gcc/tree-ssa-forwprop.c

   1 /* Forward propagation of expressions for single use variables.
   2    Copyright (C) 2004, 2005, 2007, 2008, 2009, 2010, 2011
   3    Free Software Foundation, Inc.
   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 "tm.h"
  25 #include "tree.h"
  26 #include "tm_p.h"
  27 #include "basic-block.h"
  28 #include "timevar.h"
  29 #include "gimple-pretty-print.h"
  30 #include "tree-flow.h"
  31 #include "tree-pass.h"
  32 #include "tree-dump.h"
  33 #include "langhooks.h"
  34 #include "flags.h"
  35 #include "gimple.h"
  36 #include "expr.h"
  37
  38 /* This pass propagates the RHS of assignment statements into use
  39    sites of the LHS of the assignment.  It's basically a specialized
  40    form of tree combination.   It is hoped all of this can disappear
  41    when we have a generalized tree combiner.
  42
  43    One class of common cases we handle is forward propagating a single use
  44    variable into a COND_EXPR.
  45
  46      bb0:
  47        x = a COND b;
  48        if (x) goto ... else goto ...
  49
  50    Will be transformed into:
  51
  52      bb0:
  53        if (a COND b) goto ... else goto ...
  54
  55    Similarly for the tests (x == 0), (x != 0), (x == 1) and (x != 1).
  56
  57    Or (assuming c1 and c2 are constants):
  58
  59      bb0:
  60        x = a + c1;
  61        if (x EQ/NEQ c2) goto ... else goto ...
  62
  63    Will be transformed into:
  64
  65      bb0:
  66         if (a EQ/NEQ (c2 - c1)) goto ... else goto ...
  67
  68    Similarly for x = a - c1.
  69
  70    Or
  71
  72      bb0:
  73        x = !a
  74        if (x) goto ... else goto ...
  75
  76    Will be transformed into:
  77
  78      bb0:
  79         if (a == 0) goto ... else goto ...
  80
  81    Similarly for the tests (x == 0), (x != 0), (x == 1) and (x != 1).
  82    For these cases, we propagate A into all, possibly more than one,
  83    COND_EXPRs that use X.
  84
  85    Or
  86
  87      bb0:
  88        x = (typecast) a
  89        if (x) goto ... else goto ...
  90
  91    Will be transformed into:
  92
  93      bb0:
  94         if (a != 0) goto ... else goto ...
  95
  96    (Assuming a is an integral type and x is a boolean or x is an
  97     integral and a is a boolean.)
  98
  99    Similarly for the tests (x == 0), (x != 0), (x == 1) and (x != 1).
 100    For these cases, we propagate A into all, possibly more than one,
 101    COND_EXPRs that use X.
 102
 103    In addition to eliminating the variable and the statement which assigns
 104    a value to the variable, we may be able to later thread the jump without
 105    adding insane complexity in the dominator optimizer.
 106
 107    Also note these transformations can cascade.  We handle this by having
 108    a worklist of COND_EXPR statements to examine.  As we make a change to
 109    a statement, we put it back on the worklist to examine on the next
 110    iteration of the main loop.
 111
 112    A second class of propagation opportunities arises for ADDR_EXPR
 113    nodes.
 114
 115      ptr = &x->y->z;
 116      res = *ptr;
 117
 118    Will get turned into
 119
 120      res = x->y->z;
 121
 122    Or
 123      ptr = (type1*)&type2var;
 124      res = *ptr
 125
 126    Will get turned into (if type1 and type2 are the same size
 127    and neither have volatile on them):
 128      res = VIEW_CONVERT_EXPR<type1>(type2var)
 129
 130    Or
 131
 132      ptr = &x[0];
 133      ptr2 = ptr + <constant>;
 134
 135    Will get turned into
 136
 137      ptr2 = &x[constant/elementsize];
 138
 139   Or
 140
 141      ptr = &x[0];
 142      offset = index * element_size;
 143      offset_p = (pointer) offset;
 144      ptr2 = ptr + offset_p
 145
 146   Will get turned into:
 147
 148      ptr2 = &x[index];
 149
 150   Or
 151     ssa = (int) decl
 152     res = ssa & 1
 153
 154   Provided that decl has known alignment >= 2, will get turned into
 155
 156     res = 0
 157
 158   We also propagate casts into SWITCH_EXPR and COND_EXPR conditions to
 159   allow us to remove the cast and {NOT_EXPR,NEG_EXPR} into a subsequent
 160   {NOT_EXPR,NEG_EXPR}.
 161
 162    This will (of course) be extended as other needs arise.  */
 163
 164 static bool forward_propagate_addr_expr (tree name, tree rhs);
 165
 166 /* Set to true if we delete EH edges during the optimization.  */
 167 static bool cfg_changed;
 168
 169 static tree rhs_to_tree (tree type, gimple stmt);
 170
 171 /* Get the next statement we can propagate NAME's value into skipping
 172    trivial copies.  Returns the statement that is suitable as a
 173    propagation destination or NULL_TREE if there is no such one.
 174    This only returns destinations in a single-use chain.  FINAL_NAME_P
 175    if non-NULL is written to the ssa name that represents the use.  */
 176
 177 static gimple
 178 get_prop_dest_stmt (tree name, tree *final_name_p)
 179 {
 180   use_operand_p use;
 181   gimple use_stmt;
 182
 183   do {
 184     /* If name has multiple uses, bail out.  */
 185     if (!single_imm_use (name, &use, &use_stmt))
 186       return NULL;
 187
 188     /* If this is not a trivial copy, we found it.  */
 189     if (!gimple_assign_ssa_name_copy_p (use_stmt)
 190         || gimple_assign_rhs1 (use_stmt) != name)
 191       break;
 192
 193     /* Continue searching uses of the copy destination.  */
 194     name = gimple_assign_lhs (use_stmt);
 195   } while (1);
 196
 197   if (final_name_p)
 198     *final_name_p = name;
 199
 200   return use_stmt;
 201 }
 202
 203 /* Get the statement we can propagate from into NAME skipping
 204    trivial copies.  Returns the statement which defines the
 205    propagation source or NULL_TREE if there is no such one.
 206    If SINGLE_USE_ONLY is set considers only sources which have
 207    a single use chain up to NAME.  If SINGLE_USE_P is non-null,
 208    it is set to whether the chain to NAME is a single use chain
 209    or not.  SINGLE_USE_P is not written to if SINGLE_USE_ONLY is set.  */
 210
 211 static gimple
 212 get_prop_source_stmt (tree name, bool single_use_only, bool *single_use_p)
 213 {
 214   bool single_use = true;
 215
 216   do {
 217     gimple def_stmt = SSA_NAME_DEF_STMT (name);
 218
 219     if (!has_single_use (name))
 220       {
 221         single_use = false;
 222         if (single_use_only)
 223           return NULL;
 224       }
 225
 226     /* If name is defined by a PHI node or is the default def, bail out.  */
 227     if (!is_gimple_assign (def_stmt))
 228       return NULL;
 229
 230     /* If def_stmt is not a simple copy, we possibly found it.  */
 231     if (!gimple_assign_ssa_name_copy_p (def_stmt))
 232       {
 233         tree rhs;
 234
 235         if (!single_use_only && single_use_p)
 236           *single_use_p = single_use;
 237
 238         /* We can look through pointer conversions in the search
 239            for a useful stmt for the comparison folding.  */
 240         rhs = gimple_assign_rhs1 (def_stmt);
 241         if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt))
 242             && TREE_CODE (rhs) == SSA_NAME
 243             && POINTER_TYPE_P (TREE_TYPE (gimple_assign_lhs (def_stmt)))
 244             && POINTER_TYPE_P (TREE_TYPE (rhs)))
 245           name = rhs;
 246         else
 247           return def_stmt;
 248       }
 249     else
 250       {
 251         /* Continue searching the def of the copy source name.  */
 252         name = gimple_assign_rhs1 (def_stmt);
 253       }
 254   } while (1);
 255 }
 256
 257 /* Checks if the destination ssa name in DEF_STMT can be used as
 258    propagation source.  Returns true if so, otherwise false.  */
 259
 260 static bool
 261 can_propagate_from (gimple def_stmt)
 262 {
 263   gcc_assert (is_gimple_assign (def_stmt));
 264
 265   /* If the rhs has side-effects we cannot propagate from it.  */
 266   if (gimple_has_volatile_ops (def_stmt))
 267     return false;
 268
 269   /* If the rhs is a load we cannot propagate from it.  */
 270   if (TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt)) == tcc_reference
 271       || TREE_CODE_CLASS (gimple_assign_rhs_code (def_stmt)) == tcc_declaration)
 272     return false;
 273
 274   /* Constants can be always propagated.  */
 275   if (gimple_assign_single_p (def_stmt)
 276       && is_gimple_min_invariant (gimple_assign_rhs1 (def_stmt)))
 277     return true;
 278
 279   /* We cannot propagate ssa names that occur in abnormal phi nodes.  */
 280   if (stmt_references_abnormal_ssa_name (def_stmt))
 281     return false;
 282
 283   /* If the definition is a conversion of a pointer to a function type,
 284      then we can not apply optimizations as some targets require
 285      function pointers to be canonicalized and in this case this
 286      optimization could eliminate a necessary canonicalization.  */
 287   if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt)))
 288     {
 289       tree rhs = gimple_assign_rhs1 (def_stmt);
 290       if (POINTER_TYPE_P (TREE_TYPE (rhs))
 291           && TREE_CODE (TREE_TYPE (TREE_TYPE (rhs))) == FUNCTION_TYPE)
 292         return false;
 293     }
 294
 295   return true;
 296 }
 297
 298 /* Remove a chain of dead statements starting at the definition of
 299    NAME.  The chain is linked via the first operand of the defining statements.
 300    If NAME was replaced in its only use then this function can be used
 301    to clean up dead stmts.  The function handles already released SSA
 302    names gracefully.
 303    Returns true if cleanup-cfg has to run.  */
 304
 305 static bool
 306 remove_prop_source_from_use (tree name)
 307 {
 308   gimple_stmt_iterator gsi;
 309   gimple stmt;
 310   bool cfg_changed = false;
 311
 312   do {
 313     basic_block bb;
 314
 315     if (SSA_NAME_IN_FREE_LIST (name)
 316         || SSA_NAME_IS_DEFAULT_DEF (name)
 317         || !has_zero_uses (name))
 318       return cfg_changed;
 319
 320     stmt = SSA_NAME_DEF_STMT (name);
 321     if (gimple_code (stmt) == GIMPLE_PHI
 322         || gimple_has_side_effects (stmt))
 323       return cfg_changed;
 324
 325     bb = gimple_bb (stmt);
 326     gsi = gsi_for_stmt (stmt);
 327     unlink_stmt_vdef (stmt);
 328     gsi_remove (&gsi, true);
 329     release_defs (stmt);
 330     cfg_changed |= gimple_purge_dead_eh_edges (bb);
 331
 332     name = is_gimple_assign (stmt) ? gimple_assign_rhs1 (stmt) : NULL_TREE;
 333   } while (name && TREE_CODE (name) == SSA_NAME);
 334
 335   return cfg_changed;
 336 }
 337
 338 /* Return the rhs of a gimple_assign STMT in a form of a single tree,
 339    converted to type TYPE.
 340
 341    This should disappear, but is needed so we can combine expressions and use
 342    the fold() interfaces. Long term, we need to develop folding and combine
 343    routines that deal with gimple exclusively . */
 344
 345 static tree
 346 rhs_to_tree (tree type, gimple stmt)
 347 {
 348   location_t loc = gimple_location (stmt);
 349   enum tree_code code = gimple_assign_rhs_code (stmt);
 350   if (get_gimple_rhs_class (code) == GIMPLE_TERNARY_RHS)
 351     return fold_build3_loc (loc, code, type, gimple_assign_rhs1 (stmt),
 352                             gimple_assign_rhs2 (stmt),
 353                             gimple_assign_rhs3 (stmt));
 354   else if (get_gimple_rhs_class (code) == GIMPLE_BINARY_RHS)
 355     return fold_build2_loc (loc, code, type, gimple_assign_rhs1 (stmt),
 356                         gimple_assign_rhs2 (stmt));
 357   else if (get_gimple_rhs_class (code) == GIMPLE_UNARY_RHS)
 358     return build1 (code, type, gimple_assign_rhs1 (stmt));
 359   else if (get_gimple_rhs_class (code) == GIMPLE_SINGLE_RHS)
 360     return gimple_assign_rhs1 (stmt);
 361   else
 362     gcc_unreachable ();
 363 }
 364
 365 /* Combine OP0 CODE OP1 in the context of a COND_EXPR.  Returns
 366    the folded result in a form suitable for COND_EXPR_COND or
 367    NULL_TREE, if there is no suitable simplified form.  If
 368    INVARIANT_ONLY is true only gimple_min_invariant results are
 369    considered simplified.  */
 370
 371 static tree
 372 combine_cond_expr_cond (gimple stmt, enum tree_code code, tree type,
 373                         tree op0, tree op1, bool invariant_only)
 374 {
 375   tree t;
 376
 377   gcc_assert (TREE_CODE_CLASS (code) == tcc_comparison);
 378
 379   fold_defer_overflow_warnings ();
 380   t = fold_binary_loc (gimple_location (stmt), code, type, op0, op1);
 381   if (!t)
 382     {
 383       fold_undefer_overflow_warnings (false, NULL, 0);
 384       return NULL_TREE;
 385     }
 386
 387   /* Require that we got a boolean type out if we put one in.  */
 388   gcc_assert (TREE_CODE (TREE_TYPE (t)) == TREE_CODE (type));
 389
 390   /* Canonicalize the combined condition for use in a COND_EXPR.  */
 391   t = canonicalize_cond_expr_cond (t);
 392
 393   /* Bail out if we required an invariant but didn't get one.  */
 394   if (!t || (invariant_only && !is_gimple_min_invariant (t)))
 395     {
 396       fold_undefer_overflow_warnings (false, NULL, 0);
 397       return NULL_TREE;
 398     }
 399
 400   fold_undefer_overflow_warnings (!gimple_no_warning_p (stmt), stmt, 0);
 401
 402   return t;
 403 }
 404
 405 /* Combine the comparison OP0 CODE OP1 at LOC with the defining statements
 406    of its operand.  Return a new comparison tree or NULL_TREE if there
 407    were no simplifying combines.  */
 408
 409 static tree
 410 forward_propagate_into_comparison_1 (gimple stmt,
 411                                      enum tree_code code, tree type,
 412                                      tree op0, tree op1)
 413 {
 414   tree tmp = NULL_TREE;
 415   tree rhs0 = NULL_TREE, rhs1 = NULL_TREE;
 416   bool single_use0_p = false, single_use1_p = false;
 417
 418   /* For comparisons use the first operand, that is likely to
 419      simplify comparisons against constants.  */
 420   if (TREE_CODE (op0) == SSA_NAME)
 421     {
 422       gimple def_stmt = get_prop_source_stmt (op0, false, &single_use0_p);
 423       if (def_stmt && can_propagate_from (def_stmt))
 424         {
 425           rhs0 = rhs_to_tree (TREE_TYPE (op1), def_stmt);
 426           tmp = combine_cond_expr_cond (stmt, code, type,
 427                                         rhs0, op1, !single_use0_p);
 428           if (tmp)
 429             return tmp;
 430         }
 431     }
 432
 433   /* If that wasn't successful, try the second operand.  */
 434   if (TREE_CODE (op1) == SSA_NAME)
 435     {
 436       gimple def_stmt = get_prop_source_stmt (op1, false, &single_use1_p);
 437       if (def_stmt && can_propagate_from (def_stmt))
 438         {
 439           rhs1 = rhs_to_tree (TREE_TYPE (op0), def_stmt);
 440           tmp = combine_cond_expr_cond (stmt, code, type,
 441                                         op0, rhs1, !single_use1_p);
 442           if (tmp)
 443             return tmp;
 444         }
 445     }
 446
 447   /* If that wasn't successful either, try both operands.  */
 448   if (rhs0 != NULL_TREE
 449       && rhs1 != NULL_TREE)
 450     tmp = combine_cond_expr_cond (stmt, code, type,
 451                                   rhs0, rhs1,
 452                                   !(single_use0_p && single_use1_p));
 453
 454   return tmp;
 455 }
 456
 457 /* Propagate from the ssa name definition statements of the assignment
 458    from a comparison at *GSI into the conditional if that simplifies it.
