lib/CodeGen/MachOWriter.h

   1 //=== MachOWriter.h - Target-independent Mach-O writer support --*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file was developed by Nate Begeman and is distributed under the
   6 // University of Illinois Open Source License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file defines the MachOWriter class.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #ifndef MACHOWRITER_H
  15 #define MACHOWRITER_H
  16
  17 #include "llvm/Constants.h"
  18 #include "llvm/DerivedTypes.h"
  19 #include "llvm/CodeGen/MachineFunctionPass.h"
  20 #include "llvm/CodeGen/MachineRelocation.h"
  21 #include "llvm/Target/TargetData.h"
  22 #include "llvm/Target/TargetMachine.h"
  23 #include "llvm/Target/TargetMachOWriterInfo.h"
  24
  25 namespace llvm {
  26   class GlobalVariable;
  27   class Mangler;
  28   class MachineCodeEmitter;
  29   class MachOCodeEmitter;
  30   class OutputBuffer;
  31
  32   /// MachOSym - This struct contains information about each symbol that is
  33   /// added to logical symbol table for the module.  This is eventually
  34   /// turned into a real symbol table in the file.
  35   struct MachOSym {
  36     const GlobalValue *GV;    // The global value this corresponds to.
  37     std::string GVName;       // The mangled name of the global value.
  38     uint32_t    n_strx;       // index into the string table
  39     uint8_t     n_type;       // type flag
  40     uint8_t     n_sect;       // section number or NO_SECT
  41     int16_t     n_desc;       // see <mach-o/stab.h>
  42     uint64_t    n_value;      // value for this symbol (or stab offset)
  43
  44     // Constants for the n_sect field
  45     // see <mach-o/nlist.h>
  46     enum { NO_SECT = 0 };   // symbol is not in any section
  47
  48     // Constants for the n_type field
  49     // see <mach-o/nlist.h>
  50     enum { N_UNDF  = 0x0,  // undefined, n_sect == NO_SECT
  51            N_ABS   = 0x2,  // absolute, n_sect == NO_SECT
  52            N_SECT  = 0xe,  // defined in section number n_sect
  53            N_PBUD  = 0xc,  // prebound undefined (defined in a dylib)
  54            N_INDR  = 0xa   // indirect
  55     };
  56     // The following bits are OR'd into the types above. For example, a type
  57     // of 0x0f would be an external N_SECT symbol (0x0e | 0x01).
  58     enum { N_EXT  = 0x01,   // external symbol bit
  59            N_PEXT = 0x10    // private external symbol bit
  60     };
  61
  62     // Constants for the n_desc field
  63     // see <mach-o/loader.h>
  64     enum { REFERENCE_FLAG_UNDEFINED_NON_LAZY          = 0,
  65            REFERENCE_FLAG_UNDEFINED_LAZY              = 1,
  66            REFERENCE_FLAG_DEFINED                     = 2,
  67            REFERENCE_FLAG_PRIVATE_DEFINED             = 3,
  68            REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY  = 4,
  69            REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY      = 5
  70     };
  71     enum { N_NO_DEAD_STRIP = 0x0020, // symbol is not to be dead stripped
  72            N_WEAK_REF      = 0x0040, // symbol is weak referenced
  73            N_WEAK_DEF      = 0x0080  // coalesced symbol is a weak definition
  74     };
  75
  76     MachOSym(const GlobalValue *gv, std::string name, uint8_t sect,
  77              TargetMachine &TM);
  78   };
  79
  80   /// MachOWriter - This class implements the common target-independent code for
  81   /// writing Mach-O files.  Targets should derive a class from this to
  82   /// parameterize the output format.
  83   ///
  84   class MachOWriter : public MachineFunctionPass {
  85     friend class MachOCodeEmitter;
  86   public:
  87     static char ID;
  88     MachineCodeEmitter &getMachineCodeEmitter() const {
  89       return *(MachineCodeEmitter*)MCE;
  90     }
  91
  92     MachOWriter(std::ostream &O, TargetMachine &TM);
  93     virtual ~MachOWriter();
  94
  95     virtual const char *getPassName() const {
  96       return "Mach-O Writer";
  97     }
  98
  99     typedef std::vector<unsigned char> DataBuffer;
 100   protected:
 101     /// Output stream to send the resultant object file to.
