gcc/varpool.c

   1 /* Callgraph handling code.
   2    Copyright (C) 2003-2015 Free Software Foundation, Inc.
   3    Contributed by Jan Hubicka
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it under
   8 the terms of the GNU General Public License as published by the Free
   9 Software Foundation; either version 3, or (at your option) any later
  10 version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "tm.h"
  25 #include "hash-set.h"
  26 #include "machmode.h"
  27 #include "vec.h"
  28 #include "double-int.h"
  29 #include "input.h"
  30 #include "alias.h"
  31 #include "symtab.h"
  32 #include "wide-int.h"
  33 #include "inchash.h"
  34 #include "tree.h"
  35 #include "fold-const.h"
  36 #include "varasm.h"
  37 #include "predict.h"
  38 #include "basic-block.h"
  39 #include "hash-map.h"
  40 #include "is-a.h"
  41 #include "plugin-api.h"
  42 #include "hard-reg-set.h"
  43 #include "input.h"
  44 #include "function.h"
  45 #include "ipa-ref.h"
  46 #include "cgraph.h"
  47 #include "langhooks.h"
  48 #include "diagnostic-core.h"
  49 #include "timevar.h"
  50 #include "debug.h"
  51 #include "target.h"
  52 #include "output.h"
  53 #include "gimple-expr.h"
  54 #include "flags.h"
  55 #include "tree-ssa-alias.h"
  56 #include "gimple.h"
  57 #include "lto-streamer.h"
  58 #include "context.h"
  59 #include "omp-low.h"
  60
  61 const char * const tls_model_names[]={"none", "emulated",
  62                                       "global-dynamic", "local-dynamic",
  63                                       "initial-exec", "local-exec"};
  64
  65 /* List of hooks triggered on varpool_node events.  */
  66 struct varpool_node_hook_list {
  67   varpool_node_hook hook;
  68   void *data;
  69   struct varpool_node_hook_list *next;
  70 };
  71
  72 /* Register HOOK to be called with DATA on each removed node.  */
  73 varpool_node_hook_list *
  74 symbol_table::add_varpool_removal_hook (varpool_node_hook hook, void *data)
  75 {
  76   varpool_node_hook_list *entry;
  77   varpool_node_hook_list **ptr = &m_first_varpool_removal_hook;
  78
  79   entry = (varpool_node_hook_list *) xmalloc (sizeof (*entry));
  80   entry->hook = hook;
  81   entry->data = data;
  82   entry->next = NULL;
  83   while (*ptr)
  84     ptr = &(*ptr)->next;
  85   *ptr = entry;
  86   return entry;
  87 }
  88
  89 /* Remove ENTRY from the list of hooks called on removing nodes.  */
  90 void
  91 symbol_table::remove_varpool_removal_hook (varpool_node_hook_list *entry)
  92 {
  93   varpool_node_hook_list **ptr = &m_first_varpool_removal_hook;
  94
  95   while (*ptr != entry)
  96     ptr = &(*ptr)->next;
  97   *ptr = entry->next;
  98   free (entry);
  99 }
 100
 101 /* Call all node removal hooks.  */
 102 void
 103 symbol_table::call_varpool_removal_hooks (varpool_node *node)
 104 {
 105   varpool_node_hook_list *entry = m_first_varpool_removal_hook;
 106   while (entry)
 107   {
 108     entry->hook (node, entry->data);
 109     entry = entry->next;
 110   }
 111 }
 112
 113 /* Register HOOK to be called with DATA on each inserted node.  */
 114 varpool_node_hook_list *
 115 symbol_table::add_varpool_insertion_hook (varpool_node_hook hook, void *data)
 116 {
 117   varpool_node_hook_list *entry;
 118   varpool_node_hook_list **ptr = &m_first_varpool_insertion_hook;
 119
 120   entry = (varpool_node_hook_list *) xmalloc (sizeof (*entry));
 121   entry->hook = hook;
 122   entry->data = data;
 123   entry->next = NULL;
 124   while (*ptr)
 125     ptr = &(*ptr)->next;
 126   *ptr = entry;
 127   return entry;
 128 }
 129
 130 /* Remove ENTRY from the list of hooks called on inserted nodes.  */
 131 void
 132 symbol_table::remove_varpool_insertion_hook (varpool_node_hook_list *entry)
 133 {
 134   varpool_node_hook_list **ptr = &m_first_varpool_insertion_hook;
 135
 136   while (*ptr != entry)
 137     ptr = &(*ptr)->next;
 138   *ptr = entry->next;
 139   free (entry);
 140 }
 141
 142 /* Call all node insertion hooks.  */