 459    Returns 1 if the stmt was modified and 2 if the CFG needs cleanup,
 460    otherwise returns 0.  */
 461
 462 static int
 463 forward_propagate_into_comparison (gimple_stmt_iterator *gsi)
 464 {
 465   gimple stmt = gsi_stmt (*gsi);
 466   tree tmp;
 467   bool cfg_changed = false;
 468   tree rhs1 = gimple_assign_rhs1 (stmt);
 469   tree rhs2 = gimple_assign_rhs2 (stmt);
 470
 471   /* Combine the comparison with defining statements.  */
 472   tmp = forward_propagate_into_comparison_1 (stmt,
 473                                              gimple_assign_rhs_code (stmt),
 474                                              TREE_TYPE
 475                                                (gimple_assign_lhs (stmt)),
 476                                              rhs1, rhs2);
 477   if (tmp)
 478     {
 479       gimple_assign_set_rhs_from_tree (gsi, tmp);
 480       fold_stmt (gsi);
 481       update_stmt (gsi_stmt (*gsi));
 482
 483       if (TREE_CODE (rhs1) == SSA_NAME)
 484         cfg_changed |= remove_prop_source_from_use (rhs1);
 485       if (TREE_CODE (rhs2) == SSA_NAME)
 486         cfg_changed |= remove_prop_source_from_use (rhs2);
 487       return cfg_changed ? 2 : 1;
 488     }
 489
 490   return 0;
 491 }
 492
 493 /* Propagate from the ssa name definition statements of COND_EXPR
 494    in GIMPLE_COND statement STMT into the conditional if that simplifies it.
 495    Returns zero if no statement was changed, one if there were
 496    changes and two if cfg_cleanup needs to run.
 497
 498    This must be kept in sync with forward_propagate_into_cond.  */
 499
 500 static int
 501 forward_propagate_into_gimple_cond (gimple stmt)
 502 {
 503   tree tmp;
 504   enum tree_code code = gimple_cond_code (stmt);
 505   bool cfg_changed = false;
 506   tree rhs1 = gimple_cond_lhs (stmt);
 507   tree rhs2 = gimple_cond_rhs (stmt);
 508
 509   /* We can do tree combining on SSA_NAME and comparison expressions.  */
 510   if (TREE_CODE_CLASS (gimple_cond_code (stmt)) != tcc_comparison)
 511     return 0;
 512
 513   tmp = forward_propagate_into_comparison_1 (stmt, code,
 514                                              boolean_type_node,
 515                                              rhs1, rhs2);
 516   if (tmp)
 517     {
 518       if (dump_file && tmp)
 519         {
 520           fprintf (dump_file, "  Replaced '");
 521           print_gimple_expr (dump_file, stmt, 0, 0);
 522           fprintf (dump_file, "' with '");
 523           print_generic_expr (dump_file, tmp, 0);
 524           fprintf (dump_file, "'\n");
 525         }
 526
 527       gimple_cond_set_condition_from_tree (stmt, unshare_expr (tmp));
 528       update_stmt (stmt);
 529
 530       if (TREE_CODE (rhs1) == SSA_NAME)
 531         cfg_changed |= remove_prop_source_from_use (rhs1);
 532       if (TREE_CODE (rhs2) == SSA_NAME)
 533         cfg_changed |= remove_prop_source_from_use (rhs2);
 534       return (cfg_changed || is_gimple_min_invariant (tmp)) ? 2 : 1;
 535     }
 536
 537   /* Canonicalize _Bool == 0 and _Bool != 1 to _Bool != 0 by swapping edges.  */
 538   if ((TREE_CODE (TREE_TYPE (rhs1)) == BOOLEAN_TYPE
 539        || (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
 540            && TYPE_PRECISION (TREE_TYPE (rhs1)) == 1))
 541       && ((code == EQ_EXPR
 542            && integer_zerop (rhs2))
 543           || (code == NE_EXPR
 544               && integer_onep (rhs2))))
 545     {
 546       basic_block bb = gimple_bb (stmt);
 547       gimple_cond_set_code (stmt, NE_EXPR);
 548       gimple_cond_set_rhs (stmt, build_zero_cst (TREE_TYPE (rhs1)));
 549       EDGE_SUCC (bb, 0)->flags ^= (EDGE_TRUE_VALUE|EDGE_FALSE_VALUE);
 550       EDGE_SUCC (bb, 1)->flags ^= (EDGE_TRUE_VALUE|EDGE_FALSE_VALUE);
 551       return 1;
 552     }
 553
 554   return 0;
 555 }
 556
 557
 558 /* Propagate from the ssa name definition statements of COND_EXPR
 559    in the rhs of statement STMT into the conditional if that simplifies it.
 560    Returns true zero if the stmt was changed.  */
 561
 562 static bool
 563 forward_propagate_into_cond (gimple_stmt_iterator *gsi_p)
 564 {
 565   gimple stmt = gsi_stmt (*gsi_p);
 566   tree tmp = NULL_TREE;
 567   tree cond = gimple_assign_rhs1 (stmt);
 568   bool swap = false;
 569
 570   /* We can do tree combining on SSA_NAME and comparison expressions.  */
 571   if (COMPARISON_CLASS_P (cond))
 572     tmp = forward_propagate_into_comparison_1 (stmt, TREE_CODE (cond),
 573                                                boolean_type_node,
 574                                                TREE_OPERAND (cond, 0),
 575                                                TREE_OPERAND (cond, 1));
 576   else if (TREE_CODE (cond) == SSA_NAME)
 577     {
 578       enum tree_code code;
 579       tree name = cond;
 580       gimple def_stmt = get_prop_source_stmt (name, true, NULL);
 581       if (!def_stmt || !can_propagate_from (def_stmt))
 582         return 0;
 583
 584       code = gimple_assign_rhs_code (def_stmt);
 585       if (TREE_CODE_CLASS (code) == tcc_comparison)
 586         tmp = fold_build2_loc (gimple_location (def_stmt),
 587                                code,
 588                                boolean_type_node,
 589                                gimple_assign_rhs1 (def_stmt),
 590                                gimple_assign_rhs2 (def_stmt));
 591       else if ((code == BIT_NOT_EXPR
 592                 && TYPE_PRECISION (TREE_TYPE (cond)) == 1)
 593                || (code == BIT_XOR_EXPR
 594                    && integer_onep (gimple_assign_rhs2 (def_stmt))))
 595         {
 596           tmp = gimple_assign_rhs1 (def_stmt);
 597           swap = true;
 598         }
 599     }
 600
 601   if (tmp)
 602     {
 603       if (dump_file && tmp)
 604         {
 605           fprintf (dump_file, "  Replaced '");
 606           print_generic_expr (dump_file, cond, 0);
 607           fprintf (dump_file, "' with '");
 608           print_generic_expr (dump_file, tmp, 0);
 609           fprintf (dump_file, "'\n");
 610         }
 611
 612       if (integer_onep (tmp))
 613         gimple_assign_set_rhs_from_tree (gsi_p, gimple_assign_rhs2 (stmt));
 614       else if (integer_zerop (tmp))
 615         gimple_assign_set_rhs_from_tree (gsi_p, gimple_assign_rhs3 (stmt));
 616       else
 617         {
 618           gimple_assign_set_rhs1 (stmt, unshare_expr (tmp));
 619           if (swap)
 620             {
 621               tree t = gimple_assign_rhs2 (stmt);
 622               gimple_assign_set_rhs2 (stmt, gimple_assign_rhs3 (stmt));
 623               gimple_assign_set_rhs3 (stmt, t);
 624             }
 625         }
 626       stmt = gsi_stmt (*gsi_p);
 627       update_stmt (stmt);
 628
 629       return true;
 630     }
 631
 632   return 0;
 633 }
 634
 635 /* We've just substituted an ADDR_EXPR into stmt.  Update all the
 636    relevant data structures to match.  */
 637
 638 static void
 639 tidy_after_forward_propagate_addr (gimple stmt)
 640 {
 641   /* We may have turned a trapping insn into a non-trapping insn.  */
 642   if (maybe_clean_or_replace_eh_stmt (stmt, stmt)
 643       && gimple_purge_dead_eh_edges (gimple_bb (stmt)))
 644     cfg_changed = true;
 645
 646   if (TREE_CODE (gimple_assign_rhs1 (stmt)) == ADDR_EXPR)
 647      recompute_tree_invariant_for_addr_expr (gimple_assign_rhs1 (stmt));
 648 }
 649
 650 /* DEF_RHS contains the address of the 0th element in an array.
 651    USE_STMT uses type of DEF_RHS to compute the address of an
 652    arbitrary element within the array.  The (variable) byte offset
 653    of the element is contained in OFFSET.
 654
 655    We walk back through the use-def chains of OFFSET to verify that
 656    it is indeed computing the offset of an element within the array
 657    and extract the index corresponding to the given byte offset.
 658
 659    We then try to fold the entire address expression into a form
 660    &array[index].
 661
 662    If we are successful, we replace the right hand side of USE_STMT
 663    with the new address computation.  */
 664
 665 static bool
 666 forward_propagate_addr_into_variable_array_index (tree offset,
 667                                                   tree def_rhs,
 668                                                   gimple_stmt_iterator *use_stmt_gsi)
 669 {
 670   tree index, tunit;
 671   gimple offset_def, use_stmt = gsi_stmt (*use_stmt_gsi);
 672   tree new_rhs, tmp;
 673
 674   if (TREE_CODE (TREE_OPERAND (def_rhs, 0)) == ARRAY_REF)
 675     tunit = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (def_rhs)));
 676   else if (TREE_CODE (TREE_TYPE (TREE_OPERAND (def_rhs, 0))) == ARRAY_TYPE)
 677     tunit = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (TREE_TYPE (def_rhs))));
 678   else
 679     return false;
 680   if (!host_integerp (tunit, 1))
 681     return false;
 682
 683   /* Get the offset's defining statement.  */
 684   offset_def = SSA_NAME_DEF_STMT (offset);
 685
 686   /* Try to find an expression for a proper index.  This is either a
 687      multiplication expression by the element size or just the ssa name we came
 688      along in case the element size is one. In that case, however, we do not
 689      allow multiplications because they can be computing index to a higher
 690      level dimension (PR 37861). */
 691   if (integer_onep (tunit))
 692     {
 693       if (is_gimple_assign (offset_def)
 694           && gimple_assign_rhs_code (offset_def) == MULT_EXPR)
 695         return false;
 696
 697       index = offset;
 698     }
 699   else
 700     {
 701       /* The statement which defines OFFSET before type conversion
 702          must be a simple GIMPLE_ASSIGN.  */
 703       if (!is_gimple_assign (offset_def))
 704         return false;
 705
 706       /* The RHS of the statement which defines OFFSET must be a
 707          multiplication of an object by the size of the array elements.
