gcc/tree-ssanames.c

   1 /* Generic routines for manipulating SSA_NAME expressions
   2    Copyright (C) 2003-2018 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 #include "cfgloop.h"
  33 #include "tree-scalar-evolution.h"
  34
  35 /* Rewriting a function into SSA form can create a huge number of SSA_NAMEs,
  36    many of which may be thrown away shortly after their creation if jumps
  37    were threaded through PHI nodes.
  38
  39    While our garbage collection mechanisms will handle this situation, it
  40    is extremely wasteful to create nodes and throw them away, especially
  41    when the nodes can be reused.
  42
  43    For PR 8361, we can significantly reduce the number of nodes allocated
  44    and thus the total amount of memory allocated by managing SSA_NAMEs a
  45    little.  This additionally helps reduce the amount of work done by the
  46    garbage collector.  Similar results have been seen on a wider variety
  47    of tests (such as the compiler itself).
  48
  49    Right now we maintain our free list on a per-function basis.  It may
  50    or may not make sense to maintain the free list for the duration of
  51    a compilation unit.
  52
  53    External code should rely solely upon HIGHEST_SSA_VERSION and the
  54    externally defined functions.  External code should not know about
  55    the details of the free list management.
  56
  57    External code should also not assume the version number on nodes is
  58    monotonically increasing.  We reuse the version number when we
  59    reuse an SSA_NAME expression.  This helps keep arrays and bitmaps
  60    more compact.  */
  61
  62
  63 /* Version numbers with special meanings.  We start allocating new version
  64    numbers after the special ones.  */
  65 #define UNUSED_NAME_VERSION 0
  66
  67 unsigned int ssa_name_nodes_reused;
  68 unsigned int ssa_name_nodes_created;
  69
  70 #define FREE_SSANAMES(fun) (fun)->gimple_df->free_ssanames
  71 #define FREE_SSANAMES_QUEUE(fun) (fun)->gimple_df->free_ssanames_queue
  72
  73
  74 /* Initialize management of SSA_NAMEs to default SIZE.  If SIZE is
  75    zero use default.  */
  76
  77 void
  78 init_ssanames (struct function *fn, int size)
  79 {
  80   if (size < 50)
  81     size = 50;
  82
  83   vec_alloc (SSANAMES (fn), size);
  84
  85   /* Version 0 is special, so reserve the first slot in the table.  Though
  86      currently unused, we may use version 0 in alias analysis as part of
  87      the heuristics used to group aliases when the alias sets are too
  88      large.
  89
  90      We use vec::quick_push here because we know that SSA_NAMES has at
  91      least 50 elements reserved in it.  */
  92   SSANAMES (fn)->quick_push (NULL_TREE);
  93   FREE_SSANAMES (fn) = NULL;
  94   FREE_SSANAMES_QUEUE (fn) = NULL;
  95
  96   fn->gimple_df->ssa_renaming_needed = 0;
  97   fn->gimple_df->rename_vops = 0;
  98 }
  99
 100 /* Finalize management of SSA_NAMEs.  */
 101
 102 void
 103 fini_ssanames (struct function *fn)
 104 {
 105   vec_free (SSANAMES (fn));
 106   vec_free (FREE_SSANAMES (fn));
 107   vec_free (FREE_SSANAMES_QUEUE (fn));
 108 }
 109
 110 /* Dump some simple statistics regarding the re-use of SSA_NAME nodes.  */
 111
 112 void
 113 ssanames_print_statistics (void)
 114 {
 115   fprintf (stderr, "SSA_NAME nodes allocated: %u\n", ssa_name_nodes_created);
 116   fprintf (stderr, "SSA_NAME nodes reused: %u\n", ssa_name_nodes_reused);
 117 }
 118
 119 /* Verify the state of the SSA_NAME lists.