 143 void
 144 symbol_table::call_varpool_insertion_hooks (varpool_node *node)
 145 {
 146   varpool_node_hook_list *entry = m_first_varpool_insertion_hook;
 147   while (entry)
 148   {
 149     entry->hook (node, entry->data);
 150     entry = entry->next;
 151   }
 152 }
 153
 154 /* Allocate new callgraph node and insert it into basic data structures.  */
 155
 156 varpool_node *
 157 varpool_node::create_empty (void)
 158 {
 159   varpool_node *node = ggc_cleared_alloc<varpool_node> ();
 160   node->type = SYMTAB_VARIABLE;
 161   return node;
 162 }
 163
 164 /* Return varpool node assigned to DECL.  Create new one when needed.  */
 165 varpool_node *
 166 varpool_node::get_create (tree decl)
 167 {
 168   varpool_node *node = varpool_node::get (decl);
 169   gcc_checking_assert (TREE_CODE (decl) == VAR_DECL);
 170   if (node)
 171     return node;
 172
 173   node = varpool_node::create_empty ();
 174   node->decl = decl;
 175
 176   if ((flag_openacc || flag_openmp) && !DECL_EXTERNAL (decl)
 177       && lookup_attribute ("omp declare target", DECL_ATTRIBUTES (decl)))
 178     {
 179       node->offloadable = 1;
 180 #ifdef ENABLE_OFFLOADING
 181       g->have_offload = true;
 182       if (!in_lto_p)
 183         vec_safe_push (offload_vars, decl);
 184       node->force_output = 1;
 185 #endif
 186     }
 187
 188   node->register_symbol ();
 189   return node;
 190 }
 191
 192 /* Remove variable from symbol table.  */
 193
 194 void
 195 varpool_node::remove (void)
 196 {
 197   symtab->call_varpool_removal_hooks (this);
 198   if (lto_file_data)
 199     {
 200       lto_free_function_in_decl_state_for_node (this);
 201       lto_file_data = NULL;
 202     }
 203
 204   /* When streaming we can have multiple nodes associated with decl.  */
 205   if (symtab->state == LTO_STREAMING)
 206     ;
 207   /* Keep constructor when it may be used for folding. We remove
 208      references to external variables before final compilation.  */
 209   else if (DECL_INITIAL (decl) && DECL_INITIAL (decl) != error_mark_node
 210            && !ctor_useable_for_folding_p ())
 211     remove_initializer ();
 212
 213   unregister ();
 214   ggc_free (this);
 215 }
 216
 217 /* Remove node initializer when it is no longer needed.  */
 218 void
 219 varpool_node::remove_initializer (void)
 220 {
 221   if (DECL_INITIAL (decl)
 222       && !DECL_IN_CONSTANT_POOL (decl)
 223       /* Keep vtables for BINFO folding.  */
 224       && !DECL_VIRTUAL_P (decl)
 225       /* FIXME: http://gcc.gnu.org/PR55395 */
 226       && debug_info_level == DINFO_LEVEL_NONE
 227       /* When doing declaration merging we have duplicate
 228          entries for given decl.  Do not attempt to remove
 229          the boides, or we will end up remiving
 230          wrong one.  */
 231       && symtab->state != LTO_STREAMING)
 232     DECL_INITIAL (decl) = error_mark_node;
 233 }
 234
 235 /* Dump given varpool node to F.  */
 236 void
 237 varpool_node::dump (FILE *f)
 238 {
 239   dump_base (f);
 240   fprintf (f, "  Availability: %s\n",
 241            symtab->function_flags_ready
 242            ? cgraph_availability_names[get_availability ()]
 243            : "not-ready");
 244   fprintf (f, "  Varpool flags:");
 245   if (DECL_INITIAL (decl))
 246     fprintf (f, " initialized");
 247   if (output)
 248     fprintf (f, " output");
 249   if (used_by_single_function)
 250     fprintf (f, " used-by-single-function");
 251   if (need_bounds_init)
 252     fprintf (f, " need-bounds-init");
 253   if (TREE_READONLY (decl))
 254     fprintf (f, " read-only");
 255   if (ctor_useable_for_folding_p ())
 256     fprintf (f, " const-value-known");
 257   if (writeonly)
 258     fprintf (f, " write-only");
 259   if (tls_model)
 260     fprintf (f, " tls-%s", tls_model_names [tls_model]);
 261   fprintf (f, "\n");
 262 }
 263
 264
 265 /* Dump given varpool node to stderr.  */
 266 void varpool_node::debug (void)
 267 {
