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 "CodeGenModule.h"
16 #include "CGObjCRuntime.h"
17 #include "clang/AST/ASTContext.h"
18 #include "clang/AST/DeclCXX.h"
19 #include "clang/AST/StmtVisitor.h"
20 #include "llvm/Constants.h"
21 #include "llvm/Function.h"
22 #include "llvm/GlobalVariable.h"
23 #include "llvm/Intrinsics.h"
24 using namespace clang;
25 using namespace CodeGen;
27 //===----------------------------------------------------------------------===//
28 // Aggregate Expression Emitter
29 //===----------------------------------------------------------------------===//
32 class AggExprEmitter : public StmtVisitor<AggExprEmitter> {
38 /// We want to use 'dest' as the return slot except under two
40 /// - The destination slot requires garbage collection, so we
41 /// need to use the GC API.
42 /// - The destination slot is potentially aliased.
43 bool shouldUseDestForReturnSlot() const {
44 return !(Dest.requiresGCollection() || Dest.isPotentiallyAliased());
47 ReturnValueSlot getReturnValueSlot() const {
48 if (!shouldUseDestForReturnSlot())
49 return ReturnValueSlot();
51 return ReturnValueSlot(Dest.getAddr(), Dest.isVolatile());
54 AggValueSlot EnsureSlot(QualType T) {
55 if (!Dest.isIgnored()) return Dest;
56 return CGF.CreateAggTemp(T, "agg.tmp.ensured");
60 AggExprEmitter(CodeGenFunction &cgf, AggValueSlot Dest,
62 : CGF(cgf), Builder(CGF.Builder), Dest(Dest),
63 IgnoreResult(ignore) {
66 //===--------------------------------------------------------------------===//
68 //===--------------------------------------------------------------------===//
70 /// EmitAggLoadOfLValue - Given an expression with aggregate type that
71 /// represents a value lvalue, this method emits the address of the lvalue,
72 /// then loads the result into DestPtr.
73 void EmitAggLoadOfLValue(const Expr *E);
75 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
76 void EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore = false);
77 void EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore = false);
79 void EmitMoveFromReturnSlot(const Expr *E, RValue Src);
81 AggValueSlot::NeedsGCBarriers_t needsGC(QualType T) {
82 if (CGF.getLangOptions().getGC() && TypeRequiresGCollection(T))
83 return AggValueSlot::NeedsGCBarriers;
84 return AggValueSlot::DoesNotNeedGCBarriers;
87 bool TypeRequiresGCollection(QualType T);
89 //===--------------------------------------------------------------------===//
91 //===--------------------------------------------------------------------===//
93 void VisitStmt(Stmt *S) {
94 CGF.ErrorUnsupported(S, "aggregate expression");
96 void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); }
97 void VisitGenericSelectionExpr(GenericSelectionExpr *GE) {
98 Visit(GE->getResultExpr());
100 void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); }
101 void VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) {
102 return Visit(E->getReplacement());
106 void VisitDeclRefExpr(DeclRefExpr *DRE) { EmitAggLoadOfLValue(DRE); }
107 void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); }
108 void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); }
109 void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); }
110 void VisitCompoundLiteralExpr(CompoundLiteralExpr *E);
111 void VisitArraySubscriptExpr(ArraySubscriptExpr *E) {
112 EmitAggLoadOfLValue(E);
114 void VisitBlockDeclRefExpr(const BlockDeclRefExpr *E) {
115 EmitAggLoadOfLValue(E);
117 void VisitPredefinedExpr(const PredefinedExpr *E) {
118 EmitAggLoadOfLValue(E);
122 void VisitCastExpr(CastExpr *E);
123 void VisitCallExpr(const CallExpr *E);
124 void VisitStmtExpr(const StmtExpr *E);
125 void VisitBinaryOperator(const BinaryOperator *BO);
126 void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO);
127 void VisitBinAssign(const BinaryOperator *E);
128 void VisitBinComma(const BinaryOperator *E);
130 void VisitObjCMessageExpr(ObjCMessageExpr *E);
131 void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
132 EmitAggLoadOfLValue(E);
134 void VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E);
136 void VisitAbstractConditionalOperator(const AbstractConditionalOperator *CO);
137 void VisitChooseExpr(const ChooseExpr *CE);
138 void VisitInitListExpr(InitListExpr *E);
139 void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E);
140 void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) {
141 Visit(DAE->getExpr());
143 void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E);
144 void VisitCXXConstructExpr(const CXXConstructExpr *E);
145 void VisitExprWithCleanups(ExprWithCleanups *E);
146 void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E);
147 void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); }
148 void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E);
149 void VisitOpaqueValueExpr(OpaqueValueExpr *E);
151 void VisitVAArgExpr(VAArgExpr *E);
153 void EmitInitializationToLValue(Expr *E, LValue Address);
154 void EmitNullInitializationToLValue(LValue Address);
155 // case Expr::ChooseExprClass:
156 void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); }
157 void VisitAtomicExpr(AtomicExpr *E) {
158 CGF.EmitAtomicExpr(E, EnsureSlot(E->getType()).getAddr());
161 } // end anonymous namespace.
163 //===----------------------------------------------------------------------===//
165 //===----------------------------------------------------------------------===//
167 /// EmitAggLoadOfLValue - Given an expression with aggregate type that
168 /// represents a value lvalue, this method emits the address of the lvalue,
169 /// then loads the result into DestPtr.
