gcc/varpool.c

   1 /* Callgraph handling code.
   2    Copyright (C) 2003-2015 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 "varasm.h"
  27 #include "predict.h"
  28 #include "basic-block.h"
  29 #include "hash-map.h"
  30 #include "is-a.h"
  31 #include "plugin-api.h"
  32 #include "vec.h"
  33 #include "hashtab.h"
  34 #include "hash-set.h"
  35 #include "machmode.h"
  36 #include "hard-reg-set.h"
  37 #include "input.h"
  38 #include "function.h"
  39 #include "ipa-ref.h"
  40 #include "cgraph.h"
  41 #include "langhooks.h"
  42 #include "diagnostic-core.h"
  43 #include "timevar.h"
  44 #include "debug.h"
  45 #include "target.h"
  46 #include "output.h"
  47 #include "gimple-expr.h"
  48 #include "flags.h"
  49 #include "tree-ssa-alias.h"
  50 #include "gimple.h"
  51 #include "lto-streamer.h"
  52 #include "context.h"
  53 #include "omp-low.h"
  54
  55 const char * const tls_model_names[]={"none", "tls-emulated", "tls-real",
  56                                       "tls-global-dynamic", "tls-local-dynamic",
  57                                       "tls-initial-exec", "tls-local-exec"};
  58
  59 /* List of hooks triggered on varpool_node events.  */
  60 struct varpool_node_hook_list {
  61   varpool_node_hook hook;
  62   void *data;
  63   struct varpool_node_hook_list *next;
  64 };
  65
  66 /* Register HOOK to be called with DATA on each removed node.  */
  67 varpool_node_hook_list *
  68 symbol_table::add_varpool_removal_hook (varpool_node_hook hook, void *data)
  69 {
  70   varpool_node_hook_list *entry;
  71   varpool_node_hook_list **ptr = &m_first_varpool_removal_hook;
  72
  73   entry = (varpool_node_hook_list *) xmalloc (sizeof (*entry));
  74   entry->hook = hook;
  75   entry->data = data;
  76   entry->next = NULL;
  77   while (*ptr)
  78     ptr = &(*ptr)->next;
  79   *ptr = entry;
  80   return entry;
  81 }
  82
  83 /* Remove ENTRY from the list of hooks called on removing nodes.  */
  84 void
  85 symbol_table::remove_varpool_removal_hook (varpool_node_hook_list *entry)
  86 {
  87   varpool_node_hook_list **ptr = &m_first_varpool_removal_hook;
  88
  89   while (*ptr != entry)
  90     ptr = &(*ptr)->next;
  91   *ptr = entry->next;
  92   free (entry);
  93 }
  94
  95 /* Call all node removal hooks.  */
  96 void
  97 symbol_table::call_varpool_removal_hooks (varpool_node *node)
  98 {
  99   varpool_node_hook_list *entry = m_first_varpool_removal_hook;
 100   while (entry)
 101   {
 102     entry->hook (node, entry->data);
 103     entry = entry->next;
 104   }
 105 }
 106
 107 /* Register HOOK to be called with DATA on each inserted node.  */
 108 varpool_node_hook_list *
 109 symbol_table::add_varpool_insertion_hook (varpool_node_hook hook, void *data)
 110 {
 111   varpool_node_hook_list *entry;
 112   varpool_node_hook_list **ptr = &m_first_varpool_insertion_hook;
 113
 114   entry = (varpool_node_hook_list *) xmalloc (sizeof (*entry));
 115   entry->hook = hook;
 116   entry->data = data;
 117   entry->next = NULL;
 118   while (*ptr)
 119     ptr = &(*ptr)->next;
 120   *ptr = entry;
 121   return entry;
 122 }
 123
 124 /* Remove ENTRY from the list of hooks called on inserted nodes.  */
 125 void
 126 symbol_table::remove_varpool_insertion_hook (varpool_node_hook_list *entry)
 127 {
 128   varpool_node_hook_list **ptr = &m_first_varpool_insertion_hook;
 129
 130   while (*ptr != entry)
 131     ptr = &(*ptr)->next;
 132   *ptr = entry->next;
 133   free (entry);
 134 }
 135
 136 /* Call all node insertion hooks.  */
 137 void
 138 symbol_table::call_varpool_insertion_hooks (varpool_node *node)
 139 {
 140   varpool_node_hook_list *entry = m_first_varpool_insertion_hook;
 141   while (entry)
 142   {
