| //===--- CGRecordLayoutBuilder.cpp - CGRecordLayout builder ----*- C++ -*-===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // Builder implementation for CGRecordLayout objects. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "CGRecordLayout.h" |
| #include "clang/AST/ASTContext.h" |
| #include "clang/AST/Attr.h" |
| #include "clang/AST/CXXInheritance.h" |
| #include "clang/AST/DeclCXX.h" |
| #include "clang/AST/Expr.h" |
| #include "clang/AST/RecordLayout.h" |
| #include "clang/Frontend/CodeGenOptions.h" |
| #include "CodeGenTypes.h" |
| #include "CGCXXABI.h" |
| #include "llvm/DerivedTypes.h" |
| #include "llvm/Type.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/Target/TargetData.h" |
| using namespace clang; |
| using namespace CodeGen; |
| |
| namespace { |
| |
| class CGRecordLayoutBuilder { |
| public: |
| /// FieldTypes - Holds the LLVM types that the struct is created from. |
| /// |
| SmallVector<llvm::Type *, 16> FieldTypes; |
| |
| /// BaseSubobjectType - Holds the LLVM type for the non-virtual part |
| /// of the struct. For example, consider: |
| /// |
| /// struct A { int i; }; |
| /// struct B { void *v; }; |
| /// struct C : virtual A, B { }; |
| /// |
| /// The LLVM type of C will be |
| /// %struct.C = type { i32 (...)**, %struct.A, i32, %struct.B } |
| /// |
| /// And the LLVM type of the non-virtual base struct will be |
| /// %struct.C.base = type { i32 (...)**, %struct.A, i32 } |
| /// |
| /// This only gets initialized if the base subobject type is |
| /// different from the complete-object type. |
| llvm::StructType *BaseSubobjectType; |
| |
| /// FieldInfo - Holds a field and its corresponding LLVM field number. |
| llvm::DenseMap<const FieldDecl *, unsigned> Fields; |
| |
| /// BitFieldInfo - Holds location and size information about a bit field. |
| llvm::DenseMap<const FieldDecl *, CGBitFieldInfo> BitFields; |
| |
| llvm::DenseMap<const CXXRecordDecl *, unsigned> NonVirtualBases; |
| llvm::DenseMap<const CXXRecordDecl *, unsigned> VirtualBases; |
| |
| /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are |
| /// primary base classes for some other direct or indirect base class. |
| CXXIndirectPrimaryBaseSet IndirectPrimaryBases; |
| |
| /// LaidOutVirtualBases - A set of all laid out virtual bases, used to avoid |
| /// avoid laying out virtual bases more than once. |
| llvm::SmallPtrSet<const CXXRecordDecl *, 4> LaidOutVirtualBases; |
| |
| /// IsZeroInitializable - Whether this struct can be C++ |
| /// zero-initialized with an LLVM zeroinitializer. |
| bool IsZeroInitializable; |
| bool IsZeroInitializableAsBase; |
| |
| /// Packed - Whether the resulting LLVM struct will be packed or not. |
| bool Packed; |
| |
| /// IsMsStruct - Whether ms_struct is in effect or not |
| bool IsMsStruct; |
| |
| private: |
| CodeGenTypes &Types; |
| |
| /// LastLaidOutBaseInfo - Contains the offset and non-virtual size of the |
| /// last base laid out. Used so that we can replace the last laid out base |
| /// type with an i8 array if needed. |
| struct LastLaidOutBaseInfo { |
| CharUnits Offset; |
| CharUnits NonVirtualSize; |
| |
| bool isValid() const { return !NonVirtualSize.isZero(); } |
| void invalidate() { NonVirtualSize = CharUnits::Zero(); } |
| |
| } LastLaidOutBase; |
| |
| /// Alignment - Contains the alignment of the RecordDecl. |
| CharUnits Alignment; |
| |
| /// BitsAvailableInLastField - If a bit field spans only part of a LLVM field, |
| /// this will have the number of bits still available in the field. |
| char BitsAvailableInLastField; |
| |
| /// NextFieldOffset - Holds the next field offset. |
| CharUnits NextFieldOffset; |
| |
| /// LayoutUnionField - Will layout a field in an union and return the type |
| /// that the field will have. |
| llvm::Type *LayoutUnionField(const FieldDecl *Field, |
| const ASTRecordLayout &Layout); |
| |
| /// LayoutUnion - Will layout a union RecordDecl. |
| void LayoutUnion(const RecordDecl *D); |
| |
| /// LayoutField - try to layout all fields in the record decl. |
| /// Returns false if the operation failed because the struct is not packed. |
| bool LayoutFields(const RecordDecl *D); |
| |
| /// Layout a single base, virtual or non-virtual |
| bool LayoutBase(const CXXRecordDecl *base, |
| const CGRecordLayout &baseLayout, |
| CharUnits baseOffset); |
| |
| /// LayoutVirtualBase - layout a single virtual base. |
| bool LayoutVirtualBase(const CXXRecordDecl *base, |
| CharUnits baseOffset); |
| |
| /// LayoutVirtualBases - layout the virtual bases of a record decl. |
| bool LayoutVirtualBases(const CXXRecordDecl *RD, |
| const ASTRecordLayout &Layout); |
| |
| /// MSLayoutVirtualBases - layout the virtual bases of a record decl, |
| /// like MSVC. |
| bool MSLayoutVirtualBases(const CXXRecordDecl *RD, |
| const ASTRecordLayout &Layout); |
| |
| /// LayoutNonVirtualBase - layout a single non-virtual base. |
| bool LayoutNonVirtualBase(const CXXRecordDecl *base, |
| CharUnits baseOffset); |
| |
| /// LayoutNonVirtualBases - layout the virtual bases of a record decl. |
| bool LayoutNonVirtualBases(const CXXRecordDecl *RD, |
