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 type = TREE_TYPE (gimple_assign_lhs (stmt));
 469   tree rhs1 = gimple_assign_rhs1 (stmt);
 470   tree rhs2 = gimple_assign_rhs2 (stmt);
 471
 472   /* Combine the comparison with defining statements.  */
 473   tmp = forward_propagate_into_comparison_1 (stmt,
 474                                              gimple_assign_rhs_code (stmt),
 475                                              type, rhs1, rhs2);
 476   if (tmp && useless_type_conversion_p (type, TREE_TYPE (tmp)))
 477     {
 478       gimple_assign_set_rhs_from_tree (gsi, tmp);
 479       fold_stmt (gsi);
 480       update_stmt (gsi_stmt (*gsi));
 481
 482       if (TREE_CODE (rhs1) == SSA_NAME)
 483         cfg_changed |= remove_prop_source_from_use (rhs1);
 484       if (TREE_CODE (rhs2) == SSA_NAME)
 485         cfg_changed |= remove_prop_source_from_use (rhs2);
 486       return cfg_changed ? 2 : 1;
 487     }
 488
 489   return 0;
 490 }
 491
 492 /* Propagate from the ssa name definition statements of COND_EXPR
 493    in GIMPLE_COND statement STMT into the conditional if that simplifies it.
 494    Returns zero if no statement was changed, one if there were
 495    changes and two if cfg_cleanup needs to run.
 496
 497    This must be kept in sync with forward_propagate_into_cond.  */
 498
 499 static int
 500 forward_propagate_into_gimple_cond (gimple stmt)
 501 {
 502   tree tmp;
 503   enum tree_code code = gimple_cond_code (stmt);
 504   bool cfg_changed = false;
 505   tree rhs1 = gimple_cond_lhs (stmt);
 506   tree rhs2 = gimple_cond_rhs (stmt);
 507
 508   /* We can do tree combining on SSA_NAME and comparison expressions.  */
 509   if (TREE_CODE_CLASS (gimple_cond_code (stmt)) != tcc_comparison)
 510     return 0;
 511
 512   tmp = forward_propagate_into_comparison_1 (stmt, code,
 513                                              boolean_type_node,
 514                                              rhs1, rhs2);
 515   if (tmp)
 516     {
 517       if (dump_file && tmp)
 518         {
 519           fprintf (dump_file, "  Replaced '");
 520           print_gimple_expr (dump_file, stmt, 0, 0);
 521           fprintf (dump_file, "' with '");
 522           print_generic_expr (dump_file, tmp, 0);
 523           fprintf (dump_file, "'\n");
 524         }
 525
 526       gimple_cond_set_condition_from_tree (stmt, unshare_expr (tmp));
 527       update_stmt (stmt);
 528
 529       if (TREE_CODE (rhs1) == SSA_NAME)
 530         cfg_changed |= remove_prop_source_from_use (rhs1);
 531       if (TREE_CODE (rhs2) == SSA_NAME)
 532         cfg_changed |= remove_prop_source_from_use (rhs2);
 533       return (cfg_changed || is_gimple_min_invariant (tmp)) ? 2 : 1;
 534     }
 535
 536   /* Canonicalize _Bool == 0 and _Bool != 1 to _Bool != 0 by swapping edges.  */
 537   if ((TREE_CODE (TREE_TYPE (rhs1)) == BOOLEAN_TYPE
 538        || (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
 539            && TYPE_PRECISION (TREE_TYPE (rhs1)) == 1))
 540       && ((code == EQ_EXPR
 541            && integer_zerop (rhs2))
 542           || (code == NE_EXPR
 543               && integer_onep (rhs2))))
 544     {
 545       basic_block bb = gimple_bb (stmt);
 546       gimple_cond_set_code (stmt, NE_EXPR);
 547       gimple_cond_set_rhs (stmt, build_zero_cst (TREE_TYPE (rhs1)));
 548       EDGE_SUCC (bb, 0)->flags ^= (EDGE_TRUE_VALUE|EDGE_FALSE_VALUE);
 549       EDGE_SUCC (bb, 1)->flags ^= (EDGE_TRUE_VALUE|EDGE_FALSE_VALUE);
 550       return 1;
 551     }
 552
 553   return 0;
 554 }
 555
 556
 557 /* Propagate from the ssa name definition statements of COND_EXPR
 558    in the rhs of statement STMT into the conditional if that simplifies it.
 559    Returns true zero if the stmt was changed.  */
 560
 561 static bool
 562 forward_propagate_into_cond (gimple_stmt_iterator *gsi_p)
 563 {
 564   gimple stmt = gsi_stmt (*gsi_p);
 565   tree tmp = NULL_TREE;
 566   tree cond = gimple_assign_rhs1 (stmt);
 567   bool swap = false;
 568
 569   /* We can do tree combining on SSA_NAME and comparison expressions.  */
 570   if (COMPARISON_CLASS_P (cond))
 571     tmp = forward_propagate_into_comparison_1 (stmt, TREE_CODE (cond),
 572                                                boolean_type_node,
 573                                                TREE_OPERAND (cond, 0),
 574                                                TREE_OPERAND (cond, 1));
 575   else if (TREE_CODE (cond) == SSA_NAME)
 576     {
 577       enum tree_code code;
 578       tree name = cond;
 579       gimple def_stmt = get_prop_source_stmt (name, true, NULL);
 580       if (!def_stmt || !can_propagate_from (def_stmt))
 581         return 0;
 582
 583       code = gimple_assign_rhs_code (def_stmt);
 584       if (TREE_CODE_CLASS (code) == tcc_comparison)
 585         tmp = fold_build2_loc (gimple_location (def_stmt),
 586                                code,
 587                                boolean_type_node,
 588                                gimple_assign_rhs1 (def_stmt),
 589                                gimple_assign_rhs2 (def_stmt));
 590       else if ((code == BIT_NOT_EXPR
 591                 && TYPE_PRECISION (TREE_TYPE (cond)) == 1)
 592                || (code == BIT_XOR_EXPR
 593                    && integer_onep (gimple_assign_rhs2 (def_stmt))))
 594         {
 595           tmp = gimple_assign_rhs1 (def_stmt);
 596           swap = true;
 597         }
 598     }
 599
 600   if (tmp)
 601     {
 602       if (dump_file && tmp)
 603         {
 604           fprintf (dump_file, "  Replaced '");
 605           print_generic_expr (dump_file, cond, 0);
 606           fprintf (dump_file, "' with '");
 607           print_generic_expr (dump_file, tmp, 0);
 608           fprintf (dump_file, "'\n");
 609         }
 610
 611       if (integer_onep (tmp))
 612         gimple_assign_set_rhs_from_tree (gsi_p, gimple_assign_rhs2 (stmt));
 613       else if (integer_zerop (tmp))
 614         gimple_assign_set_rhs_from_tree (gsi_p, gimple_assign_rhs3 (stmt));
 615       else
 616         {
 617           gimple_assign_set_rhs1 (stmt, unshare_expr (tmp));
 618           if (swap)
 619             {
 620               tree t = gimple_assign_rhs2 (stmt);
 621               gimple_assign_set_rhs2 (stmt, gimple_assign_rhs3 (stmt));
 622               gimple_assign_set_rhs3 (stmt, t);
 623             }
 624         }
 625       stmt = gsi_stmt (*gsi_p);
 626       update_stmt (stmt);
 627
 628       return true;
 629     }
 630
 631   return 0;
 632 }
 633
 634 /* We've just substituted an ADDR_EXPR into stmt.  Update all the
 635    relevant data structures to match.  */
 636
 637 static void
 638 tidy_after_forward_propagate_addr (gimple stmt)
 639 {
 640   /* We may have turned a trapping insn into a non-trapping insn.  */
 641   if (maybe_clean_or_replace_eh_stmt (stmt, stmt)
 642       && gimple_purge_dead_eh_edges (gimple_bb (stmt)))
 643     cfg_changed = true;
 644
 645   if (TREE_CODE (gimple_assign_rhs1 (stmt)) == ADDR_EXPR)
 646      recompute_tree_invariant_for_addr_expr (gimple_assign_rhs1 (stmt));
 647 }
 648
 649 /* DEF_RHS contains the address of the 0th element in an array.