 708          This implicitly verifies that the size of the array elements
 709          is constant.  */
 710      if (gimple_assign_rhs_code (offset_def) == MULT_EXPR
 711          && TREE_CODE (gimple_assign_rhs2 (offset_def)) == INTEGER_CST
 712          && tree_int_cst_equal (gimple_assign_rhs2 (offset_def), tunit))
 713        {
 714          /* The first operand to the MULT_EXPR is the desired index.  */
 715          index = gimple_assign_rhs1 (offset_def);
 716        }
 717      /* If we have idx * tunit + CST * tunit re-associate that.  */
 718      else if ((gimple_assign_rhs_code (offset_def) == PLUS_EXPR
 719                || gimple_assign_rhs_code (offset_def) == MINUS_EXPR)
 720               && TREE_CODE (gimple_assign_rhs1 (offset_def)) == SSA_NAME
 721               && TREE_CODE (gimple_assign_rhs2 (offset_def)) == INTEGER_CST
 722               && (tmp = div_if_zero_remainder (EXACT_DIV_EXPR,
 723                                                gimple_assign_rhs2 (offset_def),
 724                                                tunit)) != NULL_TREE)
 725        {
 726          gimple offset_def2 = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (offset_def));
 727          if (is_gimple_assign (offset_def2)
 728              && gimple_assign_rhs_code (offset_def2) == MULT_EXPR
 729              && TREE_CODE (gimple_assign_rhs2 (offset_def2)) == INTEGER_CST
 730              && tree_int_cst_equal (gimple_assign_rhs2 (offset_def2), tunit))
 731            {
 732              index = fold_build2 (gimple_assign_rhs_code (offset_def),
 733                                   TREE_TYPE (offset),
 734                                   gimple_assign_rhs1 (offset_def2), tmp);
 735            }
 736          else
 737            return false;
 738        }
 739      else
 740         return false;
 741     }
 742
 743   /* Replace the pointer addition with array indexing.  */
 744   index = force_gimple_operand_gsi (use_stmt_gsi, index, true, NULL_TREE,
 745                                     true, GSI_SAME_STMT);
 746   if (TREE_CODE (TREE_OPERAND (def_rhs, 0)) == ARRAY_REF)
 747     {
 748       new_rhs = unshare_expr (def_rhs);
 749       TREE_OPERAND (TREE_OPERAND (new_rhs, 0), 1) = index;
 750     }
 751   else
 752     {
 753       new_rhs = build4 (ARRAY_REF, TREE_TYPE (TREE_TYPE (TREE_TYPE (def_rhs))),
 754                         unshare_expr (TREE_OPERAND (def_rhs, 0)),
 755                         index, integer_zero_node, NULL_TREE);
 756       new_rhs = build_fold_addr_expr (new_rhs);
 757       if (!useless_type_conversion_p (TREE_TYPE (gimple_assign_lhs (use_stmt)),
 758                                       TREE_TYPE (new_rhs)))
 759         {
 760           new_rhs = force_gimple_operand_gsi (use_stmt_gsi, new_rhs, true,
 761                                               NULL_TREE, true, GSI_SAME_STMT);
 762           new_rhs = fold_convert (TREE_TYPE (gimple_assign_lhs (use_stmt)),
 763                                   new_rhs);
 764         }
 765     }
 766   gimple_assign_set_rhs_from_tree (use_stmt_gsi, new_rhs);
 767   fold_stmt (use_stmt_gsi);
 768   tidy_after_forward_propagate_addr (gsi_stmt (*use_stmt_gsi));
 769   return true;
 770 }
 771
 772 /* NAME is a SSA_NAME representing DEF_RHS which is of the form
 773    ADDR_EXPR <whatever>.
 774
 775    Try to forward propagate the ADDR_EXPR into the use USE_STMT.
 776    Often this will allow for removal of an ADDR_EXPR and INDIRECT_REF
 777    node or for recovery of array indexing from pointer arithmetic.
 778
 779    Return true if the propagation was successful (the propagation can
 780    be not totally successful, yet things may have been changed).  */
 781
 782 static bool
 783 forward_propagate_addr_expr_1 (tree name, tree def_rhs,
 784                                gimple_stmt_iterator *use_stmt_gsi,
 785                                bool single_use_p)
 786 {
 787   tree lhs, rhs, rhs2, array_ref;
 788   gimple use_stmt = gsi_stmt (*use_stmt_gsi);
 789   enum tree_code rhs_code;
 790   bool res = true;
 791
 792   gcc_assert (TREE_CODE (def_rhs) == ADDR_EXPR);
 793
 794   lhs = gimple_assign_lhs (use_stmt);
 795   rhs_code = gimple_assign_rhs_code (use_stmt);
 796   rhs = gimple_assign_rhs1 (use_stmt);
 797
 798   /* Trivial cases.  The use statement could be a trivial copy or a
 799      useless conversion.  Recurse to the uses of the lhs as copyprop does
 800      not copy through different variant pointers and FRE does not catch
 801      all useless conversions.  Treat the case of a single-use name and
 802      a conversion to def_rhs type separate, though.  */
 803   if (TREE_CODE (lhs) == SSA_NAME
 804       && ((rhs_code == SSA_NAME && rhs == name)
 805           || CONVERT_EXPR_CODE_P (rhs_code)))
 806     {
 807       /* Only recurse if we don't deal with a single use or we cannot
 808          do the propagation to the current statement.  In particular
 809          we can end up with a conversion needed for a non-invariant
 810          address which we cannot do in a single statement.  */
 811       if (!single_use_p
 812           || (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (def_rhs))
 813               && (!is_gimple_min_invariant (def_rhs)
 814                   || (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
 815                       && POINTER_TYPE_P (TREE_TYPE (def_rhs))
 816                       && (TYPE_PRECISION (TREE_TYPE (lhs))
 817                           > TYPE_PRECISION (TREE_TYPE (def_rhs)))))))
 818         return forward_propagate_addr_expr (lhs, def_rhs);
 819
 820       gimple_assign_set_rhs1 (use_stmt, unshare_expr (def_rhs));
 821       if (useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (def_rhs)))
 822         gimple_assign_set_rhs_code (use_stmt, TREE_CODE (def_rhs));
 823       else
 824         gimple_assign_set_rhs_code (use_stmt, NOP_EXPR);
 825       return true;
 826     }
 827
 828   /* Propagate through constant pointer adjustments.  */
 829   if (TREE_CODE (lhs) == SSA_NAME
 830       && rhs_code == POINTER_PLUS_EXPR
 831       && rhs == name
 832       && TREE_CODE (gimple_assign_rhs2 (use_stmt)) == INTEGER_CST)
 833     {
 834       tree new_def_rhs;
 835       /* As we come here with non-invariant addresses in def_rhs we need
 836          to make sure we can build a valid constant offsetted address
 837          for further propagation.  Simply rely on fold building that
 838          and check after the fact.  */
 839       new_def_rhs = fold_build2 (MEM_REF, TREE_TYPE (TREE_TYPE (rhs)),
 840                                  def_rhs,
 841                                  fold_convert (ptr_type_node,
 842                                                gimple_assign_rhs2 (use_stmt)));
 843       if (TREE_CODE (new_def_rhs) == MEM_REF
 844           && !is_gimple_mem_ref_addr (TREE_OPERAND (new_def_rhs, 0)))
 845         return false;
 846       new_def_rhs = build_fold_addr_expr_with_type (new_def_rhs,
 847                                                     TREE_TYPE (rhs));
 848
 849       /* Recurse.  If we could propagate into all uses of lhs do not
 850          bother to replace into the current use but just pretend we did.  */
 851       if (TREE_CODE (new_def_rhs) == ADDR_EXPR
 852           && forward_propagate_addr_expr (lhs, new_def_rhs))
 853         return true;
 854
 855       if (useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (new_def_rhs)))
 856         gimple_assign_set_rhs_with_ops (use_stmt_gsi, TREE_CODE (new_def_rhs),
 857                                         new_def_rhs, NULL_TREE);
 858       else if (is_gimple_min_invariant (new_def_rhs))
 859         gimple_assign_set_rhs_with_ops (use_stmt_gsi, NOP_EXPR,
 860                                         new_def_rhs, NULL_TREE);
 861       else
 862         return false;
 863       gcc_assert (gsi_stmt (*use_stmt_gsi) == use_stmt);
 864       update_stmt (use_stmt);
 865       return true;
 866     }
 867
 868   /* Now strip away any outer COMPONENT_REF/ARRAY_REF nodes from the LHS.
 869      ADDR_EXPR will not appear on the LHS.  */
 870   lhs = gimple_assign_lhs (use_stmt);
 871   while (handled_component_p (lhs))
 872     lhs = TREE_OPERAND (lhs, 0);
 873
 874   /* Now see if the LHS node is a MEM_REF using NAME.  If so,
 875      propagate the ADDR_EXPR into the use of NAME and fold the result.  */
 876   if (TREE_CODE (lhs) == MEM_REF
 877       && TREE_OPERAND (lhs, 0) == name)
 878     {
 879       tree def_rhs_base;
 880       HOST_WIDE_INT def_rhs_offset;
 881       /* If the address is invariant we can always fold it.  */
 882       if ((def_rhs_base = get_addr_base_and_unit_offset (TREE_OPERAND (def_rhs, 0),
 883                                                          &def_rhs_offset)))
 884         {
 885           double_int off = mem_ref_offset (lhs);
 886           tree new_ptr;
 887           off = double_int_add (off,
 888                                 shwi_to_double_int (def_rhs_offset));
 889           if (TREE_CODE (def_rhs_base) == MEM_REF)
 890             {
 891               off = double_int_add (off, mem_ref_offset (def_rhs_base));
 892               new_ptr = TREE_OPERAND (def_rhs_base, 0);
 893             }
 894           else
 895             new_ptr = build_fold_addr_expr (def_rhs_base);
 896           TREE_OPERAND (lhs, 0) = new_ptr;
 897           TREE_OPERAND (lhs, 1)
 898             = double_int_to_tree (TREE_TYPE (TREE_OPERAND (lhs, 1)), off);
 899           tidy_after_forward_propagate_addr (use_stmt);
 900           /* Continue propagating into the RHS if this was not the only use.  */
 901           if (single_use_p)
 902             return true;
 903         }
 904       /* If the LHS is a plain dereference and the value type is the same as
 905          that of the pointed-to type of the address we can put the
 906          dereferenced address on the LHS preserving the original alias-type.  */
 907       else if (gimple_assign_lhs (use_stmt) == lhs
 908                && useless_type_conversion_p
 909                     (TREE_TYPE (TREE_OPERAND (def_rhs, 0)),
 910                      TREE_TYPE (gimple_assign_rhs1 (use_stmt))))
 911         {
 912           tree *def_rhs_basep = &TREE_OPERAND (def_rhs, 0);
 913           tree new_offset, new_base, saved;
 914           while (handled_component_p (*def_rhs_basep))
 915             def_rhs_basep = &TREE_OPERAND (*def_rhs_basep, 0);
 916           saved = *def_rhs_basep;
 917           if (TREE_CODE (*def_rhs_basep) == MEM_REF)
 918             {
 919               new_base = TREE_OPERAND (*def_rhs_basep, 0);
 920               new_offset
 921                 = int_const_binop (PLUS_EXPR, TREE_OPERAND (lhs, 1),
 922                                    TREE_OPERAND (*def_rhs_basep, 1));
 923             }
 924           else
 925             {
 926               new_base = build_fold_addr_expr (*def_rhs_basep);
 927               new_offset = TREE_OPERAND (lhs, 1);
 928             }
 929           *def_rhs_basep = build2 (MEM_REF, TREE_TYPE (*def_rhs_basep),
 930                                    new_base, new_offset);
 931           TREE_THIS_VOLATILE (*def_rhs_basep) = TREE_THIS_VOLATILE (lhs);
 932           TREE_THIS_NOTRAP (*def_rhs_basep) = TREE_THIS_NOTRAP (lhs);
 933           gimple_assign_set_lhs (use_stmt,
 934                                  unshare_expr (TREE_OPERAND (def_rhs, 0)));
 935           *def_rhs_basep = saved;
 936           tidy_after_forward_propagate_addr (use_stmt);
 937           /* Continue propagating into the RHS if this was not the
 938              only use.  */
 939           if (single_use_p)
 940             return true;
 941         }
 942       else
 943         /* We can have a struct assignment dereferencing our name twice.
