src/ld/parsers/lto_file.cpp

   1 /* -*- mode: C++; c-basic-offset: 4; tab-width: 4 -*-
   2  *
   3  * Copyright (c) 2006-2010 Apple Inc. All rights reserved.
   4  *
   5  * @APPLE_LICENSE_HEADER_START@
   6  *
   7  * This file contains Original Code and/or Modifications of Original Code
   8  * as defined in and that are subject to the Apple Public Source License
   9  * Version 2.0 (the 'License'). You may not use this file except in
  10  * compliance with the License. Please obtain a copy of the License at
  11  * http://www.opensource.apple.com/apsl/ and read it before using this
  12  * file.
  13  *
  14  * The Original Code and all software distributed under the License are
  15  * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
  16  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
  17  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
  19  * Please see the License for the specific language governing rights and
  20  * limitations under the License.
  21  *
  22  * @APPLE_LICENSE_HEADER_END@
  23  */
  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 <mach-o/dyld.h>
  34 #include <vector>
  35 #include <ext/hash_set>
  36 #include <ext/hash_map>
  37
  38 #include "MachOFileAbstraction.hpp"
  39 #include "Architectures.hpp"
  40 #include "ld.hpp"
  41 #include "macho_relocatable_file.h"
  42 #include "lto_file.h"
  43
  44 // #defines are a work around for <rdar://problem/8760268>
  45 #define __STDC_LIMIT_MACROS 1
  46 #define __STDC_CONSTANT_MACROS 1
  47 #include "llvm-c/lto.h"
  48
  49
  50 namespace lto {
  51
  52
  53 //
  54 // ld64 only tracks non-internal symbols from an llvm bitcode file.
  55 // We model this by having an InternalAtom which represent all internal functions and data.
  56 // All non-interal symbols from a bitcode file are represented by an Atom
  57 // and each Atom has a reference to the InternalAtom.  The InternalAtom
  58 // also has references to each symbol external to the bitcode file.
  59 //
  60 class InternalAtom : public ld::Atom
  61 {
  62 public:
  63                                                                                                 InternalAtom(class File& f);
  64         // overrides of ld::Atom
  65         virtual ld::File*                                                       file() const            { return &_file; }
  66         virtual bool                                                            translationUnitSource(const char** dir, const char** nm) const
  67                                                                                                                                         { return false; }
  68         virtual const char*                                                     name() const            { return "import-atom"; }
  69         virtual uint64_t                                                        size() const            { return 0; }
  70         virtual uint64_t                                                        objectAddress() const { return 0; }
  71         virtual void                                                            copyRawContent(uint8_t buffer[]) const { }
  72         virtual void                                                            setScope(Scope)         { }
  73         virtual ld::Fixup::iterator                                     fixupsBegin() const     { return &_undefs[0]; }
  74         virtual ld::Fixup::iterator                                     fixupsEnd()     const   { return &_undefs[_undefs.size()]; }
  75
  76         // for adding references to symbols outside bitcode file
  77         void                                                                            addReference(const char* nm)
  78                                                                                                                                         { _undefs.push_back(ld::Fixup(0, ld::Fixup::k1of1,
  79                                                                                                                                                                 ld::Fixup::kindNone, false, nm)); }
  80 private:
  81
  82         ld::File&                                                                       _file;
  83         mutable std::vector<ld::Fixup>                          _undefs;
  84 };
  85
  86
  87 //
  88 // LLVM bitcode file
  89 //
  90 class File : public ld::relocatable::File
  91 {
  92 public:
  93                                                                                         File(const char* path, time_t mTime, const uint8_t* content,
  94                                                                                                         uint32_t contentLength, uint32_t ordinal, cpu_type_t arch);
  95         virtual                                                                 ~File();
  96
  97         // overrides of ld::File
  98         virtual bool                                                                            forEachAtom(ld::File::AtomHandler&) const;
  99         virtual bool                                                                            justInTimeforEachAtom(const char* name, ld::File::AtomHandler&) const
 100                                                                                                                                                                         { return false; }
 101         virtual uint32_t                                                                        cpuSubType() const                      { return _cpuSubType; }
 102
 103         // overrides of ld::relocatable::File
 104         virtual bool                                                                            objcReplacementClasses() const  { return false; }
 105         virtual DebugInfoKind                                                           debugInfo()     const                   { return _debugInfo; }
 106         virtual const char*                                                                     debugInfoPath() const           { return _debugInfoPath; }
 107         virtual time_t                                                                          debugInfoModificationTime() const
 108                                                                                                                                                                         { return _debugInfoModTime; }
 109         virtual const std::vector<ld::relocatable::File::Stab>* stabs() const                   { return NULL; }
 110         virtual bool                                                                            canScatterAtoms() const         { return true; }
 111
 112         lto_module_t                                                                            module()                                        { return _module; }
 113         class InternalAtom&                                                                     internalAtom()                          { return _internalAtom; }
 114         void                                                                                            setDebugInfo(ld::relocatable::File::DebugInfoKind k,
 115                                                                                                                                         const char* pth, time_t modTime, uint32_t subtype)
 116                                                                                                                                                                         {       _debugInfo = k;
 117                                                                                                                                                                                 _debugInfoPath = pth;
 118                                                                                                                                                                                 _debugInfoModTime = modTime;
 119                                                                                                                                                                                 _cpuSubType = subtype;}
 120
 121 private:
 122         friend class Atom;
 123         friend class InternalAtom;
 124         friend class Parser;
 125
 126         cpu_type_t                                                              _architecture;
 127         class InternalAtom                                              _internalAtom;
 128         class Atom*                                                             _atomArray;
 129         uint32_t                                                                _atomArrayCount;
 130         lto_module_t                                                    _module;
 131         const char*                                                             _debugInfoPath;
 132         time_t                                                                  _debugInfoModTime;
 133         ld::Section                                                             _section;
 134         ld::Fixup                                                               _fixupToInternal;
 135         ld::relocatable::File::DebugInfoKind    _debugInfo;
 136         uint32_t                                                                _cpuSubType;
 137 };
 138
 139 //
 140 // Atom acts as a proxy Atom for the symbols that are exported by LLVM bitcode file. Initially,
 141 // Reader creates Atoms to allow linker proceed with usual symbol resolution phase. After
 142 // optimization is performed, real Atoms are created for these symobls. However these real Atoms
 143 // are not inserted into global symbol table. Atom holds real Atom and forwards appropriate
 144 // methods to real atom.
