lib/CodeGen/MachOWriter.h

   1 //=== MachOWriter.h - Target-independent Mach-O writer support --*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // 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 #include <map>
  25
  26 namespace llvm {
  27   class GlobalVariable;
  28   class Mangler;
  29   class MachineCodeEmitter;
  30   class MachOCodeEmitter;
  31   class OutputBuffer;
  32   class raw_ostream;
  33
  34   /// MachOSym - This struct contains information about each symbol that is
  35   /// added to logical symbol table for the module.  This is eventually
  36   /// turned into a real symbol table in the file.
  37   struct MachOSym {
  38     const GlobalValue *GV;    // The global value this corresponds to.
  39     std::string GVName;       // The mangled name of the global value.
  40     uint32_t    n_strx;       // index into the string table
  41     uint8_t     n_type;       // type flag
  42     uint8_t     n_sect;       // section number or NO_SECT
  43     int16_t     n_desc;       // see <mach-o/stab.h>
  44     uint64_t    n_value;      // value for this symbol (or stab offset)
  45
  46     // Constants for the n_sect field
  47     // see <mach-o/nlist.h>
  48     enum { NO_SECT = 0 };   // symbol is not in any section
  49
  50     // Constants for the n_type field
  51     // see <mach-o/nlist.h>
  52     enum { N_UNDF  = 0x0,  // undefined, n_sect == NO_SECT
  53            N_ABS   = 0x2,  // absolute, n_sect == NO_SECT
  54            N_SECT  = 0xe,  // defined in section number n_sect
  55            N_PBUD  = 0xc,  // prebound undefined (defined in a dylib)
  56            N_INDR  = 0xa   // indirect
  57     };
  58     // The following bits are OR'd into the types above. For example, a type
  59     // of 0x0f would be an external N_SECT symbol (0x0e | 0x01).
  60     enum { N_EXT  = 0x01,   // external symbol bit
  61            N_PEXT = 0x10    // private external symbol bit
  62     };
  63
  64     // Constants for the n_desc field
  65     // see <mach-o/loader.h>
  66     enum { REFERENCE_FLAG_UNDEFINED_NON_LAZY          = 0,
  67            REFERENCE_FLAG_UNDEFINED_LAZY              = 1,
  68            REFERENCE_FLAG_DEFINED                     = 2,
  69            REFERENCE_FLAG_PRIVATE_DEFINED             = 3,
  70            REFERENCE_FLAG_PRIVATE_UNDEFINED_NON_LAZY  = 4,
  71            REFERENCE_FLAG_PRIVATE_UNDEFINED_LAZY      = 5
  72     };
  73     enum { N_NO_DEAD_STRIP = 0x0020, // symbol is not to be dead stripped
  74            N_WEAK_REF      = 0x0040, // symbol is weak referenced
  75            N_WEAK_DEF      = 0x0080  // coalesced symbol is a weak definition
  76     };
  77
  78     MachOSym(const GlobalValue *gv, std::string name, uint8_t sect,
  79              TargetMachine &TM);
  80   };
  81
  82   /// MachOWriter - This class implements the common target-independent code for
  83   /// writing Mach-O files.  Targets should derive a class from this to
  84   /// parameterize the output format.
  85   ///
  86   class MachOWriter : public MachineFunctionPass {
  87     friend class MachOCodeEmitter;
  88   public:
  89     static char ID;
  90     MachineCodeEmitter &getMachineCodeEmitter() const {
  91       return *(MachineCodeEmitter*)MCE;
  92     }
  93
  94     MachOWriter(raw_ostream &O, TargetMachine &TM);
  95     virtual ~MachOWriter();
  96
  97     virtual const char *getPassName() const {
  98       return "Mach-O Writer";
  99     }
 100
 101     typedef std::vector<unsigned char> DataBuffer;
 102   protected:
 103     /// Output stream to send the resultant object file to.
 104     ///
 105     raw_ostream &O;
 106
 107     /// Target machine description.
 108     ///
 109     TargetMachine &TM;
 110
 111     /// Mang - The object used to perform name mangling for this module.
