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[binutils.git] / gold / resolve.cc
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1 // resolve.cc -- symbol resolution for gold
3 // Copyright 2006, 2007, 2008, 2009, 2010 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.
23 #include "gold.h"
25 #include "elfcpp.h"
26 #include "target.h"
27 #include "object.h"
28 #include "symtab.h"
29 #include "plugin.h"
31 namespace gold
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.
39 inline void
40 Symbol::override_version(const char* version)
42 if (version == NULL)
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;
54 else
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.
69 inline void
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>
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)
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;
109 // Override the fields in Sized_symbol.
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)
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();
123 // Override TOSYM with symbol FROMSYM, defined in OBJECT, with version
124 // VERSION. This handles all aliases of TOSYM.
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)
133 tosym->override(fromsym, st_shndx, is_ordinary, object, version);
134 if (tosym->has_alias())
136 Symbol* sym = this->weak_aliases_[tosym];
137 gold_assert(sym != NULL);
138 Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
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);
146 while (ssym != tosym);
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.
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;
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;
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;
169 // This convenience function combines all the flags based on facts
170 // about the symbol.
172 static unsigned int
173 symbol_to_bits(elfcpp::STB binding, bool is_dynamic,
174 unsigned int shndx, bool is_ordinary, elfcpp::STT type)
176 unsigned int bits;
178 switch (binding)
180 case elfcpp::STB_GLOBAL:
181 case elfcpp::STB_GNU_UNIQUE:
182 bits = global_flag;
183 break;
185 case elfcpp::STB_WEAK:
186 bits = weak_flag;
187 break;
189 case elfcpp::STB_LOCAL:
190 // We should only see externally visible symbols in the symbol
191 // table.
192 gold_error(_("invalid STB_LOCAL symbol in external symbols"));
193 bits = global_flag;
195 default:
196 // Any target which wants to handle STB_LOOS, etc., needs to
197 // define a resolve method.
198 gold_error(_("unsupported symbol binding"));
199 bits = global_flag;
202 if (is_dynamic)
203 bits |= dynamic_flag;
204 else
205 bits |= regular_flag;
207 switch (shndx)
209 case elfcpp::SHN_UNDEF:
210 bits |= undef_flag;
211 break;
213 case elfcpp::SHN_COMMON:
214 if (!is_ordinary)
215 bits |= common_flag;
216 break;
218 default:
219 if (type == elfcpp::STT_COMMON)
220 bits |= common_flag;
221 else if (!is_ordinary && Symbol::is_common_shndx(shndx))
222 bits |= common_flag;
223 else
224 bits |= def_flag;
225 break;
228 return bits;
231 // Resolve a symbol. This is called the second and subsequent times
232 // we see a symbol. TO is the pre-existing symbol. ST_SHNDX is the
233 // section index for SYM, possibly adjusted for many sections.
234 // IS_ORDINARY is whether ST_SHNDX is a normal section index rather
235 // than a special code. ORIG_ST_SHNDX is the original section index,
236 // before any munging because of discarded sections, except that all
237 // non-ordinary section indexes are mapped to SHN_UNDEF. VERSION is
238 // the version of SYM.
240 template<int size, bool big_endian>
241 void
242 Symbol_table::resolve(Sized_symbol<size>* to,
243 const elfcpp::Sym<size, big_endian>& sym,
244 unsigned int st_shndx, bool is_ordinary,
245 unsigned int orig_st_shndx,
246 Object* object, const char* version)
248 if (parameters->target().has_resolve())
250 Sized_target<size, big_endian>* sized_target;
251 sized_target = parameters->sized_target<size, big_endian>();
252 sized_target->resolve(to, sym, object, version);
253 return;
256 if (!object->is_dynamic())
258 // Record that we've seen this symbol in a regular object.
259 to->set_in_reg();
261 else if (st_shndx == elfcpp::SHN_UNDEF
262 && (to->visibility() == elfcpp::STV_HIDDEN
263 || to->visibility() == elfcpp::STV_INTERNAL))
265 // A dynamic object cannot reference a hidden or internal symbol
266 // defined in another object.
