text: //=== MachOWriter.h - Target-independent Mach-O writer support --*- C++ -*-===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  // This file defines the MachOWriter class.
  //
  //===----------------------------------------------------------------------===//
  
  #ifndef MACHOWRITER_H
  #define MACHOWRITER_H
  
  #include "llvm/Constants.h"
  #include "llvm/DerivedTypes.h"
  #include "llvm/CodeGen/MachineFunctionPass.h"
  #include "llvm/CodeGen/MachineRelocation.h"
  #include "llvm/Target/TargetData.h"
  #include "llvm/Target/TargetMachine.h"
  #include "llvm/Target/TargetMachOWriterInfo.h"
  #include <map>
  
  namespace llvm {
    class GlobalVariable;
    class Mangler;
    class MachineCodeEmitter;
    class MachOCodeEmitter;
    class OutputBuffer;
  
    /// MachOSym - This struct contains information about each symbol that is
    /// added to logical symbol table for the module.  This is eventually
    /// turned into a real symbol table in the file.
    struct MachOSym {
      const GlobalValue *GV;    // The global value this corresponds to.
      std::string GVName;       // The mangled name of the global value.
      uint32_t    n_strx;       // index into the string table
      uint8_t     n_type;       // type flag
      uint8_t     n_sect;       // section number or NO_SECT
      int16_t     n_desc;       // see <mach-o/stab.h>
      uint64_t    n_value;      // value for this symbol (or stab offset)
      
      // Constants for the n_sect field
      // see <mach-o/nlist.h>
      enum { NO_SECT = 0 };   // symbol is not in any section
  
      // Constants for the n_type field
      // see <mach-o/nlist.h>
      enum { N_UNDF  = 0x0,  // undefined, n_sect == NO_SECT
             N_ABS   = 0x2,  // absolute, n_sect == NO_SECT
             N_SECT  = 0xe,  // defined in section number n_sect
             N_PBUD  = 0xc,  // prebound undefined (defined in a dylib)
             N_INDR  = 0xa   // indirect
      };
      // The following bits are OR'd into the types above. For example, a type
      // of 0x0f would be an external N_SECT symbol (0x0e | 0x01).
      enum { N_EXT  = 0x01,   // external symbol bit
             N_PEXT = 0x10    // private external symbol bit
      };
      
      // Constants for the n_desc field
      // see <mach-o/loader.h>
      enum { REFERENCE_FLAG_UNDEFINED_NON_LAZY          = 0,
             REFERENCE_FLAG_UNDEFINED_LAZY              = 1,
             REFERENCE_FLAG_DEFINED                     = 2,
             REFERENCE_FLAG_PRIVATE_DEFINED             = 3,
             REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY  = 4,
             REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY      = 5
      };
      enum { N_NO_DEAD_STRIP = 0x0020, // symbol is not to be dead stripped
             N_WEAK_REF      = 0x0040, // symbol is weak referenced
             N_WEAK_DEF      = 0x0080  // coalesced symbol is a weak definition
      };
      
      MachOSym(const GlobalValue *gv, std::string name, uint8_t sect,
               TargetMachine &TM);
    };
        
    /// MachOWriter - This class implements the common target-independent code for
    /// writing Mach-O files.  Targets should derive a class from this to
    /// parameterize the output format.
    ///
    class MachOWriter : public MachineFunctionPass {
      friend class MachOCodeEmitter;
    public:
      static char ID;
      MachineCodeEmitter &getMachineCodeEmitter() const {
        return *(MachineCodeEmitter*)MCE;
      }
  
      MachOWriter(std::ostream &O, TargetMachine &TM);
      virtual ~MachOWriter();
  
      virtual const char *getPassName() const {
        return "Mach-O Writer";
      }
  
      typedef std::vector<unsigned char> DataBuffer;
    protected:
      /// Output stream to send the resultant object file to.
      ///
      std::ostream &O;
  
      /// Target machine description.
      ///
      TargetMachine &TM;
  
      /// Mang - The object used to perform name mangling for this module.
      ///
      Mangler *Mang;
      
      /// MCE - The MachineCodeEmitter object that we are exposing to emit machine
      /// code for functions to the .o file.
      MachOCodeEmitter *MCE;
  
      /// is64Bit/isLittleEndian - This information is inferred from the target
      /// machine directly, indicating what header values and flags to set.
      bool is64Bit, isLittleEndian;
  
