gcc/gimple-fold.c

   1 /* Statement simplification on GIMPLE.
   2    Copyright (C) 2010, 2011 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 #include "gimple-fold.h"
  34
  35 /* Return true when DECL can be referenced from current unit.
  36    We can get declarations that are not possible to reference for
  37    various reasons:
  38
  39      1) When analyzing C++ virtual tables.
  40         C++ virtual tables do have known constructors even
  41         when they are keyed to other compilation unit.
  42         Those tables can contain pointers to methods and vars
  43         in other units.  Those methods have both STATIC and EXTERNAL
  44         set.
  45      2) In WHOPR mode devirtualization might lead to reference
  46         to method that was partitioned elsehwere.
  47         In this case we have static VAR_DECL or FUNCTION_DECL
  48         that has no corresponding callgraph/varpool node
  49         declaring the body.
  50      3) COMDAT functions referred by external vtables that
  51         we devirtualize only during final copmilation stage.
  52         At this time we already decided that we will not output
  53         the function body and thus we can't reference the symbol
  54         directly.  */
  55
  56 static bool
  57 can_refer_decl_in_current_unit_p (tree decl)
  58 {
  59   struct varpool_node *vnode;
  60   struct cgraph_node *node;
  61
  62   if (!TREE_STATIC (decl) && !DECL_EXTERNAL (decl))
  63     return true;
  64   /* External flag is set, so we deal with C++ reference
  65      to static object from other file.  */
  66   if (DECL_EXTERNAL (decl) && TREE_STATIC (decl)
  67       && TREE_CODE (decl) == VAR_DECL)
  68     {
  69       /* Just be sure it is not big in frontend setting
  70          flags incorrectly.  Those variables should never
  71          be finalized.  */
  72       gcc_checking_assert (!(vnode = varpool_get_node (decl))
  73                            || !vnode->finalized);
  74       return false;
  75     }
  76   /* When function is public, we always can introduce new reference.
  77      Exception are the COMDAT functions where introducing a direct
  78      reference imply need to include function body in the curren tunit.  */
  79   if (TREE_PUBLIC (decl) && !DECL_COMDAT (decl))
  80     return true;
  81   /* We are not at ltrans stage; so don't worry about WHOPR.
  82      Also when still gimplifying all referred comdat functions will be
  83      produced.
  84      ??? as observed in PR20991 for already optimized out comdat virtual functions
  85      we may not neccesarily give up because the copy will be output elsewhere when
  86      corresponding vtable is output.  */
  87   if (!flag_ltrans && (!DECL_COMDAT (decl) || !cgraph_function_flags_ready))
  88     return true;
  89   /* If we already output the function body, we are safe.  */
  90   if (TREE_ASM_WRITTEN (decl))
  91     return true;
  92   if (TREE_CODE (decl) == FUNCTION_DECL)
  93     {
  94       node = cgraph_get_node (decl);
  95       /* Check that we still have function body and that we didn't took
  96          the decision to eliminate offline copy of the function yet.
  97          The second is important when devirtualization happens during final
  98          compilation stage when making a new reference no longer makes callee
  99          to be compiled.  */
 100       if (!node || !node->analyzed || node->global.inlined_to)
 101         return false;
 102     }
 103   else if (TREE_CODE (decl) == VAR_DECL)
 104     {
 105       vnode = varpool_get_node (decl);
 106       if (!vnode || !vnode->finalized)
 107         return false;
 108     }
 109   return true;
 110 }
 111
 112 /* CVAL is value taken from DECL_INITIAL of variable.  Try to transform it into
 113    acceptable form for is_gimple_min_invariant.   */
 114
 115 tree
 116 canonicalize_constructor_val (tree cval)
 117 {
 118   STRIP_NOPS (cval);
 119   if (TREE_CODE (cval) == POINTER_PLUS_EXPR)
 120     {
 121       tree t = maybe_fold_offset_to_address (EXPR_LOCATION (cval),
 122                                              TREE_OPERAND (cval, 0),
 123                                              TREE_OPERAND (cval, 1),
 124                                              TREE_TYPE (cval));
 125       if (t)
 126         cval = t;
 127     }
 128   if (TREE_CODE (cval) == ADDR_EXPR)
 129     {
 130       tree base = get_base_address (TREE_OPERAND (cval, 0));
 131
 132       if (base
 133           && (TREE_CODE (base) == VAR_DECL
 134               || TREE_CODE (base) == FUNCTION_DECL)
 135           && !can_refer_decl_in_current_unit_p (base))
 136         return NULL_TREE;
 137       if (cfun && base && TREE_CODE (base) == VAR_DECL)
 138         add_referenced_var (base);
 139       /* Fixup types in global initializers.  */
 140       if (TREE_TYPE (TREE_TYPE (cval)) != TREE_TYPE (TREE_OPERAND (cval, 0)))
 141         cval = build_fold_addr_expr (TREE_OPERAND (cval, 0));
 142     }
 143   return cval;
 144 }
 145
 146 /* If SYM is a constant variable with known value, return the value.
 147    NULL_TREE is returned otherwise.  */
 148
 149 tree
 150 get_symbol_constant_value (tree sym)
 151 {
 152   if (const_value_known_p (sym))
 153     {
 154       tree val = DECL_INITIAL (sym);
 155       if (val)
 156         {
 157           val = canonicalize_constructor_val (val);
 158           if (val && is_gimple_min_invariant (val))
 159             return val;
 160           else
 161             return NULL_TREE;
 162         }
 163       /* Variables declared 'const' without an initializer
 164          have zero as the initializer if they may not be
 165          overridden at link or run time.  */
 166       if (!val
 167           && (INTEGRAL_TYPE_P (TREE_TYPE (sym))
 168                || SCALAR_FLOAT_TYPE_P (TREE_TYPE (sym))))
 169         return build_zero_cst (TREE_TYPE (sym));
 170     }
 171
 172   return NULL_TREE;
 173 }
 174
 175
 176 /* Return true if we may propagate the address expression ADDR into the
 177    dereference DEREF and cancel them.  */
 178
 179 bool
 180 may_propagate_address_into_dereference (tree addr, tree deref)
 181 {
 182   gcc_assert (TREE_CODE (deref) == MEM_REF
 183               && TREE_CODE (addr) == ADDR_EXPR);
 184
 185   /* Don't propagate if ADDR's operand has incomplete type.  */
 186   if (!COMPLETE_TYPE_P (TREE_TYPE (TREE_OPERAND (addr, 0))))
 187     return false;
 188
 189   /* If the address is invariant then we do not need to preserve restrict
 190      qualifications.  But we do need to preserve volatile qualifiers until
 191      we can annotate the folded dereference itself properly.  */
 192   if (is_gimple_min_invariant (addr)
 193       && (!TREE_THIS_VOLATILE (deref)
 194           || TYPE_VOLATILE (TREE_TYPE (addr))))
 195     return useless_type_conversion_p (TREE_TYPE (deref),
 196                                       TREE_TYPE (TREE_OPERAND (addr, 0)));
 197
 198   /* Else both the address substitution and the folding must result in
 199      a valid useless type conversion sequence.  */
 200   return (useless_type_conversion_p (TREE_TYPE (TREE_OPERAND (deref, 0)),
 201                                      TREE_TYPE (addr))
 202           && useless_type_conversion_p (TREE_TYPE (deref),
 203                                         TREE_TYPE (TREE_OPERAND (addr, 0))));
 204 }
 205
 206
 207 /* A subroutine of fold_stmt.  Attempts to fold *(A+O) to A[X].
 208    BASE is an array type.  OFFSET is a byte displacement.
 209
 210    LOC is the location of the original expression.  */
 211
 212 static tree
 213 maybe_fold_offset_to_array_ref (location_t loc, tree base, tree offset)
 214 {
 215   tree min_idx, idx, idx_type, elt_offset = integer_zero_node;
 216   tree array_type, elt_type, elt_size;
 217   tree domain_type;
 218
 219   /* If BASE is an ARRAY_REF, we can pick up another offset (this time
 220      measured in units of the size of elements type) from that ARRAY_REF).
 221      We can't do anything if either is variable.
 222
 223      The case we handle here is *(&A[N]+O).  */
 224   if (TREE_CODE (base) == ARRAY_REF)
 225     {
 226       tree low_bound = array_ref_low_bound (base);
 227
 228       elt_offset = TREE_OPERAND (base, 1);
 229       if (TREE_CODE (low_bound) != INTEGER_CST
 230           || TREE_CODE (elt_offset) != INTEGER_CST)
 231         return NULL_TREE;
 232
 233       elt_offset = int_const_binop (MINUS_EXPR, elt_offset, low_bound);
 234       base = TREE_OPERAND (base, 0);
 235     }
 236
 237   /* Ignore stupid user tricks of indexing non-array variables.  */
 238   array_type = TREE_TYPE (base);
 239   if (TREE_CODE (array_type) != ARRAY_TYPE)
 240     return NULL_TREE;
 241   elt_type = TREE_TYPE (array_type);
 242
 243   /* Use signed size type for intermediate computation on the index.  */
 244   idx_type = ssizetype;
 245
 246   /* If OFFSET and ELT_OFFSET are zero, we don't care about the size of the
 247      element type (so we can use the alignment if it's not constant).
 248      Otherwise, compute the offset as an index by using a division.  If the
 249      division isn't exact, then don't do anything.  */
 250   elt_size = TYPE_SIZE_UNIT (elt_type);
 251   if (!elt_size)
 252     return NULL;
 253   if (integer_zerop (offset))
 254     {
 255       if (TREE_CODE (elt_size) != INTEGER_CST)
 256         elt_size = size_int (TYPE_ALIGN (elt_type));
 257
 258       idx = build_int_cst (idx_type, 0);
 259     }
 260   else
 261     {
 262       unsigned HOST_WIDE_INT lquo, lrem;
 263       HOST_WIDE_INT hquo, hrem;
 264       double_int soffset;
 265
 266       /* The final array offset should be signed, so we need
 267          to sign-extend the (possibly pointer) offset here
 268          and use signed division.  */
 269       soffset = double_int_sext (tree_to_double_int (offset),
 270                                  TYPE_PRECISION (TREE_TYPE (offset)));
 271       if (TREE_CODE (elt_size) != INTEGER_CST
 272           || div_and_round_double (TRUNC_DIV_EXPR, 0,
 273                                    soffset.low, soffset.high,
 274                                    TREE_INT_CST_LOW (elt_size),
 275                                    TREE_INT_CST_HIGH (elt_size),
 276                                    &lquo, &hquo, &lrem, &hrem)
 277           || lrem || hrem)
 278         return NULL_TREE;
 279
 280       idx = build_int_cst_wide (idx_type, lquo, hquo);
 281     }
 282
 283   /* Assume the low bound is zero.  If there is a domain type, get the
 284      low bound, if any, convert the index into that type, and add the
 285      low bound.  */
 286   min_idx = build_int_cst (idx_type, 0);
 287   domain_type = TYPE_DOMAIN (array_type);
 288   if (domain_type)
 289     {
 290       idx_type = domain_type;
 291       if (TYPE_MIN_VALUE (idx_type))
 292         min_idx = TYPE_MIN_VALUE (idx_type);
 293       else
 294         min_idx = fold_convert (idx_type, min_idx);
 295
 296       if (TREE_CODE (min_idx) != INTEGER_CST)
 297         return NULL_TREE;
 298
 299       elt_offset = fold_convert (idx_type, elt_offset);
 300     }
 301
 302   if (!integer_zerop (min_idx))
 303     idx = int_const_binop (PLUS_EXPR, idx, min_idx);
 304   if (!integer_zerop (elt_offset))
 305     idx = int_const_binop (PLUS_EXPR, idx, elt_offset);
 306
 307   /* Make sure to possibly truncate late after offsetting.  */
 308   idx = fold_convert (idx_type, idx);
 309
 310   /* We don't want to construct access past array bounds. For example
 311        char *(c[4]);
 312        c[3][2];
 313      should not be simplified into (*c)[14] or tree-vrp will
 314      give false warnings.
 315      This is only an issue for multi-dimensional arrays.  */
 316   if (TREE_CODE (elt_type) == ARRAY_TYPE
 317       && domain_type)
 318     {
 319       if (TYPE_MAX_VALUE (domain_type)
 320           && TREE_CODE (TYPE_MAX_VALUE (domain_type)) == INTEGER_CST
 321           && tree_int_cst_lt (TYPE_MAX_VALUE (domain_type), idx))
 322         return NULL_TREE;
 323       else if (TYPE_MIN_VALUE (domain_type)
 324                && TREE_CODE (TYPE_MIN_VALUE (domain_type)) == INTEGER_CST
 325                && tree_int_cst_lt (idx, TYPE_MIN_VALUE (domain_type)))
 326         return NULL_TREE;
 327       else if (compare_tree_int (idx, 0) < 0)
 328         return NULL_TREE;
 329     }
 330
 331   {
 332     tree t = build4 (ARRAY_REF, elt_type, base, idx, NULL_TREE, NULL_TREE);
 333     SET_EXPR_LOCATION (t, loc);
 334     return t;
 335   }
 336 }
 337
 338
 339 /* Attempt to express (ORIG_TYPE)BASE+OFFSET as BASE[index].
 340    LOC is the location of original expression.
 341
 342    Before attempting the conversion strip off existing ADDR_EXPRs.  */
 343
 344 tree
 345 maybe_fold_offset_to_reference (location_t loc, tree base, tree offset,
 346                                 tree orig_type)
 347 {
 348   tree ret;
 349
 350   STRIP_NOPS (base);
 351   if (TREE_CODE (base) != ADDR_EXPR)
 352     return NULL_TREE;
 353
 354   base = TREE_OPERAND (base, 0);
 355   if (types_compatible_p (orig_type, TREE_TYPE (base))
 356       && integer_zerop (offset))
 357     return base;
 358
 359   ret = maybe_fold_offset_to_array_ref (loc, base, offset);
 360   if (ret && types_compatible_p (orig_type, TREE_TYPE (ret)))
 361     return ret;
 362   return NULL_TREE;
 363 }
 364
 365 /* Attempt to express (ORIG_TYPE)ADDR+OFFSET as (*ADDR)[index].
 366    LOC is the location of the original expression.  */
 367
 368 tree
 369 maybe_fold_offset_to_address (location_t loc, tree addr, tree offset,
 370                               tree orig_type)
 371 {
 372   tree base, ret;
 373
 374   STRIP_NOPS (addr);
 375   if (TREE_CODE (addr) != ADDR_EXPR)
 376     return NULL_TREE;
 377   base = TREE_OPERAND (addr, 0);
 378   ret = maybe_fold_offset_to_array_ref (loc, base, offset);
 379   if (ret)
 380     {
 381       ret = build_fold_addr_expr (ret);
 382       if (!useless_type_conversion_p (orig_type, TREE_TYPE (ret)))
 383         return NULL_TREE;
 384       SET_EXPR_LOCATION (ret, loc);
 385     }
 386
 387   return ret;
 388 }
 389
 390
 391 /* A quaint feature extant in our address arithmetic is that there
 392    can be hidden type changes here.  The type of the result need
 393    not be the same as the type of the input pointer.