267 gold_warning(_("%s symbol '%s' in %s is referenced by DSO %s"),
268 (to->visibility() == elfcpp::STV_HIDDEN
269 ? "hidden"
270 : "internal"),
271 to->demangled_name().c_str(),
272 to->object()->name().c_str(),
273 object->name().c_str());
274 return;
276 else
278 // Record that we've seen this symbol in a dynamic object.
279 to->set_in_dyn();
282 // Record if we've seen this symbol in a real ELF object (i.e., the
283 // symbol is referenced from outside the world known to the plugin).
284 if (object->pluginobj() == NULL)
285 to->set_in_real_elf();
287 // If we're processing replacement files, allow new symbols to override
288 // the placeholders from the plugin objects.
289 if (to->source() == Symbol::FROM_OBJECT)
291 Pluginobj* obj = to->object()->pluginobj();
292 if (obj != NULL
293 && parameters->options().plugins()->in_replacement_phase())
295 this->override(to, sym, st_shndx, is_ordinary, object, version);
296 return;
300 // A new weak undefined reference, merging with an old weak
301 // reference, could be a One Definition Rule (ODR) violation --
302 // especially if the types or sizes of the references differ. We'll
303 // store such pairs and look them up later to make sure they
304 // actually refer to the same lines of code. We also check
305 // combinations of weak and strong, which might occur if one case is
306 // inline and the other is not. (Note: not all ODR violations can
307 // be found this way, and not everything this finds is an ODR
308 // violation. But it's helpful to warn about.)
309 bool to_is_ordinary;
310 if (parameters->options().detect_odr_violations()
311 && (sym.get_st_bind() == elfcpp::STB_WEAK
312 || to->binding() == elfcpp::STB_WEAK)
313 && orig_st_shndx != elfcpp::SHN_UNDEF
314 && to->shndx(&to_is_ordinary) != elfcpp::SHN_UNDEF
315 && to_is_ordinary
316 && sym.get_st_size() != 0 // Ignore weird 0-sized symbols.
317 && to->symsize() != 0
318 && (sym.get_st_type() != to->type()
319 || sym.get_st_size() != to->symsize())
320 // C does not have a concept of ODR, so we only need to do this
321 // on C++ symbols. These have (mangled) names starting with _Z.
322 && to->name()[0] == '_' && to->name()[1] == 'Z')
324 Symbol_location fromloc
325 = { object, orig_st_shndx, sym.get_st_value() };
326 Symbol_location toloc = { to->object(), to->shndx(&to_is_ordinary),
327 to->value() };
328 this->candidate_odr_violations_[to->name()].insert(fromloc);
329 this->candidate_odr_violations_[to->name()].insert(toloc);
332 unsigned int frombits = symbol_to_bits(sym.get_st_bind(),
333 object->is_dynamic(),
334 st_shndx, is_ordinary,
335 sym.get_st_type());
337 bool adjust_common_sizes;
338 bool adjust_dyndef;
339 typename Sized_symbol<size>::Size_type tosize = to->symsize();
340 if (Symbol_table::should_override(to, frombits, OBJECT, object,
341 &adjust_common_sizes,
342 &adjust_dyndef))
344 elfcpp::STB tobinding = to->binding();
345 this->override(to, sym, st_shndx, is_ordinary, object, version);
346 if (adjust_common_sizes && tosize > to->symsize())
347 to->set_symsize(tosize);
348 if (adjust_dyndef)
350 // We are overriding an UNDEF or WEAK UNDEF with a DYN DEF.
351 // Remember which kind of UNDEF it was for future reference.
352 to->set_undef_binding(tobinding);
355 else
357 if (adjust_common_sizes && sym.get_st_size() > tosize)
358 to->set_symsize(sym.get_st_size());
359 if (adjust_dyndef)
361 // We are keeping a DYN DEF after seeing an UNDEF or WEAK UNDEF.
362 // Remember which kind of UNDEF it was.
363 to->set_undef_binding(sym.get_st_bind());
365 // The ELF ABI says that even for a reference to a symbol we
366 // merge the visibility.
