gcc/tree-ssa-ccp.c

   1 /* Conditional constant propagation pass for the GNU compiler.
   2    Copyright (C) 2000-2017 Free Software Foundation, Inc.
   3    Adapted from original RTL SSA-CCP by Daniel Berlin <dberlin@dberlin.org>
   4    Adapted to GIMPLE trees by Diego Novillo <dnovillo@redhat.com>
   5
   6 This file is part of GCC.
   7
   8 GCC is free software; you can redistribute it and/or modify it
   9 under the terms of the GNU General Public License as published by the
  10 Free Software Foundation; either version 3, or (at your option) any
  11 later version.
  12
  13 GCC is distributed in the hope that it will be useful, but WITHOUT
  14 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  15 FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  16 for more details.
  17
  18 You should have received a copy of the GNU General Public License
  19 along with GCC; see the file COPYING3.  If not see
  20 <http://www.gnu.org/licenses/>.  */
  21
  22 /* Conditional constant propagation (CCP) is based on the SSA
  23    propagation engine (tree-ssa-propagate.c).  Constant assignments of
  24    the form VAR = CST are propagated from the assignments into uses of
  25    VAR, which in turn may generate new constants.  The simulation uses
  26    a four level lattice to keep track of constant values associated
  27    with SSA names.  Given an SSA name V_i, it may take one of the
  28    following values:
  29
  30         UNINITIALIZED   ->  the initial state of the value.  This value
  31                             is replaced with a correct initial value
  32                             the first time the value is used, so the
  33                             rest of the pass does not need to care about
  34                             it.  Using this value simplifies initialization
  35                             of the pass, and prevents us from needlessly
  36                             scanning statements that are never reached.
  37
  38         UNDEFINED       ->  V_i is a local variable whose definition
  39                             has not been processed yet.  Therefore we
  40                             don't yet know if its value is a constant
  41                             or not.
  42
  43         CONSTANT        ->  V_i has been found to hold a constant
  44                             value C.
  45
  46         VARYING         ->  V_i cannot take a constant value, or if it
  47                             does, it is not possible to determine it
  48                             at compile time.
  49
  50    The core of SSA-CCP is in ccp_visit_stmt and ccp_visit_phi_node:
  51
  52    1- In ccp_visit_stmt, we are interested in assignments whose RHS
  53       evaluates into a constant and conditional jumps whose predicate
  54       evaluates into a boolean true or false.  When an assignment of
  55       the form V_i = CONST is found, V_i's lattice value is set to
  56       CONSTANT and CONST is associated with it.  This causes the
  57       propagation engine to add all the SSA edges coming out the
  58       assignment into the worklists, so that statements that use V_i
  59       can be visited.
  60
  61       If the statement is a conditional with a constant predicate, we
  62       mark the outgoing edges as executable or not executable
  63       depending on the predicate's value.  This is then used when
  64       visiting PHI nodes to know when a PHI argument can be ignored.
  65
  66
  67    2- In ccp_visit_phi_node, if all the PHI arguments evaluate to the
  68       same constant C, then the LHS of the PHI is set to C.  This
  69       evaluation is known as the "meet operation".  Since one of the
  70       goals of this evaluation is to optimistically return constant
  71       values as often as possible, it uses two main short cuts:
  72
  73       - If an argument is flowing in through a non-executable edge, it
  74         is ignored.  This is useful in cases like this:
  75
  76                         if (PRED)
  77                           a_9 = 3;
  78                         else
  79                           a_10 = 100;
  80                         a_11 = PHI (a_9, a_10)
  81
  82         If PRED is known to always evaluate to false, then we can
  83         assume that a_11 will always take its value from a_10, meaning
  84         that instead of consider it VARYING (a_9 and a_10 have
  85         different values), we can consider it CONSTANT 100.
  86
  87       - If an argument has an UNDEFINED value, then it does not affect
  88         the outcome of the meet operation.  If a variable V_i has an
  89         UNDEFINED value, it means that either its defining statement
  90         hasn't been visited yet or V_i has no defining statement, in
  91         which case the original symbol 'V' is being used
  92         uninitialized.  Since 'V' is a local variable, the compiler
  93         may assume any initial value for it.
  94
  95
  96    After propagation, every variable V_i that ends up with a lattice
  97    value of CONSTANT will have the associated constant value in the
  98    array CONST_VAL[i].VALUE.  That is fed into substitute_and_fold for
  99    final substitution and folding.
 100
 101    This algorithm uses wide-ints at the max precision of the target.
 102    This means that, with one uninteresting exception, variables with
 103    UNSIGNED types never go to VARYING because the bits above the
 104    precision of the type of the variable are always zero.  The
 105    uninteresting case is a variable of UNSIGNED type that has the
 106    maximum precision of the target.  Such variables can go to VARYING,
 107    but this causes no loss of infomation since these variables will
 108    never be extended.
 109
 110    References:
 111
 112      Constant propagation with conditional branches,
 113      Wegman and Zadeck, ACM TOPLAS 13(2):181-210.
 114
 115      Building an Optimizing Compiler,
 116      Robert Morgan, Butterworth-Heinemann, 1998, Section 8.9.
 117
 118      Advanced Compiler Design and Implementation,
 119      Steven Muchnick, Morgan Kaufmann, 1997, Section 12.6  */
 120
 121 #include "config.h"
 122 #include "system.h"
 123 #include "coretypes.h"
 124 #include "backend.h"
 125 #include "target.h"
 126 #include "tree.h"
 127 #include "gimple.h"
 128 #include "tree-pass.h"
 129 #include "ssa.h"
 130 #include "gimple-pretty-print.h"
 131 #include "fold-const.h"
 132 #include "gimple-fold.h"
 133 #include "tree-eh.h"
 134 #include "gimplify.h"
 135 #include "gimple-iterator.h"
 136 #include "tree-cfg.h"
 137 #include "tree-ssa-propagate.h"
 138 #include "dbgcnt.h"
 139 #include "params.h"
 140 #include "builtins.h"
 141 #include "tree-chkp.h"
 142 #include "cfgloop.h"
 143 #include "stor-layout.h"
 144 #include "optabs-query.h"
 145 #include "tree-ssa-ccp.h"
 146 #include "tree-dfa.h"
 147 #include "diagnostic-core.h"
 148
 149 /* Possible lattice values.  */
 150 typedef enum
 151 {
 152   UNINITIALIZED,
 153   UNDEFINED,
 154   CONSTANT,
 155   VARYING
 156 } ccp_lattice_t;
 157
 158 struct ccp_prop_value_t {
 159     /* Lattice value.  */
 160     ccp_lattice_t lattice_val;
 161
 162     /* Propagated value.  */
 163     tree value;
 164
 165     /* Mask that applies to the propagated value during CCP.  For X
 166        with a CONSTANT lattice value X & ~mask == value & ~mask.  The
 167        zero bits in the mask cover constant values.  The ones mean no
 168        information.  */
 169     widest_int mask;
 170 };
 171
 172 /* Array of propagated constant values.  After propagation,
 173    CONST_VAL[I].VALUE holds the constant value for SSA_NAME(I).  If
 174    the constant is held in an SSA name representing a memory store
 175    (i.e., a VDEF), CONST_VAL[I].MEM_REF will contain the actual
 176    memory reference used to store (i.e., the LHS of the assignment
 177    doing the store).  */
 178 static ccp_prop_value_t *const_val;
 179 static unsigned n_const_val;
 180
 181 static void canonicalize_value (ccp_prop_value_t *);
 182 static bool ccp_fold_stmt (gimple_stmt_iterator *);
 183 static void ccp_lattice_meet (ccp_prop_value_t *, ccp_prop_value_t *);
 184
 185 /* Dump constant propagation value VAL to file OUTF prefixed by PREFIX.  */
 186
 187 static void
 188 dump_lattice_value (FILE *outf, const char *prefix, ccp_prop_value_t val)
 189 {
 190   switch (val.lattice_val)
 191     {
 192     case UNINITIALIZED:
 193       fprintf (outf, "%sUNINITIALIZED", prefix);
 194       break;
 195     case UNDEFINED:
 196       fprintf (outf, "%sUNDEFINED", prefix);
 197       break;
 198     case VARYING:
 199       fprintf (outf, "%sVARYING", prefix);
 200       break;
 201     case CONSTANT:
 202       if (TREE_CODE (val.value) != INTEGER_CST
 203           || val.mask == 0)
 204         {
 205           fprintf (outf, "%sCONSTANT ", prefix);
 206           print_generic_expr (outf, val.value, dump_flags);
 207         }
 208       else
 209         {
 210           widest_int cval = wi::bit_and_not (wi::to_widest (val.value),
 211                                              val.mask);
 212           fprintf (outf, "%sCONSTANT ", prefix);
 213           print_hex (cval, outf);
 214           fprintf (outf, " (");
 215           print_hex (val.mask, outf);
 216           fprintf (outf, ")");
 217         }
 218       break;
 219     default:
 220       gcc_unreachable ();
 221     }
 222 }
 223
 224
 225 /* Print lattice value VAL to stderr.  */
 226
 227 void debug_lattice_value (ccp_prop_value_t val);
 228
 229 DEBUG_FUNCTION void
 230 debug_lattice_value (ccp_prop_value_t val)
 231 {
 232   dump_lattice_value (stderr, "", val);
 233   fprintf (stderr, "\n");
 234 }
 235
 236 /* Extend NONZERO_BITS to a full mask, based on sgn.  */
 237
 238 static widest_int
 239 extend_mask (const wide_int &nonzero_bits, signop sgn)
 240 {
 241   return widest_int::from (nonzero_bits, sgn);
 242 }
 243
 244 /* Compute a default value for variable VAR and store it in the
 245    CONST_VAL array.  The following rules are used to get default
 246    values:
 247
 248    1- Global and static variables that are declared constant are
 249       considered CONSTANT.
 250
 251    2- Any other value is considered UNDEFINED.  This is useful when
 252       considering PHI nodes.  PHI arguments that are undefined do not
 253       change the constant value of the PHI node, which allows for more
 254       constants to be propagated.
 255
 256    3- Variables defined by statements other than assignments and PHI
 257       nodes are considered VARYING.
 258
 259    4- Initial values of variables that are not GIMPLE registers are
 260       considered VARYING.  */
 261
 262 static ccp_prop_value_t
 263 get_default_value (tree var)
 264 {
 265   ccp_prop_value_t val = { UNINITIALIZED, NULL_TREE, 0 };
 266   gimple *stmt;
 267
 268   stmt = SSA_NAME_DEF_STMT (var);
 269
 270   if (gimple_nop_p (stmt))
 271     {
 272       /* Variables defined by an empty statement are those used
 273          before being initialized.  If VAR is a local variable, we
 274          can assume initially that it is UNDEFINED, otherwise we must
 275          consider it VARYING.  */
 276       if (!virtual_operand_p (var)
 277           && SSA_NAME_VAR (var)
 278           && TREE_CODE (SSA_NAME_VAR (var)) == VAR_DECL)
 279         val.lattice_val = UNDEFINED;
 280       else
 281         {
 282           val.lattice_val = VARYING;
 283           val.mask = -1;
 284           if (flag_tree_bit_ccp)
 285             {
 286               wide_int nonzero_bits = get_nonzero_bits (var);
 287               if (nonzero_bits != -1)
 288                 {
 289                   val.lattice_val = CONSTANT;
 290                   val.value = build_zero_cst (TREE_TYPE (var));
 291                   val.mask = extend_mask (nonzero_bits, TYPE_SIGN (TREE_TYPE (var)));
 292                 }
 293             }
 294         }
 295     }
 296   else if (is_gimple_assign (stmt))
 297     {
 298       tree cst;
 299       if (gimple_assign_single_p (stmt)
 300           && DECL_P (gimple_assign_rhs1 (stmt))
 301           && (cst = get_symbol_constant_value (gimple_assign_rhs1 (stmt))))
 302         {
 303           val.lattice_val = CONSTANT;
 304           val.value = cst;
 305         }
 306       else
 307         {
 308           /* Any other variable defined by an assignment is considered
 309              UNDEFINED.  */
 310           val.lattice_val = UNDEFINED;
 311         }
 312     }
 313   else if ((is_gimple_call (stmt)
 314             && gimple_call_lhs (stmt) != NULL_TREE)
 315            || gimple_code (stmt) == GIMPLE_PHI)
 316     {
 317       /* A variable defined by a call or a PHI node is considered
 318          UNDEFINED.  */
 319       val.lattice_val = UNDEFINED;
 320     }
 321   else
 322     {
 323       /* Otherwise, VAR will never take on a constant value.  */
 324       val.lattice_val = VARYING;
 325       val.mask = -1;
 326     }
 327
 328   return val;
 329 }
 330
 331
 332 /* Get the constant value associated with variable VAR.  */
 333
 334 static inline ccp_prop_value_t *
 335 get_value (tree var)
 336 {
 337   ccp_prop_value_t *val;
 338
 339   if (const_val == NULL
 340       || SSA_NAME_VERSION (var) >= n_const_val)
 341     return NULL;
 342
 343   val = &const_val[SSA_NAME_VERSION (var)];
 344   if (val->lattice_val == UNINITIALIZED)
 345     *val = get_default_value (var);
 346
 347   canonicalize_value (val);
 348
 349   return val;
 350 }
 351
 352 /* Return the constant tree value associated with VAR.  */
 353
 354 static inline tree
 355 get_constant_value (tree var)
 356 {
 357   ccp_prop_value_t *val;
 358   if (TREE_CODE (var) != SSA_NAME)
 359     {
 360       if (is_gimple_min_invariant (var))
 361         return var;
 362       return NULL_TREE;
 363     }
 364   val = get_value (var);
 365   if (val
 366       && val->lattice_val == CONSTANT
 367       && (TREE_CODE (val->value) != INTEGER_CST
 368           || val->mask == 0))
 369     return val->value;
 370   return NULL_TREE;
 371 }
 372
 373 /* Sets the value associated with VAR to VARYING.  */
 374
 375 static inline void
 376 set_value_varying (tree var)
 377 {
 378   ccp_prop_value_t *val = &const_val[SSA_NAME_VERSION (var)];
 379
 380   val->lattice_val = VARYING;
 381   val->value = NULL_TREE;
 382   val->mask = -1;
 383 }
 384
 385 /* For integer constants, make sure to drop TREE_OVERFLOW.  */
 386
 387 static void
 388 canonicalize_value (ccp_prop_value_t *val)
 389 {
 390   if (val->lattice_val != CONSTANT)
 391     return;
 392
 393   if (TREE_OVERFLOW_P (val->value))
 394     val->value = drop_tree_overflow (val->value);
 395 }
 396
 397 /* Return whether the lattice transition is valid.  */
 398
 399 static bool
 400 valid_lattice_transition (ccp_prop_value_t old_val, ccp_prop_value_t new_val)
 401 {
 402   /* Lattice transitions must always be monotonically increasing in
 403      value.  */
 404   if (old_val.lattice_val < new_val.lattice_val)
 405     return true;
 406
 407   if (old_val.lattice_val != new_val.lattice_val)
 408     return false;
 409
 410   if (!old_val.value && !new_val.value)
 411     return true;
 412
 413   /* Now both lattice values are CONSTANT.  */
 414
 415   /* Allow arbitrary copy changes as we might look through PHI <a_1, ...>
 416      when only a single copy edge is executable.  */
 417   if (TREE_CODE (old_val.value) == SSA_NAME
 418       && TREE_CODE (new_val.value) == SSA_NAME)
 419     return true;
 420
 421   /* Allow transitioning from a constant to a copy.  */
 422   if (is_gimple_min_invariant (old_val.value)
 423       && TREE_CODE (new_val.value) == SSA_NAME)
 424     return true;
 425
 426   /* Allow transitioning from PHI <&x, not executable> == &x
 427      to PHI <&x, &y> == common alignment.  */
 428   if (TREE_CODE (old_val.value) != INTEGER_CST
 429       && TREE_CODE (new_val.value) == INTEGER_CST)
 430     return true;
 431
 432   /* Bit-lattices have to agree in the still valid bits.  */
 433   if (TREE_CODE (old_val.value) == INTEGER_CST
 434       && TREE_CODE (new_val.value) == INTEGER_CST)
 435     return (wi::bit_and_not (wi::to_widest (old_val.value), new_val.mask)
 436             == wi::bit_and_not (wi::to_widest (new_val.value), new_val.mask));
 437
 438   /* Otherwise constant values have to agree.  */
 439   if (operand_equal_p (old_val.value, new_val.value, 0))
 440     return true;
 441
 442   /* At least the kinds and types should agree now.  */
 443   if (TREE_CODE (old_val.value) != TREE_CODE (new_val.value)
 444       || !types_compatible_p (TREE_TYPE (old_val.value),
 445                               TREE_TYPE (new_val.value)))
 446     return false;
 447
 448   /* For floats and !HONOR_NANS allow transitions from (partial) NaN
 449      to non-NaN.  */
 450   tree type = TREE_TYPE (new_val.value);
 451   if (SCALAR_FLOAT_TYPE_P (type)
 452       && !HONOR_NANS (type))
 453     {
 454       if (REAL_VALUE_ISNAN (TREE_REAL_CST (old_val.value)))
 455         return true;
 456     }
 457   else if (VECTOR_FLOAT_TYPE_P (type)
 458            && !HONOR_NANS (type))
 459     {
 460       for (unsigned i = 0; i < VECTOR_CST_NELTS (old_val.value); ++i)
 461         if (!REAL_VALUE_ISNAN
 462                (TREE_REAL_CST (VECTOR_CST_ELT (old_val.value, i)))
 463             && !operand_equal_p (VECTOR_CST_ELT (old_val.value, i),
 464                                  VECTOR_CST_ELT (new_val.value, i), 0))
 465           return false;
 466       return true;
 467     }
 468   else if (COMPLEX_FLOAT_TYPE_P (type)
 469            && !HONOR_NANS (type))
 470     {
 471       if (!REAL_VALUE_ISNAN (TREE_REAL_CST (TREE_REALPART (old_val.value)))
 472           && !operand_equal_p (TREE_REALPART (old_val.value),
 473                                TREE_REALPART (new_val.value), 0))
 474         return false;
 475       if (!REAL_VALUE_ISNAN (TREE_REAL_CST (TREE_IMAGPART (old_val.value)))
 476           && !operand_equal_p (TREE_IMAGPART (old_val.value),
 477                                TREE_IMAGPART (new_val.value), 0))
 478         return false;
 479       return true;
 480     }
 481   return false;
 482 }
 483
 484 /* Set the value for variable VAR to NEW_VAL.  Return true if the new
 485    value is different from VAR's previous value.  */
 486
 487 static bool
 488 set_lattice_value (tree var, ccp_prop_value_t *new_val)
 489 {
 490   /* We can deal with old UNINITIALIZED values just fine here.  */
 491   ccp_prop_value_t *old_val = &const_val[SSA_NAME_VERSION (var)];
 492
 493   canonicalize_value (new_val);
 494
 495   /* We have to be careful to not go up the bitwise lattice
 496      represented by the mask.  Instead of dropping to VARYING
 497      use the meet operator to retain a conservative value.
