gcc/symtab.c

   1 /* Symbol table.
   2    Copyright (C) 2012-2013 Free Software Foundation, Inc.
   3    Contributed by Jan Hubicka
   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"
  24 #include "tm.h"
  25 #include "tree.h"
  26 #include "gimple.h"
  27 #include "tree-inline.h"
  28 #include "langhooks.h"
  29 #include "hashtab.h"
  30 #include "ggc.h"
  31 #include "cgraph.h"
  32 #include "diagnostic.h"
  33 #include "timevar.h"
  34 #include "lto-streamer.h"
  35 #include "rtl.h"
  36
  37 const char * const ld_plugin_symbol_resolution_names[]=
  38 {
  39   "",
  40   "undef",
  41   "prevailing_def",
  42   "prevailing_def_ironly",
  43   "preempted_reg",
  44   "preempted_ir",
  45   "resolved_ir",
  46   "resolved_exec",
  47   "resolved_dyn",
  48   "prevailing_def_ironly_exp"
  49 };
  50
  51 /* Hash table used to convert declarations into nodes.  */
  52 static GTY((param_is (symtab_node_base))) htab_t symtab_hash;
  53 /* Hash table used to convert assembler names into nodes.  */
  54 static GTY((param_is (symtab_node_base))) htab_t assembler_name_hash;
  55
  56 /* Linked list of symbol table nodes.  */
  57 symtab_node symtab_nodes;
  58
  59 /* The order index of the next symtab node to be created.  This is
  60    used so that we can sort the cgraph nodes in order by when we saw
  61    them, to support -fno-toplevel-reorder.  */
  62 int symtab_order;
  63
  64 /* Returns a hash code for P.  */
  65
  66 static hashval_t
  67 hash_node (const void *p)
  68 {
  69   const_symtab_node n = (const_symtab_node ) p;
  70   return (hashval_t) DECL_UID (n->decl);
  71 }
  72
  73
  74 /* Returns nonzero if P1 and P2 are equal.  */
  75
  76 static int
  77 eq_node (const void *p1, const void *p2)
  78 {
  79   const_symtab_node n1 = (const_symtab_node) p1;
  80   const_symtab_node n2 = (const_symtab_node) p2;
  81   return DECL_UID (n1->decl) == DECL_UID (n2->decl);
  82 }
  83
  84 /* Returns a hash code for P.  */
  85
  86 static hashval_t
  87 hash_node_by_assembler_name (const void *p)
  88 {
  89   const_symtab_node n = (const_symtab_node) p;
  90   return (hashval_t) decl_assembler_name_hash (DECL_ASSEMBLER_NAME (n->decl));
  91 }
  92
  93 /* Returns nonzero if P1 and P2 are equal.  */
  94
  95 static int
  96 eq_assembler_name (const void *p1, const void *p2)
  97 {
  98   const_symtab_node n1 = (const_symtab_node) p1;
  99   const_tree name = (const_tree)p2;
 100   return (decl_assembler_name_equal (n1->decl, name));
 101 }
 102
 103 /* Insert NODE to assembler name hash.  */
 104
 105 static void
 106 insert_to_assembler_name_hash (symtab_node node, bool with_clones)
 107 {
 108   if (is_a <varpool_node> (node) && DECL_HARD_REGISTER (node->decl))
 109     return;
 110   gcc_checking_assert (!node->previous_sharing_asm_name
 111                        && !node->next_sharing_asm_name);
 112   if (assembler_name_hash)
 113     {
 114       void **aslot;
 115       struct cgraph_node *cnode;
 116       tree decl = node->decl;
 117
 118       tree name = DECL_ASSEMBLER_NAME (node->decl);
 119
 120       aslot = htab_find_slot_with_hash (assembler_name_hash, name,
 121                                         decl_assembler_name_hash (name),
 122                                         INSERT);
 123       gcc_assert (*aslot != node);
 124       node->next_sharing_asm_name = (symtab_node)*aslot;
 125       if (*aslot != NULL)
 126         ((symtab_node)*aslot)->previous_sharing_asm_name = node;
 127       *aslot = node;
 128
 129       /* Update also possible inline clones sharing a decl.  */
 130       cnode = dyn_cast <cgraph_node> (node);
 131       if (cnode && cnode->clones && with_clones)
 132         for (cnode = cnode->clones; cnode; cnode = cnode->next_sibling_clone)
 133           if (cnode->decl == decl)
 134             insert_to_assembler_name_hash (cnode, true);
 135     }
 136
 137 }
 138
 139 /* Remove NODE from assembler name hash.  */
 140
 141 static void
 142 unlink_from_assembler_name_hash (symtab_node node, bool with_clones)
 143 {
 144   if (assembler_name_hash)
 145     {
 146       struct cgraph_node *cnode;
 147       tree decl = node->decl;
 148
 149       if (node->next_sharing_asm_name)
 150         node->next_sharing_asm_name->previous_sharing_asm_name
 151           = node->previous_sharing_asm_name;
 152       if (node->previous_sharing_asm_name)
 153         {
 154           node->previous_sharing_asm_name->next_sharing_asm_name
 155             = node->next_sharing_asm_name;
 156         }
 157       else
 158         {
 159           tree name = DECL_ASSEMBLER_NAME (node->decl);
 160           void **slot;
 161           slot = htab_find_slot_with_hash (assembler_name_hash, name,
 162                                            decl_assembler_name_hash (name),
