gnu/dist/gcc4/gcc/tree-dfa.c

   1 /* Data flow functions for trees.
   2    Copyright (C) 2001, 2002, 2003, 2004, 2005 Free Software Foundation, Inc.
   3    Contributed by Diego Novillo <dnovillo@redhat.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 2, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING.  If not, write to
  19 the Free Software Foundation, 51 Franklin Street, Fifth Floor,
  20 Boston, MA 02110-1301, USA.  */
  21
  22 #include "config.h"
  23 #include "system.h"
  24 #include "coretypes.h"
  25 #include "tm.h"
  26 #include "hashtab.h"
  27 #include "pointer-set.h"
  28 #include "tree.h"
  29 #include "rtl.h"
  30 #include "tm_p.h"
  31 #include "hard-reg-set.h"
  32 #include "basic-block.h"
  33 #include "output.h"
  34 #include "timevar.h"
  35 #include "expr.h"
  36 #include "ggc.h"
  37 #include "langhooks.h"
  38 #include "flags.h"
  39 #include "function.h"
  40 #include "diagnostic.h"
  41 #include "tree-dump.h"
  42 #include "tree-gimple.h"
  43 #include "tree-flow.h"
  44 #include "tree-inline.h"
  45 #include "tree-pass.h"
  46 #include "convert.h"
  47 #include "params.h"
  48 #include "cgraph.h"
  49
  50 /* Build and maintain data flow information for trees.  */
  51
  52 /* Counters used to display DFA and SSA statistics.  */
  53 struct dfa_stats_d
  54 {
  55   long num_stmt_anns;
  56   long num_var_anns;
  57   long num_defs;
  58   long num_uses;
  59   long num_phis;
  60   long num_phi_args;
  61   int max_num_phi_args;
  62   long num_v_may_defs;
  63   long num_vuses;
  64   long num_v_must_defs;
  65 };
  66
  67
  68 /* Local functions.  */
  69 static void collect_dfa_stats (struct dfa_stats_d *);
  70 static tree collect_dfa_stats_r (tree *, int *, void *);
  71 static tree find_vars_r (tree *, int *, void *);
  72 static void add_referenced_var (tree, bool);
  73
  74
  75 /* Global declarations.  */
  76
  77 /* Array of all variables referenced in the function.  */
  78 htab_t referenced_vars;
  79
  80
  81 /*---------------------------------------------------------------------------
  82                         Dataflow analysis (DFA) routines
  83 ---------------------------------------------------------------------------*/
  84 /* Find all the variables referenced in the function.  This function
  85    builds the global arrays REFERENCED_VARS and CALL_CLOBBERED_VARS.
  86
  87    Note that this function does not look for statement operands, it simply
  88    determines what variables are referenced in the program and detects
  89    various attributes for each variable used by alias analysis and the
  90    optimizer.  */
  91
  92 static void
  93 find_referenced_vars (void)
  94 {
  95   basic_block bb;
  96   block_stmt_iterator si;
  97
  98   FOR_EACH_BB (bb)
  99     for (si = bsi_start (bb); !bsi_end_p (si); bsi_next (&si))
 100       {
 101         tree *stmt_p = bsi_stmt_ptr (si);
 102         walk_tree (stmt_p, find_vars_r, NULL, NULL);
 103       }
 104
 105 }
 106
 107 struct tree_opt_pass pass_referenced_vars =
 108 {
 109   NULL,                                 /* name */
 110   NULL,                                 /* gate */
 111   find_referenced_vars,                 /* execute */
 112   NULL,                                 /* sub */
 113   NULL,                                 /* next */
 114   0,                                    /* static_pass_number */
 115   TV_FIND_REFERENCED_VARS,              /* tv_id */
 116   PROP_gimple_leh | PROP_cfg,           /* properties_required */
 117   PROP_referenced_vars,                 /* properties_provided */
