| //=== RecordLayoutBuilder.cpp - Helper class for building record layouts ---==// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "clang/AST/Attr.h" |
| #include "clang/AST/Decl.h" |
| #include "clang/AST/DeclCXX.h" |
| #include "clang/AST/DeclObjC.h" |
| #include "clang/AST/Expr.h" |
| #include "clang/AST/RecordLayout.h" |
| #include "clang/Basic/TargetInfo.h" |
| #include "llvm/Support/Format.h" |
| #include "llvm/ADT/SmallSet.h" |
| #include "llvm/Support/MathExtras.h" |
| #include <map> |
| |
| using namespace clang; |
| |
| namespace { |
| |
| /// BaseSubobjectInfo - Represents a single base subobject in a complete class. |
| /// For a class hierarchy like |
| /// |
| /// class A { }; |
| /// class B : A { }; |
| /// class C : A, B { }; |
| /// |
| /// The BaseSubobjectInfo graph for C will have three BaseSubobjectInfo |
| /// instances, one for B and two for A. |
| /// |
| /// If a base is virtual, it will only have one BaseSubobjectInfo allocated. |
| struct BaseSubobjectInfo { |
| /// Class - The class for this base info. |
| const CXXRecordDecl *Class; |
| |
| /// IsVirtual - Whether the BaseInfo represents a virtual base or not. |
| bool IsVirtual; |
| |
| /// Bases - Information about the base subobjects. |
| llvm::SmallVector<BaseSubobjectInfo*, 4> Bases; |
| |
| /// PrimaryVirtualBaseInfo - Holds the base info for the primary virtual base |
| /// of this base info (if one exists). |
| BaseSubobjectInfo *PrimaryVirtualBaseInfo; |
| |
| // FIXME: Document. |
| const BaseSubobjectInfo *Derived; |
| }; |
| |
| /// EmptySubobjectMap - Keeps track of which empty subobjects exist at different |
| /// offsets while laying out a C++ class. |
| class EmptySubobjectMap { |
| ASTContext &Context; |
| |
| /// Class - The class whose empty entries we're keeping track of. |
| const CXXRecordDecl *Class; |
| |
| /// EmptyClassOffsets - A map from offsets to empty record decls. |
| typedef llvm::SmallVector<const CXXRecordDecl *, 1> ClassVectorTy; |
| typedef llvm::DenseMap<uint64_t, ClassVectorTy> EmptyClassOffsetsMapTy; |
| EmptyClassOffsetsMapTy EmptyClassOffsets; |
| |
| /// MaxEmptyClassOffset - The highest offset known to contain an empty |
| /// base subobject. |
| uint64_t MaxEmptyClassOffset; |
| |
| /// ComputeEmptySubobjectSizes - Compute the size of the largest base or |
| /// member subobject that is empty. |
| void ComputeEmptySubobjectSizes(); |
| |
| bool CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD, |
| uint64_t Offset) const; |
| |
| void AddSubobjectAtOffset(const CXXRecordDecl *RD, uint64_t Offset); |
| |
| bool CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info, |
| uint64_t Offset); |
| void UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info, |
| uint64_t Offset, bool PlacingEmptyBase); |
| |
| bool CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD, |
| const CXXRecordDecl *Class, |
| uint64_t Offset) const; |
| bool CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD, |
| uint64_t Offset) const; |
| |
| void UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD, |
| const CXXRecordDecl *Class, |
| uint64_t Offset); |
| void UpdateEmptyFieldSubobjects(const FieldDecl *FD, uint64_t Offset); |
| |
| /// AnyEmptySubobjectsBeyondOffset - Returns whether there are any empty |
| /// subobjects beyond the given offset. |
| bool AnyEmptySubobjectsBeyondOffset(uint64_t Offset) const { |
| return Offset <= MaxEmptyClassOffset; |
| } |
| |
| public: |
| /// This holds the size of the largest empty subobject (either a base |
| /// or a member). Will be zero if the record being built doesn't contain |
| /// any empty classes. |
| uint64_t SizeOfLargestEmptySubobject; |
| |
| EmptySubobjectMap(ASTContext &Context, const CXXRecordDecl *Class) |
| : Context(Context), Class(Class), MaxEmptyClassOffset(0), |
| SizeOfLargestEmptySubobject(0) { |
| ComputeEmptySubobjectSizes(); |
| } |
| |
| /// CanPlaceBaseAtOffset - Return whether the given base class can be placed |
| /// at the given offset. |
| /// Returns false if placing the record will result in two components |
| /// (direct or indirect) of the same type having the same offset. |
| bool CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info, |
| uint64_t Offset); |
| |
| /// CanPlaceFieldAtOffset - Return whether a field can be placed at the given |
| /// offset. |
| bool CanPlaceFieldAtOffset(const FieldDecl *FD, uint64_t Offset); |
| }; |
| |
| void EmptySubobjectMap::ComputeEmptySubobjectSizes() { |
| // Check the bases. |
| for (CXXRecordDecl::base_class_const_iterator I = Class->bases_begin(), |
| E = Class->bases_end(); I != E; ++I) { |
| const CXXRecordDecl *BaseDecl = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| uint64_t EmptySize = 0; |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(BaseDecl); |
| if (BaseDecl->isEmpty()) { |
| // If the class decl is empty, get its size. |
| EmptySize = Layout.getSize(); |
| } else { |
| // Otherwise, we get the largest empty subobject for the decl. |
| EmptySize = Layout.getSizeOfLargestEmptySubobject(); |
| } |
| |
| SizeOfLargestEmptySubobject = std::max(SizeOfLargestEmptySubobject, |
| EmptySize); |
| } |
| |
| // Check the fields. |
| for (CXXRecordDecl::field_iterator I = Class->field_begin(), |
| E = Class->field_end(); I != E; ++I) { |
| const FieldDecl *FD = *I; |
| |
| const RecordType *RT = |
| Context.getBaseElementType(FD->getType())->getAs<RecordType>(); |
| |
| // We only care about record types. |
| if (!RT) |
| continue; |
| |
| uint64_t EmptySize = 0; |
| const CXXRecordDecl *MemberDecl = cast<CXXRecordDecl>(RT->getDecl()); |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(MemberDecl); |
| if (MemberDecl->isEmpty()) { |
| // If the class decl is empty, get its size. |
| EmptySize = Layout.getSize(); |
| } else { |
| // Otherwise, we get the largest empty subobject for the decl. |
| EmptySize = Layout.getSizeOfLargestEmptySubobject(); |
| } |
| |
| SizeOfLargestEmptySubobject = std::max(SizeOfLargestEmptySubobject, |
| EmptySize); |
| } |
| } |
| |
| bool |
| EmptySubobjectMap::CanPlaceSubobjectAtOffset(const CXXRecordDecl *RD, |
| uint64_t Offset) const { |
| // We only need to check empty bases. |
| if (!RD->isEmpty()) |
| return true; |
| |
| EmptyClassOffsetsMapTy::const_iterator I = EmptyClassOffsets.find(Offset); |
| if (I == EmptyClassOffsets.end()) |
| return true; |
| |
| const ClassVectorTy& Classes = I->second; |
| if (std::find(Classes.begin(), Classes.end(), RD) == Classes.end()) |
| return true; |
| |
| // There is already an empty class of the same type at this offset. |
| return false; |
| } |
| |
| void EmptySubobjectMap::AddSubobjectAtOffset(const CXXRecordDecl *RD, |
| uint64_t Offset) { |
| // We only care about empty bases. |
| if (!RD->isEmpty()) |
| return; |
| |
| ClassVectorTy& Classes = EmptyClassOffsets[Offset]; |
| assert(std::find(Classes.begin(), Classes.end(), RD) == Classes.end() && |
| "Duplicate empty class detected!"); |
| |
| Classes.push_back(RD); |
| |
| // Update the empty class offset. |
| MaxEmptyClassOffset = std::max(MaxEmptyClassOffset, Offset); |