 268   varpool_node::dump (stderr);
 269 }
 270
 271 /* Dump the variable pool to F.  */
 272 void
 273 varpool_node::dump_varpool (FILE *f)
 274 {
 275   varpool_node *node;
 276
 277   fprintf (f, "variable pool:\n\n");
 278   FOR_EACH_VARIABLE (node)
 279     node->dump (f);
 280 }
 281
 282 /* Dump the variable pool to stderr.  */
 283
 284 DEBUG_FUNCTION void
 285 varpool_node::debug_varpool (void)
 286 {
 287   dump_varpool (stderr);
 288 }
 289
 290 /* Given an assembler name, lookup node.  */
 291 varpool_node *
 292 varpool_node::get_for_asmname (tree asmname)
 293 {
 294   if (symtab_node *node = symtab_node::get_for_asmname (asmname))
 295     return dyn_cast <varpool_node *> (node);
 296   else
 297     return NULL;
 298 }
 299
 300 /* When doing LTO, read variable's constructor from disk if
 301    it is not already present.  */
 302
 303 tree
 304 varpool_node::get_constructor (void)
 305 {
 306   lto_file_decl_data *file_data;
 307   const char *data, *name;
 308   size_t len;
 309
 310   if (DECL_INITIAL (decl) != error_mark_node
 311       || !in_lto_p
 312       || !lto_file_data)
 313     return DECL_INITIAL (decl);
 314
 315   timevar_push (TV_IPA_LTO_CTORS_IN);
 316
 317   file_data = lto_file_data;
 318   name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 319
 320   /* We may have renamed the declaration, e.g., a static function.  */
 321   name = lto_get_decl_name_mapping (file_data, name);
 322
 323   data = lto_get_section_data (file_data, LTO_section_function_body,
 324                                name, &len);
 325   if (!data)
 326     fatal_error (input_location, "%s: section %s is missing",
 327                  file_data->file_name,
 328                  name);
 329
 330   lto_input_variable_constructor (file_data, this, data);
 331   gcc_assert (DECL_INITIAL (decl) != error_mark_node);
 332   lto_stats.num_function_bodies++;
 333   lto_free_section_data (file_data, LTO_section_function_body, name,
 334                          data, len);
 335   lto_free_function_in_decl_state_for_node (this);
 336   timevar_pop (TV_IPA_LTO_CTORS_IN);
 337   return DECL_INITIAL (decl);
 338 }
 339
 340 /* Return true if variable has constructor that can be used for folding.  */
 341
 342 bool
 343 varpool_node::ctor_useable_for_folding_p (void)
 344 {
 345   varpool_node *real_node = this;
 346
 347   if (real_node->alias && real_node->definition)
 348     real_node = ultimate_alias_target ();
 349
 350   if (TREE_CODE (decl) == CONST_DECL
 351       || DECL_IN_CONSTANT_POOL (decl))
 352     return true;
 353   if (TREE_THIS_VOLATILE (decl))
 354     return false;
 355
 356   /* If we do not have a constructor, we can't use it.  */
 357   if (DECL_INITIAL (real_node->decl) == error_mark_node
 358       && !real_node->lto_file_data)
 359     return false;
 360
 361   /* Avoid attempts to load constructors that was not streamed.  */
 362   if (flag_ltrans && DECL_INITIAL (real_node->decl) == error_mark_node
 363       && real_node->body_removed)
 364     return false;
 365
 366   /* Vtables are defined by their types and must match no matter of interposition
 367      rules.  */
 368   if (DECL_VIRTUAL_P (decl))
 369     {
 370       /* The C++ front end creates VAR_DECLs for vtables of typeinfo
 371          classes not defined in the current TU so that it can refer
 372          to them from typeinfo objects.  Avoid returning NULL_TREE.  */
 373       return DECL_INITIAL (real_node->decl) != NULL;
 374     }
 375
 376   /* Alias of readonly variable is also readonly, since the variable is stored
 377      in readonly memory.  We also accept readonly aliases of non-readonly
 378      locations assuming that user knows what he is asking for.  */
 379   if (!TREE_READONLY (decl) && !TREE_READONLY (real_node->decl))
 380     return false;
 381
 382   /* Variables declared 'const' without an initializer
 383      have zero as the initializer if they may not be
 384      overridden at link or run time.
