1 // resolve.cc -- symbol resolution for gold
3 // Copyright (C) 2006-2015 Free Software Foundation, Inc.
4 // Written by Ian Lance Taylor <iant@google.com>.
6 // This file is part of gold.
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.
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.
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.
34 // Symbol methods used in this file.
36 // This symbol is being overridden by another symbol whose version is
37 // VERSION. Update the VERSION_ field accordingly.
40 Symbol::override_version(const char* version)
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;
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;
66 // This symbol is being overidden by another symbol whose visibility
67 // is VISIBILITY. Updated the VISIBILITY_ field accordingly.
70 Symbol::override_visibility(elfcpp::STV visibility)
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)
79 if (this->visibility_ == elfcpp::STV_DEFAULT)
80 this->visibility_ = visibility;
81 else if (this->visibility_ > visibility)
82 this->visibility_ = visibility;
86 // Override the fields in Symbol.
88 template<int size, bool big_endian>
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)
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 // Don't override st_type from plugin placeholder symbols.
100 if (object->pluginobj() == NULL)
102 // Turn IFUNC symbols from shared libraries into normal FUNC symbols.
103 elfcpp::STT type = sym.get_st_type();
104 if (object->is_dynamic() && type == elfcpp::STT_GNU_IFUNC)
105 type = elfcpp::STT_FUNC;
108 this->binding_ = sym.get_st_bind();
109 this->override_visibility(sym.get_st_visibility());
110 this->nonvis_ = sym.get_st_nonvis();
111 if (object->is_dynamic())
112 this->in_dyn_ = true;
114 this->in_reg_ = true;
117 // Override the fields in Sized_symbol.
120 template<bool big_endian>
122 Sized_symbol<size>::override(const elfcpp::Sym<size, big_endian>& sym,
123 unsigned st_shndx, bool is_ordinary,
124 Object* object, const char* version)
126 this->override_base(sym, st_shndx, is_ordinary, object, version);
127 this->value_ = sym.get_st_value();
128 this->symsize_ = sym.get_st_size();
131 // Override TOSYM with symbol FROMSYM, defined in OBJECT, with version
132 // VERSION. This handles all aliases of TOSYM.
134 template<int size, bool big_endian>
136 Symbol_table::override(Sized_symbol<size>* tosym,
137 const elfcpp::Sym<size, big_endian>& fromsym,
138 unsigned int st_shndx, bool is_ordinary,
139 Object* object, const char* version)
141 tosym->override(fromsym, st_shndx, is_ordinary, object, version);
142 if (tosym->has_alias())
144 Symbol* sym = this->weak_aliases_[tosym];
145 gold_assert(sym != NULL);
146 Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
149 ssym->override(fromsym, st_shndx, is_ordinary, object, version);
150 sym = this->weak_aliases_[ssym];
151 gold_assert(sym != NULL);
152 ssym = this->get_sized_symbol<size>(sym);
154 while (ssym != tosym);
158 // The resolve functions build a little code for each symbol.
159 // Bit 0: 0 for global, 1 for weak.
160 // Bit 1: 0 for regular object, 1 for shared object
161 // Bits 2-3: 0 for normal, 1 for undefined, 2 for common
162 // This gives us values from 0 to 11.
164 static const int global_or_weak_shift = 0;
165 static const unsigned int global_flag = 0 << global_or_weak_shift;
166 static const unsigned int weak_flag = 1 << global_or_weak_shift;
168 static const int regular_or_dynamic_shift = 1;
169 static const unsigned int regular_flag = 0 << regular_or_dynamic_shift;
170 static const unsigned int dynamic_flag = 1 << regular_or_dynamic_shift;
172 static const int def_undef_or_common_shift = 2;
173 static const unsigned int def_flag = 0 << def_undef_or_common_shift;
174 static const unsigned int undef_flag = 1 << def_undef_or_common_shift;
175 static const unsigned int common_flag = 2 << def_undef_or_common_shift;
177 // This convenience function combines all the flags based on facts
181 symbol_to_bits(elfcpp::STB binding, bool is_dynamic,
182 unsigned int shndx, bool is_ordinary)
188 case elfcpp::STB_GLOBAL:
189 case elfcpp::STB_GNU_UNIQUE:
193 case elfcpp::STB_WEAK:
197 case elfcpp::STB_LOCAL:
198 // We should only see externally visible symbols in the symbol
200 gold_error(_("invalid STB_LOCAL symbol in external symbols"));
204 // Any target which wants to handle STB_LOOS, etc., needs to
205 // define a resolve method.
