gcc/tree-dfa.c

   1 /* Data flow functions for trees.
   2    Copyright (C) 2001-2018 Free Software Foundation, Inc.
   3    Contributed by Diego Novillo <dnovillo@redhat.com>
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify
   8 it under the terms of the GNU General Public License as published by
   9 the Free Software Foundation; either version 3, or (at your option)
  10 any later version.
  11
  12 GCC is distributed in the hope that it will be useful,
  13 but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 GNU General Public License for more details.
  16
  17 You should have received a copy of the GNU General Public License
  18 along with GCC; see the file COPYING3.  If not see
  19 <http://www.gnu.org/licenses/>.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "backend.h"
  25 #include "rtl.h"
  26 #include "tree.h"
  27 #include "gimple.h"
  28 #include "tree-pass.h"
  29 #include "ssa.h"
  30 #include "tree-pretty-print.h"
  31 #include "fold-const.h"
  32 #include "stor-layout.h"
  33 #include "langhooks.h"
  34 #include "gimple-iterator.h"
  35 #include "gimple-walk.h"
  36 #include "tree-dfa.h"
  37
  38 /* Build and maintain data flow information for trees.  */
  39
  40 /* Counters used to display DFA and SSA statistics.  */
  41 struct dfa_stats_d
  42 {
  43   long num_defs;
  44   long num_uses;
  45   long num_phis;
  46   long num_phi_args;
  47   size_t max_num_phi_args;
  48   long num_vdefs;
  49   long num_vuses;
  50 };
  51
  52
  53 /* Local functions.  */
  54 static void collect_dfa_stats (struct dfa_stats_d *);
  55
  56
  57 /*---------------------------------------------------------------------------
  58                         Dataflow analysis (DFA) routines
  59 ---------------------------------------------------------------------------*/
  60
  61 /* Renumber all of the gimple stmt uids.  */
  62
  63 void
  64 renumber_gimple_stmt_uids (void)
  65 {
  66   basic_block bb;
  67
  68   set_gimple_stmt_max_uid (cfun, 0);
  69   FOR_ALL_BB_FN (bb, cfun)
  70     {
  71       gimple_stmt_iterator bsi;
  72       for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi))
  73         {
  74           gimple *stmt = gsi_stmt (bsi);
  75           gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
  76         }
  77       for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
  78         {
  79           gimple *stmt = gsi_stmt (bsi);
  80           gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
  81         }
  82     }
  83 }
  84
  85 /* Like renumber_gimple_stmt_uids, but only do work on the basic blocks
  86    in BLOCKS, of which there are N_BLOCKS.  Also renumbers PHIs.  */
  87
  88 void
  89 renumber_gimple_stmt_uids_in_blocks (basic_block *blocks, int n_blocks)
  90 {
  91   int i;
  92
  93   set_gimple_stmt_max_uid (cfun, 0);
  94   for (i = 0; i < n_blocks; i++)
  95     {
  96       basic_block bb = blocks[i];
  97       gimple_stmt_iterator bsi;
  98       for (bsi = gsi_start_phis (bb); !gsi_end_p (bsi); gsi_next (&bsi))
  99         {
 100           gimple *stmt = gsi_stmt (bsi);
 101           gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
 102         }
 103       for (bsi = gsi_start_bb (bb); !gsi_end_p (bsi); gsi_next (&bsi))
 104         {
 105           gimple *stmt = gsi_stmt (bsi);
 106           gimple_set_uid (stmt, inc_gimple_stmt_max_uid (cfun));
 107         }
 108     }
 109 }
 110
 111
 112
 113 /*---------------------------------------------------------------------------
 114                               Debugging functions
 115 ---------------------------------------------------------------------------*/
 116
 117 /* Dump variable VAR and its may-aliases to FILE.  */
 118
 119 void
 120 dump_variable (FILE *file, tree var)
 121 {
 122   if (TREE_CODE (var) == SSA_NAME)
 123     {
 124       if (POINTER_TYPE_P (TREE_TYPE (var)))
 125         dump_points_to_info_for (file, var);
 126       var = SSA_NAME_VAR (var);
 127     }
 128
 129   if (var == NULL_TREE)
 130     {
 131       fprintf (file, "<nil>");
 132       return;
 133     }
 134
 135   print_generic_expr (file, var, dump_flags);
 136
 137   fprintf (file, ", UID D.%u", (unsigned) DECL_UID (var));
 138   if (DECL_PT_UID (var) != DECL_UID (var))