 163                                            NO_INSERT);
 164           gcc_assert (*slot == node);
 165           if (!node->next_sharing_asm_name)
 166             htab_clear_slot (assembler_name_hash, slot);
 167           else
 168             *slot = node->next_sharing_asm_name;
 169         }
 170       node->next_sharing_asm_name = NULL;
 171       node->previous_sharing_asm_name = NULL;
 172
 173       /* Update also possible inline clones sharing a decl.  */
 174       cnode = dyn_cast <cgraph_node> (node);
 175       if (cnode && cnode->clones && with_clones)
 176         for (cnode = cnode->clones; cnode; cnode = cnode->next_sibling_clone)
 177           if (cnode->decl == decl)
 178             unlink_from_assembler_name_hash (cnode, true);
 179     }
 180 }
 181
 182 /* Arrange node to be first in its entry of assembler_name_hash.  */
 183
 184 void
 185 symtab_prevail_in_asm_name_hash (symtab_node node)
 186 {
 187   unlink_from_assembler_name_hash (node, false);
 188   insert_to_assembler_name_hash (node, false);
 189 }
 190
 191
 192 /* Add node into symbol table.  This function is not used directly, but via
 193    cgraph/varpool node creation routines.  */
 194
 195 void
 196 symtab_register_node (symtab_node node)
 197 {
 198   struct symtab_node_base key;
 199   symtab_node *slot;
 200
 201   node->next = symtab_nodes;
 202   node->previous = NULL;
 203   if (symtab_nodes)
 204     symtab_nodes->previous = node;
 205   symtab_nodes = node;
 206
 207   if (!symtab_hash)
 208     symtab_hash = htab_create_ggc (10, hash_node, eq_node, NULL);
 209   key.decl = node->decl;
 210   slot = (symtab_node *) htab_find_slot (symtab_hash, &key, INSERT);
 211   if (*slot == NULL)
 212     *slot = node;
 213
 214   ipa_empty_ref_list (&node->ref_list);
 215
 216   node->order = symtab_order++;
 217
 218   /* Be sure to do this last; C++ FE might create new nodes via
 219      DECL_ASSEMBLER_NAME langhook!  */
 220   insert_to_assembler_name_hash (node, false);
 221 }
 222
 223 /* Make NODE to be the one symtab hash is pointing to.  Used when reshaping tree
 224    of inline clones.  */
 225
 226 void
 227 symtab_insert_node_to_hashtable (symtab_node node)
 228 {
 229   struct symtab_node_base key;
 230   symtab_node *slot;
 231
 232   if (!symtab_hash)
 233     symtab_hash = htab_create_ggc (10, hash_node, eq_node, NULL);
 234   key.decl = node->decl;
 235   slot = (symtab_node *) htab_find_slot (symtab_hash, &key, INSERT);
 236   *slot = node;
 237 }
 238
 239 /* Remove node from symbol table.  This function is not used directly, but via
 240    cgraph/varpool node removal routines.  */
 241
 242 void
 243 symtab_unregister_node (symtab_node node)
 244 {
 245   void **slot;
 246   ipa_remove_all_references (&node->ref_list);
 247   ipa_remove_all_referring (&node->ref_list);
 248
 249   if (node->same_comdat_group)
 250     {
 251       symtab_node prev;
 252       for (prev = node->same_comdat_group;
 253            prev->same_comdat_group != node;
 254            prev = prev->same_comdat_group)
 255         ;
 256       if (node->same_comdat_group == prev)
 257         prev->same_comdat_group = NULL;
 258       else
 259         prev->same_comdat_group = node->same_comdat_group;
 260       node->same_comdat_group = NULL;
 261     }
 262
 263   if (node->previous)
 264     node->previous->next = node->next;
 265   else
 266     symtab_nodes = node->next;
 267   if (node->next)
 268     node->next->previous = node->previous;
 269   node->next = NULL;
 270   node->previous = NULL;
 271
 272   slot = htab_find_slot (symtab_hash, node, NO_INSERT);
 273
 274   /* During LTO symtab merging we temporarily corrupt decl to symtab node
 275      hash.  */
 276   gcc_assert ((slot && *slot) || in_lto_p);
 277   if (slot && *slot && *slot == node)
 278     {
 279       symtab_node replacement_node = NULL;
 280       if (cgraph_node *cnode = dyn_cast <cgraph_node> (node))
 281         replacement_node = cgraph_find_replacement_node (cnode);
 282       if (!replacement_node)
 283         htab_clear_slot (symtab_hash, slot);
 284       else
 285         *slot = replacement_node;
 286     }
 287   if (!is_a <varpool_node> (node) || !DECL_HARD_REGISTER (node->decl))
 288     unlink_from_assembler_name_hash (node, false);
 289 }
 290
 291 /* Return symbol table node associated with DECL, if any,
 292    and NULL otherwise.  */
 293
 294 symtab_node
 295 symtab_get_node (const_tree decl)
 296 {
 297   symtab_node *slot;
 298   struct symtab_node_base key;
 299
 300 #ifdef ENABLE_CHECKING
 301   /* Check that we are called for sane type of object - functions
 302      and static or external variables.  */
 303   gcc_checking_assert (TREE_CODE (decl) == FUNCTION_DECL
 304                        || (TREE_CODE (decl) == VAR_DECL