 944            Note that we didn't propagate into the lhs to not falsely
 945            claim we did when propagating into the rhs.  */
 946         res = false;
 947     }
 948
 949   /* Strip away any outer COMPONENT_REF, ARRAY_REF or ADDR_EXPR
 950      nodes from the RHS.  */
 951   rhs = gimple_assign_rhs1 (use_stmt);
 952   if (TREE_CODE (rhs) == ADDR_EXPR)
 953     rhs = TREE_OPERAND (rhs, 0);
 954   while (handled_component_p (rhs))
 955     rhs = TREE_OPERAND (rhs, 0);
 956
 957   /* Now see if the RHS node is a MEM_REF using NAME.  If so,
 958      propagate the ADDR_EXPR into the use of NAME and fold the result.  */
 959   if (TREE_CODE (rhs) == MEM_REF
 960       && TREE_OPERAND (rhs, 0) == name)
 961     {
 962       tree def_rhs_base;
 963       HOST_WIDE_INT def_rhs_offset;
 964       if ((def_rhs_base = get_addr_base_and_unit_offset (TREE_OPERAND (def_rhs, 0),
 965                                                          &def_rhs_offset)))
 966         {
 967           double_int off = mem_ref_offset (rhs);
 968           tree new_ptr;
 969           off = double_int_add (off,
 970                                 shwi_to_double_int (def_rhs_offset));
 971           if (TREE_CODE (def_rhs_base) == MEM_REF)
 972             {
 973               off = double_int_add (off, mem_ref_offset (def_rhs_base));
 974               new_ptr = TREE_OPERAND (def_rhs_base, 0);
 975             }
 976           else
 977             new_ptr = build_fold_addr_expr (def_rhs_base);
 978           TREE_OPERAND (rhs, 0) = new_ptr;
 979           TREE_OPERAND (rhs, 1)
 980             = double_int_to_tree (TREE_TYPE (TREE_OPERAND (rhs, 1)), off);
 981           fold_stmt_inplace (use_stmt_gsi);
 982           tidy_after_forward_propagate_addr (use_stmt);
 983           return res;
 984         }
 985       /* If the RHS is a plain dereference and the value type is the same as
 986          that of the pointed-to type of the address we can put the
 987          dereferenced address on the RHS preserving the original alias-type.  */
 988       else if (gimple_assign_rhs1 (use_stmt) == rhs
 989                && useless_type_conversion_p
 990                     (TREE_TYPE (gimple_assign_lhs (use_stmt)),
 991                      TREE_TYPE (TREE_OPERAND (def_rhs, 0))))
 992         {
 993           tree *def_rhs_basep = &TREE_OPERAND (def_rhs, 0);
 994           tree new_offset, new_base, saved;
 995           while (handled_component_p (*def_rhs_basep))
 996             def_rhs_basep = &TREE_OPERAND (*def_rhs_basep, 0);
 997           saved = *def_rhs_basep;
 998           if (TREE_CODE (*def_rhs_basep) == MEM_REF)
 999             {
1000               new_base = TREE_OPERAND (*def_rhs_basep, 0);
1001               new_offset
1002                 = int_const_binop (PLUS_EXPR, TREE_OPERAND (rhs, 1),
1003                                    TREE_OPERAND (*def_rhs_basep, 1));
1004             }
1005           else
1006             {
1007               new_base = build_fold_addr_expr (*def_rhs_basep);
1008               new_offset = TREE_OPERAND (rhs, 1);
1009             }
1010           *def_rhs_basep = build2 (MEM_REF, TREE_TYPE (*def_rhs_basep),
1011                                    new_base, new_offset);
1012           TREE_THIS_VOLATILE (*def_rhs_basep) = TREE_THIS_VOLATILE (rhs);
1013           TREE_THIS_NOTRAP (*def_rhs_basep) = TREE_THIS_NOTRAP (rhs);
1014           gimple_assign_set_rhs1 (use_stmt,
1015                                   unshare_expr (TREE_OPERAND (def_rhs, 0)));
1016           *def_rhs_basep = saved;
1017           fold_stmt_inplace (use_stmt_gsi);
1018           tidy_after_forward_propagate_addr (use_stmt);
1019           return res;
1020         }
1021     }
1022
1023   /* If the use of the ADDR_EXPR is not a POINTER_PLUS_EXPR, there
1024      is nothing to do. */
1025   if (gimple_assign_rhs_code (use_stmt) != POINTER_PLUS_EXPR
1026       || gimple_assign_rhs1 (use_stmt) != name)
1027     return false;
1028
1029   /* The remaining cases are all for turning pointer arithmetic into
1030      array indexing.  They only apply when we have the address of
1031      element zero in an array.  If that is not the case then there
1032      is nothing to do.  */
1033   array_ref = TREE_OPERAND (def_rhs, 0);
1034   if ((TREE_CODE (array_ref) != ARRAY_REF
1035        || TREE_CODE (TREE_TYPE (TREE_OPERAND (array_ref, 0))) != ARRAY_TYPE
1036        || TREE_CODE (TREE_OPERAND (array_ref, 1)) != INTEGER_CST)
1037       && TREE_CODE (TREE_TYPE (array_ref)) != ARRAY_TYPE)
1038     return false;
1039
1040   rhs2 = gimple_assign_rhs2 (use_stmt);
1041   /* Optimize &x[C1] p+ C2 to  &x p+ C3 with C3 = C1 * element_size + C2.  */
1042   if (TREE_CODE (rhs2) == INTEGER_CST)
1043     {
1044       tree new_rhs = build1_loc (gimple_location (use_stmt),
1045                                  ADDR_EXPR, TREE_TYPE (def_rhs),
1046                                  fold_build2 (MEM_REF,
1047                                               TREE_TYPE (TREE_TYPE (def_rhs)),
1048                                               unshare_expr (def_rhs),
1049                                               fold_convert (ptr_type_node,
1050                                                             rhs2)));
1051       gimple_assign_set_rhs_from_tree (use_stmt_gsi, new_rhs);
1052       use_stmt = gsi_stmt (*use_stmt_gsi);
1053       update_stmt (use_stmt);
1054       tidy_after_forward_propagate_addr (use_stmt);
1055       return true;
1056     }
1057
1058   /* Try to optimize &x[0] p+ OFFSET where OFFSET is defined by
1059      converting a multiplication of an index by the size of the
1060      array elements, then the result is converted into the proper
1061      type for the arithmetic.  */
1062   if (TREE_CODE (rhs2) == SSA_NAME
1063       && (TREE_CODE (array_ref) != ARRAY_REF
1064           || integer_zerop (TREE_OPERAND (array_ref, 1)))
1065       && useless_type_conversion_p (TREE_TYPE (name), TREE_TYPE (def_rhs))
1066       /* Avoid problems with IVopts creating PLUS_EXPRs with a
1067          different type than their operands.  */
1068       && useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (def_rhs)))
1069     return forward_propagate_addr_into_variable_array_index (rhs2, def_rhs,
1070                                                              use_stmt_gsi);
1071   return false;
1072 }
1073
1074 /* STMT is a statement of the form SSA_NAME = ADDR_EXPR <whatever>.
1075
1076    Try to forward propagate the ADDR_EXPR into all uses of the SSA_NAME.
1077    Often this will allow for removal of an ADDR_EXPR and INDIRECT_REF
1078    node or for recovery of array indexing from pointer arithmetic.
1079    Returns true, if all uses have been propagated into.  */
1080
1081 static bool
1082 forward_propagate_addr_expr (tree name, tree rhs)
1083 {
1084   int stmt_loop_depth = gimple_bb (SSA_NAME_DEF_STMT (name))->loop_depth;
1085   imm_use_iterator iter;
1086   gimple use_stmt;
1087   bool all = true;
1088   bool single_use_p = has_single_use (name);
1089
1090   FOR_EACH_IMM_USE_STMT (use_stmt, iter, name)
1091     {
1092       bool result;
1093       tree use_rhs;
1094
1095       /* If the use is not in a simple assignment statement, then
1096          there is nothing we can do.  */
1097       if (gimple_code (use_stmt) != GIMPLE_ASSIGN)
1098         {
1099           if (!is_gimple_debug (use_stmt))
1100             all = false;
1101           continue;
1102         }
1103
1104       /* If the use is in a deeper loop nest, then we do not want
1105          to propagate non-invariant ADDR_EXPRs into the loop as that
1106          is likely adding expression evaluations into the loop.  */
1107       if (gimple_bb (use_stmt)->loop_depth > stmt_loop_depth
1108           && !is_gimple_min_invariant (rhs))
1109         {
1110           all = false;
1111           continue;
1112         }
1113
1114       {
1115         gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
1116         result = forward_propagate_addr_expr_1 (name, rhs, &gsi,
1117                                                 single_use_p);
1118         /* If the use has moved to a different statement adjust
1119            the update machinery for the old statement too.  */
1120         if (use_stmt != gsi_stmt (gsi))
1121           {
1122             update_stmt (use_stmt);
1123             use_stmt = gsi_stmt (gsi);
1124           }
1125
1126         update_stmt (use_stmt);
1127       }
1128       all &= result;
1129
1130       /* Remove intermediate now unused copy and conversion chains.  */
1131       use_rhs = gimple_assign_rhs1 (use_stmt);
1132       if (result
1133           && TREE_CODE (gimple_assign_lhs (use_stmt)) == SSA_NAME
1134           && TREE_CODE (use_rhs) == SSA_NAME
1135           && has_zero_uses (gimple_assign_lhs (use_stmt)))
1136         {
1137           gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
1138           release_defs (use_stmt);
1139           gsi_remove (&gsi, true);
1140         }
1141     }
1142
1143   return all && has_zero_uses (name);
1144 }
1145
1146
1147 /* Forward propagate the comparison defined in STMT like
1148    cond_1 = x CMP y to uses of the form
1149      a_1 = (T')cond_1
1150      a_1 = !cond_1
1151      a_1 = cond_1 != 0
1152    Returns true if stmt is now unused.  */
1153
1154 static bool
1155 forward_propagate_comparison (gimple stmt)
1156 {
1157   tree name = gimple_assign_lhs (stmt);
1158   gimple use_stmt;
1159   tree tmp = NULL_TREE;
1160   gimple_stmt_iterator gsi;
1161   enum tree_code code;
1162   tree lhs;
1163
1164   /* Don't propagate ssa names that occur in abnormal phis.  */
1165   if ((TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
1166        && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt)))
1167       || (TREE_CODE (gimple_assign_rhs2 (stmt)) == SSA_NAME
1168         && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs2 (stmt))))
1169     return false;
1170
1171   /* Do not un-cse comparisons.  But propagate through copies.  */
1172   use_stmt = get_prop_dest_stmt (name, &name);
1173   if (!use_stmt
1174       || !is_gimple_assign (use_stmt))
1175     return false;
1176
1177   code = gimple_assign_rhs_code (use_stmt);
1178   lhs = gimple_assign_lhs (use_stmt);
1179   if (!INTEGRAL_TYPE_P (TREE_TYPE (lhs)))
1180     return false;
1181
1182   /* We can propagate the condition into a statement that
1183      computes the logical negation of the comparison result.  */
1184   if ((code == BIT_NOT_EXPR
1185        && TYPE_PRECISION (TREE_TYPE (lhs)) == 1)
1186       || (code == BIT_XOR_EXPR
1187           && integer_onep (gimple_assign_rhs2 (use_stmt))))
1188     {
1189       tree type = TREE_TYPE (gimple_assign_rhs1 (stmt));
1190       bool nans = HONOR_NANS (TYPE_MODE (type));
1191       enum tree_code inv_code;
1192       inv_code = invert_tree_comparison (gimple_assign_rhs_code (stmt), nans);
1193       if (inv_code == ERROR_MARK)
1194         return false;
1195
1196       tmp = build2 (inv_code, TREE_TYPE (lhs), gimple_assign_rhs1 (stmt),
1197                     gimple_assign_rhs2 (stmt));
1198     }
1199   else
1200     return false;
1201
1202   gsi = gsi_for_stmt (use_stmt);
1203   gimple_assign_set_rhs_from_tree (&gsi, unshare_expr (tmp));
1204   use_stmt = gsi_stmt (gsi);
1205   update_stmt (use_stmt);
1206
1207   if (dump_file && (dump_flags & TDF_DETAILS))
1208     {
1209       fprintf (dump_file, "  Replaced '");
1210       print_gimple_expr (dump_file, stmt, 0, dump_flags);
1211       fprintf (dump_file, "' with '");
1212       print_gimple_expr (dump_file, use_stmt, 0, dump_flags);
1213       fprintf (dump_file, "'\n");
1214     }
1215
1216   /* Remove defining statements.  */
1217   return remove_prop_source_from_use (name);
1218 }
1219
1220
1221 /* If we have lhs = ~x (STMT), look and see if earlier we had x = ~y.
1222    If so, we can change STMT into lhs = y which can later be copy
1223    propagated.  Similarly for negation.
1224
1225    This could trivially be formulated as a forward propagation
1226    to immediate uses.  However, we already had an implementation
1227    from DOM which used backward propagation via the use-def links.
1228
1229    It turns out that backward propagation is actually faster as
1230    there's less work to do for each NOT/NEG expression we find.
1231    Backwards propagation needs to look at the statement in a single
1232    backlink.  Forward propagation needs to look at potentially more
1233    than one forward link.
1234
1235    Returns true when the statement was changed.  */
1236
1237 static bool
1238 simplify_not_neg_expr (gimple_stmt_iterator *gsi_p)
1239 {
1240   gimple stmt = gsi_stmt (*gsi_p);
1241   tree rhs = gimple_assign_rhs1 (stmt);
1242   gimple rhs_def_stmt = SSA_NAME_DEF_STMT (rhs);
1243
1244   /* See if the RHS_DEF_STMT has the same form as our statement.  */
1245   if (is_gimple_assign (rhs_def_stmt)
1246       && gimple_assign_rhs_code (rhs_def_stmt) == gimple_assign_rhs_code (stmt))
1247     {
1248       tree rhs_def_operand = gimple_assign_rhs1 (rhs_def_stmt);
1249
1250       /* Verify that RHS_DEF_OPERAND is a suitable SSA_NAME.  */
1251       if (TREE_CODE (rhs_def_operand) == SSA_NAME
1252           && ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs_def_operand))
1253         {
1254           gimple_assign_set_rhs_from_tree (gsi_p, rhs_def_operand);
1255           stmt = gsi_stmt (*gsi_p);
1256           update_stmt (stmt);
1257           return true;
1258         }
1259     }
1260
1261   return false;
1262 }
1263
1264 /* STMT is a SWITCH_EXPR for which we attempt to find equivalent forms of
1265    the condition which we may be able to optimize better.  */
1266
1267 static bool
1268 simplify_gimple_switch (gimple stmt)
1269 {
1270   tree cond = gimple_switch_index (stmt);
1271   tree def, to, ti;
1272   gimple def_stmt;
1273
1274   /* The optimization that we really care about is removing unnecessary
1275      casts.  That will let us do much better in propagating the inferred
1276      constant at the switch target.  */
1277   if (TREE_CODE (cond) == SSA_NAME)
1278     {
1279       def_stmt = SSA_NAME_DEF_STMT (cond);
1280       if (is_gimple_assign (def_stmt))
1281         {
1282           if (gimple_assign_rhs_code (def_stmt) == NOP_EXPR)
1283             {
1284               int need_precision;
1285               bool fail;
1286
1287               def = gimple_assign_rhs1 (def_stmt);
1288
1289               /* ??? Why was Jeff testing this?  We are gimple...  */
1290               gcc_checking_assert (is_gimple_val (def));
1291
1292               to = TREE_TYPE (cond);
1293               ti = TREE_TYPE (def);
1294
1295               /* If we have an extension that preserves value, then we
1296                  can copy the source value into the switch.  */
1297
1298               need_precision = TYPE_PRECISION (ti);
1299               fail = false;
1300               if (! INTEGRAL_TYPE_P (ti))
1301                 fail = true;
1302               else if (TYPE_UNSIGNED (to) && !TYPE_UNSIGNED (ti))
1303                 fail = true;
1304               else if (!TYPE_UNSIGNED (to) && TYPE_UNSIGNED (ti))
1305                 need_precision += 1;
1306               if (TYPE_PRECISION (to) < need_precision)
1307                 fail = true;
1308
1309               if (!fail)
1310                 {
1311                   gimple_switch_set_index (stmt, def);
1312                   update_stmt (stmt);
1313                   return true;
1314                 }
1315             }
1316         }
1317     }
1318
1319   return false;
1320 }
1321
1322 /* For pointers p2 and p1 return p2 - p1 if the
1323    difference is known and constant, otherwise return NULL.  */
1324
1325 static tree
1326 constant_pointer_difference (tree p1, tree p2)
1327 {
1328   int i, j;
1329 #define CPD_ITERATIONS 5
1330   tree exps[2][CPD_ITERATIONS];
1331   tree offs[2][CPD_ITERATIONS];
1332   int cnt[2];
1333
1334   for (i = 0; i < 2; i++)
1335     {
1336       tree p = i ? p1 : p2;
1337       tree off = size_zero_node;
1338       gimple stmt;
1339       enum tree_code code;