 120
 121    There must be no duplicates on the free list.
 122    Every name on the free list must be marked as on the free list.
 123    Any name on the free list must not appear in the IL.
 124    No names can be leaked.  */
 125
 126 DEBUG_FUNCTION void
 127 verify_ssaname_freelists (struct function *fun)
 128 {
 129   if (!gimple_in_ssa_p (fun))
 130     return;
 131
 132   auto_bitmap names_in_il;
 133
 134   /* Walk the entire IL noting every SSA_NAME we see.  */
 135   basic_block bb;
 136   FOR_EACH_BB_FN (bb, fun)
 137     {
 138       tree t;
 139       /* First note the result and arguments of PHI nodes.  */
 140       for (gphi_iterator gsi = gsi_start_phis (bb);
 141            !gsi_end_p (gsi);
 142            gsi_next (&gsi))
 143         {
 144           gphi *phi = gsi.phi ();
 145           t = gimple_phi_result (phi);
 146           bitmap_set_bit (names_in_il, SSA_NAME_VERSION (t));
 147
 148           for (unsigned int i = 0; i < gimple_phi_num_args (phi); i++)
 149             {
 150               t = gimple_phi_arg_def (phi, i);
 151               if (TREE_CODE (t) == SSA_NAME)
 152                 bitmap_set_bit (names_in_il, SSA_NAME_VERSION (t));
 153             }
 154         }
 155
 156       /* Then note the operands of each statement.  */
 157       for (gimple_stmt_iterator gsi = gsi_start_bb (bb);
 158            !gsi_end_p (gsi);
 159            gsi_next (&gsi))
 160         {
 161           ssa_op_iter iter;
 162           gimple *stmt = gsi_stmt (gsi);
 163           FOR_EACH_SSA_TREE_OPERAND (t, stmt, iter, SSA_OP_ALL_OPERANDS)
 164             bitmap_set_bit (names_in_il, SSA_NAME_VERSION (t));
 165         }
 166     }
 167
 168   /* Now walk the free list noting what we find there and verifying
 169      there are no duplicates.  */
 170   auto_bitmap names_in_freelists;
 171   if (FREE_SSANAMES (fun))
 172     {
 173       for (unsigned int i = 0; i < FREE_SSANAMES (fun)->length (); i++)
 174         {
 175           tree t = (*FREE_SSANAMES (fun))[i];
 176
 177           /* Verify that the name is marked as being in the free list.  */
 178           gcc_assert (SSA_NAME_IN_FREE_LIST (t));
 179
 180           /* Verify the name has not already appeared in the free list and
 181              note it in the list of names found in the free list.  */
 182           gcc_assert (!bitmap_bit_p (names_in_freelists, SSA_NAME_VERSION (t)));
 183           bitmap_set_bit (names_in_freelists, SSA_NAME_VERSION (t));
 184         }
 185     }
 186
 187   /* Similarly for the names in the pending free list.  */
 188   if (FREE_SSANAMES_QUEUE (fun))
 189     {
 190       for (unsigned int i = 0; i < FREE_SSANAMES_QUEUE (fun)->length (); i++)
 191         {
 192           tree t = (*FREE_SSANAMES_QUEUE (fun))[i];
 193
 194           /* Verify that the name is marked as being in the free list.  */
 195           gcc_assert (SSA_NAME_IN_FREE_LIST (t));
 196
 197           /* Verify the name has not already appeared in the free list and
 198              note it in the list of names found in the free list.  */
 199           gcc_assert (!bitmap_bit_p (names_in_freelists, SSA_NAME_VERSION (t)));
 200           bitmap_set_bit (names_in_freelists, SSA_NAME_VERSION (t));
 201         }
 202     }
 203
 204   /* If any name appears in both the IL and the freelists, then
 205      something horrible has happened.  */
 206   bool intersect_p = bitmap_intersect_p (names_in_il, names_in_freelists);
 207   gcc_assert (!intersect_p);
 208
 209   /* Names can be queued up for release if there is an ssa update
 210      pending.  Pretend we saw them in the IL.  */
 211   if (names_to_release)
 212     bitmap_ior_into (names_in_il, names_to_release);
 213
 214   /* Function splitting can "lose" SSA_NAMEs in an effort to ensure that
 215      debug/non-debug compilations have the same SSA_NAMEs.  So for each
 216      lost SSA_NAME, see if it's likely one from that wart.  These will always
 217      be marked as default definitions.  So we loosely assume that anything
 218      marked as a default definition isn't leaked by pretending they are
 219      in the IL.  */
 220   for (unsigned int i = UNUSED_NAME_VERSION + 1; i < num_ssa_names; i++)
 221     if (ssa_name (i) && SSA_NAME_IS_DEFAULT_DEF (ssa_name (i)))
 222       bitmap_set_bit (names_in_il, i);
 223
 224   unsigned int i;
 225   bitmap_iterator bi;
 226   auto_bitmap all_names;
 227   bitmap_set_range (all_names, UNUSED_NAME_VERSION + 1, num_ssa_names - 1);
 228   bitmap_ior_into (names_in_il, names_in_freelists);
 229
 230   /* Any name not mentioned in the IL and not in the feelists
 231      has been leaked.  */
 232   EXECUTE_IF_AND_COMPL_IN_BITMAP(all_names, names_in_il,
 233                                  UNUSED_NAME_VERSION + 1, i, bi)
 234     gcc_assert (!ssa_name (i));
 235 }
 236
 237 /* Move all SSA_NAMEs from FREE_SSA_NAMES_QUEUE to FREE_SSA_NAMES.
