1 //===-- llvm/MC/MCMachObjectWriter.h - Mach 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_MCMACHOBJECTWRITER_H 11 #define LLVM_MC_MCMACHOBJECTWRITER_H 12 13 #include "llvm/ADT/DenseMap.h" 14 #include "llvm/ADT/OwningPtr.h" 15 #include "llvm/ADT/SmallString.h" 16 #include "llvm/MC/MCExpr.h" 17 #include "llvm/MC/MCObjectWriter.h" 18 #include "llvm/Object/MachOFormat.h" 19 #include "llvm/Support/DataTypes.h" 20 #include <vector> 21 22 namespace llvm { 23 24 class MCSectionData; 25 class MachObjectWriter; 26 27 class MCMachObjectTargetWriter { 28 const unsigned Is64Bit : 1; 29 const uint32_t CPUType; 30 const uint32_t CPUSubtype; 31 // FIXME: Remove this, we should just always use it once we no longer care 32 // about Darwin 'as' compatibility. 33 const unsigned UseAggressiveSymbolFolding : 1; 34 unsigned LocalDifference_RIT; 35 36 protected: 37 MCMachObjectTargetWriter(bool Is64Bit_, uint32_t CPUType_, 38 uint32_t CPUSubtype_, 39 bool UseAggressiveSymbolFolding_ = false); 40 41 void setLocalDifferenceRelocationType(unsigned Type) { 42 LocalDifference_RIT = Type; 43 } 44 45 public: 46 virtual ~MCMachObjectTargetWriter(); 47 48 /// @name Accessors 49 /// @{ 50 51 bool is64Bit() const { return Is64Bit; } 52 bool useAggressiveSymbolFolding() const { return UseAggressiveSymbolFolding; } 53 uint32_t getCPUType() const { return CPUType; } 54 uint32_t getCPUSubtype() const { return CPUSubtype; } 55 unsigned getLocalDifferenceRelocationType() const { 56 return LocalDifference_RIT; 57 } 58 59 /// @} 60 61 /// @name API 62 /// @{ 63 64 virtual void RecordRelocation(MachObjectWriter *Writer, 65 const MCAssembler &Asm, 66 const MCAsmLayout &Layout, 67 const MCFragment *Fragment, 68 const MCFixup &Fixup, 69 MCValue Target, 70 uint64_t &FixedValue) = 0; 71 72 /// @} 73 }; 74 75 class MachObjectWriter : public MCObjectWriter { 76 /// MachSymbolData - Helper struct for containing some precomputed information 77 /// on symbols. 78 struct MachSymbolData { 79 MCSymbolData *SymbolData; 80 uint64_t StringIndex; 81 uint8_t SectionIndex; 82 83 // Support lexicographic sorting. 84 bool operator<(const MachSymbolData &RHS) const; 85 }; 86 87 /// The target specific Mach-O writer instance. 88 llvm::OwningPtr<MCMachObjectTargetWriter> TargetObjectWriter; 89 90 /// @name Relocation Data 91 /// @{ 92 93 llvm::DenseMap<const MCSectionData*, 94 std::vector<object::macho::RelocationEntry> > Relocations; 95 llvm::DenseMap<const MCSectionData*, unsigned> IndirectSymBase; 96 97 /// @} 98 /// @name Symbol Table Data 99 /// @{ 100 101 SmallString<256> StringTable; 102 std::vector<MachSymbolData> LocalSymbolData; 103 std::vector<MachSymbolData> ExternalSymbolData; 104 std::vector<MachSymbolData> UndefinedSymbolData; 105 106 /// @} 107 108 public: 109 MachObjectWriter(MCMachObjectTargetWriter *MOTW, raw_ostream &_OS, 110 bool _IsLittleEndian) 111 : MCObjectWriter(_OS, _IsLittleEndian), TargetObjectWriter(MOTW) { 112 } 113 114 /// @name Utility Methods 115 /// @{ 116 117 bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind); 118 119 SectionAddrMap SectionAddress; 120 121 SectionAddrMap &getSectionAddressMap() { return SectionAddress; } 122 123 uint64_t getSectionAddress(const MCSectionData* SD) const { 124 return SectionAddress.lookup(SD); 125 } 126 uint64_t getSymbolAddress(const MCSymbolData* SD, 127 const MCAsmLayout &Layout) const; 128 129 uint64_t getFragmentAddress(const MCFragment *Fragment, 130 const MCAsmLayout &Layout) const; 131 132 uint64_t getPaddingSize(const MCSectionData *SD, 133 const MCAsmLayout &Layout) const; 134 135 bool doesSymbolRequireExternRelocation(const MCSymbolData *SD); 136 137 /// @} 138 139 /// @name Target Writer Proxy Accessors 140 /// @{ 141 142 bool is64Bit() const { return TargetObjectWriter->is64Bit(); } 143 bool isARM() const { 144 uint32_t CPUType = TargetObjectWriter->getCPUType() & 145 ~object::mach::CTFM_ArchMask; 146 return CPUType == object::mach::CTM_ARM; 147 } 148 149 /// @} 150 151 void WriteHeader(unsigned NumLoadCommands, unsigned LoadCommandsSize, 152 bool SubsectionsViaSymbols); 153 154 /// WriteSegmentLoadCommand - Write a segment load command. 