src/ld/parsers/lto_file.cpp

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
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  24
  25 #ifndef __LTO_READER_H__
  26 #define __LTO_READER_H__
  27
  28 #include <stdlib.h>
  29 #include <sys/param.h>
  30 #include <sys/fcntl.h>
  31 #include <sys/stat.h>
  32 #include <errno.h>
  33 #include <pthread.h>
  34 #include <mach-o/dyld.h>
  35 #include <vector>
  36 #include <map>
  37 #include <unordered_set>
  38 #include <unordered_map>
  39
  40 #include "MachOFileAbstraction.hpp"
  41 #include "Architectures.hpp"
  42 #include "ld.hpp"
  43 #include "macho_relocatable_file.h"
  44 #include "lto_file.h"
  45
  46 // #defines are a work around for <rdar://problem/8760268>
  47 #define __STDC_LIMIT_MACROS 1
  48 #define __STDC_CONSTANT_MACROS 1
  49 #include "llvm-c/lto.h"
  50
  51 namespace lto {
  52
  53
  54 //
  55 // ld64 only tracks non-internal symbols from an llvm bitcode file.
  56 // We model this by having an InternalAtom which represent all internal functions and data.
  57 // All non-interal symbols from a bitcode file are represented by an Atom
  58 // and each Atom has a reference to the InternalAtom.  The InternalAtom
  59 // also has references to each symbol external to the bitcode file.
  60 //
  61 class InternalAtom : public ld::Atom
  62 {
  63 public:
  64                                                                                                 InternalAtom(class File& f);
  65         // overrides of ld::Atom
  66         virtual ld::File*                                                       file() const            { return &_file; }
  67         virtual const char*                                                     name() const            { return "import-atom"; }
  68         virtual uint64_t                                                        size() const            { return 0; }
  69         virtual uint64_t                                                        objectAddress() const { return 0; }
  70         virtual void                                                            copyRawContent(uint8_t buffer[]) const { }
  71         virtual void                                                            setScope(Scope)         { }
  72         virtual ld::Fixup::iterator                                     fixupsBegin() const     { return &_undefs[0]; }
  73         virtual ld::Fixup::iterator                                     fixupsEnd()     const   { return &_undefs[_undefs.size()]; }
  74
  75         // for adding references to symbols outside bitcode file
  76         void                                                                            addReference(const char* nm)
  77                                                                                                                                         { _undefs.push_back(ld::Fixup(0, ld::Fixup::k1of1,
  78                                                                                                                                                                 ld::Fixup::kindNone, false, strdup(nm))); }
  79 private:
  80
  81         ld::File&                                                                       _file;
  82         mutable std::vector<ld::Fixup>                          _undefs;
  83 };
  84
  85
  86 //
  87 // LLVM bitcode file
  88 //
  89 class File : public ld::relocatable::File
  90 {
  91 public:
  92                                                                                         File(const char* path, time_t mTime, ld::File::Ordinal ordinal,
  93                                                                                                          const uint8_t* content, uint32_t contentLength, cpu_type_t arch);
  94         virtual                                                                 ~File();
  95
  96         // overrides of ld::File
  97         virtual bool                                                                            forEachAtom(ld::File::AtomHandler&) const;
  98         virtual bool                                                                            justInTimeforEachAtom(const char* name, ld::File::AtomHandler&) const
  99                                                                                                                                                                         { return false; }
 100         virtual uint32_t                                                                        cpuSubType() const                      { return _cpuSubType; }
 101
 102         // overrides of ld::relocatable::File
 103         virtual DebugInfoKind                                                           debugInfo()     const                   { return _debugInfo; }
 104         virtual const char*                                                                     debugInfoPath() const           { return _debugInfoPath; }
 105         virtual time_t                                                                          debugInfoModificationTime() const
 106                                                                                                                                                                         { return _debugInfoModTime; }
 107         virtual const std::vector<ld::relocatable::File::Stab>* stabs() const                   { return NULL; }
 108         virtual bool                                                                            canScatterAtoms() const         { return true; }
 109         virtual LinkerOptionsList*                                                      linkerOptions() const           { return NULL; }
 110
 111
 112         void                                                                                            release();
 113         lto_module_t                                                                            module()                                        { return _module; }
 114         class InternalAtom&                                                                     internalAtom()                          { return _internalAtom; }
 115         void                                                                                            setDebugInfo(ld::relocatable::File::DebugInfoKind k,
 116                                                                                                                                         const char* pth, time_t modTime, uint32_t subtype)
 117                                                                                                                                                                         {       _debugInfo = k;
 118                                                                                                                                                                                 _debugInfoPath = pth;
 119                                                                                                                                                                                 _debugInfoModTime = modTime;
 120                                                                                                                                                                                 _cpuSubType = subtype;}
 121
 122     static bool                                         sSupportsLocalContext;
 123     static bool                                         sHasTriedLocalContext;
 124     bool                                                mergeIntoGenerator(lto_code_gen_t generator, bool useSetModule);
 125 private:
 126         friend class Atom;
 127         friend class InternalAtom;
 128         friend class Parser;
 129
 130         cpu_type_t                                                              _architecture;
 131         class InternalAtom                                              _internalAtom;
 132         class Atom*                                                             _atomArray;
 133         uint32_t                                                                _atomArrayCount;
 134         lto_module_t                                                    _module;
 135         const char*                             _path;
 136         const uint8_t*                          _content;
 137         uint32_t                                _contentLength;
 138         const char*                                                             _debugInfoPath;
 139         time_t                                                                  _debugInfoModTime;
 140         ld::Section                                                             _section;
 141         ld::Fixup                                                               _fixupToInternal;
 142         ld::relocatable::File::DebugInfoKind    _debugInfo;
 143         uint32_t                                                                _cpuSubType;
 144 };
 145
 146 //
 147 // Atom acts as a proxy Atom for the symbols that are exported by LLVM bitcode file. Initially,
 148 // Reader creates Atoms to allow linker proceed with usual symbol resolution phase. After
 149 // optimization is performed, real Atoms are created for these symobls. However these real Atoms
 150 // are not inserted into global symbol table. Atom holds real Atom and forwards appropriate
 151 // methods to real atom.
