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 /* Store range information RANGE_TYPE, MIN, and MAX to tree ssa_name NAME.  */
 324
 325 void
 326 set_range_info (tree name, enum value_range_type range_type,
 327                 const wide_int_ref &min, const wide_int_ref &max)
 328 {
 329   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 330   gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
 331   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 332   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 333
 334   /* Allocate if not available.  */
 335   if (ri == NULL)
 336     {
 337       size_t size = (sizeof (range_info_def)
 338                      + trailing_wide_ints <3>::extra_size (precision));
 339       ri = static_cast<range_info_def *> (ggc_internal_alloc (size));
 340       ri->ints.set_precision (precision);
 341       SSA_NAME_RANGE_INFO (name) = ri;
 342       ri->set_nonzero_bits (wi::shwi (-1, precision));
 343     }
 344
 345   /* Record the range type.  */
 346   if (SSA_NAME_RANGE_TYPE (name) != range_type)
 347     SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
 348
 349   /* Set the values.  */
 350   ri->set_min (min);
 351   ri->set_max (max);
 352
 353   /* If it is a range, try to improve nonzero_bits from the min/max.  */
 354   if (range_type == VR_RANGE)
 355     {
 356       wide_int xorv = ri->get_min () ^ ri->get_max ();
 357       if (xorv != 0)
 358         xorv = wi::mask (precision - wi::clz (xorv), false, precision);
 359       ri->set_nonzero_bits (ri->get_nonzero_bits () & (ri->get_min () | xorv));
 360     }
 361 }
 362
 363
 364 /* Gets range information MIN, MAX and returns enum value_range_type
 365    corresponding to tree ssa_name NAME.  enum value_range_type returned
 366    is used to determine if MIN and MAX are valid values.  */
 367
 368 enum value_range_type
 369 get_range_info (const_tree name, wide_int *min, wide_int *max)
 370 {
 371   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 372   gcc_assert (min && max);
 373   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 374
 375   /* Return VR_VARYING for SSA_NAMEs with NULL RANGE_INFO or SSA_NAMEs
 376      with integral types width > 2 * HOST_BITS_PER_WIDE_INT precision.  */
 377   if (!ri || (GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (name)))
 378               > 2 * HOST_BITS_PER_WIDE_INT))
 379     return VR_VARYING;
 380
 381   *min = ri->get_min ();
 382   *max = ri->get_max ();
 383   return SSA_NAME_RANGE_TYPE (name);
 384 }
 385
 386 /* Set nonnull attribute to pointer NAME.  */
 387
 388 void
 389 set_ptr_nonnull (tree name)
 390 {
 391   gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
 392   struct ptr_info_def *pi = get_ptr_info (name);
 393   pi->pt.null = 0;
 394 }
 395
 396 /* Return nonnull attribute of pointer NAME.  */
 397 bool
 398 get_ptr_nonnull (const_tree name)
 399 {
 400   gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
 401   struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
 402   if (pi == NULL)
 403     return false;
 404   /* TODO Now pt->null is conservatively set to true in PTA
 405      analysis. vrp is the only pass (including ipa-vrp)
 406      that clears pt.null via set_ptr_nonull when it knows
 407      for sure. PTA will preserves the pt.null value set by VRP.
 408
 409      When PTA analysis is improved, pt.anything, pt.nonlocal
 410      and pt.escaped may also has to be considered before
 411      deciding that pointer cannot point to NULL.  */
 412   return !pi->pt.null;
 413 }
 414
 415 /* Change non-zero bits bitmask of NAME.  */
 416
 417 void
 418 set_nonzero_bits (tree name, const wide_int_ref &mask)
 419 {
 420   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 421   if (SSA_NAME_RANGE_INFO (name) == NULL)
 422     set_range_info (name, VR_RANGE,
 423                     TYPE_MIN_VALUE (TREE_TYPE (name)),
 424                     TYPE_MAX_VALUE (TREE_TYPE (name)));
 425   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 426   ri->set_nonzero_bits (mask);
 427 }
 428
 429 /* Return a widest_int with potentially non-zero bits in SSA_NAME
 430    NAME, the constant for INTEGER_CST, or -1 if unknown.  */
 431
 432 wide_int
 433 get_nonzero_bits (const_tree name)
 434 {
 435   if (TREE_CODE (name) == INTEGER_CST)
 436     return name;
 437
 438   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 439   if (POINTER_TYPE_P (TREE_TYPE (name)))
 440     {
 441       struct ptr_info_def *pi = SSA_NAME_PTR_INFO (name);
 442       if (pi && pi->align)
 443         return wi::shwi (-(HOST_WIDE_INT) pi->align
 444                          | (HOST_WIDE_INT) pi->misalign, precision);
 445       return wi::shwi (-1, precision);
 446     }
 447
 448   range_info_def *ri = SSA_NAME_RANGE_INFO (name);
 449   if (!ri)
 450     return wi::shwi (-1, precision);
 451
 452   return ri->get_nonzero_bits ();
 453 }
 454
 455 /* Return TRUE is OP, an SSA_NAME has a range of values [0..1], false
 456    otherwise.
