| //=== 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; | 
 |   class raw_ostream; | 
 |  | 
 |   /// 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(raw_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. | 
 |     /// | 
 |     raw_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 §) | 
 |         : 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 §, | 
 |                              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()->getTypePaddedSize(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 |