gcc/tree-ssanames.c

   1 /* Generic routines for manipulating SSA_NAME expressions
   2    Copyright (C) 2003-2017 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 "backend.h"
  24 #include "tree.h"
  25 #include "gimple.h"
  26 #include "tree-pass.h"
  27 #include "ssa.h"
  28 #include "gimple-iterator.h"
  29 #include "stor-layout.h"
  30 #include "tree-into-ssa.h"
  31 #include "tree-ssa.h"
  32
  33 /* Rewriting a function into SSA form can create a huge number of SSA_NAMEs,
  34    many of which may be thrown away shortly after their creation if jumps
  35    were threaded through PHI nodes.
  36
  37    While our garbage collection mechanisms will handle this situation, it
  38    is extremely wasteful to create nodes and throw them away, especially
  39    when the nodes can be reused.
  40
  41    For PR 8361, we can significantly reduce the number of nodes allocated
  42    and thus the total amount of memory allocated by managing SSA_NAMEs a
  43    little.  This additionally helps reduce the amount of work done by the
  44    garbage collector.  Similar results have been seen on a wider variety
  45    of tests (such as the compiler itself).
  46
  47    Right now we maintain our free list on a per-function basis.  It may
  48    or may not make sense to maintain the free list for the duration of
  49    a compilation unit.
  50
  51    External code should rely solely upon HIGHEST_SSA_VERSION and the
  52    externally defined functions.  External code should not know about
  53    the details of the free list management.
  54
  55    External code should also not assume the version number on nodes is
  56    monotonically increasing.  We reuse the version number when we
  57    reuse an SSA_NAME expression.  This helps keep arrays and bitmaps
  58    more compact.  */
  59
  60
  61 /* Version numbers with special meanings.  We start allocating new version
  62    numbers after the special ones.  */
  63 #define UNUSED_NAME_VERSION 0
  64
  65 unsigned int ssa_name_nodes_reused;
  66 unsigned int ssa_name_nodes_created;
  67
  68 #define FREE_SSANAMES(fun) (fun)->gimple_df->free_ssanames
  69 #define FREE_SSANAMES_QUEUE(fun) (fun)->gimple_df->free_ssanames_queue
  70
  71
  72 /* Initialize management of SSA_NAMEs to default SIZE.  If SIZE is
  73    zero use default.  */
  74
  75 void
  76 init_ssanames (struct function *fn, int size)
  77 {
  78   if (size < 50)
  79     size = 50;
  80
  81   vec_alloc (SSANAMES (fn), size);
  82
  83   /* Version 0 is special, so reserve the first slot in the table.  Though
  84      currently unused, we may use version 0 in alias analysis as part of
  85      the heuristics used to group aliases when the alias sets are too
  86      large.
  87
  88      We use vec::quick_push here because we know that SSA_NAMES has at
  89      least 50 elements reserved in it.  */
  90   SSANAMES (fn)->quick_push (NULL_TREE);
  91   FREE_SSANAMES (fn) = NULL;
  92   FREE_SSANAMES_QUEUE (fn) = NULL;
  93
  94   fn->gimple_df->ssa_renaming_needed = 0;
  95   fn->gimple_df->rename_vops = 0;
  96 }
  97
  98 /* Finalize management of SSA_NAMEs.  */
  99
 100 void
 101 fini_ssanames (struct function *fn)
 102 {
 103   vec_free (SSANAMES (fn));
 104   vec_free (FREE_SSANAMES (fn));
 105   vec_free (FREE_SSANAMES_QUEUE (fn));
 106 }
 107
 108 /* Dump some simple statistics regarding the re-use of SSA_NAME nodes.  */
 109
 110 void
 111 ssanames_print_statistics (void)
 112 {
 113   fprintf (stderr, "SSA_NAME nodes allocated: %u\n", ssa_name_nodes_created);
 114   fprintf (stderr, "SSA_NAME nodes reused: %u\n", ssa_name_nodes_reused);
 115 }
 116
 117 /* Verify the state of the SSA_NAME lists.
