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                       unsigned int st_shndx, bool is_ordinary,
  41                       Object* object, const char* version)
  42 {
  43   gold_assert(this->source_ == FROM_OBJECT);
  44   this->u_.from_object.object = object;
  45   if (version != NULL && this->version() != version)
  46     {
  47       gold_assert(this->version() == NULL);
  48       this->version_ = version;
  49     }
  50   this->u_.from_object.shndx = st_shndx;
  51   this->is_ordinary_shndx_ = is_ordinary;
  52   this->type_ = sym.get_st_type();
  53   this->binding_ = sym.get_st_bind();
  54   this->visibility_ = sym.get_st_visibility();
  55   this->nonvis_ = sym.get_st_nonvis();
  56   if (object->is_dynamic())
  57     this->in_dyn_ = true;
  58   else
  59     this->in_reg_ = true;
  60 }
  61
  62 // Override the fields in Sized_symbol.
  63
  64 template<int size>
  65 template<bool big_endian>
  66 void
  67 Sized_symbol<size>::override(const elfcpp::Sym<size, big_endian>& sym,
  68                              unsigned st_shndx, bool is_ordinary,
  69                              Object* object, const char* version)
  70 {
  71   this->override_base(sym, st_shndx, is_ordinary, object, version);
  72   this->value_ = sym.get_st_value();
  73   this->symsize_ = sym.get_st_size();
  74 }
  75
  76 // Override TOSYM with symbol FROMSYM, defined in OBJECT, with version
  77 // VERSION.  This handles all aliases of TOSYM.
  78
  79 template<int size, bool big_endian>
  80 void
  81 Symbol_table::override(Sized_symbol<size>* tosym,
  82                        const elfcpp::Sym<size, big_endian>& fromsym,
  83                        unsigned int st_shndx, bool is_ordinary,
  84                        Object* object, const char* version)
  85 {
  86   tosym->override(fromsym, st_shndx, is_ordinary, object, version);
  87   if (tosym->has_alias())
  88     {
  89       Symbol* sym = this->weak_aliases_[tosym];
  90       gold_assert(sym != NULL);
  91       Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
  92       do
  93         {
  94           ssym->override(fromsym, st_shndx, is_ordinary, object, version);
  95           sym = this->weak_aliases_[ssym];
  96           gold_assert(sym != NULL);
  97           ssym = this->get_sized_symbol<size>(sym);
  98         }
  99       while (ssym != tosym);
 100     }
 101 }
 102
 103 // The resolve functions build a little code for each symbol.
 104 // Bit 0: 0 for global, 1 for weak.
 105 // Bit 1: 0 for regular object, 1 for shared object
 106 // Bits 2-3: 0 for normal, 1 for undefined, 2 for common
 107 // This gives us values from 0 to 11.
 108
 109 static const int global_or_weak_shift = 0;
 110 static const unsigned int global_flag = 0 << global_or_weak_shift;
 111 static const unsigned int weak_flag = 1 << global_or_weak_shift;
 112
 113 static const int regular_or_dynamic_shift = 1;
 114 static const unsigned int regular_flag = 0 << regular_or_dynamic_shift;
 115 static const unsigned int dynamic_flag = 1 << regular_or_dynamic_shift;
 116
 117 static const int def_undef_or_common_shift = 2;
 118 static const unsigned int def_flag = 0 << def_undef_or_common_shift;
 119 static const unsigned int undef_flag = 1 << def_undef_or_common_shift;
 120 static const unsigned int common_flag = 2 << def_undef_or_common_shift;
 121
 122 // This convenience function combines all the flags based on facts
 123 // about the symbol.
 124
 125 static unsigned int
 126 symbol_to_bits(elfcpp::STB binding, bool is_dynamic,
 127                unsigned int shndx, bool is_ordinary, elfcpp::STT type)
 128 {
 129   unsigned int bits;
 130
 131   switch (binding)
 132     {
 133     case elfcpp::STB_GLOBAL:
 134       bits = global_flag;
 135       break;
 136
 137     case elfcpp::STB_WEAK:
 138       bits = weak_flag;
 139       break;
 140
 141     case elfcpp::STB_LOCAL:
 142       // We should only see externally visible symbols in the symbol
 143       // table.
