gcc/tree-ssa-copy.c

   1 /* Copy propagation and SSA_NAME replacement support routines.
   2    Copyright (C) 2004-2013 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 "tm.h"
  24 #include "tree.h"
  25 #include "flags.h"
  26 #include "tm_p.h"
  27 #include "basic-block.h"
  28 #include "function.h"
  29 #include "gimple-pretty-print.h"
  30 #include "tree-ssa-alias.h"
  31 #include "internal-fn.h"
  32 #include "gimple-expr.h"
  33 #include "is-a.h"
  34 #include "gimple.h"
  35 #include "gimple-iterator.h"
  36 #include "gimple-ssa.h"
  37 #include "tree-cfg.h"
  38 #include "tree-phinodes.h"
  39 #include "ssa-iterators.h"
  40 #include "stringpool.h"
  41 #include "tree-ssanames.h"
  42 #include "tree-pass.h"
  43 #include "tree-ssa-propagate.h"
  44 #include "langhooks.h"
  45 #include "cfgloop.h"
  46 #include "tree-scalar-evolution.h"
  47 #include "tree-ssa-dom.h"
  48
  49 /* This file implements the copy propagation pass and provides a
  50    handful of interfaces for performing const/copy propagation and
  51    simple expression replacement which keep variable annotations
  52    up-to-date.
  53
  54    We require that for any copy operation where the RHS and LHS have
  55    a non-null memory tag the memory tag be the same.   It is OK
  56    for one or both of the memory tags to be NULL.
  57
  58    We also require tracking if a variable is dereferenced in a load or
  59    store operation.
  60
  61    We enforce these requirements by having all copy propagation and
  62    replacements of one SSA_NAME with a different SSA_NAME to use the
  63    APIs defined in this file.  */
  64
  65 /*---------------------------------------------------------------------------
  66                                 Copy propagation
  67 ---------------------------------------------------------------------------*/
  68 /* Lattice for copy-propagation.  The lattice is initialized to
  69    UNDEFINED (value == NULL) for SSA names that can become a copy
  70    of something or VARYING (value == self) if not (see get_copy_of_val
  71    and stmt_may_generate_copy).  Other values make the name a COPY
  72    of that value.
  73
  74    When visiting a statement or PHI node the lattice value for an
  75    SSA name can transition from UNDEFINED to COPY to VARYING.  */
  76
  77 struct prop_value_d {
  78     /* Copy-of value.  */
  79     tree value;
  80 };
  81 typedef struct prop_value_d prop_value_t;
  82
  83 static prop_value_t *copy_of;
  84 static unsigned n_copy_of;
  85
  86
  87 /* Return true if this statement may generate a useful copy.  */
  88
  89 static bool
  90 stmt_may_generate_copy (gimple stmt)
  91 {
  92   if (gimple_code (stmt) == GIMPLE_PHI)
  93     return !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_phi_result (stmt));
  94
  95   if (gimple_code (stmt) != GIMPLE_ASSIGN)
  96     return false;
  97
  98   /* If the statement has volatile operands, it won't generate a
  99      useful copy.  */
 100   if (gimple_has_volatile_ops (stmt))
 101     return false;
 102
 103   /* Statements with loads and/or stores will never generate a useful copy.  */
 104   if (gimple_vuse (stmt))
 105     return false;
 106
 107   /* Otherwise, the only statements that generate useful copies are
 108      assignments whose RHS is just an SSA name that doesn't flow
 109      through abnormal edges.  */
 110   return ((gimple_assign_rhs_code (stmt) == SSA_NAME
 111            && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt)))
 112           || is_gimple_min_invariant (gimple_assign_rhs1 (stmt)));
 113 }
 114
 115
 116 /* Return the copy-of value for VAR.  */
 117
 118 static inline prop_value_t *
 119 get_copy_of_val (tree var)
 120 {
 121   prop_value_t *val = &copy_of[SSA_NAME_VERSION (var)];
 122
 123   if (val->value == NULL_TREE
 124       && !stmt_may_generate_copy (SSA_NAME_DEF_STMT (var)))
 125     {
 126       /* If the variable will never generate a useful copy relation,
 127          make it its own copy.  */
 128       val->value = var;
 129     }
 130
 131   return val;
 132 }
 133
 134 /* Return the variable VAR is a copy of or VAR if VAR isn't the result
 135    of a copy.  */
 136
 137 static inline tree
 138 valueize_val (tree var)
 139 {
 140   if (TREE_CODE (var) == SSA_NAME)
 141     {
 142       tree val = get_copy_of_val (var)->value;
 143       if (val)
 144         return val;
 145     }
