| 1 | // resolve.cc -- symbol resolution for gold |
| 2 | |
| 3 | // Copyright 2006, 2007, 2008, 2009 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 | #include "plugin.h" |
| 30 | |
| 31 | namespace gold |
| 32 | { |
| 33 | |
| 34 | // Symbol methods used in this file. |
| 35 | |
| 36 | // This symbol is being overridden by another symbol whose version is |
| 37 | // VERSION. Update the VERSION_ field accordingly. |
| 38 | |
| 39 | inline void |
| 40 | Symbol::override_version(const char* version) |
| 41 | { |
| 42 | if (version == NULL) |
| 43 | { |
| 44 | // This is the case where this symbol is NAME/VERSION, and the |
| 45 | // version was not marked as hidden. That makes it the default |
| 46 | // version, so we create NAME/NULL. Later we see another symbol |
| 47 | // NAME/NULL, and that symbol is overriding this one. In this |
| 48 | // case, since NAME/VERSION is the default, we make NAME/NULL |
| 49 | // override NAME/VERSION as well. They are already the same |
| 50 | // Symbol structure. Setting the VERSION_ field to NULL ensures |
| 51 | // that it will be output with the correct, empty, version. |
| 52 | this->version_ = version; |
| 53 | } |
| 54 | else |
| 55 | { |
| 56 | // This is the case where this symbol is NAME/VERSION_ONE, and |
| 57 | // now we see NAME/VERSION_TWO, and NAME/VERSION_TWO is |
| 58 | // overriding NAME. If VERSION_ONE and VERSION_TWO are |
| 59 | // different, then this can only happen when VERSION_ONE is NULL |
| 60 | // and VERSION_TWO is not hidden. |
| 61 | gold_assert(this->version_ == version || this->version_ == NULL); |
| 62 | this->version_ = version; |
| 63 | } |
| 64 | } |
| 65 | |
| 66 | // This symbol is being overidden by another symbol whose visibility |
| 67 | // is VISIBILITY. Updated the VISIBILITY_ field accordingly. |
| 68 | |
| 69 | inline void |
| 70 | Symbol::override_visibility(elfcpp::STV visibility) |
| 71 | { |
| 72 | // The rule for combining visibility is that we always choose the |
| 73 | // most constrained visibility. In order of increasing constraint, |
| 74 | // visibility goes PROTECTED, HIDDEN, INTERNAL. This is the reverse |
| 75 | // of the numeric values, so the effect is that we always want the |
| 76 | // smallest non-zero value. |
| 77 | if (visibility != elfcpp::STV_DEFAULT) |
| 78 | { |
| 79 | if (this->visibility_ == elfcpp::STV_DEFAULT) |
| 80 | this->visibility_ = visibility; |
| 81 | else if (this->visibility_ > visibility) |
| 82 | this->visibility_ = visibility; |
| 83 | } |
| 84 | } |
| 85 | |
| 86 | // Override the fields in Symbol. |
| 87 | |
| 88 | template<int size, bool big_endian> |
| 89 | void |
| 90 | Symbol::override_base(const elfcpp::Sym<size, big_endian>& sym, |
| 91 | unsigned int st_shndx, bool is_ordinary, |
| 92 | Object* object, const char* version) |
| 93 | { |
| 94 | gold_assert(this->source_ == FROM_OBJECT); |
| 95 | this->u_.from_object.object = object; |
| 96 | this->override_version(version); |
| 97 | this->u_.from_object.shndx = st_shndx; |
| 98 | this->is_ordinary_shndx_ = is_ordinary; |
| 99 | this->type_ = sym.get_st_type(); |
| 100 | this->binding_ = sym.get_st_bind(); |
| 101 | this->override_visibility(sym.get_st_visibility()); |
| 102 | this->nonvis_ = sym.get_st_nonvis(); |
| 103 | if (object->is_dynamic()) |
| 104 | this->in_dyn_ = true; |
| 105 | else |
| 106 | this->in_reg_ = true; |
| 107 | } |
| 108 | |
| 109 | // Override the fields in Sized_symbol. |
| 110 | |
| 111 | template<int size> |
| 112 | template<bool big_endian> |
| 113 | void |
| 114 | Sized_symbol<size>::override(const elfcpp::Sym<size, big_endian>& sym, |
| 115 | unsigned st_shndx, bool is_ordinary, |
| 116 | Object* object, const char* version) |
| 117 | { |
| 118 | this->override_base(sym, st_shndx, is_ordinary, object, version); |
| 119 | this->value_ = sym.get_st_value(); |
| 120 | this->symsize_ = sym.get_st_size(); |
| 121 | } |
| 122 | |
| 123 | // Override TOSYM with symbol FROMSYM, defined in OBJECT, with version |
| 124 | // VERSION. This handles all aliases of TOSYM. |
| 125 | |
| 126 | template<int size, bool big_endian> |
| 127 | void |
| 128 | Symbol_table::override(Sized_symbol<size>* tosym, |