 457
 458    This can be because it is a boolean type, any unsigned integral
 459    type with a single bit of precision, or has known range of [0..1]
 460    via VRP analysis.  */
 461
 462 bool
 463 ssa_name_has_boolean_range (tree op)
 464 {
 465   gcc_assert (TREE_CODE (op) == SSA_NAME);
 466
 467   /* Boolean types always have a range [0..1].  */
 468   if (TREE_CODE (TREE_TYPE (op)) == BOOLEAN_TYPE)
 469     return true;
 470
 471   /* An integral type with a single bit of precision.  */
 472   if (INTEGRAL_TYPE_P (TREE_TYPE (op))
 473       && TYPE_UNSIGNED (TREE_TYPE (op))
 474       && TYPE_PRECISION (TREE_TYPE (op)) == 1)
 475     return true;
 476
 477   /* An integral type with more precision, but the object
 478      only takes on values [0..1] as determined by VRP
 479      analysis.  */
 480   if (INTEGRAL_TYPE_P (TREE_TYPE (op))
 481       && (TYPE_PRECISION (TREE_TYPE (op)) > 1)
 482       && wi::eq_p (get_nonzero_bits (op), 1))
 483     return true;
 484
 485   return false;
 486 }
 487
 488 /* We no longer need the SSA_NAME expression VAR, release it so that
 489    it may be reused.
 490
 491    Note it is assumed that no calls to make_ssa_name will be made
 492    until all uses of the ssa name are released and that the only
 493    use of the SSA_NAME expression is to check its SSA_NAME_VAR.  All
 494    other fields must be assumed clobbered.  */
 495
 496 void
 497 release_ssa_name_fn (struct function *fn, tree var)
 498 {
 499   if (!var)
 500     return;
 501
 502   /* Never release the default definition for a symbol.  It's a
 503      special SSA name that should always exist once it's created.  */
 504   if (SSA_NAME_IS_DEFAULT_DEF (var))
 505     return;
 506
 507   /* If VAR has been registered for SSA updating, don't remove it.
 508      After update_ssa has run, the name will be released.  */
 509   if (name_registered_for_update_p (var))
 510     {
 511       release_ssa_name_after_update_ssa (var);
 512       return;
 513     }
 514
 515   /* release_ssa_name can be called multiple times on a single SSA_NAME.
 516      However, it should only end up on our free list one time.   We
 517      keep a status bit in the SSA_NAME node itself to indicate it has
 518      been put on the free list.