| } |
| |
| bool |
| EmptySubobjectMap::CanPlaceBaseSubobjectAtOffset(const BaseSubobjectInfo *Info, |
| uint64_t Offset) { |
| // We don't have to keep looking past the maximum offset that's known to |
| // contain an empty class. |
| if (!AnyEmptySubobjectsBeyondOffset(Offset)) |
| return true; |
| |
| if (!CanPlaceSubobjectAtOffset(Info->Class, Offset)) |
| return false; |
| |
| // Traverse all non-virtual bases. |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class); |
| for (unsigned I = 0, E = Info->Bases.size(); I != E; ++I) { |
| BaseSubobjectInfo* Base = Info->Bases[I]; |
| if (Base->IsVirtual) |
| continue; |
| |
| uint64_t BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class); |
| |
| if (!CanPlaceBaseSubobjectAtOffset(Base, BaseOffset)) |
| return false; |
| } |
| |
| if (Info->PrimaryVirtualBaseInfo) { |
| BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo; |
| |
| if (Info == PrimaryVirtualBaseInfo->Derived) { |
| if (!CanPlaceBaseSubobjectAtOffset(PrimaryVirtualBaseInfo, Offset)) |
| return false; |
| } |
| } |
| |
| // Traverse all member variables. |
| unsigned FieldNo = 0; |
| for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(), |
| E = Info->Class->field_end(); I != E; ++I, ++FieldNo) { |
| const FieldDecl *FD = *I; |
| |
| uint64_t FieldOffset = Offset + Layout.getFieldOffset(FieldNo); |
| if (!CanPlaceFieldSubobjectAtOffset(FD, FieldOffset)) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| void EmptySubobjectMap::UpdateEmptyBaseSubobjects(const BaseSubobjectInfo *Info, |
| uint64_t Offset, |
| bool PlacingEmptyBase) { |
| if (!PlacingEmptyBase && Offset >= SizeOfLargestEmptySubobject) { |
| // We know that the only empty subobjects that can conflict with empty |
| // subobject of non-empty bases, are empty bases that can be placed at |
| // offset zero. Because of this, we only need to keep track of empty base |
| // subobjects with offsets less than the size of the largest empty |
| // subobject for our class. |
| return; |
| } |
| |
| AddSubobjectAtOffset(Info->Class, Offset); |
| |
| // Traverse all non-virtual bases. |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class); |
| for (unsigned I = 0, E = Info->Bases.size(); I != E; ++I) { |
| BaseSubobjectInfo* Base = Info->Bases[I]; |
| if (Base->IsVirtual) |
| continue; |
| |
| uint64_t BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class); |
| UpdateEmptyBaseSubobjects(Base, BaseOffset, PlacingEmptyBase); |
| } |
| |
| if (Info->PrimaryVirtualBaseInfo) { |
| BaseSubobjectInfo *PrimaryVirtualBaseInfo = Info->PrimaryVirtualBaseInfo; |
| |
| if (Info == PrimaryVirtualBaseInfo->Derived) |
| UpdateEmptyBaseSubobjects(PrimaryVirtualBaseInfo, Offset, |
| PlacingEmptyBase); |
| } |
| |
| // Traverse all member variables. |
| unsigned FieldNo = 0; |
| for (CXXRecordDecl::field_iterator I = Info->Class->field_begin(), |
| E = Info->Class->field_end(); I != E; ++I, ++FieldNo) { |
| const FieldDecl *FD = *I; |
| |
| uint64_t FieldOffset = Offset + Layout.getFieldOffset(FieldNo); |
| UpdateEmptyFieldSubobjects(FD, FieldOffset); |
| } |
| } |
| |
| bool EmptySubobjectMap::CanPlaceBaseAtOffset(const BaseSubobjectInfo *Info, |
| uint64_t Offset) { |
| // If we know this class doesn't have any empty subobjects we don't need to |
| // bother checking. |
| if (!SizeOfLargestEmptySubobject) |
| return true; |
| |
| if (!CanPlaceBaseSubobjectAtOffset(Info, Offset)) |
| return false; |
| |
| // We are able to place the base at this offset. Make sure to update the |
| // empty base subobject map. |
| UpdateEmptyBaseSubobjects(Info, Offset, Info->Class->isEmpty()); |
| return true; |
| } |
| |
| bool |
| EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const CXXRecordDecl *RD, |
| const CXXRecordDecl *Class, |
| uint64_t Offset) const { |
| // We don't have to keep looking past the maximum offset that's known to |
| // contain an empty class. |
| if (!AnyEmptySubobjectsBeyondOffset(Offset)) |
| return true; |
| |
| if (!CanPlaceSubobjectAtOffset(RD, Offset)) |
| return false; |
| |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| |
| // Traverse all 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()); |
| |
| uint64_t BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl); |
| if (!CanPlaceFieldSubobjectAtOffset(BaseDecl, Class, BaseOffset)) |
| return false; |
| } |
| |
| if (RD == Class) { |
| // This is the most derived class, traverse virtual bases as well. |
| for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(), |
| E = RD->vbases_end(); I != E; ++I) { |
| const CXXRecordDecl *VBaseDecl = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| uint64_t VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl); |
| if (!CanPlaceFieldSubobjectAtOffset(VBaseDecl, Class, VBaseOffset)) |
| return false; |
| } |
| } |
| |
| // Traverse all member variables. |
| unsigned FieldNo = 0; |
| for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end(); |
| I != E; ++I, ++FieldNo) { |
| const FieldDecl *FD = *I; |
| |
| uint64_t FieldOffset = Offset + Layout.getFieldOffset(FieldNo); |
| |
| if (!CanPlaceFieldSubobjectAtOffset(FD, FieldOffset)) |
| return false; |
| } |
| |
| return true; |
| } |
| |
| bool EmptySubobjectMap::CanPlaceFieldSubobjectAtOffset(const FieldDecl *FD, |
| uint64_t Offset) const { |
| // We don't have to keep looking past the maximum offset that's known to |
| // contain an empty class. |
| if (!AnyEmptySubobjectsBeyondOffset(Offset)) |
| return true; |
| |
| QualType T = FD->getType(); |
| if (const RecordType *RT = T->getAs<RecordType>()) { |
| const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); |
| return CanPlaceFieldSubobjectAtOffset(RD, RD, Offset); |
| } |
| |
| // If we have an array type we need to look at every element. |
| if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) { |
| QualType ElemTy = Context.getBaseElementType(AT); |
| const RecordType *RT = ElemTy->getAs<RecordType>(); |
| if (!RT) |
| return true; |
| |
| const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| |
| uint64_t NumElements = Context.getConstantArrayElementCount(AT); |
| uint64_t ElementOffset = Offset; |
| for (uint64_t I = 0; I != NumElements; ++I) { |
| // We don't have to keep looking past the maximum offset that's known to |
| // contain an empty class. |
| if (!AnyEmptySubobjectsBeyondOffset(ElementOffset)) |
| return true; |
| |
| if (!CanPlaceFieldSubobjectAtOffset(RD, RD, ElementOffset)) |
| return false; |
| |
| ElementOffset += Layout.getSize(); |
| } |
| } |
| |
| return true; |
| } |
| |
| bool |
| EmptySubobjectMap::CanPlaceFieldAtOffset(const FieldDecl *FD, uint64_t Offset) { |
| if (!CanPlaceFieldSubobjectAtOffset(FD, Offset)) |
| return false; |
| |
| // We are able to place the member variable at this offset. |
| // Make sure to update the empty base subobject map. |
| UpdateEmptyFieldSubobjects(FD, Offset); |
| return true; |
| } |
| |
| void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const CXXRecordDecl *RD, |
| const CXXRecordDecl *Class, |
| uint64_t Offset) { |
| // We know that the only empty subobjects that can conflict with empty |
