Commit | Line | Data |
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14bfc3f5 ILT |
1 | // resolve.cc -- symbol resolution for gold |
2 | ||
3 | #include "gold.h" | |
4 | ||
5 | #include "elfcpp.h" | |
6 | #include "target.h" | |
7 | #include "object.h" | |
8 | #include "symtab.h" | |
9 | ||
10 | namespace gold | |
11 | { | |
12 | ||
1564db8d ILT |
13 | // Symbol methods used in this file. |
14 | ||
15 | // Override the fields in Symbol. | |
16 | ||
17 | template<int size, bool big_endian> | |
18 | void | |
19 | Symbol::override_base(const elfcpp::Sym<size, big_endian>& sym, | |
20 | Object* object) | |
21 | { | |
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(); | |
28 | } | |
29 | ||
30 | // Override the fields in Sized_symbol. | |
31 | ||
32 | template<int size> | |
33 | template<bool big_endian> | |
34 | void | |
35 | Sized_symbol<size>::override(const elfcpp::Sym<size, big_endian>& sym, | |
36 | Object* object) | |
37 | { | |
38 | this->override_base(sym, object); | |
39 | this->value_ = sym.get_st_value(); | |
40 | this->size_ = sym.get_st_size(); | |
41 | } | |
42 | ||
14bfc3f5 ILT |
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. | |
46 | ||
47 | template<int size, bool big_endian> | |
48 | void | |
1564db8d | 49 | Symbol_table::resolve(Sized_symbol<size>* to, |
14bfc3f5 ILT |
50 | const elfcpp::Sym<size, big_endian>& sym, |
51 | Object* object) | |
52 | { | |
53 | if (object->target()->has_resolve()) | |
54 | { | |
274e99f9 ILT |
55 | Sized_target<size, big_endian>* sized_target; |
56 | #ifdef HAVE_MEMBER_TEMPLATE_SPECIFICATIONS | |
57 | sized_target = object->sized_target<size, big_endian>(); | |
58 | #else | |
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); | |
63 | #endif | |
64 | sized_target->resolve(to, sym, object); | |
14bfc3f5 ILT |
65 | return; |
66 | } | |
67 | ||
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: | |
73 | ||
74 | enum | |
75 | { | |
76 | DEF = 0, | |
77 | WEAK_DEF = 1, | |
78 | DYN_DEF = 2, | |
79 | DYN_WEAK_DEF = 3, | |
80 | UNDEF = 4, | |
81 | WEAK_UNDEF = 5, | |
82 | DYN_UNDEF = 6, | |
83 | DYN_WEAK_UNDEF = 7, | |
84 | COMMON = 8, | |
85 | WEAK_COMMON = 9, | |
86 | DYN_COMMON = 10, | |
87 | DYN_WEAK_COMMON = 11 | |
88 | }; | |
89 | ||
90 | int tobits; | |
91 | switch (to->binding()) | |
92 | { | |
93 | case elfcpp::STB_GLOBAL: | |
94 | tobits = 0; | |
95 | break; | |
96 | ||
97 | case elfcpp::STB_WEAK: | |
98 | tobits = 1; | |
99 | break; | |
100 | ||
101 | case elfcpp::STB_LOCAL: | |
102 | // We should only see externally visible symbols in the symbol | |
103 | // table. | |
104 | abort(); | |
105 | ||
106 | default: | |
107 | // Any target which wants to handle STB_LOOS, etc., needs to | |
108 | // define a resolve method. | |
109 | abort(); | |
110 | } | |
111 | ||
112 | if (to->object() != NULL && to->object()->is_dynamic()) | |
113 | tobits |= (1 << 1); | |
114 | ||
115 | switch (to->shnum()) | |
116 | { | |
117 | case elfcpp::SHN_UNDEF: | |
118 | tobits |= (1 << 2); | |
119 | break; | |
120 | ||
121 | case elfcpp::SHN_COMMON: | |
122 | tobits |= (2 << 2); | |
123 | break; | |
124 | ||
125 | default: | |
1564db8d ILT |
126 | if (to->type() == elfcpp::STT_COMMON) |
127 | tobits |= (2 << 2); | |
14bfc3f5 ILT |
128 | break; |
129 | } | |
130 | ||
131 | int frombits; | |
132 | switch (sym.get_st_bind()) | |
133 | { | |
134 | case elfcpp::STB_GLOBAL: | |
135 | frombits = 0; | |
136 | break; | |
137 | ||
138 | case elfcpp::STB_WEAK: | |
139 | frombits = 1; | |
140 | break; | |
141 | ||
142 | case elfcpp::STB_LOCAL: | |
143 | fprintf(stderr, | |
144 | _("%s: %s: invalid STB_LOCAL symbol %s in external symbols\n"), | |
145 | program_name, object->name().c_str(), to->name()); | |
146 | gold_exit(false); | |
147 | ||
148 | default: | |
149 | fprintf(stderr, | |
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()); | |
153 | gold_exit(false); | |