      /// doInitialization - Emit the file header and all of the global variables
      /// for the module to the Mach-O file.
      bool doInitialization(Module &M);
  
      bool runOnMachineFunction(MachineFunction &MF);
  
      /// doFinalization - Now that the module has been completely processed, emit
      /// the Mach-O file to 'O'.
      bool doFinalization(Module &M);
  
      /// MachOHeader - This struct contains the header information about a
      /// specific architecture type/subtype pair that is emitted to the file.
      struct MachOHeader {
        uint32_t  magic;      // mach magic number identifier
        uint32_t  filetype;   // type of file
        uint32_t  ncmds;      // number of load commands
        uint32_t  sizeofcmds; // the size of all the load commands
        uint32_t  flags;      // flags
        uint32_t  reserved;   // 64-bit only
        
        /// HeaderData - The actual data for the header which we are building
        /// up for emission to the file.
        DataBuffer HeaderData;
  
        // Constants for the filetype field
        // see <mach-o/loader.h> for additional info on the various types
        enum { MH_OBJECT     = 1, // relocatable object file
               MH_EXECUTE    = 2, // demand paged executable file
               MH_FVMLIB     = 3, // fixed VM shared library file
               MH_CORE       = 4, // core file
               MH_PRELOAD    = 5, // preloaded executable file
               MH_DYLIB      = 6, // dynamically bound shared library
               MH_DYLINKER   = 7, // dynamic link editor
               MH_BUNDLE     = 8, // dynamically bound bundle file
               MH_DYLIB_STUB = 9, // shared library stub for static linking only
               MH_DSYM       = 10 // companion file wiht only debug sections
        };
        
        // Constants for the flags field
        enum { MH_NOUNDEFS                = 1 << 0,
                  // the object file has no undefined references
               MH_INCRLINK                = 1 << 1,
                  // the object file is the output of an incremental link against
                  // a base file and cannot be link edited again
               MH_DYLDLINK                = 1 << 2,
                  // the object file is input for the dynamic linker and cannot be
                  // statically link edited again.
               MH_BINDATLOAD              = 1 << 3,
                  // the object file's undefined references are bound by the
                  // dynamic linker when loaded.
               MH_PREBOUND                = 1 << 4,
                  // the file has its dynamic undefined references prebound
               MH_SPLIT_SEGS              = 1 << 5,
                  // the file has its read-only and read-write segments split
                  // see <mach/shared_memory_server.h>
               MH_LAZY_INIT               = 1 << 6,
                  // the shared library init routine is to be run lazily via
                  // catching memory faults to its writable segments (obsolete)
               MH_TWOLEVEL                = 1 << 7,
                  // the image is using two-level namespace bindings
               MH_FORCE_FLAT              = 1 << 8,
                  // the executable is forcing all images to use flat namespace
                  // bindings.
               MH_NOMULTIDEFS             = 1 << 8,
                  // this umbrella guarantees no multiple definitions of symbols
                  // in its sub-images so the two-level namespace hints can
                  // always be used.
               MH_NOFIXPREBINDING         = 1 << 10,
                  // do not have dyld notify the prebidning agent about this
                  // executable.
               MH_PREBINDABLE             = 1 << 11,
                  // the binary is not prebound but can have its prebinding
                  // redone.  only used when MH_PREBOUND is not set.
               MH_ALLMODSBOUND            = 1 << 12,
                  // indicates that this binary binds to all two-level namespace
                  // modules of its dependent libraries.  Only used when
                  // MH_PREBINDABLE and MH_TWOLEVEL are both set.
               MH_SUBSECTIONS_VIA_SYMBOLS = 1 << 13,
                  // safe to divide up the sections into sub-sections via symbols
                  // for dead code stripping.
               MH_CANONICAL               = 1 << 14,
                  // the binary has been canonicalized via the unprebind operation
               MH_WEAK_DEFINES            = 1 << 15,
                  // the final linked image contains external weak symbols
               MH_BINDS_TO_WEAK           = 1 << 16,
                  // the final linked image uses weak symbols
               MH_ALLOW_STACK_EXECUTION   = 1 << 17
                  // When this bit is set, all stacks in the task will be given
                  // stack execution privilege.  Only used in MH_EXECUTE filetype
        };
  
        MachOHeader() : magic(0), filetype(0), ncmds(0), sizeofcmds(0), flags(0),
                        reserved(0) { }
        