 112     ///
 113     Mangler *Mang;
 114
 115     /// MCE - The MachineCodeEmitter object that we are exposing to emit machine
 116     /// code for functions to the .o file.
 117     MachOCodeEmitter *MCE;
 118
 119     /// is64Bit/isLittleEndian - This information is inferred from the target
 120     /// machine directly, indicating what header values and flags to set.
 121     bool is64Bit, isLittleEndian;
 122
 123     /// doInitialization - Emit the file header and all of the global variables
 124     /// for the module to the Mach-O file.
 125     bool doInitialization(Module &M);
 126
 127     bool runOnMachineFunction(MachineFunction &MF);
 128
 129     /// doFinalization - Now that the module has been completely processed, emit
 130     /// the Mach-O file to 'O'.
 131     bool doFinalization(Module &M);
 132
 133     /// MachOHeader - This struct contains the header information about a
 134     /// specific architecture type/subtype pair that is emitted to the file.
 135     struct MachOHeader {
 136       uint32_t  magic;      // mach magic number identifier
 137       uint32_t  filetype;   // type of file
 138       uint32_t  ncmds;      // number of load commands
 139       uint32_t  sizeofcmds; // the size of all the load commands
 140       uint32_t  flags;      // flags
 141       uint32_t  reserved;   // 64-bit only
 142
 143       /// HeaderData - The actual data for the header which we are building
 144       /// up for emission to the file.
 145       DataBuffer HeaderData;
 146
 147       // Constants for the filetype field
 148       // see <mach-o/loader.h> for additional info on the various types
 149       enum { MH_OBJECT     = 1, // relocatable object file
 150              MH_EXECUTE    = 2, // demand paged executable file
 151              MH_FVMLIB     = 3, // fixed VM shared library file
 152              MH_CORE       = 4, // core file
 153              MH_PRELOAD    = 5, // preloaded executable file
 154              MH_DYLIB      = 6, // dynamically bound shared library
 155              MH_DYLINKER   = 7, // dynamic link editor
 156              MH_BUNDLE     = 8, // dynamically bound bundle file
 157              MH_DYLIB_STUB = 9, // shared library stub for static linking only
 158              MH_DSYM       = 10 // companion file wiht only debug sections
 159       };
 160
 161       // Constants for the flags field
 162       enum { MH_NOUNDEFS                = 1 << 0,
 163                 // the object file has no undefined references
 164              MH_INCRLINK                = 1 << 1,
 165                 // the object file is the output of an incremental link against
 166                 // a base file and cannot be link edited again
 167              MH_DYLDLINK                = 1 << 2,
 168                 // the object file is input for the dynamic linker and cannot be
 169                 // statically link edited again.
 170              MH_BINDATLOAD              = 1 << 3,
 171                 // the object file's undefined references are bound by the
 172                 // dynamic linker when loaded.
 173              MH_PREBOUND                = 1 << 4,
 174                 // the file has its dynamic undefined references prebound
 175              MH_SPLIT_SEGS              = 1 << 5,
 176                 // the file has its read-only and read-write segments split
 177                 // see <mach/shared_memory_server.h>
 178              MH_LAZY_INIT               = 1 << 6,
 179                 // the shared library init routine is to be run lazily via
 180                 // catching memory faults to its writable segments (obsolete)
 181              MH_TWOLEVEL                = 1 << 7,
 182                 // the image is using two-level namespace bindings
 183              MH_FORCE_FLAT              = 1 << 8,
 184                 // the executable is forcing all images to use flat namespace
 185                 // bindings.
 186              MH_NOMULTIDEFS             = 1 << 8,
 187                 // this umbrella guarantees no multiple definitions of symbols
 188                 // in its sub-images so the two-level namespace hints can
 189                 // always be used.
 190              MH_NOFIXPREBINDING         = 1 << 10,
 191                 // do not have dyld notify the prebidning agent about this
 192                 // executable.
 193              MH_PREBINDABLE             = 1 << 11,
 194                 // the binary is not prebound but can have its prebinding
 195                 // redone.  only used when MH_PREBOUND is not set.
 196              MH_ALLMODSBOUND            = 1 << 12,
 197                 // indicates that this binary binds to all two-level namespace
 198                 // modules of its dependent libraries.  Only used when
 199                 // MH_PREBINDABLE and MH_TWOLEVEL are both set.
