gcc/gimple-fold.c

   1 /* Statement simplification on GIMPLE.
   2    Copyright (C) 2010 Free Software Foundation, Inc.
   3    Split out from tree-ssa-ccp.c.
   4
   5 This file is part of GCC.
   6
   7 GCC is free software; you can redistribute it and/or modify it
   8 under the terms of the GNU General Public License as published by the
   9 Free Software Foundation; either version 3, or (at your option) any
  10 later version.
  11
  12 GCC is distributed in the hope that it will be useful, but WITHOUT
  13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  14 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  15 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 "flags.h"
  27 #include "function.h"
  28 #include "tree-dump.h"
  29 #include "tree-flow.h"
  30 #include "tree-pass.h"
  31 #include "tree-ssa-propagate.h"
  32 #include "target.h"
  33
  34 /* Return true when DECL can be referenced from current unit.
  35    We can get declarations that are not possible to reference for
  36    various reasons:
  37
  38      1) When analyzing C++ virtual tables.
  39         C++ virtual tables do have known constructors even
  40         when they are keyed to other compilation unit.
  41         Those tables can contain pointers to methods and vars
  42         in other units.  Those methods have both STATIC and EXTERNAL
  43         set.
  44      2) In WHOPR mode devirtualization might lead to reference
  45         to method that was partitioned elsehwere.
  46         In this case we have static VAR_DECL or FUNCTION_DECL
  47         that has no corresponding callgraph/varpool node
  48         declaring the body.
  49      3) COMDAT functions referred by external vtables that
  50         we devirtualize only during final copmilation stage.
  51         At this time we already decided that we will not output
  52         the function body and thus we can't reference the symbol
  53         directly.  */
  54
  55 static bool
  56 can_refer_decl_in_current_unit_p (tree decl)
  57 {
  58   struct varpool_node *vnode;
  59   struct cgraph_node *node;
  60
  61   if (!TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
  62     return true;
  63   /* External flag is set, so we deal with C++ reference
  64      to static object from other file.  */
  65   if (DECL_EXTERNAL (decl) && TREE_STATIC (decl)
  66       && TREE_CODE (decl) == VAR_DECL)
  67     {
  68       /* Just be sure it is not big in frontend setting
  69          flags incorrectly.  Those variables should never
  70          be finalized.  */
  71       gcc_checking_assert (!(vnode = varpool_get_node (decl))
  72                            || !vnode->finalized);
  73       return false;
  74     }
  75   /* When function is public, we always can introduce new reference.
  76      Exception are the COMDAT functions where introducing a direct
  77      reference imply need to include function body in the curren tunit.  */
  78   if (TREE_PUBLIC (decl) && !DECL_COMDAT (decl))
  79     return true;
  80   /* We are not at ltrans stage; so don't worry about WHOPR.
  81      Also when still gimplifying all referred comdat functions will be
  82      produced.  */
  83   if (!flag_ltrans && (!DECL_COMDAT (decl) || !cgraph_function_flags_ready))
  84     return true;
  85   /* If we already output the function body, we are safe.  */
  86   if (TREE_ASM_WRITTEN (decl))
  87     return true;
  88   if (TREE_CODE (decl) == FUNCTION_DECL)
  89     {
  90       node = cgraph_get_node (decl);
  91       /* Check that we still have function body and that we didn't took
  92          the decision to eliminate offline copy of the function yet.
  93          The second is important when devirtualization happens during final
  94          compilation stage when making a new reference no longer makes callee
  95          to be compiled.  */
  96       if (!node || !node->analyzed || node->global.inlined_to)
  97         return false;
  98     }
  99   else if (TREE_CODE (decl) == VAR_DECL)
 100     {
 101       vnode = varpool_get_node (decl);
 102       if (!vnode || !vnode->finalized)
 103         return false;
 104     }
 105   return true;
 106 }
 107
 108 /* CVAL is value taken from DECL_INITIAL of variable.  Try to transorm it into
 109    acceptable form for is_gimple_min_invariant.   */
 110
 111 tree
 112 canonicalize_constructor_val (tree cval)
 113 {
 114   STRIP_NOPS (cval);
 115   if (TREE_CODE (cval) == POINTER_PLUS_EXPR)
 116     {
 117       tree t = maybe_fold_offset_to_address (EXPR_LOCATION (cval),
 118                                              TREE_OPERAND (cval, 0),
 119                                              TREE_OPERAND (cval, 1),
 120                                              TREE_TYPE (cval));
 121       if (t)
 122         cval = t;
 123     }
 124   if (TREE_CODE (cval) == ADDR_EXPR)
 125     {
 126       tree base = get_base_address (TREE_OPERAND (cval, 0));
 127
 128       if (base
 129           && (TREE_CODE (base) == VAR_DECL
 130               || TREE_CODE (base) == FUNCTION_DECL)
 131           && !can_refer_decl_in_current_unit_p (base))
 132         return NULL_TREE;
 133       if (base && TREE_CODE (base) == VAR_DECL)
 134         add_referenced_var (base);
 135       /* We never have the chance to fixup types in global initializers
 136          during gimplification.  Do so here.  */
 137       if (TREE_TYPE (TREE_TYPE (cval)) != TREE_TYPE (TREE_OPERAND (cval, 0)))
 138         cval = build_fold_addr_expr (TREE_OPERAND (cval, 0));
 139     }
 140   return cval;
 141 }
 142
 143 /* If SYM is a constant variable with known value, return the value.
 144    NULL_TREE is returned otherwise.  */
 145
 146 tree
 147 get_symbol_constant_value (tree sym)
 148 {
 149   if (const_value_known_p (sym))
 150     {
 151       tree val = DECL_INITIAL (sym);
 152       if (val)
 153         {
 154           val = canonicalize_constructor_val (val);
 155           if (val && is_gimple_min_invariant (val))
 156             return val;
 157           else
 158             return NULL_TREE;
 159         }
 160       /* Variables declared 'const' without an initializer
 161          have zero as the initializer if they may not be
 162          overridden at link or run time.  */
 163       if (!val
 164           && (INTEGRAL_TYPE_P (TREE_TYPE (sym))
 165                || SCALAR_FLOAT_TYPE_P (TREE_TYPE (sym))))
 166         return build_zero_cst (TREE_TYPE (sym));
 167     }
 168
 169   return NULL_TREE;
 170 }
 171
 172
 173 /* Return true if we may propagate the address expression ADDR into the
 174    dereference DEREF and cancel them.  */
 175
 176 bool
 177 may_propagate_address_into_dereference (tree addr, tree deref)
 178 {
 179   gcc_assert (TREE_CODE (deref) == MEM_REF
 180               && TREE_CODE (addr) == ADDR_EXPR);
 181
 182   /* Don't propagate if ADDR's operand has incomplete type.  */
 183   if (!COMPLETE_TYPE_P (TREE_TYPE (TREE_OPERAND (addr, 0))))
 184     return false;
 185
 186   /* If the address is invariant then we do not need to preserve restrict
 187      qualifications.  But we do need to preserve volatile qualifiers until
 188      we can annotate the folded dereference itself properly.  */
 189   if (is_gimple_min_invariant (addr)
 190       && (!TREE_THIS_VOLATILE (deref)
 191           || TYPE_VOLATILE (TREE_TYPE (addr))))
 192     return useless_type_conversion_p (TREE_TYPE (deref),
 193                                       TREE_TYPE (TREE_OPERAND (addr, 0)));
 194
 195   /* Else both the address substitution and the folding must result in
 196      a valid useless type conversion sequence.  */
 197   return (useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (deref, 0)),
 198                                      TREE_TYPE (addr))
 199           && useless_type_conversion_p (TREE_TYPE (deref),
 200                                         TREE_TYPE (TREE_OPERAND (addr, 0))));
 201 }
 202
 203
 204 /* A subroutine of fold_stmt.  Attempts to fold *(A+O) to A[X].
 205    BASE is an array type.  OFFSET is a byte displacement.
 206
 207    LOC is the location of the original expression.  */
 208
 209 static tree
 210 maybe_fold_offset_to_array_ref (location_t loc, tree base, tree offset)
 211 {
 212   tree min_idx, idx, idx_type, elt_offset = integer_zero_node;
 213   tree array_type, elt_type, elt_size;
 214   tree domain_type;
 215
 216   /* If BASE is an ARRAY_REF, we can pick up another offset (this time
 217      measured in units of the size of elements type) from that ARRAY_REF).
 218      We can't do anything if either is variable.
 219
 220      The case we handle here is *(&A[N]+O).  */
 221   if (TREE_CODE (base) == ARRAY_REF)
 222     {
 223       tree low_bound = array_ref_low_bound (base);
 224
 225       elt_offset = TREE_OPERAND (base, 1);
 226       if (TREE_CODE (low_bound) != INTEGER_CST
 227           || TREE_CODE (elt_offset) != INTEGER_CST)
 228         return NULL_TREE;
 229
 230       elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound, 0);
 231       base = TREE_OPERAND (base, 0);
 232     }
 233
 234   /* Ignore stupid user tricks of indexing non-array variables.  */
 235   array_type = TREE_TYPE (base);
 236   if (TREE_CODE (array_type) != ARRAY_TYPE)
 237     return NULL_TREE;
 238   elt_type = TREE_TYPE (array_type);
 239
 240   /* Use signed size type for intermediate computation on the index.  */
 241   idx_type = ssizetype;
 242
 243   /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the
 244      element type (so we can use the alignment if it's not constant).
 245      Otherwise, compute the offset as an index by using a division.  If the
 246      division isn't exact, then don't do anything.  */
 247   elt_size = TYPE_SIZE_UNIT (elt_type);
 248   if (!elt_size)
 249     return NULL;
 250   if (integer_zerop (offset))
 251     {
 252       if (TREE_CODE (elt_size) != INTEGER_CST)
 253         elt_size = size_int (TYPE_ALIGN (elt_type));
 254
 255       idx = build_int_cst (idx_type, 0);
 256     }
 257   else
 258     {
 259       unsigned HOST_WIDE_INT lquo, lrem;
 260       HOST_WIDE_INT hquo, hrem;
 261       double_int soffset;
 262
 263       /* The final array offset should be signed, so we need
 264          to sign-extend the (possibly pointer) offset here
 265          and use signed division.  */
 266       soffset = double_int_sext (tree_to_double_int (offset),
 267                                  TYPE_PRECISION (TREE_TYPE (offset)));
 268       if (TREE_CODE (elt_size) != INTEGER_CST
 269           || div_and_round_double (TRUNC_DIV_EXPR, 0,
 270                                    soffset.low, soffset.high,
 271                                    TREE_INT_CST_LOW (elt_size),
 272                                    TREE_INT_CST_HIGH (elt_size),
 273                                    &lquo, &hquo, &lrem, &hrem)
 274           || lrem || hrem)
 275         return NULL_TREE;
 276
 277       idx = build_int_cst_wide (idx_type, lquo, hquo);
 278     }
 279
 280   /* Assume the low bound is zero.  If there is a domain type, get the
 281      low bound, if any, convert the index into that type, and add the
 282      low bound.  */
 283   min_idx = build_int_cst (idx_type, 0);
 284   domain_type = TYPE_DOMAIN (array_type);
 285   if (domain_type)
 286     {
 287       idx_type = domain_type;
 288       if (TYPE_MIN_VALUE (idx_type))
 289         min_idx = TYPE_MIN_VALUE (idx_type);
 290       else
 291         min_idx = fold_convert (idx_type, min_idx);
 292
 293       if (TREE_CODE (min_idx) != INTEGER_CST)
 294         return NULL_TREE;
 295
 296       elt_offset = fold_convert (idx_type, elt_offset);
 297     }
 298
 299   if (!integer_zerop (min_idx))
 300     idx = int_const_binop (PLUS_EXPR, idx, min_idx, 0);
 301   if (!integer_zerop (elt_offset))
 302     idx = int_const_binop (PLUS_EXPR, idx, elt_offset, 0);
 303
 304   /* Make sure to possibly truncate late after offsetting.  */
 305   idx = fold_convert (idx_type, idx);
 306
 307   /* We don't want to construct access past array bounds. For example
 308        char *(c[4]);
 309        c[3][2];
 310      should not be simplified into (*c)[14] or tree-vrp will
 311      give false warnings.
 312      This is only an issue for multi-dimensional arrays.  */
 313   if (TREE_CODE (elt_type) == ARRAY_TYPE
 314       && domain_type)
 315     {
 316       if (TYPE_MAX_VALUE (domain_type)
 317           && TREE_CODE (TYPE_MAX_VALUE (domain_type)) == INTEGER_CST
 318           && tree_int_cst_lt (TYPE_MAX_VALUE (domain_type), idx))
 319         return NULL_TREE;
 320       else if (TYPE_MIN_VALUE (domain_type)
 321                && TREE_CODE (TYPE_MIN_VALUE (domain_type)) == INTEGER_CST
 322                && tree_int_cst_lt (idx, TYPE_MIN_VALUE (domain_type)))
 323         return NULL_TREE;
 324       else if (compare_tree_int (idx, 0) < 0)
 325         return NULL_TREE;
 326     }
 327
 328   {
 329     tree t = build4 (ARRAY_REF, elt_type, base, idx, NULL_TREE, NULL_TREE);
 330     SET_EXPR_LOCATION (t, loc);
 331     return t;
 332   }
 333 }
 334
 335
 336 /* Attempt to express (ORIG_TYPE)BASE+OFFSET as BASE[index].
