gcc/tree-ssanames.c

   1 /* Generic routines for manipulating SSA_NAME expressions
   2    Copyright (C) 2003-2014 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 "tree.h"
  25 #include "stor-layout.h"
  26 #include "predict.h"
  27 #include "vec.h"
  28 #include "hashtab.h"
  29 #include "hash-set.h"
  30 #include "machmode.h"
  31 #include "hard-reg-set.h"
  32 #include "input.h"
  33 #include "function.h"
  34 #include "basic-block.h"
  35 #include "tree-ssa-alias.h"
  36 #include "internal-fn.h"
  37 #include "gimple-expr.h"
  38 #include "is-a.h"
  39 #include "gimple.h"
  40 #include "gimple-ssa.h"
  41 #include "tree-phinodes.h"
  42 #include "ssa-iterators.h"
  43 #include "stringpool.h"
  44 #include "tree-ssanames.h"
  45 #include "tree-into-ssa.h"
  46 #include "tree-ssa.h"
  47 #include "tree-pass.h"
  48
  49 /* Rewriting a function into SSA form can create a huge number of SSA_NAMEs,
  50    many of which may be thrown away shortly after their creation if jumps
  51    were threaded through PHI nodes.
  52
  53    While our garbage collection mechanisms will handle this situation, it
  54    is extremely wasteful to create nodes and throw them away, especially
  55    when the nodes can be reused.
  56
  57    For PR 8361, we can significantly reduce the number of nodes allocated
  58    and thus the total amount of memory allocated by managing SSA_NAMEs a
  59    little.  This additionally helps reduce the amount of work done by the
  60    garbage collector.  Similar results have been seen on a wider variety
  61    of tests (such as the compiler itself).
  62
  63    Right now we maintain our free list on a per-function basis.  It may
  64    or may not make sense to maintain the free list for the duration of
  65    a compilation unit.
  66
  67    External code should rely solely upon HIGHEST_SSA_VERSION and the
  68    externally defined functions.  External code should not know about
  69    the details of the free list management.
  70
  71    External code should also not assume the version number on nodes is
  72    monotonically increasing.  We reuse the version number when we
  73    reuse an SSA_NAME expression.  This helps keep arrays and bitmaps
  74    more compact.  */
  75
  76
  77 /* Version numbers with special meanings.  We start allocating new version
  78    numbers after the special ones.  */
  79 #define UNUSED_NAME_VERSION 0
  80
  81 unsigned int ssa_name_nodes_reused;
  82 unsigned int ssa_name_nodes_created;
  83
  84 #define FREE_SSANAMES(fun) (fun)->gimple_df->free_ssanames
  85
  86
  87 /* Initialize management of SSA_NAMEs to default SIZE.  If SIZE is
  88    zero use default.  */
  89
  90 void
  91 init_ssanames (struct function *fn, int size)
  92 {
  93   if (size < 50)
  94     size = 50;
  95
  96   vec_alloc (SSANAMES (fn), size);
  97
  98   /* Version 0 is special, so reserve the first slot in the table.  Though
  99      currently unused, we may use version 0 in alias analysis as part of
 100      the heuristics used to group aliases when the alias sets are too
 101      large.