170 void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) {
171 LValue LV = CGF.EmitLValue(E);
172 EmitFinalDestCopy(E, LV);
175 /// \brief True if the given aggregate type requires special GC API calls.
176 bool AggExprEmitter::TypeRequiresGCollection(QualType T) {
177 // Only record types have members that might require garbage collection.
178 const RecordType *RecordTy = T->getAs<RecordType>();
179 if (!RecordTy) return false;
181 // Don't mess with non-trivial C++ types.
182 RecordDecl *Record = RecordTy->getDecl();
183 if (isa<CXXRecordDecl>(Record) &&
184 (!cast<CXXRecordDecl>(Record)->hasTrivialCopyConstructor() ||
185 !cast<CXXRecordDecl>(Record)->hasTrivialDestructor()))
188 // Check whether the type has an object member.
189 return Record->hasObjectMember();
192 /// \brief Perform the final move to DestPtr if for some reason
193 /// getReturnValueSlot() didn't use it directly.
195 /// The idea is that you do something like this:
196 /// RValue Result = EmitSomething(..., getReturnValueSlot());
197 /// EmitMoveFromReturnSlot(E, Result);
199 /// If nothing interferes, this will cause the result to be emitted
200 /// directly into the return value slot. Otherwise, a final move
201 /// will be performed.
202 void AggExprEmitter::EmitMoveFromReturnSlot(const Expr *E, RValue Src) {
203 if (shouldUseDestForReturnSlot()) {
204 // Logically, Dest.getAddr() should equal Src.getAggregateAddr().
205 // The possibility of undef rvalues complicates that a lot,
206 // though, so we can't really assert.
210 // Otherwise, do a final copy,
211 assert(Dest.getAddr() != Src.getAggregateAddr());
212 EmitFinalDestCopy(E, Src, /*Ignore*/ true);
215 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
216 void AggExprEmitter::EmitFinalDestCopy(const Expr *E, RValue Src, bool Ignore) {
217 assert(Src.isAggregate() && "value must be aggregate value!");
219 // If Dest is ignored, then we're evaluating an aggregate expression
220 // in a context (like an expression statement) that doesn't care
221 // about the result. C says that an lvalue-to-rvalue conversion is
222 // performed in these cases; C++ says that it is not. In either
223 // case, we don't actually need to do anything unless the value is
225 if (Dest.isIgnored()) {
226 if (!Src.isVolatileQualified() ||
227 CGF.CGM.getLangOptions().CPlusPlus ||
228 (IgnoreResult && Ignore))
231 // If the source is volatile, we must read from it; to do that, we need
232 // some place to put it.
233 Dest = CGF.CreateAggTemp(E->getType(), "agg.tmp");
236 if (Dest.requiresGCollection()) {
237 CharUnits size = CGF.getContext().getTypeSizeInChars(E->getType());
238 llvm::Type *SizeTy = CGF.ConvertType(CGF.getContext().getSizeType());
239 llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size.getQuantity());
240 CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF,
242 Src.getAggregateAddr(),
246 // If the result of the assignment is used, copy the LHS there also.
247 // FIXME: Pass VolatileDest as well. I think we also need to merge volatile
248 // from the source as well, as we can't eliminate it if either operand
249 // is volatile, unless copy has volatile for both source and destination..
250 CGF.EmitAggregateCopy(Dest.getAddr(), Src.getAggregateAddr(), E->getType(),
251 Dest.isVolatile()|Src.isVolatileQualified());
254 /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired.
255 void AggExprEmitter::EmitFinalDestCopy(const Expr *E, LValue Src, bool Ignore) {
256 assert(Src.isSimple() && "Can't have aggregate bitfield, vector, etc");
258 EmitFinalDestCopy(E, RValue::getAggregate(Src.getAddress(),
259 Src.isVolatileQualified()),
263 //===----------------------------------------------------------------------===//
265 //===----------------------------------------------------------------------===//
267 void AggExprEmitter::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E){
268 Visit(E->GetTemporaryExpr());
271 void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) {
272 EmitFinalDestCopy(e, CGF.getOpaqueLValueMapping(e));
276 AggExprEmitter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) {
277 if (E->getType().isPODType(CGF.getContext())) {
278 // For a POD type, just emit a load of the lvalue + a copy, because our
279 // compound literal might alias the destination.
280 // FIXME: This is a band-aid; the real problem appears to be in our handling
281 // of assignments, where we store directly into the LHS without checking
282 // whether anything in the RHS aliases.
283 EmitAggLoadOfLValue(E);
287 AggValueSlot Slot = EnsureSlot(E->getType());
288 CGF.EmitAggExpr(E->getInitializer(), Slot);
292 void AggExprEmitter::VisitCastExpr(CastExpr *E) {
293 switch (E->getCastKind()) {
295 assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?");
296 LValue LV = CGF.EmitCheckedLValue(E->getSubExpr());
297 // FIXME: Do we also need to handle property references here?
