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d7f09764 DN |
1 | /* LTO symbol table. |
2 | Copyright 2009 Free Software Foundation, Inc. | |
3 | Contributed by CodeSourcery, Inc. | |
4 | ||
5 | This file is part of GCC. | |
6 | ||
7 | GCC is free software; you can redistribute it and/or modify it under | |
8 | the terms of the GNU General Public License as published by the Free | |
9 | Software Foundation; either version 3, or (at your option) any later | |
10 | version. | |
11 | ||
12 | GCC is distributed in the hope that it will be useful, but WITHOUT ANY | |
13 | WARRANTY; without even the implied warranty of MERCHANTABILITY or | |
14 | FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License | |
15 | for more details. | |
16 | ||
17 | You should have received a copy of the GNU General Public License | |
18 | along with GCC; see the file COPYING3. If not see | |
19 | <http://www.gnu.org/licenses/>. */ | |
20 | ||
21 | #include "config.h" | |
22 | #include "system.h" | |
23 | #include "coretypes.h" | |
718f9c0f | 24 | #include "diagnostic-core.h" |
d7f09764 DN |
25 | #include "toplev.h" |
26 | #include "tree.h" | |
27 | #include "gimple.h" | |
a9429e29 | 28 | #include "ggc.h" |
d7f09764 DN |
29 | #include "lambda.h" /* gcd */ |
30 | #include "hashtab.h" | |
31 | #include "plugin-api.h" | |
32 | #include "lto-streamer.h" | |
33 | ||
34 | /* Vector to keep track of external variables we've seen so far. */ | |
35 | VEC(tree,gc) *lto_global_var_decls; | |
36 | ||
1a735925 | 37 | /* Symbol table entry. */ |
d7f09764 | 38 | |
1a735925 | 39 | struct GTY(()) lto_symtab_entry_def |
d7f09764 | 40 | { |
1a735925 RG |
41 | /* The symbol table entry key, an IDENTIFIER. */ |
42 | tree id; | |
43 | /* The symbol table entry, a DECL. */ | |
d7f09764 | 44 | tree decl; |
2c928155 RG |
45 | /* The cgraph node if decl is a function decl. Filled in during the |
46 | merging process. */ | |
47 | struct cgraph_node *node; | |
2942c502 JH |
48 | /* The varpool node if decl is a variable decl. Filled in during the |
49 | merging process. */ | |
50 | struct varpool_node *vnode; | |
1a735925 | 51 | /* LTO file-data and symbol resolution for this decl. */ |
d7f09764 | 52 | struct lto_file_decl_data * GTY((skip (""))) file_data; |
1a735925 RG |
53 | enum ld_plugin_symbol_resolution resolution; |
54 | /* Pointer to the next entry with the same key. Before decl merging | |
55 | this links all symbols from the different TUs. After decl merging | |
56 | this links merged but incompatible decls, thus all prevailing ones | |
57 | remaining. */ | |
58 | struct lto_symtab_entry_def *next; | |
d7f09764 | 59 | }; |
1a735925 | 60 | typedef struct lto_symtab_entry_def *lto_symtab_entry_t; |
d7f09764 DN |
61 | |
62 | /* A poor man's symbol table. This hashes identifier to prevailing DECL | |
63 | if there is one. */ | |
64 | ||
1a735925 RG |
65 | static GTY ((if_marked ("lto_symtab_entry_marked_p"), |
66 | param_is (struct lto_symtab_entry_def))) | |
d7f09764 DN |
67 | htab_t lto_symtab_identifiers; |
68 | ||
9a809897 JH |
69 | /* Free symtab hashtable. */ |
70 | ||
71 | void | |
72 | lto_symtab_free (void) | |
73 | { | |
74 | htab_delete (lto_symtab_identifiers); | |
75 | lto_symtab_identifiers = NULL; | |
76 | } | |
77 | ||
1a735925 | 78 | /* Return the hash value of an lto_symtab_entry_t object pointed to by P. */ |
d7f09764 DN |
79 | |
80 | static hashval_t | |
1a735925 | 81 | lto_symtab_entry_hash (const void *p) |
d7f09764 | 82 | { |
1a735925 RG |
83 | const struct lto_symtab_entry_def *base = |
84 | (const struct lto_symtab_entry_def *) p; | |
6456e26e | 85 | return IDENTIFIER_HASH_VALUE (base->id); |
d7f09764 DN |
86 | } |
87 | ||
1a735925 RG |
88 | /* Return non-zero if P1 and P2 points to lto_symtab_entry_def structs |
89 | corresponding to the same symbol. */ | |
d7f09764 DN |
90 | |
91 | static int | |
1a735925 | 92 | lto_symtab_entry_eq (const void *p1, const void *p2) |
d7f09764 | 93 | { |
1a735925 RG |
94 | const struct lto_symtab_entry_def *base1 = |
95 | (const struct lto_symtab_entry_def *) p1; | |
96 | const struct lto_symtab_entry_def *base2 = | |
97 | (const struct lto_symtab_entry_def *) p2; | |
98 | return (base1->id == base2->id); | |
d7f09764 DN |
99 | } |
100 | ||