206 gold_error(_("unsupported symbol binding %d"), static_cast<int>(binding));
211 bits |= dynamic_flag;
213 bits |= regular_flag;
217 case elfcpp::SHN_UNDEF:
221 case elfcpp::SHN_COMMON:
227 if (!is_ordinary && Symbol::is_common_shndx(shndx))
237 // Resolve a symbol. This is called the second and subsequent times
238 // we see a symbol. TO is the pre-existing symbol. ST_SHNDX is the
239 // section index for SYM, possibly adjusted for many sections.
240 // IS_ORDINARY is whether ST_SHNDX is a normal section index rather
241 // than a special code. ORIG_ST_SHNDX is the original section index,
242 // before any munging because of discarded sections, except that all
243 // non-ordinary section indexes are mapped to SHN_UNDEF. VERSION is
244 // the version of SYM.
246 template<int size, bool big_endian>
248 Symbol_table::resolve(Sized_symbol<size>* to,
249 const elfcpp::Sym<size, big_endian>& sym,
250 unsigned int st_shndx, bool is_ordinary,
251 unsigned int orig_st_shndx,
252 Object* object, const char* version,
253 bool is_default_version)
255 // It's possible for a symbol to be defined in an object file
256 // using .symver to give it a version, and for there to also be
257 // a linker script giving that symbol the same version. We
258 // don't want to give a multiple-definition error for this
259 // harmless redefinition.
261 if (to->source() == Symbol::FROM_OBJECT
262 && to->object() == object
265 && to->shndx(&to_is_ordinary) == st_shndx
267 && to->value() == sym.get_st_value())
270 if (parameters->target().has_resolve())
272 Sized_target<size, big_endian>* sized_target;
273 sized_target = parameters->sized_target<size, big_endian>();
274 sized_target->resolve(to, sym, object, version);
278 if (!object->is_dynamic())
280 if (sym.get_st_type() == elfcpp::STT_COMMON
281 && (is_ordinary || !Symbol::is_common_shndx(st_shndx)))
283 gold_warning(_("STT_COMMON symbol '%s' in %s "
284 "is not in a common section"),
285 to->demangled_name().c_str(),
286 to->object()->name().c_str());
289 // Record that we've seen this symbol in a regular object.
292 else if (st_shndx == elfcpp::SHN_UNDEF
293 && (to->visibility() == elfcpp::STV_HIDDEN
294 || to->visibility() == elfcpp::STV_INTERNAL))
296 // The symbol is hidden, so a reference from a shared object
297 // cannot bind to it. We tried issuing a warning in this case,
298 // but that produces false positives when the symbol is
299 // actually resolved in a different shared object (PR 15574).
304 // Record that we've seen this symbol in a dynamic object.
308 // Record if we've seen this symbol in a real ELF object (i.e., the
309 // symbol is referenced from outside the world known to the plugin).
310 if (object->pluginobj() == NULL && !object->is_dynamic())
311 to->set_in_real_elf();
313 // If we're processing replacement files, allow new symbols to override
314 // the placeholders from the plugin objects.
315 // Treat common symbols specially since it is possible that an ELF
316 // file increased the size of the alignment.
317 if (to->source() == Symbol::FROM_OBJECT)
319 Pluginobj* obj = to->object()->pluginobj();
321 && parameters->options().plugins()->in_replacement_phase())
323 bool adjust_common = false;
324 typename Sized_symbol<size>::Size_type tosize = 0;
325 typename Sized_symbol<size>::Value_type tovalue = 0;
327 && !is_ordinary && Symbol::is_common_shndx(st_shndx))
329 adjust_common = true;
330 tosize = to->symsize();
331 tovalue = to->value();
333 this->override(to, sym, st_shndx, is_ordinary, object, version);
336 if (tosize > to->symsize())
337 to->set_symsize(tosize);
338 if (tovalue > to->value())
339 to->set_value(tovalue);
345 // A new weak undefined reference, merging with an old weak
346 // reference, could be a One Definition Rule (ODR) violation --
347 // especially if the types or sizes of the references differ. We'll
348 // store such pairs and look them up later to make sure they
349 // actually refer to the same lines of code. We also check
350 // combinations of weak and strong, which might occur if one case is
351 // inline and the other is not. (Note: not all ODR violations can
352 // be found this way, and not everything this finds is an ODR
353 // violation. But it's helpful to warn about.)