299 CGF.EmitDynamicCast(LV.getAddress(), cast<CXXDynamicCastExpr>(E));
301 CGF.CGM.ErrorUnsupported(E, "non-simple lvalue dynamic_cast");
303 if (!Dest.isIgnored())
304 CGF.CGM.ErrorUnsupported(E, "lvalue dynamic_cast with a destination");
309 if (Dest.isIgnored()) break;
311 // GCC union extension
312 QualType Ty = E->getSubExpr()->getType();
313 QualType PtrTy = CGF.getContext().getPointerType(Ty);
314 llvm::Value *CastPtr = Builder.CreateBitCast(Dest.getAddr(),
315 CGF.ConvertType(PtrTy));
316 EmitInitializationToLValue(E->getSubExpr(),
317 CGF.MakeAddrLValue(CastPtr, Ty));
321 case CK_DerivedToBase:
322 case CK_BaseToDerived:
323 case CK_UncheckedDerivedToBase: {
324 llvm_unreachable("cannot perform hierarchy conversion in EmitAggExpr: "
325 "should have been unpacked before we got here");
328 case CK_GetObjCProperty: {
329 LValue LV = CGF.EmitLValue(E->getSubExpr());
330 assert(LV.isPropertyRef());
331 RValue RV = CGF.EmitLoadOfPropertyRefLValue(LV, getReturnValueSlot());
332 EmitMoveFromReturnSlot(E, RV);
336 case CK_LValueToRValue: // hope for downstream optimization
338 case CK_UserDefinedConversion:
339 case CK_ConstructorConversion:
340 assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(),
342 "Implicit cast types must be compatible");
343 Visit(E->getSubExpr());
346 case CK_LValueBitCast:
347 llvm_unreachable("should not be emitting lvalue bitcast as rvalue");
352 case CK_ArrayToPointerDecay:
353 case CK_FunctionToPointerDecay:
354 case CK_NullToPointer:
355 case CK_NullToMemberPointer:
356 case CK_BaseToDerivedMemberPointer:
357 case CK_DerivedToBaseMemberPointer:
358 case CK_MemberPointerToBoolean:
359 case CK_IntegralToPointer:
360 case CK_PointerToIntegral:
361 case CK_PointerToBoolean:
364 case CK_IntegralCast:
365 case CK_IntegralToBoolean:
366 case CK_IntegralToFloating:
367 case CK_FloatingToIntegral:
368 case CK_FloatingToBoolean:
369 case CK_FloatingCast:
370 case CK_CPointerToObjCPointerCast:
371 case CK_BlockPointerToObjCPointerCast:
372 case CK_AnyPointerToBlockPointerCast:
373 case CK_ObjCObjectLValueCast:
374 case CK_FloatingRealToComplex:
375 case CK_FloatingComplexToReal:
376 case CK_FloatingComplexToBoolean:
377 case CK_FloatingComplexCast:
378 case CK_FloatingComplexToIntegralComplex:
379 case CK_IntegralRealToComplex:
380 case CK_IntegralComplexToReal:
381 case CK_IntegralComplexToBoolean:
382 case CK_IntegralComplexCast:
383 case CK_IntegralComplexToFloatingComplex:
384 case CK_ARCProduceObject:
385 case CK_ARCConsumeObject:
386 case CK_ARCReclaimReturnedObject:
387 case CK_ARCExtendBlockObject:
388 llvm_unreachable("cast kind invalid for aggregate types");
392 void AggExprEmitter::VisitCallExpr(const CallExpr *E) {
393 if (E->getCallReturnType()->isReferenceType()) {
394 EmitAggLoadOfLValue(E);
398 RValue RV = CGF.EmitCallExpr(E, getReturnValueSlot());
399 EmitMoveFromReturnSlot(E, RV);
402 void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) {
403 RValue RV = CGF.EmitObjCMessageExpr(E, getReturnValueSlot());
404 EmitMoveFromReturnSlot(E, RV);
407 void AggExprEmitter::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
408 llvm_unreachable("direct property access not surrounded by "
409 "lvalue-to-rvalue cast");
412 void AggExprEmitter::VisitBinComma(const BinaryOperator *E) {
413 CGF.EmitIgnoredExpr(E->getLHS());
417 void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) {
418 CodeGenFunction::StmtExprEvaluation eval(CGF);
419 CGF.EmitCompoundStmt(*E->getSubStmt(), true, Dest);
422 void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) {
423 if (E->getOpcode() == BO_PtrMemD || E->getOpcode() == BO_PtrMemI)
424 VisitPointerToDataMemberBinaryOperator(E);
426 CGF.ErrorUnsupported(E, "aggregate binary expression");
429 void AggExprEmitter::VisitPointerToDataMemberBinaryOperator(
430 const BinaryOperator *E) {
431 LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E);
432 EmitFinalDestCopy(E, LV);
435 void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) {
436 // For an assignment to work, the value on the right has
437 // to be compatible with the value on the left.
438 assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(),
439 E->getRHS()->getType())
440 && "Invalid assignment");
442 if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E->getLHS()))
443 if (const VarDecl *VD = dyn_cast<VarDecl>(DRE->getDecl()))
444 if (VD->hasAttr<BlocksAttr>() &&
445 E->getRHS()->HasSideEffects(CGF.getContext())) {
446 // When __block variable on LHS, the RHS must be evaluated first
447 // as it may change the 'forwarding' field via call to Block_copy.
448 LValue RHS = CGF.EmitLValue(E->getRHS());
449 LValue LHS = CGF.EmitLValue(E->getLHS());
450 Dest = AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
451 needsGC(E->getLHS()->getType()),
452 AggValueSlot::IsAliased);
453 EmitFinalDestCopy(E, RHS, true);
457 LValue LHS = CGF.EmitLValue(E->getLHS());
459 // We have to special case property setters, otherwise we must have
460 // a simple lvalue (no aggregates inside vectors, bitfields).