 519
 520      Note that once on the freelist you can not reference the SSA_NAME's
 521      defining statement.  */
 522   if (! SSA_NAME_IN_FREE_LIST (var))
 523     {
 524       tree saved_ssa_name_var = SSA_NAME_VAR (var);
 525       int saved_ssa_name_version = SSA_NAME_VERSION (var);
 526       use_operand_p imm = &(SSA_NAME_IMM_USE_NODE (var));
 527
 528       if (MAY_HAVE_DEBUG_STMTS)
 529         insert_debug_temp_for_var_def (NULL, var);
 530
 531       if (flag_checking)
 532         verify_imm_links (stderr, var);
 533       while (imm->next != imm)
 534         delink_imm_use (imm->next);
 535
 536       (*SSANAMES (fn))[SSA_NAME_VERSION (var)] = NULL_TREE;
 537       memset (var, 0, tree_size (var));
 538
 539       imm->prev = imm;
 540       imm->next = imm;
 541       imm->loc.ssa_name = var;
 542
 543       /* First put back the right tree node so that the tree checking
 544          macros do not complain.  */
 545       TREE_SET_CODE (var, SSA_NAME);
 546
 547       /* Restore the version number.  */
 548       SSA_NAME_VERSION (var) = saved_ssa_name_version;
 549
 550       /* Hopefully this can go away once we have the new incremental
 551          SSA updating code installed.  */
 552       SET_SSA_NAME_VAR_OR_IDENTIFIER (var, saved_ssa_name_var);
 553
 554       /* Note this SSA_NAME is now in the first list.  */
 555       SSA_NAME_IN_FREE_LIST (var) = 1;
 556
 557       /* And finally queue it so that it will be put on the free list.  */
 558       vec_safe_push (FREE_SSANAMES_QUEUE (fn), var);
 559     }
 560 }
 561
 562 /* If the alignment of the pointer described by PI is known, return true and
 563    store the alignment and the deviation from it into *ALIGNP and *MISALIGNP
 564    respectively.  Otherwise return false.  */
 565
 566 bool
 567 get_ptr_info_alignment (struct ptr_info_def *pi, unsigned int *alignp,
 568                         unsigned int *misalignp)
 569 {
 570   if (pi->align)
 571     {
 572       *alignp = pi->align;
 573       *misalignp = pi->misalign;
 574       return true;
 575     }
 576   else
 577     return false;
 578 }
 579
 580 /* State that the pointer described by PI has unknown alignment.  */
 581
 582 void
 583 mark_ptr_info_alignment_unknown (struct ptr_info_def *pi)
 584 {
 585   pi->align = 0;
 586   pi->misalign = 0;
 587 }
 588
 589 /* Store the power-of-two byte alignment and the deviation from that
 590    alignment of pointer described by PI to ALIOGN and MISALIGN
 591    respectively.  */
 592
 593 void
 594 set_ptr_info_alignment (struct ptr_info_def *pi, unsigned int align,
 595                             unsigned int misalign)
 596 {
 597   gcc_checking_assert (align != 0);
 598   gcc_assert ((align & (align - 1)) == 0);
 599   gcc_assert ((misalign & ~(align - 1)) == 0);
 600
 601   pi->align = align;
 602   pi->misalign = misalign;
 603 }
 604
 605 /* If pointer described by PI has known alignment, increase its known
 606    misalignment by INCREMENT modulo its current alignment.  */
 607
 608 void
 609 adjust_ptr_info_misalignment (struct ptr_info_def *pi,
 610                               unsigned int increment)
 611 {
 612   if (pi->align != 0)
 613     {
 614       pi->misalign += increment;
 615       pi->misalign &= (pi->align - 1);
 616     }
 617 }
 618
 619 /* Return the alias information associated with pointer T.  It creates a
 620    new instance if none existed.  */
 621
 622 struct ptr_info_def *
 623 get_ptr_info (tree t)
 624 {
 625   struct ptr_info_def *pi;
 626
 627   gcc_assert (POINTER_TYPE_P (TREE_TYPE (t)));
 628
 629   pi = SSA_NAME_PTR_INFO (t);
 630   if (pi == NULL)
 631     {
 632       pi = ggc_cleared_alloc<ptr_info_def> ();
 633       pt_solution_reset (&pi->pt);
