1 // resolve.cc -- symbol resolution for gold
3 // Copyright (C) 2006-2019 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->u1_.object = object;
96 this->override_version(version);
97 this->u2_.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)
101 this->type_ = sym.get_st_type();
102 this->binding_ = sym.get_st_bind();
103 this->override_visibility(sym.get_st_visibility());
104 this->nonvis_ = sym.get_st_nonvis();
105 if (object->is_dynamic())
106 this->in_dyn_ = true;
108 this->in_reg_ = true;
111 // Override the fields in Sized_symbol.
114 template<bool big_endian>
116 Sized_symbol<size>::override(const elfcpp::Sym<size, big_endian>& sym,
117 unsigned st_shndx, bool is_ordinary,
118 Object* object, const char* version)
120 this->override_base(sym, st_shndx, is_ordinary, object, version);
121 this->value_ = sym.get_st_value();
122 this->symsize_ = sym.get_st_size();
125 // Override TOSYM with symbol FROMSYM, defined in OBJECT, with version
126 // VERSION. This handles all aliases of TOSYM.
128 template<int size, bool big_endian>
130 Symbol_table::override(Sized_symbol<size>* tosym,
131 const elfcpp::Sym<size, big_endian>& fromsym,
132 unsigned int st_shndx, bool is_ordinary,
133 Object* object, const char* version)
135 tosym->override(fromsym, st_shndx, is_ordinary, object, version);
136 if (tosym->has_alias())
138 Symbol* sym = this->weak_aliases_[tosym];
139 gold_assert(sym != NULL);
140 Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
143 ssym->override(fromsym, st_shndx, is_ordinary, object, version);
144 sym = this->weak_aliases_[ssym];
145 gold_assert(sym != NULL);
146 ssym = this->get_sized_symbol<size>(sym);
148 while (ssym != tosym);
152 // The resolve functions build a little code for each symbol.
153 // Bit 0: 0 for global, 1 for weak.
154 // Bit 1: 0 for regular object, 1 for shared object
155 // Bits 2-3: 0 for normal, 1 for undefined, 2 for common
156 // This gives us values from 0 to 11.
158 static const int global_or_weak_shift = 0;
159 static const unsigned int global_flag = 0 << global_or_weak_shift;
160 static const unsigned int weak_flag = 1 << global_or_weak_shift;
162 static const int regular_or_dynamic_shift = 1;
163 static const unsigned int regular_flag = 0 << regular_or_dynamic_shift;
164 static const unsigned int dynamic_flag = 1 << regular_or_dynamic_shift;
166 static const int def_undef_or_common_shift = 2;
167 static const unsigned int def_flag = 0 << def_undef_or_common_shift;
168 static const unsigned int undef_flag = 1 << def_undef_or_common_shift;
169 static const unsigned int common_flag = 2 << def_undef_or_common_shift;
171 // This convenience function combines all the flags based on facts
175 symbol_to_bits(elfcpp::STB binding, bool is_dynamic,
176 unsigned int shndx, bool is_ordinary)
182 case elfcpp::STB_GLOBAL:
183 case elfcpp::STB_GNU_UNIQUE:
187 case elfcpp::STB_WEAK:
191 case elfcpp::STB_LOCAL:
192 // We should only see externally visible symbols in the symbol
194 gold_error(_("invalid STB_LOCAL symbol in external symbols"));
199 // Any target which wants to handle STB_LOOS, etc., needs to
200 // define a resolve method.
201 gold_error(_("unsupported symbol binding %d"), static_cast<int>(binding));
206 bits |= dynamic_flag;
208 bits |= regular_flag;
212 case elfcpp::SHN_UNDEF:
216 case elfcpp::SHN_COMMON:
222 if (!is_ordinary && Symbol::is_common_shndx(shndx))
232 // Resolve a symbol. This is called the second and subsequent times
233 // we see a symbol. TO is the pre-existing symbol. ST_SHNDX is the
234 // section index for SYM, possibly adjusted for many sections.
235 // IS_ORDINARY is whether ST_SHNDX is a normal section index rather
236 // than a special code. ORIG_ST_SHNDX is the original section index,
237 // before any munging because of discarded sections, except that all
238 // non-ordinary section indexes are mapped to SHN_UNDEF. VERSION is
239 // the version of SYM.
241 template<int size, bool big_endian>
243 Symbol_table::resolve(Sized_symbol<size>* to,
244 const elfcpp::Sym<size, big_endian>& sym,
245 unsigned int st_shndx, bool is_ordinary,
246 unsigned int orig_st_shndx,
247 Object* object, const char* version,
248 bool is_default_version)
251 const unsigned int to_shndx = to->shndx(&to_is_ordinary);
253 // It's possible for a symbol to be defined in an object file
254 // using .symver to give it a version, and for there to also be
255 // a linker script giving that symbol the same version. We
256 // don't want to give a multiple-definition error for this
257 // harmless redefinition.
