 if (Dest.isZeroed() && isSimpleZero(E, CGF)) {
1062 // Storing "i32 0" to a zero'd memory location is a noop.
1064 } else if (isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) {
1065 return EmitNullInitializationToLValue(LV);
1066 } else if (isa<NoInitExpr>(E)) {
1069 } else if (type->isReferenceType()) {
1070 RValue RV = CGF.EmitReferenceBindingToExpr(E);
1071 return CGF.EmitStoreThroughLValue(RV, LV);
1074 switch (CGF.getEvaluationKind(type)) {
1076 CGF.EmitComplexExprIntoLValue(E, LV, /*isInit*/ true);
1079 CGF.EmitAggExpr(E, AggValueSlot::forLValue(LV,
1080 AggValueSlot::IsDestructed,
1081 AggValueSlot::DoesNotNeedGCBarriers,
1082 AggValueSlot::IsNotAliased,
1086 if (LV.isSimple()) {
1087 CGF.EmitScalarInit(E, /*D=*/nullptr, LV, /*Captured=*/false);
1089 CGF.EmitStoreThroughLValue(RValue::get(CGF.EmitScalarExpr(E)), LV);
1093 llvm_unreachable("bad evaluation kind");
1096 void AggExprEmitter::EmitNullInitializationToLValue(LValue lv) {
1097 QualType type = lv.getType();
1099 // If the destination slot is already zeroed out before the aggregate is
1100 // copied into it, we don't have to emit any zeros here.
1101 if (Dest.isZeroed() && CGF.getTypes().isZeroInitializable(type))
1104 if (CGF.hasScalarEvaluationKind(type)) {
1105 // For non-aggregates, we can store the appropriate null constant.
1106 llvm::Value *null = CGF.CGM.EmitNullConstant(type);
1107 // Note that the following is not equivalent to
1108 // EmitStoreThroughBitfieldLValue for ARC types.
1109 if (lv.isBitField()) {
1110 CGF.EmitStoreThroughBitfieldLValue(RValue::get(null), lv);
1112 assert(lv.isSimple());
1113 CGF.EmitStoreOfScalar(null, lv, /* isInitialization */ true);
1116 // There's a potential optimization opportunity in combining
1117 // memsets; that would be easy for arrays, but relatively
1118 // difficult for structures with the current code.
1119 CGF.EmitNullInitialization(lv.getAddress(), lv.getType());
1123 void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
1125 // FIXME: Assess perf here? Figure out what cases are worth optimizing here
1126 // (Length of globals? Chunks of zeroed-out space?).
1128 // If we can, prefer a copy from a global; this is a lot less code for long
1129 // globals, and it's easier for the current optimizers to analyze.
1130 if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
1131 llvm::GlobalVariable* GV =
1132 new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
1133 llvm::GlobalValue::InternalLinkage, C, "");
1134 EmitFinalDestCopy(E->getType(), CGF.MakeAddrLValue(GV, E->getType()));
1138 if (E->hadArrayRangeDesignator())
1139 CGF.ErrorUnsupported(E, "GNU array range designator extension");
1141 AggValueSlot Dest = EnsureSlot(E->getType());
1143 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
1145 // Handle initialization of an array.
1146 if (E->getType()->isArrayType()) {
1147 if (E->isStringLiteralInit())
1148 return Visit(E->getInit(0));
1150 QualType elementType =
1151 CGF.getContext().getAsArrayType(E->getType())->getElementType();
1153 auto AType = cast<llvm::ArrayType>(Dest.getAddress().getElementType());
1154 EmitArrayInit(Dest.getAddress(), AType, elementType, E);
1158 if (E->getType()->isAtomicType()) {
1159 // An _Atomic(T) object can be list-initialized from an expression
1160 // of the same type.
1161 assert(E->getNumInits() == 1 &&
1162 CGF.getContext().hasSameUnqualifiedType(E->getInit(0)->getType(),
1164 "unexpected list initialization for atomic object");
1165 return Visit(E->getInit(0));
1168 assert(E->getType()->isRecordType() && "Only support structs/unions here!");
1170 // Do struct initialization; this code just sets each individual member
1171 // to the approprate value. This makes bitfield support automatic;
1172 // the disadvantage is that the generated code is more difficult for
1173 // the optimizer, especially with bitfields.
1174 unsigned NumInitElements = E->getNumInits();
1175 RecordDecl *record = E->getType()->castAs<RecordType>()->getDecl();
1177 // Prepare a 'this' for CXXDefaultInitExprs.
1178 CodeGenFunction::FieldConstructionScope FCS(CGF, Dest.getAddress());
1180 if (record->isUnion()) {
1181 // Only initialize one field of a union. The field itself is
1182 // specified by the initializer list.
