MCELFObjectWriter.h revision 4ef61f2ad4ff509ee05c7051d359009511f81226 
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
47class MCELFObjectTargetWriter {
48  const uint8_t OSABI;
49  const uint16_t EMachine;
50  const unsigned HasRelocationAddend : 1;
51  const unsigned Is64Bit : 1;
52  const unsigned IsN64 : 1;
53
54protected:
55
56  MCELFObjectTargetWriter(bool Is64Bit_, uint8_t OSABI_,
57                          uint16_t EMachine_,  bool HasRelocationAddend,
58                          bool IsN64=false);
59
60public:
61  static uint8_t getOSABI(Triple::OSType OSType) {
62    switch (OSType) {
63      case Triple::FreeBSD:
64        return ELF::ELFOSABI_FREEBSD;
65      case Triple::Linux:
66        return ELF::ELFOSABI_LINUX;
67      default:
68        return ELF::ELFOSABI_NONE;
69    }
70  }
71
72  virtual ~MCELFObjectTargetWriter() {}
73
74  virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
75                                bool IsPCRel, bool IsRelocWithSymbol,
76                                int64_t Addend) const = 0;
77  virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
78                                         const MCValue &Target,
79                                         const MCFragment &F,
80                                         const MCFixup &Fixup,
81                                         bool IsPCRel) const;
82  virtual const MCSymbol *undefinedExplicitRelSym(const MCValue &Target,
83                                                  const MCFixup &Fixup,
84                                                  bool IsPCRel) const;
85
86  virtual void sortRelocs(const MCAssembler &Asm,
87                          std::vector<ELFRelocationEntry> &Relocs);
88
89  /// @name Accessors
90  /// @{
91  uint8_t getOSABI() const { return OSABI; }
92  uint16_t getEMachine() const { return EMachine; }
93  bool hasRelocationAddend() const { return HasRelocationAddend; }
94  bool is64Bit() const { return Is64Bit; }
95  bool isN64() const { return IsN64; }
96  /// @}
97
98  // Instead of changing everyone's API we pack the N64 Type fields
99  // into the existing 32 bit data unsigned.
100#define R_TYPE_SHIFT 0
101#define R_TYPE_MASK 0xffffff00
102#define R_TYPE2_SHIFT 8
103#define R_TYPE2_MASK 0xffff00ff
104#define R_TYPE3_SHIFT 16
105#define R_TYPE3_MASK 0xff00ffff
106#define R_SSYM_SHIFT 24
107#define R_SSYM_MASK 0x00ffffff
108
109  // N64 relocation type accessors
110  unsigned getRType(uint32_t Type) const {
111    return (unsigned)((Type >> R_TYPE_SHIFT) & 0xff);
112  }
113  unsigned getRType2(uint32_t Type) const {
114    return (unsigned)((Type >> R_TYPE2_SHIFT) & 0xff);
115  }
116  unsigned getRType3(uint32_t Type) const {
117    return (unsigned)((Type >> R_TYPE3_SHIFT) & 0xff);
118  }
119  unsigned getRSsym(uint32_t Type) const {
120    return (unsigned)((Type >> R_SSYM_SHIFT) & 0xff);
121  }
122
123  // N64 relocation type setting
124  unsigned setRType(unsigned Value, unsigned Type) const {
125    return ((Type & R_TYPE_MASK) | ((Value & 0xff) << R_TYPE_SHIFT));
126  }
127  unsigned setRType2(unsigned Value, unsigned Type) const {
128    return (Type & R_TYPE2_MASK) | ((Value & 0xff) << R_TYPE2_SHIFT);
129  }
130  unsigned setRType3(unsigned Value, unsigned Type) const {
131    return (Type & R_TYPE3_MASK) | ((Value & 0xff) << R_TYPE3_SHIFT);
132  }
133  unsigned setRSsym(unsigned Value, unsigned Type) const {
134    return (Type & R_SSYM_MASK) | ((Value & 0xff) << R_SSYM_SHIFT);
135  }
136};
137
138/// \brief Construct a new ELF writer instance.
139///
140/// \param MOTW - The target specific ELF writer subclass.
141/// \param OS - The stream to write to.
142/// \returns The constructed object writer.
143MCObjectWriter *createELFObjectWriter(MCELFObjectTargetWriter *MOTW,
144                                      raw_ostream &OS, bool IsLittleEndian);
145} // End llvm namespace
146
147#endif
148