 118   0,                                    /* properties_destroyed */
 119   0,                                    /* todo_flags_start */
 120   0,                                    /* todo_flags_finish */
 121   0                                     /* letter */
 122 };
 123
 124
 125 /*---------------------------------------------------------------------------
 126                             Manage annotations
 127 ---------------------------------------------------------------------------*/
 128 /* Create a new annotation for a _DECL node T.  */
 129
 130 var_ann_t
 131 create_var_ann (tree t)
 132 {
 133   var_ann_t ann;
 134
 135   gcc_assert (t);
 136   gcc_assert (DECL_P (t));
 137   gcc_assert (!t->common.ann || t->common.ann->common.type == VAR_ANN);
 138
 139   ann = ggc_alloc (sizeof (*ann));
 140   memset ((void *) ann, 0, sizeof (*ann));
 141
 142   ann->common.type = VAR_ANN;
 143
 144   t->common.ann = (tree_ann_t) ann;
 145
 146   return ann;
 147 }
 148
 149
 150 /* Create a new annotation for a statement node T.  */
 151
 152 stmt_ann_t
 153 create_stmt_ann (tree t)
 154 {
 155   stmt_ann_t ann;
 156
 157   gcc_assert (is_gimple_stmt (t));
 158   gcc_assert (!t->common.ann || t->common.ann->common.type == STMT_ANN);
 159
 160   ann = ggc_alloc (sizeof (*ann));
 161   memset ((void *) ann, 0, sizeof (*ann));
 162
 163   ann->common.type = STMT_ANN;
 164
 165   /* Since we just created the annotation, mark the statement modified.  */
 166   ann->modified = true;
 167
 168   t->common.ann = (tree_ann_t) ann;
 169
 170   return ann;
 171 }
 172
 173 /* Create a new annotation for a tree T.  */
 174
 175 tree_ann_t
 176 create_tree_ann (tree t)
 177 {
 178   tree_ann_t ann;
 179
 180   gcc_assert (t);
 181   gcc_assert (!t->common.ann || t->common.ann->common.type == TREE_ANN_COMMON);
 182
 183   ann = ggc_alloc (sizeof (*ann));
 184   memset ((void *) ann, 0, sizeof (*ann));
 185
 186   ann->common.type = TREE_ANN_COMMON;
 187   t->common.ann = ann;
 188
 189   return ann;
 190 }
 191
 192 /* Build a temporary.  Make sure and register it to be renamed.  */
 193
 194 tree
 195 make_rename_temp (tree type, const char *prefix)
 196 {
 197   tree t = create_tmp_var (type, prefix);
 198
 199   if (TREE_CODE (type) == COMPLEX_TYPE)
 200     DECL_COMPLEX_GIMPLE_REG_P (t) = 1;
 201
 202   if (referenced_vars)
 203     {
 204       add_referenced_tmp_var (t);
 205       mark_sym_for_renaming (t);
 206     }
 207
 208   return t;
 209 }
 210
 211
 212
 213 /*---------------------------------------------------------------------------
 214                               Debugging functions
 215 ---------------------------------------------------------------------------*/
 216 /* Dump the list of all the referenced variables in the current function to
 217    FILE.  */
 218
 219 void
 220 dump_referenced_vars (FILE *file)
 221 {
 222   tree var;
 223   referenced_var_iterator rvi;
 224
 225   fprintf (file, "\nReferenced variables in %s: %u\n\n",
 226            get_name (current_function_decl), (unsigned) num_referenced_vars);
 227
 228   FOR_EACH_REFERENCED_VAR (var, rvi)
 229     {
 230       fprintf (file, "Variable: ");
 231       dump_variable (file, var);
 232       fprintf (file, "\n");
 233     }
 234 }
 235
 236
 237 /* Dump the list of all the referenced variables to stderr.  */
 238
 239 void
 240 debug_referenced_vars (void)
 241 {
 242   dump_referenced_vars (stderr);
 243 }
 244
 245
 246 /* Dump sub-variables for VAR to FILE.  */
 247
 248 void
 249 dump_subvars_for (FILE *file, tree var)
 250 {
 251   subvar_t sv = get_subvars_for_var (var);
 252
 253   if (!sv)