 394
 395    What we're after here is an expression of the form
 396         (T *)(&array + const)
 397    where array is OP0, const is OP1, RES_TYPE is T and
 398    the cast doesn't actually exist, but is implicit in the
 399    type of the POINTER_PLUS_EXPR.  We'd like to turn this into
 400         &array[x]
 401    which may be able to propagate further.  */
 402
 403 tree
 404 maybe_fold_stmt_addition (location_t loc, tree res_type, tree op0, tree op1)
 405 {
 406   tree ptd_type;
 407   tree t;
 408
 409   /* The first operand should be an ADDR_EXPR.  */
 410   if (TREE_CODE (op0) != ADDR_EXPR)
 411     return NULL_TREE;
 412   op0 = TREE_OPERAND (op0, 0);
 413
 414   /* It had better be a constant.  */
 415   if (TREE_CODE (op1) != INTEGER_CST)
 416     {
 417       /* Or op0 should now be A[0] and the non-constant offset defined
 418          via a multiplication by the array element size.  */
 419       if (TREE_CODE (op0) == ARRAY_REF
 420           /* As we will end up creating a variable index array access
 421              in the outermost array dimension make sure there isn't
 422              a more inner array that the index could overflow to.  */
 423           && TREE_CODE (TREE_OPERAND (op0, 0)) != ARRAY_REF
 424           && integer_zerop (TREE_OPERAND (op0, 1))
 425           && TREE_CODE (op1) == SSA_NAME)
 426         {
 427           gimple offset_def = SSA_NAME_DEF_STMT (op1);
 428           tree elsz = TYPE_SIZE_UNIT (TREE_TYPE (op0));
 429           if (!host_integerp (elsz, 1)
 430               || !is_gimple_assign (offset_def))
 431             return NULL_TREE;
 432
 433           /* Do not build array references of something that we can't
 434              see the true number of array dimensions for.  */
 435           if (!DECL_P (TREE_OPERAND (op0, 0))
 436               && !handled_component_p (TREE_OPERAND (op0, 0)))
 437             return NULL_TREE;
 438
 439           if (gimple_assign_rhs_code (offset_def) == MULT_EXPR
 440               && TREE_CODE (gimple_assign_rhs2 (offset_def)) == INTEGER_CST
 441               && tree_int_cst_equal (gimple_assign_rhs2 (offset_def), elsz))
 442             return build_fold_addr_expr
 443                           (build4 (ARRAY_REF, TREE_TYPE (op0),
 444                                    TREE_OPERAND (op0, 0),
 445                                    gimple_assign_rhs1 (offset_def),
 446                                    TREE_OPERAND (op0, 2),
 447                                    TREE_OPERAND (op0, 3)));
 448           else if (integer_onep (elsz)
 449                    && gimple_assign_rhs_code (offset_def) != MULT_EXPR)
 450             return build_fold_addr_expr
 451                           (build4 (ARRAY_REF, TREE_TYPE (op0),
 452                                    TREE_OPERAND (op0, 0),
 453                                    op1,
 454                                    TREE_OPERAND (op0, 2),
 455                                    TREE_OPERAND (op0, 3)));
 456         }
 457       else if (TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE
 458                /* Dto.  */
 459                && TREE_CODE (TREE_TYPE (TREE_TYPE (op0))) != ARRAY_TYPE
 460                && TREE_CODE (op1) == SSA_NAME)
 461         {
 462           gimple offset_def = SSA_NAME_DEF_STMT (op1);
 463           tree elsz = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (op0)));
 464           if (!host_integerp (elsz, 1)
 465               || !is_gimple_assign (offset_def))
 466             return NULL_TREE;
 467
 468           /* Do not build array references of something that we can't
 469              see the true number of array dimensions for.  */
 470           if (!DECL_P (op0)
 471               && !handled_component_p (op0))
 472             return NULL_TREE;
 473
 474           if (gimple_assign_rhs_code (offset_def) == MULT_EXPR
 475               && TREE_CODE (gimple_assign_rhs2 (offset_def)) == INTEGER_CST
 476               && tree_int_cst_equal (gimple_assign_rhs2 (offset_def), elsz))
 477             return build_fold_addr_expr
 478                           (build4 (ARRAY_REF, TREE_TYPE (TREE_TYPE (op0)),
 479                                    op0, gimple_assign_rhs1 (offset_def),
 480                                    integer_zero_node, NULL_TREE));
 481           else if (integer_onep (elsz)
 482                    && gimple_assign_rhs_code (offset_def) != MULT_EXPR)
 483             return build_fold_addr_expr
 484                           (build4 (ARRAY_REF, TREE_TYPE (TREE_TYPE (op0)),
 485                                    op0, op1,
 486                                    integer_zero_node, NULL_TREE));
 487         }
 488
 489       return NULL_TREE;
 490     }
 491
 492   /* If the first operand is an ARRAY_REF, expand it so that we can fold
 493      the offset into it.  */
 494   while (TREE_CODE (op0) == ARRAY_REF)
 495     {
 496       tree array_obj = TREE_OPERAND (op0, 0);
 497       tree array_idx = TREE_OPERAND (op0, 1);
 498       tree elt_type = TREE_TYPE (op0);
 499       tree elt_size = TYPE_SIZE_UNIT (elt_type);
 500       tree min_idx;
 501
 502       if (TREE_CODE (array_idx) != INTEGER_CST)
 503         break;
 504       if (TREE_CODE (elt_size) != INTEGER_CST)
 505         break;
 506
 507       /* Un-bias the index by the min index of the array type.  */
 508       min_idx = TYPE_DOMAIN (TREE_TYPE (array_obj));
 509       if (min_idx)
 510         {
 511           min_idx = TYPE_MIN_VALUE (min_idx);
 512           if (min_idx)
 513             {
 514               if (TREE_CODE (min_idx) != INTEGER_CST)
 515                 break;
 516
 517               array_idx = fold_convert (TREE_TYPE (min_idx), array_idx);
 518               if (!integer_zerop (min_idx))
 519                 array_idx = int_const_binop (MINUS_EXPR, array_idx,
 520                                              min_idx);
 521             }
 522         }
 523
 524       /* Convert the index to a byte offset.  */
 525       array_idx = fold_convert (sizetype, array_idx);
 526       array_idx = int_const_binop (MULT_EXPR, array_idx, elt_size);
 527
 528       /* Update the operands for the next round, or for folding.  */
 529       op1 = int_const_binop (PLUS_EXPR,
 530                              array_idx, op1);
 531       op0 = array_obj;
 532     }
 533
 534   ptd_type = TREE_TYPE (res_type);
 535   /* If we want a pointer to void, reconstruct the reference from the
 536      array element type.  A pointer to that can be trivially converted
 537      to void *.  This happens as we fold (void *)(ptr p+ off).  */
 538   if (VOID_TYPE_P (ptd_type)
 539       && TREE_CODE (TREE_TYPE (op0)) == ARRAY_TYPE)
 540     ptd_type = TREE_TYPE (TREE_TYPE (op0));
 541
 542   /* At which point we can try some of the same things as for indirects.  */
 543   t = maybe_fold_offset_to_array_ref (loc, op0, op1);
 544   if (t)
 545     {
 546       t = build_fold_addr_expr (t);
 547       if (!useless_type_conversion_p (res_type, TREE_TYPE (t)))
 548         return NULL_TREE;
 549       SET_EXPR_LOCATION (t, loc);
 550     }
 551
 552   return t;
 553 }
 554
 555 /* Subroutine of fold_stmt.  We perform several simplifications of the
 556    memory reference tree EXPR and make sure to re-gimplify them properly
 557    after propagation of constant addresses.  IS_LHS is true if the
 558    reference is supposed to be an lvalue.  */
 559
 560 static tree
 561 maybe_fold_reference (tree expr, bool is_lhs)
 562 {
 563   tree *t = &expr;
 564   tree result;
 565
 566   if ((TREE_CODE (expr) == VIEW_CONVERT_EXPR
 567        || TREE_CODE (expr) == REALPART_EXPR
 568        || TREE_CODE (expr) == IMAGPART_EXPR)
 569       && CONSTANT_CLASS_P (TREE_OPERAND (expr, 0)))
 570     return fold_unary_loc (EXPR_LOCATION (expr),
 571                            TREE_CODE (expr),
 572                            TREE_TYPE (expr),
 573                            TREE_OPERAND (expr, 0));
 574   else if (TREE_CODE (expr) == BIT_FIELD_REF
 575            && CONSTANT_CLASS_P (TREE_OPERAND (expr, 0)))
 576     return fold_ternary_loc (EXPR_LOCATION (expr),
 577                              TREE_CODE (expr),
 578                              TREE_TYPE (expr),
 579                              TREE_OPERAND (expr, 0),
 580                              TREE_OPERAND (expr, 1),
 581                              TREE_OPERAND (expr, 2));
 582
 583   while (handled_component_p (*t))
 584     t = &TREE_OPERAND (*t, 0);
 585
 586   /* Canonicalize MEM_REFs invariant address operand.  Do this first
 587      to avoid feeding non-canonical MEM_REFs elsewhere.  */
 588   if (TREE_CODE (*t) == MEM_REF
 589       && !is_gimple_mem_ref_addr (TREE_OPERAND (*t, 0)))
 590     {
 591       bool volatile_p = TREE_THIS_VOLATILE (*t);
 592       tree tem = fold_binary (MEM_REF, TREE_TYPE (*t),
 593                               TREE_OPERAND (*t, 0),
 594                               TREE_OPERAND (*t, 1));
 595       if (tem)
 596         {
 597           TREE_THIS_VOLATILE (tem) = volatile_p;
 598           *t = tem;
 599           tem = maybe_fold_reference (expr, is_lhs);
 600           if (tem)
 601             return tem;
 602           return expr;
 603         }
 604     }
 605
 606   if (!is_lhs
 607       && (result = fold_const_aggregate_ref (expr))
 608       && is_gimple_min_invariant (result))
 609     return result;
 610
 611   /* Fold back MEM_REFs to reference trees.  */
 612   if (TREE_CODE (*t) == MEM_REF
 613       && TREE_CODE (TREE_OPERAND (*t, 0)) == ADDR_EXPR
 614       && integer_zerop (TREE_OPERAND (*t, 1))
 615       && (TREE_THIS_VOLATILE (*t)
 616           == TREE_THIS_VOLATILE (TREE_OPERAND (TREE_OPERAND (*t, 0), 0)))
 617       && !TYPE_REF_CAN_ALIAS_ALL (TREE_TYPE (TREE_OPERAND (*t, 1)))
 618       && (TYPE_MAIN_VARIANT (TREE_TYPE (*t))
 619           == TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (TREE_OPERAND (*t, 1)))))
 620       /* We have to look out here to not drop a required conversion
 621          from the rhs to the lhs if is_lhs, but we don't have the
 622          rhs here to verify that.  Thus require strict type
 623          compatibility.  */
 624       && types_compatible_p (TREE_TYPE (*t),
 625                              TREE_TYPE (TREE_OPERAND
 626                                         (TREE_OPERAND (*t, 0), 0))))
 627     {
 628       tree tem;
 629       *t = TREE_OPERAND (TREE_OPERAND (*t, 0), 0);
 630       tem = maybe_fold_reference (expr, is_lhs);
 631       if (tem)
 632         return tem;
 633       return expr;
 634     }
 635   else if (TREE_CODE (*t) == TARGET_MEM_REF)
 636     {
 637       tree tem = maybe_fold_tmr (*t);
 638       if (tem)
 639         {
 640           *t = tem;
 641           tem = maybe_fold_reference (expr, is_lhs);
 642           if (tem)
 643             return tem;
 644           return expr;
 645         }
 646     }
 647
 648   return NULL_TREE;
 649 }
 650
 651
 652 /* Attempt to fold an assignment statement pointed-to by SI.  Returns a
 653    replacement rhs for the statement or NULL_TREE if no simplification
 654    could be made.  It is assumed that the operands have been previously
 655    folded.  */
 656
 657 static tree
 658 fold_gimple_assign (gimple_stmt_iterator *si)
 659 {
 660   gimple stmt = gsi_stmt (*si);
 661   enum tree_code subcode = gimple_assign_rhs_code (stmt);
 662   location_t loc = gimple_location (stmt);
 663
 664   tree result = NULL_TREE;
 665
 666   switch (get_gimple_rhs_class (subcode))
 667     {
 668     case GIMPLE_SINGLE_RHS:
 669       {
 670         tree rhs = gimple_assign_rhs1 (stmt);
 671
 672         /* Try to fold a conditional expression.  */
 673         if (TREE_CODE (rhs) == COND_EXPR)
 674           {
 675             tree op0 = COND_EXPR_COND (rhs);
 676             tree tem;
 677             bool set = false;
 678             location_t cond_loc = EXPR_LOCATION (rhs);
 679
 680             if (COMPARISON_CLASS_P (op0))
 681               {
 682                 fold_defer_overflow_warnings ();
 683                 tem = fold_binary_loc (cond_loc,
 684                                    TREE_CODE (op0), TREE_TYPE (op0),
 685                                    TREE_OPERAND (op0, 0),
 686                                    TREE_OPERAND (op0, 1));
 687                 /* This is actually a conditional expression, not a GIMPLE
 688                    conditional statement, however, the valid_gimple_rhs_p
 689                    test still applies.  */
 690                 set = (tem && is_gimple_condexpr (tem)
 691                        && valid_gimple_rhs_p (tem));
 692                 fold_undefer_overflow_warnings (set, stmt, 0);
 693               }
 694             else if (is_gimple_min_invariant (op0))
 695               {
 696                 tem = op0;
 697                 set = true;
 698               }
 699             else
 700               return NULL_TREE;
 701
 702             if (set)
 703               result = fold_build3_loc (cond_loc, COND_EXPR, TREE_TYPE (rhs), tem,
 704                                     COND_EXPR_THEN (rhs), COND_EXPR_ELSE (rhs));
 705           }
 706
 707         else if (REFERENCE_CLASS_P (rhs))
 708           return maybe_fold_reference (rhs, false);
 709
 710         else if (TREE_CODE (rhs) == ADDR_EXPR)
 711           {
 712             tree ref = TREE_OPERAND (rhs, 0);
 713             tree tem = maybe_fold_reference (ref, true);
 714             if (tem
 715                 && TREE_CODE (tem) == MEM_REF
 716                 && integer_zerop (TREE_OPERAND (tem, 1)))
 717               result = fold_convert (TREE_TYPE (rhs), TREE_OPERAND (tem, 0));
 718             else if (tem)
 719               result = fold_convert (TREE_TYPE (rhs),
 720                                      build_fold_addr_expr_loc (loc, tem));
 721             else if (TREE_CODE (ref) == MEM_REF
 722                      && integer_zerop (TREE_OPERAND (ref, 1)))
 723               result = fold_convert (TREE_TYPE (rhs), TREE_OPERAND (ref, 0));
 724           }
 725
 726         else if (TREE_CODE (rhs) == CONSTRUCTOR
 727                  && TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE
 728                  && (CONSTRUCTOR_NELTS (rhs)
 729                      == TYPE_VECTOR_SUBPARTS (TREE_TYPE (rhs))))
 730           {
 731             /* Fold a constant vector CONSTRUCTOR to VECTOR_CST.  */
 732             unsigned i;
 733             tree val;
 734
 735             FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs), i, val)
 736               if (TREE_CODE (val) != INTEGER_CST
 737                   && TREE_CODE (val) != REAL_CST
 738                   && TREE_CODE (val) != FIXED_CST)
 739                 return NULL_TREE;
 740
 741             return build_vector_from_ctor (TREE_TYPE (rhs),
 742                                            CONSTRUCTOR_ELTS (rhs));
 743           }
 744
 745         else if (DECL_P (rhs))
 746           return unshare_expr (get_symbol_constant_value (rhs));
 747
 748         /* If we couldn't fold the RHS, hand over to the generic
 749            fold routines.  */
 750         if (result == NULL_TREE)
 751           result = fold (rhs);
 752
 753         /* Strip away useless type conversions.  Both the NON_LVALUE_EXPR
 754            that may have been added by fold, and "useless" type
 755            conversions that might now be apparent due to propagation.  */
 756         STRIP_USELESS_TYPE_CONVERSION (result);
 757
 758         if (result != rhs && valid_gimple_rhs_p (result))
 759           return result;
 760
 761         return NULL_TREE;
 762       }
 763       break;
 764
 765     case GIMPLE_UNARY_RHS:
 766       {
 767         tree rhs = gimple_assign_rhs1 (stmt);
 768
 769         result = fold_unary_loc (loc, subcode, gimple_expr_type (stmt), rhs);
 770         if (result)
 771           {
 772             /* If the operation was a conversion do _not_ mark a
 773                resulting constant with TREE_OVERFLOW if the original
 774                constant was not.  These conversions have implementation
 775                defined behavior and retaining the TREE_OVERFLOW flag
 776                here would confuse later passes such as VRP.  */
 777             if (CONVERT_EXPR_CODE_P (subcode)
 778                 && TREE_CODE (result) == INTEGER_CST
 779                 && TREE_CODE (rhs) == INTEGER_CST)
 780               TREE_OVERFLOW (result) = TREE_OVERFLOW (rhs);
 781
 782             STRIP_USELESS_TYPE_CONVERSION (result);
 783             if (valid_gimple_rhs_p (result))
 784               return result;
 785           }
 786         else if (CONVERT_EXPR_CODE_P (subcode)
 787                  && POINTER_TYPE_P (gimple_expr_type (stmt))
 788                  && POINTER_TYPE_P (TREE_TYPE (gimple_assign_rhs1 (stmt))))
 789           {
 790             tree type = gimple_expr_type (stmt);
 791             tree t = maybe_fold_offset_to_address (loc,
 792                                                    gimple_assign_rhs1 (stmt),
 793                                                    integer_zero_node, type);
 794             if (t)
 795               return t;
 796           }
 797       }
 798       break;
 799
 800     case GIMPLE_BINARY_RHS:
 801       /* Try to fold pointer addition.  */
 802       if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR)
 803         {
 804           tree type = TREE_TYPE (gimple_assign_rhs1 (stmt));
 805           if (TREE_CODE (TREE_TYPE (type)) == ARRAY_TYPE)
 806             {
 807               type = build_pointer_type (TREE_TYPE (TREE_TYPE (type)));
 808               if (!useless_type_conversion_p
 809                     (TREE_TYPE (gimple_assign_lhs (stmt)), type))
 810                 type = TREE_TYPE (gimple_assign_rhs1 (stmt));
 811             }
 812           result = maybe_fold_stmt_addition (gimple_location (stmt),
 813                                              type,
 814                                              gimple_assign_rhs1 (stmt),
 815                                              gimple_assign_rhs2 (stmt));
 816         }
 817
 818       if (!result)
 819         result = fold_binary_loc (loc, subcode,
 820                               TREE_TYPE (gimple_assign_lhs (stmt)),
 821                               gimple_assign_rhs1 (stmt),
 822                               gimple_assign_rhs2 (stmt));
 823
 824       if (result)
 825         {
 826           STRIP_USELESS_TYPE_CONVERSION (result);
 827           if (valid_gimple_rhs_p (result))
 828             return result;
 829
 830           /* Fold might have produced non-GIMPLE, so if we trust it blindly
 831              we lose canonicalization opportunities.  Do not go again
 832              through fold here though, or the same non-GIMPLE will be
 833              produced.  */
 834           if (commutative_tree_code (subcode)
 835               && tree_swap_operands_p (gimple_assign_rhs1 (stmt),
 836                                        gimple_assign_rhs2 (stmt), false))
 837             return build2 (subcode, TREE_TYPE (gimple_assign_lhs (stmt)),
 838                            gimple_assign_rhs2 (stmt),
 839                            gimple_assign_rhs1 (stmt));
 840         }
 841       break;
 842
 843     case GIMPLE_TERNARY_RHS:
 844       result = fold_ternary_loc (loc, subcode,
 845                                  TREE_TYPE (gimple_assign_lhs (stmt)),
 846                                  gimple_assign_rhs1 (stmt),
 847                                  gimple_assign_rhs2 (stmt),
 848                                  gimple_assign_rhs3 (stmt));
 849
 850       if (result)
 851         {
 852           STRIP_USELESS_TYPE_CONVERSION (result);
 853           if (valid_gimple_rhs_p (result))
 854             return result;
 855
 856           /* Fold might have produced non-GIMPLE, so if we trust it blindly
 857              we lose canonicalization opportunities.  Do not go again
 858              through fold here though, or the same non-GIMPLE will be
 859              produced.  */
 860           if (commutative_ternary_tree_code (subcode)
 861               && tree_swap_operands_p (gimple_assign_rhs1 (stmt),
 862                                        gimple_assign_rhs2 (stmt), false))
 863             return build3 (subcode, TREE_TYPE (gimple_assign_lhs (stmt)),
 864                            gimple_assign_rhs2 (stmt),
 865                            gimple_assign_rhs1 (stmt),
 866                            gimple_assign_rhs3 (stmt));
 867         }
 868       break;
 869
 870     case GIMPLE_INVALID_RHS:
 871       gcc_unreachable ();
 872     }
 873
 874   return NULL_TREE;
 875 }
 876
 877 /* Attempt to fold a conditional statement. Return true if any changes were
 878    made. We only attempt to fold the condition expression, and do not perform
 879    any transformation that would require alteration of the cfg.  It is
 880    assumed that the operands have been previously folded.  */
 881
 882 static bool
 883 fold_gimple_cond (gimple stmt)
 884 {
 885   tree result = fold_binary_loc (gimple_location (stmt),
 886                              gimple_cond_code (stmt),
 887                              boolean_type_node,
 888                              gimple_cond_lhs (stmt),
 889                              gimple_cond_rhs (stmt));
 890
 891   if (result)
 892     {
 893       STRIP_USELESS_TYPE_CONVERSION (result);
 894       if (is_gimple_condexpr (result) && valid_gimple_rhs_p (result))
 895         {
 896           gimple_cond_set_condition_from_tree (stmt, result);
 897           return true;
 898         }
 899     }
 900
 901   return false;
 902 }
 903
 904 /* Convert EXPR into a GIMPLE value suitable for substitution on the
 905    RHS of an assignment.  Insert the necessary statements before
 906    iterator *SI_P.  The statement at *SI_P, which must be a GIMPLE_CALL
 907    is replaced.  If the call is expected to produces a result, then it
 908    is replaced by an assignment of the new RHS to the result variable.