 144       gold_error(_("invalid STB_LOCAL symbol in external symbols"));
 145       bits = global_flag;
 146
 147     default:
 148       // Any target which wants to handle STB_LOOS, etc., needs to
 149       // define a resolve method.
 150       gold_error(_("unsupported symbol binding"));
 151       bits = global_flag;
 152     }
 153
 154   if (is_dynamic)
 155     bits |= dynamic_flag;
 156   else
 157     bits |= regular_flag;
 158
 159   switch (shndx)
 160     {
 161     case elfcpp::SHN_UNDEF:
 162       bits |= undef_flag;
 163       break;
 164
 165     case elfcpp::SHN_COMMON:
 166       if (!is_ordinary)
 167         bits |= common_flag;
 168       break;
 169
 170     default:
 171       if (type == elfcpp::STT_COMMON)
 172         bits |= common_flag;
 173       else
 174         bits |= def_flag;
 175       break;
 176     }
 177
 178   return bits;
 179 }
 180
 181 // Resolve a symbol.  This is called the second and subsequent times
 182 // we see a symbol.  TO is the pre-existing symbol.  ST_SHNDX is the
 183 // section index for SYM, possibly adjusted for many sections.
 184 // IS_ORDINARY is whether ST_SHNDX is a normal section index rather
 185 // than a special code.  ORIG_ST_SHNDX is the original section index,
 186 // before any munging because of discarded sections, except that all
 187 // non-ordinary section indexes are mapped to SHN_UNDEF.  VERSION of
 188 // the version of SYM.
 189
 190 template<int size, bool big_endian>
 191 void
 192 Symbol_table::resolve(Sized_symbol<size>* to,
 193                       const elfcpp::Sym<size, big_endian>& sym,
 194                       unsigned int st_shndx, bool is_ordinary,
 195                       unsigned int orig_st_shndx,
 196                       Object* object, const char* version)
 197 {
 198   if (object->target()->has_resolve())
 199     {
 200       Sized_target<size, big_endian>* sized_target;
 201       sized_target = object->sized_target<size, big_endian>();
 202       sized_target->resolve(to, sym, object, version);
 203       return;
 204     }
 205
 206   if (!object->is_dynamic())
 207     {
 208       // Record that we've seen this symbol in a regular object.
 209       to->set_in_reg();
 210     }
 211   else
 212     {
 213       // Record that we've seen this symbol in a dynamic object.
 214       to->set_in_dyn();
 215     }
 216
 217   unsigned int frombits = symbol_to_bits(sym.get_st_bind(),
 218                                          object->is_dynamic(),
 219                                          st_shndx, is_ordinary,
 220                                          sym.get_st_type());
 221
 222   bool adjust_common_sizes;
 223   if (Symbol_table::should_override(to, frombits, object,
 224                                     &adjust_common_sizes))
 225     {
 226       typename Sized_symbol<size>::Size_type tosize = to->symsize();
 227
 228       this->override(to, sym, st_shndx, is_ordinary, object, version);
 229
 230       if (adjust_common_sizes && tosize > to->symsize())
 231         to->set_symsize(tosize);
 232     }
 233   else
 234     {
 235       if (adjust_common_sizes && sym.get_st_size() > to->symsize())
 236         to->set_symsize(sym.get_st_size());
 237     }
 238
 239   // A new weak undefined reference, merging with an old weak
 240   // reference, could be a One Definition Rule (ODR) violation --
 241   // especially if the types or sizes of the references differ.  We'll
 242   // store such pairs and look them up later to make sure they
 243   // actually refer to the same lines of code.  (Note: not all ODR
 244   // violations can be found this way, and not everything this finds
 245   // is an ODR violation.  But it's helpful to warn about.)