 305                            && (TREE_STATIC (decl) || DECL_EXTERNAL (decl)
 306                                || in_lto_p)));
 307 #endif
 308
 309   if (!symtab_hash)
 310     return NULL;
 311
 312   key.decl = CONST_CAST2 (tree, const_tree, decl);
 313
 314   slot = (symtab_node *) htab_find_slot (symtab_hash, &key,
 315                                          NO_INSERT);
 316
 317   if (slot)
 318     return *slot;
 319   return NULL;
 320 }
 321
 322 /* Remove symtab NODE from the symbol table.  */
 323
 324 void
 325 symtab_remove_node (symtab_node node)
 326 {
 327   if (cgraph_node *cnode = dyn_cast <cgraph_node> (node))
 328     cgraph_remove_node (cnode);
 329   else if (varpool_node *vnode = dyn_cast <varpool_node> (node))
 330     varpool_remove_node (vnode);
 331 }
 332
 333 /* Initalize asm name hash unless.  */
 334
 335 void
 336 symtab_initialize_asm_name_hash (void)
 337 {
 338   symtab_node node;
 339   if (!assembler_name_hash)
 340     {
 341       assembler_name_hash =
 342         htab_create_ggc (10, hash_node_by_assembler_name, eq_assembler_name,
 343                          NULL);
 344       FOR_EACH_SYMBOL (node)
 345         insert_to_assembler_name_hash (node, false);
 346     }
 347 }
 348
 349 /* Return the cgraph node that has ASMNAME for its DECL_ASSEMBLER_NAME.
 350    Return NULL if there's no such node.  */
 351
 352 symtab_node
 353 symtab_node_for_asm (const_tree asmname)
 354 {
 355   symtab_node node;
 356   void **slot;
 357
 358   symtab_initialize_asm_name_hash ();
 359   slot = htab_find_slot_with_hash (assembler_name_hash, asmname,
 360                                    decl_assembler_name_hash (asmname),
 361                                    NO_INSERT);
 362
 363   if (slot)
 364     {
 365       node = (symtab_node) *slot;
 366       return node;
 367     }
 368   return NULL;
 369 }
 370
 371 /* Set the DECL_ASSEMBLER_NAME and update symtab hashtables.  */
 372
 373 void
 374 change_decl_assembler_name (tree decl, tree name)
 375 {
 376   symtab_node node = NULL;
 377
 378   /* We can have user ASM names on things, like global register variables, that
 379      are not in the symbol table.  */
 380   if ((TREE_CODE (decl) == VAR_DECL
 381        && (TREE_STATIC (decl) || DECL_EXTERNAL (decl)))
 382       || TREE_CODE (decl) == FUNCTION_DECL)
 383     node = symtab_get_node (decl);
 384   if (!DECL_ASSEMBLER_NAME_SET_P (decl))
 385     {
 386       SET_DECL_ASSEMBLER_NAME (decl, name);
 387       if (node)
 388         insert_to_assembler_name_hash (node, true);
 389     }
 390   else
 391     {
 392       if (name == DECL_ASSEMBLER_NAME (decl))
 393         return;
 394
 395       tree alias = (IDENTIFIER_TRANSPARENT_ALIAS (DECL_ASSEMBLER_NAME (decl))
 396                     ? TREE_CHAIN (DECL_ASSEMBLER_NAME (decl))
 397                     : NULL);
 398       if (node)
 399         unlink_from_assembler_name_hash (node, true);
 400       if (TREE_SYMBOL_REFERENCED (DECL_ASSEMBLER_NAME (decl))
 401           && DECL_RTL_SET_P (decl))
 402         warning (0, "%D renamed after being referenced in assembly", decl);
 403
 404       SET_DECL_ASSEMBLER_NAME (decl, name);
 405       if (alias)
 406         {
 407           IDENTIFIER_TRANSPARENT_ALIAS (name) = 1;
 408           TREE_CHAIN (DECL_ASSEMBLER_NAME (name)) = alias;
 409         }
 410       if (node)
 411         insert_to_assembler_name_hash (node, true);
 412     }
 413 }
 414
 415 /* Add NEW_ to the same comdat group that OLD is in.  */
 416
 417 void
 418 symtab_add_to_same_comdat_group (symtab_node new_node,
 419                                  symtab_node old_node)
 420 {
 421   gcc_assert (DECL_ONE_ONLY (old_node->decl));
 422   gcc_assert (!new_node->same_comdat_group);
 423   gcc_assert (new_node != old_node);
 424
 425   DECL_COMDAT_GROUP (new_node->decl) = DECL_COMDAT_GROUP (old_node->decl);
 426   new_node->same_comdat_group = old_node;
 427   if (!old_node->same_comdat_group)
 428     old_node->same_comdat_group = new_node;
 429   else
 430     {
 431       symtab_node n;
 432       for (n = old_node->same_comdat_group;
 433            n->same_comdat_group != old_node;
 434            n = n->same_comdat_group)
 435         ;
 436       n->same_comdat_group = new_node;
 437     }
 438 }
 439
 440 /* Dissolve the same_comdat_group list in which NODE resides.  */
 441
 442 void
 443 symtab_dissolve_same_comdat_group_list (symtab_node node)
 444 {
 445   symtab_node n = node;
 446   symtab_node next;
 447
 448   if (!node->same_comdat_group)
 449     return;
 450   do
 451     {
 452       next = n->same_comdat_group;
 453       n->same_comdat_group = NULL;
 454       n = next;
 455     }
 456   while (n != node);
 457 }
 458
 459 /* Return printable assembler name of NODE.
