src/ld/SymbolTable.cpp

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  24
  25
  26 #include <stdlib.h>
  27 #include <sys/types.h>
  28 #include <sys/stat.h>
  29 #include <sys/mman.h>
  30 #include <sys/sysctl.h>
  31 #include <fcntl.h>
  32 #include <errno.h>
  33 #include <limits.h>
  34 #include <unistd.h>
  35 #include <assert.h>
  36
  37 #include <iostream>
  38 #include <sstream>
  39 #include <string>
  40 #include <map>
  41 #include <set>
  42 #include <vector>
  43 #include <algorithm>
  44
  45 #include "Options.h"
  46
  47 #include "ld.hpp"
  48 #include "InputFiles.h"
  49 #include "SymbolTable.h"
  50
  51
  52
  53 namespace ld {
  54 namespace tool {
  55
  56
  57 // HACK, I can't find a way to pass values in the compare classes (e.g. ContentFuncs)
  58 // so use global variable to pass info.
  59 static ld::IndirectBindingTable*        _s_indirectBindingTable = NULL;
  60
  61
  62 SymbolTable::SymbolTable(const Options& opts, std::vector<const ld::Atom*>& ibt)
  63         : _options(opts), _cstringTable(6151), _indirectBindingTable(ibt), _hasExternalTentativeDefinitions(false)
  64 {
  65         _s_indirectBindingTable = this;
  66 }
  67
  68
  69 size_t SymbolTable::ContentFuncs::operator()(const ld::Atom* atom) const
  70 {
  71         return atom->contentHash(*_s_indirectBindingTable);
  72 }
  73
  74 bool SymbolTable::ContentFuncs::operator()(const ld::Atom* left, const ld::Atom* right) const
  75 {
  76         return (memcmp(left->rawContentPointer(), right->rawContentPointer(), left->size()) == 0);
  77 }
  78
  79
  80
  81 size_t SymbolTable::CStringHashFuncs::operator()(const ld::Atom* atom) const
  82 {
  83         return atom->contentHash(*_s_indirectBindingTable);
  84 }
  85
  86 bool SymbolTable::CStringHashFuncs::operator()(const ld::Atom* left, const ld::Atom* right) const
  87 {
  88         return (strcmp((char*)left->rawContentPointer(), (char*)right->rawContentPointer()) == 0);
  89 }
  90
  91
  92 size_t SymbolTable::UTF16StringHashFuncs::operator()(const ld::Atom* atom) const
  93 {
  94         return atom->contentHash(*_s_indirectBindingTable);
  95 }
  96
  97 bool SymbolTable::UTF16StringHashFuncs::operator()(const ld::Atom* left, const ld::Atom* right) const
  98 {
  99         if ( left == right )
 100                 return true;
 101         const void* leftContent = left->rawContentPointer();
 102         const void* rightContent = right->rawContentPointer();
 103         unsigned int amount = left->size()-2;
 104         bool result = (memcmp(leftContent, rightContent, amount) == 0);
 105         return result;
 106 }
 107
 108
 109 size_t SymbolTable::ReferencesHashFuncs::operator()(const ld::Atom* atom) const
 110 {
 111         return atom->contentHash(*_s_indirectBindingTable);
 112 }
 113
 114 bool SymbolTable::ReferencesHashFuncs::operator()(const ld::Atom* left, const ld::Atom* right) const
 115 {
 116         return left->canCoalesceWith(*right, *_s_indirectBindingTable);
 117 }
 118
 119
 120 void SymbolTable::addDuplicateSymbol(const char *name, const ld::Atom *atom)
 121 {
 122     // Look up or create the file list for name.
