MCMachObjectWriter.h revision 85e910fe5cc308956edc0c71165b6714a1654df9
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 22namespace llvm { 23 24class MCSectionData; 25class MachObjectWriter; 26 27class 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 36protected: 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 45public: 46 virtual ~MCMachObjectTargetWriter(); 47 48 /// @name Lifetime Management 49 /// @{ 50 51 virtual void reset() {}; 52 53 /// @} 54 55 /// @name Accessors 56 /// @{ 57 58 bool is64Bit() const { return Is64Bit; } 59 bool useAggressiveSymbolFolding() const { return UseAggressiveSymbolFolding; } 60 uint32_t getCPUType() const { return CPUType; } 61 uint32_t getCPUSubtype() const { return CPUSubtype; } 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 82class 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 115public: 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; 134 135 SectionAddrMap &getSectionAddressMap() { return SectionAddress; } 136 137 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 /// @{ 155 156 bool is64Bit() const { return TargetObjectWriter->is64Bit(); } 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 // FIXME: We really need to improve the relocation validation. Basically, we 200 // want to implement a separate computation which evaluates the relocation 201 // entry as the linker would, and verifies that the resultant fixup value is 202 // exactly what the encoder wanted. This will catch several classes of 203 // problems: 204 // 205 // - Relocation entry bugs, the two algorithms are unlikely to have the same 206 // exact bug. 207 // 208 // - Relaxation issues, where we forget to relax something. 209 // 210 // - Input errors, where something cannot be correctly encoded. 'as' allows 211 // these through in many cases. 212 213 void addRelocation(const MCSectionData *SD, 214 object::macho::RelocationEntry &MRE) { 215 Relocations[SD].push_back(MRE); 216 } 217 218 void RecordScatteredRelocation(const MCAssembler &Asm, 219 const MCAsmLayout &Layout, 220 const MCFragment *Fragment, 221 const MCFixup &Fixup, MCValue Target, 222 unsigned Log2Size, 223 uint64_t &FixedValue); 224 225 void RecordTLVPRelocation(const MCAssembler &Asm, 226 const MCAsmLayout &Layout, 227 const MCFragment *Fragment, 228 const MCFixup &Fixup, MCValue Target, 229 uint64_t &FixedValue); 230 231 void RecordRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout, 232 const MCFragment *Fragment, const MCFixup &Fixup, 233 MCValue Target, uint64_t &FixedValue); 234 235 void BindIndirectSymbols(MCAssembler &Asm); 236 237 /// ComputeSymbolTable - Compute the symbol table data 238 /// 239 /// \param StringTable [out] - The string table data. 240 void ComputeSymbolTable(MCAssembler &Asm, SmallString<256> &StringTable, 241 std::vector<MachSymbolData> &LocalSymbolData, 242 std::vector<MachSymbolData> &ExternalSymbolData, 243 std::vector<MachSymbolData> &UndefinedSymbolData); 244 245 void computeSectionAddresses(const MCAssembler &Asm, 246 const MCAsmLayout &Layout); 247 248 void markAbsoluteVariableSymbols(MCAssembler &Asm, 249 const MCAsmLayout &Layout); 250 void ExecutePostLayoutBinding(MCAssembler &Asm, const MCAsmLayout &Layout); 251 252 virtual bool IsSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, 253 const MCSymbolData &DataA, 254 const MCFragment &FB, 255 bool InSet, 256 bool IsPCRel) const; 257 258 void WriteObject(MCAssembler &Asm, const MCAsmLayout &Layout); 259}; 260 261 262/// \brief Construct a new Mach-O writer instance. 263/// 264/// This routine takes ownership of the target writer subclass. 265/// 266/// \param MOTW - The target specific Mach-O writer subclass. 267/// \param OS - The stream to write to. 268/// \returns The constructed object writer. 269MCObjectWriter *createMachObjectWriter(MCMachObjectTargetWriter *MOTW, 270 raw_ostream &OS, bool IsLittleEndian); 271 272} // End llvm namespace 273 274#endif 275