 254     return;
 255
 256   fprintf (file, "{ ");
 257
 258   for (; sv; sv = sv->next)
 259     {
 260       print_generic_expr (file, sv->var, dump_flags);
 261       fprintf (file, " ");
 262     }
 263
 264   fprintf (file, "}");
 265 }
 266
 267
 268 /* Dumb sub-variables for VAR to stderr.  */
 269
 270 void
 271 debug_subvars_for (tree var)
 272 {
 273   dump_subvars_for (stderr, var);
 274 }
 275
 276
 277 /* Dump variable VAR and its may-aliases to FILE.  */
 278
 279 void
 280 dump_variable (FILE *file, tree var)
 281 {
 282   var_ann_t ann;
 283
 284   if (TREE_CODE (var) == SSA_NAME)
 285     {
 286       if (POINTER_TYPE_P (TREE_TYPE (var)))
 287         dump_points_to_info_for (file, var);
 288       var = SSA_NAME_VAR (var);
 289     }
 290
 291   if (var == NULL_TREE)
 292     {
 293       fprintf (file, "<nil>");
 294       return;
 295     }
 296
 297   print_generic_expr (file, var, dump_flags);
 298
 299   ann = var_ann (var);
 300
 301   fprintf (file, ", UID %u", (unsigned) DECL_UID (var));
 302
 303   fprintf (file, ", ");
 304   print_generic_expr (file, TREE_TYPE (var), dump_flags);
 305
 306   if (ann && ann->type_mem_tag)
 307     {
 308       fprintf (file, ", type memory tag: ");
 309       print_generic_expr (file, ann->type_mem_tag, dump_flags);
 310     }
 311
 312   if (ann && ann->is_alias_tag)
 313     fprintf (file, ", is an alias tag");
 314
 315   if (TREE_ADDRESSABLE (var))
 316     fprintf (file, ", is addressable");
 317
 318   if (is_global_var (var))
 319     fprintf (file, ", is global");
 320
 321   if (TREE_THIS_VOLATILE (var))
 322     fprintf (file, ", is volatile");
 323
 324   if (is_call_clobbered (var))
 325     fprintf (file, ", call clobbered");
 326
 327   if (default_def (var))
 328     {
 329       fprintf (file, ", default def: ");
 330       print_generic_expr (file, default_def (var), dump_flags);
 331     }
 332
 333   if (may_aliases (var))
 334     {
 335       fprintf (file, ", may aliases: ");
 336       dump_may_aliases_for (file, var);
 337     }
 338
 339   if (get_subvars_for_var (var))
 340     {
 341       fprintf (file, ", sub-vars: ");
 342       dump_subvars_for (file, var);
 343     }
 344
 345   fprintf (file, "\n");
 346 }
 347
 348
 349 /* Dump variable VAR and its may-aliases to stderr.  */
 350
 351 void
 352 debug_variable (tree var)
 353 {
 354   dump_variable (stderr, var);
 355 }
 356
 357
 358 /* Dump various DFA statistics to FILE.  */
 359
 360 void
 361 dump_dfa_stats (FILE *file)
 362 {
 363   struct dfa_stats_d dfa_stats;
 364
 365   unsigned long size, total = 0;
 366   const char * const fmt_str   = "%-30s%-13s%12s\n";
 367   const char * const fmt_str_1 = "%-30s%13lu%11lu%c\n";
 368   const char * const fmt_str_3 = "%-43s%11lu%c\n";
 369   const char *funcname
 370     = lang_hooks.decl_printable_name (current_function_decl, 2);
 371
 372   collect_dfa_stats (&dfa_stats);
 373
 374   fprintf (file, "\nDFA Statistics for %s\n\n", funcname);
 375
 376   fprintf (file, "---------------------------------------------------------\n");
 377   fprintf (file, fmt_str, "", "  Number of  ", "Memory");
 378   fprintf (file, fmt_str, "", "  instances  ", "used ");
 379   fprintf (file, "---------------------------------------------------------\n");
 380
 381   size = num_referenced_vars * sizeof (tree);
 382   total += size;
 383   fprintf (file, fmt_str_1, "Referenced variables", (unsigned long)num_referenced_vars,
 384            SCALE (size), LABEL (size));
 385
 386   size = dfa_stats.num_stmt_anns * sizeof (struct stmt_ann_d);
 387   total += size;
