gold/resolve.cc

   1 // resolve.cc -- symbol resolution for gold
   2
   3 // Copyright 2006, 2007 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;
  89       ssym = this->get_sized_symbol SELECT_SIZE_NAME(size) (sym
  90                                                             SELECT_SIZE(size));
  91       do
  92         {
  93           ssym->override(fromsym, object, version);
  94           sym = this->weak_aliases_[ssym];
  95           gold_assert(sym != NULL);
  96           ssym = this->get_sized_symbol SELECT_SIZE_NAME(size) (
  97                                                 sym SELECT_SIZE(size));
  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, 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       bits |= common_flag;
 167       break;
 168
 169     default:
 170       if (type == elfcpp::STT_COMMON)
 171         bits |= common_flag;
 172       else
 173         bits |= def_flag;
 174       break;
 175     }
 176
 177   return bits;
 178 }
 179
 180 // Resolve a symbol.  This is called the second and subsequent times
 181 // we see a symbol.  TO is the pre-existing symbol.  ORIG_SYM is the
 182 // new symbol, seen in OBJECT.  SYM is almost always identical to
 183 // ORIG_SYM, but may be munged (for instance, if we determine the
 184 // symbol is in a to-be-discarded section, we'll set sym's shndx to
 185 // UNDEFINED).  VERSION of the version of SYM.
 186
 187 template<int size, bool big_endian>
 188 void
 189 Symbol_table::resolve(Sized_symbol<size>* to,
 190                       const elfcpp::Sym<size, big_endian>& sym,
 191                       const elfcpp::Sym<size, big_endian>& orig_sym,
 192                       Object* object, const char* version)
 193 {
 194   if (object->target()->has_resolve())
 195     {
 196       Sized_target<size, big_endian>* sized_target;
 197       sized_target = object->sized_target
 198                      SELECT_SIZE_ENDIAN_NAME(size, big_endian) (
 199                          SELECT_SIZE_ENDIAN_ONLY(size, big_endian));
 200       sized_target->resolve(to, sym, object, version);
 201       return;
 202     }
 203
 204   if (!object->is_dynamic())
 205     {
 206       // Record that we've seen this symbol in a regular object.
 207       to->set_in_reg();
 208     }
 209   else
 210     {
 211       // Record that we've seen this symbol in a dynamic object.
 212       to->set_in_dyn();
 213     }
 214
 215   unsigned int frombits = symbol_to_bits(sym.get_st_bind(),
 216                                          object->is_dynamic(),
 217                                          sym.get_st_shndx(),
 218                                          sym.get_st_type());
 219
 220   bool adjust_common_sizes;
 221   if (Symbol_table::should_override(to, frombits, object,
 222                                     &adjust_common_sizes))
 223     {
 224       typename Sized_symbol<size>::Size_type tosize = to->symsize();
 225
 226       this->override(to, sym, object, version);
 227
 228       if (adjust_common_sizes && tosize > to->symsize())
 229         to->set_symsize(tosize);
 230     }
 231   else
 232     {
 233       if (adjust_common_sizes && sym.get_st_size() > to->symsize())
 234         to->set_symsize(sym.get_st_size());
 235     }
 236
 237   // A new weak undefined reference, merging with an old weak
 238   // reference, could be a One Definition Rule (ODR) violation --
 239   // especially if the types or sizes of the references differ.  We'll
 240   // store such pairs and look them up later to make sure they
 241   // actually refer to the same lines of code.  (Note: not all ODR
 242   // violations can be found this way, and not everything this finds
 243   // is an ODR violation.  But it's helpful to warn about.)
 244   // We use orig_sym here because we want the symbol exactly as it
 245   // appears in the object file, not munged via our future processing.
 246   if (orig_sym.get_st_bind() == elfcpp::STB_WEAK
 247       && to->binding() == elfcpp::STB_WEAK
 248       && orig_sym.get_st_shndx() != elfcpp::SHN_UNDEF
 249       && to->shndx() != elfcpp::SHN_UNDEF
 250       && orig_sym.get_st_size() != 0    // Ignore weird 0-sized symbols.
 251       && to->symsize() != 0
 252       && (orig_sym.get_st_type() != to->type()
 253           || orig_sym.get_st_size() != to->symsize())
 254       // C does not have a concept of ODR, so we only need to do this
 255       // on C++ symbols.  These have (mangled) names starting with _Z.
