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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 | 2154 |
1 files changed, 2154 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 000000000000..68766479a539 --- /dev/null +++ b/contrib/llvm/tools/clang/lib/CodeGen/CGExprConstant.cpp @@ -0,0 +1,2154 @@ +//===--- 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 "CGCXXABI.h" +#include "CGObjCRuntime.h" +#include "CGRecordLayout.h" +#include "CodeGenModule.h" +#include "ConstantEmitter.h" +#include "TargetInfo.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/IR/Constants.h" +#include "llvm/IR/DataLayout.h" +#include "llvm/IR/Function.h" +#include "llvm/IR/GlobalVariable.h" +using namespace clang; +using namespace CodeGen; + +//===----------------------------------------------------------------------===// +// ConstStructBuilder +//===----------------------------------------------------------------------===// + +namespace { +class ConstExprEmitter; +class ConstStructBuilder { + CodeGenModule &CGM; + ConstantEmitter &Emitter; + + bool Packed; + CharUnits NextFieldOffsetInChars; + CharUnits LLVMStructAlignment; + SmallVector<llvm::Constant *, 32> Elements; +public: + static llvm::Constant *BuildStruct(ConstantEmitter &Emitter, + ConstExprEmitter *ExprEmitter, + llvm::ConstantStruct *Base, + InitListExpr *Updater, + QualType ValTy); + static llvm::Constant *BuildStruct(ConstantEmitter &Emitter, + InitListExpr *ILE, QualType StructTy); + static llvm::Constant *BuildStruct(ConstantEmitter &Emitter, + const APValue &Value, QualType ValTy); + +private: + ConstStructBuilder(ConstantEmitter &emitter) + : CGM(emitter.CGM), Emitter(emitter), Packed(false), + NextFieldOffsetInChars(CharUnits::Zero()), + LLVMStructAlignment(CharUnits::One()) { } + + void AppendField(const FieldDecl *Field, uint64_t FieldOffset, + llvm::Constant *InitExpr); + + void AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst); + + 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); + bool Build(ConstExprEmitter *Emitter, llvm::ConstantStruct *Base, + InitListExpr *Updater); + bool Build(const APValue &Val, const RecordDecl *RD, bool IsPrimaryBase, + const CXXRecordDecl *VTableClass, CharUnits BaseOffset); + llvm::Constant *Finalize(QualType Ty); + + CharUnits getAlignment(const llvm::Constant *C) const { + if (Packed) return CharUnits::One(); + return CharUnits::fromQuantity( + CGM.getDataLayout().getABITypeAlignment(C->getType())); + } + + CharUnits getSizeInChars(const llvm::Constant *C) const { + return CharUnits::fromQuantity( + CGM.getDataLayout().getTypeAllocSize(C->getType())); + } +}; + +void ConstStructBuilder:: +AppendField(const FieldDecl *Field, uint64_t FieldOffset, + llvm::Constant *InitCst) { + const ASTContext &Context = CGM.getContext(); + + CharUnits FieldOffsetInChars = Context.toCharUnitsFromBits(FieldOffset); + + AppendBytes(FieldOffsetInChars, InitCst); +} + +void ConstStructBuilder:: +AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst) { + + 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.alignTo(FieldAlignment); + + if (AlignedNextFieldOffsetInChars < FieldOffsetInChars) { + // We need to append padding. + AppendPadding(FieldOffsetInChars - NextFieldOffsetInChars); + + assert(NextFieldOffsetInChars == FieldOffsetInChars && + "Did not add enough padding!"); + + AlignedNextFieldOffsetInChars = + NextFieldOffsetInChars.alignTo(FieldAlignment); + } + + if (AlignedNextFieldOffsetInChars > FieldOffsetInChars) { + assert(!Packed && "Alignment is wrong even with a packed struct!"); + + // Convert the struct to a packed struct. + ConvertStructToPacked(); + + // After we pack the struct, we may need to insert padding. + if (NextFieldOffsetInChars < 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); +} + +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::alignTo(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.getDataLayout().isBigEndian()) { + Tmp.lshrInPlace(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.lshrInPlace(BitsInPreviousByte); + FieldValue = FieldValue.trunc(NewFieldWidth); + } + } + + Tmp = Tmp.zext(CharWidth); + if (CGM.getDataLayout().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.getDataLayout().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.lshrInPlace(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.getDataLayout().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 = CGM.Int8Ty; + 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() { + SmallVector<llvm::Constant *, 16> 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.getDataLayout().getABITypeAlignment(C->getType())); + CharUnits AlignedElementOffsetInChars = + ElementOffsetInChars.alignTo(ElementAlign); + + if (AlignedElementOffsetInChars > ElementOffsetInChars) { + // We need some padding. + CharUnits NumChars = + AlignedElementOffsetInChars - ElementOffsetInChars; + + llvm::Type *Ty = CGM.Int8Ty; + 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.swap(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; + + // Bail out if we have base classes. We could support these, but they only + // arise in C++1z where we will have already constant folded most interesting + // cases. FIXME: There are still a few more cases we can handle this way. + if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) + if (CXXRD->getNumBases()) + return false; + + for (RecordDecl::field_iterator Field = RD->field_begin(), + FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) { + // 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()) + 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 = Emitter.tryEmitPrivateForMemory(ILE->getInit(ElementNo++), + Field->getType()); + else + EltInit = Emitter.emitNullForMemory(Field->getType()); + + if (!EltInit) + return false; + + if (!Field->isBitField()) { + // Handle non-bitfield members. + AppendField(*Field, Layout.getFieldOffset(FieldNo), EltInit); + } else { + // Otherwise we have a bitfield. + if (auto *CI = dyn_cast<llvm::ConstantInt>(EltInit)) { + AppendBitField(*Field, Layout.getFieldOffset(FieldNo), CI); + } else { + // We are trying to initialize a bitfield with a non-trivial constant, + // this must require run-time code. + return false; + } + } + } + + return true; +} + +namespace { +struct BaseInfo { + BaseInfo(const CXXRecordDecl *Decl, CharUnits Offset, unsigned Index) + : Decl(Decl), Offset(Offset), Index(Index) { + } + + const CXXRecordDecl *Decl; + CharUnits Offset; + unsigned Index; + + bool operator<(const BaseInfo &O) const { return Offset < O.Offset; } +}; +} + +bool ConstStructBuilder::Build(const APValue &Val, const RecordDecl *RD, + bool IsPrimaryBase, + const CXXRecordDecl *VTableClass, + CharUnits Offset) { + const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); + + if (const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD)) { + // Add a vtable pointer, if we need one and it hasn't already been added. + if (CD->isDynamicClass() && !IsPrimaryBase) { + llvm::Constant *VTableAddressPoint = + CGM.getCXXABI().getVTableAddressPointForConstExpr( + BaseSubobject(CD, Offset), VTableClass); + AppendBytes(Offset, VTableAddressPoint); + } + + // Accumulate and sort bases, in order to visit them in address order, which + // may not be the same as declaration order. + SmallVector<BaseInfo, 8> Bases; + Bases.reserve(CD->getNumBases()); + unsigned BaseNo = 0; + for (CXXRecordDecl::base_class_const_iterator Base = CD->bases_begin(), + BaseEnd = CD->bases_end(); Base != BaseEnd; ++Base, ++BaseNo) { + assert(!Base->isVirtual() && "should not have virtual bases here"); + const CXXRecordDecl *BD = Base->getType()->getAsCXXRecordDecl(); + CharUnits BaseOffset = Layout.getBaseClassOffset(BD); + Bases.push_back(BaseInfo(BD, BaseOffset, BaseNo)); + } + std::stable_sort(Bases.begin(), Bases.end()); + + for (unsigned I = 0, N = Bases.size(); I != N; ++I) { + BaseInfo &Base = Bases[I]; + + bool IsPrimaryBase = Layout.getPrimaryBase() == Base.Decl; + Build(Val.getStructBase(Base.Index), Base.Decl, IsPrimaryBase, + VTableClass, Offset + Base.Offset); + } + } + + unsigned FieldNo = 0; + uint64_t OffsetBits = CGM.getContext().toBits(Offset); + + for (RecordDecl::field_iterator Field = RD->field_begin(), + FieldEnd = RD->field_end(); Field != FieldEnd; ++Field, ++FieldNo) { + // If this is a union, skip all the fields that aren't being initialized. + if (RD->isUnion() && Val.getUnionField() != *Field) + continue; + + // Don't emit anonymous bitfields, they just affect layout. + if (Field->isUnnamedBitfield()) + continue; + + // Emit the value of the initializer. + const APValue &FieldValue = + RD->isUnion() ? Val.getUnionValue() : Val.getStructField(FieldNo); + llvm::Constant *EltInit = + Emitter.tryEmitPrivateForMemory(FieldValue, Field->getType()); + if (!EltInit) + return false; + + if (!Field->isBitField()) { + // Handle non-bitfield members. + AppendField(*Field, Layout.getFieldOffset(FieldNo) + OffsetBits, EltInit); + } else { + // Otherwise we have a bitfield. + AppendBitField(*Field, Layout.getFieldOffset(FieldNo) + OffsetBits, + cast<llvm::ConstantInt>(EltInit)); + } + } + + return true; +} + +llvm::Constant *ConstStructBuilder::Finalize(QualType Ty) { + RecordDecl *RD = Ty->getAs<RecordType>()->getDecl(); + const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); + + 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. + } else { + // Append tail padding if necessary. + CharUnits LLVMSizeInChars = + NextFieldOffsetInChars.alignTo(LLVMStructAlignment); + + if (LLVMSizeInChars != LayoutSizeInChars) + AppendTailPadding(LayoutSizeInChars); + + LLVMSizeInChars = NextFieldOffsetInChars.alignTo(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!"); + } + + LLVMSizeInChars = NextFieldOffsetInChars.alignTo(LLVMStructAlignment); + + assert(LayoutSizeInChars == LLVMSizeInChars && + "Tail padding mismatch!"); + } + + // 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(), + Elements, Packed); + llvm::Type *ValTy = CGM.getTypes().ConvertType(Ty); + if (llvm::StructType *ValSTy = dyn_cast<llvm::StructType>(ValTy)) { + if (ValSTy->isLayoutIdentical(STy)) + STy = ValSTy; + } + + llvm::Constant *Result = llvm::ConstantStruct::get(STy, Elements); + + assert(NextFieldOffsetInChars.alignTo(getAlignment(Result)) == + getSizeInChars(Result) && + "Size mismatch!"); + + return Result; +} + +llvm::Constant *ConstStructBuilder::BuildStruct(ConstantEmitter &Emitter, + ConstExprEmitter *ExprEmitter, + llvm::ConstantStruct *Base, + InitListExpr *Updater, + QualType ValTy) { + ConstStructBuilder Builder(Emitter); + if (!Builder.Build(ExprEmitter, Base, Updater)) + return nullptr; + return Builder.Finalize(ValTy); +} + +llvm::Constant *ConstStructBuilder::BuildStruct(ConstantEmitter &Emitter, + InitListExpr *ILE, + QualType ValTy) { + ConstStructBuilder Builder(Emitter); + + if (!Builder.Build(ILE)) + return nullptr; + + return Builder.Finalize(ValTy); +} + +llvm::Constant *ConstStructBuilder::BuildStruct(ConstantEmitter &Emitter, + const APValue &Val, + QualType ValTy) { + ConstStructBuilder Builder(Emitter); + + const RecordDecl *RD = ValTy->castAs<RecordType>()->getDecl(); + const CXXRecordDecl *CD = dyn_cast<CXXRecordDecl>(RD); + if (!Builder.Build(Val, RD, false, CD, CharUnits::Zero())) + return nullptr; + + return Builder.Finalize(ValTy); +} + + +//===----------------------------------------------------------------------===// +// ConstExprEmitter +//===----------------------------------------------------------------------===// + +static ConstantAddress tryEmitGlobalCompoundLiteral(CodeGenModule &CGM, + CodeGenFunction *CGF, + const CompoundLiteralExpr *E) { + CharUnits Align = CGM.getContext().getTypeAlignInChars(E->getType()); + if (llvm::GlobalVariable *Addr = + CGM.getAddrOfConstantCompoundLiteralIfEmitted(E)) + return ConstantAddress(Addr, Align); + + LangAS addressSpace = E->getType().getAddressSpace(); + + ConstantEmitter emitter(CGM, CGF); + llvm::Constant *C = emitter.tryEmitForInitializer(E->getInitializer(), + addressSpace, E->getType()); + if (!C) { + assert(!E->isFileScope() && + "file-scope compound literal did not have constant initializer!"); + return ConstantAddress::invalid(); + } + + auto GV = new llvm::GlobalVariable(CGM.getModule(), C->getType(), + CGM.isTypeConstant(E->getType(), true), + llvm::GlobalValue::InternalLinkage, + C, ".compoundliteral", nullptr, + llvm::GlobalVariable::NotThreadLocal, + CGM.getContext().getTargetAddressSpace(addressSpace)); + emitter.finalize(GV); + GV->setAlignment(Align.getQuantity()); + CGM.setAddrOfConstantCompoundLiteral(E, GV); + return ConstantAddress(GV, Align); +} + +static llvm::Constant * +EmitArrayConstant(CodeGenModule &CGM, const ConstantArrayType *DestType, + llvm::Type *CommonElementType, unsigned ArrayBound, + SmallVectorImpl<llvm::Constant *> &Elements, + llvm::Constant *Filler) { + // Figure out how long the initial prefix of non-zero elements is. + unsigned NonzeroLength = ArrayBound; + if (Elements.size() < NonzeroLength && Filler->isNullValue()) + NonzeroLength = Elements.size(); + if (NonzeroLength == Elements.size()) { + while (NonzeroLength > 0 && Elements[NonzeroLength - 1]->isNullValue()) + --NonzeroLength; + } + + if (NonzeroLength == 0) { + return llvm::ConstantAggregateZero::get( + CGM.getTypes().ConvertType(QualType(DestType, 0))); + } + + // Add a zeroinitializer array filler if we have lots of trailing zeroes. + unsigned TrailingZeroes = ArrayBound - NonzeroLength; + if (TrailingZeroes >= 8) { + assert(Elements.size() >= NonzeroLength && + "missing initializer for non-zero element"); + + // If all the elements had the same type up to the trailing zeroes, emit a + // struct of two arrays (the nonzero data and the zeroinitializer). + if (CommonElementType && NonzeroLength >= 8) { + llvm::Constant *Initial = llvm::ConstantArray::get( + llvm::ArrayType::get(CommonElementType, NonzeroLength), + makeArrayRef(Elements).take_front(NonzeroLength)); + Elements.resize(2); + Elements[0] = Initial; + } else { + Elements.resize(NonzeroLength + 1); + } + + auto *FillerType = + CommonElementType + ? CommonElementType + : CGM.getTypes().ConvertType(DestType->getElementType()); + FillerType = llvm::ArrayType::get(FillerType, TrailingZeroes); + Elements.back() = llvm::ConstantAggregateZero::get(FillerType); + CommonElementType = nullptr; + } else if (Elements.size() != ArrayBound) { + // Otherwise pad to the right size with the filler if necessary. + Elements.resize(ArrayBound, Filler); + if (Filler->getType() != CommonElementType) + CommonElementType = nullptr; + } + + // If all elements have the same type, just emit an array constant. + if (CommonElementType) + return llvm::ConstantArray::get( + llvm::ArrayType::get(CommonElementType, ArrayBound), Elements); + + // We have