gcc/varpool.c

   1 /* Callgraph handling code.
   2    Copyright (C) 2003, 2004, 2005, 2006, 2007, 2008, 2010, 2011
   3    Free Software Foundation, Inc.
   4    Contributed by Jan Hubicka
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it under
   9 the terms of the GNU General Public License as published by the Free
  10 Software Foundation; either version 3, or (at your option) any later
  11 version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  14 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "tree.h"
  27 #include "cgraph.h"
  28 #include "langhooks.h"
  29 #include "diagnostic-core.h"
  30 #include "hashtab.h"
  31 #include "ggc.h"
  32 #include "timevar.h"
  33 #include "debug.h"
  34 #include "target.h"
  35 #include "output.h"
  36 #include "gimple.h"
  37 #include "tree-flow.h"
  38 #include "flags.h"
  39
  40 /*  This file contains basic routines manipulating variable pool.
  41
  42     Varpool acts as interface in between the front-end and middle-end
  43     and drives the decision process on what variables and when are
  44     going to be compiled.
  45
  46     The varpool nodes are allocated lazily for declarations
  47     either by frontend or at callgraph construction time.
  48     All variables supposed to be output into final file needs to be
  49     explicitly marked by frontend via VARPOOL_FINALIZE_DECL function.  */
  50
  51 /* Hash table used to convert declarations into nodes.  */
  52 static GTY((param_is (struct varpool_node))) htab_t varpool_hash;
  53
  54 /* The linked list of cgraph varpool nodes.
  55    Linked via node->next pointer.  */
  56 struct varpool_node *varpool_nodes;
  57
  58 /* Queue of cgraph nodes scheduled to be lowered and output.
  59    The queue is maintained via mark_needed_node, linked via node->next_needed
  60    pointer.
  61
  62    LAST_NEEDED_NODE points to the end of queue, so it can be
  63    maintained in forward order.  GTY is needed to make it friendly to
  64    PCH.
  65
  66    During compilation we construct the queue of needed variables
  67    twice: first time it is during cgraph construction, second time it is at the
  68    end of compilation in VARPOOL_REMOVE_UNREFERENCED_DECLS so we can avoid
  69    optimized out variables being output.
  70
  71    Each variable is thus first analyzed and then later possibly output.
  72    FIRST_UNANALYZED_NODE points to first node in queue that was not analyzed
  73    yet and is moved via VARPOOL_ANALYZE_PENDING_DECLS.  */
  74
  75 struct varpool_node *varpool_nodes_queue;
  76 static GTY(()) struct varpool_node *varpool_last_needed_node;
  77 static GTY(()) struct varpool_node *varpool_first_unanalyzed_node;
  78
  79 /* Lists all assembled variables to be sent to debugger output later on.  */
  80 static GTY(()) struct varpool_node *varpool_assembled_nodes_queue;
  81
  82 /* Return name of the node used in debug output.  */
  83 const char *
  84 varpool_node_name (struct varpool_node *node)
  85 {
  86   return lang_hooks.decl_printable_name (node->decl, 2);
  87 }
  88
  89 /* Returns a hash code for P.  */
  90 static hashval_t
  91 hash_varpool_node (const void *p)
  92 {
  93   const struct varpool_node *n = (const struct varpool_node *) p;
  94   return (hashval_t) DECL_UID (n->decl);
  95 }
  96
  97 /* Returns nonzero if P1 and P2 are equal.  */
  98 static int
  99 eq_varpool_node (const void *p1, const void *p2)
 100 {
 101   const struct varpool_node *n1 =
 102     (const struct varpool_node *) p1;
 103   const struct varpool_node *n2 =
 104     (const struct varpool_node *) p2;
 105   return DECL_UID (n1->decl) == DECL_UID (n2->decl);
 106 }
 107
 108 /* Return varpool node assigned to DECL without creating new one.  */
 109 struct varpool_node *
 110 varpool_get_node (const_tree decl)
 111 {
 112   struct varpool_node key, **slot;
 113
 114   gcc_assert (TREE_CODE (decl) == VAR_DECL
