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//===--- CGRecordLayoutBuilder.h - Record builder helper --------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This is a helper class used to build CGRecordLayout objects and LLVM types.
//
//===----------------------------------------------------------------------===//
#ifndef CLANG_CODEGEN_CGRECORDLAYOUTBUILDER_H
#define CLANG_CODEGEN_CGRECORDLAYOUTBUILDER_H
#include "llvm/ADT/SmallVector.h"
#include "llvm/Support/DataTypes.h"
#include <vector>
namespace llvm {
class Type;
}
namespace clang {
class FieldDecl;
class RecordDecl;
namespace CodeGen {
class CGRecordLayout;
class CodeGenTypes;
class CGRecordLayoutBuilder {
CodeGenTypes &Types;
/// StructPacking - Will be 0 if this struct is not packed. If it is packed,
/// it will have the packing alignment in bits.
///
unsigned StructPacking;
/// AlignmentAsLLVMStruct - Will contain the maximum alignment of all the
/// LLVM types.
unsigned AlignmentAsLLVMStruct;
/// 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;
/// FieldTypes - Holds the LLVM types that the struct is created from.
std::vector<const llvm::Type *> FieldTypes;
/// FieldInfo - Holds size and offset information about a field.
/// FIXME: I think we can get rid of this.
struct FieldInfo {
FieldInfo(uint64_t OffsetInBytes, uint64_t SizeInBytes)
: OffsetInBytes(OffsetInBytes), SizeInBytes(SizeInBytes) { }
const uint64_t OffsetInBytes;
const uint64_t SizeInBytes;
};
llvm::SmallVector<FieldInfo, 16> FieldInfos;
/// LLVMFieldInfo - Holds a field and its corresponding LLVM field number.
typedef std::pair<const FieldDecl *, unsigned> LLVMFieldInfo;
llvm::SmallVector<LLVMFieldInfo, 16> LLVMFields;
/// LLVMBitFieldInfo - Holds location and size information about a bit field.
struct LLVMBitFieldInfo {
LLVMBitFieldInfo(const FieldDecl *FD, unsigned Start, unsigned Size)
: FD(FD), Start(Start), Size(Size) { }
const FieldDecl *FD;
unsigned Start;
unsigned Size;
};
llvm::SmallVector<LLVMBitFieldInfo, 16> LLVMBitFields;
CGRecordLayoutBuilder(CodeGenTypes &Types)
: Types(Types), StructPacking(0), AlignmentAsLLVMStruct(1)
, BitsAvailableInLastField(0) { }
/// Layout - Will layout a RecordDecl.
void Layout(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);
/// 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 size and type.
void AppendField(uint64_t FieldOffsetInBytes, uint64_t FieldSizeInBytes,
const llvm::Type *FieldTy);
/// AppendPadding - Appends enough padding bytes so that the total struct
/// size matches the alignment of the passed in type.
void AppendPadding(uint64_t FieldOffsetInBytes, const llvm::Type *FieldTy);
/// AppendPadding - Appends enough padding bytes so that the total
/// struct size is a multiple of the field alignment.
void AppendPadding(uint64_t FieldOffsetInBytes, unsigned FieldAlignment);
/// AppendBytes - Append a given number of bytes to the record.
void AppendBytes(uint64_t NumBytes);
/// getNextFieldOffsetInBytes - returns where the next field offset is.
uint64_t getNextFieldOffsetInBytes() const;
unsigned getTypeAlignment(const llvm::Type *Ty) const;
uint64_t getTypeSizeInBytes(const llvm::Type *Ty) const;
public:
/// ComputeLayout - Return the right record layout for a given record decl.
static CGRecordLayout *ComputeLayout(CodeGenTypes &Types,
const RecordDecl *D);
};
} // end namespace CodeGen
} // end namespace clang
#endif
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