 102     ///
 103     std::ostream &O;
 104
 105     /// Target machine description.
 106     ///
 107     TargetMachine &TM;
 108
 109     /// Mang - The object used to perform name mangling for this module.
 110     ///
 111     Mangler *Mang;
 112
 113     /// MCE - The MachineCodeEmitter object that we are exposing to emit machine
 114     /// code for functions to the .o file.
 115     MachOCodeEmitter *MCE;
 116
 117     /// is64Bit/isLittleEndian - This information is inferred from the target
 118     /// machine directly, indicating what header values and flags to set.
 119     bool is64Bit, isLittleEndian;
 120
 121     /// doInitialization - Emit the file header and all of the global variables
 122     /// for the module to the Mach-O file.
 123     bool doInitialization(Module &M);
 124
 125     bool runOnMachineFunction(MachineFunction &MF);
 126
 127     /// doFinalization - Now that the module has been completely processed, emit
 128     /// the Mach-O file to 'O'.
 129     bool doFinalization(Module &M);
 130
 131     /// MachOHeader - This struct contains the header information about a
 132     /// specific architecture type/subtype pair that is emitted to the file.
 133     struct MachOHeader {
 134       uint32_t  magic;      // mach magic number identifier
 135       uint32_t  filetype;   // type of file
 136       uint32_t  ncmds;      // number of load commands
 137       uint32_t  sizeofcmds; // the size of all the load commands
 138       uint32_t  flags;      // flags
 139       uint32_t  reserved;   // 64-bit only
 140
 141       /// HeaderData - The actual data for the header which we are building
 142       /// up for emission to the file.
 143       DataBuffer HeaderData;
 144
 145       // Constants for the filetype field
 146       // see <mach-o/loader.h> for additional info on the various types
 147       enum { MH_OBJECT     = 1, // relocatable object file
 148              MH_EXECUTE    = 2, // demand paged executable file
 149              MH_FVMLIB     = 3, // fixed VM shared library file
 150              MH_CORE       = 4, // core file
 151              MH_PRELOAD    = 5, // preloaded executable file
 152              MH_DYLIB      = 6, // dynamically bound shared library
 153              MH_DYLINKER   = 7, // dynamic link editor
 154              MH_BUNDLE     = 8, // dynamically bound bundle file
 155              MH_DYLIB_STUB = 9, // shared library stub for static linking only
 156              MH_DSYM       = 10 // companion file wiht only debug sections
 157       };
 158
 159       // Constants for the flags field
 160       enum { MH_NOUNDEFS                = 1 << 0,
 161                 // the object file has no undefined references
 162              MH_INCRLINK                = 1 << 1,
 163                 // the object file is the output of an incremental link against
 164                 // a base file and cannot be link edited again
 165              MH_DYLDLINK                = 1 << 2,
 166                 // the object file is input for the dynamic linker and cannot be
 167                 // statically link edited again.
 168              MH_BINDATLOAD              = 1 << 3,
 169                 // the object file's undefined references are bound by the
 170                 // dynamic linker when loaded.
 171              MH_PREBOUND                = 1 << 4,
 172                 // the file has its dynamic undefined references prebound
 173              MH_SPLIT_SEGS              = 1 << 5,
 174                 // the file has its read-only and read-write segments split
 175                 // see <mach/shared_memory_server.h>
 176              MH_LAZY_INIT               = 1 << 6,
 177                 // the shared library init routine is to be run lazily via
 178                 // catching memory faults to its writable segments (obsolete)
 179              MH_TWOLEVEL                = 1 << 7,
 180                 // the image is using two-level namespace bindings
 181              MH_FORCE_FLAT              = 1 << 8,
 182                 // the executable is forcing all images to use flat namespace
 183                 // bindings.
 184              MH_NOMULTIDEFS             = 1 << 8,
 185                 // this umbrella guarantees no multiple definitions of symbols
 186                 // in its sub-images so the two-level namespace hints can
 187                 // always be used.
 188              MH_NOFIXPREBINDING         = 1 << 10,
 189                 // do not have dyld notify the prebidning agent about this
 190                 // executable.
