gcc/varpool.cc

   1 /* Callgraph handling code.
   2    Copyright (C) 2003-2022 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 #include "tree-pass.h"
  39
  40 const char * const tls_model_names[]={"none", "emulated",
  41                                       "global-dynamic", "local-dynamic",
  42                                       "initial-exec", "local-exec"};
  43
  44 /* List of hooks triggered on varpool_node events.  */
  45 struct varpool_node_hook_list {
  46   varpool_node_hook hook;
  47   void *data;
  48   struct varpool_node_hook_list *next;
  49 };
  50
  51 /* Register HOOK to be called with DATA on each removed node.  */
  52 varpool_node_hook_list *
  53 symbol_table::add_varpool_removal_hook (varpool_node_hook hook, void *data)
  54 {
  55   varpool_node_hook_list *entry;
  56   varpool_node_hook_list **ptr = &m_first_varpool_removal_hook;
  57
  58   entry = (varpool_node_hook_list *) xmalloc (sizeof (*entry));
  59   entry->hook = hook;
  60   entry->data = data;
  61   entry->next = NULL;
  62   while (*ptr)
  63     ptr = &(*ptr)->next;
  64   *ptr = entry;
  65   return entry;
  66 }
  67
  68 /* Remove ENTRY from the list of hooks called on removing nodes.  */
  69 void
  70 symbol_table::remove_varpool_removal_hook (varpool_node_hook_list *entry)
  71 {
  72   varpool_node_hook_list **ptr = &m_first_varpool_removal_hook;
  73
  74   while (*ptr != entry)
  75     ptr = &(*ptr)->next;
  76   *ptr = entry->next;
  77   free (entry);
  78 }
  79
  80 /* Call all node removal hooks.  */
  81 void
  82 symbol_table::call_varpool_removal_hooks (varpool_node *node)
  83 {
  84   varpool_node_hook_list *entry = m_first_varpool_removal_hook;
  85   while (entry)
  86   {
  87     entry->hook (node, entry->data);
  88     entry = entry->next;
  89   }
  90 }
  91
  92 /* Register HOOK to be called with DATA on each inserted node.  */
  93 varpool_node_hook_list *
  94 symbol_table::add_varpool_insertion_hook (varpool_node_hook hook, void *data)
  95 {
  96   varpool_node_hook_list *entry;
  97   varpool_node_hook_list **ptr = &m_first_varpool_insertion_hook;
  98
  99   entry = (varpool_node_hook_list *) xmalloc (sizeof (*entry));
 100   entry->hook = hook;
 101   entry->data = data;
 102   entry->next = NULL;
 103   while (*ptr)
 104     ptr = &(*ptr)->next;
 105   *ptr = entry;
 106   return entry;
 107 }
 108
 109 /* Remove ENTRY from the list of hooks called on inserted nodes.  */
 110 void
 111 symbol_table::remove_varpool_insertion_hook (varpool_node_hook_list *entry)
 112 {
 113   varpool_node_hook_list **ptr = &m_first_varpool_insertion_hook;
 114
 115   while (*ptr != entry)
 116     ptr = &(*ptr)->next;
 117   *ptr = entry->next;
 118   free (entry);
 119 }
 120
 121 /* Call all node insertion hooks.  */
 122 void
 123 symbol_table::call_varpool_insertion_hooks (varpool_node *node)
 124 {
 125   varpool_node_hook_list *entry = m_first_varpool_insertion_hook;
 126   while (entry)
 127   {
 128     entry->hook (node, entry->data);
 129     entry = entry->next;
 130   }
 131 }
 132
 133 /* Allocate new callgraph node and insert it into basic data structures.  */
 134
 135 varpool_node *
 136 varpool_node::create_empty (void)
 137 {
 138   return new (ggc_alloc<varpool_node> ()) varpool_node ();
 139 }
 140
 141 /* Return varpool node assigned to DECL.  Create new one when needed.  */
 142 varpool_node *
