gcc/varpool.c

   1 /* Callgraph handling code.
   2    Copyright (C) 2003-2019 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 #include "stringpool.h"
  37 #include "attribs.h"
  38
  39 const char * const tls_model_names[]={"none", "emulated",
  40                                       "global-dynamic", "local-dynamic",
  41                                       "initial-exec", "local-exec"};
  42
  43 /* List of hooks triggered on varpool_node events.  */
  44 struct varpool_node_hook_list {
  45   varpool_node_hook hook;
  46   void *data;
  47   struct varpool_node_hook_list *next;
  48 };
  49
  50 /* Register HOOK to be called with DATA on each removed node.  */
  51 varpool_node_hook_list *
  52 symbol_table::add_varpool_removal_hook (varpool_node_hook hook, void *data)
  53 {
  54   varpool_node_hook_list *entry;
  55   varpool_node_hook_list **ptr = &m_first_varpool_removal_hook;
  56
  57   entry = (varpool_node_hook_list *) xmalloc (sizeof (*entry));
  58   entry->hook = hook;
  59   entry->data = data;
  60   entry->next = NULL;
  61   while (*ptr)
  62     ptr = &(*ptr)->next;
  63   *ptr = entry;
  64   return entry;
  65 }
  66
  67 /* Remove ENTRY from the list of hooks called on removing nodes.  */
  68 void
  69 symbol_table::remove_varpool_removal_hook (varpool_node_hook_list *entry)
  70 {
  71   varpool_node_hook_list **ptr = &m_first_varpool_removal_hook;
  72
  73   while (*ptr != entry)
  74     ptr = &(*ptr)->next;
  75   *ptr = entry->next;
  76   free (entry);
  77 }
  78
  79 /* Call all node removal hooks.  */
  80 void
  81 symbol_table::call_varpool_removal_hooks (varpool_node *node)
  82 {
  83   varpool_node_hook_list *entry = m_first_varpool_removal_hook;
  84   while (entry)
  85   {
  86     entry->hook (node, entry->data);
  87     entry = entry->next;
  88   }
  89 }
  90
  91 /* Register HOOK to be called with DATA on each inserted node.  */
  92 varpool_node_hook_list *
  93 symbol_table::add_varpool_insertion_hook (varpool_node_hook hook, void *data)
  94 {
  95   varpool_node_hook_list *entry;
  96   varpool_node_hook_list **ptr = &m_first_varpool_insertion_hook;
  97
  98   entry = (varpool_node_hook_list *) xmalloc (sizeof (*entry));
  99   entry->hook = hook;
 100   entry->data = data;
 101   entry->next = NULL;
 102   while (*ptr)
 103     ptr = &(*ptr)->next;
 104   *ptr = entry;
 105   return entry;
 106 }
 107
 108 /* Remove ENTRY from the list of hooks called on inserted nodes.  */
 109 void
 110 symbol_table::remove_varpool_insertion_hook (varpool_node_hook_list *entry)
 111 {
 112   varpool_node_hook_list **ptr = &m_first_varpool_insertion_hook;
 113
 114   while (*ptr != entry)
 115     ptr = &(*ptr)->next;
 116   *ptr = entry->next;
 117   free (entry);
 118 }
 119
 120 /* Call all node insertion hooks.  */
 121 void
 122 symbol_table::call_varpool_insertion_hooks (varpool_node *node)
 123 {
 124   varpool_node_hook_list *entry = m_first_varpool_insertion_hook;
 125   while (entry)
 126   {
 127     entry->hook (node, entry->data);
 128     entry = entry->next;
 129   }
 130 }
 131
 132 /* Allocate new callgraph node and insert it into basic data structures.  */
 133
 134 varpool_node *
 135 varpool_node::create_empty (void)
 136 {
 137   varpool_node *node = ggc_cleared_alloc<varpool_node> ();
 138   node->type = SYMTAB_VARIABLE;
 139   return node;
 140 }
 141
 142 /* Return varpool node assigned to DECL.  Create new one when needed.  */
 143 varpool_node *
 144 varpool_node::get_create (tree decl)
 145 {
 146   varpool_node *node = varpool_node::get (decl);
 147   gcc_checking_assert (VAR_P (decl));
 148   if (node)
 149     return node;
 150
 151   node = varpool_node::create_empty ();
 152   node->decl = decl;
 153
 154   if ((flag_openacc || flag_openmp)
 155       && lookup_attribute ("omp declare target", DECL_ATTRIBUTES (decl)))
 156     {
 157       node->offloadable = 1;
 158       if (ENABLE_OFFLOADING && !DECL_EXTERNAL (decl))
 159         {
 160           g->have_offload = true;
 161           if (!in_lto_p)
 162             vec_safe_push (offload_vars, decl);
 163         }
 164     }
 165
 166   node->register_symbol ();
 167   return node;
 168 }
 169
 170 /* Remove variable from symbol table.  */
 171
 172 void
 173 varpool_node::remove (void)
 174 {
 175   symtab->call_varpool_removal_hooks (this);