 118
 119    There must be no duplicates on the free list.
 120    Every name on the free list must be marked as on the free list.
 121    Any name on the free list must not appear in the IL.
 122    No names can be leaked.  */
 123
 124 DEBUG_FUNCTION void
 125 verify_ssaname_freelists (struct function *fun)
 126 {
 127   if (!gimple_in_ssa_p (fun))
 128     return;
 129
 130   auto_bitmap names_in_il;
 131
 132   /* Walk the entire IL noting every SSA_NAME we see.  */
 133   basic_block bb;
 134   FOR_EACH_BB_FN (bb, fun)
 135     {
 136       tree t;
 137       /* First note the result and arguments of PHI nodes.  */
 138       for (gphi_iterator gsi = gsi_start_phis (bb);
 139            !gsi_end_p (gsi);
 140            gsi_next (&gsi))
 141         {
 142           gphi *phi = gsi.phi ();
 143           t = gimple_phi_result (phi);
 144           bitmap_set_bit (names_in_il, SSA_NAME_VERSION (t));
 145
 146           for (unsigned int i = 0; i < gimple_phi_num_args (phi); i++)
 147             {
 148               t = gimple_phi_arg_def (phi, i);
 149               if (TREE_CODE (t) == SSA_NAME)
 150                 bitmap_set_bit (names_in_il, SSA_NAME_VERSION (t));
 151             }
 152         }
 153
 154       /* Then note the operands of each statement.  */
 155       for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
 156            !gsi_end_p (gsi);
 157            gsi_next (&gsi))
 158         {
 159           ssa_op_iter iter;
 160           gimple *stmt = gsi_stmt (gsi);
 161           FOR_EACH_SSA_TREE_OPERAND (t, stmt, iter, SSA_OP_ALL_OPERANDS)
 162             bitmap_set_bit (names_in_il, SSA_NAME_VERSION (t));
 163         }
 164     }
 165
 166   /* Now walk the free list noting what we find there and verifying
 167      there are no duplicates.  */
 168   auto_bitmap names_in_freelists;
 169   if (FREE_SSANAMES (fun))
 170     {
 171       for (unsigned int i = 0; i < FREE_SSANAMES (fun)->length (); i++)
 172         {
 173           tree t = (*FREE_SSANAMES (fun))[i];
 174
 175           /* Verify that the name is marked as being in the free list.  */
 176           gcc_assert (SSA_NAME_IN_FREE_LIST (t));
 177
 178           /* Verify the name has not already appeared in the free list and
 179              note it in the list of names found in the free list.  */
 180           gcc_assert (!bitmap_bit_p (names_in_freelists, SSA_NAME_VERSION (t)));
 181           bitmap_set_bit (names_in_freelists, SSA_NAME_VERSION (t));
 182         }
 183     }
 184
 185   /* Similarly for the names in the pending free list.  */
 186   if (FREE_SSANAMES_QUEUE (fun))
 187     {
 188       for (unsigned int i = 0; i < FREE_SSANAMES_QUEUE (fun)->length (); i++)
 189         {
 190           tree t = (*FREE_SSANAMES_QUEUE (fun))[i];
 191
 192           /* Verify that the name is marked as being in the free list.  */
 193           gcc_assert (SSA_NAME_IN_FREE_LIST (t));
 194
 195           /* Verify the name has not already appeared in the free list and
 196              note it in the list of names found in the free list.  */
 197           gcc_assert (!bitmap_bit_p (names_in_freelists, SSA_NAME_VERSION (t)));
 198           bitmap_set_bit (names_in_freelists, SSA_NAME_VERSION (t));
 199         }
 200     }
 201
 202   /* If any name appears in both the IL and the freelists, then
 203      something horrible has happened.  */
 204   bool intersect_p = bitmap_intersect_p (names_in_il, names_in_freelists);
 205   gcc_assert (!intersect_p);
 206
 207   /* Names can be queued up for release if there is an ssa update
 208      pending.  Pretend we saw them in the IL.  */
 209   if (names_to_release)
 210     bitmap_ior_into (names_in_il, names_to_release);
 211
 212   /* Function splitting can "lose" SSA_NAMEs in an effort to ensure that
 213      debug/non-debug compilations have the same SSA_NAMEs.  So for each
 214      lost SSA_NAME, see if it's likely one from that wart.  These will always
 215      be marked as default definitions.  So we loosely assume that anything
 216      marked as a default definition isn't leaked by pretending they are
 217      in the IL.  */
 218   for (unsigned int i = UNUSED_NAME_VERSION + 1; i < num_ssa_names; i++)
 219     if (ssa_name (i) && SSA_NAME_IS_DEFAULT_DEF (ssa_name (i)))
 220       bitmap_set_bit (names_in_il, i);
 221
 222   unsigned int i;
 223   bitmap_iterator bi;
 224   auto_bitmap all_names;
 225   bitmap_set_range (all_names, UNUSED_NAME_VERSION + 1, num_ssa_names - 1);
 226   bitmap_ior_into (names_in_il, names_in_freelists);
 227
 228   /* Any name not mentioned in the IL and not in the feelists
 229      has been leaked.  */
 230   EXECUTE_IF_AND_COMPL_IN_BITMAP(all_names, names_in_il,
 231                                  UNUSED_NAME_VERSION + 1, i, bi)
 232     gcc_assert (!ssa_name (i));
 233 }
 234
 235 /* Move all SSA_NAMEs from FREE_SSA_NAMES_QUEUE to FREE_SSA_NAMES.
