gcc/tree-ssanames.c

   1 /* Generic routines for manipulating SSA_NAME expressions
   2    Copyright (C) 2003-2015 Free Software Foundation, Inc.
   3
   4 This file is part of GCC.
   5
   6 GCC is free software; you can redistribute it and/or modify
   7 it under the terms of the GNU General Public License as published by
   8 the Free Software Foundation; either version 3, or (at your option)
   9 any later version.
  10
  11 GCC is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GCC; see the file COPYING3.  If not see
  18 <http://www.gnu.org/licenses/>.  */
  19
  20 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "tm.h"
  24 #include "hash-set.h"
  25 #include "machmode.h"
  26 #include "vec.h"
  27 #include "double-int.h"
  28 #include "input.h"
  29 #include "alias.h"
  30 #include "symtab.h"
  31 #include "wide-int.h"
  32 #include "inchash.h"
  33 #include "tree.h"
  34 #include "fold-const.h"
  35 #include "stor-layout.h"
  36 #include "predict.h"
  37 #include "hard-reg-set.h"
  38 #include "input.h"
  39 #include "function.h"
  40 #include "basic-block.h"
  41 #include "tree-ssa-alias.h"
  42 #include "internal-fn.h"
  43 #include "gimple-expr.h"
  44 #include "is-a.h"
  45 #include "gimple.h"
  46 #include "gimple-ssa.h"
  47 #include "tree-phinodes.h"
  48 #include "ssa-iterators.h"
  49 #include "stringpool.h"
  50 #include "tree-ssanames.h"
  51 #include "tree-into-ssa.h"
  52 #include "tree-ssa.h"
  53 #include "tree-pass.h"
  54
  55 /* Rewriting a function into SSA form can create a huge number of SSA_NAMEs,
  56    many of which may be thrown away shortly after their creation if jumps
  57    were threaded through PHI nodes.
  58
  59    While our garbage collection mechanisms will handle this situation, it
  60    is extremely wasteful to create nodes and throw them away, especially
  61    when the nodes can be reused.
  62
  63    For PR 8361, we can significantly reduce the number of nodes allocated
  64    and thus the total amount of memory allocated by managing SSA_NAMEs a
  65    little.  This additionally helps reduce the amount of work done by the
  66    garbage collector.  Similar results have been seen on a wider variety
  67    of tests (such as the compiler itself).
  68
  69    Right now we maintain our free list on a per-function basis.  It may
  70    or may not make sense to maintain the free list for the duration of
  71    a compilation unit.
  72
  73    External code should rely solely upon HIGHEST_SSA_VERSION and the
  74    externally defined functions.  External code should not know about
  75    the details of the free list management.
  76
  77    External code should also not assume the version number on nodes is
  78    monotonically increasing.  We reuse the version number when we
  79    reuse an SSA_NAME expression.  This helps keep arrays and bitmaps
  80    more compact.  */
  81
  82
  83 /* Version numbers with special meanings.  We start allocating new version
  84    numbers after the special ones.  */
  85 #define UNUSED_NAME_VERSION 0
  86
  87 unsigned int ssa_name_nodes_reused;
  88 unsigned int ssa_name_nodes_created;
  89
  90 #define FREE_SSANAMES(fun) (fun)->gimple_df->free_ssanames
  91
  92
  93 /* Initialize management of SSA_NAMEs to default SIZE.  If SIZE is
  94    zero use default.  */
  95
  96 void
  97 init_ssanames (struct function *fn, int size)
  98 {
  99   if (size < 50)
 100     size = 50;
 101
 102   vec_alloc (SSANAMES (fn), size);
 103
 104   /* Version 0 is special, so reserve the first slot in the table.  Though
 105      currently unused, we may use version 0 in alias analysis as part of
 106      the heuristics used to group aliases when the alias sets are too
 107      large.
