MCELFObjectWriter.h revision aa71428378c1cb491ca60041d8ba7aa110bc963d 
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  const unsigned IsN64 : 1;
58
59protected:
60
61  MCELFObjectTargetWriter(bool Is64Bit_, uint8_t OSABI_,
62                          uint16_t EMachine_,  bool HasRelocationAddend,
63                          bool IsN64=false);
64
65public:
66  static uint8_t getOSABI(Triple::OSType OSType) {
67    switch (OSType) {
68      case Triple::FreeBSD:
69        return ELF::ELFOSABI_FREEBSD;
70      case Triple::Linux:
71        return ELF::ELFOSABI_LINUX;
72      default:
73        return ELF::ELFOSABI_NONE;
74    }
75  }
76
77  virtual ~MCELFObjectTargetWriter() {}
78
79  virtual unsigned GetRelocType(const MCValue &Target, const MCFixup &Fixup,
80                                bool IsPCRel, bool IsRelocWithSymbol,
81                                int64_t Addend) const = 0;
82  virtual unsigned getEFlags() const;
83  virtual const MCSymbol *ExplicitRelSym(const MCAssembler &Asm,
84                                         const MCValue &Target,
85                                         const MCFragment &F,
86                                         const MCFixup &Fixup,
87                                         bool IsPCRel) const;
88  virtual const MCSymbol *undefinedExplicitRelSym(const MCValue &Target,
89                                                  const MCFixup &Fixup,
90                                                  bool IsPCRel) const;
91  virtual void adjustFixupOffset(const MCFixup &Fixup,
92                                 uint64_t &RelocOffset);
93
94  virtual void sortRelocs(const MCAssembler &Asm,
95                          std::vector<ELFRelocationEntry> &Relocs);
96
97  /// @name Accessors
98  /// @{
99  uint8_t getOSABI() { return OSABI; }
100  uint16_t getEMachine() { return EMachine; }
101  bool hasRelocationAddend() { return HasRelocationAddend; }
102  bool is64Bit() const { return Is64Bit; }
103  bool isN64() const { return IsN64; }
104  /// @}
105
106  // Instead of changing everyone's API we pack the N64 Type fields
107  // into the existing 32 bit data unsigned.
108#define R_TYPE_SHIFT 0
109#define R_TYPE_MASK 0xffffff00
110#define R_TYPE2_SHIFT 8
111#define R_TYPE2_MASK 0xffff00ff
112#define R_TYPE3_SHIFT 16
113#define R_TYPE3_MASK 0xff00ffff
114#define R_SSYM_SHIFT 24
115#define R_SSYM_MASK 0x00ffffff
116
117  // N64 relocation type accessors
118  unsigned getRType(uint32_t Type) const {
119    return (unsigned)((Type >> R_TYPE_SHIFT) & 0xff);
120  }
121  unsigned getRType2(uint32_t Type) const {
122    return (unsigned)((Type >> R_TYPE2_SHIFT) & 0xff);
123  }
124  unsigned getRType3(uint32_t Type) const {
125    return (unsigned)((Type >> R_TYPE3_SHIFT) & 0xff);
126  }
127  unsigned getRSsym(uint32_t Type) const {
128    return (unsigned)((Type >> R_SSYM_SHIFT) & 0xff);
129  }
130
131  // N64 relocation type setting
132  unsigned setRType(unsigned Value, unsigned Type) const {
133    return ((Type & R_TYPE_MASK) | ((Value & 0xff) << R_TYPE_SHIFT));
134  }
135  unsigned setRType2(unsigned Value, unsigned Type) const {
136    return (Type & R_TYPE2_MASK) | ((Value & 0xff) << R_TYPE2_SHIFT);
137  }
138  unsigned setRType3(unsigned Value, unsigned Type) const {
139    return (Type & R_TYPE3_MASK) | ((Value & 0xff) << R_TYPE3_SHIFT);
140  }
141  unsigned setRSsym(unsigned Value, unsigned Type) const {
142    return (Type & R_SSYM_MASK) | ((Value & 0xff) << R_SSYM_SHIFT);
143  }
144};
145
146/// \brief Construct a new ELF writer instance.
147///
148/// \param MOTW - The target specific ELF writer subclass.
149/// \param OS - The stream to write to.
150/// \returns The constructed object writer.
151MCObjectWriter *createELFObjectWriter(MCELFObjectTargetWriter *MOTW,
152                                      raw_ostream &OS, bool IsLittleEndian);
153} // End llvm namespace
154
155#endif
156