 152 //
 153 class Atom : public ld::Atom
 154 {
 155 public:
 156                                                                                 Atom(File& f, const char* name, ld::Atom::Scope s,
 157                                                                                                 ld::Atom::Definition d, ld::Atom::Combine c, ld::Atom::Alignment a, bool ah);
 158
 159         // overrides of ld::Atom
 160         virtual ld::File*                                       file() const            { return &_file; }
 161         virtual const char*                                     translationUnitSource() const
 162                                                                                                                         { return (_compiledAtom ? _compiledAtom->translationUnitSource() : NULL); }
 163         virtual const char*                                     name() const            { return _name; }
 164         virtual uint64_t                                        size() const            { return (_compiledAtom ? _compiledAtom->size() : 0); }
 165         virtual uint64_t                                        objectAddress() const { return (_compiledAtom ? _compiledAtom->objectAddress() : 0); }
 166         virtual void                                            copyRawContent(uint8_t buffer[]) const
 167                                                                                                                         { if (_compiledAtom) _compiledAtom->copyRawContent(buffer); }
 168         virtual const uint8_t*                          rawContentPointer() const
 169                                                                                                                         { return (_compiledAtom ? _compiledAtom->rawContentPointer() : NULL);  }
 170         virtual unsigned long                           contentHash(const class ld::IndirectBindingTable& ibt) const
 171                                                                                                                         { return (_compiledAtom ? _compiledAtom->contentHash(ibt) : 0);  }
 172         virtual bool                                            canCoalesceWith(const ld::Atom& rhs, const class ld::IndirectBindingTable& ibt) const
 173                                                                                                                         { return (_compiledAtom ? _compiledAtom->canCoalesceWith(rhs,ibt) : false); }
 174         virtual ld::Fixup::iterator                             fixupsBegin() const
 175                                                                                                                         { return (_compiledAtom ? _compiledAtom->fixupsBegin() : (ld::Fixup*)&_file._fixupToInternal); }
 176         virtual ld::Fixup::iterator                             fixupsEnd() const
 177                                                                                                                         { return (_compiledAtom ? _compiledAtom->fixupsEnd() : &((ld::Fixup*)&_file._fixupToInternal)[1]); }
 178         virtual ld::Atom::UnwindInfo::iterator  beginUnwind() const
 179                                                                                                                         { return (_compiledAtom ? _compiledAtom->beginUnwind() : NULL); }
 180         virtual ld::Atom::UnwindInfo::iterator  endUnwind() const
 181                                                                                                                         { return (_compiledAtom ? _compiledAtom->endUnwind() : NULL); }
 182         virtual ld::Atom::LineInfo::iterator    beginLineInfo() const
 183                                                                                                                         { return (_compiledAtom ? _compiledAtom->beginLineInfo() : NULL); }
 184         virtual ld::Atom::LineInfo::iterator    endLineInfo() const
 185                                                                                                                         { return (_compiledAtom ? _compiledAtom->endLineInfo() : NULL); }
 186
 187         const ld::Atom*                                         compiledAtom()          { return _compiledAtom; }
 188         void                                                            setCompiledAtom(const ld::Atom& atom);
 189
 190 private:
 191
 192         File&                                                           _file;
 193         const char*                                                     _name;
 194         const ld::Atom*                                         _compiledAtom;
 195 };
 196
 197
 198
 199
 200
 201
 202
 203 class Parser
 204 {
 205 public:
 206         static bool                                             validFile(const uint8_t* fileContent, uint64_t fileLength, cpu_type_t architecture, cpu_subtype_t subarch);
 207         static const char*                              fileKind(const uint8_t* fileContent, uint64_t fileLength);
 208         static File*                                    parse(const uint8_t* fileContent, uint64_t fileLength, const char* path,
 209                                                                                         time_t modTime, ld::File::Ordinal ordinal, cpu_type_t architecture, cpu_subtype_t subarch,
 210                                                                                         bool logAllFiles, bool verboseOptimizationHints);
 211         static bool                                             libLTOisLoaded() { return (::lto_get_version() != NULL); }
 212         static bool                                             optimize(   const std::vector<const ld::Atom*>& allAtoms,
 213                                                                                                 ld::Internal&                                           state,
 214                                                                                                 const OptimizeOptions&                          options,
 215                                                                                                 ld::File::AtomHandler&                          handler,
 216                                                                                                 std::vector<const ld::Atom*>&           newAtoms,
 217                                                                                                 std::vector<const char*>&                       additionalUndefines);
 218
 219         static const char*                      ltoVersion()    { return ::lto_get_version(); }
 220
 221 private:
 222         static const char*                              tripletPrefixForArch(cpu_type_t arch);
 223         static ld::relocatable::File*   parseMachOFile(const uint8_t* p, size_t len, const OptimizeOptions& options);
 224 #if LTO_API_VERSION >= 7
 225         static void ltoDiagnosticHandler(lto_codegen_diagnostic_severity_t, const char*, void*);
 226 #endif
 227
 228         typedef std::unordered_set<const char*, ld::CStringHash, ld::CStringEquals>  CStringSet;
 229         typedef std::unordered_map<const char*, Atom*, ld::CStringHash, ld::CStringEquals> CStringToAtom;
 230
 231         class AtomSyncer : public ld::File::AtomHandler {
 232         public:
 233                                                         AtomSyncer(std::vector<const char*>& a, std::vector<const ld::Atom*>&na,
 234                                                                                 CStringToAtom la, CStringToAtom dla, const OptimizeOptions& options) :
 235                                                                                 _options(options), _additionalUndefines(a), _newAtoms(na), _llvmAtoms(la), _deadllvmAtoms(dla) { }
 236                 virtual void            doAtom(const class ld::Atom&);
 237                 virtual void            doFile(const class ld::File&) { }
 238
 239
 240                 const OptimizeOptions&                  _options;
 241                 std::vector<const char*>&               _additionalUndefines;
 242                 std::vector<const ld::Atom*>&   _newAtoms;
 243                 CStringToAtom                                   _llvmAtoms;
 244                 CStringToAtom                                   _deadllvmAtoms;
 245         };
 246
 247         static std::vector<File*>               _s_files;
 248 };
 249
 250 std::vector<File*> Parser::_s_files;
 251
 252
