introduce --enable-large-address-aware

[official-gcc.git] / gcc / tree-vrp.c

/* Support routines for Value Range Propagation (VRP).
   Copyright (C) 2005-2018 Free Software Foundation, Inc.
   Contributed by Diego Novillo <dnovillo@redhat.com>.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3, or (at your option)
any later version.

GCC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING3.  If not see
<http://www.gnu.org/licenses/>.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "backend.h"
#include "insn-codes.h"
#include "rtl.h"
#include "tree.h"
#include "gimple.h"
#include "cfghooks.h"
#include "tree-pass.h"
#include "ssa.h"
#include "optabs-tree.h"
#include "gimple-pretty-print.h"
#include "diagnostic-core.h"
#include "flags.h"
#include "fold-const.h"
#include "stor-layout.h"
#include "calls.h"
#include "cfganal.h"
#include "gimple-fold.h"
#include "tree-eh.h"
#include "gimple-iterator.h"
#include "gimple-walk.h"
#include "tree-cfg.h"
#include "tree-dfa.h"
#include "tree-ssa-loop-manip.h"
#include "tree-ssa-loop-niter.h"
#include "tree-ssa-loop.h"
#include "tree-into-ssa.h"
#include "tree-ssa.h"
#include "intl.h"
#include "cfgloop.h"
#include "tree-scalar-evolution.h"
#include "tree-ssa-propagate.h"
#include "tree-chrec.h"
#include "tree-ssa-threadupdate.h"
#include "tree-ssa-scopedtables.h"
#include "tree-ssa-threadedge.h"
#include "omp-general.h"
#include "target.h"
#include "case-cfn-macros.h"
#include "params.h"
#include "alloc-pool.h"
#include "domwalk.h"
#include "tree-cfgcleanup.h"
#include "stringpool.h"
#include "attribs.h"
#include "vr-values.h"
#include "builtins.h"
#include "wide-int-range.h"

/* Set of SSA names found live during the RPO traversal of the function
   for still active basic-blocks.  */
static sbitmap *live;

/* Return true if the SSA name NAME is live on the edge E.  */

static bool
live_on_edge (edge e, tree name)
{
  return (live[e->dest->index]
          && bitmap_bit_p (live[e->dest->index], SSA_NAME_VERSION (name)));
}

/* Location information for ASSERT_EXPRs.  Each instance of this
   structure describes an ASSERT_EXPR for an SSA name.  Since a single
   SSA name may have more than one assertion associated with it, these
   locations are kept in a linked list attached to the corresponding
   SSA name.  */
struct assert_locus
{
  /* Basic block where the assertion would be inserted.  */
  basic_block bb;

  /* Some assertions need to be inserted on an edge (e.g., assertions
     generated by COND_EXPRs).  In those cases, BB will be NULL.  */
  edge e;

  /* Pointer to the statement that generated this assertion.  */
  gimple_stmt_iterator si;

  /* Predicate code for the ASSERT_EXPR.  Must be COMPARISON_CLASS_P.  */
  enum tree_code comp_code;

  /* Value being compared against.  */
  tree val;

  /* Expression to compare.  */
  tree expr;

  /* Next node in the linked list.  */
  assert_locus *next;
};

/* If bit I is present, it means that SSA name N_i has a list of
   assertions that should be inserted in the IL.  */
static bitmap need_assert_for;

/* Array of locations lists where to insert assertions.  ASSERTS_FOR[I]
   holds a list of ASSERT_LOCUS_T nodes that describe where
   ASSERT_EXPRs for SSA name N_I should be inserted.  */
static assert_locus **asserts_for;

/* Return the maximum value for TYPE.  */

tree
vrp_val_max (const_tree type)
{
  if (!INTEGRAL_TYPE_P (type))
    return NULL_TREE;

  return TYPE_MAX_VALUE (type);
}

/* Return the minimum value for TYPE.  */

tree
vrp_val_min (const_tree type)
{
  if (!INTEGRAL_TYPE_P (type))
    return NULL_TREE;

  return TYPE_MIN_VALUE (type);
}

/* Return whether VAL is equal to the maximum value of its type.
   We can't do a simple equality comparison with TYPE_MAX_VALUE because
   C typedefs and Ada subtypes can produce types whose TYPE_MAX_VALUE
   is not == to the integer constant with the same value in the type.  */

bool
vrp_val_is_max (const_tree val)
{
  tree type_max = vrp_val_max (TREE_TYPE (val));
  return (val == type_max
          || (type_max != NULL_TREE
              && operand_equal_p (val, type_max, 0)));
}

/* Return whether VAL is equal to the minimum value of its type.  */

bool
vrp_val_is_min (const_tree val)
{
  tree type_min = vrp_val_min (TREE_TYPE (val));
  return (val == type_min
          || (type_min != NULL_TREE
              && operand_equal_p (val, type_min, 0)));
}

/* VR_TYPE describes a range with mininum value *MIN and maximum
   value *MAX.  Restrict the range to the set of values that have
   no bits set outside NONZERO_BITS.  Update *MIN and *MAX and
   return the new range type.

   SGN gives the sign of the values described by the range.  */

enum value_range_type
intersect_range_with_nonzero_bits (enum value_range_type vr_type,
                                   wide_int *min, wide_int *max,
                                   const wide_int &nonzero_bits,
                                   signop sgn)
{
  if (vr_type == VR_ANTI_RANGE)
    {
      /* The VR_ANTI_RANGE is equivalent to the union of the ranges
         A: [-INF, *MIN) and B: (*MAX, +INF].  First use NONZERO_BITS
         to create an inclusive upper bound for A and an inclusive lower
         bound for B.  */
      wide_int a_max = wi::round_down_for_mask (*min - 1, nonzero_bits);
      wide_int b_min = wi::round_up_for_mask (*max + 1, nonzero_bits);

      /* If the calculation of A_MAX wrapped, A is effectively empty
         and A_MAX is the highest value that satisfies NONZERO_BITS.
         Likewise if the calculation of B_MIN wrapped, B is effectively
         empty and B_MIN is the lowest value that satisfies NONZERO_BITS.  */
      bool a_empty = wi::ge_p (a_max, *min, sgn);
      bool b_empty = wi::le_p (b_min, *max, sgn);

      /* If both A and B are empty, there are no valid values.  */
      if (a_empty && b_empty)
        return VR_UNDEFINED;

      /* If exactly one of A or B is empty, return a VR_RANGE for the
         other one.  */
      if (a_empty || b_empty)
        {
          *min = b_min;
          *max = a_max;
          gcc_checking_assert (wi::le_p (*min, *max, sgn));
          return VR_RANGE;
        }

      /* Update the VR_ANTI_RANGE bounds.  */
      *min = a_max + 1;
      *max = b_min - 1;
      gcc_checking_assert (wi::le_p (*min, *max, sgn));

      /* Now check whether the excluded range includes any values that
         satisfy NONZERO_BITS.  If not, switch to a full VR_RANGE.  */
      if (wi::round_up_for_mask (*min, nonzero_bits) == b_min)
        {
          unsigned int precision = min->get_precision ();
          *min = wi::min_value (precision, sgn);
          *max = wi::max_value (precision, sgn);
          vr_type = VR_RANGE;
        }
    }
  if (vr_type == VR_RANGE)
    {
      *max = wi::round_down_for_mask (*max, nonzero_bits);

      /* Check that the range contains at least one valid value.  */
      if (wi::gt_p (*min, *max, sgn))
        return VR_UNDEFINED;

      *min = wi::round_up_for_mask (*min, nonzero_bits);
      gcc_checking_assert (wi::le_p (*min, *max, sgn));
    }
  return vr_type;
}

/* Set value range VR to VR_UNDEFINED.  */

static inline void
set_value_range_to_undefined (value_range *vr)
{
  vr->type = VR_UNDEFINED;
  vr->min = vr->max = NULL_TREE;
  if (vr->equiv)
    bitmap_clear (vr->equiv);
}

/* Set value range VR to VR_VARYING.  */

void
set_value_range_to_varying (value_range *vr)
{
  vr->type = VR_VARYING;
  vr->min = vr->max = NULL_TREE;
  if (vr->equiv)
    bitmap_clear (vr->equiv);
}

/* Set value range VR to {T, MIN, MAX, EQUIV}.  */

void
set_value_range (value_range *vr, enum value_range_type t, tree min,
                 tree max, bitmap equiv)
{
  /* Check the validity of the range.  */
  if (flag_checking
      && (t == VR_RANGE || t == VR_ANTI_RANGE))
    {
      int cmp;

      gcc_assert (min && max);

      gcc_assert (!TREE_OVERFLOW_P (min) && !TREE_OVERFLOW_P (max));

      if (INTEGRAL_TYPE_P (TREE_TYPE (min)) && t == VR_ANTI_RANGE)
        gcc_assert (!vrp_val_is_min (min) || !vrp_val_is_max (max));

      cmp = compare_values (min, max);
      gcc_assert (cmp == 0 || cmp == -1 || cmp == -2);
    }

  if (flag_checking
      && (t == VR_UNDEFINED || t == VR_VARYING))
    {
      gcc_assert (min == NULL_TREE && max == NULL_TREE);
      gcc_assert (equiv == NULL || bitmap_empty_p (equiv));
    }

  vr->type = t;
  vr->min = min;
  vr->max = max;

  /* Since updating the equivalence set involves deep copying the
     bitmaps, only do it if absolutely necessary.

     All equivalence bitmaps are allocated from the same obstack.  So
     we can use the obstack associated with EQUIV to allocate vr->equiv.  */
  if (vr->equiv == NULL
      && equiv != NULL)
    vr->equiv = BITMAP_ALLOC (equiv->obstack);

  if (equiv != vr->equiv)
    {
      if (equiv && !bitmap_empty_p (equiv))
        bitmap_copy (vr->equiv, equiv);
      else
        bitmap_clear (vr->equiv);
    }
}


/* Set value range VR to the canonical form of {T, MIN, MAX, EQUIV}.
   This means adjusting T, MIN and MAX representing the case of a
   wrapping range with MAX < MIN covering [MIN, type_max] U [type_min, MAX]
   as anti-rage ~[MAX+1, MIN-1].  Likewise for wrapping anti-ranges.
   In corner cases where MAX+1 or MIN-1 wraps this will fall back
   to varying.
   This routine exists to ease canonicalization in the case where we
   extract ranges from var + CST op limit.  */

void
set_and_canonicalize_value_range (value_range *vr, enum value_range_type t,
                                  tree min, tree max, bitmap equiv)
{
  /* Use the canonical setters for VR_UNDEFINED and VR_VARYING.  */
  if (t == VR_UNDEFINED)
    {
      set_value_range_to_undefined (vr);
      return;
    }
  else if (t == VR_VARYING)
    {
      set_value_range_to_varying (vr);
      return;
    }

  /* Nothing to canonicalize for symbolic ranges.  */
  if (TREE_CODE (min) != INTEGER_CST
      || TREE_CODE (max) != INTEGER_CST)
    {
      set_value_range (vr, t, min, max, equiv);
      return;
    }

  /* Wrong order for min and max, to swap them and the VR type we need
     to adjust them.  */
  if (tree_int_cst_lt (max, min))
    {
      tree one, tmp;

      /* For one bit precision if max < min, then the swapped
         range covers all values, so for VR_RANGE it is varying and
         for VR_ANTI_RANGE empty range, so drop to varying as well.  */
      if (TYPE_PRECISION (TREE_TYPE (min)) == 1)
        {
          set_value_range_to_varying (vr);
          return;
        }

      one = build_int_cst (TREE_TYPE (min), 1);
      tmp = int_const_binop (PLUS_EXPR, max, one);
      max = int_const_binop (MINUS_EXPR, min, one);
      min = tmp;

      /* There's one corner case, if we had [C+1, C] before we now have
         that again.  But this represents an empty value range, so drop
         to varying in this case.  */
      if (tree_int_cst_lt (max, min))
        {
          set_value_range_to_varying (vr);
          return;
        }

      t = t == VR_RANGE ? VR_ANTI_RANGE : VR_RANGE;
    }

  /* Anti-ranges that can be represented as ranges should be so.  */
  if (t == VR_ANTI_RANGE)
    {
      /* For -fstrict-enums we may receive out-of-range ranges so consider
         values < -INF and values > INF as -INF/INF as well.  */
      tree type = TREE_TYPE (min);
      bool is_min = (INTEGRAL_TYPE_P (type)
                     && tree_int_cst_compare (min, TYPE_MIN_VALUE (type)) <= 0);
      bool is_max = (INTEGRAL_TYPE_P (type)
                     && tree_int_cst_compare (max, TYPE_MAX_VALUE (type)) >= 0);

      if (is_min && is_max)
        {
          /* We cannot deal with empty ranges, drop to varying.
             ???  This could be VR_UNDEFINED instead.  */
          set_value_range_to_varying (vr);
          return;
        }
      else if (TYPE_PRECISION (TREE_TYPE (min)) == 1
               && (is_min || is_max))
        {
          /* Non-empty boolean ranges can always be represented
             as a singleton range.  */
          if (is_min)
            min = max = vrp_val_max (TREE_TYPE (min));
          else
            min = max = vrp_val_min (TREE_TYPE (min));
          t = VR_RANGE;
        }
      else if (is_min
               /* As a special exception preserve non-null ranges.  */
               && !(TYPE_UNSIGNED (TREE_TYPE (min))
                    && integer_zerop (max)))
        {
          tree one = build_int_cst (TREE_TYPE (max), 1);
          min = int_const_binop (PLUS_EXPR, max, one);
          max = vrp_val_max (TREE_TYPE (max));
          t = VR_RANGE;
        }
      else if (is_max)
        {
          tree one = build_int_cst (TREE_TYPE (min), 1);
          max = int_const_binop (MINUS_EXPR, min, one);
          min = vrp_val_min (TREE_TYPE (min));
          t = VR_RANGE;
        }
    }

  /* Do not drop [-INF(OVF), +INF(OVF)] to varying.  (OVF) has to be sticky
     to make sure VRP iteration terminates, otherwise we can get into
     oscillations.  */

  set_value_range (vr, t, min, max, equiv);
}

/* Copy value range FROM into value range TO.  */

void
copy_value_range (value_range *to, const value_range *from)
{
  set_value_range (to, from->type, from->min, from->max, from->equiv);
}

/* Set value range VR to a single value.  This function is only called
   with values we get from statements, and exists to clear the
   TREE_OVERFLOW flag.  */

void
set_value_range_to_value (value_range *vr, tree val, bitmap equiv)
{
  gcc_assert (is_gimple_min_invariant (val));
  if (TREE_OVERFLOW_P (val))
    val = drop_tree_overflow (val);
  set_value_range (vr, VR_RANGE, val, val, equiv);
}

/* Set value range VR to a non-NULL range of type TYPE.  */

void
set_value_range_to_nonnull (value_range *vr, tree type)
{
  tree zero = build_int_cst (type, 0);
  set_value_range (vr, VR_ANTI_RANGE, zero, zero, vr->equiv);
}


/* Set value range VR to a NULL range of type TYPE.  */

void
set_value_range_to_null (value_range *vr, tree type)
{
  set_value_range_to_value (vr, build_int_cst (type, 0), vr->equiv);
}

/* Return true, if VAL1 and VAL2 are equal values for VRP purposes.  */

bool
vrp_operand_equal_p (const_tree val1, const_tree val2)
{
  if (val1 == val2)
    return true;
  if (!val1 || !val2 || !operand_equal_p (val1, val2, 0))
    return false;
  return true;
}

/* Return true, if the bitmaps B1 and B2 are equal.  */

bool
vrp_bitmap_equal_p (const_bitmap b1, const_bitmap b2)
{
  return (b1 == b2
          || ((!b1 || bitmap_empty_p (b1))
              && (!b2 || bitmap_empty_p (b2)))
          || (b1 && b2
              && bitmap_equal_p (b1, b2)));
}

/* Return true if VR is [0, 0].  */

static inline bool
range_is_null (const value_range *vr)
{
  return vr->type == VR_RANGE
         && integer_zerop (vr->min)
         && integer_zerop (vr->max);
}

/* Return true if max and min of VR are INTEGER_CST.  It's not necessary
   a singleton.  */

bool
range_int_cst_p (const value_range *vr)
{
  return (vr->type == VR_RANGE
          && TREE_CODE (vr->max) == INTEGER_CST
          && TREE_CODE (vr->min) == INTEGER_CST);
}

/* Return true if VR is a INTEGER_CST singleton.  */

bool
range_int_cst_singleton_p (const value_range *vr)
{
  return (range_int_cst_p (vr)
          && tree_int_cst_equal (vr->min, vr->max));
}

/* Return true if value range VR involves at least one symbol.  */

bool
symbolic_range_p (const value_range *vr)
{
  return (!is_gimple_min_invariant (vr->min)
          || !is_gimple_min_invariant (vr->max));
}

/* Return the single symbol (an SSA_NAME) contained in T if any, or NULL_TREE
   otherwise.  We only handle additive operations and set NEG to true if the
   symbol is negated and INV to the invariant part, if any.  */

tree
get_single_symbol (tree t, bool *neg, tree *inv)
{
  bool neg_;
  tree inv_;

  *inv = NULL_TREE;
  *neg = false;

  if (TREE_CODE (t) == PLUS_EXPR
      || TREE_CODE (t) == POINTER_PLUS_EXPR
      || TREE_CODE (t) == MINUS_EXPR)
    {
      if (is_gimple_min_invariant (TREE_OPERAND (t, 0)))
        {
          neg_ = (TREE_CODE (t) == MINUS_EXPR);
          inv_ = TREE_OPERAND (t, 0);
          t = TREE_OPERAND (t, 1);
        }
      else if (is_gimple_min_invariant (TREE_OPERAND (t, 1)))
        {
          neg_ = false;
          inv_ = TREE_OPERAND (t, 1);
          t = TREE_OPERAND (t, 0);
        }
      else
        return NULL_TREE;
    }
  else
    {
      neg_ = false;
      inv_ = NULL_TREE;
    }

  if (TREE_CODE (t) == NEGATE_EXPR)
    {
      t = TREE_OPERAND (t, 0);
      neg_ = !neg_;
    }

  if (TREE_CODE (t) != SSA_NAME)
    return NULL_TREE;

  if (inv_ && TREE_OVERFLOW_P (inv_))
    inv_ = drop_tree_overflow (inv_);

  *neg = neg_;
  *inv = inv_;
  return t;
}

/* The reverse operation: build a symbolic expression with TYPE
   from symbol SYM, negated according to NEG, and invariant INV.  */

static tree
build_symbolic_expr (tree type, tree sym, bool neg, tree inv)
{
  const bool pointer_p = POINTER_TYPE_P (type);
  tree t = sym;

  if (neg)
    t = build1 (NEGATE_EXPR, type, t);

  if (integer_zerop (inv))
    return t;

  return build2 (pointer_p ? POINTER_PLUS_EXPR : PLUS_EXPR, type, t, inv);
}

/* Return
   1 if VAL < VAL2
   0 if !(VAL < VAL2)
   -2 if those are incomparable.  */
int
operand_less_p (tree val, tree val2)
{
  /* LT is folded faster than GE and others.  Inline the common case.  */
  if (TREE_CODE (val) == INTEGER_CST && TREE_CODE (val2) == INTEGER_CST)
    return tree_int_cst_lt (val, val2);
  else
    {
      tree tcmp;

      fold_defer_overflow_warnings ();

      tcmp = fold_binary_to_constant (LT_EXPR, boolean_type_node, val, val2);

      fold_undefer_and_ignore_overflow_warnings ();

      if (!tcmp
          || TREE_CODE (tcmp) != INTEGER_CST)
        return -2;

      if (!integer_zerop (tcmp))
        return 1;
    }

  return 0;
}

/* Compare two values VAL1 and VAL2.  Return

        -2 if VAL1 and VAL2 cannot be compared at compile-time,
        -1 if VAL1 < VAL2,
         0 if VAL1 == VAL2,
        +1 if VAL1 > VAL2, and
        +2 if VAL1 != VAL2

   This is similar to tree_int_cst_compare but supports pointer values
   and values that cannot be compared at compile time.

