gold/resolve.cc

   1 // resolve.cc -- symbol resolution for gold
   2
   3 // Copyright 2006, 2007, 2008 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #include "gold.h"
  24
  25 #include "elfcpp.h"
  26 #include "target.h"
  27 #include "object.h"
  28 #include "symtab.h"
  29
  30 namespace gold
  31 {
  32
  33 // Symbol methods used in this file.
  34
  35 // Override the fields in Symbol.
  36
  37 template<int size, bool big_endian>
  38 void
  39 Symbol::override_base(const elfcpp::Sym<size, big_endian>& sym,
  40                       Object* object, const char* version)
  41 {
  42   gold_assert(this->source_ == FROM_OBJECT);
  43   this->u_.from_object.object = object;
  44   if (version != NULL && this->version() != version)
  45     {
  46       gold_assert(this->version() == NULL);
  47       this->version_ = version;
  48     }
  49   // FIXME: Handle SHN_XINDEX.
  50   this->u_.from_object.shndx = sym.get_st_shndx();
  51   this->type_ = sym.get_st_type();
  52   this->binding_ = sym.get_st_bind();
  53   this->visibility_ = sym.get_st_visibility();
  54   this->nonvis_ = sym.get_st_nonvis();
  55   if (object->is_dynamic())
  56     this->in_dyn_ = true;
  57   else
  58     this->in_reg_ = true;
  59 }
  60
  61 // Override the fields in Sized_symbol.
  62
  63 template<int size>
  64 template<bool big_endian>
  65 void
  66 Sized_symbol<size>::override(const elfcpp::Sym<size, big_endian>& sym,
  67                              Object* object, const char* version)
  68 {
  69   this->override_base(sym, object, version);
  70   this->value_ = sym.get_st_value();
  71   this->symsize_ = sym.get_st_size();
  72 }
  73
  74 // Override TOSYM with symbol FROMSYM, defined in OBJECT, with version
  75 // VERSION.  This handles all aliases of TOSYM.
  76
  77 template<int size, bool big_endian>
  78 void
  79 Symbol_table::override(Sized_symbol<size>* tosym,
  80                        const elfcpp::Sym<size, big_endian>& fromsym,
  81                        Object* object, const char* version)
  82 {
  83   tosym->override(fromsym, object, version);
  84   if (tosym->has_alias())
  85     {
  86       Symbol* sym = this->weak_aliases_[tosym];
  87       gold_assert(sym != NULL);
  88       Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
  89       do
  90         {
  91           ssym->override(fromsym, object, version);
  92           sym = this->weak_aliases_[ssym];
  93           gold_assert(sym != NULL);
  94           ssym = this->get_sized_symbol<size>(sym);
  95         }
  96       while (ssym != tosym);
  97     }
  98 }
  99
 100 // The resolve functions build a little code for each symbol.
 101 // Bit 0: 0 for global, 1 for weak.
 102 // Bit 1: 0 for regular object, 1 for shared object
 103 // Bits 2-3: 0 for normal, 1 for undefined, 2 for common
 104 // This gives us values from 0 to 11.
 105
 106 static const int global_or_weak_shift = 0;
 107 static const unsigned int global_flag = 0 << global_or_weak_shift;
 108 static const unsigned int weak_flag = 1 << global_or_weak_shift;
 109
 110 static const int regular_or_dynamic_shift = 1;
 111 static const unsigned int regular_flag = 0 << regular_or_dynamic_shift;
 112 static const unsigned int dynamic_flag = 1 << regular_or_dynamic_shift;
 113
 114 static const int def_undef_or_common_shift = 2;
 115 static const unsigned int def_flag = 0 << def_undef_or_common_shift;
 116 static const unsigned int undef_flag = 1 << def_undef_or_common_shift;
 117 static const unsigned int common_flag = 2 << def_undef_or_common_shift;
 118
 119 // This convenience function combines all the flags based on facts
 120 // about the symbol.