1183 if (!E->getInitializedFieldInUnion()) {
1184 // Empty union; we have nothing to do.
1187 // Make sure that it's really an empty and not a failure of
1188 // semantic analysis.
1189 for (const auto *Field : record->fields())
1190 assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
1195 // FIXME: volatility
1196 FieldDecl *Field = E->getInitializedFieldInUnion();
1198 LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestLV, Field);
1199 if (NumInitElements) {
1200 // Store the initializer into the field
1201 EmitInitializationToLValue(E->getInit(0), FieldLoc);
1203 // Default-initialize to null.
1204 EmitNullInitializationToLValue(FieldLoc);
1210 // We'll need to enter cleanup scopes in case any of the member
1211 // initializers throw an exception.
1212 SmallVector<EHScopeStack::stable_iterator, 16> cleanups;
1213 llvm::Instruction *cleanupDominator = nullptr;
1215 // Here we iterate over the fields; this makes it simpler to both
1216 // default-initialize fields and skip over unnamed fields.
1217 unsigned curInitIndex = 0;
1218 for (const auto *field : record->fields()) {
1219 // We're done once we hit the flexible array member.
1220 if (field->getType()->isIncompleteArrayType())
1223 // Always skip anonymous bitfields.
1224 if (field->isUnnamedBitfield())
1227 // We're done if we reach the end of the explicit initializers, we
1228 // have a zeroed object, and the rest of the fields are
1229 // zero-initializable.
1230 if (curInitIndex == NumInitElements && Dest.isZeroed() &&
1231 CGF.getTypes().isZeroInitializable(E->getType()))
1235 LValue LV = CGF.EmitLValueForFieldInitialization(DestLV, field);
1236 // We never generate write-barries for initialized fields.
1239 if (curInitIndex < NumInitElements) {
1240 // Store the initializer into the field.
1241 EmitInitializationToLValue(E->getInit(curInitIndex++), LV);
1243 // We're out of initalizers; default-initialize to null
1244 EmitNullInitializationToLValue(LV);
1247 // Push a destructor if necessary.
1248 // FIXME: if we have an array of structures, all explicitly
1249 // initialized, we can end up pushing a linear number of cleanups.
1250 bool pushedCleanup = false;
1251 if (QualType::DestructionKind dtorKind
1252 = field->getType().isDestructedType()) {
1253 assert(LV.isSimple());
1254 if (CGF.needsEHCleanup(dtorKind)) {
1255 if (!cleanupDominator)
1256 cleanupDominator = CGF.Builder.CreateAlignedLoad(
1258 llvm::Constant::getNullValue(CGF.Int8PtrTy),
1259 CharUnits::One()); // placeholder
1261 CGF.pushDestroy(EHCleanup, LV.getAddress(), field->getType(),
1262 CGF.getDestroyer(dtorKind), false);
1263 cleanups.push_back(CGF.EHStack.stable_begin());
1264 pushedCleanup = true;
1268 // If the GEP didn't get used because of a dead zero init or something
1269 // else, clean it up for -O0 builds and general tidiness.
1270 if (!pushedCleanup && LV.isSimple())
1271 if (llvm::GetElementPtrInst *GEP =
1272 dyn_cast<llvm::GetElementPtrInst>(LV.getPointer()))
1273 if (GEP->use_empty())
1274 GEP->eraseFromParent();
1277 // Deactivate all the partial cleanups in reverse order, which
1278 // generally means popping them.
1279 for (unsigned i = cleanups.size(); i != 0; --i)
1280 CGF.DeactivateCleanupBlock(cleanups[i-1], cleanupDominator);
1282 // Destroy the placeholder if we made one.
1283 if (cleanupDominator)
1284 cleanupDominator->eraseFromParent();
1287 void AggExprEmitter::VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E) {
1288 AggValueSlot Dest = EnsureSlot(E->getType());
1290 LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType());
1291 EmitInitializationToLValue(E->getBase(), DestLV);
1292 VisitInitListExpr(E->getUpdater());
1295 //===----------------------------------------------------------------------===//
1296 // Entry Points into this File
1297 //===----------------------------------------------------------------------===//
1299 /// GetNumNonZeroBytesInInit - Get an approximate count of the number of
1300 /// non-zero bytes that will be stored when outputting the initializer for the
1301 /// specified initializer expression.
1302 static CharUnits GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) {
1303 E = E->IgnoreParens();
1305 // 0 and 0.0 won't require any non-zero stores!