 176   if (lto_file_data)
 177     {
 178       lto_free_function_in_decl_state_for_node (this);
 179       lto_file_data = NULL;
 180     }
 181
 182   /* When streaming we can have multiple nodes associated with decl.  */
 183   if (symtab->state == LTO_STREAMING)
 184     ;
 185   /* Keep constructor when it may be used for folding. We remove
 186      references to external variables before final compilation.  */
 187   else if (DECL_INITIAL (decl) && DECL_INITIAL (decl) != error_mark_node
 188            && !ctor_useable_for_folding_p ())
 189     remove_initializer ();
 190
 191   unregister ();
 192   ggc_free (this);
 193 }
 194
 195 /* Remove node initializer when it is no longer needed.  */
 196 void
 197 varpool_node::remove_initializer (void)
 198 {
 199   if (DECL_INITIAL (decl)
 200       && !DECL_IN_CONSTANT_POOL (decl)
 201       /* Keep vtables for BINFO folding.  */
 202       && !DECL_VIRTUAL_P (decl)
 203       /* FIXME: http://gcc.gnu.org/PR55395 */
 204       && debug_info_level == DINFO_LEVEL_NONE
 205       /* When doing declaration merging we have duplicate
 206          entries for given decl.  Do not attempt to remove
 207          the boides, or we will end up remiving
 208          wrong one.  */
 209       && symtab->state != LTO_STREAMING)
 210     DECL_INITIAL (decl) = error_mark_node;
 211 }
 212
 213 /* Dump given varpool node to F.  */
 214 void
 215 varpool_node::dump (FILE *f)
 216 {
 217   dump_base (f);
 218   fprintf (f, "  Availability: %s\n",
 219            symtab->function_flags_ready
 220            ? cgraph_availability_names[get_availability ()]
 221            : "not-ready");
 222   fprintf (f, "  Varpool flags:");
 223   if (DECL_INITIAL (decl))
 224     fprintf (f, " initialized");
 225   if (output)
 226     fprintf (f, " output");
 227   if (used_by_single_function)
 228     fprintf (f, " used-by-single-function");
 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   if (!quiet_flag)
 309     fprintf (stderr, " in:%s", IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl)));
 310   lto_input_variable_constructor (file_data, this, data);
 311   gcc_assert (DECL_INITIAL (decl) != error_mark_node);
 312   lto_stats.num_function_bodies++;
 313   lto_free_section_data (file_data, LTO_section_function_body, name,
 314                          data, len, decl_state->compressed);
 315   lto_free_function_in_decl_state_for_node (this);
 316   timevar_pop (TV_IPA_LTO_CTORS_IN);
 317   return DECL_INITIAL (decl);
 318 }
 319
 320 /* Return true if variable has constructor that can be used for folding.  */
 321
 322 bool
 323 varpool_node::ctor_useable_for_folding_p (void)
 324 {
 325   varpool_node *real_node = this;
 326
 327   if (real_node->alias && real_node->definition)
 328     real_node = ultimate_alias_target ();
 329
 330   if (TREE_CODE (decl) == CONST_DECL
 331       || DECL_IN_CONSTANT_POOL (decl))
 332     return true;
 333   if (TREE_THIS_VOLATILE (decl))
 334     return false;
 335
 336   /* Avoid attempts to load constructors that was not streamed.  */
 337   if (in_lto_p && DECL_INITIAL (real_node->decl) == error_mark_node
 338       && real_node->body_removed)
 339     return false;
 340
 341   /* If we do not have a constructor, we can't use it.  */
 342   if (DECL_INITIAL (real_node->decl) == error_mark_node
 343       && !real_node->lto_file_data)
 344     return false;
 345
 346   /* Vtables are defined by their types and must match no matter of interposition
 347      rules.  */
 348   if (DECL_VIRTUAL_P (decl))
 349     {
 350       /* The C++ front end creates VAR_DECLs for vtables of typeinfo
 351          classes not defined in the current TU so that it can refer
 352          to them from typeinfo objects.  Avoid returning NULL_TREE.  */
 353       return DECL_INITIAL (real_node->decl) != NULL;
 354     }
 355
 356   /* Alias of readonly variable is also readonly, since the variable is stored
 357      in readonly memory.  We also accept readonly aliases of non-readonly
 358      locations assuming that user knows what he is asking for.  */
 359   if (!TREE_READONLY (decl) && !TREE_READONLY (real_node->decl))
 360     return false;
 361
 362   /* Variables declared 'const' without an initializer
 363      have zero as the initializer if they may not be
 364      overridden at link or run time.