 253 bool Parser::validFile(const uint8_t* fileContent, uint64_t fileLength, cpu_type_t architecture, cpu_subtype_t subarch)
 254 {
 255         for (const ArchInfo* t=archInfoArray; t->archName != NULL; ++t) {
 256                 if ( (architecture == t->cpuType) && (!(t->isSubType) || (subarch == t->cpuSubType)) ) {
 257                         bool result = ::lto_module_is_object_file_in_memory_for_target(fileContent, fileLength, t->llvmTriplePrefix);
 258                         if ( !result ) {
 259                                 // <rdar://problem/8434487> LTO only supports thumbv7 not armv7
 260                                 if ( t->llvmTriplePrefixAlt[0] != '\0' ) {
 261                                         result = ::lto_module_is_object_file_in_memory_for_target(fileContent, fileLength, t->llvmTriplePrefixAlt);
 262                                 }
 263                         }
 264                         return result;
 265                 }
 266         }
 267         return false;
 268 }
 269
 270 const char* Parser::fileKind(const uint8_t* p, uint64_t fileLength)
 271 {
 272         if ( (p[0] == 0xDE) && (p[1] == 0xC0) && (p[2] == 0x17) && (p[3] == 0x0B) ) {
 273                 cpu_type_t arch = LittleEndian::get32(*((uint32_t*)(&p[16])));
 274                 for (const ArchInfo* t=archInfoArray; t->archName != NULL; ++t) {
 275                         if ( arch == t->cpuType ) {
 276                                  if ( t->isSubType ) {
 277                                         if ( ::lto_module_is_object_file_in_memory_for_target(p, fileLength, t->llvmTriplePrefix) )
 278                                                 return t->archName;
 279                                 }
 280                                 else {
 281                                         return t->archName;
 282                                 }
 283                         }
 284                 }
 285                 return "unknown bitcode architecture";
 286         }
 287         return NULL;
 288 }
 289
 290 File* Parser::parse(const uint8_t* fileContent, uint64_t fileLength, const char* path, time_t modTime, ld::File::Ordinal ordinal,
 291                                                                                                         cpu_type_t architecture, cpu_subtype_t subarch, bool logAllFiles, bool verboseOptimizationHints)
 292 {
 293         File* f = new File(path, modTime, ordinal, fileContent, fileLength, architecture);
 294         _s_files.push_back(f);
 295         if ( logAllFiles )
 296                 printf("%s\n", path);
 297         return f;
 298 }
 299
 300
 301 ld::relocatable::File* Parser::parseMachOFile(const uint8_t* p, size_t len, const OptimizeOptions& options)
 302 {
 303         mach_o::relocatable::ParserOptions objOpts;
 304         objOpts.architecture            = options.arch;
 305         objOpts.objSubtypeMustMatch = false;
 306         objOpts.logAllFiles                     = false;
 307         objOpts.warnUnwindConversionProblems    = options.needsUnwindInfoSection;
 308         objOpts.keepDwarfUnwind         = options.keepDwarfUnwind;
 309         objOpts.forceDwarfConversion = false;
 310         objOpts.neverConvertDwarf   = false;
 311         objOpts.verboseOptimizationHints = options.verboseOptimizationHints;
 312         objOpts.armUsesZeroCostExceptions = options.armUsesZeroCostExceptions;
 313         objOpts.simulator                       = options.simulator;
 314         objOpts.ignoreMismatchPlatform = options.ignoreMismatchPlatform;
 315         objOpts.platform                        = options.platform;
 316         objOpts.subType                         = 0;
 317         objOpts.srcKind                         = ld::relocatable::File::kSourceLTO;
 318         objOpts.treateBitcodeAsData = false;
 319         objOpts.usingBitcode            = options.bitcodeBundle;
 320
 321         // mach-o parsing is done in-memory, but need path for debug notes
 322         const char* path = "/tmp/lto.o";
 323         time_t modTime = 0;
 324         if ( options.tmpObjectFilePath != NULL ) {
 325                 path = options.tmpObjectFilePath;
 326                 struct stat statBuffer;
 327                 if ( stat(options.tmpObjectFilePath, &statBuffer) == 0 )
 328                         modTime = statBuffer.st_mtime;
 329         }
 330
 331         ld::relocatable::File* result = mach_o::relocatable::parse(p, len, path, modTime, ld::File::Ordinal::LTOOrdinal(), objOpts);
 332         if ( result != NULL )
 333                 return result;
 334         throw "LLVM LTO, file is not of required architecture";
 335 }
 336
 337
 338
 339 File::File(const char* pth, time_t mTime, ld::File::Ordinal ordinal, const uint8_t* content, uint32_t contentLength, cpu_type_t arch)
 340         : ld::relocatable::File(pth,mTime,ordinal), _architecture(arch), _internalAtom(*this),
 341         _atomArray(NULL), _atomArrayCount(0), _module(NULL), _path(pth),
 342         _content(content), _contentLength(contentLength), _debugInfoPath(pth),
 343         _section("__TEXT_", "__tmp_lto", ld::Section::typeTempLTO),
 344         _fixupToInternal(0, ld::Fixup::k1of1, ld::Fixup::kindNone, &_internalAtom),
 345         _debugInfo(ld::relocatable::File::kDebugInfoNone), _cpuSubType(0)
 346 {
 347         const bool log = false;
 348
 349         // create llvm module
 350 #if LTO_API_VERSION >= 11
 351         if ( sSupportsLocalContext || !sHasTriedLocalContext ) {
 352                 _module = ::lto_module_create_in_local_context(content, contentLength, pth);
 353         }
 354         if ( !sHasTriedLocalContext ) {
 355                 sHasTriedLocalContext = true;
 356                 sSupportsLocalContext = (_module != NULL);
 357         }
 358         if ( (_module == NULL) && !sSupportsLocalContext )
 359 #endif
 360 #if LTO_API_VERSION >= 9
 361         _module = ::lto_module_create_from_memory_with_path(content, contentLength, pth);
 362         if ( _module == NULL && !sSupportsLocalContext )
 363 #endif
 364         _module = ::lto_module_create_from_memory(content, contentLength);
 365     if ( _module == NULL )
 366                 throwf("could not parse object file %s: '%s', using libLTO version '%s'", pth, ::lto_get_error_message(), ::lto_get_version());
 367
 368         if ( log ) fprintf(stderr, "bitcode file: %s\n", pth);
 369
 370         // create atom for each global symbol in module
 371         uint32_t count = ::lto_module_get_num_symbols(_module);
 372         _atomArray = (Atom*)malloc(sizeof(Atom)*count);
 373         for (uint32_t i=0; i < count; ++i) {
 374                 const char* name = ::lto_module_get_symbol_name(_module, i);
 375                 lto_symbol_attributes attr = lto_module_get_symbol_attribute(_module, i);
 376
 377                 // <rdar://problem/6378110> LTO doesn't like dtrace symbols
 378                 // ignore dtrace static probes for now
 379                 // later when codegen is done and a mach-o file is produces the probes will be processed
 380                 if ( (strncmp(name, "___dtrace_probe$", 16) == 0) || (strncmp(name, "___dtrace_isenabled$", 20) == 0) )
 381                         continue;
 382
 383                 ld::Atom::Definition def;
 384                 ld::Atom::Combine combine = ld::Atom::combineNever;
 385                 switch ( attr & LTO_SYMBOL_DEFINITION_MASK ) {
 386                         case LTO_SYMBOL_DEFINITION_REGULAR:
 387                                 def = ld::Atom::definitionRegular;
 388                                 break;
 389                         case LTO_SYMBOL_DEFINITION_TENTATIVE:
 390                                 def = ld::Atom::definitionTentative;
 391                                 break;
 392                         case LTO_SYMBOL_DEFINITION_WEAK:
 393                                 def = ld::Atom::definitionRegular;
 394                                 combine = ld::Atom::combineByName;
 395                                 break;
 396                         case LTO_SYMBOL_DEFINITION_UNDEFINED:
 397                         case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
 398                                 def = ld::Atom::definitionProxy;
 399                                 break;
 400                         default:
 401                                 throwf("unknown definition kind for symbol %s in bitcode file %s", name, pth);
 402                 }
 403
 404                 // make LLVM atoms for definitions and a reference for undefines