 460    This function is used only for debugging.  When assembler name
 461    is unknown go with identifier name.  */
 462
 463 const char *
 464 symtab_node_asm_name (symtab_node node)
 465 {
 466   if (!DECL_ASSEMBLER_NAME_SET_P (node->decl))
 467     return lang_hooks.decl_printable_name (node->decl, 2);
 468   return IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (node->decl));
 469 }
 470
 471 /* Return printable identifier name.  */
 472
 473 const char *
 474 symtab_node_name (symtab_node node)
 475 {
 476   return lang_hooks.decl_printable_name (node->decl, 2);
 477 }
 478
 479 static const char * const symtab_type_names[] = {"symbol", "function", "variable"};
 480
 481 /* Dump base fields of symtab nodes.  Not to be used directly.  */
 482
 483 void
 484 dump_symtab_base (FILE *f, symtab_node node)
 485 {
 486   static const char * const visibility_types[] = {
 487     "default", "protected", "hidden", "internal"
 488   };
 489
 490   fprintf (f, "%s/%i (%s)",
 491            symtab_node_asm_name (node),
 492            node->order,
 493            symtab_node_name (node));
 494   dump_addr (f, " @", (void *)node);
 495   fprintf (f, "\n  Type: %s", symtab_type_names[node->type]);
 496
 497   if (node->definition)
 498     fprintf (f, " definition");
 499   if (node->analyzed)
 500     fprintf (f, " analyzed");
 501   if (node->alias)
 502     fprintf (f, " alias");
 503   if (node->weakref)
 504     fprintf (f, " weakref");
 505   if (node->cpp_implicit_alias)
 506     fprintf (f, " cpp_implicit_alias");
 507   if (node->alias_target)
 508     fprintf (f, " target:%s",
 509              DECL_P (node->alias_target)
 510              ? IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME
 511                                      (node->alias_target))
 512              : IDENTIFIER_POINTER (node->alias_target));
 513   fprintf (f, "\n  Visibility:");
 514   if (node->in_other_partition)
 515     fprintf (f, " in_other_partition");
 516   if (node->used_from_other_partition)
 517     fprintf (f, " used_from_other_partition");
 518   if (node->force_output)
 519     fprintf (f, " force_output");
 520   if (node->forced_by_abi)
 521     fprintf (f, " forced_by_abi");
 522   if (node->externally_visible)
 523     fprintf (f, " externally_visible");
 524   if (node->resolution != LDPR_UNKNOWN)
 525     fprintf (f, " %s",
 526              ld_plugin_symbol_resolution_names[(int)node->resolution]);
 527   if (TREE_ASM_WRITTEN (node->decl))
 528     fprintf (f, " asm_written");
 529   if (DECL_EXTERNAL (node->decl))
 530     fprintf (f, " external");
 531   if (TREE_PUBLIC (node->decl))
 532     fprintf (f, " public");
 533   if (DECL_COMMON (node->decl))
 534     fprintf (f, " common");
 535   if (DECL_WEAK (node->decl))
 536     fprintf (f, " weak");
 537   if (DECL_DLLIMPORT_P (node->decl))
 538     fprintf (f, " dll_import");
 539   if (DECL_COMDAT (node->decl))
 540     fprintf (f, " comdat");
 541   if (DECL_COMDAT_GROUP (node->decl))
 542     fprintf (f, " comdat_group:%s",
 543              IDENTIFIER_POINTER (DECL_COMDAT_GROUP (node->decl)));
 544   if (DECL_ONE_ONLY (node->decl))
 545     fprintf (f, " one_only");
 546   if (DECL_SECTION_NAME (node->decl))
 547     fprintf (f, " section_name:%s",
 548              TREE_STRING_POINTER (DECL_SECTION_NAME (node->decl)));
 549   if (DECL_VISIBILITY_SPECIFIED (node->decl))
 550     fprintf (f, " visibility_specified");
 551   if (DECL_VISIBILITY (node->decl))
 552     fprintf (f, " visibility:%s",
 553              visibility_types [DECL_VISIBILITY (node->decl)]);
 554   if (DECL_VIRTUAL_P (node->decl))
 555     fprintf (f, " virtual");
 556   if (DECL_ARTIFICIAL (node->decl))
 557     fprintf (f, " artificial");
 558   if (TREE_CODE (node->decl) == FUNCTION_DECL)
 559     {
 560       if (DECL_STATIC_CONSTRUCTOR (node->decl))
 561         fprintf (f, " constructor");
 562       if (DECL_STATIC_DESTRUCTOR (node->decl))
 563         fprintf (f, " destructor");
 564     }
 565   fprintf (f, "\n");
 566
 567   if (node->same_comdat_group)
 568     fprintf (f, "  Same comdat group as: %s/%i\n",
 569              symtab_node_asm_name (node->same_comdat_group),
 570              node->same_comdat_group->order);
 571   if (node->next_sharing_asm_name)
 572     fprintf (f, "  next sharing asm name: %i\n",
 573              node->next_sharing_asm_name->order);
 574   if (node->previous_sharing_asm_name)
 575     fprintf (f, "  previous sharing asm name: %i\n",
 576              node->previous_sharing_asm_name->order);
 577
 578   if (node->address_taken)