| 129 | const elfcpp::Sym<size, big_endian>& fromsym, |
| 130 | unsigned int st_shndx, bool is_ordinary, |
| 131 | Object* object, const char* version) |
| 132 | { |
| 133 | tosym->override(fromsym, st_shndx, is_ordinary, object, version); |
| 134 | if (tosym->has_alias()) |
| 135 | { |
| 136 | Symbol* sym = this->weak_aliases_[tosym]; |
| 137 | gold_assert(sym != NULL); |
| 138 | Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym); |
| 139 | do |
| 140 | { |
| 141 | ssym->override(fromsym, st_shndx, is_ordinary, object, version); |
| 142 | sym = this->weak_aliases_[ssym]; |
| 143 | gold_assert(sym != NULL); |
| 144 | ssym = this->get_sized_symbol<size>(sym); |
| 145 | } |
| 146 | while (ssym != tosym); |
| 147 | } |
| 148 | } |
| 149 | |
| 150 | // The resolve functions build a little code for each symbol. |
| 151 | // Bit 0: 0 for global, 1 for weak. |
| 152 | // Bit 1: 0 for regular object, 1 for shared object |
| 153 | // Bits 2-3: 0 for normal, 1 for undefined, 2 for common |
| 154 | // This gives us values from 0 to 11. |
| 155 | |
| 156 | static const int global_or_weak_shift = 0; |
| 157 | static const unsigned int global_flag = 0 << global_or_weak_shift; |
| 158 | static const unsigned int weak_flag = 1 << global_or_weak_shift; |
| 159 | |
| 160 | static const int regular_or_dynamic_shift = 1; |
| 161 | static const unsigned int regular_flag = 0 << regular_or_dynamic_shift; |
| 162 | static const unsigned int dynamic_flag = 1 << regular_or_dynamic_shift; |
| 163 | |
| 164 | static const int def_undef_or_common_shift = 2; |
| 165 | static const unsigned int def_flag = 0 << def_undef_or_common_shift; |
| 166 | static const unsigned int undef_flag = 1 << def_undef_or_common_shift; |
| 167 | static const unsigned int common_flag = 2 << def_undef_or_common_shift; |
| 168 | |
| 169 | // This convenience function combines all the flags based on facts |
| 170 | // about the symbol. |
| 171 | |
| 172 | static unsigned int |
| 173 | symbol_to_bits(elfcpp::STB binding, bool is_dynamic, |
| 174 | unsigned int shndx, bool is_ordinary, elfcpp::STT type) |
| 175 | { |
| 176 | unsigned int bits; |
| 177 | |
| 178 | switch (binding) |
| 179 | { |
| 180 | case elfcpp::STB_GLOBAL: |
| 181 | bits = global_flag; |
| 182 | break; |
| 183 | |
| 184 | case elfcpp::STB_WEAK: |
| 185 | bits = weak_flag; |
| 186 | break; |
| 187 | |
| 188 | case elfcpp::STB_LOCAL: |
| 189 | // We should only see externally visible symbols in the symbol |
| 190 | // table. |
| 191 | gold_error(_("invalid STB_LOCAL symbol in external symbols")); |
| 192 | bits = global_flag; |
| 193 | |
| 194 | default: |
| 195 | // Any target which wants to handle STB_LOOS, etc., needs to |
| 196 | // define a resolve method. |
| 197 | gold_error(_("unsupported symbol binding")); |
| 198 | bits = global_flag; |
| 199 | } |
| 200 | |
| 201 | if (is_dynamic) |
| 202 | bits |= dynamic_flag; |
| 203 | else |
| 204 | bits |= regular_flag; |
| 205 | |
| 206 | switch (shndx) |
| 207 | { |
| 208 | case elfcpp::SHN_UNDEF: |
| 209 | bits |= undef_flag; |
| 210 | break; |
| 211 | |
| 212 | case elfcpp::SHN_COMMON: |
| 213 | if (!is_ordinary) |
| 214 | bits |= common_flag; |
| 215 | break; |
| 216 | |
| 217 | default: |
| 218 | if (type == elfcpp::STT_COMMON) |
| 219 | bits |= common_flag; |
| 220 | else if (!is_ordinary && Symbol::is_common_shndx(shndx)) |
| 221 | bits |= common_flag; |
| 222 | else |
| 223 | bits |= def_flag; |
| 224 | break; |
| 225 | } |
| 226 | |
| 227 | return bits; |
| 228 | } |
| 229 | |
| 230 | // Resolve a symbol. This is called the second and subsequent times |
| 231 | // we see a symbol. TO is the pre-existing symbol. ST_SHNDX is the |
| 232 | // section index for SYM, possibly adjusted for many sections. |
| 233 | // IS_ORDINARY is whether ST_SHNDX is a normal section index rather |
| 234 | // than a special code. ORIG_ST_SHNDX is the original section index, |
| 235 | // before any munging because of discarded sections, except that all |
| 236 | // non-ordinary section indexes are mapped to SHN_UNDEF. VERSION is |
| 237 | // the version of SYM. |
| 238 | |
| 239 | template<int size, bool big_endian> |
| 240 | void |
| 241 | Symbol_table::resolve(Sized_symbol<size>* to, |