258 if (to->source() == Symbol::FROM_OBJECT
259 && to->object() == object
263 && to_shndx == st_shndx
264 && to->value() == sym.get_st_value())
267 // Likewise for an absolute symbol defined twice with the same value.
269 && st_shndx == elfcpp::SHN_ABS
271 && to_shndx == elfcpp::SHN_ABS
272 && to->value() == sym.get_st_value())
275 if (parameters->target().has_resolve())
277 Sized_target<size, big_endian>* sized_target;
278 sized_target = parameters->sized_target<size, big_endian>();
279 if (sized_target->resolve(to, sym, object, version))
283 if (!object->is_dynamic())
285 if (sym.get_st_type() == elfcpp::STT_COMMON
286 && (is_ordinary || !Symbol::is_common_shndx(st_shndx)))
288 gold_warning(_("STT_COMMON symbol '%s' in %s "
289 "is not in a common section"),
290 to->demangled_name().c_str(),
291 to->object()->name().c_str());
294 // Record that we've seen this symbol in a regular object.
297 else if (st_shndx == elfcpp::SHN_UNDEF
298 && (to->visibility() == elfcpp::STV_HIDDEN
299 || to->visibility() == elfcpp::STV_INTERNAL))
301 // The symbol is hidden, so a reference from a shared object
302 // cannot bind to it. We tried issuing a warning in this case,
303 // but that produces false positives when the symbol is
304 // actually resolved in a different shared object (PR 15574).
309 // Record that we've seen this symbol in a dynamic object.
313 // Record if we've seen this symbol in a real ELF object (i.e., the
314 // symbol is referenced from outside the world known to the plugin).
315 if (object->pluginobj() == NULL && !object->is_dynamic())
316 to->set_in_real_elf();
318 // If we're processing replacement files, allow new symbols to override
319 // the placeholders from the plugin objects.
320 // Treat common symbols specially since it is possible that an ELF
321 // file increased the size of the alignment.
322 if (to->source() == Symbol::FROM_OBJECT)
324 Pluginobj* obj = to->object()->pluginobj();
326 && parameters->options().plugins()->in_replacement_phase())
328 bool adjust_common = false;
329 typename Sized_symbol<size>::Size_type tosize = 0;
330 typename Sized_symbol<size>::Value_type tovalue = 0;
332 && !is_ordinary && Symbol::is_common_shndx(st_shndx))
334 adjust_common = true;
335 tosize = to->symsize();
336 tovalue = to->value();
338 this->override(to, sym, st_shndx, is_ordinary, object, version);
341 if (tosize > to->symsize())
342 to->set_symsize(tosize);
343 if (tovalue > to->value())
344 to->set_value(tovalue);
350 // A new weak undefined reference, merging with an old weak
351 // reference, could be a One Definition Rule (ODR) violation --
352 // especially if the types or sizes of the references differ. We'll
353 // store such pairs and look them up later to make sure they
354 // actually refer to the same lines of code. We also check
355 // combinations of weak and strong, which might occur if one case is
356 // inline and the other is not. (Note: not all ODR violations can
357 // be found this way, and not everything this finds is an ODR
358 // violation. But it's helpful to warn about.)
359 if (parameters->options().detect_odr_violations()
360 && (sym.get_st_bind() == elfcpp::STB_WEAK
361 || to->binding() == elfcpp::STB_WEAK)
362 && orig_st_shndx != elfcpp::SHN_UNDEF
364 && to_shndx != elfcpp::SHN_UNDEF
365 && sym.get_st_size() != 0 // Ignore weird 0-sized symbols.
366 && to->symsize() != 0
367 && (sym.get_st_type() != to->type()
368 || sym.get_st_size() != to->symsize())
369 // C does not have a concept of ODR, so we only need to do this
370 // on C++ symbols. These have (mangled) names starting with _Z.
371 && to->name()[0] == '_' && to->name()[1] == 'Z')
373 Symbol_location fromloc
374 = { object, orig_st_shndx, static_cast<off_t>(sym.get_st_value()) };
375 Symbol_location toloc = { to->object(), to_shndx,
376 static_cast<off_t>(to->value()) };
377 this->candidate_odr_violations_[to->name()].insert(fromloc);
378 this->candidate_odr_violations_[to->name()].insert(toloc);
381 // Plugins don't provide a symbol type, so adopt the existing type
382 // if the FROM symbol is from a plugin.