 238
 239    We do not, but should have a mode to verify the state of the SSA_NAMEs
 240    lists.  In particular at this point every name must be in the IL,
 241    on the free list or in the queue.  Anything else is an error.  */
 242
 243 void
 244 flush_ssaname_freelist (void)
 245 {
 246   /* If there were any SSA names released reset the SCEV cache.  */
 247   if (! vec_safe_is_empty (FREE_SSANAMES_QUEUE (cfun)))
 248     scev_reset_htab ();
 249   vec_safe_splice (FREE_SSANAMES (cfun), FREE_SSANAMES_QUEUE (cfun));
 250   vec_safe_truncate (FREE_SSANAMES_QUEUE (cfun), 0);
 251 }
 252
 253 /* Return an SSA_NAME node for variable VAR defined in statement STMT
 254    in function FN.  STMT may be an empty statement for artificial
 255    references (e.g., default definitions created when a variable is
 256    used without a preceding definition).  If VERISON is not zero then
 257    allocate the SSA name with that version.  */
 258
 259 tree
 260 make_ssa_name_fn (struct function *fn, tree var, gimple *stmt,
 261                   unsigned int version)
 262 {
 263   tree t;
 264   use_operand_p imm;
 265
 266   gcc_assert (VAR_P (var)
 267               || TREE_CODE (var) == PARM_DECL
 268               || TREE_CODE (var) == RESULT_DECL
 269               || (TYPE_P (var) && is_gimple_reg_type (var)));
 270
 271   /* Get the specified SSA name version.  */
 272   if (version != 0)
 273     {
 274       t = make_node (SSA_NAME);
 275       SSA_NAME_VERSION (t) = version;
 276       if (version >= SSANAMES (fn)->length ())
 277         vec_safe_grow_cleared (SSANAMES (fn), version + 1);
 278       gcc_assert ((*SSANAMES (fn))[version] == NULL);
 279       (*SSANAMES (fn))[version] = t;
 280       ssa_name_nodes_created++;
 281     }
 282   /* If our free list has an element, then use it.  */
 283   else if (!vec_safe_is_empty (FREE_SSANAMES (fn)))
 284     {
 285       t = FREE_SSANAMES (fn)->pop ();
 286       ssa_name_nodes_reused++;
 287
 288       /* The node was cleared out when we put it on the free list, so
 289          there is no need to do so again here.  */
 290       gcc_assert ((*SSANAMES (fn))[SSA_NAME_VERSION (t)] == NULL);
 291       (*SSANAMES (fn))[SSA_NAME_VERSION (t)] = t;
 292     }
 293   else
 294     {
 295       t = make_node (SSA_NAME);
 296       SSA_NAME_VERSION (t) = SSANAMES (fn)->length ();
 297       vec_safe_push (SSANAMES (fn), t);
 298       ssa_name_nodes_created++;
 299     }
 300
 301   if (TYPE_P (var))
 302     {
 303       TREE_TYPE (t) = TYPE_MAIN_VARIANT (var);
 304       SET_SSA_NAME_VAR_OR_IDENTIFIER (t, NULL_TREE);
 305     }
 306   else
 307     {
 308       TREE_TYPE (t) = TREE_TYPE (var);
 309       SET_SSA_NAME_VAR_OR_IDENTIFIER (t, var);
 310     }
 311   SSA_NAME_DEF_STMT (t) = stmt;
 312   if (POINTER_TYPE_P (TREE_TYPE (t)))
 313     SSA_NAME_PTR_INFO (t) = NULL;
 314   else
 315     SSA_NAME_RANGE_INFO (t) = NULL;
 316
 317   SSA_NAME_IN_FREE_LIST (t) = 0;
 318   SSA_NAME_IS_DEFAULT_DEF (t) = 0;
 319   imm = &(SSA_NAME_IMM_USE_NODE (t));
 320   imm->use = NULL;
 321   imm->prev = imm;
 322   imm->next = imm;
 323   imm->loc.ssa_name = t;
 324
 325   return t;
 326 }
 327
 328 /* Helper function for set_range_info.