 143     entry->hook (node, entry->data);
 144     entry = entry->next;
 145   }
 146 }
 147
 148 /* Allocate new callgraph node and insert it into basic data structures.  */
 149
 150 varpool_node *
 151 varpool_node::create_empty (void)
 152 {
 153   varpool_node *node = ggc_cleared_alloc<varpool_node> ();
 154   node->type = SYMTAB_VARIABLE;
 155   return node;
 156 }
 157
 158 /* Return varpool node assigned to DECL.  Create new one when needed.  */
 159 varpool_node *
 160 varpool_node::get_create (tree decl)
 161 {
 162   varpool_node *node = varpool_node::get (decl);
 163   gcc_checking_assert (TREE_CODE (decl) == VAR_DECL);
 164   if (node)
 165     return node;
 166
 167   node = varpool_node::create_empty ();
 168   node->decl = decl;
 169
 170   if (flag_openmp
 171       && lookup_attribute ("omp declare target", DECL_ATTRIBUTES (decl)))
 172     {
 173       node->offloadable = 1;
 174 #ifdef ENABLE_OFFLOADING
 175       g->have_offload = true;
 176       if (!in_lto_p)
 177         vec_safe_push (offload_vars, decl);
 178       node->force_output = 1;
 179 #endif
 180     }
 181
 182   node->register_symbol ();
 183   return node;
 184 }
 185
 186 /* Remove variable from symbol table.  */
 187
 188 void
 189 varpool_node::remove (void)
 190 {
 191   symtab->call_varpool_removal_hooks (this);
 192   unregister ();
 193
 194   /* When streaming we can have multiple nodes associated with decl.  */
 195   if (symtab->state == LTO_STREAMING)
 196     ;
 197   /* Keep constructor when it may be used for folding. We remove
 198      references to external variables before final compilation.  */
 199   else if (DECL_INITIAL (decl) && DECL_INITIAL (decl) != error_mark_node
 200            && !ctor_useable_for_folding_p ())
 201     remove_initializer ();
 202   ggc_free (this);
 203 }
 204
 205 /* Remove node initializer when it is no longer needed.  */
 206 void
 207 varpool_node::remove_initializer (void)
 208 {
 209   if (DECL_INITIAL (decl)
 210       && !DECL_IN_CONSTANT_POOL (decl)
 211       /* Keep vtables for BINFO folding.  */
 212       && !DECL_VIRTUAL_P (decl)
 213       /* FIXME: http://gcc.gnu.org/PR55395 */
 214       && debug_info_level == DINFO_LEVEL_NONE
 215       /* When doing declaration merging we have duplicate
 216          entries for given decl.  Do not attempt to remove
 217          the boides, or we will end up remiving
 218          wrong one.  */
 219       && symtab->state != LTO_STREAMING)
 220     DECL_INITIAL (decl) = error_mark_node;
 221 }
 222
 223 /* Dump given varpool node to F.  */
 224 void
 225 varpool_node::dump (FILE *f)
 226 {
 227   dump_base (f);
 228   fprintf (f, "  Availability: %s\n",
 229            symtab->function_flags_ready
 230            ? cgraph_availability_names[get_availability ()]
 231            : "not-ready");
 232   fprintf (f, "  Varpool flags:");
 233   if (DECL_INITIAL (decl))
 234     fprintf (f, " initialized");
 235   if (output)
 236     fprintf (f, " output");
 237   if (used_by_single_function)
 238     fprintf (f, " used-by-single-function");
 239   if (need_bounds_init)
 240     fprintf (f, " need-bounds-init");
 241   if (TREE_READONLY (decl))
 242     fprintf (f, " read-only");
 243   if (ctor_useable_for_folding_p ())
 244     fprintf (f, " const-value-known");
 245   if (writeonly)
 246     fprintf (f, " write-only");
 247   if (tls_model)
 248     fprintf (f, " %s", tls_model_names [tls_model]);
 249   fprintf (f, "\n");
 250 }
 251
 252
 253 /* Dump given varpool node to stderr.  */
 254 void varpool_node::debug (void)
 255 {
 256   varpool_node::dump (stderr);
 257 }
 258
 259 /* Dump the variable pool to F.  */
 260 void
 261 varpool_node::dump_varpool (FILE *f)
 262 {