 498      Missed optimizations like PR65851 makes this necessary.
 499      It also ensures we converge to a stable lattice solution.  */
 500   if (new_val->lattice_val == CONSTANT
 501       && old_val->lattice_val == CONSTANT
 502       && TREE_CODE (new_val->value) != SSA_NAME)
 503     ccp_lattice_meet (new_val, old_val);
 504
 505   gcc_checking_assert (valid_lattice_transition (*old_val, *new_val));
 506
 507   /* If *OLD_VAL and NEW_VAL are the same, return false to inform the
 508      caller that this was a non-transition.  */
 509   if (old_val->lattice_val != new_val->lattice_val
 510       || (new_val->lattice_val == CONSTANT
 511           && (TREE_CODE (new_val->value) != TREE_CODE (old_val->value)
 512               || (TREE_CODE (new_val->value) == INTEGER_CST
 513                   && (new_val->mask != old_val->mask
 514                       || (wi::bit_and_not (wi::to_widest (old_val->value),
 515                                            new_val->mask)
 516                           != wi::bit_and_not (wi::to_widest (new_val->value),
 517                                               new_val->mask))))
 518               || (TREE_CODE (new_val->value) != INTEGER_CST
 519                   && !operand_equal_p (new_val->value, old_val->value, 0)))))
 520     {
 521       /* ???  We would like to delay creation of INTEGER_CSTs from
 522          partially constants here.  */
 523
 524       if (dump_file && (dump_flags & TDF_DETAILS))
 525         {
 526           dump_lattice_value (dump_file, "Lattice value changed to ", *new_val);
 527           fprintf (dump_file, ".  Adding SSA edges to worklist.\n");
 528         }
 529
 530       *old_val = *new_val;
 531
 532       gcc_assert (new_val->lattice_val != UNINITIALIZED);
 533       return true;
 534     }
 535
 536   return false;
 537 }
 538
 539 static ccp_prop_value_t get_value_for_expr (tree, bool);
 540 static ccp_prop_value_t bit_value_binop (enum tree_code, tree, tree, tree);
 541 void bit_value_binop (enum tree_code, signop, int, widest_int *, widest_int *,
 542                       signop, int, const widest_int &, const widest_int &,
 543                       signop, int, const widest_int &, const widest_int &);
 544
 545 /* Return a widest_int that can be used for bitwise simplifications
 546    from VAL.  */
 547
 548 static widest_int
 549 value_to_wide_int (ccp_prop_value_t val)
 550 {
 551   if (val.value
 552       && TREE_CODE (val.value) == INTEGER_CST)
 553     return wi::to_widest (val.value);
 554
 555   return 0;
 556 }
 557
 558 /* Return the value for the address expression EXPR based on alignment
 559    information.  */
 560
 561 static ccp_prop_value_t
 562 get_value_from_alignment (tree expr)
 563 {
 564   tree type = TREE_TYPE (expr);
 565   ccp_prop_value_t val;
 566   unsigned HOST_WIDE_INT bitpos;
 567   unsigned int align;
 568
 569   gcc_assert (TREE_CODE (expr) == ADDR_EXPR);
 570
 571   get_pointer_alignment_1 (expr, &align, &bitpos);
 572   val.mask = (POINTER_TYPE_P (type) || TYPE_UNSIGNED (type)
 573               ? wi::mask <widest_int> (TYPE_PRECISION (type), false)
 574               : -1).and_not (align / BITS_PER_UNIT - 1);
 575   val.lattice_val
 576     = wi::sext (val.mask, TYPE_PRECISION (type)) == -1 ? VARYING : CONSTANT;
 577   if (val.lattice_val == CONSTANT)
 578     val.value = build_int_cstu (type, bitpos / BITS_PER_UNIT);
 579   else
 580     val.value = NULL_TREE;
 581
 582   return val;
 583 }
 584
 585 /* Return the value for the tree operand EXPR.  If FOR_BITS_P is true
 586    return constant bits extracted from alignment information for
 587    invariant addresses.  */
 588
 589 static ccp_prop_value_t
 590 get_value_for_expr (tree expr, bool for_bits_p)
 591 {
 592   ccp_prop_value_t val;
 593
 594   if (TREE_CODE (expr) == SSA_NAME)
 595     {
 596       ccp_prop_value_t *val_ = get_value (expr);
 597       if (val_)
 598         val = *val_;
 599       else
 600         {
 601           val.lattice_val = VARYING;
 602           val.value = NULL_TREE;
 603           val.mask = -1;
 604         }
 605       if (for_bits_p
 606           && val.lattice_val == CONSTANT
 607           && TREE_CODE (val.value) == ADDR_EXPR)
 608         val = get_value_from_alignment (val.value);
 609       /* Fall back to a copy value.  */
 610       if (!for_bits_p
 611           && val.lattice_val == VARYING
 612           && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (expr))
 613         {
 614           val.lattice_val = CONSTANT;
 615           val.value = expr;
 616           val.mask = -1;
 617         }
 618     }
 619   else if (is_gimple_min_invariant (expr)
 620            && (!for_bits_p || TREE_CODE (expr) != ADDR_EXPR))
 621     {
 622       val.lattice_val = CONSTANT;
 623       val.value = expr;
 624       val.mask = 0;
 625       canonicalize_value (&val);
 626     }
 627   else if (TREE_CODE (expr) == ADDR_EXPR)
 628     val = get_value_from_alignment (expr);
 629   else
 630     {
 631       val.lattice_val = VARYING;
 632       val.mask = -1;
 633       val.value = NULL_TREE;
 634     }
 635
 636   if (val.lattice_val == VARYING
 637       && TYPE_UNSIGNED (TREE_TYPE (expr)))
 638     val.mask = wi::zext (val.mask, TYPE_PRECISION (TREE_TYPE (expr)));
 639
 640   return val;
 641 }
 642
 643 /* Return the likely CCP lattice value for STMT.
 644
 645    If STMT has no operands, then return CONSTANT.
 646
 647    Else if undefinedness of operands of STMT cause its value to be
 648    undefined, then return UNDEFINED.
 649
 650    Else if any operands of STMT are constants, then return CONSTANT.
 651
 652    Else return VARYING.  */
 653
 654 static ccp_lattice_t
 655 likely_value (gimple *stmt)
 656 {
 657   bool has_constant_operand, has_undefined_operand, all_undefined_operands;
 658   bool has_nsa_operand;
 659   tree use;
 660   ssa_op_iter iter;
 661   unsigned i;
 662
 663   enum gimple_code code = gimple_code (stmt);
 664
 665   /* This function appears to be called only for assignments, calls,
 666      conditionals, and switches, due to the logic in visit_stmt.  */
 667   gcc_assert (code == GIMPLE_ASSIGN
 668               || code == GIMPLE_CALL
 669               || code == GIMPLE_COND
 670               || code == GIMPLE_SWITCH);
 671
 672   /* If the statement has volatile operands, it won't fold to a
 673      constant value.  */
 674   if (gimple_has_volatile_ops (stmt))
 675     return VARYING;
 676
 677   /* Arrive here for more complex cases.  */
 678   has_constant_operand = false;
 679   has_undefined_operand = false;
 680   all_undefined_operands = true;
 681   has_nsa_operand = false;
 682   FOR_EACH_SSA_TREE_OPERAND (use, stmt, iter, SSA_OP_USE)
 683     {
 684       ccp_prop_value_t *val = get_value (use);
 685
 686       if (val && val->lattice_val == UNDEFINED)
 687         has_undefined_operand = true;
 688       else
 689         all_undefined_operands = false;
 690
 691       if (val && val->lattice_val == CONSTANT)
 692         has_constant_operand = true;
 693
 694       if (SSA_NAME_IS_DEFAULT_DEF (use)
 695           || !prop_simulate_again_p (SSA_NAME_DEF_STMT (use)))
 696         has_nsa_operand = true;
 697     }
 698
 699   /* There may be constants in regular rhs operands.  For calls we
 700      have to ignore lhs, fndecl and static chain, otherwise only
 701      the lhs.  */
 702   for (i = (is_gimple_call (stmt) ? 2 : 0) + gimple_has_lhs (stmt);
 703        i < gimple_num_ops (stmt); ++i)
 704     {
 705       tree op = gimple_op (stmt, i);
 706       if (!op || TREE_CODE (op) == SSA_NAME)
 707         continue;
 708       if (is_gimple_min_invariant (op))
 709         has_constant_operand = true;
 710     }
 711
 712   if (has_constant_operand)
 713     all_undefined_operands = false;
 714
 715   if (has_undefined_operand
 716       && code == GIMPLE_CALL
 717       && gimple_call_internal_p (stmt))
 718     switch (gimple_call_internal_fn (stmt))
 719       {
 720         /* These 3 builtins use the first argument just as a magic
 721            way how to find out a decl uid.  */
 722       case IFN_GOMP_SIMD_LANE:
 723       case IFN_GOMP_SIMD_VF:
 724       case IFN_GOMP_SIMD_LAST_LANE:
 725         has_undefined_operand = false;
 726         break;
 727       default:
 728         break;
 729       }
 730
 731   /* If the operation combines operands like COMPLEX_EXPR make sure to
 732      not mark the result UNDEFINED if only one part of the result is
 733      undefined.  */
 734   if (has_undefined_operand && all_undefined_operands)
 735     return UNDEFINED;
 736   else if (code == GIMPLE_ASSIGN && has_undefined_operand)
 737     {
 738       switch (gimple_assign_rhs_code (stmt))
 739         {
 740         /* Unary operators are handled with all_undefined_operands.  */
 741         case PLUS_EXPR:
 742         case MINUS_EXPR:
 743         case POINTER_PLUS_EXPR:
 744           /* Not MIN_EXPR, MAX_EXPR.  One VARYING operand may be selected.
 745              Not bitwise operators, one VARYING operand may specify the
 746              result completely.  Not logical operators for the same reason.
 747              Not COMPLEX_EXPR as one VARYING operand makes the result partly
 748              not UNDEFINED.  Not *DIV_EXPR, comparisons and shifts because
 749              the undefined operand may be promoted.  */
 750           return UNDEFINED;
 751
 752         case ADDR_EXPR:
 753           /* If any part of an address is UNDEFINED, like the index
 754              of an ARRAY_EXPR, then treat the result as UNDEFINED.  */
 755           return UNDEFINED;
 756
 757         default:
 758           ;
 759         }
 760     }
 761   /* If there was an UNDEFINED operand but the result may be not UNDEFINED
 762      fall back to CONSTANT.  During iteration UNDEFINED may still drop
 763      to CONSTANT.  */
 764   if (has_undefined_operand)
 765     return CONSTANT;
 766
 767   /* We do not consider virtual operands here -- load from read-only
 768      memory may have only VARYING virtual operands, but still be
 769      constant.  Also we can combine the stmt with definitions from
 770      operands whose definitions are not simulated again.  */
 771   if (has_constant_operand
 772       || has_nsa_operand
 773       || gimple_references_memory_p (stmt))
 774     return CONSTANT;
 775
 776   return VARYING;
 777 }
 778
 779 /* Returns true if STMT cannot be constant.  */
 780
 781 static bool
 782 surely_varying_stmt_p (gimple *stmt)
 783 {
 784   /* If the statement has operands that we cannot handle, it cannot be
 785      constant.  */
 786   if (gimple_has_volatile_ops (stmt))
 787     return true;
 788
 789   /* If it is a call and does not return a value or is not a
 790      builtin and not an indirect call or a call to function with
 791      assume_aligned/alloc_align attribute, it is varying.  */
 792   if (is_gimple_call (stmt))
 793     {
 794       tree fndecl, fntype = gimple_call_fntype (stmt);
 795       if (!gimple_call_lhs (stmt)
 796           || ((fndecl = gimple_call_fndecl (stmt)) != NULL_TREE
 797               && !DECL_BUILT_IN (fndecl)
 798               && !lookup_attribute ("assume_aligned",
 799                                     TYPE_ATTRIBUTES (fntype))
 800               && !lookup_attribute ("alloc_align",
 801                                     TYPE_ATTRIBUTES (fntype))))
 802         return true;
 803     }
 804
 805   /* Any other store operation is not interesting.  */
 806   else if (gimple_vdef (stmt))
 807     return true;
 808
 809   /* Anything other than assignments and conditional jumps are not
 810      interesting for CCP.  */
 811   if (gimple_code (stmt) != GIMPLE_ASSIGN
 812       && gimple_code (stmt) != GIMPLE_COND
 813       && gimple_code (stmt) != GIMPLE_SWITCH
 814       && gimple_code (stmt) != GIMPLE_CALL)
 815     return true;
 816
 817   return false;
 818 }
 819
 820 /* Initialize local data structures for CCP.  */
 821
 822 static void
 823 ccp_initialize (void)
 824 {
 825   basic_block bb;
 826
 827   n_const_val = num_ssa_names;
 828   const_val = XCNEWVEC (ccp_prop_value_t, n_const_val);
 829
 830   /* Initialize simulation flags for PHI nodes and statements.  */
 831   FOR_EACH_BB_FN (bb, cfun)
 832     {
 833       gimple_stmt_iterator i;
 834
 835       for (i = gsi_start_bb (bb); !gsi_end_p (i); gsi_next (&i))
 836         {
 837           gimple *stmt = gsi_stmt (i);
 838           bool is_varying;
 839
 840           /* If the statement is a control insn, then we do not
 841              want to avoid simulating the statement once.  Failure
 842              to do so means that those edges will never get added.  */
 843           if (stmt_ends_bb_p (stmt))
 844             is_varying = false;
 845           else
 846             is_varying = surely_varying_stmt_p (stmt);
 847
 848           if (is_varying)
 849             {
 850               tree def;
 851               ssa_op_iter iter;
 852
 853               /* If the statement will not produce a constant, mark
 854                  all its outputs VARYING.  */
 855               FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
 856                 set_value_varying (def);
 857             }
 858           prop_set_simulate_again (stmt, !is_varying);
 859         }
 860     }
 861
 862   /* Now process PHI nodes.  We never clear the simulate_again flag on
 863      phi nodes, since we do not know which edges are executable yet,
 864      except for phi nodes for virtual operands when we do not do store ccp.  */
 865   FOR_EACH_BB_FN (bb, cfun)
 866     {
 867       gphi_iterator i;
 868
 869       for (i = gsi_start_phis (bb); !gsi_end_p (i); gsi_next (&i))
 870         {
 871           gphi *phi = i.phi ();
 872
 873           if (virtual_operand_p (gimple_phi_result (phi)))
 874             prop_set_simulate_again (phi, false);
 875           else
 876             prop_set_simulate_again (phi, true);
 877         }
 878     }
 879 }
 880
 881 /* Debug count support. Reset the values of ssa names
 882    VARYING when the total number ssa names analyzed is
 883    beyond the debug count specified.  */
 884
 885 static void
 886 do_dbg_cnt (void)
 887 {
 888   unsigned i;
 889   for (i = 0; i < num_ssa_names; i++)
 890     {
 891       if (!dbg_cnt (ccp))
 892         {
 893           const_val[i].lattice_val = VARYING;
 894           const_val[i].mask = -1;
 895           const_val[i].value = NULL_TREE;
 896         }
 897     }
 898 }
 899
 900
 901 /* Do final substitution of propagated values, cleanup the flowgraph and
 902    free allocated storage.  If NONZERO_P, record nonzero bits.