354 if (parameters->options().detect_odr_violations()
355 && (sym.get_st_bind() == elfcpp::STB_WEAK
356 || to->binding() == elfcpp::STB_WEAK)
357 && orig_st_shndx != elfcpp::SHN_UNDEF
358 && to->shndx(&to_is_ordinary) != elfcpp::SHN_UNDEF
360 && sym.get_st_size() != 0 // Ignore weird 0-sized symbols.
361 && to->symsize() != 0
362 && (sym.get_st_type() != to->type()
363 || sym.get_st_size() != to->symsize())
364 // C does not have a concept of ODR, so we only need to do this
365 // on C++ symbols. These have (mangled) names starting with _Z.
366 && to->name()[0] == '_' && to->name()[1] == 'Z')
368 Symbol_location fromloc
369 = { object, orig_st_shndx, static_cast<off_t>(sym.get_st_value()) };
370 Symbol_location toloc = { to->object(), to->shndx(&to_is_ordinary),
371 static_cast<off_t>(to->value()) };
372 this->candidate_odr_violations_[to->name()].insert(fromloc);
373 this->candidate_odr_violations_[to->name()].insert(toloc);
376 // Plugins don't provide a symbol type, so adopt the existing type
377 // if the FROM symbol is from a plugin.
378 elfcpp::STT fromtype = (object->pluginobj() != NULL
380 : sym.get_st_type());
381 unsigned int frombits = symbol_to_bits(sym.get_st_bind(),
382 object->is_dynamic(),
383 st_shndx, is_ordinary);
385 bool adjust_common_sizes;
387 typename Sized_symbol<size>::Size_type tosize = to->symsize();
388 if (Symbol_table::should_override(to, frombits, fromtype, OBJECT,
389 object, &adjust_common_sizes,
390 &adjust_dyndef, is_default_version))
392 elfcpp::STB tobinding = to->binding();
393 typename Sized_symbol<size>::Value_type tovalue = to->value();
394 this->override(to, sym, st_shndx, is_ordinary, object, version);
395 if (adjust_common_sizes)
397 if (tosize > to->symsize())
398 to->set_symsize(tosize);
399 if (tovalue > to->value())
400 to->set_value(tovalue);
404 // We are overriding an UNDEF or WEAK UNDEF with a DYN DEF.
405 // Remember which kind of UNDEF it was for future reference.
406 to->set_undef_binding(tobinding);
411 if (adjust_common_sizes)
413 if (sym.get_st_size() > tosize)
414 to->set_symsize(sym.get_st_size());
415 if (sym.get_st_value() > to->value())
416 to->set_value(sym.get_st_value());
420 // We are keeping a DYN DEF after seeing an UNDEF or WEAK UNDEF.
421 // Remember which kind of UNDEF it was.
422 to->set_undef_binding(sym.get_st_bind());
424 // The ELF ABI says that even for a reference to a symbol we
425 // merge the visibility.
426 to->override_visibility(sym.get_st_visibility());
429 if (adjust_common_sizes && parameters->options().warn_common())
431 if (tosize > sym.get_st_size())
432 Symbol_table::report_resolve_problem(false,
433 _("common of '%s' overriding "
436 else if (tosize < sym.get_st_size())
437 Symbol_table::report_resolve_problem(false,
438 _("common of '%s' overidden by "
442 Symbol_table::report_resolve_problem(false,
443 _("multiple common of '%s'"),
448 // Handle the core of symbol resolution. This is called with the
449 // existing symbol, TO, and a bitflag describing the new symbol. This
450 // returns true if we should override the existing symbol with the new
451 // one, and returns false otherwise. It sets *ADJUST_COMMON_SIZES to
452 // true if we should set the symbol size to the maximum of the TO and
453 // FROM sizes. It handles error conditions.
456 Symbol_table::should_override(const Symbol* to, unsigned int frombits,
457 elfcpp::STT fromtype, Defined defined,
458 Object* object, bool* adjust_common_sizes,
459 bool* adjust_dyndef, bool is_default_version)
461 *adjust_common_sizes = false;
462 *adjust_dyndef = false;
465 if (to->source() == Symbol::IS_UNDEFINED)
466 tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_UNDEF, true);
467 else if (to->source() != Symbol::FROM_OBJECT)
468 tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_ABS, false);
472 unsigned int shndx = to->shndx(&is_ordinary);
473 tobits = symbol_to_bits(to->binding(),
474 to->object()->is_dynamic(),
479 if ((to->type() == elfcpp::STT_TLS) ^ (fromtype == elfcpp::STT_TLS)
480 && !to->is_placeholder())
481 Symbol_table::report_resolve_problem(true,
482 _("symbol '%s' used as both __thread "
484 to, defined, object);
486 // We use a giant switch table for symbol resolution. This code is
487 // unwieldy, but: 1) it is efficient; 2) we definitely handle all
488 // cases; 3) it is easy to change the handling of a particular case.