| const ASTRecordLayout &Layout); |
| |
| /// ComputeNonVirtualBaseType - Compute the non-virtual base field types. |
| bool ComputeNonVirtualBaseType(const CXXRecordDecl *RD); |
| |
| /// LayoutField - layout a single field. Returns false if the operation failed |
| /// because the current struct is not packed. |
| bool LayoutField(const FieldDecl *D, uint64_t FieldOffset); |
| |
| /// LayoutBitField - layout a single bit field. |
| void LayoutBitField(const FieldDecl *D, uint64_t FieldOffset); |
| |
| /// AppendField - Appends a field with the given offset and type. |
| void AppendField(CharUnits fieldOffset, llvm::Type *FieldTy); |
| |
| /// AppendPadding - Appends enough padding bytes so that the total |
| /// struct size is a multiple of the field alignment. |
| void AppendPadding(CharUnits fieldOffset, CharUnits fieldAlignment); |
| |
| /// ResizeLastBaseFieldIfNecessary - Fields and bases can be laid out in the |
| /// tail padding of a previous base. If this happens, the type of the previous |
| /// base needs to be changed to an array of i8. Returns true if the last |
| /// laid out base was resized. |
| bool ResizeLastBaseFieldIfNecessary(CharUnits offset); |
| |
| /// getByteArrayType - Returns a byte array type with the given number of |
| /// elements. |
| llvm::Type *getByteArrayType(CharUnits NumBytes); |
| |
| /// AppendBytes - Append a given number of bytes to the record. |
| void AppendBytes(CharUnits numBytes); |
| |
| /// AppendTailPadding - Append enough tail padding so that the type will have |
| /// the passed size. |
| void AppendTailPadding(CharUnits RecordSize); |
| |
| CharUnits getTypeAlignment(llvm::Type *Ty) const; |
| |
| /// getAlignmentAsLLVMStruct - Returns the maximum alignment of all the |
| /// LLVM element types. |
| CharUnits getAlignmentAsLLVMStruct() const; |
| |
| /// CheckZeroInitializable - Check if the given type contains a pointer |
| /// to data member. |
| void CheckZeroInitializable(QualType T); |
| |
| public: |
| CGRecordLayoutBuilder(CodeGenTypes &Types) |
| : BaseSubobjectType(0), |
| IsZeroInitializable(true), IsZeroInitializableAsBase(true), |
| Packed(false), IsMsStruct(false), |
| Types(Types), BitsAvailableInLastField(0) { } |
| |
| /// Layout - Will layout a RecordDecl. |
| void Layout(const RecordDecl *D); |
| }; |
| |
| } |
| |
| void CGRecordLayoutBuilder::Layout(const RecordDecl *D) { |
| Alignment = Types.getContext().getASTRecordLayout(D).getAlignment(); |
| Packed = D->hasAttr<PackedAttr>(); |
| |
| IsMsStruct = D->hasAttr<MsStructAttr>(); |
| |
| if (D->isUnion()) { |
| LayoutUnion(D); |
| return; |
| } |
| |
| if (LayoutFields(D)) |
| return; |
| |
| // We weren't able to layout the struct. Try again with a packed struct |
| Packed = true; |
| LastLaidOutBase.invalidate(); |
| NextFieldOffset = CharUnits::Zero(); |
| FieldTypes.clear(); |
| Fields.clear(); |
| BitFields.clear(); |
| NonVirtualBases.clear(); |
| VirtualBases.clear(); |
| |
| LayoutFields(D); |
| } |
| |
| CGBitFieldInfo CGBitFieldInfo::MakeInfo(CodeGenTypes &Types, |
| const FieldDecl *FD, |
| uint64_t FieldOffset, |
| uint64_t FieldSize, |
| uint64_t ContainingTypeSizeInBits, |
| unsigned ContainingTypeAlign) { |
| assert(ContainingTypeAlign && "Expected alignment to be specified"); |
| |
| llvm::Type *Ty = Types.ConvertTypeForMem(FD->getType()); |
| CharUnits TypeSizeInBytes = |
| CharUnits::fromQuantity(Types.getTargetData().getTypeAllocSize(Ty)); |
| uint64_t TypeSizeInBits = Types.getContext().toBits(TypeSizeInBytes); |
| |
| bool IsSigned = FD->getType()->isSignedIntegerOrEnumerationType(); |
| |
| if (FieldSize > TypeSizeInBits) { |
| // We have a wide bit-field. The extra bits are only used for padding, so |
| // if we have a bitfield of type T, with size N: |
| // |
| // T t : N; |
| // |
| // We can just assume that it's: |
| // |
| // T t : sizeof(T); |
| // |
| FieldSize = TypeSizeInBits; |
| } |
| |
| // in big-endian machines the first fields are in higher bit positions, |
| // so revert the offset. The byte offsets are reversed(back) later. |
| if (Types.getTargetData().isBigEndian()) { |
| FieldOffset = ((ContainingTypeSizeInBits)-FieldOffset-FieldSize); |
| } |
| |
| // Compute the access components. The policy we use is to start by attempting |
| // to access using the width of the bit-field type itself and to always access |
| // at aligned indices of that type. If such an access would fail because it |
| // extends past the bound of the type, then we reduce size to the next smaller |
| // power of two and retry. The current algorithm assumes pow2 sized types, |
| // although this is easy to fix. |
| // |
| assert(llvm::isPowerOf2_32(TypeSizeInBits) && "Unexpected type size!"); |
| CGBitFieldInfo::AccessInfo Components[3]; |
| unsigned NumComponents = 0; |
| unsigned AccessedTargetBits = 0; // The number of target bits accessed. |
| unsigned AccessWidth = TypeSizeInBits; // The current access width to attempt. |
| |
| // If requested, widen the initial bit-field access to be register sized. The |