 256       && to->name()[0] == '_' && to->name()[1] == 'Z')
 257     {
 258       Symbol_location from_location
 259           = { object, orig_sym.get_st_shndx(), orig_sym.get_st_value() };
 260       Symbol_location to_location = { to->object(), to->shndx(), to->value() };
 261       this->candidate_odr_violations_[to->name()].insert(from_location);
 262       this->candidate_odr_violations_[to->name()].insert(to_location);
 263     }
 264 }
 265
 266 // Handle the core of symbol resolution.  This is called with the
 267 // existing symbol, TO, and a bitflag describing the new symbol.  This
 268 // returns true if we should override the existing symbol with the new
 269 // one, and returns false otherwise.  It sets *ADJUST_COMMON_SIZES to
 270 // true if we should set the symbol size to the maximum of the TO and
 271 // FROM sizes.  It handles error conditions.
 272
 273 bool
 274 Symbol_table::should_override(const Symbol* to, unsigned int frombits,
 275                               Object* object, bool* adjust_common_sizes)
 276 {
 277   *adjust_common_sizes = false;
 278
 279   unsigned int tobits = symbol_to_bits(to->binding(),
 280                                        (to->source() == Symbol::FROM_OBJECT
 281                                         && to->object()->is_dynamic()),
 282                                        to->shndx(),
 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       // FIXME: Do a better job of reporting locations.
 317       gold_error(_("%s: multiple definition of %s"),
 318                  object != NULL ? object->name().c_str() : _("command line"),
 319                  to->name());
 320       gold_error(_("%s: previous definition here"),
 321                  (to->source() == Symbol::FROM_OBJECT
 322                   ? to->object()->name().c_str()
 323                   : _("command line")));
 324       return false;
 325
 326     case WEAK_DEF * 16 + DEF:
 327       // We've seen a weak definition, and now we see a strong
 328       // definition.  In the original SVR4 linker, this was treated as
 329       // a multiple definition error.  In the Solaris linker and the
 330       // GNU linker, a weak definition followed by a regular
 331       // definition causes the weak definition to be overridden.  We
 332       // are currently compatible with the GNU linker.  In the future
 333       // we should add a target specific option to change this.
 334       // FIXME.
 335       return true;
 336
 337     case DYN_DEF * 16 + DEF:
 338     case DYN_WEAK_DEF * 16 + DEF:
 339       // We've seen a definition in a dynamic object, and now we see a
 340       // definition in a regular object.  The definition in the
 341       // regular object overrides the definition in the dynamic
 342       // object.
 343       return true;
 344
 345     case UNDEF * 16 + DEF:
 346     case WEAK_UNDEF * 16 + DEF:
 347     case DYN_UNDEF * 16 + DEF:
 348     case DYN_WEAK_UNDEF * 16 + DEF:
 349       // We've seen an undefined reference, and now we see a
 350       // definition.  We use the definition.
 351       return true;
 352
 353     case COMMON * 16 + DEF:
 354     case WEAK_COMMON * 16 + DEF:
 355     case DYN_COMMON * 16 + DEF:
 356     case DYN_WEAK_COMMON * 16 + DEF:
 357       // We've seen a common symbol and now we see a definition.  The
 358       // definition overrides.  FIXME: We should optionally issue, version a
 359       // warning.
 360       return true;
 361
 362     case DEF * 16 + WEAK_DEF:
 363     case WEAK_DEF * 16 + WEAK_DEF:
 364       // We've seen a definition and now we see a weak definition.  We
 365       // ignore the new weak definition.
 366       return false;
 367
 368     case DYN_DEF * 16 + WEAK_DEF:
 369     case DYN_WEAK_DEF * 16 + WEAK_DEF:
 370       // We've seen a dynamic definition and now we see a regular weak
 371       // definition.  The regular weak definition overrides.
 372       return true;
 373
 374     case UNDEF * 16 + WEAK_DEF:
 375     case WEAK_UNDEF * 16 + WEAK_DEF:
 376     case DYN_UNDEF * 16 + WEAK_DEF:
 377     case DYN_WEAK_UNDEF * 16 + WEAK_DEF:
 378       // A weak definition of a currently undefined symbol.