 365
 366      It is actually requirement for C++ compiler to optimize const variables
 367      consistently. As a GNU extension, do not enfore this rule for user defined
 368      weak variables, so we support interposition on:
 369      static const int dummy = 0;
 370      extern const int foo __attribute__((__weak__, __alias__("dummy")));
 371    */
 372   if ((!DECL_INITIAL (real_node->decl)
 373        || (DECL_WEAK (decl) && !DECL_COMDAT (decl)))
 374       && (DECL_EXTERNAL (decl) || 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 /* If DECLARATION is constant variable and its initial value is known
 386    (so we can do constant folding), return its constructor (DECL_INITIAL).
 387    This may be an expression or NULL when DECL is initialized to 0.
 388    Return ERROR_MARK_NODE otherwise.
 389
 390    In LTO this may actually trigger reading the constructor from disk.
 391    For this reason varpool_ctor_useable_for_folding_p should be used when
 392    the actual constructor value is not needed.  */
 393
 394 tree
 395 ctor_for_folding (tree decl)
 396 {
 397   varpool_node *node, *real_node;
 398   tree real_decl;
 399
 400   if (!VAR_P (decl) && TREE_CODE (decl) != CONST_DECL)
 401     return error_mark_node;
 402
 403   if (TREE_CODE (decl) == CONST_DECL
 404       || DECL_IN_CONSTANT_POOL (decl))
 405     return DECL_INITIAL (decl);
 406
 407   if (TREE_THIS_VOLATILE (decl))
 408     return error_mark_node;
 409
 410   /* Do not care about automatic variables.  Those are never initialized
 411      anyway, because gimplifier exapnds the code.  */
 412   if (!TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
 413     {
 414       gcc_assert (!TREE_PUBLIC (decl));
 415       return error_mark_node;
 416     }
 417
 418   gcc_assert (VAR_P (decl));
 419
 420   real_node = node = varpool_node::get (decl);
 421   if (node)
 422     {
 423       real_node = node->ultimate_alias_target ();
 424       real_decl = real_node->decl;
 425     }
 426   else
 427     real_decl = decl;
 428
 429   /* See if we are dealing with alias.
 430      In most cases alias is just alternative symbol pointing to a given
 431      constructor.  This allows us to use interposition rules of DECL
 432      constructor of REAL_NODE.  However weakrefs are special by being just
 433      alternative name of their target (if defined).  */
 434   if (decl != real_decl)
 435     {
 436       gcc_assert (!DECL_INITIAL (decl)
 437                   || (node->alias && node->get_alias_target () == real_node)
 438                   || DECL_INITIAL (decl) == error_mark_node);
 439       while (node->transparent_alias && node->analyzed)
 440         {
 441           node = node->get_alias_target ();
 442           decl = node->decl;
 443         }
 444     }
 445
 446   if ((!DECL_VIRTUAL_P (real_decl)
 447        || DECL_INITIAL (real_decl) == error_mark_node
 448        || !DECL_INITIAL (real_decl))
 449       && (!node || !node->ctor_useable_for_folding_p ()))
 450     return error_mark_node;
 451
 452   /* OK, we can return constructor.  See if we need to fetch it from disk
 453      in LTO mode.  */
 454   if (DECL_INITIAL (real_decl) != error_mark_node
 455       || !in_lto_p)
 456     return DECL_INITIAL (real_decl);
 457   return real_node->get_constructor ();
 458 }
 459
 460 /* Add the variable DECL to the varpool.
