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Diffstat (limited to 'contrib/llvm-project/clang/lib/CodeGen/CGExprAgg.cpp')
| -rw-r--r-- | contrib/llvm-project/clang/lib/CodeGen/CGExprAgg.cpp | 2023 |
1 files changed, 2023 insertions, 0 deletions
diff --git a/contrib/llvm-project/clang/lib/CodeGen/CGExprAgg.cpp b/contrib/llvm-project/clang/lib/CodeGen/CGExprAgg.cpp new file mode 100644 index 000000000000..0a57870a7c58 --- /dev/null +++ b/contrib/llvm-project/clang/lib/CodeGen/CGExprAgg.cpp @@ -0,0 +1,2023 @@ +//===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate Expressions --------===// +// +// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. +// See https://llvm.org/LICENSE.txt for license information. +// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception +// +//===----------------------------------------------------------------------===// +// +// This contains code to emit Aggregate Expr nodes as LLVM code. +// +//===----------------------------------------------------------------------===// + +#include "CodeGenFunction.h" +#include "CGCXXABI.h" +#include "CGObjCRuntime.h" +#include "CodeGenModule.h" +#include "ConstantEmitter.h" +#include "clang/AST/ASTContext.h" +#include "clang/AST/DeclCXX.h" +#include "clang/AST/DeclTemplate.h" +#include "clang/AST/StmtVisitor.h" +#include "llvm/IR/Constants.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/GlobalVariable.h" +#include "llvm/IR/Intrinsics.h" +#include "llvm/IR/IntrinsicInst.h" +using namespace clang; +using namespace CodeGen; + +//===----------------------------------------------------------------------===// +// Aggregate Expression Emitter +//===----------------------------------------------------------------------===// + +namespace { +class AggExprEmitter : public StmtVisitor<AggExprEmitter> { + CodeGenFunction &CGF; + CGBuilderTy &Builder; + AggValueSlot Dest; + bool IsResultUnused; + + AggValueSlot EnsureSlot(QualType T) { + if (!Dest.isIgnored()) return Dest; + return CGF.CreateAggTemp(T, "agg.tmp.ensured"); + } + void EnsureDest(QualType T) { + if (!Dest.isIgnored()) return; + Dest = CGF.CreateAggTemp(T, "agg.tmp.ensured"); + } + + // Calls `Fn` with a valid return value slot, potentially creating a temporary + // to do so. If a temporary is created, an appropriate copy into `Dest` will + // be emitted, as will lifetime markers. + // + // The given function should take a ReturnValueSlot, and return an RValue that + // points to said slot. + void withReturnValueSlot(const Expr *E, + llvm::function_ref<RValue(ReturnValueSlot)> Fn); + +public: + AggExprEmitter(CodeGenFunction &cgf, AggValueSlot Dest, bool IsResultUnused) + : CGF(cgf), Builder(CGF.Builder), Dest(Dest), + IsResultUnused(IsResultUnused) { } + + //===--------------------------------------------------------------------===// + // Utilities + //===--------------------------------------------------------------------===// + + /// EmitAggLoadOfLValue - Given an expression with aggregate type that + /// represents a value lvalue, this method emits the address of the lvalue, + /// then loads the result into DestPtr. + void EmitAggLoadOfLValue(const Expr *E); + + enum ExprValueKind { + EVK_RValue, + EVK_NonRValue + }; + + /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. + /// SrcIsRValue is true if source comes from an RValue. + void EmitFinalDestCopy(QualType type, const LValue &src, + ExprValueKind SrcValueKind = EVK_NonRValue); + void EmitFinalDestCopy(QualType type, RValue src); + void EmitCopy(QualType type, const AggValueSlot &dest, + const AggValueSlot &src); + + void EmitMoveFromReturnSlot(const Expr *E, RValue Src); + + void EmitArrayInit(Address DestPtr, llvm::ArrayType *AType, + QualType ArrayQTy, InitListExpr *E); + + AggValueSlot::NeedsGCBarriers_t needsGC(QualType T) { + if (CGF.getLangOpts().getGC() && TypeRequiresGCollection(T)) + return AggValueSlot::NeedsGCBarriers; + return AggValueSlot::DoesNotNeedGCBarriers; + } + + bool TypeRequiresGCollection(QualType T); + + //===--------------------------------------------------------------------===// + // Visitor Methods + //===--------------------------------------------------------------------===// + + void Visit(Expr *E) { + ApplyDebugLocation DL(CGF, E); + StmtVisitor<AggExprEmitter>::Visit(E); + } + + void VisitStmt(Stmt *S) { + CGF.ErrorUnsupported(S, "aggregate expression"); + } + void VisitParenExpr(ParenExpr *PE) { Visit(PE->getSubExpr()); } + void VisitGenericSelectionExpr(GenericSelectionExpr *GE) { + Visit(GE->getResultExpr()); + } + void VisitCoawaitExpr(CoawaitExpr *E) { + CGF.EmitCoawaitExpr(*E, Dest, IsResultUnused); + } + void VisitCoyieldExpr(CoyieldExpr *E) { + CGF.EmitCoyieldExpr(*E, Dest, IsResultUnused); + } + void VisitUnaryCoawait(UnaryOperator *E) { Visit(E->getSubExpr()); } + void VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); } + void VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) { + return Visit(E->getReplacement()); + } + + void VisitConstantExpr(ConstantExpr *E) { + return Visit(E->getSubExpr()); + } + + // l-values. + void VisitDeclRefExpr(DeclRefExpr *E) { EmitAggLoadOfLValue(E); } + void VisitMemberExpr(MemberExpr *ME) { EmitAggLoadOfLValue(ME); } + void VisitUnaryDeref(UnaryOperator *E) { EmitAggLoadOfLValue(E); } + void VisitStringLiteral(StringLiteral *E) { EmitAggLoadOfLValue(E); } + void VisitCompoundLiteralExpr(CompoundLiteralExpr *E); + void VisitArraySubscriptExpr(ArraySubscriptExpr *E) { + EmitAggLoadOfLValue(E); + } + void VisitPredefinedExpr(const PredefinedExpr *E) { + EmitAggLoadOfLValue(E); + } + + // Operators. + void VisitCastExpr(CastExpr *E); + void VisitCallExpr(const CallExpr *E); + void VisitStmtExpr(const StmtExpr *E); + void VisitBinaryOperator(const BinaryOperator *BO); + void VisitPointerToDataMemberBinaryOperator(const BinaryOperator *BO); + void VisitBinAssign(const BinaryOperator *E); + void VisitBinComma(const BinaryOperator *E); + void VisitBinCmp(const BinaryOperator *E); + + void VisitObjCMessageExpr(ObjCMessageExpr *E); + void VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) { + EmitAggLoadOfLValue(E); + } + + void VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E); + void VisitAbstractConditionalOperator(const AbstractConditionalOperator *CO); + void VisitChooseExpr(const ChooseExpr *CE); + void VisitInitListExpr(InitListExpr *E); + void VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E, + llvm::Value *outerBegin = nullptr); + void VisitImplicitValueInitExpr(ImplicitValueInitExpr *E); + void VisitNoInitExpr(NoInitExpr *E) { } // Do nothing. + void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { + CodeGenFunction::CXXDefaultArgExprScope Scope(CGF, DAE); + Visit(DAE->getExpr()); + } + void VisitCXXDefaultInitExpr(CXXDefaultInitExpr *DIE) { + CodeGenFunction::CXXDefaultInitExprScope Scope(CGF, DIE); + Visit(DIE->getExpr()); + } + void VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E); + void VisitCXXConstructExpr(const CXXConstructExpr *E); + void VisitCXXInheritedCtorInitExpr(const CXXInheritedCtorInitExpr *E); + void VisitLambdaExpr(LambdaExpr *E); + void VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E); + void VisitExprWithCleanups(ExprWithCleanups *E); + void VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E); + void VisitCXXTypeidExpr(CXXTypeidExpr *E) { EmitAggLoadOfLValue(E); } + void VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E); + void VisitOpaqueValueExpr(OpaqueValueExpr *E); + + void VisitPseudoObjectExpr(PseudoObjectExpr *E) { + if (E->isGLValue()) { + LValue LV = CGF.EmitPseudoObjectLValue(E); + return EmitFinalDestCopy(E->getType(), LV); + } + + CGF.EmitPseudoObjectRValue(E, EnsureSlot(E->getType())); + } + + void VisitVAArgExpr(VAArgExpr *E); + + void EmitInitializationToLValue(Expr *E, LValue Address); + void EmitNullInitializationToLValue(LValue Address); + // case Expr::ChooseExprClass: + void VisitCXXThrowExpr(const CXXThrowExpr *E) { CGF.EmitCXXThrowExpr(E); } + void VisitAtomicExpr(AtomicExpr *E) { + RValue Res = CGF.EmitAtomicExpr(E); + EmitFinalDestCopy(E->getType(), Res); + } +}; +} // end anonymous namespace. + +//===----------------------------------------------------------------------===// +// Utilities +//===----------------------------------------------------------------------===// + +/// EmitAggLoadOfLValue - Given an expression with aggregate type that +/// represents a value lvalue, this method emits the address of the lvalue, +/// then loads the result into DestPtr. +void AggExprEmitter::EmitAggLoadOfLValue(const Expr *E) { + LValue LV = CGF.EmitLValue(E); + + // If the type of the l-value is atomic, then do an atomic load. + if (LV.getType()->isAtomicType() || CGF.LValueIsSuitableForInlineAtomic(LV)) { + CGF.EmitAtomicLoad(LV, E->getExprLoc(), Dest); + return; + } + + EmitFinalDestCopy(E->getType(), LV); +} + +/// True if the given aggregate type requires special GC API calls. +bool AggExprEmitter::TypeRequiresGCollection(QualType T) { + // Only record types have members that might require garbage collection. + const RecordType *RecordTy = T->getAs<RecordType>(); + if (!RecordTy) return false; + + // Don't