Moved from include/llvm/CodeGen to lib/CodeGen.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@34027 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 624 insertions, 0 deletions

diff --git a/lib/CodeGen/MachOWriter.h b/lib/CodeGen/MachOWriter.h
new file mode 100644
index 0000000000..a26945874a
--- /dev/null
+++ b/lib/CodeGen/MachOWriter.h
@@ -0,0 +1,624 @@
+//=== MachOWriter.h - Target-independent Mach-O writer support --*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file was developed by Nate Begeman and 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"
+
+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:
+    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()->getTypeSize(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<MachOSym> PendingSyms;
+    
+    /// 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) {
+      return TM.getMachOWriterInfo()->GetTargetRelocation(MR, FromIdx, ToAddr,
+                                                          ToIndex, RelocOut,
+                                                          SecOut, Scattered);
+    }
+  };
+}
+
+#endif