gcc/varpool.c

   1 /* Callgraph handling code.
   2    Copyright (C) 2003-2017 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 "backend.h"
  25 #include "target.h"
  26 #include "tree.h"
  27 #include "gimple.h"
  28 #include "timevar.h"
  29 #include "cgraph.h"
  30 #include "lto-streamer.h"
  31 #include "varasm.h"
  32 #include "debug.h"
  33 #include "output.h"
  34 #include "omp-offload.h"
  35 #include "context.h"
  36
  37 const char * const tls_model_names[]={"none", "emulated",
  38                                       "global-dynamic", "local-dynamic",
  39                                       "initial-exec", "local-exec"};
  40
  41 /* List of hooks triggered on varpool_node events.  */
  42 struct varpool_node_hook_list {
  43   varpool_node_hook hook;
  44   void *data;
  45   struct varpool_node_hook_list *next;
  46 };
  47
  48 /* Register HOOK to be called with DATA on each removed node.  */
  49 varpool_node_hook_list *
  50 symbol_table::add_varpool_removal_hook (varpool_node_hook hook, void *data)
  51 {
  52   varpool_node_hook_list *entry;
  53   varpool_node_hook_list **ptr = &m_first_varpool_removal_hook;
  54
  55   entry = (varpool_node_hook_list *) xmalloc (sizeof (*entry));
  56   entry->hook = hook;
  57   entry->data = data;
  58   entry->next = NULL;
  59   while (*ptr)
  60     ptr = &(*ptr)->next;
  61   *ptr = entry;
  62   return entry;
  63 }
  64
  65 /* Remove ENTRY from the list of hooks called on removing nodes.  */
  66 void
  67 symbol_table::remove_varpool_removal_hook (varpool_node_hook_list *entry)
  68 {
  69   varpool_node_hook_list **ptr = &m_first_varpool_removal_hook;
  70
  71   while (*ptr != entry)
  72     ptr = &(*ptr)->next;
  73   *ptr = entry->next;
  74   free (entry);
  75 }
  76
  77 /* Call all node removal hooks.  */
  78 void
  79 symbol_table::call_varpool_removal_hooks (varpool_node *node)
  80 {
  81   varpool_node_hook_list *entry = m_first_varpool_removal_hook;
  82   while (entry)
  83   {
  84     entry->hook (node, entry->data);
  85     entry = entry->next;
  86   }
  87 }
  88
  89 /* Register HOOK to be called with DATA on each inserted node.  */
  90 varpool_node_hook_list *
  91 symbol_table::add_varpool_insertion_hook (varpool_node_hook hook, void *data)
  92 {
  93   varpool_node_hook_list *entry;
  94   varpool_node_hook_list **ptr = &m_first_varpool_insertion_hook;
  95
  96   entry = (varpool_node_hook_list *) xmalloc (sizeof (*entry));
  97   entry->hook = hook;
  98   entry->data = data;
  99   entry->next = NULL;
 100   while (*ptr)
 101     ptr = &(*ptr)->next;
 102   *ptr = entry;
 103   return entry;
 104 }
 105
 106 /* Remove ENTRY from the list of hooks called on inserted nodes.  */
 107 void
 108 symbol_table::remove_varpool_insertion_hook (varpool_node_hook_list *entry)
 109 {
 110   varpool_node_hook_list **ptr = &m_first_varpool_insertion_hook;
 111
 112   while (*ptr != entry)
 113     ptr = &(*ptr)->next;
 114   *ptr = entry->next;
 115   free (entry);
 116 }
 117
 118 /* Call all node insertion hooks.  */
 119 void
 120 symbol_table::call_varpool_insertion_hooks (varpool_node *node)
 121 {
 122   varpool_node_hook_list *entry = m_first_varpool_insertion_hook;
 123   while (entry)
 124   {
 125     entry->hook (node, entry->data);
 126     entry = entry->next;
 127   }
 128 }
 129
 130 /* Allocate new callgraph node and insert it into basic data structures.  */
 131
 132 varpool_node *
 133 varpool_node::create_empty (void)
 134 {
 135   varpool_node *node = ggc_cleared_alloc<varpool_node> ();
 136   node->type = SYMTAB_VARIABLE;
 137   return node;
 138 }
 139
 140 /* Return varpool node assigned to DECL.  Create new one when needed.  */
