| //===--- CodeGenTypes.cpp - Type translation for LLVM CodeGen -------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by Chris Lattner and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This is the code that handles AST -> LLVM type lowering. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "CodeGenTypes.h" |
| #include "clang/Basic/TargetInfo.h" |
| #include "clang/AST/AST.h" |
| #include "llvm/DerivedTypes.h" |
| #include "llvm/Module.h" |
| #include "llvm/Target/TargetData.h" |
| |
| using namespace clang; |
| using namespace CodeGen; |
| |
| namespace { |
| /// RecordOrganizer - This helper class, used by CGRecordLayout, layouts |
| /// structs and unions. It manages transient information used during layout. |
| /// FIXME : At the moment assume |
| /// - one to one mapping between AST FieldDecls and |
| /// llvm::StructType elements. |
| /// - Ignore bit fields |
| /// - Ignore field aligments |
| /// - Ignore packed structs |
| class RecordOrganizer { |
| public: |
| explicit RecordOrganizer(CodeGenTypes &Types) : |
| CGT(Types), STy(NULL), FieldNo(0), Cursor(0), ExtraBits(0), |
| CurrentFieldStart(0) {} |
| |
| /// addField - Add new field. |
| void addField(const FieldDecl *FD); |
| |
| /// addLLVMField - Add llvm struct field that corresponds to llvm type Ty. |
| /// Update cursor and increment field count. |
| void addLLVMField(const llvm::Type *Ty, uint64_t Size, |
| const FieldDecl *FD = NULL, unsigned Begin = 0, |
| unsigned End = 0); |
| |
| /// addPaddingFields - Current cursor is not suitable place to add next |
| /// field. Add required padding fields. |
| void addPaddingFields(unsigned RequiredBits); |
| |
| /// layoutStructFields - Do the actual work and lay out all fields. Create |
| /// corresponding llvm struct type. This should be invoked only after |
| /// all fields are added. |
| void layoutStructFields(const ASTRecordLayout &RL); |
| |
| /// layoutUnionFields - Do the actual work and lay out all fields. Create |
| /// corresponding llvm struct type. This should be invoked only after |
| /// all fields are added. |
| void layoutUnionFields(); |
| |
| /// getLLVMType - Return associated llvm struct type. This may be NULL |
| /// if fields are not laid out. |
| llvm::Type *getLLVMType() const { |
| return STy; |
| } |
| |
| /// fixCursorPosition - When bit-field is followed by a normal field |
| /// cursor position may require some adjustments. |
| /// |
| /// For example, struct { char a; short b:2; char c; }; |
| /// |
| /// At the beginning of field 'c' layout, cursor position is 10. |
| /// However, only llvm struct field allocated so far is of type i8. |
| /// This happens because 'b' shares llvm field with 'a'. Add padding |
| /// field of i8 type and reposition cursor to point at 16. This |
| /// should be done only if next field (i.e. 'c' here) is not a bit-field |
| /// or last record field is a bit-field. |
| void fixCursorPosition(const ASTRecordLayout &RL); |
| |
| /// placeBitField - Find a place for FD, which is a bit-field. |
| void placeBitField(const FieldDecl *FD); |
| |
| private: |
| CodeGenTypes &CGT; |
| llvm::Type *STy; |
| unsigned FieldNo; |
| uint64_t Cursor; |
| /* If last field is a bitfield then it may not have occupied all allocated |
| bits. Use remaining bits for next field if it also a bitfield. */ |
