gcc/tree-ssanames.c

   1 /* Generic routines for manipulating SSA_NAME expressions
   2    Copyright (C) 2003-2016 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   bitmap names_in_il = BITMAP_ALLOC (NULL);
 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   bitmap names_in_freelists = BITMAP_ALLOC (NULL);
 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   bitmap all_names = BITMAP_ALLOC (NULL);
 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   BITMAP_FREE (all_names);
 235   BITMAP_FREE (names_in_freelists);
 236   BITMAP_FREE (names_in_il);
 237 }
 238
 239 /* Move all SSA_NAMEs from FREE_SSA_NAMES_QUEUE to FREE_SSA_NAMES.
 240
 241    We do not, but should have a mode to verify the state of the SSA_NAMEs
 242    lists.  In particular at this point every name must be in the IL,
 243    on the free list or in the queue.  Anything else is an error.  */
 244
 245 void
 246 flush_ssaname_freelist (void)
 247 {
 248   vec_safe_splice (FREE_SSANAMES (cfun), FREE_SSANAMES_QUEUE (cfun));
 249   vec_safe_truncate (FREE_SSANAMES_QUEUE (cfun), 0);
 250 }
 251
 252 /* Return an SSA_NAME node for variable VAR defined in statement STMT
 253    in function FN.  STMT may be an empty statement for artificial
 254    references (e.g., default definitions created when a variable is
 255    used without a preceding definition).  */
 256
 257 tree
 258 make_ssa_name_fn (struct function *fn, tree var, gimple *stmt)
 259 {
 260   tree t;
 261   use_operand_p imm;
 262
 263   gcc_assert (TREE_CODE (var) == VAR_DECL
 264               || TREE_CODE (var) == PARM_DECL
 265               || TREE_CODE (var) == RESULT_DECL
 266               || (TYPE_P (var) && is_gimple_reg_type (var)));
 267
 268   /* If our free list has an element, then use it.  */
 269   if (!vec_safe_is_empty (FREE_SSANAMES (fn)))
 270     {
 271       t = FREE_SSANAMES (fn)->pop ();
 272       ssa_name_nodes_reused++;
 273
 274       /* The node was cleared out when we put it on the free list, so
 275          there is no need to do so again here.  */
 276       gcc_assert ((*SSANAMES (fn))[SSA_NAME_VERSION (t)] == NULL);
 277       (*SSANAMES (fn))[SSA_NAME_VERSION (t)] = t;
 278     }
 279   else
 280     {
 281       t = make_node (SSA_NAME);
 282       SSA_NAME_VERSION (t) = SSANAMES (fn)->length ();
 283       vec_safe_push (SSANAMES (fn), t);
 284       ssa_name_nodes_created++;
 285     }
 286
 287   if (TYPE_P (var))
 288     {
 289       TREE_TYPE (t) = var;
 290       SET_SSA_NAME_VAR_OR_IDENTIFIER (t, NULL_TREE);
 291     }
 292   else
 293     {
 294       TREE_TYPE (t) = TREE_TYPE (var);
 295       SET_SSA_NAME_VAR_OR_IDENTIFIER (t, var);
 296     }
 297   SSA_NAME_DEF_STMT (t) = stmt;
 298   if (POINTER_TYPE_P (TREE_TYPE (t)))
 299     SSA_NAME_PTR_INFO (t) = NULL;
 300   else
 301     SSA_NAME_RANGE_INFO (t) = NULL;
 302
 303   SSA_NAME_IN_FREE_LIST (t) = 0;
 304   SSA_NAME_IS_DEFAULT_DEF (t) = 0;
 305   imm = &(SSA_NAME_IMM_USE_NODE (t));
 306   imm->use = NULL;
 307   imm->prev = imm;
 308   imm->next = imm;
 309   imm->loc.ssa_name = t;
 310
 311   return t;
 312 }
 313
 314 /* Store range information RANGE_TYPE, MIN, and MAX to tree ssa_name NAME.  */
 315
 316 void
 317 set_range_info (tree name, enum value_range_type range_type,
 318                 const wide_int_ref &min, const wide_int_ref &max)
 319 {
 320   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 321   gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
 322   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 323   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 324
 325   /* Allocate if not available.  */
 326   if (ri == NULL)
 327     {
 328       size_t size = (sizeof (range_info_def)
 329                      + trailing_wide_ints <3>::extra_size (precision));
 330       ri = static_cast<range_info_def *> (ggc_internal_alloc (size));
 331       ri->ints.set_precision (precision);
 332       SSA_NAME_RANGE_INFO (name) = ri;
 333       ri->set_nonzero_bits (wi::shwi (-1, precision));
 334     }
 335
