| //===--- CGExprConstant.cpp - Emit LLVM Code from Constant Expressions ----===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This contains code to emit Constant Expr nodes as LLVM code. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "CGCXXABI.h" |
| #include "CGObjCRuntime.h" |
| #include "CGRecordLayout.h" |
| #include "CodeGenFunction.h" |
| #include "CodeGenModule.h" |
| #include "ConstantEmitter.h" |
| #include "TargetInfo.h" |
| #include "clang/AST/APValue.h" |
| #include "clang/AST/ASTContext.h" |
| #include "clang/AST/Attr.h" |
| #include "clang/AST/RecordLayout.h" |
| #include "clang/AST/StmtVisitor.h" |
| #include "clang/Basic/Builtins.h" |
| #include "llvm/ADT/STLExtras.h" |
| #include "llvm/ADT/Sequence.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; |
| |
| //===----------------------------------------------------------------------===// |
| // ConstantAggregateBuilder |
| //===----------------------------------------------------------------------===// |
| |
| namespace { |
| class ConstExprEmitter; |
| |
| struct ConstantAggregateBuilderUtils { |
| CodeGenModule &CGM; |
| |
| ConstantAggregateBuilderUtils(CodeGenModule &CGM) : CGM(CGM) {} |
| |
| CharUnits getAlignment(const llvm::Constant *C) const { |
| return CharUnits::fromQuantity( |
| CGM.getDataLayout().getABITypeAlignment(C->getType())); |
| } |
| |
| CharUnits getSize(llvm::Type *Ty) const { |
| return CharUnits::fromQuantity(CGM.getDataLayout().getTypeAllocSize(Ty)); |
| } |
| |
| CharUnits getSize(const llvm::Constant *C) const { |
| return getSize(C->getType()); |
| } |
| |
| llvm::Constant *getPadding(CharUnits PadSize) const { |
| llvm::Type *Ty = CGM.Int8Ty; |
| if (PadSize > CharUnits::One()) |
| Ty = llvm::ArrayType::get(Ty, PadSize.getQuantity()); |
| return llvm::UndefValue::get(Ty); |
| } |
| |
| llvm::Constant *getZeroes(CharUnits ZeroSize) const { |
| llvm::Type *Ty = llvm::ArrayType::get(CGM.Int8Ty, ZeroSize.getQuantity()); |
| return llvm::ConstantAggregateZero::get(Ty); |
| } |
| }; |
| |
| /// Incremental builder for an llvm::Constant* holding a struct or array |
| /// constant. |
| class ConstantAggregateBuilder : private ConstantAggregateBuilderUtils { |
| /// The elements of the constant. These two arrays must have the same size; |
| /// Offsets[i] describes the offset of Elems[i] within the constant. The |
| /// elements are kept in increasing offset order, and we ensure that there |
| /// is no overlap: Offsets[i+1] >= Offsets[i] + getSize(Elemes[i]). |
| /// |
| /// This may contain explicit padding elements (in order to create a |
| /// natural layout), but need not. Gaps between elements are implicitly |
| /// considered to be filled with undef. |
| llvm::SmallVector<llvm::Constant*, 32> Elems; |
| llvm::SmallVector<CharUnits, 32> Offsets; |
| |
| /// The size of the constant (the maximum end offset of any added element). |
| /// May be larger than the end of Elems.back() if we split the last element |
| /// and removed some trailing undefs. |
| CharUnits Size = CharUnits::Zero(); |
| |
| /// This is true only if laying out Elems in order as the elements of a |
| /// non-packed LLVM struct will give the correct layout. |
| bool NaturalLayout = true; |
| |
| bool split(size_t Index, CharUnits Hint); |
| Optional<size_t> splitAt(CharUnits Pos); |
| |
| static llvm::Constant *buildFrom(CodeGenModule &CGM, |
| ArrayRef<llvm::Constant *> Elems, |
| ArrayRef<CharUnits> Offsets, |
| CharUnits StartOffset, CharUnits Size, |
| bool NaturalLayout, llvm::Type *DesiredTy, |
| bool AllowOversized); |
| |
| public: |
| ConstantAggregateBuilder(CodeGenModule &CGM) |
| : ConstantAggregateBuilderUtils(CGM) {} |
| |
| /// Update or overwrite the value starting at \p Offset with \c C. |
| /// |
| /// \param AllowOverwrite If \c true, this constant might overwrite (part of) |
| /// a constant that has already been added. This flag is only used to |
| /// detect bugs. |
| bool add(llvm::Constant *C, CharUnits Offset, bool AllowOverwrite); |
| |
| /// Update or overwrite the bits starting at \p OffsetInBits with \p Bits. |
| bool addBits(llvm::APInt Bits, uint64_t OffsetInBits, bool AllowOverwrite); |
| |
| /// Attempt to condense the value starting at \p Offset to a constant of type |
| /// \p DesiredTy. |
| void condense(CharUnits Offset, llvm::Type *DesiredTy); |
| |
| /// Produce a constant representing the entire accumulated value, ideally of |
| /// the specified type. If \p AllowOversized, the constant might be larger |
| /// than implied by \p DesiredTy (eg, if there is a flexible array member). |
| /// Otherwise, the constant will be of exactly the same size as \p DesiredTy |
| /// even if we can't represent it as that type. |
| llvm::Constant *build(llvm::Type *DesiredTy, bool AllowOversized) const { |
| return buildFrom(CGM, Elems, Offsets, CharUnits::Zero(), Size, |
