| //===- llvm/MC/MCMachObjectWriter.h - Mach Object Writer --------*- C++ -*-===// |
| // |
| // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
| // See https://llvm.org/LICENSE.txt for license information. |
| // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_MC_MCMACHOBJECTWRITER_H |
| #define LLVM_MC_MCMACHOBJECTWRITER_H |
| |
| #include "llvm/ADT/DenseMap.h" |
| #include "llvm/ADT/StringRef.h" |
| #include "llvm/BinaryFormat/MachO.h" |
| #include "llvm/MC/MCExpr.h" |
| #include "llvm/MC/MCObjectWriter.h" |
| #include "llvm/MC/MCSection.h" |
| #include "llvm/MC/StringTableBuilder.h" |
| #include "llvm/Support/EndianStream.h" |
| #include <cstdint> |
| #include <memory> |
| #include <string> |
| #include <vector> |
| |
| namespace llvm { |
| |
| class MachObjectWriter; |
| |
| class MCMachObjectTargetWriter : public MCObjectTargetWriter { |
| const unsigned Is64Bit : 1; |
| const uint32_t CPUType; |
| protected: |
| uint32_t CPUSubtype; |
| public: |
| unsigned LocalDifference_RIT; |
| |
| protected: |
| MCMachObjectTargetWriter(bool Is64Bit_, uint32_t CPUType_, |
| uint32_t CPUSubtype_); |
| |
| void setLocalDifferenceRelocationType(unsigned Type) { |
| LocalDifference_RIT = Type; |
| } |
| |
| public: |
| virtual ~MCMachObjectTargetWriter(); |
| |
| Triple::ObjectFormatType getFormat() const override { return Triple::MachO; } |
| static bool classof(const MCObjectTargetWriter *W) { |
| return W->getFormat() == Triple::MachO; |
| } |
| |
| /// \name Lifetime Management |
| /// @{ |
| |
| virtual void reset() {} |
| |
| /// @} |
| |
| /// \name Accessors |
| /// @{ |
| |
| bool is64Bit() const { return Is64Bit; } |
| uint32_t getCPUType() const { return CPUType; } |
| uint32_t getCPUSubtype() const { return CPUSubtype; } |
| unsigned getLocalDifferenceRelocationType() const { |
| return LocalDifference_RIT; |
| } |
| |
| /// @} |
| |
| /// \name API |
| /// @{ |
| |
| virtual void recordRelocation(MachObjectWriter *Writer, MCAssembler &Asm, |
| const MCAsmLayout &Layout, |
| const MCFragment *Fragment, |
| const MCFixup &Fixup, MCValue Target, |
| uint64_t &FixedValue) = 0; |
| |
| /// @} |
| }; |
| |
| class MachObjectWriter : public MCObjectWriter { |
| /// Helper struct for containing some precomputed information on symbols. |
| struct MachSymbolData { |
| const MCSymbol *Symbol; |
| uint64_t StringIndex; |
| uint8_t SectionIndex; |
| |
| // Support lexicographic sorting. |
| bool operator<(const MachSymbolData &RHS) const; |
| }; |
| |
| /// The target specific Mach-O writer instance. |
| std::unique_ptr<MCMachObjectTargetWriter> TargetObjectWriter; |
| |
| /// \name Relocation Data |
| /// @{ |
| |
| struct RelAndSymbol { |
| const MCSymbol *Sym; |
| MachO::any_relocation_info MRE; |
| RelAndSymbol(const MCSymbol *Sym, const MachO::any_relocation_info &MRE) |
| : Sym(Sym), MRE(MRE) {} |
| }; |
| |
| DenseMap<const MCSection *, std::vector<RelAndSymbol>> Relocations; |
| DenseMap<const MCSection *, unsigned> IndirectSymBase; |
| |
| SectionAddrMap SectionAddress; |
| |
| /// @} |
| /// \name Symbol Table Data |
| /// @{ |
| |
| StringTableBuilder StringTable; |
| std::vector<MachSymbolData> LocalSymbolData; |
| std::vector<MachSymbolData> ExternalSymbolData; |
| std::vector<MachSymbolData> UndefinedSymbolData; |
| |
| /// @} |
| |
| MachSymbolData *findSymbolData(const MCSymbol &Sym); |
| |
| void writeWithPadding(StringRef Str, uint64_t Size); |
| |
| public: |
| MachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW, |
| raw_pwrite_stream &OS, bool IsLittleEndian) |
| : TargetObjectWriter(std::move(MOTW)), |
| StringTable(TargetObjectWriter->is64Bit() ? StringTableBuilder::MachO64 |
| : StringTableBuilder::MachO), |
| W(OS, IsLittleEndian ? support::little : support::big) {} |
| |
| support::endian::Writer W; |
| |
| const MCSymbol &findAliasedSymbol(const MCSymbol &Sym) const; |
| |
| /// \name Lifetime management Methods |
| /// @{ |
| |
| void reset() override; |
| |
| /// @} |
| |
| /// \name Utility Methods |
| /// @{ |
| |
| bool isFixupKindPCRel(const MCAssembler &Asm, unsigned Kind); |
| |
| SectionAddrMap &getSectionAddressMap() { return SectionAddress; } |
| |
| uint64_t getSectionAddress(const MCSection *Sec) const { |
| return SectionAddress.lookup(Sec); |
| } |
| uint64_t getSymbolAddress(const MCSymbol &S, const MCAsmLayout &Layout) const; |
| |
| uint64_t getFragmentAddress(const MCFragment *Fragment, |
| const MCAsmLayout &Layout) const; |
| |
| uint64_t getPaddingSize(const MCSection *SD, const MCAsmLayout &Layout) const; |