 337    LOC is the location of original expression.
 338
 339    Before attempting the conversion strip off existing ADDR_EXPRs.  */
 340
 341 tree
 342 maybe_fold_offset_to_reference (location_t loc, tree base, tree offset,
 343                                 tree orig_type)
 344 {
 345   tree ret;
 346
 347   STRIP_NOPS (base);
 348   if (TREE_CODE (base) != ADDR_EXPR)
 349     return NULL_TREE;
 350
 351   base = TREE_OPERAND (base, 0);
 352   if (types_compatible_p (orig_type, TREE_TYPE (base))
 353       && integer_zerop (offset))
 354     return base;
 355
 356   ret = maybe_fold_offset_to_array_ref (loc, base, offset);
 357   if (ret && types_compatible_p (orig_type, TREE_TYPE (ret)))
 358     return ret;
 359   return NULL_TREE;
 360 }
 361
 362 /* Attempt to express (ORIG_TYPE)ADDR+OFFSET as (*ADDR)[index].
 363    LOC is the location of the original expression.  */
 364
 365 tree
 366 maybe_fold_offset_to_address (location_t loc, tree addr, tree offset,
 367                               tree orig_type)
 368 {
 369   tree base, ret;
 370
 371   STRIP_NOPS (addr);
 372   if (TREE_CODE (addr) != ADDR_EXPR)
 373     return NULL_TREE;
 374   base = TREE_OPERAND (addr, 0);
 375   ret = maybe_fold_offset_to_array_ref (loc, base, offset);
 376   if (ret)
 377     {
 378       ret = build_fold_addr_expr (ret);
 379       if (!useless_type_conversion_p (orig_type, TREE_TYPE (ret)))
 380         return NULL_TREE;
 381       SET_EXPR_LOCATION (ret, loc);
 382     }
 383
 384   return ret;
 385 }
 386
 387
 388 /* A quaint feature extant in our address arithmetic is that there
 389    can be hidden type changes here.  The type of the result need
 390    not be the same as the type of the input pointer.
 391
 392    What we're after here is an expression of the form
 393         (T *)(&array + const)
 394    where array is OP0, const is OP1, RES_TYPE is T and
 395    the cast doesn't actually exist, but is implicit in the
 396    type of the POINTER_PLUS_EXPR.  We'd like to turn this into
 397         &array[x]
 398    which may be able to propagate further.  */
 399
 400 tree
 401 maybe_fold_stmt_addition (location_t loc, tree res_type, tree op0, tree op1)
 402 {
 403   tree ptd_type;
 404   tree t;
 405
 406   /* The first operand should be an ADDR_EXPR.  */
 407   if (TREE_CODE (op0) != ADDR_EXPR)
 408     return NULL_TREE;
 409   op0 = TREE_OPERAND (op0, 0);
 410
 411   /* It had better be a constant.  */
 412   if (TREE_CODE (op1) != INTEGER_CST)
 413     {
 414       /* Or op0 should now be A[0] and the non-constant offset defined
 415          via a multiplication by the array element size.  */
 416       if (TREE_CODE (op0) == ARRAY_REF
 417           /* As we will end up creating a variable index array access
 418              in the outermost array dimension make sure there isn't
 419              a more inner array that the index could overflow to.  */
 420           && TREE_CODE (TREE_OPERAND (op0, 0)) != ARRAY_REF
 421           && integer_zerop (TREE_OPERAND (op0, 1))
 422           && TREE_CODE (op1) == SSA_NAME)
 423         {
 424           gimple offset_def = SSA_NAME_DEF_STMT (op1);
 425           tree elsz = TYPE_SIZE_UNIT (TREE_TYPE (op0));
 426           if (!host_integerp (elsz, 1)
 427               || !is_gimple_assign (offset_def))
 428             return NULL_TREE;
 429
 430           /* Do not build array references of something that we can't
 431              see the true number of array dimensions for.  */
 432           if (!DECL_P (TREE_OPERAND (op0, 0))
 433               && !handled_component_p (TREE_OPERAND (op0, 0)))
 434             return NULL_TREE;
 435
 436           if (gimple_assign_rhs_code (offset_def) == MULT_EXPR
 437               && TREE_CODE (gimple_assign_rhs2 (offset_def)) == INTEGER_CST
 438               && tree_int_cst_equal (gimple_assign_rhs2 (offset_def), elsz))
 439             return build_fold_addr_expr
 440                           (build4 (ARRAY_REF, TREE_TYPE (op0),
 441                                    TREE_OPERAND (op0, 0),
 442                                    gimple_assign_rhs1 (offset_def),
 443                                    TREE_OPERAND (op0, 2),
 444                                    TREE_OPERAND (op0, 3)));
 445           else if (integer_onep (elsz)
 446                    && gimple_assign_rhs_code (offset_def) != MULT_EXPR)
 447             return build_fold_addr_expr
 448                           (build4 (ARRAY_REF, TREE_TYPE (op0),
 449                                    TREE_OPERAND (op0, 0),
 450                                    op1,
 451                                    TREE_OPERAND (op0, 2),
 452                                    TREE_OPERAND (op0, 3)));
 453         }
 454       else if (TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE
 455                /* Dto.  */
 456                && TREE_CODE (TREE_TYPE (TREE_TYPE (op0))) != ARRAY_TYPE
 457                && TREE_CODE (op1) == SSA_NAME)
 458         {
 459           gimple offset_def = SSA_NAME_DEF_STMT (op1);
 460           tree elsz = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (op0)));
 461           if (!host_integerp (elsz, 1)
 462               || !is_gimple_assign (offset_def))
 463             return NULL_TREE;
 464
 465           /* Do not build array references of something that we can't
 466              see the true number of array dimensions for.  */
 467           if (!DECL_P (op0)
 468               && !handled_component_p (op0))
 469             return NULL_TREE;
 470
 471           if (gimple_assign_rhs_code (offset_def) == MULT_EXPR
 472               && TREE_CODE (gimple_assign_rhs2 (offset_def)) == INTEGER_CST
 473               && tree_int_cst_equal (gimple_assign_rhs2 (offset_def), elsz))
 474             return build_fold_addr_expr
 475                           (build4 (ARRAY_REF, TREE_TYPE (TREE_TYPE (op0)),
 476                                    op0, gimple_assign_rhs1 (offset_def),
 477                                    integer_zero_node, NULL_TREE));
 478           else if (integer_onep (elsz)
 479                    && gimple_assign_rhs_code (offset_def) != MULT_EXPR)
 480             return build_fold_addr_expr
 481                           (build4 (ARRAY_REF, TREE_TYPE (TREE_TYPE (op0)),
 482                                    op0, op1,
 483                                    integer_zero_node, NULL_TREE));
 484         }
 485
 486       return NULL_TREE;
 487     }
 488
 489   /* If the first operand is an ARRAY_REF, expand it so that we can fold
 490      the offset into it.  */
 491   while (TREE_CODE (op0) == ARRAY_REF)
 492     {
 493       tree array_obj = TREE_OPERAND (op0, 0);
 494       tree array_idx = TREE_OPERAND (op0, 1);
 495       tree elt_type = TREE_TYPE (op0);
 496       tree elt_size = TYPE_SIZE_UNIT (elt_type);
 497       tree min_idx;
 498
 499       if (TREE_CODE (array_idx) != INTEGER_CST)
 500         break;
 501       if (TREE_CODE (elt_size) != INTEGER_CST)
 502         break;
 503
 504       /* Un-bias the index by the min index of the array type.  */
 505       min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj));
 506       if (min_idx)
 507         {
 508           min_idx = TYPE_MIN_VALUE (min_idx);
 509           if (min_idx)
 510             {
 511               if (TREE_CODE (min_idx) != INTEGER_CST)
 512                 break;
 513
 514               array_idx = fold_convert (TREE_TYPE (min_idx), array_idx);
 515               if (!integer_zerop (min_idx))
 516                 array_idx = int_const_binop (MINUS_EXPR, array_idx,
 517                                              min_idx, 0);
 518             }
 519         }
 520
 521       /* Convert the index to a byte offset.  */
 522       array_idx = fold_convert (sizetype, array_idx);
 523       array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size, 0);
 524
 525       /* Update the operands for the next round, or for folding.  */
 526       op1 = int_const_binop (PLUS_EXPR,
 527                              array_idx, op1, 0);
 528       op0 = array_obj;
 529     }
 530
 531   ptd_type = TREE_TYPE (res_type);
 532   /* If we want a pointer to void, reconstruct the reference from the
 533      array element type.  A pointer to that can be trivially converted
 534      to void *.  This happens as we fold (void *)(ptr p+ off).  */
 535   if (VOID_TYPE_P (ptd_type)
 536       && TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE)
 537     ptd_type = TREE_TYPE (TREE_TYPE (op0));
 538
 539   /* At which point we can try some of the same things as for indirects.  */
 540   t = maybe_fold_offset_to_array_ref (loc, op0, op1);
 541   if (t)
 542     {
 543       t = build_fold_addr_expr (t);
 544       if (!useless_type_conversion_p (res_type, TREE_TYPE (t)))
 545         return NULL_TREE;
 546       SET_EXPR_LOCATION (t, loc);
 547     }
 548
 549   return t;
 550 }
 551
 552 /* Subroutine of fold_stmt.  We perform several simplifications of the
 553    memory reference tree EXPR and make sure to re-gimplify them properly
 554    after propagation of constant addresses.  IS_LHS is true if the
 555    reference is supposed to be an lvalue.  */
 556
 557 static tree
 558 maybe_fold_reference (tree expr, bool is_lhs)
 559 {
 560   tree *t = &expr;
 561   tree result;
 562
 563   if (!is_lhs
 564       && (result = fold_const_aggregate_ref (expr))
 565       && is_gimple_min_invariant (result))
 566     return result;
 567
 568   /* ???  We might want to open-code the relevant remaining cases
 569      to avoid using the generic fold.  */
 570   if (handled_component_p (*t)
 571       && CONSTANT_CLASS_P (TREE_OPERAND (*t, 0)))
 572     {
 573       tree tem = fold (*t);
 574       if (tem != *t)
 575         return tem;
 576     }
 577
 578   while (handled_component_p (*t))
 579     t = &TREE_OPERAND (*t, 0);
 580
 581   /* Fold back MEM_REFs to reference trees.  */
 582   if (TREE_CODE (*t) == MEM_REF
 583       && TREE_CODE (TREE_OPERAND (*t, 0)) == ADDR_EXPR
 584       && integer_zerop (TREE_OPERAND (*t, 1))
 585       && (TREE_THIS_VOLATILE (*t)
 586           == TREE_THIS_VOLATILE (TREE_OPERAND (TREE_OPERAND (*t, 0), 0)))
 587       && !TYPE_REF_CAN_ALIAS_ALL (TREE_TYPE (TREE_OPERAND (*t, 1)))
 588       && (TYPE_MAIN_VARIANT (TREE_TYPE (*t))
 589           == TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (TREE_OPERAND (*t, 1)))))
 590       /* We have to look out here to not drop a required conversion
 591          from the rhs to the lhs if is_lhs, but we don't have the
 592          rhs here to verify that.  Thus require strict type
 593          compatibility.  */
 594       && types_compatible_p (TREE_TYPE (*t),
 595                              TREE_TYPE (TREE_OPERAND
 596                                           (TREE_OPERAND (*t, 0), 0))))
 597     {
 598       tree tem;
 599       *t = TREE_OPERAND (TREE_OPERAND (*t, 0), 0);
 600       tem = maybe_fold_reference (expr, is_lhs);
 601       if (tem)
 602         return tem;
 603       return expr;
 604     }
 605   /* Canonicalize MEM_REFs invariant address operand.  */
 606   else if (TREE_CODE (*t) == MEM_REF
 607            && !is_gimple_mem_ref_addr (TREE_OPERAND (*t, 0)))
 608     {
 609       bool volatile_p = TREE_THIS_VOLATILE (*t);
 610       tree tem = fold_binary (MEM_REF, TREE_TYPE (*t),
 611                               TREE_OPERAND (*t, 0),
 612                               TREE_OPERAND (*t, 1));
 613       if (tem)
 614         {
 615           TREE_THIS_VOLATILE (tem) = volatile_p;
 616           *t = tem;
 617           tem = maybe_fold_reference (expr, is_lhs);
 618           if (tem)
 619             return tem;
 620           return expr;
 621         }
 622     }
 623   else if (TREE_CODE (*t) == TARGET_MEM_REF)
 624     {
 625       tree tem = maybe_fold_tmr (*t);
 626       if (tem)
 627         {
 628           *t = tem;
 629           tem = maybe_fold_reference (expr, is_lhs);
 630           if (tem)
 631             return tem;
 632           return expr;
 633         }
 634     }
 635   else if (!is_lhs
 636            && DECL_P (*t))
 637     {
 638       tree tem = get_symbol_constant_value (*t);
 639       if (tem
 640           && useless_type_conversion_p (TREE_TYPE (*t), TREE_TYPE (tem)))
 641         {
 642           *t = unshare_expr (tem);
 643           tem = maybe_fold_reference (expr, is_lhs);
 644           if (tem)
 645             return tem;
 646           return expr;
 647         }
 648     }
 649
 650   return NULL_TREE;
 651 }
 652
 653
 654 /* Attempt to fold an assignment statement pointed-to by SI.  Returns a
 655    replacement rhs for the statement or NULL_TREE if no simplification
 656    could be made.  It is assumed that the operands have been previously
 657    folded.  */
 658
 659 static tree
 660 fold_gimple_assign (gimple_stmt_iterator *si)
 661 {
 662   gimple stmt = gsi_stmt (*si);
 663   enum tree_code subcode = gimple_assign_rhs_code (stmt);
 664   location_t loc = gimple_location (stmt);
 665
 666   tree result = NULL_TREE;
 667
 668   switch (get_gimple_rhs_class (subcode))
 669     {
 670     case GIMPLE_SINGLE_RHS:
 671       {
 672         tree rhs = gimple_assign_rhs1 (stmt);
 673
 674         /* Try to fold a conditional expression.  */
 675         if (TREE_CODE (rhs) == COND_EXPR)
 676           {
 677             tree op0 = COND_EXPR_COND (rhs);
 678             tree tem;
 679             bool set = false;
 680             location_t cond_loc = EXPR_LOCATION (rhs);
 681
 682             if (COMPARISON_CLASS_P (op0))
 683               {
 684                 fold_defer_overflow_warnings ();
 685                 tem = fold_binary_loc (cond_loc,
 686                                    TREE_CODE (op0), TREE_TYPE (op0),
 687                                    TREE_OPERAND (op0, 0),
 688                                    TREE_OPERAND (op0, 1));
 689                 /* This is actually a conditional expression, not a GIMPLE
 690                    conditional statement, however, the valid_gimple_rhs_p
 691                    test still applies.  */
 692                 set = (tem && is_gimple_condexpr (tem)
 693                        && valid_gimple_rhs_p (tem));
 694                 fold_undefer_overflow_warnings (set, stmt, 0);
 695               }
 696             else if (is_gimple_min_invariant (op0))
 697               {
 698                 tem = op0;
 699                 set = true;
 700               }
 701             else
 702               return NULL_TREE;
 703
 704             if (set)
 705               result = fold_build3_loc (cond_loc, COND_EXPR, TREE_TYPE (rhs), tem,
 706                                     COND_EXPR_THEN (rhs), COND_EXPR_ELSE (rhs));
 707           }
 708