1a735925 | 101 | /* Returns non-zero if P points to an lto_symtab_entry_def struct that needs |
b8698a0f | 102 | to be marked for GC. */ |
d7f09764 DN |
103 | |
104 | static int | |
1a735925 | 105 | lto_symtab_entry_marked_p (const void *p) |
d7f09764 | 106 | { |
1a735925 RG |
107 | const struct lto_symtab_entry_def *base = |
108 | (const struct lto_symtab_entry_def *) p; | |
d7f09764 | 109 | |
571943de RG |
110 | /* Keep this only if the common IDENTIFIER_NODE of the symtab chain |
111 | is marked which it will be if at least one of the DECLs in the | |
112 | chain is marked. */ | |
113 | return ggc_marked_p (base->id); | |
d7f09764 DN |
114 | } |
115 | ||
d7f09764 DN |
116 | /* Lazily initialize resolution hash tables. */ |
117 | ||
118 | static void | |
1a735925 | 119 | lto_symtab_maybe_init_hash_table (void) |
d7f09764 | 120 | { |
1a735925 RG |
121 | if (lto_symtab_identifiers) |
122 | return; | |
123 | ||
124 | lto_symtab_identifiers = | |
125 | htab_create_ggc (1021, lto_symtab_entry_hash, | |
126 | lto_symtab_entry_eq, NULL); | |
d7f09764 DN |
127 | } |
128 | ||
200c8750 RG |
129 | /* Registers DECL with the LTO symbol table as having resolution RESOLUTION |
130 | and read from FILE_DATA. */ | |
131 | ||
132 | void | |
133 | lto_symtab_register_decl (tree decl, | |
134 | ld_plugin_symbol_resolution_t resolution, | |
135 | struct lto_file_decl_data *file_data) | |
136 | { | |
137 | lto_symtab_entry_t new_entry; | |
138 | void **slot; | |
139 | ||
140 | /* Check that declarations reaching this function do not have | |
141 | properties inconsistent with having external linkage. If any of | |
142 | these asertions fail, then the object file reader has failed to | |
143 | detect these cases and issue appropriate error messages. */ | |
144 | gcc_assert (decl | |
145 | && TREE_PUBLIC (decl) | |
146 | && (TREE_CODE (decl) == VAR_DECL | |
147 | || TREE_CODE (decl) == FUNCTION_DECL) | |
148 | && DECL_ASSEMBLER_NAME_SET_P (decl)); | |
149 | if (TREE_CODE (decl) == VAR_DECL | |
150 | && DECL_INITIAL (decl)) | |
151 | gcc_assert (!DECL_EXTERNAL (decl) | |
152 | || (TREE_STATIC (decl) && TREE_READONLY (decl))); | |
153 | if (TREE_CODE (decl) == FUNCTION_DECL) | |
154 | gcc_assert (!DECL_ABSTRACT (decl)); | |
155 | ||
a9429e29 | 156 | new_entry = ggc_alloc_cleared_lto_symtab_entry_def (); |
200c8750 RG |
157 | new_entry->id = DECL_ASSEMBLER_NAME (decl); |
158 | new_entry->decl = decl; | |
159 | new_entry->resolution = resolution; | |
160 | new_entry->file_data = file_data; | |
161 | ||
162 | lto_symtab_maybe_init_hash_table (); | |
163 | slot = htab_find_slot (lto_symtab_identifiers, new_entry, INSERT); | |
164 | new_entry->next = (lto_symtab_entry_t) *slot; | |
165 | *slot = new_entry; | |
166 | } | |
167 | ||
168 | /* Get the lto_symtab_entry_def struct associated with ID | |
169 | if there is one. */ | |
170 | ||
171 | static lto_symtab_entry_t | |
172 | lto_symtab_get (tree id) | |
173 | { | |
174 | struct lto_symtab_entry_def temp; | |
175 | void **slot; | |
176 | ||
177 | lto_symtab_maybe_init_hash_table (); | |
178 | temp.id = id; | |
179 | slot = htab_find_slot (lto_symtab_identifiers, &temp, NO_INSERT); | |
180 | return slot ? (lto_symtab_entry_t) *slot : NULL; | |
181 | } | |
182 | ||
183 | /* Get the linker resolution for DECL. */ | |
184 | ||
185 | enum ld_plugin_symbol_resolution | |
186 | lto_symtab_get_resolution (tree decl) | |
187 | { | |
188 | lto_symtab_entry_t e; | |
189 | ||
190 | gcc_assert (DECL_ASSEMBLER_NAME_SET_P (decl)); | |
191 | ||
192 | e = lto_symtab_get (DECL_ASSEMBLER_NAME (decl)); | |
193 | while (e && e->decl != decl) | |
194 | e = e->next; | |
195 | if (!e) | |
196 | return LDPR_UNKNOWN; | |
197 | ||
198 | return e->resolution; | |
199 | } | |
200 | ||
201 | ||
200c8750 RG |
202 | /* Replace the cgraph node NODE with PREVAILING_NODE in the cgraph, merging |
203 | all edges and removing the old node. */ | |
d7f09764 | 204 | |
200c8750 RG |
205 | static void |
206 | lto_cgraph_replace_node (struct cgraph_node *node, | |
207 | struct cgraph_node *prevailing_node) | |
d7f09764 | 208 | { |
200c8750 | 209 | struct cgraph_edge *e, *next; |
e10aaec0 JH |
210 | bool no_aliases_please = false; |
211 | ||
212 | if (cgraph_dump_file) | |
213 | { | |