154 | } | |
155 | ||
156 | if (object->is_dynamic()) | |
1564db8d ILT |
157 | { |
158 | frombits |= (1 << 1); | |
159 | ||
160 | // Record that we've seen this symbol in a dynamic object. | |
161 | to->set_in_dyn(); | |
162 | } | |
14bfc3f5 ILT |
163 | |
164 | switch (sym.get_st_shndx()) | |
165 | { | |
166 | case elfcpp::SHN_UNDEF: | |
167 | frombits |= (1 << 2); | |
168 | break; | |
169 | ||
170 | case elfcpp::SHN_COMMON: | |
171 | frombits |= (2 << 2); | |
172 | break; | |
173 | ||
174 | default: | |
1564db8d ILT |
175 | if (sym.get_st_type() == elfcpp::STT_COMMON) |
176 | frombits |= (2 << 2); | |
14bfc3f5 ILT |
177 | break; |
178 | } | |
179 | ||
1564db8d ILT |
180 | // FIXME: Warn if either but not both of TO and SYM are STT_TLS. |
181 | ||
14bfc3f5 ILT |
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 | |
188 | // statement. | |
189 | ||
190 | switch (tobits * 16 + frombits) | |
191 | { | |
192 | case DEF * 16 + DEF: | |
61ba1cf9 ILT |
193 | // Two definitions of the same symbol. We can't give an error |
194 | // here, because we have not yet discarded linkonce and comdat | |
195 | // sections. FIXME. | |
14bfc3f5 ILT |
196 | return; |
197 | ||
198 | case WEAK_DEF * 16 + DEF: | |
1564db8d ILT |
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. | |
206 | // FIXME. | |
207 | to->override(sym, object); | |
14bfc3f5 ILT |
208 | return; |
209 | ||
210 | case DYN_DEF * 16 + DEF: | |
211 | case DYN_WEAK_DEF * 16 + DEF: | |
1564db8d ILT |
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 | |
215 | // object. | |
216 | to->override(sym, object); | |
217 | return; | |
218 | ||
14bfc3f5 ILT |
219 | case UNDEF * 16 + DEF: |
220 | case WEAK_UNDEF * 16 + DEF: | |
221 | case DYN_UNDEF * 16 + DEF: | |
222 | case DYN_WEAK_UNDEF * 16 + DEF: | |
1564db8d ILT |
223 | // We've seen an undefined reference, and now we see a |
224 | // definition. We use the definition. | |
225 | to->override(sym, object); | |
226 | return; | |
227 | ||
14bfc3f5 ILT |
228 | case COMMON * 16 + DEF: |
229 | case WEAK_COMMON * 16 + DEF: | |
230 | case DYN_COMMON * 16 + DEF: | |
231 | case DYN_WEAK_COMMON * 16 + DEF: | |
1564db8d ILT |
232 | // We've seen a common symbol and now we see a definition. The |
233 | // definition overrides. FIXME: We should optionally issue a | |
234 | // warning. | |
235 | to->override(sym, object); | |
236 | return; | |
14bfc3f5 ILT |
237 | |
238 | case DEF * 16 + WEAK_DEF: | |
239 | case WEAK_DEF * 16 + WEAK_DEF: | |
1564db8d ILT |
240 | // We've seen a definition and now we see a weak definition. We |
241 | // ignore the new weak definition. | |
242 | return; | |
243 | ||
14bfc3f5 ILT |
244 | case DYN_DEF * 16 + WEAK_DEF: |
245 | case DYN_WEAK_DEF * 16 + WEAK_DEF: | |
1564db8d ILT |
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); | |
249 | return; | |
250 | ||
14bfc3f5 ILT |
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: | |
1564db8d ILT |
255 | // A weak definition of a currently undefined symbol. |
256 | to->override(sym, object); | |
257 | return; | |
258 | ||
14bfc3f5 ILT |
259 | case COMMON * 16 + WEAK_DEF: |
260 | case WEAK_COMMON * 16 + WEAK_DEF: | |
1564db8d ILT |
261 | // A weak definition does not override a common definition. |
262 | return; | |
263 | ||
14bfc3f5 ILT |
264 | case DYN_COMMON * 16 + WEAK_DEF: |
265 | case DYN_WEAK_COMMON * 16 + WEAK_DEF: | |
1564db8d ILT |
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); | |
269 | return; | |
14bfc3f5 ILT |
270 | |
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: | |
1564db8d ILT |
275 | // Ignore a dynamic definition if we already have a definition. |
276 | return; | |
277 | ||
14bfc3f5 ILT |
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: | |
1564db8d ILT |
282 | // Use a dynamic definition if we have a reference. |
283 | to->override(sym, object); | |
284 | return; | |
285 | ||
14bfc3f5 ILT |