| // theory is that this is most likely to allow multiple accesses into the same |
| // structure to be coalesced, and that the backend should be smart enough to |
| // narrow the store if no coalescing is ever done. |
| // |
| // The subsequent code will handle align these access to common boundaries and |
| // guaranteeing that we do not access past the end of the structure. |
| if (Types.getCodeGenOpts().UseRegisterSizedBitfieldAccess) { |
| if (AccessWidth < Types.getTarget().getRegisterWidth()) |
| AccessWidth = Types.getTarget().getRegisterWidth(); |
| } |
| |
| // Round down from the field offset to find the first access position that is |
| // at an aligned offset of the initial access type. |
| uint64_t AccessStart = FieldOffset - (FieldOffset % AccessWidth); |
| |
| // Adjust initial access size to fit within record. |
| while (AccessWidth > Types.getTarget().getCharWidth() && |
| AccessStart + AccessWidth > ContainingTypeSizeInBits) { |
| AccessWidth >>= 1; |
| AccessStart = FieldOffset - (FieldOffset % AccessWidth); |
| } |
| |
| while (AccessedTargetBits < FieldSize) { |
| // Check that we can access using a type of this size, without reading off |
| // the end of the structure. This can occur with packed structures and |
| // -fno-bitfield-type-align, for example. |
| if (AccessStart + AccessWidth > ContainingTypeSizeInBits) { |
| // If so, reduce access size to the next smaller power-of-two and retry. |
| AccessWidth >>= 1; |
| assert(AccessWidth >= Types.getTarget().getCharWidth() |
| && "Cannot access under byte size!"); |
| continue; |
| } |
| |
| // Otherwise, add an access component. |
| |
| // First, compute the bits inside this access which are part of the |
| // target. We are reading bits [AccessStart, AccessStart + AccessWidth); the |
| // intersection with [FieldOffset, FieldOffset + FieldSize) gives the bits |
| // in the target that we are reading. |
| assert(FieldOffset < AccessStart + AccessWidth && "Invalid access start!"); |
| assert(AccessStart < FieldOffset + FieldSize && "Invalid access start!"); |
| uint64_t AccessBitsInFieldStart = std::max(AccessStart, FieldOffset); |
| uint64_t AccessBitsInFieldSize = |
| std::min(AccessWidth + AccessStart, |
| FieldOffset + FieldSize) - AccessBitsInFieldStart; |
| |
| assert(NumComponents < 3 && "Unexpected number of components!"); |
| CGBitFieldInfo::AccessInfo &AI = Components[NumComponents++]; |
| AI.FieldIndex = 0; |
| // FIXME: We still follow the old access pattern of only using the field |
| // byte offset. We should switch this once we fix the struct layout to be |
| // pretty. |
| |
| // on big-endian machines we reverted the bit offset because first fields are |
| // in higher bits. But this also reverts the bytes, so fix this here by reverting |
| // the byte offset on big-endian machines. |
| if (Types.getTargetData().isBigEndian()) { |
| AI.FieldByteOffset = Types.getContext().toCharUnitsFromBits( |
| ContainingTypeSizeInBits - AccessStart - AccessWidth); |
| } else { |
| AI.FieldByteOffset = Types.getContext().toCharUnitsFromBits(AccessStart); |
| } |
| AI.FieldBitStart = AccessBitsInFieldStart - AccessStart; |
| AI.AccessWidth = AccessWidth; |
| AI.AccessAlignment = Types.getContext().toCharUnitsFromBits( |
| llvm::MinAlign(ContainingTypeAlign, AccessStart)); |
| AI.TargetBitOffset = AccessedTargetBits; |
| AI.TargetBitWidth = AccessBitsInFieldSize; |
| |
| AccessStart += AccessWidth; |
| AccessedTargetBits += AI.TargetBitWidth; |
| } |
| |
| assert(AccessedTargetBits == FieldSize && "Invalid bit-field access!"); |
| return CGBitFieldInfo(FieldSize, NumComponents, Components, IsSigned); |
| } |
| |
| CGBitFieldInfo CGBitFieldInfo::MakeInfo(CodeGenTypes &Types, |
| const FieldDecl *FD, |
| uint64_t FieldOffset, |
| uint64_t FieldSize) { |
| const RecordDecl *RD = FD->getParent(); |
| const ASTRecordLayout &RL = Types.getContext().getASTRecordLayout(RD); |
| uint64_t ContainingTypeSizeInBits = Types.getContext().toBits(RL.getSize()); |
| unsigned ContainingTypeAlign = Types.getContext().toBits(RL.getAlignment()); |
| |
| return MakeInfo(Types, FD, FieldOffset, FieldSize, ContainingTypeSizeInBits, |
| ContainingTypeAlign); |
| } |
| |
| void CGRecordLayoutBuilder::LayoutBitField(const FieldDecl *D, |
| uint64_t fieldOffset) { |
| uint64_t fieldSize = D->getBitWidthValue(Types.getContext()); |
| |
| if (fieldSize == 0) |
| return; |
| |
| uint64_t nextFieldOffsetInBits = Types.getContext().toBits(NextFieldOffset); |
| CharUnits numBytesToAppend; |
| unsigned charAlign = Types.getContext().getTargetInfo().getCharAlign(); |
| |
| if (fieldOffset < nextFieldOffsetInBits && !BitsAvailableInLastField) { |
| assert(fieldOffset % charAlign == 0 && |
| "Field offset not aligned correctly"); |
| |
| CharUnits fieldOffsetInCharUnits = |
| Types.getContext().toCharUnitsFromBits(fieldOffset); |
| |
| // Try to resize the last base field. |
| if (ResizeLastBaseFieldIfNecessary(fieldOffsetInCharUnits)) |
| nextFieldOffsetInBits = Types.getContext().toBits(NextFieldOffset); |
| } |
| |
| if (fieldOffset < nextFieldOffsetInBits) { |