 121
 122 static unsigned int
 123 symbol_to_bits(elfcpp::STB binding, bool is_dynamic,
 124                unsigned int shndx, elfcpp::STT type)
 125 {
 126   unsigned int bits;
 127
 128   switch (binding)
 129     {
 130     case elfcpp::STB_GLOBAL:
 131       bits = global_flag;
 132       break;
 133
 134     case elfcpp::STB_WEAK:
 135       bits = weak_flag;
 136       break;
 137
 138     case elfcpp::STB_LOCAL:
 139       // We should only see externally visible symbols in the symbol
 140       // table.
 141       gold_error(_("invalid STB_LOCAL symbol in external symbols"));
 142       bits = global_flag;
 143
 144     default:
 145       // Any target which wants to handle STB_LOOS, etc., needs to
 146       // define a resolve method.
 147       gold_error(_("unsupported symbol binding"));
 148       bits = global_flag;
 149     }
 150
 151   if (is_dynamic)
 152     bits |= dynamic_flag;
 153   else
 154     bits |= regular_flag;
 155
 156   switch (shndx)
 157     {
 158     case elfcpp::SHN_UNDEF:
 159       bits |= undef_flag;
 160       break;
 161
 162     case elfcpp::SHN_COMMON:
 163       bits |= common_flag;
 164       break;
 165
 166     default:
 167       if (type == elfcpp::STT_COMMON)
 168         bits |= common_flag;
 169       else
 170         bits |= def_flag;
 171       break;
 172     }
 173
 174   return bits;
 175 }
 176
 177 // Resolve a symbol.  This is called the second and subsequent times
 178 // we see a symbol.  TO is the pre-existing symbol.  ORIG_SYM is the
 179 // new symbol, seen in OBJECT.  SYM is almost always identical to
 180 // ORIG_SYM, but may be munged (for instance, if we determine the
 181 // symbol is in a to-be-discarded section, we'll set sym's shndx to
 182 // UNDEFINED).  VERSION of the version of SYM.
 183
 184 template<int size, bool big_endian>
 185 void
 186 Symbol_table::resolve(Sized_symbol<size>* to,
 187                       const elfcpp::Sym<size, big_endian>& sym,
 188                       const elfcpp::Sym<size, big_endian>& orig_sym,
 189                       Object* object, const char* version)
 190 {
 191   if (object->target()->has_resolve())
 192     {
 193       Sized_target<size, big_endian>* sized_target;
 194       sized_target = object->sized_target<size, big_endian>();
 195       sized_target->resolve(to, sym, object, version);
 196       return;
 197     }
 198
 199   if (!object->is_dynamic())
 200     {
 201       // Record that we've seen this symbol in a regular object.
 202       to->set_in_reg();
 203     }
 204   else
 205     {
 206       // Record that we've seen this symbol in a dynamic object.
 207       to->set_in_dyn();
 208     }
 209
 210   unsigned int frombits = symbol_to_bits(sym.get_st_bind(),
 211                                          object->is_dynamic(),
 212                                          sym.get_st_shndx(),
 213                                          sym.get_st_type());
 214
 215   bool adjust_common_sizes;
 216   if (Symbol_table::should_override(to, frombits, object,
 217                                     &adjust_common_sizes))
 218     {
 219       typename Sized_symbol<size>::Size_type tosize = to->symsize();
 220
 221       this->override(to, sym, object, version);
 222
 223       if (adjust_common_sizes && tosize > to->symsize())
 224         to->set_symsize(tosize);
 225     }
 226   else
 227     {
 228       if (adjust_common_sizes && sym.get_st_size() > to->symsize())
 229         to->set_symsize(sym.get_st_size());
 230     }
 231
 232   // A new weak undefined reference, merging with an old weak
 233   // reference, could be a One Definition Rule (ODR) violation --
 234   // especially if the types or sizes of the references differ.  We'll
 235   // store such pairs and look them up later to make sure they
 236   // actually refer to the same lines of code.  (Note: not all ODR
 237   // violations can be found this way, and not everything this finds
 238   // is an ODR violation.  But it's helpful to warn about.)
