1 //===-- llvm/MC/MCObjectWriter.h - Object File Writer Interface -*- 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_MCOBJECTWRITER_H 11 #define LLVM_MC_MCOBJECTWRITER_H 12 13 #include "llvm/ADT/Triple.h" 14 #include "llvm/Support/raw_ostream.h" 15 #include "llvm/Support/DataTypes.h" 16 #include <cassert> 17 18 namespace llvm { 19 class MCAsmLayout; 20 class MCAssembler; 21 class MCFixup; 22 class MCFragment; 23 class MCSymbol; 24 class MCSymbolData; 25 class MCSymbolRefExpr; 26 class MCValue; 27 class raw_ostream; 28 29 /// MCObjectWriter - Defines the object file and target independent interfaces 30 /// used by the assembler backend to write native file format object files. 31 /// 32 /// The object writer contains a few callbacks used by the assembler to allow 33 /// the object writer to modify the assembler data structures at appropriate 34 /// points. Once assembly is complete, the object writer is given the 35 /// MCAssembler instance, which contains all the symbol and section data which 36 /// should be emitted as part of WriteObject(). 37 /// 38 /// The object writer also contains a number of helper methods for writing 39 /// binary data to the output stream. 40 class MCObjectWriter { 41 MCObjectWriter(const MCObjectWriter &); // DO NOT IMPLEMENT 42 void operator=(const MCObjectWriter &); // DO NOT IMPLEMENT 43 44 protected: 45 raw_ostream &OS; 46 47 unsigned IsLittleEndian : 1; 48 49 protected: // Can only create subclasses. 50 MCObjectWriter(raw_ostream &_OS, bool _IsLittleEndian) 51 : OS(_OS), IsLittleEndian(_IsLittleEndian) {} 52 53 public: 54 virtual ~MCObjectWriter(); 55 56 bool isLittleEndian() const { return IsLittleEndian; } 57 58 raw_ostream &getStream() { return OS; } 59 60 /// @name High-Level API 61 /// @{ 62 63 /// Perform any late binding of symbols (for example, to assign symbol indices 64 /// for use when generating relocations). 65 /// 66 /// This routine is called by the assembler after layout and relaxation is 67 /// complete. 68 virtual void ExecutePostLayoutBinding(MCAssembler &Asm, 69 const MCAsmLayout &Layout) = 0; 70 71 /// Record a relocation entry. 72 /// 73 /// This routine is called by the assembler after layout and relaxation, and 74 /// post layout binding. The implementation is responsible for storing 75 /// information about the relocation so that it can be emitted during 76 /// WriteObject(). 77 virtual void RecordRelocation(const MCAssembler &Asm, 78 const MCAsmLayout &Layout, 79 const MCFragment *Fragment, 80 const MCFixup &Fixup, MCValue Target, 81 uint64_t &FixedValue) = 0; 82 83 /// \brief Check whether the difference (A - B) between two symbol 84 /// references is fully resolved. 85 /// 86 /// Clients are not required to answer precisely and may conservatively return 87 /// false, even when a difference is fully resolved. 88 bool 89 IsSymbolRefDifferenceFullyResolved(const MCAssembler &Asm, 90 const MCSymbolRefExpr *A, 91 const MCSymbolRefExpr *B, 92 bool InSet) const; 93 94 virtual bool 95 IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, 96 const MCSymbolData &DataA, 97 const MCFragment &FB, 98 bool InSet, 99 bool IsPCRel) const; 100 101 102 /// Write the object file. 103 /// 104 /// This routine is called by the assembler after layout and relaxation is 105 /// complete, fixups have been evaluated and applied, and relocations 106 /// generated. 107 virtual void WriteObject(MCAssembler &Asm, 108 const MCAsmLayout &Layout) = 0; 109 110 /// @} 111 /// @name Binary Output 112 /// @{ 113 114 void Write8(uint8_t Value) { 115 OS << char(Value); 116 } 117 118 void WriteLE16(uint16_t Value) { 119 Write8(uint8_t(Value >> 0)); 120 Write8(uint8_t(Value >> 8)); 121 } 122 123 void WriteLE32(uint32_t Value) { 124 WriteLE16(uint16_t(Value >> 0)); 125 WriteLE16(uint16_t(Value >> 16)); 126 } 127 128 void WriteLE64(uint64_t Value) { 129 WriteLE32(uint32_t(Value >> 0)); 130 WriteLE32(uint32_t(Value >> 32)); 131 } 132 133 void WriteBE16(uint16_t Value) { 134 Write8(uint8_t(Value >> 8)); 135 Write8(uint8_t(Value >> 0)); 136 } 137 138 void WriteBE32(uint32_t Value) { 139 WriteBE16(uint16_t(Value >> 16)); 140 WriteBE16(uint16_t(Value >> 0)); 141 } 142 143 void WriteBE64(uint64_t Value) { 144 WriteBE32(uint32_t(Value >> 32)); 145 WriteBE32(uint32_t(Value >> 0)); 146 } 147 148 void Write16(uint16_t Value) { 149 if (IsLittleEndian) 150 WriteLE16(Value); 151 else 152 WriteBE16(Value); 153 } 154 155 void Write32(uint32_t Value) { 156 if (IsLittleEndian) 157 WriteLE32(Value); 158 else 159 WriteBE32(Value); 160 } 161 162 void Write64(uint64_t Value) { 163 if (IsLittleEndian) 164 WriteLE64(Value); 165 else 166 WriteBE64(Value); 167 } 168 169 void WriteZeros(unsigned N) { 170 const char Zeros[16] = { 0 }; 171 172 for (unsigned i = 0, e = N / 16; i != e; ++i) 173 OS << StringRef(Zeros, 16); 174 175 OS << StringRef(Zeros, N % 16); 176 } 177 178 void WriteBytes(StringRef Str, unsigned ZeroFillSize = 0) { 179 assert((ZeroFillSize == 0 || Str.size () <= ZeroFillSize) && 180 "data size greater than fill size, unexpected large write will occur"); 181 OS << Str; 182 if (ZeroFillSize) 183 WriteZeros(ZeroFillSize - Str.size()); 184 } 185 186 /// @} 187 188 /// Utility function to encode a SLEB128 value. 189 static void EncodeSLEB128(int64_t Value, raw_ostream &OS); 190 /// Utility function to encode a ULEB128 value. 191 static void EncodeULEB128(uint64_t Value, raw_ostream &OS); 192 }; 193 194 MCObjectWriter *createWinCOFFObjectWriter(raw_ostream &OS, bool is64Bit); 195 196 } // End llvm namespace 197 198 #endif 199