 145 //
 146 class Atom : public ld::Atom
 147 {
 148 public:
 149                                                                                 Atom(File& f, const char* name, ld::Atom::Scope s,
 150                                                                                                 ld::Atom::Definition d, ld::Atom::Combine c, ld::Atom::Alignment a);
 151
 152         // overrides of ld::Atom
 153         virtual ld::File*                                       file() const            { return &_file; }
 154         virtual bool                                            translationUnitSource(const char** dir, const char** nm) const
 155                                                                                                                         { return (_compiledAtom ? _compiledAtom->translationUnitSource(dir, nm) : false); }
 156         virtual const char*                                     name() const            { return _name; }
 157         virtual uint64_t                                        size() const            { return (_compiledAtom ? _compiledAtom->size() : 0); }
 158         virtual uint64_t                                        objectAddress() const { return (_compiledAtom ? _compiledAtom->objectAddress() : 0); }
 159         virtual void                                            copyRawContent(uint8_t buffer[]) const
 160                                                                                                                         { if (_compiledAtom) _compiledAtom->copyRawContent(buffer); }
 161         virtual const uint8_t*                          rawContentPointer() const
 162                                                                                                                         { return (_compiledAtom ? _compiledAtom->rawContentPointer() : NULL);  }
 163         virtual unsigned long                           contentHash(const class ld::IndirectBindingTable& ibt) const
 164                                                                                                                         { return (_compiledAtom ? _compiledAtom->contentHash(ibt) : 0);  }
 165         virtual bool                                            canCoalesceWith(const ld::Atom& rhs, const class ld::IndirectBindingTable& ibt) const
 166                                                                                                                         { return (_compiledAtom ? _compiledAtom->canCoalesceWith(rhs,ibt) : false); }
 167         virtual ld::Fixup::iterator                             fixupsBegin() const
 168                                                                                                                         { return (_compiledAtom ? _compiledAtom->fixupsBegin() : (ld::Fixup*)&_file._fixupToInternal); }
 169         virtual ld::Fixup::iterator                             fixupsEnd() const
 170                                                                                                                         { return (_compiledAtom ? _compiledAtom->fixupsEnd() : &((ld::Fixup*)&_file._fixupToInternal)[1]); }
 171         virtual ld::Atom::UnwindInfo::iterator  beginUnwind() const
 172                                                                                                                         { return (_compiledAtom ? _compiledAtom->beginUnwind() : NULL); }
 173         virtual ld::Atom::UnwindInfo::iterator  endUnwind() const
 174                                                                                                                         { return (_compiledAtom ? _compiledAtom->endUnwind() : NULL); }
 175         virtual ld::Atom::LineInfo::iterator    beginLineInfo() const
 176                                                                                                                         { return (_compiledAtom ? _compiledAtom->beginLineInfo() : NULL); }
 177         virtual ld::Atom::LineInfo::iterator    endLineInfo() const
 178                                                                                                                         { return (_compiledAtom ? _compiledAtom->endLineInfo() : NULL); }
 179
 180         const ld::Atom*                                         compiledAtom()          { return _compiledAtom; }
 181         void                                                            setCompiledAtom(const ld::Atom& atom);
 182
 183 private:
 184
 185         File&                                                           _file;
 186         const char*                                                     _name;
 187         const ld::Atom*                                         _compiledAtom;
 188 };
 189
 190
 191
 192
 193
 194
 195
 196 class Parser
 197 {
 198 public:
 199         static bool                                             validFile(const uint8_t* fileContent, uint64_t fileLength, cpu_type_t architecture, cpu_subtype_t subarch);
 200         static const char*                              fileKind(const uint8_t* fileContent, uint64_t fileLength);
 201         static File*                                    parse(const uint8_t* fileContent, uint64_t fileLength, const char* path,
 202                                                                                         time_t modTime, uint32_t ordinal, cpu_type_t architecture, cpu_subtype_t subarch, bool logAllFiles);
 203         static bool                                             libLTOisLoaded() { return (::lto_get_version() != NULL); }
 204         static bool                                             optimize(   const std::vector<const ld::Atom*>& allAtoms,
 205                                                                                                 ld::Internal&                                           state,
 206                                                                                                 uint32_t                                                        nextInputOrdinal,
 207                                                                                                 const OptimizeOptions&                          options,
 208                                                                                                 ld::File::AtomHandler&                          handler,