 385
 386      It is actually requirement for C++ compiler to optimize const variables
 387      consistently. As a GNU extension, do not enfore this rule for user defined
 388      weak variables, so we support interposition on:
 389      static const int dummy = 0;
 390      extern const int foo __attribute__((__weak__, __alias__("dummy")));
 391    */
 392   if ((!DECL_INITIAL (real_node->decl)
 393        || (DECL_WEAK (decl) && !DECL_COMDAT (decl)))
 394       && (DECL_EXTERNAL (decl) || decl_replaceable_p (decl)))
 395     return false;
 396
 397   /* Variables declared `const' with an initializer are considered
 398      to not be overwritable with different initializer by default.
 399
 400      ??? Previously we behaved so for scalar variables but not for array
 401      accesses.  */
 402   return true;
 403 }
 404
 405 /* If DECLARATION is constant variable and its initial value is known
 406    (so we can do constant folding), return its constructor (DECL_INITIAL).
 407    This may be an expression or NULL when DECL is initialized to 0.
 408    Return ERROR_MARK_NODE otherwise.
 409
 410    In LTO this may actually trigger reading the constructor from disk.
 411    For this reason varpool_ctor_useable_for_folding_p should be used when
 412    the actual constructor value is not needed.  */
 413
 414 tree
 415 ctor_for_folding (tree decl)
 416 {
 417   varpool_node *node, *real_node;
 418   tree real_decl;
 419
 420   if (TREE_CODE (decl) != VAR_DECL
 421       && TREE_CODE (decl) != CONST_DECL)
 422     return error_mark_node;
 423
 424   /* Static constant bounds are created to be
 425      used instead of constants and therefore
 426      do not let folding it.  */
 427   if (POINTER_BOUNDS_P (decl))
 428     return error_mark_node;
 429
 430   if (TREE_CODE (decl) == CONST_DECL
 431       || DECL_IN_CONSTANT_POOL (decl))
 432     return DECL_INITIAL (decl);
 433
 434   if (TREE_THIS_VOLATILE (decl))
 435     return error_mark_node;
 436
 437   /* Do not care about automatic variables.  Those are never initialized
 438      anyway, because gimplifier exapnds the code.  */
 439   if (!TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
 440     {
 441       gcc_assert (!TREE_PUBLIC (decl));
 442       return error_mark_node;
 443     }
 444
 445   gcc_assert (TREE_CODE (decl) == VAR_DECL);
 446
 447   real_node = node = varpool_node::get (decl);
 448   if (node)
 449     {
 450       real_node = node->ultimate_alias_target ();
 451       real_decl = real_node->decl;
 452     }
 453   else
 454     real_decl = decl;
 455
 456   /* See if we are dealing with alias.
 457      In most cases alias is just alternative symbol pointing to a given
 458      constructor.  This allows us to use interposition rules of DECL
 459      constructor of REAL_NODE.  However weakrefs are special by being just
 460      alternative name of their target (if defined).  */
 461   if (decl != real_decl)
 462     {
 463       gcc_assert (!DECL_INITIAL (decl)
 464                   || (node->alias && node->get_alias_target () == real_node)
 465                   || DECL_INITIAL (decl) == error_mark_node);
 466       if (node->weakref)
 467         {
 468           node = node->get_alias_target ();
 469           decl = node->decl;
 470         }
 471     }
 472
 473   if ((!DECL_VIRTUAL_P (real_decl)
 474        || DECL_INITIAL (real_decl) == error_mark_node
 475        || !DECL_INITIAL (real_decl))
 476       && (!node || !node->ctor_useable_for_folding_p ()))
 477     return error_mark_node;
 478
 479   /* OK, we can return constructor.  See if we need to fetch it from disk
 480      in LTO mode.  */
 481   if (DECL_INITIAL (real_decl) != error_mark_node
 482       || !in_lto_p)
 483     return DECL_INITIAL (real_decl);
 484   return real_node->get_constructor ();
 485 }
 486
 487 /* Add the variable DECL to the varpool.