 405                 if ( def != ld::Atom::definitionProxy ) {
 406                         ld::Atom::Scope scope;
 407                         bool autohide = false;
 408                         switch ( attr & LTO_SYMBOL_SCOPE_MASK) {
 409                                 case LTO_SYMBOL_SCOPE_INTERNAL:
 410                                         scope = ld::Atom::scopeTranslationUnit;
 411                                         break;
 412                                 case LTO_SYMBOL_SCOPE_HIDDEN:
 413                                         scope = ld::Atom::scopeLinkageUnit;
 414                                         break;
 415                                 case LTO_SYMBOL_SCOPE_DEFAULT:
 416                                         scope = ld::Atom::scopeGlobal;
 417                                         break;
 418 #if LTO_API_VERSION >= 4
 419                                 case LTO_SYMBOL_SCOPE_DEFAULT_CAN_BE_HIDDEN:
 420                                         scope = ld::Atom::scopeGlobal;
 421                                         autohide = true;
 422                                         break;
 423 #endif
 424                                 default:
 425                                         throwf("unknown scope for symbol %s in bitcode file %s", name, pth);
 426                         }
 427                         // only make atoms for non-internal symbols
 428                         if ( scope == ld::Atom::scopeTranslationUnit )
 429                                 continue;
 430                         uint8_t alignment = (attr & LTO_SYMBOL_ALIGNMENT_MASK);
 431                         // make Atom using placement new operator
 432                         new (&_atomArray[_atomArrayCount++]) Atom(*this, name, scope, def, combine, alignment, autohide);
 433                         if ( scope != ld::Atom::scopeTranslationUnit )
 434                                 _internalAtom.addReference(name);
 435                         if ( log ) fprintf(stderr, "\t0x%08X %s\n", attr, name);
 436                 }
 437                 else {
 438                         // add to list of external references
 439                         _internalAtom.addReference(name);
 440                         if ( log ) fprintf(stderr, "\t%s (undefined)\n", name);
 441                 }
 442         }
 443
 444 #if LTO_API_VERSION >= 11
 445         if ( sSupportsLocalContext )
 446                 this->release();
 447 #endif
 448 }
 449
 450 File::~File()
 451 {
 452         this->release();
 453 }
 454
 455 bool File::mergeIntoGenerator(lto_code_gen_t generator, bool useSetModule) {
 456 #if LTO_API_VERSION >= 11
 457     if ( sSupportsLocalContext ) {
 458         assert(!_module && "Expected module to be disposed");
 459         _module = ::lto_module_create_in_codegen_context(_content, _contentLength,
 460                                                         _path, generator);
 461         if ( _module == NULL )
 462             throwf("could not reparse object file %s: '%s', using libLTO version '%s'",
 463                   _path, ::lto_get_error_message(), ::lto_get_version());
 464     }
 465 #endif
 466     assert(_module && "Expected module to stick around");
 467 #if LTO_API_VERSION >= 13
 468     if (useSetModule) {
 469         // lto_codegen_set_module will transfer ownership of the module to LTO code generator,
 470         // so we don't need to release the module here.
 471         ::lto_codegen_set_module(generator, _module);
 472         return false;
 473     }
 474 #endif
 475     if ( ::lto_codegen_add_module(generator, _module) )
 476         return true;
 477
 478     // <rdar://problem/15471128> linker should release module as soon as possible
 479     this->release();
 480     return false;
 481 }
 482
 483 void File::release()
 484 {
 485         if ( _module != NULL )
 486                 ::lto_module_dispose(_module);
 487         _module = NULL;
 488 }
 489
 490 bool File::forEachAtom(ld::File::AtomHandler& handler) const
 491 {
 492         handler.doAtom(_internalAtom);
 493         for(uint32_t i=0; i < _atomArrayCount; ++i) {
 494                 handler.doAtom(_atomArray[i]);
 495         }
 496         return true;
 497 }
 498
 499 InternalAtom::InternalAtom(File& f)
 500         : ld::Atom(f._section, ld::Atom::definitionRegular, ld::Atom::combineNever, ld::Atom::scopeTranslationUnit,
 501                                 ld::Atom::typeLTOtemporary, ld::Atom::symbolTableNotIn, true, false, false, ld::Atom::Alignment(0)),
 502                 _file(f)
 503 {
 504 }
 505
 506 Atom::Atom(File& f, const char* nm, ld::Atom::Scope s, ld::Atom::Definition d, ld::Atom::Combine c,
 507                         ld::Atom::Alignment a, bool ah)
 508         : ld::Atom(f._section, d, c, s, ld::Atom::typeLTOtemporary,
 509                                 ld::Atom::symbolTableIn, false, false, false, a),
 510                 _file(f), _name(strdup(nm)), _compiledAtom(NULL)
 511 {
 512         if ( ah )
 513                 this->setAutoHide();
 514 }
 515
 516 void Atom::setCompiledAtom(const ld::Atom& atom)
 517 {
 518         // set delegate so virtual methods go to it
 519         _compiledAtom = &atom;
 520
 521         //fprintf(stderr, "setting lto atom %p to delegate to mach-o atom %p (%s)\n", this, &atom, atom.name());
 522
 523         // update fields in ld::Atom to match newly constructed mach-o atom
 524         (const_cast<Atom*>(this))->setAttributesFromAtom(atom);
 525 }
 526
 527
 528
 529 // <rdar://problem/12379604> The order that files are merged must match command line order
 530 struct CommandLineOrderFileSorter
 531 {
 532      bool operator()(File* left, File* right)
 533      {
 534         return ( left->ordinal() < right->ordinal() );
 535      }
 536 };
 537
 538
 539 #if LTO_API_VERSION >= 7
 540 void Parser::ltoDiagnosticHandler(lto_codegen_diagnostic_severity_t severity, const char* message, void*)
 541 {
 542         switch ( severity ) {
 543 #if LTO_API_VERSION >= 10
 544                 case LTO_DS_REMARK:
 545                         fprintf(stderr, "ld: LTO remark: %s\n", message);
 546                         break;
 547 #endif
 548                 case LTO_DS_NOTE:
 549                 case LTO_DS_WARNING:
 550                         warning("%s", message);
 551                         break;
 552                 case LTO_DS_ERROR:
 553                         throwf("%s", message);
 554         }
 555 }
 556 #endif
 557
 558 bool Parser::optimize(  const std::vector<const ld::Atom*>&     allAtoms,
 559                                                 ld::Internal&                                           state,
 560                                                 const OptimizeOptions&                          options,
 561                                                 ld::File::AtomHandler&                          handler,
 562                                                 std::vector<const ld::Atom*>&           newAtoms,
 563                                                 std::vector<const char*>&                       additionalUndefines)
 564 {
 565         const bool logMustPreserve = false;
 566         const bool logExtraOptions = false;
 567         const bool logBitcodeFiles = false;
 568         const bool logAtomsBeforeSync = false;
 569
 570         // exit quickly if nothing to do
 571         if ( _s_files.size() == 0 )
 572                 return false;
 573
 574         // print out LTO version string if -v was used
 575         if ( options.verbose )
 576                 fprintf(stderr, "%s\n", ::lto_get_version());
 577
 578         // create optimizer and add each Reader
 579         lto_code_gen_t generator = NULL;
 580 #if LTO_API_VERSION >= 11
 581         if ( File::sSupportsLocalContext )
 582                 generator = ::lto_codegen_create_in_local_context();
 583         else
 584 #endif
 585                 generator = ::lto_codegen_create();
 586 #if LTO_API_VERSION >= 7
 587         lto_codegen_set_diagnostic_handler(generator, ltoDiagnosticHandler, NULL);
 588 #endif
 589
 590         // <rdar://problem/12379604> The order that files are merged must match command line order
 591         std::sort(_s_files.begin(), _s_files.end(), CommandLineOrderFileSorter());
 592         ld::File::Ordinal lastOrdinal;
 593
 594         // When flto_codegen_only is on and we have a single .bc file, use lto_codegen_set_module instead of
 595         // lto_codegen_add_module, to make sure the the destination module will be the same as the input .bc file.