489 // The alternative would be a series of conditionals, but it is easy
490 // to get the ordering wrong. This could also be done as a table,
491 // but that is no easier to understand than this large switch
494 // These are the values generated by the bit codes.
497 DEF = global_flag | regular_flag | def_flag,
498 WEAK_DEF = weak_flag | regular_flag | def_flag,
499 DYN_DEF = global_flag | dynamic_flag | def_flag,
500 DYN_WEAK_DEF = weak_flag | dynamic_flag | def_flag,
501 UNDEF = global_flag | regular_flag | undef_flag,
502 WEAK_UNDEF = weak_flag | regular_flag | undef_flag,
503 DYN_UNDEF = global_flag | dynamic_flag | undef_flag,
504 DYN_WEAK_UNDEF = weak_flag | dynamic_flag | undef_flag,
505 COMMON = global_flag | regular_flag | common_flag,
506 WEAK_COMMON = weak_flag | regular_flag | common_flag,
507 DYN_COMMON = global_flag | dynamic_flag | common_flag,
508 DYN_WEAK_COMMON = weak_flag | dynamic_flag | common_flag
511 switch (tobits * 16 + frombits)
514 // Two definitions of the same symbol.
516 // If either symbol is defined by an object included using
517 // --just-symbols, then don't warn. This is for compatibility
518 // with the GNU linker. FIXME: This is a hack.
519 if ((to->source() == Symbol::FROM_OBJECT && to->object()->just_symbols())
520 || (object != NULL && object->just_symbols()))
523 if (!parameters->options().muldefs())
524 Symbol_table::report_resolve_problem(true,
525 _("multiple definition of '%s'"),
526 to, defined, object);
529 case WEAK_DEF * 16 + DEF:
530 // We've seen a weak definition, and now we see a strong
531 // definition. In the original SVR4 linker, this was treated as
532 // a multiple definition error. In the Solaris linker and the
533 // GNU linker, a weak definition followed by a regular
534 // definition causes the weak definition to be overridden. We
535 // are currently compatible with the GNU linker. In the future
536 // we should add a target specific option to change this.
540 case DYN_DEF * 16 + DEF:
541 case DYN_WEAK_DEF * 16 + DEF:
542 // We've seen a definition in a dynamic object, and now we see a
543 // definition in a regular object. The definition in the
544 // regular object overrides the definition in the dynamic
548 case UNDEF * 16 + DEF:
549 case WEAK_UNDEF * 16 + DEF:
550 case DYN_UNDEF * 16 + DEF:
551 case DYN_WEAK_UNDEF * 16 + DEF:
552 // We've seen an undefined reference, and now we see a
553 // definition. We use the definition.
556 case COMMON * 16 + DEF:
557 case WEAK_COMMON * 16 + DEF:
558 case DYN_COMMON * 16 + DEF:
559 case DYN_WEAK_COMMON * 16 + DEF:
560 // We've seen a common symbol and now we see a definition. The
561 // definition overrides.
562 if (parameters->options().warn_common())
563 Symbol_table::report_resolve_problem(false,
564 _("definition of '%s' overriding "
566 to, defined, object);
569 case DEF * 16 + WEAK_DEF:
570 case WEAK_DEF * 16 + WEAK_DEF:
571 // We've seen a definition and now we see a weak definition. We
572 // ignore the new weak definition.
575 case DYN_DEF * 16 + WEAK_DEF:
576 case DYN_WEAK_DEF * 16 + WEAK_DEF:
577 // We've seen a dynamic definition and now we see a regular weak
578 // definition. The regular weak definition overrides.
581 case UNDEF * 16 + WEAK_DEF:
582 case WEAK_UNDEF * 16 + WEAK_DEF:
583 case DYN_UNDEF * 16 + WEAK_DEF:
584 case DYN_WEAK_UNDEF * 16 + WEAK_DEF:
585 // A weak definition of a currently undefined symbol.