 200              MH_SUBSECTIONS_VIA_SYMBOLS = 1 << 13,
 201                 // safe to divide up the sections into sub-sections via symbols
 202                 // for dead code stripping.
 203              MH_CANONICAL               = 1 << 14,
 204                 // the binary has been canonicalized via the unprebind operation
 205              MH_WEAK_DEFINES            = 1 << 15,
 206                 // the final linked image contains external weak symbols
 207              MH_BINDS_TO_WEAK           = 1 << 16,
 208                 // the final linked image uses weak symbols
 209              MH_ALLOW_STACK_EXECUTION   = 1 << 17
 210                 // When this bit is set, all stacks in the task will be given
 211                 // stack execution privilege.  Only used in MH_EXECUTE filetype
 212       };
 213
 214       MachOHeader() : magic(0), filetype(0), ncmds(0), sizeofcmds(0), flags(0),
 215                       reserved(0) { }
 216
 217       /// cmdSize - This routine returns the size of the MachOSection as written
 218       /// to disk, depending on whether the destination is a 64 bit Mach-O file.
 219       unsigned cmdSize(bool is64Bit) const {
 220         if (is64Bit)
 221           return 8 * sizeof(uint32_t);
 222         else
 223           return 7 * sizeof(uint32_t);
 224       }
 225
 226       /// setMagic - This routine sets the appropriate value for the 'magic'
 227       /// field based on pointer size and endianness.
 228       void setMagic(bool isLittleEndian, bool is64Bit) {
 229         if (isLittleEndian)
 230           if (is64Bit) magic = 0xcffaedfe;
 231           else         magic = 0xcefaedfe;
 232         else
 233           if (is64Bit) magic = 0xfeedfacf;
 234           else         magic = 0xfeedface;
 235       }
 236     };
 237
 238     /// Header - An instance of MachOHeader that we will update while we build
 239     /// the file, and then emit during finalization.
 240     MachOHeader Header;
 241
 242     /// MachOSegment - This struct contains the necessary information to
 243     /// emit the load commands for each section in the file.
 244     struct MachOSegment {
 245       uint32_t    cmd;      // LC_SEGMENT or LC_SEGMENT_64
 246       uint32_t    cmdsize;  // Total size of this struct and section commands
 247       std::string segname;  // segment name
 248       uint64_t    vmaddr;   // address of this segment
 249       uint64_t    vmsize;   // size of this segment, may be larger than filesize
 250       uint64_t    fileoff;  // offset in file
 251       uint64_t    filesize; // amount to read from file
 252       uint32_t    maxprot;  // maximum VM protection
 253       uint32_t    initprot; // initial VM protection
 254       uint32_t    nsects;   // number of sections in this segment
 255       uint32_t    flags;    // flags
 256
 257       // The following constants are getting pulled in by one of the
 258       // system headers, which creates a neat clash with the enum.
 259 #if !defined(VM_PROT_NONE)
 260 #define VM_PROT_NONE    0x00
 261 #endif
 262 #if !defined(VM_PROT_READ)
 263 #define VM_PROT_READ    0x01
 264 #endif
 265 #if !defined(VM_PROT_WRITE)
 266 #define VM_PROT_WRITE   0x02
 267 #endif
 268 #if !defined(VM_PROT_EXECUTE)
 269 #define VM_PROT_EXECUTE 0x04
 270 #endif
 271 #if !defined(VM_PROT_ALL)
 272 #define VM_PROT_ALL     0x07
 273 #endif
 274
 275       // Constants for the vm protection fields
 276       // see <mach-o/vm_prot.h>
 277       enum { SEG_VM_PROT_NONE     = VM_PROT_NONE,
 278              SEG_VM_PROT_READ     = VM_PROT_READ, // read permission
 279              SEG_VM_PROT_WRITE    = VM_PROT_WRITE, // write permission
 280              SEG_VM_PROT_EXECUTE  = VM_PROT_EXECUTE,
 281              SEG_VM_PROT_ALL      = VM_PROT_ALL
 282       };
 283
 284       // Constants for the cmd field
 285       // see <mach-o/loader.h>
 286       enum { LC_SEGMENT    = 0x01,  // segment of this file to be mapped
 287              LC_SEGMENT_64 = 0x19   // 64-bit segment of this file to be mapped
 288       };
 289
 290       /// cmdSize - This routine returns the size of the MachOSection as written
 291       /// to disk, depending on whether the destination is a 64 bit Mach-O file.