 909    If the result is to be ignored, then the call is replaced by a
 910    GIMPLE_NOP.  A proper VDEF chain is retained by making the first
 911    VUSE and the last VDEF of the whole sequence be the same as the replaced
 912    statement and using new SSA names for stores in between.  */
 913
 914 void
 915 gimplify_and_update_call_from_tree (gimple_stmt_iterator *si_p, tree expr)
 916 {
 917   tree lhs;
 918   tree tmp = NULL_TREE;  /* Silence warning.  */
 919   gimple stmt, new_stmt;
 920   gimple_stmt_iterator i;
 921   gimple_seq stmts = gimple_seq_alloc();
 922   struct gimplify_ctx gctx;
 923   gimple last = NULL;
 924   gimple laststore = NULL;
 925   tree reaching_vuse;
 926
 927   stmt = gsi_stmt (*si_p);
 928
 929   gcc_assert (is_gimple_call (stmt));
 930
 931   lhs = gimple_call_lhs (stmt);
 932   reaching_vuse = gimple_vuse (stmt);
 933
 934   push_gimplify_context (&gctx);
 935
 936   if (lhs == NULL_TREE)
 937     {
 938       gimplify_and_add (expr, &stmts);
 939       /* We can end up with folding a memcpy of an empty class assignment
 940          which gets optimized away by C++ gimplification.  */
 941       if (gimple_seq_empty_p (stmts))
 942         {
 943           pop_gimplify_context (NULL);
 944           if (gimple_in_ssa_p (cfun))
 945             {
 946               unlink_stmt_vdef (stmt);
 947               release_defs (stmt);
 948             }
 949           gsi_remove (si_p, true);
 950           return;
 951         }
 952     }
 953   else
 954     tmp = get_initialized_tmp_var (expr, &stmts, NULL);
 955
 956   pop_gimplify_context (NULL);
 957
 958   if (gimple_has_location (stmt))
 959     annotate_all_with_location (stmts, gimple_location (stmt));
 960
 961   /* The replacement can expose previously unreferenced variables.  */
 962   for (i = gsi_start (stmts); !gsi_end_p (i); gsi_next (&i))
 963     {
 964       if (last)
 965         {
 966           gsi_insert_before (si_p, last, GSI_NEW_STMT);
 967           gsi_next (si_p);
 968         }
 969       new_stmt = gsi_stmt (i);
 970       if (gimple_in_ssa_p (cfun))
 971         {
 972           find_new_referenced_vars (new_stmt);
 973           mark_symbols_for_renaming (new_stmt);
 974         }
 975       /* If the new statement has a VUSE, update it with exact SSA name we
 976          know will reach this one.  */
 977       if (gimple_vuse (new_stmt))
 978         {
 979           /* If we've also seen a previous store create a new VDEF for
 980              the latter one, and make that the new reaching VUSE.  */
 981           if (laststore)
 982             {
 983               reaching_vuse = make_ssa_name (gimple_vop (cfun), laststore);
 984               gimple_set_vdef (laststore, reaching_vuse);
 985               update_stmt (laststore);
 986               laststore = NULL;
 987             }
 988           gimple_set_vuse (new_stmt, reaching_vuse);
 989           gimple_set_modified (new_stmt, true);
 990         }
 991       if (gimple_assign_single_p (new_stmt)
 992           && !is_gimple_reg (gimple_assign_lhs (new_stmt)))
 993         {
 994           laststore = new_stmt;
 995         }
 996       last = new_stmt;
 997     }
 998
 999   if (lhs == NULL_TREE)
1000     {
1001       /* If we replace a call without LHS that has a VDEF and our new
1002          sequence ends with a store we must make that store have the same
1003          vdef in order not to break the sequencing.  This can happen
1004          for instance when folding memcpy calls into assignments.  */
1005       if (gimple_vdef (stmt) && laststore)
1006         {
1007           gimple_set_vdef (laststore, gimple_vdef (stmt));
1008           if (TREE_CODE (gimple_vdef (stmt)) == SSA_NAME)
1009             SSA_NAME_DEF_STMT (gimple_vdef (stmt)) = laststore;
1010           update_stmt (laststore);
1011         }
1012       else if (gimple_in_ssa_p (cfun))
1013         {
1014           unlink_stmt_vdef (stmt);
1015           release_defs (stmt);
1016         }
1017       new_stmt = last;
1018     }
1019   else
1020     {
1021       if (last)
1022         {
1023           gsi_insert_before (si_p, last, GSI_NEW_STMT);
1024           gsi_next (si_p);
1025         }
1026       if (laststore && is_gimple_reg (lhs))
1027         {
1028           gimple_set_vdef (laststore, gimple_vdef (stmt));
1029           update_stmt (laststore);
1030           if (TREE_CODE (gimple_vdef (stmt)) == SSA_NAME)
1031             SSA_NAME_DEF_STMT (gimple_vdef (stmt)) = laststore;
1032           laststore = NULL;
1033         }
1034       else if (laststore)
1035         {
1036           reaching_vuse = make_ssa_name (gimple_vop (cfun), laststore);
1037           gimple_set_vdef (laststore, reaching_vuse);
1038           update_stmt (laststore);
1039           laststore = NULL;
1040         }
1041       new_stmt = gimple_build_assign (lhs, tmp);
1042       if (!is_gimple_reg (tmp))
1043         gimple_set_vuse (new_stmt, reaching_vuse);
1044       if (!is_gimple_reg (lhs))
1045         {
1046           gimple_set_vdef (new_stmt, gimple_vdef (stmt));
1047           if (TREE_CODE (gimple_vdef (stmt)) == SSA_NAME)
1048             SSA_NAME_DEF_STMT (gimple_vdef (stmt)) = new_stmt;
1049         }
1050       else if (reaching_vuse == gimple_vuse (stmt))
1051         unlink_stmt_vdef (stmt);
1052     }
1053
1054   gimple_set_location (new_stmt, gimple_location (stmt));
1055   gsi_replace (si_p, new_stmt, false);
1056 }
1057
1058 /* Return the string length, maximum string length or maximum value of
1059    ARG in LENGTH.
1060    If ARG is an SSA name variable, follow its use-def chains.  If LENGTH
1061    is not NULL and, for TYPE == 0, its value is not equal to the length
1062    we determine or if we are unable to determine the length or value,
1063    return false.  VISITED is a bitmap of visited variables.
1064    TYPE is 0 if string length should be returned, 1 for maximum string
1065    length and 2 for maximum value ARG can have.  */
1066
1067 static bool
1068 get_maxval_strlen (tree arg, tree *length, bitmap visited, int type)
1069 {
1070   tree var, val;
1071   gimple def_stmt;
1072
1073   if (TREE_CODE (arg) != SSA_NAME)
1074     {
1075       if (TREE_CODE (arg) == COND_EXPR)
1076         return get_maxval_strlen (COND_EXPR_THEN (arg), length, visited, type)
1077                && get_maxval_strlen (COND_EXPR_ELSE (arg), length, visited, type);
1078       /* We can end up with &(*iftmp_1)[0] here as well, so handle it.  */
1079       else if (TREE_CODE (arg) == ADDR_EXPR
1080                && TREE_CODE (TREE_OPERAND (arg, 0)) == ARRAY_REF
1081                && integer_zerop (TREE_OPERAND (TREE_OPERAND (arg, 0), 1)))
1082         {
1083           tree aop0 = TREE_OPERAND (TREE_OPERAND (arg, 0), 0);
1084           if (TREE_CODE (aop0) == INDIRECT_REF
1085               && TREE_CODE (TREE_OPERAND (aop0, 0)) == SSA_NAME)
1086             return get_maxval_strlen (TREE_OPERAND (aop0, 0),
1087                                       length, visited, type);
1088         }
1089
1090       if (type == 2)
1091         {
1092           val = arg;
1093           if (TREE_CODE (val) != INTEGER_CST
1094               || tree_int_cst_sgn (val) < 0)
1095             return false;
1096         }
1097       else
1098         val = c_strlen (arg, 1);
1099       if (!val)
1100         return false;
1101
1102       if (*length)
1103         {
1104           if (type > 0)
1105             {
1106               if (TREE_CODE (*length) != INTEGER_CST
1107                   || TREE_CODE (val) != INTEGER_CST)
1108                 return false;
1109
1110               if (tree_int_cst_lt (*length, val))
1111                 *length = val;
1112               return true;
1113             }
1114           else if (simple_cst_equal (val, *length) != 1)
1115             return false;
1116         }
1117
1118       *length = val;
1119       return true;
1120     }
1121
1122   /* If we were already here, break the infinite cycle.  */
1123   if (!bitmap_set_bit (visited, SSA_NAME_VERSION (arg)))
1124     return true;
1125
1126   var = arg;
1127   def_stmt = SSA_NAME_DEF_STMT (var);
1128
1129   switch (gimple_code (def_stmt))
1130     {
1131       case GIMPLE_ASSIGN:
1132         /* The RHS of the statement defining VAR must either have a
1133            constant length or come from another SSA_NAME with a constant
1134            length.  */
1135         if (gimple_assign_single_p (def_stmt)
1136             || gimple_assign_unary_nop_p (def_stmt))
1137           {
1138             tree rhs = gimple_assign_rhs1 (def_stmt);
1139             return get_maxval_strlen (rhs, length, visited, type);
1140           }
1141         return false;
1142
1143       case GIMPLE_PHI:
1144         {
1145           /* All the arguments of the PHI node must have the same constant
1146              length.  */
1147           unsigned i;
1148
1149           for (i = 0; i < gimple_phi_num_args (def_stmt); i++)
1150           {
1151             tree arg = gimple_phi_arg (def_stmt, i)->def;
1152
1153             /* If this PHI has itself as an argument, we cannot
1154                determine the string length of this argument.  However,
1155                if we can find a constant string length for the other
1156                PHI args then we can still be sure that this is a
1157                constant string length.  So be optimistic and just
1158                continue with the next argument.  */
1159             if (arg == gimple_phi_result (def_stmt))
1160               continue;
1161
1162             if (!get_maxval_strlen (arg, length, visited, type))
1163               return false;
1164           }
1165         }
1166         return true;
1167
1168       default:
1169         return false;
1170     }
1171 }
1172
1173
1174 /* Fold builtin call in statement STMT.  Returns a simplified tree.
1175    We may return a non-constant expression, including another call
1176    to a different function and with different arguments, e.g.,
1177    substituting memcpy for strcpy when the string length is known.
1178    Note that some builtins expand into inline code that may not
1179    be valid in GIMPLE.  Callers must take care.  */
1180
1181 tree
1182 gimple_fold_builtin (gimple stmt)
1183 {
1184   tree result, val[3];
1185   tree callee, a;
1186   int arg_idx, type;
1187   bitmap visited;
1188   bool ignore;
1189   int nargs;
1190   location_t loc = gimple_location (stmt);
1191
1192   gcc_assert (is_gimple_call (stmt));
1193
1194   ignore = (gimple_call_lhs (stmt) == NULL);
1195
1196   /* First try the generic builtin folder.  If that succeeds, return the
1197      result directly.  */
1198   result = fold_call_stmt (stmt, ignore);
1199   if (result)
1200     {
1201       if (ignore)
1202         STRIP_NOPS (result);
1203       return result;
1204     }
1205
1206   /* Ignore MD builtins.  */
1207   callee = gimple_call_fndecl (stmt);
1208   if (DECL_BUILT_IN_CLASS (callee) == BUILT_IN_MD)
1209     return NULL_TREE;
1210
1211   /* If the builtin could not be folded, and it has no argument list,
1212      we're done.  */
1213   nargs = gimple_call_num_args (stmt);
1214   if (nargs == 0)
1215     return NULL_TREE;
1216
1217   /* Limit the work only for builtins we know how to simplify.  */
1218   switch (DECL_FUNCTION_CODE (callee))
1219     {
1220     case BUILT_IN_STRLEN:
1221     case BUILT_IN_FPUTS:
1222     case BUILT_IN_FPUTS_UNLOCKED:
1223       arg_idx = 0;
1224       type = 0;
1225       break;
1226     case BUILT_IN_STRCPY:
1227     case BUILT_IN_STRNCPY:
1228       arg_idx = 1;
1229       type = 0;
1230       break;
1231     case BUILT_IN_MEMCPY_CHK:
1232     case BUILT_IN_MEMPCPY_CHK:
1233     case BUILT_IN_MEMMOVE_CHK:
1234     case BUILT_IN_MEMSET_CHK:
1235     case BUILT_IN_STRNCPY_CHK:
1236       arg_idx = 2;
1237       type = 2;
1238       break;
1239     case BUILT_IN_STRCPY_CHK:
1240     case BUILT_IN_STPCPY_CHK:
1241       arg_idx = 1;
1242       type = 1;
1243       break;
1244     case BUILT_IN_SNPRINTF_CHK:
1245     case BUILT_IN_VSNPRINTF_CHK:
1246       arg_idx = 1;
1247       type = 2;
1248       break;
1249     default:
1250       return NULL_TREE;
1251     }
1252
1253   if (arg_idx >= nargs)
1254     return NULL_TREE;
1255
1256   /* Try to use the dataflow information gathered by the CCP process.  */
1257   visited = BITMAP_ALLOC (NULL);
1258   bitmap_clear (visited);
1259
1260   memset (val, 0, sizeof (val));
1261   a = gimple_call_arg (stmt, arg_idx);
1262   if (!get_maxval_strlen (a, &val[arg_idx], visited, type))
1263     val[arg_idx] = NULL_TREE;
1264
1265   BITMAP_FREE (visited);
1266
1267   result = NULL_TREE;
1268   switch (DECL_FUNCTION_CODE (callee))
1269     {
1270     case BUILT_IN_STRLEN:
1271       if (val[0] && nargs == 1)
1272         {
1273           tree new_val =
1274               fold_convert (TREE_TYPE (gimple_call_lhs (stmt)), val[0]);
1275
1276           /* If the result is not a valid gimple value, or not a cast
1277              of a valid gimple value, then we cannot use the result.  */
1278           if (is_gimple_val (new_val)
1279               || (CONVERT_EXPR_P (new_val)
1280                   && is_gimple_val (TREE_OPERAND (new_val, 0))))
1281             return new_val;
1282         }
1283       break;
1284
1285     case BUILT_IN_STRCPY:
1286       if (val[1] && is_gimple_val (val[1]) && nargs == 2)
1287         result = fold_builtin_strcpy (loc, callee,
1288                                       gimple_call_arg (stmt, 0),
1289                                       gimple_call_arg (stmt, 1),
1290                                       val[1]);
1291       break;
1292
1293     case BUILT_IN_STRNCPY:
1294       if (val[1] && is_gimple_val (val[1]) && nargs == 3)
1295         result = fold_builtin_strncpy (loc, callee,
1296                                        gimple_call_arg (stmt, 0),
1297                                        gimple_call_arg (stmt, 1),
1298                                        gimple_call_arg (stmt, 2),
1299                                        val[1]);
1300       break;
1301
1302     case BUILT_IN_FPUTS:
1303       if (nargs == 2)
1304         result = fold_builtin_fputs (loc, gimple_call_arg (stmt, 0),
1305                                      gimple_call_arg (stmt, 1),
1306                                      ignore, false, val[0]);
1307       break;
1308
1309     case BUILT_IN_FPUTS_UNLOCKED:
1310       if (nargs == 2)
1311         result = fold_builtin_fputs (loc, gimple_call_arg (stmt, 0),
1312                                      gimple_call_arg (stmt, 1),
1313                                      ignore, true, val[0]);
1314       break;
1315
1316     case BUILT_IN_MEMCPY_CHK:
1317     case BUILT_IN_MEMPCPY_CHK:
1318     case BUILT_IN_MEMMOVE_CHK:
1319     case BUILT_IN_MEMSET_CHK:
1320       if (val[2] && is_gimple_val (val[2]) && nargs == 4)
1321         result = fold_builtin_memory_chk (loc, callee,
1322                                           gimple_call_arg (stmt, 0),
1323                                           gimple_call_arg (stmt, 1),
1324                                           gimple_call_arg (stmt, 2),
1325                                           gimple_call_arg (stmt, 3),
1326                                           val[2], ignore,
1327                                           DECL_FUNCTION_CODE (callee));
1328       break;
1329
1330     case BUILT_IN_STRCPY_CHK:
1331     case BUILT_IN_STPCPY_CHK:
1332       if (val[1] && is_gimple_val (val[1]) && nargs == 3)
1333         result = fold_builtin_stxcpy_chk (loc, callee,
1334                                           gimple_call_arg (stmt, 0),
1335                                           gimple_call_arg (stmt, 1),
1336                                           gimple_call_arg (stmt, 2),
1337                                           val[1], ignore,
1338                                           DECL_FUNCTION_CODE (callee));
1339       break;
1340
1341     case BUILT_IN_STRNCPY_CHK:
1342       if (val[2] && is_gimple_val (val[2]) && nargs == 4)
1343         result = fold_builtin_strncpy_chk (loc, gimple_call_arg (stmt, 0),
1344                                            gimple_call_arg (stmt, 1),
1345                                            gimple_call_arg (stmt, 2),
1346                                            gimple_call_arg (stmt, 3),
1347                                            val[2]);
1348       break;
1349
1350     case BUILT_IN_SNPRINTF_CHK:
1351     case BUILT_IN_VSNPRINTF_CHK:
1352       if (val[1] && is_gimple_val (val[1]))
1353         result = gimple_fold_builtin_snprintf_chk (stmt, val[1],
1354                                                    DECL_FUNCTION_CODE (callee));
1355       break;
1356
1357     default:
1358       gcc_unreachable ();
1359     }
1360
1361   if (result && ignore)
1362     result = fold_ignored_result (result);
1363   return result;
1364 }
1365
1366 /* Return a declaration of a function which an OBJ_TYPE_REF references. TOKEN
1367    is integer form of OBJ_TYPE_REF_TOKEN of the reference expression.