| NaturalLayout, DesiredTy, AllowOversized); |
| } |
| }; |
| |
| template<typename Container, typename Range = std::initializer_list< |
| typename Container::value_type>> |
| static void replace(Container &C, size_t BeginOff, size_t EndOff, Range Vals) { |
| assert(BeginOff <= EndOff && "invalid replacement range"); |
| llvm::replace(C, C.begin() + BeginOff, C.begin() + EndOff, Vals); |
| } |
| |
| bool ConstantAggregateBuilder::add(llvm::Constant *C, CharUnits Offset, |
| bool AllowOverwrite) { |
| // Common case: appending to a layout. |
| if (Offset >= Size) { |
| CharUnits Align = getAlignment(C); |
| CharUnits AlignedSize = Size.alignTo(Align); |
| if (AlignedSize > Offset || Offset.alignTo(Align) != Offset) |
| NaturalLayout = false; |
| else if (AlignedSize < Offset) { |
| Elems.push_back(getPadding(Offset - Size)); |
| Offsets.push_back(Size); |
| } |
| Elems.push_back(C); |
| Offsets.push_back(Offset); |
| Size = Offset + getSize(C); |
| return true; |
| } |
| |
| // Uncommon case: constant overlaps what we've already created. |
| llvm::Optional<size_t> FirstElemToReplace = splitAt(Offset); |
| if (!FirstElemToReplace) |
| return false; |
| |
| CharUnits CSize = getSize(C); |
| llvm::Optional<size_t> LastElemToReplace = splitAt(Offset + CSize); |
| if (!LastElemToReplace) |
| return false; |
| |
| assert((FirstElemToReplace == LastElemToReplace || AllowOverwrite) && |
| "unexpectedly overwriting field"); |
| |
| replace(Elems, *FirstElemToReplace, *LastElemToReplace, {C}); |
| replace(Offsets, *FirstElemToReplace, *LastElemToReplace, {Offset}); |
| Size = std::max(Size, Offset + CSize); |
| NaturalLayout = false; |
| return true; |
| } |
| |
| bool ConstantAggregateBuilder::addBits(llvm::APInt Bits, uint64_t OffsetInBits, |
| bool AllowOverwrite) { |
| const ASTContext &Context = CGM.getContext(); |
| const uint64_t CharWidth = CGM.getContext().getCharWidth(); |
| |
| // Offset of where we want the first bit to go within the bits of the |
| // current char. |
| unsigned OffsetWithinChar = OffsetInBits % CharWidth; |
| |
| // We split bit-fields up into individual bytes. Walk over the bytes and |
| // update them. |
| for (CharUnits OffsetInChars = |
| Context.toCharUnitsFromBits(OffsetInBits - OffsetWithinChar); |
| /**/; ++OffsetInChars) { |
| // Number of bits we want to fill in this char. |
| unsigned WantedBits = |
| std::min((uint64_t)Bits.getBitWidth(), CharWidth - OffsetWithinChar); |
| |
| // Get a char containing the bits we want in the right places. The other |
| // bits have unspecified values. |
| llvm::APInt BitsThisChar = Bits; |
| if (BitsThisChar.getBitWidth() < CharWidth) |
| BitsThisChar = BitsThisChar.zext(CharWidth); |
| if (CGM.getDataLayout().isBigEndian()) { |
| // Figure out how much to shift by. We may need to left-shift if we have |
| // less than one byte of Bits left. |
| int Shift = Bits.getBitWidth() - CharWidth + OffsetWithinChar; |
| if (Shift > 0) |
| BitsThisChar.lshrInPlace(Shift); |
| else if (Shift < 0) |
| BitsThisChar = BitsThisChar.shl(-Shift); |
| } else { |
| BitsThisChar = BitsThisChar.shl(OffsetWithinChar); |
| } |
| if (BitsThisChar.getBitWidth() > CharWidth) |
| BitsThisChar = BitsThisChar.trunc(CharWidth); |
| |
| if (WantedBits == CharWidth) { |
| // Got a full byte: just add it directly. |
| add(llvm::ConstantInt::get(CGM.getLLVMContext(), BitsThisChar), |
| OffsetInChars, AllowOverwrite); |
| } else { |
| // Partial byte: update the existing integer if there is one. If we |
| // can't split out a 1-CharUnit range to update, then we can't add |
| // these bits and fail the entire constant emission. |
| llvm::Optional<size_t> FirstElemToUpdate = splitAt(OffsetInChars); |
| if (!FirstElemToUpdate) |
| return false; |
| llvm::Optional<size_t> LastElemToUpdate = |
| splitAt(OffsetInChars + CharUnits::One()); |
| if (!LastElemToUpdate) |
| return false; |
| assert(*LastElemToUpdate - *FirstElemToUpdate < 2 && |
| "should have at most one element covering one byte"); |
| |
| // Figure out which bits we want and discard the rest. |
| llvm::APInt UpdateMask(CharWidth, 0); |
| if (CGM.getDataLayout().isBigEndian()) |
| UpdateMask.setBits(CharWidth - OffsetWithinChar - WantedBits, |
| CharWidth - OffsetWithinChar); |
| else |
| UpdateMask.setBits(OffsetWithinChar, OffsetWithinChar + WantedBits); |
| BitsThisChar &= UpdateMask; |
| |
| if (*FirstElemToUpdate == *LastElemToUpdate || |
| Elems[*FirstElemToUpdate]->isNullValue() || |
| isa<llvm::UndefValue>(Elems[*FirstElemToUpdate])) { |
| // All existing bits are either zero or undef. |
| add(llvm::ConstantInt::get(CGM.getLLVMContext(), BitsThisChar), |
| OffsetInChars, /*AllowOverwrite*/ true); |
| } else { |
| llvm::Constant *&ToUpdate = Elems[*FirstElemToUpdate]; |
| // In order to perform a partial update, we need the existing bitwise |