 709         else if (REFERENCE_CLASS_P (rhs))
 710           return maybe_fold_reference (rhs, false);
 711
 712         else if (TREE_CODE (rhs) == ADDR_EXPR)
 713           {
 714             tree ref = TREE_OPERAND (rhs, 0);
 715             tree tem = maybe_fold_reference (ref, true);
 716             if (tem
 717                 && TREE_CODE (tem) == MEM_REF
 718                 && integer_zerop (TREE_OPERAND (tem, 1)))
 719               result = fold_convert (TREE_TYPE (rhs), TREE_OPERAND (tem, 0));
 720             else if (tem)
 721               result = fold_convert (TREE_TYPE (rhs),
 722                                      build_fold_addr_expr_loc (loc, tem));
 723             else if (TREE_CODE (ref) == MEM_REF
 724                      && integer_zerop (TREE_OPERAND (ref, 1)))
 725               result = fold_convert (TREE_TYPE (rhs), TREE_OPERAND (ref, 0));
 726           }
 727
 728         else if (TREE_CODE (rhs) == CONSTRUCTOR
 729                  && TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE
 730                  && (CONSTRUCTOR_NELTS (rhs)
 731                      == TYPE_VECTOR_SUBPARTS (TREE_TYPE (rhs))))
 732           {
 733             /* Fold a constant vector CONSTRUCTOR to VECTOR_CST.  */
 734             unsigned i;
 735             tree val;
 736
 737             FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs), i, val)
 738               if (TREE_CODE (val) != INTEGER_CST
 739                   && TREE_CODE (val) != REAL_CST
 740                   && TREE_CODE (val) != FIXED_CST)
 741                 return NULL_TREE;
 742
 743             return build_vector_from_ctor (TREE_TYPE (rhs),
 744                                            CONSTRUCTOR_ELTS (rhs));
 745           }
 746
 747         else if (DECL_P (rhs))
 748           return unshare_expr (get_symbol_constant_value (rhs));
 749
 750         /* If we couldn't fold the RHS, hand over to the generic
 751            fold routines.  */
 752         if (result == NULL_TREE)
 753           result = fold (rhs);
 754
 755         /* Strip away useless type conversions.  Both the NON_LVALUE_EXPR
 756            that may have been added by fold, and "useless" type
 757            conversions that might now be apparent due to propagation.  */
 758         STRIP_USELESS_TYPE_CONVERSION (result);
 759
 760         if (result != rhs && valid_gimple_rhs_p (result))
 761           return result;
 762
 763         return NULL_TREE;
 764       }
 765       break;
 766
 767     case GIMPLE_UNARY_RHS:
 768       {
 769         tree rhs = gimple_assign_rhs1 (stmt);
 770
 771         result = fold_unary_loc (loc, subcode, gimple_expr_type (stmt), rhs);
 772         if (result)
 773           {
 774             /* If the operation was a conversion do _not_ mark a
 775                resulting constant with TREE_OVERFLOW if the original
 776                constant was not.  These conversions have implementation
 777                defined behavior and retaining the TREE_OVERFLOW flag
 778                here would confuse later passes such as VRP.  */
 779             if (CONVERT_EXPR_CODE_P (subcode)
 780                 && TREE_CODE (result) == INTEGER_CST
 781                 && TREE_CODE (rhs) == INTEGER_CST)
 782               TREE_OVERFLOW (result) = TREE_OVERFLOW (rhs);
 783
 784             STRIP_USELESS_TYPE_CONVERSION (result);
 785             if (valid_gimple_rhs_p (result))
 786               return result;
 787           }
 788         else if (CONVERT_EXPR_CODE_P (subcode)
 789                  && POINTER_TYPE_P (gimple_expr_type (stmt))
 790                  && POINTER_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt))))
 791           {
 792             tree type = gimple_expr_type (stmt);
 793             tree t = maybe_fold_offset_to_address (loc,
 794                                                    gimple_assign_rhs1 (stmt),
 795                                                    integer_zero_node, type);
 796             if (t)
 797               return t;
 798           }
 799       }
 800       break;
 801
 802     case GIMPLE_BINARY_RHS:
 803       /* Try to fold pointer addition.  */
 804       if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR)
 805         {
 806           tree type = TREE_TYPE (gimple_assign_rhs1 (stmt));
 807           if (TREE_CODE (TREE_TYPE (type)) == ARRAY_TYPE)
 808             {
 809               type = build_pointer_type (TREE_TYPE (TREE_TYPE (type)));
 810               if (!useless_type_conversion_p
 811                     (TREE_TYPE (gimple_assign_lhs (stmt)), type))
 812                 type = TREE_TYPE (gimple_assign_rhs1 (stmt));
 813             }
 814           result = maybe_fold_stmt_addition (gimple_location (stmt),
 815                                              type,
 816                                              gimple_assign_rhs1 (stmt),
 817                                              gimple_assign_rhs2 (stmt));
 818         }
 819
 820       if (!result)
 821         result = fold_binary_loc (loc, subcode,
 822                               TREE_TYPE (gimple_assign_lhs (stmt)),
 823                               gimple_assign_rhs1 (stmt),
 824                               gimple_assign_rhs2 (stmt));
 825
 826       if (result)
 827         {
 828           STRIP_USELESS_TYPE_CONVERSION (result);
 829           if (valid_gimple_rhs_p (result))
 830             return result;
 831
 832           /* Fold might have produced non-GIMPLE, so if we trust it blindly
 833              we lose canonicalization opportunities.  Do not go again
 834              through fold here though, or the same non-GIMPLE will be
 835              produced.  */
 836           if (commutative_tree_code (subcode)
 837               && tree_swap_operands_p (gimple_assign_rhs1 (stmt),
 838                                        gimple_assign_rhs2 (stmt), false))
 839             return build2 (subcode, TREE_TYPE (gimple_assign_lhs (stmt)),
 840                            gimple_assign_rhs2 (stmt),
 841                            gimple_assign_rhs1 (stmt));
 842         }
 843       break;
 844
 845     case GIMPLE_TERNARY_RHS:
 846       result = fold_ternary_loc (loc, subcode,
 847                                  TREE_TYPE (gimple_assign_lhs (stmt)),
 848                                  gimple_assign_rhs1 (stmt),
 849                                  gimple_assign_rhs2 (stmt),
 850                                  gimple_assign_rhs3 (stmt));
 851
 852       if (result)
 853         {
 854           STRIP_USELESS_TYPE_CONVERSION (result);
 855           if (valid_gimple_rhs_p (result))
 856             return result;
 857
 858           /* Fold might have produced non-GIMPLE, so if we trust it blindly
 859              we lose canonicalization opportunities.  Do not go again
 860              through fold here though, or the same non-GIMPLE will be
 861              produced.  */
 862           if (commutative_ternary_tree_code (subcode)
 863               && tree_swap_operands_p (gimple_assign_rhs1 (stmt),
 864                                        gimple_assign_rhs2 (stmt), false))
 865             return build3 (subcode, TREE_TYPE (gimple_assign_lhs (stmt)),
 866                            gimple_assign_rhs2 (stmt),
 867                            gimple_assign_rhs1 (stmt),
 868                            gimple_assign_rhs3 (stmt));
 869         }
 870       break;
 871
 872     case GIMPLE_INVALID_RHS:
 873       gcc_unreachable ();
 874     }
 875
 876   return NULL_TREE;
 877 }
 878
 879 /* Attempt to fold a conditional statement. Return true if any changes were
 880    made. We only attempt to fold the condition expression, and do not perform
 881    any transformation that would require alteration of the cfg.  It is
 882    assumed that the operands have been previously folded.  */
 883
 884 static bool
 885 fold_gimple_cond (gimple stmt)
 886 {
 887   tree result = fold_binary_loc (gimple_location (stmt),
 888                              gimple_cond_code (stmt),
 889                              boolean_type_node,
 890                              gimple_cond_lhs (stmt),
 891                              gimple_cond_rhs (stmt));
 892
 893   if (result)
 894     {
 895       STRIP_USELESS_TYPE_CONVERSION (result);
 896       if (is_gimple_condexpr (result) && valid_gimple_rhs_p (result))
 897         {
 898           gimple_cond_set_condition_from_tree (stmt, result);
 899           return true;
 900         }
 901     }
 902
 903   return false;
 904 }
 905
 906 /* Convert EXPR into a GIMPLE value suitable for substitution on the
 907    RHS of an assignment.  Insert the necessary statements before
 908    iterator *SI_P.  The statement at *SI_P, which must be a GIMPLE_CALL
 909    is replaced.  If the call is expected to produces a result, then it
 910    is replaced by an assignment of the new RHS to the result variable.
 911    If the result is to be ignored, then the call is replaced by a
 912    GIMPLE_NOP.  A proper VDEF chain is retained by making the first
 913    VUSE and the last VDEF of the whole sequence be the same as the replaced
 914    statement and using new SSA names for stores in between.  */
 915
 916 void
 917 gimplify_and_update_call_from_tree (gimple_stmt_iterator *si_p, tree expr)
 918 {
 919   tree lhs;
 920   tree tmp = NULL_TREE;  /* Silence warning.  */
 921   gimple stmt, new_stmt;
 922   gimple_stmt_iterator i;
 923   gimple_seq stmts = gimple_seq_alloc();
 924   struct gimplify_ctx gctx;
 925   gimple last = NULL;
 926   gimple laststore = NULL;
 927   tree reaching_vuse;
 928
 929   stmt = gsi_stmt (*si_p);
 930
 931   gcc_assert (is_gimple_call (stmt));
 932
 933   lhs = gimple_call_lhs (stmt);
 934   reaching_vuse = gimple_vuse (stmt);
 935
 936   push_gimplify_context (&gctx);
 937
 938   if (lhs == NULL_TREE)
 939     {
 940       gimplify_and_add (expr, &stmts);
 941       /* We can end up with folding a memcpy of an empty class assignment
 942          which gets optimized away by C++ gimplification.  */
 943       if (gimple_seq_empty_p (stmts))
 944         {
 945           pop_gimplify_context (NULL);
 946           if (gimple_in_ssa_p (cfun))
 947             {
 948               unlink_stmt_vdef (stmt);
 949               release_defs (stmt);
 950             }
 951           gsi_remove (si_p, true);
 952           return;
 953         }
 954     }
 955   else
 956     tmp = get_initialized_tmp_var (expr, &stmts, NULL);
 957
 958   pop_gimplify_context (NULL);
 959
 960   if (gimple_has_location (stmt))
 961     annotate_all_with_location (stmts, gimple_location (stmt));
 962
 963   /* The replacement can expose previously unreferenced variables.  */
 964   for (i = gsi_start (stmts); !gsi_end_p (i); gsi_next (&i))
 965     {
 966       if (last)
 967         {
 968           gsi_insert_before (si_p, last, GSI_NEW_STMT);
 969           gsi_next (si_p);
 970         }
 971       new_stmt = gsi_stmt (i);
 972       if (gimple_in_ssa_p (cfun))
 973         {
 974           find_new_referenced_vars (new_stmt);
 975           mark_symbols_for_renaming (new_stmt);
 976         }
 977       /* If the new statement has a VUSE, update it with exact SSA name we
 978          know will reach this one.  */
 979       if (gimple_vuse (new_stmt))
 980         {
 981           /* If we've also seen a previous store create a new VDEF for
 982              the latter one, and make that the new reaching VUSE.  */
 983           if (laststore)
 984             {
 985               reaching_vuse = make_ssa_name (gimple_vop (cfun), laststore);
 986               gimple_set_vdef (laststore, reaching_vuse);
 987               update_stmt (laststore);
 988               laststore = NULL;
 989             }
 990           gimple_set_vuse (new_stmt, reaching_vuse);
 991           gimple_set_modified (new_stmt, true);
 992         }
 993       if (gimple_assign_single_p (new_stmt)
 994           && !is_gimple_reg (gimple_assign_lhs (new_stmt)))
 995         {
 996           laststore = new_stmt;
 997         }
 998       last = new_stmt;
 999     }
1000
1001   if (lhs == NULL_TREE)
1002     {
1003       /* If we replace a call without LHS that has a VDEF and our new
1004          sequence ends with a store we must make that store have the same
1005          vdef in order not to break the sequencing.  This can happen
1006          for instance when folding memcpy calls into assignments.  */
1007       if (gimple_vdef (stmt) && laststore)
1008         {
1009           gimple_set_vdef (laststore, gimple_vdef (stmt));
1010           if (TREE_CODE (gimple_vdef (stmt)) == SSA_NAME)
1011             SSA_NAME_DEF_STMT (gimple_vdef (stmt)) = laststore;
1012           update_stmt (laststore);
1013         }
1014       else if (gimple_in_ssa_p (cfun))
1015         {
1016           unlink_stmt_vdef (stmt);
1017           release_defs (stmt);
1018         }
1019       new_stmt = last;
1020     }
1021   else
1022     {
1023       if (last)
1024         {
1025           gsi_insert_before (si_p, last, GSI_NEW_STMT);
1026           gsi_next (si_p);
1027         }
1028       if (laststore && is_gimple_reg (lhs))
1029         {
1030           gimple_set_vdef (laststore, gimple_vdef (stmt));
1031           update_stmt (laststore);
1032           if (TREE_CODE (gimple_vdef (stmt)) == SSA_NAME)
1033             SSA_NAME_DEF_STMT (gimple_vdef (stmt)) = laststore;
1034           laststore = NULL;
1035         }
1036       else if (laststore)
1037         {
1038           reaching_vuse = make_ssa_name (gimple_vop (cfun), laststore);
1039           gimple_set_vdef (laststore, reaching_vuse);
1040           update_stmt (laststore);
1041           laststore = NULL;
1042         }
1043       new_stmt = gimple_build_assign (lhs, tmp);
1044       if (!is_gimple_reg (tmp))
1045         gimple_set_vuse (new_stmt, reaching_vuse);
1046       if (!is_gimple_reg (lhs))
1047         {
1048           gimple_set_vdef (new_stmt, gimple_vdef (stmt));
1049           if (TREE_CODE (gimple_vdef (stmt)) == SSA_NAME)
1050             SSA_NAME_DEF_STMT (gimple_vdef (stmt)) = new_stmt;
1051         }
1052       else if (reaching_vuse == gimple_vuse (stmt))
1053         unlink_stmt_vdef (stmt);
1054     }
1055
1056   gimple_set_location (new_stmt, gimple_location (stmt));
1057   gsi_replace (si_p, new_stmt, false);
1058 }
1059
1060 /* Return the string length, maximum string length or maximum value of
1061    ARG in LENGTH.
1062    If ARG is an SSA name variable, follow its use-def chains.  If LENGTH
1063    is not NULL and, for TYPE == 0, its value is not equal to the length
1064    we determine or if we are unable to determine the length or value,
1065    return false.  VISITED is a bitmap of visited variables.
