gcc/varpool.c

   1 /* Callgraph handling code.
   2    Copyright (C) 2003-2020 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   return new (ggc_alloc<varpool_node> ()) varpool_node ();
 138 }
 139
 140 /* Return varpool node assigned to DECL.  Create new one when needed.  */
 141 varpool_node *
 142 varpool_node::get_create (tree decl)
 143 {
 144   varpool_node *node = varpool_node::get (decl);
 145   gcc_checking_assert (VAR_P (decl));
 146   if (node)
 147     return node;
 148
 149   node = varpool_node::create_empty ();
 150   node->decl = decl;
 151
 152   if ((flag_openacc || flag_openmp)
 153       && lookup_attribute ("omp declare target", DECL_ATTRIBUTES (decl)))
 154     {
 155       node->offloadable = 1;
 156       if (ENABLE_OFFLOADING && !DECL_EXTERNAL (decl))
 157         {
 158           g->have_offload = true;
 159           if (!in_lto_p)
 160             vec_safe_push (offload_vars, decl);
 161         }
 162     }
 163
 164   node->register_symbol ();
 165   return node;
 166 }
 167
 168 /* Remove variable from symbol table.  */
 169
 170 void
 171 varpool_node::remove (void)
 172 {
 173   symtab->call_varpool_removal_hooks (this);
 174   if (lto_file_data)
 175     {
 176       lto_free_function_in_decl_state_for_node (this);
 177       lto_file_data = NULL;
 178     }
 179
 180   /* When streaming we can have multiple nodes associated with decl.  */
 181   if (symtab->state == LTO_STREAMING)
 182     ;
 183   /* Keep constructor when it may be used for folding. We remove
 184      references to external variables before final compilation.  */
 185   else if (DECL_INITIAL (decl) && DECL_INITIAL (decl) != error_mark_node
 186            && !ctor_useable_for_folding_p ())
 187     remove_initializer ();
 188
 189   unregister (NULL);
 190   ggc_free (this);
 191 }
 192
 193 /* Remove node initializer when it is no longer needed.  */
 194 void
 195 varpool_node::remove_initializer (void)
 196 {
 197   if (DECL_INITIAL (decl)
 198       && !DECL_IN_CONSTANT_POOL (decl)
 199       /* Keep vtables for BINFO folding.  */
 200       && !DECL_VIRTUAL_P (decl)
 201       /* FIXME: http://gcc.gnu.org/PR55395 */
 202       && debug_info_level == DINFO_LEVEL_NONE
 203       /* When doing declaration merging we have duplicate
 204          entries for given decl.  Do not attempt to remove
 205          the bodies, or we will end up removing
 206          wrong one.  */
 207       && symtab->state != LTO_STREAMING)
 208     DECL_INITIAL (decl) = error_mark_node;
 209 }
 210
 211 /* Dump given varpool node to F.  */
 212 void
 213 varpool_node::dump (FILE *f)
 214 {
 215   dump_base (f);
 216   fprintf (f, "  Availability: %s\n",
 217            symtab->function_flags_ready
 218            ? cgraph_availability_names[get_availability ()]
 219            : "not-ready");
 220   fprintf (f, "  Varpool flags:");
 221   if (DECL_INITIAL (decl))
 222     fprintf (f, " initialized");
 223   if (output)
 224     fprintf (f, " output");
 225   if (used_by_single_function)
 226     fprintf (f, " used-by-single-function");
 227   if (TREE_READONLY (decl))
 228     fprintf (f, " read-only");
 229   if (ctor_useable_for_folding_p ())
 230     fprintf (f, " const-value-known");
 231   if (writeonly)
 232     fprintf (f, " write-only");
 233   if (tls_model)
 234     fprintf (f, " tls-%s", tls_model_names [tls_model]);
 235   fprintf (f, "\n");
 236 }
 237
 238
 239 /* Dump given varpool node to stderr.  */
 240 void varpool_node::debug (void)
 241 {
 242   varpool_node::dump (stderr);
 243 }
 244
 245 /* Dump the variable pool to F.  */
 246 void
 247 varpool_node::dump_varpool (FILE *f)
 248 {
 249   varpool_node *node;
 250
 251   fprintf (f, "variable pool:\n\n");
 252   FOR_EACH_VARIABLE (node)
 253     node->dump (f);
 254 }
 255
 256 /* Dump the variable pool to stderr.  */
 257
 258 DEBUG_FUNCTION void
 259 varpool_node::debug_varpool (void)
 260 {
 261   dump_varpool (stderr);
 262 }
 263
 264 /* Given an assembler name, lookup node.  */
 265 varpool_node *
 266 varpool_node::get_for_asmname (tree asmname)
 267 {
 268   if (symtab_node *node = symtab_node::get_for_asmname (asmname))
 269     return dyn_cast <varpool_node *> (node);
 270   else
 271     return NULL;
 272 }
 273
 274 /* When doing LTO, read variable's constructor from disk if
 275    it is not already present.  */
 276
 277 tree
 278 varpool_node::get_constructor (void)
 279 {
