gcc/varpool.c

   1 /* Callgraph handling code.
   2    Copyright (C) 2003-2016 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-low.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 (TREE_CODE (decl) == VAR_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) && !DECL_EXTERNAL (decl)
 153       && lookup_attribute ("omp declare target", DECL_ATTRIBUTES (decl)))
 154     {
 155       node->offloadable = 1;
 156       if (ENABLE_OFFLOADING)
 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 (TREE_CODE (decl) != VAR_DECL
 399       && TREE_CODE (decl) != CONST_DECL)
 400     return error_mark_node;
 401
 402   /* Static constant bounds are created to be
 403      used instead of constants and therefore
 404      do not let folding it.  */
 405   if (POINTER_BOUNDS_P (decl))
 406     return error_mark_node;
 407
 408   if (TREE_CODE (decl) == CONST_DECL
 409       || DECL_IN_CONSTANT_POOL (decl))
 410     return DECL_INITIAL (decl);
 411
 412   if (TREE_THIS_VOLATILE (decl))
 413     return error_mark_node;
 414
 415   /* Do not care about automatic variables.  Those are never initialized
 416      anyway, because gimplifier exapnds the code.  */
 417   if (!TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
 418     {
 419       gcc_assert (!TREE_PUBLIC (decl));
 420       return error_mark_node;
 421     }
 422
 423   gcc_assert (TREE_CODE (decl) == VAR_DECL);
 424
 425   real_node = node = varpool_node::get (decl);
 426   if (node)
 427     {
 428       real_node = node->ultimate_alias_target ();
 429       real_decl = real_node->decl;
 430     }
 431   else
 432     real_decl = decl;
 433
 434   /* See if we are dealing with alias.
 435      In most cases alias is just alternative symbol pointing to a given
 436      constructor.  This allows us to use interposition rules of DECL
 437      constructor of REAL_NODE.  However weakrefs are special by being just
 438      alternative name of their target (if defined).  */
 439   if (decl != real_decl)
 440     {
 441       gcc_assert (!DECL_INITIAL (decl)
 442                   || (node->alias && node->get_alias_target () == real_node)
 443                   || DECL_INITIAL (decl) == error_mark_node);
 444       while (node->transparent_alias && node->analyzed)
 445         {
 446           node = node->get_alias_target ();
 447           decl = node->decl;
 448         }
 449     }
 450
 451   if ((!DECL_VIRTUAL_P (real_decl)
 452        || DECL_INITIAL (real_decl) == error_mark_node
 453        || !DECL_INITIAL (real_decl))
 454       && (!node || !node->ctor_useable_for_folding_p ()))
 455     return error_mark_node;
 456
 457   /* OK, we can return constructor.  See if we need to fetch it from disk
 458      in LTO mode.  */
 459   if (DECL_INITIAL (real_decl) != error_mark_node
 460       || !in_lto_p)
 461     return DECL_INITIAL (real_decl);
 462   return real_node->get_constructor ();
 463 }
 464
 465 /* Add the variable DECL to the varpool.
 466    Unlike finalize_decl function is intended to be used
 467    by middle end and allows insertion of new variable at arbitrary point
 468    of compilation.  */
 469 void
 470 varpool_node::add (tree decl)
 471 {
 472   varpool_node *node;
 473   varpool_node::finalize_decl (decl);
 474   node = varpool_node::get_create (decl);
 475   symtab->call_varpool_insertion_hooks (node);
 476   if (node->externally_visible_p ())
 477     node->externally_visible = true;
 478   if (lookup_attribute ("no_reorder", DECL_ATTRIBUTES (decl)))
 479     node->no_reorder = 1;
 480 }
 481
 482 /* Return variable availability.  See cgraph.h for description of individual
 483    return values.  */
 484 enum availability
 485 varpool_node::get_availability (void)
 486 {
 487   if (!definition)
 488     return AVAIL_NOT_AVAILABLE;
 489   if (!TREE_PUBLIC (decl))
 490     return AVAIL_AVAILABLE;
 491   if (DECL_IN_CONSTANT_POOL (decl)
 492       || DECL_VIRTUAL_P (decl))
 493     return AVAIL_AVAILABLE;
 494   if (transparent_alias && definition)
 495     {
 496       enum availability avail;
 497
 498       ultimate_alias_target (&avail);
 499       return avail;
 500     }
 501   /* If the variable can be overwritten, return OVERWRITABLE.  Takes
 502      care of at least one notable extension - the COMDAT variables
 503      used to share template instantiations in C++.  */
 504   if (decl_replaceable_p (decl)
 505       || DECL_EXTERNAL (decl))
 506     return AVAIL_INTERPOSABLE;
 507   return AVAIL_AVAILABLE;
 508 }
 509
 510 void
 511 varpool_node::analyze (void)
 512 {
 513   /* When reading back varpool at LTO time, we re-construct the queue in order
 514      to have "needed" list right by inserting all needed nodes into varpool.