461 if (LHS.isPropertyRef()) {
462 const ObjCPropertyRefExpr *RE = LHS.getPropertyRefExpr();
463 QualType ArgType = RE->getSetterArgType();
465 if (ArgType->isReferenceType())
466 Src = CGF.EmitReferenceBindingToExpr(E->getRHS(), 0);
468 AggValueSlot Slot = EnsureSlot(E->getRHS()->getType());
469 CGF.EmitAggExpr(E->getRHS(), Slot);
470 Src = Slot.asRValue();
472 CGF.EmitStoreThroughPropertyRefLValue(Src, LHS);
474 // Codegen the RHS so that it stores directly into the LHS.
475 AggValueSlot LHSSlot =
476 AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed,
477 needsGC(E->getLHS()->getType()),
478 AggValueSlot::IsAliased);
479 CGF.EmitAggExpr(E->getRHS(), LHSSlot, false);
480 EmitFinalDestCopy(E, LHS, true);
484 void AggExprEmitter::
485 VisitAbstractConditionalOperator(const AbstractConditionalOperator *E) {
486 llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true");
487 llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false");
488 llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end");
490 // Bind the common expression if necessary.
491 CodeGenFunction::OpaqueValueMapping binding(CGF, E);
493 CodeGenFunction::ConditionalEvaluation eval(CGF);
494 CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock);
496 // Save whether the destination's lifetime is externally managed.
497 bool isExternallyDestructed = Dest.isExternallyDestructed();
500 CGF.EmitBlock(LHSBlock);
501 Visit(E->getTrueExpr());
504 assert(CGF.HaveInsertPoint() && "expression evaluation ended with no IP!");
505 CGF.Builder.CreateBr(ContBlock);
507 // If the result of an agg expression is unused, then the emission
508 // of the LHS might need to create a destination slot. That's fine
509 // with us, and we can safely emit the RHS into the same slot, but
510 // we shouldn't claim that it's already being destructed.
511 Dest.setExternallyDestructed(isExternallyDestructed);
514 CGF.EmitBlock(RHSBlock);
515 Visit(E->getFalseExpr());
518 CGF.EmitBlock(ContBlock);
521 void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) {
522 Visit(CE->getChosenSubExpr(CGF.getContext()));
525 void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) {
526 llvm::Value *ArgValue = CGF.EmitVAListRef(VE->getSubExpr());
527 llvm::Value *ArgPtr = CGF.EmitVAArg(ArgValue, VE->getType());
530 CGF.ErrorUnsupported(VE, "aggregate va_arg expression");
534 EmitFinalDestCopy(VE, CGF.MakeAddrLValue(ArgPtr, VE->getType()));
537 void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
538 // Ensure that we have a slot, but if we already do, remember
539 // whether it was externally destructed.
540 bool wasExternallyDestructed = Dest.isExternallyDestructed();
541 Dest = EnsureSlot(E->getType());
543 // We're going to push a destructor if there isn't already one.
544 Dest.setExternallyDestructed();
546 Visit(E->getSubExpr());
548 // Push that destructor we promised.
549 if (!wasExternallyDestructed)
550 CGF.EmitCXXTemporary(E->getTemporary(), Dest.getAddr());
554 AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) {
555 AggValueSlot Slot = EnsureSlot(E->getType());
556 CGF.EmitCXXConstructExpr(E, Slot);
559 void AggExprEmitter::VisitExprWithCleanups(ExprWithCleanups *E) {
560 CGF.EmitExprWithCleanups(E, Dest);
563 void AggExprEmitter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) {
564 QualType T = E->getType();
565 AggValueSlot Slot = EnsureSlot(T);
566 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddr(), T));
569 void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) {
570 QualType T = E->getType();
571 AggValueSlot Slot = EnsureSlot(T);
572 EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddr(), T));
575 /// isSimpleZero - If emitting this value will obviously just cause a store of
576 /// zero to memory, return true. This can return false if uncertain, so it just
577 /// handles simple cases.
578 static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) {
579 E = E->IgnoreParens();
582 if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E))
583 return IL->getValue() == 0;
585 if (const FloatingLiteral *FL = dyn_cast<FloatingLiteral>(E))
586 return FL->getValue().isPosZero();
588 if ((isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) &&
589 CGF.getTypes().isZeroInitializable(E->getType()))
591 // (int*)0 - Null pointer expressions.
592 if (const CastExpr *ICE = dyn_cast<CastExpr>(E))
593 return ICE->getCastKind() == CK_NullToPointer;
595 if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E))
596 return CL->getValue() == 0;
598 // Otherwise, hard case: conservatively return false.
604 AggExprEmitter::EmitInitializationToLValue(Expr* E, LValue LV) {
605 QualType type = LV.getType();
606 // FIXME: Ignore result?
607 // FIXME: Are initializers affected by volatile?
608 if (Dest.isZeroed() && isSimpleZero(E, CGF)) {
609 // Storing "i32 0" to a zero'd memory location is a noop.