 329
 330    Store range information RANGE_TYPE, MIN, and MAX to tree ssa_name
 331    NAME.  */
 332
 333 void
 334 set_range_info_raw (tree name, enum value_range_type range_type,
 335                     const wide_int_ref &min, const wide_int_ref &max)
 336 {
 337   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 338   gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
 339   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 340   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 341
 342   /* Allocate if not available.  */
 343   if (ri == NULL)
 344     {
 345       size_t size = (sizeof (range_info_def)
 346                      + trailing_wide_ints <3>::extra_size (precision));
 347       ri = static_cast<range_info_def *> (ggc_internal_alloc (size));
 348       ri->ints.set_precision (precision);
 349       SSA_NAME_RANGE_INFO (name) = ri;
 350       ri->set_nonzero_bits (wi::shwi (-1, precision));
 351     }
 352
 353   /* Record the range type.  */
 354   if (SSA_NAME_RANGE_TYPE (name) != range_type)
 355     SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
 356
 357   /* Set the values.  */
 358   ri->set_min (min);
 359   ri->set_max (max);
 360
 361   /* If it is a range, try to improve nonzero_bits from the min/max.  */
 362   if (range_type == VR_RANGE)
 363     {
 364       wide_int xorv = ri->get_min () ^ ri->get_max ();
 365       if (xorv != 0)
 366         xorv = wi::mask (precision - wi::clz (xorv), false, precision);
 367       ri->set_nonzero_bits (ri->get_nonzero_bits () & (ri->get_min () | xorv));
 368     }
 369 }
 370
 371 /* Store range information RANGE_TYPE, MIN, and MAX to tree ssa_name
 372    NAME while making sure we don't store useless range info.  */
 373
 374 void
 375 set_range_info (tree name, enum value_range_type range_type,
 376                 const wide_int_ref &min, const wide_int_ref &max)
 377 {
 378   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 379
 380   /* A range of the entire domain is really no range at all.  */
 381   tree type = TREE_TYPE (name);
 382   if (min == wi::min_value (TYPE_PRECISION (type), TYPE_SIGN (type))
 383       && max == wi::max_value (TYPE_PRECISION (type), TYPE_SIGN (type)))
 384     {
 385       range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 386       if (ri == NULL)
 387         return;
 388       if (ri->get_nonzero_bits () == -1)
 389         {
 390           ggc_free (ri);
 391           SSA_NAME_RANGE_INFO (name) = NULL;
 392           return;
 393         }
 394     }
 395
 396   set_range_info_raw (name, range_type, min, max);
 397 }
 398
 399
 400 /* Gets range information MIN, MAX and returns enum value_range_type
 401    corresponding to tree ssa_name NAME.  enum value_range_type returned
 402    is used to determine if MIN and MAX are valid values.  */
 403
 404 enum value_range_type
 405 get_range_info (const_tree name, wide_int *min, wide_int *max)
 406 {
 407   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 408   gcc_assert (min && max);
 409   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 410
 411   /* Return VR_VARYING for SSA_NAMEs with NULL RANGE_INFO or SSA_NAMEs
 412      with integral types width > 2 * HOST_BITS_PER_WIDE_INT precision.  */
 413   if (!ri || (GET_MODE_PRECISION (SCALAR_INT_TYPE_MODE (TREE_TYPE (name)))
 414               > 2 * HOST_BITS_PER_WIDE_INT))
 415     return VR_VARYING;
 416
 417   *min = ri->get_min ();
 418   *max = ri->get_max ();
 419   return SSA_NAME_RANGE_TYPE (name);
 420 }
 421
 422 /* Set nonnull attribute to pointer NAME.  */
 423
 424 void
 425 set_ptr_nonnull (tree name)
 426 {
 427   gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
 428   struct ptr_info_def *pi = get_ptr_info (name);
 429   pi->pt.null = 0;
 430 }
 431
 432 /* Return nonnull attribute of pointer NAME.  */
 433 bool
 434 get_ptr_nonnull (const_tree name)
 435 {
 436   gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
 437   struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
 438   if (pi == NULL)
 439     return false;
 440   /* TODO Now pt->null is conservatively set to true in PTA
 441      analysis. vrp is the only pass (including ipa-vrp)
 442      that clears pt.null via set_ptr_nonull when it knows
 443      for sure. PTA will preserves the pt.null value set by VRP.