        /// cmdSize - This routine returns the size of the MachOSection as written
        /// to disk, depending on whether the destination is a 64 bit Mach-O file.
        unsigned cmdSize(bool is64Bit) const {
          if (is64Bit)
            return 8 * sizeof(uint32_t);
          else
            return 7 * sizeof(uint32_t);
        }
  
        /// setMagic - This routine sets the appropriate value for the 'magic'
        /// field based on pointer size and endianness.
        void setMagic(bool isLittleEndian, bool is64Bit) {
          if (isLittleEndian)
            if (is64Bit) magic = 0xcffaedfe;
            else         magic = 0xcefaedfe;
          else
            if (is64Bit) magic = 0xfeedfacf;
            else         magic = 0xfeedface;
        }
      };
      
      /// Header - An instance of MachOHeader that we will update while we build
      /// the file, and then emit during finalization.
      MachOHeader Header;
      
      /// MachOSegment - This struct contains the necessary information to
      /// emit the load commands for each section in the file.
      struct MachOSegment {
        uint32_t    cmd;      // LC_SEGMENT or LC_SEGMENT_64
        uint32_t    cmdsize;  // Total size of this struct and section commands
        std::string segname;  // segment name
        uint64_t    vmaddr;   // address of this segment
        uint64_t    vmsize;   // size of this segment, may be larger than filesize
        uint64_t    fileoff;  // offset in file
        uint64_t    filesize; // amount to read from file
        uint32_t    maxprot;  // maximum VM protection
        uint32_t    initprot; // initial VM protection
        uint32_t    nsects;   // number of sections in this segment
        uint32_t    flags;    // flags
        
        // The following constants are getting pulled in by one of the
        // system headers, which creates a neat clash with the enum.
  #if !defined(VM_PROT_NONE)
  #define VM_PROT_NONE    0x00
  #endif
  #if !defined(VM_PROT_READ)
  #define VM_PROT_READ    0x01
  #endif
  #if !defined(VM_PROT_WRITE)
  #define VM_PROT_WRITE   0x02
  #endif
  #if !defined(VM_PROT_EXECUTE)
  #define VM_PROT_EXECUTE 0x04
  #endif
  #if !defined(VM_PROT_ALL)
  #define VM_PROT_ALL     0x07
  #endif
  
        // Constants for the vm protection fields
        // see <mach-o/vm_prot.h>
        enum { SEG_VM_PROT_NONE     = VM_PROT_NONE, 
               SEG_VM_PROT_READ     = VM_PROT_READ, // read permission
               SEG_VM_PROT_WRITE    = VM_PROT_WRITE, // write permission
               SEG_VM_PROT_EXECUTE  = VM_PROT_EXECUTE,
               SEG_VM_PROT_ALL      = VM_PROT_ALL
        };
        
        // Constants for the cmd field
        // see <mach-o/loader.h>
        enum { LC_SEGMENT    = 0x01,  // segment of this file to be mapped
               LC_SEGMENT_64 = 0x19   // 64-bit segment of this file to be mapped
        };
        
        /// cmdSize - This routine returns the size of the MachOSection as written
        /// to disk, depending on whether the destination is a 64 bit Mach-O file.
        unsigned cmdSize(bool is64Bit) const {
          if (is64Bit)
            return 6 * sizeof(uint32_t) + 4 * sizeof(uint64_t) + 16;
          else
            return 10 * sizeof(uint32_t) + 16;  // addresses only 32 bits
        }
  
        MachOSegment(const std::string &seg, bool is64Bit)
          : cmd(is64Bit ? LC_SEGMENT_64 : LC_SEGMENT), cmdsize(0), segname(seg),
            vmaddr(0), vmsize(0), fileoff(0), filesize(0), maxprot(VM_PROT_ALL),
            initprot(VM_PROT_ALL), nsects(0), flags(0) { }
      };
  
      /// MachOSection - This struct contains information about each section in a 
      /// particular segment that is emitted to the file.  This is eventually
      /// turned into the SectionCommand in the load command for a particlar
      /// segment.
      struct MachOSection { 
        std::string  sectname; // name of this section, 
        std::string  segname;  // segment this section goes in
        uint64_t  addr;        // memory address of this section
        uint64_t  size;        // size in bytes of this section
        uint32_t  offset;      // file offset of this section
        uint32_t  align;       // section alignment (power of 2)
        uint32_t  reloff;      // file offset of relocation entries
        uint32_t  nreloc;      // number of relocation entries
        uint32_t  flags;       // flags (section type and attributes)
        uint32_t  reserved1;   // reserved (for offset or index)
        uint32_t  reserved2;   // reserved (for count or sizeof)
        uint32_t  reserved3;   // reserved (64 bit only)
        