 280   lto_file_decl_data *file_data;
 281   const char *data, *name;
 282   size_t len;
 283
 284   if (DECL_INITIAL (decl) != error_mark_node
 285       || !in_lto_p
 286       || !lto_file_data)
 287     return DECL_INITIAL (decl);
 288
 289   timevar_push (TV_IPA_LTO_CTORS_IN);
 290
 291   file_data = lto_file_data;
 292   name = IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl));
 293
 294   /* We may have renamed the declaration, e.g., a static function.  */
 295   name = lto_get_decl_name_mapping (file_data, name);
 296   struct lto_in_decl_state *decl_state
 297          = lto_get_function_in_decl_state (file_data, decl);
 298
 299   data = lto_get_section_data (file_data, LTO_section_function_body,
 300                                name, order - file_data->order_base,
 301                                &len, decl_state->compressed);
 302   if (!data)
 303     fatal_error (input_location, "%s: section %s.%d is missing",
 304                  file_data->file_name,
 305                  name, order - file_data->order_base);
 306
 307   if (!quiet_flag)
 308     fprintf (stderr, " in:%s", IDENTIFIER_POINTER (DECL_ASSEMBLER_NAME (decl)));
 309   lto_input_variable_constructor (file_data, this, data);
 310   gcc_assert (DECL_INITIAL (decl) != error_mark_node);
 311   lto_stats.num_function_bodies++;
 312   lto_free_section_data (file_data, LTO_section_function_body, name,
 313                          data, len, decl_state->compressed);
 314   lto_free_function_in_decl_state_for_node (this);
 315   timevar_pop (TV_IPA_LTO_CTORS_IN);
 316   return DECL_INITIAL (decl);
 317 }
 318
 319 /* Return true if variable has constructor that can be used for folding.  */
 320
 321 bool
 322 varpool_node::ctor_useable_for_folding_p (void)
 323 {
 324   varpool_node *real_node = this;
 325
 326   if (real_node->alias && real_node->definition)
 327     real_node = ultimate_alias_target ();
 328
 329   if (TREE_CODE (decl) == CONST_DECL
 330       || DECL_IN_CONSTANT_POOL (decl))
 331     return true;
 332   if (TREE_THIS_VOLATILE (decl))
 333     return false;
 334
 335   /* Avoid attempts to load constructors that was not streamed.  */
 336   if (in_lto_p && DECL_INITIAL (real_node->decl) == error_mark_node
 337       && real_node->body_removed)
 338     return false;
 339
 340   /* If we do not have a constructor, we can't use it.  */
 341   if (DECL_INITIAL (real_node->decl) == error_mark_node
 342       && !real_node->lto_file_data)
 343     return false;
 344
 345   /* Vtables are defined by their types and must match no matter of interposition
 346      rules.  */
 347   if (DECL_VIRTUAL_P (decl))
 348     {
 349       /* The C++ front end creates VAR_DECLs for vtables of typeinfo
 350          classes not defined in the current TU so that it can refer
 351          to them from typeinfo objects.  Avoid returning NULL_TREE.  */
 352       return DECL_INITIAL (real_node->decl) != NULL;
 353     }
 354
 355   /* An alias of a read-only variable is also read-only, since the variable
 356      is stored in read-only memory.  We also accept read-only aliases of
 357      non-read-only locations assuming that the user knows what he is asking
 358      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 enforce 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 expands 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 && !in_other_partition)
 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->symver)
 543         do_assemble_symver (alias->decl,
 544                             DECL_ASSEMBLER_NAME (decl));
 545       else if (!alias->transparent_alias)
 546         do_assemble_alias (alias->decl,
 547                            DECL_ASSEMBLER_NAME (decl));
 548       alias->assemble_aliases ();
 549     }
 550 }
 551
 552 /* Output one variable, if necessary.  Return whether we output it.  */
 553
 554 bool
 555 varpool_node::assemble_decl (void)
 556 {
 557   /* Aliases are output when their target is produced or by
 558      output_weakrefs.  */
 559   if (alias)
 560     return false;
 561
 562   /* Constant pool is output from RTL land when the reference
 563      survive till this level.  */
 564   if (DECL_IN_CONSTANT_POOL (decl) && TREE_ASM_WRITTEN (decl))
 565     return false;
 566
 567   /* Decls with VALUE_EXPR should not be in the varpool at all.  They
 568      are not real variables, but just info for debugging and codegen.