 650    USE_STMT uses type of DEF_RHS to compute the address of an
 651    arbitrary element within the array.  The (variable) byte offset
 652    of the element is contained in OFFSET.
 653
 654    We walk back through the use-def chains of OFFSET to verify that
 655    it is indeed computing the offset of an element within the array
 656    and extract the index corresponding to the given byte offset.
 657
 658    We then try to fold the entire address expression into a form
 659    &array[index].
 660
 661    If we are successful, we replace the right hand side of USE_STMT
 662    with the new address computation.  */
 663
 664 static bool
 665 forward_propagate_addr_into_variable_array_index (tree offset,
 666                                                   tree def_rhs,
 667                                                   gimple_stmt_iterator *use_stmt_gsi)
 668 {
 669   tree index, tunit;
 670   gimple offset_def, use_stmt = gsi_stmt (*use_stmt_gsi);
 671   tree new_rhs, tmp;
 672
 673   if (TREE_CODE (TREE_OPERAND (def_rhs, 0)) == ARRAY_REF)
 674     tunit = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (def_rhs)));
 675   else if (TREE_CODE (TREE_TYPE (TREE_OPERAND (def_rhs, 0))) == ARRAY_TYPE)
 676     tunit = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (TREE_TYPE (def_rhs))));
 677   else
 678     return false;
 679   if (!host_integerp (tunit, 1))
 680     return false;
 681
 682   /* Get the offset's defining statement.  */
 683   offset_def = SSA_NAME_DEF_STMT (offset);
 684
 685   /* Try to find an expression for a proper index.  This is either a
 686      multiplication expression by the element size or just the ssa name we came
 687      along in case the element size is one. In that case, however, we do not
 688      allow multiplications because they can be computing index to a higher
 689      level dimension (PR 37861). */
 690   if (integer_onep (tunit))
 691     {
 692       if (is_gimple_assign (offset_def)
 693           && gimple_assign_rhs_code (offset_def) == MULT_EXPR)
 694         return false;
 695
 696       index = offset;
 697     }
 698   else
 699     {
 700       /* The statement which defines OFFSET before type conversion
 701          must be a simple GIMPLE_ASSIGN.  */
 702       if (!is_gimple_assign (offset_def))
 703         return false;
 704
 705       /* The RHS of the statement which defines OFFSET must be a
 706          multiplication of an object by the size of the array elements.
 707          This implicitly verifies that the size of the array elements
 708          is constant.  */
 709      if (gimple_assign_rhs_code (offset_def) == MULT_EXPR
 710          && TREE_CODE (gimple_assign_rhs2 (offset_def)) == INTEGER_CST
 711          && tree_int_cst_equal (gimple_assign_rhs2 (offset_def), tunit))
 712        {
 713          /* The first operand to the MULT_EXPR is the desired index.  */
 714          index = gimple_assign_rhs1 (offset_def);
 715        }
 716      /* If we have idx * tunit + CST * tunit re-associate that.  */
 717      else if ((gimple_assign_rhs_code (offset_def) == PLUS_EXPR
 718                || gimple_assign_rhs_code (offset_def) == MINUS_EXPR)
 719               && TREE_CODE (gimple_assign_rhs1 (offset_def)) == SSA_NAME
 720               && TREE_CODE (gimple_assign_rhs2 (offset_def)) == INTEGER_CST
 721               && (tmp = div_if_zero_remainder (EXACT_DIV_EXPR,
 722                                                gimple_assign_rhs2 (offset_def),
 723                                                tunit)) != NULL_TREE)
 724        {
 725          gimple offset_def2 = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (offset_def));
 726          if (is_gimple_assign (offset_def2)
 727              && gimple_assign_rhs_code (offset_def2) == MULT_EXPR
 728              && TREE_CODE (gimple_assign_rhs2 (offset_def2)) == INTEGER_CST
 729              && tree_int_cst_equal (gimple_assign_rhs2 (offset_def2), tunit))
 730            {
 731              index = fold_build2 (gimple_assign_rhs_code (offset_def),
 732                                   TREE_TYPE (offset),
 733                                   gimple_assign_rhs1 (offset_def2), tmp);
 734            }
 735          else
 736            return false;
 737        }
 738      else
 739         return false;
 740     }
 741
 742   /* Replace the pointer addition with array indexing.  */
 743   index = force_gimple_operand_gsi (use_stmt_gsi, index, true, NULL_TREE,
 744                                     true, GSI_SAME_STMT);
 745   if (TREE_CODE (TREE_OPERAND (def_rhs, 0)) == ARRAY_REF)
 746     {
 747       new_rhs = unshare_expr (def_rhs);
 748       TREE_OPERAND (TREE_OPERAND (new_rhs, 0), 1) = index;
 749     }
 750   else
 751     {
 752       new_rhs = build4 (ARRAY_REF, TREE_TYPE (TREE_TYPE (TREE_TYPE (def_rhs))),
 753                         unshare_expr (TREE_OPERAND (def_rhs, 0)),
 754                         index, integer_zero_node, NULL_TREE);
 755       new_rhs = build_fold_addr_expr (new_rhs);
 756       if (!useless_type_conversion_p (TREE_TYPE (gimple_assign_lhs (use_stmt)),
 757                                       TREE_TYPE (new_rhs)))
 758         {
 759           new_rhs = force_gimple_operand_gsi (use_stmt_gsi, new_rhs, true,
 760                                               NULL_TREE, true, GSI_SAME_STMT);
 761           new_rhs = fold_convert (TREE_TYPE (gimple_assign_lhs (use_stmt)),
 762                                   new_rhs);
 763         }
 764     }
 765   gimple_assign_set_rhs_from_tree (use_stmt_gsi, new_rhs);
 766   fold_stmt (use_stmt_gsi);
 767   tidy_after_forward_propagate_addr (gsi_stmt (*use_stmt_gsi));
 768   return true;