| uint64_t ExtraBits; |
| /* CurrentFieldStart - Indicates starting offset for current llvm field. |
| When current llvm field is shared by multiple bitfields, this is |
| used find starting bit offset for the bitfield from the beginning of |
| llvm field. */ |
| uint64_t CurrentFieldStart; |
| llvm::SmallVector<const FieldDecl *, 8> FieldDecls; |
| std::vector<const llvm::Type*> LLVMFields; |
| llvm::SmallVector<uint64_t, 8> Offsets; |
| }; |
| } |
| |
| CodeGenTypes::CodeGenTypes(ASTContext &Ctx, llvm::Module& M, |
| const llvm::TargetData &TD) |
| : Context(Ctx), Target(Ctx.Target), TheModule(M), TheTargetData(TD) { |
| } |
| |
| CodeGenTypes::~CodeGenTypes() { |
| for(llvm::DenseMap<const llvm::Type *, CGRecordLayout *>::iterator |
| I = CGRecordLayouts.begin(), E = CGRecordLayouts.end(); |
| I != E; ++I) |
| delete I->second; |
| CGRecordLayouts.clear(); |
| } |
| |
| /// ConvertType - Convert the specified type to its LLVM form. |
| const llvm::Type *CodeGenTypes::ConvertType(QualType T) { |
| // See if type is already cached. |
| llvm::DenseMap<Type *, llvm::PATypeHolder>::iterator |
| I = TypeHolderMap.find(T.getTypePtr()); |
| if (I != TypeHolderMap.end()) |
| return I->second.get(); |
| |
| const llvm::Type *ResultType = ConvertNewType(T); |
| TypeHolderMap.insert(std::make_pair(T.getTypePtr(), |
| llvm::PATypeHolder(ResultType))); |
| return ResultType; |
| } |
| |
| const llvm::Type *CodeGenTypes::ConvertNewType(QualType T) { |
| const clang::Type &Ty = *T.getCanonicalType(); |
| |
| switch (Ty.getTypeClass()) { |
| case Type::TypeName: // typedef isn't canonical. |
| case Type::TypeOfExp: // typeof isn't canonical. |
| case Type::TypeOfTyp: // typeof isn't canonical. |
| assert(0 && "Non-canonical type, shouldn't happen"); |
| case Type::Builtin: { |
| switch (cast<BuiltinType>(Ty).getKind()) { |
| case BuiltinType::Void: |
| // LLVM void type can only be used as the result of a function call. Just |
| // map to the same as char. |
| return llvm::IntegerType::get(8); |
| |
| case BuiltinType::Bool: |
| // FIXME: This is very strange. We want scalars to be i1, but in memory |
| // they can be i1 or i32. Should the codegen handle this issue? |
| return llvm::Type::Int1Ty; |
| |
| case BuiltinType::Char_S: |
| case BuiltinType::Char_U: |
| case BuiltinType::SChar: |
| case BuiltinType::UChar: |
| case BuiltinType::Short: |
| case BuiltinType::UShort: |
| case BuiltinType::Int: |
| case BuiltinType::UInt: |
| case BuiltinType::Long: |
| case BuiltinType::ULong: |
| case BuiltinType::LongLong: |
| case BuiltinType::ULongLong: |
| return llvm::IntegerType::get( |
| static_cast<unsigned>(Context.getTypeSize(T, SourceLocation()))); |
| |
| case BuiltinType::Float: return llvm::Type::FloatTy; |
| case BuiltinType::Double: return llvm::Type::DoubleTy; |
| case BuiltinType::LongDouble: |
| // FIXME: mapping long double onto double. |
| return llvm::Type::DoubleTy; |
| } |
| break; |
| } |
| case Type::Complex: { |
| std::vector<const llvm::Type*> Elts; |
| Elts.push_back(ConvertType(cast<ComplexType>(Ty).getElementType())); |
| Elts.push_back(Elts[0]); |
| return llvm::StructType::get(Elts); |
| } |
| case Type::Pointer: { |
| const PointerType &P = cast<PointerType>(Ty); |
| return llvm::PointerType::get(ConvertType(P.getPointeeType())); |
| } |