1368    KNOWN_BINFO carries the binfo describing the true type of
1369    OBJ_TYPE_REF_OBJECT(REF).  If a call to the function must be accompanied
1370    with a this adjustment, the constant which should be added to this pointer
1371    is stored to *DELTA.  If REFUSE_THUNKS is true, return NULL if the function
1372    is a thunk (other than a this adjustment which is dealt with by DELTA). */
1373
1374 tree
1375 gimple_get_virt_method_for_binfo (HOST_WIDE_INT token, tree known_binfo,
1376                                   tree *delta, bool refuse_thunks)
1377 {
1378   HOST_WIDE_INT i;
1379   tree v, fndecl;
1380   struct cgraph_node *node;
1381
1382   v = BINFO_VIRTUALS (known_binfo);
1383   /* If there is no virtual methods leave the OBJ_TYPE_REF alone.  */
1384   if (!v)
1385     return NULL_TREE;
1386   i = 0;
1387   while (i != token)
1388     {
1389       i += (TARGET_VTABLE_USES_DESCRIPTORS
1390             ? TARGET_VTABLE_USES_DESCRIPTORS : 1);
1391       v = TREE_CHAIN (v);
1392     }
1393
1394   /* If BV_VCALL_INDEX is non-NULL, give up.  */
1395   if (TREE_TYPE (v))
1396     return NULL_TREE;
1397
1398   fndecl = TREE_VALUE (v);
1399   node = cgraph_get_node_or_alias (fndecl);
1400   if (refuse_thunks
1401       && (!node
1402     /* Bail out if it is a thunk declaration.  Since simple this_adjusting
1403        thunks are represented by a constant in TREE_PURPOSE of items in
1404        BINFO_VIRTUALS, this is a more complicate type which we cannot handle as
1405        yet.
1406
1407        FIXME: Remove the following condition once we are able to represent
1408        thunk information on call graph edges.  */
1409           || (node->same_body_alias && node->thunk.thunk_p)))
1410     return NULL_TREE;
1411
1412   /* When cgraph node is missing and function is not public, we cannot
1413      devirtualize.  This can happen in WHOPR when the actual method
1414      ends up in other partition, because we found devirtualization
1415      possibility too late.  */
1416   if (!can_refer_decl_in_current_unit_p (TREE_VALUE (v)))
1417     return NULL_TREE;
1418
1419   *delta = TREE_PURPOSE (v);
1420   gcc_checking_assert (host_integerp (*delta, 0));
1421   return fndecl;
1422 }
1423
1424 /* Generate code adjusting the first parameter of a call statement determined
1425    by GSI by DELTA.  */
1426
1427 void
1428 gimple_adjust_this_by_delta (gimple_stmt_iterator *gsi, tree delta)
1429 {
1430   gimple call_stmt = gsi_stmt (*gsi);
1431   tree parm, tmp;
1432   gimple new_stmt;
1433
1434   delta = fold_convert (sizetype, delta);
1435   gcc_assert (gimple_call_num_args (call_stmt) >= 1);
1436   parm = gimple_call_arg (call_stmt, 0);
1437   gcc_assert (POINTER_TYPE_P (TREE_TYPE (parm)));
1438   tmp = create_tmp_var (TREE_TYPE (parm), NULL);
1439   add_referenced_var (tmp);
1440
1441   tmp = make_ssa_name (tmp, NULL);
1442   new_stmt = gimple_build_assign_with_ops (POINTER_PLUS_EXPR, tmp, parm, delta);
1443   SSA_NAME_DEF_STMT (tmp) = new_stmt;
1444   gsi_insert_before (gsi, new_stmt, GSI_SAME_STMT);
1445   gimple_call_set_arg (call_stmt, 0, tmp);
1446 }
1447
1448 /* Return a binfo to be used for devirtualization of calls based on an object
1449    represented by a declaration (i.e. a global or automatically allocated one)
1450    or NULL if it cannot be found or is not safe.  CST is expected to be an
1451    ADDR_EXPR of such object or the function will return NULL.  Currently it is
1452    safe to use such binfo only if it has no base binfo (i.e. no ancestors).  */
1453
1454 tree
1455 gimple_extract_devirt_binfo_from_cst (tree cst)
1456 {
1457   HOST_WIDE_INT offset, size, max_size;
1458   tree base, type, expected_type, binfo;
1459   bool last_artificial = false;
1460
1461   if (!flag_devirtualize
1462       || TREE_CODE (cst) != ADDR_EXPR
1463       || TREE_CODE (TREE_TYPE (TREE_TYPE (cst))) != RECORD_TYPE)
1464     return NULL_TREE;
1465
1466   cst = TREE_OPERAND (cst, 0);
1467   expected_type = TREE_TYPE (cst);
1468   base = get_ref_base_and_extent (cst, &offset, &size, &max_size);
1469   type = TREE_TYPE (base);
1470   if (!DECL_P (base)
1471       || max_size == -1
1472       || max_size != size
1473       || TREE_CODE (type) != RECORD_TYPE)
1474     return NULL_TREE;
1475
1476   /* Find the sub-object the constant actually refers to and mark whether it is
1477      an artificial one (as opposed to a user-defined one).  */
1478   while (true)
1479     {
1480       HOST_WIDE_INT pos, size;
1481       tree fld;
1482
1483       if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (expected_type))
1484         break;
1485       if (offset < 0)
1486         return NULL_TREE;
1487
1488       for (fld = TYPE_FIELDS (type); fld; fld = DECL_CHAIN (fld))
1489         {
1490           if (TREE_CODE (fld) != FIELD_DECL)
1491             continue;
1492
1493           pos = int_bit_position (fld);
1494           size = tree_low_cst (DECL_SIZE (fld), 1);
1495           if (pos <= offset && (pos + size) > offset)
1496             break;
1497         }
1498       if (!fld || TREE_CODE (TREE_TYPE (fld)) != RECORD_TYPE)
1499         return NULL_TREE;
1500
1501       last_artificial = DECL_ARTIFICIAL (fld);
1502       type = TREE_TYPE (fld);
1503       offset -= pos;
1504     }
1505   /* Artifical sub-objects are ancestors, we do not want to use them for
1506      devirtualization, at least not here.  */
1507   if (last_artificial)
1508     return NULL_TREE;
1509   binfo = TYPE_BINFO (type);
1510   if (!binfo || BINFO_N_BASE_BINFOS (binfo) > 0)
1511     return NULL_TREE;
1512   else
1513     return binfo;
1514 }
1515
1516 /* Attempt to fold a call statement referenced by the statement iterator GSI.
1517    The statement may be replaced by another statement, e.g., if the call
1518    simplifies to a constant value. Return true if any changes were made.
1519    It is assumed that the operands have been previously folded.  */
1520
1521 bool
1522 gimple_fold_call (gimple_stmt_iterator *gsi, bool inplace)
1523 {
1524   gimple stmt = gsi_stmt (*gsi);
1525   tree callee;
1526
1527   /* Check for builtins that CCP can handle using information not
1528      available in the generic fold routines.  */
1529   callee = gimple_call_fndecl (stmt);
1530   if (!inplace && callee && DECL_BUILT_IN (callee))
1531     {
1532       tree result = gimple_fold_builtin (stmt);
1533
1534       if (result)
1535         {
1536           if (!update_call_from_tree (gsi, result))
1537             gimplify_and_update_call_from_tree (gsi, result);
1538           return true;
1539         }
1540     }
1541
1542   /* Check for virtual calls that became direct calls.  */
1543   callee = gimple_call_fn (stmt);
1544   if (callee && TREE_CODE (callee) == OBJ_TYPE_REF)
1545     {
1546       tree binfo, fndecl, delta, obj;
1547       HOST_WIDE_INT token;
1548
1549       if (gimple_call_addr_fndecl (OBJ_TYPE_REF_EXPR (callee)) != NULL_TREE)
1550         {
1551           gimple_call_set_fn (stmt, OBJ_TYPE_REF_EXPR (callee));
1552           return true;
1553         }
1554
1555       obj = OBJ_TYPE_REF_OBJECT (callee);
1556       binfo = gimple_extract_devirt_binfo_from_cst (obj);
1557       if (!binfo)
1558         return false;
1559       token = TREE_INT_CST_LOW (OBJ_TYPE_REF_TOKEN (callee));
1560       fndecl = gimple_get_virt_method_for_binfo (token, binfo, &delta, false);
1561       if (!fndecl)
1562         return false;
1563       gcc_assert (integer_zerop (delta));
1564       gimple_call_set_fndecl (stmt, fndecl);
1565       return true;
1566     }
1567
1568   return false;
1569 }
1570
1571 /* Worker for both fold_stmt and fold_stmt_inplace.  The INPLACE argument
1572    distinguishes both cases.  */
1573
1574 static bool
1575 fold_stmt_1 (gimple_stmt_iterator *gsi, bool inplace)
1576 {
1577   bool changed = false;
1578   gimple stmt = gsi_stmt (*gsi);
1579   unsigned i;
1580   gimple_stmt_iterator gsinext = *gsi;
1581   gimple next_stmt;
1582
1583   gsi_next (&gsinext);
1584   next_stmt = gsi_end_p (gsinext) ? NULL : gsi_stmt (gsinext);
1585
1586   /* Fold the main computation performed by the statement.  */
1587   switch (gimple_code (stmt))
1588     {
1589     case GIMPLE_ASSIGN:
1590       {
1591         unsigned old_num_ops = gimple_num_ops (stmt);
1592         tree new_rhs = fold_gimple_assign (gsi);
1593         tree lhs = gimple_assign_lhs (stmt);
1594         if (new_rhs
1595             && !useless_type_conversion_p (TREE_TYPE (lhs),
1596                                            TREE_TYPE (new_rhs)))
1597           new_rhs = fold_convert (TREE_TYPE (lhs), new_rhs);
1598         if (new_rhs
1599             && (!inplace
1600                 || get_gimple_rhs_num_ops (TREE_CODE (new_rhs)) < old_num_ops))
1601           {
1602             gimple_assign_set_rhs_from_tree (gsi, new_rhs);
1603             changed = true;
1604           }
1605         break;
1606       }
1607
1608     case GIMPLE_COND:
1609       changed |= fold_gimple_cond (stmt);
1610       break;
1611
1612     case GIMPLE_CALL:
1613       /* Fold *& in call arguments.  */
1614       for (i = 0; i < gimple_call_num_args (stmt); ++i)
1615         if (REFERENCE_CLASS_P (gimple_call_arg (stmt, i)))
1616           {
1617             tree tmp = maybe_fold_reference (gimple_call_arg (stmt, i), false);
1618             if (tmp)
1619               {
1620                 gimple_call_set_arg (stmt, i, tmp);
1621                 changed = true;
1622               }
1623           }
1624       changed |= gimple_fold_call (gsi, inplace);
1625       break;
1626
1627     case GIMPLE_ASM:
1628       /* Fold *& in asm operands.  */
1629       for (i = 0; i < gimple_asm_noutputs (stmt); ++i)
1630         {
1631           tree link = gimple_asm_output_op (stmt, i);
1632           tree op = TREE_VALUE (link);
1633           if (REFERENCE_CLASS_P (op)
1634               && (op = maybe_fold_reference (op, true)) != NULL_TREE)
1635             {
1636               TREE_VALUE (link) = op;
1637               changed = true;
1638             }
1639         }
1640       for (i = 0; i < gimple_asm_ninputs (stmt); ++i)
1641         {
1642           tree link = gimple_asm_input_op (stmt, i);
1643           tree op = TREE_VALUE (link);
1644           if (REFERENCE_CLASS_P (op)
1645               && (op = maybe_fold_reference (op, false)) != NULL_TREE)
1646             {
1647               TREE_VALUE (link) = op;
1648               changed = true;
1649             }
1650         }
1651       break;
1652
1653     case GIMPLE_DEBUG:
1654       if (gimple_debug_bind_p (stmt))
1655         {
1656           tree val = gimple_debug_bind_get_value (stmt);
1657           if (val
1658               && REFERENCE_CLASS_P (val))
1659             {
1660               tree tem = maybe_fold_reference (val, false);
1661               if (tem)
1662                 {
1663                   gimple_debug_bind_set_value (stmt, tem);
1664                   changed = true;
1665                 }
1666             }
1667         }
1668       break;
1669
1670     default:;
1671     }
1672
1673   /* If stmt folds into nothing and it was the last stmt in a bb,
1674      don't call gsi_stmt.  */
1675   if (gsi_end_p (*gsi))
1676     {
1677       gcc_assert (next_stmt == NULL);
1678       return changed;
1679     }
1680
1681   stmt = gsi_stmt (*gsi);
1682
1683   /* Fold *& on the lhs.  Don't do this if stmt folded into nothing,
1684      as we'd changing the next stmt.  */
1685   if (gimple_has_lhs (stmt) && stmt != next_stmt)
1686     {
1687       tree lhs = gimple_get_lhs (stmt);
1688       if (lhs && REFERENCE_CLASS_P (lhs))
1689         {
1690           tree new_lhs = maybe_fold_reference (lhs, true);
1691           if (new_lhs)
1692             {
1693               gimple_set_lhs (stmt, new_lhs);
1694               changed = true;
1695             }
1696         }
1697     }
1698
1699   return changed;
1700 }
1701
1702 /* Fold the statement pointed to by GSI.  In some cases, this function may
1703    replace the whole statement with a new one.  Returns true iff folding
1704    makes any changes.
1705    The statement pointed to by GSI should be in valid gimple form but may
1706    be in unfolded state as resulting from for example constant propagation
1707    which can produce *&x = 0.  */
1708
1709 bool
1710 fold_stmt (gimple_stmt_iterator *gsi)
1711 {
1712   return fold_stmt_1 (gsi, false);
1713 }
1714
1715 /* Perform the minimal folding on statement STMT.  Only operations like
1716    *&x created by constant propagation are handled.  The statement cannot
1717    be replaced with a new one.  Return true if the statement was
1718    changed, false otherwise.
1719    The statement STMT should be in valid gimple form but may
1720    be in unfolded state as resulting from for example constant propagation
1721    which can produce *&x = 0.  */
1722
1723 bool
1724 fold_stmt_inplace (gimple stmt)
1725 {
1726   gimple_stmt_iterator gsi = gsi_for_stmt (stmt);
1727   bool changed = fold_stmt_1 (&gsi, true);
1728   gcc_assert (gsi_stmt (gsi) == stmt);
1729   return changed;
1730 }
1731
1732 /* Canonicalize and possibly invert the boolean EXPR; return NULL_TREE
1733    if EXPR is null or we don't know how.
1734    If non-null, the result always has boolean type.  */
1735
1736 static tree
1737 canonicalize_bool (tree expr, bool invert)
1738 {
1739   if (!expr)
1740     return NULL_TREE;
1741   else if (invert)
1742     {
1743       if (integer_nonzerop (expr))
1744         return boolean_false_node;
1745       else if (integer_zerop (expr))
1746         return boolean_true_node;
1747       else if (TREE_CODE (expr) == SSA_NAME)
1748         return fold_build2 (EQ_EXPR, boolean_type_node, expr,
1749                             build_int_cst (TREE_TYPE (expr), 0));
1750       else if (TREE_CODE_CLASS (TREE_CODE (expr)) == tcc_comparison)
1751         return fold_build2 (invert_tree_comparison (TREE_CODE (expr), false),
1752                             boolean_type_node,
1753                             TREE_OPERAND (expr, 0),
1754                             TREE_OPERAND (expr, 1));
1755       else
1756         return NULL_TREE;
1757     }
1758   else
1759     {
1760       if (TREE_CODE (TREE_TYPE (expr)) == BOOLEAN_TYPE)
1761         return expr;
1762       if (integer_nonzerop (expr))
1763         return boolean_true_node;
1764       else if (integer_zerop (expr))
1765         return boolean_false_node;
1766       else if (TREE_CODE (expr) == SSA_NAME)
1767         return fold_build2 (NE_EXPR, boolean_type_node, expr,
1768                             build_int_cst (TREE_TYPE (expr), 0));
1769       else if (TREE_CODE_CLASS (TREE_CODE (expr)) == tcc_comparison)
1770         return fold_build2 (TREE_CODE (expr),
1771                             boolean_type_node,
1772                             TREE_OPERAND (expr, 0),
1773                             TREE_OPERAND (expr, 1));
1774       else
1775         return NULL_TREE;
1776     }
1777 }
1778
1779 /* Check to see if a boolean expression EXPR is logically equivalent to the
1780    comparison (OP1 CODE OP2).  Check for various identities involving
1781    SSA_NAMEs.  */
1782
1783 static bool
1784 same_bool_comparison_p (const_tree expr, enum tree_code code,
1785                         const_tree op1, const_tree op2)
1786 {
1787   gimple s;
1788
1789   /* The obvious case.  */
1790   if (TREE_CODE (expr) == code
1791       && operand_equal_p (TREE_OPERAND (expr, 0), op1, 0)
1792       && operand_equal_p (TREE_OPERAND (expr, 1), op2, 0))
1793     return true;
1794
1795   /* Check for comparing (name, name != 0) and the case where expr
1796      is an SSA_NAME with a definition matching the comparison.  */
1797   if (TREE_CODE (expr) == SSA_NAME
1798       && TREE_CODE (TREE_TYPE (expr)) == BOOLEAN_TYPE)
1799     {
1800       if (operand_equal_p (expr, op1, 0))
1801         return ((code == NE_EXPR && integer_zerop (op2))
1802                 || (code == EQ_EXPR && integer_nonzerop (op2)));
1803       s = SSA_NAME_DEF_STMT (expr);
1804       if (is_gimple_assign (s)
1805           && gimple_assign_rhs_code (s) == code
1806           && operand_equal_p (gimple_assign_rhs1 (s), op1, 0)
1807           && operand_equal_p (gimple_assign_rhs2 (s), op2, 0))
1808         return true;
1809     }
1810
1811   /* If op1 is of the form (name != 0) or (name == 0), and the definition
1812      of name is a comparison, recurse.  */
1813   if (TREE_CODE (op1) == SSA_NAME
1814       && TREE_CODE (TREE_TYPE (op1)) == BOOLEAN_TYPE)
1815     {
1816       s = SSA_NAME_DEF_STMT (op1);
1817       if (is_gimple_assign (s)
1818           && TREE_CODE_CLASS (gimple_assign_rhs_code (s)) == tcc_comparison)
1819         {
1820           enum tree_code c = gimple_assign_rhs_code (s);
1821           if ((c == NE_EXPR && integer_zerop (op2))
1822               || (c == EQ_EXPR && integer_nonzerop (op2)))
1823             return same_bool_comparison_p (expr, c,
1824                                            gimple_assign_rhs1 (s),
1825                                            gimple_assign_rhs2 (s));
1826           if ((c == EQ_EXPR && integer_zerop (op2))
1827               || (c == NE_EXPR && integer_nonzerop (op2)))
1828             return same_bool_comparison_p (expr,
1829                                            invert_tree_comparison (c, false),
1830                                            gimple_assign_rhs1 (s),
1831                                            gimple_assign_rhs2 (s));
1832         }
1833     }
1834   return false;
1835 }
1836
1837 /* Check to see if two boolean expressions OP1 and OP2 are logically
1838    equivalent.  */
1839
1840 static bool
1841 same_bool_result_p (const_tree op1, const_tree op2)
1842 {
1843   /* Simple cases first.  */
1844   if (operand_equal_p (op1, op2, 0))
1845     return true;
1846
1847   /* Check the cases where at least one of the operands is a comparison.