| assert(BitsAvailableInLastField && "Bitfield size mismatch!"); |
| assert(!NextFieldOffset.isZero() && "Must have laid out at least one byte"); |
| |
| // The bitfield begins in the previous bit-field. |
| numBytesToAppend = Types.getContext().toCharUnitsFromBits( |
| llvm::RoundUpToAlignment(fieldSize - BitsAvailableInLastField, |
| charAlign)); |
| } else { |
| assert(fieldOffset % charAlign == 0 && |
| "Field offset not aligned correctly"); |
| |
| // Append padding if necessary. |
| AppendPadding(Types.getContext().toCharUnitsFromBits(fieldOffset), |
| CharUnits::One()); |
| |
| numBytesToAppend = Types.getContext().toCharUnitsFromBits( |
| llvm::RoundUpToAlignment(fieldSize, charAlign)); |
| |
| assert(!numBytesToAppend.isZero() && "No bytes to append!"); |
| } |
| |
| // Add the bit field info. |
| BitFields.insert(std::make_pair(D, |
| CGBitFieldInfo::MakeInfo(Types, D, fieldOffset, fieldSize))); |
| |
| AppendBytes(numBytesToAppend); |
| |
| BitsAvailableInLastField = |
| Types.getContext().toBits(NextFieldOffset) - (fieldOffset + fieldSize); |
| } |
| |
| bool CGRecordLayoutBuilder::LayoutField(const FieldDecl *D, |
| uint64_t fieldOffset) { |
| // If the field is packed, then we need a packed struct. |
| if (!Packed && D->hasAttr<PackedAttr>()) |
| return false; |
| |
| if (D->isBitField()) { |
| // We must use packed structs for unnamed bit fields since they |
| // don't affect the struct alignment. |
| if (!Packed && !D->getDeclName()) |
| return false; |
| |
| LayoutBitField(D, fieldOffset); |
| return true; |
| } |
| |
| CheckZeroInitializable(D->getType()); |
| |
| assert(fieldOffset % Types.getTarget().getCharWidth() == 0 |
| && "field offset is not on a byte boundary!"); |
| CharUnits fieldOffsetInBytes |
| = Types.getContext().toCharUnitsFromBits(fieldOffset); |
| |
| llvm::Type *Ty = Types.ConvertTypeForMem(D->getType()); |
| CharUnits typeAlignment = getTypeAlignment(Ty); |
| |
| // If the type alignment is larger then the struct alignment, we must use |
| // a packed struct. |
| if (typeAlignment > Alignment) { |
| assert(!Packed && "Alignment is wrong even with packed struct!"); |
| return false; |
| } |
| |
| if (!Packed) { |
| if (const RecordType *RT = D->getType()->getAs<RecordType>()) { |
| const RecordDecl *RD = cast<RecordDecl>(RT->getDecl()); |
| if (const MaxFieldAlignmentAttr *MFAA = |
| RD->getAttr<MaxFieldAlignmentAttr>()) { |
| if (MFAA->getAlignment() != Types.getContext().toBits(typeAlignment)) |
| return false; |
| } |
| } |
| } |
| |
| // Round up the field offset to the alignment of the field type. |
| CharUnits alignedNextFieldOffsetInBytes = |
| NextFieldOffset.RoundUpToAlignment(typeAlignment); |
| |
| if (fieldOffsetInBytes < alignedNextFieldOffsetInBytes) { |
| // Try to resize the last base field. |
| if (ResizeLastBaseFieldIfNecessary(fieldOffsetInBytes)) { |
| alignedNextFieldOffsetInBytes = |
| NextFieldOffset.RoundUpToAlignment(typeAlignment); |
| } |
| } |
| |
| if (fieldOffsetInBytes < alignedNextFieldOffsetInBytes) { |
| assert(!Packed && "Could not place field even with packed struct!"); |
| return false; |
| } |
| |
| AppendPadding(fieldOffsetInBytes, typeAlignment); |
| |
| // Now append the field. |
| Fields[D] = FieldTypes.size(); |
| AppendField(fieldOffsetInBytes, Ty); |
| |
| LastLaidOutBase.invalidate(); |
| return true; |
| } |
| |
| llvm::Type * |
| CGRecordLayoutBuilder::LayoutUnionField(const FieldDecl *Field, |
| const ASTRecordLayout &Layout) { |
| if (Field->isBitField()) { |
| uint64_t FieldSize = Field->getBitWidthValue(Types.getContext()); |
| |
| // Ignore zero sized bit fields. |
| if (FieldSize == 0) |
| return 0; |
| |
| llvm::Type *FieldTy = llvm::Type::getInt8Ty(Types.getLLVMContext()); |
| CharUnits NumBytesToAppend = Types.getContext().toCharUnitsFromBits( |
| llvm::RoundUpToAlignment(FieldSize, |
| Types.getContext().getTargetInfo().getCharAlign())); |
| |
| if (NumBytesToAppend > CharUnits::One()) |
| FieldTy = llvm::ArrayType::get(FieldTy, NumBytesToAppend.getQuantity()); |
| |
| // Add the bit field info. |
| BitFields.insert(std::make_pair(Field, |
| CGBitFieldInfo::MakeInfo(Types, Field, 0, FieldSize))); |
| return FieldTy; |
| } |
| |
| // This is a regular union field. |
| Fields[Field] = 0; |
| return Types.ConvertTypeForMem(Field->getType()); |
| } |
| |
| void CGRecordLayoutBuilder::LayoutUnion(const RecordDecl *D) { |
| assert(D->isUnion() && "Can't call LayoutUnion on a non-union record!"); |
| |
| const ASTRecordLayout &layout = Types.getContext().getASTRecordLayout(D); |
| |
| llvm::Type *unionType = 0; |
| CharUnits unionSize = CharUnits::Zero(); |
| CharUnits unionAlign = CharUnits::Zero(); |
| |
| bool hasOnlyZeroSizedBitFields = true; |
| bool checkedFirstFieldZeroInit = false; |
| |
| unsigned fieldNo = 0; |
| for (RecordDecl::field_iterator field = D->field_begin(), |
| fieldEnd = D->field_end(); field != fieldEnd; ++field, ++fieldNo) { |
| assert(layout.getFieldOffset(fieldNo) == 0 && |
| "Union field offset did not start at the beginning of record!"); |
| llvm::Type *fieldType = LayoutUnionField(*field, layout); |