| // value, which we can only extract for a constant int. |
| auto *CI = dyn_cast<llvm::ConstantInt>(ToUpdate); |
| if (!CI) |
| return false; |
| // Because this is a 1-CharUnit range, the constant occupying it must |
| // be exactly one CharUnit wide. |
| assert(CI->getBitWidth() == CharWidth && "splitAt failed"); |
| assert((!(CI->getValue() & UpdateMask) || AllowOverwrite) && |
| "unexpectedly overwriting bitfield"); |
| BitsThisChar |= (CI->getValue() & ~UpdateMask); |
| ToUpdate = llvm::ConstantInt::get(CGM.getLLVMContext(), BitsThisChar); |
| } |
| } |
| |
| // Stop if we've added all the bits. |
| if (WantedBits == Bits.getBitWidth()) |
| break; |
| |
| // Remove the consumed bits from Bits. |
| if (!CGM.getDataLayout().isBigEndian()) |
| Bits.lshrInPlace(WantedBits); |
| Bits = Bits.trunc(Bits.getBitWidth() - WantedBits); |
| |
| // The remanining bits go at the start of the following bytes. |
| OffsetWithinChar = 0; |
| } |
| |
| return true; |
| } |
| |
| /// Returns a position within Elems and Offsets such that all elements |
| /// before the returned index end before Pos and all elements at or after |
| /// the returned index begin at or after Pos. Splits elements as necessary |
| /// to ensure this. Returns None if we find something we can't split. |
| Optional<size_t> ConstantAggregateBuilder::splitAt(CharUnits Pos) { |
| if (Pos >= Size) |
| return Offsets.size(); |
| |
| while (true) { |
| auto FirstAfterPos = llvm::upper_bound(Offsets, Pos); |
| if (FirstAfterPos == Offsets.begin()) |
| return 0; |
| |
| // If we already have an element starting at Pos, we're done. |
| size_t LastAtOrBeforePosIndex = FirstAfterPos - Offsets.begin() - 1; |
| if (Offsets[LastAtOrBeforePosIndex] == Pos) |
| return LastAtOrBeforePosIndex; |
| |
| // We found an element starting before Pos. Check for overlap. |
| if (Offsets[LastAtOrBeforePosIndex] + |
| getSize(Elems[LastAtOrBeforePosIndex]) <= Pos) |
| return LastAtOrBeforePosIndex + 1; |
| |
| // Try to decompose it into smaller constants. |
| if (!split(LastAtOrBeforePosIndex, Pos)) |
| return None; |
| } |
| } |
| |
| /// Split the constant at index Index, if possible. Return true if we did. |
| /// Hint indicates the location at which we'd like to split, but may be |
| /// ignored. |
| bool ConstantAggregateBuilder::split(size_t Index, CharUnits Hint) { |
| NaturalLayout = false; |
| llvm::Constant *C = Elems[Index]; |
| CharUnits Offset = Offsets[Index]; |
| |
| if (auto *CA = dyn_cast<llvm::ConstantAggregate>(C)) { |
| // Expand the sequence into its contained elements. |
| // FIXME: This assumes vector elements are byte-sized. |
| replace(Elems, Index, Index + 1, |
| llvm::map_range(llvm::seq(0u, CA->getNumOperands()), |
| [&](unsigned Op) { return CA->getOperand(Op); })); |
| if (isa<llvm::ArrayType>(CA->getType()) || |
| isa<llvm::VectorType>(CA->getType())) { |
| // Array or vector. |
| llvm::Type *ElemTy = |
| llvm::GetElementPtrInst::getTypeAtIndex(CA->getType(), (uint64_t)0); |
| CharUnits ElemSize = getSize(ElemTy); |
| replace( |
| Offsets, Index, Index + 1, |
| llvm::map_range(llvm::seq(0u, CA->getNumOperands()), |
| [&](unsigned Op) { return Offset + Op * ElemSize; })); |
| } else { |
| // Must be a struct. |
| auto *ST = cast<llvm::StructType>(CA->getType()); |
| const llvm::StructLayout *Layout = |
| CGM.getDataLayout().getStructLayout(ST); |
| replace(Offsets, Index, Index + 1, |
| llvm::map_range( |
| llvm::seq(0u, CA->getNumOperands()), [&](unsigned Op) { |
| return Offset + CharUnits::fromQuantity( |
| Layout->getElementOffset(Op)); |
| })); |
| } |
| return true; |
| } |
| |
| if (auto *CDS = dyn_cast<llvm::ConstantDataSequential>(C)) { |
| // Expand the sequence into its contained elements. |
| // FIXME: This assumes vector elements are byte-sized. |
| // FIXME: If possible, split into two ConstantDataSequentials at Hint. |
| CharUnits ElemSize = getSize(CDS->getElementType()); |
| replace(Elems, Index, Index + 1, |
| llvm::map_range(llvm::seq(0u, CDS->getNumElements()), |
| [&](unsigned Elem) { |
| return CDS->getElementAsConstant(Elem); |
| })); |
| replace(Offsets, Index, Index + 1, |
| llvm::map_range( |
| llvm::seq(0u, CDS->getNumElements()), |
| [&](unsigned Elem) { return Offset + Elem * ElemSize; })); |
| return true; |
| } |
| |
| if (isa<llvm::ConstantAggregateZero>(C)) { |
| // Split into two zeros at the hinted offset. |
| CharUnits ElemSize = getSize(C); |
| assert(Hint > Offset && Hint < Offset + ElemSize && "nothing to split"); |
| replace(Elems, Index, Index + 1, |
| {getZeroes(Hint - Offset), getZeroes(Offset + ElemSize - Hint)}); |
| replace(Offsets, Index, Index + 1, {Offset, Hint}); |
| return true; |
| } |
| |
| if (isa<llvm::UndefValue>(C)) { |
| // Drop undef; it doesn't contribute to the final layout. |
| replace(Elems, Index, Index + 1, {}); |
| replace(Offsets, Index, Index + 1, {}); |