   If STRICT_OVERFLOW_P is not NULL, then set *STRICT_OVERFLOW_P to
   true if the return value is only valid if we assume that signed
   overflow is undefined.  */

int
compare_values_warnv (tree val1, tree val2, bool *strict_overflow_p)
{
  if (val1 == val2)
    return 0;

  /* Below we rely on the fact that VAL1 and VAL2 are both pointers or
     both integers.  */
  gcc_assert (POINTER_TYPE_P (TREE_TYPE (val1))
              == POINTER_TYPE_P (TREE_TYPE (val2)));

  /* Convert the two values into the same type.  This is needed because
     sizetype causes sign extension even for unsigned types.  */
  val2 = fold_convert (TREE_TYPE (val1), val2);
  STRIP_USELESS_TYPE_CONVERSION (val2);

  const bool overflow_undefined
    = INTEGRAL_TYPE_P (TREE_TYPE (val1))
      && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (val1));
  tree inv1, inv2;
  bool neg1, neg2;
  tree sym1 = get_single_symbol (val1, &neg1, &inv1);
  tree sym2 = get_single_symbol (val2, &neg2, &inv2);

  /* If VAL1 and VAL2 are of the form '[-]NAME [+ CST]', return -1 or +1
     accordingly.  If VAL1 and VAL2 don't use the same name, return -2.  */
  if (sym1 && sym2)
    {
      /* Both values must use the same name with the same sign.  */
      if (sym1 != sym2 || neg1 != neg2)
        return -2;

      /* [-]NAME + CST == [-]NAME + CST.  */
      if (inv1 == inv2)
        return 0;

      /* If overflow is defined we cannot simplify more.  */
      if (!overflow_undefined)
        return -2;

      if (strict_overflow_p != NULL
          /* Symbolic range building sets TREE_NO_WARNING to declare
             that overflow doesn't happen.  */
          && (!inv1 || !TREE_NO_WARNING (val1))
          && (!inv2 || !TREE_NO_WARNING (val2)))
        *strict_overflow_p = true;

      if (!inv1)
        inv1 = build_int_cst (TREE_TYPE (val1), 0);
      if (!inv2)
        inv2 = build_int_cst (TREE_TYPE (val2), 0);

      return wi::cmp (wi::to_wide (inv1), wi::to_wide (inv2),
                      TYPE_SIGN (TREE_TYPE (val1)));
    }

  const bool cst1 = is_gimple_min_invariant (val1);
  const bool cst2 = is_gimple_min_invariant (val2);

  /* If one is of the form '[-]NAME + CST' and the other is constant, then
     it might be possible to say something depending on the constants.  */
  if ((sym1 && inv1 && cst2) || (sym2 && inv2 && cst1))
    {
      if (!overflow_undefined)
        return -2;

      if (strict_overflow_p != NULL
          /* Symbolic range building sets TREE_NO_WARNING to declare
             that overflow doesn't happen.  */
          && (!sym1 || !TREE_NO_WARNING (val1))
          && (!sym2 || !TREE_NO_WARNING (val2)))
        *strict_overflow_p = true;

      const signop sgn = TYPE_SIGN (TREE_TYPE (val1));
      tree cst = cst1 ? val1 : val2;
      tree inv = cst1 ? inv2 : inv1;

      /* Compute the difference between the constants.  If it overflows or
         underflows, this means that we can trivially compare the NAME with
         it and, consequently, the two values with each other.  */
      wide_int diff = wi::to_wide (cst) - wi::to_wide (inv);
      if (wi::cmp (0, wi::to_wide (inv), sgn)
          != wi::cmp (diff, wi::to_wide (cst), sgn))
        {
          const int res = wi::cmp (wi::to_wide (cst), wi::to_wide (inv), sgn);
          return cst1 ? res : -res;
        }

      return -2;
    }

  /* We cannot say anything more for non-constants.  */
  if (!cst1 || !cst2)
    return -2;

  if (!POINTER_TYPE_P (TREE_TYPE (val1)))
    {
      /* We cannot compare overflowed values.  */
      if (TREE_OVERFLOW (val1) || TREE_OVERFLOW (val2))
        return -2;

      if (TREE_CODE (val1) == INTEGER_CST
          && TREE_CODE (val2) == INTEGER_CST)
        return tree_int_cst_compare (val1, val2);

      if (poly_int_tree_p (val1) && poly_int_tree_p (val2))
        {
          if (known_eq (wi::to_poly_widest (val1),
                        wi::to_poly_widest (val2)))
            return 0;
          if (known_lt (wi::to_poly_widest (val1),
                        wi::to_poly_widest (val2)))
            return -1;
          if (known_gt (wi::to_poly_widest (val1),
                        wi::to_poly_widest (val2)))
            return 1;
        }

      return -2;
    }
  else
    {
      tree t;

      /* First see if VAL1 and VAL2 are not the same.  */
      if (val1 == val2 || operand_equal_p (val1, val2, 0))
        return 0;

      /* If VAL1 is a lower address than VAL2, return -1.  */
      if (operand_less_p (val1, val2) == 1)
        return -1;

      /* If VAL1 is a higher address than VAL2, return +1.  */
      if (operand_less_p (val2, val1) == 1)
        return 1;

      /* If VAL1 is different than VAL2, return +2.
         For integer constants we either have already returned -1 or 1
         or they are equivalent.  We still might succeed in proving
         something about non-trivial operands.  */
      if (TREE_CODE (val1) != INTEGER_CST
          || TREE_CODE (val2) != INTEGER_CST)
        {
          t = fold_binary_to_constant (NE_EXPR, boolean_type_node, val1, val2);
          if (t && integer_onep (t))
            return 2;
        }

      return -2;
    }
}

/* Compare values like compare_values_warnv.  */

int
compare_values (tree val1, tree val2)
{
  bool sop;
  return compare_values_warnv (val1, val2, &sop);
}


/* Return 1 if VAL is inside value range MIN <= VAL <= MAX,
          0 if VAL is not inside [MIN, MAX],
         -2 if we cannot tell either way.

   Benchmark compile/20001226-1.c compilation time after changing this
   function.  */

int
value_inside_range (tree val, tree min, tree max)
{
  int cmp1, cmp2;

  cmp1 = operand_less_p (val, min);
  if (cmp1 == -2)
    return -2;
  if (cmp1 == 1)
    return 0;

  cmp2 = operand_less_p (max, val);
  if (cmp2 == -2)
    return -2;

  return !cmp2;
}


/* Return TRUE if *VR includes the value zero.  */

bool
range_includes_zero_p (const value_range *vr)
{
  if (vr->type == VR_VARYING)
    return true;

  /* Ughh, we don't know.  We choose not to optimize.  */
  if (vr->type == VR_UNDEFINED)
    return true;

  tree zero = build_int_cst (TREE_TYPE (vr->min), 0);
  if (vr->type == VR_ANTI_RANGE)
    {
      int res = value_inside_range (zero, vr->min, vr->max);
      return res == 0 || res == -2;
    }
  return value_inside_range (zero, vr->min, vr->max) != 0;
}

/* If *VR has a value rante that is a single constant value return that,
   otherwise return NULL_TREE.  */

tree
value_range_constant_singleton (const value_range *vr)
{
  if (vr->type == VR_RANGE
      && vrp_operand_equal_p (vr->min, vr->max)
      && is_gimple_min_invariant (vr->min))
    return vr->min;

  return NULL_TREE;
}

/* Value range wrapper for wide_int_range_set_zero_nonzero_bits.

   Compute MAY_BE_NONZERO and MUST_BE_NONZERO bit masks for range in VR.

   Return TRUE if VR was a constant range and we were able to compute
   the bit masks.  */

bool
vrp_set_zero_nonzero_bits (const tree expr_type,
                           const value_range *vr,
                           wide_int *may_be_nonzero,
                           wide_int *must_be_nonzero)
{
  if (!range_int_cst_p (vr))
    {
      *may_be_nonzero = wi::minus_one (TYPE_PRECISION (expr_type));
      *must_be_nonzero = wi::zero (TYPE_PRECISION (expr_type));
      return false;
    }
  wide_int_range_set_zero_nonzero_bits (TYPE_SIGN (expr_type),
                                        wi::to_wide (vr->min),
                                        wi::to_wide (vr->max),
                                        *may_be_nonzero, *must_be_nonzero);
  return true;
}

/* Create two value-ranges in *VR0 and *VR1 from the anti-range *AR
   so that *VR0 U *VR1 == *AR.  Returns true if that is possible,
   false otherwise.  If *AR can be represented with a single range
   *VR1 will be VR_UNDEFINED.  */

static bool
ranges_from_anti_range (const value_range *ar,
                        value_range *vr0, value_range *vr1)
{
  tree type = TREE_TYPE (ar->min);

  vr0->type = VR_UNDEFINED;
  vr1->type = VR_UNDEFINED;

  /* As a future improvement, we could handle ~[0, A] as: [-INF, -1] U
     [A+1, +INF].  Not sure if this helps in practice, though.  */

  if (ar->type != VR_ANTI_RANGE
      || TREE_CODE (ar->min) != INTEGER_CST
      || TREE_CODE (ar->max) != INTEGER_CST
      || !vrp_val_min (type)
      || !vrp_val_max (type))
    return false;

  if (!vrp_val_is_min (ar->min))
    {
      vr0->type = VR_RANGE;
      vr0->min = vrp_val_min (type);
      vr0->max = wide_int_to_tree (type, wi::to_wide (ar->min) - 1);
    }
  if (!vrp_val_is_max (ar->max))
    {
      vr1->type = VR_RANGE;
      vr1->min = wide_int_to_tree (type, wi::to_wide (ar->max) + 1);
      vr1->max = vrp_val_max (type);
    }
  if (vr0->type == VR_UNDEFINED)
    {
      *vr0 = *vr1;
      vr1->type = VR_UNDEFINED;
    }

  return vr0->type != VR_UNDEFINED;
}

/* Extract the components of a value range into a pair of wide ints in
   [WMIN, WMAX].

   If the value range is anything but a VR_*RANGE of constants, the
   resulting wide ints are set to [-MIN, +MAX] for the type.  */

static void inline
extract_range_into_wide_ints (const value_range *vr,
                              signop sign, unsigned prec,
                              wide_int &wmin, wide_int &wmax)
{
  if ((vr->type == VR_RANGE
       || vr->type == VR_ANTI_RANGE)
      && TREE_CODE (vr->min) == INTEGER_CST
      && TREE_CODE (vr->max) == INTEGER_CST)
    {
      wmin = wi::to_wide (vr->min);
      wmax = wi::to_wide (vr->max);
    }
  else
    {
      wmin = wi::min_value (prec, sign);
      wmax = wi::max_value (prec, sign);
    }
}

/* Value range wrapper for wide_int_range_multiplicative_op:

     *VR = *VR0 .CODE. *VR1.  */

static void
extract_range_from_multiplicative_op (value_range *vr,
                                      enum tree_code code,
                                      const value_range *vr0,
                                      const value_range *vr1)
{
  gcc_assert (code == MULT_EXPR
              || code == TRUNC_DIV_EXPR
              || code == FLOOR_DIV_EXPR
              || code == CEIL_DIV_EXPR
              || code == EXACT_DIV_EXPR
              || code == ROUND_DIV_EXPR
              || code == RSHIFT_EXPR
              || code == LSHIFT_EXPR);
  gcc_assert (vr0->type == VR_RANGE && vr0->type == vr1->type);

  tree type = TREE_TYPE (vr0->min);
  wide_int res_lb, res_ub;
  wide_int vr0_lb = wi::to_wide (vr0->min);
  wide_int vr0_ub = wi::to_wide (vr0->max);
  wide_int vr1_lb = wi::to_wide (vr1->min);
  wide_int vr1_ub = wi::to_wide (vr1->max);
  bool overflow_undefined = TYPE_OVERFLOW_UNDEFINED (type);
  bool overflow_wraps = TYPE_OVERFLOW_WRAPS (type);
  unsigned prec = TYPE_PRECISION (type);

  if (wide_int_range_multiplicative_op (res_lb, res_ub,
                                         code, TYPE_SIGN (type), prec,
                                         vr0_lb, vr0_ub, vr1_lb, vr1_ub,
                                         overflow_undefined, overflow_wraps))
    set_and_canonicalize_value_range (vr, VR_RANGE,
                                      wide_int_to_tree (type, res_lb),
                                      wide_int_to_tree (type, res_ub), NULL);
  else
    set_value_range_to_varying (vr);
}

/* If BOUND will include a symbolic bound, adjust it accordingly,
   otherwise leave it as is.

   CODE is the original operation that combined the bounds (PLUS_EXPR
   or MINUS_EXPR).

   TYPE is the type of the original operation.

   SYM_OPn is the symbolic for OPn if it has a symbolic.

   NEG_OPn is TRUE if the OPn was negated.  */

static void
adjust_symbolic_bound (tree &bound, enum tree_code code, tree type,
                       tree sym_op0, tree sym_op1,
                       bool neg_op0, bool neg_op1)
{
  bool minus_p = (code == MINUS_EXPR);
  /* If the result bound is constant, we're done; otherwise, build the
     symbolic lower bound.  */
  if (sym_op0 == sym_op1)
    ;
  else if (sym_op0)
    bound = build_symbolic_expr (type, sym_op0,
                                 neg_op0, bound);
  else if (sym_op1)
    {
      /* We may not negate if that might introduce
         undefined overflow.  */
      if (!minus_p
          || neg_op1
          || TYPE_OVERFLOW_WRAPS (type))
        bound = build_symbolic_expr (type, sym_op1,
                                     neg_op1 ^ minus_p, bound);
      else
        bound = NULL_TREE;
    }
}

/* Combine OP1 and OP1, which are two parts of a bound, into one wide
   int bound according to CODE.  CODE is the operation combining the
   bound (either a PLUS_EXPR or a MINUS_EXPR).

   TYPE is the type of the combine operation.

   WI is the wide int to store the result.

   OVF is -1 if an underflow occurred, +1 if an overflow occurred or 0
   if over/underflow occurred.  */

static void
combine_bound (enum tree_code code, wide_int &wi, wi::overflow_type &ovf,
               tree type, tree op0, tree op1)
{
  bool minus_p = (code == MINUS_EXPR);
  const signop sgn = TYPE_SIGN (type);
  const unsigned int prec = TYPE_PRECISION (type);

  /* Combine the bounds, if any.  */
  if (op0 && op1)
    {
      if (minus_p)
        wi = wi::sub (wi::to_wide (op0), wi::to_wide (op1), sgn, &ovf);
      else
        wi = wi::add (wi::to_wide (op0), wi::to_wide (op1), sgn, &ovf);
    }
  else if (op0)
    wi = wi::to_wide (op0);
  else if (op1)
    {
      if (minus_p)
        wi = wi::neg (wi::to_wide (op1), &ovf);
      else
        wi = wi::to_wide (op1);
    }
  else
    wi = wi::shwi (0, prec);
}

/* Given a range in [WMIN, WMAX], adjust it for possible overflow and
   put the result in VR.

   TYPE is the type of the range.

   MIN_OVF and MAX_OVF indicate what type of overflow, if any,
   occurred while originally calculating WMIN or WMAX.  -1 indicates
   underflow.  +1 indicates overflow.  0 indicates neither.  */

static void
set_value_range_with_overflow (value_range &vr,
                               tree type,
                               const wide_int &wmin, const wide_int &wmax,
                               wi::overflow_type min_ovf,
                               wi::overflow_type max_ovf)
{
  const signop sgn = TYPE_SIGN (type);
  const unsigned int prec = TYPE_PRECISION (type);
  vr.type = VR_RANGE;
  vr.equiv = NULL;

  /* For one bit precision if max < min, then the swapped
     range covers all values.  */
  if (prec == 1 && wi::lt_p (wmax, wmin, sgn))
    {
      set_value_range_to_varying (&vr);
      return;
    }

  if (TYPE_OVERFLOW_WRAPS (type))
    {
      /* If overflow wraps, truncate the values and adjust the
         range kind and bounds appropriately.  */
      wide_int tmin = wide_int::from (wmin, prec, sgn);
      wide_int tmax = wide_int::from (wmax, prec, sgn);
      if ((min_ovf != wi::OVF_NONE) == (max_ovf != wi::OVF_NONE))
        {
          /* No overflow or both overflow or underflow.  The
             range kind stays VR_RANGE.  */
          vr.min = wide_int_to_tree (type, tmin);
          vr.max = wide_int_to_tree (type, tmax);
        }
      else if ((min_ovf == wi::OVF_UNDERFLOW && max_ovf == wi::OVF_NONE)
               || (max_ovf == wi::OVF_OVERFLOW && min_ovf == wi::OVF_NONE))
        {
          /* Min underflow or max overflow.  The range kind
             changes to VR_ANTI_RANGE.  */
          bool covers = false;
          wide_int tem = tmin;
          vr.type = VR_ANTI_RANGE;
          tmin = tmax + 1;
          if (wi::cmp (tmin, tmax, sgn) < 0)
            covers = true;
          tmax = tem - 1;
          if (wi::cmp (tmax, tem, sgn) > 0)
            covers = true;
          /* If the anti-range would cover nothing, drop to varying.
             Likewise if the anti-range bounds are outside of the
             types values.  */
          if (covers || wi::cmp (tmin, tmax, sgn) > 0)
            {
              set_value_range_to_varying (&vr);
              return;
            }
          vr.min = wide_int_to_tree (type, tmin);
          vr.max = wide_int_to_tree (type, tmax);
        }
      else
        {
          /* Other underflow and/or overflow, drop to VR_VARYING.  */
          set_value_range_to_varying (&vr);
          return;
        }
    }
  else
    {
      /* If overflow does not wrap, saturate to the types min/max
         value.  */
      wide_int type_min = wi::min_value (prec, sgn);
      wide_int type_max = wi::max_value (prec, sgn);
      if (min_ovf == wi::OVF_UNDERFLOW)
        vr.min = wide_int_to_tree (type, type_min);
      else if (min_ovf == wi::OVF_OVERFLOW)
        vr.min = wide_int_to_tree (type, type_max);
      else
        vr.min = wide_int_to_tree (type, wmin);

      if (max_ovf == wi::OVF_UNDERFLOW)
        vr.max = wide_int_to_tree (type, type_min);
      else if (max_ovf == wi::OVF_OVERFLOW)
        vr.max = wide_int_to_tree (type, type_max);
      else
        vr.max = wide_int_to_tree (type, wmax);
    }
}

/* Extract range information from a binary operation CODE based on
   the ranges of each of its operands *VR0 and *VR1 with resulting
   type EXPR_TYPE.  The resulting range is stored in *VR.  */

void
extract_range_from_binary_expr_1 (value_range *vr,
                                  enum tree_code code, tree expr_type,
                                  const value_range *vr0_,
                                  const value_range *vr1_)
{
  signop sign = TYPE_SIGN (expr_type);
  unsigned int prec = TYPE_PRECISION (expr_type);
  value_range vr0 = *vr0_, vr1 = *vr1_;
  value_range vrtem0 = VR_INITIALIZER, vrtem1 = VR_INITIALIZER;
  enum value_range_type type;
  tree min = NULL_TREE, max = NULL_TREE;
  int cmp;

  if (!INTEGRAL_TYPE_P (expr_type)
      && !POINTER_TYPE_P (expr_type))
    {
      set_value_range_to_varying (vr);
      return;
    }