214 | fprintf (cgraph_dump_file, "Replacing cgraph node %s/%i by %s/%i" | |
215 | " for symbol %s\n", | |
216 | cgraph_node_name (node), node->uid, | |
217 | cgraph_node_name (prevailing_node), | |
218 | prevailing_node->uid, | |
219 | IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (node->decl))); | |
220 | } | |
221 | ||
222 | if (prevailing_node->same_body_alias) | |
223 | { | |
224 | if (prevailing_node->thunk.thunk_p) | |
225 | no_aliases_please = true; | |
226 | prevailing_node = prevailing_node->same_body; | |
227 | } | |
d7f09764 | 228 | |
200c8750 RG |
229 | /* Merge node flags. */ |
230 | if (node->needed) | |
231 | cgraph_mark_needed_node (prevailing_node); | |
232 | if (node->reachable) | |
233 | cgraph_mark_reachable_node (prevailing_node); | |
234 | if (node->address_taken) | |
d7f09764 | 235 | { |
200c8750 RG |
236 | gcc_assert (!prevailing_node->global.inlined_to); |
237 | cgraph_mark_address_taken_node (prevailing_node); | |
238 | } | |
d7f09764 | 239 | |
200c8750 RG |
240 | /* Redirect all incoming edges. */ |
241 | for (e = node->callers; e; e = next) | |
242 | { | |
243 | next = e->next_caller; | |
244 | cgraph_redirect_edge_callee (e, prevailing_node); | |
245 | } | |
369451ec JH |
246 | /* Redirect incomming references. */ |
247 | ipa_clone_refering (prevailing_node, NULL, &node->ref_list); | |
d7f09764 | 248 | |
e10aaec0 JH |
249 | /* If we have aliases, redirect them to the prevailing node. */ |
250 | if (!node->same_body_alias && node->same_body) | |
b2583345 | 251 | { |
e10aaec0 JH |
252 | struct cgraph_node *alias, *last; |
253 | /* We prevail aliases/tunks by a thunk. This is doable but | |
254 | would need thunk combination. Hopefully no ABI changes will | |
255 | every be crazy enough. */ | |
256 | gcc_assert (!no_aliases_please); | |
b2583345 JJ |
257 | |
258 | for (alias = node->same_body; alias; alias = alias->next) | |
e10aaec0 JH |
259 | { |
260 | last = alias; | |
261 | gcc_assert (alias->same_body_alias); | |
262 | alias->same_body = prevailing_node; | |
263 | alias->thunk.alias = prevailing_node->decl; | |
264 | } | |
265 | last->next = prevailing_node->same_body; | |
266 | /* Node with aliases is prevailed by alias. | |
267 | We could handle this, but combining thunks together will be tricky. | |
268 | Hopefully this does not happen. */ | |
269 | if (prevailing_node->same_body) | |
270 | prevailing_node->same_body->previous = last; | |
271 | prevailing_node->same_body = node->same_body; | |
272 | node->same_body = NULL; | |
b2583345 JJ |
273 | } |
274 | ||
200c8750 | 275 | /* Finally remove the replaced node. */ |
e10aaec0 JH |
276 | if (node->same_body_alias) |
277 | cgraph_remove_same_body_alias (node); | |
278 | else | |
279 | cgraph_remove_node (node); | |
200c8750 RG |
280 | } |
281 | ||
2942c502 JH |
282 | /* Replace the cgraph node NODE with PREVAILING_NODE in the cgraph, merging |
283 | all edges and removing the old node. */ | |
284 | ||
285 | static void | |
286 | lto_varpool_replace_node (struct varpool_node *vnode, | |
287 | struct varpool_node *prevailing_node) | |
288 | { | |
289 | /* Merge node flags. */ | |
290 | if (vnode->needed) | |
291 | { | |
688a10c2 | 292 | gcc_assert (!vnode->analyzed || prevailing_node->analyzed); |
2942c502 JH |
293 | varpool_mark_needed_node (prevailing_node); |
294 | } | |
688a10c2 JH |
295 | /* Relink aliases. */ |
296 | if (vnode->extra_name && !vnode->alias) | |
297 | { | |
298 | struct varpool_node *alias, *last; | |
299 | for (alias = vnode->extra_name; | |
300 | alias; alias = alias->next) | |
301 | { | |
302 | last = alias; | |
303 | alias->extra_name = prevailing_node; | |
304 | } | |
305 | ||
306 | if (prevailing_node->extra_name) | |
307 | { | |
308 | last->next = prevailing_node->extra_name; | |
309 | prevailing_node->extra_name->prev = last; | |
310 | } | |
311 | prevailing_node->extra_name = vnode->extra_name; | |
312 | vnode->extra_name = NULL; | |
313 | } | |
2942c502 JH |
314 | gcc_assert (!vnode->finalized || prevailing_node->finalized); |
315 | gcc_assert (!vnode->analyzed || prevailing_node->analyzed); | |
316 | ||
369451ec JH |
317 | /* When replacing by an alias, the references goes to the original |
318 | variable. */ | |