 139     fprintf (file, ", PT-UID D.%u", (unsigned) DECL_PT_UID (var));
 140
 141   fprintf (file, ", ");
 142   print_generic_expr (file, TREE_TYPE (var), dump_flags);
 143
 144   if (TREE_ADDRESSABLE (var))
 145     fprintf (file, ", is addressable");
 146
 147   if (is_global_var (var))
 148     fprintf (file, ", is global");
 149
 150   if (TREE_THIS_VOLATILE (var))
 151     fprintf (file, ", is volatile");
 152
 153   if (cfun && ssa_default_def (cfun, var))
 154     {
 155       fprintf (file, ", default def: ");
 156       print_generic_expr (file, ssa_default_def (cfun, var), dump_flags);
 157     }
 158
 159   if (DECL_INITIAL (var))
 160     {
 161       fprintf (file, ", initial: ");
 162       print_generic_expr (file, DECL_INITIAL (var), dump_flags);
 163     }
 164
 165   fprintf (file, "\n");
 166 }
 167
 168
 169 /* Dump variable VAR and its may-aliases to stderr.  */
 170
 171 DEBUG_FUNCTION void
 172 debug_variable (tree var)
 173 {
 174   dump_variable (stderr, var);
 175 }
 176
 177
 178 /* Dump various DFA statistics to FILE.  */
 179
 180 void
 181 dump_dfa_stats (FILE *file)
 182 {
 183   struct dfa_stats_d dfa_stats;
 184
 185   unsigned long size, total = 0;
 186   const char * const fmt_str   = "%-30s%-13s%12s\n";
 187   const char * const fmt_str_1 = "%-30s%13lu%11lu%c\n";
 188   const char * const fmt_str_3 = "%-43s%11lu%c\n";
 189   const char *funcname
 190     = lang_hooks.decl_printable_name (current_function_decl, 2);
 191
 192   collect_dfa_stats (&dfa_stats);
 193
 194   fprintf (file, "\nDFA Statistics for %s\n\n", funcname);
 195
 196   fprintf (file, "---------------------------------------------------------\n");
 197   fprintf (file, fmt_str, "", "  Number of  ", "Memory");
 198   fprintf (file, fmt_str, "", "  instances  ", "used ");
 199   fprintf (file, "---------------------------------------------------------\n");
 200
 201   size = dfa_stats.num_uses * sizeof (tree *);
 202   total += size;
 203   fprintf (file, fmt_str_1, "USE operands", dfa_stats.num_uses,
 204            SCALE (size), LABEL (size));
 205
 206   size = dfa_stats.num_defs * sizeof (tree *);
 207   total += size;
 208   fprintf (file, fmt_str_1, "DEF operands", dfa_stats.num_defs,
 209            SCALE (size), LABEL (size));
 210
 211   size = dfa_stats.num_vuses * sizeof (tree *);
 212   total += size;
 213   fprintf (file, fmt_str_1, "VUSE operands", dfa_stats.num_vuses,
 214            SCALE (size), LABEL (size));
 215
 216   size = dfa_stats.num_vdefs * sizeof (tree *);
 217   total += size;
 218   fprintf (file, fmt_str_1, "VDEF operands", dfa_stats.num_vdefs,
 219            SCALE (size), LABEL (size));
 220
 221   size = dfa_stats.num_phis * sizeof (struct gphi);
 222   total += size;
 223   fprintf (file, fmt_str_1, "PHI nodes", dfa_stats.num_phis,
 224            SCALE (size), LABEL (size));
 225
 226   size = dfa_stats.num_phi_args * sizeof (struct phi_arg_d);
 227   total += size;
 228   fprintf (file, fmt_str_1, "PHI arguments", dfa_stats.num_phi_args,
 229            SCALE (size), LABEL (size));
 230
 231   fprintf (file, "---------------------------------------------------------\n");
 232   fprintf (file, fmt_str_3, "Total memory used by DFA/SSA data", SCALE (total),
 233            LABEL (total));
 234   fprintf (file, "---------------------------------------------------------\n");
 235   fprintf (file, "\n");
 236
 237   if (dfa_stats.num_phis)
 238     fprintf (file, "Average number of arguments per PHI node: %.1f (max: %ld)\n",
 239              (float) dfa_stats.num_phi_args / (float) dfa_stats.num_phis,
 240              (long) dfa_stats.max_num_phi_args);
 241
 242   fprintf (file, "\n");
 243 }
 244
 245
 246 /* Dump DFA statistics on stderr.  */
 247
 248 DEBUG_FUNCTION void
 249 debug_dfa_stats (void)
 250 {
 251   dump_dfa_stats (stderr);
 252 }
 253
 254
 255 /* Collect DFA statistics and store them in the structure pointed to by
 256    DFA_STATS_P.  */
 257
 258 static void
 259 collect_dfa_stats (struct dfa_stats_d *dfa_stats_p ATTRIBUTE_UNUSED)
 260 {
 261   basic_block bb;
 262
 263   gcc_assert (dfa_stats_p);
 264
 265   memset ((void *)dfa_stats_p, 0, sizeof (struct dfa_stats_d));
 266
 267   /* Walk all the statements in the function counting references.  */
 268   FOR_EACH_BB_FN (bb, cfun)
 269     {