 903
 904    Return TRUE when something was optimized.  */
 905
 906 static bool
 907 ccp_finalize (bool nonzero_p)
 908 {
 909   bool something_changed;
 910   unsigned i;
 911   tree name;
 912
 913   do_dbg_cnt ();
 914
 915   /* Derive alignment and misalignment information from partially
 916      constant pointers in the lattice or nonzero bits from partially
 917      constant integers.  */
 918   FOR_EACH_SSA_NAME (i, name, cfun)
 919     {
 920       ccp_prop_value_t *val;
 921       unsigned int tem, align;
 922
 923       if (!POINTER_TYPE_P (TREE_TYPE (name))
 924           && (!INTEGRAL_TYPE_P (TREE_TYPE (name))
 925               /* Don't record nonzero bits before IPA to avoid
 926                  using too much memory.  */
 927               || !nonzero_p))
 928         continue;
 929
 930       val = get_value (name);
 931       if (val->lattice_val != CONSTANT
 932           || TREE_CODE (val->value) != INTEGER_CST
 933           || val->mask == 0)
 934         continue;
 935
 936       if (POINTER_TYPE_P (TREE_TYPE (name)))
 937         {
 938           /* Trailing mask bits specify the alignment, trailing value
 939              bits the misalignment.  */
 940           tem = val->mask.to_uhwi ();
 941           align = least_bit_hwi (tem);
 942           if (align > 1)
 943             set_ptr_info_alignment (get_ptr_info (name), align,
 944                                     (TREE_INT_CST_LOW (val->value)
 945                                      & (align - 1)));
 946         }
 947       else
 948         {
 949           unsigned int precision = TYPE_PRECISION (TREE_TYPE (val->value));
 950           wide_int nonzero_bits = wide_int::from (val->mask, precision,
 951                                                   UNSIGNED) | val->value;
 952           nonzero_bits &= get_nonzero_bits (name);
 953           set_nonzero_bits (name, nonzero_bits);
 954         }
 955     }
 956
 957   /* Perform substitutions based on the known constant values.  */
 958   something_changed = substitute_and_fold (get_constant_value, ccp_fold_stmt);
 959
 960   free (const_val);
 961   const_val = NULL;
 962   return something_changed;;
 963 }
 964
 965
 966 /* Compute the meet operator between *VAL1 and *VAL2.  Store the result
 967    in VAL1.
 968
 969                 any  M UNDEFINED   = any
 970                 any  M VARYING     = VARYING
 971                 Ci   M Cj          = Ci         if (i == j)
 972                 Ci   M Cj          = VARYING    if (i != j)
 973    */
 974
 975 static void
 976 ccp_lattice_meet (ccp_prop_value_t *val1, ccp_prop_value_t *val2)
 977 {
 978   if (val1->lattice_val == UNDEFINED
 979       /* For UNDEFINED M SSA we can't always SSA because its definition
 980          may not dominate the PHI node.  Doing optimistic copy propagation
 981          also causes a lot of gcc.dg/uninit-pred*.c FAILs.  */
 982       && (val2->lattice_val != CONSTANT
 983           || TREE_CODE (val2->value) != SSA_NAME))
 984     {
 985       /* UNDEFINED M any = any   */
 986       *val1 = *val2;
 987     }
 988   else if (val2->lattice_val == UNDEFINED
 989            /* See above.  */
 990            && (val1->lattice_val != CONSTANT
 991                || TREE_CODE (val1->value) != SSA_NAME))
 992     {
 993       /* any M UNDEFINED = any
 994          Nothing to do.  VAL1 already contains the value we want.  */
 995       ;
 996     }
 997   else if (val1->lattice_val == VARYING
 998            || val2->lattice_val == VARYING)
 999     {
1000       /* any M VARYING = VARYING.  */
1001       val1->lattice_val = VARYING;
1002       val1->mask = -1;
1003       val1->value = NULL_TREE;
1004     }
1005   else if (val1->lattice_val == CONSTANT
1006            && val2->lattice_val == CONSTANT
1007            && TREE_CODE (val1->value) == INTEGER_CST
1008            && TREE_CODE (val2->value) == INTEGER_CST)
1009     {
1010       /* Ci M Cj = Ci           if (i == j)
1011          Ci M Cj = VARYING      if (i != j)
1012
1013          For INTEGER_CSTs mask unequal bits.  If no equal bits remain,
1014          drop to varying.  */
1015       val1->mask = (val1->mask | val2->mask
1016                     | (wi::to_widest (val1->value)
1017                        ^ wi::to_widest (val2->value)));
1018       if (wi::sext (val1->mask, TYPE_PRECISION (TREE_TYPE (val1->value))) == -1)
1019         {
1020           val1->lattice_val = VARYING;
1021           val1->value = NULL_TREE;
1022         }
1023     }
1024   else if (val1->lattice_val == CONSTANT
1025            && val2->lattice_val == CONSTANT
1026            && operand_equal_p (val1->value, val2->value, 0))
1027     {
1028       /* Ci M Cj = Ci           if (i == j)
1029          Ci M Cj = VARYING      if (i != j)
1030
1031          VAL1 already contains the value we want for equivalent values.  */
1032     }
1033   else if (val1->lattice_val == CONSTANT
1034            && val2->lattice_val == CONSTANT
1035            && (TREE_CODE (val1->value) == ADDR_EXPR
1036                || TREE_CODE (val2->value) == ADDR_EXPR))
1037     {
1038       /* When not equal addresses are involved try meeting for
1039          alignment.  */
1040       ccp_prop_value_t tem = *val2;
1041       if (TREE_CODE (val1->value) == ADDR_EXPR)
1042         *val1 = get_value_for_expr (val1->value, true);
1043       if (TREE_CODE (val2->value) == ADDR_EXPR)
1044         tem = get_value_for_expr (val2->value, true);
1045       ccp_lattice_meet (val1, &tem);
1046     }
1047   else
1048     {
1049       /* Any other combination is VARYING.  */
1050       val1->lattice_val = VARYING;
1051       val1->mask = -1;
1052       val1->value = NULL_TREE;
1053     }
1054 }
1055
1056
1057 /* Loop through the PHI_NODE's parameters for BLOCK and compare their
1058    lattice values to determine PHI_NODE's lattice value.  The value of a
1059    PHI node is determined calling ccp_lattice_meet with all the arguments
1060    of the PHI node that are incoming via executable edges.  */
1061
1062 static enum ssa_prop_result
1063 ccp_visit_phi_node (gphi *phi)
1064 {
1065   unsigned i;
1066   ccp_prop_value_t new_val;
1067
1068   if (dump_file && (dump_flags & TDF_DETAILS))
1069     {
1070       fprintf (dump_file, "\nVisiting PHI node: ");
1071       print_gimple_stmt (dump_file, phi, 0, dump_flags);
1072     }
1073
1074   new_val.lattice_val = UNDEFINED;
1075   new_val.value = NULL_TREE;
1076   new_val.mask = 0;
1077
1078   bool first = true;
1079   bool non_exec_edge = false;
1080   for (i = 0; i < gimple_phi_num_args (phi); i++)
1081     {
1082       /* Compute the meet operator over all the PHI arguments flowing
1083          through executable edges.  */
1084       edge e = gimple_phi_arg_edge (phi, i);
1085
1086       if (dump_file && (dump_flags & TDF_DETAILS))
1087         {
1088           fprintf (dump_file,
1089               "\n    Argument #%d (%d -> %d %sexecutable)\n",
1090               i, e->src->index, e->dest->index,
1091               (e->flags & EDGE_EXECUTABLE) ? "" : "not ");
1092         }
1093
1094       /* If the incoming edge is executable, Compute the meet operator for
1095          the existing value of the PHI node and the current PHI argument.  */
1096       if (e->flags & EDGE_EXECUTABLE)
1097         {
1098           tree arg = gimple_phi_arg (phi, i)->def;
1099           ccp_prop_value_t arg_val = get_value_for_expr (arg, false);
1100
1101           if (first)
1102             {
1103               new_val = arg_val;
1104               first = false;
1105             }
1106           else
1107             ccp_lattice_meet (&new_val, &arg_val);
1108
1109           if (dump_file && (dump_flags & TDF_DETAILS))
1110             {
1111               fprintf (dump_file, "\t");
1112               print_generic_expr (dump_file, arg, dump_flags);
1113               dump_lattice_value (dump_file, "\tValue: ", arg_val);
1114               fprintf (dump_file, "\n");
1115             }
1116
1117           if (new_val.lattice_val == VARYING)
1118             break;
1119         }
1120       else
1121         non_exec_edge = true;
1122     }
1123
1124   /* In case there were non-executable edges and the value is a copy
1125      make sure its definition dominates the PHI node.  */
1126   if (non_exec_edge
1127       && new_val.lattice_val == CONSTANT
1128       && TREE_CODE (new_val.value) == SSA_NAME
1129       && ! SSA_NAME_IS_DEFAULT_DEF (new_val.value)
1130       && ! dominated_by_p (CDI_DOMINATORS, gimple_bb (phi),
1131                            gimple_bb (SSA_NAME_DEF_STMT (new_val.value))))
1132     {
1133       new_val.lattice_val = VARYING;
1134       new_val.value = NULL_TREE;
1135       new_val.mask = -1;
1136     }
1137
1138   if (dump_file && (dump_flags & TDF_DETAILS))
1139     {
1140       dump_lattice_value (dump_file, "\n    PHI node value: ", new_val);
1141       fprintf (dump_file, "\n\n");
1142     }
1143
1144   /* Make the transition to the new value.  */
1145   if (set_lattice_value (gimple_phi_result (phi), &new_val))
1146     {
1147       if (new_val.lattice_val == VARYING)
1148         return SSA_PROP_VARYING;
1149       else
1150         return SSA_PROP_INTERESTING;
1151     }
1152   else
1153     return SSA_PROP_NOT_INTERESTING;
1154 }
1155
1156 /* Return the constant value for OP or OP otherwise.  */
1157
1158 static tree
1159 valueize_op (tree op)
1160 {
1161   if (TREE_CODE (op) == SSA_NAME)
1162     {
1163       tree tem = get_constant_value (op);
1164       if (tem)
1165         return tem;
1166     }
1167   return op;
1168 }
1169
1170 /* Return the constant value for OP, but signal to not follow SSA
1171    edges if the definition may be simulated again.  */
1172
1173 static tree
1174 valueize_op_1 (tree op)
1175 {
1176   if (TREE_CODE (op) == SSA_NAME)
1177     {
1178       /* If the definition may be simulated again we cannot follow
1179          this SSA edge as the SSA propagator does not necessarily
1180          re-visit the use.  */
1181       gimple *def_stmt = SSA_NAME_DEF_STMT (op);
1182       if (!gimple_nop_p (def_stmt)
1183           && prop_simulate_again_p (def_stmt))
1184         return NULL_TREE;
1185       tree tem = get_constant_value (op);
1186       if (tem)
1187         return tem;
1188     }
1189   return op;
1190 }
1191
1192 /* CCP specific front-end to the non-destructive constant folding
1193    routines.
1194
1195    Attempt to simplify the RHS of STMT knowing that one or more
1196    operands are constants.
1197
1198    If simplification is possible, return the simplified RHS,
1199    otherwise return the original RHS or NULL_TREE.  */
1200
1201 static tree
1202 ccp_fold (gimple *stmt)
1203 {
1204   location_t loc = gimple_location (stmt);
1205   switch (gimple_code (stmt))
1206     {
1207     case GIMPLE_COND:
1208       {
1209         /* Handle comparison operators that can appear in GIMPLE form.  */
1210         tree op0 = valueize_op (gimple_cond_lhs (stmt));
1211         tree op1 = valueize_op (gimple_cond_rhs (stmt));
1212         enum tree_code code = gimple_cond_code (stmt);
1213         return fold_binary_loc (loc, code, boolean_type_node, op0, op1);
1214       }
1215
1216     case GIMPLE_SWITCH:
1217       {
1218         /* Return the constant switch index.  */
1219         return valueize_op (gimple_switch_index (as_a <gswitch *> (stmt)));
1220       }
1221
1222     case GIMPLE_ASSIGN:
1223     case GIMPLE_CALL:
1224       return gimple_fold_stmt_to_constant_1 (stmt,
1225                                              valueize_op, valueize_op_1);
1226
1227     default:
1228       gcc_unreachable ();
1229     }
1230 }
1231
1232 /* Apply the operation CODE in type TYPE to the value, mask pair
1233    RVAL and RMASK representing a value of type RTYPE and set
1234    the value, mask pair *VAL and *MASK to the result.  */
1235
1236 void
1237 bit_value_unop (enum tree_code code, signop type_sgn, int type_precision,
1238                 widest_int *val, widest_int *mask,
1239                 signop rtype_sgn, int rtype_precision,
1240                 const widest_int &rval, const widest_int &rmask)
1241 {
1242   switch (code)
1243     {
1244     case BIT_NOT_EXPR:
1245       *mask = rmask;
1246       *val = ~rval;
1247       break;
1248
1249     case NEGATE_EXPR:
1250       {
1251         widest_int temv, temm;
1252         /* Return ~rval + 1.  */
1253         bit_value_unop (BIT_NOT_EXPR, type_sgn, type_precision, &temv, &temm,
1254                         type_sgn, type_precision, rval, rmask);
1255         bit_value_binop (PLUS_EXPR, type_sgn, type_precision, val, mask,
1256                          type_sgn, type_precision, temv, temm,
1257                          type_sgn, type_precision, 1, 0);
1258         break;
1259       }
1260
1261     CASE_CONVERT:
1262       {
1263         /* First extend mask and value according to the original type.  */
1264         *mask = wi::ext (rmask, rtype_precision, rtype_sgn);
1265         *val = wi::ext (rval, rtype_precision, rtype_sgn);
1266
1267         /* Then extend mask and value according to the target type.  */
1268         *mask = wi::ext (*mask, type_precision, type_sgn);
1269         *val = wi::ext (*val, type_precision, type_sgn);
1270         break;
1271       }
1272
1273     default:
1274       *mask = -1;
1275       break;
1276     }
1277 }
1278
1279 /* Apply the operation CODE in type TYPE to the value, mask pairs
1280    R1VAL, R1MASK and R2VAL, R2MASK representing a values of type R1TYPE
1281    and R2TYPE and set the value, mask pair *VAL and *MASK to the result.  */
1282
1283 void
1284 bit_value_binop (enum tree_code code, signop sgn, int width,
1285                  widest_int *val, widest_int *mask,
1286                  signop r1type_sgn, int r1type_precision,
1287                  const widest_int &r1val, const widest_int &r1mask,
1288                  signop r2type_sgn, int r2type_precision,
1289                  const widest_int &r2val, const widest_int &r2mask)
1290 {
1291   bool swap_p = false;
1292
1293   /* Assume we'll get a constant result.  Use an initial non varying
1294      value, we fall back to varying in the end if necessary.  */
1295   *mask = -1;
1296
1297   switch (code)
1298     {
1299     case BIT_AND_EXPR:
1300       /* The mask is constant where there is a known not
1301          set bit, (m1 | m2) & ((v1 | m1) & (v2 | m2)) */
1302       *mask = (r1mask | r2mask) & (r1val | r1mask) & (r2val | r2mask);
1303       *val = r1val & r2val;
1304       break;
1305
1306     case BIT_IOR_EXPR:
1307       /* The mask is constant where there is a known
1308          set bit, (m1 | m2) & ~((v1 & ~m1) | (v2 & ~m2)).  */
1309       *mask = (r1mask | r2mask)
1310               .and_not (r1val.and_not (r1mask) | r2val.and_not (r2mask));
1311       *val = r1val | r2val;
1312       break;
1313
1314     case BIT_XOR_EXPR:
1315       /* m1 | m2  */
1316       *mask = r1mask | r2mask;
1317       *val = r1val ^ r2val;
1318       break;
1319
1320     case LROTATE_EXPR:
1321     case RROTATE_EXPR:
1322       if (r2mask == 0)
1323         {
1324           widest_int shift = r2val;
1325           if (shift == 0)
1326             {
1327               *mask = r1mask;
1328               *val = r1val;
1329             }