| return true; |
| } |
| |
| // FIXME: We could split a ConstantInt if the need ever arose. |
| // We don't need to do this to handle bit-fields because we always eagerly |
| // split them into 1-byte chunks. |
| |
| return false; |
| } |
| |
| static llvm::Constant * |
| EmitArrayConstant(CodeGenModule &CGM, llvm::ArrayType *DesiredType, |
| llvm::Type *CommonElementType, unsigned ArrayBound, |
| SmallVectorImpl<llvm::Constant *> &Elements, |
| llvm::Constant *Filler); |
| |
| llvm::Constant *ConstantAggregateBuilder::buildFrom( |
| CodeGenModule &CGM, ArrayRef<llvm::Constant *> Elems, |
| ArrayRef<CharUnits> Offsets, CharUnits StartOffset, CharUnits Size, |
| bool NaturalLayout, llvm::Type *DesiredTy, bool AllowOversized) { |
| ConstantAggregateBuilderUtils Utils(CGM); |
| |
| if (Elems.empty()) |
| return llvm::UndefValue::get(DesiredTy); |
| |
| auto Offset = [&](size_t I) { return Offsets[I] - StartOffset; }; |
| |
| // If we want an array type, see if all the elements are the same type and |
| // appropriately spaced. |
| if (llvm::ArrayType *ATy = dyn_cast<llvm::ArrayType>(DesiredTy)) { |
| assert(!AllowOversized && "oversized array emission not supported"); |
| |
| bool CanEmitArray = true; |
| llvm::Type *CommonType = Elems[0]->getType(); |
| llvm::Constant *Filler = llvm::Constant::getNullValue(CommonType); |
| CharUnits ElemSize = Utils.getSize(ATy->getElementType()); |
| SmallVector<llvm::Constant*, 32> ArrayElements; |
| for (size_t I = 0; I != Elems.size(); ++I) { |
| // Skip zeroes; we'll use a zero value as our array filler. |
| if (Elems[I]->isNullValue()) |
| continue; |
| |
| // All remaining elements must be the same type. |
| if (Elems[I]->getType() != CommonType || |
| Offset(I) % ElemSize != 0) { |
| CanEmitArray = false; |
| break; |
| } |
| ArrayElements.resize(Offset(I) / ElemSize + 1, Filler); |
| ArrayElements.back() = Elems[I]; |
| } |
| |
| if (CanEmitArray) { |
| return EmitArrayConstant(CGM, ATy, CommonType, ATy->getNumElements(), |
| ArrayElements, Filler); |
| } |
| |
| // Can't emit as an array, carry on to emit as a struct. |
| } |
| |
| CharUnits DesiredSize = Utils.getSize(DesiredTy); |
| CharUnits Align = CharUnits::One(); |
| for (llvm::Constant *C : Elems) |
| Align = std::max(Align, Utils.getAlignment(C)); |
| CharUnits AlignedSize = Size.alignTo(Align); |
| |
| bool Packed = false; |
| ArrayRef<llvm::Constant*> UnpackedElems = Elems; |
| llvm::SmallVector<llvm::Constant*, 32> UnpackedElemStorage; |
| if ((DesiredSize < AlignedSize && !AllowOversized) || |
| DesiredSize.alignTo(Align) != DesiredSize) { |
| // The natural layout would be the wrong size; force use of a packed layout. |
| NaturalLayout = false; |
| Packed = true; |
| } else if (DesiredSize > AlignedSize) { |
| // The constant would be too small. Add padding to fix it. |
| UnpackedElemStorage.assign(Elems.begin(), Elems.end()); |
| UnpackedElemStorage.push_back(Utils.getPadding(DesiredSize - Size)); |
| UnpackedElems = UnpackedElemStorage; |
| } |
| |
| // If we don't have a natural layout, insert padding as necessary. |
| // As we go, double-check to see if we can actually just emit Elems |
| // as a non-packed struct and do so opportunistically if possible. |
| llvm::SmallVector<llvm::Constant*, 32> PackedElems; |
| if (!NaturalLayout) { |
| CharUnits SizeSoFar = CharUnits::Zero(); |
| for (size_t I = 0; I != Elems.size(); ++I) { |
| CharUnits Align = Utils.getAlignment(Elems[I]); |
| CharUnits NaturalOffset = SizeSoFar.alignTo(Align); |
| CharUnits DesiredOffset = Offset(I); |
| assert(DesiredOffset >= SizeSoFar && "elements out of order"); |
| |
| if (DesiredOffset != NaturalOffset) |
| Packed = true; |
| if (DesiredOffset != SizeSoFar) |
| PackedElems.push_back(Utils.getPadding(DesiredOffset - SizeSoFar)); |
| PackedElems.push_back(Elems[I]); |
| SizeSoFar = DesiredOffset + Utils.getSize(Elems[I]); |
| } |
| // If we're using the packed layout, pad it out to the desired size if |
| // necessary. |
| if (Packed) { |
| assert((SizeSoFar <= DesiredSize || AllowOversized) && |
| "requested size is too small for contents"); |
| if (SizeSoFar < DesiredSize) |
| PackedElems.push_back(Utils.getPadding(DesiredSize - SizeSoFar)); |
| } |
| } |
| |
| llvm::StructType *STy = llvm::ConstantStruct::getTypeForElements( |
| CGM.getLLVMContext(), Packed ? PackedElems : UnpackedElems, Packed); |
| |
| // Pick the type to use. If the type is layout identical to the desired |
| // type then use it, otherwise use whatever the builder produced for us. |
| if (llvm::StructType *DesiredSTy = dyn_cast<llvm::StructType>(DesiredTy)) { |
| if (DesiredSTy->isLayoutIdentical(STy)) |
| STy = DesiredSTy; |
| } |
| |
| return llvm::ConstantStruct::get(STy, Packed ? PackedElems : UnpackedElems); |
| } |
| |
| void ConstantAggregateBuilder::condense(CharUnits Offset, |