  /* Not all binary expressions can be applied to ranges in a
     meaningful way.  Handle only arithmetic operations.  */
  if (code != PLUS_EXPR
      && code != MINUS_EXPR
      && code != POINTER_PLUS_EXPR
      && code != MULT_EXPR
      && code != TRUNC_DIV_EXPR
      && code != FLOOR_DIV_EXPR
      && code != CEIL_DIV_EXPR
      && code != EXACT_DIV_EXPR
      && code != ROUND_DIV_EXPR
      && code != TRUNC_MOD_EXPR
      && code != RSHIFT_EXPR
      && code != LSHIFT_EXPR
      && code != MIN_EXPR
      && code != MAX_EXPR
      && code != BIT_AND_EXPR
      && code != BIT_IOR_EXPR
      && code != BIT_XOR_EXPR)
    {
      set_value_range_to_varying (vr);
      return;
    }

  /* If both ranges are UNDEFINED, so is the result.  */
  if (vr0.type == VR_UNDEFINED && vr1.type == VR_UNDEFINED)
    {
      set_value_range_to_undefined (vr);
      return;
    }
  /* If one of the ranges is UNDEFINED drop it to VARYING for the following
     code.  At some point we may want to special-case operations that
     have UNDEFINED result for all or some value-ranges of the not UNDEFINED
     operand.  */
  else if (vr0.type == VR_UNDEFINED)
    set_value_range_to_varying (&vr0);
  else if (vr1.type == VR_UNDEFINED)
    set_value_range_to_varying (&vr1);

  /* We get imprecise results from ranges_from_anti_range when
     code is EXACT_DIV_EXPR.  We could mask out bits in the resulting
     range, but then we also need to hack up vrp_meet.  It's just
     easier to special case when vr0 is ~[0,0] for EXACT_DIV_EXPR.  */
  if (code == EXACT_DIV_EXPR
      && vr0.type == VR_ANTI_RANGE
      && vr0.min == vr0.max
      && integer_zerop (vr0.min))
    {
      set_value_range_to_nonnull (vr, expr_type);
      return;
    }

  /* Now canonicalize anti-ranges to ranges when they are not symbolic
     and express ~[] op X as ([]' op X) U ([]'' op X).  */
  if (vr0.type == VR_ANTI_RANGE
      && ranges_from_anti_range (&vr0, &vrtem0, &vrtem1))
    {
      extract_range_from_binary_expr_1 (vr, code, expr_type, &vrtem0, vr1_);
      if (vrtem1.type != VR_UNDEFINED)
        {
          value_range vrres = VR_INITIALIZER;
          extract_range_from_binary_expr_1 (&vrres, code, expr_type,
                                            &vrtem1, vr1_);
          vrp_meet (vr, &vrres);
        }
      return;
    }
  /* Likewise for X op ~[].  */
  if (vr1.type == VR_ANTI_RANGE
      && ranges_from_anti_range (&vr1, &vrtem0, &vrtem1))
    {
      extract_range_from_binary_expr_1 (vr, code, expr_type, vr0_, &vrtem0);
      if (vrtem1.type != VR_UNDEFINED)
        {
          value_range vrres = VR_INITIALIZER;
          extract_range_from_binary_expr_1 (&vrres, code, expr_type,
                                            vr0_, &vrtem1);
          vrp_meet (vr, &vrres);
        }
      return;
    }

  /* The type of the resulting value range defaults to VR0.TYPE.  */
  type = vr0.type;

  /* Refuse to operate on VARYING ranges, ranges of different kinds
     and symbolic ranges.  As an exception, we allow BIT_{AND,IOR}
     because we may be able to derive a useful range even if one of
     the operands is VR_VARYING or symbolic range.  Similarly for
     divisions, MIN/MAX and PLUS/MINUS.

     TODO, we may be able to derive anti-ranges in some cases.  */
  if (code != BIT_AND_EXPR
      && code != BIT_IOR_EXPR
      && code != TRUNC_DIV_EXPR
      && code != FLOOR_DIV_EXPR
      && code != CEIL_DIV_EXPR
      && code != EXACT_DIV_EXPR
      && code != ROUND_DIV_EXPR
      && code != TRUNC_MOD_EXPR
      && code != MIN_EXPR
      && code != MAX_EXPR
      && code != PLUS_EXPR
      && code != MINUS_EXPR
      && code != RSHIFT_EXPR
      && code != POINTER_PLUS_EXPR
      && (vr0.type == VR_VARYING
          || vr1.type == VR_VARYING
          || vr0.type != vr1.type
          || symbolic_range_p (&vr0)
          || symbolic_range_p (&vr1)))
    {
      set_value_range_to_varying (vr);
      return;
    }

  /* Now evaluate the expression to determine the new range.  */
  if (POINTER_TYPE_P (expr_type))
    {
      if (code == MIN_EXPR || code == MAX_EXPR)
        {
          /* For MIN/MAX expressions with pointers, we only care about
             nullness, if both are non null, then the result is nonnull.
             If both are null, then the result is null. Otherwise they
             are varying.  */
          if (!range_includes_zero_p (&vr0) && !range_includes_zero_p (&vr1))
            set_value_range_to_nonnull (vr, expr_type);
          else if (range_is_null (&vr0) && range_is_null (&vr1))
            set_value_range_to_null (vr, expr_type);
          else
            set_value_range_to_varying (vr);
        }
      else if (code == POINTER_PLUS_EXPR)
        {
          /* For pointer types, we are really only interested in asserting
             whether the expression evaluates to non-NULL.  */
          if (!range_includes_zero_p (&vr0)
              || !range_includes_zero_p (&vr1))
            set_value_range_to_nonnull (vr, expr_type);
          else if (range_is_null (&vr0) && range_is_null (&vr1))
            set_value_range_to_null (vr, expr_type);
          else
            set_value_range_to_varying (vr);
        }
      else if (code == BIT_AND_EXPR)
        {
          /* For pointer types, we are really only interested in asserting
             whether the expression evaluates to non-NULL.  */
          if (!range_includes_zero_p (&vr0) && !range_includes_zero_p (&vr1))
            set_value_range_to_nonnull (vr, expr_type);
          else if (range_is_null (&vr0) || range_is_null (&vr1))
            set_value_range_to_null (vr, expr_type);
          else
            set_value_range_to_varying (vr);
        }
      else
        set_value_range_to_varying (vr);

      return;
    }

  /* For integer ranges, apply the operation to each end of the
     range and see what we end up with.  */
  if (code == PLUS_EXPR || code == MINUS_EXPR)
    {
      /* This will normalize things such that calculating
         [0,0] - VR_VARYING is not dropped to varying, but is
         calculated as [MIN+1, MAX].  */
      if (vr0.type == VR_VARYING)
        {
          vr0.type = VR_RANGE;
          vr0.min = vrp_val_min (expr_type);
          vr0.max = vrp_val_max (expr_type);
        }
      if (vr1.type == VR_VARYING)
        {
          vr1.type = VR_RANGE;
          vr1.min = vrp_val_min (expr_type);
          vr1.max = vrp_val_max (expr_type);
        }

      const bool minus_p = (code == MINUS_EXPR);
      tree min_op0 = vr0.min;
      tree min_op1 = minus_p ? vr1.max : vr1.min;
      tree max_op0 = vr0.max;
      tree max_op1 = minus_p ? vr1.min : vr1.max;
      tree sym_min_op0 = NULL_TREE;
      tree sym_min_op1 = NULL_TREE;
      tree sym_max_op0 = NULL_TREE;
      tree sym_max_op1 = NULL_TREE;
      bool neg_min_op0, neg_min_op1, neg_max_op0, neg_max_op1;

      neg_min_op0 = neg_min_op1 = neg_max_op0 = neg_max_op1 = false;

      /* If we have a PLUS or MINUS with two VR_RANGEs, either constant or
         single-symbolic ranges, try to compute the precise resulting range,
         but only if we know that this resulting range will also be constant
         or single-symbolic.  */
      if (vr0.type == VR_RANGE && vr1.type == VR_RANGE
          && (TREE_CODE (min_op0) == INTEGER_CST
              || (sym_min_op0
                  = get_single_symbol (min_op0, &neg_min_op0, &min_op0)))
          && (TREE_CODE (min_op1) == INTEGER_CST
              || (sym_min_op1
                  = get_single_symbol (min_op1, &neg_min_op1, &min_op1)))
          && (!(sym_min_op0 && sym_min_op1)
              || (sym_min_op0 == sym_min_op1
                  && neg_min_op0 == (minus_p ? neg_min_op1 : !neg_min_op1)))
          && (TREE_CODE (max_op0) == INTEGER_CST
              || (sym_max_op0
                  = get_single_symbol (max_op0, &neg_max_op0, &max_op0)))
          && (TREE_CODE (max_op1) == INTEGER_CST
              || (sym_max_op1
                  = get_single_symbol (max_op1, &neg_max_op1, &max_op1)))
          && (!(sym_max_op0 && sym_max_op1)
              || (sym_max_op0 == sym_max_op1
                  && neg_max_op0 == (minus_p ? neg_max_op1 : !neg_max_op1))))
        {
          wide_int wmin, wmax;
          wi::overflow_type min_ovf = wi::OVF_NONE;
          wi::overflow_type max_ovf = wi::OVF_NONE;

          /* Build the bounds.  */
          combine_bound (code, wmin, min_ovf, expr_type, min_op0, min_op1);
          combine_bound (code, wmax, max_ovf, expr_type, max_op0, max_op1);

          /* If we have overflow for the constant part and the resulting
             range will be symbolic, drop to VR_VARYING.  */
          if (((bool)min_ovf && sym_min_op0 != sym_min_op1)
              || ((bool)max_ovf && sym_max_op0 != sym_max_op1))
            {
              set_value_range_to_varying (vr);
              return;
            }

          /* Adjust the range for possible overflow.  */
          set_value_range_with_overflow (*vr, expr_type,
                                         wmin, wmax, min_ovf, max_ovf);
          if (vr->type == VR_VARYING)
            return;

          /* Build the symbolic bounds if needed.  */
          adjust_symbolic_bound (vr->min, code, expr_type,
                                 sym_min_op0, sym_min_op1,
                                 neg_min_op0, neg_min_op1);
          adjust_symbolic_bound (vr->max, code, expr_type,
                                 sym_max_op0, sym_max_op1,
                                 neg_max_op0, neg_max_op1);
          /* ?? It would probably be cleaner to eliminate min/max/type
             entirely and hold these values in VR directly.  */
          min = vr->min;
          max = vr->max;
          type = vr->type;
        }
      else
        {
          /* For other cases, for example if we have a PLUS_EXPR with two
             VR_ANTI_RANGEs, drop to VR_VARYING.  It would take more effort
             to compute a precise range for such a case.
             ???  General even mixed range kind operations can be expressed
             by for example transforming ~[3, 5] + [1, 2] to range-only
             operations and a union primitive:
               [-INF, 2] + [1, 2]  U  [5, +INF] + [1, 2]
                   [-INF+1, 4]     U    [6, +INF(OVF)]
             though usually the union is not exactly representable with
             a single range or anti-range as the above is
                 [-INF+1, +INF(OVF)] intersected with ~[5, 5]
             but one could use a scheme similar to equivalences for this. */
          set_value_range_to_varying (vr);
          return;
        }
    }
  else if (code == MIN_EXPR
           || code == MAX_EXPR)
    {
      wide_int wmin, wmax;
      wide_int vr0_min, vr0_max;
      wide_int vr1_min, vr1_max;
      extract_range_into_wide_ints (&vr0, sign, prec, vr0_min, vr0_max);
      extract_range_into_wide_ints (&vr1, sign, prec, vr1_min, vr1_max);
      if (wide_int_range_min_max (wmin, wmax, code, sign, prec,
                                  vr0_min, vr0_max, vr1_min, vr1_max))
        set_value_range (vr, VR_RANGE,
                         wide_int_to_tree (expr_type, wmin),
                         wide_int_to_tree (expr_type, wmax), NULL);
      else
        set_value_range_to_varying (vr);
      return;
    }
  else if (code == MULT_EXPR)
    {
      if (!range_int_cst_p (&vr0)
          || !range_int_cst_p (&vr1))
        {
          set_value_range_to_varying (vr);
          return;
        }
      extract_range_from_multiplicative_op (vr, code, &vr0, &vr1);
      return;
    }
  else if (code == RSHIFT_EXPR
           || code == LSHIFT_EXPR)
    {
      if (range_int_cst_p (&vr1)
          && !wide_int_range_shift_undefined_p (prec,
                                                wi::to_wide (vr1.min),
                                                wi::to_wide (vr1.max)))
        {
          if (code == RSHIFT_EXPR)
            {
              /* Even if vr0 is VARYING or otherwise not usable, we can derive
                 useful ranges just from the shift count.  E.g.
                 x >> 63 for signed 64-bit x is always [-1, 0].  */
              if (vr0.type != VR_RANGE || symbolic_range_p (&vr0))
                {
                  vr0.type = type = VR_RANGE;
                  vr0.min = vrp_val_min (expr_type);
                  vr0.max = vrp_val_max (expr_type);
                }
              extract_range_from_multiplicative_op (vr, code, &vr0, &vr1);
              return;
            }
          else if (code == LSHIFT_EXPR
                   && range_int_cst_p (&vr0))
            {
              wide_int res_lb, res_ub;
              if (wide_int_range_lshift (res_lb, res_ub, sign, prec,
                                         wi::to_wide (vr0.min),
                                         wi::to_wide (vr0.max),
                                         wi::to_wide (vr1.min),
                                         wi::to_wide (vr1.max),
                                         TYPE_OVERFLOW_UNDEFINED (expr_type),
                                         TYPE_OVERFLOW_WRAPS (expr_type)))
                {
                  min = wide_int_to_tree (expr_type, res_lb);
                  max = wide_int_to_tree (expr_type, res_ub);
                  set_and_canonicalize_value_range (vr, VR_RANGE,
                                                    min, max, NULL);
                  return;
                }
            }
        }
      set_value_range_to_varying (vr);
      return;
    }
  else if (code == TRUNC_DIV_EXPR
           || code == FLOOR_DIV_EXPR
           || code == CEIL_DIV_EXPR
           || code == EXACT_DIV_EXPR
           || code == ROUND_DIV_EXPR)
    {
      wide_int dividend_min, dividend_max, divisor_min, divisor_max;
      wide_int wmin, wmax, extra_min, extra_max;
      bool extra_range_p;

      /* Special case explicit division by zero as undefined.  */
      if (range_is_null (&vr1))
        {
          set_value_range_to_undefined (vr);
          return;
        }

      /* First, normalize ranges into constants we can handle.  Note
         that VR_ANTI_RANGE's of constants were already normalized
         before arriving here.

         NOTE: As a future improvement, we may be able to do better
         with mixed symbolic (anti-)ranges like [0, A].  See note in
         ranges_from_anti_range.  */
      extract_range_into_wide_ints (&vr0, sign, prec,
                                    dividend_min, dividend_max);
      extract_range_into_wide_ints (&vr1, sign, prec,
                                    divisor_min, divisor_max);
      if (!wide_int_range_div (wmin, wmax, code, sign, prec,
                               dividend_min, dividend_max,
                               divisor_min, divisor_max,
                               TYPE_OVERFLOW_UNDEFINED (expr_type),
                               TYPE_OVERFLOW_WRAPS (expr_type),
                               extra_range_p, extra_min, extra_max))
        {
          set_value_range_to_varying (vr);
          return;
        }
      set_value_range (vr, VR_RANGE,
                       wide_int_to_tree (expr_type, wmin),
                       wide_int_to_tree (expr_type, wmax), NULL);
      if (extra_range_p)
        {
          value_range extra_range = VR_INITIALIZER;
          set_value_range (&extra_range, VR_RANGE,
                           wide_int_to_tree (expr_type, extra_min),
                           wide_int_to_tree (expr_type, extra_max), NULL);
          vrp_meet (vr, &extra_range);
        }
      return;
    }
  else if (code == TRUNC_MOD_EXPR)
    {
      if (range_is_null (&vr1))
        {
          set_value_range_to_undefined (vr);
          return;
        }
      wide_int wmin, wmax, tmp;
      wide_int vr0_min, vr0_max, vr1_min, vr1_max;
      extract_range_into_wide_ints (&vr0, sign, prec, vr0_min, vr0_max);
      extract_range_into_wide_ints (&vr1, sign, prec, vr1_min, vr1_max);
      wide_int_range_trunc_mod (wmin, wmax, sign, prec,
                                vr0_min, vr0_max, vr1_min, vr1_max);
      min = wide_int_to_tree (expr_type, wmin);
      max = wide_int_to_tree (expr_type, wmax);
      set_value_range (vr, VR_RANGE, min, max, NULL);
      return;
    }
  else if (code == BIT_AND_EXPR || code == BIT_IOR_EXPR || code == BIT_XOR_EXPR)
    {
      wide_int may_be_nonzero0, may_be_nonzero1;
      wide_int must_be_nonzero0, must_be_nonzero1;
      wide_int wmin, wmax;
      wide_int vr0_min, vr0_max, vr1_min, vr1_max;
      vrp_set_zero_nonzero_bits (expr_type, &vr0,
                                 &may_be_nonzero0, &must_be_nonzero0);
      vrp_set_zero_nonzero_bits (expr_type, &vr1,
                                 &may_be_nonzero1, &must_be_nonzero1);
      extract_range_into_wide_ints (&vr0, sign, prec, vr0_min, vr0_max);
      extract_range_into_wide_ints (&vr1, sign, prec, vr1_min, vr1_max);
      if (code == BIT_AND_EXPR)
        {
          if (wide_int_range_bit_and (wmin, wmax, sign, prec,
                                      vr0_min, vr0_max,
                                      vr1_min, vr1_max,
                                      must_be_nonzero0,
                                      may_be_nonzero0,
                                      must_be_nonzero1,
                                      may_be_nonzero1))
            {
              min = wide_int_to_tree (expr_type, wmin);
              max = wide_int_to_tree (expr_type, wmax);
              set_value_range (vr, VR_RANGE, min, max, NULL);
            }
          else
            set_value_range_to_varying (vr);
          return;
        }
      else if (code == BIT_IOR_EXPR)
        {
          if (wide_int_range_bit_ior (wmin, wmax, sign,
                                      vr0_min, vr0_max,
                                      vr1_min, vr1_max,
                                      must_be_nonzero0,
                                      may_be_nonzero0,
                                      must_be_nonzero1,
                                      may_be_nonzero1))
            {
              min = wide_int_to_tree (expr_type, wmin);
              max = wide_int_to_tree (expr_type, wmax);
              set_value_range (vr, VR_RANGE, min, max, NULL);
            }
          else
            set_value_range_to_varying (vr);
          return;
        }
      else if (code == BIT_XOR_EXPR)
        {
          if (wide_int_range_bit_xor (wmin, wmax, sign, prec,
                                      must_be_nonzero0,
                                      may_be_nonzero0,
                                      must_be_nonzero1,
                                      may_be_nonzero1))
            {
              min = wide_int_to_tree (expr_type, wmin);
              max = wide_int_to_tree (expr_type, wmax);
              set_value_range (vr, VR_RANGE, min, max, NULL);
            }
          else
            set_value_range_to_varying (vr);
          return;
        }
    }
  else
    gcc_unreachable ();

  /* If either MIN or MAX overflowed, then set the resulting range to
     VARYING.  */
  if (min == NULL_TREE
      || TREE_OVERFLOW_P (min)
      || max == NULL_TREE
      || TREE_OVERFLOW_P (max))
    {
      set_value_range_to_varying (vr);
      return;
    }

  /* We punt for [-INF, +INF].
     We learn nothing when we have INF on both sides.
     Note that we do accept [-INF, -INF] and [+INF, +INF].  */
  if (vrp_val_is_min (min) && vrp_val_is_max (max))
    {
      set_value_range_to_varying (vr);
      return;
    }

  cmp = compare_values (min, max);
  if (cmp == -2 || cmp == 1)
    {
      /* If the new range has its limits swapped around (MIN > MAX),
         then the operation caused one of them to wrap around, mark
         the new range VARYING.  */
      set_value_range_to_varying (vr);
    }
  else
    set_value_range (vr, type, min, max, NULL);
}