 209                                                                                                 std::vector<const ld::Atom*>&           newAtoms,
 210                                                                                                 std::vector<const char*>&                       additionalUndefines);
 211
 212         static const char*                      ltoVersion()    { return ::lto_get_version(); }
 213
 214 private:
 215         static const char*                              tripletPrefixForArch(cpu_type_t arch);
 216         static ld::relocatable::File*   parseMachOFile(const uint8_t* p, size_t len, uint32_t nextInputOrdinal, const OptimizeOptions& options);
 217
 218         class CStringEquals
 219         {
 220         public:
 221                 bool operator()(const char* left, const char* right) const { return (strcmp(left, right) == 0); }
 222         };
 223         typedef __gnu_cxx::hash_set<const char*, __gnu_cxx::hash<const char*>, CStringEquals>  CStringSet;
 224         typedef __gnu_cxx::hash_map<const char*, Atom*, __gnu_cxx::hash<const char*>, CStringEquals> CStringToAtom;
 225
 226         class AtomSyncer : public ld::File::AtomHandler {
 227         public:
 228                                                         AtomSyncer(std::vector<const char*>& a, std::vector<const ld::Atom*>&na,
 229                                                                                 CStringToAtom la, CStringToAtom dla, const OptimizeOptions& options) :
 230                                                                                 _options(options), _additionalUndefines(a), _newAtoms(na), _llvmAtoms(la), _deadllvmAtoms(dla) { }
 231                 virtual void            doAtom(const class ld::Atom&);
 232                 virtual void            doFile(const class ld::File&) { }
 233
 234                 const OptimizeOptions&                  _options;
 235                 std::vector<const char*>&               _additionalUndefines;
 236                 std::vector<const ld::Atom*>&   _newAtoms;
 237                 CStringToAtom                                   _llvmAtoms;
 238                 CStringToAtom                                   _deadllvmAtoms;
 239         };
 240
 241         static std::vector<File*>               _s_files;
 242 };
 243
 244 std::vector<File*> Parser::_s_files;
 245
 246
 247 bool Parser::validFile(const uint8_t* fileContent, uint64_t fileLength, cpu_type_t architecture, cpu_subtype_t subarch)
 248 {
 249         switch (architecture) {
 250                 case CPU_TYPE_I386:
 251                         return ::lto_module_is_object_file_in_memory_for_target(fileContent, fileLength, "i386-");
 252                 case CPU_TYPE_X86_64:
 253                         return ::lto_module_is_object_file_in_memory_for_target(fileContent, fileLength, "x86_64-");
 254                 case CPU_TYPE_ARM:
 255                         for (const ARMSubType* t=ARMSubTypes; t->subTypeName != NULL; ++t) {
 256                                 if ( subarch == t->subType )
 257                                         return ::lto_module_is_object_file_in_memory_for_target(fileContent, fileLength, t->llvmTriplePrefix);
 258                         }
 259                         break;
 260                 case CPU_TYPE_POWERPC:
 261                         return ::lto_module_is_object_file_in_memory_for_target(fileContent, fileLength, "powerpc-");
 262         }
 263         return false;
 264 }
 265
 266 const char* Parser::fileKind(const uint8_t* p, uint64_t fileLength)
 267 {
 268         if ( (p[0] == 0xDE) && (p[1] == 0xC0) && (p[2] == 0x17) && (p[3] == 0x0B) ) {
 269                 uint32_t arch = LittleEndian::get32(*((uint32_t*)(&p[16])));
 270                 switch (arch) {
 271                         case CPU_TYPE_POWERPC:
 272                                 return "ppc";
 273                         case CPU_TYPE_I386:
 274                                 return "i386";
 275                         case CPU_TYPE_X86_64:
 276                                 return "x86_64";
 277                         case CPU_TYPE_ARM:
 278                                 for (const ARMSubType* t=ARMSubTypes; t->subTypeName != NULL; ++t) {
 279                                         if ( ::lto_module_is_object_file_in_memory_for_target(p, fileLength, t->llvmTriplePrefix) )
 280                                                 return t->subTypeName;
 281                                 }
 282                                 return "arm";
 283                 }
 284                 return "unknown bitcode architecture";
 285         }
 286         return NULL;
 287 }
 288
 289 File* Parser::parse(const uint8_t* fileContent, uint64_t fileLength, const char* path, time_t modTime,
 290                                                                                                         uint32_t ordinal, cpu_type_t architecture, cpu_subtype_t subarch, bool logAllFiles)
 291 {
 292         File* f = new File(path, modTime, fileContent, fileLength, ordinal, architecture);
 293         _s_files.push_back(f);
 294         if ( logAllFiles )
 295                 printf("%s\n", path);
 296         return f;
 297 }
 298
 299
 300 ld::relocatable::File* Parser::parseMachOFile(const uint8_t* p, size_t len, uint32_t nextInputOrdinal, const OptimizeOptions& options)
 301 {
 302         mach_o::relocatable::ParserOptions objOpts;
 303         objOpts.architecture            = options.arch;
 304         objOpts.objSubtypeMustMatch = false;
 305         objOpts.logAllFiles                     = false;
 306         objOpts.convertUnwindInfo       = true;
 307         objOpts.subType                         = 0;
 308
 309         // mach-o parsing is done in-memory, but need path for debug notes
 310         const char* path = "/tmp/lto.o";
 311         time_t modTime = 0;
 312         if ( options.tmpObjectFilePath != NULL ) {
 313                 path = options.tmpObjectFilePath;
 314                 struct stat statBuffer;
 315                 if ( stat(options.tmpObjectFilePath, &statBuffer) == 0 )
 316                         modTime = statBuffer.st_mtime;
 317         }
 318