319 | if (prevailing_node->alias && prevailing_node->extra_name) | |
320 | prevailing_node = prevailing_node->extra_name; | |
321 | ipa_clone_refering (NULL, prevailing_node, &vnode->ref_list); | |
322 | ||
b34fd25c JH |
323 | /* Be sure we can garbage collect the initializer. */ |
324 | if (DECL_INITIAL (vnode->decl)) | |
325 | DECL_INITIAL (vnode->decl) = error_mark_node; | |
2942c502 JH |
326 | /* Finally remove the replaced node. */ |
327 | varpool_remove_node (vnode); | |
328 | } | |
329 | ||
200c8750 RG |
330 | /* Merge two variable or function symbol table entries PREVAILING and ENTRY. |
331 | Return false if the symbols are not fully compatible and a diagnostic | |
332 | should be emitted. */ | |
333 | ||
334 | static bool | |
335 | lto_symtab_merge (lto_symtab_entry_t prevailing, lto_symtab_entry_t entry) | |
336 | { | |
337 | tree prevailing_decl = prevailing->decl; | |
338 | tree decl = entry->decl; | |
339 | tree prevailing_type, type; | |
200c8750 RG |
340 | |
341 | /* Merge decl state in both directions, we may still end up using | |
342 | the new decl. */ | |
343 | TREE_ADDRESSABLE (prevailing_decl) |= TREE_ADDRESSABLE (decl); | |
344 | TREE_ADDRESSABLE (decl) |= TREE_ADDRESSABLE (prevailing_decl); | |
345 | ||
200c8750 RG |
346 | /* The linker may ask us to combine two incompatible symbols. |
347 | Detect this case and notify the caller of required diagnostics. */ | |
348 | ||
349 | if (TREE_CODE (decl) == FUNCTION_DECL) | |
fd7588bc | 350 | { |
e575382e | 351 | if (TREE_TYPE (prevailing_decl) != TREE_TYPE (decl)) |
fd7588bc RG |
352 | /* If we don't have a merged type yet...sigh. The linker |
353 | wouldn't complain if the types were mismatched, so we | |
354 | probably shouldn't either. Just use the type from | |
355 | whichever decl appears to be associated with the | |
356 | definition. If for some odd reason neither decl is, the | |
357 | older one wins. */ | |
358 | (void) 0; | |
359 | ||
360 | return true; | |
361 | } | |
362 | ||
363 | /* Now we exclusively deal with VAR_DECLs. */ | |
364 | ||
e575382e RG |
365 | /* Sharing a global symbol is a strong hint that two types are |
366 | compatible. We could use this information to complete | |
367 | incomplete pointed-to types more aggressively here, ignoring | |
368 | mismatches in both field and tag names. It's difficult though | |
369 | to guarantee that this does not have side-effects on merging | |
370 | more compatible types from other translation units though. */ | |
d7f09764 | 371 | |
fd7588bc | 372 | /* We can tolerate differences in type qualification, the |
e575382e RG |
373 | qualification of the prevailing definition will prevail. |
374 | ??? In principle we might want to only warn for structurally | |
375 | incompatible types here, but unless we have protective measures | |
376 | for TBAA in place that would hide useful information. */ | |
200c8750 RG |
377 | prevailing_type = TYPE_MAIN_VARIANT (TREE_TYPE (prevailing_decl)); |
378 | type = TYPE_MAIN_VARIANT (TREE_TYPE (decl)); | |
e575382e RG |
379 | |
380 | /* We have to register and fetch canonical types here as the global | |
381 | fixup process didn't yet run. */ | |
382 | prevailing_type = gimple_register_type (prevailing_type); | |
383 | type = gimple_register_type (type); | |
384 | if (prevailing_type != type) | |
385 | { | |
386 | if (COMPLETE_TYPE_P (type)) | |
387 | return false; | |
388 | ||
389 | /* If type is incomplete then avoid warnings in the cases | |
390 | that TBAA handles just fine. */ | |
391 | ||
392 | if (TREE_CODE (prevailing_type) != TREE_CODE (type)) | |
393 | return false; | |
394 | ||
395 | if (TREE_CODE (prevailing_type) == ARRAY_TYPE) | |
396 | { | |
397 | tree tem1 = TREE_TYPE (prevailing_type); | |
398 | tree tem2 = TREE_TYPE (type); | |
399 | while (TREE_CODE (tem1) == ARRAY_TYPE | |
400 | && TREE_CODE (tem2) == ARRAY_TYPE) | |
401 | { | |
402 | tem1 = TREE_TYPE (tem1); | |
403 | tem2 = TREE_TYPE (tem2); | |
404 | } | |
405 | ||
406 | if (TREE_CODE (tem1) != TREE_CODE (tem2)) | |
407 | return false; | |
408 | ||
409 | if (gimple_register_type (tem1) != gimple_register_type (tem2)) | |
410 | return false; | |
411 | } | |
412 | ||
413 | /* Fallthru. Compatible enough. */ | |
414 | } | |
d7f09764 | 415 | |
fd7588bc RG |