 143 varpool_node::get_create (tree decl)
 144 {
 145   varpool_node *node = varpool_node::get (decl);
 146   gcc_checking_assert (VAR_P (decl));
 147   if (node)
 148     return node;
 149
 150   node = varpool_node::create_empty ();
 151   node->decl = decl;
 152
 153   if ((flag_openacc || flag_openmp)
 154       && lookup_attribute ("omp declare target", DECL_ATTRIBUTES (decl)))
 155     {
 156       node->offloadable = 1;
 157       if (ENABLE_OFFLOADING && !DECL_EXTERNAL (decl))
 158         {
 159           g->have_offload = true;
 160           if (!in_lto_p)
 161             vec_safe_push (offload_vars, decl);
 162         }
 163     }
 164
 165   node->register_symbol ();
 166   return node;
 167 }
 168
 169 /* Remove variable from symbol table.  */
 170
 171 void
 172 varpool_node::remove (void)
 173 {
 174   symtab->call_varpool_removal_hooks (this);
 175   if (lto_file_data)
 176     {
 177       lto_free_function_in_decl_state_for_node (this);
 178       lto_file_data = NULL;
 179     }
 180
 181   /* When streaming we can have multiple nodes associated with decl.  */
 182   if (symtab->state == LTO_STREAMING)
 183     ;
 184   /* Keep constructor when it may be used for folding. We remove
 185      references to external variables before final compilation.  */
 186   else if (DECL_INITIAL (decl) && DECL_INITIAL (decl) != error_mark_node
 187            && !ctor_useable_for_folding_p ())
 188     remove_initializer ();
 189
 190   unregister (NULL);
 191   ggc_free (this);
 192 }
 193
 194 /* Remove node initializer when it is no longer needed.  */
 195 void
 196 varpool_node::remove_initializer (void)
 197 {
 198   if (DECL_INITIAL (decl)
 199       && !DECL_IN_CONSTANT_POOL (decl)
 200       /* Keep vtables for BINFO folding.  */
 201       && !DECL_VIRTUAL_P (decl)
 202       /* FIXME: http://gcc.gnu.org/PR55395 */
 203       && debug_info_level == DINFO_LEVEL_NONE
 204       /* When doing declaration merging we have duplicate
 205          entries for given decl.  Do not attempt to remove
 206          the bodies, or we will end up removing
 207          wrong one.  */
 208       && symtab->state != LTO_STREAMING)
 209     DECL_INITIAL (decl) = error_mark_node;
 210 }
 211
 212 /* Dump given varpool node to F.  */
 213 void
 214 varpool_node::dump (FILE *f)
 215 {
 216   dump_base (f);
 217   fprintf (f, "  Availability: %s\n",
 218            symtab->function_flags_ready
 219            ? cgraph_availability_names[get_availability ()]
 220            : "not-ready");
 221   fprintf (f, "  Varpool flags:");
 222   if (DECL_INITIAL (decl))
 223     fprintf (f, " initialized");
 224   if (output)
 225     fprintf (f, " output");
 226   if (used_by_single_function)
 227     fprintf (f, " used-by-single-function");
 228   if (TREE_READONLY (decl))
 229     fprintf (f, " read-only");
 230   if (ctor_useable_for_folding_p ())
 231     fprintf (f, " const-value-known");
 232   if (writeonly)
 233     fprintf (f, " write-only");
 234   if (tls_model)
 235     fprintf (f, " tls-%s", tls_model_names [tls_model]);
 236   fprintf (f, "\n");
 237 }
 238
 239
 240 /* Dump given varpool node to stderr.  */
 241 void varpool_node::debug (void)
 242 {
 243   varpool_node::dump (stderr);
 244 }
 245
 246 /* Dump the variable pool to F.  */
 247 void
 248 varpool_node::dump_varpool (FILE *f)
 249 {
 250   varpool_node *node;
 251