mess with non-trivial C++ types. + RecordDecl *Record = RecordTy->getDecl(); + if (isa<CXXRecordDecl>(Record) && + (cast<CXXRecordDecl>(Record)->hasNonTrivialCopyConstructor() || + !cast<CXXRecordDecl>(Record)->hasTrivialDestructor())) + return false; + + // Check whether the type has an object member. + return Record->hasObjectMember(); +} + +void AggExprEmitter::withReturnValueSlot( + const Expr *E, llvm::function_ref<RValue(ReturnValueSlot)> EmitCall) { + QualType RetTy = E->getType(); + bool RequiresDestruction = + Dest.isIgnored() && + RetTy.isDestructedType() == QualType::DK_nontrivial_c_struct; + + // If it makes no observable difference, save a memcpy + temporary. + // + // We need to always provide our own temporary if destruction is required. + // Otherwise, EmitCall will emit its own, notice that it's "unused", and end + // its lifetime before we have the chance to emit a proper destructor call. + bool UseTemp = Dest.isPotentiallyAliased() || Dest.requiresGCollection() || + (RequiresDestruction && !Dest.getAddress().isValid()); + + Address RetAddr = Address::invalid(); + Address RetAllocaAddr = Address::invalid(); + + EHScopeStack::stable_iterator LifetimeEndBlock; + llvm::Value *LifetimeSizePtr = nullptr; + llvm::IntrinsicInst *LifetimeStartInst = nullptr; + if (!UseTemp) { + RetAddr = Dest.getAddress(); + } else { + RetAddr = CGF.CreateMemTemp(RetTy, "tmp", &RetAllocaAddr); + uint64_t Size = + CGF.CGM.getDataLayout().getTypeAllocSize(CGF.ConvertTypeForMem(RetTy)); + LifetimeSizePtr = CGF.EmitLifetimeStart(Size, RetAllocaAddr.getPointer()); + if (LifetimeSizePtr) { + LifetimeStartInst = + cast<llvm::IntrinsicInst>(std::prev(Builder.GetInsertPoint())); + assert(LifetimeStartInst->getIntrinsicID() == + llvm::Intrinsic::lifetime_start && + "Last insertion wasn't a lifetime.start?"); + + CGF.pushFullExprCleanup<CodeGenFunction::CallLifetimeEnd>( + NormalEHLifetimeMarker, RetAllocaAddr, LifetimeSizePtr); + LifetimeEndBlock = CGF.EHStack.stable_begin(); + } + } + + RValue Src = + EmitCall(ReturnValueSlot(RetAddr, Dest.isVolatile(), IsResultUnused)); + + if (RequiresDestruction) + CGF.pushDestroy(RetTy.isDestructedType(), Src.getAggregateAddress(), RetTy); + + if (!UseTemp) + return; + + assert(Dest.getPointer() != Src.getAggregatePointer()); + EmitFinalDestCopy(E->getType(), Src); + + if (!RequiresDestruction && LifetimeStartInst) { + // If there's no dtor to run, the copy was the last use of our temporary. + // Since we're not guaranteed to be in an ExprWithCleanups, clean up + // eagerly. + CGF.DeactivateCleanupBlock(LifetimeEndBlock, LifetimeStartInst); + CGF.EmitLifetimeEnd(LifetimeSizePtr, RetAllocaAddr.getPointer()); + } +} + +/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. +void AggExprEmitter::EmitFinalDestCopy(QualType type, RValue src) { + assert(src.isAggregate() && "value must be aggregate value!"); + LValue srcLV = CGF.MakeAddrLValue(src.getAggregateAddress(), type); + EmitFinalDestCopy(type, srcLV, EVK_RValue); +} + +/// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. +void AggExprEmitter::EmitFinalDestCopy(QualType type, const LValue &src, + ExprValueKind SrcValueKind) { + // If Dest is ignored, then we're evaluating an aggregate expression + // in a context that doesn't care about the result. Note that loads + // from volatile l-values force the existence of a non-ignored + // destination. + if (Dest.isIgnored()) + return; + + // Copy non-trivial C structs here. + LValue DstLV = CGF.MakeAddrLValue( + Dest.getAddress(), Dest.isVolatile() ? type.withVolatile() : type); + + if (SrcValueKind == EVK_RValue) { + if (type.isNonTrivialToPrimitiveDestructiveMove() == QualType::PCK_Struct) { + if (Dest.isPotentiallyAliased()) + CGF.callCStructMoveAssignmentOperator(DstLV, src); + else + CGF.callCStructMoveConstructor(DstLV, src); + return; + } + } else { + if (type.isNonTrivialToPrimitiveCopy() == QualType::PCK_Struct) { + if (Dest.isPotentiallyAliased()) + CGF.callCStructCopyAssignmentOperator(DstLV, src); + else + CGF.callCStructCopyConstructor(DstLV, src); + return; + } + } + + AggValueSlot srcAgg = + AggValueSlot::forLValue(src, AggValueSlot::IsDestructed, + needsGC(type), AggValueSlot::IsAliased, + AggValueSlot::MayOverlap); + EmitCopy(type, Dest, srcAgg); +} + +/// Perform a copy from the source into the destination. +/// +/// \param type - the type of the aggregate being copied; qualifiers are +/// ignored +void AggExprEmitter::EmitCopy(QualType type, const AggValueSlot &dest, + const AggValueSlot &src) { + if (dest.requiresGCollection()) { + CharUnits sz = dest.getPreferredSize(CGF.getContext(), type); + llvm::Value *size = llvm::ConstantInt::get(CGF.SizeTy, sz.getQuantity()); + CGF.CGM.getObjCRuntime().EmitGCMemmoveCollectable(CGF, + dest.getAddress(), + src.getAddress(), + size); + return; + } + + // If the result of the assignment is used, copy the LHS there also. + // It's volatile if either side is. Use the minimum alignment of + // the two sides. + LValue DestLV = CGF.MakeAddrLValue(dest.getAddress(), type); + LValue SrcLV = CGF.MakeAddrLValue(src.getAddress(), type); + CGF.EmitAggregateCopy(DestLV, SrcLV, type, dest.mayOverlap(), + dest.isVolatile() || src.isVolatile()); +} + +/// Emit the initializer for a std::initializer_list initialized with a +/// real initializer list. +void +AggExprEmitter::VisitCXXStdInitializerListExpr(CXXStdInitializerListExpr *E) { + // Emit an array containing the elements. The array is externally destructed + // if the std::initializer_list object is. + ASTContext &Ctx = CGF.getContext(); + LValue Array = CGF.EmitLValue(E->getSubExpr()); + assert(Array.isSimple() && "initializer_list array not a simple lvalue"); + Address ArrayPtr = Array.getAddress(); + + const ConstantArrayType *ArrayType = + Ctx.getAsConstantArrayType(E->getSubExpr()->getType()); + assert(ArrayType && "std::initializer_list constructed from non-array"); + + // FIXME: Perform the checks on the field types in SemaInit. + RecordDecl *Record = E->getType()->castAs<RecordType>()->getDecl(); + RecordDecl::field_iterator Field = Record->field_begin(); + if (Field == Record->field_end()) { + CGF.ErrorUnsupported(E, "weird std::initializer_list"); + return; + } + + // Start pointer. + if (!Field->getType()->isPointerType() || + !Ctx.hasSameType(Field->getType()->getPointeeType(), + ArrayType->getElementType())) { + CGF.ErrorUnsupported(E, "weird std::initializer_list"); + return; + } + + AggValueSlot Dest = EnsureSlot(E->getType()); + LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType()); + LValue Start = CGF.EmitLValueForFieldInitialization(DestLV, *Field); + llvm::Value *Zero = llvm::ConstantInt::get(CGF.PtrDiffTy, 0); + llvm::Value *IdxStart[] = { Zero, Zero }; + llvm::Value *ArrayStart = + Builder.CreateInBoundsGEP(ArrayPtr.getPointer(), IdxStart, "arraystart"); + CGF.EmitStoreThroughLValue(RValue::get(ArrayStart), Start); + ++Field; + + if (Field == Record->field_end()) { + CGF.ErrorUnsupported(E, "weird std::initializer_list"); + return; + } + + llvm::Value *Size = Builder.getInt(ArrayType->getSize()); + LValue EndOrLength = CGF.EmitLValueForFieldInitialization(DestLV, *Field); + if (Field->getType()->isPointerType() && + Ctx.hasSameType(Field->getType()->getPointeeType(), + ArrayType->getElementType())) { + // End pointer. + llvm::Value *IdxEnd[] = { Zero, Size }; + llvm::Value *ArrayEnd = + Builder.CreateInBoundsGEP(ArrayPtr.getPointer(), IdxEnd, "arrayend"); + CGF.EmitStoreThroughLValue(RValue::get(ArrayEnd), EndOrLength); + } else if (Ctx.hasSameType(Field->getType(), Ctx.getSizeType())) { + // Length. + CGF.EmitStoreThroughLValue(RValue::get(Size), EndOrLength); + } else { + CGF.ErrorUnsupported(E, "weird std::initializer_list"); + return; + } +} + +/// Determine if E is a trivial array filler, that is, one that is +/// equivalent to zero-initialization. +static bool isTrivialFiller(Expr *E) { + if (!E) + return true; + + if (isa<ImplicitValueInitExpr>(E)) + return true; + + if (auto *ILE = dyn_cast<InitListExpr>(E)) { + if (ILE->getNumInits()) + return false; + return isTrivialFiller(ILE->getArrayFiller()); + } + + if (auto *Cons = dyn_cast_or_null<CXXConstructExpr>(E)) + return Cons->getConstructor()->isDefaultConstructor() && + Cons->getConstructor()->isTrivial(); + + // FIXME: Are there other cases where we can avoid emitting an initializer? + return false; +} + +/// Emit initialization of an array from an initializer list. +void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType, + QualType ArrayQTy, InitListExpr *E) { + uint64_t NumInitElements = E->getNumInits(); + + uint64_t NumArrayElements = AType->getNumElements(); + assert(NumInitElements <= NumArrayElements); + + QualType elementType = + CGF.getContext().getAsArrayType(ArrayQTy)->getElementType(); + + // DestPtr is an array*. Construct an elementType* by drilling + // down a level. + llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0); + llvm::Value *indices[] = { zero, zero }; + llvm::Value *begin = + Builder.CreateInBoundsGEP(DestPtr.getPointer(), indices, "arrayinit.begin"); + + CharUnits elementSize = CGF.getContext().getTypeSizeInChars(elementType); + CharUnits