        /// A unique number for this section, which will be used to match symbols
        /// to the correct section.
        uint32_t Index;
        
        /// SectionData - The actual data for this section which we are building
        /// up for emission to the file.
        DataBuffer SectionData;
  
        /// RelocBuffer - A buffer to hold the mach-o relocations before we write
        /// them out at the appropriate location in the file.
        DataBuffer RelocBuffer;
        
        /// Relocations - The relocations that we have encountered so far in this 
        /// section that we will need to convert to MachORelocation entries when
        /// the file is written.
        std::vector<MachineRelocation> Relocations;
        
        // Constants for the section types (low 8 bits of flags field)
        // see <mach-o/loader.h>
        enum { S_REGULAR = 0,
                  // regular section
               S_ZEROFILL = 1,
                  // zero fill on demand section
               S_CSTRING_LITERALS = 2,
                  // section with only literal C strings
               S_4BYTE_LITERALS = 3,
                  // section with only 4 byte literals
               S_8BYTE_LITERALS = 4,
                  // section with only 8 byte literals
               S_LITERAL_POINTERS = 5, 
                  // section with only pointers to literals
               S_NON_LAZY_SYMBOL_POINTERS = 6,
                  // section with only non-lazy symbol pointers
               S_LAZY_SYMBOL_POINTERS = 7,
                  // section with only lazy symbol pointers
               S_SYMBOL_STUBS = 8,
                  // section with only symbol stubs
                  // byte size of stub in the reserved2 field
               S_MOD_INIT_FUNC_POINTERS = 9,
                  // section with only function pointers for initialization
               S_MOD_TERM_FUNC_POINTERS = 10,
                  // section with only function pointers for termination
               S_COALESCED = 11,
                  // section contains symbols that are coalesced
               S_GB_ZEROFILL = 12,
                  // zero fill on demand section (that can be larger than 4GB)
               S_INTERPOSING = 13,
                  // section with only pairs of function pointers for interposing
               S_16BYTE_LITERALS = 14
                  // section with only 16 byte literals
        };
        
        // Constants for the section flags (high 24 bits of flags field)
        // see <mach-o/loader.h>
        enum { S_ATTR_PURE_INSTRUCTIONS   = 1 << 31,
                  // section contains only true machine instructions
               S_ATTR_NO_TOC              = 1 << 30,
                  // section contains coalesced symbols that are not to be in a 
                  // ranlib table of contents
               S_ATTR_STRIP_STATIC_SYMS   = 1 << 29,
                  // ok to strip static symbols in this section in files with the
                  // MY_DYLDLINK flag
               S_ATTR_NO_DEAD_STRIP       = 1 << 28,
                  // no dead stripping
               S_ATTR_LIVE_SUPPORT        = 1 << 27,
                  // blocks are live if they reference live blocks
               S_ATTR_SELF_MODIFYING_CODE = 1 << 26,
                  // used with i386 code stubs written on by dyld
               S_ATTR_DEBUG               = 1 << 25,
                  // a debug section
               S_ATTR_SOME_INSTRUCTIONS   = 1 << 10,
                  // section contains some machine instructions
               S_ATTR_EXT_RELOC           = 1 << 9,
                  // section has external relocation entries
               S_ATTR_LOC_RELOC           = 1 << 8
                  // section has local relocation entries
        };
  
        /// cmdSize - This routine returns the size of the MachOSection as written
        /// to disk, depending on whether the destination is a 64 bit Mach-O file.
        unsigned cmdSize(bool is64Bit) const {
          if (is64Bit)
            return 7 * sizeof(uint32_t) + 2 * sizeof(uint64_t) + 32;
          else
            return 9 * sizeof(uint32_t) + 32;  // addresses only 32 bits
        }
  
        MachOSection(const std::string &seg, const std::string &sect)
          : sectname(sect), segname(seg), addr(0), size(0), offset(0), align(2),
            reloff(0), nreloc(0), flags(0), reserved1(0), reserved2(0),
            reserved3(0) { }
      };
  
    private:
  
      /// SectionList - This is the list of sections that we have emitted to the
      /// file.  Once the file has been completely built, the segment load command
      /// SectionCommands are constructed from this info.
      std::vector<MachOSection*> SectionList;
  
