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//===-- llvm/MC/MCMachObjectWriter.h - Mach Object Writer -------*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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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/SmallString.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/StringTableBuilder.h"
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#include "llvm/Support/DataTypes.h"
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#include "llvm/Support/MachO.h"
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class MachObjectWriter;
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class MCMachObjectTargetWriter {
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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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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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virtual ~MCMachObjectTargetWriter();
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/// \name Lifetime Management
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virtual void reset() {}
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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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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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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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// Support lexicographic sorting.
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bool operator<(const MachSymbolData &RHS) const;
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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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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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llvm::DenseMap<const MCSection *, std::vector<RelAndSymbol>> Relocations;
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llvm::DenseMap<const MCSection *, unsigned> IndirectSymBase;
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SectionAddrMap SectionAddress;
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/// \name Symbol Table Data
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StringTableBuilder StringTable;
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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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MachSymbolData *findSymbolData(const MCSymbol &Sym);
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MachObjectWriter(MCMachObjectTargetWriter *MOTW, raw_pwrite_stream &OS,
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: MCObjectWriter(OS, IsLittleEndian), TargetObjectWriter(MOTW) {}
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const MCSymbol &findAliasedSymbol(const MCSymbol &Sym) const;
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/// \name Lifetime management Methods
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void reset() override;
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/// \name Utility Methods
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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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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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/// \name Target Writer Proxy Accessors
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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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void writeHeader(unsigned NumLoadCommands, unsigned LoadCommandsSize,
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bool SubsectionsViaSymbols);
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/// Write a segment load command.
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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(unsigned NumSections, uint64_t VMSize,
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uint64_t SectionDataStartOffset,
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uint64_t SectionDataSize);
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void writeSection(const MCAssembler &Asm, const MCAsmLayout &Layout,
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const MCSection &Sec, uint64_t FileOffset,
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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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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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// - Relocation entry bugs, the two algorithms are unlikely to have the same
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// - Relaxation issues, where we forget to relax something.
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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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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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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, bool &IsPCRel,
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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 &SymA,
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const MCFragment &FB, bool InSet,
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bool IsPCRel) const override;
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void writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override;
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/// Construct a new Mach-O writer instance.
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/// This routine takes ownership of the target writer subclass.
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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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MCObjectWriter *createMachObjectWriter(MCMachObjectTargetWriter *MOTW,
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raw_pwrite_stream &OS,
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bool IsLittleEndian);
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} // End llvm namespace