1/* LTO symbol table. 2 Copyright 2009 Free Software Foundation, Inc. 3 Contributed by CodeSourcery, Inc. 4 5This file is part of GCC. 6 7GCC is free software; you can redistribute it and/or modify it under 8the terms of the GNU General Public License as published by the Free 9Software Foundation; either version 3, or (at your option) any later 10version. 11 12GCC is distributed in the hope that it will be useful, but WITHOUT ANY 13WARRANTY; without even the implied warranty of MERCHANTABILITY or 14FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 15for more details. 16 17You should have received a copy of the GNU General Public License 18along 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" 24#include "toplev.h" 25#include "tree.h" 26#include "gimple.h" 27#include "ggc.h" /* lambda.h needs this */ 28#include "lambda.h" /* gcd */ 29#include "hashtab.h" 30#include "plugin-api.h" 31#include "lto-streamer.h" 32 33/* Vector to keep track of external variables we've seen so far. */ 34VEC(tree,gc) *lto_global_var_decls; 35 36/* Symbol table entry. */ 37 38struct GTY(()) lto_symtab_entry_def 39{ 40 /* The symbol table entry key, an IDENTIFIER. */ 41 tree id; 42 /* The symbol table entry, a DECL. */ 43 tree decl; 44 /* The cgraph node if decl is a function decl. Filled in during the 45 merging process. */ 46 struct cgraph_node *node; 47 /* LTO file-data and symbol resolution for this decl. */ 48 struct lto_file_decl_data * GTY((skip (""))) file_data; 49 enum ld_plugin_symbol_resolution resolution; 50 /* Pointer to the next entry with the same key. Before decl merging 51 this links all symbols from the different TUs. After decl merging 52 this links merged but incompatible decls, thus all prevailing ones 53 remaining. */ 54 struct lto_symtab_entry_def *next; 55}; 56typedef struct lto_symtab_entry_def *lto_symtab_entry_t; 57 58/* A poor man's symbol table. This hashes identifier to prevailing DECL 59 if there is one. */ 60 61static GTY ((if_marked ("lto_symtab_entry_marked_p"), 62 param_is (struct lto_symtab_entry_def))) 63 htab_t lto_symtab_identifiers; 64 65/* Return the hash value of an lto_symtab_entry_t object pointed to by P. */ 66 67static hashval_t 68lto_symtab_entry_hash (const void *p) 69{ 70 const struct lto_symtab_entry_def *base = 71 (const struct lto_symtab_entry_def *) p; 72 return htab_hash_string (IDENTIFIER_POINTER (base->id)); 73} 74 75/* Return non-zero if P1 and P2 points to lto_symtab_entry_def structs 76 corresponding to the same symbol. */ 77 78static int 79lto_symtab_entry_eq (const void *p1, const void *p2) 80{ 81 const struct lto_symtab_entry_def *base1 = 82 (const struct lto_symtab_entry_def *) p1; 83 const struct lto_symtab_entry_def *base2 = 84 (const struct lto_symtab_entry_def *) p2; 85 return (base1->id == base2->id); 86} 87 88/* Returns non-zero if P points to an lto_symtab_entry_def struct that needs 89 to be marked for GC. */ 90 91static int 92lto_symtab_entry_marked_p (const void *p) 93{ 94 const struct lto_symtab_entry_def *base = 95 (const struct lto_symtab_entry_def *) p; 96 97 /* Keep this only if the common IDENTIFIER_NODE of the symtab chain 98 is marked which it will be if at least one of the DECLs in the 99 chain is marked. */ 100 return ggc_marked_p (base->id); 101} 102 103/* Lazily initialize resolution hash tables. */ 104 105static void 106lto_symtab_maybe_init_hash_table (void) 107{ 108 if (lto_symtab_identifiers) 109 return; 110 111 lto_symtab_identifiers = 112 htab_create_ggc (1021, lto_symtab_entry_hash, 113 lto_symtab_entry_eq, NULL); 114} 115 116/* Registers DECL with the LTO symbol table as having resolution RESOLUTION 117 and read from FILE_DATA. */ 118 119void 120lto_symtab_register_decl (tree decl, 121 ld_plugin_symbol_resolution_t resolution, 122 struct lto_file_decl_data *file_data) 123{ 124 lto_symtab_entry_t new_entry; 125 void **slot; 126 127 /* Check that declarations reaching this function do not have 128 properties inconsistent with having external linkage. If any of 129 these asertions fail, then the object file reader has failed to 130 detect these cases and issue appropriate error messages. */ 131 gcc_assert (decl 132 && TREE_PUBLIC (decl) 133 && (TREE_CODE (decl) == VAR_DECL 134 || TREE_CODE (decl) == FUNCTION_DECL) 135 && DECL_ASSEMBLER_NAME_SET_P (decl)); 136 if (TREE_CODE (decl) == VAR_DECL 137 && DECL_INITIAL (decl)) 138 gcc_assert (!DECL_EXTERNAL (decl) 139 || (TREE_STATIC (decl) && TREE_READONLY (decl))); 140 if (TREE_CODE (decl) == FUNCTION_DECL) 141 gcc_assert (!DECL_ABSTRACT (decl)); 142 143 new_entry = GGC_CNEW (struct lto_symtab_entry_def); 144 new_entry->id = DECL_ASSEMBLER_NAME (decl); 145 new_entry->decl = decl; 146 new_entry->resolution = resolution; 147 new_entry->file_data = file_data; 148 149 lto_symtab_maybe_init_hash_table (); 150 slot = htab_find_slot (lto_symtab_identifiers, new_entry, INSERT); 151 new_entry->next = (lto_symtab_entry_t) *slot; 152 *slot = new_entry; 153} 154 155/* Get the lto_symtab_entry_def struct associated with ID 156 if there is one. */ 157 158static lto_symtab_entry_t 159lto_symtab_get (tree id) 160{ 161 struct lto_symtab_entry_def temp; 162 void **slot; 163 164 lto_symtab_maybe_init_hash_table (); 165 temp.id = id; 166 slot = htab_find_slot (lto_symtab_identifiers, &temp, NO_INSERT); 167 return slot ? (lto_symtab_entry_t) *slot : NULL; 168} 169 170/* Get the linker resolution for DECL. */ 171 172enum ld_plugin_symbol_resolution 173lto_symtab_get_resolution (tree decl) 174{ 175 lto_symtab_entry_t e; 176 177 gcc_assert (DECL_ASSEMBLER_NAME_SET_P (decl)); 178 179 e = lto_symtab_get (DECL_ASSEMBLER_NAME (decl)); 180 while (e && e->decl != decl) 181 e = e->next; 182 if (!e) 183 return LDPR_UNKNOWN; 184 185 return e->resolution; 186} 187 188 189/* Replace the cgraph node NODE with PREVAILING_NODE in the cgraph, merging 190 all edges and removing the old node. */ 191 192static void 193lto_cgraph_replace_node (struct cgraph_node *node, 194 struct cgraph_node *prevailing_node) 195{ 196 struct cgraph_edge *e, *next; 197 198 /* Merge node flags. */ 199 if (node->needed) 200 cgraph_mark_needed_node (prevailing_node); 201 if (node->reachable) 202 cgraph_mark_reachable_node (prevailing_node); 203 if (node->address_taken) 204 { 205 gcc_assert (!prevailing_node->global.inlined_to); 206 cgraph_mark_address_taken_node (prevailing_node); 207 } 208 209 /* Redirect all incoming edges. */ 210 for (e = node->callers; e; e = next) 211 { 212 next = e->next_caller; 213 cgraph_redirect_edge_callee (e, prevailing_node); 214 } 215 216 /* There are not supposed to be any outgoing edges from a node we 217 replace. Still this can happen for multiple instances of weak 218 functions. */ 219 for (e = node->callees; e; e = next) 220 { 221 next = e->next_callee; 222 cgraph_remove_edge (e); 223 } 224 225 if (node->same_body) 226 { 227 struct cgraph_node *alias; 228 229 for (alias = node->same_body; alias; alias = alias->next) 230 if (DECL_ASSEMBLER_NAME_SET_P (alias->decl)) 231 { 232 lto_symtab_entry_t se 233 = lto_symtab_get (DECL_ASSEMBLER_NAME (alias->decl)); 234 235 for (; se; se = se->next) 236 if (se->node == node) 237 { 238 se->node = NULL; 239 break; 240 } 241 } 242 } 243 244 /* Finally remove the replaced node. */ 245 cgraph_remove_node (node); 246} 247 248/* Merge two variable or function symbol table entries PREVAILING and ENTRY. 