gcc/varpool.c

   1 /* Callgraph handling code.
   2    Copyright (C) 2003-2018 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 (need_bounds_init)
 230     fprintf (f, " need-bounds-init");
 231   if (TREE_READONLY (decl))
 232     fprintf (f, " read-only");
 233   if (ctor_useable_for_folding_p ())
 234     fprintf (f, " const-value-known");
 235   if (writeonly)
 236     fprintf (f, " write-only");
 237   if (tls_model)
 238     fprintf (f, " tls-%s", tls_model_names [tls_model]);
 239   fprintf (f, "\n");
 240 }
 241
 242
 243 /* Dump given varpool node to stderr.  */
 244 void varpool_node::debug (void)
 245 {
 246   varpool_node::dump (stderr);
 247 }
 248
 249 /* Dump the variable pool to F.  */
 250 void
 251 varpool_node::dump_varpool (FILE *f)
 252 {
 253   varpool_node *node;
 254
 255   fprintf (f, "variable pool:\n\n");
 256   FOR_EACH_VARIABLE (node)
 257     node->dump (f);
 258 }
 259
 260 /* Dump the variable pool to stderr.  */
 261
 262 DEBUG_FUNCTION void
 263 varpool_node::debug_varpool (void)
 264 {
 265   dump_varpool (stderr);
 266 }
 267
 268 /* Given an assembler name, lookup node.  */
 269 varpool_node *
 270 varpool_node::get_for_asmname (tree asmname)
 271 {
 272   if (symtab_node *node = symtab_node::get_for_asmname (asmname))
 273     return dyn_cast <varpool_node *> (node);
 274   else
 275     return NULL;
 276 }
 277
 278 /* When doing LTO, read variable's constructor from disk if
 279    it is not already present.  */
 280
 281 tree
 282 varpool_node::get_constructor (void)
 283 {
 284   lto_file_decl_data *file_data;
 285   const char *data, *name;
 286   size_t len;
 287
 288   if (DECL_INITIAL (decl) != error_mark_node
 289       || !in_lto_p
 290       || !lto_file_data)
 291     return DECL_INITIAL (decl);
 292
 293   timevar_push (TV_IPA_LTO_CTORS_IN);
 294
 295   file_data = lto_file_data;
 296   name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 297
 298   /* We may have renamed the declaration, e.g., a static function.  */
 299   name = lto_get_decl_name_mapping (file_data, name);
 300   struct lto_in_decl_state *decl_state
 301          = lto_get_function_in_decl_state (file_data, decl);
 302
 303   data = lto_get_section_data (file_data, LTO_section_function_body,
 304                                name, &len, decl_state->compressed);
 305   if (!data)
 306     fatal_error (input_location, "%s: section %s is missing",
 307                  file_data->file_name,
 308                  name);
 309
 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   /* If we do not have a constructor, we can't use it.  */
 337   if (DECL_INITIAL (real_node->decl) == error_mark_node
 338       && !real_node->lto_file_data)
 339     return false;
 340
 341   /* Avoid attempts to load constructors that was not streamed.  */
 342   if (flag_ltrans && DECL_INITIAL (real_node->decl) == error_mark_node
 343       && real_node->body_removed)
 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   /* Static constant bounds are created to be
 404      used instead of constants and therefore
 405      do not let folding it.  */
 406   if (POINTER_BOUNDS_P (decl))
 407     return error_mark_node;
 408
 409   if (TREE_CODE (decl) == CONST_DECL
 410       || DECL_IN_CONSTANT_POOL (decl))
 411     return DECL_INITIAL (decl);
 412
 413   if (TREE_THIS_VOLATILE (decl))
 414     return error_mark_node;
 415
 416   /* Do not care about automatic variables.  Those are never initialized
 417      anyway, because gimplifier exapnds the code.  */
 418   if (!TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
 419     {
 420       gcc_assert (!TREE_PUBLIC (decl));
 421       return error_mark_node;
 422     }
 423
 424   gcc_assert (VAR_P (decl));
 425
 426   real_node = node = varpool_node::get (decl);
 427   if (node)
 428     {
 429       real_node = node->ultimate_alias_target ();
 430       real_decl = real_node->decl;
 431     }
 432   else
 433     real_decl = decl;
 434
 435   /* See if we are dealing with alias.