 319         ld::relocatable::File* result = mach_o::relocatable::parse(p, len, path, modTime, nextInputOrdinal, objOpts);
 320         if ( result != NULL )
 321                 return result;
 322         throw "LLVM LTO, file is not of required architecture";
 323 }
 324
 325
 326
 327 File::File(const char* pth, time_t mTime, const uint8_t* content, uint32_t contentLength, uint32_t ord, cpu_type_t arch)
 328         : ld::relocatable::File(pth,mTime,ord), _architecture(arch), _internalAtom(*this),
 329         _atomArray(NULL), _atomArrayCount(0), _module(NULL), _debugInfoPath(pth),
 330         _section("__TEXT_", "__tmp_lto", ld::Section::typeTempLTO),
 331         _fixupToInternal(0, ld::Fixup::k1of1, ld::Fixup::kindNone, &_internalAtom),
 332         _debugInfo(ld::relocatable::File::kDebugInfoNone), _cpuSubType(0)
 333 {
 334         const bool log = false;
 335
 336         // create llvm module
 337         _module = ::lto_module_create_from_memory(content, contentLength);
 338     if ( _module == NULL )
 339                 throwf("could not parse object file %s: %s", pth, lto_get_error_message());
 340
 341         if ( log ) fprintf(stderr, "bitcode file: %s\n", pth);
 342
 343         // create atom for each global symbol in module
 344         uint32_t count = ::lto_module_get_num_symbols(_module);
 345         _atomArray = (Atom*)malloc(sizeof(Atom)*count);
 346         for (uint32_t i=0; i < count; ++i) {
 347                 const char* name = ::lto_module_get_symbol_name(_module, i);
 348                 lto_symbol_attributes attr = lto_module_get_symbol_attribute(_module, i);
 349
 350                 // <rdar://problem/6378110> LTO doesn't like dtrace symbols
 351                 // ignore dtrace static probes for now
 352                 // later when codegen is done and a mach-o file is produces the probes will be processed
 353                 if ( (strncmp(name, "___dtrace_probe$", 16) == 0) || (strncmp(name, "___dtrace_isenabled$", 20) == 0) )
 354                         continue;
 355
 356                 ld::Atom::Definition def;
 357                 ld::Atom::Combine combine = ld::Atom::combineNever;
 358                 switch ( attr & LTO_SYMBOL_DEFINITION_MASK ) {
 359                         case LTO_SYMBOL_DEFINITION_REGULAR:
 360                                 def = ld::Atom::definitionRegular;
 361                                 break;
 362                         case LTO_SYMBOL_DEFINITION_TENTATIVE:
 363                                 def = ld::Atom::definitionTentative;
 364                                 break;
 365                         case LTO_SYMBOL_DEFINITION_WEAK:
 366                                 def = ld::Atom::definitionRegular;
 367                                 combine = ld::Atom::combineByName;
 368                                 break;
 369                         case LTO_SYMBOL_DEFINITION_UNDEFINED:
 370                         case LTO_SYMBOL_DEFINITION_WEAKUNDEF:
 371                                 def = ld::Atom::definitionProxy;
 372                                 break;
 373                         default:
 374                                 throwf("unknown definition kind for symbol %s in bitcode file %s", name, pth);
 375                 }
 376
 377                 // make LLVM atoms for definitions and a reference for undefines
 378                 if ( def != ld::Atom::definitionProxy ) {
 379                         ld::Atom::Scope scope;
 380                         switch ( attr & LTO_SYMBOL_SCOPE_MASK) {
 381                                 case LTO_SYMBOL_SCOPE_INTERNAL:
 382                                         scope = ld::Atom::scopeTranslationUnit;
 383                                         break;
 384                                 case LTO_SYMBOL_SCOPE_HIDDEN:
 385                                         scope = ld::Atom::scopeLinkageUnit;
 386                                         break;
 387                                 case LTO_SYMBOL_SCOPE_DEFAULT:
 388                                         scope = ld::Atom::scopeGlobal;
 389                                         break;
 390                                 default:
 391                                         throwf("unknown scope for symbol %s in bitcode file %s", name, pth);
 392                         }
 393                         // only make atoms for non-internal symbols
 394                         if ( scope == ld::Atom::scopeTranslationUnit )
 395                                 continue;
 396                         uint8_t alignment = (attr & LTO_SYMBOL_ALIGNMENT_MASK);
 397                         // make Atom using placement new operator
 398                         new (&_atomArray[_atomArrayCount++]) Atom(*this, name, scope, def, combine, alignment);
 399                         if ( scope == ld::Atom::scopeLinkageUnit )
 400                                 _internalAtom.addReference(name);
 401                         if ( log ) fprintf(stderr, "\t0x%08X %s\n", attr, name);
 402                 }
 403                 else {
 404                         // add to list of external references
 405                         _internalAtom.addReference(name);
 406                         if ( log ) fprintf(stderr, "\t%s (undefined)\n", name);
 407                 }
 408         }
 409 }
 410
 411 File::~File()
 412 {
 413         if ( _module != NULL )
 414                 ::lto_module_dispose(_module);
 415 }
 416
 417 bool File::forEachAtom(ld::File::AtomHandler& handler) const
 418 {
 419         handler.doAtom(_internalAtom);
 420         for(uint32_t i=0; i < _atomArrayCount; ++i) {
 421                 handler.doAtom(_atomArray[i]);
 422         }
 423         return true;
 424 }
 425
 426 InternalAtom::InternalAtom(File& f)
 427         : ld::Atom(f._section, ld::Atom::definitionRegular, ld::Atom::combineNever, ld::Atom::scopeTranslationUnit,
 428                                 ld::Atom::typeLTOtemporary, ld::Atom::symbolTableNotIn, true, false, false, ld::Atom::Alignment(0)),
 429                 _file(f)
 430 {
 431 }
 432
 433 Atom::Atom(File& f, const char* nm, ld::Atom::Scope s, ld::Atom::Definition d, ld::Atom::Combine c, ld::Atom::Alignment a)
 434         : ld::Atom(f._section, d, c, s, ld::Atom::typeLTOtemporary,