 141 varpool_node *
 142 varpool_node::get_create (tree decl)
 143 {
 144   varpool_node *node = varpool_node::get (decl);
 145   gcc_checking_assert (VAR_P (decl));
 146   if (node)
 147     return node;
 148
 149   node = varpool_node::create_empty ();
 150   node->decl = decl;
 151
 152   if ((flag_openacc || flag_openmp)
 153       && lookup_attribute ("omp declare target", DECL_ATTRIBUTES (decl)))
 154     {
 155       node->offloadable = 1;
 156       if (ENABLE_OFFLOADING && !DECL_EXTERNAL (decl))
 157         {
 158           g->have_offload = true;
 159           if (!in_lto_p)
 160             vec_safe_push (offload_vars, decl);
 161         }
 162     }
 163
 164   node->register_symbol ();
 165   return node;
 166 }
 167
 168 /* Remove variable from symbol table.  */
 169
 170 void
 171 varpool_node::remove (void)
 172 {
 173   symtab->call_varpool_removal_hooks (this);
 174   if (lto_file_data)
 175     {
 176       lto_free_function_in_decl_state_for_node (this);
 177       lto_file_data = NULL;
 178     }
 179
 180   /* When streaming we can have multiple nodes associated with decl.  */
 181   if (symtab->state == LTO_STREAMING)
 182     ;
 183   /* Keep constructor when it may be used for folding. We remove
 184      references to external variables before final compilation.  */
 185   else if (DECL_INITIAL (decl) && DECL_INITIAL (decl) != error_mark_node
 186            && !ctor_useable_for_folding_p ())
 187     remove_initializer ();
 188
 189   unregister ();
 190   ggc_free (this);
 191 }
 192
 193 /* Remove node initializer when it is no longer needed.  */
 194 void
 195 varpool_node::remove_initializer (void)
 196 {
 197   if (DECL_INITIAL (decl)
 198       && !DECL_IN_CONSTANT_POOL (decl)
 199       /* Keep vtables for BINFO folding.  */
 200       && !DECL_VIRTUAL_P (decl)
 201       /* FIXME: http://gcc.gnu.org/PR55395 */
 202       && debug_info_level == DINFO_LEVEL_NONE
 203       /* When doing declaration merging we have duplicate
 204          entries for given decl.  Do not attempt to remove
 205          the boides, or we will end up remiving
 206          wrong one.  */
 207       && symtab->state != LTO_STREAMING)
 208     DECL_INITIAL (decl) = error_mark_node;
 209 }
 210
 211 /* Dump given varpool node to F.  */
 212 void
 213 varpool_node::dump (FILE *f)
 214 {
 215   dump_base (f);
 216   fprintf (f, "  Availability: %s\n",
 217            symtab->function_flags_ready
 218            ? cgraph_availability_names[get_availability ()]
 219            : "not-ready");
 220   fprintf (f, "  Varpool flags:");
 221   if (DECL_INITIAL (decl))
 222     fprintf (f, " initialized");
 223   if (output)
 224     fprintf (f, " output");
 225   if (used_by_single_function)
 226     fprintf (f, " used-by-single-function");
 227   if (need_bounds_init)
 228     fprintf (f, " need-bounds-init");
 229   if (TREE_READONLY (decl))
 230     fprintf (f, " read-only");
 231   if (ctor_useable_for_folding_p ())
 232     fprintf (f, " const-value-known");
 233   if (writeonly)
 234     fprintf (f, " write-only");
 235   if (tls_model)
 236     fprintf (f, " tls-%s", tls_model_names [tls_model]);
 237   fprintf (f, "\n");
 238 }
 239
 240
 241 /* Dump given varpool node to stderr.  */
 242 void varpool_node::debug (void)
 243 {
 244   varpool_node::dump (stderr);
 245 }
 246
 247 /* Dump the variable pool to F.  */
 248 void
 249 varpool_node::dump_varpool (FILE *f)
 250 {
 251   varpool_node *node;
 252
 253   fprintf (f, "variable pool:\n\n");
 254   FOR_EACH_VARIABLE (node)
 255     node->dump (f);
 256 }
 257
 258 /* Dump the variable pool to stderr.  */
 259
 260 DEBUG_FUNCTION void
 261 varpool_node::debug_varpool (void)
 262 {
 263   dump_varpool (stderr);