      /// SectionLookup - This is a mapping from section name to SectionList entry
      std::map<std::string, MachOSection*> SectionLookup;
      
      /// GVSection - This is a mapping from a GlobalValue to a MachOSection,
      /// to aid in emitting relocations.
      std::map<GlobalValue*, MachOSection*> GVSection;
  
      /// GVOffset - This is a mapping from a GlobalValue to an offset from the 
      /// start of the section in which the GV resides, to aid in emitting
      /// relocations.
      std::map<GlobalValue*, intptr_t> GVOffset;
  
      /// getSection - Return the section with the specified name, creating a new
      /// section if one does not already exist.
      MachOSection *getSection(const std::string &seg, const std::string &sect,
                               unsigned Flags = 0) {
        MachOSection *MOS = SectionLookup[seg+sect];
        if (MOS) return MOS;
  
        MOS = new MachOSection(seg, sect);
        SectionList.push_back(MOS);
        MOS->Index = SectionList.size();
        MOS->flags = MachOSection::S_REGULAR | Flags;
        SectionLookup[seg+sect] = MOS;
        return MOS;
      }
      MachOSection *getTextSection(bool isCode = true) {
        if (isCode)
          return getSection("__TEXT", "__text", 
                            MachOSection::S_ATTR_PURE_INSTRUCTIONS |
                            MachOSection::S_ATTR_SOME_INSTRUCTIONS);
        else
          return getSection("__TEXT", "__text");
      }
      MachOSection *getBSSSection() {
        return getSection("__DATA", "__bss", MachOSection::S_ZEROFILL);
      }
      MachOSection *getDataSection() {
        return getSection("__DATA", "__data");
      }
      MachOSection *getConstSection(Constant *C) {
        const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
        if (CVA && CVA->isCString())
          return getSection("__TEXT", "__cstring", 
                            MachOSection::S_CSTRING_LITERALS);
        
        const Type *Ty = C->getType();
        if (Ty->isPrimitiveType() || Ty->isInteger()) {
          unsigned Size = TM.getTargetData()->getABITypeSize(Ty);
          switch(Size) {
          default: break; // Fall through to __TEXT,__const
          case 4:
            return getSection("__TEXT", "__literal4",
                              MachOSection::S_4BYTE_LITERALS);
          case 8:
            return getSection("__TEXT", "__literal8",
                              MachOSection::S_8BYTE_LITERALS);
          case 16:
            return getSection("__TEXT", "__literal16",
                              MachOSection::S_16BYTE_LITERALS);
          }
        }
        return getSection("__TEXT", "__const");
      }
      MachOSection *getJumpTableSection() {
        if (TM.getRelocationModel() == Reloc::PIC_)
          return getTextSection(false);
        else
          return getSection("__TEXT", "__const");
      }
      
      /// MachOSymTab - This struct contains information about the offsets and 
      /// size of symbol table information.
      /// segment.
      struct MachOSymTab {
        uint32_t cmd;     // LC_SYMTAB
        uint32_t cmdsize; // sizeof( MachOSymTab )
        uint32_t symoff;  // symbol table offset
        uint32_t nsyms;   // number of symbol table entries
        uint32_t stroff;  // string table offset
        uint32_t strsize; // string table size in bytes
  
        // Constants for the cmd field
        // see <mach-o/loader.h>
        enum { LC_SYMTAB = 0x02  // link-edit stab symbol table info
        };
        
        MachOSymTab() : cmd(LC_SYMTAB), cmdsize(6 * sizeof(uint32_t)), symoff(0),
          nsyms(0), stroff(0), strsize(0) { }
      };
      
      /// MachOSymTab - This struct contains information about the offsets and 
      /// size of symbol table information.
      /// segment.
      struct MachODySymTab {
        uint32_t cmd;             // LC_DYSYMTAB
        uint32_t cmdsize;         // sizeof( MachODySymTab )
        uint32_t ilocalsym;       // index to local symbols
        uint32_t nlocalsym;       // number of local symbols
        uint32_t iextdefsym;      // index to externally defined symbols
        uint32_t nextdefsym;      // number of externally defined symbols
        uint32_t iundefsym;       // index to undefined symbols
        uint32_t nundefsym;       // number of undefined symbols
        uint32_t tocoff;          // file offset to table of contents
        uint32_t ntoc;            // number of entries in table of contents
        uint32_t modtaboff;       // file offset to module table
        uint32_t nmodtab;         // number of module table entries
        uint32_t extrefsymoff;    // offset to referenced symbol table
        uint32_t nextrefsyms;     // number of referenced symbol table entries
        uint32_t indirectsymoff;  // file offset to the indirect symbol table
        uint32_t nindirectsyms;   // number of indirect symbol table entries
        uint32_t extreloff;       // offset to external relocation entries
        uint32_t nextrel;         // number of external relocation entries
        uint32_t locreloff;       // offset to local relocation entries
        uint32_t nlocrel;         // number of local relocation entries
  