 388   fprintf (file, fmt_str_1, "Statements annotated", dfa_stats.num_stmt_anns,
 389            SCALE (size), LABEL (size));
 390
 391   size = dfa_stats.num_var_anns * sizeof (struct var_ann_d);
 392   total += size;
 393   fprintf (file, fmt_str_1, "Variables annotated", dfa_stats.num_var_anns,
 394            SCALE (size), LABEL (size));
 395
 396   size = dfa_stats.num_uses * sizeof (tree *);
 397   total += size;
 398   fprintf (file, fmt_str_1, "USE operands", dfa_stats.num_uses,
 399            SCALE (size), LABEL (size));
 400
 401   size = dfa_stats.num_defs * sizeof (tree *);
 402   total += size;
 403   fprintf (file, fmt_str_1, "DEF operands", dfa_stats.num_defs,
 404            SCALE (size), LABEL (size));
 405
 406   size = dfa_stats.num_vuses * sizeof (tree *);
 407   total += size;
 408   fprintf (file, fmt_str_1, "VUSE operands", dfa_stats.num_vuses,
 409            SCALE (size), LABEL (size));
 410
 411   size = dfa_stats.num_v_may_defs * sizeof (tree *);
 412   total += size;
 413   fprintf (file, fmt_str_1, "V_MAY_DEF operands", dfa_stats.num_v_may_defs,
 414            SCALE (size), LABEL (size));
 415
 416   size = dfa_stats.num_v_must_defs * sizeof (tree *);
 417   total += size;
 418   fprintf (file, fmt_str_1, "V_MUST_DEF operands", dfa_stats.num_v_must_defs,
 419            SCALE (size), LABEL (size));
 420
 421   size = dfa_stats.num_phis * sizeof (struct tree_phi_node);
 422   total += size;
 423   fprintf (file, fmt_str_1, "PHI nodes", dfa_stats.num_phis,
 424            SCALE (size), LABEL (size));
 425
 426   size = dfa_stats.num_phi_args * sizeof (struct phi_arg_d);
 427   total += size;
 428   fprintf (file, fmt_str_1, "PHI arguments", dfa_stats.num_phi_args,
 429            SCALE (size), LABEL (size));
 430
 431   fprintf (file, "---------------------------------------------------------\n");
 432   fprintf (file, fmt_str_3, "Total memory used by DFA/SSA data", SCALE (total),
 433            LABEL (total));
 434   fprintf (file, "---------------------------------------------------------\n");
 435   fprintf (file, "\n");
 436
 437   if (dfa_stats.num_phis)
 438     fprintf (file, "Average number of arguments per PHI node: %.1f (max: %d)\n",
 439              (float) dfa_stats.num_phi_args / (float) dfa_stats.num_phis,
 440              dfa_stats.max_num_phi_args);
 441
 442   fprintf (file, "\n");
 443 }
 444
 445
 446 /* Dump DFA statistics on stderr.  */
 447
 448 void
 449 debug_dfa_stats (void)
 450 {
 451   dump_dfa_stats (stderr);
 452 }
 453
 454
 455 /* Collect DFA statistics and store them in the structure pointed to by
 456    DFA_STATS_P.  */
 457
 458 static void
 459 collect_dfa_stats (struct dfa_stats_d *dfa_stats_p)
 460 {
 461   struct pointer_set_t *pset;
 462   basic_block bb;
 463   block_stmt_iterator i;
 464
 465   gcc_assert (dfa_stats_p);
 466
 467   memset ((void *)dfa_stats_p, 0, sizeof (struct dfa_stats_d));
 468
 469   /* Walk all the trees in the function counting references.  Start at
 470      basic block 0, but don't stop at block boundaries.  */
 471   pset = pointer_set_create ();
 472
 473   for (i = bsi_start (BASIC_BLOCK (0)); !bsi_end_p (i); bsi_next (&i))
 474     walk_tree (bsi_stmt_ptr (i), collect_dfa_stats_r, (void *) dfa_stats_p,
 475                pset);
 476
 477   pointer_set_destroy (pset);
 478
 479   FOR_EACH_BB (bb)
 480     {
 481       tree phi;
 482       for (phi = phi_nodes (bb); phi; phi = PHI_CHAIN (phi))
 483         {
 484           dfa_stats_p->num_phis++;
 485           dfa_stats_p->num_phi_args += PHI_NUM_ARGS (phi);
 486           if (PHI_NUM_ARGS (phi) > dfa_stats_p->max_num_phi_args)