 264 }
 265
 266 /* Given an assembler name, lookup node.  */
 267 varpool_node *
 268 varpool_node::get_for_asmname (tree asmname)
 269 {
 270   if (symtab_node *node = symtab_node::get_for_asmname (asmname))
 271     return dyn_cast <varpool_node *> (node);
 272   else
 273     return NULL;
 274 }
 275
 276 /* When doing LTO, read variable's constructor from disk if
 277    it is not already present.  */
 278
 279 tree
 280 varpool_node::get_constructor (void)
 281 {
 282   lto_file_decl_data *file_data;
 283   const char *data, *name;
 284   size_t len;
 285
 286   if (DECL_INITIAL (decl) != error_mark_node
 287       || !in_lto_p
 288       || !lto_file_data)
 289     return DECL_INITIAL (decl);
 290
 291   timevar_push (TV_IPA_LTO_CTORS_IN);
 292
 293   file_data = lto_file_data;
 294   name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 295
 296   /* We may have renamed the declaration, e.g., a static function.  */
 297   name = lto_get_decl_name_mapping (file_data, name);
 298   struct lto_in_decl_state *decl_state
 299          = lto_get_function_in_decl_state (file_data, decl);
 300
 301   data = lto_get_section_data (file_data, LTO_section_function_body,
 302                                name, &len, decl_state->compressed);
 303   if (!data)
 304     fatal_error (input_location, "%s: section %s is missing",
 305                  file_data->file_name,
 306                  name);
 307
 308   lto_input_variable_constructor (file_data, this, data);
 309   gcc_assert (DECL_INITIAL (decl) != error_mark_node);
 310   lto_stats.num_function_bodies++;
 311   lto_free_section_data (file_data, LTO_section_function_body, name,
 312                          data, len, decl_state->compressed);
 313   lto_free_function_in_decl_state_for_node (this);
 314   timevar_pop (TV_IPA_LTO_CTORS_IN);
 315   return DECL_INITIAL (decl);
 316 }
 317
 318 /* Return true if variable has constructor that can be used for folding.  */
 319
 320 bool
 321 varpool_node::ctor_useable_for_folding_p (void)
 322 {
 323   varpool_node *real_node = this;
 324
 325   if (real_node->alias && real_node->definition)
 326     real_node = ultimate_alias_target ();
 327
 328   if (TREE_CODE (decl) == CONST_DECL
 329       || DECL_IN_CONSTANT_POOL (decl))
 330     return true;
 331   if (TREE_THIS_VOLATILE (decl))
 332     return false;
 333
 334   /* If we do not have a constructor, we can't use it.  */
 335   if (DECL_INITIAL (real_node->decl) == error_mark_node
 336       && !real_node->lto_file_data)
 337     return false;
 338
 339   /* Avoid attempts to load constructors that was not streamed.  */
 340   if (flag_ltrans && DECL_INITIAL (real_node->decl) == error_mark_node
 341       && real_node->body_removed)
 342     return false;
 343
 344   /* Vtables are defined by their types and must match no matter of interposition
 345      rules.  */
 346   if (DECL_VIRTUAL_P (decl))
 347     {
 348       /* The C++ front end creates VAR_DECLs for vtables of typeinfo
 349          classes not defined in the current TU so that it can refer
 350          to them from typeinfo objects.  Avoid returning NULL_TREE.  */
 351       return DECL_INITIAL (real_node->decl) != NULL;
 352     }
 353
 354   /* Alias of readonly variable is also readonly, since the variable is stored
 355      in readonly memory.  We also accept readonly aliases of non-readonly
 356      locations assuming that user knows what he is asking for.  */
 357   if (!TREE_READONLY (decl) && !TREE_READONLY (real_node->decl))
 358     return false;
 359
 360   /* Variables declared 'const' without an initializer
 361      have zero as the initializer if they may not be
 362      overridden at link or run time.