 270       for (gphi_iterator si = gsi_start_phis (bb); !gsi_end_p (si);
 271            gsi_next (&si))
 272         {
 273           gphi *phi = si.phi ();
 274           dfa_stats_p->num_phis++;
 275           dfa_stats_p->num_phi_args += gimple_phi_num_args (phi);
 276           if (gimple_phi_num_args (phi) > dfa_stats_p->max_num_phi_args)
 277             dfa_stats_p->max_num_phi_args = gimple_phi_num_args (phi);
 278         }
 279
 280       for (gimple_stmt_iterator si = gsi_start_bb (bb); !gsi_end_p (si);
 281            gsi_next (&si))
 282         {
 283           gimple *stmt = gsi_stmt (si);
 284           dfa_stats_p->num_defs += NUM_SSA_OPERANDS (stmt, SSA_OP_DEF);
 285           dfa_stats_p->num_uses += NUM_SSA_OPERANDS (stmt, SSA_OP_USE);
 286           dfa_stats_p->num_vdefs += gimple_vdef (stmt) ? 1 : 0;
 287           dfa_stats_p->num_vuses += gimple_vuse (stmt) ? 1 : 0;
 288         }
 289     }
 290 }
 291
 292
 293 /*---------------------------------------------------------------------------
 294                              Miscellaneous helpers
 295 ---------------------------------------------------------------------------*/
 296
 297 /* Lookup VAR UID in the default_defs hashtable and return the associated
 298    variable.  */
 299
 300 tree
 301 ssa_default_def (struct function *fn, tree var)
 302 {
 303   struct tree_decl_minimal ind;
 304   struct tree_ssa_name in;
 305   gcc_assert (VAR_P (var)
 306               || TREE_CODE (var) == PARM_DECL
 307               || TREE_CODE (var) == RESULT_DECL);
 308
 309   /* Always NULL_TREE for rtl function dumps.  */
 310   if (!fn->gimple_df)
 311     return NULL_TREE;
 312
 313   in.var = (tree)&ind;
 314   ind.uid = DECL_UID (var);
 315   return DEFAULT_DEFS (fn)->find_with_hash ((tree)&in, DECL_UID (var));
 316 }
 317
 318 /* Insert the pair VAR's UID, DEF into the default_defs hashtable
 319    of function FN.  */
 320
 321 void
 322 set_ssa_default_def (struct function *fn, tree var, tree def)
 323 {
 324   struct tree_decl_minimal ind;
 325   struct tree_ssa_name in;
 326
 327   gcc_assert (VAR_P (var)
 328               || TREE_CODE (var) == PARM_DECL
 329               || TREE_CODE (var) == RESULT_DECL);
 330   in.var = (tree)&ind;
 331   ind.uid = DECL_UID (var);
 332   if (!def)
 333     {
 334       tree *loc = DEFAULT_DEFS (fn)->find_slot_with_hash ((tree)&in,
 335                                                           DECL_UID (var),
 336                                                           NO_INSERT);
 337       if (loc)
 338         {
 339           SSA_NAME_IS_DEFAULT_DEF (*(tree *)loc) = false;
 340           DEFAULT_DEFS (fn)->clear_slot (loc);
 341         }
 342       return;
 343     }
 344   gcc_assert (TREE_CODE (def) == SSA_NAME && SSA_NAME_VAR (def) == var);
 345   tree *loc = DEFAULT_DEFS (fn)->find_slot_with_hash ((tree)&in,
 346                                                       DECL_UID (var), INSERT);
 347
 348   /* Default definition might be changed by tail call optimization.  */
 349   if (*loc)
 350     SSA_NAME_IS_DEFAULT_DEF (*loc) = false;
 351
 352    /* Mark DEF as the default definition for VAR.  */
 353   *loc = def;
 354   SSA_NAME_IS_DEFAULT_DEF (def) = true;
 355 }
 356
 357 /* Retrieve or create a default definition for VAR.  */
 358
 359 tree
 360 get_or_create_ssa_default_def (struct function *fn, tree var)
 361 {
 362   tree ddef = ssa_default_def (fn, var);
 363   if (ddef == NULL_TREE)
 364     {
 365       ddef = make_ssa_name_fn (fn, var, gimple_build_nop ());
 366       set_ssa_default_def (fn, var, ddef);
 367     }
 368   return ddef;
 369 }
 370
 371
 372 /* If EXP is a handled component reference for a structure, return the
 373    base variable.  The access range is delimited by bit positions *POFFSET and
 374    *POFFSET + *PMAX_SIZE.  The access size is *PSIZE bits.  If either
 375    *PSIZE or *PMAX_SIZE is -1, they could not be determined.  If *PSIZE
 376    and *PMAX_SIZE are equal, the access is non-variable.  If *PREVERSE is
 377    true, the storage order of the reference is reversed.  */
 378
 379 tree
 380 get_ref_base_and_extent (tree exp, poly_int64_pod *poffset,
 381                          poly_int64_pod *psize,
 382                          poly_int64_pod *pmax_size,