383 elfcpp::STT fromtype = (object->pluginobj() != NULL
385 : sym.get_st_type());
386 unsigned int frombits = symbol_to_bits(sym.get_st_bind(),
387 object->is_dynamic(),
388 st_shndx, is_ordinary);
390 bool adjust_common_sizes;
392 typename Sized_symbol<size>::Size_type tosize = to->symsize();
393 if (Symbol_table::should_override(to, frombits, fromtype, OBJECT,
394 object, &adjust_common_sizes,
395 &adjust_dyndef, is_default_version))
397 elfcpp::STB orig_tobinding = to->binding();
398 typename Sized_symbol<size>::Value_type tovalue = to->value();
399 this->override(to, sym, st_shndx, is_ordinary, object, version);
400 if (adjust_common_sizes)
402 if (tosize > to->symsize())
403 to->set_symsize(tosize);
404 if (tovalue > to->value())
405 to->set_value(tovalue);
409 // We are overriding an UNDEF or WEAK UNDEF with a DYN DEF.
410 // Remember which kind of UNDEF it was for future reference.
411 to->set_undef_binding(orig_tobinding);
416 if (adjust_common_sizes)
418 if (sym.get_st_size() > tosize)
419 to->set_symsize(sym.get_st_size());
420 if (sym.get_st_value() > to->value())
421 to->set_value(sym.get_st_value());
425 // We are keeping a DYN DEF after seeing an UNDEF or WEAK UNDEF.
426 // Remember which kind of UNDEF it was.
427 to->set_undef_binding(sym.get_st_bind());
429 // The ELF ABI says that even for a reference to a symbol we
430 // merge the visibility.
431 to->override_visibility(sym.get_st_visibility());
434 // If we have a non-WEAK reference from a regular object to a
435 // dynamic object, mark the dynamic object as needed.
436 if (to->is_from_dynobj() && to->in_reg() && !to->is_undef_binding_weak())
437 to->object()->set_is_needed();
439 if (adjust_common_sizes && parameters->options().warn_common())
441 if (tosize > sym.get_st_size())
442 Symbol_table::report_resolve_problem(false,
443 _("common of '%s' overriding "
446 else if (tosize < sym.get_st_size())
447 Symbol_table::report_resolve_problem(false,
448 _("common of '%s' overidden by "
452 Symbol_table::report_resolve_problem(false,
453 _("multiple common of '%s'"),
458 // Handle the core of symbol resolution. This is called with the
459 // existing symbol, TO, and a bitflag describing the new symbol. This
460 // returns true if we should override the existing symbol with the new
461 // one, and returns false otherwise. It sets *ADJUST_COMMON_SIZES to
462 // true if we should set the symbol size to the maximum of the TO and
463 // FROM sizes. It handles error conditions.
466 Symbol_table::should_override(const Symbol* to, unsigned int frombits,
467 elfcpp::STT fromtype, Defined defined,
468 Object* object, bool* adjust_common_sizes,
469 bool* adjust_dyndef, bool is_default_version)
471 *adjust_common_sizes = false;
472 *adjust_dyndef = false;
475 if (to->source() == Symbol::IS_UNDEFINED)
476 tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_UNDEF, true);
477 else if (to->source() != Symbol::FROM_OBJECT)
478 tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_ABS, false);
482 unsigned int shndx = to->shndx(&is_ordinary);
483 tobits = symbol_to_bits(to->binding(),
484 to->object()->is_dynamic(),
489 if ((to->type() == elfcpp::STT_TLS) ^ (fromtype == elfcpp::STT_TLS)
490 && !to->is_placeholder())
491 Symbol_table::report_resolve_problem(true,
492 _("symbol '%s' used as both __thread "
494 to, defined, object);
496 // We use a giant switch table for symbol resolution. This code is
497 // unwieldy, but: 1) it is efficient; 2) we definitely handle all
498 // cases; 3) it is easy to change the handling of a particular case.
499 // The alternative would be a series of conditionals, but it is easy
500 // to get the ordering wrong. This could also be done as a table,
501 // but that is no easier to understand than this large switch
504 // These are the values generated by the bit codes.
507 DEF = global_flag | regular_flag | def_flag,
508 WEAK_DEF = weak_flag | regular_flag | def_flag,
509 DYN_DEF = global_flag | dynamic_flag | def_flag,
510 DYN_WEAK_DEF = weak_flag | dynamic_flag | def_flag,
511 UNDEF = global_flag | regular_flag | undef_flag,
512 WEAK_UNDEF = weak_flag | regular_flag | undef_flag,
513 DYN_UNDEF = global_flag | dynamic_flag | undef_flag,
514 DYN_WEAK_UNDEF = weak_flag | dynamic_flag | undef_flag,
515 COMMON = global_flag | regular_flag | common_flag,
516 WEAK_COMMON = weak_flag | regular_flag | common_flag,
517 DYN_COMMON = global_flag | dynamic_flag | common_flag,
518 DYN_WEAK_COMMON = weak_flag | dynamic_flag | common_flag
521 switch (tobits * 16 + frombits)
524 // Two definitions of the same symbol.