| llvm::Type *DesiredTy) { |
| CharUnits Size = getSize(DesiredTy); |
| |
| llvm::Optional<size_t> FirstElemToReplace = splitAt(Offset); |
| if (!FirstElemToReplace) |
| return; |
| size_t First = *FirstElemToReplace; |
| |
| llvm::Optional<size_t> LastElemToReplace = splitAt(Offset + Size); |
| if (!LastElemToReplace) |
| return; |
| size_t Last = *LastElemToReplace; |
| |
| size_t Length = Last - First; |
| if (Length == 0) |
| return; |
| |
| if (Length == 1 && Offsets[First] == Offset && |
| getSize(Elems[First]) == Size) { |
| // Re-wrap single element structs if necessary. Otherwise, leave any single |
| // element constant of the right size alone even if it has the wrong type. |
| auto *STy = dyn_cast<llvm::StructType>(DesiredTy); |
| if (STy && STy->getNumElements() == 1 && |
| STy->getElementType(0) == Elems[First]->getType()) |
| Elems[First] = llvm::ConstantStruct::get(STy, Elems[First]); |
| return; |
| } |
| |
| llvm::Constant *Replacement = buildFrom( |
| CGM, makeArrayRef(Elems).slice(First, Length), |
| makeArrayRef(Offsets).slice(First, Length), Offset, getSize(DesiredTy), |
| /*known to have natural layout=*/false, DesiredTy, false); |
| replace(Elems, First, Last, {Replacement}); |
| replace(Offsets, First, Last, {Offset}); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // ConstStructBuilder |
| //===----------------------------------------------------------------------===// |
| |
| class ConstStructBuilder { |
| CodeGenModule &CGM; |
| ConstantEmitter &Emitter; |
| ConstantAggregateBuilder &Builder; |
| CharUnits StartOffset; |
| |
| public: |
| static llvm::Constant *BuildStruct(ConstantEmitter &Emitter, |
| InitListExpr *ILE, QualType StructTy); |
| static llvm::Constant *BuildStruct(ConstantEmitter &Emitter, |
| const APValue &Value, QualType ValTy); |
| static bool UpdateStruct(ConstantEmitter &Emitter, |
| ConstantAggregateBuilder &Const, CharUnits Offset, |
| InitListExpr *Updater); |
| |
| private: |
| ConstStructBuilder(ConstantEmitter &Emitter, |
| ConstantAggregateBuilder &Builder, CharUnits StartOffset) |
| : CGM(Emitter.CGM), Emitter(Emitter), Builder(Builder), |
| StartOffset(StartOffset) {} |
| |
| bool AppendField(const FieldDecl *Field, uint64_t FieldOffset, |
| llvm::Constant *InitExpr, bool AllowOverwrite = false); |
| |
| bool AppendBytes(CharUnits FieldOffsetInChars, llvm::Constant *InitCst, |
| bool AllowOverwrite = false); |
| |
| bool AppendBitField(const FieldDecl *Field, uint64_t FieldOffset, |
| llvm::ConstantInt *InitExpr, bool AllowOverwrite = false); |
| |
| bool Build(InitListExpr *ILE, bool AllowOverwrite); |
| bool Build(const APValue &Val, const RecordDecl *RD, bool IsPrimaryBase, |
| const CXXRecordDecl *VTableClass, CharUnits BaseOffset); |
| llvm::Constant *Finalize(QualType Ty); |
| }; |
| |
| bool ConstStructBuilder::AppendField( |
| const FieldDecl *Field, uint64_t FieldOffset, llvm::Constant *InitCst, |
| bool AllowOverwrite) { |
| const ASTContext &Context = CGM.getContext(); |
| |
| CharUnits FieldOffsetInChars = Context.toCharUnitsFromBits(FieldOffset); |
| |
| return AppendBytes(FieldOffsetInChars, InitCst, AllowOverwrite); |
| } |
| |
| bool ConstStructBuilder::AppendBytes(CharUnits FieldOffsetInChars, |
| llvm::Constant *InitCst, |
| bool AllowOverwrite) { |
| return Builder.add(InitCst, StartOffset + FieldOffsetInChars, AllowOverwrite); |
| } |
| |
| bool ConstStructBuilder::AppendBitField( |
| const FieldDecl *Field, uint64_t FieldOffset, llvm::ConstantInt *CI, |
| bool AllowOverwrite) { |
| const CGRecordLayout &RL = |
| CGM.getTypes().getCGRecordLayout(Field->getParent()); |
| const CGBitFieldInfo &Info = RL.getBitFieldInfo(Field); |
| 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 (Info.Size > FieldValue.getBitWidth()) |
| FieldValue = FieldValue.zext(Info.Size); |
| |
| // Truncate the size of FieldValue to the bit field size. |
| if (Info.Size < FieldValue.getBitWidth()) |
| FieldValue = FieldValue.trunc(Info.Size); |
| |
| return Builder.addBits(FieldValue, |
| CGM.getContext().toBits(StartOffset) + FieldOffset, |
| AllowOverwrite); |
| } |
| |
| static bool EmitDesignatedInitUpdater(ConstantEmitter &Emitter, |
| ConstantAggregateBuilder &Const, |
| CharUnits Offset, QualType Type, |
| InitListExpr *Updater) { |
| if (Type->isRecordType()) |
| return ConstStructBuilder::UpdateStruct(Emitter, Const, Offset, Updater); |
| |
| auto CAT = Emitter.CGM.getContext().getAsConstantArrayType(Type); |
| if (!CAT) |
| return false; |
| QualType ElemType = CAT->getElementType(); |
| CharUnits ElemSize = Emitter.CGM.getContext().getTypeSizeInChars(ElemType); |
| llvm::Type *ElemTy = Emitter.CGM.getTypes().ConvertTypeForMem(ElemType); |
| |
| llvm::Constant *FillC = nullptr; |
| if (Expr *Filler = Updater->getArrayFiller()) { |
| if (!isa<NoInitExpr>(Filler)) { |