1330           else
1331             {
1332               if (wi::neg_p (shift))
1333                 {
1334                   shift = -shift;
1335                   if (code == RROTATE_EXPR)
1336                     code = LROTATE_EXPR;
1337                   else
1338                     code = RROTATE_EXPR;
1339                 }
1340               if (code == RROTATE_EXPR)
1341                 {
1342                   *mask = wi::rrotate (r1mask, shift, width);
1343                   *val = wi::rrotate (r1val, shift, width);
1344                 }
1345               else
1346                 {
1347                   *mask = wi::lrotate (r1mask, shift, width);
1348                   *val = wi::lrotate (r1val, shift, width);
1349                 }
1350             }
1351         }
1352       break;
1353
1354     case LSHIFT_EXPR:
1355     case RSHIFT_EXPR:
1356       /* ???  We can handle partially known shift counts if we know
1357          its sign.  That way we can tell that (x << (y | 8)) & 255
1358          is zero.  */
1359       if (r2mask == 0)
1360         {
1361           widest_int shift = r2val;
1362           if (shift == 0)
1363             {
1364               *mask = r1mask;
1365               *val = r1val;
1366             }
1367           else
1368             {
1369               if (wi::neg_p (shift))
1370                 {
1371                   shift = -shift;
1372                   if (code == RSHIFT_EXPR)
1373                     code = LSHIFT_EXPR;
1374                   else
1375                     code = RSHIFT_EXPR;
1376                 }
1377               if (code == RSHIFT_EXPR)
1378                 {
1379                   *mask = wi::rshift (wi::ext (r1mask, width, sgn), shift, sgn);
1380                   *val = wi::rshift (wi::ext (r1val, width, sgn), shift, sgn);
1381                 }
1382               else
1383                 {
1384                   *mask = wi::ext (r1mask << shift, width, sgn);
1385                   *val = wi::ext (r1val << shift, width, sgn);
1386                 }
1387             }
1388         }
1389       break;
1390
1391     case PLUS_EXPR:
1392     case POINTER_PLUS_EXPR:
1393       {
1394         /* Do the addition with unknown bits set to zero, to give carry-ins of
1395            zero wherever possible.  */
1396         widest_int lo = r1val.and_not (r1mask) + r2val.and_not (r2mask);
1397         lo = wi::ext (lo, width, sgn);
1398         /* Do the addition with unknown bits set to one, to give carry-ins of
1399            one wherever possible.  */
1400         widest_int hi = (r1val | r1mask) + (r2val | r2mask);
1401         hi = wi::ext (hi, width, sgn);
1402         /* Each bit in the result is known if (a) the corresponding bits in
1403            both inputs are known, and (b) the carry-in to that bit position
1404            is known.  We can check condition (b) by seeing if we got the same
1405            result with minimised carries as with maximised carries.  */
1406         *mask = r1mask | r2mask | (lo ^ hi);
1407         *mask = wi::ext (*mask, width, sgn);
1408         /* It shouldn't matter whether we choose lo or hi here.  */
1409         *val = lo;
1410         break;
1411       }
1412
1413     case MINUS_EXPR:
1414       {
1415         widest_int temv, temm;
1416         bit_value_unop (NEGATE_EXPR, r2type_sgn, r2type_precision, &temv, &temm,
1417                           r2type_sgn, r2type_precision, r2val, r2mask);
1418         bit_value_binop (PLUS_EXPR, sgn, width, val, mask,
1419                          r1type_sgn, r1type_precision, r1val, r1mask,
1420                          r2type_sgn, r2type_precision, temv, temm);
1421         break;
1422       }
1423
1424     case MULT_EXPR:
1425       {
1426         /* Just track trailing zeros in both operands and transfer
1427            them to the other.  */
1428         int r1tz = wi::ctz (r1val | r1mask);
1429         int r2tz = wi::ctz (r2val | r2mask);
1430         if (r1tz + r2tz >= width)
1431           {
1432             *mask = 0;
1433             *val = 0;
1434           }
1435         else if (r1tz + r2tz > 0)
1436           {
1437             *mask = wi::ext (wi::mask <widest_int> (r1tz + r2tz, true),
1438                              width, sgn);
1439             *val = 0;
1440           }
1441         break;
1442       }
1443
1444     case EQ_EXPR:
1445     case NE_EXPR:
1446       {
1447         widest_int m = r1mask | r2mask;
1448         if (r1val.and_not (m) != r2val.and_not (m))
1449           {
1450             *mask = 0;
1451             *val = ((code == EQ_EXPR) ? 0 : 1);
1452           }
1453         else
1454           {
1455             /* We know the result of a comparison is always one or zero.  */
1456             *mask = 1;
1457             *val = 0;
1458           }
1459         break;
1460       }
1461
1462     case GE_EXPR:
1463     case GT_EXPR:
1464       swap_p = true;
1465       code = swap_tree_comparison (code);
1466       /* Fall through.  */
1467     case LT_EXPR:
1468     case LE_EXPR:
1469       {
1470         int minmax, maxmin;
1471
1472         const widest_int &o1val = swap_p ? r2val : r1val;
1473         const widest_int &o1mask = swap_p ? r2mask : r1mask;
1474         const widest_int &o2val = swap_p ? r1val : r2val;
1475         const widest_int &o2mask = swap_p ? r1mask : r2mask;
1476
1477         /* If the most significant bits are not known we know nothing.  */
1478         if (wi::neg_p (o1mask) || wi::neg_p (o2mask))
1479           break;
1480
1481         /* For comparisons the signedness is in the comparison operands.  */
1482         sgn = r1type_sgn;
1483
1484         /* If we know the most significant bits we know the values
1485            value ranges by means of treating varying bits as zero
1486            or one.  Do a cross comparison of the max/min pairs.  */
1487         maxmin = wi::cmp (o1val | o1mask, o2val.and_not (o2mask), sgn);
1488         minmax = wi::cmp (o1val.and_not (o1mask), o2val | o2mask, sgn);
1489         if (maxmin < 0)  /* o1 is less than o2.  */
1490           {
1491             *mask = 0;
1492             *val = 1;
1493           }
1494         else if (minmax > 0)  /* o1 is not less or equal to o2.  */
1495           {
1496             *mask = 0;
1497             *val = 0;
1498           }
1499         else if (maxmin == minmax)  /* o1 and o2 are equal.  */
1500           {
1501             /* This probably should never happen as we'd have
1502                folded the thing during fully constant value folding.  */
1503             *mask = 0;
1504             *val = (code == LE_EXPR ? 1 : 0);
1505           }
1506         else
1507           {
1508             /* We know the result of a comparison is always one or zero.  */
1509             *mask = 1;
1510             *val = 0;
1511           }
1512         break;
1513       }
1514
1515     default:;
1516     }
1517 }
1518
1519 /* Return the propagation value when applying the operation CODE to
1520    the value RHS yielding type TYPE.  */
1521
1522 static ccp_prop_value_t
1523 bit_value_unop (enum tree_code code, tree type, tree rhs)
1524 {
1525   ccp_prop_value_t rval = get_value_for_expr (rhs, true);
1526   widest_int value, mask;
1527   ccp_prop_value_t val;
1528
1529   if (rval.lattice_val == UNDEFINED)
1530     return rval;
1531
1532   gcc_assert ((rval.lattice_val == CONSTANT
1533                && TREE_CODE (rval.value) == INTEGER_CST)
1534               || wi::sext (rval.mask, TYPE_PRECISION (TREE_TYPE (rhs))) == -1);
1535   bit_value_unop (code, TYPE_SIGN (type), TYPE_PRECISION (type), &value, &mask,
1536                   TYPE_SIGN (TREE_TYPE (rhs)), TYPE_PRECISION (TREE_TYPE (rhs)),
1537                   value_to_wide_int (rval), rval.mask);
1538   if (wi::sext (mask, TYPE_PRECISION (type)) != -1)
1539     {
1540       val.lattice_val = CONSTANT;
1541       val.mask = mask;
1542       /* ???  Delay building trees here.  */
1543       val.value = wide_int_to_tree (type, value);
1544     }
1545   else
1546     {
1547       val.lattice_val = VARYING;
1548       val.value = NULL_TREE;
1549       val.mask = -1;
1550     }
1551   return val;
1552 }
1553
1554 /* Return the propagation value when applying the operation CODE to
1555    the values RHS1 and RHS2 yielding type TYPE.  */
1556
1557 static ccp_prop_value_t
1558 bit_value_binop (enum tree_code code, tree type, tree rhs1, tree rhs2)
1559 {
1560   ccp_prop_value_t r1val = get_value_for_expr (rhs1, true);
1561   ccp_prop_value_t r2val = get_value_for_expr (rhs2, true);
1562   widest_int value, mask;
1563   ccp_prop_value_t val;
1564
1565   if (r1val.lattice_val == UNDEFINED
1566       || r2val.lattice_val == UNDEFINED)
1567     {
1568       val.lattice_val = VARYING;
1569       val.value = NULL_TREE;
1570       val.mask = -1;
1571       return val;
1572     }
1573
1574   gcc_assert ((r1val.lattice_val == CONSTANT
1575                && TREE_CODE (r1val.value) == INTEGER_CST)
1576               || wi::sext (r1val.mask,
1577                            TYPE_PRECISION (TREE_TYPE (rhs1))) == -1);
1578   gcc_assert ((r2val.lattice_val == CONSTANT
1579                && TREE_CODE (r2val.value) == INTEGER_CST)
1580               || wi::sext (r2val.mask,
1581                            TYPE_PRECISION (TREE_TYPE (rhs2))) == -1);
1582   bit_value_binop (code, TYPE_SIGN (type), TYPE_PRECISION (type), &value, &mask,
1583                    TYPE_SIGN (TREE_TYPE (rhs1)), TYPE_PRECISION (TREE_TYPE (rhs1)),
1584                    value_to_wide_int (r1val), r1val.mask,
1585                    TYPE_SIGN (TREE_TYPE (rhs2)), TYPE_PRECISION (TREE_TYPE (rhs2)),
1586                    value_to_wide_int (r2val), r2val.mask);
1587
1588   if (wi::sext (mask, TYPE_PRECISION (type)) != -1)
1589     {
1590       val.lattice_val = CONSTANT;
1591       val.mask = mask;
1592       /* ???  Delay building trees here.  */
1593       val.value = wide_int_to_tree (type, value);
1594     }
1595   else
1596     {
1597       val.lattice_val = VARYING;
1598       val.value = NULL_TREE;
1599       val.mask = -1;
1600     }
1601   return val;
1602 }
1603
1604 /* Return the propagation value for __builtin_assume_aligned
1605    and functions with assume_aligned or alloc_aligned attribute.
1606    For __builtin_assume_aligned, ATTR is NULL_TREE,
1607    for assume_aligned attribute ATTR is non-NULL and ALLOC_ALIGNED
1608    is false, for alloc_aligned attribute ATTR is non-NULL and
1609    ALLOC_ALIGNED is true.  */
1610
1611 static ccp_prop_value_t
1612 bit_value_assume_aligned (gimple *stmt, tree attr, ccp_prop_value_t ptrval,
1613                           bool alloc_aligned)
1614 {
1615   tree align, misalign = NULL_TREE, type;
1616   unsigned HOST_WIDE_INT aligni, misaligni = 0;
1617   ccp_prop_value_t alignval;
1618   widest_int value, mask;
1619   ccp_prop_value_t val;
1620
1621   if (attr == NULL_TREE)
1622     {
1623       tree ptr = gimple_call_arg (stmt, 0);
1624       type = TREE_TYPE (ptr);
1625       ptrval = get_value_for_expr (ptr, true);
1626     }
1627   else
1628     {
1629       tree lhs = gimple_call_lhs (stmt);
1630       type = TREE_TYPE (lhs);
1631     }
1632
1633   if (ptrval.lattice_val == UNDEFINED)
1634     return ptrval;
1635   gcc_assert ((ptrval.lattice_val == CONSTANT
1636                && TREE_CODE (ptrval.value) == INTEGER_CST)
1637               || wi::sext (ptrval.mask, TYPE_PRECISION (type)) == -1);
1638   if (attr == NULL_TREE)
1639     {
1640       /* Get aligni and misaligni from __builtin_assume_aligned.  */
1641       align = gimple_call_arg (stmt, 1);
1642       if (!tree_fits_uhwi_p (align))
1643         return ptrval;
1644       aligni = tree_to_uhwi (align);
1645       if (gimple_call_num_args (stmt) > 2)
1646         {
1647           misalign = gimple_call_arg (stmt, 2);
1648           if (!tree_fits_uhwi_p (misalign))
1649             return ptrval;
1650           misaligni = tree_to_uhwi (misalign);
1651         }
1652     }
1653   else
1654     {
1655       /* Get aligni and misaligni from assume_aligned or
1656          alloc_align attributes.  */
1657       if (TREE_VALUE (attr) == NULL_TREE)
1658         return ptrval;
1659       attr = TREE_VALUE (attr);
1660       align = TREE_VALUE (attr);
1661       if (!tree_fits_uhwi_p (align))
1662         return ptrval;
1663       aligni = tree_to_uhwi (align);
1664       if (alloc_aligned)
1665         {
1666           if (aligni == 0 || aligni > gimple_call_num_args (stmt))
1667             return ptrval;
1668           align = gimple_call_arg (stmt, aligni - 1);
1669           if (!tree_fits_uhwi_p (align))
1670             return ptrval;
1671           aligni = tree_to_uhwi (align);
1672         }
1673       else if (TREE_CHAIN (attr) && TREE_VALUE (TREE_CHAIN (attr)))
1674         {
1675           misalign = TREE_VALUE (TREE_CHAIN (attr));
1676           if (!tree_fits_uhwi_p (misalign))
1677             return ptrval;
1678           misaligni = tree_to_uhwi (misalign);
1679         }
1680     }
1681   if (aligni <= 1 || (aligni & (aligni - 1)) != 0 || misaligni >= aligni)
1682     return ptrval;
1683
1684   align = build_int_cst_type (type, -aligni);
1685   alignval = get_value_for_expr (align, true);
1686   bit_value_binop (BIT_AND_EXPR, TYPE_SIGN (type), TYPE_PRECISION (type), &value, &mask,
1687                    TYPE_SIGN (type), TYPE_PRECISION (type), value_to_wide_int (ptrval), ptrval.mask,
1688                    TYPE_SIGN (type), TYPE_PRECISION (type), value_to_wide_int (alignval), alignval.mask);
1689
1690   if (wi::sext (mask, TYPE_PRECISION (type)) != -1)
1691     {
1692       val.lattice_val = CONSTANT;
1693       val.mask = mask;
1694       gcc_assert ((mask.to_uhwi () & (aligni - 1)) == 0);
1695       gcc_assert ((value.to_uhwi () & (aligni - 1)) == 0);
1696       value |= misaligni;
1697       /* ???  Delay building trees here.  */
1698       val.value = wide_int_to_tree (type, value);
1699     }
1700   else
1701     {
1702       val.lattice_val = VARYING;
1703       val.value = NULL_TREE;
1704       val.mask = -1;
1705     }
1706   return val;
1707 }
1708
1709 /* Evaluate statement STMT.
1710    Valid only for assignments, calls, conditionals, and switches. */
1711
1712 static ccp_prop_value_t
1713 evaluate_stmt (gimple *stmt)
1714 {
1715   ccp_prop_value_t val;
1716   tree simplified = NULL_TREE;
1717   ccp_lattice_t likelyvalue = likely_value (stmt);
1718   bool is_constant = false;
1719   unsigned int align;
1720
1721   if (dump_file && (dump_flags & TDF_DETAILS))
1722     {
1723       fprintf (dump_file, "which is likely ");
1724       switch (likelyvalue)
1725         {
1726         case CONSTANT:
1727           fprintf (dump_file, "CONSTANT");
1728           break;
1729         case UNDEFINED:
1730           fprintf (dump_file, "UNDEFINED");
1731           break;
1732         case VARYING:
1733           fprintf (dump_file, "VARYING");
1734           break;
1735         default:;
1736         }
1737       fprintf (dump_file, "\n");
1738     }
1739
1740   /* If the statement is likely to have a CONSTANT result, then try
1741      to fold the statement to determine the constant value.  */
1742   /* FIXME.  This is the only place that we call ccp_fold.