| |
| if (!fieldType) |
| continue; |
| |
| if (field->getDeclName() && !checkedFirstFieldZeroInit) { |
| CheckZeroInitializable(field->getType()); |
| checkedFirstFieldZeroInit = true; |
| } |
| |
| hasOnlyZeroSizedBitFields = false; |
| |
| CharUnits fieldAlign = CharUnits::fromQuantity( |
| Types.getTargetData().getABITypeAlignment(fieldType)); |
| CharUnits fieldSize = CharUnits::fromQuantity( |
| Types.getTargetData().getTypeAllocSize(fieldType)); |
| |
| if (fieldAlign < unionAlign) |
| continue; |
| |
| if (fieldAlign > unionAlign || fieldSize > unionSize) { |
| unionType = fieldType; |
| unionAlign = fieldAlign; |
| unionSize = fieldSize; |
| } |
| } |
| |
| // Now add our field. |
| if (unionType) { |
| AppendField(CharUnits::Zero(), unionType); |
| |
| if (getTypeAlignment(unionType) > layout.getAlignment()) { |
| // We need a packed struct. |
| Packed = true; |
| unionAlign = CharUnits::One(); |
| } |
| } |
| if (unionAlign.isZero()) { |
| (void)hasOnlyZeroSizedBitFields; |
| assert(hasOnlyZeroSizedBitFields && |
| "0-align record did not have all zero-sized bit-fields!"); |
| unionAlign = CharUnits::One(); |
| } |
| |
| // Append tail padding. |
| CharUnits recordSize = layout.getSize(); |
| if (recordSize > unionSize) |
| AppendPadding(recordSize, unionAlign); |
| } |
| |
| bool CGRecordLayoutBuilder::LayoutBase(const CXXRecordDecl *base, |
| const CGRecordLayout &baseLayout, |
| CharUnits baseOffset) { |
| ResizeLastBaseFieldIfNecessary(baseOffset); |
| |
| AppendPadding(baseOffset, CharUnits::One()); |
| |
| const ASTRecordLayout &baseASTLayout |
| = Types.getContext().getASTRecordLayout(base); |
| |
| LastLaidOutBase.Offset = NextFieldOffset; |
| LastLaidOutBase.NonVirtualSize = baseASTLayout.getNonVirtualSize(); |
| |
| llvm::StructType *subobjectType = baseLayout.getBaseSubobjectLLVMType(); |
| if (getTypeAlignment(subobjectType) > Alignment) |
| return false; |
| |
| AppendField(baseOffset, subobjectType); |
| return true; |
| } |
| |
| bool CGRecordLayoutBuilder::LayoutNonVirtualBase(const CXXRecordDecl *base, |
| CharUnits baseOffset) { |
| // Ignore empty bases. |
| if (base->isEmpty()) return true; |
| |
| const CGRecordLayout &baseLayout = Types.getCGRecordLayout(base); |
| if (IsZeroInitializableAsBase) { |
| assert(IsZeroInitializable && |
| "class zero-initializable as base but not as complete object"); |
| |
| IsZeroInitializable = IsZeroInitializableAsBase = |
| baseLayout.isZeroInitializableAsBase(); |
| } |
| |
| if (!LayoutBase(base, baseLayout, baseOffset)) |
| return false; |
| NonVirtualBases[base] = (FieldTypes.size() - 1); |
| return true; |
| } |
| |
| bool |
| CGRecordLayoutBuilder::LayoutVirtualBase(const CXXRecordDecl *base, |
| CharUnits baseOffset) { |
| // Ignore empty bases. |
| if (base->isEmpty()) return true; |
| |
| const CGRecordLayout &baseLayout = Types.getCGRecordLayout(base); |
| if (IsZeroInitializable) |
| IsZeroInitializable = baseLayout.isZeroInitializableAsBase(); |
| |
| if (!LayoutBase(base, baseLayout, baseOffset)) |
| return false; |
| VirtualBases[base] = (FieldTypes.size() - 1); |
| return true; |
| } |
| |
| bool |
| CGRecordLayoutBuilder::MSLayoutVirtualBases(const CXXRecordDecl *RD, |
| const ASTRecordLayout &Layout) { |
| if (!RD->getNumVBases()) |
| return true; |
| |
| // The vbases list is uniqued and ordered by a depth-first |
| // traversal, which is what we need here. |
| for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(), |
| E = RD->vbases_end(); I != E; ++I) { |
| |
| const CXXRecordDecl *BaseDecl = |
| cast<CXXRecordDecl>(I->getType()->castAs<RecordType>()->getDecl()); |
| |
| CharUnits vbaseOffset = Layout.getVBaseClassOffset(BaseDecl); |
| if (!LayoutVirtualBase(BaseDecl, vbaseOffset)) |
| return false; |
| } |
| return true; |
| } |
| |
| /// LayoutVirtualBases - layout the non-virtual bases of a record decl. |
| bool |
| CGRecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD, |
| const ASTRecordLayout &Layout) { |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| const CXXRecordDecl *BaseDecl = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| // We only want to lay out virtual bases that aren't indirect primary bases |
| // of some other base. |
| if (I->isVirtual() && !IndirectPrimaryBases.count(BaseDecl)) { |
| // Only lay out the base once. |
| if (!LaidOutVirtualBases.insert(BaseDecl)) |
| continue; |
| |
| CharUnits vbaseOffset = Layout.getVBaseClassOffset(BaseDecl); |
| if (!LayoutVirtualBase(BaseDecl, vbaseOffset)) |
| return false; |
| } |
| |
| if (!BaseDecl->getNumVBases()) { |
| // This base isn't interesting since it doesn't have any virtual bases. |
| continue; |
| } |
| |
| if (!LayoutVirtualBases(BaseDecl, Layout)) |
| return false; |
| } |
| return true; |
| } |
| |
| bool |
| CGRecordLayoutBuilder::LayoutNonVirtualBases(const CXXRecordDecl *RD, |
| const ASTRecordLayout &Layout) { |
| const CXXRecordDecl *PrimaryBase = Layout.getPrimaryBase(); |
| |
| // If we have a primary base, lay it out first. |
| if (PrimaryBase) { |
| if (!Layout.isPrimaryBaseVirtual()) { |