 191              MH_PREBINDABLE             = 1 << 11,
 192                 // the binary is not prebound but can have its prebinding
 193                 // redone.  only used when MH_PREBOUND is not set.
 194              MH_ALLMODSBOUND            = 1 << 12,
 195                 // indicates that this binary binds to all two-level namespace
 196                 // modules of its dependent libraries.  Only used when
 197                 // MH_PREBINDABLE and MH_TWOLEVEL are both set.
 198              MH_SUBSECTIONS_VIA_SYMBOLS = 1 << 13,
 199                 // safe to divide up the sections into sub-sections via symbols
 200                 // for dead code stripping.
 201              MH_CANONICAL               = 1 << 14,
 202                 // the binary has been canonicalized via the unprebind operation
 203              MH_WEAK_DEFINES            = 1 << 15,
 204                 // the final linked image contains external weak symbols
 205              MH_BINDS_TO_WEAK           = 1 << 16,
 206                 // the final linked image uses weak symbols
 207              MH_ALLOW_STACK_EXECUTION   = 1 << 17
 208                 // When this bit is set, all stacks in the task will be given
 209                 // stack execution privilege.  Only used in MH_EXECUTE filetype
 210       };
 211
 212       MachOHeader() : magic(0), filetype(0), ncmds(0), sizeofcmds(0), flags(0),
 213                       reserved(0) { }
 214
 215       /// cmdSize - This routine returns the size of the MachOSection as written
 216       /// to disk, depending on whether the destination is a 64 bit Mach-O file.
 217       unsigned cmdSize(bool is64Bit) const {
 218         if (is64Bit)
 219           return 8 * sizeof(uint32_t);
 220         else
 221           return 7 * sizeof(uint32_t);
 222       }
 223
 224       /// setMagic - This routine sets the appropriate value for the 'magic'
 225       /// field based on pointer size and endianness.
 226       void setMagic(bool isLittleEndian, bool is64Bit) {
 227         if (isLittleEndian)
 228           if (is64Bit) magic = 0xcffaedfe;
 229           else         magic = 0xcefaedfe;
 230         else
 231           if (is64Bit) magic = 0xfeedfacf;
 232           else         magic = 0xfeedface;
 233       }
 234     };
 235
 236     /// Header - An instance of MachOHeader that we will update while we build
 237     /// the file, and then emit during finalization.
 238     MachOHeader Header;
 239
 240     /// MachOSegment - This struct contains the necessary information to
 241     /// emit the load commands for each section in the file.
 242     struct MachOSegment {
 243       uint32_t    cmd;      // LC_SEGMENT or LC_SEGMENT_64
 244       uint32_t    cmdsize;  // Total size of this struct and section commands
 245       std::string segname;  // segment name
 246       uint64_t    vmaddr;   // address of this segment
 247       uint64_t    vmsize;   // size of this segment, may be larger than filesize
 248       uint64_t    fileoff;  // offset in file
 249       uint64_t    filesize; // amount to read from file
 250       uint32_t    maxprot;  // maximum VM protection
 251       uint32_t    initprot; // initial VM protection
 252       uint32_t    nsects;   // number of sections in this segment
 253       uint32_t    flags;    // flags
 254
 255       // The following constants are getting pulled in by one of the
 256       // system headers, which creates a neat clash with the enum.
 257 #if !defined(VM_PROT_NONE)
 258 #define VM_PROT_NONE    0x00
 259 #endif
 260 #if !defined(VM_PROT_READ)
 261 #define VM_PROT_READ    0x01
 262 #endif
 263 #if !defined(VM_PROT_WRITE)
 264 #define VM_PROT_WRITE   0x02
 265 #endif
 266 #if !defined(VM_PROT_EXECUTE)
 267 #define VM_PROT_EXECUTE 0x04
 268 #endif
 269 #if !defined(VM_PROT_ALL)
 270 #define VM_PROT_ALL     0x07
 271 #endif
 272
 273       // Constants for the vm protection fields
 274       // see <mach-o/vm_prot.h>
 275       enum { SEG_VM_PROT_NONE     = VM_PROT_NONE,
 276              SEG_VM_PROT_READ     = VM_PROT_READ, // read permission
 277              SEG_VM_PROT_WRITE    = VM_PROT_WRITE, // write permission
 278              SEG_VM_PROT_EXECUTE  = VM_PROT_EXECUTE,
 279              SEG_VM_PROT_ALL      = VM_PROT_ALL
 280       };
 281
 282       // Constants for the cmd field
 283       // see <mach-o/loader.h>
 284       enum { LC_SEGMENT    = 0x01,  // segment of this file to be mapped
 285              LC_SEGMENT_64 = 0x19   // 64-bit segment of this file to be mapped
 286       };
 287
 288       /// cmdSize - This routine returns the size of the MachOSection as written
 289       /// to disk, depending on whether the destination is a 64 bit Mach-O file.