| 242 | const elfcpp::Sym<size, big_endian>& sym, |
| 243 | unsigned int st_shndx, bool is_ordinary, |
| 244 | unsigned int orig_st_shndx, |
| 245 | Object* object, const char* version) |
| 246 | { |
| 247 | if (object->target()->has_resolve()) |
| 248 | { |
| 249 | Sized_target<size, big_endian>* sized_target; |
| 250 | sized_target = object->sized_target<size, big_endian>(); |
| 251 | sized_target->resolve(to, sym, object, version); |
| 252 | return; |
| 253 | } |
| 254 | |
| 255 | if (!object->is_dynamic()) |
| 256 | { |
| 257 | // Record that we've seen this symbol in a regular object. |
| 258 | to->set_in_reg(); |
| 259 | } |
| 260 | else |
| 261 | { |
| 262 | // Record that we've seen this symbol in a dynamic object. |
| 263 | to->set_in_dyn(); |
| 264 | } |
| 265 | |
| 266 | // Record if we've seen this symbol in a real ELF object (i.e., the |
| 267 | // symbol is referenced from outside the world known to the plugin). |
| 268 | if (object->pluginobj() == NULL) |
| 269 | to->set_in_real_elf(); |
| 270 | |
| 271 | // If we're processing replacement files, allow new symbols to override |
| 272 | // the placeholders from the plugin objects. |
| 273 | if (to->source() == Symbol::FROM_OBJECT) |
| 274 | { |
| 275 | Pluginobj* obj = to->object()->pluginobj(); |
| 276 | if (obj != NULL |
| 277 | && parameters->options().plugins()->in_replacement_phase()) |
| 278 | { |
| 279 | this->override(to, sym, st_shndx, is_ordinary, object, version); |
| 280 | return; |
| 281 | } |
| 282 | } |
| 283 | |
| 284 | unsigned int frombits = symbol_to_bits(sym.get_st_bind(), |
| 285 | object->is_dynamic(), |
| 286 | st_shndx, is_ordinary, |
| 287 | sym.get_st_type()); |
| 288 | |
| 289 | bool adjust_common_sizes; |
| 290 | if (Symbol_table::should_override(to, frombits, object, |
| 291 | &adjust_common_sizes)) |
| 292 | { |
| 293 | typename Sized_symbol<size>::Size_type tosize = to->symsize(); |
| 294 | |
| 295 | this->override(to, sym, st_shndx, is_ordinary, object, version); |
| 296 | |
| 297 | if (adjust_common_sizes && tosize > to->symsize()) |
| 298 | to->set_symsize(tosize); |
| 299 | } |
| 300 | else |
| 301 | { |
| 302 | if (adjust_common_sizes && sym.get_st_size() > to->symsize()) |
| 303 | to->set_symsize(sym.get_st_size()); |
| 304 | // The ELF ABI says that even for a reference to a symbol we |
| 305 | // merge the visibility. |
| 306 | to->override_visibility(sym.get_st_visibility()); |
| 307 | } |
| 308 | |
| 309 | // A new weak undefined reference, merging with an old weak |
| 310 | // reference, could be a One Definition Rule (ODR) violation -- |
| 311 | // especially if the types or sizes of the references differ. We'll |
| 312 | // store such pairs and look them up later to make sure they |
| 313 | // actually refer to the same lines of code. (Note: not all ODR |
| 314 | // violations can be found this way, and not everything this finds |
| 315 | // is an ODR violation. But it's helpful to warn about.) |
| 316 | bool to_is_ordinary; |
| 317 | if (parameters->options().detect_odr_violations() |
| 318 | && sym.get_st_bind() == elfcpp::STB_WEAK |
| 319 | && to->binding() == elfcpp::STB_WEAK |
| 320 | && orig_st_shndx != elfcpp::SHN_UNDEF |
| 321 | && to->shndx(&to_is_ordinary) != elfcpp::SHN_UNDEF |
| 322 | && to_is_ordinary |
| 323 | && sym.get_st_size() != 0 // Ignore weird 0-sized symbols. |
| 324 | && to->symsize() != 0 |
| 325 | && (sym.get_st_type() != to->type() |
| 326 | || sym.get_st_size() != to->symsize()) |
| 327 | // C does not have a concept of ODR, so we only need to do this |
| 328 | // on C++ symbols. These have (mangled) names starting with _Z. |
| 329 | && to->name()[0] == '_' && to->name()[1] == 'Z') |
| 330 | { |
| 331 | Symbol_location fromloc |
| 332 | = { object, orig_st_shndx, sym.get_st_value() }; |
| 333 | Symbol_location toloc = { to->object(), to->shndx(&to_is_ordinary), |
| 334 | to->value() }; |
| 335 | this->candidate_odr_violations_[to->name()].insert(fromloc); |
| 336 | this->candidate_odr_violations_[to->name()].insert(toloc); |
| 337 | } |
| 338 | } |
| 339 | |
| 340 | // Handle the core of symbol resolution. This is called with the |
| 341 | // existing symbol, TO, and a bitflag describing the new symbol. This |