 115               && (TREE_STATIC (decl) || DECL_EXTERNAL (decl)));
 116
 117   if (!varpool_hash)
 118     return NULL;
 119   key.decl = CONST_CAST2 (tree, const_tree, decl);
 120   slot = (struct varpool_node **)
 121     htab_find_slot (varpool_hash, &key, NO_INSERT);
 122   if (!slot)
 123     return NULL;
 124   return *slot;
 125 }
 126
 127 /* Return varpool node assigned to DECL.  Create new one when needed.  */
 128 struct varpool_node *
 129 varpool_node (tree decl)
 130 {
 131   struct varpool_node key, *node, **slot;
 132
 133   gcc_assert (TREE_CODE (decl) == VAR_DECL
 134               && (TREE_STATIC (decl) || DECL_EXTERNAL (decl) || in_lto_p));
 135
 136   if (!varpool_hash)
 137     varpool_hash = htab_create_ggc (10, hash_varpool_node,
 138                                            eq_varpool_node, NULL);
 139   key.decl = decl;
 140   slot = (struct varpool_node **)
 141     htab_find_slot (varpool_hash, &key, INSERT);
 142   if (*slot)
 143     return *slot;
 144   node = ggc_alloc_cleared_varpool_node ();
 145   node->decl = decl;
 146   node->order = cgraph_order++;
 147   node->next = varpool_nodes;
 148   ipa_empty_ref_list (&node->ref_list);
 149   if (varpool_nodes)
 150     varpool_nodes->prev = node;
 151   varpool_nodes = node;
 152   *slot = node;
 153   return node;
 154 }
 155
 156 /* Remove node from the varpool.  */
 157 void
 158 varpool_remove_node (struct varpool_node *node)
 159 {
 160   void **slot;
 161   slot = htab_find_slot (varpool_hash, node, NO_INSERT);
 162   gcc_assert (*slot == node);
 163   htab_clear_slot (varpool_hash, slot);
 164   gcc_assert (!varpool_assembled_nodes_queue);
 165   if (node->next)
 166     node->next->prev = node->prev;
 167   if (node->prev)
 168     node->prev->next = node->next;
 169   else
 170     {
 171       gcc_assert (varpool_nodes == node);
 172       varpool_nodes = node->next;
 173     }
 174   if (varpool_first_unanalyzed_node == node)
 175     varpool_first_unanalyzed_node = node->next_needed;
 176   if (node->next_needed)
 177     node->next_needed->prev_needed = node->prev_needed;
 178   else if (node->prev_needed)
 179     {
 180       gcc_assert (varpool_last_needed_node);
 181       varpool_last_needed_node = node->prev_needed;
 182     }
 183   if (node->prev_needed)
 184     node->prev_needed->next_needed = node->next_needed;
 185   else if (node->next_needed)
 186     {
 187       gcc_assert (varpool_nodes_queue == node);
 188       varpool_nodes_queue = node->next_needed;
 189     }
 190   if (node->same_comdat_group)
 191     {
 192       struct varpool_node *prev;
 193       for (prev = node->same_comdat_group;
 194            prev->same_comdat_group != node;
 195            prev = prev->same_comdat_group)
 196         ;
 197       if (node->same_comdat_group == prev)
 198         prev->same_comdat_group = NULL;
 199       else
 200         prev->same_comdat_group = node->same_comdat_group;
 201       node->same_comdat_group = NULL;
 202     }
 203   ipa_remove_all_references (&node->ref_list);
 204   ipa_remove_all_refering (&node->ref_list);
 205   ggc_free (node);
 206 }
 207
 208 /* Dump given cgraph node.  */
 209 void
 210 dump_varpool_node (FILE *f, struct varpool_node *node)
 211 {
 212   fprintf (f, "%s:", varpool_node_name (node));
 213   fprintf (f, " availability:%s",
 214            cgraph_function_flags_ready
 215            ? cgraph_availability_names[cgraph_variable_initializer_availability (node)]
 216            : "not-ready");
 217   if (DECL_ASSEMBLER_NAME_SET_P (node->decl))
 218     fprintf (f, " (asm: %s)", IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (node->decl)));
 219   if (DECL_INITIAL (node->decl))
 220     fprintf (f, " initialized");
 221   if (TREE_ASM_WRITTEN (node->decl))
 222     fprintf (f, " (asm written)");
 223   if (node->needed)
 224     fprintf (f, " needed");
 225   if (node->analyzed)
