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/SmallString.h" 15 #include "llvm/MC/MCExpr.h" 16 #include "llvm/MC/MCObjectWriter.h" 17 #include "llvm/Support/DataTypes.h" 18 #include "llvm/Support/MachO.h" 19 #include <vector> 20 21 namespace llvm { 22 23 class MCSectionData; 24 class MachObjectWriter; 25 26 class MCMachObjectTargetWriter { 27 const unsigned Is64Bit : 1; 28 const uint32_t CPUType; 29 const uint32_t CPUSubtype; 30 // FIXME: Remove this, we should just always use it once we no longer care 31 // about Darwin 'as' compatibility. 32 const unsigned UseAggressiveSymbolFolding : 1; 33 unsigned LocalDifference_RIT; 34 35 protected: 36 MCMachObjectTargetWriter(bool Is64Bit_, uint32_t CPUType_, 37 uint32_t CPUSubtype_, 38 bool UseAggressiveSymbolFolding_ = false); 39 setLocalDifferenceRelocationType(unsigned Type)40 void setLocalDifferenceRelocationType(unsigned Type) { 41 LocalDifference_RIT = Type; 42 } 43 44 public: 45 virtual ~MCMachObjectTargetWriter(); 46 47 /// @name Lifetime Management 48 /// @{ 49 reset()50 virtual void reset() {}; 51 52 /// @} 53 54 /// @name Accessors 55 /// @{ 56 is64Bit()57 bool is64Bit() const { return Is64Bit; } useAggressiveSymbolFolding()58 bool useAggressiveSymbolFolding() const { return UseAggressiveSymbolFolding; } getCPUType()59 uint32_t getCPUType() const { return CPUType; } getCPUSubtype()60 uint32_t getCPUSubtype() const { return CPUSubtype; } getLocalDifferenceRelocationType()61 unsigned getLocalDifferenceRelocationType() const { 62 return LocalDifference_RIT; 63 } 64 65 /// @} 66 67 /// @name API 68 /// @{ 69 70 virtual void RecordRelocation(MachObjectWriter *Writer, 71 const MCAssembler &Asm, 72 const MCAsmLayout &Layout, 73 const MCFragment *Fragment, 74 const MCFixup &Fixup, 75 MCValue Target, 76 uint64_t &FixedValue) = 0; 77 78 /// @} 79 }; 80 81 class MachObjectWriter : public MCObjectWriter { 82 /// MachSymbolData - Helper struct for containing some precomputed information 83 /// on symbols. 84 struct MachSymbolData { 85 MCSymbolData *SymbolData; 86 uint64_t StringIndex; 87 uint8_t SectionIndex; 88 89 // Support lexicographic sorting. 90 bool operator<(const MachSymbolData &RHS) const; 91 }; 92 93 /// The target specific Mach-O writer instance. 94 std::unique_ptr<MCMachObjectTargetWriter> TargetObjectWriter; 95 96 /// @name Relocation Data 97 /// @{ 98 99 llvm::DenseMap<const MCSectionData*, 100 std::vector<MachO::any_relocation_info> > Relocations; 101 llvm::DenseMap<const MCSectionData*, unsigned> IndirectSymBase; 102 103 /// @} 104 /// @name Symbol Table Data 105 /// @{ 106 107 SmallString<256> StringTable; 108 std::vector<MachSymbolData> LocalSymbolData; 109 std::vector<MachSymbolData> ExternalSymbolData; 110 std::vector<MachSymbolData> UndefinedSymbolData; 111 112 /// @} 113 114 MachSymbolData *findSymbolData(const MCSymbol &Sym); 115 116 public: MachObjectWriter(MCMachObjectTargetWriter * MOTW,raw_ostream & _OS,bool _IsLittleEndian)117 MachObjectWriter(MCMachObjectTargetWriter *MOTW, raw_ostream &_OS, 118 bool _IsLittleEndian) 119 : MCObjectWriter(_OS, _IsLittleEndian), TargetObjectWriter(MOTW) { 120 } 121 122 /// @name Lifetime management Methods 123 /// @{ 124 125 void reset() override; 126 127 /// @} 128 129 /// @name Utility Methods 130 /// @{ 131 132 bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind); 133 134 SectionAddrMap SectionAddress; 135 getSectionAddressMap()136 SectionAddrMap &getSectionAddressMap() { return SectionAddress; } 137 getSectionAddress(const MCSectionData * SD)138 uint64_t getSectionAddress(const MCSectionData* SD) const { 139 return SectionAddress.lookup(SD); 140 } 141 uint64_t getSymbolAddress(const MCSymbolData* SD, 142 const MCAsmLayout &Layout) const; 143 144 uint64_t getFragmentAddress(const MCFragment *Fragment, 145 const MCAsmLayout &Layout) const; 146 147 uint64_t getPaddingSize(const MCSectionData *SD, 148 const MCAsmLayout &Layout) const; 149 150 bool doesSymbolRequireExternRelocation(const MCSymbolData *SD); 151 152 /// @} 153 154 /// @name Target Writer Proxy Accessors 155 /// @{ 156 is64Bit()157 bool is64Bit() const { return TargetObjectWriter->is64Bit(); } isX86_64()158 bool isX86_64() const { 159 uint32_t CPUType = TargetObjectWriter->getCPUType(); 160 return CPUType == MachO::CPU_TYPE_X86_64; 161 } 162 163 /// @} 164 165 void WriteHeader(unsigned NumLoadCommands, unsigned LoadCommandsSize, 166 bool SubsectionsViaSymbols); 167 168 /// WriteSegmentLoadCommand - Write a segment load command. 