 108
 109      We use vec::quick_push here because we know that SSA_NAMES has at
 110      least 50 elements reserved in it.  */
 111   SSANAMES (fn)->quick_push (NULL_TREE);
 112   FREE_SSANAMES (fn) = NULL;
 113
 114   fn->gimple_df->ssa_renaming_needed = 0;
 115   fn->gimple_df->rename_vops = 0;
 116 }
 117
 118 /* Finalize management of SSA_NAMEs.  */
 119
 120 void
 121 fini_ssanames (void)
 122 {
 123   vec_free (SSANAMES (cfun));
 124   vec_free (FREE_SSANAMES (cfun));
 125 }
 126
 127 /* Dump some simple statistics regarding the re-use of SSA_NAME nodes.  */
 128
 129 void
 130 ssanames_print_statistics (void)
 131 {
 132   fprintf (stderr, "SSA_NAME nodes allocated: %u\n", ssa_name_nodes_created);
 133   fprintf (stderr, "SSA_NAME nodes reused: %u\n", ssa_name_nodes_reused);
 134 }
 135
 136 /* Return an SSA_NAME node for variable VAR defined in statement STMT
 137    in function FN.  STMT may be an empty statement for artificial
 138    references (e.g., default definitions created when a variable is
 139    used without a preceding definition).  */
 140
 141 tree
 142 make_ssa_name_fn (struct function *fn, tree var, gimple stmt)
 143 {
 144   tree t;
 145   use_operand_p imm;
 146
 147   gcc_assert (TREE_CODE (var) == VAR_DECL
 148               || TREE_CODE (var) == PARM_DECL
 149               || TREE_CODE (var) == RESULT_DECL
 150               || (TYPE_P (var) && is_gimple_reg_type (var)));
 151
 152   /* If our free list has an element, then use it.  */
 153   if (!vec_safe_is_empty (FREE_SSANAMES (fn)))
 154     {
 155       t = FREE_SSANAMES (fn)->pop ();
 156       if (GATHER_STATISTICS)
 157         ssa_name_nodes_reused++;
 158
 159       /* The node was cleared out when we put it on the free list, so
 160          there is no need to do so again here.  */
 161       gcc_assert ((*SSANAMES (fn))[SSA_NAME_VERSION (t)] == NULL);
 162       (*SSANAMES (fn))[SSA_NAME_VERSION (t)] = t;
 163     }
 164   else
 165     {
 166       t = make_node (SSA_NAME);
 167       SSA_NAME_VERSION (t) = SSANAMES (fn)->length ();
 168       vec_safe_push (SSANAMES (fn), t);
 169       if (GATHER_STATISTICS)
 170         ssa_name_nodes_created++;
 171     }
 172
 173   if (TYPE_P (var))
 174     {
 175       TREE_TYPE (t) = var;
 176       SET_SSA_NAME_VAR_OR_IDENTIFIER (t, NULL_TREE);
 177     }
 178   else
 179     {
 180       TREE_TYPE (t) = TREE_TYPE (var);
 181       SET_SSA_NAME_VAR_OR_IDENTIFIER (t, var);
 182     }
 183   SSA_NAME_DEF_STMT (t) = stmt;
 184   if (POINTER_TYPE_P (TREE_TYPE (t)))
 185     SSA_NAME_PTR_INFO (t) = NULL;
 186   else
 187     SSA_NAME_RANGE_INFO (t) = NULL;
 188
 189   SSA_NAME_IN_FREE_LIST (t) = 0;
 190   SSA_NAME_IS_DEFAULT_DEF (t) = 0;
 191   imm = &(SSA_NAME_IMM_USE_NODE (t));
 192   imm->use = NULL;
 193   imm->prev = imm;
 194   imm->next = imm;
 195   imm->loc.ssa_name = t;
 196
 197   return t;
 198 }
 199
 200 /* Store range information RANGE_TYPE, MIN, and MAX to tree ssa_name NAME.  */
 201
 202 void
 203 set_range_info (tree name, enum value_range_type range_type,
 204                 const wide_int_ref &min, const wide_int_ref &max)
 205 {
 206   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 207   gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
 208   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 209   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 210
 211   /* Allocate if not available.  */
 212   if (ri == NULL)
 213     {
 214       size_t size = (sizeof (range_info_def)
 215                      + trailing_wide_ints <3>::extra_size (precision));
 216       ri = static_cast<range_info_def *> (ggc_internal_alloc (size));
 217       ri->ints.set_precision (precision);