 292       unsigned cmdSize(bool is64Bit) const {
 293         if (is64Bit)
 294           return 6 * sizeof(uint32_t) + 4 * sizeof(uint64_t) + 16;
 295         else
 296           return 10 * sizeof(uint32_t) + 16;  // addresses only 32 bits
 297       }
 298
 299       MachOSegment(const std::string &seg, bool is64Bit)
 300         : cmd(is64Bit ? LC_SEGMENT_64 : LC_SEGMENT), cmdsize(0), segname(seg),
 301           vmaddr(0), vmsize(0), fileoff(0), filesize(0), maxprot(VM_PROT_ALL),
 302           initprot(VM_PROT_ALL), nsects(0), flags(0) { }
 303     };
 304
 305     /// MachOSection - This struct contains information about each section in a
 306     /// particular segment that is emitted to the file.  This is eventually
 307     /// turned into the SectionCommand in the load command for a particlar
 308     /// segment.
 309     struct MachOSection {
 310       std::string  sectname; // name of this section,
 311       std::string  segname;  // segment this section goes in
 312       uint64_t  addr;        // memory address of this section
 313       uint64_t  size;        // size in bytes of this section
 314       uint32_t  offset;      // file offset of this section
 315       uint32_t  align;       // section alignment (power of 2)
 316       uint32_t  reloff;      // file offset of relocation entries
 317       uint32_t  nreloc;      // number of relocation entries
 318       uint32_t  flags;       // flags (section type and attributes)
 319       uint32_t  reserved1;   // reserved (for offset or index)
 320       uint32_t  reserved2;   // reserved (for count or sizeof)
 321       uint32_t  reserved3;   // reserved (64 bit only)
 322
 323       /// A unique number for this section, which will be used to match symbols
 324       /// to the correct section.
 325       uint32_t Index;
 326
 327       /// SectionData - The actual data for this section which we are building
 328       /// up for emission to the file.
 329       DataBuffer SectionData;
 330
 331       /// RelocBuffer - A buffer to hold the mach-o relocations before we write
 332       /// them out at the appropriate location in the file.
 333       DataBuffer RelocBuffer;
 334
 335       /// Relocations - The relocations that we have encountered so far in this
 336       /// section that we will need to convert to MachORelocation entries when
 337       /// the file is written.
 338       std::vector<MachineRelocation> Relocations;
 339
 340       // Constants for the section types (low 8 bits of flags field)
 341       // see <mach-o/loader.h>
 342       enum { S_REGULAR = 0,
 343                 // regular section
 344              S_ZEROFILL = 1,
 345                 // zero fill on demand section
 346              S_CSTRING_LITERALS = 2,
 347                 // section with only literal C strings
 348              S_4BYTE_LITERALS = 3,
 349                 // section with only 4 byte literals
 350              S_8BYTE_LITERALS = 4,
 351                 // section with only 8 byte literals
 352              S_LITERAL_POINTERS = 5,
 353                 // section with only pointers to literals
 354              S_NON_LAZY_SYMBOL_POINTERS = 6,
 355                 // section with only non-lazy symbol pointers
 356              S_LAZY_SYMBOL_POINTERS = 7,
 357                 // section with only lazy symbol pointers
 358              S_SYMBOL_STUBS = 8,
 359                 // section with only symbol stubs
 360                 // byte size of stub in the reserved2 field
 361              S_MOD_INIT_FUNC_POINTERS = 9,
 362                 // section with only function pointers for initialization
 363              S_MOD_TERM_FUNC_POINTERS = 10,
