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Diffstat (limited to 'contrib/llvm/tools/clang/lib/CodeGen/CGExprConstant.cpp')
| -rw-r--r-- | contrib/llvm/tools/clang/lib/CodeGen/CGExprConstant.cpp | 1355 |
1 files changed, 1355 insertions, 0 deletions
diff --git a/contrib/llvm/tools/clang/lib/CodeGen/CGExprConstant.cpp b/contrib/llvm/tools/clang/lib/CodeGen/CGExprConstant.cpp new file mode 100644 index 0000000..3997866 --- /dev/null +++ b/contrib/llvm/tools/clang/lib/CodeGen/CGExprConstant.cpp @@ -0,0 +1,1355 @@ +//===--- CGExprConstant.cpp - Emit LLVM Code from Constant 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 Constant Expr nodes as LLVM code. +// +//===----------------------------------------------------------------------===// + +#include "CodeGenFunction.h" +#include "CodeGenModule.h" +#include "CGCXXABI.h" +#include "CGObjCRuntime.h" +#include "CGRecordLayout.h" +#include "clang/AST/APValue.h" +#include "clang/AST/ASTContext.h" +#include "clang/AST/RecordLayout.h" +#include "clang/AST/StmtVisitor.h" +#include "clang/Basic/Builtins.h" +#include "llvm/Constants.h" +#include "llvm/Function.h" +#include "llvm/GlobalVariable.h" +#include "llvm/Target/TargetData.h" +using namespace clang; +using namespace CodeGen; + +//===----------------------------------------------------------------------===// +// ConstStructBuilder +//===----------------------------------------------------------------------===// + +namespace { +class ConstStructBuilder { + CodeGenModule &CGM; + CodeGenFunction *CGF; + + bool Packed; + CharUnits NextFieldOffsetInChars; + CharUnits LLVMStructAlignment; + std::vector<llvm::Constant *> Elements; +public: + static llvm::Constant *BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, + InitListExpr *ILE); + +private: + ConstStructBuilder(CodeGenModule &CGM, CodeGenFunction *CGF) + : CGM(CGM), CGF(CGF), Packed(false), + NextFieldOffsetInChars(CharUnits::Zero()), + LLVMStructAlignment(CharUnits::One()) { } + + bool AppendField(const FieldDecl *Field, uint64_t FieldOffset, + llvm::Constant *InitExpr); + + void AppendBitField(const FieldDecl *Field, uint64_t FieldOffset, + llvm::ConstantInt *InitExpr); + + void AppendPadding(CharUnits PadSize); + + void AppendTailPadding(CharUnits RecordSize); + + void ConvertStructToPacked(); + + bool Build(InitListExpr *ILE); + + CharUnits getAlignment(const llvm::Constant *C) const { + if (Packed) return CharUnits::One(); + return CharUnits::fromQuantity( + CGM.getTargetData().getABITypeAlignment(C->getType())); + } + + CharUnits getSizeInChars(const llvm::Constant *C) const { + return CharUnits::fromQuantity( + CGM.getTargetData().getTypeAllocSize(C->getType())); + } +}; + +bool ConstStructBuilder:: +AppendField(const FieldDecl *Field, uint64_t FieldOffset, + llvm::Constant *InitCst) { + + const ASTContext &Context = CGM.getContext(); + + CharUnits FieldOffsetInChars = Context.toCharUnitsFromBits(FieldOffset); + + assert(NextFieldOffsetInChars <= FieldOffsetInChars + && "Field offset mismatch!"); + + CharUnits FieldAlignment = getAlignment(InitCst); + + // Round up the field offset to the alignment of the field type. + CharUnits AlignedNextFieldOffsetInChars = + NextFieldOffsetInChars.RoundUpToAlignment(FieldAlignment); + + if (AlignedNextFieldOffsetInChars > FieldOffsetInChars) { + assert(!Packed && "Alignment is wrong even with a packed struct!"); + + // Convert the struct to a packed struct. + ConvertStructToPacked(); + + AlignedNextFieldOffsetInChars = NextFieldOffsetInChars; + } + + if (AlignedNextFieldOffsetInChars < FieldOffsetInChars) { + // We need to append padding. + AppendPadding( + FieldOffsetInChars - NextFieldOffsetInChars); + + assert(NextFieldOffsetInChars == FieldOffsetInChars && + "Did not add enough padding!"); + + AlignedNextFieldOffsetInChars = NextFieldOffsetInChars; + } + + // Add the field. + Elements.push_back(InitCst); + NextFieldOffsetInChars = AlignedNextFieldOffsetInChars + + getSizeInChars(InitCst); + + if (Packed) + assert(LLVMStructAlignment == CharUnits::One() && + "Packed struct not byte-aligned!"); + else + LLVMStructAlignment = std::max(LLVMStructAlignment, FieldAlignment); + + return true; +} + +void ConstStructBuilder::AppendBitField(const FieldDecl *Field, + uint64_t FieldOffset, + llvm::ConstantInt *CI) { + const ASTContext &Context = CGM.getContext(); + const uint64_t CharWidth = Context.getCharWidth(); + uint64_t NextFieldOffsetInBits = Context.toBits(NextFieldOffsetInChars); + if (FieldOffset > NextFieldOffsetInBits) { + // We need to add padding. + CharUnits PadSize = Context.toCharUnitsFromBits( + llvm::RoundUpToAlignment(FieldOffset - NextFieldOffsetInBits, + Context.getTargetInfo().getCharAlign())); + + AppendPadding(PadSize); + } + + uint64_t FieldSize = Field->getBitWidthValue(Context); + + llvm::APInt FieldValue = CI->getValue(); + + // Promote the size of FieldValue if necessary + // FIXME: This should never occur, but currently it can because initializer + // constants are cast to bool, and because clang is not enforcing bitfield + // width limits. + if (FieldSize > FieldValue.getBitWidth()) + FieldValue = FieldValue.zext(FieldSize); + + // Truncate the size of FieldValue to the bit field size. + if (FieldSize < FieldValue.getBitWidth()) + FieldValue = FieldValue.trunc(FieldSize); + + NextFieldOffsetInBits = Context.toBits(NextFieldOffsetInChars); + if (FieldOffset < NextFieldOffsetInBits) { + // Either part of the field or the entire field can go into the previous + // byte. + assert(!Elements.empty() && "Elements can't be empty!"); + + unsigned BitsInPreviousByte = NextFieldOffsetInBits - FieldOffset; + + bool FitsCompletelyInPreviousByte = + BitsInPreviousByte >= FieldValue.getBitWidth(); + + llvm::APInt Tmp = FieldValue; + + if (!FitsCompletelyInPreviousByte) { + unsigned NewFieldWidth = FieldSize - BitsInPreviousByte; + + if (CGM.getTargetData().isBigEndian()) { + Tmp = Tmp.lshr(NewFieldWidth); + Tmp = Tmp.trunc(BitsInPreviousByte); + + // We want the remaining high bits. + FieldValue = FieldValue.trunc(NewFieldWidth); + } else { + Tmp = Tmp.trunc(BitsInPreviousByte); + + // We want the remaining low bits. + FieldValue = FieldValue.lshr(BitsInPreviousByte); + FieldValue = FieldValue.trunc(NewFieldWidth); + } + } + + Tmp = Tmp.zext(CharWidth); + if (CGM.getTargetData().isBigEndian()) { + if (FitsCompletelyInPreviousByte) + Tmp = Tmp.shl(BitsInPreviousByte - FieldValue.getBitWidth()); + } else { + Tmp = Tmp.shl(CharWidth - BitsInPreviousByte); + } + + // 'or' in the bits that go into the previous byte. + llvm::Value *LastElt = Elements.back(); + if (llvm::ConstantInt *Val = dyn_cast<llvm::ConstantInt>(LastElt)) + Tmp |= Val->getValue(); + else { + assert(isa<llvm::UndefValue>(LastElt)); + // If there is an undef field that we're adding to, it can either be a + // scalar undef (in which case, we just replace it with our field) or it + // is an array. If it is an array, we have to pull one byte off the + // array so that the other undef bytes stay around. + if (!isa<llvm::IntegerType>(LastElt->getType())) { + // The undef padding will be a multibyte array, create a new smaller + // padding and then an hole for our i8 to get plopped into. + assert(isa<llvm::ArrayType>(LastElt->getType()) && + "Expected array padding of undefs"); + llvm::ArrayType *AT = cast<llvm::ArrayType>(LastElt->getType()); + assert(AT->getElementType()->isIntegerTy(CharWidth) && + AT->getNumElements() != 0 && + "Expected non-empty array padding of undefs"); + + // Remove the padding array. + NextFieldOffsetInChars -= CharUnits::fromQuantity(AT->getNumElements()); + Elements.pop_back(); + + // Add the padding back in two chunks. + AppendPadding(CharUnits::fromQuantity(AT->getNumElements()-1)); + AppendPadding(CharUnits::One()); + assert(isa<llvm::UndefValue>(Elements.back()) && + Elements.back()->getType()->isIntegerTy(CharWidth) && + "Padding addition didn't work right"); + } + } + + Elements.back() = llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp); + + if (FitsCompletelyInPreviousByte) + return; + } + + while (FieldValue.getBitWidth() > CharWidth) { + llvm::APInt Tmp; + + if (CGM.getTargetData().isBigEndian()) { + // We want the high bits. + Tmp = + FieldValue.lshr(FieldValue.getBitWidth() - CharWidth).trunc(CharWidth); + } else { + // We want the low bits. + Tmp = FieldValue.trunc(CharWidth); + + FieldValue = FieldValue.lshr(CharWidth); + } + + Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), Tmp)); + ++NextFieldOffsetInChars; + + FieldValue = FieldValue.trunc(FieldValue.getBitWidth() - CharWidth); + } + + assert(FieldValue.getBitWidth() > 0 && + "Should have at least one bit left!"); + assert(FieldValue.getBitWidth() <= CharWidth && + "Should not have more than a byte left!"); + + if (FieldValue.getBitWidth() < CharWidth) { + if (CGM.getTargetData().isBigEndian()) { + unsigned BitWidth = FieldValue.getBitWidth(); + + FieldValue = FieldValue.zext(CharWidth) << (CharWidth - BitWidth); + } else + FieldValue = FieldValue.zext(CharWidth); + } + + // Append the last element. + Elements.push_back(llvm::ConstantInt::get(CGM.getLLVMContext(), + FieldValue)); + ++NextFieldOffsetInChars; +} + +void ConstStructBuilder::AppendPadding(CharUnits PadSize) { + if (PadSize.isZero()) + return; + + llvm::Type *Ty = llvm::Type::getInt8Ty(CGM.getLLVMContext()); + if (PadSize > CharUnits::One()) + Ty = llvm::ArrayType::get(Ty, PadSize.getQuantity()); + + llvm::Constant *C = llvm::UndefValue::get(Ty); + Elements.push_back(C); + assert(getAlignment(C) == CharUnits::One() && + "Padding must have 1 byte alignment!"); + + NextFieldOffsetInChars += getSizeInChars(C); +} + +void ConstStructBuilder::AppendTailPadding(CharUnits RecordSize) { + assert(NextFieldOffsetInChars <= RecordSize && + "Size mismatch!"); + + AppendPadding(RecordSize - NextFieldOffsetInChars); +} + +void ConstStructBuilder::ConvertStructToPacked() { + std::vector<llvm::Constant *> PackedElements; + CharUnits ElementOffsetInChars = CharUnits::Zero(); + + for (unsigned i = 0, e = Elements.size(); i != e; ++i) { + llvm::Constant *C = Elements[i]; + + CharUnits ElementAlign = CharUnits::fromQuantity( + CGM.getTargetData().getABITypeAlignment(C->getType())); + CharUnits AlignedElementOffsetInChars = + ElementOffsetInChars.RoundUpToAlignment(ElementAlign); + + if (AlignedElementOffsetInChars > ElementOffsetInChars) { + // We need some padding. + CharUnits NumChars = + AlignedElementOffsetInChars - ElementOffsetInChars; + + llvm::Type *Ty = llvm::Type::getInt8Ty(CGM.getLLVMContext()); + if (NumChars > CharUnits::One()) + Ty = llvm::ArrayType::get(Ty, NumChars.getQuantity()); + + llvm::Constant *Padding = llvm::UndefValue::get(Ty); + PackedElements.push_back(Padding); + ElementOffsetInChars += getSizeInChars(Padding); + } + + PackedElements.push_back(C); + ElementOffsetInChars += getSizeInChars(C); + } + + assert(ElementOffsetInChars == NextFieldOffsetInChars && + "Packing the struct changed its size!"); + + Elements = PackedElements; + LLVMStructAlignment = CharUnits::One(); + Packed = true; +} + +bool ConstStructBuilder::Build(InitListExpr *ILE) { + RecordDecl *RD = ILE->getType()->getAs<RecordType>()->getDecl(); + const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); + + unsigned FieldNo = 0; + unsigned ElementNo = 0; + const FieldDecl *LastFD = 0; + bool IsMsStruct = RD->hasAttr<MsStructAttr>(); + + for (RecordDecl::field_iterator Field = RD->field_begin(), + FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) { + if (IsMsStruct) { + // Zero-length bitfields following non-bitfield members are + // ignored: + if (CGM.getContext().ZeroBitfieldFollowsNonBitfield((*Field), LastFD)) { + --FieldNo; + continue; + } + LastFD = (*Field); + } + + // If this is a union, skip all the fields that aren't being initialized. + if (RD->isUnion() && ILE->getInitializedFieldInUnion() != *Field) + continue; + + // Don't emit anonymous bitfields, they just affect layout. + if (Field->isUnnamedBitfield()) { + LastFD = (*Field); + continue; + } + + // Get the initializer. A struct can include fields without initializers, + // we just use explicit null values for them. + llvm::Constant *EltInit; + if (ElementNo < ILE->getNumInits()) + EltInit = CGM.EmitConstantExpr(ILE->getInit(ElementNo++), + Field->getType(), CGF); + else + EltInit = CGM.EmitNullConstant(Field->getType()); + + if (!EltInit) + return false; + + if (!Field->isBitField()) { + // Handle non-bitfield members. + if (!AppendField(*Field, Layout.getFieldOffset(FieldNo), EltInit)) + return false; + } else { + // Otherwise we have a bitfield. + AppendBitField(*Field, Layout.getFieldOffset(FieldNo), + cast<llvm::ConstantInt>(EltInit)); + } + } + + CharUnits LayoutSizeInChars = Layout.getSize(); + + if (NextFieldOffsetInChars > LayoutSizeInChars) { + // If the struct is bigger than the size of the record type, + // we must have a flexible array member at the end. + assert(RD->hasFlexibleArrayMember() && + "Must have flexible array member if struct is bigger than type!"); + + // No tail padding is necessary. + return true; + } + + CharUnits LLVMSizeInChars = + NextFieldOffsetInChars.RoundUpToAlignment(LLVMStructAlignment); + + // Check if we need to convert the struct to a packed struct. + if (NextFieldOffsetInChars <= LayoutSizeInChars && + LLVMSizeInChars > LayoutSizeInChars) { + assert(!Packed && "Size mismatch!"); + + ConvertStructToPacked(); + assert(NextFieldOffsetInChars <= LayoutSizeInChars && + "Converting to packed did not help!"); + } + + // Append tail padding if necessary. + AppendTailPadding(LayoutSizeInChars); + + assert(LayoutSizeInChars == NextFieldOffsetInChars && + "Tail padding mismatch!"); + + return true; +} + +llvm::Constant *ConstStructBuilder:: + BuildStruct(CodeGenModule &CGM, CodeGenFunction *CGF, InitListExpr *ILE) { + ConstStructBuilder Builder(CGM, CGF); + + if (!Builder.Build(ILE)) + return 0; + + // Pick the type to use. If the type is layout identical to the ConvertType + // type then use it, otherwise use whatever the builder produced for us. + llvm::StructType *STy = + llvm::ConstantStruct::getTypeForElements(CGM.getLLVMContext(), + Builder.Elements,Builder.Packed); + llvm::Type *ILETy = CGM.getTypes().ConvertType(ILE->getType()); + if (llvm::StructType *ILESTy = dyn_cast<llvm::StructType>(ILETy)) { + if (ILESTy->isLayoutIdentical(STy)) + STy = ILESTy; + } + + llvm::Constant *Result = + llvm::ConstantStruct::get(STy, Builder.Elements); + + assert(Builder.NextFieldOffsetInChars.RoundUpToAlignment( + Builder.getAlignment(Result)) == + Builder.getSizeInChars(Result) && "Size mismatch!"); + + return Result; +} + + +//===----------------------------------------------------------------------===// +// ConstExprEmitter +//===----------------------------------------------------------------------===// + +class ConstExprEmitter : + public StmtVisitor<ConstExprEmitter, llvm::Constant*> { + CodeGenModule &CGM; + CodeGenFunction *CGF; + llvm::LLVMContext &VMContext; +public: + ConstExprEmitter(CodeGenModule &cgm, CodeGenFunction *cgf) + : CGM(cgm), CGF(cgf), VMContext(cgm.getLLVMContext()) { + } + + //===--------------------------------------------------------------------===// + // Visitor Methods + //===--------------------------------------------------------------------===// + + llvm::Constant *VisitStmt(Stmt *S) { + return 0; + } + + llvm::Constant *VisitParenExpr(ParenExpr *PE) { + return Visit(PE->getSubExpr()); + } + + llvm::Constant * + VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *PE) { + return Visit(PE->getReplacement()); + } + + llvm::Constant *VisitGenericSelectionExpr(GenericSelectionExpr *GE) { + return Visit(GE->getResultExpr()); + } + + llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E) { + return Visit(E->getInitializer()); + } + + llvm::Constant *VisitUnaryAddrOf(UnaryOperator *E) { + if (E->getType()->isMemberPointerType()) + return CGM.getMemberPointerConstant(E); + + return 0; + } + + llvm::Constant *VisitBinSub(BinaryOperator *E) { + // This must be a pointer/pointer subtraction. This only happens for + // address of label. + if (!isa<AddrLabelExpr>(E->getLHS()->IgnoreParenNoopCasts(CGM.getContext())) || + !isa<AddrLabelExpr>(E->getRHS()->IgnoreParenNoopCasts(CGM.getContext()))) + return 0; + + llvm::Constant *LHS = CGM.EmitConstantExpr(E->getLHS(), + E->getLHS()->getType(), CGF); + llvm::Constant *RHS = CGM.EmitConstantExpr(E->getRHS(), + E->getRHS()->getType(), CGF); + + llvm::Type *ResultType = ConvertType(E->getType()); + LHS = llvm::ConstantExpr::getPtrToInt(LHS, ResultType); + RHS = llvm::ConstantExpr::getPtrToInt(RHS, ResultType); + + // No need to divide by element size, since addr of label is always void*, + // which has size 1 in GNUish. + return llvm::ConstantExpr::getSub(LHS, RHS); + } + + llvm::Constant *VisitCastExpr(CastExpr* E) { + Expr *subExpr = E->getSubExpr(); + llvm::Constant *C = CGM.EmitConstantExpr(subExpr, subExpr->getType(), CGF); + if (!C) return 0; + + llvm::Type *destType = ConvertType(E->getType()); + + switch (E->getCastKind()) { + case CK_ToUnion: { + // GCC cast to union extension + assert(E->getType()->isUnionType() && + "Destination type is not union type!"); + + // Build a struct with the union sub-element as the first member, + // and padded to the appropriate size + std::vector<llvm::Constant*> Elts; + std::vector<llvm::Type*> Types; + Elts.push_back(C); + Types.push_back(C->getType()); + unsigned CurSize = CGM.getTargetData().getTypeAllocSize(C->getType()); + unsigned TotalSize = CGM.getTargetData().getTypeAllocSize(destType); + + assert(CurSize <= TotalSize && "Union size mismatch!"); + if (unsigned NumPadBytes = TotalSize - CurSize) { + llvm::Type *Ty = llvm::Type::getInt8Ty(VMContext); + if (NumPadBytes > 1) + Ty = llvm::ArrayType::get(Ty, NumPadBytes); + + Elts.push_back(llvm::UndefValue::get(Ty)); + Types.push_back(Ty); + } + + llvm::StructType* STy = + llvm::StructType::get(C->getType()->getContext(), Types, false); + return llvm::ConstantStruct::get(STy, Elts); + } + case CK_NullToMemberPointer: { + const MemberPointerType *MPT = E->getType()->getAs<MemberPointerType>(); + return CGM.getCXXABI().EmitNullMemberPointer(MPT); + } + + case CK_DerivedToBaseMemberPointer: + case CK_BaseToDerivedMemberPointer: + return CGM.getCXXABI().EmitMemberPointerConversion(C, E); + + case CK_LValueToRValue: + case CK_NoOp: + return C; + + case CK_CPointerToObjCPointerCast: + case CK_BlockPointerToObjCPointerCast: + case CK_AnyPointerToBlockPointerCast: + case CK_LValueBitCast: + case CK_BitCast: + if (C->getType() == destType) return C; + return llvm::ConstantExpr::getBitCast(C, destType); + + case CK_Dependent: llvm_unreachable("saw dependent cast!"); + + // These will never be supported. + case CK_ObjCObjectLValueCast: + case CK_GetObjCProperty: + case CK_ToVoid: + case CK_Dynamic: + case CK_ARCProduceObject: + case CK_ARCConsumeObject: + case CK_ARCReclaimReturnedObject: + case CK_ARCExtendBlockObject: + return 0; + + // These might need to be supported for constexpr. + case CK_UserDefinedConversion: + case CK_ConstructorConversion: + return 0; + + // These should eventually be supported. + case CK_ArrayToPointerDecay: + case CK_FunctionToPointerDecay: + case CK_BaseToDerived: + case CK_DerivedToBase: + case CK_UncheckedDerivedToBase: + case CK_MemberPointerToBoolean: + case CK_VectorSplat: + 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: + return 0; + + case CK_PointerToIntegral: + if (!E->getType()->isBooleanType()) + return llvm::ConstantExpr::getPtrToInt(C, destType); + // fallthrough + + case CK_PointerToBoolean: + return llvm::ConstantExpr::getICmp(llvm::CmpInst::ICMP_EQ, C, + llvm::ConstantPointerNull::get(cast<llvm::PointerType>(C->getType()))); + + case CK_NullToPointer: + return llvm::ConstantPointerNull::get(cast<llvm::PointerType>(destType)); + + case CK_IntegralCast: { + bool isSigned = subExpr->getType()->isSignedIntegerOrEnumerationType(); + return llvm::ConstantExpr::getIntegerCast(C, destType, isSigned); + } + + case CK_IntegralToPointer: { + bool isSigned = subExpr->getType()->isSignedIntegerOrEnumerationType(); + C = llvm::ConstantExpr::getIntegerCast(C, CGM.IntPtrTy, isSigned); + return llvm::ConstantExpr::getIntToPtr(C, destType); + } + + case CK_IntegralToBoolean: + return llvm::ConstantExpr::getICmp(llvm::CmpInst::ICMP_EQ, C, + llvm::Constant::getNullValue(C->getType())); + + case CK_IntegralToFloating: + if (subExpr->getType()->isSignedIntegerOrEnumerationType()) + return llvm::ConstantExpr::getSIToFP(C, destType); + else + return llvm::ConstantExpr::getUIToFP(C, destType); + + case CK_FloatingToIntegral: + if (E->getType()->isSignedIntegerOrEnumerationType()) + return llvm::ConstantExpr::getFPToSI(C, destType); + else + return llvm::ConstantExpr::getFPToUI(C, destType); + + case CK_FloatingToBoolean: + return llvm::ConstantExpr::getFCmp(llvm::CmpInst::FCMP_UNE, C, + llvm::Constant::getNullValue(C->getType())); + + case CK_FloatingCast: + return llvm::ConstantExpr::getFPCast(C, destType); + } + llvm_unreachable("Invalid CastKind"); + } + + llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE) { + return Visit(DAE->getExpr()); + } + + llvm::Constant *VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E) { + return Visit(E->GetTemporaryExpr()); + } + + llvm::Constant *EmitArrayInitialization(InitListExpr *ILE) { + unsigned NumInitElements = ILE->getNumInits(); + if (NumInitElements == 1 && ILE->getType() == ILE->getInit(0)->getType() && + (isa<StringLiteral>(ILE->getInit(0)) || + isa<ObjCEncodeExpr>(ILE->getInit(0)))) + return Visit(ILE->getInit(0)); + + std::vector<llvm::Constant*> Elts; + llvm::ArrayType *AType = + cast<llvm::ArrayType>(ConvertType(ILE->getType())); + llvm::Type *ElemTy = AType->getElementType(); + unsigned NumElements = AType->getNumElements(); + + // Initialising an array requires us to automatically + // initialise any elements that have not been initialised explicitly + unsigned NumInitableElts = std::min(NumInitElements, NumElements); + + // Copy initializer elements. + unsigned