1340
1341       /* For each of p1 and p2 we need to iterate at least
1342          twice, to handle ADDR_EXPR directly in p1/p2,
1343          SSA_NAME with ADDR_EXPR or POINTER_PLUS_EXPR etc.
1344          on definition's stmt RHS.  Iterate a few extra times.  */
1345       j = 0;
1346       do
1347         {
1348           if (!POINTER_TYPE_P (TREE_TYPE (p)))
1349             break;
1350           if (TREE_CODE (p) == ADDR_EXPR)
1351             {
1352               tree q = TREE_OPERAND (p, 0);
1353               HOST_WIDE_INT offset;
1354               tree base = get_addr_base_and_unit_offset (q, &offset);
1355               if (base)
1356                 {
1357                   q = base;
1358                   if (offset)
1359                     off = size_binop (PLUS_EXPR, off, size_int (offset));
1360                 }
1361               if (TREE_CODE (q) == MEM_REF
1362                   && TREE_CODE (TREE_OPERAND (q, 0)) == SSA_NAME)
1363                 {
1364                   p = TREE_OPERAND (q, 0);
1365                   off = size_binop (PLUS_EXPR, off,
1366                                     double_int_to_tree (sizetype,
1367                                                         mem_ref_offset (q)));
1368                 }
1369               else
1370                 {
1371                   exps[i][j] = q;
1372                   offs[i][j++] = off;
1373                   break;
1374                 }
1375             }
1376           if (TREE_CODE (p) != SSA_NAME)
1377             break;
1378           exps[i][j] = p;
1379           offs[i][j++] = off;
1380           if (j == CPD_ITERATIONS)
1381             break;
1382           stmt = SSA_NAME_DEF_STMT (p);
1383           if (!is_gimple_assign (stmt) || gimple_assign_lhs (stmt) != p)
1384             break;
1385           code = gimple_assign_rhs_code (stmt);
1386           if (code == POINTER_PLUS_EXPR)
1387             {
1388               if (TREE_CODE (gimple_assign_rhs2 (stmt)) != INTEGER_CST)
1389                 break;
1390               off = size_binop (PLUS_EXPR, off, gimple_assign_rhs2 (stmt));
1391               p = gimple_assign_rhs1 (stmt);
1392             }
1393           else if (code == ADDR_EXPR || code == NOP_EXPR)
1394             p = gimple_assign_rhs1 (stmt);
1395           else
1396             break;
1397         }
1398       while (1);
1399       cnt[i] = j;
1400     }
1401
1402   for (i = 0; i < cnt[0]; i++)
1403     for (j = 0; j < cnt[1]; j++)
1404       if (exps[0][i] == exps[1][j])
1405         return size_binop (MINUS_EXPR, offs[0][i], offs[1][j]);
1406
1407   return NULL_TREE;
1408 }
1409
1410 /* *GSI_P is a GIMPLE_CALL to a builtin function.
1411    Optimize
1412    memcpy (p, "abcd", 4);
1413    memset (p + 4, ' ', 3);
1414    into
1415    memcpy (p, "abcd   ", 7);
1416    call if the latter can be stored by pieces during expansion.  */
1417
1418 static bool
1419 simplify_builtin_call (gimple_stmt_iterator *gsi_p, tree callee2)
1420 {
1421   gimple stmt1, stmt2 = gsi_stmt (*gsi_p);
1422   tree vuse = gimple_vuse (stmt2);
1423   if (vuse == NULL)
1424     return false;
1425   stmt1 = SSA_NAME_DEF_STMT (vuse);
1426
1427   switch (DECL_FUNCTION_CODE (callee2))
1428     {
1429     case BUILT_IN_MEMSET:
1430       if (gimple_call_num_args (stmt2) != 3
1431           || gimple_call_lhs (stmt2)
1432           || CHAR_BIT != 8
1433           || BITS_PER_UNIT != 8)
1434         break;
1435       else
1436         {
1437           tree callee1;
1438           tree ptr1, src1, str1, off1, len1, lhs1;
1439           tree ptr2 = gimple_call_arg (stmt2, 0);
1440           tree val2 = gimple_call_arg (stmt2, 1);
1441           tree len2 = gimple_call_arg (stmt2, 2);
1442           tree diff, vdef, new_str_cst;
1443           gimple use_stmt;
1444           unsigned int ptr1_align;
1445           unsigned HOST_WIDE_INT src_len;
1446           char *src_buf;
1447           use_operand_p use_p;
1448
1449           if (!host_integerp (val2, 0)
1450               || !host_integerp (len2, 1))
1451             break;
1452           if (is_gimple_call (stmt1))
1453             {
1454               /* If first stmt is a call, it needs to be memcpy
1455                  or mempcpy, with string literal as second argument and
1456                  constant length.  */
1457               callee1 = gimple_call_fndecl (stmt1);
1458               if (callee1 == NULL_TREE
1459                   || DECL_BUILT_IN_CLASS (callee1) != BUILT_IN_NORMAL
1460                   || gimple_call_num_args (stmt1) != 3)
1461                 break;
1462               if (DECL_FUNCTION_CODE (callee1) != BUILT_IN_MEMCPY
1463                   && DECL_FUNCTION_CODE (callee1) != BUILT_IN_MEMPCPY)
1464                 break;
1465               ptr1 = gimple_call_arg (stmt1, 0);
1466               src1 = gimple_call_arg (stmt1, 1);
1467               len1 = gimple_call_arg (stmt1, 2);
1468               lhs1 = gimple_call_lhs (stmt1);
1469               if (!host_integerp (len1, 1))
1470                 break;
1471               str1 = string_constant (src1, &off1);
1472               if (str1 == NULL_TREE)
1473                 break;
1474               if (!host_integerp (off1, 1)
1475                   || compare_tree_int (off1, TREE_STRING_LENGTH (str1) - 1) > 0
1476                   || compare_tree_int (len1, TREE_STRING_LENGTH (str1)
1477                                              - tree_low_cst (off1, 1)) > 0
1478                   || TREE_CODE (TREE_TYPE (str1)) != ARRAY_TYPE
1479                   || TYPE_MODE (TREE_TYPE (TREE_TYPE (str1)))
1480                      != TYPE_MODE (char_type_node))
1481                 break;
1482             }
1483           else if (gimple_assign_single_p (stmt1))
1484             {
1485               /* Otherwise look for length 1 memcpy optimized into
1486                  assignment.  */
1487               ptr1 = gimple_assign_lhs (stmt1);
1488               src1 = gimple_assign_rhs1 (stmt1);
1489               if (TREE_CODE (ptr1) != MEM_REF
1490                   || TYPE_MODE (TREE_TYPE (ptr1)) != TYPE_MODE (char_type_node)
1491                   || !host_integerp (src1, 0))
1492                 break;
1493               ptr1 = build_fold_addr_expr (ptr1);
1494               callee1 = NULL_TREE;
1495               len1 = size_one_node;
1496               lhs1 = NULL_TREE;
1497               off1 = size_zero_node;
1498               str1 = NULL_TREE;
1499             }
1500           else
1501             break;
1502
1503           diff = constant_pointer_difference (ptr1, ptr2);
1504           if (diff == NULL && lhs1 != NULL)
1505             {
1506               diff = constant_pointer_difference (lhs1, ptr2);
1507               if (DECL_FUNCTION_CODE (callee1) == BUILT_IN_MEMPCPY
1508                   && diff != NULL)
1509                 diff = size_binop (PLUS_EXPR, diff,
1510                                    fold_convert (sizetype, len1));
1511             }
1512           /* If the difference between the second and first destination pointer
1513              is not constant, or is bigger than memcpy length, bail out.  */
1514           if (diff == NULL
1515               || !host_integerp (diff, 1)
1516               || tree_int_cst_lt (len1, diff))
1517             break;
1518
1519           /* Use maximum of difference plus memset length and memcpy length
1520              as the new memcpy length, if it is too big, bail out.  */
1521           src_len = tree_low_cst (diff, 1);
1522           src_len += tree_low_cst (len2, 1);
1523           if (src_len < (unsigned HOST_WIDE_INT) tree_low_cst (len1, 1))
1524             src_len = tree_low_cst (len1, 1);
1525           if (src_len > 1024)
1526             break;
1527
1528           /* If mempcpy value is used elsewhere, bail out, as mempcpy
1529              with bigger length will return different result.  */
1530           if (lhs1 != NULL_TREE
1531               && DECL_FUNCTION_CODE (callee1) == BUILT_IN_MEMPCPY
1532               && (TREE_CODE (lhs1) != SSA_NAME
1533                   || !single_imm_use (lhs1, &use_p, &use_stmt)
1534                   || use_stmt != stmt2))
1535             break;
1536
1537           /* If anything reads memory in between memcpy and memset
1538              call, the modified memcpy call might change it.  */
1539           vdef = gimple_vdef (stmt1);
1540           if (vdef != NULL
1541               && (!single_imm_use (vdef, &use_p, &use_stmt)
1542                   || use_stmt != stmt2))
1543             break;
1544
1545           ptr1_align = get_pointer_alignment (ptr1);
1546           /* Construct the new source string literal.  */
1547           src_buf = XALLOCAVEC (char, src_len + 1);
1548           if (callee1)
1549             memcpy (src_buf,
1550                     TREE_STRING_POINTER (str1) + tree_low_cst (off1, 1),
1551                     tree_low_cst (len1, 1));
1552           else
1553             src_buf[0] = tree_low_cst (src1, 0);
1554           memset (src_buf + tree_low_cst (diff, 1),
1555                   tree_low_cst (val2, 1), tree_low_cst (len2, 1));
1556           src_buf[src_len] = '\0';
1557           /* Neither builtin_strncpy_read_str nor builtin_memcpy_read_str
1558              handle embedded '\0's.  */
1559           if (strlen (src_buf) != src_len)
1560             break;
1561           rtl_profile_for_bb (gimple_bb (stmt2));
1562           /* If the new memcpy wouldn't be emitted by storing the literal
1563              by pieces, this optimization might enlarge .rodata too much,
1564              as commonly used string literals couldn't be shared any
1565              longer.  */
1566           if (!can_store_by_pieces (src_len,
1567                                     builtin_strncpy_read_str,
1568                                     src_buf, ptr1_align, false))
1569             break;
1570
1571           new_str_cst = build_string_literal (src_len, src_buf);
1572           if (callee1)
1573             {
1574               /* If STMT1 is a mem{,p}cpy call, adjust it and remove
1575                  memset call.  */
1576               if (lhs1 && DECL_FUNCTION_CODE (callee1) == BUILT_IN_MEMPCPY)
1577                 gimple_call_set_lhs (stmt1, NULL_TREE);
1578               gimple_call_set_arg (stmt1, 1, new_str_cst);
1579               gimple_call_set_arg (stmt1, 2,
1580                                    build_int_cst (TREE_TYPE (len1), src_len));
1581               update_stmt (stmt1);
1582               unlink_stmt_vdef (stmt2);
1583               gsi_remove (gsi_p, true);
1584               release_defs (stmt2);
1585               if (lhs1 && DECL_FUNCTION_CODE (callee1) == BUILT_IN_MEMPCPY)
1586                 release_ssa_name (lhs1);
1587               return true;
1588             }
1589           else
1590             {
1591               /* Otherwise, if STMT1 is length 1 memcpy optimized into
1592                  assignment, remove STMT1 and change memset call into
1593                  memcpy call.  */
1594               gimple_stmt_iterator gsi = gsi_for_stmt (stmt1);
1595
1596               if (!is_gimple_val (ptr1))
1597                 ptr1 = force_gimple_operand_gsi (gsi_p, ptr1, true, NULL_TREE,
1598                                                  true, GSI_SAME_STMT);
1599               gimple_call_set_fndecl (stmt2, built_in_decls [BUILT_IN_MEMCPY]);
1600               gimple_call_set_arg (stmt2, 0, ptr1);
1601               gimple_call_set_arg (stmt2, 1, new_str_cst);
1602               gimple_call_set_arg (stmt2, 2,
1603                                    build_int_cst (TREE_TYPE (len2), src_len));
1604               unlink_stmt_vdef (stmt1);
1605               gsi_remove (&gsi, true);
1606               release_defs (stmt1);
1607               update_stmt (stmt2);
1608               return false;
1609             }
1610         }
1611       break;
1612     default:
1613       break;
1614     }
1615   return false;
1616 }
1617
1618 /* Checks if expression has type of one-bit precision, or is a known
1619    truth-valued expression.  */
1620 static bool
1621 truth_valued_ssa_name (tree name)
1622 {
1623   gimple def;
1624   tree type = TREE_TYPE (name);
1625
1626   if (!INTEGRAL_TYPE_P (type))
1627     return false;
1628   /* Don't check here for BOOLEAN_TYPE as the precision isn't
1629      necessarily one and so ~X is not equal to !X.  */
1630   if (TYPE_PRECISION (type) == 1)
1631     return true;
1632   def = SSA_NAME_DEF_STMT (name);
1633   if (is_gimple_assign (def))
1634     return truth_value_p (gimple_assign_rhs_code (def));
1635   return false;
1636 }
1637
1638 /* Helper routine for simplify_bitwise_binary_1 function.