| FillC = Emitter.tryEmitAbstractForMemory(Filler, ElemType); |
| if (!FillC) |
| return false; |
| } |
| } |
| |
| unsigned NumElementsToUpdate = |
| FillC ? CAT->getSize().getZExtValue() : Updater->getNumInits(); |
| for (unsigned I = 0; I != NumElementsToUpdate; ++I, Offset += ElemSize) { |
| Expr *Init = nullptr; |
| if (I < Updater->getNumInits()) |
| Init = Updater->getInit(I); |
| |
| if (!Init && FillC) { |
| if (!Const.add(FillC, Offset, true)) |
| return false; |
| } else if (!Init || isa<NoInitExpr>(Init)) { |
| continue; |
| } else if (InitListExpr *ChildILE = dyn_cast<InitListExpr>(Init)) { |
| if (!EmitDesignatedInitUpdater(Emitter, Const, Offset, ElemType, |
| ChildILE)) |
| return false; |
| // Attempt to reduce the array element to a single constant if necessary. |
| Const.condense(Offset, ElemTy); |
| } else { |
| llvm::Constant *Val = Emitter.tryEmitPrivateForMemory(Init, ElemType); |
| if (!Const.add(Val, Offset, true)) |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| bool ConstStructBuilder::Build(InitListExpr *ILE, bool AllowOverwrite) { |
| RecordDecl *RD = ILE->getType()->castAs<RecordType>()->getDecl(); |
| const ASTRecordLayout &Layout = CGM.getContext().getASTRecordLayout(RD); |
| |
| 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 this is a union, skip all the fields that aren't being initialized. |
| if (RD->isUnion() && |
| !declaresSameEntity(ILE->getInitializedFieldInUnion(), Field)) |
| continue; |
| |
| // Don't emit anonymous bitfields or zero-sized fields. |
| if (Field->isUnnamedBitfield() || Field->isZeroSize(CGM.getContext())) |
| continue; |
| |
| // Get the initializer. A struct can include fields without initializers, |
| // we just use explicit null values for them. |
| Expr *Init = nullptr; |
| if (ElementNo < ILE->getNumInits()) |
| Init = ILE->getInit(ElementNo++); |
| if (Init && isa<NoInitExpr>(Init)) |
| continue; |
| |
| // When emitting a DesignatedInitUpdateExpr, a nested InitListExpr |
| // represents additional overwriting of our current constant value, and not |
| // a new constant to emit independently. |
| if (AllowOverwrite && |
| (Field->getType()->isArrayType() || Field->getType()->isRecordType())) { |
| if (auto *SubILE = dyn_cast<InitListExpr>(Init)) { |
| CharUnits Offset = CGM.getContext().toCharUnitsFromBits( |
| Layout.getFieldOffset(FieldNo)); |
| if (!EmitDesignatedInitUpdater(Emitter, Builder, StartOffset + Offset, |
| Field->getType(), SubILE)) |
| return false; |
| // If we split apart the field's value, try to collapse it down to a |
| // single value now. |
| Builder.condense(StartOffset + Offset, |
| CGM.getTypes().ConvertTypeForMem(Field->getType())); |
| continue; |
| } |
| } |
| |
| llvm::Constant *EltInit = |
| Init ? Emitter.tryEmitPrivateForMemory(Init, Field->getType()) |
| : Emitter.emitNullForMemory(Field->getType()); |
| if (!EltInit) |
| return false; |
| |
| if (!Field->isBitField()) { |
| // Handle non-bitfield members. |
| if (!AppendField(Field, Layout.getFieldOffset(FieldNo), EltInit, |
| AllowOverwrite)) |
| return false; |
| // After emitting a non-empty field with [[no_unique_address]], we may |
| // need to overwrite its tail padding. |
| if (Field->hasAttr<NoUniqueAddressAttr>()) |
| AllowOverwrite = true; |
| } else { |
| // Otherwise we have a bitfield. |
| if (auto *CI = dyn_cast<llvm::ConstantInt>(EltInit)) { |
| if (!AppendBitField(Field, Layout.getFieldOffset(FieldNo), CI, |
| AllowOverwrite)) |
| return false; |
| } 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 (Layout.hasOwnVFPtr()) { |
| llvm::Constant *VTableAddressPoint = |
| CGM.getCXXABI().getVTableAddressPointForConstExpr( |
| BaseSubobject(CD, Offset), VTableClass); |
| if (!AppendBytes(Offset, VTableAddressPoint)) |
| return false; |
| } |
| |
| // 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)); |
| } |
| llvm::stable_sort(Bases); |
| |
| 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); |
| |
| bool AllowOverwrite = 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() && !declaresSameEntity(Val.getUnionField(), *Field)) |
| continue; |
| |
| // Don't emit anonymous bitfields or zero-sized fields. |
| if (Field->isUnnamedBitfield() || Field->isZeroSize(CGM.getContext())) |
| 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. |
| if (!AppendField(*Field, Layout.getFieldOffset(FieldNo) + OffsetBits, |
| EltInit, AllowOverwrite)) |
| return false; |
| // After emitting a non-empty field with [[no_unique_address]], we may |
| // need to overwrite its tail padding. |
| if (Field->hasAttr<NoUniqueAddressAttr>()) |
| AllowOverwrite = true; |
| } else { |
| // Otherwise we have a bitfield. |
| if (!AppendBitField(*Field, Layout.getFieldOffset(FieldNo) + OffsetBits, |
| cast<llvm::ConstantInt>(EltInit), AllowOverwrite)) |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| |