 487             dfa_stats_p->max_num_phi_args = PHI_NUM_ARGS (phi);
 488         }
 489     }
 490 }
 491
 492
 493 /* Callback for walk_tree to collect DFA statistics for a tree and its
 494    children.  */
 495
 496 static tree
 497 collect_dfa_stats_r (tree *tp, int *walk_subtrees ATTRIBUTE_UNUSED,
 498                      void *data)
 499 {
 500   tree t = *tp;
 501   struct dfa_stats_d *dfa_stats_p = (struct dfa_stats_d *)data;
 502
 503   if (t->common.ann)
 504     {
 505       switch (ann_type (t->common.ann))
 506         {
 507         case STMT_ANN:
 508           {
 509             dfa_stats_p->num_stmt_anns++;
 510             dfa_stats_p->num_defs += NUM_SSA_OPERANDS (t, SSA_OP_DEF);
 511             dfa_stats_p->num_uses += NUM_SSA_OPERANDS (t, SSA_OP_USE);
 512             dfa_stats_p->num_v_may_defs += NUM_SSA_OPERANDS (t, SSA_OP_VMAYDEF);
 513             dfa_stats_p->num_vuses += NUM_SSA_OPERANDS (t, SSA_OP_VUSE);
 514             dfa_stats_p->num_v_must_defs +=
 515                                   NUM_SSA_OPERANDS (t, SSA_OP_VMUSTDEF);
 516             break;
 517           }
 518
 519         case VAR_ANN:
 520           dfa_stats_p->num_var_anns++;
 521           break;
 522
 523         default:
 524           break;
 525         }
 526     }
 527
 528   return NULL;
 529 }
 530
 531
 532 /*---------------------------------------------------------------------------
 533                              Miscellaneous helpers
 534 ---------------------------------------------------------------------------*/
 535 /* Callback for walk_tree.  Used to collect variables referenced in
 536    the function.  */
 537
 538 static tree
 539 find_vars_r (tree *tp, int *walk_subtrees, void *data ATTRIBUTE_UNUSED)
 540 {
 541   /* If T is a regular variable that the optimizers are interested
 542      in, add it to the list of variables.  */
 543   if (SSA_VAR_P (*tp))
 544     add_referenced_var (*tp, false);
 545
 546   /* Type, _DECL and constant nodes have no interesting children.
 547      Ignore them.  */
 548   else if (IS_TYPE_OR_DECL_P (*tp) || CONSTANT_CLASS_P (*tp))
 549     *walk_subtrees = 0;
 550
 551   return NULL_TREE;
 552 }
 553
 554
 555 /* Lookup UID in the referenced_vars hashtable and return the associated
 556    variable or NULL if it is not there.  */
 557
 558 tree
 559 referenced_var_lookup_if_exists (unsigned int uid)
 560 {
 561   struct int_tree_map *h, in;
 562   in.uid = uid;
 563   h = htab_find_with_hash (referenced_vars, &in, uid);
 564   if (h)
 565     return h->to;
 566   return NULL_TREE;
 567 }
 568
 569 /* Lookup UID in the referenced_vars hashtable and return the associated
 570    variable.  */
 571
 572 tree
 573 referenced_var_lookup (unsigned int uid)
 574 {
 575   struct int_tree_map *h, in;
 576   in.uid = uid;
 577   h = htab_find_with_hash (referenced_vars, &in, uid);
 578   gcc_assert (h || uid == 0);
 579   if (h)
 580     return h->to;
 581   return NULL_TREE;
 582 }
 583
 584 /* Insert the pair UID, TO into the referenced_vars hashtable.  */
 585
 586 static void
 587 referenced_var_insert (unsigned int uid, tree to)
 588 {
 589   struct int_tree_map *h;
 590   void **loc;
 591
 592   h = ggc_alloc (sizeof (struct int_tree_map));
 593   h->uid = uid;
 594   h->to = to;
 595   loc = htab_find_slot_with_hash (referenced_vars, h, uid, INSERT);
 596   /* This assert can only trigger if a variable with the same UID has been
 597      inserted already.  */
 598   gcc_assert ((*(struct int_tree_map **)loc) == NULL);
 599   *(struct int_tree_map **)  loc = h;
 600 }
 601
 602 /* Add VAR to the list of dereferenced variables.