249 Return false if the symbols are not fully compatible and a diagnostic 250 should be emitted. */ 251 252static bool 253lto_symtab_merge (lto_symtab_entry_t prevailing, lto_symtab_entry_t entry) 254{ 255 tree prevailing_decl = prevailing->decl; 256 tree decl = entry->decl; 257 tree prevailing_type, type; 258 259 /* Merge decl state in both directions, we may still end up using 260 the new decl. */ 261 TREE_ADDRESSABLE (prevailing_decl) |= TREE_ADDRESSABLE (decl); 262 TREE_ADDRESSABLE (decl) |= TREE_ADDRESSABLE (prevailing_decl); 263 264 /* The linker may ask us to combine two incompatible symbols. 265 Detect this case and notify the caller of required diagnostics. */ 266 267 if (TREE_CODE (decl) == FUNCTION_DECL) 268 { 269 if (TREE_TYPE (prevailing_decl) != TREE_TYPE (decl)) 270 /* If we don't have a merged type yet...sigh. The linker 271 wouldn't complain if the types were mismatched, so we 272 probably shouldn't either. Just use the type from 273 whichever decl appears to be associated with the 274 definition. If for some odd reason neither decl is, the 275 older one wins. */ 276 (void) 0; 277 278 return true; 279 } 280 281 /* Now we exclusively deal with VAR_DECLs. */ 282 283 /* Sharing a global symbol is a strong hint that two types are 284 compatible. We could use this information to complete 285 incomplete pointed-to types more aggressively here, ignoring 286 mismatches in both field and tag names. It's difficult though 287 to guarantee that this does not have side-effects on merging 288 more compatible types from other translation units though. */ 289 290 /* We can tolerate differences in type qualification, the 291 qualification of the prevailing definition will prevail. 292 ??? In principle we might want to only warn for structurally 293 incompatible types here, but unless we have protective measures 294 for TBAA in place that would hide useful information. */ 295 prevailing_type = TYPE_MAIN_VARIANT (TREE_TYPE (prevailing_decl)); 296 type = TYPE_MAIN_VARIANT (TREE_TYPE (decl)); 297 298 /* We have to register and fetch canonical types here as the global 299 fixup process didn't yet run. */ 300 prevailing_type = gimple_register_type (prevailing_type); 301 type = gimple_register_type (type); 302 if (prevailing_type != type) 303 { 304 if (COMPLETE_TYPE_P (type)) 305 return false; 306 307 /* If type is incomplete then avoid warnings in the cases 308 that TBAA handles just fine. */ 309 310 if (TREE_CODE (prevailing_type) != TREE_CODE (type)) 311 return false; 312 313 if (TREE_CODE (prevailing_type) == ARRAY_TYPE) 314 { 315 tree tem1 = TREE_TYPE (prevailing_type); 316 tree tem2 = TREE_TYPE (type); 317 while (TREE_CODE (tem1) == ARRAY_TYPE 318 && TREE_CODE (tem2) == ARRAY_TYPE) 319 { 320 tem1 = TREE_TYPE (tem1); 321 tem2 = TREE_TYPE (tem2); 322 } 323 324 if (TREE_CODE (tem1) != TREE_CODE (tem2)) 325 return false; 326 327 if (gimple_register_type (tem1) != gimple_register_type (tem2)) 328 return false; 329 } 330 331 /* Fallthru. Compatible enough. */ 332 } 333 334 /* ??? We might want to emit a warning here if type qualification 335 differences were spotted. Do not do this unconditionally though. */ 336 337 /* There is no point in comparing too many details of the decls here. 338 The type compatibility checks or the completing of types has properly 339 dealt with most issues. */ 340 341 /* The following should all not invoke fatal errors as in non-LTO 342 mode the linker wouldn't complain either. Just emit warnings. */ 343 344 /* Report a warning if user-specified alignments do not match. */ 345 if ((DECL_USER_ALIGN (prevailing_decl) && DECL_USER_ALIGN (decl)) 346 && DECL_ALIGN (prevailing_decl) < DECL_ALIGN (decl)) 347 return false; 348 349 return true; 350} 351 352/* Return true if the