| //===--- CGExprAgg.cpp - Emit LLVM Code from Aggregate Expressions --------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This contains code to emit Aggregate Expr nodes as LLVM code. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "CodeGenFunction.h" |
| #include "CGObjCRuntime.h" |
| #include "CodeGenModule.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" |
| using namespace clang; |
| using namespace CodeGen; |
| |
| //===----------------------------------------------------------------------===// |
| // Aggregate Expression Emitter |
| //===----------------------------------------------------------------------===// |
| |
| namespace { |
| class AggExprEmitter : public StmtVisitor<AggExprEmitter> { |
| CodeGenFunction &CGF; |
| CGBuilderTy &Builder; |
| AggValueSlot Dest; |
| bool IsResultUnused; |
| |
| /// We want to use 'dest' as the return slot except under two |
| /// conditions: |
| /// - The destination slot requires garbage collection, so we |
| /// need to use the GC API. |
| /// - The destination slot is potentially aliased. |
| bool shouldUseDestForReturnSlot() const { |
| return !(Dest.requiresGCollection() || Dest.isPotentiallyAliased()); |
| } |
| |
| ReturnValueSlot getReturnValueSlot() const { |
| if (!shouldUseDestForReturnSlot()) |
| return ReturnValueSlot(); |
| |
| return ReturnValueSlot(Dest.getAddress(), Dest.isVolatile(), |
| 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"); |
| } |
| |
| 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); |
| |
| /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. |
| void EmitFinalDestCopy(QualType type, const LValue &src); |
| 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 elementType, 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 VisitUnaryExtension(UnaryOperator *E) { Visit(E->getSubExpr()); } |
| void VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *E) { |
| return Visit(E->getReplacement()); |
| } |
| |
| // l-values. |
| void VisitDeclRefExpr(DeclRefExpr *E) { |
| // For aggregates, we should always be able to emit the variable |
| // as an l-value unless it's a reference. This is due to the fact |
| // that we can't actually ever see a normal l2r conversion on an |
| // aggregate in C++, and in C there's no language standard |
| // actively preventing us from listing variables in the captures |
| // list of a block. |
| if (E->getDecl()->getType()->isReferenceType()) { |
| if (CodeGenFunction::ConstantEmission result |
| = CGF.tryEmitAsConstant(E)) { |
| EmitFinalDestCopy(E->getType(), result.getReferenceLValue(CGF, E)); |
| return; |
| } |
| } |
| |
| 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 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) { |
| Visit(DAE->getExpr()); |
| } |
| void VisitCXXDefaultInitExpr(CXXDefaultInitExpr *DIE) { |
| CodeGenFunction::CXXDefaultInitExprScope Scope(CGF); |
| 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); |
| } |
| |
| /// \brief 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(); |
| } |
| |
| /// \brief Perform the final move to DestPtr if for some reason |
| /// getReturnValueSlot() didn't use it directly. |
| /// |
| /// The idea is that you do something like this: |
| /// RValue Result = EmitSomething(..., getReturnValueSlot()); |
| /// EmitMoveFromReturnSlot(E, Result); |
| /// |
| /// If nothing interferes, this will cause the result to be emitted |
| /// directly into the return value slot. Otherwise, a final move |
| /// will be performed. |
| void AggExprEmitter::EmitMoveFromReturnSlot(const Expr *E, RValue src) { |
| if (shouldUseDestForReturnSlot()) { |
| // Logically, Dest.getAddr() should equal Src.getAggregateAddr(). |
| // The possibility of undef rvalues complicates that a lot, |
| // though, so we can't really assert. |
| return; |
| } |
| |
| // Otherwise, copy from there to the destination. |
| assert(Dest.getPointer() != src.getAggregatePointer()); |
| EmitFinalDestCopy(E->getType(), src); |
| } |
| |
| /// 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); |
| } |
| |
| /// EmitFinalDestCopy - Perform the final copy to DestPtr, if desired. |
| void AggExprEmitter::EmitFinalDestCopy(QualType type, const LValue &src) { |
| // 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; |
| |
| AggValueSlot srcAgg = |
| AggValueSlot::forLValue(src, AggValueSlot::IsDestructed, |
| needsGC(type), AggValueSlot::IsAliased); |
| 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 = CGF.getContext().getTypeSizeInChars(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. |
| CGF.EmitAggregateCopy(dest.getAddress(), src.getAddress(), type, |
| dest.isVolatile() || src.isVolatile()); |
| } |
| |
| /// \brief 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; |
| } |
| } |
| |
| /// \brief 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; |
| } |
| |
| /// \brief Emit initialization of an array from an initializer list. |
| void AggExprEmitter::EmitArrayInit(Address DestPtr, llvm::ArrayType *AType, |