i = 0; + bool RewriteType = false; + for (; i < NumInitableElts; ++i) { + Expr *Init = ILE->getInit(i); + llvm::Constant *C = CGM.EmitConstantExpr(Init, Init->getType(), CGF); + if (!C) + return 0; + RewriteType |= (C->getType() != ElemTy); + Elts.push_back(C); + } + + // Initialize remaining array elements. + // FIXME: This doesn't handle member pointers correctly! + llvm::Constant *fillC; + if (Expr *filler = ILE->getArrayFiller()) + fillC = CGM.EmitConstantExpr(filler, filler->getType(), CGF); + else + fillC = llvm::Constant::getNullValue(ElemTy); + if (!fillC) + return 0; + RewriteType |= (fillC->getType() != ElemTy); + for (; i < NumElements; ++i) + Elts.push_back(fillC); + + if (RewriteType) { + // FIXME: Try to avoid packing the array + std::vector<llvm::Type*> Types; + for (unsigned i = 0; i < Elts.size(); ++i) + Types.push_back(Elts[i]->getType()); + llvm::StructType *SType = llvm::StructType::get(AType->getContext(), + Types, true); + return llvm::ConstantStruct::get(SType, Elts); + } + + return llvm::ConstantArray::get(AType, Elts); + } + + llvm::Constant *EmitStructInitialization(InitListExpr *ILE) { + return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); + } + + llvm::Constant *EmitUnionInitialization(InitListExpr *ILE) { + return ConstStructBuilder::BuildStruct(CGM, CGF, ILE); + } + + llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E) { + return CGM.EmitNullConstant(E->getType()); + } + + llvm::Constant *VisitInitListExpr(InitListExpr *ILE) { + if (ILE->getType()->isAnyComplexType() && ILE->getNumInits() == 2) { + // Complex type with element initializers + Expr *Real = ILE->getInit(0); + Expr *Imag = ILE->getInit(1); + llvm::Constant *Complex[2]; + Complex[0] = CGM.EmitConstantExpr(Real, Real->getType(), CGF); + if (!Complex[0]) + return 0; + Complex[1] = CGM.EmitConstantExpr(Imag, Imag->getType(), CGF); + if (!Complex[1]) + return 0; + llvm::StructType *STy = + cast<llvm::StructType>(ConvertType(ILE->getType())); + return llvm::ConstantStruct::get(STy, Complex); + } + + if (ILE->getType()->isScalarType()) { + // We have a scalar in braces. Just use the first element. + if (ILE->getNumInits() > 0) { + Expr *Init = ILE->getInit(0); + return CGM.EmitConstantExpr(Init, Init->getType(), CGF); + } + return CGM.EmitNullConstant(ILE->getType()); + } + + if (ILE->getType()->isArrayType()) + return EmitArrayInitialization(ILE); + + if (ILE->getType()->isRecordType()) + return EmitStructInitialization(ILE); + + if (ILE->getType()->isUnionType()) + return EmitUnionInitialization(ILE); + + // If ILE was a constant vector, we would have handled it already. + if (ILE->getType()->isVectorType()) + return 0; + + llvm_unreachable("Unable to handle InitListExpr"); + } + + llvm::Constant *VisitCXXConstructExpr(CXXConstructExpr *E) { + if (!E->getConstructor()->isTrivial()) + return 0; + + QualType Ty = E->getType(); + + // FIXME: We should not have to call getBaseElementType here. + const RecordType *RT = + CGM.getContext().getBaseElementType(Ty)->getAs<RecordType>(); + const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); + + // If the class doesn't have a trivial destructor, we can't emit it as a + // constant expr. + if (!RD->hasTrivialDestructor()) + return 0; + + // Only copy and default constructors can be trivial. + + + if (E->getNumArgs()) { + assert(E->getNumArgs() == 1 && "trivial ctor with > 1 argument"); + assert(E->getConstructor()->isCopyOrMoveConstructor() && + "trivial ctor has argument but isn't a copy/move ctor"); + + Expr *Arg = E->getArg(0); + assert(CGM.getContext().hasSameUnqualifiedType(Ty, Arg->getType()) && + "argument to copy ctor is of wrong type"); + + return Visit(Arg); + } + + return CGM.EmitNullConstant(Ty); + } + + llvm::Constant *VisitStringLiteral(StringLiteral *E) { + assert(!E->getType()->isPointerType() && "Strings are always arrays"); + + // This must be a string initializing an array in a static initializer. + // Don't emit it as the address of the string, emit the string data itself + // as an inline array. + return llvm::ConstantArray::get(VMContext, + CGM.GetStringForStringLiteral(E), false); + } + + llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E) { + // This must be an @encode initializing an array in a static initializer. + // Don't emit it as the address of the string, emit the string data itself + // as an inline array. + std::string Str; + CGM.getContext().getObjCEncodingForType(E->getEncodedType(), Str); + const ConstantArrayType *CAT = cast<ConstantArrayType>(E->getType()); + + // Resize the string to the right size, adding zeros at the end, or + // truncating as needed. + Str.resize(CAT->getSize().getZExtValue(), '\0'); + return llvm::ConstantArray::get(VMContext, Str, false); + } + + llvm::Constant *VisitUnaryExtension(const UnaryOperator *E) { + return Visit(E->getSubExpr()); + } + + // Utility methods + llvm::Type *ConvertType(QualType T) { + return CGM.getTypes().ConvertType(T); + } + +public: + llvm::Constant *EmitLValue(Expr *E) { + switch (E->getStmtClass()) { + default: break; + case Expr::CompoundLiteralExprClass: { + // Note that due to the nature of compound literals, this is guaranteed + // to be the only use of the variable, so we just generate it here. + CompoundLiteralExpr *CLE = cast<CompoundLiteralExpr>(E); + llvm::Constant* C = Visit(CLE->getInitializer()); + // FIXME: "Leaked" on failure. + if (C) + C = new llvm::GlobalVariable(CGM.getModule(), C->getType(), + E->getType().isConstant(CGM.getContext()), + llvm::GlobalValue::InternalLinkage, + C, ".compoundliteral", 