 239   // We use orig_sym here because we want the symbol exactly as it
 240   // appears in the object file, not munged via our future processing.
 241   if (parameters->options().detect_odr_violations()
 242       && orig_sym.get_st_bind() == elfcpp::STB_WEAK
 243       && to->binding() == elfcpp::STB_WEAK
 244       && orig_sym.get_st_shndx() != elfcpp::SHN_UNDEF
 245       && to->shndx() != elfcpp::SHN_UNDEF
 246       && orig_sym.get_st_size() != 0    // Ignore weird 0-sized symbols.
 247       && to->symsize() != 0
 248       && (orig_sym.get_st_type() != to->type()
 249           || orig_sym.get_st_size() != to->symsize())
 250       // C does not have a concept of ODR, so we only need to do this
 251       // on C++ symbols.  These have (mangled) names starting with _Z.
 252       && to->name()[0] == '_' && to->name()[1] == 'Z')
 253     {
 254       Symbol_location fromloc
 255           = { object, orig_sym.get_st_shndx(), orig_sym.get_st_value() };
 256       Symbol_location toloc = { to->object(), to->shndx(), to->value() };
 257       this->candidate_odr_violations_[to->name()].insert(fromloc);
 258       this->candidate_odr_violations_[to->name()].insert(toloc);
 259     }
 260 }
 261
 262 // Handle the core of symbol resolution.  This is called with the
 263 // existing symbol, TO, and a bitflag describing the new symbol.  This
 264 // returns true if we should override the existing symbol with the new
 265 // one, and returns false otherwise.  It sets *ADJUST_COMMON_SIZES to
 266 // true if we should set the symbol size to the maximum of the TO and
 267 // FROM sizes.  It handles error conditions.
 268
 269 bool
 270 Symbol_table::should_override(const Symbol* to, unsigned int frombits,
 271                               Object* object, bool* adjust_common_sizes)
 272 {
 273   *adjust_common_sizes = false;
 274
 275   unsigned int tobits;
 276   if (to->source() == Symbol::FROM_OBJECT)
 277     tobits = symbol_to_bits(to->binding(),
 278                             to->object()->is_dynamic(),
 279                             to->shndx(),
 280                             to->type());
 281   else
 282     tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_ABS,
 283                             to->type());
 284
 285   // FIXME: Warn if either but not both of TO and SYM are STT_TLS.
 286
 287   // We use a giant switch table for symbol resolution.  This code is
 288   // unwieldy, but: 1) it is efficient; 2) we definitely handle all
 289   // cases; 3) it is easy to change the handling of a particular case.
 290   // The alternative would be a series of conditionals, but it is easy
 291   // to get the ordering wrong.  This could also be done as a table,
 292   // but that is no easier to understand than this large switch
 293   // statement.
 294
 295   // These are the values generated by the bit codes.
 296   enum
 297   {
 298     DEF =              global_flag | regular_flag | def_flag,
 299     WEAK_DEF =         weak_flag   | regular_flag | def_flag,
 300     DYN_DEF =          global_flag | dynamic_flag | def_flag,
 301     DYN_WEAK_DEF =     weak_flag   | dynamic_flag | def_flag,
 302     UNDEF =            global_flag | regular_flag | undef_flag,
 303     WEAK_UNDEF =       weak_flag   | regular_flag | undef_flag,
 304     DYN_UNDEF =        global_flag | dynamic_flag | undef_flag,
 305     DYN_WEAK_UNDEF =   weak_flag   | dynamic_flag | undef_flag,
 306     COMMON =           global_flag | regular_flag | common_flag,
 307     WEAK_COMMON =      weak_flag   | regular_flag | common_flag,
 308     DYN_COMMON =       global_flag | dynamic_flag | common_flag,
 309     DYN_WEAK_COMMON =  weak_flag   | dynamic_flag | common_flag
 310   };
 311
 312   switch (tobits * 16 + frombits)
 313     {
 314     case DEF * 16 + DEF:
 315       // Two definitions of the same symbol.