| 342 | // returns true if we should override the existing symbol with the new |
| 343 | // one, and returns false otherwise. It sets *ADJUST_COMMON_SIZES to |
| 344 | // true if we should set the symbol size to the maximum of the TO and |
| 345 | // FROM sizes. It handles error conditions. |
| 346 | |
| 347 | bool |
| 348 | Symbol_table::should_override(const Symbol* to, unsigned int frombits, |
| 349 | Object* object, bool* adjust_common_sizes) |
| 350 | { |
| 351 | *adjust_common_sizes = false; |
| 352 | |
| 353 | unsigned int tobits; |
| 354 | if (to->source() == Symbol::IS_UNDEFINED) |
| 355 | tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_UNDEF, true, |
| 356 | to->type()); |
| 357 | else if (to->source() != Symbol::FROM_OBJECT) |
| 358 | tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_ABS, false, |
| 359 | to->type()); |
| 360 | else |
| 361 | { |
| 362 | bool is_ordinary; |
| 363 | unsigned int shndx = to->shndx(&is_ordinary); |
| 364 | tobits = symbol_to_bits(to->binding(), |
| 365 | to->object()->is_dynamic(), |
| 366 | shndx, |
| 367 | is_ordinary, |
| 368 | to->type()); |
| 369 | } |
| 370 | |
| 371 | // FIXME: Warn if either but not both of TO and SYM are STT_TLS. |
| 372 | |
| 373 | // We use a giant switch table for symbol resolution. This code is |
| 374 | // unwieldy, but: 1) it is efficient; 2) we definitely handle all |
| 375 | // cases; 3) it is easy to change the handling of a particular case. |
| 376 | // The alternative would be a series of conditionals, but it is easy |
| 377 | // to get the ordering wrong. This could also be done as a table, |
| 378 | // but that is no easier to understand than this large switch |
| 379 | // statement. |
| 380 | |
| 381 | // These are the values generated by the bit codes. |
| 382 | enum |
| 383 | { |
| 384 | DEF = global_flag | regular_flag | def_flag, |
| 385 | WEAK_DEF = weak_flag | regular_flag | def_flag, |
| 386 | DYN_DEF = global_flag | dynamic_flag | def_flag, |
| 387 | DYN_WEAK_DEF = weak_flag | dynamic_flag | def_flag, |
| 388 | UNDEF = global_flag | regular_flag | undef_flag, |
| 389 | WEAK_UNDEF = weak_flag | regular_flag | undef_flag, |
| 390 | DYN_UNDEF = global_flag | dynamic_flag | undef_flag, |
| 391 | DYN_WEAK_UNDEF = weak_flag | dynamic_flag | undef_flag, |
| 392 | COMMON = global_flag | regular_flag | common_flag, |
| 393 | WEAK_COMMON = weak_flag | regular_flag | common_flag, |
| 394 | DYN_COMMON = global_flag | dynamic_flag | common_flag, |
| 395 | DYN_WEAK_COMMON = weak_flag | dynamic_flag | common_flag |
| 396 | }; |
| 397 | |
| 398 | switch (tobits * 16 + frombits) |
| 399 | { |
| 400 | case DEF * 16 + DEF: |
| 401 | // Two definitions of the same symbol. |
| 402 | |
| 403 | // If either symbol is defined by an object included using |
| 404 | // --just-symbols, then don't warn. This is for compatibility |
| 405 | // with the GNU linker. FIXME: This is a hack. |
| 406 | if ((to->source() == Symbol::FROM_OBJECT && to->object()->just_symbols()) |
| 407 | || object->just_symbols()) |
| 408 | return false; |
| 409 | |
| 410 | // FIXME: Do a better job of reporting locations. |
| 411 | gold_error(_("%s: multiple definition of %s"), |
| 412 | object != NULL ? object->name().c_str() : _("command line"), |
| 413 | to->demangled_name().c_str()); |
| 414 | gold_error(_("%s: previous definition here"), |
| 415 | (to->source() == Symbol::FROM_OBJECT |
| 416 | ? to->object()->name().c_str() |
| 417 | : _("command line"))); |
| 418 | return false; |
| 419 | |
| 420 | case WEAK_DEF * 16 + DEF: |
| 421 | // We've seen a weak definition, and now we see a strong |
| 422 | // definition. In the original SVR4 linker, this was treated as |
| 423 | // a multiple definition error. In the Solaris linker and the |
| 424 | // GNU linker, a weak definition followed by a regular |
| 425 | // definition causes the weak definition to be overridden. We |
| 426 | // are currently compatible with the GNU linker. In the future |
| 427 | // we should add a target specific option to change this. |
| 428 | // FIXME. |
| 429 | return true; |
| 430 | |
| 431 | case DYN_DEF * 16 + DEF: |
| 432 | case DYN_WEAK_DEF * 16 + DEF: |