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: | |
1564db8d ILT |
290 | // Ignore a dynamic definition if we already have a common |
291 | // definition. | |
292 | return; | |
14bfc3f5 ILT |
293 | |
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: | |
1564db8d ILT |
298 | // Ignore a weak dynamic definition if we already have a |
299 | // definition. | |
300 | return; | |
301 | ||
14bfc3f5 ILT |
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: | |
1564db8d ILT |
306 | // Use a weak dynamic definition if we have a reference. |
307 | to->override(sym, object); | |
308 | return; | |
309 | ||
14bfc3f5 ILT |
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: | |
1564db8d ILT |
314 | // Ignore a weak dynamic definition if we already have a common |
315 | // definition. | |
316 | return; | |
14bfc3f5 ILT |
317 | |
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: | |
1564db8d ILT |
330 | // A new undefined reference tells us nothing. |
331 | return; | |
14bfc3f5 ILT |
332 | |
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: | |
1564db8d ILT |
345 | // A new weak undefined reference tells us nothing. |
346 | return; | |
14bfc3f5 ILT |
347 | |
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: | |
1564db8d ILT |
360 | // A new dynamic undefined reference tells us nothing. |
361 | return; | |
14bfc3f5 ILT |
362 | |
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: | |
1564db8d ILT |
375 | // A new weak dynamic undefined reference tells us nothing. |
376 | return; | |
14bfc3f5 ILT |
377 | |
378 | case DEF * 16 + COMMON: | |
1564db8d ILT |
379 | // A common symbol does not override a definition. |
380 | return; | |
381 | ||
14bfc3f5 ILT |
382 | case WEAK_DEF * 16 + COMMON: |
383 | case DYN_DEF * 16 + COMMON: | |
384 | case DYN_WEAK_DEF * 16 + COMMON: | |
1564db8d ILT |
385 | // A common symbol does override a weak definition or a dynamic |
386 | // definition. | |
387 | to->override(sym, object); | |
388 | return; | |
389 | ||
14bfc3f5 ILT |
390 | case UNDEF * 16 + COMMON: |
391 | case WEAK_UNDEF * 16 + COMMON: | |
392 | case DYN_UNDEF * 16 + COMMON: | |
393 | case DYN_WEAK_UNDEF * 16 + COMMON: | |
1564db8d ILT |
394 | // A common symbol is a definition for a reference. |
395 | to->override(sym, object); | |
396 | return; | |
397 | ||
14bfc3f5 ILT |
398 | case COMMON * 16 + COMMON: |
399 | case WEAK_COMMON * 16 + COMMON: | |
400 | case DYN_COMMON * 16 + COMMON: | |
401 | case DYN_WEAK_COMMON * 16 + COMMON: | |
402 | ||
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: | |
415 | ||
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: | |
428 | ||
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: | |
1564db8d | 441 | abort(); |
14bfc3f5 | 442 | break; |
1564db8d ILT |
443 | |
444 | default: | |
445 | abort(); | |
14bfc3f5 ILT |
446 | } |
447 | } | |
448 | ||
449 | // Instantiate the templates we need. We could use the configure | |
450 | // script to restrict this to only the ones needed for implemented | |
451 | // targets. | |
452 | ||
453 | template | |
454 | void | |
455 | Symbol_table::resolve<32, true>( | |
1564db8d | 456 | Sized_symbol<32>* to, |
14bfc3f5 ILT |
457 | const elfcpp::Sym<32, true>& sym, |
458 | Object* object); | |
459 | ||
460 | template | |
461 | void | |
462 | Symbol_table::resolve<32, false>( | |
1564db8d | 463 | Sized_symbol<32>* to, |
14bfc3f5 ILT |
464 | const elfcpp::Sym<32, false>& sym, |
465 | Object* object); | |
466 | ||
467 | template | |
468 | void | |
469 | Symbol_table::resolve<64, true>( | |
1564db8d | 470 | Sized_symbol<64>* to, |
14bfc3f5 ILT |
471 | const elfcpp::Sym<64, true>& sym, |
472 | Object* object); | |
473 | ||
474 | template | |
475 | void | |
476 | Symbol_table::resolve<64, false>( | |
1564db8d | 477 | Sized_symbol<64>* to, |
14bfc3f5 ILT |
478 | const elfcpp::Sym<64, false>& sym, |
479 | Object* object); | |
480 | ||
481 | } // End namespace gold. |