416 | /* ??? We might want to emit a warning here if type qualification |
417 | differences were spotted. Do not do this unconditionally though. */ | |
d7f09764 | 418 | |
fd7588bc RG |
419 | /* There is no point in comparing too many details of the decls here. |
420 | The type compatibility checks or the completing of types has properly | |
421 | dealt with most issues. */ | |
d7f09764 | 422 | |
fd7588bc RG |
423 | /* The following should all not invoke fatal errors as in non-LTO |
424 | mode the linker wouldn't complain either. Just emit warnings. */ | |
d7f09764 | 425 | |
fd7588bc | 426 | /* Report a warning if user-specified alignments do not match. */ |
200c8750 RG |
427 | if ((DECL_USER_ALIGN (prevailing_decl) && DECL_USER_ALIGN (decl)) |
428 | && DECL_ALIGN (prevailing_decl) < DECL_ALIGN (decl)) | |
429 | return false; | |
d7f09764 | 430 | |
d7f09764 DN |
431 | return true; |
432 | } | |
433 | ||
200c8750 RG |
434 | /* Return true if the symtab entry E can be replaced by another symtab |
435 | entry. */ | |
d7f09764 | 436 | |
200c8750 RG |
437 | static bool |
438 | lto_symtab_resolve_replaceable_p (lto_symtab_entry_t e) | |
d7f09764 | 439 | { |
200c8750 RG |
440 | if (DECL_EXTERNAL (e->decl) |
441 | || DECL_COMDAT (e->decl) | |
442 | || DECL_WEAK (e->decl)) | |
443 | return true; | |
d7f09764 | 444 | |
200c8750 RG |
445 | if (TREE_CODE (e->decl) == VAR_DECL) |
446 | return (DECL_COMMON (e->decl) | |
447 | || (!flag_no_common && !DECL_INITIAL (e->decl))); | |
d7f09764 | 448 | |
200c8750 | 449 | return false; |
1a735925 | 450 | } |
d7f09764 | 451 | |
200c8750 | 452 | /* Return true if the symtab entry E can be the prevailing one. */ |
d7f09764 | 453 | |
200c8750 RG |
454 | static bool |
455 | lto_symtab_resolve_can_prevail_p (lto_symtab_entry_t e) | |
1a735925 | 456 | { |
5d96330a RG |
457 | /* The C++ frontend ends up neither setting TREE_STATIC nor |
458 | DECL_EXTERNAL on virtual methods but only TREE_PUBLIC. | |
459 | So do not reject !TREE_STATIC here but only DECL_EXTERNAL. */ | |
460 | if (DECL_EXTERNAL (e->decl)) | |
200c8750 | 461 | return false; |
d7f09764 | 462 | |
200c8750 RG |
463 | /* For functions we need a non-discarded body. */ |
464 | if (TREE_CODE (e->decl) == FUNCTION_DECL) | |
e10aaec0 JH |
465 | return (e->node |
466 | && (e->node->analyzed | |
467 | || (e->node->same_body_alias && e->node->same_body->analyzed))); | |
d7f09764 | 468 | |
200c8750 RG |
469 | /* A variable should have a size. */ |
470 | else if (TREE_CODE (e->decl) == VAR_DECL) | |
9e0546ef JH |
471 | { |
472 | if (!e->vnode) | |
473 | return false; | |
474 | if (e->vnode->finalized) | |
475 | return true; | |
476 | return e->vnode->alias && e->vnode->extra_name->finalized; | |
477 | } | |
d7f09764 | 478 | |
200c8750 | 479 | gcc_unreachable (); |
d7f09764 DN |
480 | } |
481 | ||
1a735925 RG |
482 | /* Resolve the symbol with the candidates in the chain *SLOT and store |
483 | their resolutions. */ | |
d7f09764 | 484 | |
1a735925 RG |
485 | static void |
486 | lto_symtab_resolve_symbols (void **slot) | |
487 | { | |
a5ac2cdf | 488 | lto_symtab_entry_t e; |
200c8750 | 489 | lto_symtab_entry_t prevailing = NULL; |
d7f09764 | 490 | |
a5ac2cdf RAE |
491 | /* Always set e->node so that edges are updated to reflect decl merging. */ |
492 | for (e = (lto_symtab_entry_t) *slot; e; e = e->next) | |
493 | { | |
494 | if (TREE_CODE (e->decl) == FUNCTION_DECL) | |
e10aaec0 | 495 | e->node = cgraph_get_node_or_alias (e->decl); |
2942c502 | 496 | else if (TREE_CODE (e->decl) == VAR_DECL) |
bd9eb5da RG |
497 | { |
498 | e->vnode = varpool_get_node (e->decl); | |
499 | /* The LTO plugin for gold doesn't handle common symbols | |
500 | properly. Let us choose manually. */ | |
501 | if (DECL_COMMON (e->decl)) | |
502 | e->resolution = LDPR_UNKNOWN; | |
503 | } | |
a5ac2cdf RAE |
504 | } |
505 | ||
506 | e = (lto_symtab_entry_t) *slot; | |
507 | ||
508 | /* If the chain is already resolved there is nothing else to do. */ | |
1a735925 RG |
509 | if (e->resolution != LDPR_UNKNOWN) |
510 | return; | |
511 | ||
200c8750 RG |
512 | /* Find the single non-replaceable prevailing symbol and |
513 | diagnose ODR violations. */ | |
a5ac2cdf | 514 | for (e = (lto_symtab_entry_t) *slot; e; e = e->next) |