        // Constants for the cmd field
        // see <mach-o/loader.h>
        enum { LC_DYSYMTAB = 0x0B  // dynamic link-edit symbol table info
        };
        
        MachODySymTab() : cmd(LC_DYSYMTAB), cmdsize(20 * sizeof(uint32_t)),
          ilocalsym(0), nlocalsym(0), iextdefsym(0), nextdefsym(0),
          iundefsym(0), nundefsym(0), tocoff(0), ntoc(0), modtaboff(0),
          nmodtab(0), extrefsymoff(0), nextrefsyms(0), indirectsymoff(0),
          nindirectsyms(0), extreloff(0), nextrel(0), locreloff(0), nlocrel(0) { }
      };
      
      /// SymTab - The "stab" style symbol table information
      MachOSymTab   SymTab;     
      /// DySymTab - symbol table info for the dynamic link editor
      MachODySymTab DySymTab;
  
      struct MachOSymCmp {
        // FIXME: this does not appear to be sorting 'f' after 'F'
        bool operator()(const MachOSym &LHS, const MachOSym &RHS) {
          return LHS.GVName < RHS.GVName;
        }
      };
  
      /// PartitionByLocal - Simple boolean predicate that returns true if Sym is
      /// a local symbol rather than an external symbol.
      static bool PartitionByLocal(const MachOSym &Sym);
  
      /// PartitionByDefined - Simple boolean predicate that returns true if Sym 
      /// is defined in this module.
      static bool PartitionByDefined(const MachOSym &Sym);
  
    protected:
    
      /// SymbolTable - This is the list of symbols we have emitted to the file.
      /// This actually gets rearranged before emission to the file (to put the
      /// local symbols first in the list).
      std::vector<MachOSym> SymbolTable;
      
      /// SymT - A buffer to hold the symbol table before we write it out at the
      /// appropriate location in the file.
      DataBuffer SymT;
      
      /// StrT - A buffer to hold the string table before we write it out at the
      /// appropriate location in the file.
      DataBuffer StrT;
      
      /// PendingSyms - This is a list of externally defined symbols that we have
      /// been asked to emit, but have not seen a reference to.  When a reference
      /// is seen, the symbol will move from this list to the SymbolTable.
      std::vector<GlobalValue*> PendingGlobals;
      
      /// DynamicSymbolTable - This is just a vector of indices into
      /// SymbolTable to aid in emitting the DYSYMTAB load command.
      std::vector<unsigned> DynamicSymbolTable;
      
      static void InitMem(const Constant *C, void *Addr, intptr_t Offset,
                          const TargetData *TD, 
                          std::vector<MachineRelocation> &MRs);
  
    private:
      void AddSymbolToSection(MachOSection *MOS, GlobalVariable *GV);
      void EmitGlobal(GlobalVariable *GV);
      void EmitHeaderAndLoadCommands();
      void EmitSections();
      void BufferSymbolAndStringTable();
      void CalculateRelocations(MachOSection &MOS);
  
      MachineRelocation GetJTRelocation(unsigned Offset,
                                        MachineBasicBlock *MBB) const {
        return TM.getMachOWriterInfo()->GetJTRelocation(Offset, MBB);
      }
  
      /// GetTargetRelocation - Returns the number of relocations.
      unsigned GetTargetRelocation(MachineRelocation &MR,
                                   unsigned FromIdx,
                                   unsigned ToAddr,
                                   unsigned ToIndex,
                                   OutputBuffer &RelocOut,
                                   OutputBuffer &SecOut,
                                   bool Scattered,
                                   bool Extern) {
        return TM.getMachOWriterInfo()->GetTargetRelocation(MR, FromIdx, ToAddr,
                                                            ToIndex, RelocOut,
                                                            SecOut, Scattered,
                                                            Extern);
      }
    };
  }
  
  #endif
  