 383                          bool *preverse)
 384 {
 385   poly_offset_int bitsize = -1;
 386   poly_offset_int maxsize;
 387   tree size_tree = NULL_TREE;
 388   poly_offset_int bit_offset = 0;
 389   bool seen_variable_array_ref = false;
 390
 391   /* First get the final access size and the storage order from just the
 392      outermost expression.  */
 393   if (TREE_CODE (exp) == COMPONENT_REF)
 394     size_tree = DECL_SIZE (TREE_OPERAND (exp, 1));
 395   else if (TREE_CODE (exp) == BIT_FIELD_REF)
 396     size_tree = TREE_OPERAND (exp, 1);
 397   else if (!VOID_TYPE_P (TREE_TYPE (exp)))
 398     {
 399       machine_mode mode = TYPE_MODE (TREE_TYPE (exp));
 400       if (mode == BLKmode)
 401         size_tree = TYPE_SIZE (TREE_TYPE (exp));
 402       else
 403         bitsize = GET_MODE_BITSIZE (mode);
 404     }
 405   if (size_tree != NULL_TREE
 406       && poly_int_tree_p (size_tree))
 407     bitsize = wi::to_poly_offset (size_tree);
 408
 409   *preverse = reverse_storage_order_for_component_p (exp);
 410
 411   /* Initially, maxsize is the same as the accessed element size.
 412      In the following it will only grow (or become -1).  */
 413   maxsize = bitsize;
 414
 415   /* Compute cumulative bit-offset for nested component-refs and array-refs,
 416      and find the ultimate containing object.  */
 417   while (1)
 418     {
 419       switch (TREE_CODE (exp))
 420         {
 421         case BIT_FIELD_REF:
 422           bit_offset += wi::to_poly_offset (TREE_OPERAND (exp, 2));
 423           break;
 424
 425         case COMPONENT_REF:
 426           {
 427             tree field = TREE_OPERAND (exp, 1);
 428             tree this_offset = component_ref_field_offset (exp);
 429
 430             if (this_offset && poly_int_tree_p (this_offset))
 431               {
 432                 poly_offset_int woffset = (wi::to_poly_offset (this_offset)
 433                                            << LOG2_BITS_PER_UNIT);
 434                 woffset += wi::to_offset (DECL_FIELD_BIT_OFFSET (field));
 435                 bit_offset += woffset;
 436
 437                 /* If we had seen a variable array ref already and we just
 438                    referenced the last field of a struct or a union member
 439                    then we have to adjust maxsize by the padding at the end
 440                    of our field.  */
 441                 if (seen_variable_array_ref)
 442                   {
 443                     tree stype = TREE_TYPE (TREE_OPERAND (exp, 0));
 444                     tree next = DECL_CHAIN (field);
 445                     while (next && TREE_CODE (next) != FIELD_DECL)
 446                       next = DECL_CHAIN (next);
 447                     if (!next
 448                         || TREE_CODE (stype) != RECORD_TYPE)
 449                       {
 450                         tree fsize = DECL_SIZE_UNIT (field);
 451                         tree ssize = TYPE_SIZE_UNIT (stype);
 452                         if (fsize == NULL
 453                             || !poly_int_tree_p (fsize)
 454                             || ssize == NULL
 455                             || !poly_int_tree_p (ssize))
 456                           maxsize = -1;
 457                         else if (known_size_p (maxsize))
 458                           {
 459                             poly_offset_int tem
 460                               = (wi::to_poly_offset (ssize)
 461                                  - wi::to_poly_offset (fsize));
 462                             tem <<= LOG2_BITS_PER_UNIT;
 463                             tem -= woffset;
 464                             maxsize += tem;
 465                           }
 466                       }
 467                     /* An component ref with an adjacent field up in the
 468                        structure hierarchy constrains the size of any variable
 469                        array ref lower in the access hierarchy.  */
 470                     else
 471                       seen_variable_array_ref = false;
 472                   }
 473               }
 474             else
 475               {
 476                 tree csize = TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 477                 /* We need to adjust maxsize to the whole structure bitsize.