 364                 // section with only function pointers for termination
 365              S_COALESCED = 11,
 366                 // section contains symbols that are coalesced
 367              S_GB_ZEROFILL = 12,
 368                 // zero fill on demand section (that can be larger than 4GB)
 369              S_INTERPOSING = 13,
 370                 // section with only pairs of function pointers for interposing
 371              S_16BYTE_LITERALS = 14
 372                 // section with only 16 byte literals
 373       };
 374
 375       // Constants for the section flags (high 24 bits of flags field)
 376       // see <mach-o/loader.h>
 377       enum { S_ATTR_PURE_INSTRUCTIONS   = 1 << 31,
 378                 // section contains only true machine instructions
 379              S_ATTR_NO_TOC              = 1 << 30,
 380                 // section contains coalesced symbols that are not to be in a
 381                 // ranlib table of contents
 382              S_ATTR_STRIP_STATIC_SYMS   = 1 << 29,
 383                 // ok to strip static symbols in this section in files with the
 384                 // MY_DYLDLINK flag
 385              S_ATTR_NO_DEAD_STRIP       = 1 << 28,
 386                 // no dead stripping
 387              S_ATTR_LIVE_SUPPORT        = 1 << 27,
 388                 // blocks are live if they reference live blocks
 389              S_ATTR_SELF_MODIFYING_CODE = 1 << 26,
 390                 // used with i386 code stubs written on by dyld
 391              S_ATTR_DEBUG               = 1 << 25,
 392                 // a debug section
 393              S_ATTR_SOME_INSTRUCTIONS   = 1 << 10,
 394                 // section contains some machine instructions
 395              S_ATTR_EXT_RELOC           = 1 << 9,
 396                 // section has external relocation entries
 397              S_ATTR_LOC_RELOC           = 1 << 8
 398                 // section has local relocation entries
 399       };
 400
 401       /// cmdSize - This routine returns the size of the MachOSection as written
 402       /// to disk, depending on whether the destination is a 64 bit Mach-O file.
 403       unsigned cmdSize(bool is64Bit) const {
 404         if (is64Bit)
 405           return 7 * sizeof(uint32_t) + 2 * sizeof(uint64_t) + 32;
 406         else
 407           return 9 * sizeof(uint32_t) + 32;  // addresses only 32 bits
 408       }
 409
 410       MachOSection(const std::string &seg, const std::string &sect)
 411         : sectname(sect), segname(seg), addr(0), size(0), offset(0), align(2),
 412           reloff(0), nreloc(0), flags(0), reserved1(0), reserved2(0),
 413           reserved3(0) { }
 414     };
 415
 416   private:
 417
 418     /// SectionList - This is the list of sections that we have emitted to the
 419     /// file.  Once the file has been completely built, the segment load command
 420     /// SectionCommands are constructed from this info.
 421     std::vector<MachOSection*> SectionList;
 422
 423     /// SectionLookup - This is a mapping from section name to SectionList entry
 424     std::map<std::string, MachOSection*> SectionLookup;
 425
 426     /// GVSection - This is a mapping from a GlobalValue to a MachOSection,
 427     /// to aid in emitting relocations.
 428     std::map<GlobalValue*, MachOSection*> GVSection;
 429
 430     /// GVOffset - This is a mapping from a GlobalValue to an offset from the
 431     /// start of the section in which the GV resides, to aid in emitting
 432     /// relocations.
 433     std::map<GlobalValue*, intptr_t> GVOffset;
 434
 435     /// getSection - Return the section with the specified name, creating a new
 436     /// section if one does not already exist.