 123     DuplicateSymbols::iterator symbolsIterator = _duplicateSymbols.find(name);
 124     DuplicatedSymbolAtomList *atoms = NULL;
 125     if (symbolsIterator != _duplicateSymbols.end()) {
 126         atoms = symbolsIterator->second;
 127     } else {
 128         atoms = new std::vector<const ld::Atom *>;
 129         _duplicateSymbols.insert(std::pair<const char *, DuplicatedSymbolAtomList *>(name, atoms));
 130     }
 131
 132     // check if file is already in the list, add it if not
 133     bool found = false;
 134     for (DuplicatedSymbolAtomList::iterator it = atoms->begin(); !found && it != atoms->end(); it++)
 135         if (strcmp((*it)->file()->path(), atom->file()->path()) == 0)
 136             found = true;
 137     if (!found)
 138         atoms->push_back(atom);
 139 }
 140
 141 void SymbolTable::checkDuplicateSymbols() const
 142 {
 143     bool foundDuplicate = false;
 144     for (DuplicateSymbols::const_iterator symbolIt = _duplicateSymbols.begin(); symbolIt != _duplicateSymbols.end(); symbolIt++) {
 145         DuplicatedSymbolAtomList *atoms = symbolIt->second;
 146         bool reportDuplicate;
 147         if (_options.deadCodeStrip()) {
 148             // search for a live atom
 149             reportDuplicate = false;
 150             for (DuplicatedSymbolAtomList::iterator it = atoms->begin(); !reportDuplicate && it != atoms->end(); it++) {
 151                 if ((*it)->live())
 152                     reportDuplicate = true;
 153             }
 154         } else {
 155             reportDuplicate = true;
 156         }
 157         if (reportDuplicate) {
 158             foundDuplicate = true;
 159             fprintf(stderr, "duplicate symbol %s in:\n", symbolIt->first);
 160             for (DuplicatedSymbolAtomList::iterator atomIt = atoms->begin(); atomIt != atoms->end(); atomIt++) {
 161                 fprintf(stderr, "    %s\n", (*atomIt)->file()->path());
 162             }
 163         }
 164     }
 165     if (foundDuplicate)
 166         throwf("%d duplicate symbol%s", (int)_duplicateSymbols.size(), _duplicateSymbols.size()==1?"":"s");
 167 }
 168
 169 // AtomPicker encapsulates the logic for picking which atom to use when adding an atom by name results in a collision
 170 class NameCollisionResolution {
 171 public:
 172         NameCollisionResolution(const ld::Atom& a, const ld::Atom& b, bool ignoreDuplicates, const Options& options) : _atomA(a), _atomB(b), _options(options), _reportDuplicate(false), _ignoreDuplicates(ignoreDuplicates) {
 173                 pickAtom();
 174         }
 175
 176         // Returns which atom to use
 177         const ld::Atom& chosen() { return *_chosen; }
 178         bool choseAtom(const ld::Atom& atom) { return _chosen == &atom; }
 179
 180         // Returns true if the two atoms should be reported as a duplicate symbol
 181         bool reportDuplicate()  { return _reportDuplicate; }
 182
 183 private:
 184         const ld::Atom& _atomA;
 185         const ld::Atom& _atomB;
 186         const Options& _options;
 187         const ld::Atom* _chosen;
 188         bool _reportDuplicate;
 189         bool _ignoreDuplicates;
 190
 191         void pickAtom(const ld::Atom& atom) { _chosen = &atom; } // primitive to set which atom is picked
 192         void pickAtomA() { pickAtom(_atomA); }  // primitive to pick atom A
 193         void pickAtomB() { pickAtom(_atomB); }  // primitive to pick atom B
 194
 195         // use atom A if pickA, otherwise use atom B
 196         void pickAOrB(bool pickA) { if (pickA) pickAtomA(); else pickAtomB(); }
 197
 198         void pickHigherOrdinal() {
 199                 pickAOrB(_atomA.file()->ordinal() < _atomB.file()->ordinal());
 200         }
 201
 202         void pickLowerOrdinal() {
 203                 pickAOrB(_atomA.file()->ordinal() > _atomB.file()->ordinal());
 204         }
 205
 206         void pickLargerSize() {
 207                 if (_atomA.size() == _atomB.size())
 208                         pickLowerOrdinal();
 209                 else
 210                         pickAOrB(_atomA.size() > _atomB.size());
 211         }
 212
 213         void pickGreaterAlignment() {
 214                 pickAOrB(_atomA.alignment().trailingZeros() > _atomB.alignment().trailingZeros());
 215         }
 216
 217         void pickBetweenRegularAtoms() {
 218                 if ( _atomA.combine() == ld::Atom::combineByName ) {
 219                         if ( _atomB.combine() == ld::Atom::combineByName ) {
 220                                 // <rdar://problem/9183821> always choose mach-o over llvm bit code, otherwise LTO may eliminate the llvm atom
 221                                 const bool aIsLTO = (_atomA.contentType() == ld::Atom::typeLTOtemporary);
 222                                 const bool bIsLTO = (_atomB.contentType() == ld::Atom::typeLTOtemporary);
 223                                 // <rdar://problem/9183821> always choose mach-o over llvm bit code, otherwise LTO may eliminate the llvm atom
 224                                 if ( aIsLTO != bIsLTO ) {
 225                                         pickAOrB(!aIsLTO);
 226                                 }