1848      These are a bit smarter than operand_equal_p in that they apply some
1849      identifies on SSA_NAMEs.  */
1850   if (TREE_CODE_CLASS (TREE_CODE (op2)) == tcc_comparison
1851       && same_bool_comparison_p (op1, TREE_CODE (op2),
1852                                  TREE_OPERAND (op2, 0),
1853                                  TREE_OPERAND (op2, 1)))
1854     return true;
1855   if (TREE_CODE_CLASS (TREE_CODE (op1)) == tcc_comparison
1856       && same_bool_comparison_p (op2, TREE_CODE (op1),
1857                                  TREE_OPERAND (op1, 0),
1858                                  TREE_OPERAND (op1, 1)))
1859     return true;
1860
1861   /* Default case.  */
1862   return false;
1863 }
1864
1865 /* Forward declarations for some mutually recursive functions.  */
1866
1867 static tree
1868 and_comparisons_1 (enum tree_code code1, tree op1a, tree op1b,
1869                    enum tree_code code2, tree op2a, tree op2b);
1870 static tree
1871 and_var_with_comparison (tree var, bool invert,
1872                          enum tree_code code2, tree op2a, tree op2b);
1873 static tree
1874 and_var_with_comparison_1 (gimple stmt,
1875                            enum tree_code code2, tree op2a, tree op2b);
1876 static tree
1877 or_comparisons_1 (enum tree_code code1, tree op1a, tree op1b,
1878                   enum tree_code code2, tree op2a, tree op2b);
1879 static tree
1880 or_var_with_comparison (tree var, bool invert,
1881                         enum tree_code code2, tree op2a, tree op2b);
1882 static tree
1883 or_var_with_comparison_1 (gimple stmt,
1884                           enum tree_code code2, tree op2a, tree op2b);
1885
1886 /* Helper function for and_comparisons_1:  try to simplify the AND of the
1887    ssa variable VAR with the comparison specified by (OP2A CODE2 OP2B).
1888    If INVERT is true, invert the value of the VAR before doing the AND.
1889    Return NULL_EXPR if we can't simplify this to a single expression.  */
1890
1891 static tree
1892 and_var_with_comparison (tree var, bool invert,
1893                          enum tree_code code2, tree op2a, tree op2b)
1894 {
1895   tree t;
1896   gimple stmt = SSA_NAME_DEF_STMT (var);
1897
1898   /* We can only deal with variables whose definitions are assignments.  */
1899   if (!is_gimple_assign (stmt))
1900     return NULL_TREE;
1901
1902   /* If we have an inverted comparison, apply DeMorgan's law and rewrite
1903      !var AND (op2a code2 op2b) => !(var OR !(op2a code2 op2b))
1904      Then we only have to consider the simpler non-inverted cases.  */
1905   if (invert)
1906     t = or_var_with_comparison_1 (stmt,
1907                                   invert_tree_comparison (code2, false),
1908                                   op2a, op2b);
1909   else
1910     t = and_var_with_comparison_1 (stmt, code2, op2a, op2b);
1911   return canonicalize_bool (t, invert);
1912 }
1913
1914 /* Try to simplify the AND of the ssa variable defined by the assignment
1915    STMT with the comparison specified by (OP2A CODE2 OP2B).
1916    Return NULL_EXPR if we can't simplify this to a single expression.  */
1917
1918 static tree
1919 and_var_with_comparison_1 (gimple stmt,
1920                            enum tree_code code2, tree op2a, tree op2b)
1921 {
1922   tree var = gimple_assign_lhs (stmt);
1923   tree true_test_var = NULL_TREE;
1924   tree false_test_var = NULL_TREE;
1925   enum tree_code innercode = gimple_assign_rhs_code (stmt);
1926
1927   /* Check for identities like (var AND (var == 0)) => false.  */
1928   if (TREE_CODE (op2a) == SSA_NAME
1929       && TREE_CODE (TREE_TYPE (var)) == BOOLEAN_TYPE)
1930     {
1931       if ((code2 == NE_EXPR && integer_zerop (op2b))
1932           || (code2 == EQ_EXPR && integer_nonzerop (op2b)))
1933         {
1934           true_test_var = op2a;
1935           if (var == true_test_var)
1936             return var;
1937         }
1938       else if ((code2 == EQ_EXPR && integer_zerop (op2b))
1939                || (code2 == NE_EXPR && integer_nonzerop (op2b)))
1940         {
1941           false_test_var = op2a;
1942           if (var == false_test_var)
1943             return boolean_false_node;
1944         }
1945     }
1946
1947   /* If the definition is a comparison, recurse on it.  */
1948   if (TREE_CODE_CLASS (innercode) == tcc_comparison)
1949     {
1950       tree t = and_comparisons_1 (innercode,
1951                                   gimple_assign_rhs1 (stmt),
1952                                   gimple_assign_rhs2 (stmt),
1953                                   code2,
1954                                   op2a,
1955                                   op2b);
1956       if (t)
1957         return t;
1958     }
1959
1960   /* If the definition is an AND or OR expression, we may be able to
1961      simplify by reassociating.  */
1962   if (innercode == TRUTH_AND_EXPR
1963       || innercode == TRUTH_OR_EXPR
1964       || (TREE_CODE (TREE_TYPE (var)) == BOOLEAN_TYPE
1965           && (innercode == BIT_AND_EXPR || innercode == BIT_IOR_EXPR)))
1966     {
1967       tree inner1 = gimple_assign_rhs1 (stmt);
1968       tree inner2 = gimple_assign_rhs2 (stmt);
1969       gimple s;
1970       tree t;
1971       tree partial = NULL_TREE;
1972       bool is_and = (innercode == TRUTH_AND_EXPR || innercode == BIT_AND_EXPR);
1973
1974       /* Check for boolean identities that don't require recursive examination
1975          of inner1/inner2:
1976          inner1 AND (inner1 AND inner2) => inner1 AND inner2 => var
1977          inner1 AND (inner1 OR inner2) => inner1
1978          !inner1 AND (inner1 AND inner2) => false
1979          !inner1 AND (inner1 OR inner2) => !inner1 AND inner2
1980          Likewise for similar cases involving inner2.  */
1981       if (inner1 == true_test_var)
1982         return (is_and ? var : inner1);
1983       else if (inner2 == true_test_var)
1984         return (is_and ? var : inner2);
1985       else if (inner1 == false_test_var)
1986         return (is_and
1987                 ? boolean_false_node
1988                 : and_var_with_comparison (inner2, false, code2, op2a, op2b));
1989       else if (inner2 == false_test_var)
1990         return (is_and
1991                 ? boolean_false_node
1992                 : and_var_with_comparison (inner1, false, code2, op2a, op2b));
1993
1994       /* Next, redistribute/reassociate the AND across the inner tests.
1995          Compute the first partial result, (inner1 AND (op2a code op2b))  */
1996       if (TREE_CODE (inner1) == SSA_NAME
1997           && is_gimple_assign (s = SSA_NAME_DEF_STMT (inner1))
1998           && TREE_CODE_CLASS (gimple_assign_rhs_code (s)) == tcc_comparison
1999           && (t = maybe_fold_and_comparisons (gimple_assign_rhs_code (s),
2000                                               gimple_assign_rhs1 (s),
2001                                               gimple_assign_rhs2 (s),
2002                                               code2, op2a, op2b)))
2003         {
2004           /* Handle the AND case, where we are reassociating:
2005              (inner1 AND inner2) AND (op2a code2 op2b)
2006              => (t AND inner2)
2007              If the partial result t is a constant, we win.  Otherwise
2008              continue on to try reassociating with the other inner test.  */
2009           if (is_and)
2010             {
2011               if (integer_onep (t))
2012                 return inner2;
2013               else if (integer_zerop (t))
2014                 return boolean_false_node;
2015             }
2016
2017           /* Handle the OR case, where we are redistributing:
2018              (inner1 OR inner2) AND (op2a code2 op2b)
2019              => (t OR (inner2 AND (op2a code2 op2b)))  */
2020           else if (integer_onep (t))
2021             return boolean_true_node;
2022
2023           /* Save partial result for later.  */
2024           partial = t;
2025         }
2026
2027       /* Compute the second partial result, (inner2 AND (op2a code op2b)) */
2028       if (TREE_CODE (inner2) == SSA_NAME
2029           && is_gimple_assign (s = SSA_NAME_DEF_STMT (inner2))
2030           && TREE_CODE_CLASS (gimple_assign_rhs_code (s)) == tcc_comparison
2031           && (t = maybe_fold_and_comparisons (gimple_assign_rhs_code (s),
2032                                               gimple_assign_rhs1 (s),
2033                                               gimple_assign_rhs2 (s),
2034                                               code2, op2a, op2b)))
2035         {
2036           /* Handle the AND case, where we are reassociating:
2037              (inner1 AND inner2) AND (op2a code2 op2b)
2038              => (inner1 AND t)  */
2039           if (is_and)
2040             {
2041               if (integer_onep (t))
2042                 return inner1;
2043               else if (integer_zerop (t))
2044                 return boolean_false_node;
2045               /* If both are the same, we can apply the identity
2046                  (x AND x) == x.  */
2047               else if (partial && same_bool_result_p (t, partial))
2048                 return t;
2049             }
2050
2051           /* Handle the OR case. where we are redistributing:
2052              (inner1 OR inner2) AND (op2a code2 op2b)
2053              => (t OR (inner1 AND (op2a code2 op2b)))
2054              => (t OR partial)  */
2055           else
2056             {
2057               if (integer_onep (t))
2058                 return boolean_true_node;
2059               else if (partial)
2060                 {
2061                   /* We already got a simplification for the other
2062                      operand to the redistributed OR expression.  The
2063                      interesting case is when at least one is false.
2064                      Or, if both are the same, we can apply the identity
2065                      (x OR x) == x.  */
2066                   if (integer_zerop (partial))
2067                     return t;
2068                   else if (integer_zerop (t))
2069                     return partial;
2070                   else if (same_bool_result_p (t, partial))
2071                     return t;
2072                 }
2073             }
2074         }
2075     }
2076   return NULL_TREE;
2077 }
2078
2079 /* Try to simplify the AND of two comparisons defined by
2080    (OP1A CODE1 OP1B) and (OP2A CODE2 OP2B), respectively.
2081    If this can be done without constructing an intermediate value,
2082    return the resulting tree; otherwise NULL_TREE is returned.
2083    This function is deliberately asymmetric as it recurses on SSA_DEFs
2084    in the first comparison but not the second.  */
2085
2086 static tree
2087 and_comparisons_1 (enum tree_code code1, tree op1a, tree op1b,
2088                    enum tree_code code2, tree op2a, tree op2b)
2089 {
2090   /* First check for ((x CODE1 y) AND (x CODE2 y)).  */
2091   if (operand_equal_p (op1a, op2a, 0)
2092       && operand_equal_p (op1b, op2b, 0))
2093     {
2094       tree t = combine_comparisons (UNKNOWN_LOCATION,
2095                                     TRUTH_ANDIF_EXPR, code1, code2,
2096                                     boolean_type_node, op1a, op1b);
2097       if (t)
2098         return t;
2099     }
2100
2101   /* Likewise the swapped case of the above.  */
2102   if (operand_equal_p (op1a, op2b, 0)
2103       && operand_equal_p (op1b, op2a, 0))
2104     {
2105       tree t = combine_comparisons (UNKNOWN_LOCATION,
2106                                     TRUTH_ANDIF_EXPR, code1,
2107                                     swap_tree_comparison (code2),
2108                                     boolean_type_node, op1a, op1b);
2109       if (t)
2110         return t;
2111     }
2112
2113   /* If both comparisons are of the same value against constants, we might
2114      be able to merge them.  */
2115   if (operand_equal_p (op1a, op2a, 0)
2116       && TREE_CODE (op1b) == INTEGER_CST
2117       && TREE_CODE (op2b) == INTEGER_CST)
2118     {
2119       int cmp = tree_int_cst_compare (op1b, op2b);
2120
2121       /* If we have (op1a == op1b), we should either be able to
2122          return that or FALSE, depending on whether the constant op1b
2123          also satisfies the other comparison against op2b.  */
2124       if (code1 == EQ_EXPR)
2125         {
2126           bool done = true;
2127           bool val;
2128           switch (code2)
2129             {
2130             case EQ_EXPR: val = (cmp == 0); break;
2131             case NE_EXPR: val = (cmp != 0); break;
2132             case LT_EXPR: val = (cmp < 0); break;
2133             case GT_EXPR: val = (cmp > 0); break;
2134             case LE_EXPR: val = (cmp <= 0); break;
2135             case GE_EXPR: val = (cmp >= 0); break;
2136             default: done = false;
2137             }
2138           if (done)
2139             {
2140               if (val)
2141                 return fold_build2 (code1, boolean_type_node, op1a, op1b);
2142               else
2143                 return boolean_false_node;
2144             }
2145         }
2146       /* Likewise if the second comparison is an == comparison.  */
2147       else if (code2 == EQ_EXPR)
2148         {
2149           bool done = true;
2150           bool val;
2151           switch (code1)
2152             {
2153             case EQ_EXPR: val = (cmp == 0); break;
2154             case NE_EXPR: val = (cmp != 0); break;
2155             case LT_EXPR: val = (cmp > 0); break;
2156             case GT_EXPR: val = (cmp < 0); break;
2157             case LE_EXPR: val = (cmp >= 0); break;
2158             case GE_EXPR: val = (cmp <= 0); break;
2159             default: done = false;
2160             }
2161           if (done)
2162             {
2163               if (val)
2164                 return fold_build2 (code2, boolean_type_node, op2a, op2b);
2165               else
2166                 return boolean_false_node;
2167             }
2168         }
2169
2170       /* Same business with inequality tests.  */
2171       else if (code1 == NE_EXPR)
2172         {
2173           bool val;
2174           switch (code2)
2175             {
2176             case EQ_EXPR: val = (cmp != 0); break;
2177             case NE_EXPR: val = (cmp == 0); break;
2178             case LT_EXPR: val = (cmp >= 0); break;
2179             case GT_EXPR: val = (cmp <= 0); break;
2180             case LE_EXPR: val = (cmp > 0); break;
2181             case GE_EXPR: val = (cmp < 0); break;
2182             default:
2183               val = false;
2184             }
2185           if (val)
2186             return fold_build2 (code2, boolean_type_node, op2a, op2b);
2187         }
2188       else if (code2 == NE_EXPR)
2189         {
2190           bool val;
2191           switch (code1)
2192             {
2193             case EQ_EXPR: val = (cmp == 0); break;
2194             case NE_EXPR: val = (cmp != 0); break;
2195             case LT_EXPR: val = (cmp <= 0); break;
2196             case GT_EXPR: val = (cmp >= 0); break;
2197             case LE_EXPR: val = (cmp < 0); break;
2198             case GE_EXPR: val = (cmp > 0); break;
2199             default:
2200               val = false;
2201             }
2202           if (val)
2203             return fold_build2 (code1, boolean_type_node, op1a, op1b);
2204         }
2205
2206       /* Chose the more restrictive of two < or <= comparisons.  */
2207       else if ((code1 == LT_EXPR || code1 == LE_EXPR)
2208                && (code2 == LT_EXPR || code2 == LE_EXPR))
2209         {
2210           if ((cmp < 0) || (cmp == 0 && code1 == LT_EXPR))
2211             return fold_build2 (code1, boolean_type_node, op1a, op1b);
2212           else
2213             return fold_build2 (code2, boolean_type_node, op2a, op2b);
2214         }
2215
2216       /* Likewise chose the more restrictive of two > or >= comparisons.  */
2217       else if ((code1 == GT_EXPR || code1 == GE_EXPR)
2218                && (code2 == GT_EXPR || code2 == GE_EXPR))
2219         {
2220           if ((cmp > 0) || (cmp == 0 && code1 == GT_EXPR))
2221             return fold_build2 (code1, boolean_type_node, op1a, op1b);
2222           else
2223             return fold_build2 (code2, boolean_type_node, op2a, op2b);
2224         }
2225
2226       /* Check for singleton ranges.  */
2227       else if (cmp == 0
2228                && ((code1 == LE_EXPR && code2 == GE_EXPR)
2229                    || (code1 == GE_EXPR && code2 == LE_EXPR)))
2230         return fold_build2 (EQ_EXPR, boolean_type_node, op1a, op2b);
2231
2232       /* Check for disjoint ranges. */
2233       else if (cmp <= 0
2234                && (code1 == LT_EXPR || code1 == LE_EXPR)
2235                && (code2 == GT_EXPR || code2 == GE_EXPR))
2236         return boolean_false_node;
2237       else if (cmp >= 0
2238                && (code1 == GT_EXPR || code1 == GE_EXPR)
2239                && (code2 == LT_EXPR || code2 == LE_EXPR))
2240         return boolean_false_node;
2241     }
2242
2243   /* Perhaps the first comparison is (NAME != 0) or (NAME == 1) where
2244      NAME's definition is a truth value.  See if there are any simplifications
2245      that can be done against the NAME's definition.  */
2246   if (TREE_CODE (op1a) == SSA_NAME
2247       && (code1 == NE_EXPR || code1 == EQ_EXPR)
2248       && (integer_zerop (op1b) || integer_onep (op1b)))
2249     {
2250       bool invert = ((code1 == EQ_EXPR && integer_zerop (op1b))
2251                      || (code1 == NE_EXPR && integer_onep (op1b)));
2252       gimple stmt = SSA_NAME_DEF_STMT (op1a);
2253       switch (gimple_code (stmt))
2254         {
2255         case GIMPLE_ASSIGN:
2256           /* Try to simplify by copy-propagating the definition.  */
2257           return and_var_with_comparison (op1a, invert, code2, op2a, op2b);
2258
2259         case GIMPLE_PHI:
2260           /* If every argument to the PHI produces the same result when
2261              ANDed with the second comparison, we win.
2262              Do not do this unless the type is bool since we need a bool
2263              result here anyway.  */
2264           if (TREE_CODE (TREE_TYPE (op1a)) == BOOLEAN_TYPE)
2265             {
2266               tree result = NULL_TREE;
2267               unsigned i;
2268               for (i = 0; i < gimple_phi_num_args (stmt); i++)
2269                 {
2270                   tree arg = gimple_phi_arg_def (stmt, i);
2271
2272                   /* If this PHI has itself as an argument, ignore it.