 437     MachOSection *getSection(const std::string &seg, const std::string &sect,
 438                              unsigned Flags = 0) {
 439       MachOSection *MOS = SectionLookup[seg+sect];
 440       if (MOS) return MOS;
 441
 442       MOS = new MachOSection(seg, sect);
 443       SectionList.push_back(MOS);
 444       MOS->Index = SectionList.size();
 445       MOS->flags = MachOSection::S_REGULAR | Flags;
 446       SectionLookup[seg+sect] = MOS;
 447       return MOS;
 448     }
 449     MachOSection *getTextSection(bool isCode = true) {
 450       if (isCode)
 451         return getSection("__TEXT", "__text",
 452                           MachOSection::S_ATTR_PURE_INSTRUCTIONS |
 453                           MachOSection::S_ATTR_SOME_INSTRUCTIONS);
 454       else
 455         return getSection("__TEXT", "__text");
 456     }
 457     MachOSection *getBSSSection() {
 458       return getSection("__DATA", "__bss", MachOSection::S_ZEROFILL);
 459     }
 460     MachOSection *getDataSection() {
 461       return getSection("__DATA", "__data");
 462     }
 463     MachOSection *getConstSection(Constant *C) {
 464       const ConstantArray *CVA = dyn_cast<ConstantArray>(C);
 465       if (CVA && CVA->isCString())
 466         return getSection("__TEXT", "__cstring",
 467                           MachOSection::S_CSTRING_LITERALS);
 468
 469       const Type *Ty = C->getType();
 470       if (Ty->isPrimitiveType() || Ty->isInteger()) {
 471         unsigned Size = TM.getTargetData()->getTypeAllocSize(Ty);
 472         switch(Size) {
 473         default: break; // Fall through to __TEXT,__const
 474         case 4:
 475           return getSection("__TEXT", "__literal4",
 476                             MachOSection::S_4BYTE_LITERALS);
 477         case 8:
 478           return getSection("__TEXT", "__literal8",
 479                             MachOSection::S_8BYTE_LITERALS);
 480         case 16:
 481           return getSection("__TEXT", "__literal16",
 482                             MachOSection::S_16BYTE_LITERALS);
 483         }
 484       }
 485       return getSection("__TEXT", "__const");
 486     }
 487     MachOSection *getJumpTableSection() {
 488       if (TM.getRelocationModel() == Reloc::PIC_)
 489         return getTextSection(false);
 490       else
 491         return getSection("__TEXT", "__const");
 492     }
 493
 494     /// MachOSymTab - This struct contains information about the offsets and
 495     /// size of symbol table information.
 496     /// segment.
 497     struct MachOSymTab {
 498       uint32_t cmd;     // LC_SYMTAB
 499       uint32_t cmdsize; // sizeof( MachOSymTab )
 500       uint32_t symoff;  // symbol table offset
 501       uint32_t nsyms;   // number of symbol table entries
 502       uint32_t stroff;  // string table offset
 503       uint32_t strsize; // string table size in bytes
 504
 505       // Constants for the cmd field
 506       // see <mach-o/loader.h>
 507       enum { LC_SYMTAB = 0x02  // link-edit stab symbol table info
 508       };
 509
 510       MachOSymTab() : cmd(LC_SYMTAB), cmdsize(6 * sizeof(uint32_t)), symoff(0),
 511         nsyms(0), stroff(0), strsize(0) { }
 512     };
 513
 514     /// MachOSymTab - This struct contains information about the offsets and
 515     /// size of symbol table information.
 516     /// segment.
 517     struct MachODySymTab {
 518       uint32_t cmd;             // LC_DYSYMTAB
 519       uint32_t cmdsize;         // sizeof( MachODySymTab )
 520       uint32_t ilocalsym;       // index to local symbols
 521       uint32_t nlocalsym;       // number of local symbols
 522       uint32_t iextdefsym;      // index to externally defined symbols
 523       uint32_t nextdefsym;      // number of externally defined symbols
 524       uint32_t iundefsym;       // index to undefined symbols
 525       uint32_t nundefsym;       // number of undefined symbols
 526       uint32_t tocoff;          // file offset to table of contents
 527       uint32_t ntoc;            // number of entries in table of contents
 528       uint32_t modtaboff;       // file offset to module table
 529       uint32_t nmodtab;         // number of module table entries
 530       uint32_t extrefsymoff;    // offset to referenced symbol table
 531       uint32_t nextrefsyms;     // number of referenced symbol table entries
 532       uint32_t indirectsymoff;  // file offset to the indirect symbol table
 533       uint32_t nindirectsyms;   // number of indirect symbol table entries
