Coverage Report

Created: 2019-02-21 13:17

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/include/llvm/MC/MCMachObjectWriter.h
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//===- llvm/MC/MCMachObjectWriter.h - Mach Object Writer --------*- C++ -*-===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_MC_MCMACHOBJECTWRITER_H
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#define LLVM_MC_MCMACHOBJECTWRITER_H
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#include "llvm/ADT/DenseMap.h"
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#include "llvm/ADT/StringRef.h"
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#include "llvm/BinaryFormat/MachO.h"
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#include "llvm/MC/MCExpr.h"
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#include "llvm/MC/MCObjectWriter.h"
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#include "llvm/MC/MCSection.h"
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#include "llvm/MC/StringTableBuilder.h"
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#include <cstdint>
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#include <memory>
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#include <string>
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#include <vector>
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namespace llvm {
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class MachObjectWriter;
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class MCMachObjectTargetWriter : public MCObjectTargetWriter {
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  const unsigned Is64Bit : 1;
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  const uint32_t CPUType;
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  const uint32_t CPUSubtype;
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  unsigned LocalDifference_RIT;
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protected:
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  MCMachObjectTargetWriter(bool Is64Bit_, uint32_t CPUType_,
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                           uint32_t CPUSubtype_);
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  void setLocalDifferenceRelocationType(unsigned Type) {
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    LocalDifference_RIT = Type;
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  }
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public:
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  virtual ~MCMachObjectTargetWriter();
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  virtual Triple::ObjectFormatType getFormat() const { return Triple::MachO; }
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  static bool classof(const MCObjectTargetWriter *W) {
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    return W->getFormat() == Triple::MachO;
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  }
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  /// \name Lifetime Management
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  /// @{
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  virtual void reset() {}
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  /// @}
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  /// \name Accessors
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  /// @{
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  bool is64Bit() const { return Is64Bit; }
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  uint32_t getCPUType() const { return CPUType; }
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  uint32_t getCPUSubtype() const { return CPUSubtype; }
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  unsigned getLocalDifferenceRelocationType() const {
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    return LocalDifference_RIT;
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  }
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  /// @}
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  /// \name API
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  /// @{
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  virtual void recordRelocation(MachObjectWriter *Writer, MCAssembler &Asm,
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                                const MCAsmLayout &Layout,
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                                const MCFragment *Fragment,
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                                const MCFixup &Fixup, MCValue Target,
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                                uint64_t &FixedValue) = 0;
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  /// @}
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};
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class MachObjectWriter : public MCObjectWriter {
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  /// Helper struct for containing some precomputed information on symbols.
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  struct MachSymbolData {
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    const MCSymbol *Symbol;
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    uint64_t StringIndex;
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    uint8_t SectionIndex;
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    // Support lexicographic sorting.
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    bool operator<(const MachSymbolData &RHS) const;
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  };
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  /// The target specific Mach-O writer instance.
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  std::unique_ptr<MCMachObjectTargetWriter> TargetObjectWriter;
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  /// \name Relocation Data
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  /// @{
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  struct RelAndSymbol {
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    const MCSymbol *Sym;
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    MachO::any_relocation_info MRE;
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    RelAndSymbol(const MCSymbol *Sym, const MachO::any_relocation_info &MRE)
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        : Sym(Sym), MRE(MRE) {}
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  };
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  DenseMap<const MCSection *, std::vector<RelAndSymbol>> Relocations;
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  DenseMap<const MCSection *, unsigned> IndirectSymBase;
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  SectionAddrMap SectionAddress;
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  /// @}
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  /// \name Symbol Table Data
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  /// @{
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  StringTableBuilder StringTable{StringTableBuilder::MachO};
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  std::vector<MachSymbolData> LocalSymbolData;
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  std::vector<MachSymbolData> ExternalSymbolData;
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  std::vector<MachSymbolData> UndefinedSymbolData;
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  /// @}
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  MachSymbolData *findSymbolData(const MCSymbol &Sym);
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  void writeWithPadding(StringRef Str, uint64_t Size);
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public:
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  MachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW,
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                   raw_pwrite_stream &OS, bool IsLittleEndian)
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      : TargetObjectWriter(std::move(MOTW)),
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        W(OS, IsLittleEndian ? support::little : support::big) {}
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  support::endian::Writer W;
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  const MCSymbol &findAliasedSymbol(const MCSymbol &Sym) const;
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  /// \name Lifetime management Methods
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  /// @{
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  void reset() override;
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  /// @}
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  /// \name Utility Methods
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  /// @{
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  bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind);
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  SectionAddrMap &getSectionAddressMap() { return SectionAddress; }
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  uint64_t getSectionAddress(const MCSection *Sec) const {
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    return SectionAddress.lookup(Sec);
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  }
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  uint64_t getSymbolAddress(const MCSymbol &S, const MCAsmLayout &Layout) const;
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  uint64_t getFragmentAddress(const MCFragment *Fragment,
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                              const MCAsmLayout &Layout) const;
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  uint64_t getPaddingSize(const MCSection *SD, const MCAsmLayout &Layout) const;
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  bool doesSymbolRequireExternRelocation(const MCSymbol &S);
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  /// @}
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  /// \name Target Writer Proxy Accessors
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  /// @{
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  bool is64Bit() const { return TargetObjectWriter->is64Bit(); }
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  bool isX86_64() const {
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    uint32_t CPUType = TargetObjectWriter->getCPUType();
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    return CPUType == MachO::CPU_TYPE_X86_64;
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  }
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  /// @}
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  void writeHeader(MachO::HeaderFileType Type, unsigned NumLoadCommands,
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                   unsigned LoadCommandsSize, bool SubsectionsViaSymbols);
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  /// Write a segment load command.