 102
 103      We use vec::quick_push here because we know that SSA_NAMES has at
 104      least 50 elements reserved in it.  */
 105   SSANAMES (fn)->quick_push (NULL_TREE);
 106   FREE_SSANAMES (fn) = NULL;
 107
 108   fn->gimple_df->ssa_renaming_needed = 0;
 109   fn->gimple_df->rename_vops = 0;
 110 }
 111
 112 /* Finalize management of SSA_NAMEs.  */
 113
 114 void
 115 fini_ssanames (void)
 116 {
 117   vec_free (SSANAMES (cfun));
 118   vec_free (FREE_SSANAMES (cfun));
 119 }
 120
 121 /* Dump some simple statistics regarding the re-use of SSA_NAME nodes.  */
 122
 123 void
 124 ssanames_print_statistics (void)
 125 {
 126   fprintf (stderr, "SSA_NAME nodes allocated: %u\n", ssa_name_nodes_created);
 127   fprintf (stderr, "SSA_NAME nodes reused: %u\n", ssa_name_nodes_reused);
 128 }
 129
 130 /* Return an SSA_NAME node for variable VAR defined in statement STMT
 131    in function FN.  STMT may be an empty statement for artificial
 132    references (e.g., default definitions created when a variable is
 133    used without a preceding definition).  */
 134
 135 tree
 136 make_ssa_name_fn (struct function *fn, tree var, gimple stmt)
 137 {
 138   tree t;
 139   use_operand_p imm;
 140
 141   gcc_assert (TREE_CODE (var) == VAR_DECL
 142               || TREE_CODE (var) == PARM_DECL
 143               || TREE_CODE (var) == RESULT_DECL
 144               || (TYPE_P (var) && is_gimple_reg_type (var)));
 145
 146   /* If our free list has an element, then use it.  */
 147   if (!vec_safe_is_empty (FREE_SSANAMES (fn)))
 148     {
 149       t = FREE_SSANAMES (fn)->pop ();
 150       if (GATHER_STATISTICS)
 151         ssa_name_nodes_reused++;
 152
 153       /* The node was cleared out when we put it on the free list, so
 154          there is no need to do so again here.  */
 155       gcc_assert ((*SSANAMES (fn))[SSA_NAME_VERSION (t)] == NULL);
 156       (*SSANAMES (fn))[SSA_NAME_VERSION (t)] = t;
 157     }
 158   else
 159     {
 160       t = make_node (SSA_NAME);
 161       SSA_NAME_VERSION (t) = SSANAMES (fn)->length ();
 162       vec_safe_push (SSANAMES (fn), t);
 163       if (GATHER_STATISTICS)
 164         ssa_name_nodes_created++;
 165     }
 166
 167   if (TYPE_P (var))
 168     {
 169       TREE_TYPE (t) = var;
 170       SET_SSA_NAME_VAR_OR_IDENTIFIER (t, NULL_TREE);
 171     }
 172   else
 173     {
 174       TREE_TYPE (t) = TREE_TYPE (var);
 175       SET_SSA_NAME_VAR_OR_IDENTIFIER (t, var);
 176     }
 177   SSA_NAME_DEF_STMT (t) = stmt;
 178   if (POINTER_TYPE_P (TREE_TYPE (t)))
 179     SSA_NAME_PTR_INFO (t) = NULL;
 180   else
 181     SSA_NAME_RANGE_INFO (t) = NULL;
 182
 183   SSA_NAME_IN_FREE_LIST (t) = 0;
 184   SSA_NAME_IS_DEFAULT_DEF (t) = 0;
 185   imm = &(SSA_NAME_IMM_USE_NODE (t));
 186   imm->use = NULL;
 187   imm->prev = imm;
 188   imm->next = imm;
 189   imm->loc.ssa_name = t;
 190
 191   return t;
 192 }
 193
 194 /* Store range information RANGE_TYPE, MIN, and MAX to tree ssa_name NAME.  */
 195
 196 void
 197 set_range_info (tree name, enum value_range_type range_type,
 198                 const wide_int_ref &min, const wide_int_ref &max)
 199 {
 200   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 201   gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
 202   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 203   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 204
 205   /* Allocate if not available.  */
 206   if (ri == NULL)
 207     {
 208       size_t size = (sizeof (range_info_def)
 209                      + trailing_wide_ints <3>::extra_size (precision));
 210       ri = static_cast<range_info_def *> (ggc_internal_alloc (size));
 211       ri->ints.set_precision (precision);
 212       SSA_NAME_RANGE_INFO (name) = ri;
 213       ri->set_nonzero_bits (wi::shwi (-1, precision));
 214     }
 215
 216   /* Record the range type.  */