367 to->override_visibility(sym.get_st_visibility());
370 if (adjust_common_sizes && parameters->options().warn_common())
372 if (tosize > sym.get_st_size())
373 Symbol_table::report_resolve_problem(false,
374 _("common of '%s' overriding "
375 "smaller common"),
376 to, OBJECT, object);
377 else if (tosize < sym.get_st_size())
378 Symbol_table::report_resolve_problem(false,
379 _("common of '%s' overidden by "
380 "larger common"),
381 to, OBJECT, object);
382 else
383 Symbol_table::report_resolve_problem(false,
384 _("multiple common of '%s'"),
385 to, OBJECT, object);
389 // Handle the core of symbol resolution. This is called with the
390 // existing symbol, TO, and a bitflag describing the new symbol. This
391 // returns true if we should override the existing symbol with the new
392 // one, and returns false otherwise. It sets *ADJUST_COMMON_SIZES to
393 // true if we should set the symbol size to the maximum of the TO and
394 // FROM sizes. It handles error conditions.
396 bool
397 Symbol_table::should_override(const Symbol* to, unsigned int frombits,
398 Defined defined, Object* object,
399 bool* adjust_common_sizes,
400 bool* adjust_dyndef)
402 *adjust_common_sizes = false;
403 *adjust_dyndef = false;
405 unsigned int tobits;
406 if (to->source() == Symbol::IS_UNDEFINED)
407 tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_UNDEF, true,
408 to->type());
409 else if (to->source() != Symbol::FROM_OBJECT)
410 tobits = symbol_to_bits(to->binding(), false, elfcpp::SHN_ABS, false,
411 to->type());
412 else
414 bool is_ordinary;
415 unsigned int shndx = to->shndx(&is_ordinary);
416 tobits = symbol_to_bits(to->binding(),
417 to->object()->is_dynamic(),
418 shndx,
419 is_ordinary,
420 to->type());
423 // FIXME: Warn if either but not both of TO and SYM are STT_TLS.
425 // We use a giant switch table for symbol resolution. This code is
426 // unwieldy, but: 1) it is efficient; 2) we definitely handle all
427 // cases; 3) it is easy to change the handling of a particular case.
428 // The alternative would be a series of conditionals, but it is easy
429 // to get the ordering wrong. This could also be done as a table,
430 // but that is no easier to understand than this large switch
431 // statement.
433 // These are the values generated by the bit codes.
434 enum
436 DEF = global_flag | regular_flag | def_flag,
437 WEAK_DEF = weak_flag | regular_flag | def_flag,
438 DYN_DEF = global_flag | dynamic_flag | def_flag,
439 DYN_WEAK_DEF = weak_flag | dynamic_flag | def_flag,
440 UNDEF = global_flag | regular_flag | undef_flag,
441 WEAK_UNDEF = weak_flag | regular_flag | undef_flag,
442 DYN_UNDEF = global_flag | dynamic_flag | undef_flag,
443 DYN_WEAK_UNDEF = weak_flag | dynamic_flag | undef_flag,
444 COMMON = global_flag | regular_flag | common_flag,
445 WEAK_COMMON = weak_flag | regular_flag | common_flag,
446 DYN_COMMON = global_flag | dynamic_flag | common_flag,
447 DYN_WEAK_COMMON = weak_flag | dynamic_flag | common_flag
450 switch (tobits * 16 + frombits)
452 case DEF * 16 + DEF:
453 // Two definitions of the same symbol.
455 // If either symbol is defined by an object included using
456 // --just-symbols, then don't warn. This is for compatibility
457 // with the GNU linker. FIXME: This is a hack.
458 if ((to->source() == Symbol::FROM_OBJECT && to->object()->just_symbols())
459 || (object != NULL && object->just_symbols()))
460 return false;
462 if (!parameters->options().muldefs())
463 Symbol_table::report_resolve_problem(true,
464 _("multiple definition of '%s'"),
465 to, defined, object);
466 return false;
468 case WEAK_DEF * 16 + DEF:
469 // We've seen a weak definition, and now we see a strong
470 // definition. In the original SVR4 linker, this was treated as
471 // a multiple definition error. In the Solaris linker and the
472 // GNU linker, a weak definition followed by a regular
473 // definition causes the weak definition to be overridden. We
474 // are currently compatible with the GNU linker. In the future
475 // we should add a target specific option to change this.