 444
 445      When PTA analysis is improved, pt.anything, pt.nonlocal
 446      and pt.escaped may also has to be considered before
 447      deciding that pointer cannot point to NULL.  */
 448   return !pi->pt.null;
 449 }
 450
 451 /* Change non-zero bits bitmask of NAME.  */
 452
 453 void
 454 set_nonzero_bits (tree name, const wide_int_ref &mask)
 455 {
 456   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 457   if (SSA_NAME_RANGE_INFO (name) == NULL)
 458     {
 459       if (mask == -1)
 460         return;
 461       set_range_info_raw (name, VR_RANGE,
 462                           wi::to_wide (TYPE_MIN_VALUE (TREE_TYPE (name))),
 463                           wi::to_wide (TYPE_MAX_VALUE (TREE_TYPE (name))));
 464     }
 465   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 466   ri->set_nonzero_bits (mask);
 467 }
 468
 469 /* Return a widest_int with potentially non-zero bits in SSA_NAME
 470    NAME, the constant for INTEGER_CST, or -1 if unknown.  */
 471
 472 wide_int
 473 get_nonzero_bits (const_tree name)
 474 {
 475   if (TREE_CODE (name) == INTEGER_CST)
 476     return wi::to_wide (name);
 477
 478   /* Use element_precision instead of TYPE_PRECISION so complex and
 479      vector types get a non-zero precision.  */
 480   unsigned int precision = element_precision (TREE_TYPE (name));
 481   if (POINTER_TYPE_P (TREE_TYPE (name)))
 482     {
 483       struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
 484       if (pi && pi->align)
 485         return wi::shwi (-(HOST_WIDE_INT) pi->align
 486                          | (HOST_WIDE_INT) pi->misalign, precision);
 487       return wi::shwi (-1, precision);
 488     }
 489
 490   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 491   if (!ri)
 492     return wi::shwi (-1, precision);
 493
 494   return ri->get_nonzero_bits ();
 495 }
 496
 497 /* Return TRUE is OP, an SSA_NAME has a range of values [0..1], false
 498    otherwise.
 499
 500    This can be because it is a boolean type, any unsigned integral
 501    type with a single bit of precision, or has known range of [0..1]
 502    via VRP analysis.  */
 503
 504 bool
 505 ssa_name_has_boolean_range (tree op)
 506 {
 507   gcc_assert (TREE_CODE (op) == SSA_NAME);
 508
 509   /* Boolean types always have a range [0..1].  */
 510   if (TREE_CODE (TREE_TYPE (op)) == BOOLEAN_TYPE)
 511     return true;
 512
 513   /* An integral type with a single bit of precision.  */
 514   if (INTEGRAL_TYPE_P (TREE_TYPE (op))
 515       && TYPE_UNSIGNED (TREE_TYPE (op))
 516       && TYPE_PRECISION (TREE_TYPE (op)) == 1)
 517     return true;
 518
 519   /* An integral type with more precision, but the object
 520      only takes on values [0..1] as determined by VRP
 521      analysis.  */
 522   if (INTEGRAL_TYPE_P (TREE_TYPE (op))
 523       && (TYPE_PRECISION (TREE_TYPE (op)) > 1)
 524       && wi::eq_p (get_nonzero_bits (op), 1))
 525     return true;
 526
 527   return false;
 528 }
 529
 530 /* We no longer need the SSA_NAME expression VAR, release it so that
 531    it may be reused.
 532
 533    Note it is assumed that no calls to make_ssa_name will be made
 534    until all uses of the ssa name are released and that the only
 535    use of the SSA_NAME expression is to check its SSA_NAME_VAR.  All
 536    other fields must be assumed clobbered.  */
 537
 538 void
 539 release_ssa_name_fn (struct function *fn, tree var)
 540 {
 541   if (!var)
 542     return;
 543
 544   /* Never release the default definition for a symbol.  It's a
 545      special SSA name that should always exist once it's created.  */
 546   if (SSA_NAME_IS_DEFAULT_DEF (var))
 547     return;
 548
 549   /* If VAR has been registered for SSA updating, don't remove it.
 550      After update_ssa has run, the name will be released.  */
 551   if (name_registered_for_update_p (var))
 552     {
 553       release_ssa_name_after_update_ssa (var);
 554       return;
 555     }
 556
 557   /* release_ssa_name can be called multiple times on a single SSA_NAME.