588 case COMMON * 16 + WEAK_DEF:
589 case WEAK_COMMON * 16 + WEAK_DEF:
590 // A weak definition does not override a common definition.
593 case DYN_COMMON * 16 + WEAK_DEF:
594 case DYN_WEAK_COMMON * 16 + WEAK_DEF:
595 // A weak definition does override a definition in a dynamic
597 if (parameters->options().warn_common())
598 Symbol_table::report_resolve_problem(false,
599 _("definition of '%s' overriding "
600 "dynamic common definition"),
601 to, defined, object);
604 case DEF * 16 + DYN_DEF:
605 case WEAK_DEF * 16 + DYN_DEF:
606 // Ignore a dynamic definition if we already have a definition.
609 case DYN_DEF * 16 + DYN_DEF:
610 case DYN_WEAK_DEF * 16 + DYN_DEF:
611 // Ignore a dynamic definition if we already have a definition,
612 // unless the existing definition is an unversioned definition
613 // in the same dynamic object, and the new definition is a
615 if (to->object() == object
616 && to->version() == NULL
617 && is_default_version)
621 case UNDEF * 16 + DYN_DEF:
622 case DYN_UNDEF * 16 + DYN_DEF:
623 case DYN_WEAK_UNDEF * 16 + DYN_DEF:
624 // Use a dynamic definition if we have a reference.
627 case WEAK_UNDEF * 16 + DYN_DEF:
628 // When overriding a weak undef by a dynamic definition,
629 // we need to remember that the original undef was weak.
630 *adjust_dyndef = true;
633 case COMMON * 16 + DYN_DEF:
634 case WEAK_COMMON * 16 + DYN_DEF:
635 case DYN_COMMON * 16 + DYN_DEF:
636 case DYN_WEAK_COMMON * 16 + DYN_DEF:
637 // Ignore a dynamic definition if we already have a common
641 case DEF * 16 + DYN_WEAK_DEF:
642 case WEAK_DEF * 16 + DYN_WEAK_DEF:
643 case DYN_DEF * 16 + DYN_WEAK_DEF:
644 case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF:
645 // Ignore a weak dynamic definition if we already have a
649 case UNDEF * 16 + DYN_WEAK_DEF:
650 // When overriding an undef by a dynamic weak definition,
651 // we need to remember that the original undef was not weak.
652 *adjust_dyndef = true;
655 case DYN_UNDEF * 16 + DYN_WEAK_DEF:
656 case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF:
657 // Use a weak dynamic definition if we have a reference.
660 case WEAK_UNDEF * 16 + DYN_WEAK_DEF:
661 // When overriding a weak undef by a dynamic definition,
662 // we need to remember that the original undef was weak.
663 *adjust_dyndef = true;
666 case COMMON * 16 + DYN_WEAK_DEF:
667 case WEAK_COMMON * 16 + DYN_WEAK_DEF:
668 case DYN_COMMON * 16 + DYN_WEAK_DEF:
669 case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF:
670 // Ignore a weak dynamic definition if we already have a common
674 case DEF * 16 + UNDEF:
675 case WEAK_DEF * 16 + UNDEF:
676 case UNDEF * 16 + UNDEF:
677 // A new undefined reference tells us nothing.
680 case DYN_DEF * 16 + UNDEF:
681 case DYN_WEAK_DEF * 16 + UNDEF:
682 // For a dynamic def, we need to remember which kind of undef we see.
683 *adjust_dyndef = true;
686 case WEAK_UNDEF * 16 + UNDEF:
687 case DYN_UNDEF * 16 + UNDEF:
688 case DYN_WEAK_UNDEF * 16 + UNDEF:
689 // A strong undef overrides a dynamic or weak undef.
692 case COMMON * 16 + UNDEF:
693 case WEAK_COMMON * 16 + UNDEF:
694 case DYN_COMMON * 16 + UNDEF:
695 case DYN_WEAK_COMMON * 16 + UNDEF:
696 // A new undefined reference tells us nothing.
699 case DEF * 16 + WEAK_UNDEF:
700 case WEAK_DEF * 16 + WEAK_UNDEF:
701 case UNDEF * 16 + WEAK_UNDEF:
702 case WEAK_UNDEF * 16 + WEAK_UNDEF:
703 case DYN_UNDEF * 16 + WEAK_UNDEF:
704 case COMMON * 16 + WEAK_UNDEF:
705 case WEAK_COMMON * 16 + WEAK_UNDEF:
706 case DYN_COMMON * 16 + WEAK_UNDEF:
707 case DYN_WEAK_COMMON * 16 + WEAK_UNDEF:
708 // A new weak undefined reference tells us nothing unless the
709 // exisiting symbol is a dynamic weak reference.
