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 | 55 | Sized_target<size, big_endian>* sized_target; |
5482377d ILT |
56 | sized_target = object->sized_target SELECT_SIZE_ENDIAN_NAME ( |
57 | SELECT_SIZE_ENDIAN_ONLY(size, big_endian)); | |
274e99f9 | 58 | sized_target->resolve(to, sym, object); |
14bfc3f5 ILT |
59 | return; |
60 | } | |
61 | ||
62 | // Build a little code for each symbol. | |
63 | // Bit 0: 0 for global, 1 for weak. | |
64 | // Bit 1: 0 for regular object, 1 for shared object | |
65 | // Bits 2-3: 0 for normal, 1 for undefined, 2 for common | |
66 | // This gives us values from 0 to 11: | |
67 | ||
68 | enum | |
69 | { | |
70 | DEF = 0, | |
71 | WEAK_DEF = 1, | |
72 | DYN_DEF = 2, | |
73 | DYN_WEAK_DEF = 3, | |
74 | UNDEF = 4, | |
75 | WEAK_UNDEF = 5, | |
76 | DYN_UNDEF = 6, | |
77 | DYN_WEAK_UNDEF = 7, | |
78 | COMMON = 8, | |
79 | WEAK_COMMON = 9, | |
80 | DYN_COMMON = 10, | |
81 | DYN_WEAK_COMMON = 11 | |
82 | }; | |
83 | ||
84 | int tobits; | |
85 | switch (to->binding()) | |
86 | { | |
87 | case elfcpp::STB_GLOBAL: | |
88 | tobits = 0; | |
89 | break; | |
90 | ||
91 | case elfcpp::STB_WEAK: | |
92 | tobits = 1; | |
93 | break; | |
94 | ||
95 | case elfcpp::STB_LOCAL: | |
96 | // We should only see externally visible symbols in the symbol | |
97 | // table. | |
98 | abort(); | |
99 | ||
100 | default: | |
101 | // Any target which wants to handle STB_LOOS, etc., needs to | |
102 | // define a resolve method. | |
103 | abort(); | |
104 | } | |
105 | ||
106 | if (to->object() != NULL && to->object()->is_dynamic()) | |
107 | tobits |= (1 << 1); | |
108 | ||
109 | switch (to->shnum()) | |
110 | { | |
111 | case elfcpp::SHN_UNDEF: | |
112 | tobits |= (1 << 2); | |
113 | break; | |
114 | ||
115 | case elfcpp::SHN_COMMON: | |
116 | tobits |= (2 << 2); | |
117 | break; | |
118 | ||
119 | default: | |
1564db8d ILT |
120 | if (to->type() == elfcpp::STT_COMMON) |
121 | tobits |= (2 << 2); | |
14bfc3f5 ILT |
122 | break; |
123 | } | |
124 | ||
125 | int frombits; | |
126 | switch (sym.get_st_bind()) | |
127 | { | |
128 | case elfcpp::STB_GLOBAL: | |
129 | frombits = 0; | |
130 | break; | |
131 | ||
132 | case elfcpp::STB_WEAK: | |
133 | frombits = 1; | |
134 | break; | |
135 | ||
136 | case elfcpp::STB_LOCAL: | |
137 | fprintf(stderr, | |
138 | _("%s: %s: invalid STB_LOCAL symbol %s in external symbols\n"), | |
139 | program_name, object->name().c_str(), to->name()); | |
140 | gold_exit(false); | |
141 | ||
142 | default: | |
143 | fprintf(stderr, | |
144 | _("%s: %s: unsupported symbol binding %d for symbol %s\n"), | |
145 | program_name, object->name().c_str(), | |
146 | static_cast<int>(sym.get_st_bind()), to->name()); | |
147 | gold_exit(false); | |
148 | } | |
149 | ||
150 | if (object->is_dynamic()) | |
1564db8d ILT |
151 | { |
152 | frombits |= (1 << 1); | |
153 | ||
154 | // Record that we've seen this symbol in a dynamic object. | |
155 | to->set_in_dyn(); | |
156 | } | |
14bfc3f5 ILT |
157 | |
158 | switch (sym.get_st_shndx()) | |
159 | { | |
160 | case elfcpp::SHN_UNDEF: | |
161 | frombits |= (1 << 2); | |
162 | break; | |
163 | ||
164 | case elfcpp::SHN_COMMON: | |
165 | frombits |= (2 << 2); | |