 558      However, it should only end up on our free list one time.   We
 559      keep a status bit in the SSA_NAME node itself to indicate it has
 560      been put on the free list.
 561
 562      Note that once on the freelist you can not reference the SSA_NAME's
 563      defining statement.  */
 564   if (! SSA_NAME_IN_FREE_LIST (var))
 565     {
 566       tree saved_ssa_name_var = SSA_NAME_VAR (var);
 567       int saved_ssa_name_version = SSA_NAME_VERSION (var);
 568       use_operand_p imm = &(SSA_NAME_IMM_USE_NODE (var));
 569
 570       if (MAY_HAVE_DEBUG_BIND_STMTS)
 571         insert_debug_temp_for_var_def (NULL, var);
 572
 573       if (flag_checking)
 574         verify_imm_links (stderr, var);
 575       while (imm->next != imm)
 576         delink_imm_use (imm->next);
 577
 578       (*SSANAMES (fn))[SSA_NAME_VERSION (var)] = NULL_TREE;
 579       memset (var, 0, tree_size (var));
 580
 581       imm->prev = imm;
 582       imm->next = imm;
 583       imm->loc.ssa_name = var;
 584
 585       /* First put back the right tree node so that the tree checking
 586          macros do not complain.  */
 587       TREE_SET_CODE (var, SSA_NAME);
 588
 589       /* Restore the version number.  */
 590       SSA_NAME_VERSION (var) = saved_ssa_name_version;
 591
 592       /* Hopefully this can go away once we have the new incremental
 593          SSA updating code installed.  */
 594       SET_SSA_NAME_VAR_OR_IDENTIFIER (var, saved_ssa_name_var);
 595
 596       /* Note this SSA_NAME is now in the first list.  */
 597       SSA_NAME_IN_FREE_LIST (var) = 1;
 598
 599       /* And finally queue it so that it will be put on the free list.  */
 600       vec_safe_push (FREE_SSANAMES_QUEUE (fn), var);
 601     }
 602 }
 603
 604 /* If the alignment of the pointer described by PI is known, return true and
 605    store the alignment and the deviation from it into *ALIGNP and *MISALIGNP
 606    respectively.  Otherwise return false.  */
 607
 608 bool
 609 get_ptr_info_alignment (struct ptr_info_def *pi, unsigned int *alignp,
 610                         unsigned int *misalignp)
 611 {
 612   if (pi->align)
 613     {
 614       *alignp = pi->align;
 615       *misalignp = pi->misalign;
 616       return true;
 617     }
 618   else
 619     return false;
 620 }
 621
 622 /* State that the pointer described by PI has unknown alignment.  */
 623
 624 void
 625 mark_ptr_info_alignment_unknown (struct ptr_info_def *pi)
 626 {
 627   pi->align = 0;
 628   pi->misalign = 0;
 629 }
 630
 631 /* Store the power-of-two byte alignment and the deviation from that
 632    alignment of pointer described by PI to ALIOGN and MISALIGN
 633    respectively.  */
 634
 635 void
 636 set_ptr_info_alignment (struct ptr_info_def *pi, unsigned int align,
 637                             unsigned int misalign)
 638 {
 639   gcc_checking_assert (align != 0);
 640   gcc_assert ((align & (align - 1)) == 0);
 641   gcc_assert ((misalign & ~(align - 1)) == 0);
 642
 643   pi->align = align;
 644   pi->misalign = misalign;
 645 }
 646
 647 /* If pointer described by PI has known alignment, increase its known
 648    misalignment by INCREMENT modulo its current alignment.  */
 649
 650 void
 651 adjust_ptr_info_misalignment (struct ptr_info_def *pi, poly_uint64 increment)
 652 {
 653   if (pi->align != 0)
 654     {
 655       increment += pi->misalign;
 656       if (!known_misalignment (increment, pi->align, &pi->misalign))
 657         {
 658           pi->align = known_alignment (increment);
 659           pi->misalign = 0;
 660         }
 661     }
 662 }
 663
 664 /* Return the alias information associated with pointer T.  It creates a
 665    new instance if none existed.  */
 666
 667 struct ptr_info_def *
 668 get_ptr_info (tree t)
 669 {
 670   struct ptr_info_def *pi;
 671