 316
 317       // If either symbol is defined by an object included using
 318       // --just-symbols, then don't warn.  This is for compatibility
 319       // with the GNU linker.  FIXME: This is a hack.
 320       if ((to->source() == Symbol::FROM_OBJECT && to->object()->just_symbols())
 321           || object->just_symbols())
 322         return false;
 323
 324       // FIXME: Do a better job of reporting locations.
 325       gold_error(_("%s: multiple definition of %s"),
 326                  object != NULL ? object->name().c_str() : _("command line"),
 327                  to->demangled_name().c_str());
 328       gold_error(_("%s: previous definition here"),
 329                  (to->source() == Symbol::FROM_OBJECT
 330                   ? to->object()->name().c_str()
 331                   : _("command line")));
 332       return false;
 333
 334     case WEAK_DEF * 16 + DEF:
 335       // We've seen a weak definition, and now we see a strong
 336       // definition.  In the original SVR4 linker, this was treated as
 337       // a multiple definition error.  In the Solaris linker and the
 338       // GNU linker, a weak definition followed by a regular
 339       // definition causes the weak definition to be overridden.  We
 340       // are currently compatible with the GNU linker.  In the future
 341       // we should add a target specific option to change this.
 342       // FIXME.
 343       return true;
 344
 345     case DYN_DEF * 16 + DEF:
 346     case DYN_WEAK_DEF * 16 + DEF:
 347       // We've seen a definition in a dynamic object, and now we see a
 348       // definition in a regular object.  The definition in the
 349       // regular object overrides the definition in the dynamic
 350       // object.
 351       return true;
 352
 353     case UNDEF * 16 + DEF:
 354     case WEAK_UNDEF * 16 + DEF:
 355     case DYN_UNDEF * 16 + DEF:
 356     case DYN_WEAK_UNDEF * 16 + DEF:
 357       // We've seen an undefined reference, and now we see a
 358       // definition.  We use the definition.
 359       return true;
 360
 361     case COMMON * 16 + DEF:
 362     case WEAK_COMMON * 16 + DEF:
 363     case DYN_COMMON * 16 + DEF:
 364     case DYN_WEAK_COMMON * 16 + DEF:
 365       // We've seen a common symbol and now we see a definition.  The
 366       // definition overrides.  FIXME: We should optionally issue, version a
 367       // warning.
 368       return true;
 369
 370     case DEF * 16 + WEAK_DEF:
 371     case WEAK_DEF * 16 + WEAK_DEF:
 372       // We've seen a definition and now we see a weak definition.  We
 373       // ignore the new weak definition.
 374       return false;
 375
 376     case DYN_DEF * 16 + WEAK_DEF:
 377     case DYN_WEAK_DEF * 16 + WEAK_DEF:
 378       // We've seen a dynamic definition and now we see a regular weak
 379       // definition.  The regular weak definition overrides.
 380       return true;
 381
 382     case UNDEF * 16 + WEAK_DEF:
 383     case WEAK_UNDEF * 16 + WEAK_DEF:
 384     case DYN_UNDEF * 16 + WEAK_DEF:
 385     case DYN_WEAK_UNDEF * 16 + WEAK_DEF:
 386       // A weak definition of a currently undefined symbol.
 387       return true;
 388
 389     case COMMON * 16 + WEAK_DEF:
 390     case WEAK_COMMON * 16 + WEAK_DEF:
 391       // A weak definition does not override a common definition.
 392       return false;
 393
 394     case DYN_COMMON * 16 + WEAK_DEF:
 395     case DYN_WEAK_COMMON * 16 + WEAK_DEF:
 396       // A weak definition does override a definition in a dynamic
 397       // object.  FIXME: We should optionally issue a warning.
 398       return true;
 399
 400     case DEF * 16 + DYN_DEF:
 401     case WEAK_DEF * 16 + DYN_DEF:
 402     case DYN_DEF * 16 + DYN_DEF:
 403     case DYN_WEAK_DEF * 16 + DYN_DEF:
 404       // Ignore a dynamic definition if we already have a definition.