 263   varpool_node *node;
 264
 265   fprintf (f, "variable pool:\n\n");
 266   FOR_EACH_VARIABLE (node)
 267     node->dump (f);
 268 }
 269
 270 /* Dump the variable pool to stderr.  */
 271
 272 DEBUG_FUNCTION void
 273 varpool_node::debug_varpool (void)
 274 {
 275   dump_varpool (stderr);
 276 }
 277
 278 /* Given an assembler name, lookup node.  */
 279 varpool_node *
 280 varpool_node::get_for_asmname (tree asmname)
 281 {
 282   if (symtab_node *node = symtab_node::get_for_asmname (asmname))
 283     return dyn_cast <varpool_node *> (node);
 284   else
 285     return NULL;
 286 }
 287
 288 /* When doing LTO, read variable's constructor from disk if
 289    it is not already present.  */
 290
 291 tree
 292 varpool_node::get_constructor (void)
 293 {
 294   lto_file_decl_data *file_data;
 295   const char *data, *name;
 296   size_t len;
 297
 298   if (DECL_INITIAL (decl) != error_mark_node
 299       || !in_lto_p)
 300     return DECL_INITIAL (decl);
 301
 302   timevar_push (TV_IPA_LTO_CTORS_IN);
 303
 304   file_data = lto_file_data;
 305   name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 306
 307   /* We may have renamed the declaration, e.g., a static function.  */
 308   name = lto_get_decl_name_mapping (file_data, name);
 309
 310   data = lto_get_section_data (file_data, LTO_section_function_body,
 311                                name, &len);
 312   if (!data)
 313     fatal_error ("%s: section %s is missing",
 314                  file_data->file_name,
 315                  name);
 316
 317   lto_input_variable_constructor (file_data, this, data);
 318   lto_stats.num_function_bodies++;
 319   lto_free_section_data (file_data, LTO_section_function_body, name,
 320                          data, len);
 321   lto_free_function_in_decl_state_for_node (this);
 322   timevar_pop (TV_IPA_LTO_CTORS_IN);
 323   return DECL_INITIAL (decl);
 324 }
 325
 326 /* Return true if variable has constructor that can be used for folding.  */
 327
 328 bool
 329 varpool_node::ctor_useable_for_folding_p (void)
 330 {
 331   varpool_node *real_node = this;
 332
 333   if (real_node->alias && real_node->definition)
 334     real_node = ultimate_alias_target ();
 335
 336   if (TREE_CODE (decl) == CONST_DECL
 337       || DECL_IN_CONSTANT_POOL (decl))
 338     return true;
 339   if (TREE_THIS_VOLATILE (decl))
 340     return false;
 341
 342   /* If we do not have a constructor, we can't use it.  */
 343   if (DECL_INITIAL (real_node->decl) == error_mark_node
 344       && !real_node->lto_file_data)
 345     return false;
 346
 347   /* Avoid attempts to load constructors that was not streamed.  */
 348   if (flag_ltrans && DECL_INITIAL (real_node->decl) == error_mark_node
 349       && real_node->body_removed)
 350     return false;
 351
 352   /* Vtables are defined by their types and must match no matter of interposition
 353      rules.  */
 354   if (DECL_VIRTUAL_P (decl))
 355     {
 356       /* The C++ front end creates VAR_DECLs for vtables of typeinfo
 357          classes not defined in the current TU so that it can refer
 358          to them from typeinfo objects.  Avoid returning NULL_TREE.  */
 359       return DECL_INITIAL (real_node->decl) != NULL;
 360     }
 361
 362   /* Alias of readonly variable is also readonly, since the variable is stored
 363      in readonly memory.  We also accept readonly aliases of non-readonly
 364      locations assuming that user knows what he is asking for.  */
 365   if (!TREE_READONLY (decl) && !TREE_READONLY (real_node->decl))
 366     return false;
 367
 368   /* Variables declared 'const' without an initializer
 369      have zero as the initializer if they may not be
 370      overridden at link or run time.