| case Type::Reference: { |
| const ReferenceType &R = cast<ReferenceType>(Ty); |
| return llvm::PointerType::get(ConvertType(R.getReferenceeType())); |
| } |
| |
| case Type::VariableArray: { |
| const VariableArrayType &A = cast<VariableArrayType>(Ty); |
| assert(A.getSizeModifier() == ArrayType::Normal && |
| A.getIndexTypeQualifier() == 0 && |
| "FIXME: We only handle trivial array types so far!"); |
| if (A.getSizeExpr() == 0) { |
| // int X[] -> [0 x int] |
| return llvm::ArrayType::get(ConvertType(A.getElementType()), 0); |
| } else { |
| assert(0 && "FIXME: VLAs not implemented yet!"); |
| } |
| } |
| case Type::ConstantArray: { |
| const ConstantArrayType &A = cast<ConstantArrayType>(Ty); |
| const llvm::Type *EltTy = ConvertType(A.getElementType()); |
| return llvm::ArrayType::get(EltTy, A.getSize().getZExtValue()); |
| } |
| case Type::OCUVector: |
| case Type::Vector: { |
| const VectorType &VT = cast<VectorType>(Ty); |
| return llvm::VectorType::get(ConvertType(VT.getElementType()), |
| VT.getNumElements()); |
| } |
| case Type::FunctionNoProto: |
| case Type::FunctionProto: { |
| const FunctionType &FP = cast<FunctionType>(Ty); |
| const llvm::Type *ResultType; |
| |
| if (FP.getResultType()->isVoidType()) |
| ResultType = llvm::Type::VoidTy; // Result of function uses llvm void. |
| else |
| ResultType = ConvertType(FP.getResultType()); |
| |
| // FIXME: Convert argument types. |
| bool isVarArg; |
| std::vector<const llvm::Type*> ArgTys; |
| |
| // Struct return passes the struct byref. |
| if (!ResultType->isFirstClassType() && ResultType != llvm::Type::VoidTy) { |
| const llvm::Type *RType = llvm::PointerType::get(ResultType); |
| QualType RTy = Context.getPointerType(FP.getResultType()); |
| TypeHolderMap.insert(std::make_pair(RTy.getTypePtr(), |
| llvm::PATypeHolder(RType))); |
| |
| ArgTys.push_back(RType); |
| ResultType = llvm::Type::VoidTy; |
| } |
| |
| if (const FunctionTypeProto *FTP = dyn_cast<FunctionTypeProto>(&FP)) { |
| DecodeArgumentTypes(*FTP, ArgTys); |
| isVarArg = FTP->isVariadic(); |
| } else { |
| isVarArg = true; |
| } |
| |
| return llvm::FunctionType::get(ResultType, ArgTys, isVarArg); |
| } |
| |
| case Type::ObjcInterface: |
| assert(0 && "FIXME: add missing functionality here"); |
| break; |
| |
| case Type::ObjcQualifiedInterface: |
| assert(0 && "FIXME: add missing functionality here"); |
| break; |
| |
| case Type::Tagged: |
| const TagType &TT = cast<TagType>(Ty); |
| const TagDecl *TD = TT.getDecl(); |
| llvm::Type *&ResultType = TagDeclTypes[TD]; |
| |
| if (ResultType) |
| return ResultType; |
| |
| if (!TD->isDefinition()) { |
| ResultType = llvm::OpaqueType::get(); |
| } else if (TD->getKind() == Decl::Enum) { |
| return ConvertType(cast<EnumDecl>(TD)->getIntegerType()); |
| } else if (TD->getKind() == Decl::Struct) { |
| const RecordDecl *RD = cast<const RecordDecl>(TD); |
| |
| // If this is nested record and this RecordDecl is already under |
| // process then return associated OpaqueType for now. |
| llvm::DenseMap<const RecordDecl *, llvm::Type *>::iterator |
| OpaqueI = RecordTypesToResolve.find(RD); |
| if (OpaqueI != RecordTypesToResolve.end()) |
| return OpaqueI->second; |
| |
| // Create new OpaqueType now for later use. |
| // FIXME: This creates a lot of opaque types, most of them are not |