/* Extract range information from a unary operation CODE based on
   the range of its operand *VR0 with type OP0_TYPE with resulting type TYPE.
   The resulting range is stored in *VR.  */

void
extract_range_from_unary_expr (value_range *vr,
                               enum tree_code code, tree type,
                               const value_range *vr0_, tree op0_type)
{
  signop sign = TYPE_SIGN (type);
  unsigned int prec = TYPE_PRECISION (type);
  value_range vr0 = *vr0_, vrtem0 = VR_INITIALIZER, vrtem1 = VR_INITIALIZER;

  /* VRP only operates on integral and pointer types.  */
  if (!(INTEGRAL_TYPE_P (op0_type)
        || POINTER_TYPE_P (op0_type))
      || !(INTEGRAL_TYPE_P (type)
           || POINTER_TYPE_P (type)))
    {
      set_value_range_to_varying (vr);
      return;
    }

  /* If VR0 is UNDEFINED, so is the result.  */
  if (vr0.type == VR_UNDEFINED)
    {
      set_value_range_to_undefined (vr);
      return;
    }

  /* Handle operations that we express in terms of others.  */
  if (code == PAREN_EXPR || code == OBJ_TYPE_REF)
    {
      /* PAREN_EXPR and OBJ_TYPE_REF are simple copies.  */
      copy_value_range (vr, &vr0);
      return;
    }
  else if (code == NEGATE_EXPR)
    {
      /* -X is simply 0 - X, so re-use existing code that also handles
         anti-ranges fine.  */
      value_range zero = VR_INITIALIZER;
      set_value_range_to_value (&zero, build_int_cst (type, 0), NULL);
      extract_range_from_binary_expr_1 (vr, MINUS_EXPR, type, &zero, &vr0);
      return;
    }
  else if (code == BIT_NOT_EXPR)
    {
      /* ~X is simply -1 - X, so re-use existing code that also handles
         anti-ranges fine.  */
      value_range minusone = VR_INITIALIZER;
      set_value_range_to_value (&minusone, build_int_cst (type, -1), NULL);
      extract_range_from_binary_expr_1 (vr, MINUS_EXPR,
                                        type, &minusone, &vr0);
      return;
    }

  /* Now canonicalize anti-ranges to ranges when they are not symbolic
     and express op ~[]  as (op []') U (op []'').  */
  if (vr0.type == VR_ANTI_RANGE
      && ranges_from_anti_range (&vr0, &vrtem0, &vrtem1))
    {
      extract_range_from_unary_expr (vr, code, type, &vrtem0, op0_type);
      if (vrtem1.type != VR_UNDEFINED)
        {
          value_range vrres = VR_INITIALIZER;
          extract_range_from_unary_expr (&vrres, code, type,
                                         &vrtem1, op0_type);
          vrp_meet (vr, &vrres);
        }
      return;
    }

  if (CONVERT_EXPR_CODE_P (code))
    {
      tree inner_type = op0_type;
      tree outer_type = type;

      /* If the expression involves a pointer, we are only interested in
         determining if it evaluates to NULL [0, 0] or non-NULL (~[0, 0]).

         This may lose precision when converting (char *)~[0,2] to
         int, because we'll forget that the pointer can also not be 1
         or 2.  In practice we don't care, as this is some idiot
         storing a magic constant to a pointer.  */
      if (POINTER_TYPE_P (type) || POINTER_TYPE_P (op0_type))
        {
          if (!range_includes_zero_p (&vr0))
            set_value_range_to_nonnull (vr, type);
          else if (range_is_null (&vr0))
            set_value_range_to_null (vr, type);
          else
            set_value_range_to_varying (vr);
          return;
        }

      /* The POINTER_TYPE_P code above will have dealt with all
         pointer anti-ranges.  Any remaining anti-ranges at this point
         will be integer conversions from SSA names that will be
         normalized into VARYING.  For instance: ~[x_55, x_55].  */
      gcc_assert (vr0.type != VR_ANTI_RANGE
                  || TREE_CODE (vr0.min) != INTEGER_CST);

      /* NOTES: Previously we were returning VARYING for all symbolics, but
         we can do better by treating them as [-MIN, +MAX].  For
         example, converting [SYM, SYM] from INT to LONG UNSIGNED,
         we can return: ~[0x8000000, 0xffffffff7fffffff].

         We were also failing to convert ~[0,0] from char* to unsigned,
         instead choosing to return VR_VARYING.  Now we return ~[0,0].  */
      wide_int vr0_min, vr0_max, wmin, wmax;
      signop inner_sign = TYPE_SIGN (inner_type);
      signop outer_sign = TYPE_SIGN (outer_type);
      unsigned inner_prec = TYPE_PRECISION (inner_type);
      unsigned outer_prec = TYPE_PRECISION (outer_type);
      extract_range_into_wide_ints (&vr0, inner_sign, inner_prec,
                                    vr0_min, vr0_max);
      if (wide_int_range_convert (wmin, wmax,
                                  inner_sign, inner_prec,
                                  outer_sign, outer_prec,
                                  vr0_min, vr0_max))
        {
          tree min = wide_int_to_tree (outer_type, wmin);
          tree max = wide_int_to_tree (outer_type, wmax);
          set_and_canonicalize_value_range (vr, VR_RANGE, min, max, NULL);
        }
      else
        set_value_range_to_varying (vr);
      return;
    }
  else if (code == ABS_EXPR)
    {
      wide_int wmin, wmax;
      wide_int vr0_min, vr0_max;
      extract_range_into_wide_ints (&vr0, sign, prec, vr0_min, vr0_max);
      if (wide_int_range_abs (wmin, wmax, sign, prec, vr0_min, vr0_max,
                              TYPE_OVERFLOW_UNDEFINED (type)))
        set_value_range (vr, VR_RANGE,
                         wide_int_to_tree (type, wmin),
                         wide_int_to_tree (type, wmax), NULL);
      else
        set_value_range_to_varying (vr);
      return;
    }

  /* For unhandled operations fall back to varying.  */
  set_value_range_to_varying (vr);
  return;
}

/* Debugging dumps.  */

void dump_value_range (FILE *, const value_range *);
void debug_value_range (const value_range *);
void dump_all_value_ranges (FILE *);
void dump_vr_equiv (FILE *, bitmap);
void debug_vr_equiv (bitmap);


/* Dump value range VR to FILE.  */

void
dump_value_range (FILE *file, const value_range *vr)
{
  if (vr == NULL)
    fprintf (file, "[]");
  else if (vr->type == VR_UNDEFINED)
    fprintf (file, "UNDEFINED");
  else if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
    {
      tree type = TREE_TYPE (vr->min);

      fprintf (file, "%s[", (vr->type == VR_ANTI_RANGE) ? "~" : "");

      if (INTEGRAL_TYPE_P (type)
          && !TYPE_UNSIGNED (type)
          && vrp_val_is_min (vr->min))
        fprintf (file, "-INF");
      else
        print_generic_expr (file, vr->min);

      fprintf (file, ", ");

      if (INTEGRAL_TYPE_P (type)
          && vrp_val_is_max (vr->max))
        fprintf (file, "+INF");
      else
        print_generic_expr (file, vr->max);

      fprintf (file, "]");

      if (vr->equiv)
        {
          bitmap_iterator bi;
          unsigned i, c = 0;

          fprintf (file, "  EQUIVALENCES: { ");

          EXECUTE_IF_SET_IN_BITMAP (vr->equiv, 0, i, bi)
            {
              print_generic_expr (file, ssa_name (i));
              fprintf (file, " ");
              c++;
            }

          fprintf (file, "} (%u elements)", c);
        }
    }
  else if (vr->type == VR_VARYING)
    fprintf (file, "VARYING");
  else
    fprintf (file, "INVALID RANGE");
}


/* Dump value range VR to stderr.  */

DEBUG_FUNCTION void
debug_value_range (const value_range *vr)
{
  dump_value_range (stderr, vr);
  fprintf (stderr, "\n");
}

void
value_range::dump () const
{
  debug_value_range (this);
}


/* Given a COND_EXPR COND of the form 'V OP W', and an SSA name V,
   create a new SSA name N and return the assertion assignment
   'N = ASSERT_EXPR <V, V OP W>'.  */

static gimple *
build_assert_expr_for (tree cond, tree v)
{
  tree a;
  gassign *assertion;

  gcc_assert (TREE_CODE (v) == SSA_NAME
              && COMPARISON_CLASS_P (cond));

  a = build2 (ASSERT_EXPR, TREE_TYPE (v), v, cond);
  assertion = gimple_build_assign (NULL_TREE, a);

  /* The new ASSERT_EXPR, creates a new SSA name that replaces the
     operand of the ASSERT_EXPR.  Create it so the new name and the old one
     are registered in the replacement table so that we can fix the SSA web
     after adding all the ASSERT_EXPRs.  */
  tree new_def = create_new_def_for (v, assertion, NULL);
  /* Make sure we preserve abnormalness throughout an ASSERT_EXPR chain
     given we have to be able to fully propagate those out to re-create
     valid SSA when removing the asserts.  */
  if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (v))
    SSA_NAME_OCCURS_IN_ABNORMAL_PHI (new_def) = 1;

  return assertion;
}


/* Return false if EXPR is a predicate expression involving floating
   point values.  */

static inline bool
fp_predicate (gimple *stmt)
{
  GIMPLE_CHECK (stmt, GIMPLE_COND);

  return FLOAT_TYPE_P (TREE_TYPE (gimple_cond_lhs (stmt)));
}

/* If the range of values taken by OP can be inferred after STMT executes,
   return the comparison code (COMP_CODE_P) and value (VAL_P) that
   describes the inferred range.  Return true if a range could be
   inferred.  */

bool
infer_value_range (gimple *stmt, tree op, tree_code *comp_code_p, tree *val_p)
{
  *val_p = NULL_TREE;
  *comp_code_p = ERROR_MARK;

  /* Do not attempt to infer anything in names that flow through
     abnormal edges.  */
  if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (op))
    return false;

  /* If STMT is the last statement of a basic block with no normal
     successors, there is no point inferring anything about any of its
     operands.  We would not be able to find a proper insertion point
     for the assertion, anyway.  */
  if (stmt_ends_bb_p (stmt))
    {
      edge_iterator ei;
      edge e;

      FOR_EACH_EDGE (e, ei, gimple_bb (stmt)->succs)
        if (!(e->flags & (EDGE_ABNORMAL|EDGE_EH)))
          break;
      if (e == NULL)
        return false;
    }

  if (infer_nonnull_range (stmt, op))
    {
      *val_p = build_int_cst (TREE_TYPE (op), 0);
      *comp_code_p = NE_EXPR;
      return true;
    }

  return false;
}


void dump_asserts_for (FILE *, tree);
void debug_asserts_for (tree);
void dump_all_asserts (FILE *);
void debug_all_asserts (void);

/* Dump all the registered assertions for NAME to FILE.  */

void
dump_asserts_for (FILE *file, tree name)
{
  assert_locus *loc;

  fprintf (file, "Assertions to be inserted for ");
  print_generic_expr (file, name);
  fprintf (file, "\n");

  loc = asserts_for[SSA_NAME_VERSION (name)];
  while (loc)
    {
      fprintf (file, "\t");
      print_gimple_stmt (file, gsi_stmt (loc->si), 0);
      fprintf (file, "\n\tBB #%d", loc->bb->index);
      if (loc->e)
        {
          fprintf (file, "\n\tEDGE %d->%d", loc->e->src->index,
                   loc->e->dest->index);
          dump_edge_info (file, loc->e, dump_flags, 0);
        }
      fprintf (file, "\n\tPREDICATE: ");
      print_generic_expr (file, loc->expr);
      fprintf (file, " %s ", get_tree_code_name (loc->comp_code));
      print_generic_expr (file, loc->val);
      fprintf (file, "\n\n");
      loc = loc->next;
    }

  fprintf (file, "\n");
}


/* Dump all the registered assertions for NAME to stderr.  */

DEBUG_FUNCTION void
debug_asserts_for (tree name)
{
  dump_asserts_for (stderr, name);
}


/* Dump all the registered assertions for all the names to FILE.  */

void
dump_all_asserts (FILE *file)
{
  unsigned i;
  bitmap_iterator bi;

  fprintf (file, "\nASSERT_EXPRs to be inserted\n\n");
  EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
    dump_asserts_for (file, ssa_name (i));
  fprintf (file, "\n");
}


/* Dump all the registered assertions for all the names to stderr.  */

DEBUG_FUNCTION void
debug_all_asserts (void)
{
  dump_all_asserts (stderr);
}

/* Push the assert info for NAME, EXPR, COMP_CODE and VAL to ASSERTS.  */

static void
add_assert_info (vec<assert_info> &asserts,
                 tree name, tree expr, enum tree_code comp_code, tree val)
{
  assert_info info;
  info.comp_code = comp_code;
  info.name = name;
  if (TREE_OVERFLOW_P (val))
    val = drop_tree_overflow (val);
  info.val = val;
  info.expr = expr;
  asserts.safe_push (info);
}

/* If NAME doesn't have an ASSERT_EXPR registered for asserting
   'EXPR COMP_CODE VAL' at a location that dominates block BB or
   E->DEST, then register this location as a possible insertion point
   for ASSERT_EXPR <NAME, EXPR COMP_CODE VAL>.

   BB, E and SI provide the exact insertion point for the new
   ASSERT_EXPR.  If BB is NULL, then the ASSERT_EXPR is to be inserted
   on edge E.  Otherwise, if E is NULL, the ASSERT_EXPR is inserted on
   BB.  If SI points to a COND_EXPR or a SWITCH_EXPR statement, then E
   must not be NULL.  */

static void
register_new_assert_for (tree name, tree expr,
                         enum tree_code comp_code,
                         tree val,
                         basic_block bb,
                         edge e,
                         gimple_stmt_iterator si)
{
  assert_locus *n, *loc, *last_loc;
  basic_block dest_bb;

  gcc_checking_assert (bb == NULL || e == NULL);

  if (e == NULL)
    gcc_checking_assert (gimple_code (gsi_stmt (si)) != GIMPLE_COND
                         && gimple_code (gsi_stmt (si)) != GIMPLE_SWITCH);

  /* Never build an assert comparing against an integer constant with
     TREE_OVERFLOW set.  This confuses our undefined overflow warning
     machinery.  */
  if (TREE_OVERFLOW_P (val))
    val = drop_tree_overflow (val);

  /* The new assertion A will be inserted at BB or E.  We need to
     determine if the new location is dominated by a previously
     registered location for A.  If we are doing an edge insertion,
     assume that A will be inserted at E->DEST.  Note that this is not
     necessarily true.

     If E is a critical edge, it will be split.  But even if E is
     split, the new block will dominate the same set of blocks that
     E->DEST dominates.

     The reverse, however, is not true, blocks dominated by E->DEST
     will not be dominated by the new block created to split E.  So,
     if the insertion location is on a critical edge, we will not use
     the new location to move another assertion previously registered
     at a block dominated by E->DEST.  */
  dest_bb = (bb) ? bb : e->dest;

  /* If NAME already has an ASSERT_EXPR registered for COMP_CODE and
     VAL at a block dominating DEST_BB, then we don't need to insert a new
     one.  Similarly, if the same assertion already exists at a block
     dominated by DEST_BB and the new location is not on a critical
     edge, then update the existing location for the assertion (i.e.,
     move the assertion up in the dominance tree).

     Note, this is implemented as a simple linked list because there
     should not be more than a handful of assertions registered per
     name.  If this becomes a performance problem, a table hashed by
     COMP_CODE and VAL could be implemented.  */
  loc = asserts_for[SSA_NAME_VERSION (name)];
  last_loc = loc;
  while (loc)
    {
      if (loc->comp_code == comp_code
          && (loc->val == val
              || operand_equal_p (loc->val, val, 0))
          && (loc->expr == expr
              || operand_equal_p (loc->expr, expr, 0)))
        {
          /* If E is not a critical edge and DEST_BB
             dominates the existing location for the assertion, move
             the assertion up in the dominance tree by updating its
             location information.  */
          if ((e == NULL || !EDGE_CRITICAL_P (e))
              && dominated_by_p (CDI_DOMINATORS, loc->bb, dest_bb))
            {
              loc->bb = dest_bb;
              loc->e = e;
              loc->si = si;
              return;
            }
        }

      /* Update the last node of the list and move to the next one.  */
      last_loc = loc;
      loc = loc->next;
    }

  /* If we didn't find an assertion already registered for
     NAME COMP_CODE VAL, add a new one at the end of the list of
     assertions associated with NAME.  */
  n = XNEW (struct assert_locus);
  n->bb = dest_bb;
  n->e = e;
  n->si = si;
  n->comp_code = comp_code;
  n->val = val;
  n->expr = expr;
  n->next = NULL;

  if (last_loc)
    last_loc->next = n;
  else
    asserts_for[SSA_NAME_VERSION (name)] = n;

  bitmap_set_bit (need_assert_for, SSA_NAME_VERSION (name));
}

/* (COND_OP0 COND_CODE COND_OP1) is a predicate which uses NAME.
   Extract a suitable test code and value and store them into *CODE_P and
   *VAL_P so the predicate is normalized to NAME *CODE_P *VAL_P.

   If no extraction was possible, return FALSE, otherwise return TRUE.

   If INVERT is true, then we invert the result stored into *CODE_P.  */

static bool
extract_code_and_val_from_cond_with_ops (tree name, enum tree_code cond_code,
                                         tree cond_op0, tree cond_op1,
                                         bool invert, enum tree_code *code_p,
                                         tree *val_p)
{
  enum tree_code comp_code;
  tree val;

  /* Otherwise, we have a comparison of the form NAME COMP VAL
     or VAL COMP NAME.  */
  if (name == cond_op1)
    {
      /* If the predicate is of the form VAL COMP NAME, flip
         COMP around because we need to register NAME as the
         first operand in the predicate.  */
      comp_code = swap_tree_comparison (cond_code);
      val = cond_op0;
    }
  else if (name == cond_op0)
    {
      /* The comparison is of the form NAME COMP VAL, so the
         comparison code remains unchanged.  */
      comp_code = cond_code;
      val = cond_op1;
    }
  else
    gcc_unreachable ();

  /* Invert the comparison code as necessary.  */
  if (invert)
    comp_code = invert_tree_comparison (comp_code, 0);

  /* VRP only handles integral and pointer types.  */
  if (! INTEGRAL_TYPE_P (TREE_TYPE (val))
      && ! POINTER_TYPE_P (TREE_TYPE (val)))
    return false;

  /* Do not register always-false predicates.
     FIXME:  this works around a limitation in fold() when dealing with
     enumerations.  Given 'enum { N1, N2 } x;', fold will not
     fold 'if (x > N2)' to 'if (0)'.  */
  if ((comp_code == GT_EXPR || comp_code == LT_EXPR)
      && INTEGRAL_TYPE_P (TREE_TYPE (val)))
    {
      tree min = TYPE_MIN_VALUE (TREE_TYPE (val));
      tree max = TYPE_MAX_VALUE (TREE_TYPE (val));

      if (comp_code == GT_EXPR
          && (!max
              || compare_values (val, max) == 0))
        return false;

      if (comp_code == LT_EXPR
          && (!min
              || compare_values (val, min) == 0))
        return false;
    }
  *code_p = comp_code;
  *val_p = val;
  return true;
}

/* Find out smallest RES where RES > VAL && (RES & MASK) == RES, if any
   (otherwise return VAL).  VAL and MASK must be zero-extended for
   precision PREC.  If SGNBIT is non-zero, first xor VAL with SGNBIT
   (to transform signed values into unsigned) and at the end xor
   SGNBIT back.  */

static wide_int
masked_increment (const wide_int &val_in, const wide_int &mask,
                  const wide_int &sgnbit, unsigned int prec)
{
  wide_int bit = wi::one (prec), res;
  unsigned int i;

  wide_int val = val_in ^ sgnbit;
  for (i = 0; i < prec; i++, bit += bit)
    {
      res = mask;
      if ((res & bit) == 0)
        continue;
      res = bit - 1;
      res = wi::bit_and_not (val + bit, res);
      res &= mask;
      if (wi::gtu_p (res, val))
        return res ^ sgnbit;
    }
  return val ^ sgnbit;
}

/* Helper for overflow_comparison_p

   OP0 CODE OP1 is a comparison.  Examine the comparison and potentially
   OP1's defining statement to see if it ultimately has the form
   OP0 CODE (OP0 PLUS INTEGER_CST)

   If so, return TRUE indicating this is an overflow test and store into
   *NEW_CST an updated constant that can be used in a narrowed range test.