610 } else if (isa<ImplicitValueInitExpr>(E)) {
611 EmitNullInitializationToLValue(LV);
612 } else if (type->isReferenceType()) {
613 RValue RV = CGF.EmitReferenceBindingToExpr(E, /*InitializedDecl=*/0);
614 CGF.EmitStoreThroughLValue(RV, LV);
615 } else if (type->isAnyComplexType()) {
616 CGF.EmitComplexExprIntoAddr(E, LV.getAddress(), false);
617 } else if (CGF.hasAggregateLLVMType(type)) {
618 CGF.EmitAggExpr(E, AggValueSlot::forLValue(LV,
619 AggValueSlot::IsDestructed,
620 AggValueSlot::DoesNotNeedGCBarriers,
621 AggValueSlot::IsNotAliased,
623 } else if (LV.isSimple()) {
624 CGF.EmitScalarInit(E, /*D=*/0, LV, /*Captured=*/false);
626 CGF.EmitStoreThroughLValue(RValue::get(CGF.EmitScalarExpr(E)), LV);
630 void AggExprEmitter::EmitNullInitializationToLValue(LValue lv) {
631 QualType type = lv.getType();
633 // If the destination slot is already zeroed out before the aggregate is
634 // copied into it, we don't have to emit any zeros here.
635 if (Dest.isZeroed() && CGF.getTypes().isZeroInitializable(type))
638 if (!CGF.hasAggregateLLVMType(type)) {
639 // For non-aggregates, we can store zero
640 llvm::Value *null = llvm::Constant::getNullValue(CGF.ConvertType(type));
641 CGF.EmitStoreThroughLValue(RValue::get(null), lv);
643 // There's a potential optimization opportunity in combining
644 // memsets; that would be easy for arrays, but relatively
645 // difficult for structures with the current code.
646 CGF.EmitNullInitialization(lv.getAddress(), lv.getType());
650 void AggExprEmitter::VisitInitListExpr(InitListExpr *E) {
652 // FIXME: Assess perf here? Figure out what cases are worth optimizing here
653 // (Length of globals? Chunks of zeroed-out space?).
655 // If we can, prefer a copy from a global; this is a lot less code for long
656 // globals, and it's easier for the current optimizers to analyze.
657 if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) {
658 llvm::GlobalVariable* GV =
659 new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true,
660 llvm::GlobalValue::InternalLinkage, C, "");
661 EmitFinalDestCopy(E, CGF.MakeAddrLValue(GV, E->getType()));
665 if (E->hadArrayRangeDesignator())
666 CGF.ErrorUnsupported(E, "GNU array range designator extension");
668 llvm::Value *DestPtr = Dest.getAddr();
670 // Handle initialization of an array.
671 if (E->getType()->isArrayType()) {
672 llvm::PointerType *APType =
673 cast<llvm::PointerType>(DestPtr->getType());
674 llvm::ArrayType *AType =
675 cast<llvm::ArrayType>(APType->getElementType());
677 uint64_t NumInitElements = E->getNumInits();
679 if (E->getNumInits() > 0) {
680 QualType T1 = E->getType();
681 QualType T2 = E->getInit(0)->getType();
682 if (CGF.getContext().hasSameUnqualifiedType(T1, T2)) {
683 EmitAggLoadOfLValue(E->getInit(0));
688 uint64_t NumArrayElements = AType->getNumElements();
689 assert(NumInitElements <= NumArrayElements);
691 QualType elementType = E->getType().getCanonicalType();
692 elementType = CGF.getContext().getQualifiedType(
693 cast<ArrayType>(elementType)->getElementType(),
694 elementType.getQualifiers() + Dest.getQualifiers());
696 // DestPtr is an array*. Construct an elementType* by drilling
698 llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0);
699 llvm::Value *indices[] = { zero, zero };
701 Builder.CreateInBoundsGEP(DestPtr, indices, "arrayinit.begin");
703 // Exception safety requires us to destroy all the
704 // already-constructed members if an initializer throws.
705 // For that, we'll need an EH cleanup.
706 QualType::DestructionKind dtorKind = elementType.isDestructedType();
707 llvm::AllocaInst *endOfInit = 0;
708 EHScopeStack::stable_iterator cleanup;
709 if (CGF.needsEHCleanup(dtorKind)) {
710 // In principle we could tell the cleanup where we are more
711 // directly, but the control flow can get so varied here that it
712 // would actually be quite complex. Therefore we go through an
714 endOfInit = CGF.CreateTempAlloca(begin->getType(),
715 "arrayinit.endOfInit");
716 Builder.CreateStore(begin, endOfInit);
717 CGF.pushIrregularPartialArrayCleanup(begin, endOfInit, elementType,
718 CGF.getDestroyer(dtorKind));
719 cleanup = CGF.EHStack.stable_begin();
721 // Otherwise, remember that we didn't need a cleanup.
723 dtorKind = QualType::DK_none;
726 llvm::Value *one = llvm::ConstantInt::get(CGF.SizeTy, 1);
728 // The 'current element to initialize'. The invariants on this
729 // variable are complicated. Essentially, after each iteration of
730 // the loop, it points to the last initialized element, except
731 // that it points to the beginning of the array before any
732 // elements have been initialized.
733 llvm::Value *element = begin;
735 // Emit the explicit initializers.
736 for (uint64_t i = 0; i != NumInitElements; ++i) {
737 // Advance to the next element.
739 element = Builder.CreateInBoundsGEP(element, one, "arrayinit.element");
741 // Tell the cleanup that it needs to destroy up to this
742 // element. TODO: some of these stores can be trivially
743 // observed to be unnecessary.