1066    TYPE is 0 if string length should be returned, 1 for maximum string
1067    length and 2 for maximum value ARG can have.  */
1068
1069 static bool
1070 get_maxval_strlen (tree arg, tree *length, bitmap visited, int type)
1071 {
1072   tree var, val;
1073   gimple def_stmt;
1074
1075   if (TREE_CODE (arg) != SSA_NAME)
1076     {
1077       if (TREE_CODE (arg) == COND_EXPR)
1078         return get_maxval_strlen (COND_EXPR_THEN (arg), length, visited, type)
1079                && get_maxval_strlen (COND_EXPR_ELSE (arg), length, visited, type);
1080       /* We can end up with &(*iftmp_1)[0] here as well, so handle it.  */
1081       else if (TREE_CODE (arg) == ADDR_EXPR
1082                && TREE_CODE (TREE_OPERAND (arg, 0)) == ARRAY_REF
1083                && integer_zerop (TREE_OPERAND (TREE_OPERAND (arg, 0), 1)))
1084         {
1085           tree aop0 = TREE_OPERAND (TREE_OPERAND (arg, 0), 0);
1086           if (TREE_CODE (aop0) == INDIRECT_REF
1087               && TREE_CODE (TREE_OPERAND (aop0, 0)) == SSA_NAME)
1088             return get_maxval_strlen (TREE_OPERAND (aop0, 0),
1089                                       length, visited, type);
1090         }
1091
1092       if (type == 2)
1093         {
1094           val = arg;
1095           if (TREE_CODE (val) != INTEGER_CST
1096               || tree_int_cst_sgn (val) < 0)
1097             return false;
1098         }
1099       else
1100         val = c_strlen (arg, 1);
1101       if (!val)
1102         return false;
1103
1104       if (*length)
1105         {
1106           if (type > 0)
1107             {
1108               if (TREE_CODE (*length) != INTEGER_CST
1109                   || TREE_CODE (val) != INTEGER_CST)
1110                 return false;
1111
1112               if (tree_int_cst_lt (*length, val))
1113                 *length = val;
1114               return true;
1115             }
1116           else if (simple_cst_equal (val, *length) != 1)
1117             return false;
1118         }
1119
1120       *length = val;
1121       return true;
1122     }
1123
1124   /* If we were already here, break the infinite cycle.  */
1125   if (!bitmap_set_bit (visited, SSA_NAME_VERSION (arg)))
1126     return true;
1127
1128   var = arg;
1129   def_stmt = SSA_NAME_DEF_STMT (var);
1130
1131   switch (gimple_code (def_stmt))
1132     {
1133       case GIMPLE_ASSIGN:
1134         /* The RHS of the statement defining VAR must either have a
1135            constant length or come from another SSA_NAME with a constant
1136            length.  */
1137         if (gimple_assign_single_p (def_stmt)
1138             || gimple_assign_unary_nop_p (def_stmt))
1139           {
1140             tree rhs = gimple_assign_rhs1 (def_stmt);
1141             return get_maxval_strlen (rhs, length, visited, type);
1142           }
1143         return false;
1144
1145       case GIMPLE_PHI:
1146         {
1147           /* All the arguments of the PHI node must have the same constant
1148              length.  */
1149           unsigned i;
1150
1151           for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
1152           {
1153             tree arg = gimple_phi_arg (def_stmt, i)->def;
1154
1155             /* If this PHI has itself as an argument, we cannot
1156                determine the string length of this argument.  However,
1157                if we can find a constant string length for the other
1158                PHI args then we can still be sure that this is a
1159                constant string length.  So be optimistic and just
1160                continue with the next argument.  */
1161             if (arg == gimple_phi_result (def_stmt))
1162               continue;
1163
1164             if (!get_maxval_strlen (arg, length, visited, type))
1165               return false;
1166           }
1167         }
1168         return true;
1169
1170       default:
1171         return false;
1172     }
1173 }
1174
1175
1176 /* Fold builtin call in statement STMT.  Returns a simplified tree.
1177    We may return a non-constant expression, including another call
1178    to a different function and with different arguments, e.g.,
1179    substituting memcpy for strcpy when the string length is known.
1180    Note that some builtins expand into inline code that may not
1181    be valid in GIMPLE.  Callers must take care.  */
1182
1183 tree
1184 gimple_fold_builtin (gimple stmt)
1185 {
1186   tree result, val[3];
1187   tree callee, a;
1188   int arg_idx, type;
1189   bitmap visited;
1190   bool ignore;
1191   int nargs;
1192   location_t loc = gimple_location (stmt);
1193
1194   gcc_assert (is_gimple_call (stmt));
1195
1196   ignore = (gimple_call_lhs (stmt) == NULL);
1197
1198   /* First try the generic builtin folder.  If that succeeds, return the
1199      result directly.  */
1200   result = fold_call_stmt (stmt, ignore);
1201   if (result)
1202     {
1203       if (ignore)
1204         STRIP_NOPS (result);
1205       return result;
1206     }
1207
1208   /* Ignore MD builtins.  */
1209   callee = gimple_call_fndecl (stmt);
1210   if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD)
1211     return NULL_TREE;
1212
1213   /* If the builtin could not be folded, and it has no argument list,
1214      we're done.  */
1215   nargs = gimple_call_num_args (stmt);
1216   if (nargs == 0)
1217     return NULL_TREE;
1218
1219   /* Limit the work only for builtins we know how to simplify.  */
1220   switch (DECL_FUNCTION_CODE (callee))
1221     {
1222     case BUILT_IN_STRLEN:
1223     case BUILT_IN_FPUTS:
1224     case BUILT_IN_FPUTS_UNLOCKED:
1225       arg_idx = 0;
1226       type = 0;
1227       break;
1228     case BUILT_IN_STRCPY:
1229     case BUILT_IN_STRNCPY:
1230       arg_idx = 1;
1231       type = 0;
1232       break;
1233     case BUILT_IN_MEMCPY_CHK:
1234     case BUILT_IN_MEMPCPY_CHK:
1235     case BUILT_IN_MEMMOVE_CHK:
1236     case BUILT_IN_MEMSET_CHK:
1237     case BUILT_IN_STRNCPY_CHK:
1238       arg_idx = 2;
1239       type = 2;
1240       break;
1241     case BUILT_IN_STRCPY_CHK:
1242     case BUILT_IN_STPCPY_CHK:
1243       arg_idx = 1;
1244       type = 1;
1245       break;
1246     case BUILT_IN_SNPRINTF_CHK:
1247     case BUILT_IN_VSNPRINTF_CHK:
1248       arg_idx = 1;
1249       type = 2;
1250       break;
1251     default:
1252       return NULL_TREE;
1253     }
1254
1255   if (arg_idx >= nargs)
1256     return NULL_TREE;
1257
1258   /* Try to use the dataflow information gathered by the CCP process.  */
1259   visited = BITMAP_ALLOC (NULL);
1260   bitmap_clear (visited);
1261
1262   memset (val, 0, sizeof (val));
1263   a = gimple_call_arg (stmt, arg_idx);
1264   if (!get_maxval_strlen (a, &val[arg_idx], visited, type))
1265     val[arg_idx] = NULL_TREE;
1266
1267   BITMAP_FREE (visited);
1268
1269   result = NULL_TREE;
1270   switch (DECL_FUNCTION_CODE (callee))
1271     {
1272     case BUILT_IN_STRLEN:
1273       if (val[0] && nargs == 1)
1274         {
1275           tree new_val =
1276               fold_convert (TREE_TYPE (gimple_call_lhs (stmt)), val[0]);
1277
1278           /* If the result is not a valid gimple value, or not a cast
1279              of a valid gimple value, then we cannot use the result.  */
1280           if (is_gimple_val (new_val)
1281               || (CONVERT_EXPR_P (new_val)
1282                   && is_gimple_val (TREE_OPERAND (new_val, 0))))
1283             return new_val;
1284         }
1285       break;
1286
1287     case BUILT_IN_STRCPY:
1288       if (val[1] && is_gimple_val (val[1]) && nargs == 2)
1289         result = fold_builtin_strcpy (loc, callee,
1290                                       gimple_call_arg (stmt, 0),
1291                                       gimple_call_arg (stmt, 1),
1292                                       val[1]);
1293       break;
1294
1295     case BUILT_IN_STRNCPY:
1296       if (val[1] && is_gimple_val (val[1]) && nargs == 3)
1297         result = fold_builtin_strncpy (loc, callee,
1298                                        gimple_call_arg (stmt, 0),
1299                                        gimple_call_arg (stmt, 1),
1300                                        gimple_call_arg (stmt, 2),
1301                                        val[1]);
1302       break;
1303
1304     case BUILT_IN_FPUTS:
1305       if (nargs == 2)
1306         result = fold_builtin_fputs (loc, gimple_call_arg (stmt, 0),
1307                                      gimple_call_arg (stmt, 1),
1308                                      ignore, false, val[0]);
1309       break;
1310
1311     case BUILT_IN_FPUTS_UNLOCKED:
1312       if (nargs == 2)
1313         result = fold_builtin_fputs (loc, gimple_call_arg (stmt, 0),
1314                                      gimple_call_arg (stmt, 1),
1315                                      ignore, true, val[0]);
1316       break;
1317
1318     case BUILT_IN_MEMCPY_CHK:
1319     case BUILT_IN_MEMPCPY_CHK:
1320     case BUILT_IN_MEMMOVE_CHK:
1321     case BUILT_IN_MEMSET_CHK:
1322       if (val[2] && is_gimple_val (val[2]) && nargs == 4)
1323         result = fold_builtin_memory_chk (loc, callee,
1324                                           gimple_call_arg (stmt, 0),
1325                                           gimple_call_arg (stmt, 1),
1326                                           gimple_call_arg (stmt, 2),
1327                                           gimple_call_arg (stmt, 3),
1328                                           val[2], ignore,
1329                                           DECL_FUNCTION_CODE (callee));
1330       break;
1331
1332     case BUILT_IN_STRCPY_CHK:
1333     case BUILT_IN_STPCPY_CHK:
1334       if (val[1] && is_gimple_val (val[1]) && nargs == 3)
1335         result = fold_builtin_stxcpy_chk (loc, callee,
1336                                           gimple_call_arg (stmt, 0),
1337                                           gimple_call_arg (stmt, 1),
1338                                           gimple_call_arg (stmt, 2),
1339                                           val[1], ignore,
1340                                           DECL_FUNCTION_CODE (callee));
1341       break;
1342
1343     case BUILT_IN_STRNCPY_CHK:
1344       if (val[2] && is_gimple_val (val[2]) && nargs == 4)
1345         result = fold_builtin_strncpy_chk (loc, gimple_call_arg (stmt, 0),
1346                                            gimple_call_arg (stmt, 1),
1347                                            gimple_call_arg (stmt, 2),
1348                                            gimple_call_arg (stmt, 3),
1349                                            val[2]);
1350       break;
1351
1352     case BUILT_IN_SNPRINTF_CHK:
1353     case BUILT_IN_VSNPRINTF_CHK:
1354       if (val[1] && is_gimple_val (val[1]))
1355         result = gimple_fold_builtin_snprintf_chk (stmt, val[1],
1356                                                    DECL_FUNCTION_CODE (callee));
1357       break;
1358
1359     default:
1360       gcc_unreachable ();
1361     }
1362
1363   if (result && ignore)
1364     result = fold_ignored_result (result);
1365   return result;
1366 }
1367
1368 /* Return a declaration of a function which an OBJ_TYPE_REF references. TOKEN
1369    is integer form of OBJ_TYPE_REF_TOKEN of the reference expression.