 217   if (SSA_NAME_RANGE_TYPE (name) != range_type)
 218     SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
 219
 220   /* Set the values.  */
 221   ri->set_min (min);
 222   ri->set_max (max);
 223
 224   /* If it is a range, try to improve nonzero_bits from the min/max.  */
 225   if (range_type == VR_RANGE)
 226     {
 227       wide_int xorv = ri->get_min () ^ ri->get_max ();
 228       if (xorv != 0)
 229         xorv = wi::mask (precision - wi::clz (xorv), false, precision);
 230       ri->set_nonzero_bits (ri->get_nonzero_bits () & (ri->get_min () | xorv));
 231     }
 232 }
 233
 234
 235 /* Gets range information MIN, MAX and returns enum value_range_type
 236    corresponding to tree ssa_name NAME.  enum value_range_type returned
 237    is used to determine if MIN and MAX are valid values.  */
 238
 239 enum value_range_type
 240 get_range_info (const_tree name, wide_int *min, wide_int *max)
 241 {
 242   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 243   gcc_assert (min && max);
 244   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 245
 246   /* Return VR_VARYING for SSA_NAMEs with NULL RANGE_INFO or SSA_NAMEs
 247      with integral types width > 2 * HOST_BITS_PER_WIDE_INT precision.  */
 248   if (!ri || (GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (name)))
 249               > 2 * HOST_BITS_PER_WIDE_INT))
 250     return VR_VARYING;
 251
 252   *min = ri->get_min ();
 253   *max = ri->get_max ();
 254   return SSA_NAME_RANGE_TYPE (name);
 255 }
 256
 257 /* Change non-zero bits bitmask of NAME.  */
 258
 259 void
 260 set_nonzero_bits (tree name, const wide_int_ref &mask)
 261 {
 262   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 263   if (SSA_NAME_RANGE_INFO (name) == NULL)
 264     set_range_info (name, VR_RANGE,
 265                     TYPE_MIN_VALUE (TREE_TYPE (name)),
 266                     TYPE_MAX_VALUE (TREE_TYPE (name)));
 267   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 268   ri->set_nonzero_bits (mask);
 269 }
 270
 271 /* Return a widest_int with potentially non-zero bits in SSA_NAME
 272    NAME, or -1 if unknown.  */
 273
 274 wide_int
 275 get_nonzero_bits (const_tree name)
 276 {
 277   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 278   if (POINTER_TYPE_P (TREE_TYPE (name)))
 279     {
 280       struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
 281       if (pi && pi->align)
 282         return wi::shwi (-(HOST_WIDE_INT) pi->align
 283                          | (HOST_WIDE_INT) pi->misalign, precision);
 284       return wi::shwi (-1, precision);
 285     }
 286
 287   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 288   if (!ri)
 289     return wi::shwi (-1, precision);
 290
 291   return ri->get_nonzero_bits ();
 292 }
 293
 294 /* We no longer need the SSA_NAME expression VAR, release it so that
 295    it may be reused.
 296
 297    Note it is assumed that no calls to make_ssa_name will be made
 298    until all uses of the ssa name are released and that the only
 299    use of the SSA_NAME expression is to check its SSA_NAME_VAR.  All
 300    other fields must be assumed clobbered.  */
 301
 302 void
 303 release_ssa_name_fn (struct function *fn, tree var)
 304 {
 305   if (!var)
 306     return;
 307
 308   /* Never release the default definition for a symbol.  It's a
 309      special SSA name that should always exist once it's created.  */
 310   if (SSA_NAME_IS_DEFAULT_DEF (var))
 311     return;
 312
 313   /* If VAR has been registered for SSA updating, don't remove it.
 314      After update_ssa has run, the name will be released.  */
 315   if (name_registered_for_update_p (var))
 316     {
 317       release_ssa_name_after_update_ssa (var);
 318       return;
 319     }
 320
 321   /* release_ssa_name can be called multiple times on a single SSA_NAME.