476 // FIXME.
477 return true;
479 case DYN_DEF * 16 + DEF:
480 case DYN_WEAK_DEF * 16 + DEF:
481 // We've seen a definition in a dynamic object, and now we see a
482 // definition in a regular object. The definition in the
483 // regular object overrides the definition in the dynamic
484 // object.
485 return true;
487 case UNDEF * 16 + DEF:
488 case WEAK_UNDEF * 16 + DEF:
489 case DYN_UNDEF * 16 + DEF:
490 case DYN_WEAK_UNDEF * 16 + DEF:
491 // We've seen an undefined reference, and now we see a
492 // definition. We use the definition.
493 return true;
495 case COMMON * 16 + DEF:
496 case WEAK_COMMON * 16 + DEF:
497 case DYN_COMMON * 16 + DEF:
498 case DYN_WEAK_COMMON * 16 + DEF:
499 // We've seen a common symbol and now we see a definition. The
500 // definition overrides.
501 if (parameters->options().warn_common())
502 Symbol_table::report_resolve_problem(false,
503 _("definition of '%s' overriding "
504 "common"),
505 to, defined, object);
506 return true;
508 case DEF * 16 + WEAK_DEF:
509 case WEAK_DEF * 16 + WEAK_DEF:
510 // We've seen a definition and now we see a weak definition. We
511 // ignore the new weak definition.
512 return false;
514 case DYN_DEF * 16 + WEAK_DEF:
515 case DYN_WEAK_DEF * 16 + WEAK_DEF:
516 // We've seen a dynamic definition and now we see a regular weak
517 // definition. The regular weak definition overrides.
518 return true;
520 case UNDEF * 16 + WEAK_DEF:
521 case WEAK_UNDEF * 16 + WEAK_DEF:
522 case DYN_UNDEF * 16 + WEAK_DEF:
523 case DYN_WEAK_UNDEF * 16 + WEAK_DEF:
524 // A weak definition of a currently undefined symbol.
525 return true;
527 case COMMON * 16 + WEAK_DEF:
528 case WEAK_COMMON * 16 + WEAK_DEF:
529 // A weak definition does not override a common definition.
530 return false;
532 case DYN_COMMON * 16 + WEAK_DEF:
533 case DYN_WEAK_COMMON * 16 + WEAK_DEF:
534 // A weak definition does override a definition in a dynamic
535 // object.
536 if (parameters->options().warn_common())
537 Symbol_table::report_resolve_problem(false,
538 _("definition of '%s' overriding "
539 "dynamic common definition"),
540 to, defined, object);
541 return true;
543 case DEF * 16 + DYN_DEF:
544 case WEAK_DEF * 16 + DYN_DEF:
545 case DYN_DEF * 16 + DYN_DEF:
546 case DYN_WEAK_DEF * 16 + DYN_DEF:
547 // Ignore a dynamic definition if we already have a definition.
548 return false;
550 case UNDEF * 16 + DYN_DEF:
551 case DYN_UNDEF * 16 + DYN_DEF:
552 case DYN_WEAK_UNDEF * 16 + DYN_DEF:
553 // Use a dynamic definition if we have a reference.
554 return true;
556 case WEAK_UNDEF * 16 + DYN_DEF:
557 // When overriding a weak undef by a dynamic definition,
558 // we need to remember that the original undef was weak.
559 *adjust_dyndef = true;
560 return true;
562 case COMMON * 16 + DYN_DEF:
563 case WEAK_COMMON * 16 + DYN_DEF:
564 case DYN_COMMON * 16 + DYN_DEF:
565 case DYN_WEAK_COMMON * 16 + DYN_DEF:
566 // Ignore a dynamic definition if we already have a common
567 // definition.
568 return false;
570 case DEF * 16 + DYN_WEAK_DEF:
571 case WEAK_DEF * 16 + DYN_WEAK_DEF:
572 case DYN_DEF * 16 + DYN_WEAK_DEF:
573 case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF:
574 // Ignore a weak dynamic definition if we already have a
575 // definition.