elementAlign = + DestPtr.getAlignment().alignmentOfArrayElement(elementSize); + + // Consider initializing the array by copying from a global. For this to be + // more efficient than per-element initialization, the size of the elements + // with explicit initializers should be large enough. + if (NumInitElements * elementSize.getQuantity() > 16 && + elementType.isTriviallyCopyableType(CGF.getContext())) { + CodeGen::CodeGenModule &CGM = CGF.CGM; + ConstantEmitter Emitter(CGM); + LangAS AS = ArrayQTy.getAddressSpace(); + if (llvm::Constant *C = Emitter.tryEmitForInitializer(E, AS, ArrayQTy)) { + auto GV = new llvm::GlobalVariable( + CGM.getModule(), C->getType(), + CGM.isTypeConstant(ArrayQTy, /* ExcludeCtorDtor= */ true), + llvm::GlobalValue::PrivateLinkage, C, "constinit", + /* InsertBefore= */ nullptr, llvm::GlobalVariable::NotThreadLocal, + CGM.getContext().getTargetAddressSpace(AS)); + Emitter.finalize(GV); + CharUnits Align = CGM.getContext().getTypeAlignInChars(ArrayQTy); + GV->setAlignment(Align.getQuantity()); + EmitFinalDestCopy(ArrayQTy, CGF.MakeAddrLValue(GV, ArrayQTy, Align)); + return; + } + } + + // Exception safety requires us to destroy all the + // already-constructed members if an initializer throws. + // For that, we'll need an EH cleanup. + QualType::DestructionKind dtorKind = elementType.isDestructedType(); + Address endOfInit = Address::invalid(); + EHScopeStack::stable_iterator cleanup; + llvm::Instruction *cleanupDominator = nullptr; + if (CGF.needsEHCleanup(dtorKind)) { + // In principle we could tell the cleanup where we are more + // directly, but the control flow can get so varied here that it + // would actually be quite complex. Therefore we go through an + // alloca. + endOfInit = CGF.CreateTempAlloca(begin->getType(), CGF.getPointerAlign(), + "arrayinit.endOfInit"); + cleanupDominator = Builder.CreateStore(begin, endOfInit); + CGF.pushIrregularPartialArrayCleanup(begin, endOfInit, elementType, + elementAlign, + CGF.getDestroyer(dtorKind)); + cleanup = CGF.EHStack.stable_begin(); + + // Otherwise, remember that we didn't need a cleanup. + } else { + dtorKind = QualType::DK_none; + } + + llvm::Value *one = llvm::ConstantInt::get(CGF.SizeTy, 1); + + // The 'current element to initialize'. The invariants on this + // variable are complicated. Essentially, after each iteration of + // the loop, it points to the last initialized element, except + // that it points to the beginning of the array before any + // elements have been initialized. + llvm::Value *element = begin; + + // Emit the explicit initializers. + for (uint64_t i = 0; i != NumInitElements; ++i) { + // Advance to the next element. + if (i > 0) { + element = Builder.CreateInBoundsGEP(element, one, "arrayinit.element"); + + // Tell the cleanup that it needs to destroy up to this + // element. TODO: some of these stores can be trivially + // observed to be unnecessary. + if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit); + } + + LValue elementLV = + CGF.MakeAddrLValue(Address(element, elementAlign), elementType); + EmitInitializationToLValue(E->getInit(i), elementLV); + } + + // Check whether there's a non-trivial array-fill expression. + Expr *filler = E->getArrayFiller(); + bool hasTrivialFiller = isTrivialFiller(filler); + + // Any remaining elements need to be zero-initialized, possibly + // using the filler expression. We can skip this if the we're + // emitting to zeroed memory. + if (NumInitElements != NumArrayElements && + !(Dest.isZeroed() && hasTrivialFiller && + CGF.getTypes().isZeroInitializable(elementType))) { + + // Use an actual loop. This is basically + // do { *array++ = filler; } while (array != end); + + // Advance to the start of the rest of the array. + if (NumInitElements) { + element = Builder.CreateInBoundsGEP(element, one, "arrayinit.start"); + if (endOfInit.isValid()) Builder.CreateStore(element, endOfInit); + } + + // Compute the end of the array. + llvm::Value *end = Builder.CreateInBoundsGEP(begin, + llvm::ConstantInt::get(CGF.SizeTy, NumArrayElements), + "arrayinit.end"); + + llvm::BasicBlock *entryBB = Builder.GetInsertBlock(); + llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body"); + + // Jump into the body. + CGF.EmitBlock(bodyBB); + llvm::PHINode *currentElement = + Builder.CreatePHI(element->getType(), 2, "arrayinit.cur"); + currentElement->addIncoming(element, entryBB); + + // Emit the actual filler expression. + { + // C++1z [class.temporary]p5: + // when a default constructor is called to initialize an element of + // an array with no corresponding initializer [...] the destruction of + // every temporary created in a default argument is sequenced before + // the construction of the next array element, if any + CodeGenFunction::RunCleanupsScope CleanupsScope(CGF); + LValue elementLV = + CGF.MakeAddrLValue(Address(currentElement, elementAlign), elementType); + if (filler) + EmitInitializationToLValue(filler, elementLV); + else + EmitNullInitializationToLValue(elementLV); + } + + // Move on to the next element. + llvm::Value *nextElement = + Builder.CreateInBoundsGEP(currentElement, one, "arrayinit.next"); + + // Tell the EH cleanup that we finished with the last element. + if (endOfInit.isValid()) Builder.CreateStore(nextElement, endOfInit); + + // Leave the loop if we're done. + llvm::Value *done = Builder.CreateICmpEQ(nextElement, end, + "arrayinit.done"); + llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end"); + Builder.CreateCondBr(done, endBB, bodyBB); + currentElement->addIncoming(nextElement, Builder.GetInsertBlock()); + + CGF.EmitBlock(endBB); + } + + // Leave the partial-array cleanup if we entered one. + if (dtorKind) CGF.DeactivateCleanupBlock(cleanup, cleanupDominator); +} + +//===----------------------------------------------------------------------===// +// Visitor Methods +//===----------------------------------------------------------------------===// + +void AggExprEmitter::VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E){ + Visit(E->GetTemporaryExpr()); +} + +void AggExprEmitter::VisitOpaqueValueExpr(OpaqueValueExpr *e) { + // If this is a unique OVE, just visit its source expression. + if (e->isUnique()) + Visit(e->getSourceExpr()); + else + EmitFinalDestCopy(e->getType(), CGF.getOrCreateOpaqueLValueMapping(e)); +} + +void +AggExprEmitter::VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { + if (Dest.isPotentiallyAliased() && + E->getType().isPODType(CGF.getContext())) { + // For a POD type, just emit a load of the lvalue + a copy, because our + // compound literal might alias the destination. + EmitAggLoadOfLValue(E); + return; + } + + AggValueSlot Slot = EnsureSlot(E->getType()); + CGF.EmitAggExpr(E->getInitializer(), Slot); +} + +/// Attempt to look through various unimportant expressions to find a +/// cast of the given kind. +static Expr *findPeephole(Expr *op, CastKind kind) { + while (true) { + op = op->IgnoreParens(); + if (CastExpr *castE = dyn_cast<CastExpr>(op)) { + if (castE->getCastKind() == kind) + return castE->getSubExpr(); + if (castE->getCastKind() == CK_NoOp) + continue; + } + return nullptr; + } +} + +void AggExprEmitter::VisitCastExpr(CastExpr *E) { + if (const auto *ECE = dyn_cast<ExplicitCastExpr>(E)) + CGF.CGM.EmitExplicitCastExprType(ECE, &CGF); + switch (E->getCastKind()) { + case CK_Dynamic: { + // FIXME: Can this actually happen? We have no test coverage for it. + assert(isa<CXXDynamicCastExpr>(E) && "CK_Dynamic without a dynamic_cast?"); + LValue LV = CGF.EmitCheckedLValue(E->getSubExpr(), + CodeGenFunction::TCK_Load); + // FIXME: Do we also need to handle property references here? + if (LV.isSimple()) + CGF.EmitDynamicCast(LV.getAddress(), cast<CXXDynamicCastExpr>(E)); + else + CGF.CGM.ErrorUnsupported(E, "non-simple lvalue dynamic_cast"); + + if (!Dest.isIgnored()) + CGF.CGM.ErrorUnsupported(E, "lvalue dynamic_cast with a destination"); + break; + } + + case CK_ToUnion: { + // Evaluate even if the destination is ignored. + if (Dest.isIgnored()) { + CGF.EmitAnyExpr(E->getSubExpr(), AggValueSlot::ignored(), + /*ignoreResult=*/true); + break; + } + + // GCC union extension + QualType Ty = E->getSubExpr()->getType(); + Address CastPtr = + Builder.CreateElementBitCast(Dest.getAddress(), CGF.ConvertType(Ty)); + EmitInitializationToLValue(E->getSubExpr(), + CGF.MakeAddrLValue(CastPtr, Ty)); + break; + } + + case CK_LValueToRValueBitCast: { + if (Dest.isIgnored()) { + CGF.EmitAnyExpr(E->getSubExpr(), AggValueSlot::ignored(), + /*ignoreResult=*/true); + break; + } + + LValue SourceLV = CGF.EmitLValue(E->getSubExpr()); + Address SourceAddress = + Builder.CreateElementBitCast(SourceLV.getAddress(), CGF.Int8Ty); + Address DestAddress = + Builder.CreateElementBitCast(Dest.getAddress(), CGF.Int8Ty); + llvm::Value *SizeVal = llvm::ConstantInt::get( + CGF.SizeTy, + CGF.getContext().getTypeSizeInChars(E->getType()).getQuantity()); + Builder.CreateMemCpy(DestAddress, SourceAddress, SizeVal); + break; + } + + case CK_DerivedToBase: + case CK_BaseToDerived: + case CK_UncheckedDerivedToBase: { + llvm_unreachable("cannot perform hierarchy conversion in EmitAggExpr: " + "should have been unpacked