 227                                 else {
 228                                         // both weak, prefer non-auto-hide one
 229                                         if ( _atomA.autoHide() != _atomB.autoHide() ) {
 230                                                 // <rdar://problem/6783167> support auto hidden weak symbols: .weak_def_can_be_hidden
 231                                                 pickAOrB(!_atomA.autoHide());
 232                                         }
 233                                         else if ( _atomA.autoHide() && _atomB.autoHide() ) {
 234                                                 // both have auto-hide, so use one with greater alignment
 235                                                 pickGreaterAlignment();
 236                                         }
 237                                         else {
 238                                                 // neither auto-hide, check visibility
 239                                                 if ( _atomA.scope() != _atomB.scope() ) {
 240                                                         // <rdar://problem/8304984> use more visible weak def symbol
 241                                                         pickAOrB(_atomA.scope() == ld::Atom::scopeGlobal);
 242                                                 }
 243                                                 else {
 244                                                         // both have same visibility, use one with greater alignment
 245                                                         pickGreaterAlignment();
 246                                                 }
 247                                         }
 248                                 }
 249                         }
 250                         else {
 251                                 pickAtomB(); // pick not-weak
 252
 253                         }
 254                 }
 255                 else {
 256                         if ( _atomB.combine() == ld::Atom::combineByName ) {
 257                                 pickAtomA(); // pick not-weak
 258
 259                         }
 260                         else {
 261                                 // both are not-weak
 262                                 if ( _atomA.section().type() == ld::Section::typeMachHeader ) {
 263                                         pickAtomA();
 264                                 }
 265                                 else if ( _atomB.section().type() == ld::Section::typeMachHeader ) {
 266                                         pickAtomB();
 267                                 }
 268                                 else {
 269                                         if ( _ignoreDuplicates ) {
 270                                                 pickLowerOrdinal();
 271                                         }
 272                                         else {
 273                                                 _reportDuplicate = true;
 274                                         }
 275                                 }
 276                         }
 277                 }
 278         }
 279
 280         void pickCommonsMode(const ld::Atom& dylib, const ld::Atom& proxy) {
 281                 assert(dylib.definition() == ld::Atom::definitionTentative);
 282                 assert(proxy.definition() == ld::Atom::definitionProxy);
 283                 switch ( _options.commonsMode() ) {
 284                         case Options::kCommonsIgnoreDylibs:
 285                                 if ( _options.warnCommons() )
 286                                         warning("using common symbol %s from %s and ignoring defintion from dylib %s",
 287                                                         proxy.name(), proxy.file()->path(), dylib.file()->path());
 288                                 pickAtom(dylib);
 289                                 break;
 290                         case Options::kCommonsOverriddenByDylibs:
 291                                 if ( _options.warnCommons() )
 292                                         warning("replacing common symbol %s from %s with true definition from dylib %s",
 293                                                         proxy.name(), proxy.file()->path(), dylib.file()->path());
 294                                 pickAtom(proxy);
 295                                 break;
 296                         case Options::kCommonsConflictsDylibsError:
 297                                 throwf("common symbol %s from %s conflicts with defintion from dylib %s",
 298                                            proxy.name(), proxy.file()->path(), dylib.file()->path());
 299                 }
 300         }
 301
 302         void pickProxyAtom() {
 303                 // both atoms are definitionProxy
 304                 // <rdar://problem/5137732> ld should keep looking when it finds a weak definition in a dylib
 305                 if ( _atomA.combine() == ld::Atom::combineByName ) {
 306                         pickAtomB();
 307                 } else if ( _atomB.combine() == ld::Atom::combineByName ) {
 308                         pickAtomA();
 309                 } else {