576 return false;
578 case UNDEF * 16 + DYN_WEAK_DEF:
579 case DYN_UNDEF * 16 + DYN_WEAK_DEF:
580 case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF:
581 // Use a weak dynamic definition if we have a reference.
582 return true;
584 case WEAK_UNDEF * 16 + DYN_WEAK_DEF:
585 // When overriding a weak undef by a dynamic definition,
586 // we need to remember that the original undef was weak.
587 *adjust_dyndef = true;
588 return true;
590 case COMMON * 16 + DYN_WEAK_DEF:
591 case WEAK_COMMON * 16 + DYN_WEAK_DEF:
592 case DYN_COMMON * 16 + DYN_WEAK_DEF:
593 case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF:
594 // Ignore a weak dynamic definition if we already have a common
595 // definition.
596 return false;
598 case DEF * 16 + UNDEF:
599 case WEAK_DEF * 16 + UNDEF:
600 case UNDEF * 16 + UNDEF:
601 // A new undefined reference tells us nothing.
602 return false;
604 case DYN_DEF * 16 + UNDEF:
605 case DYN_WEAK_DEF * 16 + UNDEF:
606 // For a dynamic def, we need to remember which kind of undef we see.
607 *adjust_dyndef = true;
608 return false;
610 case WEAK_UNDEF * 16 + UNDEF:
611 case DYN_UNDEF * 16 + UNDEF:
612 case DYN_WEAK_UNDEF * 16 + UNDEF:
613 // A strong undef overrides a dynamic or weak undef.
614 return true;
616 case COMMON * 16 + UNDEF:
617 case WEAK_COMMON * 16 + UNDEF:
618 case DYN_COMMON * 16 + UNDEF:
619 case DYN_WEAK_COMMON * 16 + UNDEF:
620 // A new undefined reference tells us nothing.
621 return false;
623 case DEF * 16 + WEAK_UNDEF:
624 case WEAK_DEF * 16 + WEAK_UNDEF:
625 case UNDEF * 16 + WEAK_UNDEF:
626 case WEAK_UNDEF * 16 + WEAK_UNDEF:
627 case DYN_UNDEF * 16 + WEAK_UNDEF:
628 case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF:
629 case COMMON * 16 + WEAK_UNDEF:
630 case WEAK_COMMON * 16 + WEAK_UNDEF:
631 case DYN_COMMON * 16 + WEAK_UNDEF:
632 case DYN_WEAK_COMMON * 16 + WEAK_UNDEF:
633 // A new weak undefined reference tells us nothing.
634 return false;
636 case DYN_DEF * 16 + WEAK_UNDEF:
637 case DYN_WEAK_DEF * 16 + WEAK_UNDEF:
638 // For a dynamic def, we need to remember which kind of undef we see.
639 *adjust_dyndef = true;
640 return false;
642 case DEF * 16 + DYN_UNDEF:
643 case WEAK_DEF * 16 + DYN_UNDEF:
644 case DYN_DEF * 16 + DYN_UNDEF:
645 case DYN_WEAK_DEF * 16 + DYN_UNDEF:
646 case UNDEF * 16 + DYN_UNDEF:
647 case WEAK_UNDEF * 16 + DYN_UNDEF:
648 case DYN_UNDEF * 16 + DYN_UNDEF:
649 case DYN_WEAK_UNDEF * 16 + DYN_UNDEF:
650 case COMMON * 16 + DYN_UNDEF:
651 case WEAK_COMMON * 16 + DYN_UNDEF:
652 case DYN_COMMON * 16 + DYN_UNDEF:
653 case DYN_WEAK_COMMON * 16 + DYN_UNDEF:
654 // A new dynamic undefined reference tells us nothing.