 515      We however don't want to re-analyze already analyzed nodes.  */
 516   if (!analyzed)
 517     {
 518       gcc_assert (!in_lto_p || symtab->function_flags_ready);
 519       /* Compute the alignment early so function body expanders are
 520          already informed about increased alignment.  */
 521       align_variable (decl, 0);
 522     }
 523   if (alias)
 524     resolve_alias (varpool_node::get (alias_target));
 525   else if (DECL_INITIAL (decl))
 526     record_references_in_initializer (decl, analyzed);
 527   analyzed = true;
 528 }
 529
 530 /* Assemble thunks and aliases associated to varpool node.  */
 531
 532 void
 533 varpool_node::assemble_aliases (void)
 534 {
 535   ipa_ref *ref;
 536
 537   FOR_EACH_ALIAS (this, ref)
 538     {
 539       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 540       if (!alias->transparent_alias)
 541         do_assemble_alias (alias->decl,
 542                            DECL_ASSEMBLER_NAME (decl));
 543       alias->assemble_aliases ();
 544     }
 545 }
 546
 547 /* Output one variable, if necessary.  Return whether we output it.  */
 548
 549 bool
 550 varpool_node::assemble_decl (void)
 551 {
 552   /* Aliases are outout when their target is produced or by
 553      output_weakrefs.  */
 554   if (alias)
 555     return false;
 556
 557   /* Constant pool is output from RTL land when the reference
 558      survive till this level.  */
 559   if (DECL_IN_CONSTANT_POOL (decl) && TREE_ASM_WRITTEN (decl))
 560     return false;
 561
 562   /* Decls with VALUE_EXPR should not be in the varpool at all.  They
 563      are not real variables, but just info for debugging and codegen.
 564      Unfortunately at the moment emutls is not updating varpool correctly
 565      after turning real vars into value_expr vars.  */
 566   if (DECL_HAS_VALUE_EXPR_P (decl)
 567       && !targetm.have_tls)
 568     return false;
 569
 570   /* Hard register vars do not need to be output.  */
 571   if (DECL_HARD_REGISTER (decl))
 572     return false;
 573
 574   gcc_checking_assert (!TREE_ASM_WRITTEN (decl)
 575                        && TREE_CODE (decl) == VAR_DECL
 576                        && !DECL_HAS_VALUE_EXPR_P (decl));
 577
 578   if (!in_other_partition
 579       && !DECL_EXTERNAL (decl))
 580     {
 581       get_constructor ();
 582       assemble_variable (decl, 0, 1, 0);
 583       gcc_assert (TREE_ASM_WRITTEN (decl));
 584       gcc_assert (definition);
 585       assemble_aliases ();
 586       /* After the parser has generated debugging information, augment
 587          this information with any new location/etc information that may
 588          have become available after the compilation proper.  */
 589       timevar_start (TV_PHASE_DBGINFO);
 590       debug_hooks->late_global_decl (decl);
 591       timevar_stop (TV_PHASE_DBGINFO);
 592       return true;
 593     }
 594
 595   return false;
 596 }
 597
 598 /* Add NODE to queue starting at FIRST.