 226     fprintf (f, " analyzed");
 227   if (node->finalized)
 228     fprintf (f, " finalized");
 229   if (node->output)
 230     fprintf (f, " output");
 231   if (node->externally_visible)
 232     fprintf (f, " externally_visible");
 233   if (node->resolution != LDPR_UNKNOWN)
 234     fprintf (f, " %s",
 235              ld_plugin_symbol_resolution_names[(int)node->resolution]);
 236   if (node->in_other_partition)
 237     fprintf (f, " in_other_partition");
 238   else if (node->used_from_other_partition)
 239     fprintf (f, " used_from_other_partition");
 240   fprintf (f, "\n");
 241   fprintf (f, "  References: ");
 242   ipa_dump_references (f, &node->ref_list);
 243   fprintf (f, "  Refering this var: ");
 244   ipa_dump_refering (f, &node->ref_list);
 245 }
 246
 247 /* Dump the variable pool.  */
 248 void
 249 dump_varpool (FILE *f)
 250 {
 251   struct varpool_node *node;
 252
 253   fprintf (f, "variable pool:\n\n");
 254   for (node = varpool_nodes; node; node = node->next)
 255     dump_varpool_node (f, node);
 256 }
 257
 258 /* Dump the variable pool to stderr.  */
 259
 260 DEBUG_FUNCTION void
 261 debug_varpool (void)
 262 {
 263   dump_varpool (stderr);
 264 }
 265
 266 /* Given an assembler name, lookup node.  */
 267 struct varpool_node *
 268 varpool_node_for_asm (tree asmname)
 269 {
 270   struct varpool_node *node;
 271
 272   for (node = varpool_nodes; node ; node = node->next)
 273     if (decl_assembler_name_equal (node->decl, asmname))
 274       return node;
 275
 276   return NULL;
 277 }
 278
 279 /* Helper function for finalization code - add node into lists so it will
 280    be analyzed and compiled.  */
 281 static void
 282 varpool_enqueue_needed_node (struct varpool_node *node)
 283 {
 284   if (varpool_last_needed_node)
 285     {
 286       varpool_last_needed_node->next_needed = node;
 287       node->prev_needed = varpool_last_needed_node;
 288     }
 289   varpool_last_needed_node = node;
 290   node->next_needed = NULL;
 291   if (!varpool_nodes_queue)
 292     varpool_nodes_queue = node;
 293   if (!varpool_first_unanalyzed_node)
 294     varpool_first_unanalyzed_node = node;
 295   notice_global_symbol (node->decl);
 296 }
 297
 298 /* Notify finalize_compilation_unit that given node is reachable
 299    or needed.  */
 300 void
 301 varpool_mark_needed_node (struct varpool_node *node)
 302 {
 303   if (!node->needed && node->finalized
 304       && !TREE_ASM_WRITTEN (node->decl))
 305     varpool_enqueue_needed_node (node);
 306   node->needed = 1;
 307 }
 308
 309 /* Reset the queue of needed nodes.  */
 310 void
 311 varpool_reset_queue (void)
 312 {
 313   varpool_last_needed_node = NULL;
 314   varpool_nodes_queue = NULL;
 315   varpool_first_unanalyzed_node = NULL;
 316 }
 317
 318 /* Determine if variable DECL is needed.  That is, visible to something
 319    either outside this translation unit, something magic in the system
 320    configury */
 321 bool
 322 decide_is_variable_needed (struct varpool_node *node, tree decl)
 323 {
 324   /* If the user told us it is used, then it must be so.  */
 325   if (node->force_output)
 326     return true;
 327
 328   gcc_assert (!DECL_EXTERNAL (decl));
 329
 330   /* Externally visible variables must be output.  The exception is
 331      COMDAT variables that must be output only when they are needed.  */
 332   if (TREE_PUBLIC (decl)
 333       && !DECL_COMDAT (decl)
 334       && !DECL_EXTERNAL (decl))
 335     return true;
 336
 337   /* When not reordering top level variables, we have to assume that
 338      we are going to keep everything.  */
 339   if (!flag_toplevel_reorder)
 340     return true;
 341   return false;
 342 }
 343
 344 /* Return if DECL is constant and its initial value is known (so we can do
 345    constant folding using DECL_INITIAL (decl)).  */
 346
 347 bool
 348 const_value_known_p (tree decl)
 349 {
