669fbaf232ea153d6de4899e07f10a95176b2895
1 // resolve.cc -- symbol resolution for gold
13 // Symbol methods used in this file.
15 // Override the fields in Symbol.
17 template<int size
, bool big_endian
>
19 Symbol::override_base(const elfcpp::Sym
<size
, big_endian
>& sym
,
22 this->object_
= object
;
23 this->shnum_
= sym
.get_st_shndx(); // FIXME: Handle SHN_XINDEX.
24 this->type_
= sym
.get_st_type();
25 this->binding_
= sym
.get_st_bind();
26 this->visibility_
= sym
.get_st_visibility();
27 this->other_
= sym
.get_st_nonvis();
30 // Override the fields in Sized_symbol.
33 template<bool big_endian
>
35 Sized_symbol
<size
>::override(const elfcpp::Sym
<size
, big_endian
>& sym
,
38 this->override_base(sym
, object
);
39 this->value_
= sym
.get_st_value();
40 this->size_
= sym
.get_st_size();
43 // Resolve a symbol. This is called the second and subsequent times
44 // we see a symbol. TO is the pre-existing symbol. SYM is the new
45 // symbol, seen in OBJECT.
47 template<int size
, bool big_endian
>
49 Symbol_table::resolve(Sized_symbol
<size
>* to
,
50 const elfcpp::Sym
<size
, big_endian
>& sym
,
53 if (object
->target()->has_resolve())
55 Sized_target
<size
, big_endian
>* sized_target
;
56 #ifdef HAVE_MEMBER_TEMPLATE_SPECIFICATIONS
57 sized_target
= object
->sized_target
<size
, big_endian
>();
59 Target
* target
= object
->target();
60 assert(target
->get_size() == size
);
61 assert(target
->is_big_endian() ? big_endian
: !big_endian
);
62 sized_target
= static_cast<Sized_target
<size
, big_endian
>*>(target
);
64 sized_target
->resolve(to
, sym
, object
);
68 // Build a little code for each symbol.
69 // Bit 0: 0 for global, 1 for weak.
70 // Bit 1: 0 for regular object, 1 for shared object
71 // Bits 2-3: 0 for normal, 1 for undefined, 2 for common
72 // This gives us values from 0 to 11:
91 switch (to
->binding())
93 case elfcpp::STB_GLOBAL
:
97 case elfcpp::STB_WEAK
:
101 case elfcpp::STB_LOCAL
:
102 // We should only see externally visible symbols in the symbol
107 // Any target which wants to handle STB_LOOS, etc., needs to
108 // define a resolve method.
112 if (to
->object() != NULL
&& to
->object()->is_dynamic())
117 case elfcpp::SHN_UNDEF
:
121 case elfcpp::SHN_COMMON
:
126 if (to
->type() == elfcpp::STT_COMMON
)
132 switch (sym
.get_st_bind())
134 case elfcpp::STB_GLOBAL
:
138 case elfcpp::STB_WEAK
:
142 case elfcpp::STB_LOCAL
:
144 _("%s: %s: invalid STB_LOCAL symbol %s in external symbols\n"),
145 program_name
, object
->name().c_str(), to
->name());
150 _("%s: %s: unsupported symbol binding %d for symbol %s\n"),
151 program_name
, object
->name().c_str(),
152 static_cast<int>(sym
.get_st_bind()), to
->name());
156 if (object
->is_dynamic())
158 frombits
|= (1 << 1);
160 // Record that we've seen this symbol in a dynamic object.
164 switch (sym
.get_st_shndx())
166 case elfcpp::SHN_UNDEF
:
167 frombits
|= (1 << 2);
170 case elfcpp::SHN_COMMON
:
171 frombits
|= (2 << 2);
175 if (sym
.get_st_type() == elfcpp::STT_COMMON
)
176 frombits
|= (2 << 2);
180 // FIXME: Warn if either but not both of TO and SYM are STT_TLS.
182 // We use a giant switch table for symbol resolution. This code is
183 // unwieldy, but: 1) it is efficient; 2) we definitely handle all
184 // cases; 3) it is easy to change the handling of a particular case.