| // field subobjects are subobjects of empty bases that can be placed at offset |
| // zero. Because of this, we only need to keep track of empty field |
| // subobjects with offsets less than the size of the largest empty |
| // subobject for our class. |
| if (Offset >= SizeOfLargestEmptySubobject) |
| return; |
| |
| AddSubobjectAtOffset(RD, Offset); |
| |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| |
| // Traverse all 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()); |
| |
| uint64_t BaseOffset = Offset + Layout.getBaseClassOffset(BaseDecl); |
| UpdateEmptyFieldSubobjects(BaseDecl, Class, BaseOffset); |
| } |
| |
| if (RD == Class) { |
| // This is the most derived class, traverse virtual bases as well. |
| for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(), |
| E = RD->vbases_end(); I != E; ++I) { |
| const CXXRecordDecl *VBaseDecl = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| uint64_t VBaseOffset = Offset + Layout.getVBaseClassOffset(VBaseDecl); |
| UpdateEmptyFieldSubobjects(VBaseDecl, Class, VBaseOffset); |
| } |
| } |
| |
| // Traverse all member variables. |
| unsigned FieldNo = 0; |
| for (CXXRecordDecl::field_iterator I = RD->field_begin(), E = RD->field_end(); |
| I != E; ++I, ++FieldNo) { |
| const FieldDecl *FD = *I; |
| |
| uint64_t FieldOffset = Offset + Layout.getFieldOffset(FieldNo); |
| |
| UpdateEmptyFieldSubobjects(FD, FieldOffset); |
| } |
| } |
| |
| void EmptySubobjectMap::UpdateEmptyFieldSubobjects(const FieldDecl *FD, |
| uint64_t Offset) { |
| QualType T = FD->getType(); |
| if (const RecordType *RT = T->getAs<RecordType>()) { |
| const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); |
| UpdateEmptyFieldSubobjects(RD, RD, Offset); |
| return; |
| } |
| |
| // If we have an array type we need to update every element. |
| if (const ConstantArrayType *AT = Context.getAsConstantArrayType(T)) { |
| QualType ElemTy = Context.getBaseElementType(AT); |
| const RecordType *RT = ElemTy->getAs<RecordType>(); |
| if (!RT) |
| return; |
| |
| const CXXRecordDecl *RD = cast<CXXRecordDecl>(RT->getDecl()); |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| |
| uint64_t NumElements = Context.getConstantArrayElementCount(AT); |
| uint64_t ElementOffset = Offset; |
| |
| for (uint64_t I = 0; I != NumElements; ++I) { |
| // We know that the only empty subobjects that can conflict with empty |
| // field subobjects are subobjects of empty bases that can be placed at |
| // offset zero. Because of this, we only need to keep track of empty field |
| // subobjects with offsets less than the size of the largest empty |
| // subobject for our class. |
| if (ElementOffset >= SizeOfLargestEmptySubobject) |
| return; |
| |
| UpdateEmptyFieldSubobjects(RD, RD, ElementOffset); |
| ElementOffset += Layout.getSize(); |
| } |
| } |
| } |
| |
| class RecordLayoutBuilder { |
| // FIXME: Remove this and make the appropriate fields public. |
| friend class clang::ASTContext; |
| |
| ASTContext &Context; |
| |
| EmptySubobjectMap *EmptySubobjects; |
| |
| /// Size - The current size of the record layout. |
| uint64_t Size; |
| |
| /// Alignment - The current alignment of the record layout. |
| unsigned Alignment; |
| |
| llvm::SmallVector<uint64_t, 16> FieldOffsets; |
| |
| /// Packed - Whether the record is packed or not. |
| unsigned Packed : 1; |
| |
| unsigned IsUnion : 1; |
| |
| unsigned IsMac68kAlign : 1; |
| |
| /// UnfilledBitsInLastByte - If the last field laid out was a bitfield, |
| /// this contains the number of bits in the last byte that can be used for |
| /// an adjacent bitfield if necessary. |
| unsigned char UnfilledBitsInLastByte; |
| |
| /// MaxFieldAlignment - The maximum allowed field alignment. This is set by |
| /// #pragma pack. |
| unsigned MaxFieldAlignment; |
| |
| /// DataSize - The data size of the record being laid out. |
| uint64_t DataSize; |
| |
| uint64_t NonVirtualSize; |
| unsigned NonVirtualAlignment; |
| |
| /// PrimaryBase - the primary base class (if one exists) of the class |
| /// we're laying out. |
| const CXXRecordDecl *PrimaryBase; |
| |
| /// PrimaryBaseIsVirtual - Whether the primary base of the class we're laying |
| /// out is virtual. |
| bool PrimaryBaseIsVirtual; |
| |
| typedef llvm::DenseMap<const CXXRecordDecl *, uint64_t> BaseOffsetsMapTy; |
| |
| /// Bases - base classes and their offsets in the record. |
| BaseOffsetsMapTy Bases; |
| |
| // VBases - virtual base classes and their offsets in the record. |
| BaseOffsetsMapTy VBases; |
| |
| /// IndirectPrimaryBases - Virtual base classes, direct or indirect, that are |
| /// primary base classes for some other direct or indirect base class. |
| llvm::SmallSet<const CXXRecordDecl*, 32> IndirectPrimaryBases; |
| |
| /// FirstNearlyEmptyVBase - The first nearly empty virtual base class in |
| /// inheritance graph order. Used for determining the primary base class. |
| const CXXRecordDecl *FirstNearlyEmptyVBase; |
| |
| /// VisitedVirtualBases - A set of all the visited virtual bases, used to |
| /// avoid visiting virtual bases more than once. |
| llvm::SmallPtrSet<const CXXRecordDecl *, 4> VisitedVirtualBases; |
| |
| RecordLayoutBuilder(ASTContext &Context, EmptySubobjectMap *EmptySubobjects) |
| : Context(Context), EmptySubobjects(EmptySubobjects), Size(0), Alignment(8), |
| Packed(false), IsUnion(false), IsMac68kAlign(false), |
| UnfilledBitsInLastByte(0), MaxFieldAlignment(0), DataSize(0), |
| NonVirtualSize(0), NonVirtualAlignment(8), PrimaryBase(0), |
| PrimaryBaseIsVirtual(false), FirstNearlyEmptyVBase(0) { } |
| |
| void Layout(const RecordDecl *D); |
| void Layout(const CXXRecordDecl *D); |
| void Layout(const ObjCInterfaceDecl *D); |
| |
| void LayoutFields(const RecordDecl *D); |
| void LayoutField(const FieldDecl *D); |
| void LayoutWideBitField(uint64_t FieldSize, uint64_t TypeSize); |
| void LayoutBitField(const FieldDecl *D); |
| |
| /// BaseSubobjectInfoAllocator - Allocator for BaseSubobjectInfo objects. |
| llvm::SpecificBumpPtrAllocator<BaseSubobjectInfo> BaseSubobjectInfoAllocator; |
| |
| typedef llvm::DenseMap<const CXXRecordDecl *, BaseSubobjectInfo *> |
| BaseSubobjectInfoMapTy; |
| |
| /// VirtualBaseInfo - Map from all the (direct or indirect) virtual bases |
| /// of the class we're laying out to their base subobject info. |
| BaseSubobjectInfoMapTy VirtualBaseInfo; |
| |
| /// NonVirtualBaseInfo - Map from all the direct non-virtual bases of the |
| /// class we're laying out to their base subobject info. |
| BaseSubobjectInfoMapTy NonVirtualBaseInfo; |
| |
| /// ComputeBaseSubobjectInfo - Compute the base subobject information for the |
| /// bases of the given class. |
| void ComputeBaseSubobjectInfo(const CXXRecordDecl *RD); |
| |
| /// ComputeBaseSubobjectInfo - Compute the base subobject information for a |
| /// single class and all of its base classes. |
| BaseSubobjectInfo *ComputeBaseSubobjectInfo(const CXXRecordDecl *RD, |
| bool IsVirtual, |
| BaseSubobjectInfo *Derived); |
| |
| /// DeterminePrimaryBase - Determine the primary base of the given class. |