 350   if (TREE_CODE (decl) != VAR_DECL
 351       &&TREE_CODE (decl) != CONST_DECL)
 352     return false;
 353
 354   if (TREE_CODE (decl) == CONST_DECL
 355       || DECL_IN_CONSTANT_POOL (decl))
 356     return true;
 357
 358   gcc_assert (TREE_CODE (decl) == VAR_DECL);
 359
 360   if (!TREE_READONLY (decl) || TREE_THIS_VOLATILE (decl))
 361     return false;
 362
 363   /* Gimplifier takes away constructors of local vars  */
 364   if (!TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
 365     return DECL_INITIAL (decl) != NULL;
 366
 367   gcc_assert (TREE_STATIC (decl) || DECL_EXTERNAL (decl));
 368
 369   /* Variables declared 'const' without an initializer
 370      have zero as the initializer if they may not be
 371      overridden at link or run time.  */
 372   if (!DECL_INITIAL (decl)
 373       && (DECL_EXTERNAL (decl)
 374           || decl_replaceable_p (decl)))
 375     return false;
 376
 377   /* Variables declared `const' with an initializer are considered
 378      to not be overwritable with different initializer by default.
 379
 380      ??? Previously we behaved so for scalar variables but not for array
 381      accesses.  */
 382   return true;
 383 }
 384
 385 /* Mark DECL as finalized.  By finalizing the declaration, frontend instruct the
 386    middle end to output the variable to asm file, if needed or externally
 387    visible.  */
 388 void
 389 varpool_finalize_decl (tree decl)
 390 {
 391   struct varpool_node *node = varpool_node (decl);
 392
 393   gcc_assert (TREE_STATIC (decl));
 394
 395   /* The first declaration of a variable that comes through this function
 396      decides whether it is global (in C, has external linkage)
 397      or local (in C, has internal linkage).  So do nothing more
 398      if this function has already run.  */
 399   if (node->finalized)
 400     {
 401       if (cgraph_global_info_ready)
 402         varpool_assemble_pending_decls ();
 403       return;
 404     }
 405   if (node->needed)
 406     varpool_enqueue_needed_node (node);
 407   node->finalized = true;
 408   if (TREE_THIS_VOLATILE (decl) || DECL_PRESERVE_P (decl))
 409     node->force_output = true;
 410
 411   if (decide_is_variable_needed (node, decl))
 412     varpool_mark_needed_node (node);
 413   if (cgraph_global_info_ready)
 414     varpool_assemble_pending_decls ();
 415 }
 416
 417 /* Return variable availability.  See cgraph.h for description of individual
 418    return values.  */
 419 enum availability
 420 cgraph_variable_initializer_availability (struct varpool_node *node)
 421 {
 422   gcc_assert (cgraph_function_flags_ready);
 423   if (!node->finalized)
 424     return AVAIL_NOT_AVAILABLE;
 425   if (!TREE_PUBLIC (node->decl))
 426     return AVAIL_AVAILABLE;
 427   /* If the variable can be overwritten, return OVERWRITABLE.  Takes
 428      care of at least two notable extensions - the COMDAT variables
 429      used to share template instantiations in C++.  */
 430   if (!decl_replaceable_p (node->decl))
 431     return AVAIL_OVERWRITABLE;
 432   return AVAIL_AVAILABLE;
 433 }
 434
 435 /* Walk the decls we marked as necessary and see if they reference new
 436    variables or functions and add them into the worklists.  */
 437 bool
 438 varpool_analyze_pending_decls (void)
 439 {
 440   bool changed = false;
 441
 442   timevar_push (TV_VARPOOL);
 443   while (varpool_first_unanalyzed_node)
 444     {
 445       struct varpool_node *node = varpool_first_unanalyzed_node, *next;
 446       tree decl = node->decl;
 447       bool analyzed = node->analyzed;
 448
 449       varpool_first_unanalyzed_node->analyzed = true;
 450
 451       varpool_first_unanalyzed_node = varpool_first_unanalyzed_node->next_needed;
 452
 453       /* When reading back varpool at LTO time, we re-construct the queue in order
 454          to have "needed" list right by inserting all needed nodes into varpool.