 363
 364      It is actually requirement for C++ compiler to optimize const variables
 365      consistently. As a GNU extension, do not enfore this rule for user defined
 366      weak variables, so we support interposition on:
 367      static const int dummy = 0;
 368      extern const int foo __attribute__((__weak__, __alias__("dummy")));
 369    */
 370   if ((!DECL_INITIAL (real_node->decl)
 371        || (DECL_WEAK (decl) && !DECL_COMDAT (decl)))
 372       && (DECL_EXTERNAL (decl) || decl_replaceable_p (decl)))
 373     return false;
 374
 375   /* Variables declared `const' with an initializer are considered
 376      to not be overwritable with different initializer by default.
 377
 378      ??? Previously we behaved so for scalar variables but not for array
 379      accesses.  */
 380   return true;
 381 }
 382
 383 /* If DECLARATION is constant variable and its initial value is known
 384    (so we can do constant folding), return its constructor (DECL_INITIAL).
 385    This may be an expression or NULL when DECL is initialized to 0.
 386    Return ERROR_MARK_NODE otherwise.
 387
 388    In LTO this may actually trigger reading the constructor from disk.
 389    For this reason varpool_ctor_useable_for_folding_p should be used when
 390    the actual constructor value is not needed.  */
 391
 392 tree
 393 ctor_for_folding (tree decl)
 394 {
 395   varpool_node *node, *real_node;
 396   tree real_decl;
 397
 398   if (!VAR_P (decl) && TREE_CODE (decl) != CONST_DECL)
 399     return error_mark_node;
 400
 401   /* Static constant bounds are created to be
 402      used instead of constants and therefore
 403      do not let folding it.  */
 404   if (POINTER_BOUNDS_P (decl))
 405     return error_mark_node;
 406
 407   if (TREE_CODE (decl) == CONST_DECL
 408       || DECL_IN_CONSTANT_POOL (decl))
 409     return DECL_INITIAL (decl);
 410
 411   if (TREE_THIS_VOLATILE (decl))
 412     return error_mark_node;
 413
 414   /* Do not care about automatic variables.  Those are never initialized
 415      anyway, because gimplifier exapnds the code.  */
 416   if (!TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
 417     {
 418       gcc_assert (!TREE_PUBLIC (decl));
 419       return error_mark_node;
 420     }
 421
 422   gcc_assert (VAR_P (decl));
 423
 424   real_node = node = varpool_node::get (decl);
 425   if (node)
 426     {
 427       real_node = node->ultimate_alias_target ();
 428       real_decl = real_node->decl;
 429     }
 430   else
 431     real_decl = decl;
 432
 433   /* See if we are dealing with alias.
 434      In most cases alias is just alternative symbol pointing to a given
 435      constructor.  This allows us to use interposition rules of DECL
 436      constructor of REAL_NODE.  However weakrefs are special by being just
 437      alternative name of their target (if defined).  */
 438   if (decl != real_decl)
 439     {
 440       gcc_assert (!DECL_INITIAL (decl)
 441                   || (node->alias && node->get_alias_target () == real_node)
 442                   || DECL_INITIAL (decl) == error_mark_node);
 443       while (node->transparent_alias && node->analyzed)
 444         {
 445           node = node->get_alias_target ();
 446           decl = node->decl;
 447         }
 448     }
 449
 450   if ((!DECL_VIRTUAL_P (real_decl)
 451        || DECL_INITIAL (real_decl) == error_mark_node
 452        || !DECL_INITIAL (real_decl))
 453       && (!node || !node->ctor_useable_for_folding_p ()))
 454     return error_mark_node;
 455
 456   /* OK, we can return constructor.  See if we need to fetch it from disk
 457      in LTO mode.  */
 458   if (DECL_INITIAL (real_decl) != error_mark_node
 459       || !in_lto_p)
 460     return DECL_INITIAL (real_decl);
 461   return real_node->get_constructor ();
 462 }
 463
 464 /* Add the variable DECL to the varpool.