| // needed. Reevaluate this when performance analyis finds tons of |
| // opaque types. |
| llvm::OpaqueType *OpaqueTy = llvm::OpaqueType::get(); |
| RecordTypesToResolve[RD] = OpaqueTy; |
| TypeHolderMap.insert(std::make_pair(T.getTypePtr(), |
| llvm::PATypeHolder(OpaqueTy))); |
| |
| // Layout fields. |
| RecordOrganizer RO(*this); |
| for (unsigned i = 0, e = RD->getNumMembers(); i != e; ++i) |
| RO.addField(RD->getMember(i)); |
| const ASTRecordLayout &RL = Context.getASTRecordLayout(RD, |
| SourceLocation()); |
| RO.layoutStructFields(RL); |
| |
| // Get llvm::StructType. |
| CGRecordLayout *RLI = new CGRecordLayout(RO.getLLVMType()); |
| ResultType = RLI->getLLVMType(); |
| CGRecordLayouts[ResultType] = RLI; |
| |
| // Refine any OpaqueType associated with this RecordDecl. |
| OpaqueTy->refineAbstractTypeTo(ResultType); |
| OpaqueI = RecordTypesToResolve.find(RD); |
| assert (OpaqueI != RecordTypesToResolve.end() |
| && "Expected RecordDecl in RecordTypesToResolve"); |
| RecordTypesToResolve.erase(OpaqueI); |
| |
| } else if (TD->getKind() == Decl::Union) { |
| const RecordDecl *RD = cast<const RecordDecl>(TD); |
| // Just use the largest element of the union, breaking ties with the |
| // highest aligned member. |
| |
| if (RD->getNumMembers() != 0) { |
| RecordOrganizer RO(*this); |
| for (unsigned i = 0, e = RD->getNumMembers(); i != e; ++i) |
| RO.addField(RD->getMember(i)); |
| RO.layoutUnionFields(); |
| |
| // Get llvm::StructType. |
| CGRecordLayout *RLI = new CGRecordLayout(RO.getLLVMType()); |
| ResultType = RLI->getLLVMType(); |
| CGRecordLayouts[ResultType] = RLI; |
| } else { |
| std::vector<const llvm::Type*> Fields; |
| ResultType = llvm::StructType::get(Fields); |
| } |
| } else { |
| assert(0 && "FIXME: Implement tag decl kind!"); |
| } |
| |
| std::string TypeName(TD->getKindName()); |
| TypeName += '.'; |
| |
| // Name the codegen type after the typedef name |
| // if there is no tag type name available |
| if (TD->getIdentifier() == 0) { |
| if (T->getTypeClass() == Type::TypeName) { |
| const TypedefType *TdT = cast<TypedefType>(T); |
| TypeName += TdT->getDecl()->getName(); |
| } else |
| TypeName += "anon"; |
| } else |
| TypeName += TD->getName(); |
| |
| TheModule.addTypeName(TypeName, ResultType); |
| return ResultType; |
| } |
| |
| // FIXME: implement. |
| return llvm::OpaqueType::get(); |
| } |
| |
| void CodeGenTypes::DecodeArgumentTypes(const FunctionTypeProto &FTP, |
| std::vector<const llvm::Type*> &ArgTys) { |
| for (unsigned i = 0, e = FTP.getNumArgs(); i != e; ++i) { |
| const llvm::Type *Ty = ConvertType(FTP.getArgType(i)); |
| if (Ty->isFirstClassType()) |
| ArgTys.push_back(Ty); |
| else { |
| QualType PTy = Context.getPointerType(FTP.getArgType(i)); |
| const llvm::Type *PtrTy = llvm::PointerType::get(Ty); |
| TypeHolderMap.insert(std::make_pair(PTy.getTypePtr(), |
| llvm::PATypeHolder(PtrTy))); |
| |
| ArgTys.push_back(PtrTy); |
| } |
| } |
| } |
| |
| /// getLLVMFieldNo - Return llvm::StructType element number |
| /// that corresponds to the field FD. |
| unsigned CodeGenTypes::getLLVMFieldNo(const FieldDecl *FD) { |
| // FIXME : Check bit fields also |
| llvm::DenseMap<const FieldDecl *, unsigned>::iterator |
| I = FieldInfo.find(FD); |
| assert (I != FieldInfo.end() && "Unable to find field info"); |
| return I->second; |