 236
 237    We do not, but should have a mode to verify the state of the SSA_NAMEs
 238    lists.  In particular at this point every name must be in the IL,
 239    on the free list or in the queue.  Anything else is an error.  */
 240
 241 void
 242 flush_ssaname_freelist (void)
 243 {
 244   vec_safe_splice (FREE_SSANAMES (cfun), FREE_SSANAMES_QUEUE (cfun));
 245   vec_safe_truncate (FREE_SSANAMES_QUEUE (cfun), 0);
 246 }
 247
 248 /* Return an SSA_NAME node for variable VAR defined in statement STMT
 249    in function FN.  STMT may be an empty statement for artificial
 250    references (e.g., default definitions created when a variable is
 251    used without a preceding definition).  If VERISON is not zero then
 252    allocate the SSA name with that version.  */
 253
 254 tree
 255 make_ssa_name_fn (struct function *fn, tree var, gimple *stmt,
 256                   unsigned int version)
 257 {
 258   tree t;
 259   use_operand_p imm;
 260
 261   gcc_assert (VAR_P (var)
 262               || TREE_CODE (var) == PARM_DECL
 263               || TREE_CODE (var) == RESULT_DECL
 264               || (TYPE_P (var) && is_gimple_reg_type (var)));
 265
 266   /* Get the specified SSA name version.  */
 267   if (version != 0)
 268     {
 269       t = make_node (SSA_NAME);
 270       SSA_NAME_VERSION (t) = version;
 271       if (version >= SSANAMES (fn)->length ())
 272         vec_safe_grow_cleared (SSANAMES (fn), version + 1);
 273       gcc_assert ((*SSANAMES (fn))[version] == NULL);
 274       (*SSANAMES (fn))[version] = t;
 275       ssa_name_nodes_created++;
 276     }
 277   /* If our free list has an element, then use it.  */
 278   else if (!vec_safe_is_empty (FREE_SSANAMES (fn)))
 279     {
 280       t = FREE_SSANAMES (fn)->pop ();
 281       ssa_name_nodes_reused++;
 282
 283       /* The node was cleared out when we put it on the free list, so
 284          there is no need to do so again here.  */
 285       gcc_assert ((*SSANAMES (fn))[SSA_NAME_VERSION (t)] == NULL);
 286       (*SSANAMES (fn))[SSA_NAME_VERSION (t)] = t;
 287     }
 288   else
 289     {
 290       t = make_node (SSA_NAME);
 291       SSA_NAME_VERSION (t) = SSANAMES (fn)->length ();
 292       vec_safe_push (SSANAMES (fn), t);
 293       ssa_name_nodes_created++;
 294     }
 295
 296   if (TYPE_P (var))
 297     {
 298       TREE_TYPE (t) = TYPE_MAIN_VARIANT (var);
 299       SET_SSA_NAME_VAR_OR_IDENTIFIER (t, NULL_TREE);
 300     }
 301   else
 302     {
 303       TREE_TYPE (t) = TREE_TYPE (var);
 304       SET_SSA_NAME_VAR_OR_IDENTIFIER (t, var);
 305     }
 306   SSA_NAME_DEF_STMT (t) = stmt;
 307   if (POINTER_TYPE_P (TREE_TYPE (t)))
 308     SSA_NAME_PTR_INFO (t) = NULL;
 309   else
 310     SSA_NAME_RANGE_INFO (t) = NULL;
 311
 312   SSA_NAME_IN_FREE_LIST (t) = 0;
 313   SSA_NAME_IS_DEFAULT_DEF (t) = 0;
 314   imm = &(SSA_NAME_IMM_USE_NODE (t));
 315   imm->use = NULL;
 316   imm->prev = imm;
 317   imm->next = imm;
 318   imm->loc.ssa_name = t;
 319
 320   return t;
 321 }
 322
 323 /* Helper function for set_range_info.