1a735925 | 515 | { |
200c8750 RG |
516 | if (!lto_symtab_resolve_can_prevail_p (e)) |
517 | { | |
518 | e->resolution = LDPR_RESOLVED_IR; | |
519 | continue; | |
520 | } | |
521 | ||
522 | /* Set a default resolution - the final prevailing one will get | |
523 | adjusted later. */ | |
524 | e->resolution = LDPR_PREEMPTED_IR; | |
525 | if (!lto_symtab_resolve_replaceable_p (e)) | |
526 | { | |
527 | if (prevailing) | |
528 | { | |
529 | error_at (DECL_SOURCE_LOCATION (e->decl), | |
530 | "%qD has already been defined", e->decl); | |
531 | inform (DECL_SOURCE_LOCATION (prevailing->decl), | |
532 | "previously defined here"); | |
533 | } | |
534 | prevailing = e; | |
535 | } | |
536 | } | |
537 | if (prevailing) | |
538 | goto found; | |
539 | ||
540 | /* Do a second round choosing one from the replaceable prevailing decls. */ | |
541 | for (e = (lto_symtab_entry_t) *slot; e; e = e->next) | |
542 | { | |
543 | if (e->resolution != LDPR_PREEMPTED_IR) | |
544 | continue; | |
545 | ||
546 | /* Choose the first function that can prevail as prevailing. */ | |
547 | if (TREE_CODE (e->decl) == FUNCTION_DECL) | |
1a735925 | 548 | { |
200c8750 RG |
549 | prevailing = e; |
550 | break; | |
1a735925 | 551 | } |
200c8750 RG |
552 | |
553 | /* From variables that can prevail choose the largest one. */ | |
554 | if (!prevailing | |
555 | || tree_int_cst_lt (DECL_SIZE (prevailing->decl), | |
556 | DECL_SIZE (e->decl))) | |
557 | prevailing = e; | |
1a735925 | 558 | } |
200c8750 RG |
559 | |
560 | if (!prevailing) | |
561 | return; | |
562 | ||
563 | found: | |
6d41cd02 BM |
564 | /* If current lto files represent the whole program, |
565 | it is correct to use LDPR_PREVALING_DEF_IRONLY. | |
566 | If current lto files are part of whole program, internal | |
567 | resolver doesn't know if it is LDPR_PREVAILING_DEF | |
568 | or LDPR_PREVAILING_DEF_IRONLY. Use IRONLY conforms to | |
569 | using -fwhole-program. Otherwise, it doesn't | |
570 | matter using either LDPR_PREVAILING_DEF or | |
571 | LDPR_PREVAILING_DEF_IRONLY | |
572 | ||
573 | FIXME: above workaround due to gold plugin makes some | |
574 | variables IRONLY, which are indeed PREVAILING_DEF in | |
575 | resolution file. These variables still need manual | |
576 | externally_visible attribute. */ | |
200c8750 | 577 | prevailing->resolution = LDPR_PREVAILING_DEF_IRONLY; |
1a735925 RG |
578 | } |
579 | ||
200c8750 RG |
580 | /* Merge all decls in the symbol table chain to the prevailing decl and |
581 | issue diagnostics about type mismatches. */ | |
1a735925 RG |
582 | |
583 | static void | |
584 | lto_symtab_merge_decls_2 (void **slot) | |
585 | { | |
200c8750 RG |
586 | lto_symtab_entry_t prevailing, e; |
587 | VEC(tree, heap) *mismatches = NULL; | |
588 | unsigned i; | |
589 | tree decl; | |
590 | bool diagnosed_p = false; | |
1a735925 RG |
591 | |
592 | /* Nothing to do for a single entry. */ | |
200c8750 RG |
593 | prevailing = (lto_symtab_entry_t) *slot; |
594 | if (!prevailing->next) | |
1a735925 RG |
595 | return; |
596 | ||
200c8750 RG |
597 | /* Try to merge each entry with the prevailing one. */ |
598 | for (e = prevailing->next; e; e = e->next) | |
599 | { | |
600 | if (!lto_symtab_merge (prevailing, e)) | |
601 | VEC_safe_push (tree, heap, mismatches, e->decl); | |
602 | } | |
603 | if (VEC_empty (tree, mismatches)) | |
604 | return; | |
1a735925 | 605 | |
200c8750 RG |
606 | /* Diagnose all mismatched re-declarations. */ |
607 | for (i = 0; VEC_iterate (tree, mismatches, i, decl); ++i) | |
1a735925 | 608 | { |
e575382e | 609 | if (TREE_TYPE (prevailing->decl) != TREE_TYPE (decl)) |
200c8750 RG |
610 | diagnosed_p |= warning_at (DECL_SOURCE_LOCATION (decl), 0, |
611 | "type of %qD does not match original " | |
612 | "declaration", decl); | |
613 | ||
614 | else if ((DECL_USER_ALIGN (prevailing->decl) && DECL_USER_ALIGN (decl)) | |
615 | && DECL_ALIGN (prevailing->decl) < DECL_ALIGN (decl)) | |
1a735925 | 616 | { |
200c8750 RG |
617 | diagnosed_p |= warning_at (DECL_SOURCE_LOCATION (decl), 0, |
618 | "alignment of %qD is bigger than " | |
619 | "original declaration", decl); | |
1a735925 | 620 | } |
1a735925 | 621 | } |
200c8750 RG |
622 | if (diagnosed_p) |
623 | inform (DECL_SOURCE_LOCATION (prevailing->decl), | |