 455          We however don't want to re-analyze already analyzed nodes.  */
 456       if (!analyzed)
 457         {
 458           gcc_assert (!in_lto_p || cgraph_function_flags_ready);
 459           /* Compute the alignment early so function body expanders are
 460              already informed about increased alignment.  */
 461           align_variable (decl, 0);
 462         }
 463       if (node->alias && node->alias_of)
 464         {
 465           struct varpool_node *tgt = varpool_node (node->alias_of);
 466           if (!VEC_length (ipa_ref_t, node->ref_list.references))
 467             ipa_record_reference (NULL, node, NULL, tgt, IPA_REF_ALIAS, NULL);
 468           /* C++ FE sometimes change linkage flags after producing same body aliases.  */
 469           if (node->extra_name_alias)
 470             {
 471               DECL_WEAK (node->decl) = DECL_WEAK (node->alias_of);
 472               TREE_PUBLIC (node->decl) = TREE_PUBLIC (node->alias_of);
 473               DECL_VISIBILITY (node->decl) = DECL_VISIBILITY (node->alias_of);
 474               if (TREE_PUBLIC (node->decl))
 475                 {
 476                   DECL_COMDAT (node->decl) = DECL_COMDAT (node->alias_of);
 477                   DECL_COMDAT_GROUP (node->decl) = DECL_COMDAT_GROUP (node->alias_of);
 478                   if (DECL_ONE_ONLY (node->alias_of) && !node->same_comdat_group)
 479                     {
 480                       node->same_comdat_group = tgt;
 481                       if (!tgt->same_comdat_group)
 482                         tgt->same_comdat_group = node;
 483                       else
 484                         {
 485                           struct varpool_node *n;
 486                           for (n = tgt->same_comdat_group;
 487                                n->same_comdat_group != tgt;
 488                                n = n->same_comdat_group)
 489                             ;
 490                           n->same_comdat_group = node;
 491                         }
 492                     }
 493                 }
 494             }
 495         }
 496       else if (DECL_INITIAL (decl))
 497         record_references_in_initializer (decl, analyzed);
 498       if (node->same_comdat_group)
 499         {
 500           for (next = node->same_comdat_group;
 501                next != node;
 502                next = next->same_comdat_group)
 503             varpool_mark_needed_node (next);
 504         }
 505       changed = true;
 506     }
 507   timevar_pop (TV_VARPOOL);
 508   return changed;
 509 }
 510
 511 /* Assemble thunks and aliases asociated to NODE.  */
 512
 513 static void
 514 assemble_aliases (struct varpool_node *node)
 515 {
 516   int i;
 517   struct ipa_ref *ref;
 518   for (i = 0; ipa_ref_list_refering_iterate (&node->ref_list, i, ref); i++)
 519     if (ref->use == IPA_REF_ALIAS)
 520       {
 521         struct varpool_node *alias = ipa_ref_refering_varpool_node (ref);
 522         assemble_alias (alias->decl,
 523                         DECL_ASSEMBLER_NAME (alias->alias_of));
 524         assemble_aliases (alias);
 525       }
 526 }
 527
 528 /* Output one variable, if necessary.  Return whether we output it.  */
 529 bool
 530 varpool_assemble_decl (struct varpool_node *node)
 531 {
 532   tree decl = node->decl;
 533
 534   if (!TREE_ASM_WRITTEN (decl)
 535       && !node->alias
 536       && !node->in_other_partition
 537       && !DECL_EXTERNAL (decl)
 538       && (TREE_CODE (decl) != VAR_DECL || !DECL_HAS_VALUE_EXPR_P (decl)))
 539     {
 540       assemble_variable (decl, 0, 1, 0);
 541       if (TREE_ASM_WRITTEN (decl))
 542         {
 543           node->next_needed = varpool_assembled_nodes_queue;
 544           node->prev_needed = NULL;
 545           if (varpool_assembled_nodes_queue)
 546             varpool_assembled_nodes_queue->prev_needed = node;
 547           varpool_assembled_nodes_queue = node;
 548           node->finalized = 1;
 549           assemble_aliases (node);
 550           return true;
 551         }
 552     }
 553
 554   return false;
 555 }
 556
 557 /* Optimization of function bodies might've rendered some variables as
 558    unnecessary so we want to avoid these from being compiled.