| llvm::Constant *ConstStructBuilder::Finalize(QualType Type) { |
| RecordDecl *RD = Type->castAs<RecordType>()->getDecl(); |
| llvm::Type *ValTy = CGM.getTypes().ConvertType(Type); |
| return Builder.build(ValTy, RD->hasFlexibleArrayMember()); |
| } |
| |
| llvm::Constant *ConstStructBuilder::BuildStruct(ConstantEmitter &Emitter, |
| InitListExpr *ILE, |
| QualType ValTy) { |
| ConstantAggregateBuilder Const(Emitter.CGM); |
| ConstStructBuilder Builder(Emitter, Const, CharUnits::Zero()); |
| |
| if (!Builder.Build(ILE, /*AllowOverwrite*/false)) |
| return nullptr; |
| |
| return Builder.Finalize(ValTy); |
| } |
| |
| llvm::Constant *ConstStructBuilder::BuildStruct(ConstantEmitter &Emitter, |
| const APValue &Val, |
| QualType ValTy) { |
| ConstantAggregateBuilder Const(Emitter.CGM); |
| ConstStructBuilder Builder(Emitter, Const, CharUnits::Zero()); |
| |
| 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); |
| } |
| |
| bool ConstStructBuilder::UpdateStruct(ConstantEmitter &Emitter, |
| ConstantAggregateBuilder &Const, |
| CharUnits Offset, InitListExpr *Updater) { |
| return ConstStructBuilder(Emitter, Const, Offset) |
| .Build(Updater, /*AllowOverwrite*/ true); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // 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.getAsAlign()); |
| CGM.setAddrOfConstantCompoundLiteral(E, GV); |
| return ConstantAddress(GV, Align); |
| } |
| |
| static llvm::Constant * |
| EmitArrayConstant(CodeGenModule &CGM, llvm::ArrayType *DesiredType, |
| 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(DesiredType); |
| |
| // 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 : DesiredType->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 arrays, structs and unions. Outside C++11 |
| // mode, we don't currently constant fold those types. All other types are |
| // handled by constant folding. |
| // |
| // Constant folding is currently missing support for a few features supported |
| // here: CK_ToUnion, CK_ReinterpretMemberPointer, and DesignatedInitUpdateExpr. |
| 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 *VisitConstantExpr(ConstantExpr *CE, QualType T) { |
| if (llvm::Constant *Result = Emitter.tryEmitConstantExpr(CE)) |
| return Result; |
| return Visit(CE->getSubExpr(), T); |
| } |
| |
| 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_LValueToRValueBitCast: |
| 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_FixedPointCast: |
| case CK_FixedPointToBoolean: |
| case CK_FixedPointToIntegral: |
| case CK_IntegralToFixedPoint: |
| case CK_ZeroToOCLOpaqueType: |
| return nullptr; |
| } |
| llvm_unreachable("Invalid CastKind"); |
| } |
| |
| 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) { |
| return Visit(E->getSubExpr(), T); |
| } |
| |
| llvm::Constant *VisitMaterializeTemporaryExpr(MaterializeTemporaryExpr *E, |
| QualType T) { |
| return Visit(E->getSubExpr(), 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); |
| } |
| |
| llvm::ArrayType *Desired = |
| cast<llvm::ArrayType>(CGM.getTypes().ConvertType(ILE->getType())); |
| return EmitArrayConstant(CGM, Desired, 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 *VisitDesignatedInitUpdateExpr(DesignatedInitUpdateExpr *E, |
| QualType destType) { |
| auto C = Visit(E->getBase(), destType); |
| if (!C) |
| return nullptr; |
| |
| ConstantAggregateBuilder Const(CGM); |
| Const.add(C, CharUnits::Zero(), false); |
| |
| if (!EmitDesignatedInitUpdater(Emitter, Const, CharUnits::Zero(), destType, |
| E->getUpdater())) |
| return nullptr; |
| |
| llvm::Type *ValTy = CGM.getTypes().ConvertType(destType); |
| bool HasFlexibleArray = false; |
| if (auto *RT = destType->getAs<RecordType>()) |
| HasFlexibleArray = RT->getDecl()->hasFlexibleArrayMember(); |
| return Const.build(ValTy, HasFlexibleArray); |
| } |
| |
| llvm::Constant *VisitCXXConstructExpr(CXXConstructExpr *E, QualType Ty) { |
| if (!E->getConstructor()->isTrivial()) |
| return nullptr; |
| |
| // Only default and copy/move 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) { |
| // This is a string literal initializing an array in an initializer. |
| 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. |
| |
| 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::tryEmitConstantExpr(const ConstantExpr *CE) { |
| if (!CE->hasAPValueResult()) |
| return nullptr; |
| const Expr *Inner = CE->getSubExpr()->IgnoreImplicit(); |
| QualType RetType; |
| if (auto *Call = dyn_cast<CallExpr>(Inner)) |
| RetType = Call->getCallReturnType(CGF->getContext()); |
| else if (auto *Ctor = dyn_cast<CXXConstructExpr>(Inner)) |
| RetType = Ctor->getType(); |
| llvm::Constant *Res = |
| emitAbstract(CE->getBeginLoc(), CE->getAPValueResult(), RetType); |
| return Res; |
| } |
| |
| 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()); |
| } |
| InConstantContext = true; |
| } |
| |