1743      Since likely_value never returns CONSTANT for calls, we will
1744      not attempt to fold them, including builtins that may profit.  */
1745   if (likelyvalue == CONSTANT)
1746     {
1747       fold_defer_overflow_warnings ();
1748       simplified = ccp_fold (stmt);
1749       if (simplified
1750           && TREE_CODE (simplified) == SSA_NAME
1751           /* We may not use values of something that may be simulated again,
1752              see valueize_op_1.  */
1753           && (SSA_NAME_IS_DEFAULT_DEF (simplified)
1754               || ! prop_simulate_again_p (SSA_NAME_DEF_STMT (simplified))))
1755         {
1756           ccp_prop_value_t *val = get_value (simplified);
1757           if (val && val->lattice_val != VARYING)
1758             {
1759               fold_undefer_overflow_warnings (true, stmt, 0);
1760               return *val;
1761             }
1762         }
1763       is_constant = simplified && is_gimple_min_invariant (simplified);
1764       fold_undefer_overflow_warnings (is_constant, stmt, 0);
1765       if (is_constant)
1766         {
1767           /* The statement produced a constant value.  */
1768           val.lattice_val = CONSTANT;
1769           val.value = simplified;
1770           val.mask = 0;
1771           return val;
1772         }
1773     }
1774   /* If the statement is likely to have a VARYING result, then do not
1775      bother folding the statement.  */
1776   else if (likelyvalue == VARYING)
1777     {
1778       enum gimple_code code = gimple_code (stmt);
1779       if (code == GIMPLE_ASSIGN)
1780         {
1781           enum tree_code subcode = gimple_assign_rhs_code (stmt);
1782
1783           /* Other cases cannot satisfy is_gimple_min_invariant
1784              without folding.  */
1785           if (get_gimple_rhs_class (subcode) == GIMPLE_SINGLE_RHS)
1786             simplified = gimple_assign_rhs1 (stmt);
1787         }
1788       else if (code == GIMPLE_SWITCH)
1789         simplified = gimple_switch_index (as_a <gswitch *> (stmt));
1790       else
1791         /* These cannot satisfy is_gimple_min_invariant without folding.  */
1792         gcc_assert (code == GIMPLE_CALL || code == GIMPLE_COND);
1793       is_constant = simplified && is_gimple_min_invariant (simplified);
1794       if (is_constant)
1795         {
1796           /* The statement produced a constant value.  */
1797           val.lattice_val = CONSTANT;
1798           val.value = simplified;
1799           val.mask = 0;
1800         }
1801     }
1802   /* If the statement result is likely UNDEFINED, make it so.  */
1803   else if (likelyvalue == UNDEFINED)
1804     {
1805       val.lattice_val = UNDEFINED;
1806       val.value = NULL_TREE;
1807       val.mask = 0;
1808       return val;
1809     }
1810
1811   /* Resort to simplification for bitwise tracking.  */
1812   if (flag_tree_bit_ccp
1813       && (likelyvalue == CONSTANT || is_gimple_call (stmt)
1814           || (gimple_assign_single_p (stmt)
1815               && gimple_assign_rhs_code (stmt) == ADDR_EXPR))
1816       && !is_constant)
1817     {
1818       enum gimple_code code = gimple_code (stmt);
1819       val.lattice_val = VARYING;
1820       val.value = NULL_TREE;
1821       val.mask = -1;
1822       if (code == GIMPLE_ASSIGN)
1823         {
1824           enum tree_code subcode = gimple_assign_rhs_code (stmt);
1825           tree rhs1 = gimple_assign_rhs1 (stmt);
1826           tree lhs = gimple_assign_lhs (stmt);
1827           if ((INTEGRAL_TYPE_P (TREE_TYPE (lhs))
1828                || POINTER_TYPE_P (TREE_TYPE (lhs)))
1829               && (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
1830                   || POINTER_TYPE_P (TREE_TYPE (rhs1))))
1831             switch (get_gimple_rhs_class (subcode))
1832               {
1833               case GIMPLE_SINGLE_RHS:
1834                 val = get_value_for_expr (rhs1, true);
1835                 break;
1836
1837               case GIMPLE_UNARY_RHS:
1838                 val = bit_value_unop (subcode, TREE_TYPE (lhs), rhs1);
1839                 break;
1840
1841               case GIMPLE_BINARY_RHS:
1842                 val = bit_value_binop (subcode, TREE_TYPE (lhs), rhs1,
1843                                        gimple_assign_rhs2 (stmt));
1844                 break;
1845
1846               default:;
1847               }
1848         }
1849       else if (code == GIMPLE_COND)
1850         {
1851           enum tree_code code = gimple_cond_code (stmt);
1852           tree rhs1 = gimple_cond_lhs (stmt);
1853           tree rhs2 = gimple_cond_rhs (stmt);
1854           if (INTEGRAL_TYPE_P (TREE_TYPE (rhs1))
1855               || POINTER_TYPE_P (TREE_TYPE (rhs1)))
1856             val = bit_value_binop (code, TREE_TYPE (rhs1), rhs1, rhs2);
1857         }
1858       else if (gimple_call_builtin_p (stmt, BUILT_IN_NORMAL))
1859         {
1860           tree fndecl = gimple_call_fndecl (stmt);
1861           switch (DECL_FUNCTION_CODE (fndecl))
1862             {
1863             case BUILT_IN_MALLOC:
1864             case BUILT_IN_REALLOC:
1865             case BUILT_IN_CALLOC:
1866             case BUILT_IN_STRDUP:
1867             case BUILT_IN_STRNDUP:
1868               val.lattice_val = CONSTANT;
1869               val.value = build_int_cst (TREE_TYPE (gimple_get_lhs (stmt)), 0);
1870               val.mask = ~((HOST_WIDE_INT) MALLOC_ABI_ALIGNMENT
1871                            / BITS_PER_UNIT - 1);
1872               break;
1873
1874             case BUILT_IN_ALLOCA:
1875             case BUILT_IN_ALLOCA_WITH_ALIGN:
1876               align = (DECL_FUNCTION_CODE (fndecl) == BUILT_IN_ALLOCA_WITH_ALIGN
1877                        ? TREE_INT_CST_LOW (gimple_call_arg (stmt, 1))
1878                        : BIGGEST_ALIGNMENT);
1879               val.lattice_val = CONSTANT;
1880               val.value = build_int_cst (TREE_TYPE (gimple_get_lhs (stmt)), 0);
1881               val.mask = ~((HOST_WIDE_INT) align / BITS_PER_UNIT - 1);
1882               break;
1883
1884             /* These builtins return their first argument, unmodified.  */
1885             case BUILT_IN_MEMCPY:
1886             case BUILT_IN_MEMMOVE:
1887             case BUILT_IN_MEMSET:
1888             case BUILT_IN_STRCPY:
1889             case BUILT_IN_STRNCPY:
1890             case BUILT_IN_MEMCPY_CHK:
1891             case BUILT_IN_MEMMOVE_CHK:
1892             case BUILT_IN_MEMSET_CHK:
1893             case BUILT_IN_STRCPY_CHK:
1894             case BUILT_IN_STRNCPY_CHK:
1895               val = get_value_for_expr (gimple_call_arg (stmt, 0), true);
1896               break;
1897
1898             case BUILT_IN_ASSUME_ALIGNED:
1899               val = bit_value_assume_aligned (stmt, NULL_TREE, val, false);
1900               break;
1901
1902             case BUILT_IN_ALIGNED_ALLOC:
1903               {
1904                 tree align = get_constant_value (gimple_call_arg (stmt, 0));
1905                 if (align
1906                     && tree_fits_uhwi_p (align))
1907                   {
1908                     unsigned HOST_WIDE_INT aligni = tree_to_uhwi (align);
1909                     if (aligni > 1
1910                         /* align must be power-of-two */
1911                         && (aligni & (aligni - 1)) == 0)
1912                       {
1913                         val.lattice_val = CONSTANT;
1914                         val.value = build_int_cst (ptr_type_node, 0);
1915                         val.mask = -aligni;
1916                       }
1917                   }
1918                 break;
1919               }
1920
1921             default:;
1922             }
1923         }
1924       if (is_gimple_call (stmt) && gimple_call_lhs (stmt))
1925         {
1926           tree fntype = gimple_call_fntype (stmt);
1927           if (fntype)
1928             {
1929               tree attrs = lookup_attribute ("assume_aligned",
1930                                              TYPE_ATTRIBUTES (fntype));
1931               if (attrs)
1932                 val = bit_value_assume_aligned (stmt, attrs, val, false);
1933               attrs = lookup_attribute ("alloc_align",
1934                                         TYPE_ATTRIBUTES (fntype));
1935               if (attrs)
1936                 val = bit_value_assume_aligned (stmt, attrs, val, true);
1937             }
1938         }
1939       is_constant = (val.lattice_val == CONSTANT);
1940     }
1941
1942   if (flag_tree_bit_ccp
1943       && ((is_constant && TREE_CODE (val.value) == INTEGER_CST)
1944           || !is_constant)
1945       && gimple_get_lhs (stmt)
1946       && TREE_CODE (gimple_get_lhs (stmt)) == SSA_NAME)
1947     {
1948       tree lhs = gimple_get_lhs (stmt);
1949       wide_int nonzero_bits = get_nonzero_bits (lhs);
1950       if (nonzero_bits != -1)
1951         {
1952           if (!is_constant)
1953             {
1954               val.lattice_val = CONSTANT;
1955               val.value = build_zero_cst (TREE_TYPE (lhs));
1956               val.mask = extend_mask (nonzero_bits, TYPE_SIGN (TREE_TYPE (lhs)));
1957               is_constant = true;
1958             }
1959           else
1960             {
1961               if (wi::bit_and_not (val.value, nonzero_bits) != 0)
1962                 val.value = wide_int_to_tree (TREE_TYPE (lhs),
1963                                               nonzero_bits & val.value);
1964               if (nonzero_bits == 0)
1965                 val.mask = 0;
1966               else
1967                 val.mask = val.mask & extend_mask (nonzero_bits,
1968                                                    TYPE_SIGN (TREE_TYPE (lhs)));
1969             }
1970         }
1971     }
1972
1973   /* The statement produced a nonconstant value.  */
1974   if (!is_constant)
1975     {
1976       /* The statement produced a copy.  */
1977       if (simplified && TREE_CODE (simplified) == SSA_NAME
1978           && !SSA_NAME_OCCURS_IN_ABNORMAL_PHI (simplified))
1979         {
1980           val.lattice_val = CONSTANT;
1981           val.value = simplified;
1982           val.mask = -1;
1983         }
1984       /* The statement is VARYING.  */
1985       else
1986         {
1987           val.lattice_val = VARYING;
1988           val.value = NULL_TREE;
1989           val.mask = -1;
1990         }
1991     }
1992
1993   return val;
1994 }
1995
1996 typedef hash_table<nofree_ptr_hash<gimple> > gimple_htab;
1997
1998 /* Given a BUILT_IN_STACK_SAVE value SAVED_VAL, insert a clobber of VAR before
1999    each matching BUILT_IN_STACK_RESTORE.  Mark visited phis in VISITED.  */
2000
2001 static void
2002 insert_clobber_before_stack_restore (tree saved_val, tree var,
2003                                      gimple_htab **visited)
2004 {
2005   gimple *stmt;
2006   gassign *clobber_stmt;
2007   tree clobber;
2008   imm_use_iterator iter;
2009   gimple_stmt_iterator i;
2010   gimple **slot;
2011
2012   FOR_EACH_IMM_USE_STMT (stmt, iter, saved_val)
2013     if (gimple_call_builtin_p (stmt, BUILT_IN_STACK_RESTORE))
2014       {
2015         clobber = build_constructor (TREE_TYPE (var),
2016                                      NULL);
2017         TREE_THIS_VOLATILE (clobber) = 1;
2018         clobber_stmt = gimple_build_assign (var, clobber);
2019
2020         i = gsi_for_stmt (stmt);
2021         gsi_insert_before (&i, clobber_stmt, GSI_SAME_STMT);
2022       }
2023     else if (gimple_code (stmt) == GIMPLE_PHI)
2024       {
2025         if (!*visited)
2026           *visited = new gimple_htab (10);
2027
2028         slot = (*visited)->find_slot (stmt, INSERT);
2029         if (*slot != NULL)
2030           continue;
2031
2032         *slot = stmt;
2033         insert_clobber_before_stack_restore (gimple_phi_result (stmt), var,
2034                                              visited);
2035       }
2036     else if (gimple_assign_ssa_name_copy_p (stmt))
2037       insert_clobber_before_stack_restore (gimple_assign_lhs (stmt), var,
2038                                            visited);
2039     else if (chkp_gimple_call_builtin_p (stmt, BUILT_IN_CHKP_BNDRET))
2040       continue;
2041     else
2042       gcc_assert (is_gimple_debug (stmt));
2043 }
2044
2045 /* Advance the iterator to the previous non-debug gimple statement in the same
2046    or dominating basic block.  */
2047
2048 static inline void
2049 gsi_prev_dom_bb_nondebug (gimple_stmt_iterator *i)
2050 {
2051   basic_block dom;
2052
2053   gsi_prev_nondebug (i);
2054   while (gsi_end_p (*i))
2055     {
2056       dom = get_immediate_dominator (CDI_DOMINATORS, i->bb);
2057       if (dom == NULL || dom == ENTRY_BLOCK_PTR_FOR_FN (cfun))
2058         return;
2059
2060       *i = gsi_last_bb (dom);
2061     }
2062 }
2063
2064 /* Find a BUILT_IN_STACK_SAVE dominating gsi_stmt (I), and insert
2065    a clobber of VAR before each matching BUILT_IN_STACK_RESTORE.
2066
2067    It is possible that BUILT_IN_STACK_SAVE cannot be find in a dominator when a
2068    previous pass (such as DOM) duplicated it along multiple paths to a BB.  In
2069    that case the function gives up without inserting the clobbers.  */
2070
2071 static void
2072 insert_clobbers_for_var (gimple_stmt_iterator i, tree var)
2073 {
2074   gimple *stmt;
2075   tree saved_val;
2076   gimple_htab *visited = NULL;
2077
2078   for (; !gsi_end_p (i); gsi_prev_dom_bb_nondebug (&i))
2079     {
2080       stmt = gsi_stmt (i);
2081
2082       if (!gimple_call_builtin_p (stmt, BUILT_IN_STACK_SAVE))
2083         continue;
2084
2085       saved_val = gimple_call_lhs (stmt);
2086       if (saved_val == NULL_TREE)
2087         continue;
2088
2089       insert_clobber_before_stack_restore (saved_val, var, &visited);
2090       break;
2091     }
2092
2093   delete visited;
2094 }
2095
2096 /* Detects a __builtin_alloca_with_align with constant size argument.  Declares
2097    fixed-size array and returns the address, if found, otherwise returns
2098    NULL_TREE.  */
2099
2100 static tree
2101 fold_builtin_alloca_with_align (gimple *stmt)
2102 {
2103   unsigned HOST_WIDE_INT size, threshold, n_elem;
2104   tree lhs, arg, block, var, elem_type, array_type;
2105
2106   /* Get lhs.  */
2107   lhs = gimple_call_lhs (stmt);
2108   if (lhs == NULL_TREE)
2109     return NULL_TREE;
2110
2111   /* Detect constant argument.  */
2112   arg = get_constant_value (gimple_call_arg (stmt, 0));
2113   if (arg == NULL_TREE
2114       || TREE_CODE (arg) != INTEGER_CST
2115       || !tree_fits_uhwi_p (arg))
2116     return NULL_TREE;
2117
2118   size = tree_to_uhwi (arg);
2119
2120   /* Heuristic: don't fold large allocas.  */
2121   threshold = (unsigned HOST_WIDE_INT)PARAM_VALUE (PARAM_LARGE_STACK_FRAME);
2122   /* In case the alloca is located at function entry, it has the same lifetime
2123      as a declared array, so we allow a larger size.  */
2124   block = gimple_block (stmt);
2125   if (!(cfun->after_inlining
2126         && block
2127         && TREE_CODE (BLOCK_SUPERCONTEXT (block)) == FUNCTION_DECL))
2128     threshold /= 10;
2129   if (size > threshold)
2130     return NULL_TREE;
2131
2132   /* Declare array.  */
2133   elem_type = build_nonstandard_integer_type (BITS_PER_UNIT, 1);
2134   n_elem = size * 8 / BITS_PER_UNIT;
2135   array_type = build_array_type_nelts (elem_type, n_elem);
2136   var = create_tmp_var (array_type);
2137   SET_DECL_ALIGN (var, TREE_INT_CST_LOW (gimple_call_arg (stmt, 1)));
2138   {
2139     struct ptr_info_def *pi = SSA_NAME_PTR_INFO (lhs);
2140     if (pi != NULL && !pi->pt.anything)
2141       {
2142         bool singleton_p;
2143         unsigned uid;
2144         singleton_p = pt_solution_singleton_or_null_p (&pi->pt, &uid);
2145         gcc_assert (singleton_p);
2146         SET_DECL_PT_UID (var, uid);
2147       }
2148   }
2149
2150   /* Fold alloca to the address of the array.  */
2151   return fold_convert (TREE_TYPE (lhs), build_fold_addr_expr (var));
2152 }
2153
2154 /* Fold the stmt at *GSI with CCP specific information that propagating
2155    and regular folding does not catch.  */
2156
2157 static bool
2158 ccp_fold_stmt (gimple_stmt_iterator *gsi)
2159 {
2160   gimple *stmt = gsi_stmt (*gsi);
2161
2162   switch (gimple_code (stmt))
2163     {
2164     case GIMPLE_COND:
2165       {
2166         gcond *cond_stmt = as_a <gcond *> (stmt);
2167         ccp_prop_value_t val;
2168         /* Statement evaluation will handle type mismatches in constants
2169            more gracefully than the final propagation.  This allows us to
2170            fold more conditionals here.  */
2171         val = evaluate_stmt (stmt);
2172         if (val.lattice_val != CONSTANT
2173             || val.mask != 0)
2174           return false;
2175
2176         if (dump_file)
2177           {
2178             fprintf (dump_file, "Folding predicate ");
2179             print_gimple_expr (dump_file, stmt, 0, 0);
2180             fprintf (dump_file, " to ");
2181             print_generic_expr (dump_file, val.value, 0);
2182             fprintf (dump_file, "\n");
2183           }
2184
2185         if (integer_zerop (val.value))
2186           gimple_cond_make_false (cond_stmt);
2187         else
2188           gimple_cond_make_true (cond_stmt);
2189
2190         return true;
2191       }
2192
2193     case GIMPLE_CALL:
2194       {
2195         tree lhs = gimple_call_lhs (stmt);
2196         int flags = gimple_call_flags (stmt);
2197         tree val;
2198         tree argt;
2199         bool changed = false;
2200         unsigned i;
2201
2202         /* If the call was folded into a constant make sure it goes
2203            away even if we cannot propagate into all uses because of
2204            type issues.  */
2205         if (lhs
2206             && TREE_CODE (lhs) == SSA_NAME
2207             && (val = get_constant_value (lhs))
2208             /* Don't optimize away calls that have side-effects.  */
2209             && (flags & (ECF_CONST|ECF_PURE)) != 0
2210             && (flags & ECF_LOOPING_CONST_OR_PURE) == 0)
2211           {
2212             tree new_rhs = unshare_expr (val);
2213             bool res;
2214             if (!useless_type_conversion_p (TREE_TYPE (lhs),
2215                                             TREE_TYPE (new_rhs)))
2216               new_rhs = fold_convert (TREE_TYPE (lhs), new_rhs);
2217             res = update_call_from_tree (gsi, new_rhs);
2218             gcc_assert (res);
2219             return true;
2220           }
2221
2222         /* Internal calls provide no argument types, so the extra laxity
2223            for normal calls does not apply.  */
2224         if (gimple_call_internal_p (stmt))
2225           return false;
2226
2227         /* The heuristic of fold_builtin_alloca_with_align differs before and
2228            after inlining, so we don't require the arg to be changed into a
2229            constant for folding, but just to be constant.  */
2230         if (gimple_call_builtin_p (stmt, BUILT_IN_ALLOCA_WITH_ALIGN))
2231           {
2232             tree new_rhs = fold_builtin_alloca_with_align (stmt);
2233             if (new_rhs)
2234               {
2235                 bool res = update_call_from_tree (gsi, new_rhs);
2236                 tree var = TREE_OPERAND (TREE_OPERAND (new_rhs, 0),0);
2237                 gcc_assert (res);
2238                 insert_clobbers_for_var (*gsi, var);
2239                 return true;
2240               }
2241           }
2242
2243         /* Propagate into the call arguments.  Compared to replace_uses_in
2244            this can use the argument slot types for type verification
2245            instead of the current argument type.  We also can safely
2246            drop qualifiers here as we are dealing with constants anyway.  */
2247         argt = TYPE_ARG_TYPES (gimple_call_fntype (stmt));
2248         for (i = 0; i < gimple_call_num_args (stmt) && argt;
2249              ++i, argt = TREE_CHAIN (argt))
2250           {
2251             tree arg = gimple_call_arg (stmt, i);
2252             if (TREE_CODE (arg) == SSA_NAME
2253                 && (val = get_constant_value (arg))
2254                 && useless_type_conversion_p
2255                      (TYPE_MAIN_VARIANT (TREE_VALUE (argt)),
2256                       TYPE_MAIN_VARIANT (TREE_TYPE (val))))
2257               {
2258                 gimple_call_set_arg (stmt, i, unshare_expr (val));
2259                 changed = true;
2260               }
2261           }
2262
2263         return changed;
2264       }
2265
2266     case GIMPLE_ASSIGN:
2267       {
2268         tree lhs = gimple_assign_lhs (stmt);
2269         tree val;
2270
2271         /* If we have a load that turned out to be constant replace it
2272            as we cannot propagate into all uses in all cases.  */
2273         if (gimple_assign_single_p (stmt)
2274             && TREE_CODE (lhs) == SSA_NAME
2275             && (val = get_constant_value (lhs)))
2276           {
2277             tree rhs = unshare_expr (val);
2278             if (!useless_type_conversion_p (TREE_TYPE (lhs), TREE_TYPE (rhs)))
2279               rhs = fold_build1 (VIEW_CONVERT_EXPR, TREE_TYPE (lhs), rhs);
2280             gimple_assign_set_rhs_from_tree (gsi, rhs);
2281             return true;
2282           }
2283
2284         return false;
2285       }
2286
2287     default:
2288       return false;
2289     }
2290 }
2291
2292 /* Visit the assignment statement STMT.  Set the value of its LHS to the
2293    value computed by the RHS and store LHS in *OUTPUT_P.  If STMT
2294    creates virtual definitions, set the value of each new name to that
2295    of the RHS (if we can derive a constant out of the RHS).