 478                    But we can subtract any constant offset seen so far,
 479                    because that would get us out of the structure otherwise.  */
 480                 if (known_size_p (maxsize)
 481                     && csize
 482                     && poly_int_tree_p (csize))
 483                   maxsize = wi::to_poly_offset (csize) - bit_offset;
 484                 else
 485                   maxsize = -1;
 486               }
 487           }
 488           break;
 489
 490         case ARRAY_REF:
 491         case ARRAY_RANGE_REF:
 492           {
 493             tree index = TREE_OPERAND (exp, 1);
 494             tree low_bound, unit_size;
 495
 496             /* If the resulting bit-offset is constant, track it.  */
 497             if (poly_int_tree_p (index)
 498                 && (low_bound = array_ref_low_bound (exp),
 499                     poly_int_tree_p (low_bound))
 500                 && (unit_size = array_ref_element_size (exp),
 501                     TREE_CODE (unit_size) == INTEGER_CST))
 502               {
 503                 poly_offset_int woffset
 504                   = wi::sext (wi::to_poly_offset (index)
 505                               - wi::to_poly_offset (low_bound),
 506                               TYPE_PRECISION (TREE_TYPE (index)));
 507                 woffset *= wi::to_offset (unit_size);
 508                 woffset <<= LOG2_BITS_PER_UNIT;
 509                 bit_offset += woffset;
 510
 511                 /* An array ref with a constant index up in the structure
 512                    hierarchy will constrain the size of any variable array ref
 513                    lower in the access hierarchy.  */
 514                 seen_variable_array_ref = false;
 515               }
 516             else
 517               {
 518                 tree asize = TYPE_SIZE (TREE_TYPE (TREE_OPERAND (exp, 0)));
 519                 /* We need to adjust maxsize to the whole array bitsize.
 520                    But we can subtract any constant offset seen so far,
 521                    because that would get us outside of the array otherwise.  */
 522                 if (known_size_p (maxsize)
 523                     && asize
 524                     && poly_int_tree_p (asize))
 525                   maxsize = wi::to_poly_offset (asize) - bit_offset;
 526                 else
 527                   maxsize = -1;
 528
 529                 /* Remember that we have seen an array ref with a variable
 530                    index.  */
 531                 seen_variable_array_ref = true;
 532               }
 533           }
 534           break;
 535
 536         case REALPART_EXPR:
 537           break;
 538
 539         case IMAGPART_EXPR:
 540           bit_offset += bitsize;
 541           break;
 542
 543         case VIEW_CONVERT_EXPR:
 544           break;
 545
 546         case TARGET_MEM_REF:
 547           /* Via the variable index or index2 we can reach the
 548              whole object.  Still hand back the decl here.  */
 549           if (TREE_CODE (TMR_BASE (exp)) == ADDR_EXPR
 550               && (TMR_INDEX (exp) || TMR_INDEX2 (exp)))
 551             {
 552               exp = TREE_OPERAND (TMR_BASE (exp), 0);
 553               bit_offset = 0;
 554               maxsize = -1;
 555               goto done;
 556             }
 557           /* Fallthru.  */
 558         case MEM_REF:
 559           /* We need to deal with variable arrays ending structures such as
 560              struct { int length; int a[1]; } x;           x.a[d]
 561              struct { struct { int a; int b; } a[1]; } x;  x.a[d].a
 562              struct { struct { int a[1]; } a[1]; } x;      x.a[0][d], x.a[d][0]
 563              struct { int len; union { int a[1]; struct X x; } u; } x; x.u.a[d]
 564              where we do not know maxsize for variable index accesses to
 565              the array.  The simplest way to conservatively deal with this
 566              is to punt in the case that offset + maxsize reaches the
 567              base type boundary.  This needs to include possible trailing
 568              padding that is there for alignment purposes.  */
 569           if (seen_variable_array_ref
 570               && known_size_p (maxsize)
 571               && (TYPE_SIZE (TREE_TYPE (exp)) == NULL_TREE
 572                   || !poly_int_tree_p (TYPE_SIZE (TREE_TYPE (exp)))
 573                   || (maybe_eq
 574                       (bit_offset + maxsize,
 575                        wi::to_poly_offset (TYPE_SIZE (TREE_TYPE (exp)))))))
 576             maxsize = -1;
 577
 578           /* Hand back the decl for MEM[&decl, off].  */
 579           if (TREE_CODE (TREE_OPERAND (exp, 0)) == ADDR_EXPR)
 580             {