 146   return var;
 147 }
 148
 149 /* Set VAL to be the copy of VAR.  If that changed return true.  */
 150
 151 static inline bool
 152 set_copy_of_val (tree var, tree val)
 153 {
 154   unsigned int ver = SSA_NAME_VERSION (var);
 155   tree old;
 156
 157   /* Set FIRST to be the first link in COPY_OF[DEST].  If that
 158      changed, return true.  */
 159   old = copy_of[ver].value;
 160   copy_of[ver].value = val;
 161
 162   if (old != val
 163       || (val && !operand_equal_p (old, val, 0)))
 164     return true;
 165
 166   return false;
 167 }
 168
 169
 170 /* Dump the copy-of value for variable VAR to FILE.  */
 171
 172 static void
 173 dump_copy_of (FILE *file, tree var)
 174 {
 175   tree val;
 176
 177   print_generic_expr (file, var, dump_flags);
 178   if (TREE_CODE (var) != SSA_NAME)
 179     return;
 180
 181   val = copy_of[SSA_NAME_VERSION (var)].value;
 182   fprintf (file, " copy-of chain: ");
 183   print_generic_expr (file, var, 0);
 184   fprintf (file, " ");
 185   if (!val)
 186     fprintf (file, "[UNDEFINED]");
 187   else if (val == var)
 188     fprintf (file, "[NOT A COPY]");
 189   else
 190     {
 191       fprintf (file, "-> ");
 192       print_generic_expr (file, val, 0);
 193       fprintf (file, " ");
 194       fprintf (file, "[COPY]");
 195     }
 196 }
 197
 198
 199 /* Evaluate the RHS of STMT.  If it produces a valid copy, set the LHS
 200    value and store the LHS into *RESULT_P.  */
 201
 202 static enum ssa_prop_result
 203 copy_prop_visit_assignment (gimple stmt, tree *result_p)
 204 {
 205   tree lhs, rhs;
 206
 207   lhs = gimple_assign_lhs (stmt);
 208   rhs = valueize_val (gimple_assign_rhs1 (stmt));
 209
 210   if (TREE_CODE (lhs) == SSA_NAME)
 211     {
 212       /* Straight copy between two SSA names.  First, make sure that
 213          we can propagate the RHS into uses of LHS.  */
 214       if (!may_propagate_copy (lhs, rhs))
 215         return SSA_PROP_VARYING;
 216
 217       *result_p = lhs;
 218       if (set_copy_of_val (*result_p, rhs))
 219         return SSA_PROP_INTERESTING;
 220       else
 221         return SSA_PROP_NOT_INTERESTING;
 222     }
 223
 224   return SSA_PROP_VARYING;
 225 }
 226
 227
 228 /* Visit the GIMPLE_COND STMT.  Return SSA_PROP_INTERESTING
 229    if it can determine which edge will be taken.  Otherwise, return
 230    SSA_PROP_VARYING.  */
 231
 232 static enum ssa_prop_result
 233 copy_prop_visit_cond_stmt (gimple stmt, edge *taken_edge_p)
 234 {
 235   enum ssa_prop_result retval = SSA_PROP_VARYING;
 236   location_t loc = gimple_location (stmt);
 237
 238   tree op0 = gimple_cond_lhs (stmt);
 239   tree op1 = gimple_cond_rhs (stmt);
 240
 241   /* The only conditionals that we may be able to compute statically
 242      are predicates involving two SSA_NAMEs.  */
 243   if (TREE_CODE (op0) == SSA_NAME && TREE_CODE (op1) == SSA_NAME)
 244     {
 245       op0 = valueize_val (op0);
 246       op1 = valueize_val (op1);
 247
 248       /* See if we can determine the predicate's value.  */
 249       if (dump_file && (dump_flags & TDF_DETAILS))
 250         {
 251           fprintf (dump_file, "Trying to determine truth value of ");
 252           fprintf (dump_file, "predicate ");
 253           print_gimple_stmt (dump_file, stmt, 0, 0);
 254         }
 255
 256       /* We can fold COND and get a useful result only when we have
 257          the same SSA_NAME on both sides of a comparison operator.  */
 258       if (op0 == op1)
 259         {
 260           tree folded_cond = fold_binary_loc (loc, gimple_cond_code (stmt),
 261                                           boolean_type_node, op0, op1);
 262           if (folded_cond)
 263             {
 264               basic_block bb = gimple_bb (stmt);
 265               *taken_edge_p = find_taken_edge (bb, folded_cond);
 266               if (*taken_edge_p)
 267                 retval = SSA_PROP_INTERESTING;
 268             }
 269         }
 270     }
 271
 272   if (dump_file && (dump_flags & TDF_DETAILS) && *taken_edge_p)
 273     fprintf (dump_file, "\nConditional will always take edge %d->%d\n",
 274              (*taken_edge_p)->src->index, (*taken_edge_p)->dest->index);
 275
 276   return retval;
 277 }
 278
 279
 280 /* Evaluate statement STMT.  If the statement produces a new output
 281    value, return SSA_PROP_INTERESTING and store the SSA_NAME holding
 282    the new value in *RESULT_P.