2273                      If all the other args produce the same result,
2274                      we're still OK.  */
2275                   if (arg == gimple_phi_result (stmt))
2276                     continue;
2277                   else if (TREE_CODE (arg) == INTEGER_CST)
2278                     {
2279                       if (invert ? integer_nonzerop (arg) : integer_zerop (arg))
2280                         {
2281                           if (!result)
2282                             result = boolean_false_node;
2283                           else if (!integer_zerop (result))
2284                             return NULL_TREE;
2285                         }
2286                       else if (!result)
2287                         result = fold_build2 (code2, boolean_type_node,
2288                                               op2a, op2b);
2289                       else if (!same_bool_comparison_p (result,
2290                                                         code2, op2a, op2b))
2291                         return NULL_TREE;
2292                     }
2293                   else if (TREE_CODE (arg) == SSA_NAME
2294                            && !SSA_NAME_IS_DEFAULT_DEF (arg))
2295                     {
2296                       tree temp;
2297                       gimple def_stmt = SSA_NAME_DEF_STMT (arg);
2298                       /* In simple cases we can look through PHI nodes,
2299                          but we have to be careful with loops.
2300                          See PR49073.  */
2301                       if (! dom_info_available_p (CDI_DOMINATORS)
2302                           || gimple_bb (def_stmt) == gimple_bb (stmt)
2303                           || dominated_by_p (CDI_DOMINATORS,
2304                                              gimple_bb (def_stmt),
2305                                              gimple_bb (stmt)))
2306                         return NULL_TREE;
2307                       temp = and_var_with_comparison (arg, invert, code2,
2308                                                       op2a, op2b);
2309                       if (!temp)
2310                         return NULL_TREE;
2311                       else if (!result)
2312                         result = temp;
2313                       else if (!same_bool_result_p (result, temp))
2314                         return NULL_TREE;
2315                     }
2316                   else
2317                     return NULL_TREE;
2318                 }
2319               return result;
2320             }
2321
2322         default:
2323           break;
2324         }
2325     }
2326   return NULL_TREE;
2327 }
2328
2329 /* Try to simplify the AND of two comparisons, specified by
2330    (OP1A CODE1 OP1B) and (OP2B CODE2 OP2B), respectively.
2331    If this can be simplified to a single expression (without requiring
2332    introducing more SSA variables to hold intermediate values),
2333    return the resulting tree.  Otherwise return NULL_TREE.
2334    If the result expression is non-null, it has boolean type.  */
2335
2336 tree
2337 maybe_fold_and_comparisons (enum tree_code code1, tree op1a, tree op1b,
2338                             enum tree_code code2, tree op2a, tree op2b)
2339 {
2340   tree t = and_comparisons_1 (code1, op1a, op1b, code2, op2a, op2b);
2341   if (t)
2342     return t;
2343   else
2344     return and_comparisons_1 (code2, op2a, op2b, code1, op1a, op1b);
2345 }
2346
2347 /* Helper function for or_comparisons_1:  try to simplify the OR of the
2348    ssa variable VAR with the comparison specified by (OP2A CODE2 OP2B).
2349    If INVERT is true, invert the value of VAR before doing the OR.
2350    Return NULL_EXPR if we can't simplify this to a single expression.  */
2351
2352 static tree
2353 or_var_with_comparison (tree var, bool invert,
2354                         enum tree_code code2, tree op2a, tree op2b)
2355 {
2356   tree t;
2357   gimple stmt = SSA_NAME_DEF_STMT (var);
2358
2359   /* We can only deal with variables whose definitions are assignments.  */
2360   if (!is_gimple_assign (stmt))
2361     return NULL_TREE;
2362
2363   /* If we have an inverted comparison, apply DeMorgan's law and rewrite
2364      !var OR (op2a code2 op2b) => !(var AND !(op2a code2 op2b))
2365      Then we only have to consider the simpler non-inverted cases.  */
2366   if (invert)
2367     t = and_var_with_comparison_1 (stmt,
2368                                    invert_tree_comparison (code2, false),
2369                                    op2a, op2b);
2370   else
2371     t = or_var_with_comparison_1 (stmt, code2, op2a, op2b);
2372   return canonicalize_bool (t, invert);
2373 }
2374
2375 /* Try to simplify the OR of the ssa variable defined by the assignment
2376    STMT with the comparison specified by (OP2A CODE2 OP2B).
2377    Return NULL_EXPR if we can't simplify this to a single expression.  */
2378
2379 static tree
2380 or_var_with_comparison_1 (gimple stmt,
2381                           enum tree_code code2, tree op2a, tree op2b)
2382 {
2383   tree var = gimple_assign_lhs (stmt);
2384   tree true_test_var = NULL_TREE;
2385   tree false_test_var = NULL_TREE;
2386   enum tree_code innercode = gimple_assign_rhs_code (stmt);
2387
2388   /* Check for identities like (var OR (var != 0)) => true .  */
2389   if (TREE_CODE (op2a) == SSA_NAME
2390       && TREE_CODE (TREE_TYPE (var)) == BOOLEAN_TYPE)
2391     {
2392       if ((code2 == NE_EXPR && integer_zerop (op2b))
2393           || (code2 == EQ_EXPR && integer_nonzerop (op2b)))
2394         {
2395           true_test_var = op2a;
2396           if (var == true_test_var)
2397             return var;
2398         }
2399       else if ((code2 == EQ_EXPR && integer_zerop (op2b))
2400                || (code2 == NE_EXPR && integer_nonzerop (op2b)))
2401         {
2402           false_test_var = op2a;
2403           if (var == false_test_var)
2404             return boolean_true_node;
2405         }
2406     }
2407
2408   /* If the definition is a comparison, recurse on it.  */
2409   if (TREE_CODE_CLASS (innercode) == tcc_comparison)
2410     {
2411       tree t = or_comparisons_1 (innercode,
2412                                  gimple_assign_rhs1 (stmt),
2413                                  gimple_assign_rhs2 (stmt),
2414                                  code2,
2415                                  op2a,
2416                                  op2b);
2417       if (t)
2418         return t;
2419     }
2420
2421   /* If the definition is an AND or OR expression, we may be able to
2422      simplify by reassociating.  */
2423   if (innercode == TRUTH_AND_EXPR
2424       || innercode == TRUTH_OR_EXPR
2425       || (TREE_CODE (TREE_TYPE (var)) == BOOLEAN_TYPE
2426           && (innercode == BIT_AND_EXPR || innercode == BIT_IOR_EXPR)))
2427     {
2428       tree inner1 = gimple_assign_rhs1 (stmt);
2429       tree inner2 = gimple_assign_rhs2 (stmt);
2430       gimple s;
2431       tree t;
2432       tree partial = NULL_TREE;
2433       bool is_or = (innercode == TRUTH_OR_EXPR || innercode == BIT_IOR_EXPR);
2434
2435       /* Check for boolean identities that don't require recursive examination
2436          of inner1/inner2:
2437          inner1 OR (inner1 OR inner2) => inner1 OR inner2 => var
2438          inner1 OR (inner1 AND inner2) => inner1
2439          !inner1 OR (inner1 OR inner2) => true
2440          !inner1 OR (inner1 AND inner2) => !inner1 OR inner2
2441       */
2442       if (inner1 == true_test_var)
2443         return (is_or ? var : inner1);
2444       else if (inner2 == true_test_var)
2445         return (is_or ? var : inner2);
2446       else if (inner1 == false_test_var)
2447         return (is_or
2448                 ? boolean_true_node
2449                 : or_var_with_comparison (inner2, false, code2, op2a, op2b));
2450       else if (inner2 == false_test_var)
2451         return (is_or
2452                 ? boolean_true_node
2453                 : or_var_with_comparison (inner1, false, code2, op2a, op2b));
2454
2455       /* Next, redistribute/reassociate the OR across the inner tests.
2456          Compute the first partial result, (inner1 OR (op2a code op2b))  */
2457       if (TREE_CODE (inner1) == SSA_NAME
2458           && is_gimple_assign (s = SSA_NAME_DEF_STMT (inner1))
2459           && TREE_CODE_CLASS (gimple_assign_rhs_code (s)) == tcc_comparison
2460           && (t = maybe_fold_or_comparisons (gimple_assign_rhs_code (s),
2461                                              gimple_assign_rhs1 (s),
2462                                              gimple_assign_rhs2 (s),
2463                                              code2, op2a, op2b)))
2464         {
2465           /* Handle the OR case, where we are reassociating:
2466              (inner1 OR inner2) OR (op2a code2 op2b)
2467              => (t OR inner2)
2468              If the partial result t is a constant, we win.  Otherwise
2469              continue on to try reassociating with the other inner test.  */
2470           if (is_or)
2471             {
2472               if (integer_onep (t))
2473                 return boolean_true_node;
2474               else if (integer_zerop (t))
2475                 return inner2;
2476             }
2477
2478           /* Handle the AND case, where we are redistributing:
2479              (inner1 AND inner2) OR (op2a code2 op2b)
2480              => (t AND (inner2 OR (op2a code op2b)))  */
2481           else if (integer_zerop (t))
2482             return boolean_false_node;
2483
2484           /* Save partial result for later.  */
2485           partial = t;
2486         }
2487
2488       /* Compute the second partial result, (inner2 OR (op2a code op2b)) */
2489       if (TREE_CODE (inner2) == SSA_NAME
2490           && is_gimple_assign (s = SSA_NAME_DEF_STMT (inner2))
2491           && TREE_CODE_CLASS (gimple_assign_rhs_code (s)) == tcc_comparison
2492           && (t = maybe_fold_or_comparisons (gimple_assign_rhs_code (s),
2493                                              gimple_assign_rhs1 (s),
2494                                              gimple_assign_rhs2 (s),
2495                                              code2, op2a, op2b)))
2496         {
2497           /* Handle the OR case, where we are reassociating:
2498              (inner1 OR inner2) OR (op2a code2 op2b)
2499              => (inner1 OR t)
2500              => (t OR partial)  */
2501           if (is_or)
2502             {
2503               if (integer_zerop (t))
2504                 return inner1;
2505               else if (integer_onep (t))
2506                 return boolean_true_node;
2507               /* If both are the same, we can apply the identity
2508                  (x OR x) == x.  */
2509               else if (partial && same_bool_result_p (t, partial))
2510                 return t;
2511             }
2512
2513           /* Handle the AND case, where we are redistributing:
2514              (inner1 AND inner2) OR (op2a code2 op2b)
2515              => (t AND (inner1 OR (op2a code2 op2b)))
2516              => (t AND partial)  */
2517           else
2518             {
2519               if (integer_zerop (t))
2520                 return boolean_false_node;
2521               else if (partial)
2522                 {
2523                   /* We already got a simplification for the other
2524                      operand to the redistributed AND expression.  The
2525                      interesting case is when at least one is true.
2526                      Or, if both are the same, we can apply the identity
2527                      (x AND x) == x.  */
2528                   if (integer_onep (partial))
2529                     return t;
2530                   else if (integer_onep (t))
2531                     return partial;
2532                   else if (same_bool_result_p (t, partial))
2533                     return t;
2534                 }
2535             }
2536         }
2537     }
2538   return NULL_TREE;
2539 }
2540
2541 /* Try to simplify the OR of two comparisons defined by
2542    (OP1A CODE1 OP1B) and (OP2A CODE2 OP2B), respectively.
2543    If this can be done without constructing an intermediate value,
2544    return the resulting tree; otherwise NULL_TREE is returned.
2545    This function is deliberately asymmetric as it recurses on SSA_DEFs
2546    in the first comparison but not the second.  */
2547
2548 static tree
2549 or_comparisons_1 (enum tree_code code1, tree op1a, tree op1b,
2550                   enum tree_code code2, tree op2a, tree op2b)
2551 {
2552   /* First check for ((x CODE1 y) OR (x CODE2 y)).  */
2553   if (operand_equal_p (op1a, op2a, 0)
2554       && operand_equal_p (op1b, op2b, 0))
2555     {
2556       tree t = combine_comparisons (UNKNOWN_LOCATION,
2557                                     TRUTH_ORIF_EXPR, code1, code2,
2558                                     boolean_type_node, op1a, op1b);
2559       if (t)
2560         return t;
2561     }
2562
2563   /* Likewise the swapped case of the above.  */
2564   if (operand_equal_p (op1a, op2b, 0)
2565       && operand_equal_p (op1b, op2a, 0))
2566     {
2567       tree t = combine_comparisons (UNKNOWN_LOCATION,
2568                                     TRUTH_ORIF_EXPR, code1,
2569                                     swap_tree_comparison (code2),
2570                                     boolean_type_node, op1a, op1b);
2571       if (t)
2572         return t;
2573     }
2574
2575   /* If both comparisons are of the same value against constants, we might
2576      be able to merge them.  */
2577   if (operand_equal_p (op1a, op2a, 0)
2578       && TREE_CODE (op1b) == INTEGER_CST
2579       && TREE_CODE (op2b) == INTEGER_CST)
2580     {
2581       int cmp = tree_int_cst_compare (op1b, op2b);
2582
2583       /* If we have (op1a != op1b), we should either be able to
2584          return that or TRUE, depending on whether the constant op1b
2585          also satisfies the other comparison against op2b.  */
2586       if (code1 == NE_EXPR)
2587         {
2588           bool done = true;
2589           bool val;
2590           switch (code2)
2591             {
2592             case EQ_EXPR: val = (cmp == 0); break;
2593             case NE_EXPR: val = (cmp != 0); break;
2594             case LT_EXPR: val = (cmp < 0); break;
2595             case GT_EXPR: val = (cmp > 0); break;
2596             case LE_EXPR: val = (cmp <= 0); break;
2597             case GE_EXPR: val = (cmp >= 0); break;
2598             default: done = false;
2599             }
2600           if (done)
2601             {
2602               if (val)
2603                 return boolean_true_node;
2604               else
2605                 return fold_build2 (code1, boolean_type_node, op1a, op1b);
2606             }
2607         }
2608       /* Likewise if the second comparison is a != comparison.  */
2609       else if (code2 == NE_EXPR)
2610         {
2611           bool done = true;
2612           bool val;
2613           switch (code1)
2614             {
2615             case EQ_EXPR: val = (cmp == 0); break;
2616             case NE_EXPR: val = (cmp != 0); break;
2617             case LT_EXPR: val = (cmp > 0); break;
2618             case GT_EXPR: val = (cmp < 0); break;
2619             case LE_EXPR: val = (cmp >= 0); break;
2620             case GE_EXPR: val = (cmp <= 0); break;
2621             default: done = false;
2622             }
2623           if (done)
2624             {
2625               if (val)
2626                 return boolean_true_node;
2627               else
2628                 return fold_build2 (code2, boolean_type_node, op2a, op2b);
2629             }
2630         }
2631
2632       /* See if an equality test is redundant with the other comparison.  */
2633       else if (code1 == EQ_EXPR)
2634         {
2635           bool val;
2636           switch (code2)
2637             {
2638             case EQ_EXPR: val = (cmp == 0); break;
2639             case NE_EXPR: val = (cmp != 0); break;
2640             case LT_EXPR: val = (cmp < 0); break;
2641             case GT_EXPR: val = (cmp > 0); break;
2642             case LE_EXPR: val = (cmp <= 0); break;
2643             case GE_EXPR: val = (cmp >= 0); break;
2644             default:
2645               val = false;
2646             }
2647           if (val)
2648             return fold_build2 (code2, boolean_type_node, op2a, op2b);
2649         }
2650       else if (code2 == EQ_EXPR)
2651         {
2652           bool val;
2653           switch (code1)
2654             {
2655             case EQ_EXPR: val = (cmp == 0); break;
2656             case NE_EXPR: val = (cmp != 0); break;
2657             case LT_EXPR: val = (cmp > 0); break;
2658             case GT_EXPR: val = (cmp < 0); break;
2659             case LE_EXPR: val = (cmp >= 0); break;
2660             case GE_EXPR: val = (cmp <= 0); break;
2661             default:
2662               val = false;
2663             }
2664           if (val)
2665             return fold_build2 (code1, boolean_type_node, op1a, op1b);
2666         }
2667
2668       /* Chose the less restrictive of two < or <= comparisons.  */
2669       else if ((code1 == LT_EXPR || code1 == LE_EXPR)
2670                && (code2 == LT_EXPR || code2 == LE_EXPR))
2671         {
2672           if ((cmp < 0) || (cmp == 0 && code1 == LT_EXPR))
2673             return fold_build2 (code2, boolean_type_node, op2a, op2b);
2674           else
2675             return fold_build2 (code1, boolean_type_node, op1a, op1b);
2676         }
2677
2678       /* Likewise chose the less restrictive of two > or >= comparisons.  */
2679       else if ((code1 == GT_EXPR || code1 == GE_EXPR)
2680                && (code2 == GT_EXPR || code2 == GE_EXPR))
2681         {
2682           if ((cmp > 0) || (cmp == 0 && code1 == GT_EXPR))
2683             return fold_build2 (code2, boolean_type_node, op2a, op2b);
2684           else
2685             return fold_build2 (code1, boolean_type_node, op1a, op1b);
2686         }
2687
2688       /* Check for singleton ranges.  */
2689       else if (cmp == 0
2690                && ((code1 == LT_EXPR && code2 == GT_EXPR)
2691                    || (code1 == GT_EXPR && code2 == LT_EXPR)))
2692         return fold_build2 (NE_EXPR, boolean_type_node, op1a, op2b);
2693
2694       /* Check for less/greater pairs that don't restrict the range at all.  */
2695       else if (cmp >= 0
2696                && (code1 == LT_EXPR || code1 == LE_EXPR)
2697                && (code2 == GT_EXPR || code2 == GE_EXPR))
2698         return boolean_true_node;
2699       else if (cmp <= 0
2700                && (code1 == GT_EXPR || code1 == GE_EXPR)
2701                && (code2 == LT_EXPR || code2 == LE_EXPR))
2702         return boolean_true_node;
2703     }
2704
2705   /* Perhaps the first comparison is (NAME != 0) or (NAME == 1) where
2706      NAME's definition is a truth value.  See if there are any simplifications
2707      that can be done against the NAME's definition.  */
2708   if (TREE_CODE (op1a) == SSA_NAME
2709       && (code1 == NE_EXPR || code1 == EQ_EXPR)
2710       && (integer_zerop (op1b) || integer_onep (op1b)))
2711     {
2712       bool invert = ((code1 == EQ_EXPR && integer_zerop (op1b))
2713                      || (code1 == NE_EXPR && integer_onep (op1b)));
2714       gimple stmt = SSA_NAME_DEF_STMT (op1a);
2715       switch (gimple_code (stmt))
2716         {
2717         case GIMPLE_ASSIGN:
2718           /* Try to simplify by copy-propagating the definition.  */
2719           return or_var_with_comparison (op1a, invert, code2, op2a, op2b);
2720
2721         case GIMPLE_PHI:
2722           /* If every argument to the PHI produces the same result when
2723              ORed with the second comparison, we win.
2724              Do not do this unless the type is bool since we need a bool
2725              result here anyway.  */
2726           if (TREE_CODE (TREE_TYPE (op1a)) == BOOLEAN_TYPE)
2727             {
2728               tree result = NULL_TREE;
2729               unsigned i;
2730               for (i = 0; i < gimple_phi_num_args (stmt); i++)
2731                 {
2732                   tree arg = gimple_phi_arg_def (stmt, i);
2733
2734                   /* If this PHI has itself as an argument, ignore it.