 579     fprintf (f, "  Address is taken.\n");
 580   if (node->aux)
 581     {
 582       fprintf (f, "  Aux:");
 583       dump_addr (f, " @", (void *)node->aux);
 584     }
 585
 586   fprintf (f, "  References: ");
 587   ipa_dump_references (f, &node->ref_list);
 588   fprintf (f, "  Referring: ");
 589   ipa_dump_referring (f, &node->ref_list);
 590   if (node->lto_file_data)
 591     fprintf (f, "  Read from file: %s\n",
 592              node->lto_file_data->file_name);
 593 }
 594
 595 /* Dump symtab node.  */
 596
 597 void
 598 dump_symtab_node (FILE *f, symtab_node node)
 599 {
 600   if (cgraph_node *cnode = dyn_cast <cgraph_node> (node))
 601     dump_cgraph_node (f, cnode);
 602   else if (varpool_node *vnode = dyn_cast <varpool_node> (node))
 603     dump_varpool_node (f, vnode);
 604 }
 605
 606 /* Dump symbol table.  */
 607
 608 void
 609 dump_symtab (FILE *f)
 610 {
 611   symtab_node node;
 612   fprintf (f, "Symbol table:\n\n");
 613   FOR_EACH_SYMBOL (node)
 614     dump_symtab_node (f, node);
 615 }
 616
 617 /* Dump symtab node NODE to stderr.  */
 618
 619 DEBUG_FUNCTION void
 620 debug_symtab_node (symtab_node node)
 621 {
 622   dump_symtab_node (stderr, node);
 623 }
 624
 625 /* Dump symbol table to stderr.  */
 626
 627 DEBUG_FUNCTION void
 628 debug_symtab (void)
 629 {
 630   dump_symtab (stderr);
 631 }
 632
 633 /* Verify common part of symtab nodes.  */
 634
 635 DEBUG_FUNCTION bool
 636 verify_symtab_base (symtab_node node)
 637 {
 638   bool error_found = false;
 639   symtab_node hashed_node;
 640
 641   if (is_a <cgraph_node> (node))
 642     {
 643       if (TREE_CODE (node->decl) != FUNCTION_DECL)
 644         {
 645           error ("function symbol is not function");
 646           error_found = true;
 647         }
 648     }
 649   else if (is_a <varpool_node> (node))
 650     {
 651       if (TREE_CODE (node->decl) != VAR_DECL)
 652         {
 653           error ("variable symbol is not variable");
 654           error_found = true;
 655         }
 656     }
 657   else
 658     {
 659       error ("node has unknown type");
 660       error_found = true;
 661     }
 662
 663   if (cgraph_state != CGRAPH_LTO_STREAMING)
 664     {
 665       hashed_node = symtab_get_node (node->decl);
 666       if (!hashed_node)
 667         {
 668           error ("node not found in symtab decl hashtable");
 669           error_found = true;
 670         }
 671       if (hashed_node != node
 672           && (!is_a <cgraph_node> (node)
 673               || !dyn_cast <cgraph_node> (node)->clone_of
 674               || dyn_cast <cgraph_node> (node)->clone_of->decl
 675                  != node->decl))
 676         {
 677           error ("node differs from symtab decl hashtable");
 678           error_found = true;
 679         }
 680     }
 681   if (assembler_name_hash)
 682     {
 683       hashed_node = symtab_node_for_asm (DECL_ASSEMBLER_NAME (node->decl));
 684       if (hashed_node && hashed_node->previous_sharing_asm_name)
 685         {
 686           error ("assembler name hash list corrupted");
 687           error_found = true;
 688         }
 689       while (hashed_node)
 690         {
 691           if (hashed_node == node)
 692             break;
 693           hashed_node = hashed_node->next_sharing_asm_name;
 694         }
 695       if (!hashed_node
 696           && !(is_a <varpool_node> (node)
 697                || DECL_HARD_REGISTER (node->decl)))
 698         {
 699           error ("node not found in symtab assembler name hash");
 700           error_found = true;
 701         }
 702     }
 703   if (node->previous_sharing_asm_name
 704       && node->previous_sharing_asm_name->next_sharing_asm_name != node)
 705     {
 706       error ("double linked list of assembler names corrupted");
 707       error_found = true;
 708     }
 709   if (node->analyzed && !node->definition)
 710     {
 711       error ("node is analyzed byt it is not a definition");
 712       error_found = true;
 713     }
 714   if (node->cpp_implicit_alias && !node->alias)
 715     {
 716       error ("node is alias but not implicit alias");
 717       error_found = true;
 718     }
 719   if (node->alias && !node->definition
 720       && !node->weakref)
 721     {
 722       error ("node is alias but not definition");
 723       error_found = true;
 724     }
 725   if (node->weakref && !node->alias)
 726     {
 727       error ("node is weakref but not an alias");
 728       error_found = true;
 729     }
 730   if (node->same_comdat_group)
 731     {
 732       symtab_node n = node->same_comdat_group;
 733