 461    Unlike finalize_decl function is intended to be used
 462    by middle end and allows insertion of new variable at arbitrary point
 463    of compilation.  */
 464 void
 465 varpool_node::add (tree decl)
 466 {
 467   varpool_node *node;
 468   varpool_node::finalize_decl (decl);
 469   node = varpool_node::get_create (decl);
 470   symtab->call_varpool_insertion_hooks (node);
 471   if (node->externally_visible_p ())
 472     node->externally_visible = true;
 473   if (lookup_attribute ("no_reorder", DECL_ATTRIBUTES (decl)))
 474     node->no_reorder = 1;
 475 }
 476
 477 /* Return variable availability.  See cgraph.h for description of individual
 478    return values.  */
 479 enum availability
 480 varpool_node::get_availability (symtab_node *ref)
 481 {
 482   if (!definition)
 483     return AVAIL_NOT_AVAILABLE;
 484   if (!TREE_PUBLIC (decl))
 485     return AVAIL_AVAILABLE;
 486   if (DECL_IN_CONSTANT_POOL (decl)
 487       || DECL_VIRTUAL_P (decl))
 488     return AVAIL_AVAILABLE;
 489   if (transparent_alias && definition)
 490     {
 491       enum availability avail;
 492
 493       ultimate_alias_target (&avail, ref);
 494       return avail;
 495     }
 496   /* If this is a reference from symbol itself and there are no aliases, we
 497      may be sure that the symbol was not interposed by something else because
 498      the symbol itself would be unreachable otherwise.  */
 499   if ((this == ref && !has_aliases_p ())
 500       || (ref && get_comdat_group ()
 501           && get_comdat_group () == ref->get_comdat_group ()))
 502     return AVAIL_AVAILABLE;
 503   /* If the variable can be overwritten, return OVERWRITABLE.  Takes
 504      care of at least one notable extension - the COMDAT variables
 505      used to share template instantiations in C++.  */
 506   if (decl_replaceable_p (decl)
 507       || DECL_EXTERNAL (decl))
 508     return AVAIL_INTERPOSABLE;
 509   return AVAIL_AVAILABLE;
 510 }
 511
 512 void
 513 varpool_node::analyze (void)
 514 {
 515   /* When reading back varpool at LTO time, we re-construct the queue in order
 516      to have "needed" list right by inserting all needed nodes into varpool.
 517      We however don't want to re-analyze already analyzed nodes.  */
 518   if (!analyzed)
 519     {
 520       gcc_assert (!in_lto_p || symtab->function_flags_ready);
 521       /* Compute the alignment early so function body expanders are
 522          already informed about increased alignment.  */
 523       align_variable (decl, 0);
 524     }
 525   if (alias)
 526     resolve_alias (varpool_node::get (alias_target));
 527   else if (DECL_INITIAL (decl))
 528     record_references_in_initializer (decl, analyzed);
 529   analyzed = true;
 530 }
 531
 532 /* Assemble thunks and aliases associated to varpool node.  */
 533
 534 void
 535 varpool_node::assemble_aliases (void)
 536 {
 537   ipa_ref *ref;
 538
 539   FOR_EACH_ALIAS (this, ref)
 540     {
 541       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 542       if (!alias->transparent_alias)
 543         do_assemble_alias (alias->decl,
 544                            DECL_ASSEMBLER_NAME (decl));
 545       alias->assemble_aliases ();
 546     }
 547 }
 548
 549 /* Output one variable, if necessary.  Return whether we output it.  */
 550
 551 bool
 552 varpool_node::assemble_decl (void)
 553 {
 554   /* Aliases are outout when their target is produced or by
 555      output_weakrefs.  */
 556   if (alias)
 557     return false;
 558
 559   /* Constant pool is output from RTL land when the reference
 560      survive till this level.  */
 561   if (DECL_IN_CONSTANT_POOL (decl) && TREE_ASM_WRITTEN (decl))
 562     return false;
 563
 564   /* Decls with VALUE_EXPR should not be in the varpool at all.  They
 565      are not real variables, but just info for debugging and codegen.