 634       mark_ptr_info_alignment_unknown (pi);
 635       SSA_NAME_PTR_INFO (t) = pi;
 636     }
 637
 638   return pi;
 639 }
 640
 641
 642 /* Creates a new SSA name using the template NAME tobe defined by
 643    statement STMT in function FN.  */
 644
 645 tree
 646 copy_ssa_name_fn (struct function *fn, tree name, gimple *stmt)
 647 {
 648   tree new_name;
 649
 650   if (SSA_NAME_VAR (name))
 651     new_name = make_ssa_name_fn (fn, SSA_NAME_VAR (name), stmt);
 652   else
 653     {
 654       new_name = make_ssa_name_fn (fn, TREE_TYPE (name), stmt);
 655       SET_SSA_NAME_VAR_OR_IDENTIFIER (new_name, SSA_NAME_IDENTIFIER (name));
 656     }
 657
 658   return new_name;
 659 }
 660
 661
 662 /* Creates a duplicate of the ptr_info_def at PTR_INFO for use by
 663    the SSA name NAME.  */
 664
 665 void
 666 duplicate_ssa_name_ptr_info (tree name, struct ptr_info_def *ptr_info)
 667 {
 668   struct ptr_info_def *new_ptr_info;
 669
 670   gcc_assert (POINTER_TYPE_P (TREE_TYPE (name)));
 671   gcc_assert (!SSA_NAME_PTR_INFO (name));
 672
 673   if (!ptr_info)
 674     return;
 675
 676   new_ptr_info = ggc_alloc<ptr_info_def> ();
 677   *new_ptr_info = *ptr_info;
 678
 679   SSA_NAME_PTR_INFO (name) = new_ptr_info;
 680 }
 681
 682 /* Creates a duplicate of the range_info_def at RANGE_INFO of type
 683    RANGE_TYPE for use by the SSA name NAME.  */
 684 void
 685 duplicate_ssa_name_range_info (tree name, enum value_range_type range_type,
 686                                struct range_info_def *range_info)
 687 {
 688   struct range_info_def *new_range_info;
 689
 690   gcc_assert (!POINTER_TYPE_P (TREE_TYPE (name)));
 691   gcc_assert (!SSA_NAME_RANGE_INFO (name));
 692
 693   if (!range_info)
 694     return;
 695
 696   unsigned int precision = TYPE_PRECISION (TREE_TYPE (name));
 697   size_t size = (sizeof (range_info_def)
 698                  + trailing_wide_ints <3>::extra_size (precision));
 699   new_range_info = static_cast<range_info_def *> (ggc_internal_alloc (size));
 700   memcpy (new_range_info, range_info, size);
 701
 702   gcc_assert (range_type == VR_RANGE || range_type == VR_ANTI_RANGE);
 703   SSA_NAME_ANTI_RANGE_P (name) = (range_type == VR_ANTI_RANGE);
 704   SSA_NAME_RANGE_INFO (name) = new_range_info;
 705 }
 706
 707
 708
 709 /* Creates a duplicate of a ssa name NAME tobe defined by statement STMT
 710    in function FN.  */
 711
 712 tree
 713 duplicate_ssa_name_fn (struct function *fn, tree name, gimple *stmt)
 714 {
 715   tree new_name = copy_ssa_name_fn (fn, name, stmt);
 716   if (POINTER_TYPE_P (TREE_TYPE (name)))
 717     {
 718       struct ptr_info_def *old_ptr_info = SSA_NAME_PTR_INFO (name);
 719
 720       if (old_ptr_info)
 721         duplicate_ssa_name_ptr_info (new_name, old_ptr_info);
 722     }
 723   else
 724     {
 725       struct range_info_def *old_range_info = SSA_NAME_RANGE_INFO (name);
 726
 727       if (old_range_info)
 728         duplicate_ssa_name_range_info (new_name, SSA_NAME_RANGE_TYPE (name),
 729                                        old_range_info);
 730     }
 731
 732   return new_name;
 733 }
 734
 735
 736 /* Reset all flow sensitive data on NAME such as range-info, nonzero
 737    bits and alignment.  */
 738
 739 void
 740 reset_flow_sensitive_info (tree name)
 741 {
 742   if (POINTER_TYPE_P (TREE_TYPE (name)))
 743     {
 744       /* points-to info is not flow-sensitive.  */
 745       if (SSA_NAME_PTR_INFO (name))
 746         mark_ptr_info_alignment_unknown (SSA_NAME_PTR_INFO (name));
 747     }
 748   else
 749     SSA_NAME_RANGE_INFO (name) = NULL;
 750 }
 751
 752 /* Clear all flow sensitive data from all statements and PHI definitions
 753    in BB.  */
 754
 755 void