symtab entry E can be replaced by another symtab 353 entry. */ 354 355static bool 356lto_symtab_resolve_replaceable_p (lto_symtab_entry_t e) 357{ 358 if (DECL_EXTERNAL (e->decl) 359 || DECL_COMDAT (e->decl) 360 || DECL_WEAK (e->decl)) 361 return true; 362 363 if (TREE_CODE (e->decl) == VAR_DECL) 364 return (DECL_COMMON (e->decl) 365 || (!flag_no_common && !DECL_INITIAL (e->decl))); 366 367 return false; 368} 369 370/* Return true if the symtab entry E can be the prevailing one. */ 371 372static bool 373lto_symtab_resolve_can_prevail_p (lto_symtab_entry_t e) 374{ 375 /* The C++ frontend ends up neither setting TREE_STATIC nor 376 DECL_EXTERNAL on virtual methods but only TREE_PUBLIC. 377 So do not reject !TREE_STATIC here but only DECL_EXTERNAL. */ 378 if (DECL_EXTERNAL (e->decl)) 379 return false; 380 381 /* For functions we need a non-discarded body. */ 382 if (TREE_CODE (e->decl) == FUNCTION_DECL) 383 return (e->node && e->node->analyzed); 384 385 /* A variable should have a size. */ 386 else if (TREE_CODE (e->decl) == VAR_DECL) 387 return (DECL_SIZE (e->decl) != NULL_TREE 388 /* The C++ frontend retains TREE_STATIC on the declaration 389 of foo_ in struct Foo { static Foo *foo_; }; but it is 390 not a definition. g++.dg/lto/20090315_0.C. */ 391 && !DECL_EXTERNAL (e->decl)); 392 393 gcc_unreachable (); 394} 395 396/* Resolve the symbol with the candidates in the chain *SLOT and store 397 their resolutions. */ 398 399static void 400lto_symtab_resolve_symbols (void **slot) 401{ 402 lto_symtab_entry_t e; 403 lto_symtab_entry_t prevailing = NULL; 404 405 /* Always set e->node so that edges are updated to reflect decl merging. */ 406 for (e = (lto_symtab_entry_t) *slot; e; e = e->next) 407 { 408 if (TREE_CODE (e->decl) == FUNCTION_DECL) 409 e->node = cgraph_get_node (e->decl); 410 else if (TREE_CODE (e->decl) == VAR_DECL) 411 { 412 /* The LTO plugin for gold doesn't handle common symbols 413 properly. Let us choose manually. */ 414 if (DECL_COMMON (e->decl)) 415 e->resolution = LDPR_UNKNOWN; 416 } 417 } 418 419 e = (lto_symtab_entry_t) *slot; 420 421 /* If the chain is already resolved there is nothing else to do. */ 422 if (e->resolution != LDPR_UNKNOWN) 423 return; 424 425 /* Find the single non-replaceable prevailing symbol and 426 diagnose ODR violations. */ 427 for (e = (lto_symtab_entry_t) *slot; e; e = e->next) 428 { 429 if (!lto_symtab_resolve_can_prevail_p (e)) 430 { 431 e->resolution = LDPR_RESOLVED_IR; 432 continue; 433 } 434 435 /* Set a default resolution - the final prevailing one will get 436 adjusted later. */ 437 e->resolution = LDPR_PREEMPTED_IR; 438 if (!lto_symtab_resolve_replaceable_p (e)) 439 { 440 if (prevailing) 441 { 442 error_at (DECL_SOURCE_LOCATION (e->decl), 443 "%qD has already been defined", e->decl); 444 inform (DECL_SOURCE_LOCATION (prevailing->decl), 445 "previously defined here"); 446 } 447 prevailing = e; 448 } 449 } 450 if (prevailing) 451 goto found; 452 453 /* Do a second round choosing one from the replaceable prevailing decls. */ 454 for (e = (lto_symtab_entry_t) *slot; e; e = e->next) 455 { 456 if (e->resolution != LDPR_PREEMPTED_IR) 457 continue; 458 459 /* Choose the first function that can prevail as prevailing. */ 460 if (TREE_CODE (e->decl) == FUNCTION_DECL) 461 { 462 prevailing = e; 463 break; 464 } 465 466 /* From variables that can prevail choose the largest one. */ 467 if (!prevailing 468 || tree_int_cst_lt (DECL_SIZE (prevailing->decl), 469 DECL_SIZE (e->decl))) 470 prevailing = e; 471 } 472 473 if (!prevailing) 474 return; 475 476found: 477 if (TREE_CODE (prevailing->decl) == VAR_DECL 478 && TREE_READONLY (prevailing->decl)) 479 prevailing->resolution = LDPR_PREVAILING_DEF_IRONLY; 480 else 481 