 769 }
 770
 771 /* NAME is a SSA_NAME representing DEF_RHS which is of the form
 772    ADDR_EXPR <whatever>.
 773
 774    Try to forward propagate the ADDR_EXPR into the use USE_STMT.
 775    Often this will allow for removal of an ADDR_EXPR and INDIRECT_REF
 776    node or for recovery of array indexing from pointer arithmetic.
 777
 778    Return true if the propagation was successful (the propagation can
 779    be not totally successful, yet things may have been changed).  */
 780
 781 static bool
 782 forward_propagate_addr_expr_1 (tree name, tree def_rhs,
 783                                gimple_stmt_iterator *use_stmt_gsi,
 784                                bool single_use_p)
 785 {
 786   tree lhs, rhs, rhs2, array_ref;
 787   gimple use_stmt = gsi_stmt (*use_stmt_gsi);
 788   enum tree_code rhs_code;
 789   bool res = true;
 790
 791   gcc_assert (TREE_CODE (def_rhs) == ADDR_EXPR);
 792
 793   lhs = gimple_assign_lhs (use_stmt);
 794   rhs_code = gimple_assign_rhs_code (use_stmt);
 795   rhs = gimple_assign_rhs1 (use_stmt);
 796
 797   /* Trivial cases.  The use statement could be a trivial copy or a
 798      useless conversion.  Recurse to the uses of the lhs as copyprop does
 799      not copy through different variant pointers and FRE does not catch
 800      all useless conversions.  Treat the case of a single-use name and
 801      a conversion to def_rhs type separate, though.  */
 802   if (TREE_CODE (lhs) == SSA_NAME
 803       && ((rhs_code == SSA_NAME && rhs == name)
 804           || CONVERT_EXPR_CODE_P (rhs_code)))
 805     {
 806       /* Only recurse if we don't deal with a single use or we cannot
 807          do the propagation to the current statement.  In particular
 808          we can end up with a conversion needed for a non-invariant
 809          address which we cannot do in a single statement.  */
 810       if (!single_use_p
 811           || (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (def_rhs))
 812               && (!is_gimple_min_invariant (def_rhs)
 813                   || (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
 814                       && POINTER_TYPE_P (TREE_TYPE (def_rhs))
 815                       && (TYPE_PRECISION (TREE_TYPE (lhs))
 816                           > TYPE_PRECISION (TREE_TYPE (def_rhs)))))))
 817         return forward_propagate_addr_expr (lhs, def_rhs);
 818
 819       gimple_assign_set_rhs1 (use_stmt, unshare_expr (def_rhs));
 820       if (useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (def_rhs)))
 821         gimple_assign_set_rhs_code (use_stmt, TREE_CODE (def_rhs));
 822       else
 823         gimple_assign_set_rhs_code (use_stmt, NOP_EXPR);
 824       return true;
 825     }
 826
 827   /* Propagate through constant pointer adjustments.  */
 828   if (TREE_CODE (lhs) == SSA_NAME
 829       && rhs_code == POINTER_PLUS_EXPR
 830       && rhs == name
 831       && TREE_CODE (gimple_assign_rhs2 (use_stmt)) == INTEGER_CST)
 832     {
 833       tree new_def_rhs;
 834       /* As we come here with non-invariant addresses in def_rhs we need
 835          to make sure we can build a valid constant offsetted address
 836          for further propagation.  Simply rely on fold building that
 837          and check after the fact.  */
 838       new_def_rhs = fold_build2 (MEM_REF, TREE_TYPE (TREE_TYPE (rhs)),
 839                                  def_rhs,
 840                                  fold_convert (ptr_type_node,
 841                                                gimple_assign_rhs2 (use_stmt)));
 842       if (TREE_CODE (new_def_rhs) == MEM_REF
 843           && !is_gimple_mem_ref_addr (TREE_OPERAND (new_def_rhs, 0)))
 844         return false;
 845       new_def_rhs = build_fold_addr_expr_with_type (new_def_rhs,
 846                                                     TREE_TYPE (rhs));
 847
 848       /* Recurse.  If we could propagate into all uses of lhs do not
 849          bother to replace into the current use but just pretend we did.  */
 850       if (TREE_CODE (new_def_rhs) == ADDR_EXPR
 851           && forward_propagate_addr_expr (lhs, new_def_rhs))
 852         return true;
 853
 854       if (useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (new_def_rhs)))
 855         gimple_assign_set_rhs_with_ops (use_stmt_gsi, TREE_CODE (new_def_rhs),
 856                                         new_def_rhs, NULL_TREE);
 857       else if (is_gimple_min_invariant (new_def_rhs))
 858         gimple_assign_set_rhs_with_ops (use_stmt_gsi, NOP_EXPR,
 859                                         new_def_rhs, NULL_TREE);
 860       else
 861         return false;
 862       gcc_assert (gsi_stmt (*use_stmt_gsi) == use_stmt);
 863       update_stmt (use_stmt);
 864       return true;
 865     }
 866
 867   /* Now strip away any outer COMPONENT_REF/ARRAY_REF nodes from the LHS.