 603
 604    WALK_STATE contains a hash table used to avoid adding the same
 605       variable more than once. Note that this function assumes that
 606       VAR is a valid SSA variable.  If WALK_STATE is NULL, no
 607       duplicate checking is done.  */
 608
 609 static void
 610 add_referenced_var (tree var, bool always)
 611 {
 612   var_ann_t v_ann;
 613   tree ref;
 614
 615   v_ann = get_var_ann (var);
 616   gcc_assert (DECL_P (var));
 617
 618   ref = referenced_var_lookup_if_exists (DECL_UID (var));
 619
 620   /* Catch PRs 26757 and 27793.  If this assert triggers, REF and VAR are
 621      two different variables in this function with the same DECL_UID.  */
 622   gcc_assert (!ref || ref == var);
 623
 624   if (always || ref == NULL_TREE)
 625     {
 626       /* This is the first time we find this variable, add it to the
 627          REFERENCED_VARS array and annotate it with attributes that are
 628          intrinsic to the variable.  */
 629
 630       referenced_var_insert (DECL_UID (var), var);
 631
 632       /* Global variables are always call-clobbered.  */
 633       if (is_global_var (var))
 634         mark_call_clobbered (var);
 635
 636       /* Scan DECL_INITIAL for pointer variables as they may contain
 637          address arithmetic referencing the address of other
 638          variables.  */
 639       if (DECL_INITIAL (var)
 640           /* Initializers of external variables are not useful to the
 641              optimizers.  */
 642           && !DECL_EXTERNAL (var)
 643           /* It's not necessary to walk the initial value of non-constant
 644              variables because it cannot be propagated by the
 645              optimizers.  */
 646           && (TREE_CONSTANT (var) || TREE_READONLY (var)))
 647         walk_tree (&DECL_INITIAL (var), find_vars_r, NULL, 0);
 648     }
 649 }
 650
 651
 652 /* Return the virtual variable associated to the non-scalar variable VAR.  */
 653
 654 tree
 655 get_virtual_var (tree var)
 656 {
 657   STRIP_NOPS (var);
 658
 659   if (TREE_CODE (var) == SSA_NAME)
 660     var = SSA_NAME_VAR (var);
 661
 662   while (TREE_CODE (var) == REALPART_EXPR || TREE_CODE (var) == IMAGPART_EXPR
 663          || handled_component_p (var))
 664     var = TREE_OPERAND (var, 0);
 665
 666   /* Treating GIMPLE registers as virtual variables makes no sense.
 667      Also complain if we couldn't extract a _DECL out of the original
 668      expression.  */
 669   gcc_assert (SSA_VAR_P (var));
 670   gcc_assert (!is_gimple_reg (var));
 671
 672   return var;
 673 }
 674
 675 /* Add a temporary variable to REFERENCED_VARS.  This is similar to
 676    add_referenced_var, but is used by passes that need to add new temps to
 677    the REFERENCED_VARS array after the program has been scanned for
 678    variables.  The variable will just receive a new UID and be added
 679    to the REFERENCED_VARS array without checking for duplicates.  */
 680
 681 void
 682 add_referenced_tmp_var (tree var)
 683 {
 684   add_referenced_var (var, true);
 685 }
 686
 687
 688 /* Mark all the non-SSA variables found in STMT's operands to be
 689    processed by update_ssa.  */
 690
 691 void
 692 mark_new_vars_to_rename (tree stmt)
 693 {
 694   ssa_op_iter iter;
 695   tree val;
 696   bitmap vars_in_vops_to_rename;
 697   bool found_exposed_symbol = false;
 698   int v_may_defs_before, v_may_defs_after;
 699   int v_must_defs_before, v_must_defs_after;
 700
 701   if (TREE_CODE (stmt) == PHI_NODE)
 702     return;
 703
 704   vars_in_vops_to_rename = BITMAP_ALLOC (NULL);
 705
 706   /* Before re-scanning the statement for operands, mark the existing
 707      virtual operands to be renamed again.  We do this because when new
 708      symbols are exposed, the virtual operands that were here before due to
 709      aliasing will probably be removed by the call to get_stmt_operand.