   REVERSED indicates if the comparison was originally:

   OP1 CODE' OP0.

   This affects how we build the updated constant.  */

static bool
overflow_comparison_p_1 (enum tree_code code, tree op0, tree op1,
                         bool follow_assert_exprs, bool reversed, tree *new_cst)
{
  /* See if this is a relational operation between two SSA_NAMES with
     unsigned, overflow wrapping values.  If so, check it more deeply.  */
  if ((code == LT_EXPR || code == LE_EXPR
       || code == GE_EXPR || code == GT_EXPR)
      && TREE_CODE (op0) == SSA_NAME
      && TREE_CODE (op1) == SSA_NAME
      && INTEGRAL_TYPE_P (TREE_TYPE (op0))
      && TYPE_UNSIGNED (TREE_TYPE (op0))
      && TYPE_OVERFLOW_WRAPS (TREE_TYPE (op0)))
    {
      gimple *op1_def = SSA_NAME_DEF_STMT (op1);

      /* If requested, follow any ASSERT_EXPRs backwards for OP1.  */
      if (follow_assert_exprs)
        {
          while (gimple_assign_single_p (op1_def)
                 && TREE_CODE (gimple_assign_rhs1 (op1_def)) == ASSERT_EXPR)
            {
              op1 = TREE_OPERAND (gimple_assign_rhs1 (op1_def), 0);
              if (TREE_CODE (op1) != SSA_NAME)
                break;
              op1_def = SSA_NAME_DEF_STMT (op1);
            }
        }

      /* Now look at the defining statement of OP1 to see if it adds
         or subtracts a nonzero constant from another operand.  */
      if (op1_def
          && is_gimple_assign (op1_def)
          && gimple_assign_rhs_code (op1_def) == PLUS_EXPR
          && TREE_CODE (gimple_assign_rhs2 (op1_def)) == INTEGER_CST
          && !integer_zerop (gimple_assign_rhs2 (op1_def)))
        {
          tree target = gimple_assign_rhs1 (op1_def);

          /* If requested, follow ASSERT_EXPRs backwards for op0 looking
             for one where TARGET appears on the RHS.  */
          if (follow_assert_exprs)
            {
              /* Now see if that "other operand" is op0, following the chain
                 of ASSERT_EXPRs if necessary.  */
              gimple *op0_def = SSA_NAME_DEF_STMT (op0);
              while (op0 != target
                     && gimple_assign_single_p (op0_def)
                     && TREE_CODE (gimple_assign_rhs1 (op0_def)) == ASSERT_EXPR)
                {
                  op0 = TREE_OPERAND (gimple_assign_rhs1 (op0_def), 0);
                  if (TREE_CODE (op0) != SSA_NAME)
                    break;
                  op0_def = SSA_NAME_DEF_STMT (op0);
                }
            }

          /* If we did not find our target SSA_NAME, then this is not
             an overflow test.  */
          if (op0 != target)
            return false;

          tree type = TREE_TYPE (op0);
          wide_int max = wi::max_value (TYPE_PRECISION (type), UNSIGNED);
          tree inc = gimple_assign_rhs2 (op1_def);
          if (reversed)
            *new_cst = wide_int_to_tree (type, max + wi::to_wide (inc));
          else
            *new_cst = wide_int_to_tree (type, max - wi::to_wide (inc));
          return true;
        }
    }
  return false;
}

/* OP0 CODE OP1 is a comparison.  Examine the comparison and potentially
   OP1's defining statement to see if it ultimately has the form
   OP0 CODE (OP0 PLUS INTEGER_CST)

   If so, return TRUE indicating this is an overflow test and store into
   *NEW_CST an updated constant that can be used in a narrowed range test.

   These statements are left as-is in the IL to facilitate discovery of
   {ADD,SUB}_OVERFLOW sequences later in the optimizer pipeline.  But
   the alternate range representation is often useful within VRP.  */

bool
overflow_comparison_p (tree_code code, tree name, tree val,
                       bool use_equiv_p, tree *new_cst)
{
  if (overflow_comparison_p_1 (code, name, val, use_equiv_p, false, new_cst))
    return true;
  return overflow_comparison_p_1 (swap_tree_comparison (code), val, name,
                                  use_equiv_p, true, new_cst);
}


/* Try to register an edge assertion for SSA name NAME on edge E for
   the condition COND contributing to the conditional jump pointed to by BSI.
   Invert the condition COND if INVERT is true.  */

static void
register_edge_assert_for_2 (tree name, edge e,
                            enum tree_code cond_code,
                            tree cond_op0, tree cond_op1, bool invert,
                            vec<assert_info> &asserts)
{
  tree val;
  enum tree_code comp_code;

  if (!extract_code_and_val_from_cond_with_ops (name, cond_code,
                                                cond_op0,
                                                cond_op1,
                                                invert, &comp_code, &val))
    return;

  /* Queue the assert.  */
  tree x;
  if (overflow_comparison_p (comp_code, name, val, false, &x))
    {
      enum tree_code new_code = ((comp_code == GT_EXPR || comp_code == GE_EXPR)
                                 ? GT_EXPR : LE_EXPR);
      add_assert_info (asserts, name, name, new_code, x);
    }
  add_assert_info (asserts, name, name, comp_code, val);

  /* In the case of NAME <= CST and NAME being defined as
     NAME = (unsigned) NAME2 + CST2 we can assert NAME2 >= -CST2
     and NAME2 <= CST - CST2.  We can do the same for NAME > CST.
     This catches range and anti-range tests.  */
  if ((comp_code == LE_EXPR
       || comp_code == GT_EXPR)
      && TREE_CODE (val) == INTEGER_CST
      && TYPE_UNSIGNED (TREE_TYPE (val)))
    {
      gimple *def_stmt = SSA_NAME_DEF_STMT (name);
      tree cst2 = NULL_TREE, name2 = NULL_TREE, name3 = NULL_TREE;

      /* Extract CST2 from the (optional) addition.  */
      if (is_gimple_assign (def_stmt)
          && gimple_assign_rhs_code (def_stmt) == PLUS_EXPR)
        {
          name2 = gimple_assign_rhs1 (def_stmt);
          cst2 = gimple_assign_rhs2 (def_stmt);
          if (TREE_CODE (name2) == SSA_NAME
              && TREE_CODE (cst2) == INTEGER_CST)
            def_stmt = SSA_NAME_DEF_STMT (name2);
        }

      /* Extract NAME2 from the (optional) sign-changing cast.  */
      if (gimple_assign_cast_p (def_stmt))
        {
          if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt))
              && ! TYPE_UNSIGNED (TREE_TYPE (gimple_assign_rhs1 (def_stmt)))
              && (TYPE_PRECISION (gimple_expr_type (def_stmt))
                  == TYPE_PRECISION (TREE_TYPE (gimple_assign_rhs1 (def_stmt)))))
            name3 = gimple_assign_rhs1 (def_stmt);
        }

      /* If name3 is used later, create an ASSERT_EXPR for it.  */
      if (name3 != NULL_TREE
          && TREE_CODE (name3) == SSA_NAME
          && (cst2 == NULL_TREE
              || TREE_CODE (cst2) == INTEGER_CST)
          && INTEGRAL_TYPE_P (TREE_TYPE (name3)))
        {
          tree tmp;

          /* Build an expression for the range test.  */
          tmp = build1 (NOP_EXPR, TREE_TYPE (name), name3);
          if (cst2 != NULL_TREE)
            tmp = build2 (PLUS_EXPR, TREE_TYPE (name), tmp, cst2);

          if (dump_file)
            {
              fprintf (dump_file, "Adding assert for ");
              print_generic_expr (dump_file, name3);
              fprintf (dump_file, " from ");
              print_generic_expr (dump_file, tmp);
              fprintf (dump_file, "\n");
            }

          add_assert_info (asserts, name3, tmp, comp_code, val);
        }

      /* If name2 is used later, create an ASSERT_EXPR for it.  */
      if (name2 != NULL_TREE
          && TREE_CODE (name2) == SSA_NAME
          && TREE_CODE (cst2) == INTEGER_CST
          && INTEGRAL_TYPE_P (TREE_TYPE (name2)))
        {
          tree tmp;

          /* Build an expression for the range test.  */
          tmp = name2;
          if (TREE_TYPE (name) != TREE_TYPE (name2))
            tmp = build1 (NOP_EXPR, TREE_TYPE (name), tmp);
          if (cst2 != NULL_TREE)
            tmp = build2 (PLUS_EXPR, TREE_TYPE (name), tmp, cst2);

          if (dump_file)
            {
              fprintf (dump_file, "Adding assert for ");
              print_generic_expr (dump_file, name2);
              fprintf (dump_file, " from ");
              print_generic_expr (dump_file, tmp);
              fprintf (dump_file, "\n");
            }

          add_assert_info (asserts, name2, tmp, comp_code, val);
        }
    }

  /* In the case of post-in/decrement tests like if (i++) ... and uses
     of the in/decremented value on the edge the extra name we want to
     assert for is not on the def chain of the name compared.  Instead
     it is in the set of use stmts.
     Similar cases happen for conversions that were simplified through
     fold_{sign_changed,widened}_comparison.  */
  if ((comp_code == NE_EXPR
       || comp_code == EQ_EXPR)
      && TREE_CODE (val) == INTEGER_CST)
    {
      imm_use_iterator ui;
      gimple *use_stmt;
      FOR_EACH_IMM_USE_STMT (use_stmt, ui, name)
        {
          if (!is_gimple_assign (use_stmt))
            continue;

          /* Cut off to use-stmts that are dominating the predecessor.  */
          if (!dominated_by_p (CDI_DOMINATORS, e->src, gimple_bb (use_stmt)))
            continue;

          tree name2 = gimple_assign_lhs (use_stmt);
          if (TREE_CODE (name2) != SSA_NAME)
            continue;

          enum tree_code code = gimple_assign_rhs_code (use_stmt);
          tree cst;
          if (code == PLUS_EXPR
              || code == MINUS_EXPR)
            {
              cst = gimple_assign_rhs2 (use_stmt);
              if (TREE_CODE (cst) != INTEGER_CST)
                continue;
              cst = int_const_binop (code, val, cst);
            }
          else if (CONVERT_EXPR_CODE_P (code))
            {
              /* For truncating conversions we cannot record
                 an inequality.  */
              if (comp_code == NE_EXPR
                  && (TYPE_PRECISION (TREE_TYPE (name2))
                      < TYPE_PRECISION (TREE_TYPE (name))))
                continue;
              cst = fold_convert (TREE_TYPE (name2), val);
            }
          else
            continue;

          if (TREE_OVERFLOW_P (cst))
            cst = drop_tree_overflow (cst);
          add_assert_info (asserts, name2, name2, comp_code, cst);
        }
    }
 
  if (TREE_CODE_CLASS (comp_code) == tcc_comparison
      && TREE_CODE (val) == INTEGER_CST)
    {
      gimple *def_stmt = SSA_NAME_DEF_STMT (name);
      tree name2 = NULL_TREE, names[2], cst2 = NULL_TREE;
      tree val2 = NULL_TREE;
      unsigned int prec = TYPE_PRECISION (TREE_TYPE (val));
      wide_int mask = wi::zero (prec);
      unsigned int nprec = prec;
      enum tree_code rhs_code = ERROR_MARK;

      if (is_gimple_assign (def_stmt))
        rhs_code = gimple_assign_rhs_code (def_stmt);

      /* In the case of NAME != CST1 where NAME = A +- CST2 we can
         assert that A != CST1 -+ CST2.  */
      if ((comp_code == EQ_EXPR || comp_code == NE_EXPR)
          && (rhs_code == PLUS_EXPR || rhs_code == MINUS_EXPR))
        {
          tree op0 = gimple_assign_rhs1 (def_stmt);
          tree op1 = gimple_assign_rhs2 (def_stmt);
          if (TREE_CODE (op0) == SSA_NAME
              && TREE_CODE (op1) == INTEGER_CST)
            {
              enum tree_code reverse_op = (rhs_code == PLUS_EXPR
                                           ? MINUS_EXPR : PLUS_EXPR);
              op1 = int_const_binop (reverse_op, val, op1);
              if (TREE_OVERFLOW (op1))
                op1 = drop_tree_overflow (op1);
              add_assert_info (asserts, op0, op0, comp_code, op1);
            }
        }

      /* Add asserts for NAME cmp CST and NAME being defined
         as NAME = (int) NAME2.  */
      if (!TYPE_UNSIGNED (TREE_TYPE (val))
          && (comp_code == LE_EXPR || comp_code == LT_EXPR
              || comp_code == GT_EXPR || comp_code == GE_EXPR)
          && gimple_assign_cast_p (def_stmt))
        {
          name2 = gimple_assign_rhs1 (def_stmt);
          if (CONVERT_EXPR_CODE_P (rhs_code)
              && INTEGRAL_TYPE_P (TREE_TYPE (name2))
              && TYPE_UNSIGNED (TREE_TYPE (name2))
              && prec == TYPE_PRECISION (TREE_TYPE (name2))
              && (comp_code == LE_EXPR || comp_code == GT_EXPR
                  || !tree_int_cst_equal (val,
                                          TYPE_MIN_VALUE (TREE_TYPE (val)))))
            {
              tree tmp, cst;
              enum tree_code new_comp_code = comp_code;

              cst = fold_convert (TREE_TYPE (name2),
                                  TYPE_MIN_VALUE (TREE_TYPE (val)));
              /* Build an expression for the range test.  */
              tmp = build2 (PLUS_EXPR, TREE_TYPE (name2), name2, cst);
              cst = fold_build2 (PLUS_EXPR, TREE_TYPE (name2), cst,
                                 fold_convert (TREE_TYPE (name2), val));
              if (comp_code == LT_EXPR || comp_code == GE_EXPR)
                {
                  new_comp_code = comp_code == LT_EXPR ? LE_EXPR : GT_EXPR;
                  cst = fold_build2 (MINUS_EXPR, TREE_TYPE (name2), cst,
                                     build_int_cst (TREE_TYPE (name2), 1));
                }

              if (dump_file)
                {
                  fprintf (dump_file, "Adding assert for ");
                  print_generic_expr (dump_file, name2);
                  fprintf (dump_file, " from ");
                  print_generic_expr (dump_file, tmp);
                  fprintf (dump_file, "\n");
                }

              add_assert_info (asserts, name2, tmp, new_comp_code, cst);
            }
        }

      /* Add asserts for NAME cmp CST and NAME being defined as
         NAME = NAME2 >> CST2.

         Extract CST2 from the right shift.  */
      if (rhs_code == RSHIFT_EXPR)
        {
          name2 = gimple_assign_rhs1 (def_stmt);
          cst2 = gimple_assign_rhs2 (def_stmt);
          if (TREE_CODE (name2) == SSA_NAME
              && tree_fits_uhwi_p (cst2)
              && INTEGRAL_TYPE_P (TREE_TYPE (name2))
              && IN_RANGE (tree_to_uhwi (cst2), 1, prec - 1)
              && type_has_mode_precision_p (TREE_TYPE (val)))
            {
              mask = wi::mask (tree_to_uhwi (cst2), false, prec);
              val2 = fold_binary (LSHIFT_EXPR, TREE_TYPE (val), val, cst2);
            }
        }
      if (val2 != NULL_TREE
          && TREE_CODE (val2) == INTEGER_CST
          && simple_cst_equal (fold_build2 (RSHIFT_EXPR,
                                            TREE_TYPE (val),
                                            val2, cst2), val))
        {
          enum tree_code new_comp_code = comp_code;
          tree tmp, new_val;

          tmp = name2;
          if (comp_code == EQ_EXPR || comp_code == NE_EXPR)
            {
              if (!TYPE_UNSIGNED (TREE_TYPE (val)))
                {
                  tree type = build_nonstandard_integer_type (prec, 1);
                  tmp = build1 (NOP_EXPR, type, name2);
                  val2 = fold_convert (type, val2);
                }
              tmp = fold_build2 (MINUS_EXPR, TREE_TYPE (tmp), tmp, val2);
              new_val = wide_int_to_tree (TREE_TYPE (tmp), mask);
              new_comp_code = comp_code == EQ_EXPR ? LE_EXPR : GT_EXPR;
            }
          else if (comp_code == LT_EXPR || comp_code == GE_EXPR)
            {
              wide_int minval
                = wi::min_value (prec, TYPE_SIGN (TREE_TYPE (val)));
              new_val = val2;
              if (minval == wi::to_wide (new_val))
                new_val = NULL_TREE;
            }
          else
            {
              wide_int maxval
                = wi::max_value (prec, TYPE_SIGN (TREE_TYPE (val)));
              mask |= wi::to_wide (val2);
              if (wi::eq_p (mask, maxval))
                new_val = NULL_TREE;
              else
                new_val = wide_int_to_tree (TREE_TYPE (val2), mask);
            }

          if (new_val)
            {
              if (dump_file)
                {
                  fprintf (dump_file, "Adding assert for ");
                  print_generic_expr (dump_file, name2);
                  fprintf (dump_file, " from ");
                  print_generic_expr (dump_file, tmp);
                  fprintf (dump_file, "\n");
                }

              add_assert_info (asserts, name2, tmp, new_comp_code, new_val);
            }
        }

      /* Add asserts for NAME cmp CST and NAME being defined as
         NAME = NAME2 & CST2.

         Extract CST2 from the and.