 868      ADDR_EXPR will not appear on the LHS.  */
 869   lhs = gimple_assign_lhs (use_stmt);
 870   while (handled_component_p (lhs))
 871     lhs = TREE_OPERAND (lhs, 0);
 872
 873   /* Now see if the LHS node is a MEM_REF using NAME.  If so,
 874      propagate the ADDR_EXPR into the use of NAME and fold the result.  */
 875   if (TREE_CODE (lhs) == MEM_REF
 876       && TREE_OPERAND (lhs, 0) == name)
 877     {
 878       tree def_rhs_base;
 879       HOST_WIDE_INT def_rhs_offset;
 880       /* If the address is invariant we can always fold it.  */
 881       if ((def_rhs_base = get_addr_base_and_unit_offset (TREE_OPERAND (def_rhs, 0),
 882                                                          &def_rhs_offset)))
 883         {
 884           double_int off = mem_ref_offset (lhs);
 885           tree new_ptr;
 886           off = double_int_add (off,
 887                                 shwi_to_double_int (def_rhs_offset));
 888           if (TREE_CODE (def_rhs_base) == MEM_REF)
 889             {
 890               off = double_int_add (off, mem_ref_offset (def_rhs_base));
 891               new_ptr = TREE_OPERAND (def_rhs_base, 0);
 892             }
 893           else
 894             new_ptr = build_fold_addr_expr (def_rhs_base);
 895           TREE_OPERAND (lhs, 0) = new_ptr;
 896           TREE_OPERAND (lhs, 1)
 897             = double_int_to_tree (TREE_TYPE (TREE_OPERAND (lhs, 1)), off);
 898           tidy_after_forward_propagate_addr (use_stmt);
 899           /* Continue propagating into the RHS if this was not the only use.  */
 900           if (single_use_p)
 901             return true;
 902         }
 903       /* If the LHS is a plain dereference and the value type is the same as
 904          that of the pointed-to type of the address we can put the
 905          dereferenced address on the LHS preserving the original alias-type.  */
 906       else if (gimple_assign_lhs (use_stmt) == lhs
 907                && useless_type_conversion_p
 908                     (TREE_TYPE (TREE_OPERAND (def_rhs, 0)),
 909                      TREE_TYPE (gimple_assign_rhs1 (use_stmt))))
 910         {
 911           tree *def_rhs_basep = &TREE_OPERAND (def_rhs, 0);
 912           tree new_offset, new_base, saved;
 913           while (handled_component_p (*def_rhs_basep))
 914             def_rhs_basep = &TREE_OPERAND (*def_rhs_basep, 0);
 915           saved = *def_rhs_basep;
 916           if (TREE_CODE (*def_rhs_basep) == MEM_REF)
 917             {
 918               new_base = TREE_OPERAND (*def_rhs_basep, 0);
 919               new_offset
 920                 = int_const_binop (PLUS_EXPR, TREE_OPERAND (lhs, 1),
 921                                    TREE_OPERAND (*def_rhs_basep, 1));
 922             }
 923           else
 924             {
 925               new_base = build_fold_addr_expr (*def_rhs_basep);
 926               new_offset = TREE_OPERAND (lhs, 1);
 927             }
 928           *def_rhs_basep = build2 (MEM_REF, TREE_TYPE (*def_rhs_basep),
 929                                    new_base, new_offset);
 930           TREE_THIS_VOLATILE (*def_rhs_basep) = TREE_THIS_VOLATILE (lhs);
 931           TREE_THIS_NOTRAP (*def_rhs_basep) = TREE_THIS_NOTRAP (lhs);
 932           gimple_assign_set_lhs (use_stmt,
 933                                  unshare_expr (TREE_OPERAND (def_rhs, 0)));
 934           *def_rhs_basep = saved;
 935           tidy_after_forward_propagate_addr (use_stmt);
 936           /* Continue propagating into the RHS if this was not the
 937              only use.  */
 938           if (single_use_p)
 939             return true;
 940         }
 941       else
 942         /* We can have a struct assignment dereferencing our name twice.
 943            Note that we didn't propagate into the lhs to not falsely
 944            claim we did when propagating into the rhs.  */
 945         res = false;
 946     }
 947
 948   /* Strip away any outer COMPONENT_REF, ARRAY_REF or ADDR_EXPR
 949      nodes from the RHS.  */
 950   rhs = gimple_assign_rhs1 (use_stmt);
 951   if (TREE_CODE (rhs) == ADDR_EXPR)
 952     rhs = TREE_OPERAND (rhs, 0);
 953   while (handled_component_p (rhs))
 954     rhs = TREE_OPERAND (rhs, 0);
 955
 956   /* Now see if the RHS node is a MEM_REF using NAME.  If so,
 957      propagate the ADDR_EXPR into the use of NAME and fold the result.  */
 958   if (TREE_CODE (rhs) == MEM_REF
 959       && TREE_OPERAND (rhs, 0) == name)
 960     {
 961       tree def_rhs_base;
 962       HOST_WIDE_INT def_rhs_offset;
 963       if ((def_rhs_base = get_addr_base_and_unit_offset (TREE_OPERAND (def_rhs, 0),
 964                                                          &def_rhs_offset)))
 965         {
 966           double_int off = mem_ref_offset (rhs);
 967           tree new_ptr;
 968           off = double_int_add (off,
 969                                 shwi_to_double_int (def_rhs_offset));
 970           if (TREE_CODE (def_rhs_base) == MEM_REF)
 971             {
 972               off = double_int_add (off, mem_ref_offset (def_rhs_base));
 973               new_ptr = TREE_OPERAND (def_rhs_base, 0);
 974             }
 975           else
 976             new_ptr = build_fold_addr_expr (def_rhs_base);
 977           TREE_OPERAND (rhs, 0) = new_ptr;
 978           TREE_OPERAND (rhs, 1)
 979             = double_int_to_tree (TREE_TYPE (TREE_OPERAND (rhs, 1)), off);
 980           fold_stmt_inplace (use_stmt_gsi);
 981           tidy_after_forward_propagate_addr (use_stmt);
 982           return res;
 983         }
 984       /* If the RHS is a plain dereference and the value type is the same as
 985          that of the pointed-to type of the address we can put the
 986          dereferenced address on the RHS preserving the original alias-type.  */
 987       else if (gimple_assign_rhs1 (use_stmt) == rhs
 988                && useless_type_conversion_p
 989                     (TREE_TYPE (gimple_assign_lhs (use_stmt)),
 990                      TREE_TYPE (TREE_OPERAND (def_rhs, 0))))
 991         {
 992           tree *def_rhs_basep = &TREE_OPERAND (def_rhs, 0);
 993           tree new_offset, new_base, saved;
 994           while (handled_component_p (*def_rhs_basep))
 995             def_rhs_basep = &TREE_OPERAND (*def_rhs_basep, 0);
 996           saved = *def_rhs_basep;
 997           if (TREE_CODE (*def_rhs_basep) == MEM_REF)
 998             {
 999               new_base = TREE_OPERAND (*def_rhs_basep, 0);
1000               new_offset
1001                 = int_const_binop (PLUS_EXPR, TREE_OPERAND (rhs, 1),
1002                                    TREE_OPERAND (*def_rhs_basep, 1));