 310                                 throwf("symbol %s exported from both %s and %s\n", _atomA.name(), _atomA.file()->path(), _atomB.file()->path());
 311                 }
 312         }
 313
 314         void pickAtom() {
 315                 // First, discriminate by definition
 316                 switch (_atomA.definition()) {
 317                         case ld::Atom::definitionRegular:
 318                                 switch (_atomB.definition()) {
 319                                         case ld::Atom::definitionRegular:
 320                                                 pickBetweenRegularAtoms();
 321                                                 break;
 322                                         case ld::Atom::definitionTentative:
 323                                                 pickAtomA();
 324                                                 break;
 325                                         case ld::Atom::definitionAbsolute:
 326                                                 _reportDuplicate = true;
 327                                                 pickHigherOrdinal();
 328                                                 break;
 329                                         case ld::Atom::definitionProxy:
 330                                                 pickAtomA();
 331                                                 break;
 332                                 }
 333                                 break;
 334                         case ld::Atom::definitionTentative:
 335                                 switch (_atomB.definition()) {
 336                                         case ld::Atom::definitionRegular:
 337                                                 pickAtomB();
 338                                                 break;
 339                                         case ld::Atom::definitionTentative:
 340                                                 pickLargerSize();
 341                                                 break;
 342                                         case ld::Atom::definitionAbsolute:
 343                                                 pickHigherOrdinal();
 344                                                 break;
 345                                         case ld::Atom::definitionProxy:
 346                                                 pickCommonsMode(_atomA, _atomB);
 347                                                 break;
 348                                 }
 349                                 break;
 350                         case ld::Atom::definitionAbsolute:
 351                                 switch (_atomB.definition()) {
 352                                         case ld::Atom::definitionRegular:
 353                                                 _reportDuplicate = true;
 354                                                 pickHigherOrdinal();
 355                                                 break;
 356                                         case ld::Atom::definitionTentative:
 357                                                 pickAtomA();
 358                                                 break;
 359                                         case ld::Atom::definitionAbsolute:
 360                                                 _reportDuplicate = true;
 361                                                 pickHigherOrdinal();
 362                                                 break;
 363                                         case ld::Atom::definitionProxy:
 364                                                 pickAtomA();
 365                                                 break;
 366                                 }
 367                                 break;
 368                         case ld::Atom::definitionProxy:
 369                                 switch (_atomB.definition()) {
 370                                         case ld::Atom::definitionRegular:
 371                                                 pickAtomB();
 372                                                 break;
 373                                         case ld::Atom::definitionTentative:
 374                                                 pickCommonsMode(_atomB, _atomA);
 375                                                 break;
 376                                         case ld::Atom::definitionAbsolute:
 377                                                 pickAtomB();
 378                                                 break;
 379                                         case ld::Atom::definitionProxy:
 380                                                 pickProxyAtom();
 381                                                 break;
 382                                 }
 383                                 break;
 384                 }
 385         }
 386 };
 387
 388 bool SymbolTable::addByName(const ld::Atom& newAtom, bool ignoreDuplicates)
 389 {
 390         bool useNew = true;
 391         assert(newAtom.name() != NULL);
 392         const char* name = newAtom.name();
 393         IndirectBindingSlot slot = this->findSlotForName(name);
 394         const ld::Atom* existingAtom = _indirectBindingTable[slot];