 290       unsigned cmdSize(bool is64Bit) const {
 291         if (is64Bit)
 292           return 6 * sizeof(uint32_t) + 4 * sizeof(uint64_t) + 16;
 293         else
 294           return 10 * sizeof(uint32_t) + 16;  // addresses only 32 bits
 295       }
 296
 297       MachOSegment(const std::string &seg, bool is64Bit)
 298         : cmd(is64Bit ? LC_SEGMENT_64 : LC_SEGMENT), cmdsize(0), segname(seg),
 299           vmaddr(0), vmsize(0), fileoff(0), filesize(0), maxprot(VM_PROT_ALL),
 300           initprot(VM_PROT_ALL), nsects(0), flags(0) { }
 301     };
 302
 303     /// MachOSection - This struct contains information about each section in a
 304     /// particular segment that is emitted to the file.  This is eventually
 305     /// turned into the SectionCommand in the load command for a particlar
 306     /// segment.
 307     struct MachOSection {
 308       std::string  sectname; // name of this section,
 309       std::string  segname;  // segment this section goes in
 310       uint64_t  addr;        // memory address of this section
 311       uint64_t  size;        // size in bytes of this section
 312       uint32_t  offset;      // file offset of this section
 313       uint32_t  align;       // section alignment (power of 2)
 314       uint32_t  reloff;      // file offset of relocation entries
 315       uint32_t  nreloc;      // number of relocation entries
 316       uint32_t  flags;       // flags (section type and attributes)
 317       uint32_t  reserved1;   // reserved (for offset or index)
 318       uint32_t  reserved2;   // reserved (for count or sizeof)
 319       uint32_t  reserved3;   // reserved (64 bit only)
 320
 321       /// A unique number for this section, which will be used to match symbols
 322       /// to the correct section.
 323       uint32_t Index;
 324
 325       /// SectionData - The actual data for this section which we are building
 326       /// up for emission to the file.
 327       DataBuffer SectionData;
 328
 329       /// RelocBuffer - A buffer to hold the mach-o relocations before we write
 330       /// them out at the appropriate location in the file.
 331       DataBuffer RelocBuffer;
 332
 333       /// Relocations - The relocations that we have encountered so far in this
 334       /// section that we will need to convert to MachORelocation entries when
 335       /// the file is written.