2735                      If all the other args produce the same result,
2736                      we're still OK.  */
2737                   if (arg == gimple_phi_result (stmt))
2738                     continue;
2739                   else if (TREE_CODE (arg) == INTEGER_CST)
2740                     {
2741                       if (invert ? integer_zerop (arg) : integer_nonzerop (arg))
2742                         {
2743                           if (!result)
2744                             result = boolean_true_node;
2745                           else if (!integer_onep (result))
2746                             return NULL_TREE;
2747                         }
2748                       else if (!result)
2749                         result = fold_build2 (code2, boolean_type_node,
2750                                               op2a, op2b);
2751                       else if (!same_bool_comparison_p (result,
2752                                                         code2, op2a, op2b))
2753                         return NULL_TREE;
2754                     }
2755                   else if (TREE_CODE (arg) == SSA_NAME
2756                            && !SSA_NAME_IS_DEFAULT_DEF (arg))
2757                     {
2758                       tree temp;
2759                       gimple def_stmt = SSA_NAME_DEF_STMT (arg);
2760                       /* In simple cases we can look through PHI nodes,
2761                          but we have to be careful with loops.
2762                          See PR49073.  */
2763                       if (! dom_info_available_p (CDI_DOMINATORS)
2764                           || gimple_bb (def_stmt) == gimple_bb (stmt)
2765                           || dominated_by_p (CDI_DOMINATORS,
2766                                              gimple_bb (def_stmt),
2767                                              gimple_bb (stmt)))
2768                         return NULL_TREE;
2769                       temp = or_var_with_comparison (arg, invert, code2,
2770                                                      op2a, op2b);
2771                       if (!temp)
2772                         return NULL_TREE;
2773                       else if (!result)
2774                         result = temp;
2775                       else if (!same_bool_result_p (result, temp))
2776                         return NULL_TREE;
2777                     }
2778                   else
2779                     return NULL_TREE;
2780                 }
2781               return result;
2782             }
2783
2784         default:
2785           break;
2786         }
2787     }
2788   return NULL_TREE;
2789 }
2790
2791 /* Try to simplify the OR of two comparisons, specified by
2792    (OP1A CODE1 OP1B) and (OP2B CODE2 OP2B), respectively.
2793    If this can be simplified to a single expression (without requiring
2794    introducing more SSA variables to hold intermediate values),
2795    return the resulting tree.  Otherwise return NULL_TREE.
2796    If the result expression is non-null, it has boolean type.  */
2797
2798 tree
2799 maybe_fold_or_comparisons (enum tree_code code1, tree op1a, tree op1b,
2800                            enum tree_code code2, tree op2a, tree op2b)
2801 {
2802   tree t = or_comparisons_1 (code1, op1a, op1b, code2, op2a, op2b);
2803   if (t)
2804     return t;
2805   else
2806     return or_comparisons_1 (code2, op2a, op2b, code1, op1a, op1b);
2807 }
2808
2809
2810 /* Fold STMT to a constant using VALUEIZE to valueize SSA names.
2811
2812    Either NULL_TREE, a simplified but non-constant or a constant
2813    is returned.
2814
2815    ???  This should go into a gimple-fold-inline.h file to be eventually
2816    privatized with the single valueize function used in the various TUs
2817    to avoid the indirect function call overhead.  */
2818
2819 tree
2820 gimple_fold_stmt_to_constant_1 (gimple stmt, tree (*valueize) (tree))
2821 {
2822   location_t loc = gimple_location (stmt);
2823   switch (gimple_code (stmt))
2824     {
2825     case GIMPLE_ASSIGN:
2826       {
2827         enum tree_code subcode = gimple_assign_rhs_code (stmt);
2828
2829         switch (get_gimple_rhs_class (subcode))
2830           {
2831           case GIMPLE_SINGLE_RHS:
2832             {
2833               tree rhs = gimple_assign_rhs1 (stmt);
2834               enum tree_code_class kind = TREE_CODE_CLASS (subcode);
2835
2836               if (TREE_CODE (rhs) == SSA_NAME)
2837                 {
2838                   /* If the RHS is an SSA_NAME, return its known constant value,
2839                      if any.  */
2840                   return (*valueize) (rhs);
2841                 }
2842               /* Handle propagating invariant addresses into address
2843                  operations.  */
2844               else if (TREE_CODE (rhs) == ADDR_EXPR
2845                        && !is_gimple_min_invariant (rhs))
2846                 {
2847                   HOST_WIDE_INT offset;
2848                   tree base;
2849                   base = get_addr_base_and_unit_offset_1 (TREE_OPERAND (rhs, 0),
2850                                                           &offset,
2851                                                           valueize);
2852                   if (base
2853                       && (CONSTANT_CLASS_P (base)
2854                           || decl_address_invariant_p (base)))
2855                     return build_invariant_address (TREE_TYPE (rhs),
2856                                                     base, offset);
2857                 }
2858               else if (TREE_CODE (rhs) == CONSTRUCTOR
2859                        && TREE_CODE (TREE_TYPE (rhs)) == VECTOR_TYPE
2860                        && (CONSTRUCTOR_NELTS (rhs)
2861                            == TYPE_VECTOR_SUBPARTS (TREE_TYPE (rhs))))
2862                 {
2863                   unsigned i;
2864                   tree val, list;
2865
2866                   list = NULL_TREE;
2867                   FOR_EACH_CONSTRUCTOR_VALUE (CONSTRUCTOR_ELTS (rhs), i, val)
2868                     {
2869                       val = (*valueize) (val);
2870                       if (TREE_CODE (val) == INTEGER_CST
2871                           || TREE_CODE (val) == REAL_CST
2872                           || TREE_CODE (val) == FIXED_CST)
2873                         list = tree_cons (NULL_TREE, val, list);
2874                       else
2875                         return NULL_TREE;
2876                     }
2877
2878                   return build_vector (TREE_TYPE (rhs), nreverse (list));
2879                 }
2880
2881               if (kind == tcc_reference)
2882                 {
2883                   if ((TREE_CODE (rhs) == VIEW_CONVERT_EXPR
2884                        || TREE_CODE (rhs) == REALPART_EXPR
2885                        || TREE_CODE (rhs) == IMAGPART_EXPR)
2886                       && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
2887                     {
2888                       tree val = (*valueize) (TREE_OPERAND (rhs, 0));
2889                       return fold_unary_loc (EXPR_LOCATION (rhs),
2890                                              TREE_CODE (rhs),
2891                                              TREE_TYPE (rhs), val);
2892                     }
2893                   else if (TREE_CODE (rhs) == BIT_FIELD_REF
2894                            && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
2895                     {
2896                       tree val = (*valueize) (TREE_OPERAND (rhs, 0));
2897                       return fold_ternary_loc (EXPR_LOCATION (rhs),
2898                                                TREE_CODE (rhs),
2899                                                TREE_TYPE (rhs), val,
2900                                                TREE_OPERAND (rhs, 1),
2901                                                TREE_OPERAND (rhs, 2));
2902                     }
2903                   else if (TREE_CODE (rhs) == MEM_REF
2904                            && TREE_CODE (TREE_OPERAND (rhs, 0)) == SSA_NAME)
2905                     {
2906                       tree val = (*valueize) (TREE_OPERAND (rhs, 0));
2907                       if (TREE_CODE (val) == ADDR_EXPR
2908                           && is_gimple_min_invariant (val))
2909                         {
2910                           tree tem = fold_build2 (MEM_REF, TREE_TYPE (rhs),
2911                                                   unshare_expr (val),
2912                                                   TREE_OPERAND (rhs, 1));
2913                           if (tem)
2914                             rhs = tem;
2915                         }
2916                     }
2917                   return fold_const_aggregate_ref_1 (rhs, valueize);
2918                 }
2919               else if (kind == tcc_declaration)
2920                 return get_symbol_constant_value (rhs);
2921               return rhs;
2922             }
2923
2924           case GIMPLE_UNARY_RHS:
2925             {
2926               /* Handle unary operators that can appear in GIMPLE form.
2927                  Note that we know the single operand must be a constant,
2928                  so this should almost always return a simplified RHS.  */
2929               tree lhs = gimple_assign_lhs (stmt);
2930               tree op0 = (*valueize) (gimple_assign_rhs1 (stmt));
2931
2932               /* Conversions are useless for CCP purposes if they are
2933                  value-preserving.  Thus the restrictions that
2934                  useless_type_conversion_p places for pointer type conversions
2935                  do not apply here.  Substitution later will only substitute to
2936                  allowed places.  */
2937               if (CONVERT_EXPR_CODE_P (subcode)
2938                   && POINTER_TYPE_P (TREE_TYPE (lhs))
2939                   && POINTER_TYPE_P (TREE_TYPE (op0)))
2940                 {
2941                   tree tem;
2942                   /* Try to re-construct array references on-the-fly.  */
2943                   if (!useless_type_conversion_p (TREE_TYPE (lhs),
2944                                                   TREE_TYPE (op0))
2945                       && ((tem = maybe_fold_offset_to_address
2946                            (loc,
2947                             op0, integer_zero_node, TREE_TYPE (lhs)))
2948                           != NULL_TREE))
2949                     return tem;
2950                   return op0;
2951                 }
2952
2953               return
2954                 fold_unary_ignore_overflow_loc (loc, subcode,
2955                                                 gimple_expr_type (stmt), op0);
2956             }
2957
2958           case GIMPLE_BINARY_RHS:
2959             {
2960               /* Handle binary operators that can appear in GIMPLE form.  */
2961               tree op0 = (*valueize) (gimple_assign_rhs1 (stmt));
2962               tree op1 = (*valueize) (gimple_assign_rhs2 (stmt));
2963
2964               /* Translate &x + CST into an invariant form suitable for
2965                  further propagation.  */
2966               if (gimple_assign_rhs_code (stmt) == POINTER_PLUS_EXPR
2967                   && TREE_CODE (op0) == ADDR_EXPR
2968                   && TREE_CODE (op1) == INTEGER_CST)
2969                 {
2970                   tree off = fold_convert (ptr_type_node, op1);
2971                   return build_fold_addr_expr
2972                            (fold_build2 (MEM_REF,
2973                                          TREE_TYPE (TREE_TYPE (op0)),
2974                                          unshare_expr (op0), off));
2975                 }
2976
2977               return fold_binary_loc (loc, subcode,
2978                                       gimple_expr_type (stmt), op0, op1);
2979             }
2980
2981           case GIMPLE_TERNARY_RHS:
2982             {
2983               /* Handle ternary operators that can appear in GIMPLE form.  */
2984               tree op0 = (*valueize) (gimple_assign_rhs1 (stmt));
2985               tree op1 = (*valueize) (gimple_assign_rhs2 (stmt));
2986               tree op2 = (*valueize) (gimple_assign_rhs3 (stmt));
2987
2988               return fold_ternary_loc (loc, subcode,
2989                                        gimple_expr_type (stmt), op0, op1, op2);
2990             }
2991
2992           default:
2993             gcc_unreachable ();
2994           }
2995       }
2996
2997     case GIMPLE_CALL:
2998       {
2999         tree fn;
3000
3001         if (gimple_call_internal_p (stmt))
3002           /* No folding yet for these functions.  */
3003           return NULL_TREE;
3004
3005         fn = (*valueize) (gimple_call_fn (stmt));
3006         if (TREE_CODE (fn) == ADDR_EXPR
3007             && TREE_CODE (TREE_OPERAND (fn, 0)) == FUNCTION_DECL
3008             && DECL_BUILT_IN (TREE_OPERAND (fn, 0)))
3009           {
3010             tree *args = XALLOCAVEC (tree, gimple_call_num_args (stmt));
3011             tree call, retval;
3012             unsigned i;
3013             for (i = 0; i < gimple_call_num_args (stmt); ++i)
3014               args[i] = (*valueize) (gimple_call_arg (stmt, i));
3015             call = build_call_array_loc (loc,
3016                                          gimple_call_return_type (stmt),
3017                                          fn, gimple_call_num_args (stmt), args);
3018             retval = fold_call_expr (EXPR_LOCATION (call), call, false);
3019             if (retval)
3020               /* fold_call_expr wraps the result inside a NOP_EXPR.  */
3021               STRIP_NOPS (retval);
3022             return retval;
3023           }
3024         return NULL_TREE;
3025       }
3026
3027     default:
3028       return NULL_TREE;
3029     }
3030 }
3031
3032 /* Fold STMT to a constant using VALUEIZE to valueize SSA names.
3033    Returns NULL_TREE if folding to a constant is not possible, otherwise
3034    returns a constant according to is_gimple_min_invariant.  */
3035
3036 tree
3037 gimple_fold_stmt_to_constant (gimple stmt, tree (*valueize) (tree))
3038 {
3039   tree res = gimple_fold_stmt_to_constant_1 (stmt, valueize);
3040   if (res && is_gimple_min_invariant (res))
3041     return res;
3042   return NULL_TREE;
3043 }
3044
3045
3046 /* The following set of functions are supposed to fold references using
3047    their constant initializers.  */
3048
3049 static tree fold_ctor_reference (tree type, tree ctor,
3050                                  unsigned HOST_WIDE_INT offset,
3051                                  unsigned HOST_WIDE_INT size);
3052
3053 /* See if we can find constructor defining value of BASE.
3054    When we know the consructor with constant offset (such as
3055    base is array[40] and we do know constructor of array), then
3056    BIT_OFFSET is adjusted accordingly.
3057
3058    As a special case, return error_mark_node when constructor
3059    is not explicitly available, but it is known to be zero
3060    such as 'static const int a;'.  */
3061 static tree
3062 get_base_constructor (tree base, HOST_WIDE_INT *bit_offset,
3063                       tree (*valueize)(tree))
3064 {
3065   HOST_WIDE_INT bit_offset2, size, max_size;
3066   if (TREE_CODE (base) == MEM_REF)
3067     {
3068       if (!integer_zerop (TREE_OPERAND (base, 1)))
3069         {
3070           if (!host_integerp (TREE_OPERAND (base, 1), 0))
3071             return NULL_TREE;
3072           *bit_offset += (mem_ref_offset (base).low
3073                           * BITS_PER_UNIT);
3074         }
3075
3076       if (valueize
3077           && TREE_CODE (TREE_OPERAND (base, 0)) == SSA_NAME)
3078         base = valueize (TREE_OPERAND (base, 0));
3079       if (!base || TREE_CODE (base) != ADDR_EXPR)
3080         return NULL_TREE;
3081       base = TREE_OPERAND (base, 0);
3082     }
3083
3084   /* Get a CONSTRUCTOR.  If BASE is a VAR_DECL, get its
3085      DECL_INITIAL.  If BASE is a nested reference into another
3086      ARRAY_REF or COMPONENT_REF, make a recursive call to resolve
3087      the inner reference.  */
3088   switch (TREE_CODE (base))
3089     {
3090     case VAR_DECL:
3091       if (!const_value_known_p (base))
3092         return NULL_TREE;
3093
3094       /* Fallthru.  */
3095     case CONST_DECL:
3096       if (!DECL_INITIAL (base)
3097           && (TREE_STATIC (base) || DECL_EXTERNAL (base)))
3098         return error_mark_node;
3099       return DECL_INITIAL (base);
3100
3101     case ARRAY_REF:
3102     case COMPONENT_REF:
3103       base = get_ref_base_and_extent (base, &bit_offset2, &size, &max_size);
3104       if (max_size == -1 || size != max_size)
3105         return NULL_TREE;
3106       *bit_offset +=  bit_offset2;
3107       return get_base_constructor (base, bit_offset, valueize);
3108
3109     case STRING_CST:
3110     case CONSTRUCTOR:
3111       return base;
3112
3113     default:
3114       return NULL_TREE;
3115     }
3116 }
3117
3118 /* CTOR is STRING_CST.  Fold reference of type TYPE and size SIZE
3119    to the memory at bit OFFSET.
