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