| } |
| |
| /// addFieldInfo - Assign field number to field FD. |
| void CodeGenTypes::addFieldInfo(const FieldDecl *FD, unsigned No, |
| unsigned Begin, unsigned End) { |
| if (Begin == 0 && End == 0) |
| FieldInfo[FD] = No; |
| else |
| // FD is a bit field |
| BitFields.insert(std::make_pair(FD, BitFieldInfo(No, Begin, End))); |
| } |
| |
| /// getCGRecordLayout - Return record layout info for the given llvm::Type. |
| const CGRecordLayout * |
| CodeGenTypes::getCGRecordLayout(const llvm::Type* Ty) const { |
| llvm::DenseMap<const llvm::Type*, CGRecordLayout *>::iterator I |
| = CGRecordLayouts.find(Ty); |
| assert (I != CGRecordLayouts.end() |
| && "Unable to find record layout information for type"); |
| return I->second; |
| } |
| |
| /// addField - Add new field. |
| void RecordOrganizer::addField(const FieldDecl *FD) { |
| assert (!STy && "Record fields are already laid out"); |
| FieldDecls.push_back(FD); |
| } |
| |
| /// layoutStructFields - Do the actual work and lay out all fields. Create |
| /// corresponding llvm struct type. This should be invoked only after |
| /// all fields are added. |
| /// FIXME : At the moment assume |
| /// - one to one mapping between AST FieldDecls and |
| /// llvm::StructType elements. |
| /// - Ignore bit fields |
| /// - Ignore field aligments |
| /// - Ignore packed structs |
| void RecordOrganizer::layoutStructFields(const ASTRecordLayout &RL) { |
| // FIXME : Use SmallVector |
| Cursor = 0; |
| FieldNo = 0; |
| LLVMFields.clear(); |
| for (llvm::SmallVector<const FieldDecl *, 8>::iterator I = FieldDecls.begin(), |
| E = FieldDecls.end(); I != E; ++I) { |
| const FieldDecl *FD = *I; |
| |
| if (FD->isBitField()) |
| placeBitField(FD); |
| else { |
| ExtraBits = 0; |
| // FD is not a bitfield. If prev field was a bit field then it may have |
| // positioned cursor such that it needs adjustment now. |
| if (Cursor % 8 != 0) |
| fixCursorPosition(RL); |
| |
| const llvm::Type *Ty = CGT.ConvertType(FD->getType()); |
| addLLVMField(Ty, CGT.getTargetData().getABITypeSizeInBits(Ty), FD, 0, 0); |
| } |
| } |
| |
| // At the end of structure, cursor should point to end of the strucutre. |
| // This may not happen automatically if last field is a bit-field. |
| fixCursorPosition(RL); |
| |
| STy = llvm::StructType::get(LLVMFields); |
| } |
| |
| /// addPaddingFields - Current cursor is not suitable place to add next field. |
| /// Add required padding fields. |
| void RecordOrganizer::addPaddingFields(unsigned RequiredBits) { |
| assert ((RequiredBits % 8) == 0 && "FIXME Invalid struct layout"); |
| unsigned RequiredBytes = RequiredBits / 8; |
| for (unsigned i = 0; i != RequiredBytes; ++i) |
| addLLVMField(llvm::Type::Int8Ty, |
| CGT.getTargetData().getABITypeSizeInBits(llvm::Type::Int8Ty)); |
| } |
| |
| /// addLLVMField - Add llvm struct field that corresponds to llvm type Ty. |
| /// Update cursor and increment field count. If field decl FD is available than |
| /// update field info at CodeGenTypes level. |
| void RecordOrganizer::addLLVMField(const llvm::Type *Ty, uint64_t Size, |
| const FieldDecl *FD, unsigned Begin, |
| unsigned End) { |
| |
| unsigned AlignmentInBits = CGT.getTargetData().getABITypeAlignment(Ty) * 8; |
| if (Cursor % AlignmentInBits != 0) |
| // At the moment, insert padding fields even if target specific llvm |