| 433 | // We've seen a definition in a dynamic object, and now we see a |
| 434 | // definition in a regular object. The definition in the |
| 435 | // regular object overrides the definition in the dynamic |
| 436 | // object. |
| 437 | return true; |
| 438 | |
| 439 | case UNDEF * 16 + DEF: |
| 440 | case WEAK_UNDEF * 16 + DEF: |
| 441 | case DYN_UNDEF * 16 + DEF: |
| 442 | case DYN_WEAK_UNDEF * 16 + DEF: |
| 443 | // We've seen an undefined reference, and now we see a |
| 444 | // definition. We use the definition. |
| 445 | return true; |
| 446 | |
| 447 | case COMMON * 16 + DEF: |
| 448 | case WEAK_COMMON * 16 + DEF: |
| 449 | case DYN_COMMON * 16 + DEF: |
| 450 | case DYN_WEAK_COMMON * 16 + DEF: |
| 451 | // We've seen a common symbol and now we see a definition. The |
| 452 | // definition overrides. FIXME: We should optionally issue, version a |
| 453 | // warning. |
| 454 | return true; |
| 455 | |
| 456 | case DEF * 16 + WEAK_DEF: |
| 457 | case WEAK_DEF * 16 + WEAK_DEF: |
| 458 | // We've seen a definition and now we see a weak definition. We |
| 459 | // ignore the new weak definition. |
| 460 | return false; |
| 461 | |
| 462 | case DYN_DEF * 16 + WEAK_DEF: |
| 463 | case DYN_WEAK_DEF * 16 + WEAK_DEF: |
| 464 | // We've seen a dynamic definition and now we see a regular weak |
| 465 | // definition. The regular weak definition overrides. |
| 466 | return true; |
| 467 | |
| 468 | case UNDEF * 16 + WEAK_DEF: |
| 469 | case WEAK_UNDEF * 16 + WEAK_DEF: |
| 470 | case DYN_UNDEF * 16 + WEAK_DEF: |
| 471 | case DYN_WEAK_UNDEF * 16 + WEAK_DEF: |
| 472 | // A weak definition of a currently undefined symbol. |
| 473 | return true; |
| 474 | |
| 475 | case COMMON * 16 + WEAK_DEF: |
| 476 | case WEAK_COMMON * 16 + WEAK_DEF: |
| 477 | // A weak definition does not override a common definition. |
| 478 | return false; |
| 479 | |
| 480 | case DYN_COMMON * 16 + WEAK_DEF: |
| 481 | case DYN_WEAK_COMMON * 16 + WEAK_DEF: |
| 482 | // A weak definition does override a definition in a dynamic |
| 483 | // object. FIXME: We should optionally issue a warning. |
| 484 | return true; |
| 485 | |
| 486 | case DEF * 16 + DYN_DEF: |
| 487 | case WEAK_DEF * 16 + DYN_DEF: |
| 488 | case DYN_DEF * 16 + DYN_DEF: |
| 489 | case DYN_WEAK_DEF * 16 + DYN_DEF: |
| 490 | // Ignore a dynamic definition if we already have a definition. |
| 491 | return false; |
| 492 | |
| 493 | case UNDEF * 16 + DYN_DEF: |
| 494 | case WEAK_UNDEF * 16 + DYN_DEF: |
| 495 | case DYN_UNDEF * 16 + DYN_DEF: |
| 496 | case DYN_WEAK_UNDEF * 16 + DYN_DEF: |
| 497 | // Use a dynamic definition if we have a reference. |
| 498 | return true; |
| 499 | |
| 500 | case COMMON * 16 + DYN_DEF: |
| 501 | case WEAK_COMMON * 16 + DYN_DEF: |
| 502 | case DYN_COMMON * 16 + DYN_DEF: |
| 503 | case DYN_WEAK_COMMON * 16 + DYN_DEF: |
| 504 | // Ignore a dynamic definition if we already have a common |
| 505 | // definition. |
| 506 | return false; |
| 507 | |
| 508 | case DEF * 16 + DYN_WEAK_DEF: |
| 509 | case WEAK_DEF * 16 + DYN_WEAK_DEF: |
| 510 | case DYN_DEF * 16 + DYN_WEAK_DEF: |
| 511 | case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF: |
| 512 | // Ignore a weak dynamic definition if we already have a |
| 513 | // definition. |
| 514 | return false; |
| 515 | |
| 516 | case UNDEF * 16 + DYN_WEAK_DEF: |
| 517 | case WEAK_UNDEF * 16 + DYN_WEAK_DEF: |
| 518 | case DYN_UNDEF * 16 + DYN_WEAK_DEF: |
| 519 | case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF: |
| 520 | // Use a weak dynamic definition if we have a reference. |
| 521 | return true; |
| 522 | |
| 523 | case COMMON * 16 + DYN_WEAK_DEF: |
| 524 | case WEAK_COMMON * 16 + DYN_WEAK_DEF: |
| 525 | case DYN_COMMON * 16 + DYN_WEAK_DEF: |
| 526 | case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF: |
| 527 | // Ignore a weak dynamic definition if we already have a common |
| 528 | // definition. |
| 529 | return false; |
| 530 | |
| 531 | case DEF * 16 + UNDEF: |
| 532 | case WEAK_DEF * 16 + UNDEF: |
| 533 | case DYN_DEF * 16 + UNDEF: |
| 534 | case DYN_WEAK_DEF * 16 + UNDEF: |
| 535 | case UNDEF * 16 + UNDEF: |
| 536 | // A new undefined reference tells us nothing. |
| 537 | return false; |
| 538 | |