 336   /* Record the range type.  */
 337   if (SSA_NAME_RANGE_TYPE (name) != range_type)
 338     SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
 339
 340   /* Set the values.  */
 341   ri->set_min (min);
 342   ri->set_max (max);
 343
 344   /* If it is a range, try to improve nonzero_bits from the min/max.  */
 345   if (range_type == VR_RANGE)
 346     {
 347       wide_int xorv = ri->get_min () ^ ri->get_max ();
 348       if (xorv != 0)
 349         xorv = wi::mask (precision - wi::clz (xorv), false, precision);
 350       ri->set_nonzero_bits (ri->get_nonzero_bits () & (ri->get_min () | xorv));
 351     }
 352 }
 353
 354
 355 /* Gets range information MIN, MAX and returns enum value_range_type
 356    corresponding to tree ssa_name NAME.  enum value_range_type returned
 357    is used to determine if MIN and MAX are valid values.  */
 358
 359 enum value_range_type
 360 get_range_info (const_tree name, wide_int *min, wide_int *max)
 361 {
 362   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 363   gcc_assert (min && max);
 364   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 365
 366   /* Return VR_VARYING for SSA_NAMEs with NULL RANGE_INFO or SSA_NAMEs
 367      with integral types width > 2 * HOST_BITS_PER_WIDE_INT precision.  */
 368   if (!ri || (GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (name)))
 369               > 2 * HOST_BITS_PER_WIDE_INT))
 370     return VR_VARYING;
 371
 372   *min = ri->get_min ();
 373   *max = ri->get_max ();
 374   return SSA_NAME_RANGE_TYPE (name);
 375 }
 376
 377 /* Change non-zero bits bitmask of NAME.  */
 378
 379 void
 380 set_nonzero_bits (tree name, const wide_int_ref &mask)
 381 {
 382   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 383   if (SSA_NAME_RANGE_INFO (name) == NULL)
 384     set_range_info (name, VR_RANGE,
 385                     TYPE_MIN_VALUE (TREE_TYPE (name)),
 386                     TYPE_MAX_VALUE (TREE_TYPE (name)));
 387   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 388   ri->set_nonzero_bits (mask);
 389 }
 390
 391 /* Return a widest_int with potentially non-zero bits in SSA_NAME
 392    NAME, or -1 if unknown.  */
 393
 394 wide_int
 395 get_nonzero_bits (const_tree name)
 396 {
 397   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 398   if (POINTER_TYPE_P (TREE_TYPE (name)))
 399     {
 400       struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
 401       if (pi && pi->align)
 402         return wi::shwi (-(HOST_WIDE_INT) pi->align
 403                          | (HOST_WIDE_INT) pi->misalign, precision);
 404       return wi::shwi (-1, precision);
 405     }
 406
 407   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 408   if (!ri)
 409     return wi::shwi (-1, precision);
 410
 411   return ri->get_nonzero_bits ();
 412 }
 413
 414 /* We no longer need the SSA_NAME expression VAR, release it so that
 415    it may be reused.
 416
 417    Note it is assumed that no calls to make_ssa_name will be made
 418    until all uses of the ssa name are released and that the only
 419    use of the SSA_NAME expression is to check its SSA_NAME_VAR.  All
 420    other fields must be assumed clobbered.  */
 421
 422 void
 423 release_ssa_name_fn (struct function *fn, tree var)
 424 {
 425   if (!var)
 426     return;
 427
 428   /* Never release the default definition for a symbol.  It's a
 429      special SSA name that should always exist once it's created.  */
 430   if (SSA_NAME_IS_DEFAULT_DEF (var))
 431     return;
 432
 433   /* If VAR has been registered for SSA updating, don't remove it.
 434      After update_ssa has run, the name will be released.  */
 435   if (name_registered_for_update_p (var))
 436     {
 437       release_ssa_name_after_update_ssa (var);
 438       return;
 439     }
 440
 441   /* release_ssa_name can be called multiple times on a single SSA_NAME.
 442      However, it should only end up on our free list one time.   We
 443      keep a status bit in the SSA_NAME node itself to indicate it has
 444      been put on the free list.