 336       std::vector<MachineRelocation> Relocations;
 337
 338       // Constants for the section types (low 8 bits of flags field)
 339       // see <mach-o/loader.h>
 340       enum { S_REGULAR = 0,
 341                 // regular section
 342              S_ZEROFILL = 1,
 343                 // zero fill on demand section
 344              S_CSTRING_LITERALS = 2,
 345                 // section with only literal C strings
 346              S_4BYTE_LITERALS = 3,
 347                 // section with only 4 byte literals
 348              S_8BYTE_LITERALS = 4,
 349                 // section with only 8 byte literals
 350              S_LITERAL_POINTERS = 5,
 351                 // section with only pointers to literals
 352              S_NON_LAZY_SYMBOL_POINTERS = 6,
 353                 // section with only non-lazy symbol pointers
 354              S_LAZY_SYMBOL_POINTERS = 7,
 355                 // section with only lazy symbol pointers
 356              S_SYMBOL_STUBS = 8,
 357                 // section with only symbol stubs
 358                 // byte size of stub in the reserved2 field
 359              S_MOD_INIT_FUNC_POINTERS = 9,
 360                 // section with only function pointers for initialization
 361              S_MOD_TERM_FUNC_POINTERS = 10,
 362                 // section with only function pointers for termination
 363              S_COALESCED = 11,
 364                 // section contains symbols that are coalesced
 365              S_GB_ZEROFILL = 12,
 366                 // zero fill on demand section (that can be larger than 4GB)
 367              S_INTERPOSING = 13,
 368                 // section with only pairs of function pointers for interposing
 369              S_16BYTE_LITERALS = 14
 370                 // section with only 16 byte literals
 371       };
 372
 373       // Constants for the section flags (high 24 bits of flags field)
 374       // see <mach-o/loader.h>
 375       enum { S_ATTR_PURE_INSTRUCTIONS   = 1 << 31,
 376                 // section contains only true machine instructions
 377              S_ATTR_NO_TOC              = 1 << 30,
 378                 // section contains coalesced symbols that are not to be in a
 379                 // ranlib table of contents
 380              S_ATTR_STRIP_STATIC_SYMS   = 1 << 29,
 381                 // ok to strip static symbols in this section in files with the
 382                 // MY_DYLDLINK flag
 383              S_ATTR_NO_DEAD_STRIP       = 1 << 28,
 384                 // no dead stripping
 385              S_ATTR_LIVE_SUPPORT        = 1 << 27,
 386                 // blocks are live if they reference live blocks
 387              S_ATTR_SELF_MODIFYING_CODE = 1 << 26,
 388                 // used with i386 code stubs written on by dyld
 389              S_ATTR_DEBUG               = 1 << 25,
 390                 // a debug section
 391              S_ATTR_SOME_INSTRUCTIONS   = 1 << 10,
 392                 // section contains some machine instructions
 393              S_ATTR_EXT_RELOC           = 1 << 9,
 394                 // section has external relocation entries
 395              S_ATTR_LOC_RELOC           = 1 << 8
 396                 // section has local relocation entries
 397       };
 398
 399       /// cmdSize - This routine returns the size of the MachOSection as written
 400       /// to disk, depending on whether the destination is a 64 bit Mach-O file.
 401       unsigned cmdSize(bool is64Bit) const {
 402         if (is64Bit)
 403           return 7 * sizeof(uint32_t) + 2 * sizeof(uint64_t) + 32;
 404         else
 405           return 9 * sizeof(uint32_t) + 32;  // addresses only 32 bits
 406       }
 407
 408       MachOSection(const std::string &seg, const std::string &sect)
 409         : sectname(sect), segname(seg), addr(0), size(0), offset(0), align(2),
 410           reloff(0), nreloc(0), flags(0), reserved1(0), reserved2(0),
 411           reserved3(0) { }
 412     };
 413
 414   private:
 415
 416     /// SectionList - This is the list of sections that we have emitted to the
 417     /// file.  Once the file has been completely built, the segment load command
 418     /// SectionCommands are constructed from this info.
 419     std::vector<MachOSection*> SectionList;
 420
 421     /// SectionLookup - This is a mapping from section name to SectionList entry
 422     std::map<std::string, MachOSection*> SectionLookup;
 423
 424     /// GVSection - This is a mapping from a GlobalValue to a MachOSection,
 425     /// to aid in emitting relocations.
 426     std::map<GlobalValue*, MachOSection*> GVSection;
 427
 428     /// GVOffset - This is a mapping from a GlobalValue to an offset from the
 429     /// start of the section in which the GV resides, to aid in emitting
 430     /// relocations.
 431     std::map<GlobalValue*, intptr_t> GVOffset;
 432
 433     /// getSection - Return the section with the specified name, creating a new
 434     /// section if one does not already exist.