1306 if (isSimpleZero(E, CGF)) return CharUnits::Zero();
1308 // If this is an initlist expr, sum up the size of sizes of the (present)
1309 // elements. If this is something weird, assume the whole thing is non-zero.
1310 const InitListExpr *ILE = dyn_cast<InitListExpr>(E);
1311 if (!ILE || !CGF.getTypes().isZeroInitializable(ILE->getType()))
1312 return CGF.getContext().getTypeSizeInChars(E->getType());
1314 // InitListExprs for structs have to be handled carefully. If there are
1315 // reference members, we need to consider the size of the reference, not the
1316 // referencee. InitListExprs for unions and arrays can't have references.
1317 if (const RecordType *RT = E->getType()->getAs<RecordType>()) {
1318 if (!RT->isUnionType()) {
1319 RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
1320 CharUnits NumNonZeroBytes = CharUnits::Zero();
1322 unsigned ILEElement = 0;
1323 for (const auto *Field : SD->fields()) {
1324 // We're done once we hit the flexible array member or run out of
1325 // InitListExpr elements.
1326 if (Field->getType()->isIncompleteArrayType() ||
1327 ILEElement == ILE->getNumInits())
1329 if (Field->isUnnamedBitfield())
1332 const Expr *E = ILE->getInit(ILEElement++);
1334 // Reference values are always non-null and have the width of a pointer.
1335 if (Field->getType()->isReferenceType())
1336 NumNonZeroBytes += CGF.getContext().toCharUnitsFromBits(
1337 CGF.getTarget().getPointerWidth(0));
1339 NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF);
1342 return NumNonZeroBytes;
1347 CharUnits NumNonZeroBytes = CharUnits::Zero();
1348 for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i)
1349 NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF);
1350 return NumNonZeroBytes;
1353 /// CheckAggExprForMemSetUse - If the initializer is large and has a lot of
1354 /// zeros in it, emit a memset and avoid storing the individual zeros.
1356 static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E,
1357 CodeGenFunction &CGF) {
1358 // If the slot is already known to be zeroed, nothing to do. Don't mess with
1360 if (Slot.isZeroed() || Slot.isVolatile() || !Slot.getAddress().isValid())
1363 // C++ objects with a user-declared constructor don't need zero'ing.
1364 if (CGF.getLangOpts().CPlusPlus)
1365 if (const RecordType *RT = CGF.getContext()
1366 .getBaseElementType(E->getType())->getAs<RecordType>()) {
1367 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1368 if (RD->hasUserDeclaredConstructor())
1372 // If the type is 16-bytes or smaller, prefer individual stores over memset.
1373 CharUnits Size = CGF.getContext().getTypeSizeInChars(E->getType());
1374 if (Size <= CharUnits::fromQuantity(16))
1377 // Check to see if over 3/4 of the initializer are known to be zero. If so,
1378 // we prefer to emit memset + individual stores for the rest.
1379 CharUnits NumNonZeroBytes = GetNumNonZeroBytesInInit(E, CGF);
1380 if (NumNonZeroBytes*4 > Size)
1383 // Okay, it seems like a good idea to use an initial memset, emit the call.
1384 llvm::Constant *SizeVal = CGF.Builder.getInt64(Size.getQuantity());
1386 Address Loc = Slot.getAddress();
1387 Loc = CGF.Builder.CreateElementBitCast(Loc, CGF.Int8Ty);
1388 CGF.Builder.CreateMemSet(Loc, CGF.Builder.getInt8(0), SizeVal, false);
1390 // Tell the AggExprEmitter that the slot is known zero.
1397 /// EmitAggExpr - Emit the computation of the specified expression of aggregate
1398 /// type. The result is computed into DestPtr. Note that if DestPtr is null,
1399 /// the value of the aggregate expression is not needed. If VolatileDest is
1400 /// true, DestPtr cannot be 0.
1401 void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot) {
1402 assert(E && hasAggregateEvaluationKind(E->getType()) &&
1403 "Invalid aggregate expression to emit");
1404 assert((Slot.getAddress().isValid() || Slot.isIgnored()) &&
1405 "slot has bits but no address");
1407 // Optimize the slot if possible.