 581               if (integer_zerop (TREE_OPERAND (exp, 1)))
 582                 exp = TREE_OPERAND (TREE_OPERAND (exp, 0), 0);
 583               else
 584                 {
 585                   poly_offset_int off = mem_ref_offset (exp);
 586                   off <<= LOG2_BITS_PER_UNIT;
 587                   off += bit_offset;
 588                   poly_int64 off_hwi;
 589                   if (off.to_shwi (&off_hwi))
 590                     {
 591                       bit_offset = off_hwi;
 592                       exp = TREE_OPERAND (TREE_OPERAND (exp, 0), 0);
 593                     }
 594                 }
 595             }
 596           goto done;
 597
 598         default:
 599           goto done;
 600         }
 601
 602       exp = TREE_OPERAND (exp, 0);
 603     }
 604
 605  done:
 606   if (!bitsize.to_shwi (psize) || maybe_lt (*psize, 0))
 607     {
 608       *poffset = 0;
 609       *psize = -1;
 610       *pmax_size = -1;
 611
 612       return exp;
 613     }
 614
 615   /* ???  Due to negative offsets in ARRAY_REF we can end up with
 616      negative bit_offset here.  We might want to store a zero offset
 617      in this case.  */
 618   if (!bit_offset.to_shwi (poffset))
 619     {
 620       *poffset = 0;
 621       *pmax_size = -1;
 622
 623       return exp;
 624     }
 625
 626   /* In case of a decl or constant base object we can do better.  */
 627
 628   if (DECL_P (exp))
 629     {
 630       if (VAR_P (exp)
 631           && ((flag_unconstrained_commons && DECL_COMMON (exp))
 632               || (DECL_EXTERNAL (exp) && seen_variable_array_ref)))
 633         {
 634           tree sz_tree = TYPE_SIZE (TREE_TYPE (exp));
 635           /* If size is unknown, or we have read to the end, assume there
 636              may be more to the structure than we are told.  */
 637           if (TREE_CODE (TREE_TYPE (exp)) == ARRAY_TYPE
 638               || (seen_variable_array_ref
 639                   && (sz_tree == NULL_TREE
 640                       || !poly_int_tree_p (sz_tree)
 641                       || maybe_eq (bit_offset + maxsize,
 642                                    wi::to_poly_offset (sz_tree)))))
 643             maxsize = -1;
 644         }
 645       /* If maxsize is unknown adjust it according to the size of the
 646          base decl.  */
 647       else if (!known_size_p (maxsize)
 648                && DECL_SIZE (exp)
 649                && poly_int_tree_p (DECL_SIZE (exp)))
 650         maxsize = wi::to_poly_offset (DECL_SIZE (exp)) - bit_offset;
 651     }
 652   else if (CONSTANT_CLASS_P (exp))
 653     {
 654       /* If maxsize is unknown adjust it according to the size of the
 655          base type constant.  */
 656       if (!known_size_p (maxsize)
 657           && TYPE_SIZE (TREE_TYPE (exp))
 658           && poly_int_tree_p (TYPE_SIZE (TREE_TYPE (exp))))
 659         maxsize = (wi::to_poly_offset (TYPE_SIZE (TREE_TYPE (exp)))
 660                    - bit_offset);
 661     }
 662
 663   if (!maxsize.to_shwi (pmax_size)
 664       || maybe_lt (*pmax_size, 0)
 665       || !endpoint_representable_p (*poffset, *pmax_size))
 666     *pmax_size = -1;
 667
 668   /* Punt if *POFFSET + *PSIZE overflows in HOST_WIDE_INT, the callers don't
 669      check for such overflows individually and assume it works.  */
 670   if (!endpoint_representable_p (*poffset, *psize))
 671     {
 672       *poffset = 0;
 673       *psize = -1;
 674       *pmax_size = -1;
 675
 676       return exp;
 677     }
 678
 679   return exp;
 680 }
 681
 682 /* Like get_ref_base_and_extent, but for cases in which we only care
 683    about constant-width accesses at constant offsets.  Return null
 684    if the access is anything else.  */
 685
 686 tree
 687 get_ref_base_and_extent_hwi (tree exp, HOST_WIDE_INT *poffset,
 688                              HOST_WIDE_INT *psize, bool *preverse)
 689 {
 690   poly_int64 offset, size, max_size;
 691   HOST_WIDE_INT const_offset, const_size;
 692   bool reverse;
 693   tree decl = get_ref_base_and_extent (exp, &offset, &size, &max_size,
 694                                        &reverse);
 695   if (!offset.is_constant (&const_offset)
 696       || !size.is_constant (&const_size)
 697       || const_offset < 0
 698       || !known_size_p (max_size)
 699       || maybe_ne (max_size, const_size))
 700     return NULL_TREE;
 701
 702   *poffset = const_offset;
 703   *psize = const_size;
 704   *preverse = reverse;
 705   return decl;
 706 }
 707
 708 /* Returns the base object and a constant BITS_PER_UNIT offset in *POFFSET that
 709    denotes the starting address of the memory access EXP.
 710    Returns NULL_TREE if the offset is not constant or any component
 711    is not BITS_PER_UNIT-aligned.