 488    Unlike finalize_decl function is intended to be used
 489    by middle end and allows insertion of new variable at arbitrary point
 490    of compilation.  */
 491 void
 492 varpool_node::add (tree decl)
 493 {
 494   varpool_node *node;
 495   varpool_node::finalize_decl (decl);
 496   node = varpool_node::get_create (decl);
 497   symtab->call_varpool_insertion_hooks (node);
 498   if (node->externally_visible_p ())
 499     node->externally_visible = true;
 500   if (lookup_attribute ("no_reorder", DECL_ATTRIBUTES (decl)))
 501     node->no_reorder = 1;
 502 }
 503
 504 /* Return variable availability.  See cgraph.h for description of individual
 505    return values.  */
 506 enum availability
 507 varpool_node::get_availability (void)
 508 {
 509   if (!definition)
 510     return AVAIL_NOT_AVAILABLE;
 511   if (!TREE_PUBLIC (decl))
 512     return AVAIL_AVAILABLE;
 513   if (DECL_IN_CONSTANT_POOL (decl)
 514       || DECL_VIRTUAL_P (decl))
 515     return AVAIL_AVAILABLE;
 516   if (alias && weakref)
 517     {
 518       enum availability avail;
 519
 520       ultimate_alias_target (&avail)->get_availability ();
 521       return avail;
 522     }
 523   /* If the variable can be overwritten, return OVERWRITABLE.  Takes
 524      care of at least one notable extension - the COMDAT variables
 525      used to share template instantiations in C++.  */
 526   if (decl_replaceable_p (decl)
 527       || DECL_EXTERNAL (decl))
 528     return AVAIL_INTERPOSABLE;
 529   return AVAIL_AVAILABLE;
 530 }
 531
 532 void
 533 varpool_node::analyze (void)
 534 {
 535   /* When reading back varpool at LTO time, we re-construct the queue in order
 536      to have "needed" list right by inserting all needed nodes into varpool.
 537      We however don't want to re-analyze already analyzed nodes.  */
 538   if (!analyzed)
 539     {
 540       gcc_assert (!in_lto_p || symtab->function_flags_ready);
 541       /* Compute the alignment early so function body expanders are
 542          already informed about increased alignment.  */
 543       align_variable (decl, 0);
 544     }
 545   if (alias)
 546     resolve_alias (varpool_node::get (alias_target));
 547   else if (DECL_INITIAL (decl))
 548     record_references_in_initializer (decl, analyzed);
 549   analyzed = true;
 550 }
 551
 552 /* Assemble thunks and aliases associated to varpool node.  */
 553
 554 void
 555 varpool_node::assemble_aliases (void)
 556 {
 557   ipa_ref *ref;
 558
 559   FOR_EACH_ALIAS (this, ref)
 560     {
 561       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 562       do_assemble_alias (alias->decl,
 563                          DECL_ASSEMBLER_NAME (decl));
 564       alias->assemble_aliases ();
 565     }
 566 }
 567
 568 /* Output one variable, if necessary.  Return whether we output it.  */
 569
 570 bool
 571 varpool_node::assemble_decl (void)
 572 {
 573   /* Aliases are outout when their target is produced or by
 574      output_weakrefs.  */
 575   if (alias)
 576     return false;
 577
 578   /* Constant pool is output from RTL land when the reference
 579      survive till this level.  */
 580   if (DECL_IN_CONSTANT_POOL (decl) && TREE_ASM_WRITTEN (decl))
 581     return false;
 582
 583   /* Decls with VALUE_EXPR should not be in the varpool at all.  They
 584      are not real variables, but just info for debugging and codegen.