169 /// 170 /// \param NumSections The number of sections in this segment. 171 /// \param SectionDataSize The total size of the sections. 172 void WriteSegmentLoadCommand(unsigned NumSections, 173 uint64_t VMSize, 174 uint64_t SectionDataStartOffset, 175 uint64_t SectionDataSize); 176 177 void WriteSection(const MCAssembler &Asm, const MCAsmLayout &Layout, 178 const MCSectionData &SD, uint64_t FileOffset, 179 uint64_t RelocationsStart, unsigned NumRelocations); 180 181 void WriteSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols, 182 uint32_t StringTableOffset, 183 uint32_t StringTableSize); 184 185 void WriteDysymtabLoadCommand(uint32_t FirstLocalSymbol, 186 uint32_t NumLocalSymbols, 187 uint32_t FirstExternalSymbol, 188 uint32_t NumExternalSymbols, 189 uint32_t FirstUndefinedSymbol, 190 uint32_t NumUndefinedSymbols, 191 uint32_t IndirectSymbolOffset, 192 uint32_t NumIndirectSymbols); 193 194 void WriteNlist(MachSymbolData &MSD, const MCAsmLayout &Layout); 195 196 void WriteLinkeditLoadCommand(uint32_t Type, uint32_t DataOffset, 197 uint32_t DataSize); 198 199 void WriteLinkerOptionsLoadCommand(const std::vector<std::string> &Options); 200 201 // FIXME: We really need to improve the relocation validation. Basically, we 202 // want to implement a separate computation which evaluates the relocation 203 // entry as the linker would, and verifies that the resultant fixup value is 204 // exactly what the encoder wanted. This will catch several classes of 205 // problems: 206 // 207 // - Relocation entry bugs, the two algorithms are unlikely to have the same 208 // exact bug. 209 // 210 // - Relaxation issues, where we forget to relax something. 211 // 212 // - Input errors, where something cannot be correctly encoded. 'as' allows 213 // these through in many cases. 214 addRelocation(const MCSectionData * SD,MachO::any_relocation_info & MRE)215 void addRelocation(const MCSectionData *SD, 216 MachO::any_relocation_info &MRE) { 217 Relocations[SD].push_back(MRE); 218 } 219 220 void RecordScatteredRelocation(const MCAssembler &Asm, 221 const MCAsmLayout &Layout, 222 const MCFragment *Fragment, 223 const MCFixup &Fixup, MCValue Target, 224 unsigned Log2Size, 225 uint64_t &FixedValue); 226 227 void RecordTLVPRelocation(const MCAssembler &Asm, 228 const MCAsmLayout &Layout, 229 const MCFragment *Fragment, 230 const MCFixup &Fixup, MCValue Target, 231 uint64_t &FixedValue); 232 233 void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout, 234 const MCFragment *Fragment, const MCFixup &Fixup, 235 MCValue Target, bool &IsPCRel, 236 uint64_t &FixedValue) override; 237 238 void BindIndirectSymbols(MCAssembler &Asm); 239 240 /// ComputeSymbolTable - Compute the symbol table data 241 /// 242 /// \param StringTable [out] - The string table data. 243 void ComputeSymbolTable(MCAssembler &Asm, SmallString<256> &StringTable, 244 std::vector<MachSymbolData> &LocalSymbolData, 245 std::vector<MachSymbolData> &ExternalSymbolData, 246 std::vector<MachSymbolData> &UndefinedSymbolData); 247 248 void computeSectionAddresses(const MCAssembler &Asm, 249 const MCAsmLayout &Layout); 250 251 void markAbsoluteVariableSymbols(MCAssembler &Asm, 252 const MCAsmLayout &Layout); 253 void ExecutePostLayoutBinding(MCAssembler &Asm, 254 const MCAsmLayout &Layout) override; 255 256 bool IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, 257 const MCSymbolData &DataA, 258 const MCFragment &FB, 259 bool InSet, 260 bool IsPCRel) const override; 261 262 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout) override; 263 }; 264 265 266 /// \brief Construct a new Mach-O writer instance. 267 /// 268 /// This routine takes ownership of the target writer subclass. 269 /// 270 /// \param MOTW - The target specific Mach-O writer subclass. 271 /// \param OS - The stream to write to. 272 /// \returns The constructed object writer. 273 MCObjectWriter *createMachObjectWriter(MCMachObjectTargetWriter *MOTW, 274 raw_ostream &OS, bool IsLittleEndian); 275 276 } // End llvm namespace 277 278 #endif 279