 596         bool useSetModule = false;
 597 #if LTO_API_VERSION >= 13
 598         useSetModule = (_s_files.size() == 1) && options.ltoCodegenOnly && (::lto_api_version() >= 13);
 599 #endif
 600         for (std::vector<File*>::iterator it=_s_files.begin(); it != _s_files.end(); ++it) {
 601                 File* f = *it;
 602                 assert(f->ordinal() > lastOrdinal);
 603                 if ( logBitcodeFiles && !useSetModule) fprintf(stderr, "lto_codegen_add_module(%s)\n", f->path());
 604                 if ( logBitcodeFiles && useSetModule) fprintf(stderr, "lto_codegen_set_module(%s)\n", f->path());
 605                 if ( f->mergeIntoGenerator(generator, useSetModule) )
 606                         throwf("lto: could not merge in %s because '%s', using libLTO version '%s'", f->path(), ::lto_get_error_message(), ::lto_get_version());
 607                 lastOrdinal = f->ordinal();
 608         }
 609
 610         // add any -mllvm command line options
 611         for (std::vector<const char*>::const_iterator it=options.llvmOptions->begin(); it != options.llvmOptions->end(); ++it) {
 612                 if ( logExtraOptions ) fprintf(stderr, "passing option to llvm: %s\n", *it);
 613                 ::lto_codegen_debug_options(generator, *it);
 614         }
 615
 616         // <rdar://problem/13687397> Need a way for LTO to get cpu variants (until that info is in bitcode)
 617         if ( options.mcpu != NULL )
 618                 ::lto_codegen_set_cpu(generator, options.mcpu);
 619
 620         // The atom graph uses directed edges (references). Collect all references where
 621         // originating atom is not part of any LTO Reader. This allows optimizer to optimize an
 622         // external (i.e. not originated from same .o file) reference if all originating atoms are also
 623         // defined in llvm bitcode file.
 624         CStringSet nonLLVMRefs;
 625         CStringToAtom llvmAtoms;
 626     bool hasNonllvmAtoms = false;
 627         for (std::vector<const ld::Atom*>::const_iterator it = allAtoms.begin(); it != allAtoms.end(); ++it) {
 628                 const ld::Atom* atom = *it;
 629                 // only look at references that come from an atom that is not an llvm atom
 630                 if ( atom->contentType() != ld::Atom::typeLTOtemporary ) {
 631                         if ( (atom->section().type() != ld::Section::typeMachHeader) && (atom->definition() != ld::Atom::definitionProxy) ) {
 632                                 hasNonllvmAtoms = true;
 633                         }
 634                         const ld::Atom* target;
 635                         for (ld::Fixup::iterator fit=atom->fixupsBegin(); fit != atom->fixupsEnd(); ++fit) {
 636                                 switch ( fit->binding ) {
 637                                         case ld::Fixup::bindingDirectlyBound:
 638                                                 // that reference an llvm atom
 639                                                 if ( fit->u.target->contentType() == ld::Atom::typeLTOtemporary )
 640                                                         nonLLVMRefs.insert(fit->u.target->name());
 641                                                 break;
 642                                         case ld::Fixup::bindingsIndirectlyBound:
 643                                                 target = state.indirectBindingTable[fit->u.bindingIndex];
 644                                                 if ( (target != NULL) && (target->contentType() == ld::Atom::typeLTOtemporary) )
 645                                                         nonLLVMRefs.insert(target->name());
 646                                         default:
 647                                                 break;
 648                                 }
 649                         }
 650                 }
 651                 else if ( atom->scope() >= ld::Atom::scopeLinkageUnit ) {
 652                         llvmAtoms[atom->name()] = (Atom*)atom;
 653                 }
 654         }
 655         // if entry point is in a llvm bitcode file, it must be preserved by LTO
 656         if ( state.entryPoint!= NULL ) {
 657                 if ( state.entryPoint->contentType() == ld::Atom::typeLTOtemporary )
 658                         nonLLVMRefs.insert(state.entryPoint->name());
 659         }
 660
 661         // deadAtoms are the atoms that the linker coalesced.  For instance weak or tentative definitions
 662         // overriden by another atom.  If any of these deadAtoms are llvm atoms and they were replaced
 663         // with a mach-o atom, we need to tell the lto engine to preserve (not optimize away) its dead
 664         // atom so that the linker can replace it with the mach-o one later.
 665         CStringToAtom deadllvmAtoms;
 666         for (std::vector<const ld::Atom*>::const_iterator it = allAtoms.begin(); it != allAtoms.end(); ++it) {
 667                 const ld::Atom* atom = *it;
 668                 if ( atom->coalescedAway() && (atom->contentType() == ld::Atom::typeLTOtemporary) ) {
 669                         const char* name = atom->name();
 670                         if ( logMustPreserve ) fprintf(stderr, "lto_codegen_add_must_preserve_symbol(%s) because linker coalesce away and replace with a mach-o atom\n", name);
 671                         ::lto_codegen_add_must_preserve_symbol(generator, name);
 672                         deadllvmAtoms[name] = (Atom*)atom;
 673                 }
 674         }
 675         for (std::vector<File*>::iterator it=_s_files.begin(); it != _s_files.end(); ++it) {
 676                 File* file = *it;
 677                 for(uint32_t i=0; i < file->_atomArrayCount; ++i) {
 678                         Atom* llvmAtom = &file->_atomArray[i];
 679                         if ( llvmAtom->coalescedAway()  ) {
 680                                 const char* name = llvmAtom->name();
 681                                 if ( deadllvmAtoms.find(name) == deadllvmAtoms.end() ) {
 682                                         if ( logMustPreserve )
 683                                                 fprintf(stderr, "lto_codegen_add_must_preserve_symbol(%s) because linker coalesce away and replace with a mach-o atom\n", name);
 684                                         ::lto_codegen_add_must_preserve_symbol(generator, name);
 685                                         deadllvmAtoms[name] = (Atom*)llvmAtom;
 686                                 }
 687                         }
 688                         else if ( options.linkerDeadStripping && !llvmAtom->live() ) {
 689                                 const char* name = llvmAtom->name();
 690                                 deadllvmAtoms[name] = (Atom*)llvmAtom;
 691                         }
 692                 }
 693         }
 694
 695         // tell code generator about symbols that must be preserved
 696         for (CStringToAtom::iterator it = llvmAtoms.begin(); it != llvmAtoms.end(); ++it) {
 697                 const char* name = it->first;
 698                 Atom* atom = it->second;
 699                 // Include llvm Symbol in export list if it meets one of following two conditions
 700                 // 1 - atom scope is global (and not linkage unit).