 436      In most cases alias is just alternative symbol pointing to a given
 437      constructor.  This allows us to use interposition rules of DECL
 438      constructor of REAL_NODE.  However weakrefs are special by being just
 439      alternative name of their target (if defined).  */
 440   if (decl != real_decl)
 441     {
 442       gcc_assert (!DECL_INITIAL (decl)
 443                   || (node->alias && node->get_alias_target () == real_node)
 444                   || DECL_INITIAL (decl) == error_mark_node);
 445       while (node->transparent_alias && node->analyzed)
 446         {
 447           node = node->get_alias_target ();
 448           decl = node->decl;
 449         }
 450     }
 451
 452   if ((!DECL_VIRTUAL_P (real_decl)
 453        || DECL_INITIAL (real_decl) == error_mark_node
 454        || !DECL_INITIAL (real_decl))
 455       && (!node || !node->ctor_useable_for_folding_p ()))
 456     return error_mark_node;
 457
 458   /* OK, we can return constructor.  See if we need to fetch it from disk
 459      in LTO mode.  */
 460   if (DECL_INITIAL (real_decl) != error_mark_node
 461       || !in_lto_p)
 462     return DECL_INITIAL (real_decl);
 463   return real_node->get_constructor ();
 464 }
 465
 466 /* Add the variable DECL to the varpool.
 467    Unlike finalize_decl function is intended to be used
 468    by middle end and allows insertion of new variable at arbitrary point
 469    of compilation.  */
 470 void
 471 varpool_node::add (tree decl)
 472 {
 473   varpool_node *node;
 474   varpool_node::finalize_decl (decl);
 475   node = varpool_node::get_create (decl);
 476   symtab->call_varpool_insertion_hooks (node);
 477   if (node->externally_visible_p ())
 478     node->externally_visible = true;
 479   if (lookup_attribute ("no_reorder", DECL_ATTRIBUTES (decl)))
 480     node->no_reorder = 1;
 481 }
 482
 483 /* Return variable availability.  See cgraph.h for description of individual
 484    return values.  */
 485 enum availability
 486 varpool_node::get_availability (symtab_node *ref)
 487 {
 488   if (!definition)
 489     return AVAIL_NOT_AVAILABLE;
 490   if (!TREE_PUBLIC (decl))
 491     return AVAIL_AVAILABLE;
 492   if (DECL_IN_CONSTANT_POOL (decl)
 493       || DECL_VIRTUAL_P (decl))
 494     return AVAIL_AVAILABLE;
 495   if (transparent_alias && definition)
 496     {
 497       enum availability avail;
 498
 499       ultimate_alias_target (&avail, ref);
 500       return avail;
 501     }
 502   /* If this is a reference from symbol itself and there are no aliases, we
 503      may be sure that the symbol was not interposed by something else because
 504      the symbol itself would be unreachable otherwise.  */
 505   if ((this == ref && !has_aliases_p ())
 506       || (ref && get_comdat_group ()
 507           && get_comdat_group () == ref->get_comdat_group ()))
 508     return AVAIL_AVAILABLE;
 509   /* If the variable can be overwritten, return OVERWRITABLE.  Takes
 510      care of at least one notable extension - the COMDAT variables
 511      used to share template instantiations in C++.  */
 512   if (decl_replaceable_p (decl)
 513       || DECL_EXTERNAL (decl))
 514     return AVAIL_INTERPOSABLE;
 515   return AVAIL_AVAILABLE;
 516 }
 517
 518 void
 519 varpool_node::analyze (void)
 520 {
 521   /* When reading back varpool at LTO time, we re-construct the queue in order
 522      to have "needed" list right by inserting all needed nodes into varpool.