| 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(), InConstantContext); |
| |
| 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(hasOffsetApplied) {} |
| |
| /*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 VisitConstantExpr(const ConstantExpr *E); |
| ConstantLValue VisitCompoundLiteralExpr(const CompoundLiteralExpr *E); |
| ConstantLValue VisitStringLiteral(const StringLiteral *E); |
| ConstantLValue VisitObjCBoxedExpr(const ObjCBoxedExpr *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 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(); |
| |
| // 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) { |
| // If we're producing a pointer, this is easy. |
| 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; |
| C = llvm::ConstantExpr::getIntegerCast(getOffset(), intptrTy, |
| /*isSigned*/ false); |
| C = llvm::ConstantExpr::getIntToPtr(C, destPtrTy); |
| 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)); |
| } |
| } |
| } |
| |
| if (auto *GD = dyn_cast<MSGuidDecl>(D)) |
| return CGM.GetAddrOfMSGuidDecl(GD); |
| |
| return nullptr; |
| } |
| |
| // Handle typeid(T). |
| if (TypeInfoLValue TI = base.dyn_cast<TypeInfoLValue>()) { |
| llvm::Type *StdTypeInfoPtrTy = |
| CGM.getTypes().ConvertType(base.getTypeInfoType())->getPointerTo(); |
| llvm::Constant *TypeInfo = |
| CGM.GetAddrOfRTTIDescriptor(QualType(TI.getType(), 0)); |
| if (TypeInfo->getType() != StdTypeInfoPtrTy) |
| TypeInfo = llvm::ConstantExpr::getBitCast(TypeInfo, StdTypeInfoPtrTy); |
| return TypeInfo; |
| } |
| |
| // Otherwise, it must be an expression. |
| return Visit(base.get<const Expr*>()); |
| } |
| |
| ConstantLValue |
| ConstantLValueEmitter::VisitConstantExpr(const ConstantExpr *E) { |
| if (llvm::Constant *Result = Emitter.tryEmitConstantExpr(E)) |
| return Result; |
| return Visit(E->getSubExpr()); |
| } |
| |
| 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); |
| } |
| |
| static ConstantLValue emitConstantObjCStringLiteral(const StringLiteral *S, |
| QualType T, |
| CodeGenModule &CGM) { |
| auto C = CGM.getObjCRuntime().GenerateConstantString(S); |
| return C.getElementBitCast(CGM.getTypes().ConvertTypeForMem(T)); |
| } |
| |
| ConstantLValue |
| ConstantLValueEmitter::VisitObjCStringLiteral(const ObjCStringLiteral *E) { |
| return emitConstantObjCStringLiteral(E->getString(), E->getType(), CGM); |
| } |
| |
| ConstantLValue |
| ConstantLValueEmitter::VisitObjCBoxedExpr(const ObjCBoxedExpr *E) { |
| assert(E->isExpressibleAsConstantInitializer() && |
| "this boxed expression can't be emitted as a compile-time constant"); |
| auto *SL = cast<StringLiteral>(E->getSubExpr()->IgnoreParenCasts()); |
| return emitConstantObjCStringLiteral(SL, E->getType(), CGM); |
| } |
| |
| ConstantLValue |
| ConstantLValueEmitter::VisitPredefinedExpr(const PredefinedExpr *E) { |
| return CGM.GetAddrOfConstantStringFromLiteral(E->getFunctionName()); |
| } |
| |
| 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::VisitMaterializeTemporaryExpr( |
| const MaterializeTemporaryExpr *E) { |
| assert(E->getStorageDuration() == SD_Static); |
| SmallVector<const Expr *, 2> CommaLHSs; |
| SmallVector<SubobjectAdjustment, 2> Adjustments; |
| const Expr *Inner = |
| E->getSubExpr()->skipRValueSubobjectAdjustments(CommaLHSs, Adjustments); |
| return CGM.GetAddrOfGlobalTemporary(E, Inner); |
| } |
| |
| llvm::Constant *ConstantEmitter::tryEmitPrivate(const APValue &Value, |
| QualType DestType) { |
| switch (Value.getKind()) { |
| case APValue::None: |
| case APValue::Indeterminate: |
| // Out-of-lifetime and indeterminate values can be modeled as 'undef'. |
| return llvm::UndefValue::get(CGM.getTypes().ConvertType(DestType)); |
| case APValue::LValue: |
| return ConstantLValueEmitter(*this, Value, DestType).tryEmit(); |
| case APValue::Int: |
| return llvm::ConstantInt::get(CGM.getLLVMContext(), Value.getInt()); |
| case APValue::FixedPoint: |
| return llvm::ConstantInt::get(CGM.getLLVMContext(), |
| Value.getFixedPoint().getValue()); |
| 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); |
| } |
| |
| // This means that the array type is probably "IncompleteType" or some |
| // type that is not ConstantArray. |
| if (CAT == nullptr && CommonElementType == nullptr && !NumInitElts) { |
| const ArrayType *AT = CGM.getContext().getAsArrayType(DestType); |
| CommonElementType = CGM.getTypes().ConvertType(AT->getElementType()); |
| llvm::ArrayType *AType = llvm::ArrayType::get(CommonElementType, |
| NumElements); |
| return llvm::ConstantAggregateZero::get(AType); |
| } |
| |
| llvm::ArrayType *Desired = |
| cast<llvm::ArrayType>(CGM.getTypes().ConvertType(DestType)); |
| return EmitArrayConstant(CGM, Desired, 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() && !Field->isZeroSize(CGM.getContext())) { |
| 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); |
| } |