| if (!LayoutNonVirtualBase(PrimaryBase, CharUnits::Zero())) |
| return false; |
| } else { |
| if (!LayoutVirtualBase(PrimaryBase, CharUnits::Zero())) |
| return false; |
| } |
| |
| // Otherwise, add a vtable / vf-table if the layout says to do so. |
| } else if (Layout.hasOwnVFPtr()) { |
| llvm::Type *FunctionType = |
| llvm::FunctionType::get(llvm::Type::getInt32Ty(Types.getLLVMContext()), |
| /*isVarArg=*/true); |
| llvm::Type *VTableTy = FunctionType->getPointerTo(); |
| |
| if (getTypeAlignment(VTableTy) > Alignment) { |
| // FIXME: Should we allow this to happen in Sema? |
| assert(!Packed && "Alignment is wrong even with packed struct!"); |
| return false; |
| } |
| |
| assert(NextFieldOffset.isZero() && |
| "VTable pointer must come first!"); |
| AppendField(CharUnits::Zero(), VTableTy->getPointerTo()); |
| } |
| |
| // Layout the non-virtual bases. |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| if (I->isVirtual()) |
| continue; |
| |
| const CXXRecordDecl *BaseDecl = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| // We've already laid out the primary base. |
| if (BaseDecl == PrimaryBase && !Layout.isPrimaryBaseVirtual()) |
| continue; |
| |
| if (!LayoutNonVirtualBase(BaseDecl, Layout.getBaseClassOffset(BaseDecl))) |
| return false; |
| } |
| |
| // Add a vb-table pointer if the layout insists. |
| if (Layout.getVBPtrOffset() != CharUnits::fromQuantity(-1)) { |
| CharUnits VBPtrOffset = Layout.getVBPtrOffset(); |
| llvm::Type *Vbptr = llvm::Type::getInt32PtrTy(Types.getLLVMContext()); |
| AppendPadding(VBPtrOffset, getTypeAlignment(Vbptr)); |
| AppendField(VBPtrOffset, Vbptr); |
| } |
| |
| return true; |
| } |
| |
| bool |
| CGRecordLayoutBuilder::ComputeNonVirtualBaseType(const CXXRecordDecl *RD) { |
| const ASTRecordLayout &Layout = Types.getContext().getASTRecordLayout(RD); |
| |
| CharUnits NonVirtualSize = Layout.getNonVirtualSize(); |
| CharUnits NonVirtualAlign = Layout.getNonVirtualAlign(); |
| CharUnits AlignedNonVirtualTypeSize = |
| NonVirtualSize.RoundUpToAlignment(NonVirtualAlign); |
| |
| // First check if we can use the same fields as for the complete class. |
| CharUnits RecordSize = Layout.getSize(); |
| if (AlignedNonVirtualTypeSize == RecordSize) |
| return true; |
| |
| // Check if we need padding. |
| CharUnits AlignedNextFieldOffset = |
| NextFieldOffset.RoundUpToAlignment(getAlignmentAsLLVMStruct()); |
| |
| if (AlignedNextFieldOffset > AlignedNonVirtualTypeSize) { |
| assert(!Packed && "cannot layout even as packed struct"); |
| return false; // Needs packing. |
| } |
| |
| bool needsPadding = (AlignedNonVirtualTypeSize != AlignedNextFieldOffset); |
| if (needsPadding) { |
| CharUnits NumBytes = AlignedNonVirtualTypeSize - AlignedNextFieldOffset; |
| FieldTypes.push_back(getByteArrayType(NumBytes)); |
| } |
| |
| BaseSubobjectType = llvm::StructType::create(Types.getLLVMContext(), |
| FieldTypes, "", Packed); |
| Types.addRecordTypeName(RD, BaseSubobjectType, ".base"); |
| |
| // Pull the padding back off. |
| if (needsPadding) |
| FieldTypes.pop_back(); |
| |
| return true; |
| } |
| |
| bool CGRecordLayoutBuilder::LayoutFields(const RecordDecl *D) { |
| assert(!D->isUnion() && "Can't call LayoutFields on a union!"); |
| assert(!Alignment.isZero() && "Did not set alignment!"); |
| |
| const ASTRecordLayout &Layout = Types.getContext().getASTRecordLayout(D); |
| |
| const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D); |
| if (RD) |
| if (!LayoutNonVirtualBases(RD, Layout)) |
| return false; |
| |
| unsigned FieldNo = 0; |
| const FieldDecl *LastFD = 0; |
| |
| for (RecordDecl::field_iterator Field = D->field_begin(), |
| FieldEnd = D->field_end(); Field != FieldEnd; ++Field, ++FieldNo) { |
| if (IsMsStruct) { |
| // Zero-length bitfields following non-bitfield members are |
| // ignored: |
| const FieldDecl *FD = *Field; |
| if (Types.getContext().ZeroBitfieldFollowsNonBitfield(FD, LastFD)) { |
| --FieldNo; |
| continue; |
| } |
| LastFD = FD; |
| } |
| |
| if (!LayoutField(*Field, Layout.getFieldOffset(FieldNo))) { |
| assert(!Packed && |
| "Could not layout fields even with a packed LLVM struct!"); |
| return false; |
| } |
| } |
| |
| if (RD) { |
| // We've laid out the non-virtual bases and the fields, now compute the |
| // non-virtual base field types. |
| if (!ComputeNonVirtualBaseType(RD)) { |
| assert(!Packed && "Could not layout even with a packed LLVM struct!"); |
| return false; |
| } |
| |
| // Lay out the virtual bases. The MS ABI uses a different |
| // algorithm here due to the lack of primary virtual bases. |
| if (Types.getContext().getTargetInfo().getCXXABI() != CXXABI_Microsoft) { |
| RD->getIndirectPrimaryBases(IndirectPrimaryBases); |
| if (Layout.isPrimaryBaseVirtual()) |
| IndirectPrimaryBases.insert(Layout.getPrimaryBase()); |
| |
| if (!LayoutVirtualBases(RD, Layout)) |
| return false; |
| } else { |
| if (!MSLayoutVirtualBases(RD, Layout)) |
| return false; |
| } |
| } |
| |
| // Append tail padding if necessary. |
| AppendTailPadding(Layout.getSize()); |
| |
| return true; |
| } |
| |