         Also handle
         NAME = (unsigned) NAME2;
         casts where NAME's type is unsigned and has smaller precision
         than NAME2's type as if it was NAME = NAME2 & MASK.  */
      names[0] = NULL_TREE;
      names[1] = NULL_TREE;
      cst2 = NULL_TREE;
      if (rhs_code == BIT_AND_EXPR
          || (CONVERT_EXPR_CODE_P (rhs_code)
              && INTEGRAL_TYPE_P (TREE_TYPE (val))
              && TYPE_UNSIGNED (TREE_TYPE (val))
              && TYPE_PRECISION (TREE_TYPE (gimple_assign_rhs1 (def_stmt)))
                 > prec))
        {
          name2 = gimple_assign_rhs1 (def_stmt);
          if (rhs_code == BIT_AND_EXPR)
            cst2 = gimple_assign_rhs2 (def_stmt);
          else
            {
              cst2 = TYPE_MAX_VALUE (TREE_TYPE (val));
              nprec = TYPE_PRECISION (TREE_TYPE (name2));
            }
          if (TREE_CODE (name2) == SSA_NAME
              && INTEGRAL_TYPE_P (TREE_TYPE (name2))
              && TREE_CODE (cst2) == INTEGER_CST
              && !integer_zerop (cst2)
              && (nprec > 1
                  || TYPE_UNSIGNED (TREE_TYPE (val))))
            {
              gimple *def_stmt2 = SSA_NAME_DEF_STMT (name2);
              if (gimple_assign_cast_p (def_stmt2))
                {
                  names[1] = gimple_assign_rhs1 (def_stmt2);
                  if (!CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (def_stmt2))
                      || !INTEGRAL_TYPE_P (TREE_TYPE (names[1]))
                      || (TYPE_PRECISION (TREE_TYPE (name2))
                          != TYPE_PRECISION (TREE_TYPE (names[1]))))
                    names[1] = NULL_TREE;
                }
              names[0] = name2;
            }
        }
      if (names[0] || names[1])
        {
          wide_int minv, maxv, valv, cst2v;
          wide_int tem, sgnbit;
          bool valid_p = false, valn, cst2n;
          enum tree_code ccode = comp_code;

          valv = wide_int::from (wi::to_wide (val), nprec, UNSIGNED);
          cst2v = wide_int::from (wi::to_wide (cst2), nprec, UNSIGNED);
          valn = wi::neg_p (valv, TYPE_SIGN (TREE_TYPE (val)));
          cst2n = wi::neg_p (cst2v, TYPE_SIGN (TREE_TYPE (val)));
          /* If CST2 doesn't have most significant bit set,
             but VAL is negative, we have comparison like
             if ((x & 0x123) > -4) (always true).  Just give up.  */
          if (!cst2n && valn)
            ccode = ERROR_MARK;
          if (cst2n)
            sgnbit = wi::set_bit_in_zero (nprec - 1, nprec);
          else
            sgnbit = wi::zero (nprec);
          minv = valv & cst2v;
          switch (ccode)
            {
            case EQ_EXPR:
              /* Minimum unsigned value for equality is VAL & CST2
                 (should be equal to VAL, otherwise we probably should
                 have folded the comparison into false) and
                 maximum unsigned value is VAL | ~CST2.  */
              maxv = valv | ~cst2v;
              valid_p = true;
              break;

            case NE_EXPR:
              tem = valv | ~cst2v;
              /* If VAL is 0, handle (X & CST2) != 0 as (X & CST2) > 0U.  */
              if (valv == 0)
                {
                  cst2n = false;
                  sgnbit = wi::zero (nprec);
                  goto gt_expr;
                }
              /* If (VAL | ~CST2) is all ones, handle it as
                 (X & CST2) < VAL.  */
              if (tem == -1)
                {
                  cst2n = false;
                  valn = false;
                  sgnbit = wi::zero (nprec);
                  goto lt_expr;
                }
              if (!cst2n && wi::neg_p (cst2v))
                sgnbit = wi::set_bit_in_zero (nprec - 1, nprec);
              if (sgnbit != 0)
                {
                  if (valv == sgnbit)
                    {
                      cst2n = true;
                      valn = true;
                      goto gt_expr;
                    }
                  if (tem == wi::mask (nprec - 1, false, nprec))
                    {
                      cst2n = true;
                      goto lt_expr;
                    }
                  if (!cst2n)
                    sgnbit = wi::zero (nprec);
                }
              break;

            case GE_EXPR:
              /* Minimum unsigned value for >= if (VAL & CST2) == VAL
                 is VAL and maximum unsigned value is ~0.  For signed
                 comparison, if CST2 doesn't have most significant bit
                 set, handle it similarly.  If CST2 has MSB set,
                 the minimum is the same, and maximum is ~0U/2.  */
              if (minv != valv)
                {
                  /* If (VAL & CST2) != VAL, X & CST2 can't be equal to
                     VAL.  */
                  minv = masked_increment (valv, cst2v, sgnbit, nprec);
                  if (minv == valv)
                    break;
                }
              maxv = wi::mask (nprec - (cst2n ? 1 : 0), false, nprec);
              valid_p = true;
              break;

            case GT_EXPR:
            gt_expr:
              /* Find out smallest MINV where MINV > VAL
                 && (MINV & CST2) == MINV, if any.  If VAL is signed and
                 CST2 has MSB set, compute it biased by 1 << (nprec - 1).  */
              minv = masked_increment (valv, cst2v, sgnbit, nprec);
              if (minv == valv)
                break;
              maxv = wi::mask (nprec - (cst2n ? 1 : 0), false, nprec);
              valid_p = true;
              break;

            case LE_EXPR:
              /* Minimum unsigned value for <= is 0 and maximum
                 unsigned value is VAL | ~CST2 if (VAL & CST2) == VAL.
                 Otherwise, find smallest VAL2 where VAL2 > VAL
                 && (VAL2 & CST2) == VAL2 and use (VAL2 - 1) | ~CST2
                 as maximum.
                 For signed comparison, if CST2 doesn't have most
                 significant bit set, handle it similarly.  If CST2 has
                 MSB set, the maximum is the same and minimum is INT_MIN.  */
              if (minv == valv)
                maxv = valv;
              else
                {
                  maxv = masked_increment (valv, cst2v, sgnbit, nprec);
                  if (maxv == valv)
                    break;
                  maxv -= 1;
                }
              maxv |= ~cst2v;
              minv = sgnbit;
              valid_p = true;
              break;

            case LT_EXPR:
            lt_expr:
              /* Minimum unsigned value for < is 0 and maximum
                 unsigned value is (VAL-1) | ~CST2 if (VAL & CST2) == VAL.
                 Otherwise, find smallest VAL2 where VAL2 > VAL
                 && (VAL2 & CST2) == VAL2 and use (VAL2 - 1) | ~CST2
                 as maximum.
                 For signed comparison, if CST2 doesn't have most
                 significant bit set, handle it similarly.  If CST2 has
                 MSB set, the maximum is the same and minimum is INT_MIN.  */
              if (minv == valv)
                {
                  if (valv == sgnbit)
                    break;
                  maxv = valv;
                }
              else
                {
                  maxv = masked_increment (valv, cst2v, sgnbit, nprec);
                  if (maxv == valv)
                    break;
                }
              maxv -= 1;
              maxv |= ~cst2v;
              minv = sgnbit;
              valid_p = true;
              break;

            default:
              break;
            }
          if (valid_p
              && (maxv - minv) != -1)
            {
              tree tmp, new_val, type;
              int i;

              for (i = 0; i < 2; i++)
                if (names[i])
                  {
                    wide_int maxv2 = maxv;
                    tmp = names[i];
                    type = TREE_TYPE (names[i]);
                    if (!TYPE_UNSIGNED (type))
                      {
                        type = build_nonstandard_integer_type (nprec, 1);
                        tmp = build1 (NOP_EXPR, type, names[i]);
                      }
                    if (minv != 0)
                      {
                        tmp = build2 (PLUS_EXPR, type, tmp,
                                      wide_int_to_tree (type, -minv));
                        maxv2 = maxv - minv;
                      }
                    new_val = wide_int_to_tree (type, maxv2);

                    if (dump_file)
                      {
                        fprintf (dump_file, "Adding assert for ");
                        print_generic_expr (dump_file, names[i]);
                        fprintf (dump_file, " from ");
                        print_generic_expr (dump_file, tmp);
                        fprintf (dump_file, "\n");
                      }

                    add_assert_info (asserts, names[i], tmp, LE_EXPR, new_val);
                  }
            }
        }
    }
}

/* OP is an operand of a truth value expression which is known to have
   a particular value.  Register any asserts for OP and for any
   operands in OP's defining statement.

   If CODE is EQ_EXPR, then we want to register OP is zero (false),
   if CODE is NE_EXPR, then we want to register OP is nonzero (true).   */

static void
register_edge_assert_for_1 (tree op, enum tree_code code,
                            edge e, vec<assert_info> &asserts)
{
  gimple *op_def;
  tree val;
  enum tree_code rhs_code;

  /* We only care about SSA_NAMEs.  */
  if (TREE_CODE (op) != SSA_NAME)
    return;

  /* We know that OP will have a zero or nonzero value.  */
  val = build_int_cst (TREE_TYPE (op), 0);
  add_assert_info (asserts, op, op, code, val);

  /* Now look at how OP is set.  If it's set from a comparison,
     a truth operation or some bit operations, then we may be able
     to register information about the operands of that assignment.  */
  op_def = SSA_NAME_DEF_STMT (op);
  if (gimple_code (op_def) != GIMPLE_ASSIGN)
    return;

  rhs_code = gimple_assign_rhs_code (op_def);

  if (TREE_CODE_CLASS (rhs_code) == tcc_comparison)
    {
      bool invert = (code == EQ_EXPR ? true : false);
      tree op0 = gimple_assign_rhs1 (op_def);
      tree op1 = gimple_assign_rhs2 (op_def);

      if (TREE_CODE (op0) == SSA_NAME)
        register_edge_assert_for_2 (op0, e, rhs_code, op0, op1, invert, asserts);
      if (TREE_CODE (op1) == SSA_NAME)
        register_edge_assert_for_2 (op1, e, rhs_code, op0, op1, invert, asserts);
    }
  else if ((code == NE_EXPR
            && gimple_assign_rhs_code (op_def) == BIT_AND_EXPR)
           || (code == EQ_EXPR
               && gimple_assign_rhs_code (op_def) == BIT_IOR_EXPR))
    {
      /* Recurse on each operand.  */
      tree op0 = gimple_assign_rhs1 (op_def);
      tree op1 = gimple_assign_rhs2 (op_def);
      if (TREE_CODE (op0) == SSA_NAME
          && has_single_use (op0))
        register_edge_assert_for_1 (op0, code, e, asserts);
      if (TREE_CODE (op1) == SSA_NAME
          && has_single_use (op1))
        register_edge_assert_for_1 (op1, code, e, asserts);
    }
  else if (gimple_assign_rhs_code (op_def) == BIT_NOT_EXPR
           && TYPE_PRECISION (TREE_TYPE (gimple_assign_lhs (op_def))) == 1)
    {
      /* Recurse, flipping CODE.  */
      code = invert_tree_comparison (code, false);
      register_edge_assert_for_1 (gimple_assign_rhs1 (op_def), code, e, asserts);
    }
  else if (gimple_assign_rhs_code (op_def) == SSA_NAME)
    {
      /* Recurse through the copy.  */
      register_edge_assert_for_1 (gimple_assign_rhs1 (op_def), code, e, asserts);
    }
  else if (CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (op_def)))
    {
      /* Recurse through the type conversion, unless it is a narrowing
         conversion or conversion from non-integral type.  */
      tree rhs = gimple_assign_rhs1 (op_def);
      if (INTEGRAL_TYPE_P (TREE_TYPE (rhs))
          && (TYPE_PRECISION (TREE_TYPE (rhs))
              <= TYPE_PRECISION (TREE_TYPE (op))))
        register_edge_assert_for_1 (rhs, code, e, asserts);
    }
}

/* Check if comparison
     NAME COND_OP INTEGER_CST
   has a form of
     (X & 11...100..0) COND_OP XX...X00...0
   Such comparison can yield assertions like
     X >= XX...X00...0
     X <= XX...X11...1
   in case of COND_OP being EQ_EXPR or
     X < XX...X00...0
     X > XX...X11...1
   in case of NE_EXPR.  */

static bool
is_masked_range_test (tree name, tree valt, enum tree_code cond_code,
                      tree *new_name, tree *low, enum tree_code *low_code,
                      tree *high, enum tree_code *high_code)
{
  gimple *def_stmt = SSA_NAME_DEF_STMT (name);

  if (!is_gimple_assign (def_stmt)
      || gimple_assign_rhs_code (def_stmt) != BIT_AND_EXPR)
    return false;

  tree t = gimple_assign_rhs1 (def_stmt);
  tree maskt = gimple_assign_rhs2 (def_stmt);
  if (TREE_CODE (t) != SSA_NAME || TREE_CODE (maskt) != INTEGER_CST)
    return false;

  wi::tree_to_wide_ref mask = wi::to_wide (maskt);
  wide_int inv_mask = ~mask;
  /* Must have been removed by now so don't bother optimizing.  */
  if (mask == 0 || inv_mask == 0)
    return false;

  /* Assume VALT is INTEGER_CST.  */
  wi::tree_to_wide_ref val = wi::to_wide (valt);

  if ((inv_mask & (inv_mask + 1)) != 0
      || (val & mask) != val)
    return false;

  bool is_range = cond_code == EQ_EXPR;

  tree type = TREE_TYPE (t);
  wide_int min = wi::min_value (type),
    max = wi::max_value (type);

  if (is_range)
    {
      *low_code = val == min ? ERROR_MARK : GE_EXPR;
      *high_code = val == max ? ERROR_MARK : LE_EXPR;
    }
  else
    {
      /* We can still generate assertion if one of alternatives
         is known to always be false.  */
      if (val == min)
        {
          *low_code = (enum tree_code) 0;
          *high_code = GT_EXPR;
        }
      else if ((val | inv_mask) == max)
        {
          *low_code = LT_EXPR;
          *high_code = (enum tree_code) 0;
        }
      else
        return false;
    }

  *new_name = t;
  *low = wide_int_to_tree (type, val);
  *high = wide_int_to_tree (type, val | inv_mask);

  return true;
}

/* Try to register an edge assertion for SSA name NAME on edge E for
   the condition COND contributing to the conditional jump pointed to by
   SI.  */

void
register_edge_assert_for (tree name, edge e,
                          enum tree_code cond_code, tree cond_op0,
                          tree cond_op1, vec<assert_info> &asserts)
{
  tree val;
  enum tree_code comp_code;
  bool is_else_edge = (e->flags & EDGE_FALSE_VALUE) != 0;

  /* Do not attempt to infer anything in names that flow through
     abnormal edges.  */
  if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (name))
    return;

  if (!extract_code_and_val_from_cond_with_ops (name, cond_code,
                                                cond_op0, cond_op1,
                                                is_else_edge,
                                                &comp_code, &val))
    return;

  /* Register ASSERT_EXPRs for name.  */
  register_edge_assert_for_2 (name, e, cond_code, cond_op0,
                              cond_op1, is_else_edge, asserts);


  /* If COND is effectively an equality test of an SSA_NAME against
     the value zero or one, then we may be able to assert values
     for SSA_NAMEs which flow into COND.  */

  /* In the case of NAME == 1 or NAME != 0, for BIT_AND_EXPR defining
     statement of NAME we can assert both operands of the BIT_AND_EXPR
     have nonzero value.  */
  if (((comp_code == EQ_EXPR && integer_onep (val))
       || (comp_code == NE_EXPR && integer_zerop (val))))
    {
      gimple *def_stmt = SSA_NAME_DEF_STMT (name);

      if (is_gimple_assign (def_stmt)
          && gimple_assign_rhs_code (def_stmt) == BIT_AND_EXPR)
        {
          tree op0 = gimple_assign_rhs1 (def_stmt);
          tree op1 = gimple_assign_rhs2 (def_stmt);
          register_edge_assert_for_1 (op0, NE_EXPR, e, asserts);
          register_edge_assert_for_1 (op1, NE_EXPR, e, asserts);
        }
    }

  /* In the case of NAME == 0 or NAME != 1, for BIT_IOR_EXPR defining
     statement of NAME we can assert both operands of the BIT_IOR_EXPR
     have zero value.  */
  if (((comp_code == EQ_EXPR && integer_zerop (val))
       || (comp_code == NE_EXPR && integer_onep (val))))
    {
      gimple *def_stmt = SSA_NAME_DEF_STMT (name);

      /* For BIT_IOR_EXPR only if NAME == 0 both operands have
         necessarily zero value, or if type-precision is one.  */
      if (is_gimple_assign (def_stmt)
          && (gimple_assign_rhs_code (def_stmt) == BIT_IOR_EXPR
              && (TYPE_PRECISION (TREE_TYPE (name)) == 1
                  || comp_code == EQ_EXPR)))
        {
          tree op0 = gimple_assign_rhs1 (def_stmt);
          tree op1 = gimple_assign_rhs2 (def_stmt);
          register_edge_assert_for_1 (op0, EQ_EXPR, e, asserts);
          register_edge_assert_for_1 (op1, EQ_EXPR, e, asserts);
        }
    }

  /* Sometimes we can infer ranges from (NAME & MASK) == VALUE.  */
  if ((comp_code == EQ_EXPR || comp_code == NE_EXPR)
      && TREE_CODE (val) == INTEGER_CST)
    {
      enum tree_code low_code, high_code;
      tree low, high;
      if (is_masked_range_test (name, val, comp_code, &name, &low,
                                &low_code, &high, &high_code))
        {
          if (low_code != ERROR_MARK)
            register_edge_assert_for_2 (name, e, low_code, name,
                                        low, /*invert*/false, asserts);
          if (high_code != ERROR_MARK)
            register_edge_assert_for_2 (name, e, high_code, name,
                                        high, /*invert*/false, asserts);
        }
    }
}

/* Finish found ASSERTS for E and register them at GSI.  */

static void
finish_register_edge_assert_for (edge e, gimple_stmt_iterator gsi,
                                 vec<assert_info> &asserts)
{
  for (unsigned i = 0; i < asserts.length (); ++i)
    /* Only register an ASSERT_EXPR if NAME was found in the sub-graph
       reachable from E.  */
    if (live_on_edge (e, asserts[i].name))
      register_new_assert_for (asserts[i].name, asserts[i].expr,
                               asserts[i].comp_code, asserts[i].val,
                               NULL, e, gsi);
}



/* Determine whether the outgoing edges of BB should receive an
   ASSERT_EXPR for each of the operands of BB's LAST statement.
   The last statement of BB must be a COND_EXPR.

   If any of the sub-graphs rooted at BB have an interesting use of
   the predicate operands, an assert location node is added to the
   list of assertions for the corresponding operands.  */

static void
find_conditional_asserts (basic_block bb, gcond *last)
{
  gimple_stmt_iterator bsi;
  tree op;
  edge_iterator ei;
  edge e;
  ssa_op_iter iter;

  bsi = gsi_for_stmt (last);

  /* Look for uses of the operands in each of the sub-graphs
     rooted at BB.  We need to check each of the outgoing edges
     separately, so that we know what kind of ASSERT_EXPR to
     insert.  */
  FOR_EACH_EDGE (e, ei, bb->succs)
    {
      if (e->dest == bb)
        continue;

      /* Register the necessary assertions for each operand in the
         conditional predicate.  */
      auto_vec<assert_info, 8> asserts;
      FOR_EACH_SSA_TREE_OPERAND (op, last, iter, SSA_OP_USE)
        register_edge_assert_for (op, e,
                                  gimple_cond_code (last),
                                  gimple_cond_lhs (last),
                                  gimple_cond_rhs (last), asserts);
      finish_register_edge_assert_for (e, bsi, asserts);
    }
}

struct case_info
{
  tree expr;
  basic_block bb;
};

/* Compare two case labels sorting first by the destination bb index
   and then by the case value.  */

static int
compare_case_labels (const void *p1, const void *p2)
{
  const struct case_info *ci1 = (const struct case_info *) p1;
  const struct case_info *ci2 = (const struct case_info *) p2;
  int idx1 = ci1->bb->index;
  int idx2 = ci2->bb->index;

  if (idx1 < idx2)
    return -1;
  else if (idx1 == idx2)
    {
      /* Make sure the default label is first in a group.  */
      if (!CASE_LOW (ci1->expr))
        return -1;
      else if (!CASE_LOW (ci2->expr))
        return 1;
      else
        return tree_int_cst_compare (CASE_LOW (ci1->expr),
                                     CASE_LOW (ci2->expr));
    }
  else
    return 1;
}

/* Determine whether the outgoing edges of BB should receive an
   ASSERT_EXPR for each of the operands of BB's LAST statement.
   The last statement of BB must be a SWITCH_EXPR.