 218       SSA_NAME_RANGE_INFO (name) = ri;
 219       ri->set_nonzero_bits (wi::shwi (-1, precision));
 220     }
 221
 222   /* Record the range type.  */
 223   if (SSA_NAME_RANGE_TYPE (name) != range_type)
 224     SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
 225
 226   /* Set the values.  */
 227   ri->set_min (min);
 228   ri->set_max (max);
 229
 230   /* If it is a range, try to improve nonzero_bits from the min/max.  */
 231   if (range_type == VR_RANGE)
 232     {
 233       wide_int xorv = ri->get_min () ^ ri->get_max ();
 234       if (xorv != 0)
 235         xorv = wi::mask (precision - wi::clz (xorv), false, precision);
 236       ri->set_nonzero_bits (ri->get_nonzero_bits () & (ri->get_min () | xorv));
 237     }
 238 }
 239
 240
 241 /* Gets range information MIN, MAX and returns enum value_range_type
 242    corresponding to tree ssa_name NAME.  enum value_range_type returned
 243    is used to determine if MIN and MAX are valid values.  */
 244
 245 enum value_range_type
 246 get_range_info (const_tree name, wide_int *min, wide_int *max)
 247 {
 248   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 249   gcc_assert (min && max);
 250   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 251
 252   /* Return VR_VARYING for SSA_NAMEs with NULL RANGE_INFO or SSA_NAMEs
 253      with integral types width > 2 * HOST_BITS_PER_WIDE_INT precision.  */
 254   if (!ri || (GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (name)))
 255               > 2 * HOST_BITS_PER_WIDE_INT))
 256     return VR_VARYING;
 257
 258   *min = ri->get_min ();
 259   *max = ri->get_max ();
 260   return SSA_NAME_RANGE_TYPE (name);
 261 }
 262
 263 /* Change non-zero bits bitmask of NAME.  */
 264
 265 void
 266 set_nonzero_bits (tree name, const wide_int_ref &mask)
 267 {
 268   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 269   if (SSA_NAME_RANGE_INFO (name) == NULL)
 270     set_range_info (name, VR_RANGE,
 271                     TYPE_MIN_VALUE (TREE_TYPE (name)),
 272                     TYPE_MAX_VALUE (TREE_TYPE (name)));
 273   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 274   ri->set_nonzero_bits (mask);
 275 }
 276
 277 /* Return a widest_int with potentially non-zero bits in SSA_NAME
 278    NAME, or -1 if unknown.  */
 279
 280 wide_int
 281 get_nonzero_bits (const_tree name)
 282 {
 283   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 284   if (POINTER_TYPE_P (TREE_TYPE (name)))
 285     {
 286       struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
 287       if (pi && pi->align)
 288         return wi::shwi (-(HOST_WIDE_INT) pi->align
 289                          | (HOST_WIDE_INT) pi->misalign, precision);
 290       return wi::shwi (-1, precision);
 291     }
 292
 293   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 294   if (!ri)
 295     return wi::shwi (-1, precision);
 296
 297   return ri->get_nonzero_bits ();
 298 }
 299
 300 /* We no longer need the SSA_NAME expression VAR, release it so that
 301    it may be reused.
 302
 303    Note it is assumed that no calls to make_ssa_name will be made
 304    until all uses of the ssa name are released and that the only
 305    use of the SSA_NAME expression is to check its SSA_NAME_VAR.  All
 306    other fields must be assumed clobbered.  */
 307
 308 void
 309 release_ssa_name_fn (struct function *fn, tree var)
 310 {
 311   if (!var)
 312     return;
 313
 314   /* Never release the default definition for a symbol.  It's a
 315      special SSA name that should always exist once it's created.  */
 316   if (SSA_NAME_IS_DEFAULT_DEF (var))
 317     return;
 318
 319   /* If VAR has been registered for SSA updating, don't remove it.