 701                 // 2 - included in nonLLVMRefs set.
 702                 // If a symbol is not listed in exportList then LTO is free to optimize it away.
 703                 if ( (atom->scope() == ld::Atom::scopeGlobal) && options.preserveAllGlobals ) {
 704                         if ( logMustPreserve ) fprintf(stderr, "lto_codegen_add_must_preserve_symbol(%s) because global symbol\n", name);
 705                         ::lto_codegen_add_must_preserve_symbol(generator, name);
 706                 }
 707                 else if ( nonLLVMRefs.find(name) != nonLLVMRefs.end() ) {
 708                         if ( logMustPreserve ) fprintf(stderr, "lto_codegen_add_must_preserve_symbol(%s) because referenced by a mach-o atom\n", name);
 709                         ::lto_codegen_add_must_preserve_symbol(generator, name);
 710                 }
 711                 else if ( options.relocatable && hasNonllvmAtoms ) {
 712                         // <rdar://problem/14334895> ld -r mode but merging in some mach-o files, so need to keep libLTO from optimizing away anything
 713                         if ( logMustPreserve ) fprintf(stderr, "lto_codegen_add_must_preserve_symbol(%s) because -r mode disable LTO dead stripping\n", name);
 714                         ::lto_codegen_add_must_preserve_symbol(generator, name);
 715                 }
 716         }
 717
 718         // <rdar://problem/16165191> tell code generator to preserve initial undefines
 719         for( std::vector<const char*>::const_iterator it=options.initialUndefines->begin(); it != options.initialUndefines->end(); ++it) {
 720                 if ( logMustPreserve ) fprintf(stderr, "lto_codegen_add_must_preserve_symbol(%s) because it is an initial undefine\n", *it);
 721                 ::lto_codegen_add_must_preserve_symbol(generator, *it);
 722         }
 723
 724     // special case running ld -r on all bitcode files to produce another bitcode file (instead of mach-o)
 725     if ( options.relocatable && !hasNonllvmAtoms ) {
 726 #if LTO_API_VERSION >= 15
 727                 ::lto_codegen_set_should_embed_uselists(generator, false);
 728 #endif
 729                 if ( ! ::lto_codegen_write_merged_modules(generator, options.outputFilePath) ) {
 730                         // HACK, no good way to tell linker we are all done, so just quit
 731                         exit(0);
 732                 }
 733                 warning("could not produce merged bitcode file");
 734     }
 735
 736         // set code-gen model
 737         lto_codegen_model model = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
 738         if ( options.mainExecutable ) {
 739                 if ( options.staticExecutable ) {
 740                         // x86_64 "static" or any "-static -pie" is really dynamic code model
 741                         if ( (options.arch == CPU_TYPE_X86_64) || options.pie )
 742                                 model = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
 743                         else
 744                                 model = LTO_CODEGEN_PIC_MODEL_STATIC;
 745                 }
 746                 else {
 747                         if ( options.pie )
 748                                 model = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
 749                         else
 750                                 model = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
 751                 }
 752         }
 753         else {
 754                 if ( options.allowTextRelocs )
 755                         model = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
 756                 else
 757                         model = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
 758         }
 759         if ( ::lto_codegen_set_pic_model(generator, model) )
 760                 throwf("could not create set codegen model: %s", lto_get_error_message());
 761
 762     // if requested, save off merged bitcode file
 763     if ( options.saveTemps ) {
 764         char tempBitcodePath[MAXPATHLEN];
 765         strcpy(tempBitcodePath, options.outputFilePath);
 766         strcat(tempBitcodePath, ".lto.bc");
 767 #if LTO_API_VERSION >= 15
 768         ::lto_codegen_set_should_embed_uselists(generator, true);
 769 #endif
 770         ::lto_codegen_write_merged_modules(generator, tempBitcodePath);
 771     }
 772
 773 #if LTO_API_VERSION >= 3
 774         // find assembler next to linker
 775         char path[PATH_MAX];
 776         uint32_t bufSize = PATH_MAX;
 777         if ( _NSGetExecutablePath(path, &bufSize) != -1 ) {
 778                 char* lastSlash = strrchr(path, '/');
 779                 if ( lastSlash != NULL ) {
 780                         strcpy(lastSlash+1, "as");
 781                         struct stat statInfo;
 782                         if ( stat(path, &statInfo) == 0 )
 783                                 ::lto_codegen_set_assembler_path(generator, path);
 784                 }
 785         }
 786 #endif
 787
 788         // When lto API version is greater than or equal to 12, we use lto_codegen_optimize and lto_codegen_compile_optimized
 789         // instead of lto_codegen_compile, and we save the merged bitcode file in between.