mixed types. Use a packed struct. + llvm::SmallVector<llvm::Type *, 16> Types; + Types.reserve(Elements.size()); + for (llvm::Constant *Elt : Elements) + Types.push_back(Elt->getType()); + llvm::StructType *SType = + llvm::StructType::get(CGM.getLLVMContext(), Types, true); + return llvm::ConstantStruct::get(SType, Elements); +} + +/// This class only needs to handle two cases: +/// 1) Literals (this is used by APValue emission to emit literals). +/// 2) Arrays, structs and unions (outside C++11 mode, we don't currently +/// constant fold these types). +class ConstExprEmitter : + public StmtVisitor<ConstExprEmitter, llvm::Constant*, QualType> { + CodeGenModule &CGM; + ConstantEmitter &Emitter; + llvm::LLVMContext &VMContext; +public: + ConstExprEmitter(ConstantEmitter &emitter) + : CGM(emitter.CGM), Emitter(emitter), VMContext(CGM.getLLVMContext()) { + } + + //===--------------------------------------------------------------------===// + // Visitor Methods + //===--------------------------------------------------------------------===// + + llvm::Constant *VisitStmt(Stmt *S, QualType T) { + return nullptr; + } + + llvm::Constant *VisitParenExpr(ParenExpr *PE, QualType T) { + return Visit(PE->getSubExpr(), T); + } + + llvm::Constant * + VisitSubstNonTypeTemplateParmExpr(SubstNonTypeTemplateParmExpr *PE, + QualType T) { + return Visit(PE->getReplacement(), T); + } + + llvm::Constant *VisitGenericSelectionExpr(GenericSelectionExpr *GE, + QualType T) { + return Visit(GE->getResultExpr(), T); + } + + llvm::Constant *VisitChooseExpr(ChooseExpr *CE, QualType T) { + return Visit(CE->getChosenSubExpr(), T); + } + + llvm::Constant *VisitCompoundLiteralExpr(CompoundLiteralExpr *E, QualType T) { + return Visit(E->getInitializer(), T); + } + + llvm::Constant *VisitCastExpr(CastExpr *E, QualType destType) { + if (const auto *ECE = dyn_cast<ExplicitCastExpr>(E)) + CGM.EmitExplicitCastExprType(ECE, Emitter.CGF); + Expr *subExpr = E->getSubExpr(); + + switch (E->getCastKind()) { + case CK_ToUnion: { + // GCC cast to union extension + assert(E->getType()->isUnionType() && + "Destination type is not union type!"); + + auto field = E->getTargetUnionField(); + + auto C = Emitter.tryEmitPrivateForMemory(subExpr, field->getType()); + if (!C) return nullptr; + + auto destTy = ConvertType(destType); + if (C->getType() == destTy) return C; + + // Build a struct with the union sub-element as the first member, + // and padded to the appropriate size. + SmallVector<llvm::Constant*, 2> Elts; + SmallVector<llvm::Type*, 2> Types; + Elts.push_back(C); + Types.push_back(C->getType()); + unsigned CurSize = CGM.getDataLayout().getTypeAllocSize(C->getType()); + unsigned TotalSize = CGM.getDataLayout().getTypeAllocSize(destTy); + + assert(CurSize <= TotalSize && "Union size mismatch!"); + if (unsigned NumPadBytes = TotalSize - CurSize) { + llvm::Type *Ty = CGM.Int8Ty; + 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(VMContext, Types, false); + return llvm::ConstantStruct::get(STy, Elts); + } + + case CK_AddressSpaceConversion: { + auto C = Emitter.tryEmitPrivate(subExpr, subExpr->getType()); + if (!C) return nullptr; + LangAS destAS = E->getType()->getPointeeType().getAddressSpace(); + LangAS srcAS = subExpr->getType()->getPointeeType().getAddressSpace(); + llvm::Type *destTy = ConvertType(E->getType()); + return CGM.getTargetCodeGenInfo().performAddrSpaceCast(CGM, C, srcAS, + destAS, destTy); + } + + case CK_LValueToRValue: + case CK_AtomicToNonAtomic: + case CK_NonAtomicToAtomic: + case CK_NoOp: + case CK_ConstructorConversion: + return Visit(subExpr, destType); + + case CK_IntToOCLSampler: + llvm_unreachable("global sampler variables are not generated"); + + case CK_Dependent: llvm_unreachable("saw dependent cast!"); + + case CK_BuiltinFnToFnPtr: + llvm_unreachable("builtin functions are handled elsewhere"); + + case CK_ReinterpretMemberPointer: + case CK_DerivedToBaseMemberPointer: + case CK_BaseToDerivedMemberPointer: { + auto C = Emitter.tryEmitPrivate(subExpr, subExpr->getType()); + if (!C) return nullptr; + return CGM.getCXXABI().EmitMemberPointerConversion(E, C); + } + + // These will never be supported. + case CK_ObjCObjectLValueCast: + case CK_ARCProduceObject: + case CK_ARCConsumeObject: + case CK_ARCReclaimReturnedObject: + case CK_ARCExtendBlockObject: + case CK_CopyAndAutoreleaseBlockObject: + return nullptr; + + // These don't need to be handled here because Evaluate knows how to + // evaluate them in the cases where they can be folded. + case CK_BitCast: + case CK_ToVoid: + case CK_Dynamic: + case CK_LValueBitCast: + case CK_NullToMemberPointer: + case CK_UserDefinedConversion: + case CK_CPointerToObjCPointerCast: + case CK_BlockPointerToObjCPointerCast: + case CK_AnyPointerToBlockPointerCast: + 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: + case CK_PointerToIntegral: + case CK_PointerToBoolean: + case CK_NullToPointer: + case CK_IntegralCast: + case CK_BooleanToSignedIntegral: + case CK_IntegralToPointer: + case CK_IntegralToBoolean: + case CK_IntegralToFloating: + case CK_FloatingToIntegral: + case CK_FloatingToBoolean: + case CK_FloatingCast: + case CK_ZeroToOCLEvent: + case CK_ZeroToOCLQueue: + return nullptr; + } + llvm_unreachable("Invalid CastKind"); + } + + llvm::Constant *VisitCXXDefaultArgExpr(CXXDefaultArgExpr *DAE, QualType T) { + return Visit(DAE->getExpr(), T); + } + + llvm::Constant *VisitCXXDefaultInitExpr(CXXDefaultInitExpr *DIE, QualType T) { + // No need for a DefaultInitExprScope: we don't handle 'this' in a + // constant expression. + return Visit(DIE->getExpr(), T); + } + + llvm::Constant *VisitExprWithCleanups(ExprWithCleanups *E, QualType T) { + if (!E->cleanupsHaveSideEffects()) + return Visit(E->getSubExpr(), T); + return nullptr; + } + + llvm::Constant *VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E, + QualType T) { + return Visit(E->GetTemporaryExpr(), T); + } + + llvm::Constant *EmitArrayInitialization(InitListExpr *ILE, QualType T) { + auto *CAT = CGM.getContext().getAsConstantArrayType(ILE->getType()); + assert(CAT && "can't emit array init for non-constant-bound array"); + unsigned NumInitElements = ILE->getNumInits(); + unsigned NumElements = CAT->getSize().getZExtValue(); + + // Initialising an array requires us to automatically + // initialise any elements that have not been initialised explicitly + unsigned NumInitableElts = std::min(NumInitElements, NumElements); + + QualType EltType = CAT->getElementType(); + + // Initialize remaining array elements. + llvm::Constant *fillC = nullptr; + if (Expr *filler = ILE->getArrayFiller()) { + fillC = Emitter.tryEmitAbstractForMemory(filler, EltType); + if (!fillC) + return nullptr; + } + + // Copy initializer elements. + SmallVector<llvm::Constant*, 16> Elts; + if (fillC && fillC->isNullValue()) + Elts.reserve(NumInitableElts + 1); + else + Elts.reserve(NumElements); + + llvm::Type *CommonElementType = nullptr; + for (unsigned i = 0; i < NumInitableElts; ++i) { + Expr *Init = ILE->getInit(i); + llvm::Constant *C = Emitter.tryEmitPrivateForMemory(Init, EltType); + if (!C) + return nullptr; + if (i == 0) + CommonElementType = C->getType(); + else if (C->getType() != CommonElementType) + CommonElementType = nullptr; + Elts.push_back(C); + } + + return EmitArrayConstant(CGM, CAT, CommonElementType, NumElements, Elts, + fillC); + } + + llvm::Constant *EmitRecordInitialization(InitListExpr *ILE, QualType T) { + return ConstStructBuilder::BuildStruct(Emitter, ILE, T); + } + + llvm::Constant *VisitImplicitValueInitExpr(ImplicitValueInitExpr* E, + QualType T) { + return CGM.EmitNullConstant(T); + } + + llvm::Constant *VisitInitListExpr(InitListExpr *ILE, QualType T) { + if (ILE->isTransparent()) + return Visit(ILE->getInit(0), T); + + if (ILE->getType()->isArrayType()) + return EmitArrayInitialization(ILE, T); + + if (ILE->getType()->isRecordType()) + return EmitRecordInitialization(ILE, T); + + return nullptr; + } + + llvm::Constant *EmitDesignatedInitUpdater(llvm::Constant *Base, + InitListExpr *Updater, + QualType destType) { + if (auto destAT = CGM.getContext().getAsArrayType(destType)) { + llvm::ArrayType *AType = cast<llvm::ArrayType>(ConvertType(destType)); + llvm::Type *ElemType = AType->getElementType(); + + unsigned NumInitElements = Updater->getNumInits(); + unsigned NumElements = AType->getNumElements(); + + std::vector<llvm::Constant *> Elts; + Elts.reserve(NumElements); + + QualType destElemType = destAT->getElementType(); + + if (auto DataArray = dyn_cast<llvm::ConstantDataArray>(Base)) + for (unsigned i = 0; i != NumElements; ++i) + Elts.push_back(DataArray->getElementAsConstant(i)); + else if (auto Array = dyn_cast<llvm::ConstantArray>(Base)) + for (unsigned i = 0; i != NumElements; ++i) + Elts.push_back(Array->getOperand(i)); + else + return nullptr; // FIXME: other array types not implemented + + llvm::Constant *fillC = nullptr; + if (Expr *filler = Updater->getArrayFiller()) + if (!isa<NoInitExpr>(filler)) + fillC = Emitter.tryEmitAbstractForMemory(filler, destElemType); + bool RewriteType = (fillC && fillC->getType() != ElemType); + + for (unsigned i = 0; i != NumElements; ++i) { + Expr *Init = nullptr; + if (i < NumInitElements) + Init = Updater->getInit(i); + + if (!Init && fillC) + Elts[i] = fillC; + else if (!Init || isa<NoInitExpr>(Init)) + ; // Do nothing. + else if (InitListExpr *ChildILE = dyn_cast<InitListExpr>(Init)) + Elts[i] = EmitDesignatedInitUpdater(Elts[i], ChildILE, destElemType); + else + Elts[i] = Emitter.tryEmitPrivateForMemory(Init, destElemType); + + if (!Elts[i]) + return nullptr; + RewriteType |= (Elts[i]->getType() != ElemType); + } + + if (RewriteType) { + std::vector<llvm::Type *> Types; + Types.reserve(NumElements); + for (unsigned i = 0; i != NumElements; ++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); + } + + if (destType->isRecordType()) + return ConstStructBuilder::BuildStruct(Emitter, this, + dyn_cast<llvm::ConstantStruct>(Base), Updater, destType); + + return nullptr; + } + + llvm::Constant *VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E, + QualType destType) { + auto C = Visit(E->getBase(), destType); + if (!C) return nullptr; + return EmitDesignatedInitUpdater(C, E->getUpdater(), destType); + } + + llvm::Constant *VisitCXXConstructExpr(CXXConstructExpr *E, QualType Ty) { + if (!E->getConstructor()->isTrivial()) + return nullptr; + + // 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 nullptr; + + // 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, Ty); + } + + return CGM.EmitNullConstant(Ty); + } + + llvm::Constant *VisitStringLiteral(StringLiteral *E, QualType T) { + return CGM.GetConstantArrayFromStringLiteral(E); + } + + llvm::Constant *VisitObjCEncodeExpr(ObjCEncodeExpr *E, QualType T) { + // 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 = CGM.getContext().getAsConstantArrayType(T); + + // Resize the string to the right size, adding zeros at the end, or + // truncating as needed. + Str.resize(CAT->getSize().getZExtValue(), '\0'); + return llvm::ConstantDataArray::getString(VMContext, Str, false); + } + + llvm::Constant *VisitUnaryExtension(const UnaryOperator *E, QualType T) { + return Visit(E->getSubExpr(), T); + } + + // Utility methods + llvm::Type *ConvertType(QualType T) { + return CGM.getTypes().ConvertType(T); + } +}; + +} // end anonymous namespace. + +bool ConstStructBuilder::Build(ConstExprEmitter *ExprEmitter, + llvm::ConstantStruct *Base, + InitListExpr *Updater) { + assert(Base && "base expression should not be empty"); + + QualType ExprType = Updater->getType(); + RecordDecl *RD = ExprType->getAs<RecordType>()->getDecl(); + const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); + const llvm::StructLayout *BaseLayout = CGM.getDataLayout().getStructLayout( + Base->getType()); + unsigned FieldNo = -1; + unsigned ElementNo = 0; + + // Bail out if we have base classes. We could support these, but they only + // arise in C++1z where we will have already constant folded most interesting + // cases. FIXME: There are still a few more cases we can handle this way. + if (auto *CXXRD = dyn_cast<CXXRecordDecl>(RD)) + if (CXXRD->getNumBases()) + return false; + + for (FieldDecl *Field : RD->fields()) { + ++FieldNo; + + if (RD->isUnion() && Updater->getInitializedFieldInUnion() != Field) + continue; + + // Skip anonymous bitfields. + if (Field->isUnnamedBitfield()) + continue; + + llvm::Constant *EltInit = Base->getOperand(ElementNo); + + // Bail out if the type of the ConstantStruct does not have the same layout + // as the type of the InitListExpr. + if (CGM.getTypes().ConvertType(Field->getType()) != EltInit->getType() || + Layout.getFieldOffset(ElementNo) != + BaseLayout->getElementOffsetInBits(ElementNo)) + return false; + + // Get the initializer. If we encounter an empty field or a NoInitExpr, + // we use values from the base expression. + Expr *Init = nullptr; + if (ElementNo < Updater->getNumInits()) + Init = Updater->getInit(ElementNo); + + if (!Init || isa<NoInitExpr>(Init)) + ; // Do nothing. + else if (InitListExpr *ChildILE = dyn_cast<InitListExpr>(Init)) + EltInit = ExprEmitter->EmitDesignatedInitUpdater(EltInit, ChildILE, + Field->getType()); + else + EltInit = Emitter.tryEmitPrivateForMemory(Init, Field->getType()); + + ++ElementNo; + + if (!EltInit) + return false; + + if (!Field->isBitField()) + AppendField(Field, Layout.getFieldOffset(FieldNo), EltInit); + else if (llvm::ConstantInt *CI = dyn_cast<llvm::ConstantInt>(EltInit)) + AppendBitField(Field, Layout.getFieldOffset(FieldNo), CI); + else + // Initializing a bitfield with a non-trivial constant? + return false; + } + + return true; +} + +llvm::Constant *ConstantEmitter::validateAndPopAbstract(llvm::Constant *C, + AbstractState saved) { + Abstract = saved.OldValue; + + assert(saved.OldPlaceholdersSize == PlaceholderAddresses.size() && + "created a placeholder while doing an abstract emission?"); + + // No validation necessary for now. + // No cleanup to do for now. + return C; +} + +llvm::Constant * +ConstantEmitter::tryEmitAbstractForInitializer(const VarDecl &D) { + auto state = pushAbstract(); + auto C = tryEmitPrivateForVarInit(D); + return validateAndPopAbstract(C, state); +} + +llvm::Constant * +ConstantEmitter::tryEmitAbstract(const Expr *E, QualType destType) { + auto state = pushAbstract(); + auto C = tryEmitPrivate(E, destType); + return validateAndPopAbstract(C, state); +} + +llvm::Constant * +ConstantEmitter::tryEmitAbstract(const APValue &value, QualType destType) { + auto state = pushAbstract(); + auto C = tryEmitPrivate(value, destType); + return validateAndPopAbstract(C, state); +} + +llvm::Constant * +ConstantEmitter::emitAbstract(const Expr *E, QualType destType) { + auto state = pushAbstract(); + auto C = tryEmitPrivate(E, destType); + C = validateAndPopAbstract(C, state); + if (!C) { + CGM.Error(E->getExprLoc(), + "internal error: could not emit constant value \"abstractly\""); + C = CGM.EmitNullConstant(destType); + } + return C; +} + +llvm::Constant * +ConstantEmitter::emitAbstract(SourceLocation loc, const APValue &value, + QualType destType) { + auto state = pushAbstract(); + auto C = tryEmitPrivate(value, destType); + C = validateAndPopAbstract(C, state); + if (!C) { + CGM.Error(loc, + "internal error: could not emit constant value \"abstractly\""); + C = CGM.EmitNullConstant(destType); + } + return C; +} + +llvm::Constant *ConstantEmitter::tryEmitForInitializer(const VarDecl &D) { + initializeNonAbstract(D.getType().getAddressSpace()); + return markIfFailed(tryEmitPrivateForVarInit(D)); +} + +llvm::Constant *ConstantEmitter::tryEmitForInitializer(const Expr *E, + LangAS destAddrSpace, + QualType destType) { + initializeNonAbstract(destAddrSpace); + return markIfFailed(tryEmitPrivateForMemory(E, destType)); +} + +llvm::Constant *ConstantEmitter::emitForInitializer(const APValue &value, + LangAS destAddrSpace, + QualType destType) { + initializeNonAbstract(destAddrSpace); + auto C = tryEmitPrivateForMemory(value, destType); + assert(C && "couldn't emit constant value non-abstractly?"); + return C; +} + +llvm::GlobalValue *ConstantEmitter::getCurrentAddrPrivate() { + assert(!Abstract && "cannot get current address for abstract constant"); + + + + // Make an obviously ill-formed global that should blow up compilation + // if it survives. + auto global = new llvm::GlobalVariable(CGM.getModule(), CGM.Int8Ty, true, + llvm::GlobalValue::PrivateLinkage, + /*init*/ nullptr, + /*name*/ "", + /*before*/ nullptr, + llvm::GlobalVariable::NotThreadLocal, + CGM.getContext().getTargetAddressSpace(DestAddressSpace)); + + PlaceholderAddresses.push_back(std::make_pair(nullptr, global)); + + return global; +} + +void ConstantEmitter::registerCurrentAddrPrivate(llvm::Constant *signal, + llvm::GlobalValue *placeholder) { + assert(!PlaceholderAddresses.empty()); + assert(PlaceholderAddresses.back().first == nullptr); + assert(PlaceholderAddresses.back().second == placeholder); + PlaceholderAddresses.back().first = signal; +} + +namespace { + struct ReplacePlaceholders { + CodeGenModule &CGM; + + /// The base address of the global. + llvm::Constant *Base; + llvm::Type *BaseValueTy = nullptr; + + /// The placeholder addresses that were registered during emission. + llvm::DenseMap<llvm::Constant*, llvm::GlobalVariable*> PlaceholderAddresses; + + /// The locations of the placeholder signals. + llvm::DenseMap<llvm::GlobalVariable*, llvm::Constant*> Locations; + + /// The current index stack. We use a simple unsigned stack because + /// we assume that placeholders will be relatively sparse in the + /// initializer, but we cache the index values we find just in case. + llvm::SmallVector<unsigned, 8> Indices; + llvm::SmallVector<llvm::Constant*, 8> IndexValues; + + ReplacePlaceholders(CodeGenModule &CGM, llvm::Constant *base, + ArrayRef<std::pair<llvm::Constant*, + llvm::GlobalVariable*>> addresses) + : CGM(CGM), Base(base), + PlaceholderAddresses(addresses.begin(), addresses.end()) { + } + + void replaceInInitializer(llvm::Constant *init) { + // Remember the type of the top-most initializer. + BaseValueTy = init->getType(); + + // Initialize the stack. + Indices.push_back(0); + IndexValues.push_back(nullptr); + + // Recurse into the initializer. + findLocations(init); + + // Check invariants. + assert(IndexValues.size() == Indices.size() && "mismatch"); + assert(Indices.size() == 1 && "didn't pop all indices"); + + // Do the replacement; this basically invalidates 'init'. + assert(Locations.size() == PlaceholderAddresses.size() && + "missed a placeholder?"); + + // We're iterating over a hashtable, so this would be a source of + // non-determinism in compiler output *except* that we're just + // messing around with llvm::Constant structures, which never itself + // does anything that should be visible in compiler output. + for (auto &entry : Locations) { + assert(entry.first->getParent() == nullptr && "not a placeholder!"); + entry.first->replaceAllUsesWith(entry.second); + entry.first->eraseFromParent(); + } + } + + private: + void findLocations(llvm::Constant *init) { + // Recurse into aggregates. + if (auto agg = dyn_cast<llvm::ConstantAggregate>(init)) { + for (unsigned i = 0, e = agg->getNumOperands(); i != e; ++i) { + Indices.push_back(i); + IndexValues.push_back(nullptr); + + findLocations(agg->getOperand(i)); + + IndexValues.pop_back(); + Indices.pop_back(); + } + return; + } + + // Otherwise, check for registered constants. + while (true) { + auto it = PlaceholderAddresses.find(init); + if (it != PlaceholderAddresses.end()) { + setLocation(it->second); + break; + } + + // Look through bitcasts or other expressions. + if (auto expr = dyn_cast<llvm::ConstantExpr>(init)) { + init = expr->getOperand(0); + } else { + break; + } + } + } + + void setLocation(llvm::GlobalVariable *placeholder) { + assert(Locations.find(placeholder) == Locations.end() && + "already found location for placeholder!"); + + // Lazily fill in IndexValues with the values from Indices. + // We do this in reverse because we should always have a strict + // prefix of indices from the start. + assert(Indices.size() == IndexValues.size()); + for (size_t i = Indices.size() - 1; i != size_t(-1); --i) { + if (IndexValues[i]) { +#ifndef NDEBUG + for (size_t j = 0; j != i + 1; ++j) { + assert(IndexValues[j] && + isa<llvm::ConstantInt>(IndexValues[j]) && + cast<llvm::ConstantInt>(IndexValues[j])->getZExtValue() + == Indices[j]); + } +#endif + break; + } + + IndexValues[i] = llvm::ConstantInt::get(CGM.Int32Ty, Indices[i]); + } + + // Form a GEP and then bitcast to the placeholder type so that the + // replacement will succeed. + llvm::Constant *location = + llvm::ConstantExpr::getInBoundsGetElementPtr(BaseValueTy, + Base, IndexValues); + location = llvm::ConstantExpr::getBitCast(location, + placeholder->getType()); + + Locations.insert({placeholder, location}); + } + }; +} + +void ConstantEmitter::finalize(llvm::GlobalVariable *global) { + assert(InitializedNonAbstract && + "finalizing emitter that was used for abstract emission?"); + assert(!Finalized && "finalizing emitter multiple times"); + assert(global->getInitializer()); + + // Note that we might also be Failed. + Finalized = true; + + if (!PlaceholderAddresses.empty()) { + ReplacePlaceholders(CGM, global, PlaceholderAddresses) + .replaceInInitializer(global->getInitializer()); + PlaceholderAddresses.clear(); // satisfy + } +} + +ConstantEmitter::~ConstantEmitter() { + assert((!InitializedNonAbstract || Finalized || Failed) && + "not finalized after being initialized for non-abstract emission"); + assert(PlaceholderAddresses.empty() && "unhandled placeholders"); +} + +static QualType getNonMemoryType(CodeGenModule &CGM, QualType type) { + if (auto AT = type->getAs<AtomicType>()) { + return CGM.getContext().getQualifiedType(AT->getValueType(), + type.getQualifiers()); + } + return type; +} + +llvm::Constant *ConstantEmitter::tryEmitPrivateForVarInit(const VarDecl &D) { + // Make a quick check if variable can be default NULL initialized + // and avoid going through rest of code which may do, for c++11, + // initialization of memory to all NULLs. + if (!D.hasLocalStorage()) { + QualType Ty = CGM.getContext().getBaseElementType(D.getType()); + if (Ty->isRecordType()) + if (const CXXConstructExpr *E = + dyn_cast_or_null<CXXConstructExpr>(D.getInit())) { + const CXXConstructorDecl *CD = E->getConstructor(); + if (CD->isTrivial() && CD->isDefaultConstructor()) + return CGM.EmitNullConstant(D.getType()); + } + } + + QualType destType = D.getType(); + + // Try to emit the initializer. Note that this can allow some things that + // are not allowed by tryEmitPrivateForMemory alone. + if (auto value = D.evaluateValue()) { + return tryEmitPrivateForMemory(*value, destType); + } + + // FIXME: Implement C++11 [basic.start.init]p2: if the initializer of a + // reference is a constant expression, and the reference binds to a temporary, + // then constant initialization is performed. ConstExprEmitter will + // incorrectly emit a prvalue constant in this case, and the calling code + // interprets that as the (pointer) value of the reference, rather than the + // desired value of the referee. + if (destType->isReferenceType()) + return nullptr; + + const Expr *E = D.getInit(); + assert(E && "No initializer to emit"); + + auto nonMemoryDestType = getNonMemoryType(CGM, destType); + auto C = + ConstExprEmitter(*this).Visit(const_cast<Expr*>(E), nonMemoryDestType); + return (C ? emitForMemory(C, destType) : nullptr); +} + +llvm::Constant * +ConstantEmitter::tryEmitAbstractForMemory(const Expr *E, QualType destType) { + auto nonMemoryDestType = getNonMemoryType(CGM, destType); + auto C = tryEmitAbstract(E, nonMemoryDestType); + return (C ? emitForMemory(C, destType) : nullptr); +} + +llvm::Constant * +ConstantEmitter::tryEmitAbstractForMemory(const APValue &value, + QualType destType) { + auto nonMemoryDestType = getNonMemoryType(CGM, destType); + auto C = tryEmitAbstract(value, nonMemoryDestType); + return (C ? emitForMemory(C, destType) : nullptr); +} + +llvm::Constant *ConstantEmitter::tryEmitPrivateForMemory(const Expr *E, + QualType destType) { + auto nonMemoryDestType = getNonMemoryType(CGM, destType); + llvm::Constant *C = tryEmitPrivate(E, nonMemoryDestType); + return (C ? emitForMemory(C, destType) : nullptr); +} + +llvm::Constant *ConstantEmitter::tryEmitPrivateForMemory(const APValue &value, + QualType destType) { + auto nonMemoryDestType = getNonMemoryType(CGM, destType); + auto C = tryEmitPrivate(value, nonMemoryDestType); + return (C ? emitForMemory(C, destType) : nullptr); +} + +llvm::Constant *ConstantEmitter::emitForMemory(CodeGenModule &CGM, + llvm::Constant *C, + QualType destType) { + // For an _Atomic-qualified constant, we may need to add tail padding. + if (auto AT = destType->getAs<AtomicType>()) { + QualType destValueType = AT->getValueType(); + C = emitForMemory(CGM, C, destValueType); + + uint64_t innerSize = CGM.getContext().getTypeSize(destValueType); + uint64_t outerSize = CGM.getContext().getTypeSize(destType); + if (innerSize == outerSize) + return C; + + assert(innerSize < outerSize && "emitted over-large constant for atomic"); + llvm::Constant *elts[] = { + C, + llvm::ConstantAggregateZero::get( + llvm::ArrayType::get(CGM.Int8Ty, (outerSize - innerSize) / 8)) + }; + return llvm::ConstantStruct::getAnon(elts); + } + + // Zero-extend bool. + if (C->getType()->isIntegerTy(1)) { + llvm::Type *boolTy = CGM.getTypes().ConvertTypeForMem(destType); + return llvm::ConstantExpr::getZExt(C, boolTy); + } + + return C; +} + +llvm::Constant *ConstantEmitter::tryEmitPrivate(const Expr *E, + QualType destType) { + Expr::EvalResult Result; + + bool Success = false; + + if (destType->isReferenceType()) + Success = E->EvaluateAsLValue(Result, CGM.getContext()); + else + Success = E->EvaluateAsRValue(Result, CGM.getContext()); + + llvm::Constant *C; + if (Success && !Result.HasSideEffects) + C = tryEmitPrivate(Result.Val, destType); + else + C = ConstExprEmitter(*this).Visit(const_cast<Expr*>(E), destType); + + return C; +} + +llvm::Constant *CodeGenModule::getNullPointer(llvm::PointerType *T, QualType QT) { + return getTargetCodeGenInfo().getNullPointer(*this, T, QT); +} + +namespace { +/// A struct which can be used to peephole certain kinds of finalization +/// that normally happen during l-value emission. +struct ConstantLValue { + llvm::Constant *Value; + bool HasOffsetApplied; + + /*implicit*/ ConstantLValue(llvm::Constant *value, + bool hasOffsetApplied = false) + : Value(value), HasOffsetApplied(false) {} + + /*implicit*/ ConstantLValue(ConstantAddress address) + : ConstantLValue(address.getPointer()) {} +}; + +/// A helper class for emitting constant l-values. +class ConstantLValueEmitter : public ConstStmtVisitor<ConstantLValueEmitter, + ConstantLValue> { + CodeGenModule &CGM; + ConstantEmitter &Emitter; + const APValue &Value; + QualType DestType; + + // Befriend StmtVisitorBase so that we don't have to expose Visit*. + friend StmtVisitorBase; + +public: + ConstantLValueEmitter(ConstantEmitter &emitter, const APValue &value, + QualType destType) + : CGM(emitter.CGM), Emitter(emitter), Value(value), DestType(destType) {} + + llvm::Constant *tryEmit(); + +private: + llvm::Constant *tryEmitAbsolute(llvm::Type *destTy); + ConstantLValue tryEmitBase(const APValue::LValueBase &base); + + ConstantLValue VisitStmt(const Stmt *S) { return nullptr; } + ConstantLValue VisitCompoundLiteralExpr(const CompoundLiteralExpr *E); + ConstantLValue VisitStringLiteral(const StringLiteral *E); + ConstantLValue VisitObjCEncodeExpr(const ObjCEncodeExpr *E); + ConstantLValue VisitObjCStringLiteral(const ObjCStringLiteral *E); + ConstantLValue VisitPredefinedExpr(const PredefinedExpr *E); + ConstantLValue VisitAddrLabelExpr(const AddrLabelExpr *E); + ConstantLValue VisitCallExpr(const CallExpr *E); + ConstantLValue VisitBlockExpr(const BlockExpr *E); + ConstantLValue VisitCXXTypeidExpr(const CXXTypeidExpr *E); + ConstantLValue VisitCXXUuidofExpr(const CXXUuidofExpr *E); + ConstantLValue VisitMaterializeTemporaryExpr( + const MaterializeTemporaryExpr *E); + + bool hasNonZeroOffset() const { + return !Value.getLValueOffset().isZero(); + } + + /// Return the value offset. + llvm::Constant *getOffset() { + return llvm::ConstantInt::get(CGM.Int64Ty, + Value.getLValueOffset().getQuantity()); + } + + /// Apply the value offset to the given constant. + llvm::Constant *applyOffset(llvm::Constant *C) { + if (!hasNonZeroOffset()) + return C; + + llvm::Type *origPtrTy = C->getType(); + unsigned AS = origPtrTy->getPointerAddressSpace(); + llvm::Type *charPtrTy = CGM.Int8Ty->getPointerTo(AS); + C = llvm::ConstantExpr::getBitCast(C, charPtrTy); + C = llvm::ConstantExpr::getGetElementPtr(CGM.Int8Ty, C, getOffset()); + C = llvm::ConstantExpr::getPointerCast(C, origPtrTy); + return C; + } +}; + +} + +llvm::Constant *ConstantLValueEmitter::tryEmit() { + const APValue::LValueBase &base = Value.getLValueBase(); + + // Certain special array initializers are represented in APValue + // as l-values referring to the base expression which generates the + // array. This happens with e.g. string literals. These should + // probably just get their own representation kind in APValue. + if (DestType->isArrayType()) { + assert(!hasNonZeroOffset() && "offset on array initializer"); + auto expr = const_cast<Expr*>(base.get<const Expr*>()); + return ConstExprEmitter(Emitter).Visit(expr, DestType); + } + + // Otherwise, the destination type should be a pointer or reference + // type, but it might also be a