2296    Value-returning call statements also perform an assignment, and
2297    are handled here.  */
2298
2299 static enum ssa_prop_result
2300 visit_assignment (gimple *stmt, tree *output_p)
2301 {
2302   ccp_prop_value_t val;
2303   enum ssa_prop_result retval = SSA_PROP_NOT_INTERESTING;
2304
2305   tree lhs = gimple_get_lhs (stmt);
2306   if (TREE_CODE (lhs) == SSA_NAME)
2307     {
2308       /* Evaluate the statement, which could be
2309          either a GIMPLE_ASSIGN or a GIMPLE_CALL.  */
2310       val = evaluate_stmt (stmt);
2311
2312       /* If STMT is an assignment to an SSA_NAME, we only have one
2313          value to set.  */
2314       if (set_lattice_value (lhs, &val))
2315         {
2316           *output_p = lhs;
2317           if (val.lattice_val == VARYING)
2318             retval = SSA_PROP_VARYING;
2319           else
2320             retval = SSA_PROP_INTERESTING;
2321         }
2322     }
2323
2324   return retval;
2325 }
2326
2327
2328 /* Visit the conditional statement STMT.  Return SSA_PROP_INTERESTING
2329    if it can determine which edge will be taken.  Otherwise, return
2330    SSA_PROP_VARYING.  */
2331
2332 static enum ssa_prop_result
2333 visit_cond_stmt (gimple *stmt, edge *taken_edge_p)
2334 {
2335   ccp_prop_value_t val;
2336   basic_block block;
2337
2338   block = gimple_bb (stmt);
2339   val = evaluate_stmt (stmt);
2340   if (val.lattice_val != CONSTANT
2341       || val.mask != 0)
2342     return SSA_PROP_VARYING;
2343
2344   /* Find which edge out of the conditional block will be taken and add it
2345      to the worklist.  If no single edge can be determined statically,
2346      return SSA_PROP_VARYING to feed all the outgoing edges to the
2347      propagation engine.  */
2348   *taken_edge_p = find_taken_edge (block, val.value);
2349   if (*taken_edge_p)
2350     return SSA_PROP_INTERESTING;
2351   else
2352     return SSA_PROP_VARYING;
2353 }
2354
2355
2356 /* Evaluate statement STMT.  If the statement produces an output value and
2357    its evaluation changes the lattice value of its output, return
2358    SSA_PROP_INTERESTING and set *OUTPUT_P to the SSA_NAME holding the
2359    output value.
2360
2361    If STMT is a conditional branch and we can determine its truth
2362    value, set *TAKEN_EDGE_P accordingly.  If STMT produces a varying
2363    value, return SSA_PROP_VARYING.  */
2364
2365 static enum ssa_prop_result
2366 ccp_visit_stmt (gimple *stmt, edge *taken_edge_p, tree *output_p)
2367 {
2368   tree def;
2369   ssa_op_iter iter;
2370
2371   if (dump_file && (dump_flags & TDF_DETAILS))
2372     {
2373       fprintf (dump_file, "\nVisiting statement:\n");
2374       print_gimple_stmt (dump_file, stmt, 0, dump_flags);
2375     }
2376
2377   switch (gimple_code (stmt))
2378     {
2379       case GIMPLE_ASSIGN:
2380         /* If the statement is an assignment that produces a single
2381            output value, evaluate its RHS to see if the lattice value of
2382            its output has changed.  */
2383         return visit_assignment (stmt, output_p);
2384
2385       case GIMPLE_CALL:
2386         /* A value-returning call also performs an assignment.  */
2387         if (gimple_call_lhs (stmt) != NULL_TREE)
2388           return visit_assignment (stmt, output_p);
2389         break;
2390
2391       case GIMPLE_COND:
2392       case GIMPLE_SWITCH:
2393         /* If STMT is a conditional branch, see if we can determine
2394            which branch will be taken.   */
2395         /* FIXME.  It appears that we should be able to optimize
2396            computed GOTOs here as well.  */
2397         return visit_cond_stmt (stmt, taken_edge_p);
2398
2399       default:
2400         break;
2401     }
2402
2403   /* Any other kind of statement is not interesting for constant
2404      propagation and, therefore, not worth simulating.  */
2405   if (dump_file && (dump_flags & TDF_DETAILS))
2406     fprintf (dump_file, "No interesting values produced.  Marked VARYING.\n");
2407
2408   /* Definitions made by statements other than assignments to
2409      SSA_NAMEs represent unknown modifications to their outputs.
2410      Mark them VARYING.  */
2411   FOR_EACH_SSA_TREE_OPERAND (def, stmt, iter, SSA_OP_ALL_DEFS)
2412     set_value_varying (def);
2413
2414   return SSA_PROP_VARYING;
2415 }
2416
2417
2418 /* Main entry point for SSA Conditional Constant Propagation.  If NONZERO_P,
2419    record nonzero bits.  */
2420
2421 static unsigned int
2422 do_ssa_ccp (bool nonzero_p)
2423 {
2424   unsigned int todo = 0;
2425   calculate_dominance_info (CDI_DOMINATORS);
2426
2427   ccp_initialize ();
2428   ssa_propagate (ccp_visit_stmt, ccp_visit_phi_node);
2429   if (ccp_finalize (nonzero_p || flag_ipa_bit_cp))
2430     {
2431       todo = (TODO_cleanup_cfg | TODO_update_ssa);
2432
2433       /* ccp_finalize does not preserve loop-closed ssa.  */
2434       loops_state_clear (LOOP_CLOSED_SSA);
2435     }
2436
2437   free_dominance_info (CDI_DOMINATORS);
2438   return todo;
2439 }
2440
2441
2442 namespace {
2443
2444 const pass_data pass_data_ccp =
2445 {
2446   GIMPLE_PASS, /* type */
2447   "ccp", /* name */
2448   OPTGROUP_NONE, /* optinfo_flags */
2449   TV_TREE_CCP, /* tv_id */
2450   ( PROP_cfg | PROP_ssa ), /* properties_required */
2451   0, /* properties_provided */
2452   0, /* properties_destroyed */
2453   0, /* todo_flags_start */
2454   TODO_update_address_taken, /* todo_flags_finish */
2455 };
2456
2457 class pass_ccp : public gimple_opt_pass
2458 {
2459 public:
2460   pass_ccp (gcc::context *ctxt)
2461     : gimple_opt_pass (pass_data_ccp, ctxt), nonzero_p (false)
2462   {}
2463
2464   /* opt_pass methods: */
2465   opt_pass * clone () { return new pass_ccp (m_ctxt); }
2466   void set_pass_param (unsigned int n, bool param)
2467     {
2468       gcc_assert (n == 0);
2469       nonzero_p = param;
2470     }
2471   virtual bool gate (function *) { return flag_tree_ccp != 0; }
2472   virtual unsigned int execute (function *) { return do_ssa_ccp (nonzero_p); }
2473
2474  private:
2475   /* Determines whether the pass instance records nonzero bits.  */
2476   bool nonzero_p;
2477 }; // class pass_ccp
2478
2479 } // anon namespace
2480
2481 gimple_opt_pass *
2482 make_pass_ccp (gcc::context *ctxt)
2483 {
2484   return new pass_ccp (ctxt);
2485 }
2486
2487
2488
2489 /* Try to optimize out __builtin_stack_restore.  Optimize it out
2490    if there is another __builtin_stack_restore in the same basic
2491    block and no calls or ASM_EXPRs are in between, or if this block's
2492    only outgoing edge is to EXIT_BLOCK and there are no calls or
2493    ASM_EXPRs after this __builtin_stack_restore.  */
2494
2495 static tree
2496 optimize_stack_restore (gimple_stmt_iterator i)
2497 {
2498   tree callee;
2499   gimple *stmt;
2500
2501   basic_block bb = gsi_bb (i);
2502   gimple *call = gsi_stmt (i);
2503
2504   if (gimple_code (call) != GIMPLE_CALL
2505       || gimple_call_num_args (call) != 1
2506       || TREE_CODE (gimple_call_arg (call, 0)) != SSA_NAME
2507       || !POINTER_TYPE_P (TREE_TYPE (gimple_call_arg (call, 0))))
2508     return NULL_TREE;
2509
2510   for (gsi_next (&i); !gsi_end_p (i); gsi_next (&i))
2511     {
2512       stmt = gsi_stmt (i);
2513       if (gimple_code (stmt) == GIMPLE_ASM)
2514         return NULL_TREE;
2515       if (gimple_code (stmt) != GIMPLE_CALL)
2516         continue;
2517
2518       callee = gimple_call_fndecl (stmt);
2519       if (!callee
2520           || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
2521           /* All regular builtins are ok, just obviously not alloca.  */
2522           || DECL_FUNCTION_CODE (callee) == BUILT_IN_ALLOCA
2523           || DECL_FUNCTION_CODE (callee) == BUILT_IN_ALLOCA_WITH_ALIGN)
2524         return NULL_TREE;
2525
2526       if (DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_RESTORE)
2527         goto second_stack_restore;
2528     }
2529
2530   if (!gsi_end_p (i))
2531     return NULL_TREE;
2532
2533   /* Allow one successor of the exit block, or zero successors.  */
2534   switch (EDGE_COUNT (bb->succs))
2535     {
2536     case 0:
2537       break;
2538     case 1:
2539       if (single_succ_edge (bb)->dest != EXIT_BLOCK_PTR_FOR_FN (cfun))
2540         return NULL_TREE;
2541       break;
2542     default:
2543       return NULL_TREE;
2544     }
2545  second_stack_restore:
2546
2547   /* If there's exactly one use, then zap the call to __builtin_stack_save.