 790         bool useSplitAPI = false;
 791 #if LTO_API_VERSION >= 12
 792         if ( ::lto_api_version() >= 12)
 793                 useSplitAPI = true;
 794 #endif
 795
 796         size_t machOFileLen = 0;
 797         const uint8_t* machOFile = NULL;
 798         if ( useSplitAPI) {
 799 #if LTO_API_VERSION >= 12
 800 #if LTO_API_VERSION >= 14
 801         if ( ::lto_api_version() >= 14 && options.ltoCodegenOnly)
 802           lto_codegen_set_should_internalize(generator, false);
 803 #endif
 804                 // run optimizer
 805                 if ( !options.ltoCodegenOnly && ::lto_codegen_optimize(generator) )
 806                         throwf("could not do LTO optimization: '%s', using libLTO version '%s'", ::lto_get_error_message(), ::lto_get_version());
 807
 808                 if ( options.saveTemps || options.bitcodeBundle ) {
 809                         // save off merged bitcode file
 810                         char tempOptBitcodePath[MAXPATHLEN];
 811                         strcpy(tempOptBitcodePath, options.outputFilePath);
 812                         strcat(tempOptBitcodePath, ".lto.opt.bc");
 813 #if LTO_API_VERSION >= 15
 814                         ::lto_codegen_set_should_embed_uselists(generator, true);
 815 #endif
 816                         ::lto_codegen_write_merged_modules(generator, tempOptBitcodePath);
 817                         if ( options.bitcodeBundle )
 818                                 state.ltoBitcodePath = tempOptBitcodePath;
 819                 }
 820
 821                 // run code generator
 822                 machOFile = (uint8_t*)::lto_codegen_compile_optimized(generator, &machOFileLen);
 823 #endif
 824                 if ( machOFile == NULL )
 825                         throwf("could not do LTO codegen: '%s', using libLTO version '%s'", ::lto_get_error_message(), ::lto_get_version());
 826         }
 827         else {
 828                 // run optimizer and code generator
 829                 machOFile = (uint8_t*)::lto_codegen_compile(generator, &machOFileLen);
 830                 if ( machOFile == NULL )
 831                         throwf("could not do LTO codegen: '%s', using libLTO version '%s'", ::lto_get_error_message(), ::lto_get_version());
 832                 if ( options.saveTemps ) {
 833                         // save off merged bitcode file
 834                         char tempOptBitcodePath[MAXPATHLEN];
 835                         strcpy(tempOptBitcodePath, options.outputFilePath);
 836                         strcat(tempOptBitcodePath, ".lto.opt.bc");
 837 #if LTO_API_VERSION >= 15
 838                         ::lto_codegen_set_should_embed_uselists(generator, true);
 839 #endif
 840                         ::lto_codegen_write_merged_modules(generator, tempOptBitcodePath);
 841                 }
 842         }
 843
 844     // if requested, save off temp mach-o file
 845     if ( options.saveTemps ) {
 846         char tempMachoPath[MAXPATHLEN];
 847         strcpy(tempMachoPath, options.outputFilePath);
 848         strcat(tempMachoPath, ".lto.o");
 849         int fd = ::open(tempMachoPath, O_CREAT | O_WRONLY | O_TRUNC, 0666);
 850                 if ( fd != -1) {
 851                         ::write(fd, machOFile, machOFileLen);
 852                         ::close(fd);
 853                 }
 854         }
 855
 856         // if needed, save temp mach-o file to specific location
 857         if ( options.tmpObjectFilePath != NULL ) {
 858                 int fd = ::open(options.tmpObjectFilePath, O_CREAT | O_WRONLY | O_TRUNC, 0666);
 859                 if ( fd != -1) {
 860                         ::write(fd, machOFile, machOFileLen);
 861                         ::close(fd);
 862                 }
 863                 else {
 864                         warning("could not write LTO temp file '%s', errno=%d", options.tmpObjectFilePath, errno);
 865                 }
 866         }
 867
 868         // parse generated mach-o file into a MachOReader
 869         ld::relocatable::File* machoFile = parseMachOFile(machOFile, machOFileLen, options);
 870
 871         // sync generated mach-o atoms with existing atoms ld knows about
 872         if ( logAtomsBeforeSync ) {
 873                 fprintf(stderr, "llvmAtoms:\n");
 874                 for (CStringToAtom::iterator it = llvmAtoms.begin(); it != llvmAtoms.end(); ++it) {
 875                         const char* name = it->first;
 876                         Atom* atom = it->second;
 877                         fprintf(stderr, "\t%p\t%s\n", atom, name);
 878                 }
 879                 fprintf(stderr, "deadllvmAtoms:\n");
 880                 for (CStringToAtom::iterator it = deadllvmAtoms.begin(); it != deadllvmAtoms.end(); ++it) {
 881                         const char* name = it->first;
 882                         Atom* atom = it->second;
 883                         fprintf(stderr, "\t%p\t%s\n", atom, name);
 884                 }
 885         }
 886         AtomSyncer syncer(additionalUndefines, newAtoms, llvmAtoms, deadllvmAtoms, options);
 887         machoFile->forEachAtom(syncer);
 888
 889         // Remove InternalAtoms from ld
 890         for (std::vector<File*>::iterator it=_s_files.begin(); it != _s_files.end(); ++it) {
 891                 (*it)->internalAtom().setCoalescedAway();
 892         }
 893         // Remove Atoms from ld if code generator optimized them away
 894         for (CStringToAtom::iterator li = llvmAtoms.begin(), le = llvmAtoms.end(); li != le; ++li) {
 895                 // check if setRealAtom() called on this Atom
 896                 if ( li->second->compiledAtom() == NULL ) {
 897                         //fprintf(stderr, "llvm optimized away %p %s\n", li->second, li->second->name());
 898                         li->second->setCoalescedAway();
 899                 }
 900         }
 901
 902         // notify about file level attributes
 903         handler.doFile(*machoFile);
 904
 905         // if final mach-o file has debug info, update original bitcode files to match
 906         for (std::vector<File*>::iterator it=_s_files.begin(); it != _s_files.end(); ++it) {
 907                 (*it)->setDebugInfo(machoFile->debugInfo(), machoFile->path(),
 908                                                         machoFile->modificationTime(), machoFile->cpuSubType());
 909         }
 910
 911         return true;
 912 }
 913
 914
 915 void Parser::AtomSyncer::doAtom(const ld::Atom& machoAtom)
 916 {
 917         static const bool log = false;
 918         static const ld::Atom* lastProxiedAtom = NULL;
 919         static const ld::File* lastProxiedFile = NULL;
 920         // update proxy atoms to point to real atoms and find new atoms
 921         const char* name = machoAtom.name();
 922         CStringToAtom::iterator pos = _llvmAtoms.find(name);
 923         if ( pos != _llvmAtoms.end() ) {
 924                 // turn Atom into a proxy for this mach-o atom
 925                 pos->second->setCompiledAtom(machoAtom);
 926                 lastProxiedAtom = &machoAtom;
 927                 lastProxiedFile = pos->second->file();
 928                 if (log) fprintf(stderr, "AtomSyncer, mach-o atom %p synced to lto atom %p (name=%s)\n", &machoAtom, pos->second, machoAtom.name());
 929         }
 930         else {
 931                 // an atom of this name was not in the allAtoms list the linker gave us
 932                 if ( _deadllvmAtoms.find(name) != _deadllvmAtoms.end() ) {
 933                         // this corresponding to an atom that the linker coalesced away or marked not-live
 934                         if ( _options.linkerDeadStripping ) {
 935                                 // llvm seems to want this atom and -dead_strip is enabled, so it will be deleted if not needed, so add back
 936                                 Atom* llvmAtom = _deadllvmAtoms[name];
 937                                 llvmAtom->setCompiledAtom(machoAtom);
 938                                 _newAtoms.push_back(&machoAtom);
 939                                 if (log) fprintf(stderr, "AtomSyncer, mach-o atom %p matches dead lto atom %p but adding back (name=%s)\n", &machoAtom, llvmAtom, machoAtom.name());
 940                         }
 941                         else {
 942                                 // Don't pass it back as a new atom
 943                                 if (log) fprintf(stderr, "AtomSyncer, mach-o atom %p matches dead lto atom %p (name=%s)\n", &machoAtom, _deadllvmAtoms[name], machoAtom.name());
 944                         }
 945                 }
 946                 else
 947                 {
 948                         // this is something new that lto conjured up, tell ld its new
 949                         _newAtoms.push_back(&machoAtom);
 950                         // <rdar://problem/15469363> if new static atom in same section as previous non-static atom, assign to same file as previous
 951                         if ( (lastProxiedAtom != NULL) && (lastProxiedAtom->section() == machoAtom.section()) ) {
 952                                 ld::Atom* ma = const_cast<ld::Atom*>(&machoAtom);
 953                                 ma->setFile(lastProxiedFile);
 954                         }
 955                         if (log) fprintf(stderr, "AtomSyncer, mach-o atom %p is totally new (name=%s)\n", &machoAtom, machoAtom.name());
 956                 }
 957         }
 958
 959         // adjust fixups to go through proxy atoms
 960         if (log) fprintf(stderr, "  adjusting fixups in atom: %s\n", machoAtom.name());
 961         for (ld::Fixup::iterator fit=machoAtom.fixupsBegin(); fit != machoAtom.fixupsEnd(); ++fit) {
 962                 switch ( fit->binding ) {
 963                         case ld::Fixup::bindingNone:
 964                                 break;
 965                         case ld::Fixup::bindingByNameUnbound:
 966                                 // don't know if this target has been seen by linker before or if it is new
 967                                 // be conservative and tell linker it is new
 968                                 _additionalUndefines.push_back(fit->u.name);
 969                                 if (log) fprintf(stderr, "    adding by-name symbol %s\n", fit->u.name);
 970                                 break;
 971                         case ld::Fixup::bindingDirectlyBound:
 972                                 // If mach-o atom is referencing another mach-o atom then
 973                                 // reference is not going through Atom proxy. Fix it here to ensure that all
 974                                 // llvm symbol references always go through Atom proxy.