1370    KNOWN_BINFO carries the binfo describing the true type of
1371    OBJ_TYPE_REF_OBJECT(REF).  If a call to the function must be accompanied
1372    with a this adjustment, the constant which should be added to this pointer
1373    is stored to *DELTA.  If REFUSE_THUNKS is true, return NULL if the function
1374    is a thunk (other than a this adjustment which is dealt with by DELTA). */
1375
1376 tree
1377 gimple_get_virt_mehtod_for_binfo (HOST_WIDE_INT token, tree known_binfo,
1378                                   tree *delta, bool refuse_thunks)
1379 {
1380   HOST_WIDE_INT i;
1381   tree v, fndecl;
1382   struct cgraph_node *node;
1383
1384   v = BINFO_VIRTUALS (known_binfo);
1385   /* If there is no virtual methods leave the OBJ_TYPE_REF alone.  */
1386   if (!v)
1387     return NULL_TREE;
1388   i = 0;
1389   while (i != token)
1390     {
1391       i += (TARGET_VTABLE_USES_DESCRIPTORS
1392             ? TARGET_VTABLE_USES_DESCRIPTORS : 1);
1393       v = TREE_CHAIN (v);
1394     }
1395
1396   fndecl = TREE_VALUE (v);
1397   node = cgraph_get_node_or_alias (fndecl);
1398   if (refuse_thunks
1399       && (!node
1400     /* Bail out if it is a thunk declaration.  Since simple this_adjusting
1401        thunks are represented by a constant in TREE_PURPOSE of items in
1402        BINFO_VIRTUALS, this is a more complicate type which we cannot handle as
1403        yet.
1404
1405        FIXME: Remove the following condition once we are able to represent
1406        thunk information on call graph edges.  */
1407           || (node->same_body_alias && node->thunk.thunk_p)))
1408     return NULL_TREE;
1409
1410   /* When cgraph node is missing and function is not public, we cannot
1411      devirtualize.  This can happen in WHOPR when the actual method
1412      ends up in other partition, because we found devirtualization
1413      possibility too late.  */
1414   if (!can_refer_decl_in_current_unit_p (TREE_VALUE (v)))
1415     return NULL_TREE;
1416
1417   *delta = TREE_PURPOSE (v);
1418   gcc_checking_assert (host_integerp (*delta, 0));
1419   return fndecl;
1420 }
1421
1422 /* Generate code adjusting the first parameter of a call statement determined
1423    by GSI by DELTA.  */
1424
1425 void
1426 gimple_adjust_this_by_delta (gimple_stmt_iterator *gsi, tree delta)
1427 {
1428   gimple call_stmt = gsi_stmt (*gsi);
1429   tree parm, tmp;
1430   gimple new_stmt;
1431
1432   delta = fold_convert (sizetype, delta);
1433   gcc_assert (gimple_call_num_args (call_stmt) >= 1);
1434   parm = gimple_call_arg (call_stmt, 0);
1435   gcc_assert (POINTER_TYPE_P (TREE_TYPE (parm)));
1436   tmp = create_tmp_var (TREE_TYPE (parm), NULL);
1437   add_referenced_var (tmp);
1438
1439   tmp = make_ssa_name (tmp, NULL);
1440   new_stmt = gimple_build_assign_with_ops (POINTER_PLUS_EXPR, tmp, parm, delta);
1441   SSA_NAME_DEF_STMT (tmp) = new_stmt;
1442   gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
1443   gimple_call_set_arg (call_stmt, 0, tmp);
1444 }
1445
1446 /* Fold a call statement to OBJ_TYPE_REF to a direct call, if possible.  GSI
1447    determines the statement, generating new statements is allowed only if
1448    INPLACE is false.  Return true iff the statement was changed.  */
1449
1450 static bool
1451 gimple_fold_obj_type_ref_call (gimple_stmt_iterator *gsi)
1452 {
1453   gimple stmt = gsi_stmt (*gsi);
1454   tree ref = gimple_call_fn (stmt);
1455   tree obj = OBJ_TYPE_REF_OBJECT (ref);
1456   tree binfo, fndecl, delta;
1457   HOST_WIDE_INT token;
1458
1459   if (TREE_CODE (obj) != ADDR_EXPR)
1460     return false;
1461   obj = TREE_OPERAND (obj, 0);
1462   if (!DECL_P (obj)
1463       || TREE_CODE (TREE_TYPE (obj)) != RECORD_TYPE)
1464     return false;
1465   binfo = TYPE_BINFO (TREE_TYPE (obj));
1466   if (!binfo)
1467     return false;
1468
1469   token = tree_low_cst (OBJ_TYPE_REF_TOKEN (ref), 1);
1470   fndecl = gimple_get_virt_mehtod_for_binfo (token, binfo, &delta, false);
1471   if (!fndecl)
1472     return false;
1473   gcc_assert (integer_zerop (delta));
1474   gimple_call_set_fndecl (stmt, fndecl);
1475   return true;
1476 }
1477
1478 /* Attempt to fold a call statement referenced by the statement iterator GSI.
1479    The statement may be replaced by another statement, e.g., if the call
1480    simplifies to a constant value. Return true if any changes were made.
1481    It is assumed that the operands have been previously folded.  */
1482
1483 bool
1484 gimple_fold_call (gimple_stmt_iterator *gsi, bool inplace)
1485 {
1486   gimple stmt = gsi_stmt (*gsi);
1487
1488   tree callee = gimple_call_fndecl (stmt);
1489
1490   /* Check for builtins that CCP can handle using information not
1491      available in the generic fold routines.  */
1492   if (!inplace && callee && DECL_BUILT_IN (callee))
1493     {
1494       tree result = gimple_fold_builtin (stmt);
1495
1496       if (result)
1497         {
1498           if (!update_call_from_tree (gsi, result))
1499             gimplify_and_update_call_from_tree (gsi, result);
1500           return true;
1501         }
1502     }
1503   else
1504     {
1505       /* ??? Should perhaps do this in fold proper.  However, doing it
1506          there requires that we create a new CALL_EXPR, and that requires
1507          copying EH region info to the new node.  Easier to just do it
1508          here where we can just smash the call operand.  */
1509       callee = gimple_call_fn (stmt);
1510       if (TREE_CODE (callee) == OBJ_TYPE_REF)
1511         return gimple_fold_obj_type_ref_call (gsi);
1512     }
1513
1514   return false;
1515 }
1516
1517 /* Worker for both fold_stmt and fold_stmt_inplace.  The INPLACE argument
1518    distinguishes both cases.  */
1519
1520 static bool
1521 fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace)
1522 {
1523   bool changed = false;
1524   gimple stmt = gsi_stmt (*gsi);
1525   unsigned i;
1526
1527   /* Fold the main computation performed by the statement.  */
1528   switch (gimple_code (stmt))
1529     {
1530     case GIMPLE_ASSIGN:
1531       {
1532         unsigned old_num_ops = gimple_num_ops (stmt);
1533         tree new_rhs = fold_gimple_assign (gsi);
1534         tree lhs = gimple_assign_lhs (stmt);
1535         if (new_rhs
1536             && !useless_type_conversion_p (TREE_TYPE (lhs),
1537                                            TREE_TYPE (new_rhs)))
1538           new_rhs = fold_convert (TREE_TYPE (lhs), new_rhs);
1539         if (new_rhs
1540             && (!inplace
1541                 || get_gimple_rhs_num_ops (TREE_CODE (new_rhs)) < old_num_ops))
1542           {
1543             gimple_assign_set_rhs_from_tree (gsi, new_rhs);
1544             changed = true;
1545           }
1546         break;
1547       }
1548
1549     case GIMPLE_COND:
1550       changed |= fold_gimple_cond (stmt);
1551       break;
1552
1553     case GIMPLE_CALL:
1554       /* Fold *& in call arguments.  */
1555       for (i = 0; i < gimple_call_num_args (stmt); ++i)
1556         if (REFERENCE_CLASS_P (gimple_call_arg (stmt, i)))
1557           {
1558             tree tmp = maybe_fold_reference (gimple_call_arg (stmt, i), false);
1559             if (tmp)
1560               {
1561                 gimple_call_set_arg (stmt, i, tmp);
1562                 changed = true;
1563               }
1564           }
1565       changed |= gimple_fold_call (gsi, inplace);
1566       break;
1567
1568     case GIMPLE_ASM:
1569       /* Fold *& in asm operands.  */
1570       for (i = 0; i < gimple_asm_noutputs (stmt); ++i)
1571         {
1572           tree link = gimple_asm_output_op (stmt, i);
1573           tree op = TREE_VALUE (link);
1574           if (REFERENCE_CLASS_P (op)
1575               && (op = maybe_fold_reference (op, true)) != NULL_TREE)
1576             {
1577               TREE_VALUE (link) = op;
1578               changed = true;
1579             }
1580         }
1581       for (i = 0; i < gimple_asm_ninputs (stmt); ++i)
1582         {
1583           tree link = gimple_asm_input_op (stmt, i);
1584           tree op = TREE_VALUE (link);
1585           if (REFERENCE_CLASS_P (op)
1586               && (op = maybe_fold_reference (op, false)) != NULL_TREE)
1587             {
1588               TREE_VALUE (link) = op;
1589               changed = true;
1590             }
1591         }
1592       break;
1593
1594     case GIMPLE_DEBUG:
1595       if (gimple_debug_bind_p (stmt))
1596         {
1597           tree val = gimple_debug_bind_get_value (stmt);
1598           if (val
1599               && REFERENCE_CLASS_P (val))
1600             {
1601               tree tem = maybe_fold_reference (val, false);
1602               if (tem)
1603                 {
1604                   gimple_debug_bind_set_value (stmt, tem);
1605                   changed = true;
1606                 }
1607             }
1608         }
1609       break;
1610
1611     default:;
1612     }
1613
1614   stmt = gsi_stmt (*gsi);
1615
1616   /* Fold *& on the lhs.  */
1617   if (gimple_has_lhs (stmt))
1618     {
1619       tree lhs = gimple_get_lhs (stmt);
1620       if (lhs && REFERENCE_CLASS_P (lhs))
1621         {
1622           tree new_lhs = maybe_fold_reference (lhs, true);
1623           if (new_lhs)
1624             {
1625               gimple_set_lhs (stmt, new_lhs);
1626               changed = true;
1627             }
1628         }
1629     }
1630
1631   return changed;
1632 }
1633
1634 /* Fold the statement pointed to by GSI.  In some cases, this function may
1635    replace the whole statement with a new one.  Returns true iff folding
1636    makes any changes.
1637    The statement pointed to by GSI should be in valid gimple form but may
1638    be in unfolded state as resulting from for example constant propagation
1639    which can produce *&x = 0.  */
1640
1641 bool
1642 fold_stmt (gimple_stmt_iterator *gsi)
1643 {
1644   return fold_stmt_1 (gsi, false);
1645 }
1646
1647 /* Perform the minimal folding on statement STMT.  Only operations like
1648    *&x created by constant propagation are handled.  The statement cannot
1649    be replaced with a new one.  Return true if the statement was
1650    changed, false otherwise.
1651    The statement STMT should be in valid gimple form but may
1652    be in unfolded state as resulting from for example constant propagation
1653    which can produce *&x = 0.  */
1654
1655 bool
1656 fold_stmt_inplace (gimple stmt)
1657 {
1658   gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
1659   bool changed = fold_stmt_1 (&gsi, true);
1660   gcc_assert (gsi_stmt (gsi) == stmt);
1661   return changed;
1662 }
1663
1664 /* Canonicalize and possibly invert the boolean EXPR; return NULL_TREE
1665    if EXPR is null or we don't know how.
1666    If non-null, the result always has boolean type.  */
1667
1668 static tree
1669 canonicalize_bool (tree expr, bool invert)
1670 {
1671   if (!expr)
1672     return NULL_TREE;
1673   else if (invert)
1674     {
1675       if (integer_nonzerop (expr))
1676         return boolean_false_node;
1677       else if (integer_zerop (expr))
1678         return boolean_true_node;
1679       else if (TREE_CODE (expr) == SSA_NAME)
1680         return fold_build2 (EQ_EXPR, boolean_type_node, expr,
1681                             build_int_cst (TREE_TYPE (expr), 0));
1682       else if (TREE_CODE_CLASS (TREE_CODE (expr)) == tcc_comparison)
1683         return fold_build2 (invert_tree_comparison (TREE_CODE (expr), false),
1684                             boolean_type_node,
1685                             TREE_OPERAND (expr, 0),
1686                             TREE_OPERAND (expr, 1));
1687       else
1688         return NULL_TREE;
1689     }
1690   else
1691     {
1692       if (TREE_CODE (TREE_TYPE (expr)) == BOOLEAN_TYPE)
1693         return expr;
1694       if (integer_nonzerop (expr))
1695         return boolean_true_node;
1696       else if (integer_zerop (expr))
1697         return boolean_false_node;
1698       else if (TREE_CODE (expr) == SSA_NAME)
1699         return fold_build2 (NE_EXPR, boolean_type_node, expr,
1700                             build_int_cst (TREE_TYPE (expr), 0));
1701       else if (TREE_CODE_CLASS (TREE_CODE (expr)) == tcc_comparison)
1702         return fold_build2 (TREE_CODE (expr),
1703                             boolean_type_node,
1704                             TREE_OPERAND (expr, 0),
1705                             TREE_OPERAND (expr, 1));
1706       else
1707         return NULL_TREE;
1708     }
1709 }
1710
1711 /* Check to see if a boolean expression EXPR is logically equivalent to the
1712    comparison (OP1 CODE OP2).  Check for various identities involving
1713    SSA_NAMEs.  */
1714
1715 static bool
1716 same_bool_comparison_p (const_tree expr, enum tree_code code,
1717                         const_tree op1, const_tree op2)
1718 {
1719   gimple s;
1720
1721   /* The obvious case.  */
1722   if (TREE_CODE (expr) == code
1723       && operand_equal_p (TREE_OPERAND (expr, 0), op1, 0)
1724       && operand_equal_p (TREE_OPERAND (expr, 1), op2, 0))
1725     return true;
1726
1727   /* Check for comparing (name, name != 0) and the case where expr
1728      is an SSA_NAME with a definition matching the comparison.  */
1729   if (TREE_CODE (expr) == SSA_NAME
1730       && TREE_CODE (TREE_TYPE (expr)) == BOOLEAN_TYPE)
1731     {
1732       if (operand_equal_p (expr, op1, 0))
1733         return ((code == NE_EXPR && integer_zerop (op2))
1734                 || (code == EQ_EXPR && integer_nonzerop (op2)));
1735       s = SSA_NAME_DEF_STMT (expr);
1736       if (is_gimple_assign (s)
1737           && gimple_assign_rhs_code (s) == code
1738           && operand_equal_p (gimple_assign_rhs1 (s), op1, 0)
1739           && operand_equal_p (gimple_assign_rhs2 (s), op2, 0))
1740         return true;
1741     }
1742
1743   /* If op1 is of the form (name != 0) or (name == 0), and the definition
1744      of name is a comparison, recurse.  */
1745   if (TREE_CODE (op1) == SSA_NAME
1746       && TREE_CODE (TREE_TYPE (op1)) == BOOLEAN_TYPE)
1747     {
1748       s = SSA_NAME_DEF_STMT (op1);
1749       if (is_gimple_assign (s)
1750           && TREE_CODE_CLASS (gimple_assign_rhs_code (s)) == tcc_comparison)
1751         {
1752           enum tree_code c = gimple_assign_rhs_code (s);
1753           if ((c == NE_EXPR && integer_zerop (op2))
1754               || (c == EQ_EXPR && integer_nonzerop (op2)))
1755             return same_bool_comparison_p (expr, c,
1756                                            gimple_assign_rhs1 (s),
1757                                            gimple_assign_rhs2 (s));
1758           if ((c == EQ_EXPR && integer_zerop (op2))
1759               || (c == NE_EXPR && integer_nonzerop (op2)))
1760             return same_bool_comparison_p (expr,
1761                                            invert_tree_comparison (c, false),
1762                                            gimple_assign_rhs1 (s),
1763                                            gimple_assign_rhs2 (s));
1764         }
1765     }
1766   return false;
1767 }
1768
1769 /* Check to see if two boolean expressions OP1 and OP2 are logically
1770    equivalent.  */
1771
1772 static bool
1773 same_bool_result_p (const_tree op1, const_tree op2)
1774 {
1775   /* Simple cases first.  */
1776   if (operand_equal_p (op1, op2, 0))
1777     return true;
1778
1779   /* Check the cases where at least one of the operands is a comparison.