 324
 325    Store range information RANGE_TYPE, MIN, and MAX to tree ssa_name
 326    NAME.  */
 327
 328 void
 329 set_range_info_raw (tree name, enum value_range_type range_type,
 330                     const wide_int_ref &min, const wide_int_ref &max)
 331 {
 332   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 333   gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
 334   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 335   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 336
 337   /* Allocate if not available.  */
 338   if (ri == NULL)
 339     {
 340       size_t size = (sizeof (range_info_def)
 341                      + trailing_wide_ints <3>::extra_size (precision));
 342       ri = static_cast<range_info_def *> (ggc_internal_alloc (size));
 343       ri->ints.set_precision (precision);
 344       SSA_NAME_RANGE_INFO (name) = ri;
 345       ri->set_nonzero_bits (wi::shwi (-1, precision));
 346     }
 347
 348   /* Record the range type.  */
 349   if (SSA_NAME_RANGE_TYPE (name) != range_type)
 350     SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
 351
 352   /* Set the values.  */
 353   ri->set_min (min);
 354   ri->set_max (max);
 355
 356   /* If it is a range, try to improve nonzero_bits from the min/max.  */
 357   if (range_type == VR_RANGE)
 358     {
 359       wide_int xorv = ri->get_min () ^ ri->get_max ();
 360       if (xorv != 0)
 361         xorv = wi::mask (precision - wi::clz (xorv), false, precision);
 362       ri->set_nonzero_bits (ri->get_nonzero_bits () & (ri->get_min () | xorv));
 363     }
 364 }
 365
 366 /* Store range information RANGE_TYPE, MIN, and MAX to tree ssa_name
 367    NAME while making sure we don't store useless range info.  */
 368
 369 void
 370 set_range_info (tree name, enum value_range_type range_type,
 371                 const wide_int_ref &min, const wide_int_ref &max)
 372 {
 373   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 374
 375   /* A range of the entire domain is really no range at all.  */
 376   tree type = TREE_TYPE (name);
 377   if (min == wi::min_value (TYPE_PRECISION (type), TYPE_SIGN (type))
 378       && max == wi::max_value (TYPE_PRECISION (type), TYPE_SIGN (type)))
 379     {
 380       range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 381       if (ri == NULL)
 382         return;
 383       if (ri->get_nonzero_bits () == -1)
 384         {
 385           ggc_free (ri);
 386           SSA_NAME_RANGE_INFO (name) = NULL;
 387           return;
 388         }
 389     }
 390
 391   set_range_info_raw (name, range_type, min, max);
 392 }
 393
 394
 395 /* Gets range information MIN, MAX and returns enum value_range_type
 396    corresponding to tree ssa_name NAME.  enum value_range_type returned
 397    is used to determine if MIN and MAX are valid values.  */
 398
 399 enum value_range_type
 400 get_range_info (const_tree name, wide_int *min, wide_int *max)
 401 {
 402   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 403   gcc_assert (min && max);
 404   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 405
 406   /* Return VR_VARYING for SSA_NAMEs with NULL RANGE_INFO or SSA_NAMEs
 407      with integral types width > 2 * HOST_BITS_PER_WIDE_INT precision.  */
 408   if (!ri || (GET_MODE_PRECISION (SCALAR_INT_TYPE_MODE (TREE_TYPE (name)))
 409               > 2 * HOST_BITS_PER_WIDE_INT))
 410     return VR_VARYING;
 411
 412   *min = ri->get_min ();
 413   *max = ri->get_max ();
 414   return SSA_NAME_RANGE_TYPE (name);
 415 }
 416
 417 /* Set nonnull attribute to pointer NAME.  */
 418
 419 void
 420 set_ptr_nonnull (tree name)
 421 {
 422   gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
 423   struct ptr_info_def *pi = get_ptr_info (name);
 424   pi->pt.null = 0;
 425 }
 426
 427 /* Return nonnull attribute of pointer NAME.  */
 428 bool
 429 get_ptr_nonnull (const_tree name)
 430 {
 431   gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
 432   struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
 433   if (pi == NULL)
 434     return false;
 435   /* TODO Now pt->null is conservatively set to true in PTA
 436      analysis. vrp is the only pass (including ipa-vrp)
 437      that clears pt.null via set_ptr_nonull when it knows
 438      for sure. PTA will preserves the pt.null value set by VRP.