 322      However, it should only end up on our free list one time.   We
 323      keep a status bit in the SSA_NAME node itself to indicate it has
 324      been put on the free list.
 325
 326      Note that once on the freelist you can not reference the SSA_NAME's
 327      defining statement.  */
 328   if (! SSA_NAME_IN_FREE_LIST (var))
 329     {
 330       tree saved_ssa_name_var = SSA_NAME_VAR (var);
 331       int saved_ssa_name_version = SSA_NAME_VERSION (var);
 332       use_operand_p imm = &(SSA_NAME_IMM_USE_NODE (var));
 333
 334       if (MAY_HAVE_DEBUG_STMTS)
 335         insert_debug_temp_for_var_def (NULL, var);
 336
 337 #ifdef ENABLE_CHECKING
 338       verify_imm_links (stderr, var);
 339 #endif
 340       while (imm->next != imm)
 341         delink_imm_use (imm->next);
 342
 343       (*SSANAMES (fn))[SSA_NAME_VERSION (var)] = NULL_TREE;
 344       memset (var, 0, tree_size (var));
 345
 346       imm->prev = imm;
 347       imm->next = imm;
 348       imm->loc.ssa_name = var;
 349
 350       /* First put back the right tree node so that the tree checking
 351          macros do not complain.  */
 352       TREE_SET_CODE (var, SSA_NAME);
 353
 354       /* Restore the version number.  */
 355       SSA_NAME_VERSION (var) = saved_ssa_name_version;
 356
 357       /* Hopefully this can go away once we have the new incremental
 358          SSA updating code installed.  */
 359       SET_SSA_NAME_VAR_OR_IDENTIFIER (var, saved_ssa_name_var);
 360
 361       /* Note this SSA_NAME is now in the first list.  */
 362       SSA_NAME_IN_FREE_LIST (var) = 1;
 363
 364       /* And finally put it on the free list.  */
 365       vec_safe_push (FREE_SSANAMES (fn), var);
 366     }
 367 }
 368
 369 /* If the alignment of the pointer described by PI is known, return true and
 370    store the alignment and the deviation from it into *ALIGNP and *MISALIGNP
 371    respectively.  Otherwise return false.  */
 372
 373 bool
 374 get_ptr_info_alignment (struct ptr_info_def *pi, unsigned int *alignp,
 375                         unsigned int *misalignp)
 376 {
 377   if (pi->align)
 378     {
 379       *alignp = pi->align;
 380       *misalignp = pi->misalign;
 381       return true;
 382     }
 383   else
 384     return false;
 385 }
 386
 387 /* State that the pointer described by PI has unknown alignment.  */
 388
 389 void
 390 mark_ptr_info_alignment_unknown (struct ptr_info_def *pi)
 391 {
 392   pi->align = 0;
 393   pi->misalign = 0;
 394 }
 395
 396 /* Store the the power-of-two byte alignment and the deviation from that
 397    alignment of pointer described by PI to ALIOGN and MISALIGN
 398    respectively.  */
 399
 400 void
 401 set_ptr_info_alignment (struct ptr_info_def *pi, unsigned int align,
 402                             unsigned int misalign)
 403 {
 404   gcc_checking_assert (align != 0);
 405   gcc_assert ((align & (align - 1)) == 0);
 406   gcc_assert ((misalign & ~(align - 1)) == 0);
 407
 408   pi->align = align;
 409   pi->misalign = misalign;
 410 }
 411
 412 /* If pointer described by PI has known alignment, increase its known
 413    misalignment by INCREMENT modulo its current alignment.  */
 414
 415 void
 416 adjust_ptr_info_misalignment (struct ptr_info_def *pi,
 417                               unsigned int increment)
 418 {
 419   if (pi->align != 0)