| 539 | case WEAK_UNDEF * 16 + UNDEF: |
| 540 | case DYN_UNDEF * 16 + UNDEF: |
| 541 | case DYN_WEAK_UNDEF * 16 + UNDEF: |
| 542 | // A strong undef overrides a dynamic or weak undef. |
| 543 | return true; |
| 544 | |
| 545 | case COMMON * 16 + UNDEF: |
| 546 | case WEAK_COMMON * 16 + UNDEF: |
| 547 | case DYN_COMMON * 16 + UNDEF: |
| 548 | case DYN_WEAK_COMMON * 16 + UNDEF: |
| 549 | // A new undefined reference tells us nothing. |
| 550 | return false; |
| 551 | |
| 552 | case DEF * 16 + WEAK_UNDEF: |
| 553 | case WEAK_DEF * 16 + WEAK_UNDEF: |
| 554 | case DYN_DEF * 16 + WEAK_UNDEF: |
| 555 | case DYN_WEAK_DEF * 16 + WEAK_UNDEF: |
| 556 | case UNDEF * 16 + WEAK_UNDEF: |
| 557 | case WEAK_UNDEF * 16 + WEAK_UNDEF: |
| 558 | case DYN_UNDEF * 16 + WEAK_UNDEF: |
| 559 | case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF: |
| 560 | case COMMON * 16 + WEAK_UNDEF: |
| 561 | case WEAK_COMMON * 16 + WEAK_UNDEF: |
| 562 | case DYN_COMMON * 16 + WEAK_UNDEF: |
| 563 | case DYN_WEAK_COMMON * 16 + WEAK_UNDEF: |
| 564 | // A new weak undefined reference tells us nothing. |
| 565 | return false; |
| 566 | |
| 567 | case DEF * 16 + DYN_UNDEF: |
| 568 | case WEAK_DEF * 16 + DYN_UNDEF: |
| 569 | case DYN_DEF * 16 + DYN_UNDEF: |
| 570 | case DYN_WEAK_DEF * 16 + DYN_UNDEF: |
| 571 | case UNDEF * 16 + DYN_UNDEF: |
| 572 | case WEAK_UNDEF * 16 + DYN_UNDEF: |
| 573 | case DYN_UNDEF * 16 + DYN_UNDEF: |
| 574 | case DYN_WEAK_UNDEF * 16 + DYN_UNDEF: |
| 575 | case COMMON * 16 + DYN_UNDEF: |
| 576 | case WEAK_COMMON * 16 + DYN_UNDEF: |
| 577 | case DYN_COMMON * 16 + DYN_UNDEF: |
| 578 | case DYN_WEAK_COMMON * 16 + DYN_UNDEF: |
| 579 | // A new dynamic undefined reference tells us nothing. |
| 580 | return false; |
| 581 | |
| 582 | case DEF * 16 + DYN_WEAK_UNDEF: |
| 583 | case WEAK_DEF * 16 + DYN_WEAK_UNDEF: |
| 584 | case DYN_DEF * 16 + DYN_WEAK_UNDEF: |
| 585 | case DYN_WEAK_DEF * 16 + DYN_WEAK_UNDEF: |
| 586 | case UNDEF * 16 + DYN_WEAK_UNDEF: |
| 587 | case WEAK_UNDEF * 16 + DYN_WEAK_UNDEF: |
| 588 | case DYN_UNDEF * 16 + DYN_WEAK_UNDEF: |
| 589 | case DYN_WEAK_UNDEF * 16 + DYN_WEAK_UNDEF: |
| 590 | case COMMON * 16 + DYN_WEAK_UNDEF: |
| 591 | case WEAK_COMMON * 16 + DYN_WEAK_UNDEF: |
| 592 | case DYN_COMMON * 16 + DYN_WEAK_UNDEF: |
| 593 | case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF: |
| 594 | // A new weak dynamic undefined reference tells us nothing. |
| 595 | return false; |
| 596 | |
| 597 | case DEF * 16 + COMMON: |
| 598 | // A common symbol does not override a definition. |
| 599 | return false; |
| 600 | |
| 601 | case WEAK_DEF * 16 + COMMON: |
| 602 | case DYN_DEF * 16 + COMMON: |
| 603 | case DYN_WEAK_DEF * 16 + COMMON: |
| 604 | // A common symbol does override a weak definition or a dynamic |
| 605 | // definition. |
| 606 | return true; |
| 607 | |
| 608 | case UNDEF * 16 + COMMON: |
| 609 | case WEAK_UNDEF * 16 + COMMON: |
| 610 | case DYN_UNDEF * 16 + COMMON: |
| 611 | case DYN_WEAK_UNDEF * 16 + COMMON: |
| 612 | // A common symbol is a definition for a reference. |
| 613 | return true; |
| 614 | |
| 615 | case COMMON * 16 + COMMON: |
| 616 | // Set the size to the maximum. |
| 617 | *adjust_common_sizes = true; |
| 618 | return false; |
| 619 | |
| 620 | case WEAK_COMMON * 16 + COMMON: |
| 621 | // I'm not sure just what a weak common symbol means, but |
| 622 | // presumably it can be overridden by a regular common symbol. |
| 623 | return true; |
| 624 | |
| 625 | case DYN_COMMON * 16 + COMMON: |
| 626 | case DYN_WEAK_COMMON * 16 + COMMON: |
| 627 | // Use the real common symbol, but adjust the size if necessary. |
| 628 | *adjust_common_sizes = true; |
| 629 | return true; |
| 630 | |
| 631 | case DEF * 16 + WEAK_COMMON: |
| 632 | case WEAK_DEF * 16 + WEAK_COMMON: |
| 633 | case DYN_DEF * 16 + WEAK_COMMON: |
| 634 | case DYN_WEAK_DEF * 16 + WEAK_COMMON: |
| 635 | // Whatever a weak common symbol is, it won't override a |
| 636 | // definition. |
| 637 | return false; |
| 638 | |
| 639 | case UNDEF * 16 + WEAK_COMMON: |
| 640 | case WEAK_UNDEF * 16 + WEAK_COMMON: |
| 641 | case DYN_UNDEF * 16 + WEAK_COMMON: |
| 642 | case DYN_WEAK_UNDEF * 16 + WEAK_COMMON: |
| 643 | // A weak common symbol is better than an undefined symbol. |