 252   fprintf (f, "variable pool:\n\n");
 253   FOR_EACH_VARIABLE (node)
 254     node->dump (f);
 255 }
 256
 257 /* Dump the variable pool to stderr.  */
 258
 259 DEBUG_FUNCTION void
 260 varpool_node::debug_varpool (void)
 261 {
 262   dump_varpool (stderr);
 263 }
 264
 265 /* Given an assembler name, lookup node.  */
 266 varpool_node *
 267 varpool_node::get_for_asmname (tree asmname)
 268 {
 269   if (symtab_node *node = symtab_node::get_for_asmname (asmname))
 270     return dyn_cast <varpool_node *> (node);
 271   else
 272     return NULL;
 273 }
 274
 275 /* When doing LTO, read variable's constructor from disk if
 276    it is not already present.  */
 277
 278 tree
 279 varpool_node::get_constructor (void)
 280 {
 281   lto_file_decl_data *file_data;
 282   const char *data, *name;
 283   size_t len;
 284
 285   if (DECL_INITIAL (decl) != error_mark_node
 286       || !in_lto_p
 287       || !lto_file_data)
 288     return DECL_INITIAL (decl);
 289
 290   timevar_push (TV_IPA_LTO_CTORS_IN);
 291
 292   file_data = lto_file_data;
 293   name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 294
 295   /* We may have renamed the declaration, e.g., a static function.  */
 296   name = lto_get_decl_name_mapping (file_data, name);
 297   struct lto_in_decl_state *decl_state
 298          = lto_get_function_in_decl_state (file_data, decl);
 299
 300   data = lto_get_section_data (file_data, LTO_section_function_body,
 301                                name, order - file_data->order_base,
 302                                &len, decl_state->compressed);
 303   if (!data)
 304     fatal_error (input_location, "%s: section %s.%d is missing",
 305                  file_data->file_name,
 306                  name, order - file_data->order_base);
 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   /* An alias of a read-only variable is also read-only, since the variable
 357      is stored in read-only memory.  We also accept read-only aliases of
 358      non-read-only locations assuming that the user knows what he is asking
 359      for.  */
 360   if (!TREE_READONLY (decl) && !TREE_READONLY (real_node->decl))
 361     return false;
 362
 363   /* Variables declared 'const' without an initializer
 364      have zero as the initializer if they may not be
 365      overridden at link or run time.
 366
 367      It is actually requirement for C++ compiler to optimize const variables
 368      consistently. As a GNU extension, do not enforce this rule for user defined
 369      weak variables, so we support interposition on:
 370      static const int dummy = 0;
 371      extern const int foo __attribute__((__weak__, __alias__("dummy")));
 372    */
 373   if ((!DECL_INITIAL (real_node->decl)
 374        || (DECL_WEAK (decl) && !DECL_COMDAT (decl)))
 375       && ((DECL_EXTERNAL (decl) && !in_other_partition)
 376           || decl_replaceable_p (decl, semantic_interposition)))
 377     return false;
 378
 379   /* Variables declared `const' with an initializer are considered
 380      to not be overwritable with different initializer by default.
 381
 382      ??? Previously we behaved so for scalar variables but not for array
 383      accesses.  */
 384   return true;
 385 }
 386
 387 /* If DECLARATION is constant variable and its initial value is known
 388    (so we can do constant folding), return its constructor (DECL_INITIAL).