 534       uint32_t extreloff;       // offset to external relocation entries
 535       uint32_t nextrel;         // number of external relocation entries
 536       uint32_t locreloff;       // offset to local relocation entries
 537       uint32_t nlocrel;         // number of local relocation entries
 538
 539       // Constants for the cmd field
 540       // see <mach-o/loader.h>
 541       enum { LC_DYSYMTAB = 0x0B  // dynamic link-edit symbol table info
 542       };
 543
 544       MachODySymTab() : cmd(LC_DYSYMTAB), cmdsize(20 * sizeof(uint32_t)),
 545         ilocalsym(0), nlocalsym(0), iextdefsym(0), nextdefsym(0),
 546         iundefsym(0), nundefsym(0), tocoff(0), ntoc(0), modtaboff(0),
 547         nmodtab(0), extrefsymoff(0), nextrefsyms(0), indirectsymoff(0),
 548         nindirectsyms(0), extreloff(0), nextrel(0), locreloff(0), nlocrel(0) { }
 549     };
 550
 551     /// SymTab - The "stab" style symbol table information
 552     MachOSymTab   SymTab;
 553     /// DySymTab - symbol table info for the dynamic link editor
 554     MachODySymTab DySymTab;
 555
 556     struct MachOSymCmp {
 557       // FIXME: this does not appear to be sorting 'f' after 'F'
 558       bool operator()(const MachOSym &LHS, const MachOSym &RHS) {
 559         return LHS.GVName < RHS.GVName;
 560       }
 561     };
 562
 563     /// PartitionByLocal - Simple boolean predicate that returns true if Sym is
 564     /// a local symbol rather than an external symbol.
 565     static bool PartitionByLocal(const MachOSym &Sym);
 566
 567     /// PartitionByDefined - Simple boolean predicate that returns true if Sym
 568     /// is defined in this module.
 569     static bool PartitionByDefined(const MachOSym &Sym);
 570
 571   protected:
 572
 573     /// SymbolTable - This is the list of symbols we have emitted to the file.
 574     /// This actually gets rearranged before emission to the file (to put the
 575     /// local symbols first in the list).
 576     std::vector<MachOSym> SymbolTable;
 577
 578     /// SymT - A buffer to hold the symbol table before we write it out at the
 579     /// appropriate location in the file.
 580     DataBuffer SymT;
 581
 582     /// StrT - A buffer to hold the string table before we write it out at the
 583     /// appropriate location in the file.
 584     DataBuffer StrT;
 585
 586     /// PendingSyms - This is a list of externally defined symbols that we have
 587     /// been asked to emit, but have not seen a reference to.  When a reference
 588     /// is seen, the symbol will move from this list to the SymbolTable.
 589     std::vector<GlobalValue*> PendingGlobals;
 590
 591     /// DynamicSymbolTable - This is just a vector of indices into
 592     /// SymbolTable to aid in emitting the DYSYMTAB load command.
 593     std::vector<unsigned> DynamicSymbolTable;
 594
 595     static void InitMem(const Constant *C, void *Addr, intptr_t Offset,
 596                         const TargetData *TD,
 597                         std::vector<MachineRelocation> &MRs);
 598
 599   private:
 600     void AddSymbolToSection(MachOSection *MOS, GlobalVariable *GV);
 601     void EmitGlobal(GlobalVariable *GV);
 602     void EmitHeaderAndLoadCommands();
 603     void EmitSections();
 604     void BufferSymbolAndStringTable();
 605     void CalculateRelocations(MachOSection &MOS);
 606
 607     MachineRelocation GetJTRelocation(unsigned Offset,
 608                                       MachineBasicBlock *MBB) const {
 609       return TM.getMachOWriterInfo()->GetJTRelocation(Offset, MBB);
 610     }
 611
 612     /// GetTargetRelocation - Returns the number of relocations.
 613     unsigned GetTargetRelocation(MachineRelocation &MR,
 614                                  unsigned FromIdx,
 615                                  unsigned ToAddr,
 616                                  unsigned ToIndex,
 617                                  OutputBuffer &RelocOut,
 618                                  OutputBuffer &SecOut,
 619                                  bool Scattered,
 620                                  bool Extern) {
 621       return TM.getMachOWriterInfo()->GetTargetRelocation(MR, FromIdx, ToAddr,
 622                                                           ToIndex, RelocOut,
 623                                                           SecOut, Scattered,
 624                                                           Extern);
 625     }
 626   };
 627 }
 628
 629 #endif