 445
 446      Note that once on the freelist you can not reference the SSA_NAME's
 447      defining statement.  */
 448   if (! SSA_NAME_IN_FREE_LIST (var))
 449     {
 450       tree saved_ssa_name_var = SSA_NAME_VAR (var);
 451       int saved_ssa_name_version = SSA_NAME_VERSION (var);
 452       use_operand_p imm = &(SSA_NAME_IMM_USE_NODE (var));
 453
 454       if (MAY_HAVE_DEBUG_STMTS)
 455         insert_debug_temp_for_var_def (NULL, var);
 456
 457       if (flag_checking)
 458         verify_imm_links (stderr, var);
 459       while (imm->next != imm)
 460         delink_imm_use (imm->next);
 461
 462       (*SSANAMES (fn))[SSA_NAME_VERSION (var)] = NULL_TREE;
 463       memset (var, 0, tree_size (var));
 464
 465       imm->prev = imm;
 466       imm->next = imm;
 467       imm->loc.ssa_name = var;
 468
 469       /* First put back the right tree node so that the tree checking
 470          macros do not complain.  */
 471       TREE_SET_CODE (var, SSA_NAME);
 472
 473       /* Restore the version number.  */
 474       SSA_NAME_VERSION (var) = saved_ssa_name_version;
 475
 476       /* Hopefully this can go away once we have the new incremental
 477          SSA updating code installed.  */
 478       SET_SSA_NAME_VAR_OR_IDENTIFIER (var, saved_ssa_name_var);
 479
 480       /* Note this SSA_NAME is now in the first list.  */
 481       SSA_NAME_IN_FREE_LIST (var) = 1;
 482
 483       /* And finally queue it so that it will be put on the free list.  */
 484       vec_safe_push (FREE_SSANAMES_QUEUE (fn), var);
 485     }
 486 }
 487
 488 /* If the alignment of the pointer described by PI is known, return true and
 489    store the alignment and the deviation from it into *ALIGNP and *MISALIGNP
 490    respectively.  Otherwise return false.  */
 491
 492 bool
 493 get_ptr_info_alignment (struct ptr_info_def *pi, unsigned int *alignp,
 494                         unsigned int *misalignp)
 495 {
 496   if (pi->align)
 497     {
 498       *alignp = pi->align;
 499       *misalignp = pi->misalign;
 500       return true;
 501     }
 502   else
 503     return false;
 504 }
 505
 506 /* State that the pointer described by PI has unknown alignment.  */
 507
 508 void
 509 mark_ptr_info_alignment_unknown (struct ptr_info_def *pi)
 510 {
 511   pi->align = 0;
 512   pi->misalign = 0;
 513 }
 514
 515 /* Store the power-of-two byte alignment and the deviation from that
 516    alignment of pointer described by PI to ALIOGN and MISALIGN
 517    respectively.  */
 518
 519 void
 520 set_ptr_info_alignment (struct ptr_info_def *pi, unsigned int align,
 521                             unsigned int misalign)
 522 {
 523   gcc_checking_assert (align != 0);
 524   gcc_assert ((align & (align - 1)) == 0);
 525   gcc_assert ((misalign & ~(align - 1)) == 0);
 526
 527   pi->align = align;
 528   pi->misalign = misalign;
 529 }
 530
 531 /* If pointer described by PI has known alignment, increase its known
 532    misalignment by INCREMENT modulo its current alignment.  */
 533
 534 void
 535 adjust_ptr_info_misalignment (struct ptr_info_def *pi,
 536                               unsigned int increment)
 537 {
 538   if (pi->align != 0)
 539     {
 540       pi->misalign += increment;
 541       pi->misalign &= (pi->align - 1);
 542     }
 543 }
 544
 545 /* Return the alias information associated with pointer T.  It creates a
 546    new instance if none existed.  */
 547
 548 struct ptr_info_def *
 549 get_ptr_info (tree t)
 550 {
 551   struct ptr_info_def *pi;
 552
 553   gcc_assert (POINTER_TYPE_P (TREE_TYPE (t)));
 554
 555   pi = SSA_NAME_PTR_INFO (t);
 556   if (pi == NULL)
 557     {
 558       pi = ggc_cleared_alloc<ptr_info_def> ();
 559       pt_solution_reset (&pi->pt);
 560       mark_ptr_info_alignment_unknown (pi);
