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//===- 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;

  void populateAddrSigSection(MCAssembler &Asm);

  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