 439
 440      When PTA analysis is improved, pt.anything, pt.nonlocal
 441      and pt.escaped may also has to be considered before
 442      deciding that pointer cannot point to NULL.  */
 443   return !pi->pt.null;
 444 }
 445
 446 /* Change non-zero bits bitmask of NAME.  */
 447
 448 void
 449 set_nonzero_bits (tree name, const wide_int_ref &mask)
 450 {
 451   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 452   if (SSA_NAME_RANGE_INFO (name) == NULL)
 453     {
 454       if (mask == -1)
 455         return;
 456       set_range_info_raw (name, VR_RANGE,
 457                           wi::to_wide (TYPE_MIN_VALUE (TREE_TYPE (name))),
 458                           wi::to_wide (TYPE_MAX_VALUE (TREE_TYPE (name))));
 459     }
 460   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 461   ri->set_nonzero_bits (mask);
 462 }
 463
 464 /* Return a widest_int with potentially non-zero bits in SSA_NAME
 465    NAME, the constant for INTEGER_CST, or -1 if unknown.  */
 466
 467 wide_int
 468 get_nonzero_bits (const_tree name)
 469 {
 470   if (TREE_CODE (name) == INTEGER_CST)
 471     return wi::to_wide (name);
 472
 473   /* Use element_precision instead of TYPE_PRECISION so complex and
 474      vector types get a non-zero precision.  */
 475   unsigned int precision = element_precision (TREE_TYPE (name));
 476   if (POINTER_TYPE_P (TREE_TYPE (name)))
 477     {
 478       struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
 479       if (pi && pi->align)
 480         return wi::shwi (-(HOST_WIDE_INT) pi->align
 481                          | (HOST_WIDE_INT) pi->misalign, precision);
 482       return wi::shwi (-1, precision);
 483     }
 484
 485   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 486   if (!ri)
 487     return wi::shwi (-1, precision);
 488
 489   return ri->get_nonzero_bits ();
 490 }
 491
 492 /* Return TRUE is OP, an SSA_NAME has a range of values [0..1], false
 493    otherwise.
 494
 495    This can be because it is a boolean type, any unsigned integral
 496    type with a single bit of precision, or has known range of [0..1]
 497    via VRP analysis.  */
 498
 499 bool
 500 ssa_name_has_boolean_range (tree op)
 501 {
 502   gcc_assert (TREE_CODE (op) == SSA_NAME);
 503
 504   /* Boolean types always have a range [0..1].  */
 505   if (TREE_CODE (TREE_TYPE (op)) == BOOLEAN_TYPE)
 506     return true;
 507
 508   /* An integral type with a single bit of precision.  */
 509   if (INTEGRAL_TYPE_P (TREE_TYPE (op))
 510       && TYPE_UNSIGNED (TREE_TYPE (op))
 511       && TYPE_PRECISION (TREE_TYPE (op)) == 1)
 512     return true;
 513
 514   /* An integral type with more precision, but the object
 515      only takes on values [0..1] as determined by VRP
 516      analysis.  */
 517   if (INTEGRAL_TYPE_P (TREE_TYPE (op))
 518       && (TYPE_PRECISION (TREE_TYPE (op)) > 1)
 519       && wi::eq_p (get_nonzero_bits (op), 1))
 520     return true;
 521
 522   return false;
 523 }
 524
 525 /* We no longer need the SSA_NAME expression VAR, release it so that
 526    it may be reused.
 527
 528    Note it is assumed that no calls to make_ssa_name will be made
 529    until all uses of the ssa name are released and that the only
 530    use of the SSA_NAME expression is to check its SSA_NAME_VAR.  All
 531    other fields must be assumed clobbered.  */
 532
 533 void
 534 release_ssa_name_fn (struct function *fn, tree var)
 535 {
 536   if (!var)
 537     return;
 538
 539   /* Never release the default definition for a symbol.  It's a
 540      special SSA name that should always exist once it's created.  */
 541   if (SSA_NAME_IS_DEFAULT_DEF (var))
 542     return;
 543
 544   /* If VAR has been registered for SSA updating, don't remove it.