 672   gcc_assert (POINTER_TYPE_P (TREE_TYPE (t)));
 673
 674   pi = SSA_NAME_PTR_INFO (t);
 675   if (pi == NULL)
 676     {
 677       pi = ggc_cleared_alloc<ptr_info_def> ();
 678       pt_solution_reset (&pi->pt);
 679       mark_ptr_info_alignment_unknown (pi);
 680       SSA_NAME_PTR_INFO (t) = pi;
 681     }
 682
 683   return pi;
 684 }
 685
 686
 687 /* Creates a new SSA name using the template NAME tobe defined by
 688    statement STMT in function FN.  */
 689
 690 tree
 691 copy_ssa_name_fn (struct function *fn, tree name, gimple *stmt)
 692 {
 693   tree new_name;
 694
 695   if (SSA_NAME_VAR (name))
 696     new_name = make_ssa_name_fn (fn, SSA_NAME_VAR (name), stmt);
 697   else
 698     {
 699       new_name = make_ssa_name_fn (fn, TREE_TYPE (name), stmt);
 700       SET_SSA_NAME_VAR_OR_IDENTIFIER (new_name, SSA_NAME_IDENTIFIER (name));
 701     }
 702
 703   return new_name;
 704 }
 705
 706
 707 /* Creates a duplicate of the ptr_info_def at PTR_INFO for use by
 708    the SSA name NAME.  */
 709
 710 void
 711 duplicate_ssa_name_ptr_info (tree name, struct ptr_info_def *ptr_info)
 712 {
 713   struct ptr_info_def *new_ptr_info;
 714
 715   gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
 716   gcc_assert (!SSA_NAME_PTR_INFO (name));
 717
 718   if (!ptr_info)
 719     return;
 720
 721   new_ptr_info = ggc_alloc<ptr_info_def> ();
 722   *new_ptr_info = *ptr_info;
 723
 724   SSA_NAME_PTR_INFO (name) = new_ptr_info;
 725 }
 726
 727 /* Creates a duplicate of the range_info_def at RANGE_INFO of type
 728    RANGE_TYPE for use by the SSA name NAME.  */
 729 void
 730 duplicate_ssa_name_range_info (tree name, enum value_range_type range_type,
 731                                struct range_info_def *range_info)
 732 {
 733   struct range_info_def *new_range_info;
 734
 735   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 736   gcc_assert (!SSA_NAME_RANGE_INFO (name));
 737
 738   if (!range_info)
 739     return;
 740
 741   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 742   size_t size = (sizeof (range_info_def)
 743                  + trailing_wide_ints <3>::extra_size (precision));
 744   new_range_info = static_cast<range_info_def *> (ggc_internal_alloc (size));
 745   memcpy (new_range_info, range_info, size);
 746
 747   gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
 748   SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
 749   SSA_NAME_RANGE_INFO (name) = new_range_info;
 750 }
 751
 752
 753
 754 /* Creates a duplicate of a ssa name NAME tobe defined by statement STMT
 755    in function FN.  */
 756
 757 tree
 758 duplicate_ssa_name_fn (struct function *fn, tree name, gimple *stmt)
 759 {
 760   tree new_name = copy_ssa_name_fn (fn, name, stmt);
 761   if (POINTER_TYPE_P (TREE_TYPE (name)))
 762     {
 763       struct ptr_info_def *old_ptr_info = SSA_NAME_PTR_INFO (name);
 764
 765       if (old_ptr_info)
 766         duplicate_ssa_name_ptr_info (new_name, old_ptr_info);
 767     }
 768   else
 769     {
 770       struct range_info_def *old_range_info = SSA_NAME_RANGE_INFO (name);
 771
 772       if (old_range_info)
 773         duplicate_ssa_name_range_info (new_name, SSA_NAME_RANGE_TYPE (name),
 774                                        old_range_info);
 775     }
 776
 777   return new_name;
 778 }
 779
 780
 781 /* Reset all flow sensitive data on NAME such as range-info, nonzero
 782    bits and alignment.  */
 783
 784 void
 785 reset_flow_sensitive_info (tree name)
 786 {
 787   if (POINTER_TYPE_P (TREE_TYPE (name)))
 788     {
 789       /* points-to info is not flow-sensitive.  */
 790       if (SSA_NAME_PTR_INFO (name))
 791         mark_ptr_info_alignment_unknown (SSA_NAME_PTR_INFO (name));
 792     }
 793   else
 794     SSA_NAME_RANGE_INFO (name) = NULL;
 795 }
 796