 585      Unfortunately at the moment emutls is not updating varpool correctly
 586      after turning real vars into value_expr vars.  */
 587   if (DECL_HAS_VALUE_EXPR_P (decl)
 588       && !targetm.have_tls)
 589     return false;
 590
 591   /* Hard register vars do not need to be output.  */
 592   if (DECL_HARD_REGISTER (decl))
 593     return false;
 594
 595   gcc_checking_assert (!TREE_ASM_WRITTEN (decl)
 596                        && TREE_CODE (decl) == VAR_DECL
 597                        && !DECL_HAS_VALUE_EXPR_P (decl));
 598
 599   if (!in_other_partition
 600       && !DECL_EXTERNAL (decl))
 601     {
 602       get_constructor ();
 603       assemble_variable (decl, 0, 1, 0);
 604       gcc_assert (TREE_ASM_WRITTEN (decl));
 605       gcc_assert (definition);
 606       assemble_aliases ();
 607       return true;
 608     }
 609
 610   return false;
 611 }
 612
 613 /* Add NODE to queue starting at FIRST.
 614    The queue is linked via AUX pointers and terminated by pointer to 1.  */
 615
 616 static void
 617 enqueue_node (varpool_node *node, varpool_node **first)
 618 {
 619   if (node->aux)
 620     return;
 621   gcc_checking_assert (*first);
 622   node->aux = *first;
 623   *first = node;
 624 }
 625
 626 /* Optimization of function bodies might've rendered some variables as
 627    unnecessary so we want to avoid these from being compiled.  Re-do
 628    reachability starting from variables that are either externally visible
 629    or was referred from the asm output routines.  */
 630
 631 void
 632 symbol_table::remove_unreferenced_decls (void)
 633 {
 634   varpool_node *next, *node;
 635   varpool_node *first = (varpool_node *)(void *)1;
 636   int i;
 637   ipa_ref *ref = NULL;
 638   hash_set<varpool_node *> referenced;
 639
 640   if (seen_error ())
 641     return;
 642
 643   if (dump_file)
 644     fprintf (dump_file, "Trivially needed variables:");
 645   FOR_EACH_DEFINED_VARIABLE (node)
 646     {
 647       if (node->analyzed
 648           && (!node->can_remove_if_no_refs_p ()
 649               /* We just expanded all function bodies.  See if any of
 650                  them needed the variable.  */
 651               || DECL_RTL_SET_P (node->decl)))
 652         {
 653           enqueue_node (node, &first);
 654           if (dump_file)
 655             fprintf (dump_file, " %s", node->asm_name ());
 656         }
 657     }
 658   while (first != (varpool_node *)(void *)1)
 659     {
 660       node = first;
 661       first = (varpool_node *)first->aux;
 662
 663       if (node->same_comdat_group)
 664         {
 665           symtab_node *next;
 666           for (next = node->same_comdat_group;
 667                next != node;
 668                next = next->same_comdat_group)
 669             {
 670               varpool_node *vnext = dyn_cast <varpool_node *> (next);
 671               if (vnext && vnext->analyzed && !next->comdat_local_p ())
 672                 enqueue_node (vnext, &first);
 673             }
 674         }
 675       for (i = 0; node->iterate_reference (i, ref); i++)
 676         {
 677           varpool_node *vnode = dyn_cast <varpool_node *> (ref->referred);
 678           if (vnode
 679               && !vnode->in_other_partition
 680               && (!DECL_EXTERNAL (ref->referred->decl)
 681                   || vnode->alias)
 682               && vnode->analyzed)
 683             enqueue_node (vnode, &first);
 684           else
 685             referenced.add (node);
 686         }
 687     }
 688   if (dump_file)
 689     fprintf (dump_file, "\nRemoving variables:");
 690   for (node = first_defined_variable (); node; node = next)
 691     {
 692       next = next_defined_variable (node);
 693       if (!node->aux && !node->no_reorder)
 694         {
 695           if (dump_file)
 696             fprintf (dump_file, " %s", node->asm_name ());
 697           if (referenced.contains(node))
 698             node->remove_initializer ();
 699           else
 700             node->remove ();
 701         }
 702     }
 703
 704   if (dump_file)