| void DeterminePrimaryBase(const CXXRecordDecl *RD); |
| |
| void SelectPrimaryVBase(const CXXRecordDecl *RD); |
| |
| /// IdentifyPrimaryBases - Identify all virtual base classes, direct or |
| /// indirect, that are primary base classes for some other direct or indirect |
| /// base class. |
| void IdentifyPrimaryBases(const CXXRecordDecl *RD); |
| |
| bool IsNearlyEmpty(const CXXRecordDecl *RD) const; |
| |
| /// LayoutNonVirtualBases - Determines the primary base class (if any) and |
| /// lays it out. Will then proceed to lay out all non-virtual base clasess. |
| void LayoutNonVirtualBases(const CXXRecordDecl *RD); |
| |
| /// LayoutNonVirtualBase - Lays out a single non-virtual base. |
| void LayoutNonVirtualBase(const BaseSubobjectInfo *Base); |
| |
| void AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info, |
| uint64_t Offset); |
| |
| /// LayoutVirtualBases - Lays out all the virtual bases. |
| void LayoutVirtualBases(const CXXRecordDecl *RD, |
| const CXXRecordDecl *MostDerivedClass); |
| |
| /// LayoutVirtualBase - Lays out a single virtual base. |
| void LayoutVirtualBase(const BaseSubobjectInfo *Base); |
| |
| /// LayoutBase - Will lay out a base and return the offset where it was |
| /// placed, in bits. |
| uint64_t LayoutBase(const BaseSubobjectInfo *Base); |
| |
| /// InitializeLayout - Initialize record layout for the given record decl. |
| void InitializeLayout(const Decl *D); |
| |
| /// FinishLayout - Finalize record layout. Adjust record size based on the |
| /// alignment. |
| void FinishLayout(); |
| |
| void UpdateAlignment(unsigned NewAlignment); |
| |
| RecordLayoutBuilder(const RecordLayoutBuilder&); // DO NOT IMPLEMENT |
| void operator=(const RecordLayoutBuilder&); // DO NOT IMPLEMENT |
| public: |
| static const CXXMethodDecl *ComputeKeyFunction(const CXXRecordDecl *RD); |
| }; |
| } // end anonymous namespace |
| |
| /// IsNearlyEmpty - Indicates when a class has a vtable pointer, but |
| /// no other data. |
| bool RecordLayoutBuilder::IsNearlyEmpty(const CXXRecordDecl *RD) const { |
| // FIXME: Audit the corners |
| if (!RD->isDynamicClass()) |
| return false; |
| const ASTRecordLayout &BaseInfo = Context.getASTRecordLayout(RD); |
| if (BaseInfo.getNonVirtualSize() == Context.Target.getPointerWidth(0)) |
| return true; |
| return false; |
| } |
| |
| void RecordLayoutBuilder::IdentifyPrimaryBases(const CXXRecordDecl *RD) { |
| const ASTRecordLayout::PrimaryBaseInfo &BaseInfo = |
| Context.getASTRecordLayout(RD).getPrimaryBaseInfo(); |
| |
| // If the record has a primary base class that is virtual, add it to the set |
| // of primary bases. |
| if (BaseInfo.isVirtual()) |
| IndirectPrimaryBases.insert(BaseInfo.getBase()); |
| |
| // Now traverse all bases and find primary bases for them. |
| for (CXXRecordDecl::base_class_const_iterator i = RD->bases_begin(), |
| e = RD->bases_end(); i != e; ++i) { |
| assert(!i->getType()->isDependentType() && |
| "Cannot layout class with dependent bases."); |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl()); |
| |
| // Only bases with virtual bases participate in computing the |
| // indirect primary virtual base classes. |
| if (Base->getNumVBases()) |
| IdentifyPrimaryBases(Base); |
| } |
| } |
| |
| void |
| RecordLayoutBuilder::SelectPrimaryVBase(const CXXRecordDecl *RD) { |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| assert(!I->getType()->isDependentType() && |
| "Cannot layout class with dependent bases."); |
| |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| // Check if this is a nearly empty virtual base. |
| if (I->isVirtual() && IsNearlyEmpty(Base)) { |
| // If it's not an indirect primary base, then we've found our primary |
| // base. |
| if (!IndirectPrimaryBases.count(Base)) { |
| PrimaryBase = Base; |
| PrimaryBaseIsVirtual = true; |
| return; |
| } |
| |
| // Is this the first nearly empty virtual base? |
| if (!FirstNearlyEmptyVBase) |
| FirstNearlyEmptyVBase = Base; |
| } |
| |
| SelectPrimaryVBase(Base); |
| if (PrimaryBase) |
| return; |
| } |
| } |
| |
| /// DeterminePrimaryBase - Determine the primary base of the given class. |
| void RecordLayoutBuilder::DeterminePrimaryBase(const CXXRecordDecl *RD) { |
| // If the class isn't dynamic, it won't have a primary base. |
| if (!RD->isDynamicClass()) |
| return; |
| |
| // Compute all the primary virtual bases for all of our direct and |
| // indirect bases, and record all their primary virtual base classes. |
| for (CXXRecordDecl::base_class_const_iterator i = RD->bases_begin(), |
| e = RD->bases_end(); i != e; ++i) { |
| assert(!i->getType()->isDependentType() && |
| "Cannot lay out class with dependent bases."); |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl()); |
| IdentifyPrimaryBases(Base); |
| } |
| |
| // If the record has a dynamic base class, attempt to choose a primary base |
| // class. It is the first (in direct base class order) non-virtual dynamic |
| // base class, if one exists. |
| for (CXXRecordDecl::base_class_const_iterator i = RD->bases_begin(), |
| e = RD->bases_end(); i != e; ++i) { |
| // Ignore virtual bases. |
| if (i->isVirtual()) |
| continue; |
| |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(i->getType()->getAs<RecordType>()->getDecl()); |
| |
| if (Base->isDynamicClass()) { |
| // We found it. |
| PrimaryBase = Base; |
| PrimaryBaseIsVirtual = false; |
| return; |
| } |
| } |
| |
| // Otherwise, it is the first nearly empty virtual base that is not an |
| // indirect primary virtual base class, if one exists. |
| if (RD->getNumVBases() != 0) { |
| SelectPrimaryVBase(RD); |
| if (PrimaryBase) |
| return; |
| } |
| |
| // Otherwise, it is the first nearly empty virtual base that is not an |
| // indirect primary virtual base class, if one exists. |
| if (FirstNearlyEmptyVBase) { |
| PrimaryBase = FirstNearlyEmptyVBase; |
| PrimaryBaseIsVirtual = true; |
| return; |
| } |
| |
| // Otherwise there is no primary base class. |
| assert(!PrimaryBase && "Should not get here with a primary base!"); |
| |
| // Allocate the virtual table pointer at offset zero. |
| assert(DataSize == 0 && "Vtable pointer must be at offset zero!"); |
| |
| // Update the size. |
| Size += Context.Target.getPointerWidth(0); |
| DataSize = Size; |
| |
| // Update the alignment. |
| UpdateAlignment(Context.Target.getPointerAlign(0)); |
| } |
| |
| BaseSubobjectInfo * |
| RecordLayoutBuilder::ComputeBaseSubobjectInfo(const CXXRecordDecl *RD, |
| bool IsVirtual, |
| BaseSubobjectInfo *Derived) { |
| BaseSubobjectInfo *Info; |
| |
| if (IsVirtual) { |
| // Check if we already have info about this virtual base. |
| BaseSubobjectInfo *&InfoSlot = VirtualBaseInfo[RD]; |
| if (InfoSlot) { |
| assert(InfoSlot->Class == RD && "Wrong class for virtual base info!"); |
| return InfoSlot; |
| } |
| |
| // We don't, create it. |
| InfoSlot = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo; |
| Info = InfoSlot; |
| } else { |
| Info = new (BaseSubobjectInfoAllocator.Allocate()) BaseSubobjectInfo; |
| } |
| |
| Info->Class = RD; |
| Info->IsVirtual = IsVirtual; |
| Info->Derived = 0; |