 246   bool to_is_ordinary;
 247   if (parameters->options().detect_odr_violations()
 248       && sym.get_st_bind() == elfcpp::STB_WEAK
 249       && to->binding() == elfcpp::STB_WEAK
 250       && orig_st_shndx != elfcpp::SHN_UNDEF
 251       && to->shndx(&to_is_ordinary) != elfcpp::SHN_UNDEF
 252       && to_is_ordinary
 253       && sym.get_st_size() != 0    // Ignore weird 0-sized symbols.
 254       && to->symsize() != 0
 255       && (sym.get_st_type() != to->type()
 256           || sym.get_st_size() != to->symsize())
 257       // C does not have a concept of ODR, so we only need to do this
 258       // on C++ symbols.  These have (mangled) names starting with _Z.
 259       && to->name()[0] == '_' && to->name()[1] == 'Z')
 260     {
 261       Symbol_location fromloc
 262           = { object, orig_st_shndx, sym.get_st_value() };
 263       Symbol_location toloc = { to->object(), to->shndx(&to_is_ordinary),
 264                                 to->value() };
 265       this->candidate_odr_violations_[to->name()].insert(fromloc);
 266       this->candidate_odr_violations_[to->name()].insert(toloc);
 267     }
 268 }
 269
 270 // Handle the core of symbol resolution.  This is called with the
 271 // existing symbol, TO, and a bitflag describing the new symbol.  This
 272 // returns true if we should override the existing symbol with the new
 273 // one, and returns false otherwise.  It sets *ADJUST_COMMON_SIZES to
 274 // true if we should set the symbol size to the maximum of the TO and
 275 // FROM sizes.  It handles error conditions.
 276
 277 bool
 278 Symbol_table::should_override(const Symbol* to, unsigned int frombits,
 279                               Object* object, bool* adjust_common_sizes)
 280 {
 281   *adjust_common_sizes = false;
 282
 283   unsigned int tobits;
 284   if (to->source() == Symbol::IS_UNDEFINED)
 285     tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_UNDEF, true,
 286                             to->type());
 287   else if (to->source() != Symbol::FROM_OBJECT)
 288     tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_ABS, false,
 289                             to->type());
 290   else
 291     {
 292       bool is_ordinary;
 293       unsigned int shndx = to->shndx(&is_ordinary);
 294       tobits = symbol_to_bits(to->binding(),
 295                               to->object()->is_dynamic(),
 296                               shndx,
 297                               is_ordinary,
 298                               to->type());
 299     }
 300
 301   // FIXME: Warn if either but not both of TO and SYM are STT_TLS.
 302
 303   // We use a giant switch table for symbol resolution.  This code is
 304   // unwieldy, but: 1) it is efficient; 2) we definitely handle all
 305   // cases; 3) it is easy to change the handling of a particular case.
 306   // The alternative would be a series of conditionals, but it is easy
 307   // to get the ordering wrong.  This could also be done as a table,
 308   // but that is no easier to understand than this large switch
 309   // statement.
 310
 311   // These are the values generated by the bit codes.
 312   enum
 313   {
 314     DEF =              global_flag | regular_flag | def_flag,
 315     WEAK_DEF =         weak_flag   | regular_flag | def_flag,
 316     DYN_DEF =          global_flag | dynamic_flag | def_flag,
 317     DYN_WEAK_DEF =     weak_flag   | dynamic_flag | def_flag,
 318     UNDEF =            global_flag | regular_flag | undef_flag,
 319     WEAK_UNDEF =       weak_flag   | regular_flag | undef_flag,
 320     DYN_UNDEF =        global_flag | dynamic_flag | undef_flag,
 321     DYN_WEAK_UNDEF =   weak_flag   | dynamic_flag | undef_flag,
 322     COMMON =           global_flag | regular_flag | common_flag,
 323     WEAK_COMMON =      weak_flag   | regular_flag | common_flag,
 324     DYN_COMMON =       global_flag | dynamic_flag | common_flag,
 325     DYN_WEAK_COMMON =  weak_flag   | dynamic_flag | common_flag
 326   };
 327
 328   switch (tobits * 16 + frombits)
 329     {
 330     case DEF * 16 + DEF:
 331       // Two definitions of the same symbol.