744 if (endOfInit) Builder.CreateStore(element, endOfInit);
747 LValue elementLV = CGF.MakeAddrLValue(element, elementType);
748 EmitInitializationToLValue(E->getInit(i), elementLV);
751 // Check whether there's a non-trivial array-fill expression.
752 // Note that this will be a CXXConstructExpr even if the element
753 // type is an array (or array of array, etc.) of class type.
754 Expr *filler = E->getArrayFiller();
755 bool hasTrivialFiller = true;
756 if (CXXConstructExpr *cons = dyn_cast_or_null<CXXConstructExpr>(filler)) {
757 assert(cons->getConstructor()->isDefaultConstructor());
758 hasTrivialFiller = cons->getConstructor()->isTrivial();
761 // Any remaining elements need to be zero-initialized, possibly
762 // using the filler expression. We can skip this if the we're
763 // emitting to zeroed memory.
764 if (NumInitElements != NumArrayElements &&
765 !(Dest.isZeroed() && hasTrivialFiller &&
766 CGF.getTypes().isZeroInitializable(elementType))) {
768 // Use an actual loop. This is basically
769 // do { *array++ = filler; } while (array != end);
771 // Advance to the start of the rest of the array.
772 if (NumInitElements) {
773 element = Builder.CreateInBoundsGEP(element, one, "arrayinit.start");
774 if (endOfInit) Builder.CreateStore(element, endOfInit);
777 // Compute the end of the array.
778 llvm::Value *end = Builder.CreateInBoundsGEP(begin,
779 llvm::ConstantInt::get(CGF.SizeTy, NumArrayElements),
782 llvm::BasicBlock *entryBB = Builder.GetInsertBlock();
783 llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body");
785 // Jump into the body.
786 CGF.EmitBlock(bodyBB);
787 llvm::PHINode *currentElement =
788 Builder.CreatePHI(element->getType(), 2, "arrayinit.cur");
789 currentElement->addIncoming(element, entryBB);
791 // Emit the actual filler expression.
792 LValue elementLV = CGF.MakeAddrLValue(currentElement, elementType);
794 EmitInitializationToLValue(filler, elementLV);
796 EmitNullInitializationToLValue(elementLV);
798 // Move on to the next element.
799 llvm::Value *nextElement =
800 Builder.CreateInBoundsGEP(currentElement, one, "arrayinit.next");
802 // Tell the EH cleanup that we finished with the last element.
803 if (endOfInit) Builder.CreateStore(nextElement, endOfInit);
805 // Leave the loop if we're done.
806 llvm::Value *done = Builder.CreateICmpEQ(nextElement, end,
808 llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end");
809 Builder.CreateCondBr(done, endBB, bodyBB);
810 currentElement->addIncoming(nextElement, Builder.GetInsertBlock());
812 CGF.EmitBlock(endBB);
815 // Leave the partial-array cleanup if we entered one.
816 if (dtorKind) CGF.DeactivateCleanupBlock(cleanup);
821 assert(E->getType()->isRecordType() && "Only support structs/unions here!");
823 // Do struct initialization; this code just sets each individual member
824 // to the approprate value. This makes bitfield support automatic;
825 // the disadvantage is that the generated code is more difficult for
826 // the optimizer, especially with bitfields.
827 unsigned NumInitElements = E->getNumInits();
828 RecordDecl *record = E->getType()->castAs<RecordType>()->getDecl();
830 if (record->isUnion()) {
831 // Only initialize one field of a union. The field itself is
832 // specified by the initializer list.
833 if (!E->getInitializedFieldInUnion()) {
834 // Empty union; we have nothing to do.
837 // Make sure that it's really an empty and not a failure of
838 // semantic analysis.
839 for (RecordDecl::field_iterator Field = record->field_begin(),
840 FieldEnd = record->field_end();
841 Field != FieldEnd; ++Field)
842 assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed");
848 FieldDecl *Field = E->getInitializedFieldInUnion();
850 LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestPtr, Field, 0);
851 if (NumInitElements) {
852 // Store the initializer into the field
853 EmitInitializationToLValue(E->getInit(0), FieldLoc);
855 // Default-initialize to null.
856 EmitNullInitializationToLValue(FieldLoc);
862 // We'll need to enter cleanup scopes in case any of the member
863 // initializers throw an exception.
864 SmallVector<EHScopeStack::stable_iterator, 16> cleanups;
866 // Here we iterate over the fields; this makes it simpler to both
867 // default-initialize fields and skip over unnamed fields.
868 unsigned curInitIndex = 0;
869 for (RecordDecl::field_iterator field = record->field_begin(),
870 fieldEnd = record->field_end();
871 field != fieldEnd; ++field) {
872 // We're done once we hit the flexible array member.
873 if (field->getType()->isIncompleteArrayType())
876 // Always skip anonymous bitfields.
877 if (field->isUnnamedBitfield())
880 // We're done if we reach the end of the explicit initializers, we
881 // have a zeroed object, and the rest of the fields are
882 // zero-initializable.
883 if (curInitIndex == NumInitElements && Dest.isZeroed() &&
884 CGF.getTypes().isZeroInitializable(E->getType()))
888 LValue LV = CGF.EmitLValueForFieldInitialization(DestPtr, *field, 0);
889 // We never generate write-barries for initialized fields.
892 if (curInitIndex < NumInitElements) {
893 // Store the initializer into the field.
894 EmitInitializationToLValue(E->getInit(curInitIndex++), LV);
896 // We're out of initalizers; default-initialize to null
897 EmitNullInitializationToLValue(LV);
900 // Push a destructor if necessary.