 561       SSA_NAME_PTR_INFO (t) = pi;
 562     }
 563
 564   return pi;
 565 }
 566
 567
 568 /* Creates a new SSA name using the template NAME tobe defined by
 569    statement STMT in function FN.  */
 570
 571 tree
 572 copy_ssa_name_fn (struct function *fn, tree name, gimple *stmt)
 573 {
 574   tree new_name;
 575
 576   if (SSA_NAME_VAR (name))
 577     new_name = make_ssa_name_fn (fn, SSA_NAME_VAR (name), stmt);
 578   else
 579     {
 580       new_name = make_ssa_name_fn (fn, TREE_TYPE (name), stmt);
 581       SET_SSA_NAME_VAR_OR_IDENTIFIER (new_name, SSA_NAME_IDENTIFIER (name));
 582     }
 583
 584   return new_name;
 585 }
 586
 587
 588 /* Creates a duplicate of the ptr_info_def at PTR_INFO for use by
 589    the SSA name NAME.  */
 590
 591 void
 592 duplicate_ssa_name_ptr_info (tree name, struct ptr_info_def *ptr_info)
 593 {
 594   struct ptr_info_def *new_ptr_info;
 595
 596   gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
 597   gcc_assert (!SSA_NAME_PTR_INFO (name));
 598
 599   if (!ptr_info)
 600     return;
 601
 602   new_ptr_info = ggc_alloc<ptr_info_def> ();
 603   *new_ptr_info = *ptr_info;
 604
 605   SSA_NAME_PTR_INFO (name) = new_ptr_info;
 606 }
 607
 608 /* Creates a duplicate of the range_info_def at RANGE_INFO of type
 609    RANGE_TYPE for use by the SSA name NAME.  */
 610 void
 611 duplicate_ssa_name_range_info (tree name, enum value_range_type range_type,
 612                                struct range_info_def *range_info)
 613 {
 614   struct range_info_def *new_range_info;
 615
 616   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 617   gcc_assert (!SSA_NAME_RANGE_INFO (name));
 618
 619   if (!range_info)
 620     return;
 621
 622   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 623   size_t size = (sizeof (range_info_def)
 624                  + trailing_wide_ints <3>::extra_size (precision));
 625   new_range_info = static_cast<range_info_def *> (ggc_internal_alloc (size));
 626   memcpy (new_range_info, range_info, size);
 627
 628   gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
 629   SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
 630   SSA_NAME_RANGE_INFO (name) = new_range_info;
 631 }
 632
 633
 634
 635 /* Creates a duplicate of a ssa name NAME tobe defined by statement STMT
 636    in function FN.  */
 637
 638 tree
 639 duplicate_ssa_name_fn (struct function *fn, tree name, gimple *stmt)
 640 {
 641   tree new_name = copy_ssa_name_fn (fn, name, stmt);
 642   if (POINTER_TYPE_P (TREE_TYPE (name)))
 643     {
 644       struct ptr_info_def *old_ptr_info = SSA_NAME_PTR_INFO (name);
 645
 646       if (old_ptr_info)
 647         duplicate_ssa_name_ptr_info (new_name, old_ptr_info);
 648     }
 649   else
 650     {
 651       struct range_info_def *old_range_info = SSA_NAME_RANGE_INFO (name);
 652
 653       if (old_range_info)
 654         duplicate_ssa_name_range_info (new_name, SSA_NAME_RANGE_TYPE (name),
 655                                        old_range_info);
 656     }
 657
 658   return new_name;
 659 }
 660
 661
 662 /* Reset all flow sensitive data on NAME such as range-info, nonzero
 663    bits and alignment.  */
 664
 665 void
 666 reset_flow_sensitive_info (tree name)
 667 {
 668   if (POINTER_TYPE_P (TREE_TYPE (name)))
 669     {
 670       /* points-to info is not flow-sensitive.  */
 671       if (SSA_NAME_PTR_INFO (name))
 672         mark_ptr_info_alignment_unknown (SSA_NAME_PTR_INFO (name));
 673     }
 674   else
 675     SSA_NAME_RANGE_INFO (name) = NULL;
 676 }
 677
 678 /* Clear all flow sensitive data from all statements and PHI definitions
 679    in BB.  */
 680
 681 void
 682 reset_flow_sensitive_info_in_bb (basic_block bb)
 683 {
 684   for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);