 395         //fprintf(stderr, "addByName(%p) name=%s, slot=%u, existing=%p\n", &newAtom, newAtom.name(), slot, existingAtom);
 396         if ( existingAtom != NULL ) {
 397                 assert(&newAtom != existingAtom);
 398                 NameCollisionResolution picker(newAtom, *existingAtom, ignoreDuplicates, _options);
 399                 if (picker.reportDuplicate()) {
 400                         addDuplicateSymbol(name, existingAtom);
 401                         addDuplicateSymbol(name, &newAtom);
 402                 }
 403                 useNew = picker.choseAtom(newAtom);
 404         }
 405         if ( useNew ) {
 406                 _indirectBindingTable[slot] = &newAtom;
 407                 if ( existingAtom != NULL ) {
 408                         markCoalescedAway(existingAtom);
 409                 }
 410                 if ( newAtom.scope() == ld::Atom::scopeGlobal ) {
 411                         if ( newAtom.definition() == ld::Atom::definitionTentative ) {
 412                                 _hasExternalTentativeDefinitions = true;
 413                         }
 414                 }
 415         }
 416         else {
 417                 markCoalescedAway(&newAtom);
 418         }
 419         // return if existing atom in symbol table was replaced
 420         return useNew && (existingAtom != NULL);
 421 }
 422
 423
 424 bool SymbolTable::addByContent(const ld::Atom& newAtom)
 425 {
 426         bool useNew = true;
 427         const ld::Atom* existingAtom;
 428         IndirectBindingSlot slot = this->findSlotForContent(&newAtom, &existingAtom);
 429         //fprintf(stderr, "addByContent(%p) name=%s, slot=%u, existing=%p\n", &newAtom, newAtom.name(), slot, existingAtom);
 430         if ( existingAtom != NULL ) {
 431                 // use existing unless new one has greater alignment requirements
 432                 useNew = ( newAtom.alignment().trailingZeros() > existingAtom->alignment().trailingZeros() );
 433         }
 434         if ( useNew ) {
 435                 _indirectBindingTable[slot] = &newAtom;
 436                 if ( existingAtom != NULL )
 437                         markCoalescedAway(existingAtom);
 438         }
 439         else {
 440                 _indirectBindingTable[slot] = existingAtom;
 441                 if ( existingAtom != &newAtom )
 442                         markCoalescedAway(&newAtom);
 443         }
 444         // return if existing atom in symbol table was replaced
 445         return useNew && (existingAtom != NULL);
 446 }
 447
 448 bool SymbolTable::addByReferences(const ld::Atom& newAtom)
 449 {
 450         bool useNew = true;
 451         const ld::Atom* existingAtom;
 452         IndirectBindingSlot slot = this->findSlotForReferences(&newAtom, &existingAtom);
 453         //fprintf(stderr, "addByReferences(%p) name=%s, slot=%u, existing=%p\n", &newAtom, newAtom.name(), slot, existingAtom);
 454         if ( existingAtom != NULL ) {
 455                 // use existing unless new one has greater alignment requirements
 456                 useNew = ( newAtom.alignment().trailingZeros() > existingAtom->alignment().trailingZeros() );
 457         }
 458         if ( useNew ) {
 459                 _indirectBindingTable[slot] = &newAtom;
 460                 if ( existingAtom != NULL )
 461                         markCoalescedAway(existingAtom);
 462         }
 463         else {
 464                 if ( existingAtom != &newAtom )
 465                         markCoalescedAway(&newAtom);
 466         }
 467         // return if existing atom in symbol table was replaced
 468         return useNew && (existingAtom != NULL);
 469 }
 470
 471
 472 bool SymbolTable::add(const ld::Atom& atom, bool ignoreDuplicates)
 473 {
 474         //fprintf(stderr, "SymbolTable::add(%p), name=%s\n", &atom, atom.name());
 475         assert(atom.scope() != ld::Atom::scopeTranslationUnit);
 476         switch ( atom.combine() ) {
 477                 case ld::Atom::combineNever:
 478                 case ld::Atom::combineByName:
 479                         return this->addByName(atom, ignoreDuplicates);
 480                         break;
 481                 case ld::Atom::combineByNameAndContent:
 482                         return this->addByContent(atom);
 483                         break;
 484                 case ld::Atom::combineByNameAndReferences:
 485                         return this->addByReferences(atom);
 486                         break;
 487         }
 488
 489         return false;
 490 }
 491
 492 void SymbolTable::markCoalescedAway(const ld::Atom* atom)
 493 {
 494         // remove this from list of all atoms used
 495         //fprintf(stderr, "markCoalescedAway(%p) from %s\n", atom, atom->file()->path());
 496         (const_cast<ld::Atom*>(atom))->setCoalescedAway();
 497
 498         //
 499         // The fixupNoneGroupSubordinate* fixup kind is used to model group comdat.
 500         // The "signature" atom in the group has a fixupNoneGroupSubordinate* fixup to
 501         // all other members of the group.  So, if the signature atom is
 502         // coalesced away, all other atoms in the group should also be removed.