 371
 372      It is actually requirement for C++ compiler to optimize const variables
 373      consistently. As a GNU extension, do not enfore this rule for user defined
 374      weak variables, so we support interposition on:
 375      static const int dummy = 0;
 376      extern const int foo __attribute__((__weak__, __alias__("dummy")));
 377    */
 378   if ((!DECL_INITIAL (real_node->decl)
 379        || (DECL_WEAK (decl) && !DECL_COMDAT (decl)))
 380       && (DECL_EXTERNAL (decl) || decl_replaceable_p (decl)))
 381     return false;
 382
 383   /* Variables declared `const' with an initializer are considered
 384      to not be overwritable with different initializer by default.
 385
 386      ??? Previously we behaved so for scalar variables but not for array
 387      accesses.  */
 388   return true;
 389 }
 390
 391 /* If DECLARATION is constant variable and its initial value is known
 392    (so we can do constant folding), return its constructor (DECL_INITIAL).
 393    This may be an expression or NULL when DECL is initialized to 0.
 394    Return ERROR_MARK_NODE otherwise.
 395
 396    In LTO this may actually trigger reading the constructor from disk.
 397    For this reason varpool_ctor_useable_for_folding_p should be used when
 398    the actual constructor value is not needed.  */
 399
 400 tree
 401 ctor_for_folding (tree decl)
 402 {
 403   varpool_node *node, *real_node;
 404   tree real_decl;
 405
 406   if (TREE_CODE (decl) != VAR_DECL
 407       && TREE_CODE (decl) != CONST_DECL)
 408     return error_mark_node;
 409
 410   /* Static constant bounds are created to be
 411      used instead of constants and therefore
 412      do not let folding it.  */
 413   if (POINTER_BOUNDS_P (decl))
 414     return error_mark_node;
 415
 416   if (TREE_CODE (decl) == CONST_DECL
 417       || DECL_IN_CONSTANT_POOL (decl))
 418     return DECL_INITIAL (decl);
 419
 420   if (TREE_THIS_VOLATILE (decl))
 421     return error_mark_node;
 422
 423   /* Do not care about automatic variables.  Those are never initialized
 424      anyway, because gimplifier exapnds the code.  */
 425   if (!TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
 426     {
 427       gcc_assert (!TREE_PUBLIC (decl));
 428       return error_mark_node;
 429     }
 430
 431   gcc_assert (TREE_CODE (decl) == VAR_DECL);
 432
 433   real_node = node = varpool_node::get (decl);
 434   if (node)
 435     {
 436       real_node = node->ultimate_alias_target ();
 437       real_decl = real_node->decl;
 438     }
 439   else
 440     real_decl = decl;
 441
 442   /* See if we are dealing with alias.
 443      In most cases alias is just alternative symbol pointing to a given
 444      constructor.  This allows us to use interposition rules of DECL
 445      constructor of REAL_NODE.  However weakrefs are special by being just
 446      alternative name of their target (if defined).  */
 447   if (decl != real_decl)
 448     {
 449       gcc_assert (!DECL_INITIAL (decl)
 450                   || (node->alias && node->get_alias_target () == real_node)
 451                   || DECL_INITIAL (decl) == error_mark_node);
 452       if (node->weakref)
 453         {
 454           node = node->get_alias_target ();
 455           decl = node->decl;
 456         }
 457     }
 458
 459   if ((!DECL_VIRTUAL_P (real_decl)
 460        || DECL_INITIAL (real_decl) == error_mark_node
 461        || !DECL_INITIAL (real_decl))
 462       && (!node || !node->ctor_useable_for_folding_p ()))
 463     return error_mark_node;
 464
 465   /* OK, we can return constructor.  See if we need to fetch it from disk
 466      in LTO mode.  */
 467   if (DECL_INITIAL (real_decl) != error_mark_node
 468       || !in_lto_p)
 469     return DECL_INITIAL (real_decl);
 470   return real_node->get_constructor ();
 471 }
 472
 473 /* Add the variable DECL to the varpool.