 435                                 ld::Atom::symbolTableIn, false, false, false, a),
 436                 _file(f), _name(nm), _compiledAtom(NULL)
 437 {
 438 }
 439
 440 void Atom::setCompiledAtom(const ld::Atom& atom)
 441 {
 442         // set delegate so virtual methods go to it
 443         _compiledAtom = &atom;
 444
 445         //fprintf(stderr, "setting lto atom %p to delegate to mach-o atom %p (%s)\n", this, &atom, atom.name());
 446
 447         // update fields in ld::Atom to match newly constructed mach-o atom
 448         (const_cast<Atom*>(this))->setAttributesFromAtom(atom);
 449 }
 450
 451
 452
 453 bool Parser::optimize(  const std::vector<const ld::Atom*>&     allAtoms,
 454                                                 ld::Internal&                                           state,
 455                                                 uint32_t                                                        nextInputOrdinal,
 456                                                 const OptimizeOptions&                          options,
 457                                                 ld::File::AtomHandler&                          handler,
 458                                                 std::vector<const ld::Atom*>&           newAtoms,
 459                                                 std::vector<const char*>&                       additionalUndefines)
 460 {
 461         const bool logMustPreserve = false;
 462         const bool logExtraOptions = false;
 463         const bool logBitcodeFiles = false;
 464         const bool logAtomsBeforeSync = false;
 465
 466         // exit quickly if nothing to do
 467         if ( _s_files.size() == 0 )
 468                 return false;
 469
 470         // print out LTO version string if -v was used
 471         if ( options.verbose )
 472                 fprintf(stderr, "%s\n", lto_get_version());
 473
 474         // create optimizer and add each Reader
 475         lto_code_gen_t generator = ::lto_codegen_create();
 476         for (std::vector<File*>::iterator it=_s_files.begin(); it != _s_files.end(); ++it) {
 477                 if ( logBitcodeFiles ) fprintf(stderr, "lto_codegen_add_module(%s)\n", (*it)->path());
 478                 if ( ::lto_codegen_add_module(generator, (*it)->module()) )
 479                         throwf("lto: could not merge in %s because %s", (*it)->path(), ::lto_get_error_message());
 480         }
 481
 482         // add any -mllvm command line options
 483         for (std::vector<const char*>::const_iterator it=options.llvmOptions->begin(); it != options.llvmOptions->end(); ++it) {
 484                 if ( logExtraOptions ) fprintf(stderr, "passing option to llvm: %s\n", *it);
 485                 ::lto_codegen_debug_options(generator, *it);
 486         }
 487
 488         // The atom graph uses directed edges (references). Collect all references where
 489         // originating atom is not part of any LTO Reader. This allows optimizer to optimize an
 490         // external (i.e. not originated from same .o file) reference if all originating atoms are also
 491         // defined in llvm bitcode file.
 492         CStringSet nonLLVMRefs;
 493         CStringToAtom llvmAtoms;
 494     bool hasNonllvmAtoms = false;
 495         for (std::vector<const ld::Atom*>::const_iterator it = allAtoms.begin(); it != allAtoms.end(); ++it) {
 496                 const ld::Atom* atom = *it;
 497                 // only look at references that come from an atom that is not an llvm atom
 498                 if ( atom->contentType() != ld::Atom::typeLTOtemporary ) {
 499                         if ( (atom->section().type() != ld::Section::typeMachHeader) && (atom->definition() != ld::Atom::definitionProxy) ) {
 500                                 hasNonllvmAtoms = true;
 501                         }
 502                         const ld::Atom* target;
 503                         for (ld::Fixup::iterator fit=atom->fixupsBegin(); fit != atom->fixupsEnd(); ++fit) {
 504                                 switch ( fit->binding ) {
 505                                         case ld::Fixup::bindingDirectlyBound:
 506                                                 // that reference an llvm atom
 507                                                 if ( fit->u.target->contentType() == ld::Atom::typeLTOtemporary )
 508                                                         nonLLVMRefs.insert(fit->u.target->name());
 509                                                 break;
 510                                         case ld::Fixup::bindingsIndirectlyBound:
 511                                                 target = state.indirectBindingTable[fit->u.bindingIndex];
 512                                                 if ( target == NULL )
 513                                                         throwf("'%s' in %s contains undefined reference", atom->name(), atom->file()->path());
 514                                                 assert(target != NULL);
 515                                                 if ( target->contentType() == ld::Atom::typeLTOtemporary )
 516                                                         nonLLVMRefs.insert(target->name());
 517                                         default:
 518                                                 break;
 519                                 }
 520                         }
 521                 }
 522                 else {
 523                         llvmAtoms[atom->name()] = (Atom*)atom;
 524                 }
 525         }
 526         // if entry point is in a llvm bitcode file, it must be preserved by LTO
 527         if ( state.entryPoint!= NULL ) {
 528                 if ( state.entryPoint->contentType() == ld::Atom::typeLTOtemporary )
 529                         nonLLVMRefs.insert(state.entryPoint->name());
 530         }
 531
 532         // deadAtoms are the atoms that the linker coalesced.  For instance weak or tentative definitions
 533         // overriden by another atom.  If any of these deadAtoms are llvm atoms and they were replaced
 534         // with a mach-o atom, we need to tell the lto engine to preserve (not optimize away) its dead
 535         // atom so that the linker can replace it with the mach-o one later.