 523      We however don't want to re-analyze already analyzed nodes.  */
 524   if (!analyzed)
 525     {
 526       gcc_assert (!in_lto_p || symtab->function_flags_ready);
 527       /* Compute the alignment early so function body expanders are
 528          already informed about increased alignment.  */
 529       align_variable (decl, 0);
 530     }
 531   if (alias)
 532     resolve_alias (varpool_node::get (alias_target));
 533   else if (DECL_INITIAL (decl))
 534     record_references_in_initializer (decl, analyzed);
 535   analyzed = true;
 536 }
 537
 538 /* Assemble thunks and aliases associated to varpool node.  */
 539
 540 void
 541 varpool_node::assemble_aliases (void)
 542 {
 543   ipa_ref *ref;
 544
 545   FOR_EACH_ALIAS (this, ref)
 546     {
 547       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 548       if (!alias->transparent_alias)
 549         do_assemble_alias (alias->decl,
 550                            DECL_ASSEMBLER_NAME (decl));
 551       alias->assemble_aliases ();
 552     }
 553 }
 554
 555 /* Output one variable, if necessary.  Return whether we output it.  */
 556
 557 bool
 558 varpool_node::assemble_decl (void)
 559 {
 560   /* Aliases are outout when their target is produced or by
 561      output_weakrefs.  */
 562   if (alias)
 563     return false;
 564
 565   /* Constant pool is output from RTL land when the reference
 566      survive till this level.  */
 567   if (DECL_IN_CONSTANT_POOL (decl) && TREE_ASM_WRITTEN (decl))
 568     return false;
 569
 570   /* Decls with VALUE_EXPR should not be in the varpool at all.  They
 571      are not real variables, but just info for debugging and codegen.
 572      Unfortunately at the moment emutls is not updating varpool correctly
 573      after turning real vars into value_expr vars.  */
 574   if (DECL_HAS_VALUE_EXPR_P (decl)
 575       && !targetm.have_tls)
 576     return false;
 577
 578   /* Hard register vars do not need to be output.  */
 579   if (DECL_HARD_REGISTER (decl))
 580     return false;
 581
 582   gcc_checking_assert (!TREE_ASM_WRITTEN (decl)
 583                        && VAR_P (decl)
 584                        && !DECL_HAS_VALUE_EXPR_P (decl));
 585
 586   if (!in_other_partition
 587       && !DECL_EXTERNAL (decl))
 588     {
 589       get_constructor ();
 590       assemble_variable (decl, 0, 1, 0);
 591       gcc_assert (TREE_ASM_WRITTEN (decl));
 592       gcc_assert (definition);
 593       assemble_aliases ();
 594       /* After the parser has generated debugging information, augment
 595          this information with any new location/etc information that may
 596          have become available after the compilation proper.  */
 597       debug_hooks->late_global_decl (decl);
 598       return true;
 599     }
 600
 601   return false;
 602 }
 603
 604 /* Add NODE to queue starting at FIRST.
 605    The queue is linked via AUX pointers and terminated by pointer to 1.  */
 606
 607 static void
 608 enqueue_node (varpool_node *node, varpool_node **first)
 609 {
 610   if (node->aux)
 611     return;
 612   gcc_checking_assert (*first);
 613   node->aux = *first;
 614   *first = node;
 615 }
 616
 617 /* Optimization of function bodies might've rendered some variables as
 618    unnecessary so we want to avoid these from being compiled.  Re-do
 619    reachability starting from variables that are either externally visible
 620    or was referred from the asm output routines.  */
 621
 622 void
 623 symbol_table::remove_unreferenced_decls (void)
 624 {
 625   varpool_node *next, *node;
 626   varpool_node *first = (varpool_node *)(void *)1;
 627   int i;
 628   ipa_ref *ref = NULL;
 629   hash_set<varpool_node *> referenced;
 630
 631   if (seen_error ())
 632     return;
 633
 634   if (dump_file)
 635     fprintf (dump_file, "Trivially needed variables:");
 636   FOR_EACH_DEFINED_VARIABLE (node)
 637     {
 638       if (node->analyzed
 639           && (!node->can_remove_if_no_refs_p ()
 640               /* We just expanded all function bodies.  See if any of
 641                  them needed the variable.  */
 642               || DECL_RTL_SET_P (node->decl)))