 283
 284    If STMT is a conditional branch and we can determine its truth
 285    value, set *TAKEN_EDGE_P accordingly.
 286
 287    If the new value produced by STMT is varying, return
 288    SSA_PROP_VARYING.  */
 289
 290 static enum ssa_prop_result
 291 copy_prop_visit_stmt (gimple stmt, edge *taken_edge_p, tree *result_p)
 292 {
 293   enum ssa_prop_result retval;
 294
 295   if (dump_file && (dump_flags & TDF_DETAILS))
 296     {
 297       fprintf (dump_file, "\nVisiting statement:\n");
 298       print_gimple_stmt (dump_file, stmt, 0, dump_flags);
 299       fprintf (dump_file, "\n");
 300     }
 301
 302   if (gimple_assign_single_p (stmt)
 303       && TREE_CODE (gimple_assign_lhs (stmt)) == SSA_NAME
 304       && (TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
 305           || is_gimple_min_invariant (gimple_assign_rhs1 (stmt))))
 306     {
 307       /* If the statement is a copy assignment, evaluate its RHS to
 308          see if the lattice value of its output has changed.  */
 309       retval = copy_prop_visit_assignment (stmt, result_p);
 310     }
 311   else if (gimple_code (stmt) == GIMPLE_COND)
 312     {
 313       /* See if we can determine which edge goes out of a conditional
 314          jump.  */
 315       retval = copy_prop_visit_cond_stmt (stmt, taken_edge_p);
 316     }
 317   else
 318     retval = SSA_PROP_VARYING;
 319
 320   if (retval == SSA_PROP_VARYING)
 321     {
 322       tree def;
 323       ssa_op_iter i;
 324
 325       /* Any other kind of statement is not interesting for constant
 326          propagation and, therefore, not worth simulating.  */
 327       if (dump_file && (dump_flags & TDF_DETAILS))
 328         fprintf (dump_file, "No interesting values produced.\n");
 329
 330       /* The assignment is not a copy operation.  Don't visit this
 331          statement again and mark all the definitions in the statement
 332          to be copies of nothing.  */
 333       FOR_EACH_SSA_TREE_OPERAND (def, stmt, i, SSA_OP_ALL_DEFS)
 334         set_copy_of_val (def, def);
 335     }
 336
 337   return retval;
 338 }
 339
 340
 341 /* Visit PHI node PHI.  If all the arguments produce the same value,
 342    set it to be the value of the LHS of PHI.  */
 343
 344 static enum ssa_prop_result
 345 copy_prop_visit_phi_node (gimple phi)
 346 {
 347   enum ssa_prop_result retval;
 348   unsigned i;
 349   prop_value_t phi_val = { NULL_TREE };
 350
 351   tree lhs = gimple_phi_result (phi);
 352
 353   if (dump_file && (dump_flags & TDF_DETAILS))
 354     {
 355       fprintf (dump_file, "\nVisiting PHI node: ");
 356       print_gimple_stmt (dump_file, phi, 0, dump_flags);
 357     }
 358
 359   for (i = 0; i < gimple_phi_num_args (phi); i++)
 360     {
 361       prop_value_t *arg_val;
 362       tree arg_value;
 363       tree arg = gimple_phi_arg_def (phi, i);
 364       edge e = gimple_phi_arg_edge (phi, i);
 365
 366       /* We don't care about values flowing through non-executable
 367          edges.  */
 368       if (!(e->flags & EDGE_EXECUTABLE))
 369         continue;
 370
 371       /* Names that flow through abnormal edges cannot be used to
 372          derive copies.  */
 373       if (TREE_CODE (arg) == SSA_NAME && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (arg))
 374         {
 375           phi_val.value = lhs;
 376           break;
 377         }
 378
 379       if (dump_file && (dump_flags & TDF_DETAILS))
 380         {
 381           fprintf (dump_file, "\tArgument #%d: ", i);
 382           dump_copy_of (dump_file, arg);
 383           fprintf (dump_file, "\n");
 384         }
 385
 386       if (TREE_CODE (arg) == SSA_NAME)
 387         {
 388           arg_val = get_copy_of_val (arg);