| Info->PrimaryVirtualBaseInfo = 0; |
| |
| const CXXRecordDecl *PrimaryVirtualBase = 0; |
| BaseSubobjectInfo *PrimaryVirtualBaseInfo = 0; |
| |
| // Check if this base has a primary virtual base. |
| if (RD->getNumVBases()) { |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| if (Layout.getPrimaryBaseWasVirtual()) { |
| // This base does have a primary virtual base. |
| PrimaryVirtualBase = Layout.getPrimaryBase(); |
| assert(PrimaryVirtualBase && "Didn't have a primary virtual base!"); |
| |
| // Now check if we have base subobject info about this primary base. |
| PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase); |
| |
| if (PrimaryVirtualBaseInfo) { |
| if (PrimaryVirtualBaseInfo->Derived) { |
| // We did have info about this primary base, and it turns out that it |
| // has already been claimed as a primary virtual base for another |
| // base. |
| PrimaryVirtualBase = 0; |
| } else { |
| // We can claim this base as our primary base. |
| Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo; |
| PrimaryVirtualBaseInfo->Derived = Info; |
| } |
| } |
| } |
| } |
| |
| // Now go through all direct bases. |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| bool IsVirtual = I->isVirtual(); |
| |
| const CXXRecordDecl *BaseDecl = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| Info->Bases.push_back(ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, Info)); |
| } |
| |
| if (PrimaryVirtualBase && !PrimaryVirtualBaseInfo) { |
| // Traversing the bases must have created the base info for our primary |
| // virtual base. |
| PrimaryVirtualBaseInfo = VirtualBaseInfo.lookup(PrimaryVirtualBase); |
| assert(PrimaryVirtualBaseInfo && |
| "Did not create a primary virtual base!"); |
| |
| // Claim the primary virtual base as our primary virtual base. |
| Info->PrimaryVirtualBaseInfo = PrimaryVirtualBaseInfo; |
| PrimaryVirtualBaseInfo->Derived = Info; |
| } |
| |
| return Info; |
| } |
| |
| void RecordLayoutBuilder::ComputeBaseSubobjectInfo(const CXXRecordDecl *RD) { |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| bool IsVirtual = I->isVirtual(); |
| |
| const CXXRecordDecl *BaseDecl = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| // Compute the base subobject info for this base. |
| BaseSubobjectInfo *Info = ComputeBaseSubobjectInfo(BaseDecl, IsVirtual, 0); |
| |
| if (IsVirtual) { |
| // ComputeBaseInfo has already added this base for us. |
| assert(VirtualBaseInfo.count(BaseDecl) && |
| "Did not add virtual base!"); |
| } else { |
| // Add the base info to the map of non-virtual bases. |
| assert(!NonVirtualBaseInfo.count(BaseDecl) && |
| "Non-virtual base already exists!"); |
| NonVirtualBaseInfo.insert(std::make_pair(BaseDecl, Info)); |
| } |
| } |
| } |
| |
| void |
| RecordLayoutBuilder::LayoutNonVirtualBases(const CXXRecordDecl *RD) { |
| // Then, determine the primary base class. |
| DeterminePrimaryBase(RD); |
| |
| // Compute base subobject info. |
| ComputeBaseSubobjectInfo(RD); |
| |
| // If we have a primary base class, lay it out. |
| if (PrimaryBase) { |
| if (PrimaryBaseIsVirtual) { |
| // If the primary virtual base was a primary virtual base of some other |
| // base class we'll have to steal it. |
| BaseSubobjectInfo *PrimaryBaseInfo = VirtualBaseInfo.lookup(PrimaryBase); |
| PrimaryBaseInfo->Derived = 0; |
| |
| // We have a virtual primary base, insert it as an indirect primary base. |
| IndirectPrimaryBases.insert(PrimaryBase); |
| |
| assert(!VisitedVirtualBases.count(PrimaryBase) && |
| "vbase already visited!"); |
| VisitedVirtualBases.insert(PrimaryBase); |
| |
| LayoutVirtualBase(PrimaryBaseInfo); |
| } else { |
| BaseSubobjectInfo *PrimaryBaseInfo = |
| NonVirtualBaseInfo.lookup(PrimaryBase); |
| assert(PrimaryBaseInfo && |
| "Did not find base info for non-virtual primary base!"); |
| |
| LayoutNonVirtualBase(PrimaryBaseInfo); |
| } |
| } |
| |
| // Now lay out the non-virtual bases. |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| |
| // Ignore virtual bases. |
| if (I->isVirtual()) |
| continue; |
| |
| const CXXRecordDecl *BaseDecl = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| // Skip the primary base. |
| if (BaseDecl == PrimaryBase && !PrimaryBaseIsVirtual) |
| continue; |
| |
| // Lay out the base. |
| BaseSubobjectInfo *BaseInfo = NonVirtualBaseInfo.lookup(BaseDecl); |
| assert(BaseInfo && "Did not find base info for non-virtual base!"); |
| |
| LayoutNonVirtualBase(BaseInfo); |
| } |
| } |
| |
| void RecordLayoutBuilder::LayoutNonVirtualBase(const BaseSubobjectInfo *Base) { |
| // Layout the base. |
| uint64_t Offset = LayoutBase(Base); |
| |
| // Add its base class offset. |
| assert(!Bases.count(Base->Class) && "base offset already exists!"); |
| Bases.insert(std::make_pair(Base->Class, Offset)); |
| |
| AddPrimaryVirtualBaseOffsets(Base, Offset); |
| } |
| |
| void |
| RecordLayoutBuilder::AddPrimaryVirtualBaseOffsets(const BaseSubobjectInfo *Info, |
| uint64_t Offset) { |
| // This base isn't interesting, it has no virtual bases. |
| if (!Info->Class->getNumVBases()) |
| return; |
| |
| // First, check if we have a virtual primary base to add offsets for. |
| if (Info->PrimaryVirtualBaseInfo) { |
| assert(Info->PrimaryVirtualBaseInfo->IsVirtual && |
| "Primary virtual base is not virtual!"); |
| if (Info->PrimaryVirtualBaseInfo->Derived == Info) { |
| // Add the offset. |
| assert(!VBases.count(Info->PrimaryVirtualBaseInfo->Class) && |
| "primary vbase offset already exists!"); |
| VBases.insert(std::make_pair(Info->PrimaryVirtualBaseInfo->Class, |
| Offset)); |
| |
| // Traverse the primary virtual base. |
| AddPrimaryVirtualBaseOffsets(Info->PrimaryVirtualBaseInfo, Offset); |
| } |
| } |
| |
| // Now go through all direct non-virtual bases. |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(Info->Class); |
| for (unsigned I = 0, E = Info->Bases.size(); I != E; ++I) { |
| const BaseSubobjectInfo *Base = Info->Bases[I]; |
| if (Base->IsVirtual) |
| continue; |
| |
| uint64_t BaseOffset = Offset + Layout.getBaseClassOffset(Base->Class); |
| AddPrimaryVirtualBaseOffsets(Base, BaseOffset); |
| } |
| } |
| |
| void |
| RecordLayoutBuilder::LayoutVirtualBases(const CXXRecordDecl *RD, |
| const CXXRecordDecl *MostDerivedClass) { |
| const CXXRecordDecl *PrimaryBase; |
| bool PrimaryBaseIsVirtual; |
| |
| if (MostDerivedClass == RD) { |
| PrimaryBase = this->PrimaryBase; |
| PrimaryBaseIsVirtual = this->PrimaryBaseIsVirtual; |
| } else { |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(RD); |
| PrimaryBase = Layout.getPrimaryBase(); |
| PrimaryBaseIsVirtual = Layout.getPrimaryBaseWasVirtual(); |
| } |
| |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| assert(!I->getType()->isDependentType() && |
| "Cannot layout class with dependent bases."); |
| |
| const CXXRecordDecl *BaseDecl = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| if (I->isVirtual()) { |
| if (PrimaryBase != BaseDecl || !PrimaryBaseIsVirtual) { |
| bool IndirectPrimaryBase = IndirectPrimaryBases.count(BaseDecl); |
| |
| // Only lay out the virtual base if it's not an indirect primary base. |