0, false, + CGM.getContext().getTargetAddressSpace(E->getType())); + return C; + } + case Expr::DeclRefExprClass: { + ValueDecl *Decl = cast<DeclRefExpr>(E)->getDecl(); + if (Decl->hasAttr<WeakRefAttr>()) + return CGM.GetWeakRefReference(Decl); + if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(Decl)) + return CGM.GetAddrOfFunction(FD); + if (const VarDecl* VD = dyn_cast<VarDecl>(Decl)) { + // We can never refer to a variable with local storage. + if (!VD->hasLocalStorage()) { + if (VD->isFileVarDecl() || VD->hasExternalStorage()) + return CGM.GetAddrOfGlobalVar(VD); + else if (VD->isLocalVarDecl()) { + assert(CGF && "Can't access static local vars without CGF"); + return CGF->GetAddrOfStaticLocalVar(VD); + } + } + } + break; + } + case Expr::StringLiteralClass: + return CGM.GetAddrOfConstantStringFromLiteral(cast<StringLiteral>(E)); + case Expr::ObjCEncodeExprClass: + return CGM.GetAddrOfConstantStringFromObjCEncode(cast<ObjCEncodeExpr>(E)); + case Expr::ObjCStringLiteralClass: { + ObjCStringLiteral* SL = cast<ObjCStringLiteral>(E); + llvm::Constant *C = + CGM.getObjCRuntime().GenerateConstantString(SL->getString()); + return llvm::ConstantExpr::getBitCast(C, ConvertType(E->getType())); + } + case Expr::PredefinedExprClass: { + unsigned Type = cast<PredefinedExpr>(E)->getIdentType(); + if (CGF) { + LValue Res = CGF->EmitPredefinedLValue(cast<PredefinedExpr>(E)); + return cast<llvm::Constant>(Res.getAddress()); + } else if (Type == PredefinedExpr::PrettyFunction) { + return CGM.GetAddrOfConstantCString("top level", ".tmp"); + } + + return CGM.GetAddrOfConstantCString("", ".tmp"); + } + case Expr::AddrLabelExprClass: { + assert(CGF && "Invalid address of label expression outside function."); + llvm::Constant *Ptr = + CGF->GetAddrOfLabel(cast<AddrLabelExpr>(E)->getLabel()); + return llvm::ConstantExpr::getBitCast(Ptr, ConvertType(E->getType())); + } + case Expr::CallExprClass: { + CallExpr* CE = cast<CallExpr>(E); + unsigned builtin = CE->isBuiltinCall(CGM.getContext()); + if (builtin != + Builtin::BI__builtin___CFStringMakeConstantString && + builtin != + Builtin::BI__builtin___NSStringMakeConstantString) + break; + const Expr *Arg = CE->getArg(0)->IgnoreParenCasts(); + const StringLiteral *Literal = cast<StringLiteral>(Arg); + if (builtin == + Builtin::BI__builtin___NSStringMakeConstantString) { + return CGM.getObjCRuntime().GenerateConstantString(Literal); + } + // FIXME: need to deal with UCN conversion issues. + return CGM.GetAddrOfConstantCFString(Literal); + } + case Expr::BlockExprClass: { + std::string FunctionName; + if (CGF) + FunctionName = CGF->CurFn->getName(); + else + FunctionName = "global"; + + return CGM.GetAddrOfGlobalBlock(cast<BlockExpr>(E), FunctionName.c_str()); + } + } + + return 0; + } +}; + +} // end anonymous namespace. + +llvm::Constant *CodeGenModule::EmitConstantExpr(const Expr *E, + QualType DestType, + CodeGenFunction *CGF) { + Expr::EvalResult Result; + + bool Success = false; + + if (DestType->isReferenceType()) + Success = E->EvaluateAsLValue(Result, Context); + else + Success = E->Evaluate(Result, Context); + + if (Success && !Result.HasSideEffects) { + switch (Result.Val.getKind()) { + case APValue::Uninitialized: + llvm_unreachable("Constant expressions should be initialized."); + case APValue::LValue: { + llvm::Type *DestTy = getTypes().ConvertTypeForMem(DestType); + llvm::Constant *Offset = + llvm::ConstantInt::get(llvm::Type::getInt64Ty(VMContext), + Result.Val.getLValueOffset().getQuantity()); + + llvm::Constant *C; + if (const Expr *LVBase = Result.Val.getLValueBase()) { + C = ConstExprEmitter(*this, CGF).EmitLValue(const_cast<Expr*>(LVBase)); + + // Apply offset if necessary. + if (!Offset->isNullValue()) { + llvm::Type *Type = llvm::Type::getInt8PtrTy(VMContext); + llvm::Constant *Casted = llvm::ConstantExpr::getBitCast(C, Type); + Casted = llvm::ConstantExpr::getGetElementPtr(Casted, Offset); + C = llvm::ConstantExpr::getBitCast(Casted, C->getType()); + } + + // Convert to the appropriate type; this could be an lvalue for + // an integer. + if (isa<llvm::PointerType>(DestTy)) + return llvm::ConstantExpr::getBitCast(C, DestTy); + + return llvm::ConstantExpr::getPtrToInt(C, DestTy); + } else { + C = Offset; + + // Convert to the appropriate type; this could be an lvalue for + // an integer. + if (isa<llvm::PointerType>(DestTy)) + return llvm::ConstantExpr::getIntToPtr(C, DestTy); + + // If the types don't match this should only be a truncate. + if (C->getType() != DestTy) + return llvm::ConstantExpr::getTrunc(C, DestTy); + + return C; + } + } + case APValue::Int: { + llvm::Constant *C = llvm::ConstantInt::get(VMContext, + Result.Val.getInt()); + + if (C->getType()->isIntegerTy(1)) { + llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); + C = llvm::ConstantExpr::getZExt(C, BoolTy); + } + return C; + } + case APValue::ComplexInt: { + llvm::Constant *Complex[2]; + + Complex[0] = llvm::ConstantInt::get(VMContext, + Result.Val.getComplexIntReal()); + Complex[1] = llvm::ConstantInt::get(VMContext, + Result.Val.getComplexIntImag()); + + // FIXME: the target may want to specify that this is packed. + llvm::StructType *STy = llvm::StructType::get(Complex[0]->getType(), + Complex[1]->getType(), + NULL); + return llvm::ConstantStruct::get(STy, Complex); + } + case APValue::Float: { + const llvm::APFloat &Init = Result.Val.getFloat(); + if (&Init.getSemantics() == &llvm::APFloat::IEEEhalf) + return