prevailing->resolution = LDPR_PREVAILING_DEF; 482} 483 484/* Merge all decls in the symbol table chain to the prevailing decl and 485 issue diagnostics about type mismatches. */ 486 487static void 488lto_symtab_merge_decls_2 (void **slot) 489{ 490 lto_symtab_entry_t prevailing, e; 491 VEC(tree, heap) *mismatches = NULL; 492 unsigned i; 493 tree decl; 494 bool diagnosed_p = false; 495 496 /* Nothing to do for a single entry. */ 497 prevailing = (lto_symtab_entry_t) *slot; 498 if (!prevailing->next) 499 return; 500 501 /* Try to merge each entry with the prevailing one. */ 502 for (e = prevailing->next; e; e = e->next) 503 { 504 if (!lto_symtab_merge (prevailing, e)) 505 VEC_safe_push (tree, heap, mismatches, e->decl); 506 } 507 if (VEC_empty (tree, mismatches)) 508 return; 509 510 /* Diagnose all mismatched re-declarations. */ 511 for (i = 0; VEC_iterate (tree, mismatches, i, decl); ++i) 512 { 513 if (TREE_TYPE (prevailing->decl) != TREE_TYPE (decl)) 514 diagnosed_p |= warning_at (DECL_SOURCE_LOCATION (decl), 0, 515 "type of %qD does not match original " 516 "declaration", decl); 517 518 else if ((DECL_USER_ALIGN (prevailing->decl) && DECL_USER_ALIGN (decl)) 519 && DECL_ALIGN (prevailing->decl) < DECL_ALIGN (decl)) 520 { 521 diagnosed_p |= warning_at (DECL_SOURCE_LOCATION (decl), 0, 522 "alignment of %qD is bigger than " 523 "original declaration", decl); 524 } 525 } 526 if (diagnosed_p) 527 inform (DECL_SOURCE_LOCATION (prevailing->decl), 528 "previously declared here"); 529 530 VEC_free (tree, heap, mismatches); 531} 532 533/* Helper to process the decl chain for the symbol table entry *SLOT. */ 534 535static int 536lto_symtab_merge_decls_1 (void **slot, void *data ATTRIBUTE_UNUSED) 537{ 538 lto_symtab_entry_t e, prevailing; 539 bool diagnosed_p = false; 540 541 /* Compute the symbol resolutions. This is a no-op when using the 542 linker plugin. */ 543 lto_symtab_resolve_symbols (slot); 544 545 /* Find the prevailing decl. */ 546 for (prevailing = (lto_symtab_entry_t) *slot; 547 prevailing 548 && prevailing->resolution != LDPR_PREVAILING_DEF_IRONLY 549 && prevailing->resolution != LDPR_PREVAILING_DEF; 550 prevailing = prevailing->next) 551 ; 552 553 /* Assert it's the only one. */ 554 if (prevailing) 555 for (e = prevailing->next; e; e = e->next) 556 gcc_assert (e->resolution != LDPR_PREVAILING_DEF_IRONLY 557 && e->resolution != LDPR_PREVAILING_DEF); 558 559 /* If there's not a prevailing symbol yet it's an external reference. 560 Happens a lot during ltrans. Choose the first symbol with a 561 cgraph or a varpool node. */ 562 if (!prevailing) 563 { 564 prevailing = (lto_symtab_entry_t) *slot; 565 /* For functions choose one with a cgraph node. */ 566 if (TREE_CODE (prevailing->decl) == FUNCTION_DECL) 567 while (!prevailing->node 568 && prevailing->next) 569 prevailing = prevailing->next; 570 /* We do not stream varpool nodes, so the first decl has to 571 be good enough for now. 572 ??? For QOI choose a variable with readonly initializer 573 if there is one. This matches C++ 574 struct Foo { static const int i = 1; }; without a real 575 definition. */ 576 if (TREE_CODE (prevailing->decl) == VAR_DECL) 577 while (!