 435     MachOSection *getSection(const std::string &seg, const std::string &sect,
 436                              unsigned Flags = 0) {
 437       MachOSection *MOS = SectionLookup[seg+sect];
 438       if (MOS) return MOS;
 439
 440       MOS = new MachOSection(seg, sect);
 441       SectionList.push_back(MOS);
 442       MOS->Index = SectionList.size();
 443       MOS->flags = MachOSection::S_REGULAR | Flags;
 444       SectionLookup[seg+sect] = MOS;
 445       return MOS;
 446     }
 447     MachOSection *getTextSection(bool isCode = true) {
 448       if (isCode)
 449         return getSection("__TEXT", "__text",
 450                           MachOSection::S_ATTR_PURE_INSTRUCTIONS |
 451                           MachOSection::S_ATTR_SOME_INSTRUCTIONS);
 452       else
 453         return getSection("__TEXT", "__text");
 454     }
 455     MachOSection *getBSSSection() {
 456       return getSection("__DATA", "__bss", MachOSection::S_ZEROFILL);
 457     }
 458     MachOSection *getDataSection() {
 459       return getSection("__DATA", "__data");
 460     }
 461     MachOSection *getConstSection(Constant *C) {
 462       const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
 463       if (CVA && CVA->isCString())
 464         return getSection("__TEXT", "__cstring",
 465                           MachOSection::S_CSTRING_LITERALS);
 466
 467       const Type *Ty = C->getType();
 468       if (Ty->isPrimitiveType() || Ty->isInteger()) {
 469         unsigned Size = TM.getTargetData()->getTypeSize(Ty);
 470         switch(Size) {
 471         default: break; // Fall through to __TEXT,__const
 472         case 4:
 473           return getSection("__TEXT", "__literal4",
 474                             MachOSection::S_4BYTE_LITERALS);
 475         case 8:
 476           return getSection("__TEXT", "__literal8",
 477                             MachOSection::S_8BYTE_LITERALS);
 478         case 16:
 479           return getSection("__TEXT", "__literal16",
 480                             MachOSection::S_16BYTE_LITERALS);
 481         }
 482       }
 483       return getSection("__TEXT", "__const");
 484     }
 485     MachOSection *getJumpTableSection() {
 486       if (TM.getRelocationModel() == Reloc::PIC_)
 487         return getTextSection(false);
 488       else
 489         return getSection("__TEXT", "__const");
 490     }
 491
 492     /// MachOSymTab - This struct contains information about the offsets and
 493     /// size of symbol table information.
 494     /// segment.
 495     struct MachOSymTab {
 496       uint32_t cmd;     // LC_SYMTAB
 497       uint32_t cmdsize; // sizeof( MachOSymTab )
 498       uint32_t symoff;  // symbol table offset
 499       uint32_t nsyms;   // number of symbol table entries
 500       uint32_t stroff;  // string table offset
 501       uint32_t strsize; // string table size in bytes
 502
 503       // Constants for the cmd field
 504       // see <mach-o/loader.h>
 505       enum { LC_SYMTAB = 0x02  // link-edit stab symbol table info
 506       };
 507
 508       MachOSymTab() : cmd(LC_SYMTAB), cmdsize(6 * sizeof(uint32_t)), symoff(0),
 509         nsyms(0), stroff(0), strsize(0) { }
 510     };
 511
 512     /// MachOSymTab - This struct contains information about the offsets and
 513     /// size of symbol table information.
 514     /// segment.
 515     struct MachODySymTab {
 516       uint32_t cmd;             // LC_DYSYMTAB
 517       uint32_t cmdsize;         // sizeof( MachODySymTab )
 518       uint32_t ilocalsym;       // index to local symbols
 519       uint32_t nlocalsym;       // number of local symbols
 520       uint32_t iextdefsym;      // index to externally defined symbols
 521       uint32_t nextdefsym;      // number of externally defined symbols
 522       uint32_t iundefsym;       // index to undefined symbols
 523       uint32_t nundefsym;       // number of undefined symbols
 524       uint32_t tocoff;          // file offset to table of contents
 525       uint32_t ntoc;            // number of entries in table of contents
 526       uint32_t modtaboff;       // file offset to module table
 527       uint32_t nmodtab;         // number of module table entries
 528       uint32_t extrefsymoff;    // offset to referenced symbol table
 529       uint32_t nextrefsyms;     // number of referenced symbol table entries
 530       uint32_t indirectsymoff;  // file offset to the indirect symbol table
 531       uint32_t nindirectsyms;   // number of indirect symbol table entries