 712    VALUEIZE if non-NULL is used to valueize SSA names.  It should return
 713    its argument or a constant if the argument is known to be constant.  */
 714
 715 tree
 716 get_addr_base_and_unit_offset_1 (tree exp, poly_int64_pod *poffset,
 717                                  tree (*valueize) (tree))
 718 {
 719   poly_int64 byte_offset = 0;
 720
 721   /* Compute cumulative byte-offset for nested component-refs and array-refs,
 722      and find the ultimate containing object.  */
 723   while (1)
 724     {
 725       switch (TREE_CODE (exp))
 726         {
 727         case BIT_FIELD_REF:
 728           {
 729             poly_int64 this_byte_offset;
 730             poly_uint64 this_bit_offset;
 731             if (!poly_int_tree_p (TREE_OPERAND (exp, 2), &this_bit_offset)
 732                 || !multiple_p (this_bit_offset, BITS_PER_UNIT,
 733                                 &this_byte_offset))
 734               return NULL_TREE;
 735             byte_offset += this_byte_offset;
 736           }
 737           break;
 738
 739         case COMPONENT_REF:
 740           {
 741             tree field = TREE_OPERAND (exp, 1);
 742             tree this_offset = component_ref_field_offset (exp);
 743             poly_int64 hthis_offset;
 744
 745             if (!this_offset
 746                 || !poly_int_tree_p (this_offset, &hthis_offset)
 747                 || (TREE_INT_CST_LOW (DECL_FIELD_BIT_OFFSET (field))
 748                     % BITS_PER_UNIT))
 749               return NULL_TREE;
 750
 751             hthis_offset += (TREE_INT_CST_LOW (DECL_FIELD_BIT_OFFSET (field))
 752                              / BITS_PER_UNIT);
 753             byte_offset += hthis_offset;
 754           }
 755           break;
 756
 757         case ARRAY_REF:
 758         case ARRAY_RANGE_REF:
 759           {
 760             tree index = TREE_OPERAND (exp, 1);
 761             tree low_bound, unit_size;
 762
 763             if (valueize
 764                 && TREE_CODE (index) == SSA_NAME)
 765               index = (*valueize) (index);
 766
 767             /* If the resulting bit-offset is constant, track it.  */
 768             if (poly_int_tree_p (index)
 769                 && (low_bound = array_ref_low_bound (exp),
 770                     poly_int_tree_p (low_bound))
 771                 && (unit_size = array_ref_element_size (exp),
 772                     TREE_CODE (unit_size) == INTEGER_CST))
 773               {
 774                 poly_offset_int woffset
 775                   = wi::sext (wi::to_poly_offset (index)
 776                               - wi::to_poly_offset (low_bound),
 777                               TYPE_PRECISION (TREE_TYPE (index)));
 778                 woffset *= wi::to_offset (unit_size);
 779                 byte_offset += woffset.force_shwi ();
 780               }
 781             else
 782               return NULL_TREE;
 783           }
 784           break;
 785
 786         case REALPART_EXPR:
 787           break;
 788
 789         case IMAGPART_EXPR:
 790           byte_offset += TREE_INT_CST_LOW (TYPE_SIZE_UNIT (TREE_TYPE (exp)));
 791           break;
 792
 793         case VIEW_CONVERT_EXPR:
 794           break;
 795
 796         case MEM_REF:
 797           {
 798             tree base = TREE_OPERAND (exp, 0);
 799             if (valueize
 800                 && TREE_CODE (base) == SSA_NAME)
 801               base = (*valueize) (base);
 802
 803             /* Hand back the decl for MEM[&decl, off].  */
 804             if (TREE_CODE (base) == ADDR_EXPR)
 805               {
 806                 if (!integer_zerop (TREE_OPERAND (exp, 1)))
 807                   {
 808                     poly_offset_int off = mem_ref_offset (exp);
 809                     byte_offset += off.force_shwi ();
 810                   }
 811                 exp = TREE_OPERAND (base, 0);
 812               }
 813             goto done;
 814           }
 815
 816         case TARGET_MEM_REF:
 817           {
 818             tree base = TREE_OPERAND (exp, 0);
 819             if (valueize
 820                 && TREE_CODE (base) == SSA_NAME)
 821               base = (*valueize) (base);
 822
 823             /* Hand back the decl for MEM[&decl, off].  */
 824             if (TREE_CODE (base) == ADDR_EXPR)
 825               {
 826                 if (TMR_INDEX (exp) || TMR_INDEX2 (exp))
 827                   return NULL_TREE;
 828                 if (!integer_zerop (TMR_OFFSET (exp)))
 829                   {
 830                     poly_offset_int off = mem_ref_offset (exp);
 831                     byte_offset += off.force_shwi ();
 832                   }
 833                 exp = TREE_OPERAND (base, 0);
 834               }
 835             goto done;
 836           }
 837
 838         default:
 839           goto done;
 840         }
 841
 842       exp = TREE_OPERAND (exp, 0);
 843     }
 844 done:
 845
 846   *poffset = byte_offset;
 847   return exp;
 848 }
 849
 850 /* Returns the base object and a constant BITS_PER_UNIT offset in *POFFSET that
 851    denotes the starting address of the memory access EXP.