 536         CStringToAtom deadllvmAtoms;
 537         for (std::vector<const ld::Atom*>::const_iterator it = allAtoms.begin(); it != allAtoms.end(); ++it) {
 538                 const ld::Atom* atom = *it;
 539                 if ( atom->coalescedAway() && (atom->contentType() == ld::Atom::typeLTOtemporary) ) {
 540                         const char* name = atom->name();
 541                         if ( logMustPreserve ) fprintf(stderr, "lto_codegen_add_must_preserve_symbol(%s) because linker coalesce away and replace with a mach-o atom\n", name);
 542                         ::lto_codegen_add_must_preserve_symbol(generator, name);
 543                         deadllvmAtoms[name] = (Atom*)atom;
 544                 }
 545         }
 546         for (std::vector<File*>::iterator it=_s_files.begin(); it != _s_files.end(); ++it) {
 547                 File* file = *it;
 548                 for(uint32_t i=0; i < file->_atomArrayCount; ++i) {
 549                         Atom* llvmAtom = &file->_atomArray[i];
 550                         if ( llvmAtom->coalescedAway()  ) {
 551                                 const char* name = llvmAtom->name();
 552                                 if ( deadllvmAtoms.find(name) == deadllvmAtoms.end() ) {
 553                                         if ( logMustPreserve )
 554                                                 fprintf(stderr, "lto_codegen_add_must_preserve_symbol(%s) because linker coalesce away and replace with a mach-o atom\n", name);
 555                                         ::lto_codegen_add_must_preserve_symbol(generator, name);
 556                                         deadllvmAtoms[name] = (Atom*)llvmAtom;
 557                                 }
 558                         }
 559                         else if ( options.linkerDeadStripping && !llvmAtom->live() ) {
 560                                 const char* name = llvmAtom->name();
 561                                 deadllvmAtoms[name] = (Atom*)llvmAtom;
 562                         }
 563                 }
 564         }
 565
 566         // tell code generator about symbols that must be preserved
 567         for (CStringToAtom::iterator it = llvmAtoms.begin(); it != llvmAtoms.end(); ++it) {
 568                 const char* name = it->first;
 569                 Atom* atom = it->second;
 570                 // Include llvm Symbol in export list if it meets one of following two conditions
 571                 // 1 - atom scope is global (and not linkage unit).
 572                 // 2 - included in nonLLVMRefs set.
 573                 // If a symbol is not listed in exportList then LTO is free to optimize it away.
 574                 if ( (atom->scope() == ld::Atom::scopeGlobal) ) {
 575                         if ( logMustPreserve ) fprintf(stderr, "lto_codegen_add_must_preserve_symbol(%s) because global symbol\n", name);
 576                         ::lto_codegen_add_must_preserve_symbol(generator, name);
 577                 }
 578                 else if ( nonLLVMRefs.find(name) != nonLLVMRefs.end() ) {
 579                         if ( logMustPreserve ) fprintf(stderr, "lto_codegen_add_must_preserve_symbol(%s) because referenced by a mach-o atom\n", name);
 580                         ::lto_codegen_add_must_preserve_symbol(generator, name);
 581                 }
 582         }
 583
 584     // special case running ld -r on all bitcode files to produce another bitcode file (instead of mach-o)
 585     if ( options.relocatable && !hasNonllvmAtoms ) {
 586                 if ( ! ::lto_codegen_write_merged_modules(generator, options.outputFilePath) ) {
 587                         // HACK, no good way to tell linker we are all done, so just quit
 588                         exit(0);
 589                 }
 590                 warning("could not produce merged bitcode file");
 591     }
 592
 593         // set code-gen model
 594         lto_codegen_model model = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
 595         if ( options.mainExecutable ) {
 596                 if ( options.staticExecutable ) {
 597                         // darwin x86_64 "static" code model is really dynamic code model
 598                         if ( options.arch == CPU_TYPE_X86_64 )
 599                                 model = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
 600                         else
 601                                 model = LTO_CODEGEN_PIC_MODEL_STATIC;
 602                 }
 603                 else {
 604                         if ( options.pie )
 605                                 model = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
 606                         else
 607                                 model = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
 608                 }
 609         }
 610         else {
 611                 if ( options.allowTextRelocs )
 612                         model = LTO_CODEGEN_PIC_MODEL_DYNAMIC_NO_PIC;
 613                 else
 614                         model = LTO_CODEGEN_PIC_MODEL_DYNAMIC;
 615         }
 616         if ( ::lto_codegen_set_pic_model(generator, model) )
 617                 throwf("could not create set codegen model: %s", lto_get_error_message());
 618
 619     // if requested, save off merged bitcode file
 620     if ( options.saveTemps ) {
 621         char tempBitcodePath[MAXPATHLEN];
 622         strcpy(tempBitcodePath, options.outputFilePath);
 623         strcat(tempBitcodePath, ".lto.bc");
 624         ::lto_codegen_write_merged_modules(generator, tempBitcodePath);
 625     }
 626
 627 #if LTO_API_VERSION >= 3
 628         // find assembler next to linker
 629         char path[PATH_MAX];
 630         uint32_t bufSize = PATH_MAX;
 631         if ( _NSGetExecutablePath(path, &bufSize) != -1 ) {
 632                 char* lastSlash = strrchr(path, '/');
 633                 if ( lastSlash != NULL ) {
 634                         strcpy(lastSlash+1, "as");
 635                         struct stat statInfo;
 636                         if ( stat(path, &statInfo) == 0 )