901 // FIXME: if we have an array of structures, all explicitly
902 // initialized, we can end up pushing a linear number of cleanups.
903 bool pushedCleanup = false;
904 if (QualType::DestructionKind dtorKind
905 = field->getType().isDestructedType()) {
906 assert(LV.isSimple());
907 if (CGF.needsEHCleanup(dtorKind)) {
908 CGF.pushDestroy(EHCleanup, LV.getAddress(), field->getType(),
909 CGF.getDestroyer(dtorKind), false);
910 cleanups.push_back(CGF.EHStack.stable_begin());
911 pushedCleanup = true;
915 // If the GEP didn't get used because of a dead zero init or something
916 // else, clean it up for -O0 builds and general tidiness.
917 if (!pushedCleanup && LV.isSimple())
918 if (llvm::GetElementPtrInst *GEP =
919 dyn_cast<llvm::GetElementPtrInst>(LV.getAddress()))
920 if (GEP->use_empty())
921 GEP->eraseFromParent();
924 // Deactivate all the partial cleanups in reverse order, which
925 // generally means popping them.
926 for (unsigned i = cleanups.size(); i != 0; --i)
927 CGF.DeactivateCleanupBlock(cleanups[i-1]);
930 //===----------------------------------------------------------------------===//
931 // Entry Points into this File
932 //===----------------------------------------------------------------------===//
934 /// GetNumNonZeroBytesInInit - Get an approximate count of the number of
935 /// non-zero bytes that will be stored when outputting the initializer for the
936 /// specified initializer expression.
937 static CharUnits GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) {
938 E = E->IgnoreParens();
940 // 0 and 0.0 won't require any non-zero stores!
941 if (isSimpleZero(E, CGF)) return CharUnits::Zero();
943 // If this is an initlist expr, sum up the size of sizes of the (present)
944 // elements. If this is something weird, assume the whole thing is non-zero.
945 const InitListExpr *ILE = dyn_cast<InitListExpr>(E);
946 if (ILE == 0 || !CGF.getTypes().isZeroInitializable(ILE->getType()))
947 return CGF.getContext().getTypeSizeInChars(E->getType());
949 // InitListExprs for structs have to be handled carefully. If there are
950 // reference members, we need to consider the size of the reference, not the
951 // referencee. InitListExprs for unions and arrays can't have references.
952 if (const RecordType *RT = E->getType()->getAs<RecordType>()) {
953 if (!RT->isUnionType()) {
954 RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl();
955 CharUnits NumNonZeroBytes = CharUnits::Zero();
957 unsigned ILEElement = 0;
958 for (RecordDecl::field_iterator Field = SD->field_begin(),
959 FieldEnd = SD->field_end(); Field != FieldEnd; ++Field) {
960 // We're done once we hit the flexible array member or run out of
961 // InitListExpr elements.
962 if (Field->getType()->isIncompleteArrayType() ||
963 ILEElement == ILE->getNumInits())
965 if (Field->isUnnamedBitfield())
968 const Expr *E = ILE->getInit(ILEElement++);
970 // Reference values are always non-null and have the width of a pointer.
971 if (Field->getType()->isReferenceType())
972 NumNonZeroBytes += CGF.getContext().toCharUnitsFromBits(
973 CGF.getContext().getTargetInfo().getPointerWidth(0));
975 NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF);
978 return NumNonZeroBytes;
983 CharUnits NumNonZeroBytes = CharUnits::Zero();
984 for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i)
985 NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF);
986 return NumNonZeroBytes;
989 /// CheckAggExprForMemSetUse - If the initializer is large and has a lot of
990 /// zeros in it, emit a memset and avoid storing the individual zeros.
992 static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E,
993 CodeGenFunction &CGF) {
994 // If the slot is already known to be zeroed, nothing to do. Don't mess with
996 if (Slot.isZeroed() || Slot.isVolatile() || Slot.getAddr() == 0) return;
998 // C++ objects with a user-declared constructor don't need zero'ing.
999 if (CGF.getContext().getLangOptions().CPlusPlus)
1000 if (const RecordType *RT = CGF.getContext()
1001 .getBaseElementType(E->getType())->getAs<RecordType>()) {
1002 const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl());
1003 if (RD->hasUserDeclaredConstructor())
1007 // If the type is 16-bytes or smaller, prefer individual stores over memset.
1008 std::pair<CharUnits, CharUnits> TypeInfo =
1009 CGF.getContext().getTypeInfoInChars(E->getType());
1010 if (TypeInfo.first <= CharUnits::fromQuantity(16))
1013 // Check to see if over 3/4 of the initializer are known to be zero. If so,
1014 // we prefer to emit memset + individual stores for the rest.
1015 CharUnits NumNonZeroBytes = GetNumNonZeroBytesInInit(E, CGF);
1016 if (NumNonZeroBytes*4 > TypeInfo.first)
1019 // Okay, it seems like a good idea to use an initial memset, emit the call.
1020 llvm::Constant *SizeVal = CGF.Builder.getInt64(TypeInfo.first.getQuantity());
1021 CharUnits Align = TypeInfo.second;
1023 llvm::Value *Loc = Slot.getAddr();
1024 llvm::Type *BP = llvm::Type::getInt8PtrTy(CGF.getLLVMContext());
1026 Loc = CGF.Builder.CreateBitCast(Loc, BP);
1027 CGF.Builder.CreateMemSet(Loc, CGF.Builder.getInt8(0), SizeVal,
1028 Align.getQuantity(), false);
1030 // Tell the AggExprEmitter that the slot is known zero.
