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::FROM_OBJECT)
 285     tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_ABS, false,
 286                             to->type());
 287   else
 288     {
 289       bool is_ordinary;
 290       unsigned int shndx = to->shndx(&is_ordinary);
 291       tobits = symbol_to_bits(to->binding(),
 292                               to->object()->is_dynamic(),
 293                               shndx,
 294                               is_ordinary,
 295                               to->type());
 296     }
 297
 298   // FIXME: Warn if either but not both of TO and SYM are STT_TLS.
 299
 300   // We use a giant switch table for symbol resolution.  This code is
 301   // unwieldy, but: 1) it is efficient; 2) we definitely handle all
 302   // cases; 3) it is easy to change the handling of a particular case.
 303   // The alternative would be a series of conditionals, but it is easy
 304   // to get the ordering wrong.  This could also be done as a table,
 305   // but that is no easier to understand than this large switch
 306   // statement.
 307
 308   // These are the values generated by the bit codes.
 309   enum
 310   {
 311     DEF =              global_flag | regular_flag | def_flag,
 312     WEAK_DEF =         weak_flag   | regular_flag | def_flag,
 313     DYN_DEF =          global_flag | dynamic_flag | def_flag,
 314     DYN_WEAK_DEF =     weak_flag   | dynamic_flag | def_flag,
 315     UNDEF =            global_flag | regular_flag | undef_flag,
 316     WEAK_UNDEF =       weak_flag   | regular_flag | undef_flag,
 317     DYN_UNDEF =        global_flag | dynamic_flag | undef_flag,
 318     DYN_WEAK_UNDEF =   weak_flag   | dynamic_flag | undef_flag,
 319     COMMON =           global_flag | regular_flag | common_flag,
 320     WEAK_COMMON =      weak_flag   | regular_flag | common_flag,
 321     DYN_COMMON =       global_flag | dynamic_flag | common_flag,
 322     DYN_WEAK_COMMON =  weak_flag   | dynamic_flag | common_flag
 323   };
 324
 325   switch (tobits * 16 + frombits)
 326     {
 327     case DEF * 16 + DEF:
 328       // Two definitions of the same symbol.
 329
 330       // If either symbol is defined by an object included using
 331       // --just-symbols, then don't warn.  This is for compatibility
 332       // with the GNU linker.  FIXME: This is a hack.
 333       if ((to->source() == Symbol::FROM_OBJECT && to->object()->just_symbols())
 334           || object->just_symbols())
 335         return false;
 336
 337       // FIXME: Do a better job of reporting locations.
 338       gold_error(_("%s: multiple definition of %s"),
 339                  object != NULL ? object->name().c_str() : _("command line"),
 340                  to->demangled_name().c_str());
 341       gold_error(_("%s: previous definition here"),
 342                  (to->source() == Symbol::FROM_OBJECT
 343                   ? to->object()->name().c_str()
 344                   : _("command line")));
 345       return false;
 346
 347     case WEAK_DEF * 16 + DEF:
 348       // We've seen a weak definition, and now we see a strong
 349       // definition.  In the original SVR4 linker, this was treated as
 350       // a multiple definition error.  In the Solaris linker and the
 351       // GNU linker, a weak definition followed by a regular
 352       // definition causes the weak definition to be overridden.  We
 353       // are currently compatible with the GNU linker.  In the future
 354       // we should add a target specific option to change this.
 355       // FIXME.
 356       return true;
 357
 358     case DYN_DEF * 16 + DEF:
 359     case DYN_WEAK_DEF * 16 + DEF:
 360       // We've seen a definition in a dynamic object, and now we see a
 361       // definition in a regular object.  The definition in the
 362       // regular object overrides the definition in the dynamic
 363       // object.
 364       return true;
 365
 366     case UNDEF * 16 + DEF:
 367     case WEAK_UNDEF * 16 + DEF:
 368     case DYN_UNDEF * 16 + DEF:
 369     case DYN_WEAK_UNDEF * 16 + DEF:
 370       // We've seen an undefined reference, and now we see a
 371       // definition.  We use the definition.
 372       return true;
 373
 374     case COMMON * 16 + DEF:
 375     case WEAK_COMMON * 16 + DEF:
 376     case DYN_COMMON * 16 + DEF:
 377     case DYN_WEAK_COMMON * 16 + DEF:
 378       // We've seen a common symbol and now we see a definition.  The
 379       // definition overrides.  FIXME: We should optionally issue, version a
 380       // warning.