526 // If either symbol is defined by an object included using
527 // --just-symbols, then don't warn. This is for compatibility
528 // with the GNU linker. FIXME: This is a hack.
529 if ((to->source() == Symbol::FROM_OBJECT && to->object()->just_symbols())
530 || (object != NULL && object->just_symbols()))
533 if (!parameters->options().muldefs())
534 Symbol_table::report_resolve_problem(true,
535 _("multiple definition of '%s'"),
536 to, defined, object);
539 case WEAK_DEF * 16 + DEF:
540 // We've seen a weak definition, and now we see a strong
541 // definition. In the original SVR4 linker, this was treated as
542 // a multiple definition error. In the Solaris linker and the
543 // GNU linker, a weak definition followed by a regular
544 // definition causes the weak definition to be overridden. We
545 // are currently compatible with the GNU linker. In the future
546 // we should add a target specific option to change this.
550 case DYN_DEF * 16 + DEF:
551 case DYN_WEAK_DEF * 16 + DEF:
552 // We've seen a definition in a dynamic object, and now we see a
553 // definition in a regular object. The definition in the
554 // regular object overrides the definition in the dynamic
558 case UNDEF * 16 + DEF:
559 case WEAK_UNDEF * 16 + DEF:
560 case DYN_UNDEF * 16 + DEF:
561 case DYN_WEAK_UNDEF * 16 + DEF:
562 // We've seen an undefined reference, and now we see a
563 // definition. We use the definition.
566 case COMMON * 16 + DEF:
567 case WEAK_COMMON * 16 + DEF:
568 case DYN_COMMON * 16 + DEF:
569 case DYN_WEAK_COMMON * 16 + DEF:
570 // We've seen a common symbol and now we see a definition. The
571 // definition overrides.
572 if (parameters->options().warn_common())
573 Symbol_table::report_resolve_problem(false,
574 _("definition of '%s' overriding "
576 to, defined, object);
579 case DEF * 16 + WEAK_DEF:
580 case WEAK_DEF * 16 + WEAK_DEF:
581 // We've seen a definition and now we see a weak definition. We
582 // ignore the new weak definition.
585 case DYN_DEF * 16 + WEAK_DEF:
586 case DYN_WEAK_DEF * 16 + WEAK_DEF:
587 // We've seen a dynamic definition and now we see a regular weak
588 // definition. The regular weak definition overrides.
591 case UNDEF * 16 + WEAK_DEF:
592 case WEAK_UNDEF * 16 + WEAK_DEF:
593 case DYN_UNDEF * 16 + WEAK_DEF:
594 case DYN_WEAK_UNDEF * 16 + WEAK_DEF:
595 // A weak definition of a currently undefined symbol.
598 case COMMON * 16 + WEAK_DEF:
599 case WEAK_COMMON * 16 + WEAK_DEF:
600 // A weak definition does not override a common definition.
603 case DYN_COMMON * 16 + WEAK_DEF:
604 case DYN_WEAK_COMMON * 16 + WEAK_DEF:
605 // A weak definition does override a definition in a dynamic
607 if (parameters->options().warn_common())
608 Symbol_table::report_resolve_problem(false,
609 _("definition of '%s' overriding "
610 "dynamic common definition"),
611 to, defined, object);
614 case DEF * 16 + DYN_DEF:
615 case WEAK_DEF * 16 + DYN_DEF:
616 // Ignore a dynamic definition if we already have a definition.
619 case DYN_DEF * 16 + DYN_DEF:
620 case DYN_WEAK_DEF * 16 + DYN_DEF:
621 // Ignore a dynamic definition if we already have a definition,
622 // unless the existing definition is an unversioned definition
623 // in the same dynamic object, and the new definition is a
625 if (to->object() == object
626 && to->version() == NULL
627 && is_default_version)
629 // Or, if the existing definition is in an unused --as-needed library,
630 // and the reference is weak, let the new definition override.
632 && to->is_undef_binding_weak()
633 && to->object()->as_needed()
634 && !to->object()->is_needed())
638 case UNDEF * 16 + DYN_DEF:
639 case DYN_UNDEF * 16 + DYN_DEF:
640 case DYN_WEAK_UNDEF * 16 + DYN_DEF:
641 // Use a dynamic definition if we have a reference.
644 case WEAK_UNDEF * 16 + DYN_DEF:
645 // When overriding a weak undef by a dynamic definition,
646 // we need to remember that the original undef was weak.