 569      Unfortunately at the moment emutls is not updating varpool correctly
 570      after turning real vars into value_expr vars.  */
 571   if (DECL_HAS_VALUE_EXPR_P (decl)
 572       && !targetm.have_tls)
 573     return false;
 574
 575   /* Hard register vars do not need to be output.  */
 576   if (DECL_HARD_REGISTER (decl))
 577     return false;
 578
 579   gcc_checking_assert (!TREE_ASM_WRITTEN (decl)
 580                        && VAR_P (decl)
 581                        && !DECL_HAS_VALUE_EXPR_P (decl));
 582
 583   if (!in_other_partition
 584       && !DECL_EXTERNAL (decl))
 585     {
 586       get_constructor ();
 587       assemble_variable (decl, 0, 1, 0);
 588       gcc_assert (TREE_ASM_WRITTEN (decl));
 589       gcc_assert (definition);
 590       assemble_aliases ();
 591       /* After the parser has generated debugging information, augment
 592          this information with any new location/etc information that may
 593          have become available after the compilation proper.  */
 594       debug_hooks->late_global_decl (decl);
 595       return true;
 596     }
 597
 598   return false;
 599 }
 600
 601 /* Add NODE to queue starting at FIRST.
 602    The queue is linked via AUX pointers and terminated by pointer to 1.  */
 603
 604 static void
 605 enqueue_node (varpool_node *node, varpool_node **first)
 606 {
 607   if (node->aux)
 608     return;
 609   gcc_checking_assert (*first);
 610   node->aux = *first;
 611   *first = node;
 612 }
 613
 614 /* Optimization of function bodies might've rendered some variables as
 615    unnecessary so we want to avoid these from being compiled.  Re-do
 616    reachability starting from variables that are either externally visible
 617    or was referred from the asm output routines.  */
 618
 619 void
 620 symbol_table::remove_unreferenced_decls (void)
 621 {
 622   varpool_node *next, *node;
 623   varpool_node *first = (varpool_node *)(void *)1;
 624   int i;
 625   ipa_ref *ref = NULL;
 626   hash_set<varpool_node *> referenced;
 627
 628   if (seen_error ())
 629     return;
 630
 631   if (dump_file)
 632     fprintf (dump_file, "Trivially needed variables:");
 633   FOR_EACH_DEFINED_VARIABLE (node)
 634     {
 635       if (node->analyzed
 636           && (!node->can_remove_if_no_refs_p ()
 637               /* We just expanded all function bodies.  See if any of
 638                  them needed the variable.  */
 639               || DECL_RTL_SET_P (node->decl)))
 640         {
 641           enqueue_node (node, &first);
 642           if (dump_file)
 643             fprintf (dump_file, " %s", node->dump_asm_name ());
 644         }
 645     }
 646   while (first != (varpool_node *)(void *)1)
 647     {
 648       node = first;
 649       first = (varpool_node *)first->aux;
 650
 651       if (node->same_comdat_group)
 652         {
 653           symtab_node *next;
 654           for (next = node->same_comdat_group;
 655                next != node;
 656                next = next->same_comdat_group)
 657             {
 658               varpool_node *vnext = dyn_cast <varpool_node *> (next);
 659               if (vnext && vnext->analyzed && !next->comdat_local_p ())
 660                 enqueue_node (vnext, &first);
 661             }
 662         }
 663       for (i = 0; node->iterate_reference (i, ref); i++)
 664         {
 665           varpool_node *vnode = dyn_cast <varpool_node *> (ref->referred);
 666           if (vnode
 667               && !vnode->in_other_partition
 668               && (!DECL_EXTERNAL (ref->referred->decl)
 669                   || vnode->alias)
 670               && vnode->analyzed)
 671             enqueue_node (vnode, &first);
 672           else
 673             {
 674               referenced.add (vnode);
 675               while (vnode && vnode->alias && vnode->definition)
 676                 {
 677                   vnode = vnode->get_alias_target ();
 678                   referenced.add (vnode);
 679                 }
 680             }
 681         }
 682     }
 683   if (dump_file)
 684     fprintf (dump_file, "\nRemoving variables:");
 685   for (node = first_defined_variable (); node; node = next)
 686     {
 687       next = next_defined_variable (node);
 688       if (!node->aux && !node->no_reorder)
 689         {
 690           if (dump_file)
 691             fprintf (dump_file, " %s", node->dump_asm_name ());