712 case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF:
713 // A new weak reference overrides an existing dynamic weak reference.
714 // This is necessary because a dynamic weak reference remembers
715 // the old binding, which may not be weak. If we keeps the existing
716 // dynamic weak reference, the weakness may be dropped in the output.
719 case DYN_DEF * 16 + WEAK_UNDEF:
720 case DYN_WEAK_DEF * 16 + WEAK_UNDEF:
721 // For a dynamic def, we need to remember which kind of undef we see.
722 *adjust_dyndef = true;
725 case DEF * 16 + DYN_UNDEF:
726 case WEAK_DEF * 16 + DYN_UNDEF:
727 case DYN_DEF * 16 + DYN_UNDEF:
728 case DYN_WEAK_DEF * 16 + DYN_UNDEF:
729 case UNDEF * 16 + DYN_UNDEF:
730 case WEAK_UNDEF * 16 + DYN_UNDEF:
731 case DYN_UNDEF * 16 + DYN_UNDEF:
732 case DYN_WEAK_UNDEF * 16 + DYN_UNDEF:
733 case COMMON * 16 + DYN_UNDEF:
734 case WEAK_COMMON * 16 + DYN_UNDEF:
735 case DYN_COMMON * 16 + DYN_UNDEF:
736 case DYN_WEAK_COMMON * 16 + DYN_UNDEF:
737 // A new dynamic undefined reference tells us nothing.
740 case DEF * 16 + DYN_WEAK_UNDEF:
741 case WEAK_DEF * 16 + DYN_WEAK_UNDEF:
742 case DYN_DEF * 16 + DYN_WEAK_UNDEF:
743 case DYN_WEAK_DEF * 16 + DYN_WEAK_UNDEF:
744 case UNDEF * 16 + DYN_WEAK_UNDEF:
745 case WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
746 case DYN_UNDEF * 16 + DYN_WEAK_UNDEF:
747 case DYN_WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
748 case COMMON * 16 + DYN_WEAK_UNDEF:
749 case WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
750 case DYN_COMMON * 16 + DYN_WEAK_UNDEF:
751 case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
752 // A new weak dynamic undefined reference tells us nothing.
755 case DEF * 16 + COMMON:
756 // A common symbol does not override a definition.
757 if (parameters->options().warn_common())
758 Symbol_table::report_resolve_problem(false,
759 _("common '%s' overridden by "
760 "previous definition"),
761 to, defined, object);
764 case WEAK_DEF * 16 + COMMON:
765 case DYN_DEF * 16 + COMMON:
766 case DYN_WEAK_DEF * 16 + COMMON:
767 // A common symbol does override a weak definition or a dynamic
771 case UNDEF * 16 + COMMON:
772 case WEAK_UNDEF * 16 + COMMON:
773 case DYN_UNDEF * 16 + COMMON:
774 case DYN_WEAK_UNDEF * 16 + COMMON:
775 // A common symbol is a definition for a reference.
778 case COMMON * 16 + COMMON:
779 // Set the size to the maximum.
780 *adjust_common_sizes = true;
783 case WEAK_COMMON * 16 + COMMON:
784 // I'm not sure just what a weak common symbol means, but
785 // presumably it can be overridden by a regular common symbol.
788 case DYN_COMMON * 16 + COMMON:
789 case DYN_WEAK_COMMON * 16 + COMMON:
790 // Use the real common symbol, but adjust the size if necessary.
791 *adjust_common_sizes = true;
794 case DEF * 16 + WEAK_COMMON:
795 case WEAK_DEF * 16 + WEAK_COMMON:
796 case DYN_DEF * 16 + WEAK_COMMON:
797 case DYN_WEAK_DEF * 16 + WEAK_COMMON:
798 // Whatever a weak common symbol is, it won't override a
802 case UNDEF * 16 + WEAK_COMMON:
803 case WEAK_UNDEF * 16 + WEAK_COMMON:
804 case DYN_UNDEF * 16 + WEAK_COMMON:
805 case DYN_WEAK_UNDEF * 16 + WEAK_COMMON:
806 // A weak common symbol is better than an undefined symbol.