before we got here"); + } + + case CK_NonAtomicToAtomic: + case CK_AtomicToNonAtomic: { + bool isToAtomic = (E->getCastKind() == CK_NonAtomicToAtomic); + + // Determine the atomic and value types. + QualType atomicType = E->getSubExpr()->getType(); + QualType valueType = E->getType(); + if (isToAtomic) std::swap(atomicType, valueType); + + assert(atomicType->isAtomicType()); + assert(CGF.getContext().hasSameUnqualifiedType(valueType, + atomicType->castAs<AtomicType>()->getValueType())); + + // Just recurse normally if we're ignoring the result or the + // atomic type doesn't change representation. + if (Dest.isIgnored() || !CGF.CGM.isPaddedAtomicType(atomicType)) { + return Visit(E->getSubExpr()); + } + + CastKind peepholeTarget = + (isToAtomic ? CK_AtomicToNonAtomic : CK_NonAtomicToAtomic); + + // These two cases are reverses of each other; try to peephole them. + if (Expr *op = findPeephole(E->getSubExpr(), peepholeTarget)) { + assert(CGF.getContext().hasSameUnqualifiedType(op->getType(), + E->getType()) && + "peephole significantly changed types?"); + return Visit(op); + } + + // If we're converting an r-value of non-atomic type to an r-value + // of atomic type, just emit directly into the relevant sub-object. + if (isToAtomic) { + AggValueSlot valueDest = Dest; + if (!valueDest.isIgnored() && CGF.CGM.isPaddedAtomicType(atomicType)) { + // Zero-initialize. (Strictly speaking, we only need to initialize + // the padding at the end, but this is simpler.) + if (!Dest.isZeroed()) + CGF.EmitNullInitialization(Dest.getAddress(), atomicType); + + // Build a GEP to refer to the subobject. + Address valueAddr = + CGF.Builder.CreateStructGEP(valueDest.getAddress(), 0); + valueDest = AggValueSlot::forAddr(valueAddr, + valueDest.getQualifiers(), + valueDest.isExternallyDestructed(), + valueDest.requiresGCollection(), + valueDest.isPotentiallyAliased(), + AggValueSlot::DoesNotOverlap, + AggValueSlot::IsZeroed); + } + + CGF.EmitAggExpr(E->getSubExpr(), valueDest); + return; + } + + // Otherwise, we're converting an atomic type to a non-atomic type. + // Make an atomic temporary, emit into that, and then copy the value out. + AggValueSlot atomicSlot = + CGF.CreateAggTemp(atomicType, "atomic-to-nonatomic.temp"); + CGF.EmitAggExpr(E->getSubExpr(), atomicSlot); + + Address valueAddr = Builder.CreateStructGEP(atomicSlot.getAddress(), 0); + RValue rvalue = RValue::getAggregate(valueAddr, atomicSlot.isVolatile()); + return EmitFinalDestCopy(valueType, rvalue); + } + case CK_AddressSpaceConversion: + return Visit(E->getSubExpr()); + + case CK_LValueToRValue: + // If we're loading from a volatile type, force the destination + // into existence. + if (E->getSubExpr()->getType().isVolatileQualified()) { + EnsureDest(E->getType()); + return Visit(E->getSubExpr()); + } + + LLVM_FALLTHROUGH; + + + case CK_NoOp: + case CK_UserDefinedConversion: + case CK_ConstructorConversion: + assert(CGF.getContext().hasSameUnqualifiedType(E->getSubExpr()->getType(), + E->getType()) && + "Implicit cast types must be compatible"); + Visit(E->getSubExpr()); + break; + + case CK_LValueBitCast: + llvm_unreachable("should not be emitting lvalue bitcast as rvalue"); + + case CK_Dependent: + case CK_BitCast: + case CK_ArrayToPointerDecay: + case CK_FunctionToPointerDecay: + case CK_NullToPointer: + case CK_NullToMemberPointer: + case CK_BaseToDerivedMemberPointer: + case CK_DerivedToBaseMemberPointer: + case CK_MemberPointerToBoolean: + case CK_ReinterpretMemberPointer: + case CK_IntegralToPointer: + case CK_PointerToIntegral: + case CK_PointerToBoolean: + case CK_ToVoid: + case CK_VectorSplat: + case CK_IntegralCast: + case CK_BooleanToSignedIntegral: + case CK_IntegralToBoolean: + case CK_IntegralToFloating: + case CK_FloatingToIntegral: + case CK_FloatingToBoolean: + case CK_FloatingCast: + case CK_CPointerToObjCPointerCast: + case CK_BlockPointerToObjCPointerCast: + case CK_AnyPointerToBlockPointerCast: + case CK_ObjCObjectLValueCast: + case CK_FloatingRealToComplex: + case CK_FloatingComplexToReal: + case CK_FloatingComplexToBoolean: + case CK_FloatingComplexCast: + case CK_FloatingComplexToIntegralComplex: + case CK_IntegralRealToComplex: + case CK_IntegralComplexToReal: + case CK_IntegralComplexToBoolean: + case CK_IntegralComplexCast: + case CK_IntegralComplexToFloatingComplex: + case CK_ARCProduceObject: + case CK_ARCConsumeObject: + case CK_ARCReclaimReturnedObject: + case CK_ARCExtendBlockObject: + case CK_CopyAndAutoreleaseBlockObject: + case CK_BuiltinFnToFnPtr: + case CK_ZeroToOCLOpaqueType: + + case CK_IntToOCLSampler: + case CK_FixedPointCast: + case CK_FixedPointToBoolean: + case CK_FixedPointToIntegral: + case CK_IntegralToFixedPoint: + llvm_unreachable("cast kind invalid for aggregate types"); + } +} + +void AggExprEmitter::VisitCallExpr(const CallExpr *E) { + if (E->getCallReturnType(CGF.getContext())->isReferenceType()) { + EmitAggLoadOfLValue(E); + return; + } + + withReturnValueSlot(E, [&](ReturnValueSlot Slot) { + return CGF.EmitCallExpr(E, Slot); + }); +} + +void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) { + withReturnValueSlot(E, [&](ReturnValueSlot Slot) { + return CGF.EmitObjCMessageExpr(E, Slot); + }); +} + +void AggExprEmitter::VisitBinComma(const BinaryOperator *E) { + CGF.EmitIgnoredExpr(E->getLHS()); + Visit(E->getRHS()); +} + +void AggExprEmitter::VisitStmtExpr(const StmtExpr *E) { + CodeGenFunction::StmtExprEvaluation eval(CGF); + CGF.EmitCompoundStmt(*E->getSubStmt(), true, Dest); +} + +enum CompareKind { + CK_Less, + CK_Greater, + CK_Equal, +}; + +static llvm::Value *EmitCompare(CGBuilderTy &Builder, CodeGenFunction &CGF, + const BinaryOperator *E, llvm::Value *LHS, + llvm::Value *RHS, CompareKind Kind, + const char *NameSuffix = "") { + QualType ArgTy = E->getLHS()->getType(); + if (const ComplexType *CT = ArgTy->getAs<ComplexType>()) + ArgTy = CT->getElementType(); + + if (const auto *MPT = ArgTy->getAs<MemberPointerType>()) { + assert(Kind == CK_Equal && + "member pointers may only be compared for equality"); + return CGF.CGM.getCXXABI().EmitMemberPointerComparison( + CGF, LHS, RHS, MPT, /*IsInequality*/ false); + } + + // Compute the comparison instructions for the specified comparison kind. + struct CmpInstInfo { + const char *Name; + llvm::CmpInst::Predicate FCmp; + llvm::CmpInst::Predicate SCmp; + llvm::CmpInst::Predicate UCmp; + }; + CmpInstInfo InstInfo = [&]() -> CmpInstInfo { + using FI = llvm::FCmpInst; + using II = llvm::ICmpInst; + switch (Kind) { + case CK_Less: + return {"cmp.lt", FI::FCMP_OLT, II::ICMP_SLT, II::ICMP_ULT}; + case CK_Greater: + return {"cmp.gt", FI::FCMP_OGT, II::ICMP_SGT, II::ICMP_UGT}; + case CK_Equal: + return {"cmp.eq", FI::FCMP_OEQ, II::ICMP_EQ, II::ICMP_EQ}; + } + llvm_unreachable("Unrecognised CompareKind enum"); + }(); + + if (ArgTy->hasFloatingRepresentation()) + return Builder.CreateFCmp(InstInfo.FCmp, LHS, RHS, + llvm::Twine(InstInfo.Name) + NameSuffix); + if (ArgTy->isIntegralOrEnumerationType() || ArgTy->isPointerType()) { + auto Inst = + ArgTy->hasSignedIntegerRepresentation() ? InstInfo.SCmp : InstInfo.UCmp; + return Builder.CreateICmp(Inst, LHS, RHS, + llvm::Twine(InstInfo.Name) + NameSuffix); + } + + llvm_unreachable("unsupported aggregate binary expression should have " + "already been handled"); +} + +void AggExprEmitter::VisitBinCmp(const BinaryOperator *E) { + using llvm::BasicBlock; + using llvm::PHINode; + using llvm::Value; + assert(CGF.getContext().hasSameType(E->getLHS()->getType(), + E->getRHS()->getType())); + const ComparisonCategoryInfo &CmpInfo = + CGF.getContext().CompCategories.getInfoForType(E->getType()); + assert(CmpInfo.Record->isTriviallyCopyable() && + "cannot copy non-trivially copyable aggregate"); + + QualType ArgTy = E->getLHS()->getType(); + + // TODO: Handle comparing these types. + if (ArgTy->isVectorType()) + return CGF.ErrorUnsupported( + E, "aggregate three-way comparison with vector arguments"); + if (!ArgTy->isIntegralOrEnumerationType() && !ArgTy->isRealFloatingType() && + !ArgTy->isNullPtrType() && !ArgTy->isPointerType() && + !ArgTy->isMemberPointerType() && !ArgTy->isAnyComplexType()) { + return CGF.ErrorUnsupported(E, "aggregate three-way comparison"); + } + bool IsComplex = ArgTy->isAnyComplexType(); + + // Evaluate the operands to the expression and extract their values. + auto EmitOperand = [&](Expr *E) -> std::pair<Value *, Value *> { + RValue RV = CGF.EmitAnyExpr(E); + if (RV.isScalar()) + return {RV.getScalarVal(), nullptr}; + if (RV.isAggregate()) + return {RV.getAggregatePointer(), nullptr}; + assert(RV.isComplex()); + return RV.getComplexVal(); + }; + auto LHSValues = EmitOperand(E->getLHS()), + RHSValues = EmitOperand(E->getRHS()); + + auto EmitCmp = [&](CompareKind K) { + Value *Cmp = EmitCompare(Builder, CGF, E, LHSValues.first, RHSValues.first, + K, IsComplex ? ".r" : ""); + if (!IsComplex) + return Cmp; + assert(K == CompareKind::CK_Equal); + Value *CmpImag = EmitCompare(Builder, CGF, E, LHSValues.second, + RHSValues.second, K, ".i"); + return Builder.CreateAnd(Cmp, CmpImag, "and.eq"); + }; + auto EmitCmpRes = [&](const ComparisonCategoryInfo::ValueInfo *VInfo) { + return