 389    This may be an expression or NULL when DECL is initialized to 0.
 390    Return ERROR_MARK_NODE otherwise.
 391
 392    In LTO this may actually trigger reading the constructor from disk.
 393    For this reason varpool_ctor_useable_for_folding_p should be used when
 394    the actual constructor value is not needed.  */
 395
 396 tree
 397 ctor_for_folding (tree decl)
 398 {
 399   varpool_node *node, *real_node;
 400   tree real_decl;
 401
 402   if (!VAR_P (decl) && TREE_CODE (decl) != CONST_DECL)
 403     return error_mark_node;
 404
 405   if (TREE_CODE (decl) == CONST_DECL
 406       || DECL_IN_CONSTANT_POOL (decl))
 407     return DECL_INITIAL (decl);
 408
 409   if (TREE_THIS_VOLATILE (decl))
 410     return error_mark_node;
 411
 412   /* Do not care about automatic variables.  Those are never initialized
 413      anyway, because gimplifier expands the code.  */
 414   if (!TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
 415     {
 416       gcc_assert (!TREE_PUBLIC (decl));
 417       /* Unless this is called during FE folding.  */
 418       if (cfun
 419           && (cfun->curr_properties & (PROP_gimple | PROP_rtl)) == 0
 420           && TREE_READONLY (decl)
 421           && !TREE_SIDE_EFFECTS (decl)
 422           && DECL_INITIAL (decl))
 423         return DECL_INITIAL (decl);
 424       return error_mark_node;
 425     }
 426
 427   gcc_assert (VAR_P (decl));
 428
 429   real_node = node = varpool_node::get (decl);
 430   if (node)
 431     {
 432       real_node = node->ultimate_alias_target ();
 433       real_decl = real_node->decl;
 434     }
 435   else
 436     real_decl = decl;
 437
 438   /* See if we are dealing with alias.
 439      In most cases alias is just alternative symbol pointing to a given
 440      constructor.  This allows us to use interposition rules of DECL
 441      constructor of REAL_NODE.  However weakrefs are special by being just
 442      alternative name of their target (if defined).  */
 443   if (decl != real_decl)
 444     {
 445       gcc_assert (!DECL_INITIAL (decl)
 446                   || (node->alias && node->get_alias_target () == real_node)
 447                   || DECL_INITIAL (decl) == error_mark_node);
 448       while (node->transparent_alias && node->analyzed)
 449         {
 450           node = node->get_alias_target ();
 451           decl = node->decl;
 452         }
 453     }
 454
 455   if ((!DECL_VIRTUAL_P (real_decl)
 456        || DECL_INITIAL (real_decl) == error_mark_node
 457        || !DECL_INITIAL (real_decl))
 458       && (!node || !node->ctor_useable_for_folding_p ()))
 459     return error_mark_node;
 460
 461   /* OK, we can return constructor.  See if we need to fetch it from disk
 462      in LTO mode.  */
 463   if (DECL_INITIAL (real_decl) != error_mark_node
 464       || !in_lto_p)
 465     return DECL_INITIAL (real_decl);
 466   return real_node->get_constructor ();
 467 }
 468
 469 /* Add the variable DECL to the varpool.
 470    Unlike finalize_decl function is intended to be used
 471    by middle end and allows insertion of new variable at arbitrary point
 472    of compilation.  */
 473 void
 474 varpool_node::add (tree decl)
 475 {
 476   varpool_node *node;
 477   varpool_node::finalize_decl (decl);
 478   node = varpool_node::get_create (decl);
 479   symtab->call_varpool_insertion_hooks (node);
 480   if (node->externally_visible_p ())
 481     node->externally_visible = true;
 482   if (lookup_attribute ("no_reorder", DECL_ATTRIBUTES (decl)))
 483     node->no_reorder = 1;
 484 }
 485
 486 /* Return variable availability.  See cgraph.h for description of individual
 487    return values.  */
 488 enum availability
 489 varpool_node::get_availability (symtab_node *ref)
 490 {
 491   if (!definition && !in_other_partition)
 492     return AVAIL_NOT_AVAILABLE;
 493   if (!TREE_PUBLIC (decl))
 494     return AVAIL_AVAILABLE;
 495   if (DECL_IN_CONSTANT_POOL (decl)
 496       || DECL_VIRTUAL_P (decl))
 497     return AVAIL_AVAILABLE;
 498   if (transparent_alias && definition)
 499     {
 500       enum availability avail;
 501
 502       ultimate_alias_target (&avail, ref);
 503       return avail;
 504     }
 505   /* If this is a reference from symbol itself and there are no aliases, we
 506      may be sure that the symbol was not interposed by something else because
 507      the symbol itself would be unreachable otherwise.  */
 508   if ((this == ref && !has_aliases_p ())
 509       || (ref && get_comdat_group ()
 510           && get_comdat_group () == ref->get_comdat_group ()))
 511     return AVAIL_AVAILABLE;
 512   /* If the variable can be overwritten, return OVERWRITABLE.  Takes
 513      care of at least one notable extension - the COMDAT variables
 514      used to share template instantiations in C++.  */
 515   if (decl_replaceable_p (decl, semantic_interposition)
 516       || (DECL_EXTERNAL (decl) && !in_other_partition))
 517     return AVAIL_INTERPOSABLE;
 518   return AVAIL_AVAILABLE;
 519 }
 520
 521 void
 522 varpool_node::analyze (void)
 523 {
 524   /* When reading back varpool at LTO time, we re-construct the queue in order
 525      to have "needed" list right by inserting all needed nodes into varpool.