1037 /// EmitAggExpr - Emit the computation of the specified expression of aggregate
1038 /// type. The result is computed into DestPtr. Note that if DestPtr is null,
1039 /// the value of the aggregate expression is not needed. If VolatileDest is
1040 /// true, DestPtr cannot be 0.
1042 /// \param IsInitializer - true if this evaluation is initializing an
1043 /// object whose lifetime is already being managed.
1044 void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot,
1045 bool IgnoreResult) {
1046 assert(E && hasAggregateLLVMType(E->getType()) &&
1047 "Invalid aggregate expression to emit");
1048 assert((Slot.getAddr() != 0 || Slot.isIgnored()) &&
1049 "slot has bits but no address");
1051 // Optimize the slot if possible.
1052 CheckAggExprForMemSetUse(Slot, E, *this);
1054 AggExprEmitter(*this, Slot, IgnoreResult).Visit(const_cast<Expr*>(E));
1057 LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) {
1058 assert(hasAggregateLLVMType(E->getType()) && "Invalid argument!");
1059 llvm::Value *Temp = CreateMemTemp(E->getType());
1060 LValue LV = MakeAddrLValue(Temp, E->getType());
1061 EmitAggExpr(E, AggValueSlot::forLValue(LV, AggValueSlot::IsNotDestructed,
1062 AggValueSlot::DoesNotNeedGCBarriers,
1063 AggValueSlot::IsNotAliased));
1067 void CodeGenFunction::EmitAggregateCopy(llvm::Value *DestPtr,
1068 llvm::Value *SrcPtr, QualType Ty,
1070 assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex");
1072 if (getContext().getLangOptions().CPlusPlus) {
1073 if (const RecordType *RT = Ty->getAs<RecordType>()) {
1074 CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl());
1075 assert((Record->hasTrivialCopyConstructor() ||
1076 Record->hasTrivialCopyAssignment() ||
1077 Record->hasTrivialMoveConstructor() ||
1078 Record->hasTrivialMoveAssignment()) &&
1079 "Trying to aggregate-copy a type without a trivial copy "
1080 "constructor or assignment operator");
1081 // Ignore empty classes in C++.
1082 if (Record->isEmpty())
1087 // Aggregate assignment turns into llvm.memcpy. This is almost valid per
1088 // C99 6.5.16.1p3, which states "If the value being stored in an object is
1089 // read from another object that overlaps in anyway the storage of the first
1090 // object, then the overlap shall be exact and the two objects shall have
1091 // qualified or unqualified versions of a compatible type."
1093 // memcpy is not defined if the source and destination pointers are exactly
1094 // equal, but other compilers do this optimization, and almost every memcpy
1095 // implementation handles this case safely. If there is a libc that does not
1096 // safely handle this, we can add a target hook.
1098 // Get size and alignment info for this aggregate.
1099 std::pair<CharUnits, CharUnits> TypeInfo =
1100 getContext().getTypeInfoInChars(Ty);
1102 // FIXME: Handle variable sized types.
1104 // FIXME: If we have a volatile struct, the optimizer can remove what might
1105 // appear to be `extra' memory ops:
1107 // volatile struct { int i; } a, b;
1114 // we need to use a different call here. We use isVolatile to indicate when
1115 // either the source or the destination is volatile.
1117 llvm::PointerType *DPT = cast<llvm::PointerType>(DestPtr->getType());
1119 llvm::Type::getInt8PtrTy(getLLVMContext(), DPT->getAddressSpace());
1120 DestPtr = Builder.CreateBitCast(DestPtr, DBP);
1122 llvm::PointerType *SPT = cast<llvm::PointerType>(SrcPtr->getType());
1124 llvm::Type::getInt8PtrTy(getLLVMContext(), SPT->getAddressSpace());
1125 SrcPtr = Builder.CreateBitCast(SrcPtr, SBP);
1127 // Don't do any of the memmove_collectable tests if GC isn't set.
1128 if (CGM.getLangOptions().getGC() == LangOptions::NonGC) {
1130 } else if (const RecordType *RecordTy = Ty->getAs<RecordType>()) {
1131 RecordDecl *Record = RecordTy->getDecl();
1132 if (Record->hasObjectMember()) {
1133 CharUnits size = TypeInfo.first;
1134 llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
1135 llvm::Value *SizeVal = llvm::ConstantInt::get(SizeTy, size.getQuantity());
1136 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1140 } else if (Ty->isArrayType()) {
1141 QualType BaseType = getContext().getBaseElementType(Ty);
1142 if (const RecordType *RecordTy = BaseType->getAs<RecordType>()) {
1143 if (RecordTy->getDecl()->hasObjectMember()) {
1144 CharUnits size = TypeInfo.first;
1145 llvm::Type *SizeTy = ConvertType(getContext().getSizeType());
1146 llvm::Value *SizeVal =
1147 llvm::ConstantInt::get(SizeTy, size.getQuantity());
1148 CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr,
1155 Builder.CreateMemCpy(DestPtr, SrcPtr,
1156 llvm::ConstantInt::get(IntPtrTy,
1157 TypeInfo.first.getQuantity()),
1158 TypeInfo.second.getQuantity(), isVolatile);