 332
 333       // If either symbol is defined by an object included using
 334       // --just-symbols, then don't warn.  This is for compatibility
 335       // with the GNU linker.  FIXME: This is a hack.
 336       if ((to->source() == Symbol::FROM_OBJECT && to->object()->just_symbols())
 337           || object->just_symbols())
 338         return false;
 339
 340       // FIXME: Do a better job of reporting locations.
 341       gold_error(_("%s: multiple definition of %s"),
 342                  object != NULL ? object->name().c_str() : _("command line"),
 343                  to->demangled_name().c_str());
 344       gold_error(_("%s: previous definition here"),
 345                  (to->source() == Symbol::FROM_OBJECT
 346                   ? to->object()->name().c_str()
 347                   : _("command line")));
 348       return false;
 349
 350     case WEAK_DEF * 16 + DEF:
 351       // We've seen a weak definition, and now we see a strong
 352       // definition.  In the original SVR4 linker, this was treated as
 353       // a multiple definition error.  In the Solaris linker and the
 354       // GNU linker, a weak definition followed by a regular
 355       // definition causes the weak definition to be overridden.  We
 356       // are currently compatible with the GNU linker.  In the future
 357       // we should add a target specific option to change this.
 358       // FIXME.
 359       return true;
 360
 361     case DYN_DEF * 16 + DEF:
 362     case DYN_WEAK_DEF * 16 + DEF:
 363       // We've seen a definition in a dynamic object, and now we see a
 364       // definition in a regular object.  The definition in the
 365       // regular object overrides the definition in the dynamic
 366       // object.
 367       return true;
 368
 369     case UNDEF * 16 + DEF:
 370     case WEAK_UNDEF * 16 + DEF:
 371     case DYN_UNDEF * 16 + DEF:
 372     case DYN_WEAK_UNDEF * 16 + DEF:
 373       // We've seen an undefined reference, and now we see a
 374       // definition.  We use the definition.
 375       return true;
 376
 377     case COMMON * 16 + DEF:
 378     case WEAK_COMMON * 16 + DEF:
 379     case DYN_COMMON * 16 + DEF:
 380     case DYN_WEAK_COMMON * 16 + DEF:
 381       // We've seen a common symbol and now we see a definition.  The
 382       // definition overrides.  FIXME: We should optionally issue, version a
 383       // warning.
 384       return true;
 385
 386     case DEF * 16 + WEAK_DEF:
 387     case WEAK_DEF * 16 + WEAK_DEF:
 388       // We've seen a definition and now we see a weak definition.  We
 389       // ignore the new weak definition.
 390       return false;
 391
 392     case DYN_DEF * 16 + WEAK_DEF:
 393     case DYN_WEAK_DEF * 16 + WEAK_DEF:
 394       // We've seen a dynamic definition and now we see a regular weak
 395       // definition.  The regular weak definition overrides.
 396       return true;
 397
 398     case UNDEF * 16 + WEAK_DEF:
 399     case WEAK_UNDEF * 16 + WEAK_DEF:
 400     case DYN_UNDEF * 16 + WEAK_DEF:
 401     case DYN_WEAK_UNDEF * 16 + WEAK_DEF:
 402       // A weak definition of a currently undefined symbol.
 403       return true;
 404
 405     case COMMON * 16 + WEAK_DEF:
 406     case WEAK_COMMON * 16 + WEAK_DEF:
 407       // A weak definition does not override a common definition.
 408       return false;
 409
 410     case DYN_COMMON * 16 + WEAK_DEF:
 411     case DYN_WEAK_COMMON * 16 + WEAK_DEF:
 412       // A weak definition does override a definition in a dynamic
 413       // object.  FIXME: We should optionally issue a warning.
 414       return true;
 415
 416     case DEF * 16 + DYN_DEF:
 417     case WEAK_DEF * 16 + DYN_DEF:
 418     case DYN_DEF * 16 + DYN_DEF:
 419     case DYN_WEAK_DEF * 16 + DYN_DEF:
 420       // Ignore a dynamic definition if we already have a definition.