 379       return true;
 380
 381     case COMMON * 16 + WEAK_DEF:
 382     case WEAK_COMMON * 16 + WEAK_DEF:
 383       // A weak definition does not override a common definition.
 384       return false;
 385
 386     case DYN_COMMON * 16 + WEAK_DEF:
 387     case DYN_WEAK_COMMON * 16 + WEAK_DEF:
 388       // A weak definition does override a definition in a dynamic
 389       // object.  FIXME: We should optionally issue a warning.
 390       return true;
 391
 392     case DEF * 16 + DYN_DEF:
 393     case WEAK_DEF * 16 + DYN_DEF:
 394     case DYN_DEF * 16 + DYN_DEF:
 395     case DYN_WEAK_DEF * 16 + DYN_DEF:
 396       // Ignore a dynamic definition if we already have a definition.
 397       return false;
 398
 399     case UNDEF * 16 + DYN_DEF:
 400     case WEAK_UNDEF * 16 + DYN_DEF:
 401     case DYN_UNDEF * 16 + DYN_DEF:
 402     case DYN_WEAK_UNDEF * 16 + DYN_DEF:
 403       // Use a dynamic definition if we have a reference.
 404       return true;
 405
 406     case COMMON * 16 + DYN_DEF:
 407     case WEAK_COMMON * 16 + DYN_DEF:
 408     case DYN_COMMON * 16 + DYN_DEF:
 409     case DYN_WEAK_COMMON * 16 + DYN_DEF:
 410       // Ignore a dynamic definition if we already have a common
 411       // definition.
 412       return false;
 413
 414     case DEF * 16 + DYN_WEAK_DEF:
 415     case WEAK_DEF * 16 + DYN_WEAK_DEF:
 416     case DYN_DEF * 16 + DYN_WEAK_DEF:
 417     case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF:
 418       // Ignore a weak dynamic definition if we already have a
 419       // definition.
 420       return false;
 421
 422     case UNDEF * 16 + DYN_WEAK_DEF:
 423     case WEAK_UNDEF * 16 + DYN_WEAK_DEF:
 424     case DYN_UNDEF * 16 + DYN_WEAK_DEF:
 425     case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF:
 426       // Use a weak dynamic definition if we have a reference.
 427       return true;
 428
 429     case COMMON * 16 + DYN_WEAK_DEF:
 430     case WEAK_COMMON * 16 + DYN_WEAK_DEF:
 431     case DYN_COMMON * 16 + DYN_WEAK_DEF:
 432     case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF:
 433       // Ignore a weak dynamic definition if we already have a common
 434       // definition.
 435       return false;
 436
 437     case DEF * 16 + UNDEF:
 438     case WEAK_DEF * 16 + UNDEF:
 439     case DYN_DEF * 16 + UNDEF:
 440     case DYN_WEAK_DEF * 16 + UNDEF:
 441     case UNDEF * 16 + UNDEF:
 442       // A new undefined reference tells us nothing.
 443       return false;
 444
 445     case WEAK_UNDEF * 16 + UNDEF:
 446     case DYN_UNDEF * 16 + UNDEF:
 447     case DYN_WEAK_UNDEF * 16 + UNDEF:
 448       // A strong undef overrides a dynamic or weak undef.
 449       return true;
 450
 451     case COMMON * 16 + UNDEF:
 452     case WEAK_COMMON * 16 + UNDEF:
 453     case DYN_COMMON * 16 + UNDEF:
 454     case DYN_WEAK_COMMON * 16 + UNDEF:
 455       // A new undefined reference tells us nothing.
 456       return false;
 457
 458     case DEF * 16 + WEAK_UNDEF:
 459     case WEAK_DEF * 16 + WEAK_UNDEF:
 460     case DYN_DEF * 16 + WEAK_UNDEF:
 461     case DYN_WEAK_DEF * 16 + WEAK_UNDEF:
 462     case UNDEF * 16 + WEAK_UNDEF:
 463     case WEAK_UNDEF * 16 + WEAK_UNDEF:
 464     case DYN_UNDEF * 16 + WEAK_UNDEF:
 465     case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF:
 466     case COMMON * 16 + WEAK_UNDEF:
 467     case WEAK_COMMON * 16 + WEAK_UNDEF:
 468     case DYN_COMMON * 16 + WEAK_UNDEF:
 469     case DYN_WEAK_COMMON * 16 + WEAK_UNDEF:
 470       // A new weak undefined reference tells us nothing.