647 *adjust_dyndef = true;
650 case COMMON * 16 + DYN_DEF:
651 case WEAK_COMMON * 16 + DYN_DEF:
652 // Ignore a dynamic definition if we already have a common
656 case DEF * 16 + DYN_WEAK_DEF:
657 case WEAK_DEF * 16 + DYN_WEAK_DEF:
658 // Ignore a weak dynamic definition if we already have a
662 case UNDEF * 16 + DYN_WEAK_DEF:
663 // When overriding an undef by a dynamic weak definition,
664 // we need to remember that the original undef was not weak.
665 *adjust_dyndef = true;
668 case DYN_UNDEF * 16 + DYN_WEAK_DEF:
669 case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF:
670 // Use a weak dynamic definition if we have a reference.
673 case WEAK_UNDEF * 16 + DYN_WEAK_DEF:
674 // When overriding a weak undef by a dynamic definition,
675 // we need to remember that the original undef was weak.
676 *adjust_dyndef = true;
679 case COMMON * 16 + DYN_WEAK_DEF:
680 case WEAK_COMMON * 16 + DYN_WEAK_DEF:
681 // Ignore a weak dynamic definition if we already have a common
685 case DYN_COMMON * 16 + DYN_DEF:
686 case DYN_WEAK_COMMON * 16 + DYN_DEF:
687 case DYN_DEF * 16 + DYN_WEAK_DEF:
688 case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF:
689 case DYN_COMMON * 16 + DYN_WEAK_DEF:
690 case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF:
691 // If the existing definition is in an unused --as-needed library,
692 // and the reference is weak, let a new dynamic definition override.
694 && to->is_undef_binding_weak()
695 && to->object()->as_needed()
696 && !to->object()->is_needed())
700 case DEF * 16 + UNDEF:
701 case WEAK_DEF * 16 + UNDEF:
702 case UNDEF * 16 + UNDEF:
703 // A new undefined reference tells us nothing.
706 case DYN_DEF * 16 + UNDEF:
707 case DYN_WEAK_DEF * 16 + UNDEF:
708 // For a dynamic def, we need to remember which kind of undef we see.
709 *adjust_dyndef = true;
712 case WEAK_UNDEF * 16 + UNDEF:
713 case DYN_UNDEF * 16 + UNDEF:
714 case DYN_WEAK_UNDEF * 16 + UNDEF:
715 // A strong undef overrides a dynamic or weak undef.
718 case COMMON * 16 + UNDEF:
719 case WEAK_COMMON * 16 + UNDEF:
720 case DYN_COMMON * 16 + UNDEF:
721 case DYN_WEAK_COMMON * 16 + UNDEF:
722 // A new undefined reference tells us nothing.
725 case DEF * 16 + WEAK_UNDEF:
726 case WEAK_DEF * 16 + WEAK_UNDEF:
727 case UNDEF * 16 + WEAK_UNDEF:
728 case WEAK_UNDEF * 16 + WEAK_UNDEF:
729 case DYN_UNDEF * 16 + WEAK_UNDEF:
730 case COMMON * 16 + WEAK_UNDEF:
731 case WEAK_COMMON * 16 + WEAK_UNDEF:
732 case DYN_COMMON * 16 + WEAK_UNDEF:
733 case DYN_WEAK_COMMON * 16 + WEAK_UNDEF:
734 // A new weak undefined reference tells us nothing unless the
735 // exisiting symbol is a dynamic weak reference.
738 case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF:
739 // A new weak reference overrides an existing dynamic weak reference.
740 // This is necessary because a dynamic weak reference remembers
741 // the old binding, which may not be weak. If we keeps the existing
742 // dynamic weak reference, the weakness may be dropped in the output.
745 case DYN_DEF * 16 + WEAK_UNDEF:
746 case DYN_WEAK_DEF * 16 + WEAK_UNDEF:
747 // For a dynamic def, we need to remember which kind of undef we see.
748 *adjust_dyndef = true;
751 case DEF * 16 + DYN_UNDEF:
752 case WEAK_DEF * 16 + DYN_UNDEF:
753 case DYN_DEF * 16 + DYN_UNDEF:
754 case DYN_WEAK_DEF * 16 + DYN_UNDEF:
755 case UNDEF * 16 + DYN_UNDEF:
756 case WEAK_UNDEF * 16 + DYN_UNDEF:
757 case DYN_UNDEF * 16 + DYN_UNDEF:
758 case DYN_WEAK_UNDEF * 16 + DYN_UNDEF:
759 case COMMON * 16 + DYN_UNDEF:
760 case WEAK_COMMON * 16 + DYN_UNDEF:
761 case DYN_COMMON * 16 + DYN_UNDEF:
762 case DYN_WEAK_COMMON * 16 + DYN_UNDEF:
763 // A new dynamic undefined reference tells us nothing.