| 644 | return true; |
| 645 | |
| 646 | case COMMON * 16 + WEAK_COMMON: |
| 647 | case WEAK_COMMON * 16 + WEAK_COMMON: |
| 648 | case DYN_COMMON * 16 + WEAK_COMMON: |
| 649 | case DYN_WEAK_COMMON * 16 + WEAK_COMMON: |
| 650 | // Ignore a weak common symbol in the presence of a real common |
| 651 | // symbol. |
| 652 | return false; |
| 653 | |
| 654 | case DEF * 16 + DYN_COMMON: |
| 655 | case WEAK_DEF * 16 + DYN_COMMON: |
| 656 | case DYN_DEF * 16 + DYN_COMMON: |
| 657 | case DYN_WEAK_DEF * 16 + DYN_COMMON: |
| 658 | // Ignore a dynamic common symbol in the presence of a |
| 659 | // definition. |
| 660 | return false; |
| 661 | |
| 662 | case UNDEF * 16 + DYN_COMMON: |
| 663 | case WEAK_UNDEF * 16 + DYN_COMMON: |
| 664 | case DYN_UNDEF * 16 + DYN_COMMON: |
| 665 | case DYN_WEAK_UNDEF * 16 + DYN_COMMON: |
| 666 | // A dynamic common symbol is a definition of sorts. |
| 667 | return true; |
| 668 | |
| 669 | case COMMON * 16 + DYN_COMMON: |
| 670 | case WEAK_COMMON * 16 + DYN_COMMON: |
| 671 | case DYN_COMMON * 16 + DYN_COMMON: |
| 672 | case DYN_WEAK_COMMON * 16 + DYN_COMMON: |
| 673 | // Set the size to the maximum. |
| 674 | *adjust_common_sizes = true; |
| 675 | return false; |
| 676 | |
| 677 | case DEF * 16 + DYN_WEAK_COMMON: |
| 678 | case WEAK_DEF * 16 + DYN_WEAK_COMMON: |
| 679 | case DYN_DEF * 16 + DYN_WEAK_COMMON: |
| 680 | case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON: |
| 681 | // A common symbol is ignored in the face of a definition. |
| 682 | return false; |
| 683 | |
| 684 | case UNDEF * 16 + DYN_WEAK_COMMON: |
| 685 | case WEAK_UNDEF * 16 + DYN_WEAK_COMMON: |
| 686 | case DYN_UNDEF * 16 + DYN_WEAK_COMMON: |
| 687 | case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON: |
| 688 | // I guess a weak common symbol is better than a definition. |
| 689 | return true; |
| 690 | |
| 691 | case COMMON * 16 + DYN_WEAK_COMMON: |
| 692 | case WEAK_COMMON * 16 + DYN_WEAK_COMMON: |
| 693 | case DYN_COMMON * 16 + DYN_WEAK_COMMON: |
| 694 | case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON: |
| 695 | // Set the size to the maximum. |
| 696 | *adjust_common_sizes = true; |
| 697 | return false; |
| 698 | |
| 699 | default: |
| 700 | gold_unreachable(); |
| 701 | } |
| 702 | } |
| 703 | |
| 704 | // A special case of should_override which is only called for a strong |
| 705 | // defined symbol from a regular object file. This is used when |
| 706 | // defining special symbols. |
| 707 | |
| 708 | bool |
| 709 | Symbol_table::should_override_with_special(const Symbol* to) |
| 710 | { |
| 711 | bool adjust_common_sizes; |
| 712 | unsigned int frombits = global_flag | regular_flag | def_flag; |
| 713 | bool ret = Symbol_table::should_override(to, frombits, NULL, |
| 714 | &adjust_common_sizes); |
| 715 | gold_assert(!adjust_common_sizes); |
| 716 | return ret; |
| 717 | } |
| 718 | |
| 719 | // Override symbol base with a special symbol. |
| 720 | |
| 721 | void |
| 722 | Symbol::override_base_with_special(const Symbol* from) |
| 723 | { |
| 724 | gold_assert(this->name_ == from->name_ || this->has_alias()); |
| 725 | |
| 726 | this->source_ = from->source_; |
| 727 | switch (from->source_) |
| 728 | { |
| 729 | case FROM_OBJECT: |
| 730 | this->u_.from_object = from->u_.from_object; |
| 731 | break; |
| 732 | case IN_OUTPUT_DATA: |
| 733 | this->u_.in_output_data = from->u_.in_output_data; |
| 734 | break; |
| 735 | case IN_OUTPUT_SEGMENT: |
| 736 | this->u_.in_output_segment = from->u_.in_output_segment; |
| 737 | break; |
| 738 | case IS_CONSTANT: |
| 739 | case IS_UNDEFINED: |
| 740 | break; |
| 741 | default: |
| 742 | gold_unreachable(); |
| 743 | break; |
| 744 | } |
| 745 | |
| 746 | this->override_version(from->version_); |
| 747 | this->type_ = from->type_; |
| 748 | this->binding_ = from->binding_; |
| 749 | this->override_visibility(from->visibility_); |
| 750 | this->nonvis_ = from->nonvis_; |
| 751 | |
| 752 | // Special symbols are always considered to be regular symbols. |
| 753 | this->in_reg_ = true; |
| 754 | |
| 755 | if (from->needs_dynsym_entry_) |
| 756 | this->needs_dynsym_entry_ = true; |
| 757 | if (from->needs_dynsym_value_) |