| void CGRecordLayoutBuilder::AppendTailPadding(CharUnits RecordSize) { |
| ResizeLastBaseFieldIfNecessary(RecordSize); |
| |
| assert(NextFieldOffset <= RecordSize && "Size mismatch!"); |
| |
| CharUnits AlignedNextFieldOffset = |
| NextFieldOffset.RoundUpToAlignment(getAlignmentAsLLVMStruct()); |
| |
| if (AlignedNextFieldOffset == RecordSize) { |
| // We don't need any padding. |
| return; |
| } |
| |
| CharUnits NumPadBytes = RecordSize - NextFieldOffset; |
| AppendBytes(NumPadBytes); |
| } |
| |
| void CGRecordLayoutBuilder::AppendField(CharUnits fieldOffset, |
| llvm::Type *fieldType) { |
| CharUnits fieldSize = |
| CharUnits::fromQuantity(Types.getTargetData().getTypeAllocSize(fieldType)); |
| |
| FieldTypes.push_back(fieldType); |
| |
| NextFieldOffset = fieldOffset + fieldSize; |
| BitsAvailableInLastField = 0; |
| } |
| |
| void CGRecordLayoutBuilder::AppendPadding(CharUnits fieldOffset, |
| CharUnits fieldAlignment) { |
| assert(NextFieldOffset <= fieldOffset && |
| "Incorrect field layout!"); |
| |
| // Do nothing if we're already at the right offset. |
| if (fieldOffset == NextFieldOffset) return; |
| |
| // If we're not emitting a packed LLVM type, try to avoid adding |
| // unnecessary padding fields. |
| if (!Packed) { |
| // Round up the field offset to the alignment of the field type. |
| CharUnits alignedNextFieldOffset = |
| NextFieldOffset.RoundUpToAlignment(fieldAlignment); |
| assert(alignedNextFieldOffset <= fieldOffset); |
| |
| // If that's the right offset, we're done. |
| if (alignedNextFieldOffset == fieldOffset) return; |
| } |
| |
| // Otherwise we need explicit padding. |
| CharUnits padding = fieldOffset - NextFieldOffset; |
| AppendBytes(padding); |
| } |
| |
| bool CGRecordLayoutBuilder::ResizeLastBaseFieldIfNecessary(CharUnits offset) { |
| // Check if we have a base to resize. |
| if (!LastLaidOutBase.isValid()) |
| return false; |
| |
| // This offset does not overlap with the tail padding. |
| if (offset >= NextFieldOffset) |
| return false; |
| |
| // Restore the field offset and append an i8 array instead. |
| FieldTypes.pop_back(); |
| NextFieldOffset = LastLaidOutBase.Offset; |
| AppendBytes(LastLaidOutBase.NonVirtualSize); |
| LastLaidOutBase.invalidate(); |
| |
| return true; |
| } |
| |
| llvm::Type *CGRecordLayoutBuilder::getByteArrayType(CharUnits numBytes) { |
| assert(!numBytes.isZero() && "Empty byte arrays aren't allowed."); |
| |
| llvm::Type *Ty = llvm::Type::getInt8Ty(Types.getLLVMContext()); |
| if (numBytes > CharUnits::One()) |
| Ty = llvm::ArrayType::get(Ty, numBytes.getQuantity()); |
| |
| return Ty; |
| } |
| |
| void CGRecordLayoutBuilder::AppendBytes(CharUnits numBytes) { |
| if (numBytes.isZero()) |
| return; |
| |
| // Append the padding field |
| AppendField(NextFieldOffset, getByteArrayType(numBytes)); |
| } |
| |
| CharUnits CGRecordLayoutBuilder::getTypeAlignment(llvm::Type *Ty) const { |
| if (Packed) |
| return CharUnits::One(); |
| |
| return CharUnits::fromQuantity(Types.getTargetData().getABITypeAlignment(Ty)); |
| } |
| |
| CharUnits CGRecordLayoutBuilder::getAlignmentAsLLVMStruct() const { |
| if (Packed) |
| return CharUnits::One(); |
| |
| CharUnits maxAlignment = CharUnits::One(); |
| for (size_t i = 0; i != FieldTypes.size(); ++i) |
| maxAlignment = std::max(maxAlignment, getTypeAlignment(FieldTypes[i])); |
| |
| return maxAlignment; |
| } |
| |
| /// Merge in whether a field of the given type is zero-initializable. |
| void CGRecordLayoutBuilder::CheckZeroInitializable(QualType T) { |
| // This record already contains a member pointer. |
| if (!IsZeroInitializableAsBase) |
| return; |
| |
| // Can only have member pointers if we're compiling C++. |
| if (!Types.getContext().getLangOpts().CPlusPlus) |
| return; |
| |
| const Type *elementType = T->getBaseElementTypeUnsafe(); |
| |
| if (const MemberPointerType *MPT = elementType->getAs<MemberPointerType>()) { |
| if (!Types.getCXXABI().isZeroInitializable(MPT)) |
| IsZeroInitializable = IsZeroInitializableAsBase = false; |
| } else if (const RecordType *RT = elementType->getAs<RecordType>()) { |
| const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); |
| const CGRecordLayout &Layout = Types.getCGRecordLayout(RD); |
| if (!Layout.isZeroInitializable()) |
| IsZeroInitializable = IsZeroInitializableAsBase = false; |
| } |
| } |
| |
| CGRecordLayout *CodeGenTypes::ComputeRecordLayout(const RecordDecl *D, |
| llvm::StructType *Ty) { |
| CGRecordLayoutBuilder Builder(*this); |
| |
| Builder.Layout(D); |
| |
| Ty->setBody(Builder.FieldTypes, Builder.Packed); |
| |
| // If we're in C++, compute the base subobject type. |
| llvm::StructType *BaseTy = 0; |
| if (isa<CXXRecordDecl>(D) && !D->isUnion()) { |
| BaseTy = Builder.BaseSubobjectType; |
| if (!BaseTy) BaseTy = Ty; |
| } |
| |
| CGRecordLayout *RL = |
| new CGRecordLayout(Ty, BaseTy, Builder.IsZeroInitializable, |
| Builder.IsZeroInitializableAsBase); |
| |
| RL->NonVirtualBases.swap(Builder.NonVirtualBases); |
| RL->CompleteObjectVirtualBases.swap(Builder.VirtualBases); |
| |
| // Add all the field numbers. |
| RL->FieldInfo.swap(Builder.Fields); |