 692           if (referenced.contains(node))
 693             node->remove_initializer ();
 694           else
 695             node->remove ();
 696         }
 697     }
 698
 699   if (dump_file)
 700     fprintf (dump_file, "\n");
 701 }
 702
 703 /* For variables in named sections make sure get_variable_section
 704    is called before we switch to those sections.  Then section
 705    conflicts between read-only and read-only requiring relocations
 706    sections can be resolved.  */
 707 void
 708 varpool_node::finalize_named_section_flags (void)
 709 {
 710   if (!TREE_ASM_WRITTEN (decl)
 711       && !alias
 712       && !in_other_partition
 713       && !DECL_EXTERNAL (decl)
 714       && VAR_P (decl)
 715       && !DECL_HAS_VALUE_EXPR_P (decl)
 716       && get_section ())
 717     get_variable_section (decl, false);
 718 }
 719
 720 /* Output all variables enqueued to be assembled.  */
 721 bool
 722 symbol_table::output_variables (void)
 723 {
 724   bool changed = false;
 725   varpool_node *node;
 726
 727   if (seen_error ())
 728     return false;
 729
 730   remove_unreferenced_decls ();
 731
 732   timevar_push (TV_VAROUT);
 733
 734   FOR_EACH_DEFINED_VARIABLE (node)
 735     {
 736       /* Handled in output_in_order.  */
 737       if (node->no_reorder)
 738         continue;
 739
 740       node->finalize_named_section_flags ();
 741     }
 742
 743   /* There is a similar loop in output_in_order.  Please keep them in sync.  */
 744   FOR_EACH_VARIABLE (node)
 745     {
 746       /* Handled in output_in_order.  */
 747       if (node->no_reorder)
 748         continue;
 749       if (DECL_HARD_REGISTER (node->decl)
 750           || DECL_HAS_VALUE_EXPR_P (node->decl))
 751         continue;
 752       if (node->definition)
 753         changed |= node->assemble_decl ();
 754       else
 755         assemble_undefined_decl (node->decl);
 756     }
 757   timevar_pop (TV_VAROUT);
 758   return changed;
 759 }
 760
 761 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 762    Extra name aliases are output whenever DECL is output.  */
 763
 764 varpool_node *
 765 varpool_node::create_alias (tree alias, tree decl)
 766 {
 767   varpool_node *alias_node;
 768
 769   gcc_assert (VAR_P (decl));
 770   gcc_assert (VAR_P (alias));
 771   alias_node = varpool_node::get_create (alias);
 772   alias_node->alias = true;
 773   alias_node->definition = true;
 774   alias_node->alias_target = decl;
 775   if (lookup_attribute ("weakref", DECL_ATTRIBUTES (alias)) != NULL)
 776     alias_node->weakref = alias_node->transparent_alias = true;
 777   return alias_node;
 778 }
 779
 780 /* Attempt to mark ALIAS as an alias to DECL.  Return TRUE if successful.
 781    Extra name aliases are output whenever DECL is output.  */
 782
 783 varpool_node *
 784 varpool_node::create_extra_name_alias (tree alias, tree decl)
 785 {
 786   varpool_node *alias_node;
 787
 788   /* If aliases aren't supported by the assembler, fail.  */
 789   if (!TARGET_SUPPORTS_ALIASES)
 790     return NULL;
 791
 792   alias_node = varpool_node::create_alias (alias, decl);
 793   alias_node->cpp_implicit_alias = true;
 794
 795   /* Extra name alias mechanism creates aliases really late
 796      via DECL_ASSEMBLER_NAME mechanism.
 797      This is unfortunate because they are not going through the
 798      standard channels.  Ensure they get output.  */
 799   if (symtab->cpp_implicit_aliases_done)
 800     alias_node->resolve_alias (varpool_node::get_create (decl));
 801   return alias_node;
 802 }
 803
 804 /* Worker for call_for_symbol_and_aliases.  */
 805
 806 bool
 807 varpool_node::call_for_symbol_and_aliases_1 (bool (*callback) (varpool_node *,
 808                                                                void *),
 809                                              void *data,
 810                                              bool include_overwritable)
 811 {
 812   ipa_ref *ref;
 813
 814   FOR_EACH_ALIAS (this, ref)
 815     {
 816       varpool_node *alias = dyn_cast <varpool_node *> (ref->referring);
 817       if (include_overwritable
 818           || alias->get_availability () > AVAIL_INTERPOSABLE)
 819         if (alias->call_for_symbol_and_aliases (callback, data,
 820                                                 include_overwritable))
 821           return true;
 822     }
 823   return false;
 824 }