1639    Return for the SSA name NAME the expression X if it mets condition
1640    NAME = !X. Otherwise return NULL_TREE.
1641    Detected patterns for NAME = !X are:
1642      !X and X == 0 for X with integral type.
1643      X ^ 1, X != 1,or ~X for X with integral type with precision of one.  */
1644 static tree
1645 lookup_logical_inverted_value (tree name)
1646 {
1647   tree op1, op2;
1648   enum tree_code code;
1649   gimple def;
1650
1651   /* If name has none-intergal type, or isn't a SSA_NAME, then
1652      return.  */
1653   if (TREE_CODE (name) != SSA_NAME
1654       || !INTEGRAL_TYPE_P (TREE_TYPE (name)))
1655     return NULL_TREE;
1656   def = SSA_NAME_DEF_STMT (name);
1657   if (!is_gimple_assign (def))
1658     return NULL_TREE;
1659
1660   code = gimple_assign_rhs_code (def);
1661   op1 = gimple_assign_rhs1 (def);
1662   op2 = NULL_TREE;
1663
1664   /* Get for EQ_EXPR or BIT_XOR_EXPR operation the second operand.
1665      If CODE isn't an EQ_EXPR, BIT_XOR_EXPR, or BIT_NOT_EXPR, then return.  */
1666   if (code == EQ_EXPR || code == NE_EXPR
1667       || code == BIT_XOR_EXPR)
1668     op2 = gimple_assign_rhs2 (def);
1669
1670   switch (code)
1671     {
1672     case BIT_NOT_EXPR:
1673       if (truth_valued_ssa_name (name))
1674         return op1;
1675       break;
1676     case EQ_EXPR:
1677       /* Check if we have X == 0 and X has an integral type.  */
1678       if (!INTEGRAL_TYPE_P (TREE_TYPE (op1)))
1679         break;
1680       if (integer_zerop (op2))
1681         return op1;
1682       break;
1683     case NE_EXPR:
1684       /* Check if we have X != 1 and X is a truth-valued.  */
1685       if (!INTEGRAL_TYPE_P (TREE_TYPE (op1)))
1686         break;
1687       if (integer_onep (op2) && truth_valued_ssa_name (op1))
1688         return op1;
1689       break;
1690     case BIT_XOR_EXPR:
1691       /* Check if we have X ^ 1 and X is truth valued.  */
1692       if (integer_onep (op2) && truth_valued_ssa_name (op1))
1693         return op1;
1694       break;
1695     default:
1696       break;
1697     }
1698
1699   return NULL_TREE;
1700 }
1701
1702 /* Optimize ARG1 CODE ARG2 to a constant for bitwise binary
1703    operations CODE, if one operand has the logically inverted
1704    value of the other.  */
1705 static tree
1706 simplify_bitwise_binary_1 (enum tree_code code, tree type,
1707                            tree arg1, tree arg2)
1708 {
1709   tree anot;
1710
1711   /* If CODE isn't a bitwise binary operation, return NULL_TREE.  */
1712   if (code != BIT_AND_EXPR && code != BIT_IOR_EXPR
1713       && code != BIT_XOR_EXPR)
1714     return NULL_TREE;
1715
1716   /* First check if operands ARG1 and ARG2 are equal.  If so
1717      return NULL_TREE as this optimization is handled fold_stmt.  */
1718   if (arg1 == arg2)
1719     return NULL_TREE;
1720   /* See if we have in arguments logical-not patterns.  */
1721   if (((anot = lookup_logical_inverted_value (arg1)) == NULL_TREE
1722        || anot != arg2)
1723       && ((anot = lookup_logical_inverted_value (arg2)) == NULL_TREE
1724           || anot != arg1))
1725     return NULL_TREE;
1726
1727   /* X & !X -> 0.  */
1728   if (code == BIT_AND_EXPR)
1729     return fold_convert (type, integer_zero_node);
1730   /* X | !X -> 1 and X ^ !X -> 1, if X is truth-valued.  */
1731   if (truth_valued_ssa_name (anot))
1732     return fold_convert (type, integer_one_node);
1733
1734   /* ??? Otherwise result is (X != 0 ? X : 1).  not handled.  */
1735   return NULL_TREE;
1736 }
1737
1738 /* Simplify bitwise binary operations.
1739    Return true if a transformation applied, otherwise return false.  */
1740
1741 static bool
1742 simplify_bitwise_binary (gimple_stmt_iterator *gsi)
1743 {
1744   gimple stmt = gsi_stmt (*gsi);
1745   tree arg1 = gimple_assign_rhs1 (stmt);
1746   tree arg2 = gimple_assign_rhs2 (stmt);
1747   enum tree_code code = gimple_assign_rhs_code (stmt);
1748   tree res;
1749   gimple def1 = NULL, def2 = NULL;
1750   tree def1_arg1, def2_arg1;
1751   enum tree_code def1_code, def2_code;
1752
1753   def1_code = TREE_CODE (arg1);
1754   def1_arg1 = arg1;
1755   if (TREE_CODE (arg1) == SSA_NAME)
1756     {
1757       def1 = SSA_NAME_DEF_STMT (arg1);
1758       if (is_gimple_assign (def1))
1759         {
1760           def1_code = gimple_assign_rhs_code (def1);
1761           def1_arg1 = gimple_assign_rhs1 (def1);
1762         }
1763     }
1764
1765   def2_code = TREE_CODE (arg2);
1766   def2_arg1 = arg2;
1767   if (TREE_CODE (arg2) == SSA_NAME)
1768     {
1769       def2 = SSA_NAME_DEF_STMT (arg2);
1770       if (is_gimple_assign (def2))
1771         {
1772           def2_code = gimple_assign_rhs_code (def2);
1773           def2_arg1 = gimple_assign_rhs1 (def2);
1774         }
1775     }
1776
1777   /* Try to fold (type) X op CST -> (type) (X op ((type-x) CST)).  */
1778   if (TREE_CODE (arg2) == INTEGER_CST
1779       && CONVERT_EXPR_CODE_P (def1_code)
1780       && INTEGRAL_TYPE_P (TREE_TYPE (def1_arg1))
1781       && int_fits_type_p (arg2, TREE_TYPE (def1_arg1)))
1782     {
1783       gimple newop;
1784       tree tem = create_tmp_reg (TREE_TYPE (def1_arg1), NULL);
1785       newop =
1786         gimple_build_assign_with_ops (code, tem, def1_arg1,
1787                                       fold_convert_loc (gimple_location (stmt),
1788                                                         TREE_TYPE (def1_arg1),
1789                                                         arg2));
1790       tem = make_ssa_name (tem, newop);
1791       gimple_assign_set_lhs (newop, tem);
1792       gimple_set_location (newop, gimple_location (stmt));
1793       gsi_insert_before (gsi, newop, GSI_SAME_STMT);
1794       gimple_assign_set_rhs_with_ops_1 (gsi, NOP_EXPR,
1795                                         tem, NULL_TREE, NULL_TREE);
1796       update_stmt (gsi_stmt (*gsi));
1797       return true;
1798     }
1799
1800   /* For bitwise binary operations apply operand conversions to the
1801      binary operation result instead of to the operands.  This allows
1802      to combine successive conversions and bitwise binary operations.  */
1803   if (CONVERT_EXPR_CODE_P (def1_code)
1804       && CONVERT_EXPR_CODE_P (def2_code)
1805       && types_compatible_p (TREE_TYPE (def1_arg1), TREE_TYPE (def2_arg1))
1806       /* Make sure that the conversion widens the operands, or has same
1807          precision,  or that it changes the operation to a bitfield
1808          precision.  */
1809       && ((TYPE_PRECISION (TREE_TYPE (def1_arg1))
1810            <= TYPE_PRECISION (TREE_TYPE (arg1)))
1811           || (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (arg1)))
1812               != MODE_INT)
1813           || (TYPE_PRECISION (TREE_TYPE (arg1))
1814               != GET_MODE_PRECISION (TYPE_MODE (TREE_TYPE (arg1))))))
1815     {
1816       gimple newop;
1817       tree tem = create_tmp_reg (TREE_TYPE (def1_arg1),
1818                                  NULL);
1819       newop = gimple_build_assign_with_ops (code, tem, def1_arg1, def2_arg1);
1820       tem = make_ssa_name (tem, newop);
1821       gimple_assign_set_lhs (newop, tem);
1822       gimple_set_location (newop, gimple_location (stmt));
1823       gsi_insert_before (gsi, newop, GSI_SAME_STMT);
1824       gimple_assign_set_rhs_with_ops_1 (gsi, NOP_EXPR,
1825                                         tem, NULL_TREE, NULL_TREE);
1826       update_stmt (gsi_stmt (*gsi));
1827       return true;
1828     }
1829
1830   /* (a | CST1) & CST2  ->  (a & CST2) | (CST1 & CST2).  */
1831   if (code == BIT_AND_EXPR
1832       && def1_code == BIT_IOR_EXPR
1833       && TREE_CODE (arg2) == INTEGER_CST
1834       && TREE_CODE (gimple_assign_rhs2 (def1)) == INTEGER_CST)
1835     {
1836       tree cst = fold_build2 (BIT_AND_EXPR, TREE_TYPE (arg2),
1837                               arg2, gimple_assign_rhs2 (def1));
1838       tree tem;
1839       gimple newop;
1840       if (integer_zerop (cst))
1841         {
1842           gimple_assign_set_rhs1 (stmt, def1_arg1);
1843           update_stmt (stmt);
1844           return true;
1845         }
1846       tem = create_tmp_reg (TREE_TYPE (arg2), NULL);
1847       newop = gimple_build_assign_with_ops (BIT_AND_EXPR,
1848                                             tem, def1_arg1, arg2);
1849       tem = make_ssa_name (tem, newop);
1850       gimple_assign_set_lhs (newop, tem);
1851       gimple_set_location (newop, gimple_location (stmt));
1852       /* Make sure to re-process the new stmt as it's walking upwards.  */
1853       gsi_insert_before (gsi, newop, GSI_NEW_STMT);
1854       gimple_assign_set_rhs1 (stmt, tem);
1855       gimple_assign_set_rhs2 (stmt, cst);
1856       gimple_assign_set_rhs_code (stmt, BIT_IOR_EXPR);
1857       update_stmt (stmt);
1858       return true;
1859     }
1860
1861   /* Combine successive equal operations with constants.  */
1862   if ((code == BIT_AND_EXPR
1863        || code == BIT_IOR_EXPR
1864        || code == BIT_XOR_EXPR)
1865       && def1_code == code
1866       && TREE_CODE (arg2) == INTEGER_CST
1867       && TREE_CODE (gimple_assign_rhs2 (def1)) == INTEGER_CST)
1868     {
1869       tree cst = fold_build2 (code, TREE_TYPE (arg2),
1870                               arg2, gimple_assign_rhs2 (def1));
1871       gimple_assign_set_rhs1 (stmt, def1_arg1);
1872       gimple_assign_set_rhs2 (stmt, cst);
1873       update_stmt (stmt);
1874       return true;
1875     }
1876
1877   /* Canonicalize X ^ ~0 to ~X.  */
1878   if (code == BIT_XOR_EXPR
1879       && TREE_CODE (arg2) == INTEGER_CST
1880       && integer_all_onesp (arg2))
1881     {
1882       gimple_assign_set_rhs_with_ops (gsi, BIT_NOT_EXPR, arg1, NULL_TREE);
1883       gcc_assert (gsi_stmt (*gsi) == stmt);
1884       update_stmt (stmt);
1885       return true;
1886     }
1887
1888   /* Try simple folding for X op !X, and X op X.  */
1889   res = simplify_bitwise_binary_1 (code, TREE_TYPE (arg1), arg1, arg2);
1890   if (res != NULL_TREE)
1891     {
1892       gimple_assign_set_rhs_from_tree (gsi, res);
1893       update_stmt (gsi_stmt (*gsi));
1894       return true;
1895     }
1896
1897   return false;
1898 }
1899
1900
1901 /* Perform re-associations of the plus or minus statement STMT that are
1902    always permitted.  Returns true if the CFG was changed.  */
1903
1904 static bool
1905 associate_plusminus (gimple_stmt_iterator *gsi)
1906 {
1907   gimple stmt = gsi_stmt (*gsi);
1908   tree rhs1 = gimple_assign_rhs1 (stmt);
1909   tree rhs2 = gimple_assign_rhs2 (stmt);
1910   enum tree_code code = gimple_assign_rhs_code (stmt);
1911   bool changed;
1912
1913   /* We can't reassociate at all for saturating types.  */
1914   if (TYPE_SATURATING (TREE_TYPE (rhs1)))
1915     return false;
1916
1917   /* First contract negates.  */
1918   do
1919     {
1920       changed = false;
1921
1922       /* A +- (-B) -> A -+ B.  */
1923       if (TREE_CODE (rhs2) == SSA_NAME)
1924         {
1925           gimple def_stmt = SSA_NAME_DEF_STMT (rhs2);
1926           if (is_gimple_assign (def_stmt)
1927               && gimple_assign_rhs_code (def_stmt) == NEGATE_EXPR
1928               && can_propagate_from (def_stmt))
1929             {
1930               code = (code == MINUS_EXPR) ? PLUS_EXPR : MINUS_EXPR;
1931               gimple_assign_set_rhs_code (stmt, code);
1932               rhs2 = gimple_assign_rhs1 (def_stmt);
1933               gimple_assign_set_rhs2 (stmt, rhs2);
1934               gimple_set_modified (stmt, true);
1935               changed = true;
1936             }
1937         }
1938
1939       /* (-A) + B -> B - A.  */
1940       if (TREE_CODE (rhs1) == SSA_NAME
1941           && code == PLUS_EXPR)
1942         {
1943           gimple def_stmt = SSA_NAME_DEF_STMT (rhs1);
1944           if (is_gimple_assign (def_stmt)
1945               && gimple_assign_rhs_code (def_stmt) == NEGATE_EXPR
1946               && can_propagate_from (def_stmt))
1947             {
1948               code = MINUS_EXPR;
1949               gimple_assign_set_rhs_code (stmt, code);
1950               rhs1 = rhs2;
1951               gimple_assign_set_rhs1 (stmt, rhs1);
1952               rhs2 = gimple_assign_rhs1 (def_stmt);
1953               gimple_assign_set_rhs2 (stmt, rhs2);
1954               gimple_set_modified (stmt, true);
1955               changed = true;
1956             }
1957         }
1958     }
1959   while (changed);
1960
1961   /* We can't reassociate floating-point or fixed-point plus or minus
1962      because of saturation to +-Inf.  */
1963   if (FLOAT_TYPE_P (TREE_TYPE (rhs1))
1964       || FIXED_POINT_TYPE_P (TREE_TYPE (rhs1)))
1965     goto out;
1966
1967   /* Second match patterns that allow contracting a plus-minus pair
1968      irrespective of overflow issues.