 381       return true;
 382
 383     case DEF * 16 + WEAK_DEF:
 384     case WEAK_DEF * 16 + WEAK_DEF:
 385       // We've seen a definition and now we see a weak definition.  We
 386       // ignore the new weak definition.
 387       return false;
 388
 389     case DYN_DEF * 16 + WEAK_DEF:
 390     case DYN_WEAK_DEF * 16 + WEAK_DEF:
 391       // We've seen a dynamic definition and now we see a regular weak
 392       // definition.  The regular weak definition overrides.
 393       return true;
 394
 395     case UNDEF * 16 + WEAK_DEF:
 396     case WEAK_UNDEF * 16 + WEAK_DEF:
 397     case DYN_UNDEF * 16 + WEAK_DEF:
 398     case DYN_WEAK_UNDEF * 16 + WEAK_DEF:
 399       // A weak definition of a currently undefined symbol.
 400       return true;
 401
 402     case COMMON * 16 + WEAK_DEF:
 403     case WEAK_COMMON * 16 + WEAK_DEF:
 404       // A weak definition does not override a common definition.
 405       return false;
 406
 407     case DYN_COMMON * 16 + WEAK_DEF:
 408     case DYN_WEAK_COMMON * 16 + WEAK_DEF:
 409       // A weak definition does override a definition in a dynamic
 410       // object.  FIXME: We should optionally issue a warning.
 411       return true;
 412
 413     case DEF * 16 + DYN_DEF:
 414     case WEAK_DEF * 16 + DYN_DEF:
 415     case DYN_DEF * 16 + DYN_DEF:
 416     case DYN_WEAK_DEF * 16 + DYN_DEF:
 417       // Ignore a dynamic definition if we already have a definition.
 418       return false;
 419
 420     case UNDEF * 16 + DYN_DEF:
 421     case WEAK_UNDEF * 16 + DYN_DEF:
 422     case DYN_UNDEF * 16 + DYN_DEF:
 423     case DYN_WEAK_UNDEF * 16 + DYN_DEF:
 424       // Use a dynamic definition if we have a reference.
 425       return true;
 426
 427     case COMMON * 16 + DYN_DEF:
 428     case WEAK_COMMON * 16 + DYN_DEF:
 429     case DYN_COMMON * 16 + DYN_DEF:
 430     case DYN_WEAK_COMMON * 16 + DYN_DEF:
 431       // Ignore a dynamic definition if we already have a common
 432       // definition.
 433       return false;
 434
 435     case DEF * 16 + DYN_WEAK_DEF:
 436     case WEAK_DEF * 16 + DYN_WEAK_DEF:
 437     case DYN_DEF * 16 + DYN_WEAK_DEF:
 438     case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF:
 439       // Ignore a weak dynamic definition if we already have a
 440       // definition.
 441       return false;
 442
 443     case UNDEF * 16 + DYN_WEAK_DEF:
 444     case WEAK_UNDEF * 16 + DYN_WEAK_DEF:
 445     case DYN_UNDEF * 16 + DYN_WEAK_DEF:
 446     case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF:
 447       // Use a weak dynamic definition if we have a reference.
 448       return true;
 449
 450     case COMMON * 16 + DYN_WEAK_DEF:
 451     case WEAK_COMMON * 16 + DYN_WEAK_DEF:
 452     case DYN_COMMON * 16 + DYN_WEAK_DEF:
 453     case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF:
 454       // Ignore a weak dynamic definition if we already have a common
 455       // definition.
 456       return false;
 457
 458     case DEF * 16 + UNDEF:
 459     case WEAK_DEF * 16 + UNDEF:
 460     case DYN_DEF * 16 + UNDEF:
 461     case DYN_WEAK_DEF * 16 + UNDEF:
 462     case UNDEF * 16 + UNDEF:
 463       // A new undefined reference tells us nothing.
 464       return false;
 465
 466     case WEAK_UNDEF * 16 + UNDEF:
 467     case DYN_UNDEF * 16 + UNDEF:
 468     case DYN_WEAK_UNDEF * 16 + UNDEF:
 469       // A strong undef overrides a dynamic or weak undef.
 470       return true;
 471
 472     case COMMON * 16 + UNDEF:
 473     case WEAK_COMMON * 16 + UNDEF:
 474     case DYN_COMMON * 16 + UNDEF:
 475     case DYN_WEAK_COMMON * 16 + UNDEF:
 476       // A new undefined reference tells us nothing.