1780      These are a bit smarter than operand_equal_p in that they apply some
1781      identifies on SSA_NAMEs.  */
1782   if (TREE_CODE_CLASS (TREE_CODE (op2)) == tcc_comparison
1783       && same_bool_comparison_p (op1, TREE_CODE (op2),
1784                                  TREE_OPERAND (op2, 0),
1785                                  TREE_OPERAND (op2, 1)))
1786     return true;
1787   if (TREE_CODE_CLASS (TREE_CODE (op1)) == tcc_comparison
1788       && same_bool_comparison_p (op2, TREE_CODE (op1),
1789                                  TREE_OPERAND (op1, 0),
1790                                  TREE_OPERAND (op1, 1)))
1791     return true;
1792
1793   /* Default case.  */
1794   return false;
1795 }
1796
1797 /* Forward declarations for some mutually recursive functions.  */
1798
1799 static tree
1800 and_comparisons_1 (enum tree_code code1, tree op1a, tree op1b,
1801                    enum tree_code code2, tree op2a, tree op2b);
1802 static tree
1803 and_var_with_comparison (tree var, bool invert,
1804                          enum tree_code code2, tree op2a, tree op2b);
1805 static tree
1806 and_var_with_comparison_1 (gimple stmt,
1807                            enum tree_code code2, tree op2a, tree op2b);
1808 static tree
1809 or_comparisons_1 (enum tree_code code1, tree op1a, tree op1b,
1810                   enum tree_code code2, tree op2a, tree op2b);
1811 static tree
1812 or_var_with_comparison (tree var, bool invert,
1813                         enum tree_code code2, tree op2a, tree op2b);
1814 static tree
1815 or_var_with_comparison_1 (gimple stmt,
1816                           enum tree_code code2, tree op2a, tree op2b);
1817
1818 /* Helper function for and_comparisons_1:  try to simplify the AND of the
1819    ssa variable VAR with the comparison specified by (OP2A CODE2 OP2B).
1820    If INVERT is true, invert the value of the VAR before doing the AND.
1821    Return NULL_EXPR if we can't simplify this to a single expression.  */
1822
1823 static tree
1824 and_var_with_comparison (tree var, bool invert,
1825                          enum tree_code code2, tree op2a, tree op2b)
1826 {
1827   tree t;
1828   gimple stmt = SSA_NAME_DEF_STMT (var);
1829
1830   /* We can only deal with variables whose definitions are assignments.  */
1831   if (!is_gimple_assign (stmt))
1832     return NULL_TREE;
1833
1834   /* If we have an inverted comparison, apply DeMorgan's law and rewrite
1835      !var AND (op2a code2 op2b) => !(var OR !(op2a code2 op2b))
1836      Then we only have to consider the simpler non-inverted cases.  */
1837   if (invert)
1838     t = or_var_with_comparison_1 (stmt,
1839                                   invert_tree_comparison (code2, false),
1840                                   op2a, op2b);
1841   else
1842     t = and_var_with_comparison_1 (stmt, code2, op2a, op2b);
1843   return canonicalize_bool (t, invert);
1844 }
1845
1846 /* Try to simplify the AND of the ssa variable defined by the assignment
1847    STMT with the comparison specified by (OP2A CODE2 OP2B).
1848    Return NULL_EXPR if we can't simplify this to a single expression.  */
1849
1850 static tree
1851 and_var_with_comparison_1 (gimple stmt,
1852                            enum tree_code code2, tree op2a, tree op2b)
1853 {
1854   tree var = gimple_assign_lhs (stmt);
1855   tree true_test_var = NULL_TREE;
1856   tree false_test_var = NULL_TREE;
1857   enum tree_code innercode = gimple_assign_rhs_code (stmt);
1858
1859   /* Check for identities like (var AND (var == 0)) => false.  */
1860   if (TREE_CODE (op2a) == SSA_NAME
1861       && TREE_CODE (TREE_TYPE (var)) == BOOLEAN_TYPE)
1862     {
1863       if ((code2 == NE_EXPR && integer_zerop (op2b))
1864           || (code2 == EQ_EXPR && integer_nonzerop (op2b)))
1865         {
1866           true_test_var = op2a;
1867           if (var == true_test_var)
1868             return var;
1869         }
1870       else if ((code2 == EQ_EXPR && integer_zerop (op2b))
1871                || (code2 == NE_EXPR && integer_nonzerop (op2b)))
1872         {
1873           false_test_var = op2a;
1874           if (var == false_test_var)
1875             return boolean_false_node;
1876         }
1877     }
1878
1879   /* If the definition is a comparison, recurse on it.  */
1880   if (TREE_CODE_CLASS (innercode) == tcc_comparison)
1881     {
1882       tree t = and_comparisons_1 (innercode,
1883                                   gimple_assign_rhs1 (stmt),
1884                                   gimple_assign_rhs2 (stmt),
1885                                   code2,
1886                                   op2a,
1887                                   op2b);
1888       if (t)
1889         return t;
1890     }
1891
1892   /* If the definition is an AND or OR expression, we may be able to
1893      simplify by reassociating.  */
1894   if (innercode == TRUTH_AND_EXPR
1895       || innercode == TRUTH_OR_EXPR
1896       || (TREE_CODE (TREE_TYPE (var)) == BOOLEAN_TYPE
1897           && (innercode == BIT_AND_EXPR || innercode == BIT_IOR_EXPR)))
1898     {
1899       tree inner1 = gimple_assign_rhs1 (stmt);
1900       tree inner2 = gimple_assign_rhs2 (stmt);
1901       gimple s;
1902       tree t;
1903       tree partial = NULL_TREE;
1904       bool is_and = (innercode == TRUTH_AND_EXPR || innercode == BIT_AND_EXPR);
1905
1906       /* Check for boolean identities that don't require recursive examination
1907          of inner1/inner2:
1908          inner1 AND (inner1 AND inner2) => inner1 AND inner2 => var
1909          inner1 AND (inner1 OR inner2) => inner1
1910          !inner1 AND (inner1 AND inner2) => false
1911          !inner1 AND (inner1 OR inner2) => !inner1 AND inner2
1912          Likewise for similar cases involving inner2.  */
1913       if (inner1 == true_test_var)
1914         return (is_and ? var : inner1);
1915       else if (inner2 == true_test_var)
1916         return (is_and ? var : inner2);
1917       else if (inner1 == false_test_var)
1918         return (is_and
1919                 ? boolean_false_node
1920                 : and_var_with_comparison (inner2, false, code2, op2a, op2b));
1921       else if (inner2 == false_test_var)
1922         return (is_and
1923                 ? boolean_false_node
1924                 : and_var_with_comparison (inner1, false, code2, op2a, op2b));
1925
1926       /* Next, redistribute/reassociate the AND across the inner tests.
1927          Compute the first partial result, (inner1 AND (op2a code op2b))  */
1928       if (TREE_CODE (inner1) == SSA_NAME
1929           && is_gimple_assign (s = SSA_NAME_DEF_STMT (inner1))
1930           && TREE_CODE_CLASS (gimple_assign_rhs_code (s)) == tcc_comparison
1931           && (t = maybe_fold_and_comparisons (gimple_assign_rhs_code (s),
1932                                               gimple_assign_rhs1 (s),
1933                                               gimple_assign_rhs2 (s),
1934                                               code2, op2a, op2b)))
1935         {
1936           /* Handle the AND case, where we are reassociating:
1937              (inner1 AND inner2) AND (op2a code2 op2b)
1938              => (t AND inner2)
1939              If the partial result t is a constant, we win.  Otherwise
1940              continue on to try reassociating with the other inner test.  */
1941           if (is_and)
1942             {
1943               if (integer_onep (t))
1944                 return inner2;
1945               else if (integer_zerop (t))
1946                 return boolean_false_node;
1947             }
1948
1949           /* Handle the OR case, where we are redistributing:
1950              (inner1 OR inner2) AND (op2a code2 op2b)
1951              => (t OR (inner2 AND (op2a code2 op2b)))  */
1952           else if (integer_onep (t))
1953             return boolean_true_node;
1954
1955           /* Save partial result for later.  */
1956           partial = t;
1957         }
1958
1959       /* Compute the second partial result, (inner2 AND (op2a code op2b)) */
1960       if (TREE_CODE (inner2) == SSA_NAME
1961           && is_gimple_assign (s = SSA_NAME_DEF_STMT (inner2))
1962           && TREE_CODE_CLASS (gimple_assign_rhs_code (s)) == tcc_comparison
1963           && (t = maybe_fold_and_comparisons (gimple_assign_rhs_code (s),
1964                                               gimple_assign_rhs1 (s),
1965                                               gimple_assign_rhs2 (s),
1966                                               code2, op2a, op2b)))
1967         {
1968           /* Handle the AND case, where we are reassociating:
1969              (inner1 AND inner2) AND (op2a code2 op2b)
1970              => (inner1 AND t)  */
1971           if (is_and)
1972             {
1973               if (integer_onep (t))
1974                 return inner1;
1975               else if (integer_zerop (t))
1976                 return boolean_false_node;
1977               /* If both are the same, we can apply the identity
1978                  (x AND x) == x.  */
1979               else if (partial && same_bool_result_p (t, partial))
1980                 return t;
1981             }
1982
1983           /* Handle the OR case. where we are redistributing:
1984              (inner1 OR inner2) AND (op2a code2 op2b)
1985              => (t OR (inner1 AND (op2a code2 op2b)))
1986              => (t OR partial)  */
1987           else
1988             {
1989               if (integer_onep (t))
1990                 return boolean_true_node;
1991               else if (partial)
1992                 {
1993                   /* We already got a simplification for the other
1994                      operand to the redistributed OR expression.  The
1995                      interesting case is when at least one is false.
1996                      Or, if both are the same, we can apply the identity
1997                      (x OR x) == x.  */
1998                   if (integer_zerop (partial))
1999                     return t;
2000                   else if (integer_zerop (t))
2001                     return partial;
2002                   else if (same_bool_result_p (t, partial))
2003                     return t;
2004                 }
2005             }
2006         }
2007     }
2008   return NULL_TREE;
2009 }
2010
2011 /* Try to simplify the AND of two comparisons defined by
2012    (OP1A CODE1 OP1B) and (OP2A CODE2 OP2B), respectively.
2013    If this can be done without constructing an intermediate value,
2014    return the resulting tree; otherwise NULL_TREE is returned.