 420     {
 421       pi->misalign += increment;
 422       pi->misalign &= (pi->align - 1);
 423     }
 424 }
 425
 426 /* Return the alias information associated with pointer T.  It creates a
 427    new instance if none existed.  */
 428
 429 struct ptr_info_def *
 430 get_ptr_info (tree t)
 431 {
 432   struct ptr_info_def *pi;
 433
 434   gcc_assert (POINTER_TYPE_P (TREE_TYPE (t)));
 435
 436   pi = SSA_NAME_PTR_INFO (t);
 437   if (pi == NULL)
 438     {
 439       pi = ggc_cleared_alloc<ptr_info_def> ();
 440       pt_solution_reset (&pi->pt);
 441       mark_ptr_info_alignment_unknown (pi);
 442       SSA_NAME_PTR_INFO (t) = pi;
 443     }
 444
 445   return pi;
 446 }
 447
 448
 449 /* Creates a new SSA name using the template NAME tobe defined by
 450    statement STMT in function FN.  */
 451
 452 tree
 453 copy_ssa_name_fn (struct function *fn, tree name, gimple stmt)
 454 {
 455   tree new_name;
 456
 457   if (SSA_NAME_VAR (name))
 458     new_name = make_ssa_name_fn (fn, SSA_NAME_VAR (name), stmt);
 459   else
 460     {
 461       new_name = make_ssa_name_fn (fn, TREE_TYPE (name), stmt);
 462       SET_SSA_NAME_VAR_OR_IDENTIFIER (new_name, SSA_NAME_IDENTIFIER (name));
 463     }
 464
 465   return new_name;
 466 }
 467
 468
 469 /* Creates a duplicate of the ptr_info_def at PTR_INFO for use by
 470    the SSA name NAME.  */
 471
 472 void
 473 duplicate_ssa_name_ptr_info (tree name, struct ptr_info_def *ptr_info)
 474 {
 475   struct ptr_info_def *new_ptr_info;
 476
 477   gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
 478   gcc_assert (!SSA_NAME_PTR_INFO (name));
 479
 480   if (!ptr_info)
 481     return;
 482
 483   new_ptr_info = ggc_alloc<ptr_info_def> ();
 484   *new_ptr_info = *ptr_info;
 485
 486   SSA_NAME_PTR_INFO (name) = new_ptr_info;
 487 }
 488
 489 /* Creates a duplicate of the range_info_def at RANGE_INFO of type
 490    RANGE_TYPE for use by the SSA name NAME.  */
 491 void
 492 duplicate_ssa_name_range_info (tree name, enum value_range_type range_type,
 493                                struct range_info_def *range_info)
 494 {
 495   struct range_info_def *new_range_info;
 496
 497   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 498   gcc_assert (!SSA_NAME_RANGE_INFO (name));
 499   gcc_assert (!SSA_NAME_ANTI_RANGE_P (name));
 500
 501   if (!range_info)
 502     return;
 503
 504   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 505   size_t size = (sizeof (range_info_def)
 506                  + trailing_wide_ints <3>::extra_size (precision));
 507   new_range_info = static_cast<range_info_def *> (ggc_internal_alloc (size));
 508   memcpy (new_range_info, range_info, size);
 509
 510   gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
 511   SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
 512   SSA_NAME_RANGE_INFO (name) = new_range_info;
 513 }
 514
 515
 516
 517 /* Creates a duplicate of a ssa name NAME tobe defined by statement STMT
 518    in function FN.  */
 519
 520 tree
 521 duplicate_ssa_name_fn (struct function *fn, tree name, gimple stmt)
 522 {
 523   tree new_name = copy_ssa_name_fn (fn, name, stmt);
 524   if (POINTER_TYPE_P (TREE_TYPE (name)))
 525     {
 526       struct ptr_info_def *old_ptr_info = SSA_NAME_PTR_INFO (name);
 527
 528       if (old_ptr_info)
 529         duplicate_ssa_name_ptr_info (new_name, old_ptr_info);