 477       return false;
 478
 479     case DEF * 16 + WEAK_UNDEF:
 480     case WEAK_DEF * 16 + WEAK_UNDEF:
 481     case DYN_DEF * 16 + WEAK_UNDEF:
 482     case DYN_WEAK_DEF * 16 + WEAK_UNDEF:
 483     case UNDEF * 16 + WEAK_UNDEF:
 484     case WEAK_UNDEF * 16 + WEAK_UNDEF:
 485     case DYN_UNDEF * 16 + WEAK_UNDEF:
 486     case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF:
 487     case COMMON * 16 + WEAK_UNDEF:
 488     case WEAK_COMMON * 16 + WEAK_UNDEF:
 489     case DYN_COMMON * 16 + WEAK_UNDEF:
 490     case DYN_WEAK_COMMON * 16 + WEAK_UNDEF:
 491       // A new weak undefined reference tells us nothing.
 492       return false;
 493
 494     case DEF * 16 + DYN_UNDEF:
 495     case WEAK_DEF * 16 + DYN_UNDEF:
 496     case DYN_DEF * 16 + DYN_UNDEF:
 497     case DYN_WEAK_DEF * 16 + DYN_UNDEF:
 498     case UNDEF * 16 + DYN_UNDEF:
 499     case WEAK_UNDEF * 16 + DYN_UNDEF:
 500     case DYN_UNDEF * 16 + DYN_UNDEF:
 501     case DYN_WEAK_UNDEF * 16 + DYN_UNDEF:
 502     case COMMON * 16 + DYN_UNDEF:
 503     case WEAK_COMMON * 16 + DYN_UNDEF:
 504     case DYN_COMMON * 16 + DYN_UNDEF:
 505     case DYN_WEAK_COMMON * 16 + DYN_UNDEF:
 506       // A new dynamic undefined reference tells us nothing.
 507       return false;
 508
 509     case DEF * 16 + DYN_WEAK_UNDEF:
 510     case WEAK_DEF * 16 + DYN_WEAK_UNDEF:
 511     case DYN_DEF * 16 + DYN_WEAK_UNDEF:
 512     case DYN_WEAK_DEF * 16 + DYN_WEAK_UNDEF:
 513     case UNDEF * 16 + DYN_WEAK_UNDEF:
 514     case WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
 515     case DYN_UNDEF * 16 + DYN_WEAK_UNDEF:
 516     case DYN_WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
 517     case COMMON * 16 + DYN_WEAK_UNDEF:
 518     case WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
 519     case DYN_COMMON * 16 + DYN_WEAK_UNDEF:
 520     case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
 521       // A new weak dynamic undefined reference tells us nothing.
 522       return false;
 523
 524     case DEF * 16 + COMMON:
 525       // A common symbol does not override a definition.
 526       return false;
 527
 528     case WEAK_DEF * 16 + COMMON:
 529     case DYN_DEF * 16 + COMMON:
 530     case DYN_WEAK_DEF * 16 + COMMON:
 531       // A common symbol does override a weak definition or a dynamic
 532       // definition.
 533       return true;
 534
 535     case UNDEF * 16 + COMMON:
 536     case WEAK_UNDEF * 16 + COMMON:
 537     case DYN_UNDEF * 16 + COMMON:
 538     case DYN_WEAK_UNDEF * 16 + COMMON:
 539       // A common symbol is a definition for a reference.
 540       return true;
 541
 542     case COMMON * 16 + COMMON:
 543       // Set the size to the maximum.
 544       *adjust_common_sizes = true;
 545       return false;
 546
 547     case WEAK_COMMON * 16 + COMMON:
 548       // I'm not sure just what a weak common symbol means, but
 549       // presumably it can be overridden by a regular common symbol.
 550       return true;
 551
 552     case DYN_COMMON * 16 + COMMON:
 553     case DYN_WEAK_COMMON * 16 + COMMON:
 554       // Use the real common symbol, but adjust the size if necessary.
 555       *adjust_common_sizes = true;
 556       return true;
 557
 558     case DEF * 16 + WEAK_COMMON:
 559     case WEAK_DEF * 16 + WEAK_COMMON:
 560     case DYN_DEF * 16 + WEAK_COMMON:
 561     case DYN_WEAK_DEF * 16 + WEAK_COMMON:
 562       // Whatever a weak common symbol is, it won't override a
 563       // definition.