766 case DEF * 16 + DYN_WEAK_UNDEF:
767 case WEAK_DEF * 16 + DYN_WEAK_UNDEF:
768 case DYN_DEF * 16 + DYN_WEAK_UNDEF:
769 case DYN_WEAK_DEF * 16 + DYN_WEAK_UNDEF:
770 case UNDEF * 16 + DYN_WEAK_UNDEF:
771 case WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
772 case DYN_UNDEF * 16 + DYN_WEAK_UNDEF:
773 case DYN_WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
774 case COMMON * 16 + DYN_WEAK_UNDEF:
775 case WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
776 case DYN_COMMON * 16 + DYN_WEAK_UNDEF:
777 case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
778 // A new weak dynamic undefined reference tells us nothing.
781 case DEF * 16 + COMMON:
782 // A common symbol does not override a definition.
783 if (parameters->options().warn_common())
784 Symbol_table::report_resolve_problem(false,
785 _("common '%s' overridden by "
786 "previous definition"),
787 to, defined, object);
790 case WEAK_DEF * 16 + COMMON:
791 case DYN_DEF * 16 + COMMON:
792 case DYN_WEAK_DEF * 16 + COMMON:
793 // A common symbol does override a weak definition or a dynamic
797 case UNDEF * 16 + COMMON:
798 case WEAK_UNDEF * 16 + COMMON:
799 case DYN_UNDEF * 16 + COMMON:
800 case DYN_WEAK_UNDEF * 16 + COMMON:
801 // A common symbol is a definition for a reference.
804 case COMMON * 16 + COMMON:
805 // Set the size to the maximum.
806 *adjust_common_sizes = true;
809 case WEAK_COMMON * 16 + COMMON:
810 // I'm not sure just what a weak common symbol means, but
811 // presumably it can be overridden by a regular common symbol.
814 case DYN_COMMON * 16 + COMMON:
815 case DYN_WEAK_COMMON * 16 + COMMON:
816 // Use the real common symbol, but adjust the size if necessary.
817 *adjust_common_sizes = true;
820 case DEF * 16 + WEAK_COMMON:
821 case WEAK_DEF * 16 + WEAK_COMMON:
822 case DYN_DEF * 16 + WEAK_COMMON:
823 case DYN_WEAK_DEF * 16 + WEAK_COMMON:
824 // Whatever a weak common symbol is, it won't override a
828 case UNDEF * 16 + WEAK_COMMON:
829 case WEAK_UNDEF * 16 + WEAK_COMMON:
830 case DYN_UNDEF * 16 + WEAK_COMMON:
831 case DYN_WEAK_UNDEF * 16 + WEAK_COMMON:
832 // A weak common symbol is better than an undefined symbol.
835 case COMMON * 16 + WEAK_COMMON:
836 case WEAK_COMMON * 16 + WEAK_COMMON:
837 case DYN_COMMON * 16 + WEAK_COMMON:
838 case DYN_WEAK_COMMON * 16 + WEAK_COMMON:
839 // Ignore a weak common symbol in the presence of a real common
843 case DEF * 16 + DYN_COMMON:
844 case WEAK_DEF * 16 + DYN_COMMON:
845 case DYN_DEF * 16 + DYN_COMMON:
846 case DYN_WEAK_DEF * 16 + DYN_COMMON:
847 // Ignore a dynamic common symbol in the presence of a
851 case UNDEF * 16 + DYN_COMMON:
852 case WEAK_UNDEF * 16 + DYN_COMMON:
853 case DYN_UNDEF * 16 + DYN_COMMON:
854 case DYN_WEAK_UNDEF * 16 + DYN_COMMON:
855 // A dynamic common symbol is a definition of sorts.
858 case COMMON * 16 + DYN_COMMON:
859 case WEAK_COMMON * 16 + DYN_COMMON:
860 case DYN_COMMON * 16 + DYN_COMMON:
861 case DYN_WEAK_COMMON * 16 + DYN_COMMON:
862 // Set the size to the maximum.
863 *adjust_common_sizes = true;
866 case DEF * 16 + DYN_WEAK_COMMON:
867 case WEAK_DEF * 16 + DYN_WEAK_COMMON:
868 case DYN_DEF * 16 + DYN_WEAK_COMMON:
869 case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON:
870 // A common symbol is ignored in the face of a definition.
873 case UNDEF * 16 + DYN_WEAK_COMMON:
874 case WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
875 case DYN_UNDEF * 16 + DYN_WEAK_COMMON:
876 case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
877 // I guess a weak common symbol is better than a definition.
880 case COMMON * 16 + DYN_WEAK_COMMON:
881 case WEAK_COMMON * 16 + DYN_WEAK_COMMON:
882 case DYN_COMMON * 16 + DYN_WEAK_COMMON:
883 case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON:
884 // Set the size to the maximum.