 405       return false;
 406
 407     case UNDEF * 16 + DYN_DEF:
 408     case WEAK_UNDEF * 16 + DYN_DEF:
 409     case DYN_UNDEF * 16 + DYN_DEF:
 410     case DYN_WEAK_UNDEF * 16 + DYN_DEF:
 411       // Use a dynamic definition if we have a reference.
 412       return true;
 413
 414     case COMMON * 16 + DYN_DEF:
 415     case WEAK_COMMON * 16 + DYN_DEF:
 416     case DYN_COMMON * 16 + DYN_DEF:
 417     case DYN_WEAK_COMMON * 16 + DYN_DEF:
 418       // Ignore a dynamic definition if we already have a common
 419       // definition.
 420       return false;
 421
 422     case DEF * 16 + DYN_WEAK_DEF:
 423     case WEAK_DEF * 16 + DYN_WEAK_DEF:
 424     case DYN_DEF * 16 + DYN_WEAK_DEF:
 425     case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF:
 426       // Ignore a weak dynamic definition if we already have a
 427       // definition.
 428       return false;
 429
 430     case UNDEF * 16 + DYN_WEAK_DEF:
 431     case WEAK_UNDEF * 16 + DYN_WEAK_DEF:
 432     case DYN_UNDEF * 16 + DYN_WEAK_DEF:
 433     case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF:
 434       // Use a weak dynamic definition if we have a reference.
 435       return true;
 436
 437     case COMMON * 16 + DYN_WEAK_DEF:
 438     case WEAK_COMMON * 16 + DYN_WEAK_DEF:
 439     case DYN_COMMON * 16 + DYN_WEAK_DEF:
 440     case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF:
 441       // Ignore a weak dynamic definition if we already have a common
 442       // definition.
 443       return false;
 444
 445     case DEF * 16 + UNDEF:
 446     case WEAK_DEF * 16 + UNDEF:
 447     case DYN_DEF * 16 + UNDEF:
 448     case DYN_WEAK_DEF * 16 + UNDEF:
 449     case UNDEF * 16 + UNDEF:
 450       // A new undefined reference tells us nothing.
 451       return false;
 452
 453     case WEAK_UNDEF * 16 + UNDEF:
 454     case DYN_UNDEF * 16 + UNDEF:
 455     case DYN_WEAK_UNDEF * 16 + UNDEF:
 456       // A strong undef overrides a dynamic or weak undef.
 457       return true;
 458
 459     case COMMON * 16 + UNDEF:
 460     case WEAK_COMMON * 16 + UNDEF:
 461     case DYN_COMMON * 16 + UNDEF:
 462     case DYN_WEAK_COMMON * 16 + UNDEF:
 463       // A new undefined reference tells us nothing.
 464       return false;
 465
 466     case DEF * 16 + WEAK_UNDEF:
 467     case WEAK_DEF * 16 + WEAK_UNDEF:
 468     case DYN_DEF * 16 + WEAK_UNDEF:
 469     case DYN_WEAK_DEF * 16 + WEAK_UNDEF:
 470     case UNDEF * 16 + WEAK_UNDEF:
 471     case WEAK_UNDEF * 16 + WEAK_UNDEF:
 472     case DYN_UNDEF * 16 + WEAK_UNDEF:
 473     case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF:
 474     case COMMON * 16 + WEAK_UNDEF:
 475     case WEAK_COMMON * 16 + WEAK_UNDEF:
 476     case DYN_COMMON * 16 + WEAK_UNDEF:
 477     case DYN_WEAK_COMMON * 16 + WEAK_UNDEF:
 478       // A new weak undefined reference tells us nothing.