 564       return false;
 565
 566     case UNDEF * 16 + WEAK_COMMON:
 567     case WEAK_UNDEF * 16 + WEAK_COMMON:
 568     case DYN_UNDEF * 16 + WEAK_COMMON:
 569     case DYN_WEAK_UNDEF * 16 + WEAK_COMMON:
 570       // A weak common symbol is better than an undefined symbol.
 571       return true;
 572
 573     case COMMON * 16 + WEAK_COMMON:
 574     case WEAK_COMMON * 16 + WEAK_COMMON:
 575     case DYN_COMMON * 16 + WEAK_COMMON:
 576     case DYN_WEAK_COMMON * 16 + WEAK_COMMON:
 577       // Ignore a weak common symbol in the presence of a real common
 578       // symbol.
 579       return false;
 580
 581     case DEF * 16 + DYN_COMMON:
 582     case WEAK_DEF * 16 + DYN_COMMON:
 583     case DYN_DEF * 16 + DYN_COMMON:
 584     case DYN_WEAK_DEF * 16 + DYN_COMMON:
 585       // Ignore a dynamic common symbol in the presence of a
 586       // definition.
 587       return false;
 588
 589     case UNDEF * 16 + DYN_COMMON:
 590     case WEAK_UNDEF * 16 + DYN_COMMON:
 591     case DYN_UNDEF * 16 + DYN_COMMON:
 592     case DYN_WEAK_UNDEF * 16 + DYN_COMMON:
 593       // A dynamic common symbol is a definition of sorts.
 594       return true;
 595
 596     case COMMON * 16 + DYN_COMMON:
 597     case WEAK_COMMON * 16 + DYN_COMMON:
 598     case DYN_COMMON * 16 + DYN_COMMON:
 599     case DYN_WEAK_COMMON * 16 + DYN_COMMON:
 600       // Set the size to the maximum.
 601       *adjust_common_sizes = true;
 602       return false;
 603
 604     case DEF * 16 + DYN_WEAK_COMMON:
 605     case WEAK_DEF * 16 + DYN_WEAK_COMMON:
 606     case DYN_DEF * 16 + DYN_WEAK_COMMON:
 607     case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON:
 608       // A common symbol is ignored in the face of a definition.
 609       return false;
 610
 611     case UNDEF * 16 + DYN_WEAK_COMMON:
 612     case WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
 613     case DYN_UNDEF * 16 + DYN_WEAK_COMMON:
 614     case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
 615       // I guess a weak common symbol is better than a definition.
 616       return true;
 617
 618     case COMMON * 16 + DYN_WEAK_COMMON:
 619     case WEAK_COMMON * 16 + DYN_WEAK_COMMON:
 620     case DYN_COMMON * 16 + DYN_WEAK_COMMON:
 621     case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON:
 622       // Set the size to the maximum.
 623       *adjust_common_sizes = true;
 624       return false;
 625
 626     default:
 627       gold_unreachable();
 628     }
 629 }
 630
 631 // A special case of should_override which is only called for a strong
 632 // defined symbol from a regular object file.  This is used when
 633 // defining special symbols.
 634
 635 bool
 636 Symbol_table::should_override_with_special(const Symbol* to)
 637 {
 638   bool adjust_common_sizes;
 639   unsigned int frombits = global_flag | regular_flag | def_flag;
 640   bool ret = Symbol_table::should_override(to, frombits, NULL,
 641                                            &adjust_common_sizes);
 642   gold_assert(!adjust_common_sizes);
 643   return ret;
 644 }
 645
 646 // Override symbol base with a special symbol.
 647
 648 void
 649 Symbol::override_base_with_special(const Symbol* from)
 650 {
 651   gold_assert(this->name_ == from->name_ || this->has_alias());
 652
 653   this->source_ = from->source_;
 654   switch (from->source_)
 655     {
 656     case FROM_OBJECT:
 657       this->u_.from_object = from->u_.from_object;
 658       break;
 659     case IN_OUTPUT_DATA:
 660       this->u_.in_output_data = from->u_.in_output_data;
 661       break;
 662     case IN_OUTPUT_SEGMENT:
 663       this->u_.in_output_segment = from->u_.in_output_segment;
 664       break;
 665     case CONSTANT:
 666       break;
 667     default:
 668       gold_unreachable();
 669       break;
 670     }
 671
 672   if (from->version_ != NULL && this->version_ != from->version_)
 673     {
 674       gold_assert(this->version_ == NULL);
 675       this->version_ = from->version_;
 676     }
 677
 678   this->type_ = from->type_;
 679   this->binding_ = from->binding_;
 680   this->visibility_ = from->visibility_;
 681   this->nonvis_ = from->nonvis_;
 682
 683   // Special symbols are always considered to be regular symbols.