1408 CheckAggExprForMemSetUse(Slot, E, *this);
1410 AggExprEmitter(*this, Slot, Slot.isIgnored()).Visit(const_cast<Expr*>(E));
1413 LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) {
1414 assert(hasAggregateEvaluationKind(E->getType()) && "Invalid argument!");
1415 Address Temp = CreateMemTemp(E->getType());
1416 LValue LV = MakeAddrLValue(Temp, E->getType());
1417 EmitAggExpr(E, AggValueSlot::forLValue(LV, AggValueSlot::IsNotDestructed,
1418 AggValueSlot::DoesNotNeedGCBarriers,
1419 AggValueSlot::IsNotAliased));
1423 void CodeGenFunction::EmitAggregateCopy(Address DestPtr,
1424 Address SrcPtr, QualType Ty,
1426 bool isAssignment) {
1427 assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
1429 if (getLangOpts().CPlusPlus) {
1430 if (const RecordType *RT = Ty->getAs<RecordType>()) {
1431 CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl());
1432 assert((Record->hasTrivialCopyConstructor() ||
1433 Record->hasTrivialCopyAssignment() ||
1434 Record->hasTrivialMoveConstructor() ||
1435 Record->hasTrivialMoveAssignment() ||
1436 Record->isUnion()) &&
1437 "Trying to aggregate-copy a type without a trivial copy/move "
1438 "constructor or assignment operator");
1439 // Ignore empty classes in C++.
1440 if (Record->isEmpty())
1445 // Aggregate assignment turns into llvm.memcpy. This is almost valid per
1446 // C99 6.5.16.1p3, which states "If the value being stored in an object is
1447 // read from another object that overlaps in anyway the storage of the first
1448 // object, then the overlap shall be exact and the two objects shall have
1449 // qualified or unqualified versions of a compatible type."
1451 // memcpy is not defined if the source and destination pointers are exactly
1452 // equal, but other compilers do this optimization, and almost every memcpy
1453 // implementation handles this case safely. If there is a libc that does not
1454 // safely handle this, we can add a target hook.
1456 // Get data size info for this aggregate. If this is an assignment,
1457 // don't copy the tail padding, because we might be assigning into a
1458 // base subobject where the tail padding is claimed. Otherwise,
1459 // copying it is fine.
1460 std::pair<CharUnits, CharUnits> TypeInfo;
1462 TypeInfo = getContext().getTypeInfoDataSizeInChars(Ty);
1464 TypeInfo = getContext().getTypeInfoInChars(Ty);
1466 llvm::Value *SizeVal = nullptr;
1467 if (TypeInfo.first.isZero()) {
1468 // But note that getTypeInfo returns 0 for a VLA.
1469 if (auto *VAT = dyn_cast_or_null<VariableArrayType>(
1470 getContext().getAsArrayType(Ty))) {
1472 SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr);
1473 TypeInfo = getContext().getTypeInfoDataSizeInChars(BaseEltTy);
1474 std::pair<CharUnits, CharUnits> LastElementTypeInfo;
1476 LastElementTypeInfo = getContext().getTypeInfoInChars(BaseEltTy);
1477 assert(!TypeInfo.first.isZero());
1478 SizeVal = Builder.CreateNUWMul(
1480 llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity()));
1481 if (!isAssignment) {
1482 SizeVal = Builder.CreateNUWSub(
1484 llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity()));
1485 SizeVal = Builder.CreateNUWAdd(
1486 SizeVal, llvm::ConstantInt::get(
1487 SizeTy, LastElementTypeInfo.first.getQuantity()));
1492 SizeVal = llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity());
1495 // FIXME: If we have a volatile struct, the optimizer can remove what might
1496 // appear to be `extra' memory ops:
1498 // volatile struct { int i; } a, b;
1505 // we need to use a different call here. We use isVolatile to indicate when
1506 // either the source or the destination is volatile.
1508 DestPtr = Builder.CreateElementBitCast(DestPtr, Int8Ty);
1509 SrcPtr = Builder.CreateElementBitCast(SrcPtr, Int8Ty);
1511 // Don't do any of the memmove_collectable tests if GC isn't set.
1512 if (CGM.getLangOpts().getGC() == LangOptions::NonGC) {
1514 } else if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
1515 RecordDecl *Record = RecordTy->getDecl();
1516 if (Record->hasObjectMember()) {
1517 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1521 } else if (Ty->isArrayType()) {
1522 QualType BaseType = getContext().getBaseElementType(Ty);
1523 if (const RecordType *RecordTy = BaseType->getAs<RecordType>()) {
1524 if (RecordTy->getDecl()->hasObjectMember()) {
1525 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1532 auto Inst = Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, isVolatile);
1534 // Determine the metadata to describe the position of any padding in this
1535 // memcpy, as well as the TBAA tags for the members of the struct, in case
1536 // the optimizer wishes to expand it in to scalar memory operations.
1537 if (llvm::MDNode *TBAAStructTag = CGM.getTBAAStructInfo(Ty))
1538 Inst->setMetadata(llvm::LLVMContext::MD_tbaa_struct, TBAAStructTag);