 545      After update_ssa has run, the name will be released.  */
 546   if (name_registered_for_update_p (var))
 547     {
 548       release_ssa_name_after_update_ssa (var);
 549       return;
 550     }
 551
 552   /* release_ssa_name can be called multiple times on a single SSA_NAME.
 553      However, it should only end up on our free list one time.   We
 554      keep a status bit in the SSA_NAME node itself to indicate it has
 555      been put on the free list.
 556
 557      Note that once on the freelist you can not reference the SSA_NAME's
 558      defining statement.  */
 559   if (! SSA_NAME_IN_FREE_LIST (var))
 560     {
 561       tree saved_ssa_name_var = SSA_NAME_VAR (var);
 562       int saved_ssa_name_version = SSA_NAME_VERSION (var);
 563       use_operand_p imm = &(SSA_NAME_IMM_USE_NODE (var));
 564
 565       if (MAY_HAVE_DEBUG_STMTS)
 566         insert_debug_temp_for_var_def (NULL, var);
 567
 568       if (flag_checking)
 569         verify_imm_links (stderr, var);
 570       while (imm->next != imm)
 571         delink_imm_use (imm->next);
 572
 573       (*SSANAMES (fn))[SSA_NAME_VERSION (var)] = NULL_TREE;
 574       memset (var, 0, tree_size (var));
 575
 576       imm->prev = imm;
 577       imm->next = imm;
 578       imm->loc.ssa_name = var;
 579
 580       /* First put back the right tree node so that the tree checking
 581          macros do not complain.  */
 582       TREE_SET_CODE (var, SSA_NAME);
 583
 584       /* Restore the version number.  */
 585       SSA_NAME_VERSION (var) = saved_ssa_name_version;
 586
 587       /* Hopefully this can go away once we have the new incremental
 588          SSA updating code installed.  */
 589       SET_SSA_NAME_VAR_OR_IDENTIFIER (var, saved_ssa_name_var);
 590
 591       /* Note this SSA_NAME is now in the first list.  */
 592       SSA_NAME_IN_FREE_LIST (var) = 1;
 593
 594       /* And finally queue it so that it will be put on the free list.  */
 595       vec_safe_push (FREE_SSANAMES_QUEUE (fn), var);
 596     }
 597 }
 598
 599 /* If the alignment of the pointer described by PI is known, return true and
 600    store the alignment and the deviation from it into *ALIGNP and *MISALIGNP
 601    respectively.  Otherwise return false.  */
 602
 603 bool
 604 get_ptr_info_alignment (struct ptr_info_def *pi, unsigned int *alignp,
 605                         unsigned int *misalignp)
 606 {
 607   if (pi->align)
 608     {
 609       *alignp = pi->align;
 610       *misalignp = pi->misalign;
 611       return true;
 612     }
 613   else
 614     return false;
 615 }
 616
 617 /* State that the pointer described by PI has unknown alignment.  */
 618
 619 void
 620 mark_ptr_info_alignment_unknown (struct ptr_info_def *pi)
 621 {
 622   pi->align = 0;
 623   pi->misalign = 0;
 624 }
 625
 626 /* Store the power-of-two byte alignment and the deviation from that
 627    alignment of pointer described by PI to ALIOGN and MISALIGN
 628    respectively.  */
 629
 630 void
 631 set_ptr_info_alignment (struct ptr_info_def *pi, unsigned int align,
 632                             unsigned int misalign)
 633 {
 634   gcc_checking_assert (align != 0);
 635   gcc_assert ((align & (align - 1)) == 0);
 636   gcc_assert ((misalign & ~(align - 1)) == 0);
 637
 638   pi->align = align;
 639   pi->misalign = misalign;
 640 }
 641
 642 /* If pointer described by PI has known alignment, increase its known
 643    misalignment by INCREMENT modulo its current alignment.  */
 644
 645 void
 646 adjust_ptr_info_misalignment (struct ptr_info_def *pi,
 647                               unsigned int increment)
 648 {
 649   if (pi->align != 0)
 650     {
 651       pi->misalign += increment;
 652       pi->misalign &= (pi->align - 1);
 653     }
 654 }
 655
 656 /* Return the alias information associated with pointer T.  It creates a
 657    new instance if none existed.  */