3120
3121    We do only simple job of folding byte accesses.  */
3122
3123 static tree
3124 fold_string_cst_ctor_reference (tree type, tree ctor,
3125                                 unsigned HOST_WIDE_INT offset,
3126                                 unsigned HOST_WIDE_INT size)
3127 {
3128   if (INTEGRAL_TYPE_P (type)
3129       && (TYPE_MODE (type)
3130           == TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
3131       && (GET_MODE_CLASS (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor))))
3132           == MODE_INT)
3133       && GET_MODE_SIZE (TYPE_MODE (TREE_TYPE (TREE_TYPE (ctor)))) == 1
3134       && size == BITS_PER_UNIT
3135       && !(offset % BITS_PER_UNIT))
3136     {
3137       offset /= BITS_PER_UNIT;
3138       if (offset < (unsigned HOST_WIDE_INT) TREE_STRING_LENGTH (ctor))
3139         return build_int_cst_type (type, (TREE_STRING_POINTER (ctor)
3140                                    [offset]));
3141       /* Folding
3142          const char a[20]="hello";
3143          return a[10];
3144
3145          might lead to offset greater than string length.  In this case we
3146          know value is either initialized to 0 or out of bounds.  Return 0
3147          in both cases.  */
3148       return build_zero_cst (type);
3149     }
3150   return NULL_TREE;
3151 }
3152
3153 /* CTOR is CONSTRUCTOR of an array type.  Fold reference of type TYPE and size
3154    SIZE to the memory at bit OFFSET.  */
3155
3156 static tree
3157 fold_array_ctor_reference (tree type, tree ctor,
3158                            unsigned HOST_WIDE_INT offset,
3159                            unsigned HOST_WIDE_INT size)
3160 {
3161   unsigned HOST_WIDE_INT cnt;
3162   tree cfield, cval;
3163   double_int low_bound, elt_size;
3164   double_int index, max_index;
3165   double_int access_index;
3166   tree domain_type = TYPE_DOMAIN (TREE_TYPE (ctor));
3167   HOST_WIDE_INT inner_offset;
3168
3169   /* Compute low bound and elt size.  */
3170   if (domain_type && TYPE_MIN_VALUE (domain_type))
3171     {
3172       /* Static constructors for variably sized objects makes no sense.  */
3173       gcc_assert (TREE_CODE (TYPE_MIN_VALUE (domain_type)) == INTEGER_CST);
3174       low_bound = tree_to_double_int (TYPE_MIN_VALUE (domain_type));
3175     }
3176   else
3177     low_bound = double_int_zero;
3178   /* Static constructors for variably sized objects makes no sense.  */
3179   gcc_assert (TREE_CODE(TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (ctor))))
3180               == INTEGER_CST);
3181   elt_size =
3182     tree_to_double_int (TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (ctor))));
3183
3184
3185   /* We can handle only constantly sized accesses that are known to not
3186      be larger than size of array element.  */
3187   if (!TYPE_SIZE_UNIT (type)
3188       || TREE_CODE (TYPE_SIZE_UNIT (type)) != INTEGER_CST
3189       || double_int_cmp (elt_size,
3190                          tree_to_double_int (TYPE_SIZE_UNIT (type)), 0) < 0)
3191     return NULL_TREE;
3192
3193   /* Compute the array index we look for.  */
3194   access_index = double_int_udiv (uhwi_to_double_int (offset / BITS_PER_UNIT),
3195                                   elt_size, TRUNC_DIV_EXPR);
3196   access_index = double_int_add (access_index, low_bound);
3197
3198   /* And offset within the access.  */
3199   inner_offset = offset % (double_int_to_uhwi (elt_size) * BITS_PER_UNIT);
3200
3201   /* See if the array field is large enough to span whole access.  We do not
3202      care to fold accesses spanning multiple array indexes.  */
3203   if (inner_offset + size > double_int_to_uhwi (elt_size) * BITS_PER_UNIT)
3204     return NULL_TREE;
3205
3206   index = double_int_sub (low_bound, double_int_one);
3207   FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield, cval)
3208     {
3209       /* Array constructor might explicitely set index, or specify range
3210          or leave index NULL meaning that it is next index after previous
3211          one.  */
3212       if (cfield)
3213         {
3214           if (TREE_CODE (cfield) == INTEGER_CST)
3215             max_index = index = tree_to_double_int (cfield);
3216           else
3217             {
3218               gcc_assert (TREE_CODE (cfield) == RANGE_EXPR);
3219               index = tree_to_double_int (TREE_OPERAND (cfield, 0));
3220               max_index = tree_to_double_int (TREE_OPERAND (cfield, 1));
3221             }
3222         }
3223       else
3224         max_index = index = double_int_add (index, double_int_one);
3225
3226       /* Do we have match?  */
3227       if (double_int_cmp (access_index, index, 1) >= 0
3228           && double_int_cmp (access_index, max_index, 1) <= 0)
3229         return fold_ctor_reference (type, cval, inner_offset, size);
3230     }
3231   /* When memory is not explicitely mentioned in constructor,
3232      it is 0 (or out of range).  */
3233   return build_zero_cst (type);
3234 }
3235
3236 /* CTOR is CONSTRUCTOR of an aggregate or vector.
3237    Fold reference of type TYPE and size SIZE to the memory at bit OFFSET.  */
3238
3239 static tree
3240 fold_nonarray_ctor_reference (tree type, tree ctor,
3241                               unsigned HOST_WIDE_INT offset,
3242                               unsigned HOST_WIDE_INT size)
3243 {
3244   unsigned HOST_WIDE_INT cnt;
3245   tree cfield, cval;
3246
3247   FOR_EACH_CONSTRUCTOR_ELT (CONSTRUCTOR_ELTS (ctor), cnt, cfield,
3248                             cval)
3249     {
3250       tree byte_offset = DECL_FIELD_OFFSET (cfield);
3251       tree field_offset = DECL_FIELD_BIT_OFFSET (cfield);
3252       tree field_size = DECL_SIZE (cfield);
3253       double_int bitoffset;
3254       double_int byte_offset_cst = tree_to_double_int (byte_offset);
3255       double_int bits_per_unit_cst = uhwi_to_double_int (BITS_PER_UNIT);
3256       double_int bitoffset_end;
3257
3258       /* Variable sized objects in static constructors makes no sense,
3259          but field_size can be NULL for flexible array members.  */
3260       gcc_assert (TREE_CODE (field_offset) == INTEGER_CST
3261                   && TREE_CODE (byte_offset) == INTEGER_CST
3262                   && (field_size != NULL_TREE
3263                       ? TREE_CODE (field_size) == INTEGER_CST
3264                       : TREE_CODE (TREE_TYPE (cfield)) == ARRAY_TYPE));
3265
3266       /* Compute bit offset of the field.  */
3267       bitoffset = double_int_add (tree_to_double_int (field_offset),
3268                                   double_int_mul (byte_offset_cst,
3269                                                   bits_per_unit_cst));
3270       /* Compute bit offset where the field ends.  */
3271       if (field_size != NULL_TREE)
3272         bitoffset_end = double_int_add (bitoffset,
3273                                         tree_to_double_int (field_size));
3274       else
3275         bitoffset_end = double_int_zero;
3276
3277       /* Is OFFSET in the range (BITOFFSET, BITOFFSET_END)?  */
3278       if (double_int_cmp (uhwi_to_double_int (offset), bitoffset, 0) >= 0
3279           && (field_size == NULL_TREE
3280               || double_int_cmp (uhwi_to_double_int (offset),
3281                                  bitoffset_end, 0) < 0))
3282         {
3283           double_int access_end = double_int_add (uhwi_to_double_int (offset),
3284                                                   uhwi_to_double_int (size));
3285           double_int inner_offset = double_int_sub (uhwi_to_double_int (offset),
3286                                                     bitoffset);
3287           /* We do have overlap.  Now see if field is large enough to
3288              cover the access.  Give up for accesses spanning multiple
3289              fields.  */
3290           if (double_int_cmp (access_end, bitoffset_end, 0) > 0)
3291             return NULL_TREE;
3292           return fold_ctor_reference (type, cval,
3293                                       double_int_to_uhwi (inner_offset), size);
3294         }
3295     }
3296   /* When memory is not explicitely mentioned in constructor, it is 0.  */
3297   return build_zero_cst (type);
3298 }
3299
3300 /* CTOR is value initializing memory, fold reference of type TYPE and size SIZE
3301    to the memory at bit OFFSET.  */
3302
3303 static tree
3304 fold_ctor_reference (tree type, tree ctor, unsigned HOST_WIDE_INT offset,
3305                      unsigned HOST_WIDE_INT size)
3306 {
3307   tree ret;
3308
3309   /* We found the field with exact match.  */
3310   if (useless_type_conversion_p (type, TREE_TYPE (ctor))
3311       && !offset)
3312     return canonicalize_constructor_val (ctor);
3313
3314   /* We are at the end of walk, see if we can view convert the
3315      result.  */
3316   if (!AGGREGATE_TYPE_P (TREE_TYPE (ctor)) && !offset
3317       /* VIEW_CONVERT_EXPR is defined only for matching sizes.  */
3318       && operand_equal_p (TYPE_SIZE (type),
3319                           TYPE_SIZE (TREE_TYPE (ctor)), 0))
3320     {
3321       ret = canonicalize_constructor_val (ctor);
3322       ret = fold_unary (VIEW_CONVERT_EXPR, type, ret);
3323       if (ret)
3324         STRIP_NOPS (ret);
3325       return ret;
3326     }
3327   if (TREE_CODE (ctor) == STRING_CST)
3328     return fold_string_cst_ctor_reference (type, ctor, offset, size);
3329   if (TREE_CODE (ctor) == CONSTRUCTOR)
3330     {
3331
3332       if (TREE_CODE (TREE_TYPE (ctor)) == ARRAY_TYPE)
3333         return fold_array_ctor_reference (type, ctor, offset, size);
3334       else
3335         return fold_nonarray_ctor_reference (type, ctor, offset, size);
3336     }
3337
3338   return NULL_TREE;
3339 }
3340
3341 /* Return the tree representing the element referenced by T if T is an
3342    ARRAY_REF or COMPONENT_REF into constant aggregates valuezing SSA
3343    names using VALUEIZE.  Return NULL_TREE otherwise.  */
3344
3345 tree
3346 fold_const_aggregate_ref_1 (tree t, tree (*valueize) (tree))
3347 {
3348   tree ctor, idx, base;
3349   HOST_WIDE_INT offset, size, max_size;
3350   tree tem;
3351
3352   if (TREE_CODE_CLASS (TREE_CODE (t)) == tcc_declaration)
3353     return get_symbol_constant_value (t);
3354
3355   tem = fold_read_from_constant_string (t);
3356   if (tem)
3357     return tem;
3358
3359   switch (TREE_CODE (t))
3360     {
3361     case ARRAY_REF:
3362     case ARRAY_RANGE_REF:
3363       /* Constant indexes are handled well by get_base_constructor.
3364          Only special case variable offsets.
3365          FIXME: This code can't handle nested references with variable indexes
3366          (they will be handled only by iteration of ccp).  Perhaps we can bring
3367          get_ref_base_and_extent here and make it use a valueize callback.  */
3368       if (TREE_CODE (TREE_OPERAND (t, 1)) == SSA_NAME
3369           && valueize
3370           && (idx = (*valueize) (TREE_OPERAND (t, 1)))
3371           && host_integerp (idx, 0))
3372         {
3373           tree low_bound, unit_size;
3374
3375           /* If the resulting bit-offset is constant, track it.  */
3376           if ((low_bound = array_ref_low_bound (t),
3377                host_integerp (low_bound, 0))
3378               && (unit_size = array_ref_element_size (t),
3379                   host_integerp (unit_size, 1)))
3380             {
3381               offset = TREE_INT_CST_LOW (idx);
3382               offset -= TREE_INT_CST_LOW (low_bound);
3383               offset *= TREE_INT_CST_LOW (unit_size);
3384               offset *= BITS_PER_UNIT;
3385
3386               base = TREE_OPERAND (t, 0);
3387               ctor = get_base_constructor (base, &offset, valueize);
3388               /* Empty constructor.  Always fold to 0.  */
3389               if (ctor == error_mark_node)
3390                 return build_zero_cst (TREE_TYPE (t));
3391               /* Out of bound array access.  Value is undefined,
3392                  but don't fold.  */
3393               if (offset < 0)
3394                 return NULL_TREE;
3395               /* We can not determine ctor.  */
3396               if (!ctor)
3397                 return NULL_TREE;
3398               return fold_ctor_reference (TREE_TYPE (t), ctor, offset,
3399                                           TREE_INT_CST_LOW (unit_size)
3400                                           * BITS_PER_UNIT);
3401             }
3402         }
3403       /* Fallthru.  */
3404
3405     case COMPONENT_REF:
3406     case BIT_FIELD_REF:
3407     case TARGET_MEM_REF:
3408     case MEM_REF:
3409       base = get_ref_base_and_extent (t, &offset, &size, &max_size);
3410       ctor = get_base_constructor (base, &offset, valueize);
3411
3412       /* Empty constructor.  Always fold to 0.  */
3413       if (ctor == error_mark_node)
3414         return build_zero_cst (TREE_TYPE (t));
3415       /* We do not know precise address.  */
3416       if (max_size == -1 || max_size != size)
3417         return NULL_TREE;
3418       /* We can not determine ctor.  */
3419       if (!ctor)
3420         return NULL_TREE;
3421
3422       /* Out of bound array access.  Value is undefined, but don't fold.  */
3423       if (offset < 0)
3424         return NULL_TREE;
3425
3426       return fold_ctor_reference (TREE_TYPE (t), ctor, offset, size);
3427
3428     case REALPART_EXPR:
3429     case IMAGPART_EXPR:
3430       {
3431         tree c = fold_const_aggregate_ref_1 (TREE_OPERAND (t, 0), valueize);
3432         if (c && TREE_CODE (c) == COMPLEX_CST)
3433           return fold_build1_loc (EXPR_LOCATION (t),
3434                               TREE_CODE (t), TREE_TYPE (t), c);
3435         break;
3436       }
3437
3438     default:
3439       break;
3440     }
3441
3442   return NULL_TREE;
3443 }
3444
3445 tree
3446 fold_const_aggregate_ref (tree t)
3447 {
3448   return fold_const_aggregate_ref_1 (t, NULL);
3449 }
3450
3451 /* Return true iff VAL is a gimple expression that is known to be
3452    non-negative.  Restricted to floating-point inputs.  */
3453
3454 bool
3455 gimple_val_nonnegative_real_p (tree val)
3456 {
3457   gimple def_stmt;
3458
3459   gcc_assert (val && SCALAR_FLOAT_TYPE_P (TREE_TYPE (val)));
3460
3461   /* Use existing logic for non-gimple trees.  */
3462   if (tree_expr_nonnegative_p (val))
3463     return true;
3464
3465   if (TREE_CODE (val) != SSA_NAME)
3466     return false;
3467
3468   /* Currently we look only at the immediately defining statement
3469      to make this determination, since recursion on defining
3470      statements of operands can lead to quadratic behavior in the
3471      worst case.  This is expected to catch almost all occurrences
3472      in practice.  It would be possible to implement limited-depth
3473      recursion if important cases are lost.  Alternatively, passes
3474      that need this information (such as the pow/powi lowering code
3475      in the cse_sincos pass) could be revised to provide it through
3476      dataflow propagation.  */
3477
3478   def_stmt = SSA_NAME_DEF_STMT (val);
3479
3480   if (is_gimple_assign (def_stmt))
3481     {
3482       tree op0, op1;
3483
3484       /* See fold-const.c:tree_expr_nonnegative_p for additional
3485          cases that could be handled with recursion.  */
3486
3487       switch (gimple_assign_rhs_code (def_stmt))
3488         {
3489         case ABS_EXPR:
3490           /* Always true for floating-point operands.  */
3491           return true;
3492
3493         case MULT_EXPR:
3494           /* True if the two operands are identical (since we are
3495              restricted to floating-point inputs).  */
3496           op0 = gimple_assign_rhs1 (def_stmt);
3497           op1 = gimple_assign_rhs2 (def_stmt);
3498
3499           if (op0 == op1
3500               || operand_equal_p (op0, op1, 0))
3501             return true;
3502
3503         default:
3504           return false;
3505         }
3506     }
3507   else if (is_gimple_call (def_stmt))
3508     {
3509       tree fndecl = gimple_call_fndecl (def_stmt);
3510       if (fndecl
3511           && DECL_BUILT_IN_CLASS (fndecl) == BUILT_IN_NORMAL)
3512         {
3513           tree arg1;
3514
3515           switch (DECL_FUNCTION_CODE (fndecl))
3516             {
3517             CASE_FLT_FN (BUILT_IN_ACOS):
3518             CASE_FLT_FN (BUILT_IN_ACOSH):
3519             CASE_FLT_FN (BUILT_IN_CABS):
3520             CASE_FLT_FN (BUILT_IN_COSH):
3521             CASE_FLT_FN (BUILT_IN_ERFC):
3522             CASE_FLT_FN (BUILT_IN_EXP):
3523             CASE_FLT_FN (BUILT_IN_EXP10):
3524             CASE_FLT_FN (BUILT_IN_EXP2):
3525             CASE_FLT_FN (BUILT_IN_FABS):
3526             CASE_FLT_FN (BUILT_IN_FDIM):
3527             CASE_FLT_FN (BUILT_IN_HYPOT):
3528             CASE_FLT_FN (BUILT_IN_POW10):
3529               return true;
3530
3531             CASE_FLT_FN (BUILT_IN_SQRT):
3532               /* sqrt(-0.0) is -0.0, and sqrt is not defined over other
3533                  nonnegative inputs.  */
3534               if (!HONOR_SIGNED_ZEROS (TYPE_MODE (TREE_TYPE (val))))
3535                 return true;
3536
3537               break;
3538
3539             CASE_FLT_FN (BUILT_IN_POWI):
3540               /* True if the second argument is an even integer.  */
3541               arg1 = gimple_call_arg (def_stmt, 1);
3542
3543               if (TREE_CODE (arg1) == INTEGER_CST
3544                   && (TREE_INT_CST_LOW (arg1) & 1) == 0)
3545                 return true;
3546
3547               break;
3548
3549             CASE_FLT_FN (BUILT_IN_POW):
3550               /* True if the second argument is an even integer-valued
3551                  real.  */
3552               arg1 = gimple_call_arg (def_stmt, 1);
3553
3554               if (TREE_CODE (arg1) == REAL_CST)
3555                 {
3556                   REAL_VALUE_TYPE c;
3557                   HOST_WIDE_INT n;
3558
3559                   c = TREE_REAL_CST (arg1);
3560                   n = real_to_integer (&c);
3561
3562                   if ((n & 1) == 0)
3563                     {
3564                       REAL_VALUE_TYPE cint;
3565                       real_from_integer (&cint, VOIDmode, n, n < 0 ? -1 : 0, 0);
3566                       if (real_identical (&c, &cint))
3567                         return true;
3568                     }
3569                 }
3570
3571               break;
3572
3573             default:
3574               return false;
3575             }
3576         }
3577     }
3578
3579   return false;
3580 }