 530     }
 531   else
 532     {
 533       struct range_info_def *old_range_info = SSA_NAME_RANGE_INFO (name);
 534
 535       if (old_range_info)
 536         duplicate_ssa_name_range_info (new_name, SSA_NAME_RANGE_TYPE (name),
 537                                        old_range_info);
 538     }
 539
 540   return new_name;
 541 }
 542
 543
 544 /* Release all the SSA_NAMEs created by STMT.  */
 545
 546 void
 547 release_defs (gimple stmt)
 548 {
 549   tree def;
 550   ssa_op_iter iter;
 551
 552   /* Make sure that we are in SSA.  Otherwise, operand cache may point
 553      to garbage.  */
 554   gcc_assert (gimple_in_ssa_p (cfun));
 555
 556   FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
 557     if (TREE_CODE (def) == SSA_NAME)
 558       release_ssa_name (def);
 559 }
 560
 561
 562 /* Replace the symbol associated with SSA_NAME with SYM.  */
 563
 564 void
 565 replace_ssa_name_symbol (tree ssa_name, tree sym)
 566 {
 567   SET_SSA_NAME_VAR_OR_IDENTIFIER (ssa_name, sym);
 568   TREE_TYPE (ssa_name) = TREE_TYPE (sym);
 569 }
 570
 571 /* Return SSA names that are unused to GGC memory and compact the SSA
 572    version namespace.  This is used to keep footprint of compiler during
 573    interprocedural optimization.  */
 574
 575 namespace {
 576
 577 const pass_data pass_data_release_ssa_names =
 578 {
 579   GIMPLE_PASS, /* type */
 580   "release_ssa", /* name */
 581   OPTGROUP_NONE, /* optinfo_flags */
 582   TV_TREE_SSA_OTHER, /* tv_id */
 583   PROP_ssa, /* properties_required */
 584   0, /* properties_provided */
 585   0, /* properties_destroyed */
 586   TODO_remove_unused_locals, /* todo_flags_start */
 587   0, /* todo_flags_finish */
 588 };
 589
 590 class pass_release_ssa_names : public gimple_opt_pass
 591 {
 592 public:
 593   pass_release_ssa_names (gcc::context *ctxt)
 594     : gimple_opt_pass (pass_data_release_ssa_names, ctxt)
 595   {}
 596
 597   /* opt_pass methods: */
 598   virtual unsigned int execute (function *);
 599
 600 }; // class pass_release_ssa_names
 601
 602 unsigned int
 603 pass_release_ssa_names::execute (function *fun)
 604 {
 605   unsigned i, j;
 606   int n = vec_safe_length (FREE_SSANAMES (fun));
 607
 608   /* Now release the freelist.  */
 609   vec_free (FREE_SSANAMES (fun));
 610
 611   /* And compact the SSA number space.  We make sure to not change the
 612      relative order of SSA versions.  */
 613   for (i = 1, j = 1; i < fun->gimple_df->ssa_names->length (); ++i)
 614     {
 615       tree name = ssa_name (i);
 616       if (name)
 617         {
 618           if (i != j)
 619             {
 620               SSA_NAME_VERSION (name) = j;
 621               (*fun->gimple_df->ssa_names)[j] = name;
 622             }
 623           j++;
 624         }
 625     }
 626   fun->gimple_df->ssa_names->truncate (j);
 627
 628   statistics_counter_event (fun, "SSA names released", n);
 629   statistics_counter_event (fun, "SSA name holes removed", i - j);
 630   if (dump_file)
 631     fprintf (dump_file, "Released %i names, %.2f%%, removed %i holes\n",
 632              n, n * 100.0 / num_ssa_names, i - j);
 633   return 0;
 634 }
 635
 636 } // anon namespace
 637
 638 gimple_opt_pass *
 639 make_pass_release_ssa_names (gcc::context *ctxt)
 640 {
 641   return new pass_release_ssa_names (ctxt);
 642 }