166 | break; | |
167 | ||
168 | default: | |
1564db8d ILT |
169 | if (sym.get_st_type() == elfcpp::STT_COMMON) |
170 | frombits |= (2 << 2); | |
14bfc3f5 ILT |
171 | break; |
172 | } | |
173 | ||
1564db8d ILT |
174 | // FIXME: Warn if either but not both of TO and SYM are STT_TLS. |
175 | ||
14bfc3f5 ILT |
176 | // We use a giant switch table for symbol resolution. This code is |
177 | // unwieldy, but: 1) it is efficient; 2) we definitely handle all | |
178 | // cases; 3) it is easy to change the handling of a particular case. | |
179 | // The alternative would be a series of conditionals, but it is easy | |
180 | // to get the ordering wrong. This could also be done as a table, | |
181 | // but that is no easier to understand than this large switch | |
182 | // statement. | |
183 | ||
184 | switch (tobits * 16 + frombits) | |
185 | { | |
186 | case DEF * 16 + DEF: | |
61ba1cf9 ILT |
187 | // Two definitions of the same symbol. We can't give an error |
188 | // here, because we have not yet discarded linkonce and comdat | |
189 | // sections. FIXME. | |
14bfc3f5 ILT |
190 | return; |
191 | ||
192 | case WEAK_DEF * 16 + DEF: | |
1564db8d ILT |
193 | // We've seen a weak definition, and now we see a strong |
194 | // definition. In the original SVR4 linker, this was treated as | |
195 | // a multiple definition error. In the Solaris linker and the | |
196 | // GNU linker, a weak definition followed by a regular | |
197 | // definition causes the weak definition to be overridden. We | |
198 | // are currently compatible with the GNU linker. In the future | |
199 | // we should add a target specific option to change this. | |
200 | // FIXME. | |
201 | to->override(sym, object); | |
14bfc3f5 ILT |
202 | return; |
203 | ||
204 | case DYN_DEF * 16 + DEF: | |
205 | case DYN_WEAK_DEF * 16 + DEF: | |
1564db8d ILT |
206 | // We've seen a definition in a dynamic object, and now we see a |
207 | // definition in a regular object. The definition in the | |
208 | // regular object overrides the definition in the dynamic | |
209 | // object. | |
210 | to->override(sym, object); | |
211 | return; | |
212 | ||
14bfc3f5 ILT |
213 | case UNDEF * 16 + DEF: |
214 | case WEAK_UNDEF * 16 + DEF: | |
215 | case DYN_UNDEF * 16 + DEF: | |
216 | case DYN_WEAK_UNDEF * 16 + DEF: | |
1564db8d ILT |
217 | // We've seen an undefined reference, and now we see a |
218 | // definition. We use the definition. | |
219 | to->override(sym, object); | |
220 | return; | |
221 | ||
14bfc3f5 ILT |
222 | case COMMON * 16 + DEF: |
223 | case WEAK_COMMON * 16 + DEF: | |
224 | case DYN_COMMON * 16 + DEF: | |
225 | case DYN_WEAK_COMMON * 16 + DEF: | |
1564db8d ILT |
226 | // We've seen a common symbol and now we see a definition. The |
227 | // definition overrides. FIXME: We should optionally issue a | |
228 | // warning. | |
229 | to->override(sym, object); | |
230 | return; | |
14bfc3f5 ILT |
231 | |
232 | case DEF * 16 + WEAK_DEF: | |
233 | case WEAK_DEF * 16 + WEAK_DEF: | |
1564db8d ILT |
234 | // We've seen a definition and now we see a weak definition. We |
235 | // ignore the new weak definition. | |
236 | return; | |
237 | ||
14bfc3f5 ILT |