 471       return false;
 472
 473     case DEF * 16 + DYN_UNDEF:
 474     case WEAK_DEF * 16 + DYN_UNDEF:
 475     case DYN_DEF * 16 + DYN_UNDEF:
 476     case DYN_WEAK_DEF * 16 + DYN_UNDEF:
 477     case UNDEF * 16 + DYN_UNDEF:
 478     case WEAK_UNDEF * 16 + DYN_UNDEF:
 479     case DYN_UNDEF * 16 + DYN_UNDEF:
 480     case DYN_WEAK_UNDEF * 16 + DYN_UNDEF:
 481     case COMMON * 16 + DYN_UNDEF:
 482     case WEAK_COMMON * 16 + DYN_UNDEF:
 483     case DYN_COMMON * 16 + DYN_UNDEF:
 484     case DYN_WEAK_COMMON * 16 + DYN_UNDEF:
 485       // A new dynamic undefined reference tells us nothing.
 486       return false;
 487
 488     case DEF * 16 + DYN_WEAK_UNDEF:
 489     case WEAK_DEF * 16 + DYN_WEAK_UNDEF:
 490     case DYN_DEF * 16 + DYN_WEAK_UNDEF:
 491     case DYN_WEAK_DEF * 16 + DYN_WEAK_UNDEF:
 492     case UNDEF * 16 + DYN_WEAK_UNDEF:
 493     case WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
 494     case DYN_UNDEF * 16 + DYN_WEAK_UNDEF:
 495     case DYN_WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
 496     case COMMON * 16 + DYN_WEAK_UNDEF:
 497     case WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
 498     case DYN_COMMON * 16 + DYN_WEAK_UNDEF:
 499     case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
 500       // A new weak dynamic undefined reference tells us nothing.
 501       return false;
 502
 503     case DEF * 16 + COMMON:
 504       // A common symbol does not override a definition.
 505       return false;
 506
 507     case WEAK_DEF * 16 + COMMON:
 508     case DYN_DEF * 16 + COMMON:
 509     case DYN_WEAK_DEF * 16 + COMMON:
 510       // A common symbol does override a weak definition or a dynamic
 511       // definition.
 512       return true;
 513
 514     case UNDEF * 16 + COMMON:
 515     case WEAK_UNDEF * 16 + COMMON:
 516     case DYN_UNDEF * 16 + COMMON:
 517     case DYN_WEAK_UNDEF * 16 + COMMON:
 518       // A common symbol is a definition for a reference.
 519       return true;
 520
 521     case COMMON * 16 + COMMON:
 522       // Set the size to the maximum.
 523       *adjust_common_sizes = true;
 524       return false;
 525
 526     case WEAK_COMMON * 16 + COMMON:
 527       // I'm not sure just what a weak common symbol means, but
 528       // presumably it can be overridden by a regular common symbol.
 529       return true;
 530
 531     case DYN_COMMON * 16 + COMMON:
 532     case DYN_WEAK_COMMON * 16 + COMMON:
 533       // Use the real common symbol, but adjust the size if necessary.
 534       *adjust_common_sizes = true;
 535       return true;
 536
 537     case DEF * 16 + WEAK_COMMON:
 538     case WEAK_DEF * 16 + WEAK_COMMON:
 539     case DYN_DEF * 16 + WEAK_COMMON:
 540     case DYN_WEAK_DEF * 16 + WEAK_COMMON:
 541       // Whatever a weak common symbol is, it won't override a
 542       // definition.
 543       return false;
 544
 545     case UNDEF * 16 + WEAK_COMMON:
 546     case WEAK_UNDEF * 16 + WEAK_COMMON:
 547     case DYN_UNDEF * 16 + WEAK_COMMON:
 548     case DYN_WEAK_UNDEF * 16 + WEAK_COMMON:
 549       // A weak common symbol is better than an undefined symbol.