 465    Unlike finalize_decl function is intended to be used
 466    by middle end and allows insertion of new variable at arbitrary point
 467    of compilation.  */
 468 void
 469 varpool_node::add (tree decl)
 470 {
 471   varpool_node *node;
 472   varpool_node::finalize_decl (decl);
 473   node = varpool_node::get_create (decl);
 474   symtab->call_varpool_insertion_hooks (node);
 475   if (node->externally_visible_p ())
 476     node->externally_visible = true;
 477   if (lookup_attribute ("no_reorder", DECL_ATTRIBUTES (decl)))
 478     node->no_reorder = 1;
 479 }
 480
 481 /* Return variable availability.  See cgraph.h for description of individual
 482    return values.  */
 483 enum availability
 484 varpool_node::get_availability (symtab_node *ref)
 485 {
 486   if (!definition)
 487     return AVAIL_NOT_AVAILABLE;
 488   if (!TREE_PUBLIC (decl))
 489     return AVAIL_AVAILABLE;
 490   if (DECL_IN_CONSTANT_POOL (decl)
 491       || DECL_VIRTUAL_P (decl))
 492     return AVAIL_AVAILABLE;
 493   if (transparent_alias && definition)
 494     {
 495       enum availability avail;
 496
 497       ultimate_alias_target (&avail, ref);
 498       return avail;
 499     }
 500   /* If this is a reference from symbol itself and there are no aliases, we
 501      may be sure that the symbol was not interposed by something else because
 502      the symbol itself would be unreachable otherwise.  */
 503   if ((this == ref && !has_aliases_p ())
 504       || (ref && get_comdat_group ()
 505           && get_comdat_group () == ref->get_comdat_group ()))
 506     return AVAIL_AVAILABLE;
 507   /* If the variable can be overwritten, return OVERWRITABLE.  Takes
 508      care of at least one notable extension - the COMDAT variables
 509      used to share template instantiations in C++.  */
 510   if (decl_replaceable_p (decl)
 511       || DECL_EXTERNAL (decl))
 512     return AVAIL_INTERPOSABLE;
 513   return AVAIL_AVAILABLE;
 514 }
 515
 516 void
 517 varpool_node::analyze (void)
 518 {
 519   /* When reading back varpool at LTO time, we re-construct the queue in order
 520      to have "needed" list right by inserting all needed nodes into varpool.
 521      We however don't want to re-analyze already analyzed nodes.  */
 522   if (!analyzed)
 523     {
 524       gcc_assert (!in_lto_p || symtab->function_flags_ready);
 525       /* Compute the alignment early so function body expanders are
 526          already informed about increased alignment.  */
 527       align_variable (decl, 0);
 528     }
 529   if (alias)
 530     resolve_alias (varpool_node::get (alias_target));
 531   else if (DECL_INITIAL (decl))
 532     record_references_in_initializer (decl, analyzed);
 533   analyzed = true;
 534 }
 535
 536 /* Assemble thunks and aliases associated to varpool node.  */
 537
 538 void
 539 varpool_node::assemble_aliases (void)
 540 {
 541   ipa_ref *ref;
 542
 543   FOR_EACH_ALIAS (this, ref)
 544     {
 545       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 546       if (!alias->transparent_alias)
 547         do_assemble_alias (alias->decl,
 548                            DECL_ASSEMBLER_NAME (decl));
 549       alias->assemble_aliases ();
 550     }
 551 }
 552
 553 /* Output one variable, if necessary.  Return whether we output it.  */
 554
 555 bool
 556 varpool_node::assemble_decl (void)
 557 {
 558   /* Aliases are outout when their target is produced or by
 559      output_weakrefs.  */
 560   if (alias)
 561     return false;
 562
 563   /* Constant pool is output from RTL land when the reference
 564      survive till this level.  */
 565   if (DECL_IN_CONSTANT_POOL (decl) && TREE_ASM_WRITTEN (decl))
 566     return false;
 567
 568   /* Decls with VALUE_EXPR should not be in the varpool at all.  They
 569      are not real variables, but just info for debugging and codegen.