238 | case DYN_DEF * 16 + WEAK_DEF: |
239 | case DYN_WEAK_DEF * 16 + WEAK_DEF: | |
1564db8d ILT |
240 | // We've seen a dynamic definition and now we see a regular weak |
241 | // definition. The regular weak definition overrides. | |
242 | to->override(sym, object); | |
243 | return; | |
244 | ||
14bfc3f5 ILT |
245 | case UNDEF * 16 + WEAK_DEF: |
246 | case WEAK_UNDEF * 16 + WEAK_DEF: | |
247 | case DYN_UNDEF * 16 + WEAK_DEF: | |
248 | case DYN_WEAK_UNDEF * 16 + WEAK_DEF: | |
1564db8d ILT |
249 | // A weak definition of a currently undefined symbol. |
250 | to->override(sym, object); | |
251 | return; | |
252 | ||
14bfc3f5 ILT |
253 | case COMMON * 16 + WEAK_DEF: |
254 | case WEAK_COMMON * 16 + WEAK_DEF: | |
1564db8d ILT |
255 | // A weak definition does not override a common definition. |
256 | return; | |
257 | ||
14bfc3f5 ILT |
258 | case DYN_COMMON * 16 + WEAK_DEF: |
259 | case DYN_WEAK_COMMON * 16 + WEAK_DEF: | |
1564db8d ILT |
260 | // A weak definition does override a definition in a dynamic |
261 | // object. FIXME: We should optionally issue a warning. | |
262 | to->override(sym, object); | |
263 | return; | |
14bfc3f5 ILT |
264 | |
265 | case DEF * 16 + DYN_DEF: | |
266 | case WEAK_DEF * 16 + DYN_DEF: | |
267 | case DYN_DEF * 16 + DYN_DEF: | |
268 | case DYN_WEAK_DEF * 16 + DYN_DEF: | |
1564db8d ILT |
269 | // Ignore a dynamic definition if we already have a definition. |
270 | return; | |
271 | ||
14bfc3f5 ILT |
272 | case UNDEF * 16 + DYN_DEF: |
273 | case WEAK_UNDEF * 16 + DYN_DEF: | |
274 | case DYN_UNDEF * 16 + DYN_DEF: | |
275 | case DYN_WEAK_UNDEF * 16 + DYN_DEF: | |
1564db8d ILT |
276 | // Use a dynamic definition if we have a reference. |
277 | to->override(sym, object); | |
278 | return; | |
279 | ||
14bfc3f5 ILT |
280 | case COMMON * 16 + DYN_DEF: |
281 | case WEAK_COMMON * 16 + DYN_DEF: | |
282 | case DYN_COMMON * 16 + DYN_DEF: | |
283 | case DYN_WEAK_COMMON * 16 + DYN_DEF: | |
1564db8d ILT |
284 | // Ignore a dynamic definition if we already have a common |
285 | // definition. | |
286 | return; | |
14bfc3f5 ILT |
287 | |
288 | case DEF * 16 + DYN_WEAK_DEF: | |
289 | case WEAK_DEF * 16 + DYN_WEAK_DEF: | |
290 | case DYN_DEF * 16 + DYN_WEAK_DEF: | |
291 | case DYN_WEAK_DEF * 16 + DYN_WEAK_DEF: | |
1564db8d ILT |
292 | // Ignore a weak dynamic definition if we already have a |
293 | // definition. | |
294 | return; | |
295 | ||
14bfc3f5 ILT |
296 | case UNDEF * 16 + DYN_WEAK_DEF: |
297 | case WEAK_UNDEF * 16 + DYN_WEAK_DEF: | |
298 | case DYN_UNDEF * 16 + DYN_WEAK_DEF: | |
299 | case DYN_WEAK_UNDEF * 16 + DYN_WEAK_DEF: | |
1564db8d ILT |
300 | // Use a weak dynamic definition if we have a reference. |
301 | to->override(sym, object); | |
302 | return; | |
303 | ||
14bfc3f5 ILT |
304 | case COMMON * 16 + DYN_WEAK_DEF: |
305 | case WEAK_COMMON * 16 + DYN_WEAK_DEF: | |
306 | case DYN_COMMON * 16 + DYN_WEAK_DEF: | |
307 | case DYN_WEAK_COMMON * 16 + DYN_WEAK_DEF: | |
1564db8d ILT |
308 | // Ignore a weak dynamic definition if we already have a common |
309 | // definition. | |
310 | return; | |
14bfc3f5 ILT |
311 | |
312 | case DEF * 16 + UNDEF: | |
313 | case WEAK_DEF * 16 + UNDEF: | |