624 | "previously declared here"); | |
1a735925 | 625 | |
200c8750 | 626 | VEC_free (tree, heap, mismatches); |
1a735925 RG |
627 | } |
628 | ||
629 | /* Helper to process the decl chain for the symbol table entry *SLOT. */ | |
630 | ||
631 | static int | |
632 | lto_symtab_merge_decls_1 (void **slot, void *data ATTRIBUTE_UNUSED) | |
d7f09764 | 633 | { |
200c8750 RG |
634 | lto_symtab_entry_t e, prevailing; |
635 | bool diagnosed_p = false; | |
1a735925 | 636 | |
200c8750 RG |
637 | /* Compute the symbol resolutions. This is a no-op when using the |
638 | linker plugin. */ | |
1a735925 RG |
639 | lto_symtab_resolve_symbols (slot); |
640 | ||
200c8750 RG |
641 | /* Find the prevailing decl. */ |
642 | for (prevailing = (lto_symtab_entry_t) *slot; | |
643 | prevailing | |
644 | && prevailing->resolution != LDPR_PREVAILING_DEF_IRONLY | |
645 | && prevailing->resolution != LDPR_PREVAILING_DEF; | |
646 | prevailing = prevailing->next) | |
647 | ; | |
648 | ||
649 | /* Assert it's the only one. */ | |
650 | if (prevailing) | |
651 | for (e = prevailing->next; e; e = e->next) | |
e56d9a76 AK |
652 | { |
653 | if (e->resolution == LDPR_PREVAILING_DEF_IRONLY | |
654 | || e->resolution == LDPR_PREVAILING_DEF) | |
655 | fatal_error ("multiple prevailing defs for %qE", | |
656 | DECL_NAME (prevailing->decl)); | |
657 | } | |
200c8750 RG |
658 | |
659 | /* If there's not a prevailing symbol yet it's an external reference. | |
660 | Happens a lot during ltrans. Choose the first symbol with a | |
661 | cgraph or a varpool node. */ | |
662 | if (!prevailing) | |
663 | { | |
664 | prevailing = (lto_symtab_entry_t) *slot; | |
665 | /* For functions choose one with a cgraph node. */ | |
666 | if (TREE_CODE (prevailing->decl) == FUNCTION_DECL) | |
2c928155 | 667 | while (!prevailing->node |
200c8750 RG |
668 | && prevailing->next) |
669 | prevailing = prevailing->next; | |
9e0546ef JH |
670 | /* For variables chose with a priority variant with vnode |
671 | attached (i.e. from unit where external declaration of | |
672 | variable is actually used). | |
673 | When there are multiple variants, chose one with size. | |
674 | This is needed for C++ typeinfos, for example in | |
675 | lto/20081204-1 there are typeifos in both units, just | |
676 | one of them do have size. */ | |
2942c502 | 677 | if (TREE_CODE (prevailing->decl) == VAR_DECL) |
9e0546ef JH |
678 | { |
679 | for (e = prevailing->next; e; e = e->next) | |
680 | if ((!prevailing->vnode && e->vnode) | |
681 | || ((prevailing->vnode != NULL) == (e->vnode != NULL) | |
682 | && !COMPLETE_TYPE_P (TREE_TYPE (prevailing->decl)) | |
683 | && COMPLETE_TYPE_P (TREE_TYPE (e->decl)))) | |
684 | prevailing = e; | |
685 | } | |
200c8750 | 686 | } |
1a735925 | 687 | |
200c8750 RG |
688 | /* Move it first in the list. */ |
689 | if ((lto_symtab_entry_t) *slot != prevailing) | |
690 | { | |
691 | for (e = (lto_symtab_entry_t) *slot; e->next != prevailing; e = e->next) | |
692 | ; | |
693 | e->next = prevailing->next; | |
694 | prevailing->next = (lto_symtab_entry_t) *slot; | |
695 | *slot = (void *) prevailing; | |
696 | } | |
1a735925 | 697 | |
200c8750 RG |
698 | /* Record the prevailing variable. */ |
699 | if (TREE_CODE (prevailing->decl) == VAR_DECL) | |
700 | VEC_safe_push (tree, gc, lto_global_var_decls, prevailing->decl); | |
1a735925 | 701 | |
200c8750 RG |
702 | /* Diagnose mismatched objects. */ |
703 | for (e = prevailing->next; e; e = e->next) | |
704 | { | |
705 | if (TREE_CODE (prevailing->decl) == TREE_CODE (e->decl)) | |
706 | continue; | |
1a735925 | 707 | |
200c8750 RG |
708 | switch (TREE_CODE (prevailing->decl)) |
709 | { | |
710 | case VAR_DECL: | |
711 | gcc_assert (TREE_CODE (e->decl) == FUNCTION_DECL); | |
712 | error_at (DECL_SOURCE_LOCATION (e->decl), | |
713 | "variable %qD redeclared as function", prevailing->decl); | |
714 | break; | |
715 | ||
716 | case FUNCTION_DECL: | |
717 | gcc_assert (TREE_CODE (e->decl) == VAR_DECL); | |
718 | error_at (DECL_SOURCE_LOCATION (e->decl), | |
719 | "function %qD redeclared as variable", prevailing->decl); | |
720 | break; | |
1a735925 | 721 | |
200c8750 RG |
722 | default: |
723 | gcc_unreachable (); | |
724 | } | |
725 | ||
726 | diagnosed_p = true; | |
727 | } | |
728 | if (diagnosed_p) | |