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  ///
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  /// \param NumSections The number of sections in this segment.
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  /// \param SectionDataSize The total size of the sections.
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  void writeSegmentLoadCommand(StringRef Name, unsigned NumSections,
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                               uint64_t VMAddr, uint64_t VMSize,
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                               uint64_t SectionDataStartOffset,
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                               uint64_t SectionDataSize, uint32_t MaxProt,
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                               uint32_t InitProt);
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  void writeSection(const MCAsmLayout &Layout, const MCSection &Sec,
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                    uint64_t VMAddr, uint64_t FileOffset, unsigned Flags,
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                    uint64_t RelocationsStart, unsigned NumRelocations);
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  void writeSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols,
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                              uint32_t StringTableOffset,
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                              uint32_t StringTableSize);
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  void writeDysymtabLoadCommand(
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      uint32_t FirstLocalSymbol, uint32_t NumLocalSymbols,
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      uint32_t FirstExternalSymbol, uint32_t NumExternalSymbols,
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      uint32_t FirstUndefinedSymbol, uint32_t NumUndefinedSymbols,
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      uint32_t IndirectSymbolOffset, uint32_t NumIndirectSymbols);
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  void writeNlist(MachSymbolData &MSD, const MCAsmLayout &Layout);
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  void writeLinkeditLoadCommand(uint32_t Type, uint32_t DataOffset,
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                                uint32_t DataSize);
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  void writeLinkerOptionsLoadCommand(const std::vector<std::string> &Options);
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  // FIXME: We really need to improve the relocation validation. Basically, we
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  // want to implement a separate computation which evaluates the relocation
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  // entry as the linker would, and verifies that the resultant fixup value is
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  // exactly what the encoder wanted. This will catch several classes of
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  // problems:
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  //
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  //  - Relocation entry bugs, the two algorithms are unlikely to have the same
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  //    exact bug.
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  //
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  //  - Relaxation issues, where we forget to relax something.
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  //
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  //  - Input errors, where something cannot be correctly encoded. 'as' allows
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  //    these through in many cases.
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  // Add a relocation to be output in the object file. At the time this is
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  // called, the symbol indexes are not know, so if the relocation refers
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  // to a symbol it should be passed as \p RelSymbol so that it can be updated
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  // afterwards. If the relocation doesn't refer to a symbol, nullptr should be
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  // used.
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  void addRelocation(const MCSymbol *RelSymbol, const MCSection *Sec,
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                     MachO::any_relocation_info &MRE) {
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    RelAndSymbol P(RelSymbol, MRE);
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    Relocations[Sec].push_back(P);
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  }
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  void recordScatteredRelocation(const MCAssembler &Asm,
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                                 const MCAsmLayout &Layout,
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                                 const MCFragment *Fragment,
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                                 const MCFixup &Fixup, MCValue Target,
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                                 unsigned Log2Size, uint64_t &FixedValue);
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  void recordTLVPRelocation(const MCAssembler &Asm, const MCAsmLayout &Layout,
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                            const MCFragment *Fragment, const MCFixup &Fixup,
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                            MCValue Target, uint64_t &FixedValue);
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  void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout,
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                        const MCFragment *Fragment, const MCFixup &Fixup,
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                        MCValue Target, uint64_t &FixedValue) override;
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  void bindIndirectSymbols(MCAssembler &Asm);
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  /// Compute the symbol table data.
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  void computeSymbolTable(MCAssembler &Asm,
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                          std::vector<MachSymbolData> &LocalSymbolData,
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                          std::vector<MachSymbolData> &ExternalSymbolData,
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                          std::vector<MachSymbolData> &UndefinedSymbolData);
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  void computeSectionAddresses(const MCAssembler &Asm,
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                               const MCAsmLayout &Layout);
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  void executePostLayoutBinding(MCAssembler &Asm,
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                                const MCAsmLayout &Layout) override;
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  bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
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                                              const MCSymbol &A,
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                                              const MCSymbol &B,
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                                              bool InSet) const override;
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  bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm,
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                                              const MCSymbol &SymA,
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                                              const MCFragment &FB, bool InSet,
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                                              bool IsPCRel) const override;
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  uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
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};
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/// Construct a new Mach-O writer instance.
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///
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/// This routine takes ownership of the target writer subclass.
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///
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/// \param MOTW - The target specific Mach-O writer subclass.
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/// \param OS - The stream to write to.
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/// \returns The constructed object writer.
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std::unique_ptr<MCObjectWriter>
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createMachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW,
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                       raw_pwrite_stream &OS, bool IsLittleEndian);
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} // end namespace llvm
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#endif // LLVM_MC_MCMACHOBJECTWRITER_H