655 return false;
657 case DEF * 16 + DYN_WEAK_UNDEF:
658 case WEAK_DEF * 16 + DYN_WEAK_UNDEF:
659 case DYN_DEF * 16 + DYN_WEAK_UNDEF:
660 case DYN_WEAK_DEF * 16 + DYN_WEAK_UNDEF:
661 case UNDEF * 16 + DYN_WEAK_UNDEF:
662 case WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
663 case DYN_UNDEF * 16 + DYN_WEAK_UNDEF:
664 case DYN_WEAK_UNDEF * 16 + DYN_WEAK_UNDEF:
665 case COMMON * 16 + DYN_WEAK_UNDEF:
666 case WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
667 case DYN_COMMON * 16 + DYN_WEAK_UNDEF:
668 case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF:
669 // A new weak dynamic undefined reference tells us nothing.
670 return false;
672 case DEF * 16 + COMMON:
673 // A common symbol does not override a definition.
674 if (parameters->options().warn_common())
675 Symbol_table::report_resolve_problem(false,
676 _("common '%s' overridden by "
677 "previous definition"),
678 to, defined, object);
679 return false;
681 case WEAK_DEF * 16 + COMMON:
682 case DYN_DEF * 16 + COMMON:
683 case DYN_WEAK_DEF * 16 + COMMON:
684 // A common symbol does override a weak definition or a dynamic
685 // definition.
686 return true;
688 case UNDEF * 16 + COMMON:
689 case WEAK_UNDEF * 16 + COMMON:
690 case DYN_UNDEF * 16 + COMMON:
691 case DYN_WEAK_UNDEF * 16 + COMMON:
692 // A common symbol is a definition for a reference.
693 return true;
695 case COMMON * 16 + COMMON:
696 // Set the size to the maximum.
697 *adjust_common_sizes = true;
698 return false;
700 case WEAK_COMMON * 16 + COMMON:
701 // I'm not sure just what a weak common symbol means, but
702 // presumably it can be overridden by a regular common symbol.
703 return true;
705 case DYN_COMMON * 16 + COMMON:
706 case DYN_WEAK_COMMON * 16 + COMMON:
707 // Use the real common symbol, but adjust the size if necessary.
708 *adjust_common_sizes = true;
709 return true;
711 case DEF * 16 + WEAK_COMMON:
712 case WEAK_DEF * 16 + WEAK_COMMON:
713 case DYN_DEF * 16 + WEAK_COMMON:
714 case DYN_WEAK_DEF * 16 + WEAK_COMMON:
715 // Whatever a weak common symbol is, it won't override a
716 // definition.
717 return false;
719 case UNDEF * 16 + WEAK_COMMON:
720 case WEAK_UNDEF * 16 + WEAK_COMMON:
721 case DYN_UNDEF * 16 + WEAK_COMMON:
722 case DYN_WEAK_UNDEF * 16 + WEAK_COMMON:
723 // A weak common symbol is better than an undefined symbol.
724 return true;
726 case COMMON * 16 + WEAK_COMMON:
727 case WEAK_COMMON * 16 + WEAK_COMMON:
728 case DYN_COMMON * 16 + WEAK_COMMON:
729 case DYN_WEAK_COMMON * 16 + WEAK_COMMON:
730 // Ignore a weak common symbol in the presence of a real common
731 // symbol.
732 return false;
734 case DEF * 16 + DYN_COMMON:
735 case WEAK_DEF * 16 + DYN_COMMON:
736 case DYN_DEF * 16 + DYN_COMMON:
737 case DYN_WEAK_DEF * 16 + DYN_COMMON:
738 // Ignore a dynamic common symbol in the presence of a
739 // definition.
740 return false;
742 case UNDEF * 16 + DYN_COMMON:
743 case WEAK_UNDEF * 16 + DYN_COMMON:
744 case DYN_UNDEF * 16 + DYN_COMMON:
745 case DYN_WEAK_UNDEF * 16 + DYN_COMMON:
746 // A dynamic common symbol is a definition of sorts.
747 return true;
749 case COMMON * 16 + DYN_COMMON:
750 case WEAK_COMMON * 16 + DYN_COMMON:
751 case DYN_COMMON * 16 + DYN_COMMON:
752 case DYN_WEAK_COMMON * 16 + DYN_COMMON:
753 // Set the size to the maximum.