 503         //
 504         for (ld::Fixup::iterator fit=atom->fixupsBegin(), fend=atom->fixupsEnd(); fit != fend; ++fit) {
 505                 switch ( fit->kind ) {
 506                         case ld::Fixup::kindNoneGroupSubordinate:
 507                         case ld::Fixup::kindNoneGroupSubordinateFDE:
 508                         case ld::Fixup::kindNoneGroupSubordinateLSDA:
 509                                 assert(fit->binding == ld::Fixup::bindingDirectlyBound);
 510                                 this->markCoalescedAway(fit->u.target);
 511                                 break;
 512                         default:
 513                                 break;
 514                 }
 515         }
 516
 517 }
 518
 519
 520 struct StrcmpSorter {
 521                 bool operator() (const char* i,const char* j) {
 522                         if (i==NULL)
 523                                 return true;
 524                         if (j==NULL)
 525                                 return false;
 526                         return strcmp(i, j)<0;}
 527 };
 528
 529 void SymbolTable::undefines(std::vector<const char*>& undefs)
 530 {
 531         // return all names in _byNameTable that have no associated atom
 532         for (NameToSlot::iterator it=_byNameTable.begin(); it != _byNameTable.end(); ++it) {
 533                 //fprintf(stderr, "  _byNameTable[%s] = slot %d which has atom %p\n", it->first, it->second, _indirectBindingTable[it->second]);
 534                 if ( _indirectBindingTable[it->second] == NULL )
 535                         undefs.push_back(it->first);
 536         }
 537         // sort so that undefines are in a stable order (not dependent on hashing functions)
 538         struct StrcmpSorter strcmpSorter;
 539         std::sort(undefs.begin(), undefs.end(), strcmpSorter);
 540 }
 541
 542
 543 void SymbolTable::tentativeDefs(std::vector<const char*>& tents)
 544 {
 545         // return all names in _byNameTable that have no associated atom
 546         for (NameToSlot::iterator it=_byNameTable.begin(); it != _byNameTable.end(); ++it) {
 547                 const char* name = it->first;
 548                 const ld::Atom* atom = _indirectBindingTable[it->second];
 549                 if ( (atom != NULL) && (atom->definition() == ld::Atom::definitionTentative) )
 550                         tents.push_back(name);
 551         }
 552         std::sort(tents.begin(), tents.end());
 553 }
 554
 555
 556 bool SymbolTable::hasName(const char* name)
 557 {
 558         NameToSlot::iterator pos = _byNameTable.find(name);
 559         if ( pos == _byNameTable.end() )
 560                 return false;
 561         return (_indirectBindingTable[pos->second] != NULL);
 562 }
 563
 564 // find existing or create new slot
 565 SymbolTable::IndirectBindingSlot SymbolTable::findSlotForName(const char* name)
 566 {
 567         NameToSlot::iterator pos = _byNameTable.find(name);
 568         if ( pos != _byNameTable.end() )
 569                 return pos->second;
 570         // create new slot for this name
 571         SymbolTable::IndirectBindingSlot slot = _indirectBindingTable.size();
 572         _indirectBindingTable.push_back(NULL);
 573         _byNameTable[name] = slot;
 574         _byNameReverseTable[slot] = name;
 575         return slot;
 576 }
 577
 578
 579 // find existing or create new slot
 580 SymbolTable::IndirectBindingSlot SymbolTable::findSlotForContent(const ld::Atom* atom, const ld::Atom** existingAtom)
 581 {
 582         //fprintf(stderr, "findSlotForContent(%p)\n", atom);
 583         SymbolTable::IndirectBindingSlot slot = 0;
 584         UTF16StringToSlot::iterator upos;
 585         CStringToSlot::iterator cspos;
 586         ContentToSlot::iterator pos;
 587         switch ( atom->section().type() ) {
 588                 case ld::Section::typeCString:
 589                         cspos = _cstringTable.find(atom);
 590                         if ( cspos != _cstringTable.end() ) {
 591                                 *existingAtom = _indirectBindingTable[cspos->second];
 592                                 return cspos->second;
 593                         }
 594                         slot = _indirectBindingTable.size();
 595                         _cstringTable[atom] = slot;
 596                         break;
 597                 case ld::Section::typeNonStdCString:
 598                         {
 599                                 // use seg/sect name is key to map to avoid coalescing across segments and sections
 600                                 char segsect[64];