809 case COMMON * 16 + WEAK_COMMON:
810 case WEAK_COMMON * 16 + WEAK_COMMON:
811 case DYN_COMMON * 16 + WEAK_COMMON:
812 case DYN_WEAK_COMMON * 16 + WEAK_COMMON:
813 // Ignore a weak common symbol in the presence of a real common
817 case DEF * 16 + DYN_COMMON:
818 case WEAK_DEF * 16 + DYN_COMMON:
819 case DYN_DEF * 16 + DYN_COMMON:
820 case DYN_WEAK_DEF * 16 + DYN_COMMON:
821 // Ignore a dynamic common symbol in the presence of a
825 case UNDEF * 16 + DYN_COMMON:
826 case WEAK_UNDEF * 16 + DYN_COMMON:
827 case DYN_UNDEF * 16 + DYN_COMMON:
828 case DYN_WEAK_UNDEF * 16 + DYN_COMMON:
829 // A dynamic common symbol is a definition of sorts.
832 case COMMON * 16 + DYN_COMMON:
833 case WEAK_COMMON * 16 + DYN_COMMON:
834 case DYN_COMMON * 16 + DYN_COMMON:
835 case DYN_WEAK_COMMON * 16 + DYN_COMMON:
836 // Set the size to the maximum.
837 *adjust_common_sizes = true;
840 case DEF * 16 + DYN_WEAK_COMMON:
841 case WEAK_DEF * 16 + DYN_WEAK_COMMON:
842 case DYN_DEF * 16 + DYN_WEAK_COMMON:
843 case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON:
844 // A common symbol is ignored in the face of a definition.
847 case UNDEF * 16 + DYN_WEAK_COMMON:
848 case WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
849 case DYN_UNDEF * 16 + DYN_WEAK_COMMON:
850 case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
851 // I guess a weak common symbol is better than a definition.
854 case COMMON * 16 + DYN_WEAK_COMMON:
855 case WEAK_COMMON * 16 + DYN_WEAK_COMMON:
856 case DYN_COMMON * 16 + DYN_WEAK_COMMON:
857 case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON:
858 // Set the size to the maximum.
859 *adjust_common_sizes = true;
867 // Issue an error or warning due to symbol resolution. IS_ERROR
868 // indicates an error rather than a warning. MSG is the error
869 // message; it is expected to have a %s for the symbol name. TO is
870 // the existing symbol. DEFINED/OBJECT is where the new symbol was
873 // FIXME: We should have better location information here. When the
874 // symbol is defined, we should be able to pull the location from the
875 // debug info if there is any.
878 Symbol_table::report_resolve_problem(bool is_error, const char* msg,
879 const Symbol* to, Defined defined,
882 std::string demangled(to->demangled_name());
883 size_t len = strlen(msg) + demangled.length() + 10;
884 char* buf = new char[len];
885 snprintf(buf, len, msg, demangled.c_str());
891 objname = object->name().c_str();
894 objname = _("COPY reloc");
898 objname = _("command line");
901 objname = _("linker script");
904 case INCREMENTAL_BASE:
905 objname = _("linker defined");
912 gold_error("%s: %s", objname, buf);
914 gold_warning("%s: %s", objname, buf);
918 if (to->source() == Symbol::FROM_OBJECT)
919 objname = to->object()->name().c_str();
921 objname = _("command line");
922 gold_info("%s: %s: previous definition here", program_name, objname);
925 // A special case of should_override which is only called for a strong
926 // defined symbol from a regular object file. This is used when
927 // defining special symbols.
930 Symbol_table::should_override_with_special(const Symbol* to,
931 elfcpp::STT fromtype,
934 bool adjust_common_sizes;
936 unsigned int frombits = global_flag | regular_flag | def_flag;
937 bool ret = Symbol_table::should_override(to, frombits, fromtype, defined,
938 NULL, &adjust_common_sizes,
939 &adjust_dyn_def, false);
940 gold_assert(!adjust_common_sizes && !adjust_dyn_def);
944 // Override symbol base with a special symbol.
947 Symbol::override_base_with_special(const Symbol* from)
949 bool same_name = this->name_ == from->name_;
950 gold_assert(same_name || this->has_alias());
952 // If we are overriding an undef, remember the original binding.