185 // The alternative would be a series of conditionals, but it is easy
186 // to get the ordering wrong. This could also be done as a table,
187 // but that is no easier to understand than this large switch
190 switch (tobits
* 16 + frombits
)
193 // Two definitions of the same symbol. We can't give an error
194 // here, because we have not yet discarded linkonce and comdat
198 case WEAK_DEF
* 16 + DEF
:
199 // We've seen a weak definition, and now we see a strong
200 // definition. In the original SVR4 linker, this was treated as
201 // a multiple definition error. In the Solaris linker and the
202 // GNU linker, a weak definition followed by a regular
203 // definition causes the weak definition to be overridden. We
204 // are currently compatible with the GNU linker. In the future
205 // we should add a target specific option to change this.
207 to
->override(sym
, object
);
210 case DYN_DEF
* 16 + DEF
:
211 case DYN_WEAK_DEF
* 16 + DEF
:
212 // We've seen a definition in a dynamic object, and now we see a
213 // definition in a regular object. The definition in the
214 // regular object overrides the definition in the dynamic
216 to
->override(sym
, object
);
219 case UNDEF
* 16 + DEF
:
220 case WEAK_UNDEF
* 16 + DEF
:
221 case DYN_UNDEF
* 16 + DEF
:
222 case DYN_WEAK_UNDEF
* 16 + DEF
:
223 // We've seen an undefined reference, and now we see a
224 // definition. We use the definition.
225 to
->override(sym
, object
);
228 case COMMON
* 16 + DEF
:
229 case WEAK_COMMON
* 16 + DEF
:
230 case DYN_COMMON
* 16 + DEF
:
231 case DYN_WEAK_COMMON
* 16 + DEF
:
232 // We've seen a common symbol and now we see a definition. The
233 // definition overrides. FIXME: We should optionally issue a
235 to
->override(sym
, object
);
238 case DEF
* 16 + WEAK_DEF
:
239 case WEAK_DEF
* 16 + WEAK_DEF
:
240 // We've seen a definition and now we see a weak definition. We
241 // ignore the new weak definition.
244 case DYN_DEF
* 16 + WEAK_DEF
:
245 case DYN_WEAK_DEF
* 16 + WEAK_DEF
:
246 // We've seen a dynamic definition and now we see a regular weak
247 // definition. The regular weak definition overrides.
248 to
->override(sym
, object
);
251 case UNDEF
* 16 + WEAK_DEF
:
252 case WEAK_UNDEF
* 16 + WEAK_DEF
:
253 case DYN_UNDEF
* 16 + WEAK_DEF
:
254 case DYN_WEAK_UNDEF
* 16 + WEAK_DEF
:
255 // A weak definition of a currently undefined symbol.
256 to
->override(sym
, object
);
259 case COMMON
* 16 + WEAK_DEF
:
260 case WEAK_COMMON
* 16 + WEAK_DEF
:
261 // A weak definition does not override a common definition.
264 case DYN_COMMON
* 16 + WEAK_DEF
:
265 case DYN_WEAK_COMMON
* 16 + WEAK_DEF
:
266 // A weak definition does override a definition in a dynamic
267 // object. FIXME: We should optionally issue a warning.
268 to
->override(sym
, object
);
271 case DEF
* 16 + DYN_DEF
:
272 case WEAK_DEF
* 16 + DYN_DEF
:
273 case DYN_DEF
* 16 + DYN_DEF
:
274 case DYN_WEAK_DEF
* 16 + DYN_DEF
:
275 // Ignore a dynamic definition if we already have a definition.
278 case UNDEF
* 16 + DYN_DEF
:
279 case WEAK_UNDEF
* 16 + DYN_DEF
:
280 case DYN_UNDEF
* 16 + DYN_DEF
:
281 case DYN_WEAK_UNDEF
* 16 + DYN_DEF
:
282 // Use a dynamic definition if we have a reference.
283 to
->override(sym
, object
);
286 case COMMON
* 16 + DYN_DEF
:
287 case WEAK_COMMON
* 16 + DYN_DEF
:
288 case DYN_COMMON
* 16 + DYN_DEF
:
289 case DYN_WEAK_COMMON
* 16 + DYN_DEF
:
290 // Ignore a dynamic definition if we already have a common
294 case DEF
* 16 + DYN_WEAK_DEF
:
295 case WEAK_DEF
* 16 + DYN_WEAK_DEF
:
296 case DYN_DEF
* 16 + DYN_WEAK_DEF
:
297 case DYN_WEAK_DEF
* 16 + DYN_WEAK_DEF
:
298 // Ignore a weak dynamic definition if we already have a
302 case UNDEF
* 16 + DYN_WEAK_DEF
:
303 case WEAK_UNDEF
* 16 + DYN_WEAK_DEF
:
304 case DYN_UNDEF
* 16 + DYN_WEAK_DEF
:
305 case DYN_WEAK_UNDEF
* 16 + DYN_WEAK_DEF
:
306 // Use a weak dynamic definition if we have a reference.