754 *adjust_common_sizes = true;
755 return false;
757 case DEF * 16 + DYN_WEAK_COMMON:
758 case WEAK_DEF * 16 + DYN_WEAK_COMMON:
759 case DYN_DEF * 16 + DYN_WEAK_COMMON:
760 case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON:
761 // A common symbol is ignored in the face of a definition.
762 return false;
764 case UNDEF * 16 + DYN_WEAK_COMMON:
765 case WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
766 case DYN_UNDEF * 16 + DYN_WEAK_COMMON:
767 case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON:
768 // I guess a weak common symbol is better than a definition.
769 return true;
771 case COMMON * 16 + DYN_WEAK_COMMON:
772 case WEAK_COMMON * 16 + DYN_WEAK_COMMON:
773 case DYN_COMMON * 16 + DYN_WEAK_COMMON:
774 case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON:
775 // Set the size to the maximum.
776 *adjust_common_sizes = true;
777 return false;
779 default:
780 gold_unreachable();
784 // Issue an error or warning due to symbol resolution. IS_ERROR
785 // indicates an error rather than a warning. MSG is the error
786 // message; it is expected to have a %s for the symbol name. TO is
787 // the existing symbol. DEFINED/OBJECT is where the new symbol was
788 // found.
790 // FIXME: We should have better location information here. When the
791 // symbol is defined, we should be able to pull the location from the
792 // debug info if there is any.
794 void
795 Symbol_table::report_resolve_problem(bool is_error, const char* msg,
796 const Symbol* to, Defined defined,
797 Object* object)
799 std::string demangled(to->demangled_name());
800 size_t len = strlen(msg) + demangled.length() + 10;
801 char* buf = new char[len];
802 snprintf(buf, len, msg, demangled.c_str());
804 const char* objname;
805 switch (defined)
807 case OBJECT:
808 objname = object->name().c_str();
809 break;
810 case COPY:
811 objname = _("COPY reloc");
812 break;
813 case DEFSYM:
814 case UNDEFINED:
815 objname = _("command line");
816 break;
817 case SCRIPT:
818 objname = _("linker script");
819 break;
820 case PREDEFINED:
821 objname = _("linker defined");
822 break;
823 default:
824 gold_unreachable();
827 if (is_error)
828 gold_error("%s: %s", objname, buf);
829 else
830 gold_warning("%s: %s", objname, buf);
832 delete[] buf;
834 if (to->source() == Symbol::FROM_OBJECT)
835 objname = to->object()->name().c_str();
836 else
837 objname = _("command line");
838 gold_info("%s: %s: previous definition here", program_name, objname);
841 // A special case of should_override which is only called for a strong
842 // defined symbol from a regular object file. This is used when
843 // defining special symbols.
845 bool
846 Symbol_table::should_override_with_special(const Symbol* to, Defined defined)
848 bool adjust_common_sizes;
849 bool adjust_dyn_def;
850 unsigned int frombits = global_flag | regular_flag | def_flag;
851 bool ret = Symbol_table::should_override(to, frombits, defined, NULL,
852 &adjust_common_sizes,
853 &adjust_dyn_def);
854 gold_assert(!adjust_common_sizes && !adjust_dyn_def);
855 return ret;
858 // Override symbol base with a special symbol.
860 void
861 Symbol::override_base_with_special(const Symbol* from)
863 gold_assert(this->name_ == from->name_ || this->has_alias());
865 this->source_ = from->source_;
866 switch (from->source_)
868 case FROM_OBJECT:
869 this->u_.from_object = from->u_.from_object;
870 break;
871 case IN_OUTPUT_DATA:
872 this->u_.in_output_data = from->u_.in_output_data;
873 break;
874 case IN_OUTPUT_SEGMENT:
875 this->u_.in_output_segment = from->u_.in_output_segment;
876 break;
877 case IS_CONSTANT:
878 case IS_UNDEFINED:
879 break;
880 default:
881 gold_unreachable();
882 break;
885 this->override_version(from->version_);
886 this->type_ = from->type_;
887 this->binding_ = from->binding_;
888 this->override_visibility(from->visibility_);
889 this->nonvis_ = from->nonvis_;
891 // Special symbols are always considered to be regular symbols.