1003             }
1004           else
1005             {
1006               new_base = build_fold_addr_expr (*def_rhs_basep);
1007               new_offset = TREE_OPERAND (rhs, 1);
1008             }
1009           *def_rhs_basep = build2 (MEM_REF, TREE_TYPE (*def_rhs_basep),
1010                                    new_base, new_offset);
1011           TREE_THIS_VOLATILE (*def_rhs_basep) = TREE_THIS_VOLATILE (rhs);
1012           TREE_THIS_NOTRAP (*def_rhs_basep) = TREE_THIS_NOTRAP (rhs);
1013           gimple_assign_set_rhs1 (use_stmt,
1014                                   unshare_expr (TREE_OPERAND (def_rhs, 0)));
1015           *def_rhs_basep = saved;
1016           fold_stmt_inplace (use_stmt_gsi);
1017           tidy_after_forward_propagate_addr (use_stmt);
1018           return res;
1019         }
1020     }
1021
1022   /* If the use of the ADDR_EXPR is not a POINTER_PLUS_EXPR, there
1023      is nothing to do. */
1024   if (gimple_assign_rhs_code (use_stmt) != POINTER_PLUS_EXPR
1025       || gimple_assign_rhs1 (use_stmt) != name)
1026     return false;
1027
1028   /* The remaining cases are all for turning pointer arithmetic into
1029      array indexing.  They only apply when we have the address of
1030      element zero in an array.  If that is not the case then there
1031      is nothing to do.  */
1032   array_ref = TREE_OPERAND (def_rhs, 0);
1033   if ((TREE_CODE (array_ref) != ARRAY_REF
1034        || TREE_CODE (TREE_TYPE (TREE_OPERAND (array_ref, 0))) != ARRAY_TYPE
1035        || TREE_CODE (TREE_OPERAND (array_ref, 1)) != INTEGER_CST)
1036       && TREE_CODE (TREE_TYPE (array_ref)) != ARRAY_TYPE)
1037     return false;
1038
1039   rhs2 = gimple_assign_rhs2 (use_stmt);
1040   /* Optimize &x[C1] p+ C2 to  &x p+ C3 with C3 = C1 * element_size + C2.  */
1041   if (TREE_CODE (rhs2) == INTEGER_CST)
1042     {
1043       tree new_rhs = build1_loc (gimple_location (use_stmt),
1044                                  ADDR_EXPR, TREE_TYPE (def_rhs),
1045                                  fold_build2 (MEM_REF,
1046                                               TREE_TYPE (TREE_TYPE (def_rhs)),
1047                                               unshare_expr (def_rhs),
1048                                               fold_convert (ptr_type_node,
1049                                                             rhs2)));
1050       gimple_assign_set_rhs_from_tree (use_stmt_gsi, new_rhs);
1051       use_stmt = gsi_stmt (*use_stmt_gsi);
1052       update_stmt (use_stmt);
1053       tidy_after_forward_propagate_addr (use_stmt);
1054       return true;
1055     }
1056
1057   /* Try to optimize &x[0] p+ OFFSET where OFFSET is defined by
1058      converting a multiplication of an index by the size of the
1059      array elements, then the result is converted into the proper
1060      type for the arithmetic.  */
1061   if (TREE_CODE (rhs2) == SSA_NAME
1062       && (TREE_CODE (array_ref) != ARRAY_REF
1063           || integer_zerop (TREE_OPERAND (array_ref, 1)))
1064       && useless_type_conversion_p (TREE_TYPE (name), TREE_TYPE (def_rhs))
1065       /* Avoid problems with IVopts creating PLUS_EXPRs with a
1066          different type than their operands.  */
1067       && useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (def_rhs)))
1068     return forward_propagate_addr_into_variable_array_index (rhs2, def_rhs,
1069                                                              use_stmt_gsi);
1070   return false;
1071 }
1072
1073 /* STMT is a statement of the form SSA_NAME = ADDR_EXPR <whatever>.
1074
1075    Try to forward propagate the ADDR_EXPR into all uses of the SSA_NAME.
1076    Often this will allow for removal of an ADDR_EXPR and INDIRECT_REF
1077    node or for recovery of array indexing from pointer arithmetic.
1078    Returns true, if all uses have been propagated into.  */
1079
1080 static bool
1081 forward_propagate_addr_expr (tree name, tree rhs)
1082 {
1083   int stmt_loop_depth = gimple_bb (SSA_NAME_DEF_STMT (name))->loop_depth;
1084   imm_use_iterator iter;
1085   gimple use_stmt;
1086   bool all = true;
1087   bool single_use_p = has_single_use (name);
1088
1089   FOR_EACH_IMM_USE_STMT (use_stmt, iter, name)
1090     {
1091       bool result;
1092       tree use_rhs;
1093
1094       /* If the use is not in a simple assignment statement, then
1095          there is nothing we can do.  */
1096       if (gimple_code (use_stmt) != GIMPLE_ASSIGN)
1097         {
1098           if (!is_gimple_debug (use_stmt))
1099             all = false;
1100           continue;
1101         }
1102
1103       /* If the use is in a deeper loop nest, then we do not want
1104          to propagate non-invariant ADDR_EXPRs into the loop as that
1105          is likely adding expression evaluations into the loop.  */
1106       if (gimple_bb (use_stmt)->loop_depth > stmt_loop_depth
1107           && !is_gimple_min_invariant (rhs))
1108         {
1109           all = false;
1110           continue;
1111         }
1112
1113       {
1114         gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
1115         result = forward_propagate_addr_expr_1 (name, rhs, &gsi,
1116                                                 single_use_p);
1117         /* If the use has moved to a different statement adjust
1118            the update machinery for the old statement too.  */
1119         if (use_stmt != gsi_stmt (gsi))
1120           {
1121             update_stmt (use_stmt);
1122             use_stmt = gsi_stmt (gsi);
1123           }
1124
1125         update_stmt (use_stmt);
1126       }
1127       all &= result;
1128
1129       /* Remove intermediate now unused copy and conversion chains.  */
1130       use_rhs = gimple_assign_rhs1 (use_stmt);
1131       if (result
1132           && TREE_CODE (gimple_assign_lhs (use_stmt)) == SSA_NAME
1133           && TREE_CODE (use_rhs) == SSA_NAME
1134           && has_zero_uses (gimple_assign_lhs (use_stmt)))
1135         {
1136           gimple_stmt_iterator gsi = gsi_for_stmt (use_stmt);
1137           release_defs (use_stmt);
1138           gsi_remove (&gsi, true);
1139         }
1140     }
1141
1142   return all && has_zero_uses (name);
1143 }
1144
1145
1146 /* Forward propagate the comparison defined in STMT like
1147    cond_1 = x CMP y to uses of the form
1148      a_1 = (T')cond_1
1149      a_1 = !cond_1
1150      a_1 = cond_1 != 0
1151    Returns true if stmt is now unused.  */
1152
1153 static bool
1154 forward_propagate_comparison (gimple stmt)
1155 {
1156   tree name = gimple_assign_lhs (stmt);
1157   gimple use_stmt;
1158   tree tmp = NULL_TREE;