Builder.getInt(VInfo->getIntValue()); + }; + + Value *Select; + if (ArgTy->isNullPtrType()) { + Select = EmitCmpRes(CmpInfo.getEqualOrEquiv()); + } else if (CmpInfo.isEquality()) { + Select = Builder.CreateSelect( + EmitCmp(CK_Equal), EmitCmpRes(CmpInfo.getEqualOrEquiv()), + EmitCmpRes(CmpInfo.getNonequalOrNonequiv()), "sel.eq"); + } else if (!CmpInfo.isPartial()) { + Value *SelectOne = + Builder.CreateSelect(EmitCmp(CK_Less), EmitCmpRes(CmpInfo.getLess()), + EmitCmpRes(CmpInfo.getGreater()), "sel.lt"); + Select = Builder.CreateSelect(EmitCmp(CK_Equal), + EmitCmpRes(CmpInfo.getEqualOrEquiv()), + SelectOne, "sel.eq"); + } else { + Value *SelectEq = Builder.CreateSelect( + EmitCmp(CK_Equal), EmitCmpRes(CmpInfo.getEqualOrEquiv()), + EmitCmpRes(CmpInfo.getUnordered()), "sel.eq"); + Value *SelectGT = Builder.CreateSelect(EmitCmp(CK_Greater), + EmitCmpRes(CmpInfo.getGreater()), + SelectEq, "sel.gt"); + Select = Builder.CreateSelect( + EmitCmp(CK_Less), EmitCmpRes(CmpInfo.getLess()), SelectGT, "sel.lt"); + } + // Create the return value in the destination slot. + EnsureDest(E->getType()); + LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType()); + + // Emit the address of the first (and only) field in the comparison category + // type, and initialize it from the constant integer value selected above. + LValue FieldLV = CGF.EmitLValueForFieldInitialization( + DestLV, *CmpInfo.Record->field_begin()); + CGF.EmitStoreThroughLValue(RValue::get(Select), FieldLV, /*IsInit*/ true); + + // All done! The result is in the Dest slot. +} + +void AggExprEmitter::VisitBinaryOperator(const BinaryOperator *E) { + if (E->getOpcode() == BO_PtrMemD || E->getOpcode() == BO_PtrMemI) + VisitPointerToDataMemberBinaryOperator(E); + else + CGF.ErrorUnsupported(E, "aggregate binary expression"); +} + +void AggExprEmitter::VisitPointerToDataMemberBinaryOperator( + const BinaryOperator *E) { + LValue LV = CGF.EmitPointerToDataMemberBinaryExpr(E); + EmitFinalDestCopy(E->getType(), LV); +} + +/// Is the value of the given expression possibly a reference to or +/// into a __block variable? +static bool isBlockVarRef(const Expr *E) { + // Make sure we look through parens. + E = E->IgnoreParens(); + + // Check for a direct reference to a __block variable. + if (const DeclRefExpr *DRE = dyn_cast<DeclRefExpr>(E)) { + const VarDecl *var = dyn_cast<VarDecl>(DRE->getDecl()); + return (var && var->hasAttr<BlocksAttr>()); + } + + // More complicated stuff. + + // Binary operators. + if (const BinaryOperator *op = dyn_cast<BinaryOperator>(E)) { + // For an assignment or pointer-to-member operation, just care + // about the LHS. + if (op->isAssignmentOp() || op->isPtrMemOp()) + return isBlockVarRef(op->getLHS()); + + // For a comma, just care about the RHS. + if (op->getOpcode() == BO_Comma) + return isBlockVarRef(op->getRHS()); + + // FIXME: pointer arithmetic? + return false; + + // Check both sides of a conditional operator. + } else if (const AbstractConditionalOperator *op + = dyn_cast<AbstractConditionalOperator>(E)) { + return isBlockVarRef(op->getTrueExpr()) + || isBlockVarRef(op->getFalseExpr()); + + // OVEs are required to support BinaryConditionalOperators. + } else if (const OpaqueValueExpr *op + = dyn_cast<OpaqueValueExpr>(E)) { + if (const Expr *src = op->getSourceExpr()) + return isBlockVarRef(src); + + // Casts are necessary to get things like (*(int*)&var) = foo(). + // We don't really care about the kind of cast here, except + // we don't want to look through l2r casts, because it's okay + // to get the *value* in a __block variable. + } else if (const CastExpr *cast = dyn_cast<CastExpr>(E)) { + if (cast->getCastKind() == CK_LValueToRValue) + return false; + return isBlockVarRef(cast->getSubExpr()); + + // Handle unary operators. Again, just aggressively look through + // it, ignoring the operation. + } else if (const UnaryOperator *uop = dyn_cast<UnaryOperator>(E)) { + return isBlockVarRef(uop->getSubExpr()); + + // Look into the base of a field access. + } else if (const MemberExpr *mem = dyn_cast<MemberExpr>(E)) { + return isBlockVarRef(mem->getBase()); + + // Look into the base of a subscript. + } else if (const ArraySubscriptExpr *sub = dyn_cast<ArraySubscriptExpr>(E)) { + return isBlockVarRef(sub->getBase()); + } + + return false; +} + +void AggExprEmitter::VisitBinAssign(const BinaryOperator *E) { + // For an assignment to work, the value on the right has + // to be compatible with the value on the left. + assert(CGF.getContext().hasSameUnqualifiedType(E->getLHS()->getType(), + E->getRHS()->getType()) + && "Invalid assignment"); + + // If the LHS might be a __block variable, and the RHS can + // potentially cause a block copy, we need to evaluate the RHS first + // so that the assignment goes the right place. + // This is pretty semantically fragile. + if (isBlockVarRef(E->getLHS()) && + E->getRHS()->HasSideEffects(CGF.getContext())) { + // Ensure that we have a destination, and evaluate the RHS into that. + EnsureDest(E->getRHS()->getType()); + Visit(E->getRHS()); + + // Now emit the LHS and copy into it. + LValue LHS = CGF.EmitCheckedLValue(E->getLHS(), CodeGenFunction::TCK_Store); + + // That copy is an atomic copy if the LHS is atomic. + if (LHS.getType()->isAtomicType() || + CGF.LValueIsSuitableForInlineAtomic(LHS)) { + CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false); + return; + } + + EmitCopy(E->getLHS()->getType(), + AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed, + needsGC(E->getLHS()->getType()), + AggValueSlot::IsAliased, + AggValueSlot::MayOverlap), + Dest); + return; + } + + LValue LHS = CGF.EmitLValue(E->getLHS()); + + // If we have an atomic type, evaluate into the destination and then + // do an atomic copy. + if (LHS.getType()->isAtomicType() || + CGF.LValueIsSuitableForInlineAtomic(LHS)) { + EnsureDest(E->getRHS()->getType()); + Visit(E->getRHS()); + CGF.EmitAtomicStore(Dest.asRValue(), LHS, /*isInit*/ false); + return; + } + + // Codegen the RHS so that it stores directly into the LHS. + AggValueSlot LHSSlot = + AggValueSlot::forLValue(LHS, AggValueSlot::IsDestructed, + needsGC(E->getLHS()->getType()), + AggValueSlot::IsAliased, + AggValueSlot::MayOverlap); + // A non-volatile aggregate destination might have volatile member. + if (!LHSSlot.isVolatile() && + CGF.hasVolatileMember(E->getLHS()->getType())) + LHSSlot.setVolatile(true); + + CGF.EmitAggExpr(E->getRHS(), LHSSlot); + + // Copy into the destination if the assignment isn't ignored. + EmitFinalDestCopy(E->getType(), LHS); +} + +void AggExprEmitter:: +VisitAbstractConditionalOperator(const AbstractConditionalOperator *E) { + llvm::BasicBlock *LHSBlock = CGF.createBasicBlock("cond.true"); + llvm::BasicBlock *RHSBlock = CGF.createBasicBlock("cond.false"); + llvm::BasicBlock *ContBlock = CGF.createBasicBlock("cond.end"); + + // Bind the common expression if necessary. + CodeGenFunction::OpaqueValueMapping binding(CGF, E); + + CodeGenFunction::ConditionalEvaluation eval(CGF); + CGF.EmitBranchOnBoolExpr(E->getCond(), LHSBlock, RHSBlock, + CGF.getProfileCount(E)); + + // Save whether the destination's lifetime is externally managed. + bool isExternallyDestructed = Dest.isExternallyDestructed(); + + eval.begin(CGF); + CGF.EmitBlock(LHSBlock); + CGF.incrementProfileCounter(E); + Visit(E->getTrueExpr()); + eval.end(CGF); + + assert(CGF.HaveInsertPoint() && "expression evaluation ended with no IP!"); + CGF.Builder.CreateBr(ContBlock); + + // If the result of an agg expression is unused, then the emission + // of the LHS might need to create a destination slot. That's fine + // with us, and we can safely emit the RHS into the same slot, but + // we shouldn't claim that it's already being destructed. + Dest.setExternallyDestructed(isExternallyDestructed); + + eval.begin(CGF); + CGF.EmitBlock(RHSBlock); + Visit(E->getFalseExpr()); + eval.end(CGF); + + CGF.EmitBlock(ContBlock); +} + +void AggExprEmitter::VisitChooseExpr(const ChooseExpr *CE) { + Visit(CE->getChosenSubExpr()); +} + +void AggExprEmitter::VisitVAArgExpr(VAArgExpr *VE) { + Address ArgValue = Address::invalid(); + Address ArgPtr = CGF.EmitVAArg(VE, ArgValue); + + // If EmitVAArg fails, emit an error. + if (!ArgPtr.isValid()) { + CGF.ErrorUnsupported(VE, "aggregate va_arg expression"); + return; + } + + EmitFinalDestCopy(VE->getType(), CGF.MakeAddrLValue(ArgPtr, VE->getType())); +} + +void AggExprEmitter::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) { + // Ensure that we have a slot, but if we already do, remember + // whether it was externally destructed. + bool wasExternallyDestructed = Dest.isExternallyDestructed(); + EnsureDest(E->getType()); + + // We're going to push a destructor if there isn't already one. + Dest.setExternallyDestructed(); + + Visit(E->getSubExpr()); + + // Push that destructor we promised. + if (!wasExternallyDestructed) + CGF.EmitCXXTemporary(E->getTemporary(), E->getType(), Dest.getAddress()); +} + +void +AggExprEmitter::VisitCXXConstructExpr(const CXXConstructExpr *E) { + AggValueSlot Slot = EnsureSlot(E->getType()); + CGF.EmitCXXConstructExpr(E, Slot); +} + +void AggExprEmitter::VisitCXXInheritedCtorInitExpr( + const CXXInheritedCtorInitExpr *E) { + AggValueSlot Slot = EnsureSlot(E->getType()); + CGF.EmitInheritedCXXConstructorCall( + E->getConstructor(), E->constructsVBase(), Slot.getAddress(), + E->inheritedFromVBase(), E); +} + +void +AggExprEmitter::VisitLambdaExpr(LambdaExpr *E) { + AggValueSlot Slot = EnsureSlot(E->getType()); + LValue SlotLV = CGF.MakeAddrLValue(Slot.getAddress(), E->getType()); + + // We'll need to enter cleanup scopes in case any of the element + // initializers throws an exception. + SmallVector<EHScopeStack::stable_iterator, 16> Cleanups; + llvm::Instruction *CleanupDominator = nullptr; + + CXXRecordDecl::field_iterator CurField = E->getLambdaClass()->field_begin(); + for (LambdaExpr::const_capture_init_iterator i = E->capture_init_begin(), + e = E->capture_init_end(); + i != e; ++i, ++CurField) { + // Emit initialization + LValue LV = CGF.EmitLValueForFieldInitialization(SlotLV, *CurField); + if (CurField->hasCapturedVLAType()) { + CGF.EmitLambdaVLACapture(CurField->getCapturedVLAType(), LV); + continue; + } + + EmitInitializationToLValue(*i, LV); + + // Push a destructor if necessary. + if (QualType::DestructionKind DtorKind = + CurField->getType().isDestructedType()) { + assert(LV.isSimple()); + if (CGF.needsEHCleanup(DtorKind)) { + if (!CleanupDominator) + CleanupDominator = CGF.Builder.CreateAlignedLoad( + CGF.Int8Ty, + llvm::Constant::getNullValue(CGF.Int8PtrTy), + CharUnits::One()); // placeholder + + CGF.pushDestroy(EHCleanup, LV.getAddress(), CurField->getType(), + CGF.getDestroyer(DtorKind), false); + Cleanups.push_back(CGF.EHStack.stable_begin()); + } + } + } + + // Deactivate all the partial cleanups in reverse order, which + // generally means popping them. + for (unsigned i = Cleanups.size(); i != 0; --i) + CGF.DeactivateCleanupBlock(Cleanups[i-1], CleanupDominator); + + // Destroy the placeholder if we made one. + if (CleanupDominator) + CleanupDominator->eraseFromParent(); +} + +void AggExprEmitter::VisitExprWithCleanups(ExprWithCleanups *E) { + CGF.enterFullExpression(E); + CodeGenFunction::RunCleanupsScope cleanups(CGF); + Visit(E->getSubExpr()); +} + +void AggExprEmitter::VisitCXXScalarValueInitExpr(CXXScalarValueInitExpr *E) { + QualType T = E->getType(); + AggValueSlot Slot = EnsureSlot(T); + EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddress(), T)); +} + +void AggExprEmitter::VisitImplicitValueInitExpr(ImplicitValueInitExpr *E) { + QualType T = E->getType(); + AggValueSlot Slot = EnsureSlot(T); + EmitNullInitializationToLValue(CGF.MakeAddrLValue(Slot.getAddress(), T)); +} + +/// isSimpleZero - If emitting this value will obviously just cause a store of +/// zero to memory, return true. This can return false if uncertain, so it just +/// handles simple cases. +static bool isSimpleZero(const Expr *E, CodeGenFunction &CGF) { + E = E->IgnoreParens(); + + // 0 + if (const IntegerLiteral *IL = dyn_cast<IntegerLiteral>(E)) + return IL->getValue() == 0; + // +0.0 + if (const FloatingLiteral *FL = dyn_cast<FloatingLiteral>(E)) + return FL->getValue().isPosZero(); + // int() + if ((isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) && + CGF.getTypes().isZeroInitializable(E->getType())) + return true; + // (int*)0 - Null pointer expressions. + if (const CastExpr *ICE = dyn_cast<CastExpr>(E)) + return ICE->getCastKind() == CK_NullToPointer && + CGF.getTypes().isPointerZeroInitializable(E->getType()) && + !E->HasSideEffects(CGF.getContext()); + // '\0' + if (const CharacterLiteral *CL = dyn_cast<CharacterLiteral>(E)) + return CL->getValue() == 0; + + // Otherwise, hard case: conservatively return false. + return false; +} + + +void +AggExprEmitter::EmitInitializationToLValue(Expr *E, LValue LV) { + QualType type = LV.getType(); + // FIXME: Ignore result? + // FIXME: Are initializers affected by volatile? + if (Dest.isZeroed() && isSimpleZero(E, CGF)) { + // Storing "i32 0" to a zero'd memory location is a noop. + return; + } else if (isa<ImplicitValueInitExpr>(E) || isa<CXXScalarValueInitExpr>(E)) { + return EmitNullInitializationToLValue(LV); + } else if (isa<NoInitExpr>(E)) { + // Do nothing. + return; + } else if (type->isReferenceType()) { + RValue RV = CGF.EmitReferenceBindingToExpr(E); + return CGF.EmitStoreThroughLValue(RV, LV); + } + + switch (CGF.getEvaluationKind(type)) { + case TEK_Complex: + CGF.EmitComplexExprIntoLValue(E, LV, /*isInit*/ true); + return; + case TEK_Aggregate: + CGF.EmitAggExpr(E, AggValueSlot::forLValue(LV, + AggValueSlot::IsDestructed, + AggValueSlot::DoesNotNeedGCBarriers, + AggValueSlot::IsNotAliased, + AggValueSlot::MayOverlap, + Dest.isZeroed())); + return; + case TEK_Scalar: + if (LV.isSimple()) { + CGF.EmitScalarInit(E, /*D=*/nullptr, LV, /*Captured=*/false); + } else { + CGF.EmitStoreThroughLValue(RValue::get(CGF.EmitScalarExpr(E)), LV); + } + return; + } + llvm_unreachable("bad evaluation kind"); +} + +void AggExprEmitter::EmitNullInitializationToLValue(LValue lv) { + QualType type = lv.getType(); + + // If the destination slot is already zeroed out before the aggregate is + // copied into it, we don't have to emit any zeros here. + if (Dest.isZeroed() && CGF.getTypes().isZeroInitializable(type)) + return; + + if (CGF.hasScalarEvaluationKind(type)) { + // For non-aggregates, we can store the appropriate null constant. + llvm::Value *null = CGF.CGM.EmitNullConstant(type); + // Note that the following is not equivalent to + // EmitStoreThroughBitfieldLValue for ARC types. + if (lv.isBitField()) { + CGF.EmitStoreThroughBitfieldLValue(RValue::get(null), lv); + } else { + assert(lv.isSimple()); + CGF.EmitStoreOfScalar(null, lv, /* isInitialization */ true); + } + } else { + // There's a potential optimization opportunity in combining + // memsets; that would be easy for arrays, but relatively + // difficult for structures with the current code. + CGF.EmitNullInitialization(lv.getAddress(), lv.getType()); + } +} + +void AggExprEmitter::VisitInitListExpr(InitListExpr *E) { +#if 0 + // FIXME: Assess perf here? Figure out what cases are worth optimizing here + // (Length of globals? Chunks of zeroed-out space?). + // + // If we can, prefer a copy from a global; this is a lot less code for long + // globals, and it's easier for the current optimizers to analyze. + if (llvm::Constant* C = CGF.CGM.EmitConstantExpr(E, E->getType(), &CGF)) { + llvm::GlobalVariable* GV = + new llvm::GlobalVariable(CGF.CGM.getModule(), C->getType(), true, + llvm::GlobalValue::InternalLinkage, C, ""); + EmitFinalDestCopy(E->getType(), CGF.MakeAddrLValue(GV, E->getType())); + return; + } +#endif + if (E->hadArrayRangeDesignator()) + CGF.ErrorUnsupported(E, "GNU array range designator extension"); + + if (E->isTransparent()) + return Visit(E->getInit(0)); + + AggValueSlot Dest = EnsureSlot(E->getType()); + + LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType()); + + // Handle initialization of an array. + if (E->getType()->isArrayType()) { + auto AType = cast<llvm::ArrayType>(Dest.getAddress().getElementType()); + EmitArrayInit(Dest.getAddress(), AType, E->getType(), E); + return; + } + + assert(E->getType()->isRecordType() && "Only support structs/unions here!"); + + // Do struct initialization; this code just sets each individual member + // to the approprate value. This makes bitfield support automatic; + // the disadvantage is that the generated code is more difficult for + // the optimizer, especially with bitfields. + unsigned NumInitElements = E->getNumInits(); + RecordDecl *record = E->getType()->castAs<RecordType>()->getDecl(); + + // We'll need to enter cleanup scopes in case any of the element + // initializers throws an exception. + SmallVector<EHScopeStack::stable_iterator, 16> cleanups; + llvm::Instruction *cleanupDominator = nullptr; + auto addCleanup = [&](const EHScopeStack::stable_iterator &cleanup) { + cleanups.push_back(cleanup); + if (!cleanupDominator) // create placeholder once needed + cleanupDominator = CGF.Builder.CreateAlignedLoad( + CGF.Int8Ty, llvm::Constant::getNullValue(CGF.Int8PtrTy), + CharUnits::One()); + }; + + unsigned curInitIndex = 0; + + // Emit initialization of base classes. + if (auto *CXXRD = dyn_cast<CXXRecordDecl>(record)) { + assert(E->getNumInits() >= CXXRD->getNumBases() && + "missing initializer for base class"); + for (auto &Base : CXXRD->bases()) { + assert(!Base.isVirtual() && "should not see vbases here"); + auto *BaseRD = Base.getType()->getAsCXXRecordDecl(); + Address V = CGF.GetAddressOfDirectBaseInCompleteClass( + Dest.getAddress(), CXXRD, BaseRD, + /*isBaseVirtual*/ false); + AggValueSlot AggSlot = AggValueSlot::forAddr( + V, Qualifiers(), + AggValueSlot::IsDestructed, + AggValueSlot::DoesNotNeedGCBarriers, + AggValueSlot::IsNotAliased, + CGF.getOverlapForBaseInit(CXXRD, BaseRD, Base.isVirtual())); + CGF.EmitAggExpr(E->getInit(curInitIndex++), AggSlot); + + if (QualType::DestructionKind dtorKind = + Base.getType().isDestructedType()) { + CGF.pushDestroy(dtorKind, V, Base.getType()); + addCleanup(CGF.EHStack.stable_begin()); + } + } + } + + // Prepare a 'this' for CXXDefaultInitExprs. + CodeGenFunction::FieldConstructionScope FCS(CGF, Dest.getAddress()); + + if (record->isUnion()) { + // Only initialize