 559
 560    This is done by pruning the queue and keeping only the variables that
 561    really appear needed (ie they are either externally visible or referenced
 562    by compiled function). Re-doing the reachability analysis on variables
 563    brings back the remaining variables referenced by these.  */
 564 void
 565 varpool_remove_unreferenced_decls (void)
 566 {
 567   struct varpool_node *next, *node = varpool_nodes_queue;
 568
 569   varpool_reset_queue ();
 570
 571   if (seen_error ())
 572     return;
 573
 574   while (node)
 575     {
 576       next = node->next_needed;
 577       node->needed = 0;
 578
 579       if (node->analyzed
 580           && (!varpool_can_remove_if_no_refs (node)
 581               /* We just expanded all function bodies.  See if any of
 582                  them needed the variable.  */
 583               || DECL_RTL_SET_P (node->decl)))
 584         varpool_mark_needed_node (node);
 585
 586       node = next;
 587     }
 588   /* Make sure we mark alias targets as used targets.  */
 589   finish_aliases_1 ();
 590   varpool_analyze_pending_decls ();
 591 }
 592
 593 /* For variables in named sections make sure get_variable_section
 594    is called before we switch to those sections.  Then section
 595    conflicts between read-only and read-only requiring relocations
 596    sections can be resolved.  */
 597 void
 598 varpool_finalize_named_section_flags (struct varpool_node *node)
 599 {
 600   if (!TREE_ASM_WRITTEN (node->decl)
 601       && !node->alias
 602       && !node->in_other_partition
 603       && !DECL_EXTERNAL (node->decl)
 604       && TREE_CODE (node->decl) == VAR_DECL
 605       && !DECL_HAS_VALUE_EXPR_P (node->decl)
 606       && DECL_SECTION_NAME (node->decl))
 607     get_variable_section (node->decl, false);
 608 }
 609
 610 /* Output all variables enqueued to be assembled.  */
 611 bool
 612 varpool_assemble_pending_decls (void)
 613 {
 614   bool changed = false;
 615   struct varpool_node *node;
 616
 617   if (seen_error ())
 618     return false;
 619
 620   timevar_push (TV_VAROUT);
 621   /* EH might mark decls as needed during expansion.  This should be safe since
 622      we don't create references to new function, but it should not be used
 623      elsewhere.  */
 624   varpool_analyze_pending_decls ();
 625
 626   for (node = varpool_nodes_queue; node; node = node->next_needed)
 627     varpool_finalize_named_section_flags (node);
 628
 629   while (varpool_nodes_queue)
 630     {
 631       struct varpool_node *node = varpool_nodes_queue;
 632
 633       varpool_nodes_queue = varpool_nodes_queue->next_needed;
 634       if (varpool_assemble_decl (node))
 635         changed = true;
 636       else
 637         {
 638           node->prev_needed = NULL;
 639           node->next_needed = NULL;
 640         }
 641     }
 642   /* varpool_nodes_queue is now empty, clear the pointer to the last element
 643      in the queue.  */
 644   varpool_last_needed_node = NULL;
 645   timevar_pop (TV_VAROUT);
 646   return changed;
 647 }
 648
 649 /* Remove all elements from the queue so we can re-use it for debug output.  */
 650 void
 651 varpool_empty_needed_queue (void)
 652 {
 653   /* EH might mark decls as needed during expansion.  This should be safe since
 654      we don't create references to new function, but it should not be used
 655      elsewhere.  */
 656   varpool_analyze_pending_decls ();
 657
 658   while (varpool_nodes_queue)
 659     {
 660       struct varpool_node *node = varpool_nodes_queue;
 661       varpool_nodes_queue = varpool_nodes_queue->next_needed;
 662       node->next_needed = NULL;
 663       node->prev_needed = NULL;