cast thereof. + // + // FIXME: the chain of casts required should be reflected in the APValue. + // We need this in order to correctly handle things like a ptrtoint of a + // non-zero null pointer and addrspace casts that aren't trivially + // represented in LLVM IR. + auto destTy = CGM.getTypes().ConvertTypeForMem(DestType); + assert(isa<llvm::IntegerType>(destTy) || isa<llvm::PointerType>(destTy)); + + // If there's no base at all, this is a null or absolute pointer, + // possibly cast back to an integer type. + if (!base) { + return tryEmitAbsolute(destTy); + } + + // Otherwise, try to emit the base. + ConstantLValue result = tryEmitBase(base); + + // If that failed, we're done. + llvm::Constant *value = result.Value; + if (!value) return nullptr; + + // Apply the offset if necessary and not already done. + if (!result.HasOffsetApplied) { + value = applyOffset(value); + } + + // Convert to the appropriate type; this could be an lvalue for + // an integer. FIXME: performAddrSpaceCast + if (isa<llvm::PointerType>(destTy)) + return llvm::ConstantExpr::getPointerCast(value, destTy); + + return llvm::ConstantExpr::getPtrToInt(value, destTy); +} + +/// Try to emit an absolute l-value, such as a null pointer or an integer +/// bitcast to pointer type. +llvm::Constant * +ConstantLValueEmitter::tryEmitAbsolute(llvm::Type *destTy) { + auto offset = getOffset(); + + // If we're producing a pointer, this is easy. + if (auto destPtrTy = cast<llvm::PointerType>(destTy)) { + if (Value.isNullPointer()) { + // FIXME: integer offsets from non-zero null pointers. + return CGM.getNullPointer(destPtrTy, DestType); + } + + // Convert the integer to a pointer-sized integer before converting it + // to a pointer. + // FIXME: signedness depends on the original integer type. + auto intptrTy = CGM.getDataLayout().getIntPtrType(destPtrTy); + llvm::Constant *C = offset; + C = llvm::ConstantExpr::getIntegerCast(getOffset(), intptrTy, + /*isSigned*/ false); + C = llvm::ConstantExpr::getIntToPtr(C, destPtrTy); + return C; + } + + // Otherwise, we're basically returning an integer constant. + + // FIXME: this does the wrong thing with ptrtoint of a null pointer, + // but since we don't know the original pointer type, there's not much + // we can do about it. + + auto C = getOffset(); + C = llvm::ConstantExpr::getIntegerCast(C, destTy, /*isSigned*/ false); + return C; +} + +ConstantLValue +ConstantLValueEmitter::tryEmitBase(const APValue::LValueBase &base) { + // Handle values. + if (const ValueDecl *D = base.dyn_cast<const ValueDecl*>()) { + if (D->hasAttr<WeakRefAttr>()) + return CGM.GetWeakRefReference(D).getPointer(); + + if (auto FD = dyn_cast<FunctionDecl>(D)) + return CGM.GetAddrOfFunction(FD); + + if (auto VD = dyn_cast<VarDecl>(D)) { + // We can never refer to a variable with local storage. + if (!VD->hasLocalStorage()) { + if (VD->isFileVarDecl() || VD->hasExternalStorage()) + return CGM.GetAddrOfGlobalVar(VD); + + if (VD->isLocalVarDecl()) { + return CGM.getOrCreateStaticVarDecl( + *VD, CGM.getLLVMLinkageVarDefinition(VD, /*isConstant=*/false)); + } + } + } + + return nullptr; + } + + // Otherwise, it must be an expression. + return Visit(base.get<const Expr*>()); +} + +ConstantLValue +ConstantLValueEmitter::VisitCompoundLiteralExpr(const CompoundLiteralExpr *E) { + return tryEmitGlobalCompoundLiteral(CGM, Emitter.CGF, E); +} + +ConstantLValue +ConstantLValueEmitter::VisitStringLiteral(const StringLiteral *E) { + return CGM.GetAddrOfConstantStringFromLiteral(E); +} + +ConstantLValue +ConstantLValueEmitter::VisitObjCEncodeExpr(const ObjCEncodeExpr *E) { + return CGM.GetAddrOfConstantStringFromObjCEncode(E); +} + +ConstantLValue +ConstantLValueEmitter::VisitObjCStringLiteral(const ObjCStringLiteral *E) { + auto C = CGM.getObjCRuntime().GenerateConstantString(E->getString()); + return C.getElementBitCast(CGM.getTypes().ConvertTypeForMem(E->getType())); +} + +ConstantLValue +ConstantLValueEmitter::VisitPredefinedExpr(const PredefinedExpr *E) { + if (auto CGF = Emitter.CGF) { + LValue Res = CGF->EmitPredefinedLValue(E); + return cast<ConstantAddress>(Res.getAddress()); + } + + auto kind = E->getIdentType(); + if (kind == PredefinedExpr::PrettyFunction) { + return CGM.GetAddrOfConstantCString("top level", ".tmp"); + } + + return CGM.GetAddrOfConstantCString("", ".tmp"); +} + +ConstantLValue +ConstantLValueEmitter::VisitAddrLabelExpr(const AddrLabelExpr *E) { + assert(Emitter.CGF && "Invalid address of label expression outside function"); + llvm::Constant *Ptr = Emitter.CGF->GetAddrOfLabel(E->getLabel()); + Ptr = llvm::ConstantExpr::getBitCast(Ptr, + CGM.getTypes().ConvertType(E->getType())); + return Ptr; +} + +ConstantLValue +ConstantLValueEmitter::VisitCallExpr(const CallExpr *E) { + unsigned builtin = E->getBuiltinCallee(); + if (builtin != Builtin::BI__builtin___CFStringMakeConstantString && + builtin != Builtin::BI__builtin___NSStringMakeConstantString) + return nullptr; + + auto literal = cast<StringLiteral>(E->getArg(0)->IgnoreParenCasts()); + if (builtin == Builtin::BI__builtin___NSStringMakeConstantString) { + return CGM.getObjCRuntime().GenerateConstantString(literal); + } else { + // FIXME: need to deal with UCN conversion issues. + return CGM.GetAddrOfConstantCFString(literal); + } +} + +ConstantLValue +ConstantLValueEmitter::VisitBlockExpr(const BlockExpr *E) { + StringRef functionName; + if (auto CGF = Emitter.CGF) + functionName = CGF->CurFn->getName(); + else + functionName = "global"; + + return CGM.GetAddrOfGlobalBlock(E, functionName); +} + +ConstantLValue +ConstantLValueEmitter::VisitCXXTypeidExpr(const CXXTypeidExpr *E) { + QualType T; + if (E->isTypeOperand()) + T = E->getTypeOperand(CGM.getContext()); + else + T = E->getExprOperand()->getType(); + return CGM.GetAddrOfRTTIDescriptor(T); +} + +ConstantLValue +ConstantLValueEmitter::VisitCXXUuidofExpr(const CXXUuidofExpr *E) { + return CGM.GetAddrOfUuidDescriptor(E); +} + +ConstantLValue +ConstantLValueEmitter::VisitMaterializeTemporaryExpr( + const MaterializeTemporaryExpr *E) { + assert(E->getStorageDuration() == SD_Static); + SmallVector<const Expr *, 2> CommaLHSs; + SmallVector<SubobjectAdjustment, 2> Adjustments; + const Expr *Inner = E->GetTemporaryExpr() + ->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments); + return CGM.GetAddrOfGlobalTemporary(E, Inner); +} + +llvm::Constant *ConstantEmitter::tryEmitPrivate(const APValue &Value, + QualType DestType) { + switch (Value.getKind()) { + case APValue::Uninitialized: + llvm_unreachable("Constant expressions should be initialized."); + case APValue::LValue: + return ConstantLValueEmitter(*this, Value, DestType).tryEmit(); + case APValue::Int: + return llvm::ConstantInt::get(CGM.getLLVMContext(), Value.getInt()); + case APValue::ComplexInt: { + llvm::Constant *Complex[2]; + + Complex[0] = llvm::ConstantInt::get(CGM.getLLVMContext(), + Value.getComplexIntReal()); + Complex[1] = llvm::ConstantInt::get(CGM.getLLVMContext(), + Value.getComplexIntImag()); + + // FIXME: the target may want to specify that this is packed. + llvm::StructType *STy = + llvm::StructType::get(Complex[0]->getType(), Complex[1]->getType()); + return llvm::ConstantStruct::get(STy, Complex); + } + case APValue::Float: { + const llvm::APFloat &Init = Value.getFloat(); + if (&Init.getSemantics() == &llvm::APFloat::IEEEhalf() && + !CGM.getContext().getLangOpts().NativeHalfType && + CGM.getContext().getTargetInfo().useFP16ConversionIntrinsics()) + return llvm::ConstantInt::get(CGM.getLLVMContext(), + Init.bitcastToAPInt()); + else + return llvm::ConstantFP::get(CGM.getLLVMContext(), Init); + } + case APValue::ComplexFloat: { + llvm::Constant *Complex[2]; + + Complex[0] = llvm::ConstantFP::get(CGM.getLLVMContext(), + Value.getComplexFloatReal()); + Complex[1] = llvm::ConstantFP::get(CGM.getLLVMContext(), + Value.getComplexFloatImag()); + + // FIXME: the target may want to specify that this is packed. + llvm::StructType *STy = + llvm::StructType::get(Complex[0]->getType(), Complex[1]->getType()); + return llvm::ConstantStruct::get(STy, Complex); + } + case APValue::Vector: { + unsigned NumElts = Value.getVectorLength(); + SmallVector<llvm::Constant *, 4> Inits(NumElts); + + for (unsigned I = 0; I != NumElts; ++I) { + const APValue &Elt = Value.getVectorElt(I); + if (Elt.isInt()) + Inits[I] = llvm::ConstantInt::get(CGM.getLLVMContext(), Elt.getInt()); + else if (Elt.isFloat()) + Inits[I] = llvm::ConstantFP::get(CGM.getLLVMContext(), Elt.getFloat()); + else + llvm_unreachable("unsupported vector element type"); + } + return llvm::ConstantVector::get(Inits); + } + case APValue::AddrLabelDiff: { + const AddrLabelExpr *LHSExpr = Value.getAddrLabelDiffLHS(); + const AddrLabelExpr *RHSExpr = Value.getAddrLabelDiffRHS(); + llvm::Constant *LHS = tryEmitPrivate(LHSExpr, LHSExpr->getType()); + llvm::Constant *RHS = tryEmitPrivate(RHSExpr, RHSExpr->getType()); + if (!LHS || !RHS) return nullptr; + + // Compute difference + llvm::Type *ResultType = CGM.getTypes().ConvertType(DestType); + LHS = llvm::ConstantExpr::getPtrToInt(LHS, CGM.IntPtrTy); + RHS = llvm::ConstantExpr::getPtrToInt(RHS, CGM.IntPtrTy); + llvm::Constant *AddrLabelDiff = llvm::ConstantExpr::getSub(LHS, RHS); + + // LLVM is a bit sensitive about the exact format of the + // address-of-label difference; make sure to truncate after + // the subtraction. + return llvm::ConstantExpr::getTruncOrBitCast(AddrLabelDiff, ResultType); + } + case APValue::Struct: + case APValue::Union: + return ConstStructBuilder::BuildStruct(*this, Value, DestType); + case APValue::Array: { + const ConstantArrayType *CAT = + CGM.getContext().getAsConstantArrayType(DestType); + unsigned NumElements = Value.getArraySize(); + unsigned NumInitElts = Value.getArrayInitializedElts(); + + // Emit array filler, if there is one. + llvm::Constant *Filler = nullptr; + if (Value.hasArrayFiller()) { + Filler = tryEmitAbstractForMemory(Value.getArrayFiller(), + CAT->getElementType()); + if (!Filler) + return nullptr; + } + + // Emit initializer elements. + SmallVector<llvm::Constant*, 16> Elts; + if (Filler && Filler->isNullValue()) + Elts.reserve(NumInitElts + 1); + else + Elts.reserve(NumElements); + + llvm::Type *CommonElementType = nullptr; + for (unsigned I = 0; I < NumInitElts; ++I) { + llvm::Constant *C = tryEmitPrivateForMemory( + Value.getArrayInitializedElt(I), CAT->getElementType()); + if (!C) return nullptr; + + if (I == 0) + CommonElementType = C->getType(); + else if (C->getType() != CommonElementType) + CommonElementType = nullptr; + Elts.push_back(C); + } + + return EmitArrayConstant(CGM, CAT, CommonElementType, NumElements, Elts, + Filler); + } + case APValue::MemberPointer: + return CGM.getCXXABI().EmitMemberPointer(Value, DestType); + } + llvm_unreachable("Unknown APValue kind"); +} + +llvm::GlobalVariable *CodeGenModule::getAddrOfConstantCompoundLiteralIfEmitted( + const CompoundLiteralExpr *E) { + return EmittedCompoundLiterals.lookup(E); +} + +void CodeGenModule::setAddrOfConstantCompoundLiteral( + const CompoundLiteralExpr *CLE, llvm::GlobalVariable *GV) { + bool Ok = EmittedCompoundLiterals.insert(std::make_pair(CLE, GV)).second; + (void)Ok; + assert(Ok && "CLE has already been emitted!"); +} + +ConstantAddress +CodeGenModule::GetAddrOfConstantCompoundLiteral(const CompoundLiteralExpr *E) { + assert(E->isFileScope() && "not a file-scope compound literal expr"); + return tryEmitGlobalCompoundLiteral(*this, nullptr, E); +} + +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().EmitMemberFunctionPointer(method); + + // Otherwise, a member data pointer. + uint64_t fieldOffset = getContext().getFieldOffset(decl); + CharUnits chars = getContext().toCharUnitsFromBits((int64_t) fieldOffset); + return getCXXABI().EmitMemberDataPointer(type, chars); +} + +static llvm::Constant *EmitNullConstantForBase(CodeGenModule &CGM, + llvm::Type *baseType, + const CXXRecordDecl *base); + +static llvm::Constant *EmitNullConstant(CodeGenModule &CGM, + const RecordDecl *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); + + auto CXXR = dyn_cast<CXXRecordDecl>(record); + // Fill in all the bases. + if (CXXR) { + for (const auto &I : CXXR->bases()) { + 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() || + CGM.getContext().getASTRecordLayout(base).getNonVirtualSize() + .isZero()) + continue; + + unsigned fieldIndex = layout.getNonVirtualBaseLLVMFieldNo(base); + llvm::Type *baseType = structure->getElementType(fieldIndex); + elements[fieldIndex] = EmitNullConstantForBase(CGM, baseType, base); + } + } + + // Fill in all the fields. + for (const auto *Field : record->fields()) { + // Fill in non-bitfields. (Bitfields always use a zero pattern, which we + // will fill in later.) + if (!Field->isBitField()) { + unsigned fieldIndex = layout.getLLVMFieldNo(Field); + elements[fieldIndex] = CGM.EmitNullConstant(Field->getType()); + } + + // For unions, stop after the first named field. + if (record->isUnion()) { + if (Field->getIdentifier()) + break; + if (const auto *FieldRD = Field->getType()->getAsRecordDecl()) + if (FieldRD->findFirstNamedDataMember()) + break; + } + } + + // Fill in the virtual bases, if we're working with the complete object. + if (CXXR && asCompleteObject) { + for (const auto &I : CXXR->vbases()) { + 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); + + // Otherwise, we can just use its null constant. + return EmitNullConstant(CGM, base, /*asCompleteObject=*/false); +} + +llvm::Constant *ConstantEmitter::emitNullForMemory(CodeGenModule &CGM, + QualType T) { + return emitForMemory(CGM, CGM.EmitNullConstant(T), T); +} + +llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) { + if (T->getAs<PointerType>()) + return getNullPointer( + cast<llvm::PointerType>(getTypes().ConvertTypeForMem(T)), T); + + if (getTypes().isZeroInitializable(T)) + return llvm::Constant::getNullValue(getTypes().ConvertTypeForMem(T)); + + if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(T)) { + llvm::ArrayType *ATy = + cast<llvm::ArrayType>(getTypes().ConvertTypeForMem(T)); + + QualType ElementTy = CAT->getElementType(); + + llvm::Constant *Element = + ConstantEmitter::emitNullForMemory(*this, ElementTy); + unsigned NumElements = CAT->getSize().getZExtValue(); + SmallVector<llvm::Constant *, 8> Array(NumElements, Element); + return llvm::ConstantArray::get(ATy, Array); + } + + if (const RecordType *RT = T->getAs<RecordType>()) + return ::EmitNullConstant(*this, RT->getDecl(), /*complete object*/ true); + + assert(T->isMemberDataPointerType() && + "Should only see pointers to data members here!"); + + return getCXXABI().EmitNullMemberPointer(T->castAs<MemberPointerType>()); +} + +llvm::Constant * +CodeGenModule::EmitNullConstantForBase(const CXXRecordDecl *Record) { + return ::EmitNullConstant(*this, Record, false); +} |