 570      Unfortunately at the moment emutls is not updating varpool correctly
 571      after turning real vars into value_expr vars.  */
 572   if (DECL_HAS_VALUE_EXPR_P (decl)
 573       && !targetm.have_tls)
 574     return false;
 575
 576   /* Hard register vars do not need to be output.  */
 577   if (DECL_HARD_REGISTER (decl))
 578     return false;
 579
 580   gcc_checking_assert (!TREE_ASM_WRITTEN (decl)
 581                        && VAR_P (decl)
 582                        && !DECL_HAS_VALUE_EXPR_P (decl));
 583
 584   if (!in_other_partition
 585       && !DECL_EXTERNAL (decl))
 586     {
 587       get_constructor ();
 588       assemble_variable (decl, 0, 1, 0);
 589       gcc_assert (TREE_ASM_WRITTEN (decl));
 590       gcc_assert (definition);
 591       assemble_aliases ();
 592       /* After the parser has generated debugging information, augment
 593          this information with any new location/etc information that may
 594          have become available after the compilation proper.  */
 595       debug_hooks->late_global_decl (decl);
 596       return true;
 597     }
 598
 599   return false;
 600 }
 601
 602 /* Add NODE to queue starting at FIRST.
 603    The queue is linked via AUX pointers and terminated by pointer to 1.  */
 604
 605 static void
 606 enqueue_node (varpool_node *node, varpool_node **first)
 607 {
 608   if (node->aux)
 609     return;
 610   gcc_checking_assert (*first);
 611   node->aux = *first;
 612   *first = node;
 613 }
 614
 615 /* Optimization of function bodies might've rendered some variables as
 616    unnecessary so we want to avoid these from being compiled.  Re-do
 617    reachability starting from variables that are either externally visible
 618    or was referred from the asm output routines.  */
 619
 620 void
 621 symbol_table::remove_unreferenced_decls (void)
 622 {
 623   varpool_node *next, *node;
 624   varpool_node *first = (varpool_node *)(void *)1;
 625   int i;
 626   ipa_ref *ref = NULL;
 627   hash_set<varpool_node *> referenced;
 628
 629   if (seen_error ())
 630     return;
 631
 632   if (dump_file)
 633     fprintf (dump_file, "Trivially needed variables:");
 634   FOR_EACH_DEFINED_VARIABLE (node)
 635     {
 636       if (node->analyzed
 637           && (!node->can_remove_if_no_refs_p ()
 638               /* We just expanded all function bodies.  See if any of
 639                  them needed the variable.  */
 640               || DECL_RTL_SET_P (node->decl)))
 641         {
 642           enqueue_node (node, &first);
 643           if (dump_file)
 644             fprintf (dump_file, " %s", node->asm_name ());
 645         }
 646     }
 647   while (first != (varpool_node *)(void *)1)
 648     {
 649       node = first;
 650       first = (varpool_node *)first->aux;
 651
 652       if (node->same_comdat_group)
 653         {
 654           symtab_node *next;
 655           for (next = node->same_comdat_group;
 656                next != node;
 657                next = next->same_comdat_group)
 658             {
 659               varpool_node *vnext = dyn_cast <varpool_node *> (next);
 660               if (vnext && vnext->analyzed && !next->comdat_local_p ())
 661                 enqueue_node (vnext, &first);
 662             }
 663         }
 664       for (i = 0; node->iterate_reference (i, ref); i++)
 665         {
 666           varpool_node *vnode = dyn_cast <varpool_node *> (ref->referred);
 667           if (vnode
 668               && !vnode->in_other_partition
 669               && (!DECL_EXTERNAL (ref->referred->decl)
 670                   || vnode->alias)
 671               && vnode->analyzed)
 672             enqueue_node (vnode, &first);
 673           else
 674             {
 675               referenced.add (vnode);
 676               while (vnode && vnode->alias && vnode->definition)
 677                 {
 678                   vnode = vnode->get_alias_target ();
 679                   referenced.add (vnode);
 680                 }
 681             }
 682         }
 683     }
 684   if (dump_file)
 685     fprintf (dump_file, "\nRemoving variables:");
 686   for (node = first_defined_variable (); node; node = next)
 687     {
 688       next = next_defined_variable (node);
 689       if (!node->aux && !node->no_reorder)
 690         {
 691           if (dump_file)
 692             fprintf (dump_file, " %s", node->asm_name ());