307 to
->override(sym
, object
);
310 case COMMON
* 16 + DYN_WEAK_DEF
:
311 case WEAK_COMMON
* 16 + DYN_WEAK_DEF
:
312 case DYN_COMMON
* 16 + DYN_WEAK_DEF
:
313 case DYN_WEAK_COMMON
* 16 + DYN_WEAK_DEF
:
314 // Ignore a weak dynamic definition if we already have a common
318 case DEF
* 16 + UNDEF
:
319 case WEAK_DEF
* 16 + UNDEF
:
320 case DYN_DEF
* 16 + UNDEF
:
321 case DYN_WEAK_DEF
* 16 + UNDEF
:
322 case UNDEF
* 16 + UNDEF
:
323 case WEAK_UNDEF
* 16 + UNDEF
:
324 case DYN_UNDEF
* 16 + UNDEF
:
325 case DYN_WEAK_UNDEF
* 16 + UNDEF
:
326 case COMMON
* 16 + UNDEF
:
327 case WEAK_COMMON
* 16 + UNDEF
:
328 case DYN_COMMON
* 16 + UNDEF
:
329 case DYN_WEAK_COMMON
* 16 + UNDEF
:
330 // A new undefined reference tells us nothing.
333 case DEF
* 16 + WEAK_UNDEF
:
334 case WEAK_DEF
* 16 + WEAK_UNDEF
:
335 case DYN_DEF
* 16 + WEAK_UNDEF
:
336 case DYN_WEAK_DEF
* 16 + WEAK_UNDEF
:
337 case UNDEF
* 16 + WEAK_UNDEF
:
338 case WEAK_UNDEF
* 16 + WEAK_UNDEF
:
339 case DYN_UNDEF
* 16 + WEAK_UNDEF
:
340 case DYN_WEAK_UNDEF
* 16 + WEAK_UNDEF
:
341 case COMMON
* 16 + WEAK_UNDEF
:
342 case WEAK_COMMON
* 16 + WEAK_UNDEF
:
343 case DYN_COMMON
* 16 + WEAK_UNDEF
:
344 case DYN_WEAK_COMMON
* 16 + WEAK_UNDEF
:
345 // A new weak undefined reference tells us nothing.
348 case DEF
* 16 + DYN_UNDEF
:
349 case WEAK_DEF
* 16 + DYN_UNDEF
:
350 case DYN_DEF
* 16 + DYN_UNDEF
:
351 case DYN_WEAK_DEF
* 16 + DYN_UNDEF
:
352 case UNDEF
* 16 + DYN_UNDEF
:
353 case WEAK_UNDEF
* 16 + DYN_UNDEF
:
354 case DYN_UNDEF
* 16 + DYN_UNDEF
:
355 case DYN_WEAK_UNDEF
* 16 + DYN_UNDEF
:
356 case COMMON
* 16 + DYN_UNDEF
:
357 case WEAK_COMMON
* 16 + DYN_UNDEF
:
358 case DYN_COMMON
* 16 + DYN_UNDEF
:
359 case DYN_WEAK_COMMON
* 16 + DYN_UNDEF
:
360 // A new dynamic undefined reference tells us nothing.
363 case DEF
* 16 + DYN_WEAK_UNDEF
:
364 case WEAK_DEF
* 16 + DYN_WEAK_UNDEF
:
365 case DYN_DEF
* 16 + DYN_WEAK_UNDEF
:
366 case DYN_WEAK_DEF
* 16 + DYN_WEAK_UNDEF
:
367 case UNDEF
* 16 + DYN_WEAK_UNDEF
:
368 case WEAK_UNDEF
* 16 + DYN_WEAK_UNDEF
:
369 case DYN_UNDEF
* 16 + DYN_WEAK_UNDEF
:
370 case DYN_WEAK_UNDEF
* 16 + DYN_WEAK_UNDEF
:
371 case COMMON
* 16 + DYN_WEAK_UNDEF
:
372 case WEAK_COMMON
* 16 + DYN_WEAK_UNDEF
:
373 case DYN_COMMON
* 16 + DYN_WEAK_UNDEF
:
374 case DYN_WEAK_COMMON
* 16 + DYN_WEAK_UNDEF
:
375 // A new weak dynamic undefined reference tells us nothing.