885 *adjust_common_sizes = true;
893 // Issue an error or warning due to symbol resolution. IS_ERROR
894 // indicates an error rather than a warning. MSG is the error
895 // message; it is expected to have a %s for the symbol name. TO is
896 // the existing symbol. DEFINED/OBJECT is where the new symbol was
899 // FIXME: We should have better location information here. When the
900 // symbol is defined, we should be able to pull the location from the
901 // debug info if there is any.
904 Symbol_table::report_resolve_problem(bool is_error, const char* msg,
905 const Symbol* to, Defined defined,
908 std::string demangled(to->demangled_name());
909 size_t len = strlen(msg) + demangled.length() + 10;
910 char* buf = new char[len];
911 snprintf(buf, len, msg, demangled.c_str());
917 objname = object->name().c_str();
920 objname = _("COPY reloc");
924 objname = _("command line");
927 objname = _("linker script");
930 case INCREMENTAL_BASE:
931 objname = _("linker defined");
938 gold_error("%s: %s", objname, buf);
940 gold_warning("%s: %s", objname, buf);
944 if (to->source() == Symbol::FROM_OBJECT)
945 objname = to->object()->name().c_str();
947 objname = _("command line");
948 gold_info("%s: %s: previous definition here", program_name, objname);
951 // Completely override existing symbol. Everything bar name_,
952 // version_, and is_forced_local_ flag are copied. version_ is
953 // cleared if from->version_ is clear. Returns true if this symbol
954 // should be forced local.
956 Symbol::clone(const Symbol* from)
958 // Don't allow cloning after dynamic linking info is attached to symbols.
959 // We aren't prepared to merge such.
960 gold_assert(!this->has_symtab_index() && !from->has_symtab_index());
961 gold_assert(!this->has_dynsym_index() && !from->has_dynsym_index());
962 gold_assert(this->got_offset_list() == NULL
963 && from->got_offset_list() == NULL);
964 gold_assert(!this->has_plt_offset() && !from->has_plt_offset());
967 this->version_ = from->version_;
968 this->u1_ = from->u1_;
969 this->u2_ = from->u2_;
970 this->type_ = from->type_;
971 this->binding_ = from->binding_;
972 this->visibility_ = from->visibility_;
973 this->nonvis_ = from->nonvis_;
974 this->source_ = from->source_;
975 this->is_def_ = from->is_def_;
976 this->is_forwarder_ = from->is_forwarder_;
977 this->has_alias_ = from->has_alias_;
978 this->needs_dynsym_entry_ = from->needs_dynsym_entry_;
979 this->in_reg_ = from->in_reg_;
980 this->in_dyn_ = from->in_dyn_;
981 this->needs_dynsym_value_ = from->needs_dynsym_value_;
982 this->has_warning_ = from->has_warning_;
983 this->is_copied_from_dynobj_ = from->is_copied_from_dynobj_;
984 this->is_ordinary_shndx_ = from->is_ordinary_shndx_;
985 this->in_real_elf_ = from->in_real_elf_;
986 this->is_defined_in_discarded_section_
987 = from->is_defined_in_discarded_section_;
988 this->undef_binding_set_ = from->undef_binding_set_;
989 this->undef_binding_weak_ = from->undef_binding_weak_;
990 this->is_predefined_ = from->is_predefined_;
991 this->is_protected_ = from->is_protected_;
992 this->non_zero_localentry_ = from->non_zero_localentry_;
994 return !this->is_forced_local_ && from->is_forced_local_;
999 Sized_symbol<size>::clone(const Sized_symbol<size>* from)
1001 this->value_ = from->value_;
1002 this->symsize_ = from->symsize_;
1003 return Symbol::clone(from);
1006 // A special case of should_override which is only called for a strong
1007 // defined symbol from a regular object file. This is used when
1008 // defining special symbols.
1011 Symbol_table::should_override_with_special(const Symbol* to,
1012 elfcpp::STT fromtype,
1015 bool adjust_common_sizes;
1016 bool adjust_dyn_def;
1017 unsigned int frombits = global_flag | regular_flag | def_flag;
1018 bool ret = Symbol_table::should_override(to, frombits, fromtype, defined,
1019 NULL, &adjust_common_sizes,
1020 &adjust_dyn_def, false);
1021 gold_assert(!adjust_common_sizes && !adjust_dyn_def);
1025 // Override symbol base with a special symbol.
1028 Symbol::override_base_with_special(const Symbol* from)
1030 bool same_name = this->name_ == from->name_;
1031 gold_assert(same_name || this->has_alias());
1033 // If we are overriding an undef, remember the original binding.