 601                                 sprintf(segsect, "%s/%s", atom->section().segmentName(), atom->section().sectionName());
 602                                 NameToMap::iterator mpos = _nonStdCStringSectionToMap.find(segsect);
 603                                 CStringToSlot* map = NULL;
 604                                 if ( mpos == _nonStdCStringSectionToMap.end() ) {
 605                                         map = new CStringToSlot();
 606                                         _nonStdCStringSectionToMap[strdup(segsect)] = map;
 607                                 }
 608                                 else {
 609                                         map = mpos->second;
 610                                 }
 611                                 cspos = map->find(atom);
 612                                 if ( cspos != map->end() ) {
 613                                         *existingAtom = _indirectBindingTable[cspos->second];
 614                                         return cspos->second;
 615                                 }
 616                                 slot = _indirectBindingTable.size();
 617                                 map->operator[](atom) = slot;
 618                         }
 619                         break;
 620                 case ld::Section::typeUTF16Strings:
 621                         upos = _utf16Table.find(atom);
 622                         if ( upos != _utf16Table.end() ) {
 623                                 *existingAtom = _indirectBindingTable[upos->second];
 624                                 return upos->second;
 625                         }
 626                         slot = _indirectBindingTable.size();
 627                         _utf16Table[atom] = slot;
 628                         break;
 629                 case ld::Section::typeLiteral4:
 630                         pos = _literal4Table.find(atom);
 631                         if ( pos != _literal4Table.end() ) {
 632                                 *existingAtom = _indirectBindingTable[pos->second];
 633                                 return pos->second;
 634                         }
 635                         slot = _indirectBindingTable.size();
 636                         _literal4Table[atom] = slot;
 637                         break;
 638                 case ld::Section::typeLiteral8:
 639                         pos = _literal8Table.find(atom);
 640                         if ( pos != _literal8Table.end() ) {
 641                                 *existingAtom = _indirectBindingTable[pos->second];
 642                                 return pos->second;
 643                         }
 644                         slot = _indirectBindingTable.size();
 645                         _literal8Table[atom] = slot;
 646                         break;
 647                 case ld::Section::typeLiteral16:
 648                         pos = _literal16Table.find(atom);
 649                         if ( pos != _literal16Table.end() ) {
 650                                 *existingAtom = _indirectBindingTable[pos->second];
 651                                 return pos->second;
 652                         }
 653                         slot = _indirectBindingTable.size();
 654                         _literal16Table[atom] = slot;
 655                         break;
 656                 default:
 657                         assert(0 && "section type does not support coalescing by content");
 658         }
 659         _indirectBindingTable.push_back(atom);
 660         *existingAtom = NULL;
 661         return slot;
 662 }
 663
 664
 665
 666 // find existing or create new slot
 667 SymbolTable::IndirectBindingSlot SymbolTable::findSlotForReferences(const ld::Atom* atom, const ld::Atom** existingAtom)
 668 {
 669         //fprintf(stderr, "findSlotForReferences(%p)\n", atom);
 670
 671         SymbolTable::IndirectBindingSlot slot = 0;
 672         ReferencesToSlot::iterator pos;
 673         switch ( atom->section().type() ) {
 674                 case ld::Section::typeNonLazyPointer:
 675                         pos = _nonLazyPointerTable.find(atom);
 676                         if ( pos != _nonLazyPointerTable.end() ) {
 677                                 *existingAtom = _indirectBindingTable[pos->second];
 678                                 return pos->second;
 679                         }
 680                         slot = _indirectBindingTable.size();
 681                         _nonLazyPointerTable[atom] = slot;
 682                         break;
 683                 case ld::Section::typeCFString:
 684                         pos = _cfStringTable.find(atom);
 685                         if ( pos != _cfStringTable.end() ) {