   If any of the sub-graphs rooted at BB have an interesting use of
   the predicate operands, an assert location node is added to the
   list of assertions for the corresponding operands.  */

static void
find_switch_asserts (basic_block bb, gswitch *last)
{
  gimple_stmt_iterator bsi;
  tree op;
  edge e;
  struct case_info *ci;
  size_t n = gimple_switch_num_labels (last);
#if GCC_VERSION >= 4000
  unsigned int idx;
#else
  /* Work around GCC 3.4 bug (PR 37086).  */
  volatile unsigned int idx;
#endif

  bsi = gsi_for_stmt (last);
  op = gimple_switch_index (last);
  if (TREE_CODE (op) != SSA_NAME)
    return;

  /* Build a vector of case labels sorted by destination label.  */
  ci = XNEWVEC (struct case_info, n);
  for (idx = 0; idx < n; ++idx)
    {
      ci[idx].expr = gimple_switch_label (last, idx);
      ci[idx].bb = label_to_block (cfun, CASE_LABEL (ci[idx].expr));
    }
  edge default_edge = find_edge (bb, ci[0].bb);
  qsort (ci, n, sizeof (struct case_info), compare_case_labels);

  for (idx = 0; idx < n; ++idx)
    {
      tree min, max;
      tree cl = ci[idx].expr;
      basic_block cbb = ci[idx].bb;

      min = CASE_LOW (cl);
      max = CASE_HIGH (cl);

      /* If there are multiple case labels with the same destination
         we need to combine them to a single value range for the edge.  */
      if (idx + 1 < n && cbb == ci[idx + 1].bb)
        {
          /* Skip labels until the last of the group.  */
          do {
            ++idx;
          } while (idx < n && cbb == ci[idx].bb);
          --idx;

          /* Pick up the maximum of the case label range.  */
          if (CASE_HIGH (ci[idx].expr))
            max = CASE_HIGH (ci[idx].expr);
          else
            max = CASE_LOW (ci[idx].expr);
        }

      /* Can't extract a useful assertion out of a range that includes the
         default label.  */
      if (min == NULL_TREE)
        continue;

      /* Find the edge to register the assert expr on.  */
      e = find_edge (bb, cbb);

      /* Register the necessary assertions for the operand in the
         SWITCH_EXPR.  */
      auto_vec<assert_info, 8> asserts;
      register_edge_assert_for (op, e,
                                max ? GE_EXPR : EQ_EXPR,
                                op, fold_convert (TREE_TYPE (op), min),
                                asserts);
      if (max)
        register_edge_assert_for (op, e, LE_EXPR, op,
                                  fold_convert (TREE_TYPE (op), max),
                                  asserts);
      finish_register_edge_assert_for (e, bsi, asserts);
    }

  XDELETEVEC (ci);

  if (!live_on_edge (default_edge, op))
    return;

  /* Now register along the default label assertions that correspond to the
     anti-range of each label.  */
  int insertion_limit = PARAM_VALUE (PARAM_MAX_VRP_SWITCH_ASSERTIONS);
  if (insertion_limit == 0)
    return;

  /* We can't do this if the default case shares a label with another case.  */
  tree default_cl = gimple_switch_default_label (last);
  for (idx = 1; idx < n; idx++)
    {
      tree min, max;
      tree cl = gimple_switch_label (last, idx);
      if (CASE_LABEL (cl) == CASE_LABEL (default_cl))
        continue;

      min = CASE_LOW (cl);
      max = CASE_HIGH (cl);

      /* Combine contiguous case ranges to reduce the number of assertions
         to insert.  */
      for (idx = idx + 1; idx < n; idx++)
        {
          tree next_min, next_max;
          tree next_cl = gimple_switch_label (last, idx);
          if (CASE_LABEL (next_cl) == CASE_LABEL (default_cl))
            break;

          next_min = CASE_LOW (next_cl);
          next_max = CASE_HIGH (next_cl);

          wide_int difference = (wi::to_wide (next_min)
                                 - wi::to_wide (max ? max : min));
          if (wi::eq_p (difference, 1))
            max = next_max ? next_max : next_min;
          else
            break;
        }
      idx--;

      if (max == NULL_TREE)
        {
          /* Register the assertion OP != MIN.  */
          auto_vec<assert_info, 8> asserts;
          min = fold_convert (TREE_TYPE (op), min);
          register_edge_assert_for (op, default_edge, NE_EXPR, op, min,
                                    asserts);
          finish_register_edge_assert_for (default_edge, bsi, asserts);
        }
      else
        {
          /* Register the assertion (unsigned)OP - MIN > (MAX - MIN),
             which will give OP the anti-range ~[MIN,MAX].  */
          tree uop = fold_convert (unsigned_type_for (TREE_TYPE (op)), op);
          min = fold_convert (TREE_TYPE (uop), min);
          max = fold_convert (TREE_TYPE (uop), max);

          tree lhs = fold_build2 (MINUS_EXPR, TREE_TYPE (uop), uop, min);
          tree rhs = int_const_binop (MINUS_EXPR, max, min);
          register_new_assert_for (op, lhs, GT_EXPR, rhs,
                                   NULL, default_edge, bsi);
        }

      if (--insertion_limit == 0)
        break;
    }
}


/* Traverse all the statements in block BB looking for statements that
   may generate useful assertions for the SSA names in their operand.
   If a statement produces a useful assertion A for name N_i, then the
   list of assertions already generated for N_i is scanned to
   determine if A is actually needed.

   If N_i already had the assertion A at a location dominating the
   current location, then nothing needs to be done.  Otherwise, the
   new location for A is recorded instead.

   1- For every statement S in BB, all the variables used by S are
      added to bitmap FOUND_IN_SUBGRAPH.

   2- If statement S uses an operand N in a way that exposes a known
      value range for N, then if N was not already generated by an
      ASSERT_EXPR, create a new assert location for N.  For instance,
      if N is a pointer and the statement dereferences it, we can
      assume that N is not NULL.

   3- COND_EXPRs are a special case of #2.  We can derive range
      information from the predicate but need to insert different
      ASSERT_EXPRs for each of the sub-graphs rooted at the
      conditional block.  If the last statement of BB is a conditional
      expression of the form 'X op Y', then

      a) Remove X and Y from the set FOUND_IN_SUBGRAPH.

      b) If the conditional is the only entry point to the sub-graph
         corresponding to the THEN_CLAUSE, recurse into it.  On
         return, if X and/or Y are marked in FOUND_IN_SUBGRAPH, then
         an ASSERT_EXPR is added for the corresponding variable.

      c) Repeat step (b) on the ELSE_CLAUSE.

      d) Mark X and Y in FOUND_IN_SUBGRAPH.

      For instance,

            if (a == 9)
              b = a;
            else
              b = c + 1;

      In this case, an assertion on the THEN clause is useful to
      determine that 'a' is always 9 on that edge.  However, an assertion
      on the ELSE clause would be unnecessary.

   4- If BB does not end in a conditional expression, then we recurse
      into BB's dominator children.

   At the end of the recursive traversal, every SSA name will have a
   list of locations where ASSERT_EXPRs should be added.  When a new
   location for name N is found, it is registered by calling
   register_new_assert_for.  That function keeps track of all the
   registered assertions to prevent adding unnecessary assertions.
   For instance, if a pointer P_4 is dereferenced more than once in a
   dominator tree, only the location dominating all the dereference of
   P_4 will receive an ASSERT_EXPR.  */

static void
find_assert_locations_1 (basic_block bb, sbitmap live)
{
  gimple *last;

  last = last_stmt (bb);

  /* If BB's last statement is a conditional statement involving integer
     operands, determine if we need to add ASSERT_EXPRs.  */
  if (last
      && gimple_code (last) == GIMPLE_COND
      && !fp_predicate (last)
      && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
    find_conditional_asserts (bb, as_a <gcond *> (last));

  /* If BB's last statement is a switch statement involving integer
     operands, determine if we need to add ASSERT_EXPRs.  */
  if (last
      && gimple_code (last) == GIMPLE_SWITCH
      && !ZERO_SSA_OPERANDS (last, SSA_OP_USE))
    find_switch_asserts (bb, as_a <gswitch *> (last));

  /* Traverse all the statements in BB marking used names and looking
     for statements that may infer assertions for their used operands.  */
  for (gimple_stmt_iterator si = gsi_last_bb (bb); !gsi_end_p (si);
       gsi_prev (&si))
    {
      gimple *stmt;
      tree op;
      ssa_op_iter i;

      stmt = gsi_stmt (si);

      if (is_gimple_debug (stmt))
        continue;

      /* See if we can derive an assertion for any of STMT's operands.  */
      FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
        {
          tree value;
          enum tree_code comp_code;

          /* If op is not live beyond this stmt, do not bother to insert
             asserts for it.  */
          if (!bitmap_bit_p (live, SSA_NAME_VERSION (op)))
            continue;

          /* If OP is used in such a way that we can infer a value
             range for it, and we don't find a previous assertion for
             it, create a new assertion location node for OP.  */
          if (infer_value_range (stmt, op, &comp_code, &value))
            {
              /* If we are able to infer a nonzero value range for OP,
                 then walk backwards through the use-def chain to see if OP
                 was set via a typecast.

                 If so, then we can also infer a nonzero value range
                 for the operand of the NOP_EXPR.  */
              if (comp_code == NE_EXPR && integer_zerop (value))
                {
                  tree t = op;
                  gimple *def_stmt = SSA_NAME_DEF_STMT (t);

                  while (is_gimple_assign (def_stmt)
                         && CONVERT_EXPR_CODE_P
                             (gimple_assign_rhs_code (def_stmt))
                         && TREE_CODE
                             (gimple_assign_rhs1 (def_stmt)) == SSA_NAME
                         && POINTER_TYPE_P
                             (TREE_TYPE (gimple_assign_rhs1 (def_stmt))))
                    {
                      t = gimple_assign_rhs1 (def_stmt);
                      def_stmt = SSA_NAME_DEF_STMT (t);

                      /* Note we want to register the assert for the
                         operand of the NOP_EXPR after SI, not after the
                         conversion.  */
                      if (bitmap_bit_p (live, SSA_NAME_VERSION (t)))
                        register_new_assert_for (t, t, comp_code, value,
                                                 bb, NULL, si);
                    }
                }

              register_new_assert_for (op, op, comp_code, value, bb, NULL, si);
            }
        }

      /* Update live.  */
      FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_USE)
        bitmap_set_bit (live, SSA_NAME_VERSION (op));
      FOR_EACH_SSA_TREE_OPERAND (op, stmt, i, SSA_OP_DEF)
        bitmap_clear_bit (live, SSA_NAME_VERSION (op));
    }

  /* Traverse all PHI nodes in BB, updating live.  */
  for (gphi_iterator si = gsi_start_phis (bb); !gsi_end_p (si);
       gsi_next (&si))
    {
      use_operand_p arg_p;
      ssa_op_iter i;
      gphi *phi = si.phi ();
      tree res = gimple_phi_result (phi);

      if (virtual_operand_p (res))
        continue;

      FOR_EACH_PHI_ARG (arg_p, phi, i, SSA_OP_USE)
        {
          tree arg = USE_FROM_PTR (arg_p);
          if (TREE_CODE (arg) == SSA_NAME)
            bitmap_set_bit (live, SSA_NAME_VERSION (arg));
        }

      bitmap_clear_bit (live, SSA_NAME_VERSION (res));
    }
}

/* Do an RPO walk over the function computing SSA name liveness
   on-the-fly and deciding on assert expressions to insert.  */

static void
find_assert_locations (void)
{
  int *rpo = XNEWVEC (int, last_basic_block_for_fn (cfun));
  int *bb_rpo = XNEWVEC (int, last_basic_block_for_fn (cfun));
  int *last_rpo = XCNEWVEC (int, last_basic_block_for_fn (cfun));
  int rpo_cnt, i;

  live = XCNEWVEC (sbitmap, last_basic_block_for_fn (cfun));
  rpo_cnt = pre_and_rev_post_order_compute (NULL, rpo, false);
  for (i = 0; i < rpo_cnt; ++i)
    bb_rpo[rpo[i]] = i;

  /* Pre-seed loop latch liveness from loop header PHI nodes.  Due to
     the order we compute liveness and insert asserts we otherwise
     fail to insert asserts into the loop latch.  */
  loop_p loop;
  FOR_EACH_LOOP (loop, 0)
    {
      i = loop->latch->index;
      unsigned int j = single_succ_edge (loop->latch)->dest_idx;
      for (gphi_iterator gsi = gsi_start_phis (loop->header);
           !gsi_end_p (gsi); gsi_next (&gsi))
        {
          gphi *phi = gsi.phi ();
          if (virtual_operand_p (gimple_phi_result (phi)))
            continue;
          tree arg = gimple_phi_arg_def (phi, j);
          if (TREE_CODE (arg) == SSA_NAME)
            {
              if (live[i] == NULL)
                {
                  live[i] = sbitmap_alloc (num_ssa_names);
                  bitmap_clear (live[i]);
                }
              bitmap_set_bit (live[i], SSA_NAME_VERSION (arg));
            }
        }
    }

  for (i = rpo_cnt - 1; i >= 0; --i)
    {
      basic_block bb = BASIC_BLOCK_FOR_FN (cfun, rpo[i]);
      edge e;
      edge_iterator ei;

      if (!live[rpo[i]])
        {
          live[rpo[i]] = sbitmap_alloc (num_ssa_names);
          bitmap_clear (live[rpo[i]]);
        }

      /* Process BB and update the live information with uses in
         this block.  */
      find_assert_locations_1 (bb, live[rpo[i]]);

      /* Merge liveness into the predecessor blocks and free it.  */
      if (!bitmap_empty_p (live[rpo[i]]))
        {
          int pred_rpo = i;
          FOR_EACH_EDGE (e, ei, bb->preds)
            {
              int pred = e->src->index;
              if ((e->flags & EDGE_DFS_BACK) || pred == ENTRY_BLOCK)
                continue;

              if (!live[pred])
                {
                  live[pred] = sbitmap_alloc (num_ssa_names);
                  bitmap_clear (live[pred]);
                }
              bitmap_ior (live[pred], live[pred], live[rpo[i]]);

              if (bb_rpo[pred] < pred_rpo)
                pred_rpo = bb_rpo[pred];
            }

          /* Record the RPO number of the last visited block that needs
             live information from this block.  */
          last_rpo[rpo[i]] = pred_rpo;
        }
      else
        {
          sbitmap_free (live[rpo[i]]);
          live[rpo[i]] = NULL;
        }

      /* We can free all successors live bitmaps if all their
         predecessors have been visited already.  */
      FOR_EACH_EDGE (e, ei, bb->succs)
        if (last_rpo[e->dest->index] == i
            && live[e->dest->index])
          {
            sbitmap_free (live[e->dest->index]);
            live[e->dest->index] = NULL;
          }
    }

  XDELETEVEC (rpo);
  XDELETEVEC (bb_rpo);
  XDELETEVEC (last_rpo);
  for (i = 0; i < last_basic_block_for_fn (cfun); ++i)
    if (live[i])
      sbitmap_free (live[i]);
  XDELETEVEC (live);
}

/* Create an ASSERT_EXPR for NAME and insert it in the location
   indicated by LOC.  Return true if we made any edge insertions.  */

static bool
process_assert_insertions_for (tree name, assert_locus *loc)
{
  /* Build the comparison expression NAME_i COMP_CODE VAL.  */
  gimple *stmt;
  tree cond;
  gimple *assert_stmt;
  edge_iterator ei;
  edge e;

  /* If we have X <=> X do not insert an assert expr for that.  */
  if (loc->expr == loc->val)
    return false;

  cond = build2 (loc->comp_code, boolean_type_node, loc->expr, loc->val);
  assert_stmt = build_assert_expr_for (cond, name);
  if (loc->e)
    {
      /* We have been asked to insert the assertion on an edge.  This
         is used only by COND_EXPR and SWITCH_EXPR assertions.  */
      gcc_checking_assert (gimple_code (gsi_stmt (loc->si)) == GIMPLE_COND
                           || (gimple_code (gsi_stmt (loc->si))
                               == GIMPLE_SWITCH));

      gsi_insert_on_edge (loc->e, assert_stmt);
      return true;
    }

  /* If the stmt iterator points at the end then this is an insertion
     at the beginning of a block.  */
  if (gsi_end_p (loc->si))
    {
      gimple_stmt_iterator si = gsi_after_labels (loc->bb);
      gsi_insert_before (&si, assert_stmt, GSI_SAME_STMT);
      return false;

    }
  /* Otherwise, we can insert right after LOC->SI iff the
     statement must not be the last statement in the block.  */
  stmt = gsi_stmt (loc->si);
  if (!stmt_ends_bb_p (stmt))
    {
      gsi_insert_after (&loc->si, assert_stmt, GSI_SAME_STMT);
      return false;
    }

  /* If STMT must be the last statement in BB, we can only insert new
     assertions on the non-abnormal edge out of BB.  Note that since
     STMT is not control flow, there may only be one non-abnormal/eh edge
     out of BB.  */
  FOR_EACH_EDGE (e, ei, loc->bb->succs)
    if (!(e->flags & (EDGE_ABNORMAL|EDGE_EH)))
      {
        gsi_insert_on_edge (e, assert_stmt);
        return true;
      }

  gcc_unreachable ();
}

/* Qsort helper for sorting assert locations.  If stable is true, don't
   use iterative_hash_expr because it can be unstable for -fcompare-debug,
   on the other side some pointers might be NULL.  */

template <bool stable>
static int
compare_assert_loc (const void *pa, const void *pb)
{
  assert_locus * const a = *(assert_locus * const *)pa;
  assert_locus * const b = *(assert_locus * const *)pb;

  /* If stable, some asserts might be optimized away already, sort
     them last.  */
  if (stable)
    {
      if (a == NULL)
        return b != NULL;
      else if (b == NULL)
        return -1;
    }

  if (a->e == NULL && b->e != NULL)
    return 1;
  else if (a->e != NULL && b->e == NULL)
    return -1;

  /* After the above checks, we know that (a->e == NULL) == (b->e == NULL),
     no need to test both a->e and b->e.  */

  /* Sort after destination index.  */
  if (a->e == NULL)
    ;
  else if (a->e->dest->index > b->e->dest->index)
    return 1;
  else if (a->e->dest->index < b->e->dest->index)
    return -1;

  /* Sort after comp_code.  */
  if (a->comp_code > b->comp_code)
    return 1;
  else if (a->comp_code < b->comp_code)
    return -1;

  hashval_t ha, hb;

  /* E.g. if a->val is ADDR_EXPR of a VAR_DECL, iterative_hash_expr
     uses DECL_UID of the VAR_DECL, so sorting might differ between
     -g and -g0.  When doing the removal of redundant assert exprs
     and commonization to successors, this does not matter, but for
     the final sort needs to be stable.  */
  if (stable)
    {
      ha = 0;
      hb = 0;
    }
  else
    {
      ha = iterative_hash_expr (a->expr, iterative_hash_expr (a->val, 0));
      hb = iterative_hash_expr (b->expr, iterative_hash_expr (b->val, 0));
    }

  /* Break the tie using hashing and source/bb index.  */
  if (ha == hb)
    return (a->e != NULL
            ? a->e->src->index - b->e->src->index
            : a->bb->index - b->bb->index);
  return ha > hb ? 1 : -1;
}

/* Process all the insertions registered for every name N_i registered
   in NEED_ASSERT_FOR.  The list of assertions to be inserted are
   found in ASSERTS_FOR[i].  */

static void
process_assert_insertions (void)
{
  unsigned i;
  bitmap_iterator bi;
  bool update_edges_p = false;
  int num_asserts = 0;

  if (dump_file && (dump_flags & TDF_DETAILS))
    dump_all_asserts (dump_file);

  EXECUTE_IF_SET_IN_BITMAP (need_assert_for, 0, i, bi)
    {
      assert_locus *loc = asserts_for[i];
      gcc_assert (loc);

      auto_vec<assert_locus *, 16> asserts;
      for (; loc; loc = loc->next)
        asserts.safe_push (loc);
      asserts.qsort (compare_assert_loc<false>);