 734       if (!DECL_ONE_ONLY (n->decl))
 735         {
 736           error ("non-DECL_ONE_ONLY node in a same_comdat_group list");
 737           error_found = true;
 738         }
 739       if (n->type != node->type)
 740         {
 741           error ("mixing different types of symbol in same comdat groups is not supported");
 742           error_found = true;
 743         }
 744       if (n == node)
 745         {
 746           error ("node is alone in a comdat group");
 747           error_found = true;
 748         }
 749       do
 750         {
 751           if (!n->same_comdat_group)
 752             {
 753               error ("same_comdat_group is not a circular list");
 754               error_found = true;
 755               break;
 756             }
 757           n = n->same_comdat_group;
 758         }
 759       while (n != node);
 760     }
 761   return error_found;
 762 }
 763
 764 /* Verify consistency of NODE.  */
 765
 766 DEBUG_FUNCTION void
 767 verify_symtab_node (symtab_node node)
 768 {
 769   if (seen_error ())
 770     return;
 771
 772   timevar_push (TV_CGRAPH_VERIFY);
 773   if (cgraph_node *cnode = dyn_cast <cgraph_node> (node))
 774     verify_cgraph_node (cnode);
 775   else
 776     if (verify_symtab_base (node))
 777       {
 778         dump_symtab_node (stderr, node);
 779         internal_error ("verify_symtab_node failed");
 780       }
 781   timevar_pop (TV_CGRAPH_VERIFY);
 782 }
 783
 784 /* Verify symbol table for internal consistency.  */
 785
 786 DEBUG_FUNCTION void
 787 verify_symtab (void)
 788 {
 789   symtab_node node;
 790   FOR_EACH_SYMBOL (node)
 791    verify_symtab_node (node);
 792 }
 793
 794 /* Return true when RESOLUTION indicate that linker will use
 795    the symbol from non-LTO object files.  */
 796
 797 bool
 798 resolution_used_from_other_file_p (enum ld_plugin_symbol_resolution resolution)
 799 {
 800   return (resolution == LDPR_PREVAILING_DEF
 801           || resolution == LDPR_PREEMPTED_REG
 802           || resolution == LDPR_RESOLVED_EXEC
 803           || resolution == LDPR_RESOLVED_DYN);
 804 }
 805
 806 /* Return true when NODE is known to be used from other (non-LTO) object file.
 807    Known only when doing LTO via linker plugin.  */
 808
 809 bool
 810 symtab_used_from_object_file_p (symtab_node node)
 811 {
 812   if (!TREE_PUBLIC (node->decl) || DECL_EXTERNAL (node->decl))
 813     return false;
 814   if (resolution_used_from_other_file_p (node->resolution))
 815     return true;
 816   return false;
 817 }
 818
 819 /* Make DECL local.  FIXME: We shouldn't need to mess with rtl this early,
 820    but other code such as notice_global_symbol generates rtl.  */
 821
 822 void
 823 symtab_make_decl_local (tree decl)
 824 {
 825   rtx rtl, symbol;
 826
 827   if (TREE_CODE (decl) == VAR_DECL)
 828     DECL_COMMON (decl) = 0;
 829   else gcc_assert (TREE_CODE (decl) == FUNCTION_DECL);
 830
 831   if (DECL_ONE_ONLY (decl) || DECL_COMDAT (decl))
 832     {
 833       DECL_SECTION_NAME (decl) = 0;
 834       DECL_COMDAT (decl) = 0;
 835     }
 836   DECL_COMDAT_GROUP (decl) = 0;
 837   DECL_WEAK (decl) = 0;
 838   DECL_EXTERNAL (decl) = 0;
 839   DECL_VISIBILITY_SPECIFIED (decl) = 0;
 840   DECL_VISIBILITY (decl) = VISIBILITY_DEFAULT;
 841   TREE_PUBLIC (decl) = 0;
 842   if (!DECL_RTL_SET_P (decl))
 843     return;
 844
 845   /* Update rtl flags.  */
 846   make_decl_rtl (decl);
 847
 848   rtl = DECL_RTL (decl);
 849   if (!MEM_P (rtl))
 850     return;
 851
 852   symbol = XEXP (rtl, 0);
 853   if (GET_CODE (symbol) != SYMBOL_REF)
 854     return;
 855
 856   SYMBOL_REF_WEAK (symbol) = DECL_WEAK (decl);
 857 }
 858
 859 /* Return availability of NODE.  */
 860
 861 enum availability
 862 symtab_node_availability (symtab_node node)
 863 {
 864   if (is_a <cgraph_node> (node))
 865     return cgraph_function_body_availability (cgraph (node));
 866   else
 867     return cgraph_variable_initializer_availability (varpool (node));
 868 }
 869
 870 /* Given NODE, walk the alias chain to return the symbol NODE is alias of.
 871    If NODE is not an alias, return NODE.
 872    When AVAILABILITY is non-NULL, get minimal availability in the chain.  */
 873
 874 symtab_node
 875 symtab_alias_ultimate_target (symtab_node node, enum availability *availability)
 876 {
 877   bool weakref_p = false;
 878
 879   if (!node->alias)
 880     {
 881       if (availability)
 882         *availability = symtab_node_availability (node);
 883       return node;
 884     }
 885
 886   /* To determine visibility of the target, we follow ELF semantic of aliases.