 637                                 ::lto_codegen_set_assembler_path(generator, path);
 638                 }
 639         }
 640 #endif
 641         // run code generator
 642         size_t machOFileLen;
 643         const uint8_t* machOFile = (uint8_t*)::lto_codegen_compile(generator, &machOFileLen);
 644         if ( machOFile == NULL )
 645                 throwf("could not do LTO codegen: %s", ::lto_get_error_message());
 646
 647     // if requested, save off temp mach-o file
 648     if ( options.saveTemps ) {
 649         char tempMachoPath[MAXPATHLEN];
 650         strcpy(tempMachoPath, options.outputFilePath);
 651         strcat(tempMachoPath, ".lto.o");
 652         int fd = ::open(tempMachoPath, O_CREAT | O_WRONLY | O_TRUNC, 0666);
 653                 if ( fd != -1) {
 654                         ::write(fd, machOFile, machOFileLen);
 655                         ::close(fd);
 656                 }
 657                 //      save off merged bitcode file
 658                 char tempOptBitcodePath[MAXPATHLEN];
 659         strcpy(tempOptBitcodePath, options.outputFilePath);
 660         strcat(tempOptBitcodePath, ".lto.opt.bc");
 661         ::lto_codegen_write_merged_modules(generator, tempOptBitcodePath);
 662         }
 663
 664         // if needed, save temp mach-o file to specific location
 665         if ( options.tmpObjectFilePath != NULL ) {
 666                 int fd = ::open(options.tmpObjectFilePath, O_CREAT | O_WRONLY | O_TRUNC, 0666);
 667                 if ( fd != -1) {
 668                         ::write(fd, machOFile, machOFileLen);
 669                         ::close(fd);
 670                 }
 671                 else {
 672                         warning("could not write LTO temp file '%s', errno=%d", options.tmpObjectFilePath, errno);
 673                 }
 674         }
 675
 676         // parse generated mach-o file into a MachOReader
 677         ld::relocatable::File* machoFile = parseMachOFile(machOFile, machOFileLen, nextInputOrdinal, options);
 678
 679         // sync generated mach-o atoms with existing atoms ld knows about
 680         if ( logAtomsBeforeSync ) {
 681                 fprintf(stderr, "llvmAtoms:\n");
 682                 for (CStringToAtom::iterator it = llvmAtoms.begin(); it != llvmAtoms.end(); ++it) {
 683                         const char* name = it->first;
 684                         //Atom* atom = it->second;
 685                         fprintf(stderr, "\t%s\n", name);
 686                 }
 687                 fprintf(stderr, "deadllvmAtoms:\n");
 688                 for (CStringToAtom::iterator it = deadllvmAtoms.begin(); it != deadllvmAtoms.end(); ++it) {
 689                         const char* name = it->first;
 690                         //Atom* atom = it->second;
 691                         fprintf(stderr, "\t%s\n", name);
 692                 }
 693         }
 694         AtomSyncer syncer(additionalUndefines, newAtoms, llvmAtoms, deadllvmAtoms, options);
 695         machoFile->forEachAtom(syncer);
 696
 697         // Remove InternalAtoms from ld
 698         for (std::vector<File*>::iterator it=_s_files.begin(); it != _s_files.end(); ++it) {
 699                 (*it)->internalAtom().setCoalescedAway();
 700         }
 701         // Remove Atoms from ld if code generator optimized them away
 702         for (CStringToAtom::iterator li = llvmAtoms.begin(), le = llvmAtoms.end(); li != le; ++li) {
 703                 // check if setRealAtom() called on this Atom
 704                 if ( li->second->compiledAtom() == NULL ) {
 705                         //fprintf(stderr, "llvm optimized away %p %s\n", li->second, li->second->name());
 706                         li->second->setCoalescedAway();
 707                 }
 708         }
 709
 710         // notify about file level attributes
 711         handler.doFile(*machoFile);
 712
 713         // if final mach-o file has debug info, update original bitcode files to match
 714         for (std::vector<File*>::iterator it=_s_files.begin(); it != _s_files.end(); ++it) {
 715                 (*it)->setDebugInfo(machoFile->debugInfo(), machoFile->path(),
 716                                                         machoFile->modificationTime(), machoFile->cpuSubType());
 717         }
 718
 719         return true;
 720 }
 721
 722
 723 void Parser::AtomSyncer::doAtom(const ld::Atom& machoAtom)
 724 {
 725         // update proxy atoms to point to real atoms and find new atoms
 726         const char* name = machoAtom.name();
 727         if ( machoAtom.scope() >= ld::Atom::scopeLinkageUnit ) {
 728                 CStringToAtom::iterator pos = _llvmAtoms.find(name);
 729                 if ( pos != _llvmAtoms.end() ) {
 730                         // turn Atom into a proxy for this mach-o atom
 731                         pos->second->setCompiledAtom(machoAtom);
 732                 }
 733                 else {
 734                         // an atom of this name was not in the allAtoms list the linker gave us
 735                         if ( _deadllvmAtoms.find(name) != _deadllvmAtoms.end() ) {
 736                                 // this corresponding to an atom that the linker coalesced away or marked not-live
 737                                 if ( _options.linkerDeadStripping ) {
 738                                         // llvm seems to want this atom and -dead_strip is enabled, so it will be deleted if not needed, so add back
 739                                         Atom* llvmAtom = _deadllvmAtoms[name];
 740                                         llvmAtom->setCompiledAtom(machoAtom);
 741                                         _newAtoms.push_back(&machoAtom);
 742                                 }
 743                                 else {
 744                                         // Don't pass it back as a new atom
 745                                 }
 746                         }
 747                         else
 748                         {