1159   gimple_stmt_iterator gsi;
1160   enum tree_code code;
1161   tree lhs;
1162
1163   /* Don't propagate ssa names that occur in abnormal phis.  */
1164   if ((TREE_CODE (gimple_assign_rhs1 (stmt)) == SSA_NAME
1165        && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs1 (stmt)))
1166       || (TREE_CODE (gimple_assign_rhs2 (stmt)) == SSA_NAME
1167         && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (gimple_assign_rhs2 (stmt))))
1168     return false;
1169
1170   /* Do not un-cse comparisons.  But propagate through copies.  */
1171   use_stmt = get_prop_dest_stmt (name, &name);
1172   if (!use_stmt
1173       || !is_gimple_assign (use_stmt))
1174     return false;
1175
1176   code = gimple_assign_rhs_code (use_stmt);
1177   lhs = gimple_assign_lhs (use_stmt);
1178   if (!INTEGRAL_TYPE_P (TREE_TYPE (lhs)))
1179     return false;
1180
1181   /* We can propagate the condition into a statement that
1182      computes the logical negation of the comparison result.  */
1183   if ((code == BIT_NOT_EXPR
1184        && TYPE_PRECISION (TREE_TYPE (lhs)) == 1)
1185       || (code == BIT_XOR_EXPR
1186           && integer_onep (gimple_assign_rhs2 (use_stmt))))
1187     {
1188       tree type = TREE_TYPE (gimple_assign_rhs1 (stmt));
1189       bool nans = HONOR_NANS (TYPE_MODE (type));
1190       enum tree_code inv_code;
1191       inv_code = invert_tree_comparison (gimple_assign_rhs_code (stmt), nans);
1192       if (inv_code == ERROR_MARK)
1193         return false;
1194
1195       tmp = build2 (inv_code, TREE_TYPE (lhs), gimple_assign_rhs1 (stmt),
1196                     gimple_assign_rhs2 (stmt));
1197     }
1198   else
1199     return false;
1200
1201   gsi = gsi_for_stmt (use_stmt);
1202   gimple_assign_set_rhs_from_tree (&gsi, unshare_expr (tmp));
1203   use_stmt = gsi_stmt (gsi);
1204   update_stmt (use_stmt);
1205
1206   if (dump_file && (dump_flags & TDF_DETAILS))
1207     {
1208       fprintf (dump_file, "  Replaced '");
1209       print_gimple_expr (dump_file, stmt, 0, dump_flags);
1210       fprintf (dump_file, "' with '");
1211       print_gimple_expr (dump_file, use_stmt, 0, dump_flags);
1212       fprintf (dump_file, "'\n");
1213     }
1214
1215   /* Remove defining statements.  */
1216   return remove_prop_source_from_use (name);
1217 }
1218
1219
1220 /* If we have lhs = ~x (STMT), look and see if earlier we had x = ~y.
1221    If so, we can change STMT into lhs = y which can later be copy
1222    propagated.  Similarly for negation.
1223
1224    This could trivially be formulated as a forward propagation
1225    to immediate uses.  However, we already had an implementation
1226    from DOM which used backward propagation via the use-def links.
1227
1228    It turns out that backward propagation is actually faster as
1229    there's less work to do for each NOT/NEG expression we find.
1230    Backwards propagation needs to look at the statement in a single
1231    backlink.  Forward propagation needs to look at potentially more
1232    than one forward link.
1233
1234    Returns true when the statement was changed.  */
1235
1236 static bool
1237 simplify_not_neg_expr (gimple_stmt_iterator *gsi_p)
1238 {
1239   gimple stmt = gsi_stmt (*gsi_p);
1240   tree rhs = gimple_assign_rhs1 (stmt);
1241   gimple rhs_def_stmt = SSA_NAME_DEF_STMT (rhs);
1242
1243   /* See if the RHS_DEF_STMT has the same form as our statement.  */
1244   if (is_gimple_assign (rhs_def_stmt)
1245       && gimple_assign_rhs_code (rhs_def_stmt) == gimple_assign_rhs_code (stmt))
1246     {
1247       tree rhs_def_operand = gimple_assign_rhs1 (rhs_def_stmt);
1248
1249       /* Verify that RHS_DEF_OPERAND is a suitable SSA_NAME.  */
1250       if (TREE_CODE (rhs_def_operand) == SSA_NAME
1251           && ! SSA_NAME_OCCURS_IN_ABNORMAL_PHI (rhs_def_operand))
1252         {
1253           gimple_assign_set_rhs_from_tree (gsi_p, rhs_def_operand);
1254           stmt = gsi_stmt (*gsi_p);
1255           update_stmt (stmt);
1256           return true;
1257         }
1258     }
1259
1260   return false;
1261 }
1262
1263 /* STMT is a SWITCH_EXPR for which we attempt to find equivalent forms of
1264    the condition which we may be able to optimize better.  */
1265
1266 static bool
1267 simplify_gimple_switch (gimple stmt)
1268 {
1269   tree cond = gimple_switch_index (stmt);
1270   tree def, to, ti;
1271   gimple def_stmt;
1272
1273   /* The optimization that we really care about is removing unnecessary
1274      casts.  That will let us do much better in propagating the inferred
1275      constant at the switch target.  */
1276   if (TREE_CODE (cond) == SSA_NAME)
1277     {
1278       def_stmt = SSA_NAME_DEF_STMT (cond);
1279       if (is_gimple_assign (def_stmt))
1280         {
1281           if (gimple_assign_rhs_code (def_stmt) == NOP_EXPR)
1282             {
1283               int need_precision;
1284               bool fail;
1285
1286               def = gimple_assign_rhs1 (def_stmt);
1287
1288               /* ??? Why was Jeff testing this?  We are gimple...  */
1289               gcc_checking_assert (is_gimple_val (def));
1290
1291               to = TREE_TYPE (cond);
1292               ti = TREE_TYPE (def);
1293
1294               /* If we have an extension that preserves value, then we
1295                  can copy the source value into the switch.  */
1296
1297               need_precision = TYPE_PRECISION (ti);
1298               fail = false;
1299               if (! INTEGRAL_TYPE_P (ti))
1300                 fail = true;
1301               else if (TYPE_UNSIGNED (to) && !TYPE_UNSIGNED (ti))
1302                 fail = true;
1303               else if (!TYPE_UNSIGNED (to) && TYPE_UNSIGNED (ti))
1304                 need_precision += 1;
1305               if (TYPE_PRECISION (to) < need_precision)
1306                 fail = true;
1307
1308               if (!fail)
1309                 {
1310                   gimple_switch_set_index (stmt, def);
1311                   update_stmt (stmt);
1312                   return true;
1313                 }
1314             }
1315         }
1316     }
1317
1318   return false;
1319 }
1320
1321 /* For pointers p2 and p1 return p2 - p1 if the
1322    difference is known and constant, otherwise return NULL.  */
1323
1324 static tree
1325 constant_pointer_difference (tree p1, tree p2)
1326 {
1327   int i, j;
1328 #define CPD_ITERATIONS 5
1329   tree exps[2][CPD_ITERATIONS];
1330   tree offs[2][CPD_ITERATIONS];
1331   int cnt[2];
1332
1333   for (i = 0; i < 2; i++)
1334     {
1335       tree p = i ? p1 : p2;
1336       tree off = size_zero_node;
1337       gimple stmt;
1338       enum tree_code code;