 887      Here alias is an alternative assembler name of a given definition. Its
 888      availability prevails the availability of its target (i.e. static alias of
 889      weak definition is available.
 890
 891      Weakref is a different animal (and not part of ELF per se). It is just
 892      alternative name of a given symbol used within one complation unit
 893      and is translated prior hitting the object file.  It inherits the
 894      visibility of its target (i.e. weakref of non-overwritable definition
 895      is non-overwritable, while weakref of weak definition is weak).
 896
 897      If we ever get into supporting targets with different semantics, a target
 898      hook will be needed here.  */
 899
 900   if (availability)
 901     {
 902       weakref_p = node->weakref;
 903       if (!weakref_p)
 904         *availability = symtab_node_availability (node);
 905       else
 906         *availability = AVAIL_LOCAL;
 907     }
 908   while (node)
 909     {
 910       if (node->alias && node->analyzed)
 911         node = symtab_alias_target (node);
 912       else
 913         {
 914           if (!availability)
 915             ;
 916           else if (node->analyzed)
 917             {
 918               if (weakref_p)
 919                 {
 920                   enum availability a = symtab_node_availability (node);
 921                   if (a < *availability)
 922                     *availability = a;
 923                 }
 924             }
 925           else
 926             *availability = AVAIL_NOT_AVAILABLE;
 927           return node;
 928         }
 929       if (node && availability && weakref_p)
 930         {
 931           enum availability a = symtab_node_availability (node);
 932           if (a < *availability)
 933             *availability = a;
 934           weakref_p = node->weakref;
 935         }
 936     }
 937   if (availability)
 938     *availability = AVAIL_NOT_AVAILABLE;
 939   return NULL;
 940 }
 941
 942 /* C++ FE sometimes change linkage flags after producing same body aliases.
 943
 944    FIXME: C++ produce implicit aliases for virtual functions and vtables that
 945    are obviously equivalent.  The way it is doing so is however somewhat
 946    kludgy and interferes with the visibility code. As a result we need to
 947    copy the visibility from the target to get things right.  */
 948
 949 void
 950 fixup_same_cpp_alias_visibility (symtab_node node, symtab_node target)
 951 {
 952   if (is_a <cgraph_node> (node))
 953     {
 954       DECL_DECLARED_INLINE_P (node->decl)
 955          = DECL_DECLARED_INLINE_P (target->decl);
 956       DECL_DISREGARD_INLINE_LIMITS (node->decl)
 957          = DECL_DISREGARD_INLINE_LIMITS (target->decl);
 958     }
 959   /* FIXME: It is not really clear why those flags should not be copied for
 960      functions, too.  */
 961   else
 962     {
 963       DECL_WEAK (node->decl) = DECL_WEAK (target->decl);
 964       DECL_EXTERNAL (node->decl) = DECL_EXTERNAL (target->decl);
 965       DECL_VISIBILITY (node->decl) = DECL_VISIBILITY (target->decl);
 966     }
 967   DECL_VIRTUAL_P (node->decl) = DECL_VIRTUAL_P (target->decl);
 968   if (TREE_PUBLIC (node->decl))
 969     {
 970       DECL_EXTERNAL (node->decl) = DECL_EXTERNAL (target->decl);
 971       DECL_COMDAT (node->decl) = DECL_COMDAT (target->decl);
 972       DECL_COMDAT_GROUP (node->decl)
 973          = DECL_COMDAT_GROUP (target->decl);
 974       if (DECL_ONE_ONLY (target->decl)
 975           && !node->same_comdat_group)
 976         symtab_add_to_same_comdat_group (node, target);
 977     }
 978   node->externally_visible = target->externally_visible;
 979 }
 980
 981 /* Add reference recording that NODE is alias of TARGET.
 982    The function can fail in the case of aliasing cycles; in this case
 983    it returns false.  */
 984
 985 bool
 986 symtab_resolve_alias (symtab_node node, symtab_node target)
 987 {
 988   symtab_node n;
 989
 990   gcc_assert (!node->analyzed
 991               && !vec_safe_length (node->ref_list.references));
 992
 993   /* Never let cycles to creep into the symbol table alias references;
 994      those will make alias walkers to be infinite.  */
 995   for (n = target; n && n->alias;
 996        n = n->analyzed ? symtab_alias_target (n) : NULL)
 997     if (n == node)
 998        {
 999          if (is_a <cgraph_node> (node))
1000            error ("function %q+D part of alias cycle", node->decl);
1001          else if (is_a <varpool_node> (node))
1002            error ("variable %q+D part of alias cycle", node->decl);
1003          else
1004            gcc_unreachable ();
1005          node->alias = false;
1006          return false;
1007        }
1008
1009   /* "analyze" the node - i.e. mark the reference.  */
1010   node->definition = true;
1011   node->alias = true;
1012   node->analyzed = true;
1013   ipa_record_reference (node, target, IPA_REF_ALIAS, NULL);
1014
1015   /* Alias targets become reudndant after alias is resolved into an reference.
1016      We do not want to keep it around or we would have to mind updating them
1017      when renaming symbols.  */
1018   node->alias_target = NULL;
1019
1020   if (node->cpp_implicit_alias && cgraph_state >= CGRAPH_STATE_CONSTRUCTION)
1021     fixup_same_cpp_alias_visibility (node, target);
1022
1023   /* If alias has address taken, so does the target.  */
1024   if (node->address_taken)
1025     symtab_alias_ultimate_target (target, NULL)->address_taken = true;
1026   return true;
1027 }
1028
1029 /* Call calback on NODE and aliases associated to NODE.