378 case DEF
* 16 + COMMON
:
379 // A common symbol does not override a definition.
382 case WEAK_DEF
* 16 + COMMON
:
383 case DYN_DEF
* 16 + COMMON
:
384 case DYN_WEAK_DEF
* 16 + COMMON
:
385 // A common symbol does override a weak definition or a dynamic
387 to
->override(sym
, object
);
390 case UNDEF
* 16 + COMMON
:
391 case WEAK_UNDEF
* 16 + COMMON
:
392 case DYN_UNDEF
* 16 + COMMON
:
393 case DYN_WEAK_UNDEF
* 16 + COMMON
:
394 // A common symbol is a definition for a reference.
395 to
->override(sym
, object
);
398 case COMMON
* 16 + COMMON
:
399 case WEAK_COMMON
* 16 + COMMON
:
400 case DYN_COMMON
* 16 + COMMON
:
401 case DYN_WEAK_COMMON
* 16 + COMMON
:
403 case DEF
* 16 + WEAK_COMMON
:
404 case WEAK_DEF
* 16 + WEAK_COMMON
:
405 case DYN_DEF
* 16 + WEAK_COMMON
:
406 case DYN_WEAK_DEF
* 16 + WEAK_COMMON
:
407 case UNDEF
* 16 + WEAK_COMMON
:
408 case WEAK_UNDEF
* 16 + WEAK_COMMON
:
409 case DYN_UNDEF
* 16 + WEAK_COMMON
:
410 case DYN_WEAK_UNDEF
* 16 + WEAK_COMMON
:
411 case COMMON
* 16 + WEAK_COMMON
:
412 case WEAK_COMMON
* 16 + WEAK_COMMON
:
413 case DYN_COMMON
* 16 + WEAK_COMMON
:
414 case DYN_WEAK_COMMON
* 16 + WEAK_COMMON
:
416 case DEF
* 16 + DYN_COMMON
:
417 case WEAK_DEF
* 16 + DYN_COMMON
:
418 case DYN_DEF
* 16 + DYN_COMMON
:
419 case DYN_WEAK_DEF
* 16 + DYN_COMMON
:
420 case UNDEF
* 16 + DYN_COMMON
:
421 case WEAK_UNDEF
* 16 + DYN_COMMON
:
422 case DYN_UNDEF
* 16 + DYN_COMMON
:
423 case DYN_WEAK_UNDEF
* 16 + DYN_COMMON
:
424 case COMMON
* 16 + DYN_COMMON
:
425 case WEAK_COMMON
* 16 + DYN_COMMON
:
426 case DYN_COMMON
* 16 + DYN_COMMON
:
427 case DYN_WEAK_COMMON
* 16 + DYN_COMMON
:
429 case DEF
* 16 + DYN_WEAK_COMMON
:
430 case WEAK_DEF
* 16 + DYN_WEAK_COMMON
:
431 case DYN_DEF
* 16 + DYN_WEAK_COMMON
:
432 case DYN_WEAK_DEF
* 16 + DYN_WEAK_COMMON
:
433 case UNDEF
* 16 + DYN_WEAK_COMMON
:
434 case WEAK_UNDEF
* 16 + DYN_WEAK_COMMON
:
435 case DYN_UNDEF
* 16 + DYN_WEAK_COMMON
:
436 case DYN_WEAK_UNDEF
* 16 + DYN_WEAK_COMMON
:
437 case COMMON
* 16 + DYN_WEAK_COMMON
:
438 case WEAK_COMMON
* 16 + DYN_WEAK_COMMON
:
439 case DYN_COMMON
* 16 + DYN_WEAK_COMMON
:
440 case DYN_WEAK_COMMON
* 16 + DYN_WEAK_COMMON
:
449 // Instantiate the templates we need. We could use the configure
450 // script to restrict this to only the ones needed for implemented
455 Symbol_table::resolve
<32, true>(
456 Sized_symbol
<32>* to
,
457 const elfcpp::Sym
<32, true>& sym
,
462 Symbol_table::resolve
<32, false>(
463 Sized_symbol
<32>* to
,
464 const elfcpp::Sym
<32, false>& sym
,
469 Symbol_table::resolve
<64, true>(
470 Sized_symbol
<64>* to
,
471 const elfcpp::Sym
<64, true>& sym
,
476 Symbol_table::resolve
<64, false>(
477 Sized_symbol
<64>* to
,
478 const elfcpp::Sym
<64, false>& sym
,
481 } // End namespace gold.
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