1969
1970         (A +- B) - A       ->  +- B
1971         (A +- B) -+ B      ->  A
1972         (CST +- A) +- CST  ->  CST +- A
1973         (A + CST) +- CST   ->  A + CST
1974         ~A + A             ->  -1
1975         ~A + 1             ->  -A
1976         A - (A +- B)       ->  -+ B
1977         A +- (B +- A)      ->  +- B
1978         CST +- (CST +- A)  ->  CST +- A
1979         CST +- (A +- CST)  ->  CST +- A
1980         A + ~A             ->  -1
1981
1982      via commutating the addition and contracting operations to zero
1983      by reassociation.  */
1984
1985   if (TREE_CODE (rhs1) == SSA_NAME)
1986     {
1987       gimple def_stmt = SSA_NAME_DEF_STMT (rhs1);
1988       if (is_gimple_assign (def_stmt) && can_propagate_from (def_stmt))
1989         {
1990           enum tree_code def_code = gimple_assign_rhs_code (def_stmt);
1991           if (def_code == PLUS_EXPR
1992               || def_code == MINUS_EXPR)
1993             {
1994               tree def_rhs1 = gimple_assign_rhs1 (def_stmt);
1995               tree def_rhs2 = gimple_assign_rhs2 (def_stmt);
1996               if (operand_equal_p (def_rhs1, rhs2, 0)
1997                   && code == MINUS_EXPR)
1998                 {
1999                   /* (A +- B) - A -> +- B.  */
2000                   code = ((def_code == PLUS_EXPR)
2001                           ? TREE_CODE (def_rhs2) : NEGATE_EXPR);
2002                   rhs1 = def_rhs2;
2003                   rhs2 = NULL_TREE;
2004                   gimple_assign_set_rhs_with_ops (gsi, code, rhs1, NULL_TREE);
2005                   gcc_assert (gsi_stmt (*gsi) == stmt);
2006                   gimple_set_modified (stmt, true);
2007                 }
2008               else if (operand_equal_p (def_rhs2, rhs2, 0)
2009                        && code != def_code)
2010                 {
2011                   /* (A +- B) -+ B -> A.  */
2012                   code = TREE_CODE (def_rhs1);
2013                   rhs1 = def_rhs1;
2014                   rhs2 = NULL_TREE;
2015                   gimple_assign_set_rhs_with_ops (gsi, code, rhs1, NULL_TREE);
2016                   gcc_assert (gsi_stmt (*gsi) == stmt);
2017                   gimple_set_modified (stmt, true);
2018                 }
2019               else if (TREE_CODE (rhs2) == INTEGER_CST
2020                        && TREE_CODE (def_rhs1) == INTEGER_CST)
2021                 {
2022                   /* (CST +- A) +- CST -> CST +- A.  */
2023                   tree cst = fold_binary (code, TREE_TYPE (rhs1),
2024                                           def_rhs1, rhs2);
2025                   if (cst && !TREE_OVERFLOW (cst))
2026                     {
2027                       code = def_code;
2028                       gimple_assign_set_rhs_code (stmt, code);
2029                       rhs1 = cst;
2030                       gimple_assign_set_rhs1 (stmt, rhs1);
2031                       rhs2 = def_rhs2;
2032                       gimple_assign_set_rhs2 (stmt, rhs2);
2033                       gimple_set_modified (stmt, true);
2034                     }
2035                 }
2036               else if (TREE_CODE (rhs2) == INTEGER_CST
2037                        && TREE_CODE (def_rhs2) == INTEGER_CST
2038                        && def_code == PLUS_EXPR)
2039                 {
2040                   /* (A + CST) +- CST -> A + CST.  */
2041                   tree cst = fold_binary (code, TREE_TYPE (rhs1),
2042                                           def_rhs2, rhs2);
2043                   if (cst && !TREE_OVERFLOW (cst))
2044                     {
2045                       code = PLUS_EXPR;
2046                       gimple_assign_set_rhs_code (stmt, code);
2047                       rhs1 = def_rhs1;
2048                       gimple_assign_set_rhs1 (stmt, rhs1);
2049                       rhs2 = cst;
2050                       gimple_assign_set_rhs2 (stmt, rhs2);
2051                       gimple_set_modified (stmt, true);
2052                     }
2053                 }
2054             }
2055           else if (def_code == BIT_NOT_EXPR
2056                    && INTEGRAL_TYPE_P (TREE_TYPE (rhs1)))
2057             {
2058               tree def_rhs1 = gimple_assign_rhs1 (def_stmt);
2059               if (code == PLUS_EXPR
2060                   && operand_equal_p (def_rhs1, rhs2, 0))
2061                 {
2062                   /* ~A + A -> -1.  */
2063                   code = INTEGER_CST;
2064                   rhs1 = build_int_cst_type (TREE_TYPE (rhs2), -1);
2065                   rhs2 = NULL_TREE;
2066                   gimple_assign_set_rhs_with_ops (gsi, code, rhs1, NULL_TREE);
2067                   gcc_assert (gsi_stmt (*gsi) == stmt);
2068                   gimple_set_modified (stmt, true);
2069                 }
2070               else if (code == PLUS_EXPR
2071                        && integer_onep (rhs1))
2072                 {
2073                   /* ~A + 1 -> -A.  */
2074                   code = NEGATE_EXPR;
2075                   rhs1 = def_rhs1;
2076                   rhs2 = NULL_TREE;
2077                   gimple_assign_set_rhs_with_ops (gsi, code, rhs1, NULL_TREE);
2078                   gcc_assert (gsi_stmt (*gsi) == stmt);
2079                   gimple_set_modified (stmt, true);
2080                 }
2081             }
2082         }
2083     }
2084
2085   if (rhs2 && TREE_CODE (rhs2) == SSA_NAME)
2086     {
2087       gimple def_stmt = SSA_NAME_DEF_STMT (rhs2);
2088       if (is_gimple_assign (def_stmt) && can_propagate_from (def_stmt))
2089         {
2090           enum tree_code def_code = gimple_assign_rhs_code (def_stmt);
2091           if (def_code == PLUS_EXPR
2092               || def_code == MINUS_EXPR)
2093             {
2094               tree def_rhs1 = gimple_assign_rhs1 (def_stmt);
2095               tree def_rhs2 = gimple_assign_rhs2 (def_stmt);
2096               if (operand_equal_p (def_rhs1, rhs1, 0)
2097                   && code == MINUS_EXPR)
2098                 {
2099                   /* A - (A +- B) -> -+ B.  */
2100                   code = ((def_code == PLUS_EXPR)
2101                           ? NEGATE_EXPR : TREE_CODE (def_rhs2));
2102                   rhs1 = def_rhs2;
2103                   rhs2 = NULL_TREE;
2104                   gimple_assign_set_rhs_with_ops (gsi, code, rhs1, NULL_TREE);
2105                   gcc_assert (gsi_stmt (*gsi) == stmt);
2106                   gimple_set_modified (stmt, true);
2107                 }
2108               else if (operand_equal_p (def_rhs2, rhs1, 0)
2109                        && code != def_code)
2110                 {
2111                   /* A +- (B +- A) -> +- B.  */
2112                   code = ((code == PLUS_EXPR)
2113                           ? TREE_CODE (def_rhs1) : NEGATE_EXPR);
2114                   rhs1 = def_rhs1;
2115                   rhs2 = NULL_TREE;
2116                   gimple_assign_set_rhs_with_ops (gsi, code, rhs1, NULL_TREE);
2117                   gcc_assert (gsi_stmt (*gsi) == stmt);
2118                   gimple_set_modified (stmt, true);
2119                 }
2120               else if (TREE_CODE (rhs1) == INTEGER_CST
2121                        && TREE_CODE (def_rhs1) == INTEGER_CST)
2122                 {
2123                   /* CST +- (CST +- A) -> CST +- A.  */
2124                   tree cst = fold_binary (code, TREE_TYPE (rhs2),
2125                                           rhs1, def_rhs1);
2126                   if (cst && !TREE_OVERFLOW (cst))
2127                     {
2128                       code = (code == def_code ? PLUS_EXPR : MINUS_EXPR);
2129                       gimple_assign_set_rhs_code (stmt, code);
2130                       rhs1 = cst;
2131                       gimple_assign_set_rhs1 (stmt, rhs1);
2132                       rhs2 = def_rhs2;
2133                       gimple_assign_set_rhs2 (stmt, rhs2);
2134                       gimple_set_modified (stmt, true);
2135                     }
2136                 }
2137               else if (TREE_CODE (rhs1) == INTEGER_CST
2138                        && TREE_CODE (def_rhs2) == INTEGER_CST)
2139                 {
2140                   /* CST +- (A +- CST) -> CST +- A.  */
2141                   tree cst = fold_binary (def_code == code
2142                                           ? PLUS_EXPR : MINUS_EXPR,
2143                                           TREE_TYPE (rhs2),
2144                                           rhs1, def_rhs2);
2145                   if (cst && !TREE_OVERFLOW (cst))
2146                     {
2147                       rhs1 = cst;
2148                       gimple_assign_set_rhs1 (stmt, rhs1);
2149                       rhs2 = def_rhs1;
2150                       gimple_assign_set_rhs2 (stmt, rhs2);
2151                       gimple_set_modified (stmt, true);
2152                     }
2153                 }
2154             }
2155           else if (def_code == BIT_NOT_EXPR
2156                    && INTEGRAL_TYPE_P (TREE_TYPE (rhs2)))
2157             {
2158               tree def_rhs1 = gimple_assign_rhs1 (def_stmt);
2159               if (code == PLUS_EXPR
2160                   && operand_equal_p (def_rhs1, rhs1, 0))
2161                 {
2162                   /* A + ~A -> -1.  */
2163                   code = INTEGER_CST;
2164                   rhs1 = build_int_cst_type (TREE_TYPE (rhs1), -1);
2165                   rhs2 = NULL_TREE;
2166                   gimple_assign_set_rhs_with_ops (gsi, code, rhs1, NULL_TREE);
2167                   gcc_assert (gsi_stmt (*gsi) == stmt);
2168                   gimple_set_modified (stmt, true);
2169                 }
2170             }
2171         }
2172     }
2173
2174 out:
2175   if (gimple_modified_p (stmt))
2176     {
2177       fold_stmt_inplace (gsi);
2178       update_stmt (stmt);
2179       if (maybe_clean_or_replace_eh_stmt (stmt, stmt)
2180           && gimple_purge_dead_eh_edges (gimple_bb (stmt)))
2181         return true;
2182     }
2183
2184   return false;
2185 }
2186
2187 /* Combine two conversions in a row for the second conversion at *GSI.