953 if (this->is_undefined())
954 this->set_undef_binding(this->binding_);
956 this->source_ = from->source_;
957 switch (from->source_)
960 this->u_.from_object = from->u_.from_object;
963 this->u_.in_output_data = from->u_.in_output_data;
965 case IN_OUTPUT_SEGMENT:
966 this->u_.in_output_segment = from->u_.in_output_segment;
978 // When overriding a versioned symbol with a special symbol, we
979 // may be changing the version. This will happen if we see a
980 // special symbol such as "_end" defined in a shared object with
981 // one version (from a version script), but we want to define it
982 // here with a different version (from a different version
984 this->version_ = from->version_;
986 this->type_ = from->type_;
987 this->binding_ = from->binding_;
988 this->override_visibility(from->visibility_);
989 this->nonvis_ = from->nonvis_;
991 // Special symbols are always considered to be regular symbols.
992 this->in_reg_ = true;
994 if (from->needs_dynsym_entry_)
995 this->needs_dynsym_entry_ = true;
996 if (from->needs_dynsym_value_)
997 this->needs_dynsym_value_ = true;
999 this->is_predefined_ = from->is_predefined_;
1001 // We shouldn't see these flags. If we do, we need to handle them
1003 gold_assert(!from->is_forwarder_);
1004 gold_assert(!from->has_plt_offset());
1005 gold_assert(!from->has_warning_);
1006 gold_assert(!from->is_copied_from_dynobj_);
1007 gold_assert(!from->is_forced_local_);
1010 // Override a symbol with a special symbol.
1014 Sized_symbol<size>::override_with_special(const Sized_symbol<size>* from)
1016 this->override_base_with_special(from);
1017 this->value_ = from->value_;
1018 this->symsize_ = from->symsize_;
1021 // Override TOSYM with the special symbol FROMSYM. This handles all
1022 // aliases of TOSYM.
1026 Symbol_table::override_with_special(Sized_symbol<size>* tosym,
1027 const Sized_symbol<size>* fromsym)
1029 tosym->override_with_special(fromsym);
1030 if (tosym->has_alias())
1032 Symbol* sym = this->weak_aliases_[tosym];
1033 gold_assert(sym != NULL);
1034 Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
1037 ssym->override_with_special(fromsym);
1038 sym = this->weak_aliases_[ssym];
1039 gold_assert(sym != NULL);
1040 ssym = this->get_sized_symbol<size>(sym);
1042 while (ssym != tosym);
1044 if (tosym->binding() == elfcpp::STB_LOCAL
1045 || ((tosym->visibility() == elfcpp::STV_HIDDEN
1046 || tosym->visibility() == elfcpp::STV_INTERNAL)
1047 && (tosym->binding() == elfcpp::STB_GLOBAL
1048 || tosym->binding() == elfcpp::STB_GNU_UNIQUE
1049 || tosym->binding() == elfcpp::STB_WEAK)
1050 && !parameters->options().relocatable()))
1051 this->force_local(tosym);
1054 // Instantiate the templates we need. We could use the configure
1055 // script to restrict this to only the ones needed for implemented
1058 // We have to instantiate both big and little endian versions because
1059 // these are used by other templates that depends on size only.
1061 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
1064 Symbol_table::resolve<32, false>(
1065 Sized_symbol<32>* to,
1066 const elfcpp::Sym<32, false>& sym,
1067 unsigned int st_shndx,
1069 unsigned int orig_st_shndx,
1071 const char* version,
1072 bool is_default_version);
1076 Symbol_table::resolve<32, true>(
1077 Sized_symbol<32>* to,
1078 const elfcpp::Sym<32, true>& sym,
1079 unsigned int st_shndx,
1081 unsigned int orig_st_shndx,
1083 const char* version,
1084 bool is_default_version);
1087 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
1090 Symbol_table::resolve<64, false>(
1091 Sized_symbol<64>* to,
1092 const elfcpp::Sym<64, false>& sym,
1093 unsigned int st_shndx,
1095 unsigned int orig_st_shndx,
1097 const char* version,
1098 bool is_default_version);
1102 Symbol_table::resolve<64, true>(
1103 Sized_symbol<64>* to,
1104 const elfcpp::Sym<64, true>& sym,
1105 unsigned int st_shndx,
1107 unsigned int orig_st_shndx,
1109 const char* version,
1110 bool is_default_version);
1113 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
1116 Symbol_table::override_with_special<32>(Sized_symbol<32>*,
1117 const Sized_symbol<32>*);
1120 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
1123 Symbol_table::override_with_special<64>(Sized_symbol<64>*,
1124 const Sized_symbol<64>*);
1127 } // End namespace gold.