llvm::ConstantInt::get(VMContext, Init.bitcastToAPInt()); + else + return llvm::ConstantFP::get(VMContext, Init); + } + case APValue::ComplexFloat: { + llvm::Constant *Complex[2]; + + Complex[0] = llvm::ConstantFP::get(VMContext, + Result.Val.getComplexFloatReal()); + Complex[1] = llvm::ConstantFP::get(VMContext, + Result.Val.getComplexFloatImag()); + + // FIXME: the target may want to specify that this is packed. + llvm::StructType *STy = llvm::StructType::get(Complex[0]->getType(), + Complex[1]->getType(), + NULL); + return llvm::ConstantStruct::get(STy, Complex); + } + case APValue::Vector: { + SmallVector<llvm::Constant *, 4> Inits; + unsigned NumElts = Result.Val.getVectorLength(); + + if (Context.getLangOptions().AltiVec && + isa<CastExpr>(E) && + cast<CastExpr>(E)->getCastKind() == CK_VectorSplat) { + // AltiVec vector initialization with a single literal + APValue &Elt = Result.Val.getVectorElt(0); + + llvm::Constant* InitValue = Elt.isInt() + ? cast<llvm::Constant> + (llvm::ConstantInt::get(VMContext, Elt.getInt())) + : cast<llvm::Constant> + (llvm::ConstantFP::get(VMContext, Elt.getFloat())); + + for (unsigned i = 0; i != NumElts; ++i) + Inits.push_back(InitValue); + + } else { + for (unsigned i = 0; i != NumElts; ++i) { + APValue &Elt = Result.Val.getVectorElt(i); + if (Elt.isInt()) + Inits.push_back(llvm::ConstantInt::get(VMContext, Elt.getInt())); + else + Inits.push_back(llvm::ConstantFP::get(VMContext, Elt.getFloat())); + } + } + return llvm::ConstantVector::get(Inits); + } + } + } + + llvm::Constant* C = ConstExprEmitter(*this, CGF).Visit(const_cast<Expr*>(E)); + if (C && C->getType()->isIntegerTy(1)) { + llvm::Type *BoolTy = getTypes().ConvertTypeForMem(E->getType()); + C = llvm::ConstantExpr::getZExt(C, BoolTy); + } + return C; +} + +static uint64_t getFieldOffset(ASTContext &C, const FieldDecl *field) { + const ASTRecordLayout &layout = C.getASTRecordLayout(field->getParent()); + return layout.getFieldOffset(field->getFieldIndex()); +} + +llvm::Constant * +CodeGenModule::getMemberPointerConstant(const UnaryOperator *uo) { + // Member pointer constants always have a very particular form. + const MemberPointerType *type = cast<MemberPointerType>(uo->getType()); + const ValueDecl *decl = cast<DeclRefExpr>(uo->getSubExpr())->getDecl(); + + // A member function pointer. + if (const CXXMethodDecl *method = dyn_cast<CXXMethodDecl>(decl)) + return getCXXABI().EmitMemberPointer(method); + + // Otherwise, a member data pointer. + uint64_t fieldOffset; + if (const FieldDecl *field = dyn_cast<FieldDecl>(decl)) + fieldOffset = getFieldOffset(getContext(), field); + else { + const IndirectFieldDecl *ifield = cast<IndirectFieldDecl>(decl); + + fieldOffset = 0; + for (IndirectFieldDecl::chain_iterator ci = ifield->chain_begin(), + ce = ifield->chain_end(); ci != ce; ++ci) + fieldOffset += getFieldOffset(getContext(), cast<FieldDecl>(*ci)); + } + + CharUnits chars = getContext().toCharUnitsFromBits((int64_t) fieldOffset); + return getCXXABI().EmitMemberDataPointer(type, chars); +} + +static void +FillInNullDataMemberPointers(CodeGenModule &CGM, QualType T, + std::vector<llvm::Constant *> &Elements, + uint64_t StartOffset) { + assert(StartOffset % CGM.getContext().getCharWidth() == 0 && + "StartOffset not byte aligned!"); + + if (CGM.getTypes().isZeroInitializable(T)) + return; + + if (const ConstantArrayType *CAT = + CGM.getContext().getAsConstantArrayType(T)) { + QualType ElementTy = CAT->getElementType(); + uint64_t ElementSize = CGM.getContext().getTypeSize(ElementTy); + + for (uint64_t I = 0, E = CAT->getSize().getZExtValue(); I != E; ++I) { + FillInNullDataMemberPointers(CGM, ElementTy, Elements, + StartOffset + I * ElementSize); + } + } else if (const RecordType *RT = T->getAs<RecordType>()) { + const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); + const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); + + // Go through all bases and fill in any null pointer to data members. + for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), + E = RD->bases_end(); I != E; ++I) { + if (I->isVirtual()) { + // Ignore virtual bases. + continue; + } + + const CXXRecordDecl *BaseDecl = + cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); + + // Ignore empty bases. + if (BaseDecl->isEmpty()) + continue; + + // Ignore bases that don't have any pointer to data members. + if (CGM.getTypes().isZeroInitializable(BaseDecl)) + continue; + + uint64_t BaseOffset = Layout.getBaseClassOffsetInBits(BaseDecl); + FillInNullDataMemberPointers(CGM, I->getType(), + Elements, StartOffset + BaseOffset); + } + + // Visit all fields. + unsigned FieldNo = 0; + for (RecordDecl::field_iterator I = RD->field_begin(), + E = RD->field_end(); I != E; ++I, ++FieldNo) { + QualType FieldType = I->getType(); + + if (CGM.getTypes().isZeroInitializable(FieldType)) + continue; + + uint64_t FieldOffset = StartOffset + Layout.getFieldOffset(FieldNo); + FillInNullDataMemberPointers(CGM, FieldType, Elements, FieldOffset); + } + } else { + assert(T->isMemberPointerType() && "Should only see member pointers here!"); + assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() && + "Should only see pointers to data members here!"); + + CharUnits StartIndex = CGM.getContext().toCharUnitsFromBits(StartOffset); + CharUnits EndIndex = StartIndex + CGM.getContext().getTypeSizeInChars(T); + + // FIXME: hardcodes Itanium member pointer representation! + llvm::Constant *NegativeOne = + llvm::ConstantInt::get(llvm::Type::getInt8Ty(CGM.getLLVMContext()), + -1ULL, /*isSigned*/true); + + // Fill