| |
| bool doesSymbolRequireExternRelocation(const MCSymbol &S); |
| |
| /// @} |
| |
| /// \name Target Writer Proxy Accessors |
| /// @{ |
| |
| bool is64Bit() const { return TargetObjectWriter->is64Bit(); } |
| bool isX86_64() const { |
| uint32_t CPUType = TargetObjectWriter->getCPUType(); |
| return CPUType == MachO::CPU_TYPE_X86_64; |
| } |
| |
| /// @} |
| |
| void writeHeader(MachO::HeaderFileType Type, unsigned NumLoadCommands, |
| unsigned LoadCommandsSize, bool SubsectionsViaSymbols); |
| |
| /// Write a segment load command. |
| /// |
| /// \param NumSections The number of sections in this segment. |
| /// \param SectionDataSize The total size of the sections. |
| void writeSegmentLoadCommand(StringRef Name, unsigned NumSections, |
| uint64_t VMAddr, uint64_t VMSize, |
| uint64_t SectionDataStartOffset, |
| uint64_t SectionDataSize, uint32_t MaxProt, |
| uint32_t InitProt); |
| |
| void writeSection(const MCAsmLayout &Layout, const MCSection &Sec, |
| uint64_t VMAddr, uint64_t FileOffset, unsigned Flags, |
| uint64_t RelocationsStart, unsigned NumRelocations); |
| |
| void writeSymtabLoadCommand(uint32_t SymbolOffset, uint32_t NumSymbols, |
| uint32_t StringTableOffset, |
| uint32_t StringTableSize); |
| |
| void writeDysymtabLoadCommand( |
| uint32_t FirstLocalSymbol, uint32_t NumLocalSymbols, |
| uint32_t FirstExternalSymbol, uint32_t NumExternalSymbols, |
| uint32_t FirstUndefinedSymbol, uint32_t NumUndefinedSymbols, |
| uint32_t IndirectSymbolOffset, uint32_t NumIndirectSymbols); |
| |
| void writeNlist(MachSymbolData &MSD, const MCAsmLayout &Layout); |
| |
| void writeLinkeditLoadCommand(uint32_t Type, uint32_t DataOffset, |
| uint32_t DataSize); |
| |
| void writeLinkerOptionsLoadCommand(const std::vector<std::string> &Options); |
| |
| // FIXME: We really need to improve the relocation validation. Basically, we |
| // want to implement a separate computation which evaluates the relocation |
| // entry as the linker would, and verifies that the resultant fixup value is |
| // exactly what the encoder wanted. This will catch several classes of |
| // problems: |
| // |
| // - Relocation entry bugs, the two algorithms are unlikely to have the same |
| // exact bug. |
| // |
| // - Relaxation issues, where we forget to relax something. |
| // |
| // - Input errors, where something cannot be correctly encoded. 'as' allows |
| // these through in many cases. |
| |
| // Add a relocation to be output in the object file. At the time this is |
| // called, the symbol indexes are not know, so if the relocation refers |
| // to a symbol it should be passed as \p RelSymbol so that it can be updated |
| // afterwards. If the relocation doesn't refer to a symbol, nullptr should be |
| // used. |
| void addRelocation(const MCSymbol *RelSymbol, const MCSection *Sec, |
| MachO::any_relocation_info &MRE) { |
| RelAndSymbol P(RelSymbol, MRE); |
| Relocations[Sec].push_back(P); |
| } |
| |
| void recordRelocation(MCAssembler &Asm, const MCAsmLayout &Layout, |
| const MCFragment *Fragment, const MCFixup &Fixup, |
| MCValue Target, uint64_t &FixedValue) override; |
| |
| void bindIndirectSymbols(MCAssembler &Asm); |
| |
| /// Compute the symbol table data. |
| void computeSymbolTable(MCAssembler &Asm, |
| std::vector<MachSymbolData> &LocalSymbolData, |
| std::vector<MachSymbolData> &ExternalSymbolData, |
| std::vector<MachSymbolData> &UndefinedSymbolData); |
| |
| void computeSectionAddresses(const MCAssembler &Asm, |
| const MCAsmLayout &Layout); |
| |
| void executePostLayoutBinding(MCAssembler &Asm, |
| const MCAsmLayout &Layout) override; |
| |
| bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, |
| const MCSymbol &A, |
| const MCSymbol &B, |
| bool InSet) const override; |
| |
| bool isSymbolRefDifferenceFullyResolvedImpl(const MCAssembler &Asm, |
| const MCSymbol &SymA, |
| const MCFragment &FB, bool InSet, |
| bool IsPCRel) const override; |
| |
| uint64_t writeObject(MCAssembler &Asm, const MCAsmLayout &Layout) override; |
| }; |
| |
| /// Construct a new Mach-O writer instance. |
| /// |
| /// This routine takes ownership of the target writer subclass. |
| /// |
| /// \param MOTW - The target specific Mach-O writer subclass. |
| /// \param OS - The stream to write to. |
| /// \returns The constructed object writer. |
| std::unique_ptr<MCObjectWriter> |
| createMachObjectWriter(std::unique_ptr<MCMachObjectTargetWriter> MOTW, |
| raw_pwrite_stream &OS, bool IsLittleEndian); |
| |
| } // end namespace llvm |
| |
| #endif // LLVM_MC_MCMACHOBJECTWRITER_H |