 479       return false;
 480
 481     case DEF * 16 + DYN_UNDEF:
 482     case WEAK_DEF * 16 + DYN_UNDEF:
 483     case DYN_DEF * 16 + DYN_UNDEF:
 484     case DYN_WEAK_DEF * 16 + DYN_UNDEF:
 485     case UNDEF * 16 + DYN_UNDEF:
 486     case WEAK_UNDEF * 16 + DYN_UNDEF:
 487     case DYN_UNDEF * 16 + DYN_UNDEF:
 488     case DYN_WEAK_UNDEF * 16 + DYN_UNDEF:
 489     case COMMON * 16 + DYN_UNDEF:
 490     case WEAK_COMMON * 16 + DYN_UNDEF:
 491     case DYN_COMMON * 16 + DYN_UNDEF:
 492     case DYN_WEAK_COMMON * 16 + DYN_UNDEF:
 493       // A new dynamic undefined reference tells us nothing.
 494       return false;
 495
 496     case DEF * 16 + DYN_WEAK_UNDEF:
 497     case WEAK_DEF * 16 + DYN_WEAK_UNDEF:
 498     case DYN_DEF * 16 + DYN_WEAK_UNDEF:
 499     case DYN_WEAK_DEF * 16 + DYN_WEAK_UNDEF:
 500     case UNDEF * 16 + DYN_WEAK_UNDEF:
 501     case WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
 502     case DYN_UNDEF * 16 + DYN_WEAK_UNDEF:
 503     case DYN_WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
 504     case COMMON * 16 + DYN_WEAK_UNDEF:
 505     case WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
 506     case DYN_COMMON * 16 + DYN_WEAK_UNDEF:
 507     case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
 508       // A new weak dynamic undefined reference tells us nothing.
 509       return false;
 510
 511     case DEF * 16 + COMMON:
 512       // A common symbol does not override a definition.
 513       return false;
 514
 515     case WEAK_DEF * 16 + COMMON:
 516     case DYN_DEF * 16 + COMMON:
 517     case DYN_WEAK_DEF * 16 + COMMON:
 518       // A common symbol does override a weak definition or a dynamic
 519       // definition.
 520       return true;
 521
 522     case UNDEF * 16 + COMMON:
 523     case WEAK_UNDEF * 16 + COMMON:
 524     case DYN_UNDEF * 16 + COMMON:
 525     case DYN_WEAK_UNDEF * 16 + COMMON:
 526       // A common symbol is a definition for a reference.
 527       return true;
 528
 529     case COMMON * 16 + COMMON:
 530       // Set the size to the maximum.
 531       *adjust_common_sizes = true;
 532       return false;
 533
 534     case WEAK_COMMON * 16 + COMMON:
 535       // I'm not sure just what a weak common symbol means, but
 536       // presumably it can be overridden by a regular common symbol.
 537       return true;
 538
 539     case DYN_COMMON * 16 + COMMON:
 540     case DYN_WEAK_COMMON * 16 + COMMON:
 541       // Use the real common symbol, but adjust the size if necessary.
 542       *adjust_common_sizes = true;
 543       return true;
 544
 545     case DEF * 16 + WEAK_COMMON:
 546     case WEAK_DEF * 16 + WEAK_COMMON:
 547     case DYN_DEF * 16 + WEAK_COMMON:
 548     case DYN_WEAK_DEF * 16 + WEAK_COMMON:
 549       // Whatever a weak common symbol is, it won't override a
 550       // definition.
 551       return false;
 552
 553     case UNDEF * 16 + WEAK_COMMON:
 554     case WEAK_UNDEF * 16 + WEAK_COMMON:
 555     case DYN_UNDEF * 16 + WEAK_COMMON:
 556     case DYN_WEAK_UNDEF * 16 + WEAK_COMMON:
 557       // A weak common symbol is better than an undefined symbol.
 558       return true;
 559
 560     case COMMON * 16 + WEAK_COMMON:
 561     case WEAK_COMMON * 16 + WEAK_COMMON:
 562     case DYN_COMMON * 16 + WEAK_COMMON:
 563     case DYN_WEAK_COMMON * 16 + WEAK_COMMON:
 564       // Ignore a weak common symbol in the presence of a real common
 565       // symbol.