2548      If there are multiple uses, then the last one should remove the call.
2549      In any case, whether the call to __builtin_stack_save can be removed
2550      or not is irrelevant to removing the call to __builtin_stack_restore.  */
2551   if (has_single_use (gimple_call_arg (call, 0)))
2552     {
2553       gimple *stack_save = SSA_NAME_DEF_STMT (gimple_call_arg (call, 0));
2554       if (is_gimple_call (stack_save))
2555         {
2556           callee = gimple_call_fndecl (stack_save);
2557           if (callee
2558               && DECL_BUILT_IN_CLASS (callee) == BUILT_IN_NORMAL
2559               && DECL_FUNCTION_CODE (callee) == BUILT_IN_STACK_SAVE)
2560             {
2561               gimple_stmt_iterator stack_save_gsi;
2562               tree rhs;
2563
2564               stack_save_gsi = gsi_for_stmt (stack_save);
2565               rhs = build_int_cst (TREE_TYPE (gimple_call_arg (call, 0)), 0);
2566               update_call_from_tree (&stack_save_gsi, rhs);
2567             }
2568         }
2569     }
2570
2571   /* No effect, so the statement will be deleted.  */
2572   return integer_zero_node;
2573 }
2574
2575 /* If va_list type is a simple pointer and nothing special is needed,
2576    optimize __builtin_va_start (&ap, 0) into ap = __builtin_next_arg (0),
2577    __builtin_va_end (&ap) out as NOP and __builtin_va_copy into a simple
2578    pointer assignment.  */
2579
2580 static tree
2581 optimize_stdarg_builtin (gimple *call)
2582 {
2583   tree callee, lhs, rhs, cfun_va_list;
2584   bool va_list_simple_ptr;
2585   location_t loc = gimple_location (call);
2586
2587   if (gimple_code (call) != GIMPLE_CALL)
2588     return NULL_TREE;
2589
2590   callee = gimple_call_fndecl (call);
2591
2592   cfun_va_list = targetm.fn_abi_va_list (callee);
2593   va_list_simple_ptr = POINTER_TYPE_P (cfun_va_list)
2594                        && (TREE_TYPE (cfun_va_list) == void_type_node
2595                            || TREE_TYPE (cfun_va_list) == char_type_node);
2596
2597   switch (DECL_FUNCTION_CODE (callee))
2598     {
2599     case BUILT_IN_VA_START:
2600       if (!va_list_simple_ptr
2601           || targetm.expand_builtin_va_start != NULL
2602           || !builtin_decl_explicit_p (BUILT_IN_NEXT_ARG))
2603         return NULL_TREE;
2604
2605       if (gimple_call_num_args (call) != 2)
2606         return NULL_TREE;
2607
2608       lhs = gimple_call_arg (call, 0);
2609       if (!POINTER_TYPE_P (TREE_TYPE (lhs))
2610           || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
2611              != TYPE_MAIN_VARIANT (cfun_va_list))
2612         return NULL_TREE;
2613
2614       lhs = build_fold_indirect_ref_loc (loc, lhs);
2615       rhs = build_call_expr_loc (loc, builtin_decl_explicit (BUILT_IN_NEXT_ARG),
2616                              1, integer_zero_node);
2617       rhs = fold_convert_loc (loc, TREE_TYPE (lhs), rhs);
2618       return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
2619
2620     case BUILT_IN_VA_COPY:
2621       if (!va_list_simple_ptr)
2622         return NULL_TREE;
2623
2624       if (gimple_call_num_args (call) != 2)
2625         return NULL_TREE;
2626
2627       lhs = gimple_call_arg (call, 0);
2628       if (!POINTER_TYPE_P (TREE_TYPE (lhs))
2629           || TYPE_MAIN_VARIANT (TREE_TYPE (TREE_TYPE (lhs)))
2630              != TYPE_MAIN_VARIANT (cfun_va_list))
2631         return NULL_TREE;
2632
2633       lhs = build_fold_indirect_ref_loc (loc, lhs);
2634       rhs = gimple_call_arg (call, 1);
2635       if (TYPE_MAIN_VARIANT (TREE_TYPE (rhs))
2636           != TYPE_MAIN_VARIANT (cfun_va_list))
2637         return NULL_TREE;
2638
2639       rhs = fold_convert_loc (loc, TREE_TYPE (lhs), rhs);
2640       return build2 (MODIFY_EXPR, TREE_TYPE (lhs), lhs, rhs);
2641
2642     case BUILT_IN_VA_END:
2643       /* No effect, so the statement will be deleted.  */
2644       return integer_zero_node;
2645
2646     default:
2647       gcc_unreachable ();
2648     }
2649 }
2650
2651 /* Attemp to make the block of __builtin_unreachable I unreachable by changing
2652    the incoming jumps.  Return true if at least one jump was changed.  */
2653
2654 static bool
2655 optimize_unreachable (gimple_stmt_iterator i)
2656 {
2657   basic_block bb = gsi_bb (i);
2658   gimple_stmt_iterator gsi;
2659   gimple *stmt;
2660   edge_iterator ei;
2661   edge e;
2662   bool ret;
2663
2664   if (flag_sanitize & SANITIZE_UNREACHABLE)
2665     return false;
2666
2667   for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
2668     {
2669       stmt = gsi_stmt (gsi);
2670
2671       if (is_gimple_debug (stmt))
2672        continue;
2673
2674       if (glabel *label_stmt = dyn_cast <glabel *> (stmt))
2675         {
2676           /* Verify we do not need to preserve the label.  */
2677           if (FORCED_LABEL (gimple_label_label (label_stmt)))
2678             return false;
2679
2680           continue;
2681         }
2682
2683       /* Only handle the case that __builtin_unreachable is the first statement
2684          in the block.  We rely on DCE to remove stmts without side-effects
2685          before __builtin_unreachable.  */
2686       if (gsi_stmt (gsi) != gsi_stmt (i))
2687         return false;
2688     }
2689
2690   ret = false;
2691   FOR_EACH_EDGE (e, ei, bb->preds)
2692     {
2693       gsi = gsi_last_bb (e->src);
2694       if (gsi_end_p (gsi))
2695         continue;
2696
2697       stmt = gsi_stmt (gsi);
2698       if (gcond *cond_stmt = dyn_cast <gcond *> (stmt))
2699         {
2700           if (e->flags & EDGE_TRUE_VALUE)
2701             gimple_cond_make_false (cond_stmt);
2702           else if (e->flags & EDGE_FALSE_VALUE)
2703             gimple_cond_make_true (cond_stmt);
2704           else
2705             gcc_unreachable ();
2706           update_stmt (cond_stmt);
2707         }
2708       else
2709         {
2710           /* Todo: handle other cases, f.i. switch statement.  */
2711           continue;
2712         }
2713
2714       ret = true;
2715     }
2716
2717   return ret;
2718 }
2719
2720 /* Optimize
2721      mask_2 = 1 << cnt_1;
2722      _4 = __atomic_fetch_or_* (ptr_6, mask_2, _3);
2723      _5 = _4 & mask_2;
2724    to
2725      _4 = ATOMIC_BIT_TEST_AND_SET (ptr_6, cnt_1, 0, _3);
2726      _5 = _4;
2727    If _5 is only used in _5 != 0 or _5 == 0 comparisons, 1
2728    is passed instead of 0, and the builtin just returns a zero
2729    or 1 value instead of the actual bit.
2730    Similarly for __sync_fetch_and_or_* (without the ", _3" part
2731    in there), and/or if mask_2 is a power of 2 constant.
2732    Similarly for xor instead of or, use ATOMIC_BIT_TEST_AND_COMPLEMENT
2733    in that case.  And similarly for and instead of or, except that
2734    the second argument to the builtin needs to be one's complement
2735    of the mask instead of mask.  */
2736
2737 static void
2738 optimize_atomic_bit_test_and (gimple_stmt_iterator *gsip,
2739                               enum internal_fn fn, bool has_model_arg,
2740                               bool after)
2741 {
2742   gimple *call = gsi_stmt (*gsip);
2743   tree lhs = gimple_call_lhs (call);
2744   use_operand_p use_p;
2745   gimple *use_stmt;
2746   tree mask, bit;
2747   optab optab;
2748
2749   if (!flag_inline_atomics
2750       || optimize_debug
2751       || !gimple_call_builtin_p (call, BUILT_IN_NORMAL)
2752       || !lhs
2753       || SSA_NAME_OCCURS_IN_ABNORMAL_PHI (lhs)
2754       || !single_imm_use (lhs, &use_p, &use_stmt)
2755       || !is_gimple_assign (use_stmt)
2756       || gimple_assign_rhs_code (use_stmt) != BIT_AND_EXPR
2757       || !gimple_vdef (call))
2758     return;
2759
2760   switch (fn)
2761     {
2762     case IFN_ATOMIC_BIT_TEST_AND_SET:
2763       optab = atomic_bit_test_and_set_optab;
2764       break;
2765     case IFN_ATOMIC_BIT_TEST_AND_COMPLEMENT:
2766       optab = atomic_bit_test_and_complement_optab;
2767       break;
2768     case IFN_ATOMIC_BIT_TEST_AND_RESET:
2769       optab = atomic_bit_test_and_reset_optab;
2770       break;
2771     default:
2772       return;
2773     }
2774
2775   if (optab_handler (optab, TYPE_MODE (TREE_TYPE (lhs))) == CODE_FOR_nothing)
2776     return;
2777
2778   mask = gimple_call_arg (call, 1);
2779   tree use_lhs = gimple_assign_lhs (use_stmt);
2780   if (!use_lhs)
2781     return;
2782
2783   if (TREE_CODE (mask) == INTEGER_CST)
2784     {
2785       if (fn == IFN_ATOMIC_BIT_TEST_AND_RESET)
2786         mask = const_unop (BIT_NOT_EXPR, TREE_TYPE (mask), mask);
2787       mask = fold_convert (TREE_TYPE (lhs), mask);
2788       int ibit = tree_log2 (mask);
2789       if (ibit < 0)
2790         return;
2791       bit = build_int_cst (TREE_TYPE (lhs), ibit);
2792     }
2793   else if (TREE_CODE (mask) == SSA_NAME)
2794     {
2795       gimple *g = SSA_NAME_DEF_STMT (mask);
2796       if (fn == IFN_ATOMIC_BIT_TEST_AND_RESET)
2797         {
2798           if (!is_gimple_assign (g)
2799               || gimple_assign_rhs_code (g) != BIT_NOT_EXPR)
2800             return;
2801           mask = gimple_assign_rhs1 (g);
2802           if (TREE_CODE (mask) != SSA_NAME)
2803             return;
2804           g = SSA_NAME_DEF_STMT (mask);
2805         }
2806       if (!is_gimple_assign (g)
2807           || gimple_assign_rhs_code (g) != LSHIFT_EXPR
2808           || !integer_onep (gimple_assign_rhs1 (g)))
2809         return;
2810       bit = gimple_assign_rhs2 (g);
2811     }
2812   else
2813     return;
2814
2815   if (gimple_assign_rhs1 (use_stmt) == lhs)
2816     {
2817       if (!operand_equal_p (gimple_assign_rhs2 (use_stmt), mask, 0))
2818         return;
2819     }
2820   else if (gimple_assign_rhs2 (use_stmt) != lhs
2821            || !operand_equal_p (gimple_assign_rhs1 (use_stmt), mask, 0))
2822     return;
2823
2824   bool use_bool = true;
2825   bool has_debug_uses = false;
2826   imm_use_iterator iter;
2827   gimple *g;
2828
2829   if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (use_lhs))
2830     use_bool = false;
2831   FOR_EACH_IMM_USE_STMT (g, iter, use_lhs)
2832     {
2833       enum tree_code code = ERROR_MARK;
2834       tree op0 = NULL_TREE, op1 = NULL_TREE;
2835       if (is_gimple_debug (g))
2836         {
2837           has_debug_uses = true;
2838           continue;
2839         }
2840       else if (is_gimple_assign (g))
2841         switch (gimple_assign_rhs_code (g))
2842           {
2843           case COND_EXPR:
2844             op1 = gimple_assign_rhs1 (g);
2845             code = TREE_CODE (op1);
2846             op0 = TREE_OPERAND (op1, 0);
2847             op1 = TREE_OPERAND (op1, 1);
2848             break;
2849           case EQ_EXPR:
2850           case NE_EXPR:
2851             code = gimple_assign_rhs_code (g);
2852             op0 = gimple_assign_rhs1 (g);
2853             op1 = gimple_assign_rhs2 (g);
2854             break;
2855           default:
2856             break;
2857           }
2858       else if (gimple_code (g) == GIMPLE_COND)
2859         {
2860           code = gimple_cond_code (g);
2861           op0 = gimple_cond_lhs (g);
2862           op1 = gimple_cond_rhs (g);
2863         }
2864
2865       if ((code == EQ_EXPR || code == NE_EXPR)
2866           && op0 == use_lhs
2867           && integer_zerop (op1))
2868         {
2869           use_operand_p use_p;
2870           int n = 0;
2871           FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
2872             n++;
2873           if (n == 1)
2874             continue;
2875         }
2876
2877       use_bool = false;
2878       BREAK_FROM_IMM_USE_STMT (iter);
2879     }
2880
2881   tree new_lhs = make_ssa_name (TREE_TYPE (lhs));
2882   tree flag = build_int_cst (TREE_TYPE (lhs), use_bool);
2883   if (has_model_arg)
2884     g = gimple_build_call_internal (fn, 4, gimple_call_arg (call, 0),
2885                                     bit, flag, gimple_call_arg (call, 2));
2886   else
2887     g = gimple_build_call_internal (fn, 3, gimple_call_arg (call, 0),
2888                                     bit, flag);
2889   gimple_call_set_lhs (g, new_lhs);
2890   gimple_set_location (g, gimple_location (call));
2891   gimple_set_vuse (g, gimple_vuse (call));
2892   gimple_set_vdef (g, gimple_vdef (call));
2893   bool throws = stmt_can_throw_internal (call);
2894   gimple_call_set_nothrow (as_a <gcall *> (g),
2895                            gimple_call_nothrow_p (as_a <gcall *> (call)));
2896   SSA_NAME_DEF_STMT (gimple_vdef (call)) = g;
2897   gimple_stmt_iterator gsi = *gsip;
2898   gsi_insert_after (&gsi, g, GSI_NEW_STMT);
2899   edge e = NULL;
2900   if (throws)
2901     {
2902       maybe_clean_or_replace_eh_stmt (call, g);
2903       if (after || (use_bool && has_debug_uses))
2904         e = find_fallthru_edge (gsi_bb (gsi)->succs);
2905     }
2906   if (after)
2907     {
2908       /* The internal function returns the value of the specified bit
2909          before the atomic operation.  If we are interested in the value
2910          of the specified bit after the atomic operation (makes only sense
2911          for xor, otherwise the bit content is compile time known),
2912          we need to invert the bit.  */
2913       g = gimple_build_assign (make_ssa_name (TREE_TYPE (lhs)),
2914                                BIT_XOR_EXPR, new_lhs,
2915                                use_bool ? build_int_cst (TREE_TYPE (lhs), 1)
2916                                         : mask);
2917       new_lhs = gimple_assign_lhs (g);
2918       if (throws)
2919         {
2920           gsi_insert_on_edge_immediate (e, g);
2921           gsi = gsi_for_stmt (g);
2922         }
2923       else
2924         gsi_insert_after (&gsi, g, GSI_NEW_STMT);
2925     }
2926   if (use_bool && has_debug_uses)
2927     {
2928       tree temp = NULL_TREE;
2929       if (!throws || after || single_pred_p (e->dest))
2930         {
2931           temp = make_node (DEBUG_EXPR_DECL);
2932           DECL_ARTIFICIAL (temp) = 1;
2933           TREE_TYPE (temp) = TREE_TYPE (lhs);
2934           SET_DECL_MODE (temp, TYPE_MODE (TREE_TYPE (lhs)));
2935           tree t = build2 (LSHIFT_EXPR, TREE_TYPE (lhs), new_lhs, bit);
2936           g = gimple_build_debug_bind (temp, t, g);
2937           if (throws && !after)
2938             {
2939               gsi = gsi_after_labels (e->dest);
2940               gsi_insert_before (&gsi, g, GSI_SAME_STMT);
2941             }
2942           else
2943             gsi_insert_after (&gsi, g, GSI_NEW_STMT);
2944         }
2945       FOR_EACH_IMM_USE_STMT (g, iter, use_lhs)
2946         if (is_gimple_debug (g))
2947           {
2948             use_operand_p use_p;
2949             if (temp == NULL_TREE)
2950               gimple_debug_bind_reset_value (g);
2951             else
2952               FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
2953                 SET_USE (use_p, temp);
2954             update_stmt (g);
2955           }
2956     }
2957   SSA_NAME_OCCURS_IN_ABNORMAL_PHI (new_lhs)
2958     = SSA_NAME_OCCURS_IN_ABNORMAL_PHI (use_lhs);
2959   replace_uses_by (use_lhs, new_lhs);
2960   gsi = gsi_for_stmt (use_stmt);
2961   gsi_remove (&gsi, true);
2962   release_defs (use_stmt);
2963   gsi_remove (gsip, true);
2964   release_ssa_name (lhs);
2965 }
2966
2967 /* Optimize
2968    a = {};
2969    b = a;
2970    into
2971    a = {};
2972    b = {};
2973    Similarly for memset (&a, ..., sizeof (a)); instead of a = {};
2974    and/or memcpy (&b, &a, sizeof (a)); instead of b = a;  */
2975
2976 static void
2977 optimize_memcpy (gimple_stmt_iterator *gsip, tree dest, tree src, tree len)
2978 {
2979   gimple *stmt = gsi_stmt (*gsip);
2980   if (gimple_has_volatile_ops (stmt))
2981     return;
2982
2983   tree vuse = gimple_vuse (stmt);
2984   if (vuse == NULL)
2985     return;
2986
2987   gimple *defstmt = SSA_NAME_DEF_STMT (vuse);
2988   tree src2 = NULL_TREE, len2 = NULL_TREE;
2989   HOST_WIDE_INT offset, offset2;
2990   tree val = integer_zero_node;
2991   if (gimple_store_p (defstmt)
2992       && gimple_assign_single_p (defstmt)
2993       && TREE_CODE (gimple_assign_rhs1 (defstmt)) == CONSTRUCTOR
2994       && !gimple_clobber_p (defstmt))
2995     src2 = gimple_assign_lhs (defstmt);
2996   else if (gimple_call_builtin_p (defstmt, BUILT_IN_MEMSET)
2997            && TREE_CODE (gimple_call_arg (defstmt, 0)) == ADDR_EXPR
2998            && TREE_CODE (gimple_call_arg (defstmt, 1)) == INTEGER_CST)
2999     {
3000       src2 = TREE_OPERAND (gimple_call_arg (defstmt, 0), 0);
3001       len2 = gimple_call_arg (defstmt, 2);
3002       val = gimple_call_arg (defstmt, 1);
3003       /* For non-0 val, we'd have to transform stmt from assignment
3004          into memset (only if dest is addressable).  */
3005       if (!integer_zerop (val) && is_gimple_assign (stmt))
3006         src2 = NULL_TREE;
3007     }
3008
3009   if (src2 == NULL_TREE)
3010     return;
3011
3012   if (len == NULL_TREE)
3013     len = (TREE_CODE (src) == COMPONENT_REF
3014            ? DECL_SIZE_UNIT (TREE_OPERAND (src, 1))
3015            : TYPE_SIZE_UNIT (TREE_TYPE (src)));
3016   if (len2 == NULL_TREE)
3017     len2 = (TREE_CODE (src2) == COMPONENT_REF
3018             ? DECL_SIZE_UNIT (TREE_OPERAND (src2, 1))
3019             : TYPE_SIZE_UNIT (TREE_TYPE (src2)));
3020   if (len == NULL_TREE
3021       || TREE_CODE (len) != INTEGER_CST
3022       || len2 == NULL_TREE
3023       || TREE_CODE (len2) != INTEGER_CST)
3024     return;
3025
3026   src = get_addr_base_and_unit_offset (src, &offset);
3027   src2 = get_addr_base_and_unit_offset (src2, &offset2);
3028   if (src == NULL_TREE
3029       || src2 == NULL_TREE
3030       || offset < offset2)
3031     return;
3032
3033   if (!operand_equal_p (src, src2, 0))
3034     return;
3035
3036   /* [ src + offset2, src + offset2 + len2 - 1 ] is set to val.