| if (!IndirectPrimaryBase) { |
| // Only visit virtual bases once. |
| if (!VisitedVirtualBases.insert(BaseDecl)) |
| continue; |
| |
| const BaseSubobjectInfo *BaseInfo = VirtualBaseInfo.lookup(BaseDecl); |
| assert(BaseInfo && "Did not find virtual base info!"); |
| LayoutVirtualBase(BaseInfo); |
| } |
| } |
| } |
| |
| if (!BaseDecl->getNumVBases()) { |
| // This base isn't interesting since it doesn't have any virtual bases. |
| continue; |
| } |
| |
| LayoutVirtualBases(BaseDecl, MostDerivedClass); |
| } |
| } |
| |
| void RecordLayoutBuilder::LayoutVirtualBase(const BaseSubobjectInfo *Base) { |
| assert(!Base->Derived && "Trying to lay out a primary virtual base!"); |
| |
| // Layout the base. |
| uint64_t Offset = LayoutBase(Base); |
| |
| // Add its base class offset. |
| assert(!VBases.count(Base->Class) && "vbase offset already exists!"); |
| VBases.insert(std::make_pair(Base->Class, Offset)); |
| |
| AddPrimaryVirtualBaseOffsets(Base, Offset); |
| } |
| |
| uint64_t RecordLayoutBuilder::LayoutBase(const BaseSubobjectInfo *Base) { |
| const ASTRecordLayout &Layout = Context.getASTRecordLayout(Base->Class); |
| |
| // If we have an empty base class, try to place it at offset 0. |
| if (Base->Class->isEmpty() && |
| EmptySubobjects->CanPlaceBaseAtOffset(Base, 0)) { |
| Size = std::max(Size, Layout.getSize()); |
| |
| return 0; |
| } |
| |
| unsigned BaseAlign = Layout.getNonVirtualAlign(); |
| |
| // Round up the current record size to the base's alignment boundary. |
| uint64_t Offset = llvm::RoundUpToAlignment(DataSize, BaseAlign); |
| |
| // Try to place the base. |
| while (!EmptySubobjects->CanPlaceBaseAtOffset(Base, Offset)) |
| Offset += BaseAlign; |
| |
| if (!Base->Class->isEmpty()) { |
| // Update the data size. |
| DataSize = Offset + Layout.getNonVirtualSize(); |
| |
| Size = std::max(Size, DataSize); |
| } else |
| Size = std::max(Size, Offset + Layout.getSize()); |
| |
| // Remember max struct/class alignment. |
| UpdateAlignment(BaseAlign); |
| |
| return Offset; |
| } |
| |
| void RecordLayoutBuilder::InitializeLayout(const Decl *D) { |
| if (const RecordDecl *RD = dyn_cast<RecordDecl>(D)) |
| IsUnion = RD->isUnion(); |
| |
| Packed = D->hasAttr<PackedAttr>(); |
| |
| // mac68k alignment supersedes maximum field alignment and attribute aligned, |
| // and forces all structures to have 2-byte alignment. The IBM docs on it |
| // allude to additional (more complicated) semantics, especially with regard |
| // to bit-fields, but gcc appears not to follow that. |
| if (D->hasAttr<AlignMac68kAttr>()) { |
| IsMac68kAlign = true; |
| MaxFieldAlignment = 2 * 8; |
| Alignment = 2 * 8; |
| } else { |
| if (const MaxFieldAlignmentAttr *MFAA = D->getAttr<MaxFieldAlignmentAttr>()) |
| MaxFieldAlignment = MFAA->getAlignment(); |
| |
| if (const AlignedAttr *AA = D->getAttr<AlignedAttr>()) |
| UpdateAlignment(AA->getMaxAlignment()); |
| } |
| } |
| |
| void RecordLayoutBuilder::Layout(const RecordDecl *D) { |
| InitializeLayout(D); |
| LayoutFields(D); |
| |
| // Finally, round the size of the total struct up to the alignment of the |
| // struct itself. |
| FinishLayout(); |
| } |
| |
| void RecordLayoutBuilder::Layout(const CXXRecordDecl *RD) { |
| InitializeLayout(RD); |
| |
| // Lay out the vtable and the non-virtual bases. |
| LayoutNonVirtualBases(RD); |
| |
| LayoutFields(RD); |
| |
| NonVirtualSize = Size; |
| NonVirtualAlignment = Alignment; |
| |
| // Lay out the virtual bases and add the primary virtual base offsets. |
| LayoutVirtualBases(RD, RD); |
| |
| VisitedVirtualBases.clear(); |
| |
| // Finally, round the size of the total struct up to the alignment of the |
| // struct itself. |
| FinishLayout(); |
| |
| #ifndef NDEBUG |
| // Check that we have base offsets for all 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()); |
| |
| assert(Bases.count(BaseDecl) && "Did not find base offset!"); |
| } |
| |
| // And all virtual bases. |
| for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(), |
| E = RD->vbases_end(); I != E; ++I) { |
| const CXXRecordDecl *BaseDecl = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| assert(VBases.count(BaseDecl) && "Did not find base offset!"); |
| } |
| #endif |
| } |
| |
| void RecordLayoutBuilder::Layout(const ObjCInterfaceDecl *D) { |
| if (ObjCInterfaceDecl *SD = D->getSuperClass()) { |
| const ASTRecordLayout &SL = Context.getASTObjCInterfaceLayout(SD); |
| |
| UpdateAlignment(SL.getAlignment()); |
| |
| // We start laying out ivars not at the end of the superclass |
| // structure, but at the next byte following the last field. |
| Size = llvm::RoundUpToAlignment(SL.getDataSize(), 8); |
| DataSize = Size; |
| } |
| |
| InitializeLayout(D); |
| |
| // Layout each ivar sequentially. |
| llvm::SmallVector<ObjCIvarDecl*, 16> Ivars; |
| Context.ShallowCollectObjCIvars(D, Ivars); |
| for (unsigned i = 0, e = Ivars.size(); i != e; ++i) |
| LayoutField(Ivars[i]); |
| |
| // Finally, round the size of the total struct up to the alignment of the |
| // struct itself. |
| FinishLayout(); |
| } |
| |
| void RecordLayoutBuilder::LayoutFields(const RecordDecl *D) { |
| // Layout each field, for now, just sequentially, respecting alignment. In |
| // the future, this will need to be tweakable by targets. |
| for (RecordDecl::field_iterator Field = D->field_begin(), |
| FieldEnd = D->field_end(); Field != FieldEnd; ++Field) |
| LayoutField(*Field); |
| } |
| |
| void RecordLayoutBuilder::LayoutWideBitField(uint64_t FieldSize, |
| uint64_t TypeSize) { |
| assert(Context.getLangOptions().CPlusPlus && |
| "Can only have wide bit-fields in C++!"); |
| |
| // Itanium C++ ABI 2.4: |
| // If sizeof(T)*8 < n, let T' be the largest integral POD type with |
| // sizeof(T')*8 <= n. |
| |
| QualType IntegralPODTypes[] = { |
| Context.UnsignedCharTy, Context.UnsignedShortTy, Context.UnsignedIntTy, |
| Context.UnsignedLongTy, Context.UnsignedLongLongTy |
| }; |
| |
| QualType Type; |
| for (unsigned I = 0, E = llvm::array_lengthof(IntegralPODTypes); |
| I != E; ++I) { |
| uint64_t Size = Context.getTypeSize(IntegralPODTypes[I]); |
| |
| if (Size > FieldSize) |
| break; |
| |
| Type = IntegralPODTypes[I]; |
| } |
| assert(!Type.isNull() && "Did not find a type!"); |
| |
| unsigned TypeAlign = Context.getTypeAlign(Type); |
| |
| // We're not going to use any of the unfilled bits in the last byte. |
| UnfilledBitsInLastByte = 0; |
| |
| uint64_t FieldOffset; |
| |
| if (IsUnion) { |
| DataSize = std::max(DataSize, FieldSize); |
| FieldOffset = 0; |
| } else { |
| // The bitfield is allocated starting at the next offset aligned appropriately |
| // for T', with length n bits. |
| FieldOffset = llvm::RoundUpToAlignment(DataSize, TypeAlign); |
| |
| uint64_t NewSizeInBits = FieldOffset + FieldSize; |
| |
| DataSize = llvm::RoundUpToAlignment(NewSizeInBits, 8); |
| UnfilledBitsInLastByte = DataSize - NewSizeInBits; |
| } |
| |
| // Place this field at the current location. |
| FieldOffsets.push_back(FieldOffset); |
| |
| // Update the size. |
| Size = std::max(Size, DataSize); |
| |
| // Remember max struct/class alignment. |