(TREE_READONLY (prevailing->decl) 578 && DECL_INITIAL (prevailing->decl)) 579 && prevailing->next) 580 prevailing = prevailing->next; 581 } 582 583 /* Move it first in the list. */ 584 if ((lto_symtab_entry_t) *slot != prevailing) 585 { 586 for (e = (lto_symtab_entry_t) *slot; e->next != prevailing; e = e->next) 587 ; 588 e->next = prevailing->next; 589 prevailing->next = (lto_symtab_entry_t) *slot; 590 *slot = (void *) prevailing; 591 } 592 593 /* Record the prevailing variable. */ 594 if (TREE_CODE (prevailing->decl) == VAR_DECL) 595 VEC_safe_push (tree, gc, lto_global_var_decls, prevailing->decl); 596 597 /* Diagnose mismatched objects. */ 598 for (e = prevailing->next; e; e = e->next) 599 { 600 if (TREE_CODE (prevailing->decl) == TREE_CODE (e->decl)) 601 continue; 602 603 switch (TREE_CODE (prevailing->decl)) 604 { 605 case VAR_DECL: 606 gcc_assert (TREE_CODE (e->decl) == FUNCTION_DECL); 607 error_at (DECL_SOURCE_LOCATION (e->decl), 608 "variable %qD redeclared as function", prevailing->decl); 609 break; 610 611 case FUNCTION_DECL: 612 gcc_assert (TREE_CODE (e->decl) == VAR_DECL); 613 error_at (DECL_SOURCE_LOCATION (e->decl), 614 "function %qD redeclared as variable", prevailing->decl); 615 break; 616 617 default: 618 gcc_unreachable (); 619 } 620 621 diagnosed_p = true; 622 } 623 if (diagnosed_p) 624 inform (DECL_SOURCE_LOCATION (prevailing->decl), 625 "previously declared here"); 626 627 /* Register and adjust types of the entries. */ 628 for (e = (lto_symtab_entry_t) *slot; e; e = e->next) 629 TREE_TYPE (e->decl) = gimple_register_type (TREE_TYPE (e->decl)); 630 631 /* Merge the chain to the single prevailing decl and diagnose 632 mismatches. */ 633 lto_symtab_merge_decls_2 (slot); 634 635 /* Drop all but the prevailing decl from the symtab. */ 636 if (TREE_CODE (prevailing->decl) != FUNCTION_DECL) 637 prevailing->next = NULL; 638 639 return 1; 640} 641 642/* Resolve and merge all symbol table chains to a prevailing decl. */ 643 644void 645lto_symtab_merge_decls (void) 646{ 647 lto_symtab_maybe_init_hash_table (); 648 htab_traverse (lto_symtab_identifiers, lto_symtab_merge_decls_1, NULL); 649} 650 651/* Helper to process the decl chain for the symbol table entry *SLOT. */ 652 653static int 654lto_symtab_merge_cgraph_nodes_1 (void **slot, void *data ATTRIBUTE_UNUSED) 655{ 656 lto_symtab_entry_t e, prevailing = (lto_symtab_entry_t) *slot; 657 658 if (!prevailing->next) 659 return 1; 660 661 gcc_assert (TREE_CODE (prevailing->decl) == FUNCTION_DECL); 662 663 /* Replace the cgraph node of each entry with the prevailing one. */ 664 for (e = prevailing->next; e; e = e->next) 665 { 666 if (e->node != NULL) 667 { 668 if (e->node->decl != e->decl && e->node->same_body) 669 { 670 struct cgraph_node *alias; 671 672 for (alias = e->node->same_body; alias; alias = alias->next) 673 if (alias->decl == e->decl) 674 break; 675 if (alias) 676 { 677 cgraph_remove_same_body_alias (alias); 678 continue; 679 } 680 } 681 lto_cgraph_replace_node (e->node, prevailing->node); 682 } 683 } 684 685 /* Drop all but the prevailing decl from the symtab. */ 686 prevailing->next = NULL; 687 688 return 1; 689} 690 691/* Merge cgraph nodes according to the symbol merging done by 692 lto_symtab_merge_decls. */ 693 694void 695lto_symtab_merge_cgraph_nodes (void) 696{ 697 lto_symtab_maybe_init_hash_table (); 698 htab_traverse (lto_symtab_identifiers, lto_symtab_merge_cgraph_nodes_1, NULL); 699} 700 701/* Given the decl DECL, return the prevailing decl with the same name. */ 702 703tree 704lto_symtab_prevailing_decl (tree decl) 705{ 706 lto_symtab_entry_t ret; 707 708 /* Builtins and local symbols are their own prevailing decl. */ 709 if (!TREE_PUBLIC (decl) || is_builtin_fn (decl)) 710 return decl; 711 712 /* DECL_ABSTRACTs are their own prevailng decl. */ 713 if (TREE_CODE (decl) == FUNCTION_DECL && DECL_ABSTRACT (decl)) 714 return decl; 715 716 /* Ensure DECL_ASSEMBLER_NAME will not set assembler name. */ 717 gcc_assert (DECL_ASSEMBLER_NAME_SET_P (decl)); 718 719 /* Walk through the list of candidates and return the one we merged to. */ 720 ret = lto_symtab_get (DECL_ASSEMBLER_NAME (decl)); 721 if (!ret) 722 return NULL_TREE; 723 724 return ret->decl; 725} 726 727#include "gt-lto-symtab.h" 728