2188    Returns 1 if there were any changes made, 2 if cfg-cleanup needs to
2189    run.  Else it returns 0.  */
2190
2191 static int
2192 combine_conversions (gimple_stmt_iterator *gsi)
2193 {
2194   gimple stmt = gsi_stmt (*gsi);
2195   gimple def_stmt;
2196   tree op0, lhs;
2197   enum tree_code code = gimple_assign_rhs_code (stmt);
2198
2199   gcc_checking_assert (CONVERT_EXPR_CODE_P (code)
2200                        || code == FLOAT_EXPR
2201                        || code == FIX_TRUNC_EXPR);
2202
2203   lhs = gimple_assign_lhs (stmt);
2204   op0 = gimple_assign_rhs1 (stmt);
2205   if (useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (op0)))
2206     {
2207       gimple_assign_set_rhs_code (stmt, TREE_CODE (op0));
2208       return 1;
2209     }
2210
2211   if (TREE_CODE (op0) != SSA_NAME)
2212     return 0;
2213
2214   def_stmt = SSA_NAME_DEF_STMT (op0);
2215   if (!is_gimple_assign (def_stmt))
2216     return 0;
2217
2218   if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt)))
2219     {
2220       tree defop0 = gimple_assign_rhs1 (def_stmt);
2221       tree type = TREE_TYPE (lhs);
2222       tree inside_type = TREE_TYPE (defop0);
2223       tree inter_type = TREE_TYPE (op0);
2224       int inside_int = INTEGRAL_TYPE_P (inside_type);
2225       int inside_ptr = POINTER_TYPE_P (inside_type);
2226       int inside_float = FLOAT_TYPE_P (inside_type);
2227       int inside_vec = TREE_CODE (inside_type) == VECTOR_TYPE;
2228       unsigned int inside_prec = TYPE_PRECISION (inside_type);
2229       int inside_unsignedp = TYPE_UNSIGNED (inside_type);
2230       int inter_int = INTEGRAL_TYPE_P (inter_type);
2231       int inter_ptr = POINTER_TYPE_P (inter_type);
2232       int inter_float = FLOAT_TYPE_P (inter_type);
2233       int inter_vec = TREE_CODE (inter_type) == VECTOR_TYPE;
2234       unsigned int inter_prec = TYPE_PRECISION (inter_type);
2235       int inter_unsignedp = TYPE_UNSIGNED (inter_type);
2236       int final_int = INTEGRAL_TYPE_P (type);
2237       int final_ptr = POINTER_TYPE_P (type);
2238       int final_float = FLOAT_TYPE_P (type);
2239       int final_vec = TREE_CODE (type) == VECTOR_TYPE;
2240       unsigned int final_prec = TYPE_PRECISION (type);
2241       int final_unsignedp = TYPE_UNSIGNED (type);
2242
2243       /* In addition to the cases of two conversions in a row
2244          handled below, if we are converting something to its own
2245          type via an object of identical or wider precision, neither
2246          conversion is needed.  */
2247       if (useless_type_conversion_p (type, inside_type)
2248           && (((inter_int || inter_ptr) && final_int)
2249               || (inter_float && final_float))
2250           && inter_prec >= final_prec)
2251         {
2252           gimple_assign_set_rhs1 (stmt, unshare_expr (defop0));
2253           gimple_assign_set_rhs_code (stmt, TREE_CODE (defop0));
2254           update_stmt (stmt);
2255           return remove_prop_source_from_use (op0) ? 2 : 1;
2256         }
2257
2258       /* Likewise, if the intermediate and initial types are either both
2259          float or both integer, we don't need the middle conversion if the
2260          former is wider than the latter and doesn't change the signedness
2261          (for integers).  Avoid this if the final type is a pointer since
2262          then we sometimes need the middle conversion.  Likewise if the
2263          final type has a precision not equal to the size of its mode.  */
2264       if (((inter_int && inside_int)
2265            || (inter_float && inside_float)
2266            || (inter_vec && inside_vec))
2267           && inter_prec >= inside_prec
2268           && (inter_float || inter_vec
2269               || inter_unsignedp == inside_unsignedp)
2270           && ! (final_prec != GET_MODE_BITSIZE (TYPE_MODE (type))
2271                 && TYPE_MODE (type) == TYPE_MODE (inter_type))
2272           && ! final_ptr
2273           && (! final_vec || inter_prec == inside_prec))
2274         {
2275           gimple_assign_set_rhs1 (stmt, defop0);
2276           update_stmt (stmt);
2277           return remove_prop_source_from_use (op0) ? 2 : 1;
2278         }
2279
2280       /* If we have a sign-extension of a zero-extended value, we can
2281          replace that by a single zero-extension.  */
2282       if (inside_int && inter_int && final_int
2283           && inside_prec < inter_prec && inter_prec < final_prec
2284           && inside_unsignedp && !inter_unsignedp)
2285         {
2286           gimple_assign_set_rhs1 (stmt, defop0);
2287           update_stmt (stmt);
2288           return remove_prop_source_from_use (op0) ? 2 : 1;
2289         }
2290
2291       /* Two conversions in a row are not needed unless:
2292          - some conversion is floating-point (overstrict for now), or
2293          - some conversion is a vector (overstrict for now), or
2294          - the intermediate type is narrower than both initial and
2295          final, or
2296          - the intermediate type and innermost type differ in signedness,
2297          and the outermost type is wider than the intermediate, or
2298          - the initial type is a pointer type and the precisions of the
2299          intermediate and final types differ, or
2300          - the final type is a pointer type and the precisions of the
2301          initial and intermediate types differ.  */
2302       if (! inside_float && ! inter_float && ! final_float
2303           && ! inside_vec && ! inter_vec && ! final_vec
2304           && (inter_prec >= inside_prec || inter_prec >= final_prec)
2305           && ! (inside_int && inter_int
2306                 && inter_unsignedp != inside_unsignedp
2307                 && inter_prec < final_prec)
2308           && ((inter_unsignedp && inter_prec > inside_prec)
2309               == (final_unsignedp && final_prec > inter_prec))
2310           && ! (inside_ptr && inter_prec != final_prec)
2311           && ! (final_ptr && inside_prec != inter_prec)
2312           && ! (final_prec != GET_MODE_BITSIZE (TYPE_MODE (type))
2313                 && TYPE_MODE (type) == TYPE_MODE (inter_type)))
2314         {
2315           gimple_assign_set_rhs1 (stmt, defop0);
2316           update_stmt (stmt);
2317           return remove_prop_source_from_use (op0) ? 2 : 1;
2318         }
2319
2320       /* A truncation to an unsigned type should be canonicalized as
2321          bitwise and of a mask.  */
2322       if (final_int && inter_int && inside_int
2323           && final_prec == inside_prec
2324           && final_prec > inter_prec
2325           && inter_unsignedp)
2326         {
2327           tree tem;
2328           tem = fold_build2 (BIT_AND_EXPR, inside_type,
2329                              defop0,
2330                              double_int_to_tree
2331                                (inside_type, double_int_mask (inter_prec)));
2332           if (!useless_type_conversion_p (type, inside_type))
2333             {
2334               tem = force_gimple_operand_gsi (gsi, tem, true, NULL_TREE, true,
2335                                               GSI_SAME_STMT);
2336               gimple_assign_set_rhs1 (stmt, tem);
2337             }
2338           else
2339             gimple_assign_set_rhs_from_tree (gsi, tem);
2340           update_stmt (gsi_stmt (*gsi));
2341           return 1;
2342         }
2343     }
2344
2345   return 0;
2346 }
2347
2348 /* Main entry point for the forward propagation and statement combine
2349    optimizer.  */
2350
2351 static unsigned int
2352 ssa_forward_propagate_and_combine (void)
2353 {
2354   basic_block bb;
2355   unsigned int todoflags = 0;
2356
2357   cfg_changed = false;
2358
2359   FOR_EACH_BB (bb)
2360     {
2361       gimple_stmt_iterator gsi, prev;
2362       bool prev_initialized;
2363
2364       /* Apply forward propagation to all stmts in the basic-block.
2365          Note we update GSI within the loop as necessary.  */
2366       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); )
2367         {
2368           gimple stmt = gsi_stmt (gsi);
2369           tree lhs, rhs;
2370           enum tree_code code;
2371
2372           if (!is_gimple_assign (stmt))
2373             {
2374               gsi_next (&gsi);
2375               continue;
2376             }
2377
2378           lhs = gimple_assign_lhs (stmt);
2379           rhs = gimple_assign_rhs1 (stmt);
2380           code = gimple_assign_rhs_code (stmt);
2381           if (TREE_CODE (lhs) != SSA_NAME
2382               || has_zero_uses (lhs))
2383             {
2384               gsi_next (&gsi);
2385               continue;
2386             }
2387
2388           /* If this statement sets an SSA_NAME to an address,
2389              try to propagate the address into the uses of the SSA_NAME.  */
2390           if (code == ADDR_EXPR
2391               /* Handle pointer conversions on invariant addresses
2392                  as well, as this is valid gimple.  */
2393               || (CONVERT_EXPR_CODE_P (code)
2394                   && TREE_CODE (rhs) == ADDR_EXPR
2395                   && POINTER_TYPE_P (TREE_TYPE (lhs))))
2396             {
2397               tree base = get_base_address (TREE_OPERAND (rhs, 0));
2398               if ((!base
2399                    || !DECL_P (base)
2400                    || decl_address_invariant_p (base))
2401                   && !stmt_references_abnormal_ssa_name (stmt)
2402                   && forward_propagate_addr_expr (lhs, rhs))
2403                 {
2404                   release_defs (stmt);
2405                   todoflags |= TODO_remove_unused_locals;
2406                   gsi_remove (&gsi, true);
2407                 }
2408               else
2409                 gsi_next (&gsi);
2410             }
2411           else if (code == POINTER_PLUS_EXPR)
2412             {
2413               tree off = gimple_assign_rhs2 (stmt);
2414               if (TREE_CODE (off) == INTEGER_CST
2415                   && can_propagate_from (stmt)
2416                   && !simple_iv_increment_p (stmt)
2417                   /* ???  Better adjust the interface to that function
2418                      instead of building new trees here.  */
2419                   && forward_propagate_addr_expr
2420                        (lhs,
2421                         build1_loc (gimple_location (stmt),
2422                                     ADDR_EXPR, TREE_TYPE (rhs),
2423                                     fold_build2 (MEM_REF,
2424                                                  TREE_TYPE (TREE_TYPE (rhs)),
2425                                                  rhs,
2426                                                  fold_convert (ptr_type_node,
2427                                                                off)))))
2428                 {
2429                   release_defs (stmt);
2430                   todoflags |= TODO_remove_unused_locals;
2431                   gsi_remove (&gsi, true);
2432                 }
2433               else if (is_gimple_min_invariant (rhs))
2434                 {
2435                   /* Make sure to fold &a[0] + off_1 here.  */
2436                   fold_stmt_inplace (&gsi);
2437                   update_stmt (stmt);
2438                   if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR)
2439                     gsi_next (&gsi);
2440                 }
2441               else
2442                 gsi_next (&gsi);
2443             }
2444           else if (TREE_CODE_CLASS (code) == tcc_comparison)
2445             {
2446               if (forward_propagate_comparison (stmt))
2447                 cfg_changed = true;
2448               gsi_next (&gsi);
2449             }
2450           else
2451             gsi_next (&gsi);
2452         }
2453
2454       /* Combine stmts with the stmts defining their operands.
2455          Note we update GSI within the loop as necessary.  */
2456       prev_initialized = false;
2457       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi);)
2458         {
2459           gimple stmt = gsi_stmt (gsi);
2460           bool changed = false;
2461
2462           switch (gimple_code (stmt))
2463             {
2464             case GIMPLE_ASSIGN:
2465               {
2466                 tree rhs1 = gimple_assign_rhs1 (stmt);
2467                 enum tree_code code = gimple_assign_rhs_code (stmt);
2468
2469                 if ((code == BIT_NOT_EXPR
2470                      || code == NEGATE_EXPR)
2471                     && TREE_CODE (rhs1) == SSA_NAME)
2472                   changed = simplify_not_neg_expr (&gsi);
2473                 else if (code == COND_EXPR)
2474                   {
2475                     /* In this case the entire COND_EXPR is in rhs1. */
2476                     changed |= forward_propagate_into_cond (&gsi);
2477                     stmt = gsi_stmt (gsi);
2478                   }
2479                 else if (TREE_CODE_CLASS (code) == tcc_comparison)
2480                   {
2481                     int did_something;
2482                     did_something = forward_propagate_into_comparison (&gsi);
2483                     if (did_something == 2)
2484                       cfg_changed = true;
2485                     changed = did_something != 0;
2486                   }
2487                 else if (code == BIT_AND_EXPR
2488                          || code == BIT_IOR_EXPR
2489                          || code == BIT_XOR_EXPR)
2490                   changed = simplify_bitwise_binary (&gsi);
2491                 else if (code == PLUS_EXPR
2492                          || code == MINUS_EXPR)
2493                   changed = associate_plusminus (&gsi);
2494                 else if (CONVERT_EXPR_CODE_P (code)
2495                          || code == FLOAT_EXPR
2496                          || code == FIX_TRUNC_EXPR)
2497                   {
2498                     int did_something = combine_conversions (&gsi);
2499                     if (did_something == 2)
2500                       cfg_changed = true;
2501                     changed = did_something != 0;
2502                   }
2503                 break;
2504               }
2505
2506             case GIMPLE_SWITCH:
2507               changed = simplify_gimple_switch (stmt);
2508               break;
2509
2510             case GIMPLE_COND:
2511               {
2512                 int did_something;
2513                 did_something = forward_propagate_into_gimple_cond (stmt);
2514                 if (did_something == 2)
2515                   cfg_changed = true;
2516                 changed = did_something != 0;
2517                 break;
2518               }
2519
2520             case GIMPLE_CALL:
2521               {
2522                 tree callee = gimple_call_fndecl (stmt);
2523                 if (callee != NULL_TREE
2524                     && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL)
2525                   changed = simplify_builtin_call (&gsi, callee);
2526                 break;
2527               }
2528
2529             default:;
2530             }
2531
2532           if (changed)
2533             {
2534               /* If the stmt changed then re-visit it and the statements
2535                  inserted before it.  */
2536               if (!prev_initialized)
2537                 gsi = gsi_start_bb (bb);
2538               else
2539                 {
2540                   gsi = prev;
2541                   gsi_next (&gsi);
2542                 }
2543             }
2544           else
2545             {
2546               prev = gsi;
2547               prev_initialized = true;
2548               gsi_next (&gsi);
2549             }
2550         }
2551     }
2552
2553   if (cfg_changed)
2554     todoflags |= TODO_cleanup_cfg;
2555
2556   return todoflags;
2557 }
2558
2559
2560 static bool
2561 gate_forwprop (void)
2562 {
2563   return flag_tree_forwprop;
2564 }
2565
2566 struct gimple_opt_pass pass_forwprop =
2567 {
2568  {
2569   GIMPLE_PASS,
2570   "forwprop",                   /* name */
2571   gate_forwprop,                /* gate */
2572   ssa_forward_propagate_and_combine,    /* execute */
2573   NULL,                         /* sub */
2574   NULL,                         /* next */
2575   0,                            /* static_pass_number */
2576   TV_TREE_FORWPROP,             /* tv_id */
2577   PROP_cfg | PROP_ssa,          /* properties_required */
2578   0,                            /* properties_provided */
2579   0,                            /* properties_destroyed */
2580   0,                            /* todo_flags_start */
2581   TODO_ggc_collect
2582   | TODO_update_ssa
2583   | TODO_verify_ssa             /* todo_flags_finish */
2584  }
2585 };