314 | case DYN_DEF * 16 + UNDEF: | |
315 | case DYN_WEAK_DEF * 16 + UNDEF: | |
316 | case UNDEF * 16 + UNDEF: | |
317 | case WEAK_UNDEF * 16 + UNDEF: | |
318 | case DYN_UNDEF * 16 + UNDEF: | |
319 | case DYN_WEAK_UNDEF * 16 + UNDEF: | |
320 | case COMMON * 16 + UNDEF: | |
321 | case WEAK_COMMON * 16 + UNDEF: | |
322 | case DYN_COMMON * 16 + UNDEF: | |
323 | case DYN_WEAK_COMMON * 16 + UNDEF: | |
1564db8d ILT |
324 | // A new undefined reference tells us nothing. |
325 | return; | |
14bfc3f5 ILT |
326 | |
327 | case DEF * 16 + WEAK_UNDEF: | |
328 | case WEAK_DEF * 16 + WEAK_UNDEF: | |
329 | case DYN_DEF * 16 + WEAK_UNDEF: | |
330 | case DYN_WEAK_DEF * 16 + WEAK_UNDEF: | |
331 | case UNDEF * 16 + WEAK_UNDEF: | |
332 | case WEAK_UNDEF * 16 + WEAK_UNDEF: | |
333 | case DYN_UNDEF * 16 + WEAK_UNDEF: | |
334 | case DYN_WEAK_UNDEF * 16 + WEAK_UNDEF: | |
335 | case COMMON * 16 + WEAK_UNDEF: | |
336 | case WEAK_COMMON * 16 + WEAK_UNDEF: | |
337 | case DYN_COMMON * 16 + WEAK_UNDEF: | |
338 | case DYN_WEAK_COMMON * 16 + WEAK_UNDEF: | |
1564db8d ILT |
339 | // A new weak undefined reference tells us nothing. |
340 | return; | |
14bfc3f5 ILT |
341 | |
342 | case DEF * 16 + DYN_UNDEF: | |
343 | case WEAK_DEF * 16 + DYN_UNDEF: | |
344 | case DYN_DEF * 16 + DYN_UNDEF: | |
345 | case DYN_WEAK_DEF * 16 + DYN_UNDEF: | |
346 | case UNDEF * 16 + DYN_UNDEF: | |
347 | case WEAK_UNDEF * 16 + DYN_UNDEF: | |
348 | case DYN_UNDEF * 16 + DYN_UNDEF: | |
349 | case DYN_WEAK_UNDEF * 16 + DYN_UNDEF: | |
350 | case COMMON * 16 + DYN_UNDEF: | |
351 | case WEAK_COMMON * 16 + DYN_UNDEF: | |
352 | case DYN_COMMON * 16 + DYN_UNDEF: | |
353 | case DYN_WEAK_COMMON * 16 + DYN_UNDEF: | |
1564db8d ILT |
354 | // A new dynamic undefined reference tells us nothing. |
355 | return; | |
14bfc3f5 ILT |
356 | |
357 | case DEF * 16 + DYN_WEAK_UNDEF: | |
358 | case WEAK_DEF * 16 + DYN_WEAK_UNDEF: | |
359 | case DYN_DEF * 16 + DYN_WEAK_UNDEF: | |
360 | case DYN_WEAK_DEF * 16 + DYN_WEAK_UNDEF: | |
361 | case UNDEF * 16 + DYN_WEAK_UNDEF: | |
362 | case WEAK_UNDEF * 16 + DYN_WEAK_UNDEF: | |
363 | case DYN_UNDEF * 16 + DYN_WEAK_UNDEF: | |
364 | case DYN_WEAK_UNDEF * 16 + DYN_WEAK_UNDEF: | |
365 | case COMMON * 16 + DYN_WEAK_UNDEF: | |
366 | case WEAK_COMMON * 16 + DYN_WEAK_UNDEF: | |
367 | case DYN_COMMON * 16 + DYN_WEAK_UNDEF: | |
368 | case DYN_WEAK_COMMON * 16 + DYN_WEAK_UNDEF: | |
1564db8d ILT |
369 | // A new weak dynamic undefined reference tells us nothing. |
370 | return; | |
14bfc3f5 ILT |
371 | |
372 | case DEF * 16 + COMMON: | |
1564db8d ILT |
373 | // A common symbol does not override a definition. |
374 | return; | |
375 | ||
14bfc3f5 ILT |
376 | case WEAK_DEF * 16 + COMMON: |
377 | case DYN_DEF * 16 + COMMON: | |
378 | case DYN_WEAK_DEF * 16 + COMMON: | |
1564db8d ILT |
379 | // A common symbol does override a weak definition or a dynamic |
380 | // definition. | |
381 | to->override(sym, object); | |
382 | return; | |
383 | ||
14bfc3f5 ILT |
384 | case UNDEF * 16 + COMMON: |
385 | case WEAK_UNDEF * 16 + COMMON: | |
386 | case DYN_UNDEF * 16 + COMMON: | |
387 | case DYN_WEAK_UNDEF * 16 + COMMON: | |
1564db8d ILT |
388 | // A common symbol is a definition for a reference. |