 975                                 {
 976                                         const char* targetName = fit->u.target->name();
 977                                         CStringToAtom::iterator post = _llvmAtoms.find(targetName);
 978                                         if ( post != _llvmAtoms.end() ) {
 979                                                 const ld::Atom* t = post->second;
 980                                                 if (log) fprintf(stderr, "    updating direct reference to %p to be ref to %p: %s\n", fit->u.target, t, targetName);
 981                                                 fit->u.target = t;
 982                                         }
 983                                         else {
 984                                                 // <rdar://problem/12859831> Don't unbind follow-on reference into by-name reference
 985                                                 if ( (_deadllvmAtoms.find(targetName) != _deadllvmAtoms.end()) && (fit->kind != ld::Fixup::kindNoneFollowOn) && (fit->u.target->scope() != ld::Atom::scopeTranslationUnit) ) {
 986                                                         // target was coalesed away and replace by mach-o atom from a non llvm .o file
 987                                                         fit->binding = ld::Fixup::bindingByNameUnbound;
 988                                                         fit->u.name = targetName;
 989                                                 }
 990                                         }
 991                                 }
 992                                 //fprintf(stderr, "    direct ref to: %s (scope=%d)\n", fit->u.target->name(), fit->u.target->scope());
 993                                 break;
 994                         case ld::Fixup::bindingByContentBound:
 995                                 //fprintf(stderr, "    direct by content to: %s\n", fit->u.target->name());
 996                                 break;
 997                         case ld::Fixup::bindingsIndirectlyBound:
 998                                 assert(0 && "indirect binding found in initial mach-o file?");
 999                                 //fprintf(stderr, "    indirect by content to: %u\n", fit->u.bindingIndex);
1000                                 break;
1001                 }
1002         }
1003
1004 }
1005
1006 class Mutex {
1007         static pthread_mutex_t lto_lock;
1008 public:
1009         Mutex() { pthread_mutex_lock(&lto_lock); }
1010         ~Mutex() { pthread_mutex_unlock(&lto_lock); }
1011 };
1012 pthread_mutex_t Mutex::lto_lock = PTHREAD_MUTEX_INITIALIZER;
1013 bool File::sSupportsLocalContext = false;
1014 bool File::sHasTriedLocalContext = false;
1015
1016 //
1017 // Used by archive reader to see if member is an llvm bitcode file
1018 //
1019 bool isObjectFile(const uint8_t* fileContent, uint64_t fileLength, cpu_type_t architecture, cpu_subtype_t subarch)
1020 {
1021         Mutex lock;
1022         return Parser::validFile(fileContent, fileLength, architecture, subarch);
1023 }
1024
1025
1026 static ld::relocatable::File *parseImpl(
1027           const uint8_t *fileContent, uint64_t fileLength, const char *path,
1028           time_t modTime, ld::File::Ordinal ordinal, cpu_type_t architecture,
1029           cpu_subtype_t subarch, bool logAllFiles,
1030           bool verboseOptimizationHints)
1031 {
1032         if ( Parser::validFile(fileContent, fileLength, architecture, subarch) )
1033                 return Parser::parse(fileContent, fileLength, path, modTime, ordinal, architecture, subarch, logAllFiles, verboseOptimizationHints);
1034         else
1035                 return NULL;
1036 }
1037
1038 //
1039 // main function used by linker to instantiate ld::Files
1040 //
1041 ld::relocatable::File* parse(const uint8_t* fileContent, uint64_t fileLength,
1042                                                                 const char* path, time_t modTime, ld::File::Ordinal ordinal,
1043                                                                 cpu_type_t architecture, cpu_subtype_t subarch, bool logAllFiles,
1044                                                                 bool verboseOptimizationHints)
1045 {
1046         // Note: Once lto_module_create_in_local_context() and friends are thread safe
1047         // this lock can be removed.
1048         Mutex lock;
1049         return parseImpl(fileContent, fileLength, path, modTime, ordinal,
1050                                         architecture, subarch, logAllFiles,
1051                                         verboseOptimizationHints);
1052 }
1053
1054 //
1055 // used by "ld -v" to report version of libLTO.dylib being used
1056 //
1057 const char* version()
1058 {
1059         Mutex lock;
1060         return ::lto_get_version();
1061 }
1062
1063
1064 //
1065 // used by ld for error reporting
1066 //
1067 bool libLTOisLoaded()
1068 {
1069         Mutex lock;
1070         return (::lto_get_version() != NULL);
1071 }
1072
1073 //
1074 // used by ld for error reporting
1075 //
1076 const char* archName(const uint8_t* fileContent, uint64_t fileLength)
1077 {
1078         Mutex lock;
1079         return Parser::fileKind(fileContent, fileLength);
1080 }
1081
1082 //
1083 // used by ld for doing link time optimization
1084 //
1085 bool optimize(  const std::vector<const ld::Atom*>&     allAtoms,
1086                                 ld::Internal&                                           state,
1087                                 const OptimizeOptions&                          options,
1088                                 ld::File::AtomHandler&                          handler,
1089                                 std::vector<const ld::Atom*>&           newAtoms,
1090                                 std::vector<const char*>&                       additionalUndefines)
1091 {
1092         Mutex lock;
1093         return Parser::optimize(allAtoms, state, options, handler, newAtoms, additionalUndefines);
1094 }
1095
1096
1097
1098 }; // namespace lto
1099
1100
1101 #endif
1102