 664     }
 665   /* varpool_nodes_queue is now empty, clear the pointer to the last element
 666      in the queue.  */
 667   varpool_last_needed_node = NULL;
 668 }
 669
 670 /* Create a new global variable of type TYPE.  */
 671 tree
 672 add_new_static_var (tree type)
 673 {
 674   tree new_decl;
 675   struct varpool_node *new_node;
 676
 677   new_decl = create_tmp_var (type, NULL);
 678   DECL_NAME (new_decl) = create_tmp_var_name (NULL);
 679   TREE_READONLY (new_decl) = 0;
 680   TREE_STATIC (new_decl) = 1;
 681   TREE_USED (new_decl) = 1;
 682   DECL_CONTEXT (new_decl) = NULL_TREE;
 683   DECL_ABSTRACT (new_decl) = 0;
 684   lang_hooks.dup_lang_specific_decl (new_decl);
 685   create_var_ann (new_decl);
 686   new_node = varpool_node (new_decl);
 687   varpool_mark_needed_node (new_node);
 688   add_referenced_var (new_decl);
 689   varpool_finalize_decl (new_decl);
 690
 691   return new_node->decl;
 692 }
 693
 694 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 695    Extra name aliases are output whenever DECL is output.  */
 696
 697 struct varpool_node *
 698 varpool_create_variable_alias (tree alias, tree decl)
 699 {
 700   struct varpool_node *alias_node;
 701
 702   gcc_assert (TREE_CODE (decl) == VAR_DECL);
 703   gcc_assert (TREE_CODE (alias) == VAR_DECL);
 704   alias_node = varpool_node (alias);
 705   alias_node->alias = 1;
 706   alias_node->finalized = 1;
 707   alias_node->alias_of = decl;
 708   if (decide_is_variable_needed (alias_node, alias)
 709       || alias_node->needed)
 710     varpool_mark_needed_node (alias_node);
 711   return alias_node;
 712 }
 713
 714 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 715    Extra name aliases are output whenever DECL is output.  */
 716
 717 struct varpool_node *
 718 varpool_extra_name_alias (tree alias, tree decl)
 719 {
 720   struct varpool_node *alias_node;
 721
 722 #ifndef ASM_OUTPUT_DEF
 723   /* If aliases aren't supported by the assembler, fail.  */
 724   return NULL;
 725 #endif
 726   alias_node = varpool_create_variable_alias (alias, decl);
 727   alias_node->extra_name_alias = true;
 728   return alias_node;
 729 }
 730
 731 /* Return true when NODE is known to be used from other (non-LTO) object file.
 732    Known only when doing LTO via linker plugin.  */
 733
 734 bool
 735 varpool_used_from_object_file_p (struct varpool_node *node)
 736 {
 737   if (!TREE_PUBLIC (node->decl))
 738     return false;
 739   if (resolution_used_from_other_file_p (node->resolution))
 740     return true;
 741   return false;
 742 }
 743
 744 /* Call calback on NODE and aliases asociated to NODE.
 745    When INCLUDE_OVERWRITABLE is false, overwritable aliases and thunks are
 746    skipped. */
 747
 748 bool
 749 varpool_for_node_and_aliases (struct varpool_node *node,
 750                               bool (*callback) (struct varpool_node *, void *),
 751                               void *data,
 752                               bool include_overwritable)
 753 {
 754   int i;
 755   struct ipa_ref *ref;
 756
 757   if (callback (node, data))
 758     return true;
 759   for (i = 0; ipa_ref_list_refering_iterate (&node->ref_list, i, ref); i++)
 760     if (ref->use == IPA_REF_ALIAS)
 761       {
 762         struct varpool_node *alias = ipa_ref_refering_varpool_node (ref);
 763         if (include_overwritable
 764             || cgraph_variable_initializer_availability (alias) > AVAIL_OVERWRITABLE)
 765           if (varpool_for_node_and_aliases (alias, callback, data,
 766                                            include_overwritable))
 767             return true;
 768       }
 769   return false;
 770 }
 771 #include "gt-varpool.h"