2015    This function is deliberately asymmetric as it recurses on SSA_DEFs
2016    in the first comparison but not the second.  */
2017
2018 static tree
2019 and_comparisons_1 (enum tree_code code1, tree op1a, tree op1b,
2020                    enum tree_code code2, tree op2a, tree op2b)
2021 {
2022   /* First check for ((x CODE1 y) AND (x CODE2 y)).  */
2023   if (operand_equal_p (op1a, op2a, 0)
2024       && operand_equal_p (op1b, op2b, 0))
2025     {
2026       tree t = combine_comparisons (UNKNOWN_LOCATION,
2027                                     TRUTH_ANDIF_EXPR, code1, code2,
2028                                     boolean_type_node, op1a, op1b);
2029       if (t)
2030         return t;
2031     }
2032
2033   /* Likewise the swapped case of the above.  */
2034   if (operand_equal_p (op1a, op2b, 0)
2035       && operand_equal_p (op1b, op2a, 0))
2036     {
2037       tree t = combine_comparisons (UNKNOWN_LOCATION,
2038                                     TRUTH_ANDIF_EXPR, code1,
2039                                     swap_tree_comparison (code2),
2040                                     boolean_type_node, op1a, op1b);
2041       if (t)
2042         return t;
2043     }
2044
2045   /* If both comparisons are of the same value against constants, we might
2046      be able to merge them.  */
2047   if (operand_equal_p (op1a, op2a, 0)
2048       && TREE_CODE (op1b) == INTEGER_CST
2049       && TREE_CODE (op2b) == INTEGER_CST)
2050     {
2051       int cmp = tree_int_cst_compare (op1b, op2b);
2052
2053       /* If we have (op1a == op1b), we should either be able to
2054          return that or FALSE, depending on whether the constant op1b
2055          also satisfies the other comparison against op2b.  */
2056       if (code1 == EQ_EXPR)
2057         {
2058           bool done = true;
2059           bool val;
2060           switch (code2)
2061             {
2062             case EQ_EXPR: val = (cmp == 0); break;
2063             case NE_EXPR: val = (cmp != 0); break;
2064             case LT_EXPR: val = (cmp < 0); break;
2065             case GT_EXPR: val = (cmp > 0); break;
2066             case LE_EXPR: val = (cmp <= 0); break;
2067             case GE_EXPR: val = (cmp >= 0); break;
2068             default: done = false;
2069             }
2070           if (done)
2071             {
2072               if (val)
2073                 return fold_build2 (code1, boolean_type_node, op1a, op1b);
2074               else
2075                 return boolean_false_node;
2076             }
2077         }
2078       /* Likewise if the second comparison is an == comparison.  */
2079       else if (code2 == EQ_EXPR)
2080         {
2081           bool done = true;
2082           bool val;
2083           switch (code1)
2084             {
2085             case EQ_EXPR: val = (cmp == 0); break;
2086             case NE_EXPR: val = (cmp != 0); break;
2087             case LT_EXPR: val = (cmp > 0); break;
2088             case GT_EXPR: val = (cmp < 0); break;
2089             case LE_EXPR: val = (cmp >= 0); break;
2090             case GE_EXPR: val = (cmp <= 0); break;
2091             default: done = false;
2092             }
2093           if (done)
2094             {
2095               if (val)
2096                 return fold_build2 (code2, boolean_type_node, op2a, op2b);
2097               else
2098                 return boolean_false_node;
2099             }
2100         }
2101
2102       /* Same business with inequality tests.  */
2103       else if (code1 == NE_EXPR)
2104         {
2105           bool val;
2106           switch (code2)
2107             {
2108             case EQ_EXPR: val = (cmp != 0); break;
2109             case NE_EXPR: val = (cmp == 0); break;
2110             case LT_EXPR: val = (cmp >= 0); break;
2111             case GT_EXPR: val = (cmp <= 0); break;
2112             case LE_EXPR: val = (cmp > 0); break;
2113             case GE_EXPR: val = (cmp < 0); break;
2114             default:
2115               val = false;
2116             }
2117           if (val)
2118             return fold_build2 (code2, boolean_type_node, op2a, op2b);
2119         }
2120       else if (code2 == NE_EXPR)
2121         {
2122           bool val;
2123           switch (code1)
2124             {
2125             case EQ_EXPR: val = (cmp == 0); break;
2126             case NE_EXPR: val = (cmp != 0); break;
2127             case LT_EXPR: val = (cmp <= 0); break;
2128             case GT_EXPR: val = (cmp >= 0); break;
2129             case LE_EXPR: val = (cmp < 0); break;
2130             case GE_EXPR: val = (cmp > 0); break;
2131             default:
2132               val = false;
2133             }
2134           if (val)
2135             return fold_build2 (code1, boolean_type_node, op1a, op1b);
2136         }
2137
2138       /* Chose the more restrictive of two < or <= comparisons.  */
2139       else if ((code1 == LT_EXPR || code1 == LE_EXPR)
2140                && (code2 == LT_EXPR || code2 == LE_EXPR))
2141         {
2142           if ((cmp < 0) || (cmp == 0 && code1 == LT_EXPR))
2143             return fold_build2 (code1, boolean_type_node, op1a, op1b);
2144           else
2145             return fold_build2 (code2, boolean_type_node, op2a, op2b);
2146         }
2147
2148       /* Likewise chose the more restrictive of two > or >= comparisons.  */
2149       else if ((code1 == GT_EXPR || code1 == GE_EXPR)
2150                && (code2 == GT_EXPR || code2 == GE_EXPR))
2151         {
2152           if ((cmp > 0) || (cmp == 0 && code1 == GT_EXPR))
2153             return fold_build2 (code1, boolean_type_node, op1a, op1b);
2154           else
2155             return fold_build2 (code2, boolean_type_node, op2a, op2b);
2156         }
2157
2158       /* Check for singleton ranges.  */
2159       else if (cmp == 0
2160                && ((code1 == LE_EXPR && code2 == GE_EXPR)
2161                    || (code1 == GE_EXPR && code2 == LE_EXPR)))
2162         return fold_build2 (EQ_EXPR, boolean_type_node, op1a, op2b);
2163
2164       /* Check for disjoint ranges. */
2165       else if (cmp <= 0
2166                && (code1 == LT_EXPR || code1 == LE_EXPR)
2167                && (code2 == GT_EXPR || code2 == GE_EXPR))
2168         return boolean_false_node;
2169       else if (cmp >= 0
2170                && (code1 == GT_EXPR || code1 == GE_EXPR)
2171                && (code2 == LT_EXPR || code2 == LE_EXPR))
2172         return boolean_false_node;
2173     }
2174
2175   /* Perhaps the first comparison is (NAME != 0) or (NAME == 1) where
2176      NAME's definition is a truth value.  See if there are any simplifications
2177      that can be done against the NAME's definition.  */
2178   if (TREE_CODE (op1a) == SSA_NAME
2179       && (code1 == NE_EXPR || code1 == EQ_EXPR)
2180       && (integer_zerop (op1b) || integer_onep (op1b)))
2181     {
2182       bool invert = ((code1 == EQ_EXPR && integer_zerop (op1b))
2183                      || (code1 == NE_EXPR && integer_onep (op1b)));
2184       gimple stmt = SSA_NAME_DEF_STMT (op1a);
2185       switch (gimple_code (stmt))
2186         {
2187         case GIMPLE_ASSIGN:
2188           /* Try to simplify by copy-propagating the definition.  */
2189           return and_var_with_comparison (op1a, invert, code2, op2a, op2b);
2190
2191         case GIMPLE_PHI:
2192           /* If every argument to the PHI produces the same result when
2193              ANDed with the second comparison, we win.
2194              Do not do this unless the type is bool since we need a bool
2195              result here anyway.  */
2196           if (TREE_CODE (TREE_TYPE (op1a)) == BOOLEAN_TYPE)
2197             {
2198               tree result = NULL_TREE;
2199               unsigned i;
2200               for (i = 0; i < gimple_phi_num_args (stmt); i++)
2201                 {
2202                   tree arg = gimple_phi_arg_def (stmt, i);
2203
2204                   /* If this PHI has itself as an argument, ignore it.
2205                      If all the other args produce the same result,
2206                      we're still OK.  */
2207                   if (arg == gimple_phi_result (stmt))
2208                     continue;
2209                   else if (TREE_CODE (arg) == INTEGER_CST)
2210                     {
2211                       if (invert ? integer_nonzerop (arg) : integer_zerop (arg))
2212                         {
2213                           if (!result)
2214                             result = boolean_false_node;
2215                           else if (!integer_zerop (result))
2216                             return NULL_TREE;
2217                         }
2218                       else if (!result)
2219                         result = fold_build2 (code2, boolean_type_node,
2220                                               op2a, op2b);
2221                       else if (!same_bool_comparison_p (result,
2222                                                         code2, op2a, op2b))
2223                         return NULL_TREE;
2224                     }
2225                   else if (TREE_CODE (arg) == SSA_NAME)
2226                     {
2227                       tree temp = and_var_with_comparison (arg, invert,
2228                                                            code2, op2a, op2b);
2229                       if (!temp)
2230                         return NULL_TREE;
2231                       else if (!result)
2232                         result = temp;
2233                       else if (!same_bool_result_p (result, temp))
2234                         return NULL_TREE;
2235                     }
2236                   else
2237                     return NULL_TREE;
2238                 }
2239               return result;
2240             }
2241
2242         default:
2243           break;
2244         }
2245     }
2246   return NULL_TREE;
2247 }
2248
2249 /* Try to simplify the AND of two comparisons, specified by
2250    (OP1A CODE1 OP1B) and (OP2B CODE2 OP2B), respectively.
2251    If this can be simplified to a single expression (without requiring
2252    introducing more SSA variables to hold intermediate values),
2253    return the resulting tree.  Otherwise return NULL_TREE.
2254    If the result expression is non-null, it has boolean type.  */
2255
2256 tree
2257 maybe_fold_and_comparisons (enum tree_code code1, tree op1a, tree op1b,
2258                             enum tree_code code2, tree op2a, tree op2b)
2259 {
2260   tree t = and_comparisons_1 (code1, op1a, op1b, code2, op2a, op2b);
2261   if (t)
2262     return t;
2263   else
2264     return and_comparisons_1 (code2, op2a, op2b, code1, op1a, op1b);
2265 }
2266
2267 /* Helper function for or_comparisons_1:  try to simplify the OR of the
2268    ssa variable VAR with the comparison specified by (OP2A CODE2 OP2B).
2269    If INVERT is true, invert the value of VAR before doing the OR.
2270    Return NULL_EXPR if we can't simplify this to a single expression.  */
2271
2272 static tree
2273 or_var_with_comparison (tree var, bool invert,
2274                         enum tree_code code2, tree op2a, tree op2b)
2275 {
2276   tree t;
2277   gimple stmt = SSA_NAME_DEF_STMT (var);
2278
2279   /* We can only deal with variables whose definitions are assignments.  */
2280   if (!is_gimple_assign (stmt))
2281     return NULL_TREE;
2282
2283   /* If we have an inverted comparison, apply DeMorgan's law and rewrite
2284      !var OR (op2a code2 op2b) => !(var AND !(op2a code2 op2b))
2285      Then we only have to consider the simpler non-inverted cases.  */
2286   if (invert)
2287     t = and_var_with_comparison_1 (stmt,
2288                                    invert_tree_comparison (code2, false),
2289                                    op2a, op2b);
2290   else
2291     t = or_var_with_comparison_1 (stmt, code2, op2a, op2b);
2292   return canonicalize_bool (t, invert);
2293 }
2294
2295 /* Try to simplify the OR of the ssa variable defined by the assignment
2296    STMT with the comparison specified by (OP2A CODE2 OP2B).
2297    Return NULL_EXPR if we can't simplify this to a single expression.  */
2298
2299 static tree
2300 or_var_with_comparison_1 (gimple stmt,
2301                           enum tree_code code2, tree op2a, tree op2b)
2302 {
2303   tree var = gimple_assign_lhs (stmt);
2304   tree true_test_var = NULL_TREE;
2305   tree false_test_var = NULL_TREE;
2306   enum tree_code innercode = gimple_assign_rhs_code (stmt);
2307
2308   /* Check for identities like (var OR (var != 0)) => true .  */
2309   if (TREE_CODE (op2a) == SSA_NAME
2310       && TREE_CODE (TREE_TYPE (var)) == BOOLEAN_TYPE)
2311     {
2312       if ((code2 == NE_EXPR && integer_zerop (op2b))
2313           || (code2 == EQ_EXPR && integer_nonzerop (op2b)))
2314         {
2315           true_test_var = op2a;
2316           if (var == true_test_var)
2317             return var;
2318         }
2319       else if ((code2 == EQ_EXPR && integer_zerop (op2b))
2320                || (code2 == NE_EXPR && integer_nonzerop (op2b)))
2321         {
2322           false_test_var = op2a;
2323           if (var == false_test_var)
2324             return boolean_true_node;
2325         }
2326     }
2327
2328   /* If the definition is a comparison, recurse on it.  */
2329   if (TREE_CODE_CLASS (innercode) == tcc_comparison)
2330     {
2331       tree t = or_comparisons_1 (innercode,
2332                                  gimple_assign_rhs1 (stmt),
2333                                  gimple_assign_rhs2 (stmt),
2334                                  code2,
2335                                  op2a,
2336                                  op2b);
2337       if (t)
2338         return t;
2339     }
2340
2341   /* If the definition is an AND or OR expression, we may be able to
2342      simplify by reassociating.  */
2343   if (innercode == TRUTH_AND_EXPR
2344       || innercode == TRUTH_OR_EXPR
2345       || (TREE_CODE (TREE_TYPE (var)) == BOOLEAN_TYPE
2346           && (innercode == BIT_AND_EXPR || innercode == BIT_IOR_EXPR)))
2347     {
2348       tree inner1 = gimple_assign_rhs1 (stmt);
2349       tree inner2 = gimple_assign_rhs2 (stmt);
2350       gimple s;
2351       tree t;
2352       tree partial = NULL_TREE;
2353       bool is_or = (innercode == TRUTH_OR_EXPR || innercode == BIT_IOR_EXPR);
2354
2355       /* Check for boolean identities that don't require recursive examination
2356          of inner1/inner2:
2357          inner1 OR (inner1 OR inner2) => inner1 OR inner2 => var
2358          inner1 OR (inner1 AND inner2) => inner1
2359          !inner1 OR (inner1 OR inner2) => true
2360          !inner1 OR (inner1 AND inner2) => !inner1 OR inner2
2361       */
2362       if (inner1 == true_test_var)
2363         return (is_or ? var : inner1);
2364       else if (inner2 == true_test_var)
2365         return (is_or ? var : inner2);
2366       else if (inner1 == false_test_var)
2367         return (is_or
2368                 ? boolean_true_node
2369                 : or_var_with_comparison (inner2, false, code2, op2a, op2b));
2370       else if (inner2 == false_test_var)
2371         return (is_or
2372                 ? boolean_true_node
2373                 : or_var_with_comparison (inner1, false, code2, op2a, op2b));
2374
2375       /* Next, redistribute/reassociate the OR across the inner tests.