 421       return false;
 422
 423     case UNDEF * 16 + DYN_DEF:
 424     case WEAK_UNDEF * 16 + DYN_DEF:
 425     case DYN_UNDEF * 16 + DYN_DEF:
 426     case DYN_WEAK_UNDEF * 16 + DYN_DEF:
 427       // Use a dynamic definition if we have a reference.
 428       return true;
 429
 430     case COMMON * 16 + DYN_DEF:
 431     case WEAK_COMMON * 16 + DYN_DEF:
 432     case DYN_COMMON * 16 + DYN_DEF:
 433     case DYN_WEAK_COMMON * 16 + DYN_DEF:
 434       // Ignore a dynamic definition if we already have a common
 435       // definition.
 436       return false;
 437
 438     case DEF * 16 + DYN_WEAK_DEF:
 439     case WEAK_DEF * 16 + DYN_WEAK_DEF:
 440     case DYN_DEF * 16 + DYN_WEAK_DEF:
 441     case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF:
 442       // Ignore a weak dynamic definition if we already have a
 443       // definition.
 444       return false;
 445
 446     case UNDEF * 16 + DYN_WEAK_DEF:
 447     case WEAK_UNDEF * 16 + DYN_WEAK_DEF:
 448     case DYN_UNDEF * 16 + DYN_WEAK_DEF:
 449     case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF:
 450       // Use a weak dynamic definition if we have a reference.
 451       return true;
 452
 453     case COMMON * 16 + DYN_WEAK_DEF:
 454     case WEAK_COMMON * 16 + DYN_WEAK_DEF:
 455     case DYN_COMMON * 16 + DYN_WEAK_DEF:
 456     case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF:
 457       // Ignore a weak dynamic definition if we already have a common
 458       // definition.
 459       return false;
 460
 461     case DEF * 16 + UNDEF:
 462     case WEAK_DEF * 16 + UNDEF:
 463     case DYN_DEF * 16 + UNDEF:
 464     case DYN_WEAK_DEF * 16 + UNDEF:
 465     case UNDEF * 16 + UNDEF:
 466       // A new undefined reference tells us nothing.
 467       return false;
 468
 469     case WEAK_UNDEF * 16 + UNDEF:
 470     case DYN_UNDEF * 16 + UNDEF:
 471     case DYN_WEAK_UNDEF * 16 + UNDEF:
 472       // A strong undef overrides a dynamic or weak undef.
 473       return true;
 474
 475     case COMMON * 16 + UNDEF:
 476     case WEAK_COMMON * 16 + UNDEF:
 477     case DYN_COMMON * 16 + UNDEF:
 478     case DYN_WEAK_COMMON * 16 + UNDEF:
 479       // A new undefined reference tells us nothing.
 480       return false;
 481
 482     case DEF * 16 + WEAK_UNDEF:
 483     case WEAK_DEF * 16 + WEAK_UNDEF:
 484     case DYN_DEF * 16 + WEAK_UNDEF:
 485     case DYN_WEAK_DEF * 16 + WEAK_UNDEF:
 486     case UNDEF * 16 + WEAK_UNDEF:
 487     case WEAK_UNDEF * 16 + WEAK_UNDEF:
 488     case DYN_UNDEF * 16 + WEAK_UNDEF:
 489     case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF:
 490     case COMMON * 16 + WEAK_UNDEF:
 491     case WEAK_COMMON * 16 + WEAK_UNDEF:
 492     case DYN_COMMON * 16 + WEAK_UNDEF:
 493     case DYN_WEAK_COMMON * 16 + WEAK_UNDEF:
 494       // A new weak undefined reference tells us nothing.