| UpdateAlignment(TypeAlign); |
| } |
| |
| void RecordLayoutBuilder::LayoutBitField(const FieldDecl *D) { |
| bool FieldPacked = Packed || D->hasAttr<PackedAttr>(); |
| uint64_t FieldOffset = IsUnion ? 0 : (DataSize - UnfilledBitsInLastByte); |
| uint64_t FieldSize = D->getBitWidth()->EvaluateAsInt(Context).getZExtValue(); |
| |
| std::pair<uint64_t, unsigned> FieldInfo = Context.getTypeInfo(D->getType()); |
| uint64_t TypeSize = FieldInfo.first; |
| unsigned FieldAlign = FieldInfo.second; |
| |
| if (FieldSize > TypeSize) { |
| LayoutWideBitField(FieldSize, TypeSize); |
| return; |
| } |
| |
| if (FieldPacked || !Context.Target.useBitFieldTypeAlignment()) |
| FieldAlign = 1; |
| if (const AlignedAttr *AA = D->getAttr<AlignedAttr>()) |
| FieldAlign = std::max(FieldAlign, AA->getMaxAlignment()); |
| |
| // The maximum field alignment overrides the aligned attribute. |
| if (MaxFieldAlignment) |
| FieldAlign = std::min(FieldAlign, MaxFieldAlignment); |
| |
| // Check if we need to add padding to give the field the correct alignment. |
| if (FieldSize == 0 || (FieldOffset & (FieldAlign-1)) + FieldSize > TypeSize) |
| FieldOffset = llvm::RoundUpToAlignment(FieldOffset, FieldAlign); |
| |
| // Padding members don't affect overall alignment. |
| if (!D->getIdentifier()) |
| FieldAlign = 1; |
| |
| // Place this field at the current location. |
| FieldOffsets.push_back(FieldOffset); |
| |
| // Update DataSize to include the last byte containing (part of) the bitfield. |
| if (IsUnion) { |
| // FIXME: I think FieldSize should be TypeSize here. |
| DataSize = std::max(DataSize, FieldSize); |
| } else { |
| uint64_t NewSizeInBits = FieldOffset + FieldSize; |
| |
| DataSize = llvm::RoundUpToAlignment(NewSizeInBits, 8); |
| UnfilledBitsInLastByte = DataSize - NewSizeInBits; |
| } |
| |
| // Update the size. |
| Size = std::max(Size, DataSize); |
| |
| // Remember max struct/class alignment. |
| UpdateAlignment(FieldAlign); |
| } |
| |
| void RecordLayoutBuilder::LayoutField(const FieldDecl *D) { |
| if (D->isBitField()) { |
| LayoutBitField(D); |
| return; |
| } |
| |
| // Reset the unfilled bits. |
| UnfilledBitsInLastByte = 0; |
| |
| bool FieldPacked = Packed || D->hasAttr<PackedAttr>(); |
| uint64_t FieldOffset = IsUnion ? 0 : DataSize; |
| uint64_t FieldSize; |
| unsigned FieldAlign; |
| |
| if (D->getType()->isIncompleteArrayType()) { |
| // This is a flexible array member; we can't directly |
| // query getTypeInfo about these, so we figure it out here. |
| // Flexible array members don't have any size, but they |
| // have to be aligned appropriately for their element type. |
| FieldSize = 0; |
| const ArrayType* ATy = Context.getAsArrayType(D->getType()); |
| FieldAlign = Context.getTypeAlign(ATy->getElementType()); |
| } else if (const ReferenceType *RT = D->getType()->getAs<ReferenceType>()) { |
| unsigned AS = RT->getPointeeType().getAddressSpace(); |
| FieldSize = Context.Target.getPointerWidth(AS); |
| FieldAlign = Context.Target.getPointerAlign(AS); |
| } else { |
| std::pair<uint64_t, unsigned> FieldInfo = Context.getTypeInfo(D->getType()); |
| FieldSize = FieldInfo.first; |
| FieldAlign = FieldInfo.second; |
| } |
| |
| if (FieldPacked) |
| FieldAlign = 8; |
| if (const AlignedAttr *AA = D->getAttr<AlignedAttr>()) |
| FieldAlign = std::max(FieldAlign, AA->getMaxAlignment()); |
| |
| // The maximum field alignment overrides the aligned attribute. |
| if (MaxFieldAlignment) |
| FieldAlign = std::min(FieldAlign, MaxFieldAlignment); |
| |
| // Round up the current record size to the field's alignment boundary. |
| FieldOffset = llvm::RoundUpToAlignment(FieldOffset, FieldAlign); |
| |
| if (!IsUnion && EmptySubobjects) { |
| // Check if we can place the field at this offset. |
| while (!EmptySubobjects->CanPlaceFieldAtOffset(D, FieldOffset)) { |
| // We couldn't place the field at the offset. Try again at a new offset. |
| FieldOffset += FieldAlign; |
| } |
| } |
| |
| // Place this field at the current location. |
| FieldOffsets.push_back(FieldOffset); |
| |
| // Reserve space for this field. |
| if (IsUnion) |
| Size = std::max(Size, FieldSize); |
| else |
| Size = FieldOffset + FieldSize; |
| |
| // Update the data size. |
| DataSize = Size; |
| |
| // Remember max struct/class alignment. |
| UpdateAlignment(FieldAlign); |
| } |
| |
| void RecordLayoutBuilder::FinishLayout() { |
| // In C++, records cannot be of size 0. |
| if (Context.getLangOptions().CPlusPlus && Size == 0) |
| Size = 8; |
| // Finally, round the size of the record up to the alignment of the |
| // record itself. |
| Size = llvm::RoundUpToAlignment(Size, Alignment); |
| } |
| |
| void RecordLayoutBuilder::UpdateAlignment(unsigned NewAlignment) { |
| // The alignment is not modified when using 'mac68k' alignment. |
| if (IsMac68kAlign) |
| return; |
| |
| if (NewAlignment <= Alignment) |
| return; |
| |
| assert(llvm::isPowerOf2_32(NewAlignment && "Alignment not a power of 2")); |
| |
| Alignment = NewAlignment; |
| } |
| |
| const CXXMethodDecl * |
| RecordLayoutBuilder::ComputeKeyFunction(const CXXRecordDecl *RD) { |
| // If a class isn't polymorphic it doesn't have a key function. |
| if (!RD->isPolymorphic()) |
| return 0; |
| |
| // A class inside an anonymous namespace doesn't have a key function. (Or |
| // at least, there's no point to assigning a key function to such a class; |
| // this doesn't affect the ABI.) |
| if (RD->isInAnonymousNamespace()) |
| return 0; |
| |
| for (CXXRecordDecl::method_iterator I = RD->method_begin(), |
| E = RD->method_end(); I != E; ++I) { |
| const CXXMethodDecl *MD = *I; |
| |
| if (!MD->isVirtual()) |
| continue; |
| |
| if (MD->isPure()) |
| continue; |
| |
| // Ignore implicit member functions, they are always marked as inline, but |
| // they don't have a body until they're defined. |
| if (MD->isImplicit()) |
| continue; |
| |
| if (MD->isInlineSpecified()) |
| continue; |
| |
| if (MD->hasInlineBody()) |
| continue; |
| |
| // We found it. |
| return MD; |
| } |
| |
| return 0; |
| } |
| |
| /// getASTRecordLayout - Get or compute information about the layout of the |
| /// specified record (struct/union/class), which indicates its size and field |
| /// position information. |
| const ASTRecordLayout &ASTContext::getASTRecordLayout(const RecordDecl *D) { |
| D = D->getDefinition(); |
| assert(D && "Cannot get layout of forward declarations!"); |
| |
| // Look up this layout, if already laid out, return what we have. |
| // Note that we can't save a reference to the entry because this function |
| // is recursive. |
| const ASTRecordLayout *Entry = ASTRecordLayouts[D]; |
| if (Entry) return *Entry; |
| |
| const ASTRecordLayout *NewEntry; |
| |
| if (const CXXRecordDecl *RD = dyn_cast<CXXRecordDecl>(D)) { |
| EmptySubobjectMap EmptySubobjects(*this, RD); |
| |
| RecordLayoutBuilder Builder(*this, &EmptySubobjects); |
| Builder.Layout(RD); |
| |
| // FIXME: This is not always correct. See the part about bitfields at |
| // http://www.codesourcery.com/public/cxx-abi/abi.html#POD for more info. |
| // FIXME: IsPODForThePurposeOfLayout should be stored in the record layout. |