in the null data member pointer. + for (CharUnits I = StartIndex; I != EndIndex; ++I) + Elements[I.getQuantity()] = NegativeOne; + } +} + +static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM, + llvm::Type *baseType, + const CXXRecordDecl *base); + +static llvm::Constant *EmitNullConstant(CodeGenModule &CGM, + const CXXRecordDecl *record, + bool asCompleteObject) { + const CGRecordLayout &layout = CGM.getTypes().getCGRecordLayout(record); + llvm::StructType *structure = + (asCompleteObject ? layout.getLLVMType() + : layout.getBaseSubobjectLLVMType()); + + unsigned numElements = structure->getNumElements(); + std::vector<llvm::Constant *> elements(numElements); + + // Fill in all the bases. + for (CXXRecordDecl::base_class_const_iterator + I = record->bases_begin(), E = record->bases_end(); I != E; ++I) { + if (I->isVirtual()) { + // Ignore virtual bases; if we're laying out for a complete + // object, we'll lay these out later. + continue; + } + + const CXXRecordDecl *base = + cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl()); + + // Ignore empty bases. + if (base->isEmpty()) + continue; + + unsigned fieldIndex = layout.getNonVirtualBaseLLVMFieldNo(base); + llvm::Type *baseType = structure->getElementType(fieldIndex); + elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base); + } + + // Fill in all the fields. + for (RecordDecl::field_iterator I = record->field_begin(), + E = record->field_end(); I != E; ++I) { + const FieldDecl *field = *I; + + // Ignore bit fields. + if (field->isBitField()) + continue; + + unsigned fieldIndex = layout.getLLVMFieldNo(field); + elements[fieldIndex] = CGM.EmitNullConstant(field->getType()); + } + + // Fill in the virtual bases, if we're working with the complete object. + if (asCompleteObject) { + for (CXXRecordDecl::base_class_const_iterator + I = record->vbases_begin(), E = record->vbases_end(); I != E; ++I) { + const CXXRecordDecl *base = + cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl()); + + // Ignore empty bases. + if (base->isEmpty()) + continue; + + unsigned fieldIndex = layout.getVirtualBaseIndex(base); + + // We might have already laid this field out. + if (elements[fieldIndex]) continue; + + llvm::Type *baseType = structure->getElementType(fieldIndex); + elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base); + } + } + + // Now go through all other fields and zero them out. + for (unsigned i = 0; i != numElements; ++i) { + if (!elements[i]) + elements[i] = llvm::Constant::getNullValue(structure->getElementType(i)); + } + + return llvm::ConstantStruct::get(structure, elements); +} + +/// Emit the null constant for a base subobject. +static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM, + llvm::Type *baseType, + const CXXRecordDecl *base) { + const CGRecordLayout &baseLayout = CGM.getTypes().getCGRecordLayout(base); + + // Just zero out bases that don't have any pointer to data members. + if (baseLayout.isZeroInitializableAsBase()) + return llvm::Constant::getNullValue(baseType); + + // If the base type is a struct, we can just use its null constant. + if (isa<llvm::StructType>(baseType)) { + return EmitNullConstant(CGM, base, /*complete*/ false); + } + + // Otherwise, some bases are represented as arrays of i8 if the size + // of the base is smaller than its corresponding LLVM type. Figure + // out how many elements this base array has. + llvm::ArrayType *baseArrayType = cast<llvm::ArrayType>(baseType); + unsigned numBaseElements = baseArrayType->getNumElements(); + + // Fill in null data member pointers. + std::vector<llvm::Constant *> baseElements(numBaseElements); + FillInNullDataMemberPointers(CGM, CGM.getContext().getTypeDeclType(base), + baseElements, 0); + + // Now go through all other elements and zero them out. + if (numBaseElements) { + llvm::Type *i8 = llvm::Type::getInt8Ty(CGM.getLLVMContext()); + llvm::Constant *i8_zero = llvm::Constant::getNullValue(i8); + for (unsigned i = 0; i != numBaseElements; ++i) { + if (!baseElements[i]) + baseElements[i] = i8_zero; + } + } + + return llvm::ConstantArray::get(baseArrayType, baseElements); +} + +llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) { + if (getTypes().isZeroInitializable(T)) + return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T)); + + if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(T)) { + + QualType ElementTy = CAT->getElementType(); + + llvm::Constant *Element = EmitNullConstant(ElementTy); + unsigned NumElements = CAT->getSize().getZExtValue(); + std::vector<llvm::Constant *> Array(NumElements); + for (unsigned i = 0; i != NumElements; ++i) + Array[i] = Element; + + llvm::ArrayType *ATy = + cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T)); + return llvm::ConstantArray::get(ATy, Array); + } + + if (const RecordType *RT = T->getAs<RecordType>()) { + const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); + return ::EmitNullConstant(*this, RD, /*complete object*/ true); + } + + assert(T->isMemberPointerType() && "Should only see member pointers here!"); + assert(!T->getAs<MemberPointerType>()->getPointeeType()->isFunctionType() && + "Should only see pointers to data members here!"); + + // Itanium C++ ABI 2.3: + // A NULL pointer is represented as -1. + return getCXXABI().EmitNullMemberPointer(T->castAs<MemberPointerType>()); +} + +llvm::Constant * +CodeGenModule::EmitNullConstantForBase(const CXXRecordDecl *Record) { + return ::EmitNullConstant(*this, Record, false); +} |