 495       return false;
 496
 497     case DEF * 16 + DYN_UNDEF:
 498     case WEAK_DEF * 16 + DYN_UNDEF:
 499     case DYN_DEF * 16 + DYN_UNDEF:
 500     case DYN_WEAK_DEF * 16 + DYN_UNDEF:
 501     case UNDEF * 16 + DYN_UNDEF:
 502     case WEAK_UNDEF * 16 + DYN_UNDEF:
 503     case DYN_UNDEF * 16 + DYN_UNDEF:
 504     case DYN_WEAK_UNDEF * 16 + DYN_UNDEF:
 505     case COMMON * 16 + DYN_UNDEF:
 506     case WEAK_COMMON * 16 + DYN_UNDEF:
 507     case DYN_COMMON * 16 + DYN_UNDEF:
 508     case DYN_WEAK_COMMON * 16 + DYN_UNDEF:
 509       // A new dynamic undefined reference tells us nothing.
 510       return false;
 511
 512     case DEF * 16 + DYN_WEAK_UNDEF:
 513     case WEAK_DEF * 16 + DYN_WEAK_UNDEF:
 514     case DYN_DEF * 16 + DYN_WEAK_UNDEF:
 515     case DYN_WEAK_DEF * 16 + DYN_WEAK_UNDEF:
 516     case UNDEF * 16 + DYN_WEAK_UNDEF:
 517     case WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
 518     case DYN_UNDEF * 16 + DYN_WEAK_UNDEF:
 519     case DYN_WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
 520     case COMMON * 16 + DYN_WEAK_UNDEF:
 521     case WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
 522     case DYN_COMMON * 16 + DYN_WEAK_UNDEF:
 523     case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
 524       // A new weak dynamic undefined reference tells us nothing.
 525       return false;
 526
 527     case DEF * 16 + COMMON:
 528       // A common symbol does not override a definition.
 529       return false;
 530
 531     case WEAK_DEF * 16 + COMMON:
 532     case DYN_DEF * 16 + COMMON:
 533     case DYN_WEAK_DEF * 16 + COMMON:
 534       // A common symbol does override a weak definition or a dynamic
 535       // definition.
 536       return true;
 537
 538     case UNDEF * 16 + COMMON:
 539     case WEAK_UNDEF * 16 + COMMON:
 540     case DYN_UNDEF * 16 + COMMON:
 541     case DYN_WEAK_UNDEF * 16 + COMMON:
 542       // A common symbol is a definition for a reference.
 543       return true;
 544
 545     case COMMON * 16 + COMMON:
 546       // Set the size to the maximum.
 547       *adjust_common_sizes = true;
 548       return false;
 549
 550     case WEAK_COMMON * 16 + COMMON:
 551       // I'm not sure just what a weak common symbol means, but
 552       // presumably it can be overridden by a regular common symbol.
 553       return true;
 554
 555     case DYN_COMMON * 16 + COMMON:
 556     case DYN_WEAK_COMMON * 16 + COMMON:
 557       // Use the real common symbol, but adjust the size if necessary.
 558       *adjust_common_sizes = true;
 559       return true;
 560
 561     case DEF * 16 + WEAK_COMMON:
 562     case WEAK_DEF * 16 + WEAK_COMMON:
 563     case DYN_DEF * 16 + WEAK_COMMON:
 564     case DYN_WEAK_DEF * 16 + WEAK_COMMON:
 565       // Whatever a weak common symbol is, it won't override a
 566       // definition.
 567       return false;
 568
 569     case UNDEF * 16 + WEAK_COMMON:
 570     case WEAK_UNDEF * 16 + WEAK_COMMON:
 571     case DYN_UNDEF * 16 + WEAK_COMMON:
 572     case DYN_WEAK_UNDEF * 16 + WEAK_COMMON:
 573       // A weak common symbol is better than an undefined symbol.
 574       return true;
 575
 576     case COMMON * 16 + WEAK_COMMON:
 577     case WEAK_COMMON * 16 + WEAK_COMMON:
 578     case DYN_COMMON * 16 + WEAK_COMMON:
 579     case DYN_WEAK_COMMON * 16 + WEAK_COMMON:
 580       // Ignore a weak common symbol in the presence of a real common
 581       // symbol.
 582       return false;
 583
 584     case DEF * 16 + DYN_COMMON:
 585     case WEAK_DEF * 16 + DYN_COMMON:
 586     case DYN_DEF * 16 + DYN_COMMON:
 587     case DYN_WEAK_DEF * 16 + DYN_COMMON:
 588       // Ignore a dynamic common symbol in the presence of a
 589       // definition.