| bool IsPODForThePurposeOfLayout = cast<CXXRecordDecl>(D)->isPOD(); |
| |
| // FIXME: This should be done in FinalizeLayout. |
| uint64_t DataSize = |
| IsPODForThePurposeOfLayout ? Builder.Size : Builder.DataSize; |
| uint64_t NonVirtualSize = |
| IsPODForThePurposeOfLayout ? DataSize : Builder.NonVirtualSize; |
| |
| NewEntry = |
| new (*this) ASTRecordLayout(*this, Builder.Size, Builder.Alignment, |
| DataSize, Builder.FieldOffsets.data(), |
| Builder.FieldOffsets.size(), |
| NonVirtualSize, |
| Builder.NonVirtualAlignment, |
| EmptySubobjects.SizeOfLargestEmptySubobject, |
| Builder.PrimaryBase, |
| Builder.PrimaryBaseIsVirtual, |
| Builder.Bases, Builder.VBases); |
| } else { |
| RecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/0); |
| Builder.Layout(D); |
| |
| NewEntry = |
| new (*this) ASTRecordLayout(*this, Builder.Size, Builder.Alignment, |
| Builder.Size, |
| Builder.FieldOffsets.data(), |
| Builder.FieldOffsets.size()); |
| } |
| |
| ASTRecordLayouts[D] = NewEntry; |
| |
| if (getLangOptions().DumpRecordLayouts) { |
| llvm::errs() << "\n*** Dumping AST Record Layout\n"; |
| DumpRecordLayout(D, llvm::errs()); |
| } |
| |
| return *NewEntry; |
| } |
| |
| const CXXMethodDecl *ASTContext::getKeyFunction(const CXXRecordDecl *RD) { |
| RD = cast<CXXRecordDecl>(RD->getDefinition()); |
| assert(RD && "Cannot get key function for forward declarations!"); |
| |
| const CXXMethodDecl *&Entry = KeyFunctions[RD]; |
| if (!Entry) |
| Entry = RecordLayoutBuilder::ComputeKeyFunction(RD); |
| else |
| assert(Entry == RecordLayoutBuilder::ComputeKeyFunction(RD) && |
| "Key function changed!"); |
| |
| return Entry; |
| } |
| |
| /// getInterfaceLayoutImpl - Get or compute information about the |
| /// layout of the given interface. |
| /// |
| /// \param Impl - If given, also include the layout of the interface's |
| /// implementation. This may differ by including synthesized ivars. |
| const ASTRecordLayout & |
| ASTContext::getObjCLayout(const ObjCInterfaceDecl *D, |
| const ObjCImplementationDecl *Impl) { |
| assert(!D->isForwardDecl() && "Invalid interface decl!"); |
| |
| // Look up this layout, if already laid out, return what we have. |
| ObjCContainerDecl *Key = |
| Impl ? (ObjCContainerDecl*) Impl : (ObjCContainerDecl*) D; |
| if (const ASTRecordLayout *Entry = ObjCLayouts[Key]) |
| return *Entry; |
| |
| // Add in synthesized ivar count if laying out an implementation. |
| if (Impl) { |
| unsigned SynthCount = CountNonClassIvars(D); |
| // If there aren't any sythesized ivars then reuse the interface |
| // entry. Note we can't cache this because we simply free all |
| // entries later; however we shouldn't look up implementations |
| // frequently. |
| if (SynthCount == 0) |
| return getObjCLayout(D, 0); |
| } |
| |
| RecordLayoutBuilder Builder(*this, /*EmptySubobjects=*/0); |
| Builder.Layout(D); |
| |
| const ASTRecordLayout *NewEntry = |
| new (*this) ASTRecordLayout(*this, Builder.Size, Builder.Alignment, |
| Builder.DataSize, |
| Builder.FieldOffsets.data(), |
| Builder.FieldOffsets.size()); |
| |
| ObjCLayouts[Key] = NewEntry; |
| |
| return *NewEntry; |
| } |
| |
| static void PrintOffset(llvm::raw_ostream &OS, |
| uint64_t Offset, unsigned IndentLevel) { |
| OS << llvm::format("%4d | ", Offset); |
| OS.indent(IndentLevel * 2); |
| } |
| |
| static void DumpCXXRecordLayout(llvm::raw_ostream &OS, |
| const CXXRecordDecl *RD, ASTContext &C, |
| uint64_t Offset, |
| unsigned IndentLevel, |
| const char* Description, |
| bool IncludeVirtualBases) { |
| const ASTRecordLayout &Info = C.getASTRecordLayout(RD); |
| |
| PrintOffset(OS, Offset, IndentLevel); |
| OS << C.getTypeDeclType(const_cast<CXXRecordDecl *>(RD)).getAsString(); |
| if (Description) |
| OS << ' ' << Description; |
| if (RD->isEmpty()) |
| OS << " (empty)"; |
| OS << '\n'; |
| |
| IndentLevel++; |
| |
| const CXXRecordDecl *PrimaryBase = Info.getPrimaryBase(); |
| |
| // Vtable pointer. |
| if (RD->isDynamicClass() && !PrimaryBase) { |
| PrintOffset(OS, Offset, IndentLevel); |
| OS << '(' << RD << " vtable pointer)\n"; |
| } |
| // Dump (non-virtual) bases |
| for (CXXRecordDecl::base_class_const_iterator I = RD->bases_begin(), |
| E = RD->bases_end(); I != E; ++I) { |
| assert(!I->getType()->isDependentType() && |
| "Cannot layout class with dependent bases."); |
| if (I->isVirtual()) |
| continue; |
| |
| const CXXRecordDecl *Base = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| uint64_t BaseOffset = Offset + Info.getBaseClassOffset(Base) / 8; |
| |
| DumpCXXRecordLayout(OS, Base, C, BaseOffset, IndentLevel, |
| Base == PrimaryBase ? "(primary base)" : "(base)", |
| /*IncludeVirtualBases=*/false); |
| } |
| |
| // Dump fields. |
| uint64_t FieldNo = 0; |
| for (CXXRecordDecl::field_iterator I = RD->field_begin(), |
| E = RD->field_end(); I != E; ++I, ++FieldNo) { |
| const FieldDecl *Field = *I; |
| uint64_t FieldOffset = Offset + Info.getFieldOffset(FieldNo) / 8; |
| |
| if (const RecordType *RT = Field->getType()->getAs<RecordType>()) { |
| if (const CXXRecordDecl *D = dyn_cast<CXXRecordDecl>(RT->getDecl())) { |
| DumpCXXRecordLayout(OS, D, C, FieldOffset, IndentLevel, |
| Field->getNameAsCString(), |
| /*IncludeVirtualBases=*/true); |
| continue; |
| } |
| } |
| |
| PrintOffset(OS, FieldOffset, IndentLevel); |
| OS << Field->getType().getAsString() << ' ' << Field << '\n'; |
| } |
| |
| if (!IncludeVirtualBases) |
| return; |
| |
| // Dump virtual bases. |
| for (CXXRecordDecl::base_class_const_iterator I = RD->vbases_begin(), |
| E = RD->vbases_end(); I != E; ++I) { |
| assert(I->isVirtual() && "Found non-virtual class!"); |
| const CXXRecordDecl *VBase = |
| cast<CXXRecordDecl>(I->getType()->getAs<RecordType>()->getDecl()); |
| |
| uint64_t VBaseOffset = Offset + Info.getVBaseClassOffset(VBase) / 8; |
| DumpCXXRecordLayout(OS, VBase, C, VBaseOffset, IndentLevel, |
| VBase == PrimaryBase ? |
| "(primary virtual base)" : "(virtual base)", |
| /*IncludeVirtualBases=*/false); |
| } |
| |
| OS << " sizeof=" << Info.getSize() / 8; |
| OS << ", dsize=" << Info.getDataSize() / 8; |
| OS << ", align=" << Info.getAlignment() / 8 << '\n'; |
| OS << " nvsize=" << Info.getNonVirtualSize() / 8; |
| OS << ", nvalign=" << Info.getNonVirtualAlign() / 8 << '\n'; |
| OS << '\n'; |
| } |
| |
| void ASTContext::DumpRecordLayout(const RecordDecl *RD, |
| llvm::raw_ostream &OS) { |
| const ASTRecordLayout &Info = getASTRecordLayout(RD); |
| |
| if (const CXXRecordDecl *CXXRD = dyn_cast<CXXRecordDecl>(RD)) |
| return DumpCXXRecordLayout(OS, CXXRD, *this, 0, 0, 0, |
| /*IncludeVirtualBases=*/true); |
| |
| OS << "Type: " << getTypeDeclType(RD).getAsString() << "\n"; |
| OS << "Record: "; |
| RD->dump(); |
| OS << "\nLayout: "; |
| OS << "<ASTRecordLayout\n"; |
| OS << " Size:" << Info.getSize() << "\n"; |
| OS << " DataSize:" << Info.getDataSize() << "\n"; |
| OS << " Alignment:" << Info.getAlignment() << "\n"; |
| OS << " FieldOffsets: ["; |
| for (unsigned i = 0, e = Info.getFieldCount(); i != e; ++i) { |
| if (i) OS << ", "; |
| OS << Info.getFieldOffset(i); |
| } |
| OS << "]>\n"; |
| } |