 389
 390           /* If we didn't visit the definition of arg yet treat it as
 391              UNDEFINED.  This also handles PHI arguments that are the
 392              same as lhs.  We'll come here again.  */
 393           if (!arg_val->value)
 394             continue;
 395
 396           arg_value = arg_val->value;
 397         }
 398       else
 399         arg_value = valueize_val (arg);
 400
 401       /* Avoid copy propagation from an inner into an outer loop.
 402          Otherwise, this may move loop variant variables outside of
 403          their loops and prevent coalescing opportunities.  If the
 404          value was loop invariant, it will be hoisted by LICM and
 405          exposed for copy propagation.
 406          ???  The value will be always loop invariant.
 407          In loop-closed SSA form do not copy-propagate through
 408          PHI nodes in blocks with a loop exit edge predecessor.  */
 409       if (current_loops
 410           && TREE_CODE (arg_value) == SSA_NAME
 411           && (loop_depth_of_name (arg_value) > loop_depth_of_name (lhs)
 412               || (loops_state_satisfies_p (LOOP_CLOSED_SSA)
 413                   && loop_exit_edge_p (e->src->loop_father, e))))
 414         {
 415           phi_val.value = lhs;
 416           break;
 417         }
 418
 419       /* If the LHS didn't have a value yet, make it a copy of the
 420          first argument we find.   */
 421       if (phi_val.value == NULL_TREE)
 422         {
 423           phi_val.value = arg_value;
 424           continue;
 425         }
 426
 427       /* If PHI_VAL and ARG don't have a common copy-of chain, then
 428          this PHI node cannot be a copy operation.  */
 429       if (phi_val.value != arg_value
 430           && !operand_equal_p (phi_val.value, arg_value, 0))
 431         {
 432           phi_val.value = lhs;
 433           break;
 434         }
 435     }
 436
 437   if (phi_val.value
 438       && may_propagate_copy (lhs, phi_val.value)
 439       && set_copy_of_val (lhs, phi_val.value))
 440     retval = (phi_val.value != lhs) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
 441   else
 442     retval = SSA_PROP_NOT_INTERESTING;
 443
 444   if (dump_file && (dump_flags & TDF_DETAILS))
 445     {
 446       fprintf (dump_file, "PHI node ");
 447       dump_copy_of (dump_file, lhs);
 448       fprintf (dump_file, "\nTelling the propagator to ");
 449       if (retval == SSA_PROP_INTERESTING)
 450         fprintf (dump_file, "add SSA edges out of this PHI and continue.");
 451       else if (retval == SSA_PROP_VARYING)
 452         fprintf (dump_file, "add SSA edges out of this PHI and never visit again.");
 453       else
 454         fprintf (dump_file, "do nothing with SSA edges and keep iterating.");
 455       fprintf (dump_file, "\n\n");
 456     }
 457
 458   return retval;
 459 }
 460
 461
 462 /* Initialize structures used for copy propagation.  */
 463
 464 static void
 465 init_copy_prop (void)
 466 {
 467   basic_block bb;
 468
 469   n_copy_of = num_ssa_names;
 470   copy_of = XCNEWVEC (prop_value_t, n_copy_of);
 471
 472   FOR_EACH_BB_FN (bb, cfun)
 473     {
 474       gimple_stmt_iterator si;
 475       int depth = bb_loop_depth (bb);
 476
 477       for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
 478         {
 479           gimple stmt = gsi_stmt (si);
 480           ssa_op_iter iter;
 481           tree def;
 482
 483           /* The only statements that we care about are those that may
 484              generate useful copies.  We also need to mark conditional
 485              jumps so that their outgoing edges are added to the work
 486              lists of the propagator.