 590       return false;
 591
 592     case UNDEF * 16 + DYN_COMMON:
 593     case WEAK_UNDEF * 16 + DYN_COMMON:
 594     case DYN_UNDEF * 16 + DYN_COMMON:
 595     case DYN_WEAK_UNDEF * 16 + DYN_COMMON:
 596       // A dynamic common symbol is a definition of sorts.
 597       return true;
 598
 599     case COMMON * 16 + DYN_COMMON:
 600     case WEAK_COMMON * 16 + DYN_COMMON:
 601     case DYN_COMMON * 16 + DYN_COMMON:
 602     case DYN_WEAK_COMMON * 16 + DYN_COMMON:
 603       // Set the size to the maximum.
 604       *adjust_common_sizes = true;
 605       return false;
 606
 607     case DEF * 16 + DYN_WEAK_COMMON:
 608     case WEAK_DEF * 16 + DYN_WEAK_COMMON:
 609     case DYN_DEF * 16 + DYN_WEAK_COMMON:
 610     case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON:
 611       // A common symbol is ignored in the face of a definition.
 612       return false;
 613
 614     case UNDEF * 16 + DYN_WEAK_COMMON:
 615     case WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
 616     case DYN_UNDEF * 16 + DYN_WEAK_COMMON:
 617     case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
 618       // I guess a weak common symbol is better than a definition.
 619       return true;
 620
 621     case COMMON * 16 + DYN_WEAK_COMMON:
 622     case WEAK_COMMON * 16 + DYN_WEAK_COMMON:
 623     case DYN_COMMON * 16 + DYN_WEAK_COMMON:
 624     case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON:
 625       // Set the size to the maximum.
 626       *adjust_common_sizes = true;
 627       return false;
 628
 629     default:
 630       gold_unreachable();
 631     }
 632 }
 633
 634 // A special case of should_override which is only called for a strong
 635 // defined symbol from a regular object file.  This is used when
 636 // defining special symbols.
 637
 638 bool
 639 Symbol_table::should_override_with_special(const Symbol* to)
 640 {
 641   bool adjust_common_sizes;
 642   unsigned int frombits = global_flag | regular_flag | def_flag;
 643   bool ret = Symbol_table::should_override(to, frombits, NULL,
 644                                            &adjust_common_sizes);
 645   gold_assert(!adjust_common_sizes);
 646   return ret;
 647 }
 648
 649 // Override symbol base with a special symbol.
 650
 651 void
 652 Symbol::override_base_with_special(const Symbol* from)
 653 {
 654   gold_assert(this->name_ == from->name_ || this->has_alias());
 655
 656   this->source_ = from->source_;
 657   switch (from->source_)
 658     {
 659     case FROM_OBJECT:
 660       this->u_.from_object = from->u_.from_object;
 661       break;
 662     case IN_OUTPUT_DATA:
 663       this->u_.in_output_data = from->u_.in_output_data;
 664       break;
 665     case IN_OUTPUT_SEGMENT:
 666       this->u_.in_output_segment = from->u_.in_output_segment;
 667       break;
 668     case IS_CONSTANT:
 669     case IS_UNDEFINED:
 670       break;
 671     default:
 672       gold_unreachable();
 673       break;
 674     }
 675
 676   if (from->version_ != NULL && this->version_ != from->version_)
 677     {
 678       gold_assert(this->version_ == NULL);
 679       this->version_ = from->version_;
 680     }
 681
 682   this->type_ = from->type_;
 683   this->binding_ = from->binding_;
 684   this->visibility_ = from->visibility_;
 685   this->nonvis_ = from->nonvis_;
 686
 687   // Special symbols are always considered to be regular symbols.
 688   this->in_reg_ = true;
 689
 690   if (from->needs_dynsym_entry_)
 691     this->needs_dynsym_entry_ = true;
 692   if (from->needs_dynsym_value_)
 693     this->needs_dynsym_value_ = true;
 694
 695   // We shouldn't see these flags.  If we do, we need to handle them
 696   // somehow.