 599    The queue is linked via AUX pointers and terminated by pointer to 1.  */
 600
 601 static void
 602 enqueue_node (varpool_node *node, varpool_node **first)
 603 {
 604   if (node->aux)
 605     return;
 606   gcc_checking_assert (*first);
 607   node->aux = *first;
 608   *first = node;
 609 }
 610
 611 /* Optimization of function bodies might've rendered some variables as
 612    unnecessary so we want to avoid these from being compiled.  Re-do
 613    reachability starting from variables that are either externally visible
 614    or was referred from the asm output routines.  */
 615
 616 void
 617 symbol_table::remove_unreferenced_decls (void)
 618 {
 619   varpool_node *next, *node;
 620   varpool_node *first = (varpool_node *)(void *)1;
 621   int i;
 622   ipa_ref *ref = NULL;
 623   hash_set<varpool_node *> referenced;
 624
 625   if (seen_error ())
 626     return;
 627
 628   if (dump_file)
 629     fprintf (dump_file, "Trivially needed variables:");
 630   FOR_EACH_DEFINED_VARIABLE (node)
 631     {
 632       if (node->analyzed
 633           && (!node->can_remove_if_no_refs_p ()
 634               /* We just expanded all function bodies.  See if any of
 635                  them needed the variable.  */
 636               || DECL_RTL_SET_P (node->decl)))
 637         {
 638           enqueue_node (node, &first);
 639           if (dump_file)
 640             fprintf (dump_file, " %s", node->asm_name ());
 641         }
 642     }
 643   while (first != (varpool_node *)(void *)1)
 644     {
 645       node = first;
 646       first = (varpool_node *)first->aux;
 647
 648       if (node->same_comdat_group)
 649         {
 650           symtab_node *next;
 651           for (next = node->same_comdat_group;
 652                next != node;
 653                next = next->same_comdat_group)
 654             {
 655               varpool_node *vnext = dyn_cast <varpool_node *> (next);
 656               if (vnext && vnext->analyzed && !next->comdat_local_p ())
 657                 enqueue_node (vnext, &first);
 658             }
 659         }
 660       for (i = 0; node->iterate_reference (i, ref); i++)
 661         {
 662           varpool_node *vnode = dyn_cast <varpool_node *> (ref->referred);
 663           if (vnode
 664               && !vnode->in_other_partition
 665               && (!DECL_EXTERNAL (ref->referred->decl)
 666                   || vnode->alias)
 667               && vnode->analyzed)
 668             enqueue_node (vnode, &first);
 669           else
 670             {
 671               referenced.add (vnode);
 672               while (vnode && vnode->alias && vnode->definition)
 673                 {
 674                   vnode = vnode->get_alias_target ();
 675                   referenced.add (vnode);
 676                 }
 677             }
 678         }
 679     }
 680   if (dump_file)
 681     fprintf (dump_file, "\nRemoving variables:");
 682   for (node = first_defined_variable (); node; node = next)
 683     {
 684       next = next_defined_variable (node);
 685       if (!node->aux && !node->no_reorder)
 686         {
 687           if (dump_file)
 688             fprintf (dump_file, " %s", node->asm_name ());
 689           if (referenced.contains(node))
 690             node->remove_initializer ();
 691           else
 692             node->remove ();
 693         }
 694     }
 695
 696   if (dump_file)
 697     fprintf (dump_file, "\n");
 698 }
 699
 700 /* For variables in named sections make sure get_variable_section
 701    is called before we switch to those sections.  Then section
 702    conflicts between read-only and read-only requiring relocations
 703    sections can be resolved.  */
 704 void
 705 varpool_node::finalize_named_section_flags (void)
 706 {
 707   if (!TREE_ASM_WRITTEN (decl)
 708       && !alias
 709       && !in_other_partition
 710       && !DECL_EXTERNAL (decl)