 852    Returns NULL_TREE if the offset is not constant or any component
 853    is not BITS_PER_UNIT-aligned.  */
 854
 855 tree
 856 get_addr_base_and_unit_offset (tree exp, poly_int64_pod *poffset)
 857 {
 858   return get_addr_base_and_unit_offset_1 (exp, poffset, NULL);
 859 }
 860
 861 /* Returns true if STMT references an SSA_NAME that has
 862    SSA_NAME_OCCURS_IN_ABNORMAL_PHI set, otherwise false.  */
 863
 864 bool
 865 stmt_references_abnormal_ssa_name (gimple *stmt)
 866 {
 867   ssa_op_iter oi;
 868   use_operand_p use_p;
 869
 870   FOR_EACH_SSA_USE_OPERAND (use_p, stmt, oi, SSA_OP_USE)
 871     {
 872       if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (USE_FROM_PTR (use_p)))
 873         return true;
 874     }
 875
 876   return false;
 877 }
 878
 879 /* If STMT takes any abnormal PHI values as input, replace them with
 880    local copies.  */
 881
 882 void
 883 replace_abnormal_ssa_names (gimple *stmt)
 884 {
 885   ssa_op_iter oi;
 886   use_operand_p use_p;
 887
 888   FOR_EACH_SSA_USE_OPERAND (use_p, stmt, oi, SSA_OP_USE)
 889     {
 890       tree op = USE_FROM_PTR (use_p);
 891       if (TREE_CODE (op) == SSA_NAME && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
 892         {
 893           gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
 894           tree new_name = make_ssa_name (TREE_TYPE (op));
 895           gassign *assign = gimple_build_assign (new_name, op);
 896           gsi_insert_before (&gsi, assign, GSI_SAME_STMT);
 897           SET_USE (use_p, new_name);
 898         }
 899     }
 900 }
 901
 902 /* Pair of tree and a sorting index, for dump_enumerated_decls.  */
 903 struct GTY(()) numbered_tree
 904 {
 905   tree t;
 906   int num;
 907 };
 908
 909
 910 /* Compare two declarations references by their DECL_UID / sequence number.
 911    Called via qsort.  */
 912
 913 static int
 914 compare_decls_by_uid (const void *pa, const void *pb)
 915 {
 916   const numbered_tree *nt_a = ((const numbered_tree *)pa);
 917   const numbered_tree *nt_b = ((const numbered_tree *)pb);
 918
 919   if (DECL_UID (nt_a->t) != DECL_UID (nt_b->t))
 920     return  DECL_UID (nt_a->t) - DECL_UID (nt_b->t);
 921   return nt_a->num - nt_b->num;
 922 }
 923
 924 /* Called via walk_gimple_stmt / walk_gimple_op by dump_enumerated_decls.  */
 925 static tree
 926 dump_enumerated_decls_push (tree *tp, int *walk_subtrees, void *data)
 927 {
 928   struct walk_stmt_info *wi = (struct walk_stmt_info *) data;
 929   vec<numbered_tree> *list = (vec<numbered_tree> *) wi->info;
 930   numbered_tree nt;
 931
 932   if (!DECL_P (*tp))
 933     return NULL_TREE;
 934   nt.t = *tp;
 935   nt.num = list->length ();
 936   list->safe_push (nt);
 937   *walk_subtrees = 0;
 938   return NULL_TREE;
 939 }
 940
 941 /* Find all the declarations used by the current function, sort them by uid,
 942    and emit the sorted list.  Each declaration is tagged with a sequence
 943    number indicating when it was found during statement / tree walking,
 944    so that TDF_NOUID comparisons of anonymous declarations are still
 945    meaningful.  Where a declaration was encountered more than once, we
 946    emit only the sequence number of the first encounter.
 947    FILE is the dump file where to output the list and FLAGS is as in
 948    print_generic_expr.  */
 949 void
 950 dump_enumerated_decls (FILE *file, dump_flags_t flags)
 951 {
 952   basic_block bb;
 953   struct walk_stmt_info wi;
 954   auto_vec<numbered_tree, 40> decl_list;
 955
 956   memset (&wi, '\0', sizeof (wi));
 957   wi.info = (void *) &decl_list;
 958   FOR_EACH_BB_FN (bb, cfun)
 959     {
 960       gimple_stmt_iterator gsi;
 961
 962       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
 963         if (!is_gimple_debug (gsi_stmt (gsi)))
 964           walk_gimple_stmt (&gsi, NULL, dump_enumerated_decls_push, &wi);
 965     }
 966   decl_list.qsort (compare_decls_by_uid);
 967   if (decl_list.length ())
 968     {
 969       unsigned ix;
 970       numbered_tree *ntp;
 971       tree last = NULL_TREE;
 972
 973       fprintf (file, "Declarations used by %s, sorted by DECL_UID:\n",
 974                current_function_name ());
 975       FOR_EACH_VEC_ELT (decl_list, ix, ntp)
 976         {
 977           if (ntp->t == last)
 978             continue;
 979           fprintf (file, "%d: ", ntp->num);
 980           print_generic_decl (file, ntp->t, flags);
 981           fprintf (file, "\n");
 982           last = ntp->t;
 983         }
 984     }
 985 }