 474    Unlike finalize_decl function is intended to be used
 475    by middle end and allows insertion of new variable at arbitrary point
 476    of compilation.  */
 477 void
 478 varpool_node::add (tree decl)
 479 {
 480   varpool_node *node;
 481   varpool_node::finalize_decl (decl);
 482   node = varpool_node::get_create (decl);
 483   symtab->call_varpool_insertion_hooks (node);
 484   if (node->externally_visible_p ())
 485     node->externally_visible = true;
 486   if (lookup_attribute ("no_reorder", DECL_ATTRIBUTES (decl)))
 487     node->no_reorder = 1;
 488 }
 489
 490 /* Return variable availability.  See cgraph.h for description of individual
 491    return values.  */
 492 enum availability
 493 varpool_node::get_availability (void)
 494 {
 495   if (!definition)
 496     return AVAIL_NOT_AVAILABLE;
 497   if (!TREE_PUBLIC (decl))
 498     return AVAIL_AVAILABLE;
 499   if (DECL_IN_CONSTANT_POOL (decl)
 500       || DECL_VIRTUAL_P (decl))
 501     return AVAIL_AVAILABLE;
 502   if (alias && weakref)
 503     {
 504       enum availability avail;
 505
 506       ultimate_alias_target (&avail)->get_availability ();
 507       return avail;
 508     }
 509   /* If the variable can be overwritten, return OVERWRITABLE.  Takes
 510      care of at least one notable extension - the COMDAT variables
 511      used to share template instantiations in C++.  */
 512   if (decl_replaceable_p (decl)
 513       || DECL_EXTERNAL (decl))
 514     return AVAIL_INTERPOSABLE;
 515   return AVAIL_AVAILABLE;
 516 }
 517
 518 void
 519 varpool_node::analyze (void)
 520 {
 521   /* When reading back varpool at LTO time, we re-construct the queue in order
 522      to have "needed" list right by inserting all needed nodes into varpool.
 523      We however don't want to re-analyze already analyzed nodes.  */
 524   if (!analyzed)
 525     {
 526       gcc_assert (!in_lto_p || symtab->function_flags_ready);
 527       /* Compute the alignment early so function body expanders are
 528          already informed about increased alignment.  */
 529       align_variable (decl, 0);
 530     }
 531   if (alias)
 532     resolve_alias (varpool_node::get (alias_target));
 533   else if (DECL_INITIAL (decl))
 534     record_references_in_initializer (decl, analyzed);
 535   analyzed = true;
 536 }
 537
 538 /* Assemble thunks and aliases associated to varpool node.  */
 539
 540 void
 541 varpool_node::assemble_aliases (void)
 542 {
 543   ipa_ref *ref;
 544
 545   FOR_EACH_ALIAS (this, ref)
 546     {
 547       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 548       do_assemble_alias (alias->decl,
 549                          DECL_ASSEMBLER_NAME (decl));
 550       alias->assemble_aliases ();
 551     }
 552 }
 553
 554 /* Output one variable, if necessary.  Return whether we output it.  */
 555
 556 bool
 557 varpool_node::assemble_decl (void)
 558 {
 559   /* Aliases are outout when their target is produced or by
 560      output_weakrefs.  */
 561   if (alias)
 562     return false;
 563
 564   /* Constant pool is output from RTL land when the reference
 565      survive till this level.  */
 566   if (DECL_IN_CONSTANT_POOL (decl) && TREE_ASM_WRITTEN (decl))
 567     return false;
 568
 569   /* Decls with VALUE_EXPR should not be in the varpool at all.  They
 570      are not real variables, but just info for debugging and codegen.
 571      Unfortunately at the moment emutls is not updating varpool correctly
 572      after turning real vars into value_expr vars.  */
 573   if (DECL_HAS_VALUE_EXPR_P (decl)
 574       && !targetm.have_tls)
 575     return false;
 576
 577   /* Hard register vars do not need to be output.  */
 578   if (DECL_HARD_REGISTER (decl))
 579     return false;
 580
 581   gcc_checking_assert (!TREE_ASM_WRITTEN (decl)
 582                        && TREE_CODE (decl) == VAR_DECL
 583                        && !DECL_HAS_VALUE_EXPR_P (decl));
 584
 585   if (!in_other_partition
 586       && !DECL_EXTERNAL (decl))
 587     {
 588       get_constructor ();
 589       assemble_variable (decl, 0, 1, 0);
 590       gcc_assert (TREE_ASM_WRITTEN (decl));
 591       gcc_assert (definition);
 592       assemble_aliases ();
 593       return true;
 594     }
 595
 596   return false;
 597 }
 598
 599 /* Add NODE to queue starting at FIRST.