389 | to->override(sym, object); | |
390 | return; | |
391 | ||
14bfc3f5 ILT |
392 | case COMMON * 16 + COMMON: |
393 | case WEAK_COMMON * 16 + COMMON: | |
394 | case DYN_COMMON * 16 + COMMON: | |
395 | case DYN_WEAK_COMMON * 16 + COMMON: | |
396 | ||
397 | case DEF * 16 + WEAK_COMMON: | |
398 | case WEAK_DEF * 16 + WEAK_COMMON: | |
399 | case DYN_DEF * 16 + WEAK_COMMON: | |
400 | case DYN_WEAK_DEF * 16 + WEAK_COMMON: | |
401 | case UNDEF * 16 + WEAK_COMMON: | |
402 | case WEAK_UNDEF * 16 + WEAK_COMMON: | |
403 | case DYN_UNDEF * 16 + WEAK_COMMON: | |
404 | case DYN_WEAK_UNDEF * 16 + WEAK_COMMON: | |
405 | case COMMON * 16 + WEAK_COMMON: | |
406 | case WEAK_COMMON * 16 + WEAK_COMMON: | |
407 | case DYN_COMMON * 16 + WEAK_COMMON: | |
408 | case DYN_WEAK_COMMON * 16 + WEAK_COMMON: | |
409 | ||
410 | case DEF * 16 + DYN_COMMON: | |
411 | case WEAK_DEF * 16 + DYN_COMMON: | |
412 | case DYN_DEF * 16 + DYN_COMMON: | |
413 | case DYN_WEAK_DEF * 16 + DYN_COMMON: | |
414 | case UNDEF * 16 + DYN_COMMON: | |
415 | case WEAK_UNDEF * 16 + DYN_COMMON: | |
416 | case DYN_UNDEF * 16 + DYN_COMMON: | |
417 | case DYN_WEAK_UNDEF * 16 + DYN_COMMON: | |
418 | case COMMON * 16 + DYN_COMMON: | |
419 | case WEAK_COMMON * 16 + DYN_COMMON: | |
420 | case DYN_COMMON * 16 + DYN_COMMON: | |
421 | case DYN_WEAK_COMMON * 16 + DYN_COMMON: | |
422 | ||
423 | case DEF * 16 + DYN_WEAK_COMMON: | |
424 | case WEAK_DEF * 16 + DYN_WEAK_COMMON: | |
425 | case DYN_DEF * 16 + DYN_WEAK_COMMON: | |
426 | case DYN_WEAK_DEF * 16 + DYN_WEAK_COMMON: | |
427 | case UNDEF * 16 + DYN_WEAK_COMMON: | |
428 | case WEAK_UNDEF * 16 + DYN_WEAK_COMMON: | |
429 | case DYN_UNDEF * 16 + DYN_WEAK_COMMON: | |
430 | case DYN_WEAK_UNDEF * 16 + DYN_WEAK_COMMON: | |
431 | case COMMON * 16 + DYN_WEAK_COMMON: | |
432 | case WEAK_COMMON * 16 + DYN_WEAK_COMMON: | |
433 | case DYN_COMMON * 16 + DYN_WEAK_COMMON: | |
434 | case DYN_WEAK_COMMON * 16 + DYN_WEAK_COMMON: | |
1564db8d | 435 | abort(); |
14bfc3f5 | 436 | break; |
1564db8d ILT |
437 | |
438 | default: | |
439 | abort(); | |
14bfc3f5 ILT |
440 | } |
441 | } | |
442 | ||
443 | // Instantiate the templates we need. We could use the configure | |
444 | // script to restrict this to only the ones needed for implemented | |
445 | // targets. | |
446 | ||
447 | template | |
448 | void | |
449 | Symbol_table::resolve<32, true>( | |
1564db8d | 450 | Sized_symbol<32>* to, |
14bfc3f5 ILT |
451 | const elfcpp::Sym<32, true>& sym, |
452 | Object* object); | |
453 | ||
454 | template | |
455 | void | |
456 | Symbol_table::resolve<32, false>( | |
1564db8d | 457 | Sized_symbol<32>* to, |
14bfc3f5 ILT |
458 | const elfcpp::Sym<32, false>& sym, |
459 | Object* object); | |
460 | ||
461 | template | |
462 | void | |
463 | Symbol_table::resolve<64, true>( | |
1564db8d | 464 | Sized_symbol<64>* to, |
14bfc3f5 ILT |
465 | const elfcpp::Sym<64, true>& sym, |
466 | Object* object); | |
467 | ||
468 | template | |
469 | void | |
470 | Symbol_table::resolve<64, false>( | |
1564db8d | 471 | Sized_symbol<64>* to, |
14bfc3f5 ILT |
472 | const elfcpp::Sym<64, false>& sym, |
473 | Object* object); | |
474 | ||
475 | } // End namespace gold. |