 710      Therefore, we need to flag them to be renamed beforehand.
 711
 712      We flag them in a separate bitmap because we don't really want to
 713      rename them if there are not any newly exposed symbols in the
 714      statement operands.  */
 715   v_may_defs_before = NUM_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF);
 716   v_must_defs_before = NUM_SSA_OPERANDS (stmt, SSA_OP_VMUSTDEF);
 717
 718   FOR_EACH_SSA_TREE_OPERAND (val, stmt, iter,
 719                              SSA_OP_VMAYDEF | SSA_OP_VUSE | SSA_OP_VMUSTDEF)
 720     {
 721       if (!DECL_P (val))
 722         val = SSA_NAME_VAR (val);
 723       bitmap_set_bit (vars_in_vops_to_rename, DECL_UID (val));
 724     }
 725
 726   /* Now force an operand re-scan on the statement and mark any newly
 727      exposed variables.  */
 728   update_stmt (stmt);
 729
 730   v_may_defs_after = NUM_SSA_OPERANDS (stmt, SSA_OP_VMAYDEF);
 731   v_must_defs_after = NUM_SSA_OPERANDS (stmt, SSA_OP_VMUSTDEF);
 732
 733   FOR_EACH_SSA_TREE_OPERAND (val, stmt, iter, SSA_OP_ALL_OPERANDS)
 734     if (DECL_P (val))
 735       {
 736         found_exposed_symbol = true;
 737         mark_sym_for_renaming (val);
 738       }
 739
 740   /* If we found any newly exposed symbols, or if there are fewer VDEF
 741      operands in the statement, add the variables we had set in
 742      VARS_IN_VOPS_TO_RENAME to VARS_TO_RENAME.  We need to check for
 743      vanishing VDEFs because in those cases, the names that were formerly
 744      generated by this statement are not going to be available anymore.  */
 745   if (found_exposed_symbol
 746       || v_may_defs_before > v_may_defs_after
 747       || v_must_defs_before > v_must_defs_after)
 748     mark_set_for_renaming (vars_in_vops_to_rename);
 749
 750   BITMAP_FREE (vars_in_vops_to_rename);
 751 }
 752
 753 /* Find all variables within the gimplified statement that were not previously
 754    visible to the function and add them to the referenced variables list.  */
 755
 756 static tree
 757 find_new_referenced_vars_1 (tree *tp, int *walk_subtrees,
 758                             void *data ATTRIBUTE_UNUSED)
 759 {
 760   tree t = *tp;
 761
 762   if (TREE_CODE (t) == VAR_DECL && !var_ann (t))
 763     {
 764       add_referenced_tmp_var (t);
 765       mark_sym_for_renaming (t);
 766     }
 767
 768   if (IS_TYPE_OR_DECL_P (t))
 769     *walk_subtrees = 0;
 770
 771   return NULL;
 772 }
 773
 774 void
 775 find_new_referenced_vars (tree *stmt_p)
 776 {
 777   walk_tree (stmt_p, find_new_referenced_vars_1, NULL, NULL);
 778 }
 779
 780
 781 /* If REF is a COMPONENT_REF for a structure that can have sub-variables, and
 782    we know where REF is accessing, return the variable in REF that has the
 783    sub-variables.  If the return value is not NULL, POFFSET will be the
 784    offset, in bits, of REF inside the return value, and PSIZE will be the
 785    size, in bits, of REF inside the return value.  */
 786
 787 tree
 788 okay_component_ref_for_subvars (tree ref, unsigned HOST_WIDE_INT *poffset,
 789                                 unsigned HOST_WIDE_INT *psize)
 790 {
 791   tree result = NULL;
 792   HOST_WIDE_INT bitsize;
 793   HOST_WIDE_INT bitpos;
 794   tree offset;
 795   enum machine_mode mode;
 796   int unsignedp;
 797   int volatilep;
 798
 799   gcc_assert (!SSA_VAR_P (ref));
 800   *poffset = 0;
 801   *psize = (unsigned int) -1;
 802
 803   if (ref_contains_array_ref (ref))
 804     return result;
 805   ref = get_inner_reference (ref, &bitsize, &bitpos, &offset, &mode,
 806                              &unsignedp, &volatilep, false);
 807   if (TREE_CODE (ref) == INDIRECT_REF)
 808     return result;
 809   else if (offset == NULL && bitsize != -1 && SSA_VAR_P (ref))
 810     {
 811       *poffset = bitpos;
 812       *psize = bitsize;
 813       if (get_subvars_for_var (ref) != NULL)
 814         return ref;
 815     }
 816   else if (SSA_VAR_P (ref))
 817     {
 818       if (get_subvars_for_var (ref) != NULL)
 819         return ref;
 820     }
 821   return NULL_TREE;
 822 }