 797 /* Clear all flow sensitive data from all statements and PHI definitions
 798    in BB.  */
 799
 800 void
 801 reset_flow_sensitive_info_in_bb (basic_block bb)
 802 {
 803   for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);
 804        gsi_next (&gsi))
 805     {
 806       gimple *stmt = gsi_stmt (gsi);
 807       ssa_op_iter i;
 808       tree op;
 809       FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_DEF)
 810         reset_flow_sensitive_info (op);
 811     }
 812
 813   for (gphi_iterator gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
 814        gsi_next (&gsi))
 815     {
 816       tree phi_def = gimple_phi_result (gsi.phi ());
 817       reset_flow_sensitive_info (phi_def);
 818     }
 819 }
 820
 821 /* Release all the SSA_NAMEs created by STMT.  */
 822
 823 void
 824 release_defs (gimple *stmt)
 825 {
 826   tree def;
 827   ssa_op_iter iter;
 828
 829   FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
 830     if (TREE_CODE (def) == SSA_NAME)
 831       release_ssa_name (def);
 832 }
 833
 834
 835 /* Replace the symbol associated with SSA_NAME with SYM.  */
 836
 837 void
 838 replace_ssa_name_symbol (tree ssa_name, tree sym)
 839 {
 840   SET_SSA_NAME_VAR_OR_IDENTIFIER (ssa_name, sym);
 841   TREE_TYPE (ssa_name) = TREE_TYPE (sym);
 842 }
 843
 844 /* Release the vector of free SSA_NAMEs and compact the vector of SSA_NAMEs
 845    that are live.  */
 846
 847 static void
 848 release_free_names_and_compact_live_names (function *fun)
 849 {
 850   unsigned i, j;
 851   int n = vec_safe_length (FREE_SSANAMES (fun));
 852
 853   /* Now release the freelist.  */
 854   vec_free (FREE_SSANAMES (fun));
 855
 856   /* And compact the SSA number space.  We make sure to not change the
 857      relative order of SSA versions.  */
 858   for (i = 1, j = 1; i < fun->gimple_df->ssa_names->length (); ++i)
 859     {
 860       tree name = ssa_name (i);
 861       if (name)
 862         {
 863           if (i != j)
 864             {
 865               SSA_NAME_VERSION (name) = j;
 866               (*fun->gimple_df->ssa_names)[j] = name;
 867             }
 868           j++;
 869         }
 870     }
 871   fun->gimple_df->ssa_names->truncate (j);
 872
 873   statistics_counter_event (fun, "SSA names released", n);
 874   statistics_counter_event (fun, "SSA name holes removed", i - j);
 875   if (dump_file)
 876     fprintf (dump_file, "Released %i names, %.2f%%, removed %i holes\n",
 877              n, n * 100.0 / num_ssa_names, i - j);
 878 }
 879
 880 /* Return SSA names that are unused to GGC memory and compact the SSA
 881    version namespace.  This is used to keep footprint of compiler during
 882    interprocedural optimization.  */
 883
 884 namespace {
 885
 886 const pass_data pass_data_release_ssa_names =
 887 {
 888   GIMPLE_PASS, /* type */
 889   "release_ssa", /* name */
 890   OPTGROUP_NONE, /* optinfo_flags */
 891   TV_TREE_SSA_OTHER, /* tv_id */
 892   PROP_ssa, /* properties_required */
 893   0, /* properties_provided */
 894   0, /* properties_destroyed */
 895   TODO_remove_unused_locals, /* todo_flags_start */
 896   0, /* todo_flags_finish */
 897 };
 898
 899 class pass_release_ssa_names : public gimple_opt_pass
 900 {
 901 public:
 902   pass_release_ssa_names (gcc::context *ctxt)
 903     : gimple_opt_pass (pass_data_release_ssa_names, ctxt)
 904   {}
 905
 906   /* opt_pass methods: */
 907   virtual unsigned int execute (function *);
 908
 909 }; // class pass_release_ssa_names
 910
 911 unsigned int
 912 pass_release_ssa_names::execute (function *fun)
 913 {
 914   release_free_names_and_compact_live_names (fun);
 915   return 0;
 916 }
 917
 918 } // anon namespace
 919
 920 gimple_opt_pass *
 921 make_pass_release_ssa_names (gcc::context *ctxt)
 922 {
 923   return new pass_release_ssa_names (ctxt);
 924 }