 566      Unfortunately at the moment emutls is not updating varpool correctly
 567      after turning real vars into value_expr vars.  */
 568   if (DECL_HAS_VALUE_EXPR_P (decl)
 569       && !targetm.have_tls)
 570     return false;
 571
 572   /* Hard register vars do not need to be output.  */
 573   if (DECL_HARD_REGISTER (decl))
 574     return false;
 575
 576   gcc_checking_assert (!TREE_ASM_WRITTEN (decl)
 577                        && VAR_P (decl)
 578                        && !DECL_HAS_VALUE_EXPR_P (decl));
 579
 580   if (!in_other_partition
 581       && !DECL_EXTERNAL (decl))
 582     {
 583       get_constructor ();
 584       assemble_variable (decl, 0, 1, 0);
 585       gcc_assert (TREE_ASM_WRITTEN (decl));
 586       gcc_assert (definition);
 587       assemble_aliases ();
 588       /* After the parser has generated debugging information, augment
 589          this information with any new location/etc information that may
 590          have become available after the compilation proper.  */
 591       debug_hooks->late_global_decl (decl);
 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       && VAR_P (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_DEFINED_VARIABLE (node)
 732     {
 733       /* Handled in output_in_order.  */
 734       if (node->no_reorder)
 735         continue;
 736
 737       node->finalize_named_section_flags ();
 738     }
 739
 740   /* There is a similar loop in output_in_order.  Please keep them in sync.  */
 741   FOR_EACH_VARIABLE (node)
 742     {
 743       /* Handled in output_in_order.  */
 744       if (node->no_reorder)
 745         continue;
 746       if (DECL_HARD_REGISTER (node->decl)
 747           || DECL_HAS_VALUE_EXPR_P (node->decl))
 748         continue;
 749       if (node->definition)
 750         changed |= node->assemble_decl ();
 751       else
 752         assemble_undefined_decl (node->decl);
 753     }
 754   timevar_pop (TV_VAROUT);
 755   return changed;
 756 }
 757
 758 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 759    Extra name aliases are output whenever DECL is output.  */
 760
 761 varpool_node *
 762 varpool_node::create_alias (tree alias, tree decl)
 763 {
 764   varpool_node *alias_node;
 765
 766   gcc_assert (VAR_P (decl));
 767   gcc_assert (VAR_P (alias));
 768   alias_node = varpool_node::get_create (alias);
 769   alias_node->alias = true;
 770   alias_node->definition = true;
 771   alias_node->alias_target = decl;
 772   if (lookup_attribute ("weakref", DECL_ATTRIBUTES (alias)) != NULL)
 773     alias_node->weakref = alias_node->transparent_alias = true;
 774   return alias_node;
 775 }
 776
 777 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 778    Extra name aliases are output whenever DECL is output.  */
 779
 780 varpool_node *
 781 varpool_node::create_extra_name_alias (tree alias, tree decl)
 782 {
 783   varpool_node *alias_node;
 784
 785   /* If aliases aren't supported by the assembler, fail.  */
 786   if (!TARGET_SUPPORTS_ALIASES)
 787     return NULL;
 788
 789   alias_node = varpool_node::create_alias (alias, decl);
 790   alias_node->cpp_implicit_alias = true;
 791
 792   /* Extra name alias mechanizm creates aliases really late
 793      via DECL_ASSEMBLER_NAME mechanizm.
 794      This is unfortunate because they are not going through the
 795      standard channels.  Ensure they get output.  */
 796   if (symtab->cpp_implicit_aliases_done)
 797     alias_node->resolve_alias (varpool_node::get_create (decl));
 798   return alias_node;
 799 }
 800
 801 /* Worker for call_for_symbol_and_aliases.  */
 802
 803 bool
 804 varpool_node::call_for_symbol_and_aliases_1 (bool (*callback) (varpool_node *,
 805                                                                void *),
 806                                              void *data,
 807                                              bool include_overwritable)
 808 {
 809   ipa_ref *ref;
 810
 811   FOR_EACH_ALIAS (this, ref)
 812     {
 813       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 814       if (include_overwritable
 815           || alias->get_availability () > AVAIL_INTERPOSABLE)
 816         if (alias->call_for_symbol_and_aliases (callback, data,
 817                                                 include_overwritable))
 818           return true;
 819     }
 820   return false;
 821 }