 566       return false;
 567
 568     case DEF * 16 + DYN_COMMON:
 569     case WEAK_DEF * 16 + DYN_COMMON:
 570     case DYN_DEF * 16 + DYN_COMMON:
 571     case DYN_WEAK_DEF * 16 + DYN_COMMON:
 572       // Ignore a dynamic common symbol in the presence of a
 573       // definition.
 574       return false;
 575
 576     case UNDEF * 16 + DYN_COMMON:
 577     case WEAK_UNDEF * 16 + DYN_COMMON:
 578     case DYN_UNDEF * 16 + DYN_COMMON:
 579     case DYN_WEAK_UNDEF * 16 + DYN_COMMON:
 580       // A dynamic common symbol is a definition of sorts.
 581       return true;
 582
 583     case COMMON * 16 + DYN_COMMON:
 584     case WEAK_COMMON * 16 + DYN_COMMON:
 585     case DYN_COMMON * 16 + DYN_COMMON:
 586     case DYN_WEAK_COMMON * 16 + DYN_COMMON:
 587       // Set the size to the maximum.
 588       *adjust_common_sizes = true;
 589       return false;
 590
 591     case DEF * 16 + DYN_WEAK_COMMON:
 592     case WEAK_DEF * 16 + DYN_WEAK_COMMON:
 593     case DYN_DEF * 16 + DYN_WEAK_COMMON:
 594     case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON:
 595       // A common symbol is ignored in the face of a definition.
 596       return false;
 597
 598     case UNDEF * 16 + DYN_WEAK_COMMON:
 599     case WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
 600     case DYN_UNDEF * 16 + DYN_WEAK_COMMON:
 601     case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
 602       // I guess a weak common symbol is better than a definition.
 603       return true;
 604
 605     case COMMON * 16 + DYN_WEAK_COMMON:
 606     case WEAK_COMMON * 16 + DYN_WEAK_COMMON:
 607     case DYN_COMMON * 16 + DYN_WEAK_COMMON:
 608     case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON:
 609       // Set the size to the maximum.
 610       *adjust_common_sizes = true;
 611       return false;
 612
 613     default:
 614       gold_unreachable();
 615     }
 616 }
 617
 618 // A special case of should_override which is only called for a strong
 619 // defined symbol from a regular object file.  This is used when
 620 // defining special symbols.
 621
 622 bool
 623 Symbol_table::should_override_with_special(const Symbol* to)
 624 {
 625   bool adjust_common_sizes;
 626   unsigned int frombits = global_flag | regular_flag | def_flag;
 627   bool ret = Symbol_table::should_override(to, frombits, NULL,
 628                                            &adjust_common_sizes);
 629   gold_assert(!adjust_common_sizes);
 630   return ret;
 631 }
 632
 633 // Override symbol base with a special symbol.
 634
 635 void
 636 Symbol::override_base_with_special(const Symbol* from)
 637 {
 638   gold_assert(this->name_ == from->name_ || this->has_alias());
 639
 640   this->source_ = from->source_;
 641   switch (from->source_)
 642     {
 643     case FROM_OBJECT:
 644       this->u_.from_object = from->u_.from_object;
 645       break;
 646     case IN_OUTPUT_DATA:
 647       this->u_.in_output_data = from->u_.in_output_data;
 648       break;
 649     case IN_OUTPUT_SEGMENT:
 650       this->u_.in_output_segment = from->u_.in_output_segment;
 651       break;
 652     case CONSTANT:
 653       break;
 654     default:
 655       gold_unreachable();
 656       break;
 657     }
 658
 659   if (from->version_ != NULL && this->version_ != from->version_)
 660     {
 661       gold_assert(this->version_ == NULL);
 662       this->version_ = from->version_;
 663     }
 664
 665   this->type_ = from->type_;
 666   this->binding_ = from->binding_;
 667   this->visibility_ = from->visibility_;
 668   this->nonvis_ = from->nonvis_;
 669
 670   // Special symbols are always considered to be regular symbols.