 320      After update_ssa has run, the name will be released.  */
 321   if (name_registered_for_update_p (var))
 322     {
 323       release_ssa_name_after_update_ssa (var);
 324       return;
 325     }
 326
 327   /* release_ssa_name can be called multiple times on a single SSA_NAME.
 328      However, it should only end up on our free list one time.   We
 329      keep a status bit in the SSA_NAME node itself to indicate it has
 330      been put on the free list.
 331
 332      Note that once on the freelist you can not reference the SSA_NAME's
 333      defining statement.  */
 334   if (! SSA_NAME_IN_FREE_LIST (var))
 335     {
 336       tree saved_ssa_name_var = SSA_NAME_VAR (var);
 337       int saved_ssa_name_version = SSA_NAME_VERSION (var);
 338       use_operand_p imm = &(SSA_NAME_IMM_USE_NODE (var));
 339
 340       if (MAY_HAVE_DEBUG_STMTS)
 341         insert_debug_temp_for_var_def (NULL, var);
 342
 343 #ifdef ENABLE_CHECKING
 344       verify_imm_links (stderr, var);
 345 #endif
 346       while (imm->next != imm)
 347         delink_imm_use (imm->next);
 348
 349       (*SSANAMES (fn))[SSA_NAME_VERSION (var)] = NULL_TREE;
 350       memset (var, 0, tree_size (var));
 351
 352       imm->prev = imm;
 353       imm->next = imm;
 354       imm->loc.ssa_name = var;
 355
 356       /* First put back the right tree node so that the tree checking
 357          macros do not complain.  */
 358       TREE_SET_CODE (var, SSA_NAME);
 359
 360       /* Restore the version number.  */
 361       SSA_NAME_VERSION (var) = saved_ssa_name_version;
 362
 363       /* Hopefully this can go away once we have the new incremental
 364          SSA updating code installed.  */
 365       SET_SSA_NAME_VAR_OR_IDENTIFIER (var, saved_ssa_name_var);
 366
 367       /* Note this SSA_NAME is now in the first list.  */
 368       SSA_NAME_IN_FREE_LIST (var) = 1;
 369
 370       /* And finally put it on the free list.  */
 371       vec_safe_push (FREE_SSANAMES (fn), var);
 372     }
 373 }
 374
 375 /* If the alignment of the pointer described by PI is known, return true and
 376    store the alignment and the deviation from it into *ALIGNP and *MISALIGNP
 377    respectively.  Otherwise return false.  */
 378
 379 bool
 380 get_ptr_info_alignment (struct ptr_info_def *pi, unsigned int *alignp,
 381                         unsigned int *misalignp)
 382 {
 383   if (pi->align)
 384     {
 385       *alignp = pi->align;
 386       *misalignp = pi->misalign;
 387       return true;
 388     }
 389   else
 390     return false;
 391 }
 392
 393 /* State that the pointer described by PI has unknown alignment.  */
 394
 395 void
 396 mark_ptr_info_alignment_unknown (struct ptr_info_def *pi)
 397 {
 398   pi->align = 0;
 399   pi->misalign = 0;
 400 }
 401
 402 /* Store the the power-of-two byte alignment and the deviation from that
 403    alignment of pointer described by PI to ALIOGN and MISALIGN
 404    respectively.  */
 405
 406 void
 407 set_ptr_info_alignment (struct ptr_info_def *pi, unsigned int align,
 408                             unsigned int misalign)
 409 {
 410   gcc_checking_assert (align != 0);
 411   gcc_assert ((align & (align - 1)) == 0);
 412   gcc_assert ((misalign & ~(align - 1)) == 0);
 413
 414   pi->align = align;
 415   pi->misalign = misalign;
 416 }
 417
 418 /* If pointer described by PI has known alignment, increase its known
 419    misalignment by INCREMENT modulo its current alignment.  */
