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 setLocalDifferenceRelocationType(unsigned Type)41 void setLocalDifferenceRelocationType(unsigned Type) { 42 LocalDifference_RIT = Type; 43 } 44 45 public: 46 virtual ~MCMachObjectTargetWriter(); 47 48 /// @name Lifetime Management 49 /// @{ 50 reset()51 virtual void reset() {}; 52 53 /// @} 54 55 /// @name Accessors 56 /// @{ 57 is64Bit()58 bool is64Bit() const { return Is64Bit; } useAggressiveSymbolFolding()59 bool useAggressiveSymbolFolding() const { return UseAggressiveSymbolFolding; } getCPUType()60 uint32_t getCPUType() const { return CPUType; } getCPUSubtype()61 uint32_t getCPUSubtype() const { return CPUSubtype; } getLocalDifferenceRelocationType()62 unsigned getLocalDifferenceRelocationType() const { 63 return LocalDifference_RIT; 64 } 65 66 /// @} 67 68 /// @name API 69 /// @{ 70 71 virtual void RecordRelocation(MachObjectWriter *Writer, 72 const MCAssembler &Asm, 73 const MCAsmLayout &Layout, 74 const MCFragment *Fragment, 75 const MCFixup &Fixup, 76 MCValue Target, 77 uint64_t &FixedValue) = 0; 78 79 /// @} 80 }; 81 82 class MachObjectWriter : public MCObjectWriter { 83 /// MachSymbolData - Helper struct for containing some precomputed information 84 /// on symbols. 85 struct MachSymbolData { 86 MCSymbolData *SymbolData; 87 uint64_t StringIndex; 88 uint8_t SectionIndex; 89 90 // Support lexicographic sorting. 91 bool operator<(const MachSymbolData &RHS) const; 92 }; 93 94 /// The target specific Mach-O writer instance. 95 llvm::OwningPtr<MCMachObjectTargetWriter> TargetObjectWriter; 96 97 /// @name Relocation Data 98 /// @{ 99 100 llvm::DenseMap<const MCSectionData*, 101 std::vector<object::macho::RelocationEntry> > Relocations; 102 llvm::DenseMap<const MCSectionData*, unsigned> IndirectSymBase; 103 104 /// @} 105 /// @name Symbol Table Data 106 /// @{ 107 108 SmallString<256> StringTable; 109 std::vector<MachSymbolData> LocalSymbolData; 110 std::vector<MachSymbolData> ExternalSymbolData; 111 std::vector<MachSymbolData> UndefinedSymbolData; 112 113 /// @} 114 115 public: MachObjectWriter(MCMachObjectTargetWriter * MOTW,raw_ostream & _OS,bool _IsLittleEndian)116 MachObjectWriter(MCMachObjectTargetWriter *MOTW, raw_ostream &_OS, 117 bool _IsLittleEndian) 118 : MCObjectWriter(_OS, _IsLittleEndian), TargetObjectWriter(MOTW) { 119 } 120 121 /// @name Lifetime management Methods 122 /// @{ 123 124 virtual void reset(); 125 126 /// @} 127 128 /// @name Utility Methods 129 /// @{ 130 131 bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind); 132 133 SectionAddrMap SectionAddress; 134 getSectionAddressMap()135 SectionAddrMap &getSectionAddressMap() { return SectionAddress; } 136 getSectionAddress(const MCSectionData * SD)137 uint64_t getSectionAddress(const MCSectionData* SD) const { 138 return SectionAddress.lookup(SD); 139 } 140 uint64_t getSymbolAddress(const MCSymbolData* SD, 141 const MCAsmLayout &Layout) const; 142 143 uint64_t getFragmentAddress(const MCFragment *Fragment, 144 const MCAsmLayout &Layout) const; 145 146 uint64_t getPaddingSize(const MCSectionData *SD, 147 const MCAsmLayout &Layout) const; 148 149 bool doesSymbolRequireExternRelocation(const MCSymbolData *SD); 150 151 /// @} 152 153 /// @name Target Writer Proxy Accessors 154 /// @{ 155 is64Bit()156 bool is64Bit() const { return TargetObjectWriter->is64Bit(); } isARM()157 bool isARM() const { 158 uint32_t CPUType = TargetObjectWriter->getCPUType() & 159 ~object::mach::CTFM_ArchMask; 160 return CPUType == object::mach::CTM_ARM; 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,object::macho::RelocationEntry & MRE)215 void addRelocation(const MCSectionData *SD, 216 object::macho::RelocationEntry &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, uint64_t &FixedValue); 236 237 void BindIndirectSymbols(MCAssembler &Asm); 238 239 /// ComputeSymbolTable - Compute the symbol table data 240 /// 241 /// \param StringTable [out] - The string table data. 242 void ComputeSymbolTable(MCAssembler &Asm, SmallString<256> &StringTable, 243 std::vector<MachSymbolData> &LocalSymbolData, 244 std::vector<MachSymbolData> &ExternalSymbolData, 245 std::vector<MachSymbolData> &UndefinedSymbolData); 246 247 void computeSectionAddresses(const MCAssembler &Asm, 248 const MCAsmLayout &Layout); 249 250 void markAbsoluteVariableSymbols(MCAssembler &Asm, 251 const MCAsmLayout &Layout); 252 void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout); 253 254 virtual bool IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, 255 const MCSymbolData &DataA, 256 const MCFragment &FB, 257 bool InSet, 258 bool IsPCRel) const; 259 260 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout); 261 }; 262 263 264 /// \brief Construct a new Mach-O writer instance. 265 /// 266 /// This routine takes ownership of the target writer subclass. 267 /// 268 /// \param MOTW - The target specific Mach-O writer subclass. 269 /// \param OS - The stream to write to. 270 /// \returns The constructed object writer. 271 MCObjectWriter *createMachObjectWriter(MCMachObjectTargetWriter *MOTW, 272 raw_ostream &OS, bool IsLittleEndian); 273 274 } // End llvm namespace 275 276 #endif 277