 658
 659 struct ptr_info_def *
 660 get_ptr_info (tree t)
 661 {
 662   struct ptr_info_def *pi;
 663
 664   gcc_assert (POINTER_TYPE_P (TREE_TYPE (t)));
 665
 666   pi = SSA_NAME_PTR_INFO (t);
 667   if (pi == NULL)
 668     {
 669       pi = ggc_cleared_alloc<ptr_info_def> ();
 670       pt_solution_reset (&pi->pt);
 671       mark_ptr_info_alignment_unknown (pi);
 672       SSA_NAME_PTR_INFO (t) = pi;
 673     }
 674
 675   return pi;
 676 }
 677
 678
 679 /* Creates a new SSA name using the template NAME tobe defined by
 680    statement STMT in function FN.  */
 681
 682 tree
 683 copy_ssa_name_fn (struct function *fn, tree name, gimple *stmt)
 684 {
 685   tree new_name;
 686
 687   if (SSA_NAME_VAR (name))
 688     new_name = make_ssa_name_fn (fn, SSA_NAME_VAR (name), stmt);
 689   else
 690     {
 691       new_name = make_ssa_name_fn (fn, TREE_TYPE (name), stmt);
 692       SET_SSA_NAME_VAR_OR_IDENTIFIER (new_name, SSA_NAME_IDENTIFIER (name));
 693     }
 694
 695   return new_name;
 696 }
 697
 698
 699 /* Creates a duplicate of the ptr_info_def at PTR_INFO for use by
 700    the SSA name NAME.  */
 701
 702 void
 703 duplicate_ssa_name_ptr_info (tree name, struct ptr_info_def *ptr_info)
 704 {
 705   struct ptr_info_def *new_ptr_info;
 706
 707   gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
 708   gcc_assert (!SSA_NAME_PTR_INFO (name));
 709
 710   if (!ptr_info)
 711     return;
 712
 713   new_ptr_info = ggc_alloc<ptr_info_def> ();
 714   *new_ptr_info = *ptr_info;
 715
 716   SSA_NAME_PTR_INFO (name) = new_ptr_info;
 717 }
 718
 719 /* Creates a duplicate of the range_info_def at RANGE_INFO of type
 720    RANGE_TYPE for use by the SSA name NAME.  */
 721 void
 722 duplicate_ssa_name_range_info (tree name, enum value_range_type range_type,
 723                                struct range_info_def *range_info)
 724 {
 725   struct range_info_def *new_range_info;
 726
 727   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 728   gcc_assert (!SSA_NAME_RANGE_INFO (name));
 729
 730   if (!range_info)
 731     return;
 732
 733   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 734   size_t size = (sizeof (range_info_def)
 735                  + trailing_wide_ints <3>::extra_size (precision));
 736   new_range_info = static_cast<range_info_def *> (ggc_internal_alloc (size));
 737   memcpy (new_range_info, range_info, size);
 738
 739   gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
 740   SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
 741   SSA_NAME_RANGE_INFO (name) = new_range_info;
 742 }
 743
 744
 745
 746 /* Creates a duplicate of a ssa name NAME tobe defined by statement STMT
 747    in function FN.  */
 748
 749 tree
 750 duplicate_ssa_name_fn (struct function *fn, tree name, gimple *stmt)
 751 {
 752   tree new_name = copy_ssa_name_fn (fn, name, stmt);
 753   if (POINTER_TYPE_P (TREE_TYPE (name)))
 754     {
 755       struct ptr_info_def *old_ptr_info = SSA_NAME_PTR_INFO (name);
 756
 757       if (old_ptr_info)
 758         duplicate_ssa_name_ptr_info (new_name, old_ptr_info);
 759     }
 760   else
 761     {
 762       struct range_info_def *old_range_info = SSA_NAME_RANGE_INFO (name);
 763
 764       if (old_range_info)
 765         duplicate_ssa_name_range_info (new_name, SSA_NAME_RANGE_TYPE (name),
 766                                        old_range_info);
 767     }
 768
 769   return new_name;
 770 }
 771
 772
 773 /* Reset all flow sensitive data on NAME such as range-info, nonzero
 774    bits and alignment.  */
 775
 776 void
 777 reset_flow_sensitive_info (tree name)
 778 {
 779   if (POINTER_TYPE_P (TREE_TYPE (name)))
 780     {
 781       /* points-to info is not flow-sensitive.  */
 782       if (SSA_NAME_PTR_INFO (name))
 783         mark_ptr_info_alignment_unknown (SSA_NAME_PTR_INFO (name));
 784     }
 785   else