 526      We however don't want to re-analyze already analyzed nodes.  */
 527   if (!analyzed)
 528     {
 529       gcc_assert (!in_lto_p || symtab->function_flags_ready);
 530       /* Compute the alignment early so function body expanders are
 531          already informed about increased alignment.  */
 532       align_variable (decl, 0);
 533     }
 534   if (alias)
 535     resolve_alias (varpool_node::get (alias_target));
 536   else if (DECL_INITIAL (decl))
 537     record_references_in_initializer (decl, analyzed);
 538   analyzed = true;
 539 }
 540
 541 /* Assemble thunks and aliases associated to varpool node.  */
 542
 543 void
 544 varpool_node::assemble_aliases (void)
 545 {
 546   ipa_ref *ref;
 547
 548   FOR_EACH_ALIAS (this, ref)
 549     {
 550       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 551       if (alias->symver)
 552         do_assemble_symver (alias->decl,
 553                             DECL_ASSEMBLER_NAME (decl));
 554       else if (!alias->transparent_alias)
 555         do_assemble_alias (alias->decl,
 556                            DECL_ASSEMBLER_NAME (decl));
 557       alias->assemble_aliases ();
 558     }
 559 }
 560
 561 /* Output one variable, if necessary.  Return whether we output it.  */
 562
 563 bool
 564 varpool_node::assemble_decl (void)
 565 {
 566   /* Aliases are output when their target is produced or by
 567      output_weakrefs.  */
 568   if (alias)
 569     return false;
 570
 571   /* Constant pool is output from RTL land when the reference
 572      survive till this level.  */
 573   if (DECL_IN_CONSTANT_POOL (decl) && TREE_ASM_WRITTEN (decl))
 574     return false;
 575
 576   /* Decls with VALUE_EXPR should not be in the varpool at all.  They
 577      are not real variables, but just info for debugging and codegen.
 578      Unfortunately at the moment emutls is not updating varpool correctly
 579      after turning real vars into value_expr vars.  */
 580   if (DECL_HAS_VALUE_EXPR_P (decl)
 581       && !targetm.have_tls)
 582     return false;
 583
 584   /* Hard register vars do not need to be output.  */
 585   if (DECL_HARD_REGISTER (decl))
 586     return false;
 587
 588   gcc_checking_assert (!TREE_ASM_WRITTEN (decl)
 589                        && VAR_P (decl)
 590                        && !DECL_HAS_VALUE_EXPR_P (decl));
 591
 592   if (!in_other_partition
 593       && !DECL_EXTERNAL (decl))
 594     {
 595       get_constructor ();
 596       assemble_variable (decl, 0, 1, 0);
 597       gcc_assert (TREE_ASM_WRITTEN (decl));
 598       gcc_assert (definition);
 599       assemble_aliases ();
 600       /* After the parser has generated debugging information, augment
 601          this information with any new location/etc information that may
 602          have become available after the compilation proper.  */
 603       debug_hooks->late_global_decl (decl);
 604       return true;
 605     }
 606
 607   return false;
 608 }
 609
 610 /* Add NODE to queue starting at FIRST.