 420
 421 void
 422 adjust_ptr_info_misalignment (struct ptr_info_def *pi,
 423                               unsigned int increment)
 424 {
 425   if (pi->align != 0)
 426     {
 427       pi->misalign += increment;
 428       pi->misalign &= (pi->align - 1);
 429     }
 430 }
 431
 432 /* Return the alias information associated with pointer T.  It creates a
 433    new instance if none existed.  */
 434
 435 struct ptr_info_def *
 436 get_ptr_info (tree t)
 437 {
 438   struct ptr_info_def *pi;
 439
 440   gcc_assert (POINTER_TYPE_P (TREE_TYPE (t)));
 441
 442   pi = SSA_NAME_PTR_INFO (t);
 443   if (pi == NULL)
 444     {
 445       pi = ggc_cleared_alloc<ptr_info_def> ();
 446       pt_solution_reset (&pi->pt);
 447       mark_ptr_info_alignment_unknown (pi);
 448       SSA_NAME_PTR_INFO (t) = pi;
 449     }
 450
 451   return pi;
 452 }
 453
 454
 455 /* Creates a new SSA name using the template NAME tobe defined by
 456    statement STMT in function FN.  */
 457
 458 tree
 459 copy_ssa_name_fn (struct function *fn, tree name, gimple stmt)
 460 {
 461   tree new_name;
 462
 463   if (SSA_NAME_VAR (name))
 464     new_name = make_ssa_name_fn (fn, SSA_NAME_VAR (name), stmt);
 465   else
 466     {
 467       new_name = make_ssa_name_fn (fn, TREE_TYPE (name), stmt);
 468       SET_SSA_NAME_VAR_OR_IDENTIFIER (new_name, SSA_NAME_IDENTIFIER (name));
 469     }
 470
 471   return new_name;
 472 }
 473
 474
 475 /* Creates a duplicate of the ptr_info_def at PTR_INFO for use by
 476    the SSA name NAME.  */
 477
 478 void
 479 duplicate_ssa_name_ptr_info (tree name, struct ptr_info_def *ptr_info)
 480 {
 481   struct ptr_info_def *new_ptr_info;
 482
 483   gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
 484   gcc_assert (!SSA_NAME_PTR_INFO (name));
 485
 486   if (!ptr_info)
 487     return;
 488
 489   new_ptr_info = ggc_alloc<ptr_info_def> ();
 490   *new_ptr_info = *ptr_info;
 491
 492   SSA_NAME_PTR_INFO (name) = new_ptr_info;
 493 }
 494
 495 /* Creates a duplicate of the range_info_def at RANGE_INFO of type
 496    RANGE_TYPE for use by the SSA name NAME.  */
 497 void
 498 duplicate_ssa_name_range_info (tree name, enum value_range_type range_type,
 499                                struct range_info_def *range_info)
 500 {
 501   struct range_info_def *new_range_info;
 502
 503   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 504   gcc_assert (!SSA_NAME_RANGE_INFO (name));
 505   gcc_assert (!SSA_NAME_ANTI_RANGE_P (name));
 506
 507   if (!range_info)
 508     return;
 509
 510   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 511   size_t size = (sizeof (range_info_def)
 512                  + trailing_wide_ints <3>::extra_size (precision));
 513   new_range_info = static_cast<range_info_def *> (ggc_internal_alloc (size));
 514   memcpy (new_range_info, range_info, size);
 515
 516   gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
 517   SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
 518   SSA_NAME_RANGE_INFO (name) = new_range_info;
 519 }
 520
 521
 522
 523 /* Creates a duplicate of a ssa name NAME tobe defined by statement STMT
 524    in function FN.  */
 525
 526 tree
 527 duplicate_ssa_name_fn (struct function *fn, tree name, gimple stmt)
 528 {
 529   tree new_name = copy_ssa_name_fn (fn, name, stmt);
 530   if (POINTER_TYPE_P (TREE_TYPE (name)))
 531     {
 532       struct ptr_info_def *old_ptr_info = SSA_NAME_PTR_INFO (name);