 487
 488              Avoid copy propagation from an inner into an outer loop.
 489              Otherwise, this may move loop variant variables outside of
 490              their loops and prevent coalescing opportunities.  If the
 491              value was loop invariant, it will be hoisted by LICM and
 492              exposed for copy propagation.
 493              ???  This doesn't make sense.  */
 494           if (stmt_ends_bb_p (stmt))
 495             prop_set_simulate_again (stmt, true);
 496           else if (stmt_may_generate_copy (stmt)
 497                    /* Since we are iterating over the statements in
 498                       BB, not the phi nodes, STMT will always be an
 499                       assignment.  */
 500                    && loop_depth_of_name (gimple_assign_rhs1 (stmt)) <= depth)
 501             prop_set_simulate_again (stmt, true);
 502           else
 503             prop_set_simulate_again (stmt, false);
 504
 505           /* Mark all the outputs of this statement as not being
 506              the copy of anything.  */
 507           FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
 508             if (!prop_simulate_again_p (stmt))
 509               set_copy_of_val (def, def);
 510         }
 511
 512       for (si = gsi_start_phis (bb); !gsi_end_p (si); gsi_next (&si))
 513         {
 514           gimple phi = gsi_stmt (si);
 515           tree def;
 516
 517           def = gimple_phi_result (phi);
 518           if (virtual_operand_p (def))
 519             prop_set_simulate_again (phi, false);
 520           else
 521             prop_set_simulate_again (phi, true);
 522
 523           if (!prop_simulate_again_p (phi))
 524             set_copy_of_val (def, def);
 525         }
 526     }
 527 }
 528
 529 /* Callback for substitute_and_fold to get at the final copy-of values.  */
 530
 531 static tree
 532 get_value (tree name)
 533 {
 534   tree val;
 535   if (SSA_NAME_VERSION (name) >= n_copy_of)
 536     return NULL_TREE;
 537   val = copy_of[SSA_NAME_VERSION (name)].value;
 538   if (val && val != name)
 539     return val;
 540   return NULL_TREE;
 541 }
 542
 543 /* Deallocate memory used in copy propagation and do final
 544    substitution.  */
 545
 546 static void
 547 fini_copy_prop (void)
 548 {
 549   unsigned i;
 550
 551   /* Set the final copy-of value for each variable by traversing the
 552      copy-of chains.  */
 553   for (i = 1; i < num_ssa_names; i++)
 554     {
 555       tree var = ssa_name (i);
 556       if (!var
 557           || !copy_of[i].value
 558           || copy_of[i].value == var)
 559         continue;
 560
 561       /* In theory the points-to solution of all members of the
 562          copy chain is their intersection.  For now we do not bother
 563          to compute this but only make sure we do not lose points-to
 564          information completely by setting the points-to solution
 565          of the representative to the first solution we find if
 566          it doesn't have one already.  */
 567       if (copy_of[i].value != var
 568           && TREE_CODE (copy_of[i].value) == SSA_NAME)
 569         {
 570           basic_block copy_of_bb
 571             = gimple_bb (SSA_NAME_DEF_STMT (copy_of[i].value));
 572           basic_block var_bb = gimple_bb (SSA_NAME_DEF_STMT (var));
 573           if (POINTER_TYPE_P (TREE_TYPE (var))
 574               && SSA_NAME_PTR_INFO (var)
 575               && !SSA_NAME_PTR_INFO (copy_of[i].value))
 576             {
 577               duplicate_ssa_name_ptr_info (copy_of[i].value,
 578                                            SSA_NAME_PTR_INFO (var));
 579               /* Points-to information is cfg insensitive,
 580                  but alignment info might be cfg sensitive, if it
 581                  e.g. is derived from VRP derived non-zero bits.