 611    The queue is linked via AUX pointers and terminated by pointer to 1.  */
 612
 613 static void
 614 enqueue_node (varpool_node *node, varpool_node **first)
 615 {
 616   if (node->aux)
 617     return;
 618   gcc_checking_assert (*first);
 619   node->aux = *first;
 620   *first = node;
 621 }
 622
 623 /* Optimization of function bodies might've rendered some variables as
 624    unnecessary so we want to avoid these from being compiled.  Re-do
 625    reachability starting from variables that are either externally visible
 626    or was referred from the asm output routines.  */
 627
 628 void
 629 symbol_table::remove_unreferenced_decls (void)
 630 {
 631   varpool_node *next, *node;
 632   varpool_node *first = (varpool_node *)(void *)1;
 633   int i;
 634   ipa_ref *ref = NULL;
 635   hash_set<varpool_node *> referenced;
 636
 637   if (seen_error ())
 638     return;
 639
 640   if (dump_file)
 641     fprintf (dump_file, "Trivially needed variables:");
 642   FOR_EACH_DEFINED_VARIABLE (node)
 643     {
 644       if (node->analyzed
 645           && (!node->can_remove_if_no_refs_p ()
 646               /* We just expanded all function bodies.  See if any of
 647                  them needed the variable.  */
 648               || DECL_RTL_SET_P (node->decl)))
 649         {
 650           enqueue_node (node, &first);
 651           if (dump_file)
 652             fprintf (dump_file, " %s", node->dump_asm_name ());
 653         }
 654     }
 655   while (first != (varpool_node *)(void *)1)
 656     {
 657       node = first;
 658       first = (varpool_node *)first->aux;
 659
 660       if (node->same_comdat_group)
 661         {
 662           symtab_node *next;
 663           for (next = node->same_comdat_group;
 664                next != node;
 665                next = next->same_comdat_group)
 666             {
 667               varpool_node *vnext = dyn_cast <varpool_node *> (next);
 668               if (vnext && vnext->analyzed && !next->comdat_local_p ())
 669                 enqueue_node (vnext, &first);
 670             }
 671         }
 672       for (i = 0; node->iterate_reference (i, ref); i++)
 673         {
 674           varpool_node *vnode = dyn_cast <varpool_node *> (ref->referred);
 675           if (vnode
 676               && !vnode->in_other_partition
 677               && (!DECL_EXTERNAL (ref->referred->decl)
 678                   || vnode->alias)
 679               && vnode->analyzed)
 680             enqueue_node (vnode, &first);
 681           else
 682             {
 683               referenced.add (vnode);
 684               while (vnode && vnode->alias && vnode->definition)
 685                 {
 686                   vnode = vnode->get_alias_target ();
 687                   referenced.add (vnode);
 688                 }
 689             }
 690         }
 691     }
 692   if (dump_file)
 693     fprintf (dump_file, "\nRemoving variables:");
 694   for (node = first_defined_variable (); node; node = next)
 695     {
 696       next = next_defined_variable (node);
 697       if (!node->aux && !node->no_reorder)
 698         {
 699           if (dump_file)
 700             fprintf (dump_file, " %s", node->dump_asm_name ());
 701           if (referenced.contains(node))
 702             node->remove_initializer ();
 703           else
 704             node->remove ();
 705         }
 706     }
 707
 708   if (dump_file)
 709     fprintf (dump_file, "\n");
 710 }
 711
 712 /* For variables in named sections make sure get_variable_section
 713    is called before we switch to those sections.  Then section
 714    conflicts between read-only and read-only requiring relocations
 715    sections can be resolved.  */