 756 reset_flow_sensitive_info_in_bb (basic_block bb)
 757 {
 758   for (gimple_stmt_iterator gsi = gsi_start_bb (bb); !gsi_end_p (gsi);
 759        gsi_next (&gsi))
 760     {
 761       gimple *stmt = gsi_stmt (gsi);
 762       ssa_op_iter i;
 763       tree op;
 764       FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_DEF)
 765         reset_flow_sensitive_info (op);
 766     }
 767
 768   for (gphi_iterator gsi = gsi_start_phis (bb); !gsi_end_p (gsi);
 769        gsi_next (&gsi))
 770     {
 771       tree phi_def = gimple_phi_result (gsi.phi ());
 772       reset_flow_sensitive_info (phi_def);
 773     }
 774 }
 775
 776 /* Release all the SSA_NAMEs created by STMT.  */
 777
 778 void
 779 release_defs (gimple *stmt)
 780 {
 781   tree def;
 782   ssa_op_iter iter;
 783
 784   FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
 785     if (TREE_CODE (def) == SSA_NAME)
 786       release_ssa_name (def);
 787 }
 788
 789
 790 /* Replace the symbol associated with SSA_NAME with SYM.  */
 791
 792 void
 793 replace_ssa_name_symbol (tree ssa_name, tree sym)
 794 {
 795   SET_SSA_NAME_VAR_OR_IDENTIFIER (ssa_name, sym);
 796   TREE_TYPE (ssa_name) = TREE_TYPE (sym);
 797 }
 798
 799 /* Release the vector of free SSA_NAMEs and compact the vector of SSA_NAMEs
 800    that are live.  */
 801
 802 static void
 803 release_free_names_and_compact_live_names (function *fun)
 804 {
 805   unsigned i, j;
 806   int n = vec_safe_length (FREE_SSANAMES (fun));
 807
 808   /* Now release the freelist.  */
 809   vec_free (FREE_SSANAMES (fun));
 810
 811   /* And compact the SSA number space.  We make sure to not change the
 812      relative order of SSA versions.  */
 813   for (i = 1, j = 1; i < fun->gimple_df->ssa_names->length (); ++i)
 814     {
 815       tree name = ssa_name (i);
 816       if (name)
 817         {
 818           if (i != j)
 819             {
 820               SSA_NAME_VERSION (name) = j;
 821               (*fun->gimple_df->ssa_names)[j] = name;
 822             }
 823           j++;
 824         }
 825     }
 826   fun->gimple_df->ssa_names->truncate (j);
 827
 828   statistics_counter_event (fun, "SSA names released", n);
 829   statistics_counter_event (fun, "SSA name holes removed", i - j);
 830   if (dump_file)
 831     fprintf (dump_file, "Released %i names, %.2f%%, removed %i holes\n",
 832              n, n * 100.0 / num_ssa_names, i - j);
 833 }
 834
 835 /* Return SSA names that are unused to GGC memory and compact the SSA
 836    version namespace.  This is used to keep footprint of compiler during
 837    interprocedural optimization.  */
 838
 839 namespace {
 840
 841 const pass_data pass_data_release_ssa_names =
 842 {
 843   GIMPLE_PASS, /* type */
 844   "release_ssa", /* name */
 845   OPTGROUP_NONE, /* optinfo_flags */
 846   TV_TREE_SSA_OTHER, /* tv_id */
 847   PROP_ssa, /* properties_required */
 848   0, /* properties_provided */
 849   0, /* properties_destroyed */
 850   TODO_remove_unused_locals, /* todo_flags_start */
 851   0, /* todo_flags_finish */
 852 };
 853
 854 class pass_release_ssa_names : public gimple_opt_pass
 855 {
 856 public:
 857   pass_release_ssa_names (gcc::context *ctxt)
 858     : gimple_opt_pass (pass_data_release_ssa_names, ctxt)
 859   {}
 860
 861   /* opt_pass methods: */
 862   virtual unsigned int execute (function *);
 863
 864 }; // class pass_release_ssa_names
 865
 866 unsigned int
 867 pass_release_ssa_names::execute (function *fun)
 868 {
 869   release_free_names_and_compact_live_names (fun);
 870   return 0;
 871 }
 872
 873 } // anon namespace
 874
 875 gimple_opt_pass *
 876 make_pass_release_ssa_names (gcc::context *ctxt)
 877 {
 878   return new pass_release_ssa_names (ctxt);
 879 }