 582                  So, do not copy alignment info if the two SSA_NAMEs
 583                  aren't defined in the same basic block.  */
 584               if (var_bb != copy_of_bb)
 585                 mark_ptr_info_alignment_unknown
 586                                 (SSA_NAME_PTR_INFO (copy_of[i].value));
 587             }
 588           else if (!POINTER_TYPE_P (TREE_TYPE (var))
 589                    && SSA_NAME_RANGE_INFO (var)
 590                    && !SSA_NAME_RANGE_INFO (copy_of[i].value)
 591                    && var_bb == copy_of_bb)
 592             duplicate_ssa_name_range_info (copy_of[i].value,
 593                                            SSA_NAME_RANGE_TYPE (var),
 594                                            SSA_NAME_RANGE_INFO (var));
 595         }
 596     }
 597
 598   /* Don't do DCE if SCEV is initialized.  It would destroy the scev cache.  */
 599   substitute_and_fold (get_value, NULL, !scev_initialized_p ());
 600
 601   free (copy_of);
 602 }
 603
 604
 605 /* Main entry point to the copy propagator.
 606
 607    PHIS_ONLY is true if we should only consider PHI nodes as generating
 608    copy propagation opportunities.
 609
 610    The algorithm propagates the value COPY-OF using ssa_propagate.  For
 611    every variable X_i, COPY-OF(X_i) indicates which variable is X_i created
 612    from.  The following example shows how the algorithm proceeds at a
 613    high level:
 614
 615             1   a_24 = x_1
 616             2   a_2 = PHI <a_24, x_1>
 617             3   a_5 = PHI <a_2>
 618             4   x_1 = PHI <x_298, a_5, a_2>
 619
 620    The end result should be that a_2, a_5, a_24 and x_1 are a copy of
 621    x_298.  Propagation proceeds as follows.
 622
 623    Visit #1: a_24 is copy-of x_1.  Value changed.
 624    Visit #2: a_2 is copy-of x_1.  Value changed.
 625    Visit #3: a_5 is copy-of x_1.  Value changed.
 626    Visit #4: x_1 is copy-of x_298.  Value changed.
 627    Visit #1: a_24 is copy-of x_298.  Value changed.
 628    Visit #2: a_2 is copy-of x_298.  Value changed.
 629    Visit #3: a_5 is copy-of x_298.  Value changed.
 630    Visit #4: x_1 is copy-of x_298.  Stable state reached.
 631
 632    When visiting PHI nodes, we only consider arguments that flow
 633    through edges marked executable by the propagation engine.  So,
 634    when visiting statement #2 for the first time, we will only look at
 635    the first argument (a_24) and optimistically assume that its value
 636    is the copy of a_24 (x_1).  */
 637
 638 static unsigned int
 639 execute_copy_prop (void)
 640 {
 641   init_copy_prop ();
 642   ssa_propagate (copy_prop_visit_stmt, copy_prop_visit_phi_node);
 643   fini_copy_prop ();
 644   return 0;
 645 }
 646
 647 static bool
 648 gate_copy_prop (void)
 649 {
 650   return flag_tree_copy_prop != 0;
 651 }
 652
 653 namespace {
 654
 655 const pass_data pass_data_copy_prop =
 656 {
 657   GIMPLE_PASS, /* type */
 658   "copyprop", /* name */
 659   OPTGROUP_NONE, /* optinfo_flags */
 660   true, /* has_gate */
 661   true, /* has_execute */
 662   TV_TREE_COPY_PROP, /* tv_id */
 663   ( PROP_ssa | PROP_cfg ), /* properties_required */
 664   0, /* properties_provided */
 665   0, /* properties_destroyed */
 666   0, /* todo_flags_start */
 667   ( TODO_cleanup_cfg | TODO_verify_ssa
 668     | TODO_update_ssa ), /* todo_flags_finish */
 669 };
 670
 671 class pass_copy_prop : public gimple_opt_pass
 672 {
 673 public:
 674   pass_copy_prop (gcc::context *ctxt)
 675     : gimple_opt_pass (pass_data_copy_prop, ctxt)
 676   {}
 677
 678   /* opt_pass methods: */
 679   opt_pass * clone () { return new pass_copy_prop (m_ctxt); }
 680   bool gate () { return gate_copy_prop (); }
 681   unsigned int execute () { return execute_copy_prop (); }
 682
 683 }; // class pass_copy_prop
 684
 685 } // anon namespace
 686
 687 gimple_opt_pass *
 688 make_pass_copy_prop (gcc::context *ctxt)
 689 {
 690   return new pass_copy_prop (ctxt);
 691 }