 643         {
 644           enqueue_node (node, &first);
 645           if (dump_file)
 646             fprintf (dump_file, " %s", node->asm_name ());
 647         }
 648     }
 649   while (first != (varpool_node *)(void *)1)
 650     {
 651       node = first;
 652       first = (varpool_node *)first->aux;
 653
 654       if (node->same_comdat_group)
 655         {
 656           symtab_node *next;
 657           for (next = node->same_comdat_group;
 658                next != node;
 659                next = next->same_comdat_group)
 660             {
 661               varpool_node *vnext = dyn_cast <varpool_node *> (next);
 662               if (vnext && vnext->analyzed && !next->comdat_local_p ())
 663                 enqueue_node (vnext, &first);
 664             }
 665         }
 666       for (i = 0; node->iterate_reference (i, ref); i++)
 667         {
 668           varpool_node *vnode = dyn_cast <varpool_node *> (ref->referred);
 669           if (vnode
 670               && !vnode->in_other_partition
 671               && (!DECL_EXTERNAL (ref->referred->decl)
 672                   || vnode->alias)
 673               && vnode->analyzed)
 674             enqueue_node (vnode, &first);
 675           else
 676             {
 677               referenced.add (vnode);
 678               while (vnode && vnode->alias && vnode->definition)
 679                 {
 680                   vnode = vnode->get_alias_target ();
 681                   referenced.add (vnode);
 682                 }
 683             }
 684         }
 685     }
 686   if (dump_file)
 687     fprintf (dump_file, "\nRemoving variables:");
 688   for (node = first_defined_variable (); node; node = next)
 689     {
 690       next = next_defined_variable (node);
 691       if (!node->aux && !node->no_reorder)
 692         {
 693           if (dump_file)
 694             fprintf (dump_file, " %s", node->asm_name ());
 695           if (referenced.contains(node))
 696             node->remove_initializer ();
 697           else
 698             node->remove ();
 699         }
 700     }
 701
 702   if (dump_file)
 703     fprintf (dump_file, "\n");
 704 }
 705
 706 /* For variables in named sections make sure get_variable_section
 707    is called before we switch to those sections.  Then section
 708    conflicts between read-only and read-only requiring relocations
 709    sections can be resolved.  */
 710 void
 711 varpool_node::finalize_named_section_flags (void)
 712 {
 713   if (!TREE_ASM_WRITTEN (decl)
 714       && !alias
 715       && !in_other_partition
 716       && !DECL_EXTERNAL (decl)
 717       && VAR_P (decl)
 718       && !DECL_HAS_VALUE_EXPR_P (decl)
 719       && get_section ())
 720     get_variable_section (decl, false);
 721 }
 722
 723 /* Output all variables enqueued to be assembled.  */
 724 bool
 725 symbol_table::output_variables (void)
 726 {
 727   bool changed = false;
 728   varpool_node *node;
 729
 730   if (seen_error ())
 731     return false;
 732
 733   remove_unreferenced_decls ();
 734
 735   timevar_push (TV_VAROUT);
 736
 737   FOR_EACH_DEFINED_VARIABLE (node)
 738     {
 739       /* Handled in output_in_order.  */
 740       if (node->no_reorder)
 741         continue;
 742
 743       node->finalize_named_section_flags ();
 744     }
 745
 746   /* There is a similar loop in output_in_order.  Please keep them in sync.  */
 747   FOR_EACH_VARIABLE (node)
 748     {
 749       /* Handled in output_in_order.  */
 750       if (node->no_reorder)
 751         continue;
 752       if (DECL_HARD_REGISTER (node->decl)
 753           || DECL_HAS_VALUE_EXPR_P (node->decl))
 754         continue;
 755       if (node->definition)
 756         changed |= node->assemble_decl ();
 757       else
 758         assemble_undefined_decl (node->decl);
 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 (VAR_P (decl));
 773   gcc_assert (VAR_P (alias));
 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   /* If aliases aren't supported by the assembler, fail.  */
 792   if (!TARGET_SUPPORTS_ALIASES)
 793     return NULL;
 794
 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 }