| // type alignment enforces implict padding fields for FD. Later on, |
| // optimize llvm fields by removing implicit padding fields and |
| // combining consequetive padding fields. |
| addPaddingFields(Cursor % AlignmentInBits); |
| |
| Offsets.push_back(Cursor); |
| CurrentFieldStart = Cursor; |
| Cursor += Size; |
| LLVMFields.push_back(Ty); |
| if (FD) |
| CGT.addFieldInfo(FD, FieldNo, Begin, End); |
| ++FieldNo; |
| } |
| |
| /// layoutUnionFields - Do the actual work and lay out all fields. Create |
| /// corresponding llvm struct type. This should be invoked only after |
| /// all fields are added. |
| void RecordOrganizer::layoutUnionFields() { |
| |
| unsigned PrimaryEltNo = 0; |
| std::pair<uint64_t, unsigned> PrimaryElt = |
| CGT.getContext().getTypeInfo(FieldDecls[0]->getType(), SourceLocation()); |
| CGT.addFieldInfo(FieldDecls[0], 0, 0, 0); |
| |
| unsigned Size = FieldDecls.size(); |
| for(unsigned i = 1; i != Size; ++i) { |
| const FieldDecl *FD = FieldDecls[i]; |
| assert (!FD->isBitField() && "Bit fields are not yet supported"); |
| std::pair<uint64_t, unsigned> EltInfo = |
| CGT.getContext().getTypeInfo(FD->getType(), SourceLocation()); |
| |
| // Use largest element, breaking ties with the hightest aligned member. |
| if (EltInfo.first > PrimaryElt.first || |
| (EltInfo.first == PrimaryElt.first && |
| EltInfo.second > PrimaryElt.second)) { |
| PrimaryElt = EltInfo; |
| PrimaryEltNo = i; |
| } |
| |
| // In union, each field gets first slot. |
| CGT.addFieldInfo(FD, 0, 0, 0); |
| } |
| |
| std::vector<const llvm::Type*> Fields; |
| const llvm::Type *Ty = CGT.ConvertType(FieldDecls[PrimaryEltNo]->getType()); |
| Fields.push_back(Ty); |
| STy = llvm::StructType::get(Fields); |
| } |
| |
| /// fixCursorPosition - When bit-field is followed by a normal field |
| /// cursor position may require some adjustments. |
| /// |
| /// For example, struct { char a; short b:2; char c; }; |
| /// |
| /// At the beginning of field 'c' layout, cursor position is 10. |
| /// However, only llvm struct field allocated so far is of type i8. |
| /// This happens because 'b' shares llvm field with 'a'. Add padding |
| /// field of i8 type and reposition cursor to point at 16. This |
| /// should be done only if next field (i.e. 'c' here) is not a bit-field |
| /// or last record field is a bit-field. |
| void RecordOrganizer::fixCursorPosition(const ASTRecordLayout &RL) { |
| uint64_t llvmSize = 0; |
| for(std::vector<const llvm::Type*>::iterator LI = LLVMFields.begin(), |
| LE = LLVMFields.end(); LI != LE; ++LI) { |
| const llvm::Type *Ty = *LI; |
| llvmSize += CGT.getTargetData().getABITypeSizeInBits(Ty); |
| } |
| Cursor = llvmSize; |
| unsigned llvmSizeBytes = llvmSize/8; |
| unsigned StructAlign = RL.getAlignment() / 8; |
| if (llvmSizeBytes % StructAlign) { |
| unsigned StructPadding = StructAlign - (llvmSizeBytes % StructAlign); |
| addPaddingFields(StructPadding*8); |
| } |
| } |
| |
| /// placeBitField - Find a place for FD, which is a bit-field. |
| /// There are three separate cases to handle |
| /// 1) Cursor starts at byte boundry and there are no extra |
| /// bits are available in last llvm struct field. |
| /// 2) Extra bits from previous last llvm struct field are |
| /// available and have enough space to hold entire FD. |