 532       uint32_t extreloff;       // offset to external relocation entries
 533       uint32_t nextrel;         // number of external relocation entries
 534       uint32_t locreloff;       // offset to local relocation entries
 535       uint32_t nlocrel;         // number of local relocation entries
 536
 537       // Constants for the cmd field
 538       // see <mach-o/loader.h>
 539       enum { LC_DYSYMTAB = 0x0B  // dynamic link-edit symbol table info
 540       };
 541
 542       MachODySymTab() : cmd(LC_DYSYMTAB), cmdsize(20 * sizeof(uint32_t)),
 543         ilocalsym(0), nlocalsym(0), iextdefsym(0), nextdefsym(0),
 544         iundefsym(0), nundefsym(0), tocoff(0), ntoc(0), modtaboff(0),
 545         nmodtab(0), extrefsymoff(0), nextrefsyms(0), indirectsymoff(0),
 546         nindirectsyms(0), extreloff(0), nextrel(0), locreloff(0), nlocrel(0) { }
 547     };
 548
 549     /// SymTab - The "stab" style symbol table information
 550     MachOSymTab   SymTab;
 551     /// DySymTab - symbol table info for the dynamic link editor
 552     MachODySymTab DySymTab;
 553
 554     struct MachOSymCmp {
 555       // FIXME: this does not appear to be sorting 'f' after 'F'
 556       bool operator()(const MachOSym &LHS, const MachOSym &RHS) {
 557         return LHS.GVName < RHS.GVName;
 558       }
 559     };
 560
 561     /// PartitionByLocal - Simple boolean predicate that returns true if Sym is
 562     /// a local symbol rather than an external symbol.
 563     static bool PartitionByLocal(const MachOSym &Sym);
 564
 565     /// PartitionByDefined - Simple boolean predicate that returns true if Sym
 566     /// is defined in this module.
 567     static bool PartitionByDefined(const MachOSym &Sym);
 568
 569   protected:
 570
 571     /// SymbolTable - This is the list of symbols we have emitted to the file.
 572     /// This actually gets rearranged before emission to the file (to put the
 573     /// local symbols first in the list).
 574     std::vector<MachOSym> SymbolTable;
 575
 576     /// SymT - A buffer to hold the symbol table before we write it out at the
 577     /// appropriate location in the file.
 578     DataBuffer SymT;
 579
 580     /// StrT - A buffer to hold the string table before we write it out at the
 581     /// appropriate location in the file.
 582     DataBuffer StrT;
 583
 584     /// PendingSyms - This is a list of externally defined symbols that we have
 585     /// been asked to emit, but have not seen a reference to.  When a reference
 586     /// is seen, the symbol will move from this list to the SymbolTable.
 587     std::vector<GlobalValue*> PendingGlobals;
 588
 589     /// DynamicSymbolTable - This is just a vector of indices into
 590     /// SymbolTable to aid in emitting the DYSYMTAB load command.
 591     std::vector<unsigned> DynamicSymbolTable;
 592
 593     static void InitMem(const Constant *C, void *Addr, intptr_t Offset,
 594                         const TargetData *TD,
 595                         std::vector<MachineRelocation> &MRs);
 596
 597   private:
 598     void AddSymbolToSection(MachOSection *MOS, GlobalVariable *GV);
 599     void EmitGlobal(GlobalVariable *GV);
 600     void EmitHeaderAndLoadCommands();
 601     void EmitSections();
 602     void BufferSymbolAndStringTable();
 603     void CalculateRelocations(MachOSection &MOS);
 604
 605     MachineRelocation GetJTRelocation(unsigned Offset,
 606                                       MachineBasicBlock *MBB) const {
 607       return TM.getMachOWriterInfo()->GetJTRelocation(Offset, MBB);
 608     }
 609
 610     /// GetTargetRelocation - Returns the number of relocations.
 611     unsigned GetTargetRelocation(MachineRelocation &MR,
 612                                  unsigned FromIdx,
 613                                  unsigned ToAddr,
 614                                  unsigned ToIndex,
 615                                  OutputBuffer &RelocOut,
 616                                  OutputBuffer &SecOut,
 617                                  bool Scattered,
 618                                  bool Extern) {
 619       return TM.getMachOWriterInfo()->GetTargetRelocation(MR, FromIdx, ToAddr,
 620                                                           ToIndex, RelocOut,
 621                                                           SecOut, Scattered,
 622                                                           Extern);
 623     }
 624   };
 625 }
 626
 627 #endif