 550       return true;
 551
 552     case COMMON * 16 + WEAK_COMMON:
 553     case WEAK_COMMON * 16 + WEAK_COMMON:
 554     case DYN_COMMON * 16 + WEAK_COMMON:
 555     case DYN_WEAK_COMMON * 16 + WEAK_COMMON:
 556       // Ignore a weak common symbol in the presence of a real common
 557       // symbol.
 558       return false;
 559
 560     case DEF * 16 + DYN_COMMON:
 561     case WEAK_DEF * 16 + DYN_COMMON:
 562     case DYN_DEF * 16 + DYN_COMMON:
 563     case DYN_WEAK_DEF * 16 + DYN_COMMON:
 564       // Ignore a dynamic common symbol in the presence of a
 565       // definition.
 566       return false;
 567
 568     case UNDEF * 16 + DYN_COMMON:
 569     case WEAK_UNDEF * 16 + DYN_COMMON:
 570     case DYN_UNDEF * 16 + DYN_COMMON:
 571     case DYN_WEAK_UNDEF * 16 + DYN_COMMON:
 572       // A dynamic common symbol is a definition of sorts.
 573       return true;
 574
 575     case COMMON * 16 + DYN_COMMON:
 576     case WEAK_COMMON * 16 + DYN_COMMON:
 577     case DYN_COMMON * 16 + DYN_COMMON:
 578     case DYN_WEAK_COMMON * 16 + DYN_COMMON:
 579       // Set the size to the maximum.
 580       *adjust_common_sizes = true;
 581       return false;
 582
 583     case DEF * 16 + DYN_WEAK_COMMON:
 584     case WEAK_DEF * 16 + DYN_WEAK_COMMON:
 585     case DYN_DEF * 16 + DYN_WEAK_COMMON:
 586     case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON:
 587       // A common symbol is ignored in the face of a definition.
 588       return false;
 589
 590     case UNDEF * 16 + DYN_WEAK_COMMON:
 591     case WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
 592     case DYN_UNDEF * 16 + DYN_WEAK_COMMON:
 593     case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
 594       // I guess a weak common symbol is better than a definition.
 595       return true;
 596
 597     case COMMON * 16 + DYN_WEAK_COMMON:
 598     case WEAK_COMMON * 16 + DYN_WEAK_COMMON:
 599     case DYN_COMMON * 16 + DYN_WEAK_COMMON:
 600     case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON:
 601       // Set the size to the maximum.
 602       *adjust_common_sizes = true;
 603       return false;
 604
 605     default:
 606       gold_unreachable();
 607     }
 608 }
 609
 610 // A special case of should_override which is only called for a strong
 611 // defined symbol from a regular object file.  This is used when
 612 // defining special symbols.
 613
 614 bool
 615 Symbol_table::should_override_with_special(const Symbol* to)
 616 {
 617   bool adjust_common_sizes;
 618   unsigned int frombits = global_flag | regular_flag | def_flag;
 619   bool ret = Symbol_table::should_override(to, frombits, NULL,
 620                                            &adjust_common_sizes);
 621   gold_assert(!adjust_common_sizes);
 622   return ret;
 623 }
 624
 625 // Override symbol base with a special symbol.
 626
 627 void
 628 Symbol::override_base_with_special(const Symbol* from)
 629 {
 630   gold_assert(this->name_ == from->name_ || this->has_alias());
 631
 632   this->source_ = from->source_;
 633   switch (from->source_)
 634     {
 635     case FROM_OBJECT:
 636       this->u_.from_object = from->u_.from_object;
 637       break;
 638     case IN_OUTPUT_DATA:
 639       this->u_.in_output_data = from->u_.in_output_data;
 640       break;
 641     case IN_OUTPUT_SEGMENT:
 642       this->u_.in_output_segment = from->u_.in_output_segment;
 643       break;
 644     case CONSTANT:
 645       break;
 646     default:
 647       gold_unreachable();
 648       break;
 649     }
 650
 651   if (from->version_ != NULL && this->version_ != from->version_)
 652     {
 653       gold_assert(this->version_ == NULL);
 654       this->version_ = from->version_;
 655     }
 656
 657   this->type_ = from->type_;
 658   this->binding_ = from->binding_;
 659   this->visibility_ = from->visibility_;
 660   this->nonvis_ = from->nonvis_;
 661
 662   // Special symbols are always considered to be regular symbols.