155 /// 156 /// \arg NumSections - The number of sections in this segment. 157 /// \arg SectionDataSize - The total size of the sections. 158 void WriteSegmentLoadCommand(unsigned NumSections, 159 uint64_t VMSize, 160 uint64_t SectionDataStartOffset, 161 uint64_t SectionDataSize); 162 163 void WriteSection(const MCAssembler &Asm, const MCAsmLayout &Layout, 164 const MCSectionData &SD, uint64_t FileOffset, 165 uint64_t RelocationsStart, unsigned NumRelocations); 166 167 void WriteSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols, 168 uint32_t StringTableOffset, 169 uint32_t StringTableSize); 170 171 void WriteDysymtabLoadCommand(uint32_t FirstLocalSymbol, 172 uint32_t NumLocalSymbols, 173 uint32_t FirstExternalSymbol, 174 uint32_t NumExternalSymbols, 175 uint32_t FirstUndefinedSymbol, 176 uint32_t NumUndefinedSymbols, 177 uint32_t IndirectSymbolOffset, 178 uint32_t NumIndirectSymbols); 179 180 void WriteNlist(MachSymbolData &MSD, const MCAsmLayout &Layout); 181 182 // FIXME: We really need to improve the relocation validation. Basically, we 183 // want to implement a separate computation which evaluates the relocation 184 // entry as the linker would, and verifies that the resultant fixup value is 185 // exactly what the encoder wanted. This will catch several classes of 186 // problems: 187 // 188 // - Relocation entry bugs, the two algorithms are unlikely to have the same 189 // exact bug. 190 // 191 // - Relaxation issues, where we forget to relax something. 192 // 193 // - Input errors, where something cannot be correctly encoded. 'as' allows 194 // these through in many cases. 195 196 void addRelocation(const MCSectionData *SD, 197 object::macho::RelocationEntry &MRE) { 198 Relocations[SD].push_back(MRE); 199 } 200 201 void RecordScatteredRelocation(const MCAssembler &Asm, 202 const MCAsmLayout &Layout, 203 const MCFragment *Fragment, 204 const MCFixup &Fixup, MCValue Target, 205 unsigned Log2Size, 206 uint64_t &FixedValue); 207 208 void RecordTLVPRelocation(const MCAssembler &Asm, 209 const MCAsmLayout &Layout, 210 const MCFragment *Fragment, 211 const MCFixup &Fixup, MCValue Target, 212 uint64_t &FixedValue); 213 214 void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout, 215 const MCFragment *Fragment, const MCFixup &Fixup, 216 MCValue Target, uint64_t &FixedValue); 217 218 void BindIndirectSymbols(MCAssembler &Asm); 219 220 /// ComputeSymbolTable - Compute the symbol table data 221 /// 222 /// \param StringTable [out] - The string table data. 223 /// \param StringIndexMap [out] - Map from symbol names to offsets in the 224 /// string table. 225 void ComputeSymbolTable(MCAssembler &Asm, SmallString<256> &StringTable, 226 std::vector<MachSymbolData> &LocalSymbolData, 227 std::vector<MachSymbolData> &ExternalSymbolData, 228 std::vector<MachSymbolData> &UndefinedSymbolData); 229 230 void computeSectionAddresses(const MCAssembler &Asm, 231 const MCAsmLayout &Layout); 232 233 void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout); 234 235 virtual bool IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, 236 const MCSymbolData &DataA, 237 const MCFragment &FB, 238 bool InSet, 239 bool IsPCRel) const; 240 241 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout); 242 }; 243 244 245 /// \brief Construct a new Mach-O writer instance. 246 /// 247 /// This routine takes ownership of the target writer subclass. 248 /// 249 /// \param MOTW - The target specific Mach-O writer subclass. 250 /// \param OS - The stream to write to. 251 /// \returns The constructed object writer. 252 MCObjectWriter *createMachObjectWriter(MCMachObjectTargetWriter *MOTW, 253 raw_ostream &OS, bool IsLittleEndian); 254 255 } // End llvm namespace 256 257 #endif 258