 716 void
 717 varpool_node::finalize_named_section_flags (void)
 718 {
 719   if (!TREE_ASM_WRITTEN (decl)
 720       && !alias
 721       && !in_other_partition
 722       && !DECL_EXTERNAL (decl)
 723       && VAR_P (decl)
 724       && !DECL_HAS_VALUE_EXPR_P (decl)
 725       && get_section ())
 726     get_variable_section (decl, false);
 727 }
 728
 729 /* Output all variables enqueued to be assembled.  */
 730 bool
 731 symbol_table::output_variables (void)
 732 {
 733   bool changed = false;
 734   varpool_node *node;
 735
 736   if (seen_error ())
 737     return false;
 738
 739   remove_unreferenced_decls ();
 740
 741   timevar_push (TV_VAROUT);
 742
 743   FOR_EACH_DEFINED_VARIABLE (node)
 744     {
 745       /* Handled in output_in_order.  */
 746       if (node->no_reorder)
 747         continue;
 748
 749       node->finalize_named_section_flags ();
 750     }
 751
 752   /* There is a similar loop in output_in_order.  Please keep them in sync.  */
 753   FOR_EACH_VARIABLE (node)
 754     {
 755       /* Handled in output_in_order.  */
 756       if (node->no_reorder)
 757         continue;
 758       if (DECL_HARD_REGISTER (node->decl)
 759           || DECL_HAS_VALUE_EXPR_P (node->decl))
 760         continue;
 761       if (node->definition)
 762         changed |= node->assemble_decl ();
 763       else
 764         assemble_undefined_decl (node->decl);
 765     }
 766   timevar_pop (TV_VAROUT);
 767   return changed;
 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 (VAR_P (decl));
 779   gcc_assert (VAR_P (alias));
 780   alias_node = varpool_node::get_create (alias);
 781   alias_node->alias = true;
 782   alias_node->definition = true;
 783   alias_node->semantic_interposition = flag_semantic_interposition;
 784   alias_node->alias_target = decl;
 785   if (lookup_attribute ("weakref", DECL_ATTRIBUTES (alias)) != NULL)
 786     alias_node->weakref = alias_node->transparent_alias = true;
 787   return alias_node;
 788 }
 789
 790 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 791    Extra name aliases are output whenever DECL is output.  */
 792
 793 varpool_node *
 794 varpool_node::create_extra_name_alias (tree alias, tree decl)
 795 {
 796   varpool_node *alias_node;
 797
 798   /* If aliases aren't supported by the assembler, fail.  */
 799   if (!TARGET_SUPPORTS_ALIASES)
 800     return NULL;
 801
 802   alias_node = varpool_node::create_alias (alias, decl);
 803   alias_node->cpp_implicit_alias = true;
 804
 805   /* Extra name alias mechanism creates aliases really late
 806      via DECL_ASSEMBLER_NAME mechanism.
 807      This is unfortunate because they are not going through the
 808      standard channels.  Ensure they get output.  */
 809   if (symtab->cpp_implicit_aliases_done)
 810     alias_node->resolve_alias (varpool_node::get_create (decl));
 811   return alias_node;
 812 }
 813
 814 /* Worker for call_for_symbol_and_aliases.  */
 815
 816 bool
 817 varpool_node::call_for_symbol_and_aliases_1 (bool (*callback) (varpool_node *,
 818                                                                void *),
 819                                              void *data,
 820                                              bool include_overwritable)
 821 {
 822   ipa_ref *ref;
 823
 824   FOR_EACH_ALIAS (this, ref)
 825     {
 826       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 827       if (include_overwritable
 828           || alias->get_availability () > AVAIL_INTERPOSABLE)
 829         if (alias->call_for_symbol_and_aliases (callback, data,
 830                                                 include_overwritable))
 831           return true;
 832     }
 833   return false;
 834 }