892 this->in_reg_ = true;
894 if (from->needs_dynsym_entry_)
895 this->needs_dynsym_entry_ = true;
896 if (from->needs_dynsym_value_)
897 this->needs_dynsym_value_ = true;
899 // We shouldn't see these flags. If we do, we need to handle them
900 // somehow.
901 gold_assert(!from->is_forwarder_);
902 gold_assert(!from->has_plt_offset());
903 gold_assert(!from->has_warning_);
904 gold_assert(!from->is_copied_from_dynobj_);
905 gold_assert(!from->is_forced_local_);
908 // Override a symbol with a special symbol.
910 template<int size>
911 void
912 Sized_symbol<size>::override_with_special(const Sized_symbol<size>* from)
914 this->override_base_with_special(from);
915 this->value_ = from->value_;
916 this->symsize_ = from->symsize_;
919 // Override TOSYM with the special symbol FROMSYM. This handles all
920 // aliases of TOSYM.
922 template<int size>
923 void
924 Symbol_table::override_with_special(Sized_symbol<size>* tosym,
925 const Sized_symbol<size>* fromsym)
927 tosym->override_with_special(fromsym);
928 if (tosym->has_alias())
930 Symbol* sym = this->weak_aliases_[tosym];
931 gold_assert(sym != NULL);
932 Sized_symbol<size>* ssym = this->get_sized_symbol<size>(sym);
935 ssym->override_with_special(fromsym);
936 sym = this->weak_aliases_[ssym];
937 gold_assert(sym != NULL);
938 ssym = this->get_sized_symbol<size>(sym);
940 while (ssym != tosym);
942 if (tosym->binding() == elfcpp::STB_LOCAL
943 || ((tosym->visibility() == elfcpp::STV_HIDDEN
944 || tosym->visibility() == elfcpp::STV_INTERNAL)
945 && (tosym->binding() == elfcpp::STB_GLOBAL
946 || tosym->binding() == elfcpp::STB_GNU_UNIQUE
947 || tosym->binding() == elfcpp::STB_WEAK)
948 && !parameters->options().relocatable()))
949 this->force_local(tosym);
952 // Instantiate the templates we need. We could use the configure
953 // script to restrict this to only the ones needed for implemented
954 // targets.
956 // We have to instantiate both big and little endian versions because
957 // these are used by other templates that depends on size only.
959 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
960 template
961 void
962 Symbol_table::resolve<32, false>(
963 Sized_symbol<32>* to,
964 const elfcpp::Sym<32, false>& sym,
965 unsigned int st_shndx,
966 bool is_ordinary,
967 unsigned int orig_st_shndx,
968 Object* object,
969 const char* version);
971 template
972 void
973 Symbol_table::resolve<32, true>(
974 Sized_symbol<32>* to,
975 const elfcpp::Sym<32, true>& sym,
976 unsigned int st_shndx,
977 bool is_ordinary,
978 unsigned int orig_st_shndx,
979 Object* object,
980 const char* version);
981 #endif
983 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
984 template
985 void
986 Symbol_table::resolve<64, false>(
987 Sized_symbol<64>* to,
988 const elfcpp::Sym<64, false>& sym,
989 unsigned int st_shndx,
990 bool is_ordinary,
991 unsigned int orig_st_shndx,
992 Object* object,
993 const char* version);
995 template
996 void
997 Symbol_table::resolve<64, true>(
998 Sized_symbol<64>* to,
999 const elfcpp::Sym<64, true>& sym,
1000 unsigned int st_shndx,
1001 bool is_ordinary,
1002 unsigned int orig_st_shndx,
1003 Object* object,
1004 const char* version);
1005 #endif
1007 #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_32_BIG)
1008 template
1009 void
1010 Symbol_table::override_with_special<32>(Sized_symbol<32>*,
1011 const Sized_symbol<32>*);
1012 #endif
1014 #if defined(HAVE_TARGET_64_LITTLE) || defined(HAVE_TARGET_64_BIG)
1015 template
1016 void
1017 Symbol_table::override_with_special<64>(Sized_symbol<64>*,
1018 const Sized_symbol<64>*);
1019 #endif
1021 } // End namespace gold.