 600    The queue is linked via AUX pointers and terminated by pointer to 1.  */
 601
 602 static void
 603 enqueue_node (varpool_node *node, varpool_node **first)
 604 {
 605   if (node->aux)
 606     return;
 607   gcc_checking_assert (*first);
 608   node->aux = *first;
 609   *first = node;
 610 }
 611
 612 /* Optimization of function bodies might've rendered some variables as
 613    unnecessary so we want to avoid these from being compiled.  Re-do
 614    reachability starting from variables that are either externally visible
 615    or was referred from the asm output routines.  */
 616
 617 void
 618 symbol_table::remove_unreferenced_decls (void)
 619 {
 620   varpool_node *next, *node;
 621   varpool_node *first = (varpool_node *)(void *)1;
 622   int i;
 623   ipa_ref *ref = NULL;
 624   hash_set<varpool_node *> referenced;
 625
 626   if (seen_error ())
 627     return;
 628
 629   if (dump_file)
 630     fprintf (dump_file, "Trivially needed variables:");
 631   FOR_EACH_DEFINED_VARIABLE (node)
 632     {
 633       if (node->analyzed
 634           && (!node->can_remove_if_no_refs_p ()
 635               /* We just expanded all function bodies.  See if any of
 636                  them needed the variable.  */
 637               || DECL_RTL_SET_P (node->decl)))
 638         {
 639           enqueue_node (node, &first);
 640           if (dump_file)
 641             fprintf (dump_file, " %s", node->asm_name ());
 642         }
 643     }
 644   while (first != (varpool_node *)(void *)1)
 645     {
 646       node = first;
 647       first = (varpool_node *)first->aux;
 648
 649       if (node->same_comdat_group)
 650         {
 651           symtab_node *next;
 652           for (next = node->same_comdat_group;
 653                next != node;
 654                next = next->same_comdat_group)
 655             {
 656               varpool_node *vnext = dyn_cast <varpool_node *> (next);
 657               if (vnext && vnext->analyzed && !next->comdat_local_p ())
 658                 enqueue_node (vnext, &first);
 659             }
 660         }
 661       for (i = 0; node->iterate_reference (i, ref); i++)
 662         {
 663           varpool_node *vnode = dyn_cast <varpool_node *> (ref->referred);
 664           if (vnode
 665               && !vnode->in_other_partition
 666               && (!DECL_EXTERNAL (ref->referred->decl)
 667                   || vnode->alias)
 668               && vnode->analyzed)
 669             enqueue_node (vnode, &first);
 670           else
 671             referenced.add (node);
 672         }
 673     }
 674   if (dump_file)
 675     fprintf (dump_file, "\nRemoving variables:");
 676   for (node = first_defined_variable (); node; node = next)
 677     {
 678       next = next_defined_variable (node);
 679       if (!node->aux && !node->no_reorder)
 680         {
 681           if (dump_file)
 682             fprintf (dump_file, " %s", node->asm_name ());
 683           if (referenced.contains(node))
 684             node->remove_initializer ();
 685           else
 686             node->remove ();
 687         }
 688     }
 689
 690   if (dump_file)
 691     fprintf (dump_file, "\n");
 692 }
 693
 694 /* For variables in named sections make sure get_variable_section
 695    is called before we switch to those sections.  Then section
 696    conflicts between read-only and read-only requiring relocations
 697    sections can be resolved.  */
 698 void
 699 varpool_node::finalize_named_section_flags (void)
 700 {
 701   if (!TREE_ASM_WRITTEN (decl)
 702       && !alias
 703       && !in_other_partition
 704       && !DECL_EXTERNAL (decl)
 705       && TREE_CODE (decl) == VAR_DECL
 706       && !DECL_HAS_VALUE_EXPR_P (decl)
 707       && get_section ())
 708     get_variable_section (decl, false);
 709 }
 710
 711 /* Output all variables enqueued to be assembled.  */
 712 bool
 713 symbol_table::output_variables (void)
 714 {
 715   bool changed = false;
 716   varpool_node *node;