| /// 3) Extra bits from previous last llvm struct field are |
| /// available but they are not enough to hold FD entirly. |
| void RecordOrganizer::placeBitField(const FieldDecl *FD) { |
| |
| assert (FD->isBitField() && "FD is not a bit-field"); |
| Expr *BitWidth = FD->getBitWidth(); |
| llvm::APSInt FieldSize(32); |
| bool isBitField = |
| BitWidth->isIntegerConstantExpr(FieldSize, CGT.getContext()); |
| assert (isBitField && "Invalid BitField size expression"); |
| uint64_t BitFieldSize = FieldSize.getZExtValue(); |
| if (ExtraBits == 0) { |
| // CurrentField is a bit-field and structure is in one of the |
| // following form. |
| // struct { char CurrentField:2; char B:4; } |
| // struct { char A; char CurrentField:2; }; |
| // struct { char A; short CurrentField:2; }; |
| const llvm::Type *Ty = CGT.ConvertType(FD->getType()); |
| // Calculate extra bits available in this bitfield. |
| ExtraBits = CGT.getTargetData().getABITypeSizeInBits(Ty) - BitFieldSize; |
| |
| if (LLVMFields.empty()) |
| // Ths is - struct { char CurrentField:2; char B:4; } |
| addLLVMField(Ty, BitFieldSize, FD, 0, ExtraBits); |
| else { |
| const llvm::Type *PrevTy = LLVMFields.back(); |
| if (CGT.getTargetData().getABITypeSizeInBits(PrevTy) >= |
| CGT.getTargetData().getABITypeSizeInBits(Ty)) |
| // This is - struct { char A; char CurrentField:2; }; |
| addLLVMField(Ty, BitFieldSize, FD, 0, ExtraBits); |
| else { |
| // This is - struct { char A; short CurrentField:2; }; |
| // Use one of the previous filed to access current field. |
| bool FoundPrevField = false; |
| unsigned TotalOffsets = Offsets.size(); |
| uint64_t TySize = CGT.getTargetData().getABITypeSizeInBits(Ty); |
| for (unsigned i = TotalOffsets; i != 0; --i) { |
| uint64_t O = Offsets[i - 1]; |
| if (O % TySize == 0) { |
| // This is appropriate llvm field to share access. |
| FoundPrevField = true; |
| CurrentFieldStart = O % TySize; |
| unsigned FieldBegin = Cursor - (O % TySize); |
| unsigned FieldEnd = TySize - (FieldBegin + BitFieldSize); |
| Cursor += BitFieldSize; |
| CGT.addFieldInfo(FD, i, FieldBegin, FieldEnd); |
| } |
| } |
| assert(FoundPrevField && |
| "Unable to find a place for bitfield in struct layout"); |
| } |
| } |
| } else if (ExtraBits >= BitFieldSize) { |
| const llvm::Type *Ty = CGT.ConvertType(FD->getType()); |
| uint64_t TySize = CGT.getTargetData().getABITypeSizeInBits(Ty); |
| assert ( Cursor - CurrentFieldStart + BitFieldSize <= TySize |
| && "Incomplete layout. struct {char a; int b:10; int c:18;};"); |
| |
| // Reuse existing llvm field |
| ExtraBits = ExtraBits - BitFieldSize; |
| CGT.addFieldInfo(FD, FieldNo, Cursor - CurrentFieldStart, ExtraBits); |
| Cursor = Cursor + BitFieldSize; |
| ++FieldNo; |
| } else { |
| //ExtraBits are not enough to hold entire FD. |
| const llvm::Type *Ty = CGT.ConvertType(FD->getType()); |
| const llvm::Type *PrevTy = LLVMFields.back(); |
| uint64_t TySize = CGT.getTargetData().getABITypeSizeInBits(Ty); |
| assert (CGT.getTargetData().getABITypeSizeInBits(PrevTy) >= TySize |
| && "Unable to handle bit field"); |
| |
| // Previous field does not allow sharing of ExtraBits. Use new field. |
| // struct { char a; char b:5; char c:4; } where c is current FD. |
| Cursor += ExtraBits; |
| ExtraBits = 0; |
| addLLVMField(Ty, TySize, FD, 0, BitFieldSize); |
| } |
| } |