 685        gsi_next (&gsi))
 686     {
 687       gimple *stmt = gsi_stmt (gsi);
 688       ssa_op_iter i;
 689       tree op;
 690       FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_DEF)
 691         reset_flow_sensitive_info (op);
 692     }
 693
 694   for (gphi_iterator gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
 695        gsi_next (&gsi))
 696     {
 697       tree phi_def = gimple_phi_result (gsi.phi ());
 698       reset_flow_sensitive_info (phi_def);
 699     }
 700 }
 701
 702 /* Release all the SSA_NAMEs created by STMT.  */
 703
 704 void
 705 release_defs (gimple *stmt)
 706 {
 707   tree def;
 708   ssa_op_iter iter;
 709
 710   /* Make sure that we are in SSA.  Otherwise, operand cache may point
 711      to garbage.  */
 712   gcc_assert (gimple_in_ssa_p (cfun));
 713
 714   FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
 715     if (TREE_CODE (def) == SSA_NAME)
 716       release_ssa_name (def);
 717 }
 718
 719
 720 /* Replace the symbol associated with SSA_NAME with SYM.  */
 721
 722 void
 723 replace_ssa_name_symbol (tree ssa_name, tree sym)
 724 {
 725   SET_SSA_NAME_VAR_OR_IDENTIFIER (ssa_name, sym);
 726   TREE_TYPE (ssa_name) = TREE_TYPE (sym);
 727 }
 728
 729 /* Release the vector of free SSA_NAMEs and compact the the
 730    vector of SSA_NAMEs that are live.  */
 731
 732 static void
 733 release_free_names_and_compact_live_names (function *fun)
 734 {
 735   unsigned i, j;
 736   int n = vec_safe_length (FREE_SSANAMES (fun));
 737
 738   /* Now release the freelist.  */
 739   vec_free (FREE_SSANAMES (fun));
 740
 741   /* And compact the SSA number space.  We make sure to not change the
 742      relative order of SSA versions.  */
 743   for (i = 1, j = 1; i < fun->gimple_df->ssa_names->length (); ++i)
 744     {
 745       tree name = ssa_name (i);
 746       if (name)
 747         {
 748           if (i != j)
 749             {
 750               SSA_NAME_VERSION (name) = j;
 751               (*fun->gimple_df->ssa_names)[j] = name;
 752             }
 753           j++;
 754         }
 755     }
 756   fun->gimple_df->ssa_names->truncate (j);
 757
 758   statistics_counter_event (fun, "SSA names released", n);
 759   statistics_counter_event (fun, "SSA name holes removed", i - j);
 760   if (dump_file)
 761     fprintf (dump_file, "Released %i names, %.2f%%, removed %i holes\n",
 762              n, n * 100.0 / num_ssa_names, i - j);
 763 }
 764
 765 /* Return SSA names that are unused to GGC memory and compact the SSA
 766    version namespace.  This is used to keep footprint of compiler during
 767    interprocedural optimization.  */
 768
 769 namespace {
 770
 771 const pass_data pass_data_release_ssa_names =
 772 {
 773   GIMPLE_PASS, /* type */
 774   "release_ssa", /* name */
 775   OPTGROUP_NONE, /* optinfo_flags */
 776   TV_TREE_SSA_OTHER, /* tv_id */
 777   PROP_ssa, /* properties_required */
 778   0, /* properties_provided */
 779   0, /* properties_destroyed */
 780   TODO_remove_unused_locals, /* todo_flags_start */
 781   0, /* todo_flags_finish */
 782 };
 783
 784 class pass_release_ssa_names : public gimple_opt_pass
 785 {
 786 public:
 787   pass_release_ssa_names (gcc::context *ctxt)
 788     : gimple_opt_pass (pass_data_release_ssa_names, ctxt)
 789   {}
 790
 791   /* opt_pass methods: */
 792   virtual unsigned int execute (function *);
 793
 794 }; // class pass_release_ssa_names
 795
 796 unsigned int
 797 pass_release_ssa_names::execute (function *fun)
 798 {
 799   release_free_names_and_compact_live_names (fun);
 800   return 0;
 801 }
 802
 803 } // anon namespace
 804
 805 gimple_opt_pass *
 806 make_pass_release_ssa_names (gcc::context *ctxt)
 807 {
 808   return new pass_release_ssa_names (ctxt);
 809 }