 711       && TREE_CODE (decl) == VAR_DECL
 712       && !DECL_HAS_VALUE_EXPR_P (decl)
 713       && get_section ())
 714     get_variable_section (decl, false);
 715 }
 716
 717 /* Output all variables enqueued to be assembled.  */
 718 bool
 719 symbol_table::output_variables (void)
 720 {
 721   bool changed = false;
 722   varpool_node *node;
 723
 724   if (seen_error ())
 725     return false;
 726
 727   remove_unreferenced_decls ();
 728
 729   timevar_push (TV_VAROUT);
 730
 731   FOR_EACH_VARIABLE (node)
 732     if (!node->definition
 733         && !DECL_HAS_VALUE_EXPR_P (node->decl)
 734         && !DECL_HARD_REGISTER (node->decl))
 735       assemble_undefined_decl (node->decl);
 736   FOR_EACH_DEFINED_VARIABLE (node)
 737     {
 738       /* Handled in output_in_order.  */
 739       if (node->no_reorder)
 740         continue;
 741
 742       node->finalize_named_section_flags ();
 743     }
 744
 745   FOR_EACH_DEFINED_VARIABLE (node)
 746     {
 747       /* Handled in output_in_order.  */
 748       if (node->no_reorder)
 749         continue;
 750 #ifdef ACCEL_COMPILER
 751       /* Do not assemble "omp declare target link" vars.  */
 752       if (DECL_HAS_VALUE_EXPR_P (node->decl)
 753           && lookup_attribute ("omp declare target link",
 754                                DECL_ATTRIBUTES (node->decl)))
 755         continue;
 756 #endif
 757       if (node->assemble_decl ())
 758         changed = true;
 759     }
 760   timevar_pop (TV_VAROUT);
 761   return changed;
 762 }
 763
 764 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 765    Extra name aliases are output whenever DECL is output.  */
 766
 767 varpool_node *
 768 varpool_node::create_alias (tree alias, tree decl)
 769 {
 770   varpool_node *alias_node;
 771
 772   gcc_assert (TREE_CODE (decl) == VAR_DECL);
 773   gcc_assert (TREE_CODE (alias) == VAR_DECL);
 774   alias_node = varpool_node::get_create (alias);
 775   alias_node->alias = true;
 776   alias_node->definition = true;
 777   alias_node->alias_target = decl;
 778   if (lookup_attribute ("weakref", DECL_ATTRIBUTES (alias)) != NULL)
 779     alias_node->weakref = alias_node->transparent_alias = true;
 780   return alias_node;
 781 }
 782
 783 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 784    Extra name aliases are output whenever DECL is output.  */
 785
 786 varpool_node *
 787 varpool_node::create_extra_name_alias (tree alias, tree decl)
 788 {
 789   varpool_node *alias_node;
 790
 791 #ifndef ASM_OUTPUT_DEF
 792   /* If aliases aren't supported by the assembler, fail.  */
 793   return NULL;
 794 #endif
 795   alias_node = varpool_node::create_alias (alias, decl);
 796   alias_node->cpp_implicit_alias = true;
 797
 798   /* Extra name alias mechanizm creates aliases really late
 799      via DECL_ASSEMBLER_NAME mechanizm.
 800      This is unfortunate because they are not going through the
 801      standard channels.  Ensure they get output.  */
 802   if (symtab->cpp_implicit_aliases_done)
 803     alias_node->resolve_alias (varpool_node::get_create (decl));
 804   return alias_node;
 805 }
 806
 807 /* Worker for call_for_symbol_and_aliases.  */
 808
 809 bool
 810 varpool_node::call_for_symbol_and_aliases_1 (bool (*callback) (varpool_node *,
 811                                                                void *),
 812                                              void *data,
 813                                              bool include_overwritable)
 814 {
 815   ipa_ref *ref;
 816
 817   FOR_EACH_ALIAS (this, ref)
 818     {
 819       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 820       if (include_overwritable
 821           || alias->get_availability () > AVAIL_INTERPOSABLE)
 822         if (alias->call_for_symbol_and_aliases (callback, data,
 823                                                 include_overwritable))
 824           return true;
 825     }
 826   return false;
 827 }