 786     SSA_NAME_RANGE_INFO (name) = NULL;
 787 }
 788
 789 /* Clear all flow sensitive data from all statements and PHI definitions
 790    in BB.  */
 791
 792 void
 793 reset_flow_sensitive_info_in_bb (basic_block bb)
 794 {
 795   for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);
 796        gsi_next (&gsi))
 797     {
 798       gimple *stmt = gsi_stmt (gsi);
 799       ssa_op_iter i;
 800       tree op;
 801       FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_DEF)
 802         reset_flow_sensitive_info (op);
 803     }
 804
 805   for (gphi_iterator gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
 806        gsi_next (&gsi))
 807     {
 808       tree phi_def = gimple_phi_result (gsi.phi ());
 809       reset_flow_sensitive_info (phi_def);
 810     }
 811 }
 812
 813 /* Release all the SSA_NAMEs created by STMT.  */
 814
 815 void
 816 release_defs (gimple *stmt)
 817 {
 818   tree def;
 819   ssa_op_iter iter;
 820
 821   FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
 822     if (TREE_CODE (def) == SSA_NAME)
 823       release_ssa_name (def);
 824 }
 825
 826
 827 /* Replace the symbol associated with SSA_NAME with SYM.  */
 828
 829 void
 830 replace_ssa_name_symbol (tree ssa_name, tree sym)
 831 {
 832   SET_SSA_NAME_VAR_OR_IDENTIFIER (ssa_name, sym);
 833   TREE_TYPE (ssa_name) = TREE_TYPE (sym);
 834 }
 835
 836 /* Release the vector of free SSA_NAMEs and compact the vector of SSA_NAMEs
 837    that are live.  */
 838
 839 static void
 840 release_free_names_and_compact_live_names (function *fun)
 841 {
 842   unsigned i, j;
 843   int n = vec_safe_length (FREE_SSANAMES (fun));
 844
 845   /* Now release the freelist.  */
 846   vec_free (FREE_SSANAMES (fun));
 847
 848   /* And compact the SSA number space.  We make sure to not change the
 849      relative order of SSA versions.  */
 850   for (i = 1, j = 1; i < fun->gimple_df->ssa_names->length (); ++i)
 851     {
 852       tree name = ssa_name (i);
 853       if (name)
 854         {
 855           if (i != j)
 856             {
 857               SSA_NAME_VERSION (name) = j;
 858               (*fun->gimple_df->ssa_names)[j] = name;
 859             }
 860           j++;
 861         }
 862     }
 863   fun->gimple_df->ssa_names->truncate (j);
 864
 865   statistics_counter_event (fun, "SSA names released", n);
 866   statistics_counter_event (fun, "SSA name holes removed", i - j);
 867   if (dump_file)
 868     fprintf (dump_file, "Released %i names, %.2f%%, removed %i holes\n",
 869              n, n * 100.0 / num_ssa_names, i - j);
 870 }
 871
 872 /* Return SSA names that are unused to GGC memory and compact the SSA
 873    version namespace.  This is used to keep footprint of compiler during
 874    interprocedural optimization.  */
 875
 876 namespace {
 877
 878 const pass_data pass_data_release_ssa_names =
 879 {
 880   GIMPLE_PASS, /* type */
 881   "release_ssa", /* name */
 882   OPTGROUP_NONE, /* optinfo_flags */
 883   TV_TREE_SSA_OTHER, /* tv_id */
 884   PROP_ssa, /* properties_required */
 885   0, /* properties_provided */
 886   0, /* properties_destroyed */
 887   TODO_remove_unused_locals, /* todo_flags_start */
 888   0, /* todo_flags_finish */
 889 };
 890
 891 class pass_release_ssa_names : public gimple_opt_pass
 892 {
 893 public:
 894   pass_release_ssa_names (gcc::context *ctxt)
 895     : gimple_opt_pass (pass_data_release_ssa_names, ctxt)
 896   {}
 897
 898   /* opt_pass methods: */
 899   virtual unsigned int execute (function *);
 900
 901 }; // class pass_release_ssa_names
 902
 903 unsigned int
 904 pass_release_ssa_names::execute (function *fun)
 905 {
 906   release_free_names_and_compact_live_names (fun);
 907   return 0;
 908 }
 909
 910 } // anon namespace
 911
 912 gimple_opt_pass *
 913 make_pass_release_ssa_names (gcc::context *ctxt)
 914 {
 915   return new pass_release_ssa_names (ctxt);
 916 }