 533
 534       if (old_ptr_info)
 535         duplicate_ssa_name_ptr_info (new_name, old_ptr_info);
 536     }
 537   else
 538     {
 539       struct range_info_def *old_range_info = SSA_NAME_RANGE_INFO (name);
 540
 541       if (old_range_info)
 542         duplicate_ssa_name_range_info (new_name, SSA_NAME_RANGE_TYPE (name),
 543                                        old_range_info);
 544     }
 545
 546   return new_name;
 547 }
 548
 549
 550 /* Release all the SSA_NAMEs created by STMT.  */
 551
 552 void
 553 release_defs (gimple stmt)
 554 {
 555   tree def;
 556   ssa_op_iter iter;
 557
 558   /* Make sure that we are in SSA.  Otherwise, operand cache may point
 559      to garbage.  */
 560   gcc_assert (gimple_in_ssa_p (cfun));
 561
 562   FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
 563     if (TREE_CODE (def) == SSA_NAME)
 564       release_ssa_name (def);
 565 }
 566
 567
 568 /* Replace the symbol associated with SSA_NAME with SYM.  */
 569
 570 void
 571 replace_ssa_name_symbol (tree ssa_name, tree sym)
 572 {
 573   SET_SSA_NAME_VAR_OR_IDENTIFIER (ssa_name, sym);
 574   TREE_TYPE (ssa_name) = TREE_TYPE (sym);
 575 }
 576
 577 /* Return SSA names that are unused to GGC memory and compact the SSA
 578    version namespace.  This is used to keep footprint of compiler during
 579    interprocedural optimization.  */
 580
 581 namespace {
 582
 583 const pass_data pass_data_release_ssa_names =
 584 {
 585   GIMPLE_PASS, /* type */
 586   "release_ssa", /* name */
 587   OPTGROUP_NONE, /* optinfo_flags */
 588   TV_TREE_SSA_OTHER, /* tv_id */
 589   PROP_ssa, /* properties_required */
 590   0, /* properties_provided */
 591   0, /* properties_destroyed */
 592   TODO_remove_unused_locals, /* todo_flags_start */
 593   0, /* todo_flags_finish */
 594 };
 595
 596 class pass_release_ssa_names : public gimple_opt_pass
 597 {
 598 public:
 599   pass_release_ssa_names (gcc::context *ctxt)
 600     : gimple_opt_pass (pass_data_release_ssa_names, ctxt)
 601   {}
 602
 603   /* opt_pass methods: */
 604   virtual unsigned int execute (function *);
 605
 606 }; // class pass_release_ssa_names
 607
 608 unsigned int
 609 pass_release_ssa_names::execute (function *fun)
 610 {
 611   unsigned i, j;
 612   int n = vec_safe_length (FREE_SSANAMES (fun));
 613
 614   /* Now release the freelist.  */
 615   vec_free (FREE_SSANAMES (fun));
 616
 617   /* And compact the SSA number space.  We make sure to not change the
 618      relative order of SSA versions.  */
 619   for (i = 1, j = 1; i < fun->gimple_df->ssa_names->length (); ++i)
 620     {
 621       tree name = ssa_name (i);
 622       if (name)
 623         {
 624           if (i != j)
 625             {
 626               SSA_NAME_VERSION (name) = j;
 627               (*fun->gimple_df->ssa_names)[j] = name;
 628             }
 629           j++;
 630         }
 631     }
 632   fun->gimple_df->ssa_names->truncate (j);
 633
 634   statistics_counter_event (fun, "SSA names released", n);
 635   statistics_counter_event (fun, "SSA name holes removed", i - j);
 636   if (dump_file)
 637     fprintf (dump_file, "Released %i names, %.2f%%, removed %i holes\n",
 638              n, n * 100.0 / num_ssa_names, i - j);
 639   return 0;
 640 }
 641
 642 } // anon namespace
 643
 644 gimple_opt_pass *
 645 make_pass_release_ssa_names (gcc::context *ctxt)
 646 {
 647   return new pass_release_ssa_names (ctxt);
 648 }