one field of a union. The field itself is + // specified by the initializer list. + if (!E->getInitializedFieldInUnion()) { + // Empty union; we have nothing to do. + +#ifndef NDEBUG + // Make sure that it's really an empty and not a failure of + // semantic analysis. + for (const auto *Field : record->fields()) + assert(Field->isUnnamedBitfield() && "Only unnamed bitfields allowed"); +#endif + return; + } + + // FIXME: volatility + FieldDecl *Field = E->getInitializedFieldInUnion(); + + LValue FieldLoc = CGF.EmitLValueForFieldInitialization(DestLV, Field); + if (NumInitElements) { + // Store the initializer into the field + EmitInitializationToLValue(E->getInit(0), FieldLoc); + } else { + // Default-initialize to null. + EmitNullInitializationToLValue(FieldLoc); + } + + return; + } + + // Here we iterate over the fields; this makes it simpler to both + // default-initialize fields and skip over unnamed fields. + for (const auto *field : record->fields()) { + // We're done once we hit the flexible array member. + if (field->getType()->isIncompleteArrayType()) + break; + + // Always skip anonymous bitfields. + if (field->isUnnamedBitfield()) + continue; + + // We're done if we reach the end of the explicit initializers, we + // have a zeroed object, and the rest of the fields are + // zero-initializable. + if (curInitIndex == NumInitElements && Dest.isZeroed() && + CGF.getTypes().isZeroInitializable(E->getType())) + break; + + + LValue LV = CGF.EmitLValueForFieldInitialization(DestLV, field); + // We never generate write-barries for initialized fields. + LV.setNonGC(true); + + if (curInitIndex < NumInitElements) { + // Store the initializer into the field. + EmitInitializationToLValue(E->getInit(curInitIndex++), LV); + } else { + // We're out of initializers; default-initialize to null + EmitNullInitializationToLValue(LV); + } + + // Push a destructor if necessary. + // FIXME: if we have an array of structures, all explicitly + // initialized, we can end up pushing a linear number of cleanups. + bool pushedCleanup = false; + if (QualType::DestructionKind dtorKind + = field->getType().isDestructedType()) { + assert(LV.isSimple()); + if (CGF.needsEHCleanup(dtorKind)) { + CGF.pushDestroy(EHCleanup, LV.getAddress(), field->getType(), + CGF.getDestroyer(dtorKind), false); + addCleanup(CGF.EHStack.stable_begin()); + pushedCleanup = true; + } + } + + // If the GEP didn't get used because of a dead zero init or something + // else, clean it up for -O0 builds and general tidiness. + if (!pushedCleanup && LV.isSimple()) + if (llvm::GetElementPtrInst *GEP = + dyn_cast<llvm::GetElementPtrInst>(LV.getPointer())) + if (GEP->use_empty()) + GEP->eraseFromParent(); + } + + // Deactivate all the partial cleanups in reverse order, which + // generally means popping them. + assert((cleanupDominator || cleanups.empty()) && + "Missing cleanupDominator before deactivating cleanup blocks"); + for (unsigned i = cleanups.size(); i != 0; --i) + CGF.DeactivateCleanupBlock(cleanups[i-1], cleanupDominator); + + // Destroy the placeholder if we made one. + if (cleanupDominator) + cleanupDominator->eraseFromParent(); +} + +void AggExprEmitter::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E, + llvm::Value *outerBegin) { + // Emit the common subexpression. + CodeGenFunction::OpaqueValueMapping binding(CGF, E->getCommonExpr()); + + Address destPtr = EnsureSlot(E->getType()).getAddress(); + uint64_t numElements = E->getArraySize().getZExtValue(); + + if (!numElements) + return; + + // destPtr is an array*. Construct an elementType* by drilling down a level. + llvm::Value *zero = llvm::ConstantInt::get(CGF.SizeTy, 0); + llvm::Value *indices[] = {zero, zero}; + llvm::Value *begin = Builder.CreateInBoundsGEP(destPtr.getPointer(), indices, + "arrayinit.begin"); + + // Prepare to special-case multidimensional array initialization: we avoid + // emitting multiple destructor loops in that case. + if (!outerBegin) + outerBegin = begin; + ArrayInitLoopExpr *InnerLoop = dyn_cast<ArrayInitLoopExpr>(E->getSubExpr()); + + QualType elementType = + CGF.getContext().getAsArrayType(E->getType())->getElementType(); + CharUnits elementSize = CGF.getContext().getTypeSizeInChars(elementType); + CharUnits elementAlign = + destPtr.getAlignment().alignmentOfArrayElement(elementSize); + + llvm::BasicBlock *entryBB = Builder.GetInsertBlock(); + llvm::BasicBlock *bodyBB = CGF.createBasicBlock("arrayinit.body"); + + // Jump into the body. + CGF.EmitBlock(bodyBB); + llvm::PHINode *index = + Builder.CreatePHI(zero->getType(), 2, "arrayinit.index"); + index->addIncoming(zero, entryBB); + llvm::Value *element = Builder.CreateInBoundsGEP(begin, index); + + // Prepare for a cleanup. + QualType::DestructionKind dtorKind = elementType.isDestructedType(); + EHScopeStack::stable_iterator cleanup; + if (CGF.needsEHCleanup(dtorKind) && !InnerLoop) { + if (outerBegin->getType() != element->getType()) + outerBegin = Builder.CreateBitCast(outerBegin, element->getType()); + CGF.pushRegularPartialArrayCleanup(outerBegin, element, elementType, + elementAlign, + CGF.getDestroyer(dtorKind)); + cleanup = CGF.EHStack.stable_begin(); + } else { + dtorKind = QualType::DK_none; + } + + // Emit the actual filler expression. + { + // Temporaries created in an array initialization loop are destroyed + // at the end of each iteration. + CodeGenFunction::RunCleanupsScope CleanupsScope(CGF); + CodeGenFunction::ArrayInitLoopExprScope Scope(CGF, index); + LValue elementLV = + CGF.MakeAddrLValue(Address(element, elementAlign), elementType); + + if (InnerLoop) { + // If the subexpression is an ArrayInitLoopExpr, share its cleanup. + auto elementSlot = AggValueSlot::forLValue( + elementLV, AggValueSlot::IsDestructed, + AggValueSlot::DoesNotNeedGCBarriers, + AggValueSlot::IsNotAliased, + AggValueSlot::DoesNotOverlap); + AggExprEmitter(CGF, elementSlot, false) + .VisitArrayInitLoopExpr(InnerLoop, outerBegin); + } else + EmitInitializationToLValue(E->getSubExpr(), elementLV); + } + + // Move on to the next element. + llvm::Value *nextIndex = Builder.CreateNUWAdd( + index, llvm::ConstantInt::get(CGF.SizeTy, 1), "arrayinit.next"); + index->addIncoming(nextIndex, Builder.GetInsertBlock()); + + // Leave the loop if we're done. + llvm::Value *done = Builder.CreateICmpEQ( + nextIndex, llvm::ConstantInt::get(CGF.SizeTy, numElements), + "arrayinit.done"); + llvm::BasicBlock *endBB = CGF.createBasicBlock("arrayinit.end"); + Builder.CreateCondBr(done, endBB, bodyBB); + + CGF.EmitBlock(endBB); + + // Leave the partial-array cleanup if we entered one. + if (dtorKind) + CGF.DeactivateCleanupBlock(cleanup, index); +} + +void AggExprEmitter::VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E) { + AggValueSlot Dest = EnsureSlot(E->getType()); + + LValue DestLV = CGF.MakeAddrLValue(Dest.getAddress(), E->getType()); + EmitInitializationToLValue(E->getBase(), DestLV); + VisitInitListExpr(E->getUpdater()); +} + +//===----------------------------------------------------------------------===// +// Entry Points into this File +//===----------------------------------------------------------------------===// + +/// GetNumNonZeroBytesInInit - Get an approximate count of the number of +/// non-zero bytes that will be stored when outputting the initializer for the +/// specified initializer expression. +static CharUnits GetNumNonZeroBytesInInit(const Expr *E, CodeGenFunction &CGF) { + E = E->IgnoreParens(); + + // 0 and 0.0 won't require any non-zero stores! + if (isSimpleZero(E, CGF)) return CharUnits::Zero(); + + // If this is an initlist expr, sum up the size of sizes of the (present) + // elements. If this is something weird, assume the whole thing is non-zero. + const InitListExpr *ILE = dyn_cast<InitListExpr>(E); + while (ILE && ILE->isTransparent()) + ILE = dyn_cast<InitListExpr>(ILE->getInit(0)); + if (!ILE || !CGF.getTypes().isZeroInitializable(ILE->getType())) + return CGF.getContext().getTypeSizeInChars(E->getType()); + + // InitListExprs for structs have to be handled carefully. If there are + // reference members, we need to consider the size of the reference, not the + // referencee. InitListExprs for unions and arrays can't have references. + if (const RecordType *RT = E->getType()->getAs<RecordType>()) { + if (!RT->isUnionType()) { + RecordDecl *SD = E->getType()->getAs<RecordType>()->getDecl(); + CharUnits NumNonZeroBytes = CharUnits::Zero(); + + unsigned ILEElement = 0; + if (auto *CXXRD = dyn_cast<CXXRecordDecl>(SD)) + while (ILEElement != CXXRD->getNumBases()) + NumNonZeroBytes += + GetNumNonZeroBytesInInit(ILE->getInit(ILEElement++), CGF); + for (const auto *Field : SD->fields()) { + // We're done once we hit the flexible array member or run out of + // InitListExpr elements. + if (Field->getType()->isIncompleteArrayType() || + ILEElement == ILE->getNumInits()) + break; + if (Field->isUnnamedBitfield()) + continue; + + const Expr *E = ILE->getInit(ILEElement++); + + // Reference values are always non-null and have the width of a pointer. + if (Field->getType()->isReferenceType()) + NumNonZeroBytes += CGF.getContext().toCharUnitsFromBits( + CGF.getTarget().getPointerWidth(0)); + else + NumNonZeroBytes += GetNumNonZeroBytesInInit(E, CGF); + } + + return NumNonZeroBytes; + } + } + + + CharUnits NumNonZeroBytes = CharUnits::Zero(); + for (unsigned i = 0, e = ILE->getNumInits(); i != e; ++i) + NumNonZeroBytes += GetNumNonZeroBytesInInit(ILE->getInit(i), CGF); + return NumNonZeroBytes; +} + +/// CheckAggExprForMemSetUse - If the initializer is large and has a lot of +/// zeros in it, emit a memset and avoid storing the individual zeros. +/// +static void CheckAggExprForMemSetUse(AggValueSlot &Slot, const Expr *E, + CodeGenFunction &CGF) { + // If the slot is already known to be zeroed, nothing to do. Don't mess with + // volatile stores. + if (Slot.isZeroed() || Slot.isVolatile() || !Slot.getAddress().isValid()) + return; + + // C++ objects with a user-declared constructor don't need zero'ing. + if (CGF.getLangOpts().CPlusPlus) + if (const RecordType *RT = CGF.getContext() + .getBaseElementType(E->getType())->getAs<RecordType>()) { + const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); + if (RD->hasUserDeclaredConstructor()) + return; + } + + // If the type is 16-bytes or smaller, prefer individual stores over memset. + CharUnits Size = Slot.getPreferredSize(CGF.getContext(), E->getType()); + if (Size <= CharUnits::fromQuantity(16)) + return; + + // Check to see if over 3/4 of the initializer are known to be zero. If so, + // we prefer to emit memset + individual stores for the rest. + CharUnits NumNonZeroBytes = GetNumNonZeroBytesInInit(E, CGF); + if (NumNonZeroBytes*4 > Size) + return; + + // Okay, it seems like a good idea to use an initial memset, emit the call. + llvm::Constant *SizeVal = CGF.Builder.getInt64(Size.getQuantity()); + + Address Loc = Slot.getAddress(); + Loc = CGF.Builder.CreateElementBitCast(Loc, CGF.Int8Ty); + CGF.Builder.CreateMemSet(Loc, CGF.Builder.getInt8(0), SizeVal, false); + + // Tell the AggExprEmitter that the slot is known zero. + Slot.setZeroed(); +} + + + + +/// EmitAggExpr - Emit the computation of the specified expression of aggregate +/// type. The result is computed into DestPtr. Note that if DestPtr is null, +/// the value of the aggregate expression is not needed. If VolatileDest is +/// true, DestPtr cannot be 0. +void CodeGenFunction::EmitAggExpr(const Expr *E, AggValueSlot Slot) { + assert(E && hasAggregateEvaluationKind(E->getType()) && + "Invalid aggregate expression to emit"); + assert((Slot.getAddress().isValid() || Slot.isIgnored()) && + "slot has bits but no address"); + + // Optimize the slot if possible. + CheckAggExprForMemSetUse(Slot, E, *this); + + AggExprEmitter(*this, Slot, Slot.isIgnored()).Visit(const_cast<Expr*>(E)); +} + +LValue CodeGenFunction::EmitAggExprToLValue(const Expr *E) { + assert(hasAggregateEvaluationKind(E->getType()) && "Invalid argument!"); + Address Temp = CreateMemTemp(E->getType()); + LValue LV = MakeAddrLValue(Temp, E->getType()); + EmitAggExpr(E, AggValueSlot::forLValue(LV, AggValueSlot::IsNotDestructed, + AggValueSlot::DoesNotNeedGCBarriers, + AggValueSlot::IsNotAliased, + AggValueSlot::DoesNotOverlap)); + return LV; +} + +AggValueSlot::Overlap_t +CodeGenFunction::getOverlapForFieldInit(const FieldDecl *FD) { + if (!FD->hasAttr<NoUniqueAddressAttr>() || !FD->getType()->isRecordType()) + return AggValueSlot::DoesNotOverlap; + + // If the field lies entirely within the enclosing class's nvsize, its tail + // padding cannot overlap any already-initialized object. (The only subobjects + // with greater addresses that might already be initialized are vbases.) + const RecordDecl *ClassRD = FD->getParent(); + const ASTRecordLayout &Layout = getContext().getASTRecordLayout(ClassRD); + if (Layout.getFieldOffset(FD->getFieldIndex()) + + getContext().getTypeSize(FD->getType()) <= + (uint64_t)getContext().toBits(Layout.getNonVirtualSize())) + return AggValueSlot::DoesNotOverlap; + + // The tail padding may contain values we need to preserve. + return AggValueSlot::MayOverlap; +} + +AggValueSlot::Overlap_t CodeGenFunction::getOverlapForBaseInit( + const CXXRecordDecl *RD, const CXXRecordDecl *BaseRD, bool IsVirtual) { + // If the most-derived object is a field declared with [[no_unique_address]], + // the tail padding of any virtual base could be reused for other subobjects + // of that field's class. + if (IsVirtual) + return AggValueSlot::MayOverlap; + + // If the base class is laid out entirely within the nvsize of the derived + // class, its tail padding cannot yet be initialized, so we can issue + // stores at the full width of the base class. + const ASTRecordLayout &Layout = getContext().getASTRecordLayout(RD); + if (Layout.getBaseClassOffset(BaseRD) + + getContext().getASTRecordLayout(BaseRD).getSize() <= + Layout.getNonVirtualSize()) + return AggValueSlot::DoesNotOverlap; + + // The tail padding may contain values we need to preserve. + return AggValueSlot::MayOverlap; +} + +void CodeGenFunction::EmitAggregateCopy(LValue Dest, LValue Src, QualType Ty, + AggValueSlot::Overlap_t MayOverlap, + bool isVolatile) { + assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex"); + + Address DestPtr = Dest.getAddress(); + Address SrcPtr = Src.getAddress(); + + if (getLangOpts().CPlusPlus) { + if (const RecordType *RT = Ty->getAs<RecordType>()) { + CXXRecordDecl *Record = cast<CXXRecordDecl>(RT->getDecl()); + assert((Record->hasTrivialCopyConstructor() || + Record->hasTrivialCopyAssignment() || + Record->hasTrivialMoveConstructor() || + Record->hasTrivialMoveAssignment() || + Record->isUnion()) && + "Trying to aggregate-copy a type without a trivial copy/move " + "constructor or assignment operator"); + // Ignore empty classes in C++. + if (Record->isEmpty()) + return; + } + } + + // Aggregate assignment turns into llvm.memcpy. This is almost valid per + // C99 6.5.16.1p3, which states "If the value being stored in an object is + // read from another object that overlaps in anyway the storage of the first + // object, then the overlap shall be exact and the two objects shall have + // qualified or unqualified versions of a compatible type." + // + // memcpy is not defined if the source and destination pointers are exactly + // equal, but other compilers do this optimization, and almost every memcpy + // implementation handles this case safely. If there is a libc that does not + // safely handle this, we can add a target hook. + + // Get data size info for this aggregate. Don't copy the tail padding if this + // might be a potentially-overlapping subobject, since the tail padding might + // be occupied by a different object. Otherwise, copying it is fine. + std::pair<CharUnits, CharUnits> TypeInfo; + if (MayOverlap) + TypeInfo = getContext().getTypeInfoDataSizeInChars(Ty); + else + TypeInfo = getContext().getTypeInfoInChars(Ty); + + llvm::Value *SizeVal = nullptr; + if (TypeInfo.first.isZero()) { + // But note that getTypeInfo returns 0 for a VLA. + if (auto *VAT = dyn_cast_or_null<VariableArrayType>( + getContext().getAsArrayType(Ty))) { + QualType BaseEltTy; + SizeVal = emitArrayLength(VAT, BaseEltTy, DestPtr); + TypeInfo = getContext().getTypeInfoInChars(BaseEltTy); + assert(!TypeInfo.first.isZero()); + SizeVal = Builder.CreateNUWMul( + SizeVal, + llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity())); + } + } + if (!SizeVal) { + SizeVal = llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity()); + } + + // FIXME: If we have a volatile struct, the optimizer can remove what might + // appear to be `extra' memory ops: + // + // volatile struct { int i; } a, b; + // + // int main() { + // a = b; + // a = b; + // } + // + // we need to use a different call here. We use isVolatile to indicate when + // either the source or the destination is volatile. + + DestPtr = Builder.CreateElementBitCast(DestPtr, Int8Ty); + SrcPtr = Builder.CreateElementBitCast(SrcPtr, Int8Ty); + + // Don't do any of the memmove_collectable tests if GC isn't set. + if (CGM.getLangOpts().getGC() == LangOptions::NonGC) { + // fall through + } else if (const RecordType *RecordTy = Ty->getAs<RecordType>()) { + RecordDecl *Record = RecordTy->getDecl(); + if (Record->hasObjectMember()) { + CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr, + SizeVal); + return; + } + } else if (Ty->isArrayType()) { + QualType BaseType = getContext().getBaseElementType(Ty); + if (const RecordType *RecordTy = BaseType->getAs<RecordType>()) { + if (RecordTy->getDecl()->hasObjectMember()) { + CGM.getObjCRuntime().EmitGCMemmoveCollectable(*this, DestPtr, SrcPtr, + SizeVal); + return; + } + } + } + + auto Inst = Builder.CreateMemCpy(DestPtr, SrcPtr, SizeVal, isVolatile); + + // Determine the metadata to describe the position of any padding in this + // memcpy, as well as the TBAA tags for the members of the struct, in case + // the optimizer wishes to expand it in to scalar memory operations. + if (llvm::MDNode *TBAAStructTag = CGM.getTBAAStructInfo(Ty)) + Inst->setMetadata(llvm::LLVMContext::MD_tbaa_struct, TBAAStructTag); + + if (CGM.getCodeGenOpts().NewStructPathTBAA) { + TBAAAccessInfo TBAAInfo = CGM.mergeTBAAInfoForMemoryTransfer( + Dest.getTBAAInfo(), Src.getTBAAInfo()); + CGM.DecorateInstructionWithTBAA(Inst, TBAAInfo); + } +} |