1339
1340       /* For each of p1 and p2 we need to iterate at least
1341          twice, to handle ADDR_EXPR directly in p1/p2,
1342          SSA_NAME with ADDR_EXPR or POINTER_PLUS_EXPR etc.
1343          on definition's stmt RHS.  Iterate a few extra times.  */
1344       j = 0;
1345       do
1346         {
1347           if (!POINTER_TYPE_P (TREE_TYPE (p)))
1348             break;
1349           if (TREE_CODE (p) == ADDR_EXPR)
1350             {
1351               tree q = TREE_OPERAND (p, 0);
1352               HOST_WIDE_INT offset;
1353               tree base = get_addr_base_and_unit_offset (q, &offset);
1354               if (base)
1355                 {
1356                   q = base;
1357                   if (offset)
1358                     off = size_binop (PLUS_EXPR, off, size_int (offset));
1359                 }
1360               if (TREE_CODE (q) == MEM_REF
1361                   && TREE_CODE (TREE_OPERAND (q, 0)) == SSA_NAME)
1362                 {
1363                   p = TREE_OPERAND (q, 0);
1364                   off = size_binop (PLUS_EXPR, off,
1365                                     double_int_to_tree (sizetype,
1366                                                         mem_ref_offset (q)));
1367                 }
1368               else
1369                 {
1370                   exps[i][j] = q;
1371                   offs[i][j++] = off;
1372                   break;
1373                 }
1374             }
1375           if (TREE_CODE (p) != SSA_NAME)
1376             break;
1377           exps[i][j] = p;
1378           offs[i][j++] = off;
1379           if (j == CPD_ITERATIONS)
1380             break;
1381           stmt = SSA_NAME_DEF_STMT (p);
1382           if (!is_gimple_assign (stmt) || gimple_assign_lhs (stmt) != p)
1383             break;
1384           code = gimple_assign_rhs_code (stmt);
1385           if (code == POINTER_PLUS_EXPR)
1386             {
1387               if (TREE_CODE (gimple_assign_rhs2 (stmt)) != INTEGER_CST)
1388                 break;
1389               off = size_binop (PLUS_EXPR, off, gimple_assign_rhs2 (stmt));
1390               p = gimple_assign_rhs1 (stmt);
1391             }
1392           else if (code == ADDR_EXPR || code == NOP_EXPR)
1393             p = gimple_assign_rhs1 (stmt);
1394           else
1395             break;
1396         }
1397       while (1);
1398       cnt[i] = j;
1399     }
1400
1401   for (i = 0; i < cnt[0]; i++)
1402     for (j = 0; j < cnt[1]; j++)
1403       if (exps[0][i] == exps[1][j])
1404         return size_binop (MINUS_EXPR, offs[0][i], offs[1][j]);
1405
1406   return NULL_TREE;
1407 }
1408
1409 /* *GSI_P is a GIMPLE_CALL to a builtin function.
1410    Optimize
1411    memcpy (p, "abcd", 4);
1412    memset (p + 4, ' ', 3);
1413    into
1414    memcpy (p, "abcd   ", 7);
1415    call if the latter can be stored by pieces during expansion.  */
1416
1417 static bool
1418 simplify_builtin_call (gimple_stmt_iterator *gsi_p, tree callee2)
1419 {
1420   gimple stmt1, stmt2 = gsi_stmt (*gsi_p);
1421   tree vuse = gimple_vuse (stmt2);
1422   if (vuse == NULL)
1423     return false;
1424   stmt1 = SSA_NAME_DEF_STMT (vuse);
1425
1426   switch (DECL_FUNCTION_CODE (callee2))
1427     {
1428     case BUILT_IN_MEMSET:
1429       if (gimple_call_num_args (stmt2) != 3
1430           || gimple_call_lhs (stmt2)
1431           || CHAR_BIT != 8
1432           || BITS_PER_UNIT != 8)
1433         break;
1434       else
1435         {
1436           tree callee1;
1437           tree ptr1, src1, str1, off1, len1, lhs1;
1438           tree ptr2 = gimple_call_arg (stmt2, 0);
1439           tree val2 = gimple_call_arg (stmt2, 1);
1440           tree len2 = gimple_call_arg (stmt2, 2);
1441           tree diff, vdef, new_str_cst;
1442           gimple use_stmt;
1443           unsigned int ptr1_align;
1444           unsigned HOST_WIDE_INT src_len;
1445           char *src_buf;
1446           use_operand_p use_p;
1447
1448           if (!host_integerp (val2, 0)
1449               || !host_integerp (len2, 1))
1450             break;
1451           if (is_gimple_call (stmt1))
1452             {
1453               /* If first stmt is a call, it needs to be memcpy
1454                  or mempcpy, with string literal as second argument and
1455                  constant length.  */
1456               callee1 = gimple_call_fndecl (stmt1);
1457               if (callee1 == NULL_TREE
1458                   || DECL_BUILT_IN_CLASS (callee1) != BUILT_IN_NORMAL
1459                   || gimple_call_num_args (stmt1) != 3)
1460                 break;
1461               if (DECL_FUNCTION_CODE (callee1) != BUILT_IN_MEMCPY
1462                   && DECL_FUNCTION_CODE (callee1) != BUILT_IN_MEMPCPY)
1463                 break;
1464               ptr1 = gimple_call_arg (stmt1, 0);
1465               src1 = gimple_call_arg (stmt1, 1);
1466               len1 = gimple_call_arg (stmt1, 2);
1467               lhs1 = gimple_call_lhs (stmt1);
1468               if (!host_integerp (len1, 1))
1469                 break;
1470               str1 = string_constant (src1, &off1);
1471               if (str1 == NULL_TREE)
1472                 break;
1473               if (!host_integerp (off1, 1)
1474                   || compare_tree_int (off1, TREE_STRING_LENGTH (str1) - 1) > 0
1475                   || compare_tree_int (len1, TREE_STRING_LENGTH (str1)
1476                                              - tree_low_cst (off1, 1)) > 0
1477                   || TREE_CODE (TREE_TYPE (str1)) != ARRAY_TYPE
1478                   || TYPE_MODE (TREE_TYPE (TREE_TYPE (str1)))
1479                      != TYPE_MODE (char_type_node))
1480                 break;
1481             }
1482           else if (gimple_assign_single_p (stmt1))