 697   gold_assert(!from->is_target_special_ || this->is_target_special_);
 698   gold_assert(!from->is_forwarder_);
 699   gold_assert(!from->has_plt_offset_);
 700   gold_assert(!from->has_warning_);
 701   gold_assert(!from->is_copied_from_dynobj_);
 702   gold_assert(!from->is_forced_local_);
 703 }
 704
 705 // Override a symbol with a special symbol.
 706
 707 template<int size>
 708 void
 709 Sized_symbol<size>::override_with_special(const Sized_symbol<size>* from)
 710 {
 711   this->override_base_with_special(from);
 712   this->value_ = from->value_;
 713   this->symsize_ = from->symsize_;
 714 }
 715
 716 // Override TOSYM with the special symbol FROMSYM.  This handles all
 717 // aliases of TOSYM.
 718
 719 template<int size>
 720 void
 721 Symbol_table::override_with_special(Sized_symbol<size>* tosym,
 722                                     const Sized_symbol<size>* fromsym)
 723 {
 724   tosym->override_with_special(fromsym);
 725   if (tosym->has_alias())
 726     {
 727       Symbol* sym = this->weak_aliases_[tosym];
 728       gold_assert(sym != NULL);
 729       Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
 730       do
 731         {
 732           ssym->override_with_special(fromsym);
 733           sym = this->weak_aliases_[ssym];
 734           gold_assert(sym != NULL);
 735           ssym = this->get_sized_symbol<size>(sym);
 736         }
 737       while (ssym != tosym);
 738     }
 739   if (tosym->binding() == elfcpp::STB_LOCAL)
 740     this->force_local(tosym);
 741 }
 742
 743 // Instantiate the templates we need.  We could use the configure
 744 // script to restrict this to only the ones needed for implemented
 745 // targets.
 746
 747 #ifdef HAVE_TARGET_32_LITTLE
 748 template
 749 void
 750 Symbol_table::resolve<32, false>(
 751     Sized_symbol<32>* to,
 752     const elfcpp::Sym<32, false>& sym,
 753     unsigned int st_shndx,
 754     bool is_ordinary,
 755     unsigned int orig_st_shndx,
 756     Object* object,
 757     const char* version);
 758 #endif
 759
 760 #ifdef HAVE_TARGET_32_BIG
 761 template
 762 void
 763 Symbol_table::resolve<32, true>(
 764     Sized_symbol<32>* to,
 765     const elfcpp::Sym<32, true>& sym,
 766     unsigned int st_shndx,
 767     bool is_ordinary,
 768     unsigned int orig_st_shndx,
 769     Object* object,
 770     const char* version);
 771 #endif
 772
 773 #ifdef HAVE_TARGET_64_LITTLE
 774 template
 775 void
 776 Symbol_table::resolve<64, false>(
 777     Sized_symbol<64>* to,
 778     const elfcpp::Sym<64, false>& sym,
 779     unsigned int st_shndx,
 780     bool is_ordinary,
 781     unsigned int orig_st_shndx,
 782     Object* object,
 783     const char* version);
 784 #endif
 785
 786 #ifdef HAVE_TARGET_64_BIG
 787 template
 788 void
 789 Symbol_table::resolve<64, true>(
 790     Sized_symbol<64>* to,
 791     const elfcpp::Sym<64, true>& sym,
 792     unsigned int st_shndx,
 793     bool is_ordinary,
 794     unsigned int orig_st_shndx,
 795     Object* object,
 796     const char* version);
 797 #endif
 798
 799 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
 800 template
 801 void
 802 Symbol_table::override_with_special<32>(Sized_symbol<32>*,
 803                                         const Sized_symbol<32>*);
 804 #endif
 805
 806 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
 807 template
 808 void
 809 Symbol_table::override_with_special<64>(Sized_symbol<64>*,
 810                                         const Sized_symbol<64>*);
 811 #endif
 812
 813 } // End namespace gold.