| 758 | this->needs_dynsym_value_ = true; |
| 759 | |
| 760 | // We shouldn't see these flags. If we do, we need to handle them |
| 761 | // somehow. |
| 762 | gold_assert(!from->is_target_special_ || this->is_target_special_); |
| 763 | gold_assert(!from->is_forwarder_); |
| 764 | gold_assert(!from->has_plt_offset_); |
| 765 | gold_assert(!from->has_warning_); |
| 766 | gold_assert(!from->is_copied_from_dynobj_); |
| 767 | gold_assert(!from->is_forced_local_); |
| 768 | } |
| 769 | |
| 770 | // Override a symbol with a special symbol. |
| 771 | |
| 772 | template<int size> |
| 773 | void |
| 774 | Sized_symbol<size>::override_with_special(const Sized_symbol<size>* from) |
| 775 | { |
| 776 | this->override_base_with_special(from); |
| 777 | this->value_ = from->value_; |
| 778 | this->symsize_ = from->symsize_; |
| 779 | } |
| 780 | |
| 781 | // Override TOSYM with the special symbol FROMSYM. This handles all |
| 782 | // aliases of TOSYM. |
| 783 | |
| 784 | template<int size> |
| 785 | void |
| 786 | Symbol_table::override_with_special(Sized_symbol<size>* tosym, |
| 787 | const Sized_symbol<size>* fromsym) |
| 788 | { |
| 789 | tosym->override_with_special(fromsym); |
| 790 | if (tosym->has_alias()) |
| 791 | { |
| 792 | Symbol* sym = this->weak_aliases_[tosym]; |
| 793 | gold_assert(sym != NULL); |
| 794 | Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym); |
| 795 | do |
| 796 | { |
| 797 | ssym->override_with_special(fromsym); |
| 798 | sym = this->weak_aliases_[ssym]; |
| 799 | gold_assert(sym != NULL); |
| 800 | ssym = this->get_sized_symbol<size>(sym); |
| 801 | } |
| 802 | while (ssym != tosym); |
| 803 | } |
| 804 | if (tosym->binding() == elfcpp::STB_LOCAL |
| 805 | || ((tosym->visibility() == elfcpp::STV_HIDDEN |
| 806 | || tosym->visibility() == elfcpp::STV_INTERNAL) |
| 807 | && (tosym->binding() == elfcpp::STB_GLOBAL |
| 808 | || tosym->binding() == elfcpp::STB_WEAK) |
| 809 | && !parameters->options().relocatable())) |
| 810 | this->force_local(tosym); |
| 811 | } |
| 812 | |
| 813 | // Instantiate the templates we need. We could use the configure |
| 814 | // script to restrict this to only the ones needed for implemented |
| 815 | // targets. |
| 816 | |
| 817 | #ifdef HAVE_TARGET_32_LITTLE |
| 818 | template |
| 819 | void |
| 820 | Symbol_table::resolve<32, false>( |
| 821 | Sized_symbol<32>* to, |
| 822 | const elfcpp::Sym<32, false>& sym, |
| 823 | unsigned int st_shndx, |
| 824 | bool is_ordinary, |
| 825 | unsigned int orig_st_shndx, |
| 826 | Object* object, |
| 827 | const char* version); |
| 828 | #endif |
| 829 | |
| 830 | #ifdef HAVE_TARGET_32_BIG |
| 831 | template |
| 832 | void |
| 833 | Symbol_table::resolve<32, true>( |
| 834 | Sized_symbol<32>* to, |
| 835 | const elfcpp::Sym<32, true>& sym, |
| 836 | unsigned int st_shndx, |
| 837 | bool is_ordinary, |
| 838 | unsigned int orig_st_shndx, |
| 839 | Object* object, |
| 840 | const char* version); |
| 841 | #endif |
| 842 | |
| 843 | #ifdef HAVE_TARGET_64_LITTLE |
| 844 | template |
| 845 | void |
| 846 | Symbol_table::resolve<64, false>( |
| 847 | Sized_symbol<64>* to, |
| 848 | const elfcpp::Sym<64, false>& sym, |
| 849 | unsigned int st_shndx, |
| 850 | bool is_ordinary, |
| 851 | unsigned int orig_st_shndx, |
| 852 | Object* object, |
| 853 | const char* version); |
| 854 | #endif |
| 855 | |
| 856 | #ifdef HAVE_TARGET_64_BIG |
| 857 | template |
| 858 | void |
| 859 | Symbol_table::resolve<64, true>( |
| 860 | Sized_symbol<64>* to, |
| 861 | const elfcpp::Sym<64, true>& sym, |
| 862 | unsigned int st_shndx, |
| 863 | bool is_ordinary, |
| 864 | unsigned int orig_st_shndx, |
| 865 | Object* object, |
| 866 | const char* version); |
| 867 | #endif |
| 868 | |
| 869 | #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG) |
| 870 | template |
| 871 | void |
| 872 | Symbol_table::override_with_special<32>(Sized_symbol<32>*, |
| 873 | const Sized_symbol<32>*); |
| 874 | #endif |
| 875 | |
| 876 | #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG) |
| 877 | template |
| 878 | void |
| 879 | Symbol_table::override_with_special<64>(Sized_symbol<64>*, |
| 880 | const Sized_symbol<64>*); |
| 881 | #endif |
| 882 | |
| 883 | } // End namespace gold. |