 671   this->in_reg_ = true;
 672
 673   if (from->needs_dynsym_entry_)
 674     this->needs_dynsym_entry_ = true;
 675   if (from->needs_dynsym_value_)
 676     this->needs_dynsym_value_ = true;
 677
 678   // We shouldn't see these flags.  If we do, we need to handle them
 679   // somehow.
 680   gold_assert(!from->is_target_special_ || this->is_target_special_);
 681   gold_assert(!from->is_forwarder_);
 682   gold_assert(!from->has_plt_offset_);
 683   gold_assert(!from->has_warning_);
 684   gold_assert(!from->is_copied_from_dynobj_);
 685   gold_assert(!from->is_forced_local_);
 686 }
 687
 688 // Override a symbol with a special symbol.
 689
 690 template<int size>
 691 void
 692 Sized_symbol<size>::override_with_special(const Sized_symbol<size>* from)
 693 {
 694   this->override_base_with_special(from);
 695   this->value_ = from->value_;
 696   this->symsize_ = from->symsize_;
 697 }
 698
 699 // Override TOSYM with the special symbol FROMSYM.  This handles all
 700 // aliases of TOSYM.
 701
 702 template<int size>
 703 void
 704 Symbol_table::override_with_special(Sized_symbol<size>* tosym,
 705                                     const Sized_symbol<size>* fromsym)
 706 {
 707   tosym->override_with_special(fromsym);
 708   if (tosym->has_alias())
 709     {
 710       Symbol* sym = this->weak_aliases_[tosym];
 711       gold_assert(sym != NULL);
 712       Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
 713       do
 714         {
 715           ssym->override_with_special(fromsym);
 716           sym = this->weak_aliases_[ssym];
 717           gold_assert(sym != NULL);
 718           ssym = this->get_sized_symbol<size>(sym);
 719         }
 720       while (ssym != tosym);
 721     }
 722   if (tosym->binding() == elfcpp::STB_LOCAL)
 723     this->force_local(tosym);
 724 }
 725
 726 // Instantiate the templates we need.  We could use the configure
 727 // script to restrict this to only the ones needed for implemented
 728 // targets.
 729
 730 #ifdef HAVE_TARGET_32_LITTLE
 731 template
 732 void
 733 Symbol_table::resolve<32, false>(
 734     Sized_symbol<32>* to,
 735     const elfcpp::Sym<32, false>& sym,
 736     const elfcpp::Sym<32, false>& orig_sym,
 737     Object* object,
 738     const char* version);
 739 #endif
 740
 741 #ifdef HAVE_TARGET_32_BIG
 742 template
 743 void
 744 Symbol_table::resolve<32, true>(
 745     Sized_symbol<32>* to,
 746     const elfcpp::Sym<32, true>& sym,
 747     const elfcpp::Sym<32, true>& orig_sym,
 748     Object* object,
 749     const char* version);
 750 #endif
 751
 752 #ifdef HAVE_TARGET_64_LITTLE
 753 template
 754 void
 755 Symbol_table::resolve<64, false>(
 756     Sized_symbol<64>* to,
 757     const elfcpp::Sym<64, false>& sym,
 758     const elfcpp::Sym<64, false>& orig_sym,
 759     Object* object,
 760     const char* version);
 761 #endif
 762
 763 #ifdef HAVE_TARGET_64_BIG
 764 template
 765 void
 766 Symbol_table::resolve<64, true>(
 767     Sized_symbol<64>* to,
 768     const elfcpp::Sym<64, true>& sym,
 769     const elfcpp::Sym<64, true>& orig_sym,
 770     Object* object,
 771     const char* version);
 772 #endif
 773
 774 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
 775 template
 776 void
 777 Symbol_table::override_with_special<32>(Sized_symbol<32>*,
 778                                         const Sized_symbol<32>*);
 779 #endif
 780
 781 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
 782 template
 783 void
 784 Symbol_table::override_with_special<64>(Sized_symbol<64>*,
 785                                         const Sized_symbol<64>*);
 786 #endif
 787
 788 } // End namespace gold.