 749                                 // this is something new that lto conjured up, tell ld its new
 750                                 _newAtoms.push_back(&machoAtom);
 751                         }
 752                 }
 753         }
 754         else {
 755                 // ld only knew about non-static atoms, so this one must be new
 756                 _newAtoms.push_back(&machoAtom);
 757         }
 758
 759         // adjust fixups to go through proxy atoms
 760         //fprintf(stderr, "adjusting fixups in atom: %s\n", machoAtom.name());
 761         for (ld::Fixup::iterator fit=machoAtom.fixupsBegin(); fit != machoAtom.fixupsEnd(); ++fit) {
 762                 switch ( fit->binding ) {
 763                         case ld::Fixup::bindingNone:
 764                                 break;
 765                         case ld::Fixup::bindingByNameUnbound:
 766                                 // don't know if this target has been seen by linker before or if it is new
 767                                 // be conservative and tell linker it is new
 768                                 _additionalUndefines.push_back(fit->u.name);
 769                                 //fprintf(stderr, "    by name ref to: %s\n", fit->u.name);
 770                                 break;
 771                         case ld::Fixup::bindingDirectlyBound:
 772                                 // If mach-o atom is referencing another mach-o atom then
 773                                 // reference is not going through Atom proxy. Fix it here to ensure that all
 774                                 // llvm symbol references always go through Atom proxy.
 775                                 if (  fit->u.target->scope() != ld::Atom::scopeTranslationUnit ) {
 776                                         const char* targetName = fit->u.target->name();
 777                                         CStringToAtom::iterator pos = _llvmAtoms.find(targetName);
 778                                         if ( pos != _llvmAtoms.end() ) {
 779                                                 fit->u.target = pos->second;
 780                                         }
 781                                         else {
 782                                                 if ( _deadllvmAtoms.find(targetName) != _deadllvmAtoms.end() ) {
 783                                                         // target was coalesed away and replace by mach-o atom from a non llvm .o file
 784                                                         fit->binding = ld::Fixup::bindingByNameUnbound;
 785                                                         fit->u.name = targetName;
 786                                                 }
 787                                         }
 788                                 }
 789                                 //fprintf(stderr, "    direct ref to: %s (scope=%d)\n", fit->u.target->name(), fit->u.target->scope());
 790                                 break;
 791                         case ld::Fixup::bindingByContentBound:
 792                                 //fprintf(stderr, "    direct by content to: %s\n", fit->u.target->name());
 793                                 break;
 794                         case ld::Fixup::bindingsIndirectlyBound:
 795                                 assert(0 && "indirect binding found in initial mach-o file?");
 796                                 //fprintf(stderr, "    indirect by content to: %u\n", fit->u.bindingIndex);
 797                                 break;
 798                 }
 799         }
 800
 801 }
 802
 803
 804 //
 805 // Used by archive reader to see if member is an llvm bitcode file
 806 //
 807 bool isObjectFile(const uint8_t* fileContent, uint64_t fileLength, cpu_type_t architecture, cpu_subtype_t subarch)
 808 {
 809         return Parser::validFile(fileContent, fileLength, architecture, subarch);
 810 }
 811
 812
 813 //
 814 // main function used by linker to instantiate ld::Files
 815 //
 816 ld::relocatable::File* parse(const uint8_t* fileContent, uint64_t fileLength,
 817                                                                 const char* path, time_t modTime, uint32_t ordinal,
 818                                                                 cpu_type_t architecture, cpu_subtype_t subarch, bool logAllFiles)
 819 {
 820         if ( Parser::validFile(fileContent, fileLength, architecture, subarch) )
 821                 return Parser::parse(fileContent, fileLength, path, modTime, ordinal, architecture, subarch, logAllFiles);
 822         else
 823                 return NULL;
 824 }
 825
 826 //
 827 // used by "ld -v" to report version of libLTO.dylib being used
 828 //
 829 const char* version()
 830 {
 831         return ::lto_get_version();
 832 }
 833
 834
 835 //
 836 // used by ld for error reporting
 837 //
 838 bool libLTOisLoaded()
 839 {
 840         return (::lto_get_version() != NULL);
 841 }
 842
 843 //
 844 // used by ld for error reporting
 845 //
 846 const char* archName(const uint8_t* fileContent, uint64_t fileLength)
 847 {
 848         return Parser::fileKind(fileContent, fileLength);
 849 }
 850
 851 //
 852 // used by ld for doing link time optimization
 853 //
 854 bool optimize(  const std::vector<const ld::Atom*>&     allAtoms,
 855                                 ld::Internal&                                           state,
 856                                 uint32_t                                                        nextInputOrdinal,
 857                                 const OptimizeOptions&                          options,
 858                                 ld::File::AtomHandler&                          handler,
 859                                 std::vector<const ld::Atom*>&           newAtoms,
 860                                 std::vector<const char*>&                       additionalUndefines)
 861 {
 862         return Parser::optimize(allAtoms, state, nextInputOrdinal, options, handler, newAtoms, additionalUndefines);
 863 }
 864
 865
 866
 867 }; // namespace lto
 868
 869
 870 #endif
 871