| |
| // Add bitfield info. |
| RL->BitFields.swap(Builder.BitFields); |
| |
| // Dump the layout, if requested. |
| if (getContext().getLangOpts().DumpRecordLayouts) { |
| llvm::errs() << "\n*** Dumping IRgen Record Layout\n"; |
| llvm::errs() << "Record: "; |
| D->dump(); |
| llvm::errs() << "\nLayout: "; |
| RL->dump(); |
| } |
| |
| #ifndef NDEBUG |
| // Verify that the computed LLVM struct size matches the AST layout size. |
| const ASTRecordLayout &Layout = getContext().getASTRecordLayout(D); |
| |
| uint64_t TypeSizeInBits = getContext().toBits(Layout.getSize()); |
| assert(TypeSizeInBits == getTargetData().getTypeAllocSizeInBits(Ty) && |
| "Type size mismatch!"); |
| |
| if (BaseTy) { |
| CharUnits NonVirtualSize = Layout.getNonVirtualSize(); |
| CharUnits NonVirtualAlign = Layout.getNonVirtualAlign(); |
| CharUnits AlignedNonVirtualTypeSize = |
| NonVirtualSize.RoundUpToAlignment(NonVirtualAlign); |
| |
| uint64_t AlignedNonVirtualTypeSizeInBits = |
| getContext().toBits(AlignedNonVirtualTypeSize); |
| |
| assert(AlignedNonVirtualTypeSizeInBits == |
| getTargetData().getTypeAllocSizeInBits(BaseTy) && |
| "Type size mismatch!"); |
| } |
| |
| // Verify that the LLVM and AST field offsets agree. |
| llvm::StructType *ST = |
| dyn_cast<llvm::StructType>(RL->getLLVMType()); |
| const llvm::StructLayout *SL = getTargetData().getStructLayout(ST); |
| |
| const ASTRecordLayout &AST_RL = getContext().getASTRecordLayout(D); |
| RecordDecl::field_iterator it = D->field_begin(); |
| const FieldDecl *LastFD = 0; |
| bool IsMsStruct = D->hasAttr<MsStructAttr>(); |
| for (unsigned i = 0, e = AST_RL.getFieldCount(); i != e; ++i, ++it) { |
| const FieldDecl *FD = *it; |
| |
| // For non-bit-fields, just check that the LLVM struct offset matches the |
| // AST offset. |
| if (!FD->isBitField()) { |
| unsigned FieldNo = RL->getLLVMFieldNo(FD); |
| assert(AST_RL.getFieldOffset(i) == SL->getElementOffsetInBits(FieldNo) && |
| "Invalid field offset!"); |
| LastFD = FD; |
| continue; |
| } |
| |
| if (IsMsStruct) { |
| // Zero-length bitfields following non-bitfield members are |
| // ignored: |
| if (getContext().ZeroBitfieldFollowsNonBitfield(FD, LastFD)) { |
| --i; |
| continue; |
| } |
| LastFD = FD; |
| } |
| |
| // Ignore unnamed bit-fields. |
| if (!FD->getDeclName()) { |
| LastFD = FD; |
| continue; |
| } |
| |
| const CGBitFieldInfo &Info = RL->getBitFieldInfo(FD); |
| for (unsigned i = 0, e = Info.getNumComponents(); i != e; ++i) { |
| const CGBitFieldInfo::AccessInfo &AI = Info.getComponent(i); |
| |
| // Verify that every component access is within the structure. |
| uint64_t FieldOffset = SL->getElementOffsetInBits(AI.FieldIndex); |
| uint64_t AccessBitOffset = FieldOffset + |
| getContext().toBits(AI.FieldByteOffset); |
| assert(AccessBitOffset + AI.AccessWidth <= TypeSizeInBits && |
| "Invalid bit-field access (out of range)!"); |
| } |
| } |
| #endif |
| |
| return RL; |
| } |
| |
| void CGRecordLayout::print(raw_ostream &OS) const { |
| OS << "<CGRecordLayout\n"; |
| OS << " LLVMType:" << *CompleteObjectType << "\n"; |
| if (BaseSubobjectType) |
| OS << " NonVirtualBaseLLVMType:" << *BaseSubobjectType << "\n"; |
| OS << " IsZeroInitializable:" << IsZeroInitializable << "\n"; |
| OS << " BitFields:[\n"; |
| |
| // Print bit-field infos in declaration order. |
| std::vector<std::pair<unsigned, const CGBitFieldInfo*> > BFIs; |
| for (llvm::DenseMap<const FieldDecl*, CGBitFieldInfo>::const_iterator |
| it = BitFields.begin(), ie = BitFields.end(); |
| it != ie; ++it) { |
| const RecordDecl *RD = it->first->getParent(); |
| unsigned Index = 0; |
| for (RecordDecl::field_iterator |
| it2 = RD->field_begin(); *it2 != it->first; ++it2) |
| ++Index; |
| BFIs.push_back(std::make_pair(Index, &it->second)); |
| } |
| llvm::array_pod_sort(BFIs.begin(), BFIs.end()); |
| for (unsigned i = 0, e = BFIs.size(); i != e; ++i) { |
| OS.indent(4); |
| BFIs[i].second->print(OS); |
| OS << "\n"; |
| } |
| |
| OS << "]>\n"; |
| } |
| |
| void CGRecordLayout::dump() const { |
| print(llvm::errs()); |
| } |
| |
| void CGBitFieldInfo::print(raw_ostream &OS) const { |
| OS << "<CGBitFieldInfo"; |
| OS << " Size:" << Size; |
| OS << " IsSigned:" << IsSigned << "\n"; |
| |
| OS.indent(4 + strlen("<CGBitFieldInfo")); |
| OS << " NumComponents:" << getNumComponents(); |
| OS << " Components: ["; |
| if (getNumComponents()) { |
| OS << "\n"; |
| for (unsigned i = 0, e = getNumComponents(); i != e; ++i) { |
| const AccessInfo &AI = getComponent(i); |
| OS.indent(8); |
| OS << "<AccessInfo" |
| << " FieldIndex:" << AI.FieldIndex |
| << " FieldByteOffset:" << AI.FieldByteOffset.getQuantity() |
| << " FieldBitStart:" << AI.FieldBitStart |
| << " AccessWidth:" << AI.AccessWidth << "\n"; |
| OS.indent(8 + strlen("<AccessInfo")); |
| OS << " AccessAlignment:" << AI.AccessAlignment.getQuantity() |
| << " TargetBitOffset:" << AI.TargetBitOffset |
| << " TargetBitWidth:" << AI.TargetBitWidth |
| << ">\n"; |
| } |
| OS.indent(4); |
| } |
| OS << "]>"; |
| } |
| |
| void CGBitFieldInfo::dump() const { |
| print(llvm::errs()); |
| } |