 693           if (referenced.contains(node))
 694             node->remove_initializer ();
 695           else
 696             node->remove ();
 697         }
 698     }
 699
 700   if (dump_file)
 701     fprintf (dump_file, "\n");
 702 }
 703
 704 /* For variables in named sections make sure get_variable_section
 705    is called before we switch to those sections.  Then section
 706    conflicts between read-only and read-only requiring relocations
 707    sections can be resolved.  */
 708 void
 709 varpool_node::finalize_named_section_flags (void)
 710 {
 711   if (!TREE_ASM_WRITTEN (decl)
 712       && !alias
 713       && !in_other_partition
 714       && !DECL_EXTERNAL (decl)
 715       && VAR_P (decl)
 716       && !DECL_HAS_VALUE_EXPR_P (decl)
 717       && get_section ())
 718     get_variable_section (decl, false);
 719 }
 720
 721 /* Output all variables enqueued to be assembled.  */
 722 bool
 723 symbol_table::output_variables (void)
 724 {
 725   bool changed = false;
 726   varpool_node *node;
 727
 728   if (seen_error ())
 729     return false;
 730
 731   remove_unreferenced_decls ();
 732
 733   timevar_push (TV_VAROUT);
 734
 735   FOR_EACH_DEFINED_VARIABLE (node)
 736     {
 737       /* Handled in output_in_order.  */
 738       if (node->no_reorder)
 739         continue;
 740
 741       node->finalize_named_section_flags ();
 742     }
 743
 744   /* There is a similar loop in output_in_order.  Please keep them in sync.  */
 745   FOR_EACH_VARIABLE (node)
 746     {
 747       /* Handled in output_in_order.  */
 748       if (node->no_reorder)
 749         continue;
 750       if (DECL_HARD_REGISTER (node->decl)
 751           || DECL_HAS_VALUE_EXPR_P (node->decl))
 752         continue;
 753       if (node->definition)
 754         changed |= node->assemble_decl ();
 755       else
 756         assemble_undefined_decl (node->decl);
 757     }
 758   timevar_pop (TV_VAROUT);
 759   return changed;
 760 }
 761
 762 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 763    Extra name aliases are output whenever DECL is output.  */
 764
 765 varpool_node *
 766 varpool_node::create_alias (tree alias, tree decl)
 767 {
 768   varpool_node *alias_node;
 769
 770   gcc_assert (VAR_P (decl));
 771   gcc_assert (VAR_P (alias));
 772   alias_node = varpool_node::get_create (alias);
 773   alias_node->alias = true;
 774   alias_node->definition = true;
 775   alias_node->alias_target = decl;
 776   if (lookup_attribute ("weakref", DECL_ATTRIBUTES (alias)) != NULL)
 777     alias_node->weakref = alias_node->transparent_alias = true;
 778   return alias_node;
 779 }
 780
 781 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 782    Extra name aliases are output whenever DECL is output.  */
 783
 784 varpool_node *
 785 varpool_node::create_extra_name_alias (tree alias, tree decl)
 786 {
 787   varpool_node *alias_node;
 788
 789 #ifndef ASM_OUTPUT_DEF
 790   /* If aliases aren't supported by the assembler, fail.  */
 791   return NULL;
 792 #endif
 793   alias_node = varpool_node::create_alias (alias, decl);
 794   alias_node->cpp_implicit_alias = true;
 795
 796   /* Extra name alias mechanizm creates aliases really late
 797      via DECL_ASSEMBLER_NAME mechanizm.
 798      This is unfortunate because they are not going through the
 799      standard channels.  Ensure they get output.  */
 800   if (symtab->cpp_implicit_aliases_done)
 801     alias_node->resolve_alias (varpool_node::get_create (decl));
 802   return alias_node;
 803 }
 804
 805 /* Worker for call_for_symbol_and_aliases.  */
 806
 807 bool
 808 varpool_node::call_for_symbol_and_aliases_1 (bool (*callback) (varpool_node *,
 809                                                                void *),
 810                                              void *data,
 811                                              bool include_overwritable)
 812 {
 813   ipa_ref *ref;
 814
 815   FOR_EACH_ALIAS (this, ref)
 816     {
 817       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 818       if (include_overwritable
 819           || alias->get_availability () > AVAIL_INTERPOSABLE)
 820         if (alias->call_for_symbol_and_aliases (callback, data,
 821                                                 include_overwritable))
 822           return true;
 823     }
 824   return false;
 825 }