 705     fprintf (dump_file, "\n");
 706 }
 707
 708 /* For variables in named sections make sure get_variable_section
 709    is called before we switch to those sections.  Then section
 710    conflicts between read-only and read-only requiring relocations
 711    sections can be resolved.  */
 712 void
 713 varpool_node::finalize_named_section_flags (void)
 714 {
 715   if (!TREE_ASM_WRITTEN (decl)
 716       && !alias
 717       && !in_other_partition
 718       && !DECL_EXTERNAL (decl)
 719       && TREE_CODE (decl) == VAR_DECL
 720       && !DECL_HAS_VALUE_EXPR_P (decl)
 721       && get_section ())
 722     get_variable_section (decl, false);
 723 }
 724
 725 /* Output all variables enqueued to be assembled.  */
 726 bool
 727 symbol_table::output_variables (void)
 728 {
 729   bool changed = false;
 730   varpool_node *node;
 731
 732   if (seen_error ())
 733     return false;
 734
 735   remove_unreferenced_decls ();
 736
 737   timevar_push (TV_VAROUT);
 738
 739   FOR_EACH_VARIABLE (node)
 740     if (!node->definition
 741         && !DECL_HAS_VALUE_EXPR_P (node->decl)
 742         && !DECL_HARD_REGISTER (node->decl))
 743       assemble_undefined_decl (node->decl);
 744   FOR_EACH_DEFINED_VARIABLE (node)
 745     {
 746       /* Handled in output_in_order.  */
 747       if (node->no_reorder)
 748         continue;
 749
 750       node->finalize_named_section_flags ();
 751     }
 752
 753   FOR_EACH_DEFINED_VARIABLE (node)
 754     {
 755       /* Handled in output_in_order.  */
 756       if (node->no_reorder)
 757         continue;
 758       if (node->assemble_decl ())
 759         changed = true;
 760     }
 761   timevar_pop (TV_VAROUT);
 762   return changed;
 763 }
 764
 765 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 766    Extra name aliases are output whenever DECL is output.  */
 767
 768 varpool_node *
 769 varpool_node::create_alias (tree alias, tree decl)
 770 {
 771   varpool_node *alias_node;
 772
 773   gcc_assert (TREE_CODE (decl) == VAR_DECL);
 774   gcc_assert (TREE_CODE (alias) == VAR_DECL);
 775   alias_node = varpool_node::get_create (alias);
 776   alias_node->alias = true;
 777   alias_node->definition = true;
 778   alias_node->alias_target = decl;
 779   if (lookup_attribute ("weakref", DECL_ATTRIBUTES (alias)) != NULL)
 780     alias_node->weakref = true;
 781   return alias_node;
 782 }
 783
 784 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 785    Extra name aliases are output whenever DECL is output.  */
 786
 787 varpool_node *
 788 varpool_node::create_extra_name_alias (tree alias, tree decl)
 789 {
 790   varpool_node *alias_node;
 791
 792 #ifndef ASM_OUTPUT_DEF
 793   /* If aliases aren't supported by the assembler, fail.  */
 794   return NULL;
 795 #endif
 796   alias_node = varpool_node::create_alias (alias, decl);
 797   alias_node->cpp_implicit_alias = true;
 798
 799   /* Extra name alias mechanizm creates aliases really late
 800      via DECL_ASSEMBLER_NAME mechanizm.
 801      This is unfortunate because they are not going through the
 802      standard channels.  Ensure they get output.  */
 803   if (symtab->cpp_implicit_aliases_done)
 804     alias_node->resolve_alias (varpool_node::get_create (decl));
 805   return alias_node;
 806 }
 807
 808 /* Worker for call_for_symbol_and_aliases.  */
 809
 810 bool
 811 varpool_node::call_for_symbol_and_aliases_1 (bool (*callback) (varpool_node *,
 812                                                                void *),
 813                                              void *data,
 814                                              bool include_overwritable)
 815 {
 816   ipa_ref *ref;
 817
 818   FOR_EACH_ALIAS (this, ref)
 819     {
 820       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 821       if (include_overwritable
 822           || alias->get_availability () > AVAIL_INTERPOSABLE)
 823         if (alias->call_for_symbol_and_aliases (callback, data,
 824                                                 include_overwritable))
 825           return true;
 826     }
 827   return false;
 828 }