| QualType elementType, InitListExpr *E) { |
| uint64_t NumInitElements = E->getNumInits(); |
| |
| uint64_t NumArrayElements = AType->getNumElements(); |
| assert(NumInitElements <= NumArrayElements); |
| |
| // 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); |
| |
| // 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. |
| 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) { |
| EmitFinalDestCopy(e->getType(), CGF.getOpaqueLValueMapping(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_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 intialize |
| // 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, |
| CharUnits()); |
| valueDest = AggValueSlot::forAddr(valueAddr, |
| valueDest.getQualifiers(), |
| valueDest.isExternallyDestructed(), |
| valueDest.requiresGCollection(), |
| valueDest.isPotentiallyAliased(), |
| 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, CharUnits()); |
| RValue rvalue = RValue::getAggregate(valueAddr, atomicSlot.isVolatile()); |
| return EmitFinalDestCopy(valueType, rvalue); |
| } |
| |
| 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()); |
| } |
| |
| // 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_ZeroToOCLEvent: |
| case CK_ZeroToOCLQueue: |
| case CK_AddressSpaceConversion: |
| case CK_IntToOCLSampler: |
| llvm_unreachable("cast kind invalid for aggregate types"); |
| } |
| } |
| |
| void AggExprEmitter::VisitCallExpr(const CallExpr *E) { |
| if (E->getCallReturnType(CGF.getContext())->isReferenceType()) { |
| EmitAggLoadOfLValue(E); |
| return; |
| } |
| |
| RValue RV = CGF.EmitCallExpr(E, getReturnValueSlot()); |
| EmitMoveFromReturnSlot(E, RV); |
| } |
| |
| void AggExprEmitter::VisitObjCMessageExpr(ObjCMessageExpr *E) { |
| RValue RV = CGF.EmitObjCMessageExpr(E, getReturnValueSlot()); |
| EmitMoveFromReturnSlot(E, RV); |
| } |
| |
| 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); |
| } |
| |
| 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), |
| 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); |
| // 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()); |
| CGF.EmitLambdaExpr(E, Slot); |
| } |
| |
| 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()); |
| // '\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, |
| 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()) { |
| QualType elementType = |
| CGF.getContext().getAsArrayType(E->getType())->getElementType(); |
| |
| auto AType = cast<llvm::ArrayType>(Dest.getAddress().getElementType()); |
| EmitArrayInit(Dest.getAddress(), AType, elementType, 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; |
| |
| 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.EmitAggExpr(E->getInit(curInitIndex++), AggSlot); |
| |
| if (QualType::DestructionKind dtorKind = |
| Base.getType().isDestructedType()) { |
| CGF.pushDestroy(dtorKind, V, Base.getType()); |
| cleanups.push_back(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 initalizers; 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)) { |
| if (!cleanupDominator) |
| cleanupDominator = CGF.Builder.CreateAlignedLoad( |
| CGF.Int8Ty, |
| llvm::Constant::getNullValue(CGF.Int8PtrTy), |
| CharUnits::One()); // placeholder |
| |
| CGF.pushDestroy(EHCleanup, LV.getAddress(), field->getType(), |
| CGF.getDestroyer(dtorKind), false); |
| cleanups.push_back(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. |
| 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); |
| 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); |
| 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 = CGF.getContext().getTypeSizeInChars(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)); |
| return LV; |
| } |
| |
| void CodeGenFunction::EmitAggregateCopy(Address DestPtr, |
| Address SrcPtr, QualType Ty, |
| bool isVolatile, |
| bool isAssignment) { |
| assert(!Ty->isAnyComplexType() && "Shouldn't happen for complex"); |
| |
| 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. If this is an assignment, |
| // don't copy the tail padding, because we might be assigning into a |
| // base subobject where the tail padding is claimed. Otherwise, |
| // copying it is fine. |
| std::pair<CharUnits, CharUnits> TypeInfo; |
| if (isAssignment) |
| 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().getTypeInfoDataSizeInChars(BaseEltTy); |
| std::pair<CharUnits, CharUnits> LastElementTypeInfo; |
| if (!isAssignment) |
| LastElementTypeInfo = getContext().getTypeInfoInChars(BaseEltTy); |
| assert(!TypeInfo.first.isZero()); |
| SizeVal = Builder.CreateNUWMul( |
| SizeVal, |
| llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity())); |
| if (!isAssignment) { |
| SizeVal = Builder.CreateNUWSub( |
| SizeVal, |
| llvm::ConstantInt::get(SizeTy, TypeInfo.first.getQuantity())); |
| SizeVal = Builder.CreateNUWAdd( |
| SizeVal, llvm::ConstantInt::get( |
| SizeTy, LastElementTypeInfo.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); |
| } |