 717
 718   if (seen_error ())
 719     return false;
 720
 721   remove_unreferenced_decls ();
 722
 723   timevar_push (TV_VAROUT);
 724
 725   FOR_EACH_VARIABLE (node)
 726     if (!node->definition)
 727       assemble_undefined_decl (node->decl);
 728   FOR_EACH_DEFINED_VARIABLE (node)
 729     {
 730       /* Handled in output_in_order.  */
 731       if (node->no_reorder)
 732         continue;
 733
 734       node->finalize_named_section_flags ();
 735     }
 736
 737   FOR_EACH_DEFINED_VARIABLE (node)
 738     {
 739       /* Handled in output_in_order.  */
 740       if (node->no_reorder)
 741         continue;
 742       if (node->assemble_decl ())
 743         changed = true;
 744     }
 745   timevar_pop (TV_VAROUT);
 746   return changed;
 747 }
 748
 749 /* Create a new global variable of type TYPE.  */
 750 tree
 751 add_new_static_var (tree type)
 752 {
 753   tree new_decl;
 754   varpool_node *new_node;
 755
 756   new_decl = create_tmp_var_raw (type);
 757   DECL_NAME (new_decl) = create_tmp_var_name (NULL);
 758   TREE_READONLY (new_decl) = 0;
 759   TREE_STATIC (new_decl) = 1;
 760   TREE_USED (new_decl) = 1;
 761   DECL_CONTEXT (new_decl) = NULL_TREE;
 762   DECL_ABSTRACT_P (new_decl) = false;
 763   lang_hooks.dup_lang_specific_decl (new_decl);
 764   new_node = varpool_node::get_create (new_decl);
 765   varpool_node::finalize_decl (new_decl);
 766
 767   return new_node->decl;
 768 }
 769
 770 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 771    Extra name aliases are output whenever DECL is output.  */
 772
 773 varpool_node *
 774 varpool_node::create_alias (tree alias, tree decl)
 775 {
 776   varpool_node *alias_node;
 777
 778   gcc_assert (TREE_CODE (decl) == VAR_DECL);
 779   gcc_assert (TREE_CODE (alias) == VAR_DECL);
 780   alias_node = varpool_node::get_create (alias);
 781   alias_node->alias = true;
 782   alias_node->definition = true;
 783   alias_node->alias_target = decl;
 784   if (lookup_attribute ("weakref", DECL_ATTRIBUTES (alias)) != NULL)
 785     alias_node->weakref = true;
 786   return alias_node;
 787 }
 788
 789 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 790    Extra name aliases are output whenever DECL is output.  */
 791
 792 varpool_node *
 793 varpool_node::create_extra_name_alias (tree alias, tree decl)
 794 {
 795   varpool_node *alias_node;
 796
 797 #ifndef ASM_OUTPUT_DEF
 798   /* If aliases aren't supported by the assembler, fail.  */
 799   return NULL;
 800 #endif
 801   alias_node = varpool_node::create_alias (alias, decl);
 802   alias_node->cpp_implicit_alias = true;
 803
 804   /* Extra name alias mechanizm creates aliases really late
 805      via DECL_ASSEMBLER_NAME mechanizm.
 806      This is unfortunate because they are not going through the
 807      standard channels.  Ensure they get output.  */
 808   if (symtab->cpp_implicit_aliases_done)
 809     alias_node->resolve_alias (varpool_node::get_create (decl));
 810   return alias_node;
 811 }
 812
 813 /* Call calback on varpool symbol and aliases associated to varpool symbol.
 814    When INCLUDE_OVERWRITABLE is false, overwritable aliases and thunks are
 815    skipped. */
 816
 817 bool
 818 varpool_node::call_for_node_and_aliases (bool (*callback) (varpool_node *,
 819                                                            void *),
 820                                          void *data,
 821                                          bool include_overwritable)
 822 {
 823   ipa_ref *ref;
 824
 825   if (callback (this, data))
 826     return true;
 827
 828   FOR_EACH_ALIAS (this, ref)
 829     {
 830       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 831       if (include_overwritable
 832           || alias->get_availability () > AVAIL_INTERPOSABLE)
 833         if (alias->call_for_node_and_aliases (callback, data,
 834                                               include_overwritable))
 835           return true;
 836     }
 837   return false;
 838 }