1483             {
1484               /* Otherwise look for length 1 memcpy optimized into
1485                  assignment.  */
1486               ptr1 = gimple_assign_lhs (stmt1);
1487               src1 = gimple_assign_rhs1 (stmt1);
1488               if (TREE_CODE (ptr1) != MEM_REF
1489                   || TYPE_MODE (TREE_TYPE (ptr1)) != TYPE_MODE (char_type_node)
1490                   || !host_integerp (src1, 0))
1491                 break;
1492               ptr1 = build_fold_addr_expr (ptr1);
1493               callee1 = NULL_TREE;
1494               len1 = size_one_node;
1495               lhs1 = NULL_TREE;
1496               off1 = size_zero_node;
1497               str1 = NULL_TREE;
1498             }
1499           else
1500             break;
1501
1502           diff = constant_pointer_difference (ptr1, ptr2);
1503           if (diff == NULL && lhs1 != NULL)
1504             {
1505               diff = constant_pointer_difference (lhs1, ptr2);
1506               if (DECL_FUNCTION_CODE (callee1) == BUILT_IN_MEMPCPY
1507                   && diff != NULL)
1508                 diff = size_binop (PLUS_EXPR, diff,
1509                                    fold_convert (sizetype, len1));
1510             }
1511           /* If the difference between the second and first destination pointer
1512              is not constant, or is bigger than memcpy length, bail out.  */
1513           if (diff == NULL
1514               || !host_integerp (diff, 1)
1515               || tree_int_cst_lt (len1, diff))
1516             break;
1517
1518           /* Use maximum of difference plus memset length and memcpy length
1519              as the new memcpy length, if it is too big, bail out.  */
1520           src_len = tree_low_cst (diff, 1);
1521           src_len += tree_low_cst (len2, 1);
1522           if (src_len < (unsigned HOST_WIDE_INT) tree_low_cst (len1, 1))
1523             src_len = tree_low_cst (len1, 1);
1524           if (src_len > 1024)
1525             break;
1526
1527           /* If mempcpy value is used elsewhere, bail out, as mempcpy
1528              with bigger length will return different result.  */
1529           if (lhs1 != NULL_TREE
1530               && DECL_FUNCTION_CODE (callee1) == BUILT_IN_MEMPCPY
1531               && (TREE_CODE (lhs1) != SSA_NAME
1532                   || !single_imm_use (lhs1, &use_p, &use_stmt)
1533                   || use_stmt != stmt2))
1534             break;
1535
1536           /* If anything reads memory in between memcpy and memset
1537              call, the modified memcpy call might change it.  */
1538           vdef = gimple_vdef (stmt1);
1539           if (vdef != NULL
1540               && (!single_imm_use (vdef, &use_p, &use_stmt)
1541                   || use_stmt != stmt2))
1542             break;
1543
1544           ptr1_align = get_pointer_alignment (ptr1);
1545           /* Construct the new source string literal.  */
1546           src_buf = XALLOCAVEC (char, src_len + 1);
1547           if (callee1)
1548             memcpy (src_buf,
1549                     TREE_STRING_POINTER (str1) + tree_low_cst (off1, 1),
1550                     tree_low_cst (len1, 1));
1551           else
1552             src_buf[0] = tree_low_cst (src1, 0);
1553           memset (src_buf + tree_low_cst (diff, 1),
1554                   tree_low_cst (val2, 1), tree_low_cst (len2, 1));
1555           src_buf[src_len] = '\0';
1556           /* Neither builtin_strncpy_read_str nor builtin_memcpy_read_str
1557              handle embedded '\0's.  */
1558           if (strlen (src_buf) != src_len)
1559             break;
1560           rtl_profile_for_bb (gimple_bb (stmt2));
1561           /* If the new memcpy wouldn't be emitted by storing the literal
1562              by pieces, this optimization might enlarge .rodata too much,
1563              as commonly used string literals couldn't be shared any
1564              longer.  */
1565           if (!can_store_by_pieces (src_len,
1566                                     builtin_strncpy_read_str,
1567                                     src_buf, ptr1_align, false))
1568             break;
1569
1570           new_str_cst = build_string_literal (src_len, src_buf);
1571           if (callee1)
1572             {
1573               /* If STMT1 is a mem{,p}cpy call, adjust it and remove
1574                  memset call.  */
1575               if (lhs1 && DECL_FUNCTION_CODE (callee1) == BUILT_IN_MEMPCPY)
1576                 gimple_call_set_lhs (stmt1, NULL_TREE);
1577               gimple_call_set_arg (stmt1, 1, new_str_cst);
1578               gimple_call_set_arg (stmt1, 2,
1579                                    build_int_cst (TREE_TYPE (len1), src_len));
1580               update_stmt (stmt1);
1581               unlink_stmt_vdef (stmt2);
1582               gsi_remove (gsi_p, true);
1583               release_defs (stmt2);
1584               if (lhs1 && DECL_FUNCTION_CODE (callee1) == BUILT_IN_MEMPCPY)
1585                 release_ssa_name (lhs1);
1586               return true;
1587             }
1588           else
1589             {
1590               /* Otherwise, if STMT1 is length 1 memcpy optimized into
1591                  assignment, remove STMT1 and change memset call into
1592                  memcpy call.  */
1593               gimple_stmt_iterator gsi = gsi_for_stmt (stmt1);
1594
1595               if (!is_gimple_val (ptr1))
1596                 ptr1 = force_gimple_operand_gsi (gsi_p, ptr1, true, NULL_TREE,
1597                                                  true, GSI_SAME_STMT);
1598               gimple_call_set_fndecl (stmt2,
1599                                       builtin_decl_explicit (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 };