1030    When INCLUDE_OVERWRITABLE is false, overwritable aliases and thunks are
1031    skipped. */
1032
1033 bool
1034 symtab_for_node_and_aliases (symtab_node node,
1035                              bool (*callback) (symtab_node, void *),
1036                              void *data,
1037                              bool include_overwritable)
1038 {
1039   int i;
1040   struct ipa_ref *ref;
1041
1042   if (callback (node, data))
1043     return true;
1044   for (i = 0; ipa_ref_list_referring_iterate (&node->ref_list, i, ref); i++)
1045     if (ref->use == IPA_REF_ALIAS)
1046       {
1047         symtab_node alias = ref->referring;
1048         if (include_overwritable
1049             || symtab_node_availability (alias) > AVAIL_OVERWRITABLE)
1050           if (symtab_for_node_and_aliases (alias, callback, data,
1051                                            include_overwritable))
1052             return true;
1053       }
1054   return false;
1055 }
1056
1057 /* Worker searching nonoverwritable alias.  */
1058
1059 static bool
1060 symtab_nonoverwritable_alias_1 (symtab_node node, void *data)
1061 {
1062   if (decl_binds_to_current_def_p (node->decl))
1063     {
1064       *(symtab_node *)data = node;
1065       return true;
1066     }
1067   return false;
1068 }
1069
1070 /* If NODE can not be overwriten by static or dynamic linker to point to different
1071    definition, return NODE. Otherwise look for alias with such property and if
1072    none exists, introduce new one.  */
1073
1074 symtab_node
1075 symtab_nonoverwritable_alias (symtab_node node)
1076 {
1077   tree new_decl;
1078   symtab_node new_node = NULL;
1079
1080   /* First try to look up existing alias or base object
1081      (if that is already non-overwritable).  */
1082   node = symtab_alias_ultimate_target (node, NULL);
1083   gcc_assert (!node->alias && !node->weakref);
1084   symtab_for_node_and_aliases (node, symtab_nonoverwritable_alias_1,
1085                                (void *)&new_node, true);
1086   if (new_node)
1087     return new_node;
1088 #ifndef ASM_OUTPUT_DEF
1089   /* If aliases aren't supported by the assembler, fail.  */
1090   return NULL;
1091 #endif
1092
1093   /* Otherwise create a new one.  */
1094   new_decl = copy_node (node->decl);
1095   DECL_NAME (new_decl) = clone_function_name (node->decl, "localalias");
1096   if (TREE_CODE (new_decl) == FUNCTION_DECL)
1097     DECL_STRUCT_FUNCTION (new_decl) = NULL;
1098   DECL_INITIAL (new_decl) = NULL;
1099   SET_DECL_ASSEMBLER_NAME (new_decl, DECL_NAME (new_decl));
1100   SET_DECL_RTL (new_decl, NULL);
1101
1102   /* Update the properties.  */
1103   DECL_EXTERNAL (new_decl) = 0;
1104   if (DECL_ONE_ONLY (node->decl))
1105     DECL_SECTION_NAME (new_decl) = NULL;
1106   DECL_COMDAT_GROUP (new_decl) = 0;
1107   TREE_PUBLIC (new_decl) = 0;
1108   DECL_COMDAT (new_decl) = 0;
1109   DECL_WEAK (new_decl) = 0;
1110   DECL_VIRTUAL_P (new_decl) = 0;
1111   if (TREE_CODE (new_decl) == FUNCTION_DECL)
1112     {
1113       DECL_STATIC_CONSTRUCTOR (new_decl) = 0;
1114       DECL_STATIC_DESTRUCTOR (new_decl) = 0;
1115       new_node = cgraph_create_function_alias
1116                                  (new_decl, node->decl);
1117     }
1118   else
1119     new_node = varpool_create_variable_alias (new_decl,
1120                                                             node->decl);
1121   symtab_resolve_alias (new_node, node);
1122   gcc_assert (decl_binds_to_current_def_p (new_decl));
1123   return new_node;
1124 }
1125
1126 /* Return true if A and B represents semantically equivalent symbols.  */
1127
1128 bool
1129 symtab_semantically_equivalent_p (symtab_node a,
1130                                   symtab_node b)
1131 {
1132   enum availability avail;
1133   symtab_node ba;
1134   symtab_node bb;
1135
1136   /* Equivalent functions are equivalent.  */
1137   if (a->decl == b->decl)
1138     return true;
1139
1140   /* If symbol is not overwritable by different implementation,
1141      walk to the base object it defines.  */
1142   ba = symtab_alias_ultimate_target (a, &avail);
1143   if (avail >= AVAIL_AVAILABLE)
1144     {
1145       if (ba == b)
1146         return true;
1147     }
1148   else
1149     ba = a;
1150   bb = symtab_alias_ultimate_target (b, &avail);
1151   if (avail >= AVAIL_AVAILABLE)
1152     {
1153       if (a == bb)
1154         return true;
1155     }
1156   else
1157     bb = b;
1158   return bb == ba;
1159 }
1160 #include "gt-symtab.h"