 684   this->in_reg_ = true;
 685
 686   if (from->needs_dynsym_entry_)
 687     this->needs_dynsym_entry_ = true;
 688   if (from->needs_dynsym_value_)
 689     this->needs_dynsym_value_ = true;
 690
 691   // We shouldn't see these flags.  If we do, we need to handle them
 692   // somehow.
 693   gold_assert(!from->is_target_special_ || this->is_target_special_);
 694   gold_assert(!from->is_forwarder_);
 695   gold_assert(!from->has_plt_offset_);
 696   gold_assert(!from->has_warning_);
 697   gold_assert(!from->is_copied_from_dynobj_);
 698   gold_assert(!from->is_forced_local_);
 699 }
 700
 701 // Override a symbol with a special symbol.
 702
 703 template<int size>
 704 void
 705 Sized_symbol<size>::override_with_special(const Sized_symbol<size>* from)
 706 {
 707   this->override_base_with_special(from);
 708   this->value_ = from->value_;
 709   this->symsize_ = from->symsize_;
 710 }
 711
 712 // Override TOSYM with the special symbol FROMSYM.  This handles all
 713 // aliases of TOSYM.
 714
 715 template<int size>
 716 void
 717 Symbol_table::override_with_special(Sized_symbol<size>* tosym,
 718                                     const Sized_symbol<size>* fromsym)
 719 {
 720   tosym->override_with_special(fromsym);
 721   if (tosym->has_alias())
 722     {
 723       Symbol* sym = this->weak_aliases_[tosym];
 724       gold_assert(sym != NULL);
 725       Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
 726       do
 727         {
 728           ssym->override_with_special(fromsym);
 729           sym = this->weak_aliases_[ssym];
 730           gold_assert(sym != NULL);
 731           ssym = this->get_sized_symbol<size>(sym);
 732         }
 733       while (ssym != tosym);
 734     }
 735   if (tosym->binding() == elfcpp::STB_LOCAL)
 736     this->force_local(tosym);
 737 }
 738
 739 // Instantiate the templates we need.  We could use the configure
 740 // script to restrict this to only the ones needed for implemented
 741 // targets.
 742
 743 #ifdef HAVE_TARGET_32_LITTLE
 744 template
 745 void
 746 Symbol_table::resolve<32, false>(
 747     Sized_symbol<32>* to,
 748     const elfcpp::Sym<32, false>& sym,
 749     unsigned int st_shndx,
 750     bool is_ordinary,
 751     unsigned int orig_st_shndx,
 752     Object* object,
 753     const char* version);
 754 #endif
 755
 756 #ifdef HAVE_TARGET_32_BIG
 757 template
 758 void
 759 Symbol_table::resolve<32, true>(
 760     Sized_symbol<32>* to,
 761     const elfcpp::Sym<32, true>& sym,
 762     unsigned int st_shndx,
 763     bool is_ordinary,
 764     unsigned int orig_st_shndx,
 765     Object* object,
 766     const char* version);
 767 #endif
 768
 769 #ifdef HAVE_TARGET_64_LITTLE
 770 template
 771 void
 772 Symbol_table::resolve<64, false>(
 773     Sized_symbol<64>* to,
 774     const elfcpp::Sym<64, false>& sym,
 775     unsigned int st_shndx,
 776     bool is_ordinary,
 777     unsigned int orig_st_shndx,
 778     Object* object,
 779     const char* version);
 780 #endif
 781
 782 #ifdef HAVE_TARGET_64_BIG
 783 template
 784 void
 785 Symbol_table::resolve<64, true>(
 786     Sized_symbol<64>* to,
 787     const elfcpp::Sym<64, true>& sym,
 788     unsigned int st_shndx,
 789     bool is_ordinary,
 790     unsigned int orig_st_shndx,
 791     Object* object,
 792     const char* version);
 793 #endif
 794
 795 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
 796 template
 797 void
 798 Symbol_table::override_with_special<32>(Sized_symbol<32>*,
 799                                         const Sized_symbol<32>*);
 800 #endif
 801
 802 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
 803 template
 804 void
 805 Symbol_table::override_with_special<64>(Sized_symbol<64>*,
 806                                         const Sized_symbol<64>*);
 807 #endif
 808
 809 } // End namespace gold.