 663   this->in_reg_ = true;
 664
 665   if (from->needs_dynsym_entry_)
 666     this->needs_dynsym_entry_ = true;
 667   if (from->needs_dynsym_value_)
 668     this->needs_dynsym_value_ = true;
 669
 670   // We shouldn't see these flags.  If we do, we need to handle them
 671   // somehow.
 672   gold_assert(!from->is_target_special_ || this->is_target_special_);
 673   gold_assert(!from->is_forwarder_);
 674   gold_assert(!from->has_got_offset_);
 675   gold_assert(!from->has_plt_offset_);
 676   gold_assert(!from->has_warning_);
 677   gold_assert(!from->is_copied_from_dynobj_);
 678 }
 679
 680 // Override a symbol with a special symbol.
 681
 682 template<int size>
 683 void
 684 Sized_symbol<size>::override_with_special(const Sized_symbol<size>* from)
 685 {
 686   this->override_base_with_special(from);
 687   this->value_ = from->value_;
 688   this->symsize_ = from->symsize_;
 689 }
 690
 691 // Override TOSYM with the special symbol FROMSYM.  This handles all
 692 // aliases of TOSYM.
 693
 694 template<int size>
 695 void
 696 Symbol_table::override_with_special(Sized_symbol<size>* tosym,
 697                                     const Sized_symbol<size>* fromsym)
 698 {
 699   tosym->override_with_special(fromsym);
 700   if (tosym->has_alias())
 701     {
 702       Symbol* sym = this->weak_aliases_[tosym];
 703       gold_assert(sym != NULL);
 704       Sized_symbol<size>* ssym;
 705       ssym = this->get_sized_symbol SELECT_SIZE_NAME(size) (sym
 706                                                             SELECT_SIZE(size));
 707       do
 708         {
 709           ssym->override_with_special(fromsym);
 710           sym = this->weak_aliases_[ssym];
 711           gold_assert(sym != NULL);
 712           ssym = this->get_sized_symbol SELECT_SIZE_NAME(size) (
 713                                                 sym SELECT_SIZE(size));
 714         }
 715       while (ssym != tosym);
 716     }
 717 }
 718
 719 // Instantiate the templates we need.  We could use the configure
 720 // script to restrict this to only the ones needed for implemented
 721 // targets.
 722
 723 #ifdef HAVE_TARGET_32_LITTLE
 724 template
 725 void
 726 Symbol_table::resolve<32, false>(
 727     Sized_symbol<32>* to,
 728     const elfcpp::Sym<32, false>& sym,
 729     const elfcpp::Sym<32, false>& orig_sym,
 730     Object* object,
 731     const char* version);
 732 #endif
 733
 734 #ifdef HAVE_TARGET_32_BIG
 735 template
 736 void
 737 Symbol_table::resolve<32, true>(
 738     Sized_symbol<32>* to,
 739     const elfcpp::Sym<32, true>& sym,
 740     const elfcpp::Sym<32, true>& orig_sym,
 741     Object* object,
 742     const char* version);
 743 #endif
 744
 745 #ifdef HAVE_TARGET_64_LITTLE
 746 template
 747 void
 748 Symbol_table::resolve<64, false>(
 749     Sized_symbol<64>* to,
 750     const elfcpp::Sym<64, false>& sym,
 751     const elfcpp::Sym<64, false>& orig_sym,
 752     Object* object,
 753     const char* version);
 754 #endif
 755
 756 #ifdef HAVE_TARGET_64_BIG
 757 template
 758 void
 759 Symbol_table::resolve<64, true>(
 760     Sized_symbol<64>* to,
 761     const elfcpp::Sym<64, true>& sym,
 762     const elfcpp::Sym<64, true>& orig_sym,
 763     Object* object,
 764     const char* version);
 765 #endif
 766
 767 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
 768 template
 769 void
 770 Symbol_table::override_with_special<32>(Sized_symbol<32>*,
 771                                         const Sized_symbol<32>*);
 772 #endif
 773
 774 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
 775 template
 776 void
 777 Symbol_table::override_with_special<64>(Sized_symbol<64>*,
 778                                         const Sized_symbol<64>*);
 779 #endif
 780
 781 } // End namespace gold.