 686                                 *existingAtom = _indirectBindingTable[pos->second];
 687                                 return pos->second;
 688                         }
 689                         slot = _indirectBindingTable.size();
 690                         _cfStringTable[atom] = slot;
 691                         break;
 692                 case ld::Section::typeObjCClassRefs:
 693                         pos = _objc2ClassRefTable.find(atom);
 694                         if ( pos != _objc2ClassRefTable.end() ) {
 695                                 *existingAtom = _indirectBindingTable[pos->second];
 696                                 return pos->second;
 697                         }
 698                         slot = _indirectBindingTable.size();
 699                         _objc2ClassRefTable[atom] = slot;
 700                         break;
 701                 case ld::Section::typeCStringPointer:
 702                         pos = _pointerToCStringTable.find(atom);
 703                         if ( pos != _pointerToCStringTable.end() ) {
 704                                 *existingAtom = _indirectBindingTable[pos->second];
 705                                 return pos->second;
 706                         }
 707                         slot = _indirectBindingTable.size();
 708                         _pointerToCStringTable[atom] = slot;
 709                         break;
 710                 default:
 711                         assert(0 && "section type does not support coalescing by references");
 712         }
 713         _indirectBindingTable.push_back(atom);
 714         *existingAtom = NULL;
 715         return slot;
 716 }
 717
 718
 719 const char*     SymbolTable::indirectName(IndirectBindingSlot slot) const
 720 {
 721         assert(slot < _indirectBindingTable.size());
 722         const ld::Atom* target = _indirectBindingTable[slot];
 723         if ( target != NULL )  {
 724                 return target->name();
 725         }
 726         // handle case when by-name reference is indirected and no atom yet in _byNameTable
 727         SlotToName::const_iterator pos = _byNameReverseTable.find(slot);
 728         if ( pos != _byNameReverseTable.end() )
 729                 return pos->second;
 730         assert(0);
 731         return NULL;
 732 }
 733
 734 const ld::Atom* SymbolTable::indirectAtom(IndirectBindingSlot slot) const
 735 {
 736         assert(slot < _indirectBindingTable.size());
 737         return _indirectBindingTable[slot];
 738 }
 739
 740 void SymbolTable::printStatistics()
 741 {
 742 //      fprintf(stderr, "cstring table size: %lu, bucket count: %lu, hash func called %u times\n",
 743 //                              _cstringTable.size(), _cstringTable.bucket_count(), cstringHashCount);
 744         int count[11];
 745         for(unsigned int b=0; b < 11; ++b) {
 746                 count[b] = 0;
 747         }
 748         for(unsigned int i=0; i < _cstringTable.bucket_count(); ++i) {
 749                 unsigned int n = _cstringTable.bucket_size(i);
 750                 if ( n < 10 )
 751                         count[n] += 1;
 752                 else
 753                         count[10] += 1;
 754         }
 755         fprintf(stderr, "cstring table distribution\n");
 756         for(unsigned int b=0; b < 11; ++b) {
 757                 fprintf(stderr, "%u buckets have %u elements\n", count[b], b);
 758         }
 759         fprintf(stderr, "indirect table size: %lu\n", _indirectBindingTable.size());
 760         fprintf(stderr, "by-name table size: %lu\n", _byNameTable.size());
 761 //      fprintf(stderr, "by-content table size: %lu, hash count: %u, equals count: %u, lookup count: %u\n",
 762 //                                              _byContentTable.size(), contentHashCount, contentEqualCount, contentLookupCount);
 763 //      fprintf(stderr, "by-ref table size: %lu, hashed count: %u, equals count: %u, lookup count: %u, insert count: %u\n",
 764 //                                              _byReferencesTable.size(), refHashCount, refEqualsCount, refLookupCount, refInsertCount);
 765
 766         //ReferencesHash obj;
 767         //for(ReferencesHashToSlot::iterator it=_byReferencesTable.begin(); it != _byReferencesTable.end(); ++it) {
 768         //      if ( obj.operator()(it->first) == 0x2F3AC0EAC744EA70 ) {
 769         //              fprintf(stderr, "hash=0x2F3AC0EAC744EA70 for %p %s from %s\n", it->first, it->first->name(), it->first->file()->path());
 770         //
 771         //      }
 772         //}
 773
 774 }
 775
 776 } // namespace tool
 777 } // namespace ld
 778