MCELFObjectWriter.h revision f1d0f7781e766df878bec4e7977fa3204374f394 
1//===-- llvm/MC/MCELFObjectWriter.h - ELF Object Writer ---------*- C++ -*-===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9
10#ifndef LLVM_MC_MCELFOBJECTWRITER_H
11#define LLVM_MC_MCELFOBJECTWRITER_H
12
13#include "llvm/ADT/Triple.h"
14#include "llvm/Support/DataTypes.h"
15#include "llvm/Support/ELF.h"
16#include <vector>
17
18namespace llvm {
19class MCAssembler;
20class MCFixup;
21class MCFragment;
22class MCObjectWriter;
23class MCSymbol;
24class MCValue;
25
26/// @name Relocation Data
27/// @{
28
29struct ELFRelocationEntry {
30  // Make these big enough for both 32-bit and 64-bit
31  uint64_t r_offset;
32  int Index;
33  unsigned Type;
34  const MCSymbol *Symbol;
35  uint64_t r_addend;
36  const MCFixup *Fixup;
37
38  ELFRelocationEntry()
39    : r_offset(0), Index(0), Type(0), Symbol(0), r_addend(0), Fixup(0) {}
40
41  ELFRelocationEntry(uint64_t RelocOffset, int Idx, unsigned RelType,
42                     const MCSymbol *Sym, uint64_t Addend, const MCFixup &Fixup)
43    : r_offset(RelocOffset), Index(Idx), Type(RelType), Symbol(Sym),
44      r_addend(Addend), Fixup(&Fixup) {}
45
46  // Support lexicographic sorting.
47  bool operator<(const ELFRelocationEntry &RE) const {
48    return RE.r_offset < r_offset;
49  }
50};
51
52class MCELFObjectTargetWriter {
53  const uint8_t OSABI;
54  const uint16_t EMachine;
55  const unsigned HasRelocationAddend : 1;
56  const unsigned Is64Bit : 1;
57
58protected:
59
60  MCELFObjectTargetWriter(bool Is64Bit_, uint8_t OSABI_,
61                          uint16_t EMachine_,  bool HasRelocationAddend_);
62
63public:
64  static uint8_t getOSABI(Triple::OSType OSType) {
65    switch (OSType) {
66      case Triple::FreeBSD:
67        return ELF::ELFOSABI_FREEBSD;
68      case Triple::Linux:
69        return ELF::ELFOSABI_LINUX;
70      default:
71        return ELF::ELFOSABI_NONE;
72    }
73  }
74
75  virtual ~MCELFObjectTargetWriter() {}
76
77  virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
78                                bool IsPCRel, bool IsRelocWithSymbol,
79                                int64_t Addend) const = 0;
80  virtual unsigned getEFlags() const;
81  virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
82                                         const MCValue &Target,
83                                         const MCFragment &F,
84                                         const MCFixup &Fixup,
85                                         bool IsPCRel) const;
86  virtual void adjustFixupOffset(const MCFixup &Fixup,
87                                 uint64_t &RelocOffset);
88
89  virtual void sortRelocs(const MCAssembler &Asm,
90                          std::vector<ELFRelocationEntry> &Relocs);
91
92  /// @name Accessors
93  /// @{
94  uint8_t getOSABI() { return OSABI; }
95  uint16_t getEMachine() { return EMachine; }
96  bool hasRelocationAddend() { return HasRelocationAddend; }
97  bool is64Bit() const { return Is64Bit; }
98  /// @}
99};
100
101/// \brief Construct a new ELF writer instance.
102///
103/// \param MOTW - The target specific ELF writer subclass.
104/// \param OS - The stream to write to.
105/// \returns The constructed object writer.
106MCObjectWriter *createELFObjectWriter(MCELFObjectTargetWriter *MOTW,
107                                      raw_ostream &OS, bool IsLittleEndian);
108} // End llvm namespace
109
110#endif
111