1034 if (this->is_undefined())
1035 this->set_undef_binding(this->binding_);
1037 this->source_ = from->source_;
1038 switch (from->source_)
1041 case IN_OUTPUT_DATA:
1042 case IN_OUTPUT_SEGMENT:
1043 this->u1_ = from->u1_;
1044 this->u2_ = from->u2_;
1056 // When overriding a versioned symbol with a special symbol, we
1057 // may be changing the version. This will happen if we see a
1058 // special symbol such as "_end" defined in a shared object with
1059 // one version (from a version script), but we want to define it
1060 // here with a different version (from a different version
1062 this->version_ = from->version_;
1064 this->type_ = from->type_;
1065 this->binding_ = from->binding_;
1066 this->override_visibility(from->visibility_);
1067 this->nonvis_ = from->nonvis_;
1069 // Special symbols are always considered to be regular symbols.
1070 this->in_reg_ = true;
1072 if (from->needs_dynsym_entry_)
1073 this->needs_dynsym_entry_ = true;
1074 if (from->needs_dynsym_value_)
1075 this->needs_dynsym_value_ = true;
1077 this->is_predefined_ = from->is_predefined_;
1079 // We shouldn't see these flags. If we do, we need to handle them
1081 gold_assert(!from->is_forwarder_);
1082 gold_assert(!from->has_plt_offset());
1083 gold_assert(!from->has_warning_);
1084 gold_assert(!from->is_copied_from_dynobj_);
1085 gold_assert(!from->is_forced_local_);
1088 // Override a symbol with a special symbol.
1092 Sized_symbol<size>::override_with_special(const Sized_symbol<size>* from)
1094 this->override_base_with_special(from);
1095 this->value_ = from->value_;
1096 this->symsize_ = from->symsize_;
1099 // Override TOSYM with the special symbol FROMSYM. This handles all
1100 // aliases of TOSYM.
1104 Symbol_table::override_with_special(Sized_symbol<size>* tosym,
1105 const Sized_symbol<size>* fromsym)
1107 tosym->override_with_special(fromsym);
1108 if (tosym->has_alias())
1110 Symbol* sym = this->weak_aliases_[tosym];
1111 gold_assert(sym != NULL);
1112 Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
1115 ssym->override_with_special(fromsym);
1116 sym = this->weak_aliases_[ssym];
1117 gold_assert(sym != NULL);
1118 ssym = this->get_sized_symbol<size>(sym);
1120 while (ssym != tosym);
1122 if (tosym->binding() == elfcpp::STB_LOCAL
1123 || ((tosym->visibility() == elfcpp::STV_HIDDEN
1124 || tosym->visibility() == elfcpp::STV_INTERNAL)
1125 && (tosym->binding() == elfcpp::STB_GLOBAL
1126 || tosym->binding() == elfcpp::STB_GNU_UNIQUE
1127 || tosym->binding() == elfcpp::STB_WEAK)
1128 && !parameters->options().relocatable()))
1129 this->force_local(tosym);
1132 // Instantiate the templates we need. We could use the configure
1133 // script to restrict this to only the ones needed for implemented
1136 // We have to instantiate both big and little endian versions because
1137 // these are used by other templates that depends on size only.
1139 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
1142 Symbol_table::resolve<32, false>(
1143 Sized_symbol<32>* to,
1144 const elfcpp::Sym<32, false>& sym,
1145 unsigned int st_shndx,
1147 unsigned int orig_st_shndx,
1149 const char* version,
1150 bool is_default_version);
1154 Symbol_table::resolve<32, true>(
1155 Sized_symbol<32>* to,
1156 const elfcpp::Sym<32, true>& sym,
1157 unsigned int st_shndx,
1159 unsigned int orig_st_shndx,
1161 const char* version,
1162 bool is_default_version);
1165 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
1168 Symbol_table::resolve<64, false>(
1169 Sized_symbol<64>* to,
1170 const elfcpp::Sym<64, false>& sym,
1171 unsigned int st_shndx,
1173 unsigned int orig_st_shndx,
1175 const char* version,
1176 bool is_default_version);
1180 Symbol_table::resolve<64, true>(
1181 Sized_symbol<64>* to,
1182 const elfcpp::Sym<64, true>& sym,
1183 unsigned int st_shndx,
1185 unsigned int orig_st_shndx,
1187 const char* version,
1188 bool is_default_version);
1191 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
1194 Symbol_table::override_with_special<32>(Sized_symbol<32>*,
1195 const Sized_symbol<32>*);
1198 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
1201 Symbol_table::override_with_special<64>(Sized_symbol<64>*,
1202 const Sized_symbol<64>*);
1207 Sized_symbol<32>::clone(const Sized_symbol<32>*);
1211 Sized_symbol<64>::clone(const Sized_symbol<64>*);
1212 } // End namespace gold.