3037      Make sure that
3038      [ src + offset, src + offset + len - 1 ] is a subset of that.  */
3039   if (wi::to_offset (len) + (offset - offset2) > wi::to_offset (len2))
3040     return;
3041
3042   if (dump_file && (dump_flags & TDF_DETAILS))
3043     {
3044       fprintf (dump_file, "Simplified\n  ");
3045       print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3046       fprintf (dump_file, "after previous\n  ");
3047       print_gimple_stmt (dump_file, defstmt, 0, dump_flags);
3048     }
3049
3050   /* For simplicity, don't change the kind of the stmt,
3051      turn dest = src; into dest = {}; and memcpy (&dest, &src, len);
3052      into memset (&dest, val, len);
3053      In theory we could change dest = src into memset if dest
3054      is addressable (maybe beneficial if val is not 0), or
3055      memcpy (&dest, &src, len) into dest = {} if len is the size
3056      of dest, dest isn't volatile.  */
3057   if (is_gimple_assign (stmt))
3058     {
3059       tree ctor = build_constructor (TREE_TYPE (dest), NULL);
3060       gimple_assign_set_rhs_from_tree (gsip, ctor);
3061       update_stmt (stmt);
3062     }
3063   else /* If stmt is memcpy, transform it into memset.  */
3064     {
3065       gcall *call = as_a <gcall *> (stmt);
3066       tree fndecl = builtin_decl_implicit (BUILT_IN_MEMSET);
3067       gimple_call_set_fndecl (call, fndecl);
3068       gimple_call_set_fntype (call, TREE_TYPE (fndecl));
3069       gimple_call_set_arg (call, 1, val);
3070       update_stmt (stmt);
3071     }
3072
3073   if (dump_file && (dump_flags & TDF_DETAILS))
3074     {
3075       fprintf (dump_file, "into\n  ");
3076       print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3077     }
3078 }
3079
3080 /* A simple pass that attempts to fold all builtin functions.  This pass
3081    is run after we've propagated as many constants as we can.  */
3082
3083 namespace {
3084
3085 const pass_data pass_data_fold_builtins =
3086 {
3087   GIMPLE_PASS, /* type */
3088   "fab", /* name */
3089   OPTGROUP_NONE, /* optinfo_flags */
3090   TV_NONE, /* tv_id */
3091   ( PROP_cfg | PROP_ssa ), /* properties_required */
3092   0, /* properties_provided */
3093   0, /* properties_destroyed */
3094   0, /* todo_flags_start */
3095   TODO_update_ssa, /* todo_flags_finish */
3096 };
3097
3098 class pass_fold_builtins : public gimple_opt_pass
3099 {
3100 public:
3101   pass_fold_builtins (gcc::context *ctxt)
3102     : gimple_opt_pass (pass_data_fold_builtins, ctxt)
3103   {}
3104
3105   /* opt_pass methods: */
3106   opt_pass * clone () { return new pass_fold_builtins (m_ctxt); }
3107   virtual unsigned int execute (function *);
3108
3109 }; // class pass_fold_builtins
3110
3111 unsigned int
3112 pass_fold_builtins::execute (function *fun)
3113 {
3114   bool cfg_changed = false;
3115   basic_block bb;
3116   unsigned int todoflags = 0;
3117
3118   FOR_EACH_BB_FN (bb, fun)
3119     {
3120       gimple_stmt_iterator i;
3121       for (i = gsi_start_bb (bb); !gsi_end_p (i); )
3122         {
3123           gimple *stmt, *old_stmt;
3124           tree callee;
3125           enum built_in_function fcode;
3126
3127           stmt = gsi_stmt (i);
3128
3129           if (gimple_code (stmt) != GIMPLE_CALL)
3130             {
3131               /* Remove all *ssaname_N ={v} {CLOBBER}; stmts,
3132                  after the last GIMPLE DSE they aren't needed and might
3133                  unnecessarily keep the SSA_NAMEs live.  */
3134               if (gimple_clobber_p (stmt))
3135                 {
3136                   tree lhs = gimple_assign_lhs (stmt);
3137                   if (TREE_CODE (lhs) == MEM_REF
3138                       && TREE_CODE (TREE_OPERAND (lhs, 0)) == SSA_NAME)
3139                     {
3140                       unlink_stmt_vdef (stmt);
3141                       gsi_remove (&i, true);
3142                       release_defs (stmt);
3143                       continue;
3144                     }
3145                 }
3146               else if (gimple_assign_load_p (stmt) && gimple_store_p (stmt))
3147                 optimize_memcpy (&i, gimple_assign_lhs (stmt),
3148                                  gimple_assign_rhs1 (stmt), NULL_TREE);
3149               gsi_next (&i);
3150               continue;
3151             }
3152
3153           callee = gimple_call_fndecl (stmt);
3154           if (!callee || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL)
3155             {
3156               gsi_next (&i);
3157               continue;
3158             }
3159
3160           fcode = DECL_FUNCTION_CODE (callee);
3161           if (fold_stmt (&i))
3162             ;
3163           else
3164             {
3165               tree result = NULL_TREE;
3166               switch (DECL_FUNCTION_CODE (callee))
3167                 {
3168                 case BUILT_IN_CONSTANT_P:
3169                   /* Resolve __builtin_constant_p.  If it hasn't been
3170                      folded to integer_one_node by now, it's fairly
3171                      certain that the value simply isn't constant.  */
3172                   result = integer_zero_node;
3173                   break;
3174
3175                 case BUILT_IN_ASSUME_ALIGNED:
3176                   /* Remove __builtin_assume_aligned.  */
3177                   result = gimple_call_arg (stmt, 0);
3178                   break;
3179
3180                 case BUILT_IN_STACK_RESTORE:
3181                   result = optimize_stack_restore (i);
3182                   if (result)
3183                     break;
3184                   gsi_next (&i);
3185                   continue;
3186
3187                 case BUILT_IN_UNREACHABLE:
3188                   if (optimize_unreachable (i))
3189                     cfg_changed = true;
3190                   break;
3191
3192                 case BUILT_IN_ATOMIC_FETCH_OR_1:
3193                 case BUILT_IN_ATOMIC_FETCH_OR_2:
3194                 case BUILT_IN_ATOMIC_FETCH_OR_4:
3195                 case BUILT_IN_ATOMIC_FETCH_OR_8:
3196                 case BUILT_IN_ATOMIC_FETCH_OR_16:
3197                   optimize_atomic_bit_test_and (&i,
3198                                                 IFN_ATOMIC_BIT_TEST_AND_SET,
3199                                                 true, false);
3200                   break;
3201                 case BUILT_IN_SYNC_FETCH_AND_OR_1:
3202                 case BUILT_IN_SYNC_FETCH_AND_OR_2:
3203                 case BUILT_IN_SYNC_FETCH_AND_OR_4:
3204                 case BUILT_IN_SYNC_FETCH_AND_OR_8:
3205                 case BUILT_IN_SYNC_FETCH_AND_OR_16:
3206                   optimize_atomic_bit_test_and (&i,
3207                                                 IFN_ATOMIC_BIT_TEST_AND_SET,
3208                                                 false, false);
3209                   break;
3210
3211                 case BUILT_IN_ATOMIC_FETCH_XOR_1:
3212                 case BUILT_IN_ATOMIC_FETCH_XOR_2:
3213                 case BUILT_IN_ATOMIC_FETCH_XOR_4:
3214                 case BUILT_IN_ATOMIC_FETCH_XOR_8:
3215                 case BUILT_IN_ATOMIC_FETCH_XOR_16:
3216                   optimize_atomic_bit_test_and
3217                         (&i, IFN_ATOMIC_BIT_TEST_AND_COMPLEMENT, true, false);
3218                   break;
3219                 case BUILT_IN_SYNC_FETCH_AND_XOR_1:
3220                 case BUILT_IN_SYNC_FETCH_AND_XOR_2:
3221                 case BUILT_IN_SYNC_FETCH_AND_XOR_4:
3222                 case BUILT_IN_SYNC_FETCH_AND_XOR_8:
3223                 case BUILT_IN_SYNC_FETCH_AND_XOR_16:
3224                   optimize_atomic_bit_test_and
3225                         (&i, IFN_ATOMIC_BIT_TEST_AND_COMPLEMENT, false, false);
3226                   break;
3227
3228                 case BUILT_IN_ATOMIC_XOR_FETCH_1:
3229                 case BUILT_IN_ATOMIC_XOR_FETCH_2:
3230                 case BUILT_IN_ATOMIC_XOR_FETCH_4:
3231                 case BUILT_IN_ATOMIC_XOR_FETCH_8:
3232                 case BUILT_IN_ATOMIC_XOR_FETCH_16:
3233                   optimize_atomic_bit_test_and
3234                         (&i, IFN_ATOMIC_BIT_TEST_AND_COMPLEMENT, true, true);
3235                   break;
3236                 case BUILT_IN_SYNC_XOR_AND_FETCH_1:
3237                 case BUILT_IN_SYNC_XOR_AND_FETCH_2:
3238                 case BUILT_IN_SYNC_XOR_AND_FETCH_4:
3239                 case BUILT_IN_SYNC_XOR_AND_FETCH_8:
3240                 case BUILT_IN_SYNC_XOR_AND_FETCH_16:
3241                   optimize_atomic_bit_test_and
3242                         (&i, IFN_ATOMIC_BIT_TEST_AND_COMPLEMENT, false, true);
3243                   break;
3244
3245                 case BUILT_IN_ATOMIC_FETCH_AND_1:
3246                 case BUILT_IN_ATOMIC_FETCH_AND_2:
3247                 case BUILT_IN_ATOMIC_FETCH_AND_4:
3248                 case BUILT_IN_ATOMIC_FETCH_AND_8:
3249                 case BUILT_IN_ATOMIC_FETCH_AND_16:
3250                   optimize_atomic_bit_test_and (&i,
3251                                                 IFN_ATOMIC_BIT_TEST_AND_RESET,
3252                                                 true, false);
3253                   break;
3254                 case BUILT_IN_SYNC_FETCH_AND_AND_1:
3255                 case BUILT_IN_SYNC_FETCH_AND_AND_2:
3256                 case BUILT_IN_SYNC_FETCH_AND_AND_4:
3257                 case BUILT_IN_SYNC_FETCH_AND_AND_8:
3258                 case BUILT_IN_SYNC_FETCH_AND_AND_16:
3259                   optimize_atomic_bit_test_and (&i,
3260                                                 IFN_ATOMIC_BIT_TEST_AND_RESET,
3261                                                 false, false);
3262                   break;
3263
3264                 case BUILT_IN_MEMCPY:
3265                   if (gimple_call_builtin_p (stmt, BUILT_IN_NORMAL)
3266                       && TREE_CODE (gimple_call_arg (stmt, 0)) == ADDR_EXPR
3267                       && TREE_CODE (gimple_call_arg (stmt, 1)) == ADDR_EXPR
3268                       && TREE_CODE (gimple_call_arg (stmt, 2)) == INTEGER_CST)
3269                     {
3270                       tree dest = TREE_OPERAND (gimple_call_arg (stmt, 0), 0);
3271                       tree src = TREE_OPERAND (gimple_call_arg (stmt, 1), 0);
3272                       tree len = gimple_call_arg (stmt, 2);
3273                       optimize_memcpy (&i, dest, src, len);
3274                     }
3275                   break;
3276
3277                 case BUILT_IN_VA_START:
3278                 case BUILT_IN_VA_END:
3279                 case BUILT_IN_VA_COPY:
3280                   /* These shouldn't be folded before pass_stdarg.  */
3281                   result = optimize_stdarg_builtin (stmt);
3282                   break;
3283
3284                 default:;
3285                 }
3286
3287               if (!result)
3288                 {
3289                   gsi_next (&i);
3290                   continue;
3291                 }
3292
3293               if (!update_call_from_tree (&i, result))
3294                 gimplify_and_update_call_from_tree (&i, result);
3295             }
3296
3297           todoflags |= TODO_update_address_taken;
3298
3299           if (dump_file && (dump_flags & TDF_DETAILS))
3300             {
3301               fprintf (dump_file, "Simplified\n  ");
3302               print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3303             }
3304
3305           old_stmt = stmt;
3306           stmt = gsi_stmt (i);
3307           update_stmt (stmt);
3308
3309           if (maybe_clean_or_replace_eh_stmt (old_stmt, stmt)
3310               && gimple_purge_dead_eh_edges (bb))
3311             cfg_changed = true;
3312
3313           if (dump_file && (dump_flags & TDF_DETAILS))
3314             {
3315               fprintf (dump_file, "to\n  ");
3316               print_gimple_stmt (dump_file, stmt, 0, dump_flags);
3317               fprintf (dump_file, "\n");
3318             }
3319
3320           /* Retry the same statement if it changed into another
3321              builtin, there might be new opportunities now.  */
3322           if (gimple_code (stmt) != GIMPLE_CALL)
3323             {
3324               gsi_next (&i);
3325               continue;
3326             }
3327           callee = gimple_call_fndecl (stmt);
3328           if (!callee
3329               || DECL_BUILT_IN_CLASS (callee) != BUILT_IN_NORMAL
3330               || DECL_FUNCTION_CODE (callee) == fcode)
3331             gsi_next (&i);
3332         }
3333     }
3334
3335   /* Delete unreachable blocks.  */
3336   if (cfg_changed)
3337     todoflags |= TODO_cleanup_cfg;
3338
3339   return todoflags;
3340 }
3341
3342 } // anon namespace
3343
3344 gimple_opt_pass *
3345 make_pass_fold_builtins (gcc::context *ctxt)
3346 {
3347   return new pass_fold_builtins (ctxt);
3348 }
3349
3350 /* A simple pass that emits some warnings post IPA.  */
3351
3352 namespace {
3353
3354 const pass_data pass_data_post_ipa_warn =
3355 {
3356   GIMPLE_PASS, /* type */
3357   "post_ipa_warn", /* name */
3358   OPTGROUP_NONE, /* optinfo_flags */
3359   TV_NONE, /* tv_id */
3360   ( PROP_cfg | PROP_ssa ), /* properties_required */
3361   0, /* properties_provided */
3362   0, /* properties_destroyed */
3363   0, /* todo_flags_start */
3364   0, /* todo_flags_finish */
3365 };
3366
3367 class pass_post_ipa_warn : public gimple_opt_pass
3368 {
3369 public:
3370   pass_post_ipa_warn (gcc::context *ctxt)
3371     : gimple_opt_pass (pass_data_post_ipa_warn, ctxt)
3372   {}
3373
3374   /* opt_pass methods: */
3375   opt_pass * clone () { return new pass_post_ipa_warn (m_ctxt); }
3376   virtual bool gate (function *) { return warn_nonnull != 0; }
3377   virtual unsigned int execute (function *);
3378
3379 }; // class pass_fold_builtins
3380
3381 unsigned int
3382 pass_post_ipa_warn::execute (function *fun)
3383 {
3384   basic_block bb;
3385
3386   FOR_EACH_BB_FN (bb, fun)
3387     {
3388       gimple_stmt_iterator gsi;
3389       for (gsi = gsi_start_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
3390         {
3391           gimple *stmt = gsi_stmt (gsi);
3392           if (!is_gimple_call (stmt) || gimple_no_warning_p (stmt))
3393             continue;
3394
3395           if (warn_nonnull)
3396             {
3397               bitmap nonnullargs
3398                 = get_nonnull_args (gimple_call_fntype (stmt));
3399               if (nonnullargs)
3400                 {
3401                   for (unsigned i = 0; i < gimple_call_num_args (stmt); i++)
3402                     {
3403                       tree arg = gimple_call_arg (stmt, i);
3404                       if (TREE_CODE (TREE_TYPE (arg)) != POINTER_TYPE)
3405                         continue;
3406                       if (!integer_zerop (arg))
3407                         continue;
3408                       if (!bitmap_empty_p (nonnullargs)
3409                           && !bitmap_bit_p (nonnullargs, i))
3410                         continue;
3411
3412                       location_t loc = gimple_location (stmt);
3413                       if (warning_at (loc, OPT_Wnonnull,
3414                                       "argument %u null where non-null "
3415                                       "expected", i + 1))
3416                         {
3417                           tree fndecl = gimple_call_fndecl (stmt);
3418                           if (fndecl && DECL_IS_BUILTIN (fndecl))
3419                             inform (loc, "in a call to built-in function %qD",
3420                                     fndecl);
3421                           else if (fndecl)
3422                             inform (DECL_SOURCE_LOCATION (fndecl),
3423                                     "in a call to function %qD declared here",
3424                                     fndecl);
3425
3426                         }
3427                     }
3428                   BITMAP_FREE (nonnullargs);
3429                 }
3430             }
3431         }
3432     }
3433   return 0;
3434 }
3435
3436 } // anon namespace
3437
3438 gimple_opt_pass *
3439 make_pass_post_ipa_warn (gcc::context *ctxt)
3440 {
3441   return new pass_post_ipa_warn (ctxt);
3442 }