729 | inform (DECL_SOURCE_LOCATION (prevailing->decl), | |
730 | "previously declared here"); | |
731 | ||
732 | /* Register and adjust types of the entries. */ | |
1a735925 | 733 | for (e = (lto_symtab_entry_t) *slot; e; e = e->next) |
200c8750 RG |
734 | TREE_TYPE (e->decl) = gimple_register_type (TREE_TYPE (e->decl)); |
735 | ||
736 | /* Merge the chain to the single prevailing decl and diagnose | |
737 | mismatches. */ | |
738 | lto_symtab_merge_decls_2 (slot); | |
739 | ||
740 | /* Drop all but the prevailing decl from the symtab. */ | |
2942c502 JH |
741 | if (TREE_CODE (prevailing->decl) != FUNCTION_DECL |
742 | && TREE_CODE (prevailing->decl) != VAR_DECL) | |
2c928155 | 743 | prevailing->next = NULL; |
1a735925 | 744 | |
6d41cd02 BM |
745 | /* Set externally_visible flags for declaration of LDPR_PREVAILING_DEF */ |
746 | if (flag_whole_program) | |
747 | { | |
748 | if (prevailing->resolution == LDPR_PREVAILING_DEF) | |
749 | { | |
750 | if (TREE_CODE (prevailing->decl) == FUNCTION_DECL) | |
751 | prevailing->node->local.used_from_object_file = true; | |
752 | else | |
753 | prevailing->vnode->used_from_object_file = true; | |
754 | } | |
755 | else if (prevailing->resolution == LDPR_PREVAILING_DEF_IRONLY) | |
756 | { | |
757 | if (TREE_CODE (prevailing->decl) == FUNCTION_DECL) | |
758 | prevailing->node->local.used_from_object_file = false; | |
759 | else | |
760 | prevailing->vnode->used_from_object_file = false; | |
761 | } | |
762 | } | |
1a735925 | 763 | return 1; |
d7f09764 DN |
764 | } |
765 | ||
1a735925 | 766 | /* Resolve and merge all symbol table chains to a prevailing decl. */ |
d7f09764 DN |
767 | |
768 | void | |
1a735925 | 769 | lto_symtab_merge_decls (void) |
d7f09764 | 770 | { |
1a735925 RG |
771 | lto_symtab_maybe_init_hash_table (); |
772 | htab_traverse (lto_symtab_identifiers, lto_symtab_merge_decls_1, NULL); | |
d7f09764 DN |
773 | } |
774 | ||
2c928155 RG |
775 | /* Helper to process the decl chain for the symbol table entry *SLOT. */ |
776 | ||
777 | static int | |
778 | lto_symtab_merge_cgraph_nodes_1 (void **slot, void *data ATTRIBUTE_UNUSED) | |
779 | { | |
780 | lto_symtab_entry_t e, prevailing = (lto_symtab_entry_t) *slot; | |
781 | ||
782 | if (!prevailing->next) | |
783 | return 1; | |
784 | ||
2c928155 RG |
785 | /* Replace the cgraph node of each entry with the prevailing one. */ |
786 | for (e = prevailing->next; e; e = e->next) | |
787 | { | |
788 | if (e->node != NULL) | |
e10aaec0 | 789 | lto_cgraph_replace_node (e->node, prevailing->node); |
2942c502 JH |
790 | if (e->vnode != NULL) |
791 | lto_varpool_replace_node (e->vnode, prevailing->vnode); | |
2c928155 RG |
792 | } |
793 | ||
794 | /* Drop all but the prevailing decl from the symtab. */ | |
795 | prevailing->next = NULL; | |
796 | ||
797 | return 1; | |
798 | } | |
799 | ||
800 | /* Merge cgraph nodes according to the symbol merging done by | |
801 | lto_symtab_merge_decls. */ | |
802 | ||
803 | void | |
804 | lto_symtab_merge_cgraph_nodes (void) | |
805 | { | |
806 | lto_symtab_maybe_init_hash_table (); | |
807 | htab_traverse (lto_symtab_identifiers, lto_symtab_merge_cgraph_nodes_1, NULL); | |
808 | } | |
1a735925 | 809 | |
d7f09764 DN |
810 | /* Given the decl DECL, return the prevailing decl with the same name. */ |
811 | ||
812 | tree | |
813 | lto_symtab_prevailing_decl (tree decl) | |
814 | { | |
1a735925 | 815 | lto_symtab_entry_t ret; |
d7f09764 DN |
816 | |
817 | /* Builtins and local symbols are their own prevailing decl. */ | |
818 | if (!TREE_PUBLIC (decl) || is_builtin_fn (decl)) | |
819 | return decl; | |
820 | ||
821 | /* DECL_ABSTRACTs are their own prevailng decl. */ | |
822 | if (TREE_CODE (decl) == FUNCTION_DECL && DECL_ABSTRACT (decl)) | |
823 | return decl; | |
824 | ||
825 | /* Ensure DECL_ASSEMBLER_NAME will not set assembler name. */ | |
826 | gcc_assert (DECL_ASSEMBLER_NAME_SET_P (decl)); | |
827 | ||
828 | /* Walk through the list of candidates and return the one we merged to. */ | |
1a735925 RG |
829 | ret = lto_symtab_get (DECL_ASSEMBLER_NAME (decl)); |
830 | if (!ret) | |
831 | return NULL_TREE; | |
832 | ||
200c8750 | 833 | return ret->decl; |
d7f09764 DN |
834 | } |
835 | ||
d7f09764 | 836 | #include "gt-lto-symtab.h" |