2376          Compute the first partial result, (inner1 OR (op2a code op2b))  */
2377       if (TREE_CODE (inner1) == SSA_NAME
2378           && is_gimple_assign (s = SSA_NAME_DEF_STMT (inner1))
2379           && TREE_CODE_CLASS (gimple_assign_rhs_code (s)) == tcc_comparison
2380           && (t = maybe_fold_or_comparisons (gimple_assign_rhs_code (s),
2381                                              gimple_assign_rhs1 (s),
2382                                              gimple_assign_rhs2 (s),
2383                                              code2, op2a, op2b)))
2384         {
2385           /* Handle the OR case, where we are reassociating:
2386              (inner1 OR inner2) OR (op2a code2 op2b)
2387              => (t OR inner2)
2388              If the partial result t is a constant, we win.  Otherwise
2389              continue on to try reassociating with the other inner test.  */
2390           if (is_or)
2391             {
2392               if (integer_onep (t))
2393                 return boolean_true_node;
2394               else if (integer_zerop (t))
2395                 return inner2;
2396             }
2397
2398           /* Handle the AND case, where we are redistributing:
2399              (inner1 AND inner2) OR (op2a code2 op2b)
2400              => (t AND (inner2 OR (op2a code op2b)))  */
2401           else if (integer_zerop (t))
2402             return boolean_false_node;
2403
2404           /* Save partial result for later.  */
2405           partial = t;
2406         }
2407
2408       /* Compute the second partial result, (inner2 OR (op2a code op2b)) */
2409       if (TREE_CODE (inner2) == SSA_NAME
2410           && is_gimple_assign (s = SSA_NAME_DEF_STMT (inner2))
2411           && TREE_CODE_CLASS (gimple_assign_rhs_code (s)) == tcc_comparison
2412           && (t = maybe_fold_or_comparisons (gimple_assign_rhs_code (s),
2413                                              gimple_assign_rhs1 (s),
2414                                              gimple_assign_rhs2 (s),
2415                                              code2, op2a, op2b)))
2416         {
2417           /* Handle the OR case, where we are reassociating:
2418              (inner1 OR inner2) OR (op2a code2 op2b)
2419              => (inner1 OR t)
2420              => (t OR partial)  */
2421           if (is_or)
2422             {
2423               if (integer_zerop (t))
2424                 return inner1;
2425               else if (integer_onep (t))
2426                 return boolean_true_node;
2427               /* If both are the same, we can apply the identity
2428                  (x OR x) == x.  */
2429               else if (partial && same_bool_result_p (t, partial))
2430                 return t;
2431             }
2432
2433           /* Handle the AND case, where we are redistributing:
2434              (inner1 AND inner2) OR (op2a code2 op2b)
2435              => (t AND (inner1 OR (op2a code2 op2b)))
2436              => (t AND partial)  */
2437           else
2438             {
2439               if (integer_zerop (t))
2440                 return boolean_false_node;
2441               else if (partial)
2442                 {
2443                   /* We already got a simplification for the other
2444                      operand to the redistributed AND expression.  The
2445                      interesting case is when at least one is true.
2446                      Or, if both are the same, we can apply the identity
2447                      (x AND x) == x.  */
2448                   if (integer_onep (partial))
2449                     return t;
2450                   else if (integer_onep (t))
2451                     return partial;
2452                   else if (same_bool_result_p (t, partial))
2453                     return t;
2454                 }
2455             }
2456         }
2457     }
2458   return NULL_TREE;
2459 }
2460
2461 /* Try to simplify the OR of two comparisons defined by
2462    (OP1A CODE1 OP1B) and (OP2A CODE2 OP2B), respectively.
2463    If this can be done without constructing an intermediate value,
2464    return the resulting tree; otherwise NULL_TREE is returned.
2465    This function is deliberately asymmetric as it recurses on SSA_DEFs
2466    in the first comparison but not the second.  */
2467
2468 static tree
2469 or_comparisons_1 (enum tree_code code1, tree op1a, tree op1b,
2470                   enum tree_code code2, tree op2a, tree op2b)
2471 {
2472   /* First check for ((x CODE1 y) OR (x CODE2 y)).  */
2473   if (operand_equal_p (op1a, op2a, 0)
2474       && operand_equal_p (op1b, op2b, 0))
2475     {
2476       tree t = combine_comparisons (UNKNOWN_LOCATION,
2477                                     TRUTH_ORIF_EXPR, code1, code2,
2478                                     boolean_type_node, op1a, op1b);
2479       if (t)
2480         return t;
2481     }
2482
2483   /* Likewise the swapped case of the above.  */
2484   if (operand_equal_p (op1a, op2b, 0)
2485       && operand_equal_p (op1b, op2a, 0))
2486     {
2487       tree t = combine_comparisons (UNKNOWN_LOCATION,
2488                                     TRUTH_ORIF_EXPR, code1,
2489                                     swap_tree_comparison (code2),
2490                                     boolean_type_node, op1a, op1b);
2491       if (t)
2492         return t;
2493     }
2494
2495   /* If both comparisons are of the same value against constants, we might
2496      be able to merge them.  */
2497   if (operand_equal_p (op1a, op2a, 0)
2498       && TREE_CODE (op1b) == INTEGER_CST
2499       && TREE_CODE (op2b) == INTEGER_CST)
2500     {
2501       int cmp = tree_int_cst_compare (op1b, op2b);
2502
2503       /* If we have (op1a != op1b), we should either be able to
2504          return that or TRUE, depending on whether the constant op1b
2505          also satisfies the other comparison against op2b.  */
2506       if (code1 == NE_EXPR)
2507         {
2508           bool done = true;
2509           bool val;
2510           switch (code2)
2511             {
2512             case EQ_EXPR: val = (cmp == 0); break;
2513             case NE_EXPR: val = (cmp != 0); break;
2514             case LT_EXPR: val = (cmp < 0); break;
2515             case GT_EXPR: val = (cmp > 0); break;
2516             case LE_EXPR: val = (cmp <= 0); break;
2517             case GE_EXPR: val = (cmp >= 0); break;
2518             default: done = false;
2519             }
2520           if (done)
2521             {
2522               if (val)
2523                 return boolean_true_node;
2524               else
2525                 return fold_build2 (code1, boolean_type_node, op1a, op1b);
2526             }
2527         }
2528       /* Likewise if the second comparison is a != comparison.  */
2529       else if (code2 == NE_EXPR)
2530         {
2531           bool done = true;
2532           bool val;
2533           switch (code1)
2534             {
2535             case EQ_EXPR: val = (cmp == 0); break;
2536             case NE_EXPR: val = (cmp != 0); break;
2537             case LT_EXPR: val = (cmp > 0); break;
2538             case GT_EXPR: val = (cmp < 0); break;
2539             case LE_EXPR: val = (cmp >= 0); break;
2540             case GE_EXPR: val = (cmp <= 0); break;
2541             default: done = false;
2542             }
2543           if (done)
2544             {
2545               if (val)
2546                 return boolean_true_node;
2547               else
2548                 return fold_build2 (code2, boolean_type_node, op2a, op2b);
2549             }
2550         }
2551
2552       /* See if an equality test is redundant with the other comparison.  */
2553       else if (code1 == EQ_EXPR)
2554         {
2555           bool val;
2556           switch (code2)
2557             {
2558             case EQ_EXPR: val = (cmp == 0); break;
2559             case NE_EXPR: val = (cmp != 0); break;
2560             case LT_EXPR: val = (cmp < 0); break;
2561             case GT_EXPR: val = (cmp > 0); break;
2562             case LE_EXPR: val = (cmp <= 0); break;
2563             case GE_EXPR: val = (cmp >= 0); break;
2564             default:
2565               val = false;
2566             }
2567           if (val)
2568             return fold_build2 (code2, boolean_type_node, op2a, op2b);
2569         }
2570       else if (code2 == EQ_EXPR)
2571         {
2572           bool val;
2573           switch (code1)
2574             {
2575             case EQ_EXPR: val = (cmp == 0); break;
2576             case NE_EXPR: val = (cmp != 0); break;
2577             case LT_EXPR: val = (cmp > 0); break;
2578             case GT_EXPR: val = (cmp < 0); break;
2579             case LE_EXPR: val = (cmp >= 0); break;
2580             case GE_EXPR: val = (cmp <= 0); break;
2581             default:
2582               val = false;
2583             }
2584           if (val)
2585             return fold_build2 (code1, boolean_type_node, op1a, op1b);
2586         }
2587
2588       /* Chose the less restrictive of two < or <= comparisons.  */
2589       else if ((code1 == LT_EXPR || code1 == LE_EXPR)
2590                && (code2 == LT_EXPR || code2 == LE_EXPR))
2591         {
2592           if ((cmp < 0) || (cmp == 0 && code1 == LT_EXPR))
2593             return fold_build2 (code2, boolean_type_node, op2a, op2b);
2594           else
2595             return fold_build2 (code1, boolean_type_node, op1a, op1b);
2596         }
2597
2598       /* Likewise chose the less restrictive of two > or >= comparisons.  */
2599       else if ((code1 == GT_EXPR || code1 == GE_EXPR)
2600                && (code2 == GT_EXPR || code2 == GE_EXPR))
2601         {
2602           if ((cmp > 0) || (cmp == 0 && code1 == GT_EXPR))
2603             return fold_build2 (code2, boolean_type_node, op2a, op2b);
2604           else
2605             return fold_build2 (code1, boolean_type_node, op1a, op1b);
2606         }
2607
2608       /* Check for singleton ranges.  */
2609       else if (cmp == 0
2610                && ((code1 == LT_EXPR && code2 == GT_EXPR)
2611                    || (code1 == GT_EXPR && code2 == LT_EXPR)))
2612         return fold_build2 (NE_EXPR, boolean_type_node, op1a, op2b);
2613
2614       /* Check for less/greater pairs that don't restrict the range at all.  */
2615       else if (cmp >= 0
2616                && (code1 == LT_EXPR || code1 == LE_EXPR)
2617                && (code2 == GT_EXPR || code2 == GE_EXPR))
2618         return boolean_true_node;
2619       else if (cmp <= 0
2620                && (code1 == GT_EXPR || code1 == GE_EXPR)
2621                && (code2 == LT_EXPR || code2 == LE_EXPR))
2622         return boolean_true_node;
2623     }
2624
2625   /* Perhaps the first comparison is (NAME != 0) or (NAME == 1) where
2626      NAME's definition is a truth value.  See if there are any simplifications
2627      that can be done against the NAME's definition.  */
2628   if (TREE_CODE (op1a) == SSA_NAME
2629       && (code1 == NE_EXPR || code1 == EQ_EXPR)
2630       && (integer_zerop (op1b) || integer_onep (op1b)))
2631     {
2632       bool invert = ((code1 == EQ_EXPR && integer_zerop (op1b))
2633                      || (code1 == NE_EXPR && integer_onep (op1b)));
2634       gimple stmt = SSA_NAME_DEF_STMT (op1a);
2635       switch (gimple_code (stmt))
2636         {
2637         case GIMPLE_ASSIGN:
2638           /* Try to simplify by copy-propagating the definition.  */
2639           return or_var_with_comparison (op1a, invert, code2, op2a, op2b);
2640
2641         case GIMPLE_PHI:
2642           /* If every argument to the PHI produces the same result when
2643              ORed with the second comparison, we win.
2644              Do not do this unless the type is bool since we need a bool
2645              result here anyway.  */
2646           if (TREE_CODE (TREE_TYPE (op1a)) == BOOLEAN_TYPE)
2647             {
2648               tree result = NULL_TREE;
2649               unsigned i;
2650               for (i = 0; i < gimple_phi_num_args (stmt); i++)
2651                 {
2652                   tree arg = gimple_phi_arg_def (stmt, i);
2653
2654                   /* If this PHI has itself as an argument, ignore it.
2655                      If all the other args produce the same result,
2656                      we're still OK.  */
2657                   if (arg == gimple_phi_result (stmt))
2658                     continue;
2659                   else if (TREE_CODE (arg) == INTEGER_CST)
2660                     {
2661                       if (invert ? integer_zerop (arg) : integer_nonzerop (arg))
2662                         {
2663                           if (!result)
2664                             result = boolean_true_node;
2665                           else if (!integer_onep (result))
2666                             return NULL_TREE;
2667                         }
2668                       else if (!result)
2669                         result = fold_build2 (code2, boolean_type_node,
2670                                               op2a, op2b);
2671                       else if (!same_bool_comparison_p (result,
2672                                                         code2, op2a, op2b))
2673                         return NULL_TREE;
2674                     }
2675                   else if (TREE_CODE (arg) == SSA_NAME)
2676                     {
2677                       tree temp = or_var_with_comparison (arg, invert,
2678                                                           code2, op2a, op2b);
2679                       if (!temp)
2680                         return NULL_TREE;
2681                       else if (!result)
2682                         result = temp;
2683                       else if (!same_bool_result_p (result, temp))
2684                         return NULL_TREE;
2685                     }
2686                   else
2687                     return NULL_TREE;
2688                 }
2689               return result;
2690             }
2691
2692         default:
2693           break;
2694         }
2695     }
2696   return NULL_TREE;
2697 }
2698
2699 /* Try to simplify the OR of two comparisons, specified by
2700    (OP1A CODE1 OP1B) and (OP2B CODE2 OP2B), respectively.
2701    If this can be simplified to a single expression (without requiring
2702    introducing more SSA variables to hold intermediate values),
2703    return the resulting tree.  Otherwise return NULL_TREE.
2704    If the result expression is non-null, it has boolean type.  */
2705
2706 tree
2707 maybe_fold_or_comparisons (enum tree_code code1, tree op1a, tree op1b,
2708                            enum tree_code code2, tree op2a, tree op2b)
2709 {
2710   tree t = or_comparisons_1 (code1, op1a, op1b, code2, op2a, op2b);
2711   if (t)
2712     return t;
2713   else
2714     return or_comparisons_1 (code2, op2a, op2b, code1, op1a, op1b);
2715 }