      /* Push down common asserts to successors and remove redundant ones.  */
      unsigned ecnt = 0;
      assert_locus *common = NULL;
      unsigned commonj = 0;
      for (unsigned j = 0; j < asserts.length (); ++j)
        {
          loc = asserts[j];
          if (! loc->e)
            common = NULL;
          else if (! common
                   || loc->e->dest != common->e->dest
                   || loc->comp_code != common->comp_code
                   || ! operand_equal_p (loc->val, common->val, 0)
                   || ! operand_equal_p (loc->expr, common->expr, 0))
            {
              commonj = j;
              common = loc;
              ecnt = 1;
            }
          else if (loc->e == asserts[j-1]->e)
            {
              /* Remove duplicate asserts.  */
              if (commonj == j - 1)
                {
                  commonj = j;
                  common = loc;
                }
              free (asserts[j-1]);
              asserts[j-1] = NULL;
            }
          else
            {
              ecnt++;
              if (EDGE_COUNT (common->e->dest->preds) == ecnt)
                {
                  /* We have the same assertion on all incoming edges of a BB.
                     Insert it at the beginning of that block.  */
                  loc->bb = loc->e->dest;
                  loc->e = NULL;
                  loc->si = gsi_none ();
                  common = NULL;
                  /* Clear asserts commoned.  */
                  for (; commonj != j; ++commonj)
                    if (asserts[commonj])
                      {
                        free (asserts[commonj]);
                        asserts[commonj] = NULL;
                      }
                }
            }
        }

      /* The asserts vector sorting above might be unstable for
         -fcompare-debug, sort again to ensure a stable sort.  */
      asserts.qsort (compare_assert_loc<true>);
      for (unsigned j = 0; j < asserts.length (); ++j)
        {
          loc = asserts[j];
          if (! loc)
            break;
          update_edges_p |= process_assert_insertions_for (ssa_name (i), loc);
          num_asserts++;
          free (loc);
        }
    }

  if (update_edges_p)
    gsi_commit_edge_inserts ();

  statistics_counter_event (cfun, "Number of ASSERT_EXPR expressions inserted",
                            num_asserts);
}


/* Traverse the flowgraph looking for conditional jumps to insert range
   expressions.  These range expressions are meant to provide information
   to optimizations that need to reason in terms of value ranges.  They
   will not be expanded into RTL.  For instance, given:

   x = ...
   y = ...
   if (x < y)
     y = x - 2;
   else
     x = y + 3;

   this pass will transform the code into:

   x = ...
   y = ...
   if (x < y)
    {
      x = ASSERT_EXPR <x, x < y>
      y = x - 2
    }
   else
    {
      y = ASSERT_EXPR <y, x >= y>
      x = y + 3
    }

   The idea is that once copy and constant propagation have run, other
   optimizations will be able to determine what ranges of values can 'x'
   take in different paths of the code, simply by checking the reaching
   definition of 'x'.  */

static void
insert_range_assertions (void)
{
  need_assert_for = BITMAP_ALLOC (NULL);
  asserts_for = XCNEWVEC (assert_locus *, num_ssa_names);

  calculate_dominance_info (CDI_DOMINATORS);

  find_assert_locations ();
  if (!bitmap_empty_p (need_assert_for))
    {
      process_assert_insertions ();
      update_ssa (TODO_update_ssa_no_phi);
    }

  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "\nSSA form after inserting ASSERT_EXPRs\n");
      dump_function_to_file (current_function_decl, dump_file, dump_flags);
    }

  free (asserts_for);
  BITMAP_FREE (need_assert_for);
}

class vrp_prop : public ssa_propagation_engine
{
 public:
  enum ssa_prop_result visit_stmt (gimple *, edge *, tree *) FINAL OVERRIDE;
  enum ssa_prop_result visit_phi (gphi *) FINAL OVERRIDE;

  void vrp_initialize (void);
  void vrp_finalize (bool);
  void check_all_array_refs (void);
  void check_array_ref (location_t, tree, bool);
  void check_mem_ref (location_t, tree, bool);
  void search_for_addr_array (tree, location_t);

  class vr_values vr_values;
  /* Temporary delegator to minimize code churn.  */
  value_range *get_value_range (const_tree op)
    { return vr_values.get_value_range (op); }
  void set_defs_to_varying (gimple *stmt)
    { return vr_values.set_defs_to_varying (stmt); }
  void extract_range_from_stmt (gimple *stmt, edge *taken_edge_p,
                                tree *output_p, value_range *vr)
    { vr_values.extract_range_from_stmt (stmt, taken_edge_p, output_p, vr); }
  bool update_value_range (const_tree op, value_range *vr)
    { return vr_values.update_value_range (op, vr); }
  void extract_range_basic (value_range *vr, gimple *stmt)
    { vr_values.extract_range_basic (vr, stmt); }
  void extract_range_from_phi_node (gphi *phi, value_range *vr)
    { vr_values.extract_range_from_phi_node (phi, vr); }
};
/* Checks one ARRAY_REF in REF, located at LOCUS. Ignores flexible arrays
   and "struct" hacks. If VRP can determine that the
   array subscript is a constant, check if it is outside valid
   range. If the array subscript is a RANGE, warn if it is
   non-overlapping with valid range.
   IGNORE_OFF_BY_ONE is true if the ARRAY_REF is inside a ADDR_EXPR.  */

void
vrp_prop::check_array_ref (location_t location, tree ref,
                           bool ignore_off_by_one)
{
  const value_range *vr = NULL;
  tree low_sub, up_sub;
  tree low_bound, up_bound, up_bound_p1;

  if (TREE_NO_WARNING (ref))
    return;

  low_sub = up_sub = TREE_OPERAND (ref, 1);
  up_bound = array_ref_up_bound (ref);

  if (!up_bound
      || TREE_CODE (up_bound) != INTEGER_CST
      || (warn_array_bounds < 2
          && array_at_struct_end_p (ref)))
    {
      /* Accesses to trailing arrays via pointers may access storage
         beyond the types array bounds.  For such arrays, or for flexible
         array members, as well as for other arrays of an unknown size,
         replace the upper bound with a more permissive one that assumes
         the size of the largest object is PTRDIFF_MAX.  */
      tree eltsize = array_ref_element_size (ref);

      if (TREE_CODE (eltsize) != INTEGER_CST
          || integer_zerop (eltsize))
        {
          up_bound = NULL_TREE;
          up_bound_p1 = NULL_TREE;
        }
      else
        {
          tree maxbound = TYPE_MAX_VALUE (ptrdiff_type_node);
          tree arg = TREE_OPERAND (ref, 0);
          poly_int64 off;

          if (get_addr_base_and_unit_offset (arg, &off) && known_gt (off, 0))
            maxbound = wide_int_to_tree (sizetype,
                                         wi::sub (wi::to_wide (maxbound),
                                                  off));
          else
            maxbound = fold_convert (sizetype, maxbound);

          up_bound_p1 = int_const_binop (TRUNC_DIV_EXPR, maxbound, eltsize);

          up_bound = int_const_binop (MINUS_EXPR, up_bound_p1,
                                      build_int_cst (ptrdiff_type_node, 1));
        }
    }
  else
    up_bound_p1 = int_const_binop (PLUS_EXPR, up_bound,
                                   build_int_cst (TREE_TYPE (up_bound), 1));

  low_bound = array_ref_low_bound (ref);

  tree artype = TREE_TYPE (TREE_OPERAND (ref, 0));

  bool warned = false;

  /* Empty array.  */
  if (up_bound && tree_int_cst_equal (low_bound, up_bound_p1))
    warned = warning_at (location, OPT_Warray_bounds,
                         "array subscript %E is above array bounds of %qT",
                         low_bound, artype);

  if (TREE_CODE (low_sub) == SSA_NAME)
    {
      vr = get_value_range (low_sub);
      if (vr->type == VR_RANGE || vr->type == VR_ANTI_RANGE)
        {
          low_sub = vr->type == VR_RANGE ? vr->max : vr->min;
          up_sub = vr->type == VR_RANGE ? vr->min : vr->max;
        }
    }

  if (vr && vr->type == VR_ANTI_RANGE)
    {
      if (up_bound
          && TREE_CODE (up_sub) == INTEGER_CST
          && (ignore_off_by_one
              ? tree_int_cst_lt (up_bound, up_sub)
              : tree_int_cst_le (up_bound, up_sub))
          && TREE_CODE (low_sub) == INTEGER_CST
          && tree_int_cst_le (low_sub, low_bound))
        warned = warning_at (location, OPT_Warray_bounds,
                             "array subscript [%E, %E] is outside "
                             "array bounds of %qT",
                             low_sub, up_sub, artype);
    }
  else if (up_bound
           && TREE_CODE (up_sub) == INTEGER_CST
           && (ignore_off_by_one
               ? !tree_int_cst_le (up_sub, up_bound_p1)
               : !tree_int_cst_le (up_sub, up_bound)))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
        {
          fprintf (dump_file, "Array bound warning for ");
          dump_generic_expr (MSG_NOTE, TDF_SLIM, ref);
          fprintf (dump_file, "\n");
        }
      warned = warning_at (location, OPT_Warray_bounds,
                           "array subscript %E is above array bounds of %qT",
                           up_sub, artype);
    }
  else if (TREE_CODE (low_sub) == INTEGER_CST
           && tree_int_cst_lt (low_sub, low_bound))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
        {
          fprintf (dump_file, "Array bound warning for ");
          dump_generic_expr (MSG_NOTE, TDF_SLIM, ref);
          fprintf (dump_file, "\n");
        }
      warned = warning_at (location, OPT_Warray_bounds,
                           "array subscript %E is below array bounds of %qT",
                           low_sub, artype);
    }

  if (warned)
    {
      ref = TREE_OPERAND (ref, 0);

      if (DECL_P (ref))
        inform (DECL_SOURCE_LOCATION (ref), "while referencing %qD", ref);

      TREE_NO_WARNING (ref) = 1;
    }
}

/* Checks one MEM_REF in REF, located at LOCATION, for out-of-bounds
   references to string constants.  If VRP can determine that the array
   subscript is a constant, check if it is outside valid range.
   If the array subscript is a RANGE, warn if it is non-overlapping
   with valid range.
   IGNORE_OFF_BY_ONE is true if the MEM_REF is inside an ADDR_EXPR
   (used to allow one-past-the-end indices for code that takes
   the address of the just-past-the-end element of an array).  */

void
vrp_prop::check_mem_ref (location_t location, tree ref,
                         bool ignore_off_by_one)
{
  if (TREE_NO_WARNING (ref))
    return;

  tree arg = TREE_OPERAND (ref, 0);
  /* The constant and variable offset of the reference.  */
  tree cstoff = TREE_OPERAND (ref, 1);
  tree varoff = NULL_TREE;

  const offset_int maxobjsize = tree_to_shwi (max_object_size ());

  /* The array or string constant bounds in bytes.  Initially set
     to [-MAXOBJSIZE - 1, MAXOBJSIZE]  until a tighter bound is
     determined.  */
  offset_int arrbounds[2] = { -maxobjsize - 1, maxobjsize };

  /* The minimum and maximum intermediate offset.  For a reference
     to be valid, not only does the final offset/subscript must be
     in bounds but all intermediate offsets should be as well.
     GCC may be able to deal gracefully with such out-of-bounds
     offsets so the checking is only enbaled at -Warray-bounds=2
     where it may help detect bugs in uses of the intermediate
     offsets that could otherwise not be detectable.  */
  offset_int ioff = wi::to_offset (fold_convert (ptrdiff_type_node, cstoff));
  offset_int extrema[2] = { 0, wi::abs (ioff) };

  /* The range of the byte offset into the reference.  */
  offset_int offrange[2] = { 0, 0 };

  const value_range *vr = NULL;

  /* Determine the offsets and increment OFFRANGE for the bounds of each.
     The loop computes the the range of the final offset for expressions
     such as (A + i0 + ... + iN)[CSTOFF] where i0 through iN are SSA_NAMEs
     in some range.  */
  while (TREE_CODE (arg) == SSA_NAME)
    {
      gimple *def = SSA_NAME_DEF_STMT (arg);
      if (!is_gimple_assign (def))
        break;

      tree_code code = gimple_assign_rhs_code (def);
      if (code == POINTER_PLUS_EXPR)
        {
          arg = gimple_assign_rhs1 (def);
          varoff = gimple_assign_rhs2 (def);
        }
      else if (code == ASSERT_EXPR)
        {
          arg = TREE_OPERAND (gimple_assign_rhs1 (def), 0);
          continue;
        }
      else
        return;

      /* VAROFF should always be a SSA_NAME here (and not even
         INTEGER_CST) but there's no point in taking chances.  */
      if (TREE_CODE (varoff) != SSA_NAME)
        break;

      vr = get_value_range (varoff);
      if (!vr || vr->type == VR_UNDEFINED || !vr->min || !vr->max)
        break;

      if (TREE_CODE (vr->min) != INTEGER_CST
          || TREE_CODE (vr->max) != INTEGER_CST)
        break;

      if (vr->type == VR_RANGE)
        {
          if (tree_int_cst_lt (vr->min, vr->max))
            {
              offset_int min
                = wi::to_offset (fold_convert (ptrdiff_type_node, vr->min));
              offset_int max
                = wi::to_offset (fold_convert (ptrdiff_type_node, vr->max));
              if (min < max)
                {
                  offrange[0] += min;
                  offrange[1] += max;
                }
              else
                {
                  offrange[0] += max;
                  offrange[1] += min;
                }
            }
          else
            {
              /* Conservatively add [-MAXOBJSIZE -1, MAXOBJSIZE]
                 to OFFRANGE.  */
              offrange[0] += arrbounds[0];
              offrange[1] += arrbounds[1];
            }
        }
      else
        {
          /* For an anti-range, analogously to the above, conservatively
             add [-MAXOBJSIZE -1, MAXOBJSIZE] to OFFRANGE.  */
          offrange[0] += arrbounds[0];
          offrange[1] += arrbounds[1];
        }

      /* Keep track of the minimum and maximum offset.  */
      if (offrange[1] < 0 && offrange[1] < extrema[0])
        extrema[0] = offrange[1];
      if (offrange[0] > 0 && offrange[0] > extrema[1])
        extrema[1] = offrange[0];

      if (offrange[0] < arrbounds[0])
        offrange[0] = arrbounds[0];

      if (offrange[1] > arrbounds[1])
        offrange[1] = arrbounds[1];
    }

  if (TREE_CODE (arg) == ADDR_EXPR)
    {
      arg = TREE_OPERAND (arg, 0);
      if (TREE_CODE (arg) != STRING_CST
          && TREE_CODE (arg) != VAR_DECL)
        return;
    }
  else
    return;

  /* The type of the object being referred to.  It can be an array,
     string literal, or a non-array type when the MEM_REF represents
     a reference/subscript via a pointer to an object that is not
     an element of an array.  References to members of structs and
     unions are excluded because MEM_REF doesn't make it possible
     to identify the member where the reference originated.
     Incomplete types are excluded as well because their size is
     not known.  */
  tree reftype = TREE_TYPE (arg);
  if (POINTER_TYPE_P (reftype)
      || !COMPLETE_TYPE_P (reftype)
      || TREE_CODE (TYPE_SIZE_UNIT (reftype)) != INTEGER_CST
      || RECORD_OR_UNION_TYPE_P (reftype))
    return;

  offset_int eltsize;
  if (TREE_CODE (reftype) == ARRAY_TYPE)
    {
      eltsize = wi::to_offset (TYPE_SIZE_UNIT (TREE_TYPE (reftype)));

      if (tree dom = TYPE_DOMAIN (reftype))
        {
          tree bnds[] = { TYPE_MIN_VALUE (dom), TYPE_MAX_VALUE (dom) };
          if (array_at_struct_end_p (arg)
              || !bnds[0] || !bnds[1])
            {
              arrbounds[0] = 0;
              arrbounds[1] = wi::lrshift (maxobjsize, wi::floor_log2 (eltsize));
            }
          else
            {
              arrbounds[0] = wi::to_offset (bnds[0]) * eltsize;
              arrbounds[1] = (wi::to_offset (bnds[1]) + 1) * eltsize;
            }
        }
      else
        {
          arrbounds[0] = 0;
          arrbounds[1] = wi::lrshift (maxobjsize, wi::floor_log2 (eltsize));
        }

      if (TREE_CODE (ref) == MEM_REF)
        {
          /* For MEM_REF determine a tighter bound of the non-array
             element type.  */
          tree eltype = TREE_TYPE (reftype);
          while (TREE_CODE (eltype) == ARRAY_TYPE)
            eltype = TREE_TYPE (eltype);
          eltsize = wi::to_offset (TYPE_SIZE_UNIT (eltype));
        }
    }
  else
    {
      eltsize = 1;
      arrbounds[0] = 0;
      arrbounds[1] = wi::to_offset (TYPE_SIZE_UNIT (reftype));
    }

  offrange[0] += ioff;
  offrange[1] += ioff;

  /* Compute the more permissive upper bound when IGNORE_OFF_BY_ONE
     is set (when taking the address of the one-past-last element
     of an array) but always use the stricter bound in diagnostics. */
  offset_int ubound = arrbounds[1];
  if (ignore_off_by_one)
    ubound += 1;

  if (offrange[0] >= ubound || offrange[1] < arrbounds[0])
    {
      /* Treat a reference to a non-array object as one to an array
         of a single element.  */
      if (TREE_CODE (reftype) != ARRAY_TYPE)
        reftype = build_array_type_nelts (reftype, 1);

      if (TREE_CODE (ref) == MEM_REF)
        {
          /* Extract the element type out of MEM_REF and use its size
             to compute the index to print in the diagnostic; arrays
             in MEM_REF don't mean anything.   */
          tree type = TREE_TYPE (ref);
          while (TREE_CODE (type) == ARRAY_TYPE)
            type = TREE_TYPE (type);
          tree size = TYPE_SIZE_UNIT (type);
          offrange[0] = offrange[0] / wi::to_offset (size);
          offrange[1] = offrange[1] / wi::to_offset (size);
        }
      else
        {
          /* For anything other than MEM_REF, compute the index to
             print in the diagnostic as the offset over element size.  */
          offrange[0] = offrange[0] / eltsize;
          offrange[1] = offrange[1] / eltsize;
        }

      bool warned;
      if (offrange[0] == offrange[1])
        warned = warning_at (location, OPT_Warray_bounds,
                             "array subscript %wi is outside array bounds "
                             "of %qT",
                             offrange[0].to_shwi (), reftype);
      else
        warned = warning_at (location, OPT_Warray_bounds,
                             "array subscript [%wi, %wi] is outside "
                             "array bounds of %qT",
                             offrange[0].to_shwi (),
                             offrange[1].to_shwi (), reftype);
      if (warned && DECL_P (arg))
        inform (DECL_SOURCE_LOCATION (arg), "while referencing %qD", arg);

      TREE_NO_WARNING (ref) = 1;
      return;
    }

  if (warn_array_bounds < 2)
    return;

  /* At level 2 check also intermediate offsets.  */
  int i = 0;
  if (extrema[i] < -arrbounds[1] || extrema[i = 1] > ubound)
    {
      HOST_WIDE_INT tmpidx = extrema[i].to_shwi () / eltsize.to_shwi ();

      warning_at (location, OPT_Warray_bounds,
                  "intermediate array offset %wi is outside array bounds "
                  "of %qT",
                  tmpidx,  reftype);
      TREE_NO_WARNING (ref) = 1;
    }
}

/* Searches if the expr T, located at LOCATION computes
   address of an ARRAY_REF, and call check_array_ref on it.  */

void
vrp_prop::search_for_addr_array (tree t, location_t location)
{
  /* Check each ARRAY_REF and MEM_REF in the reference chain. */
  do
    {
      if (TREE_CODE (t) == ARRAY_REF)
        check_array_ref (location, t, true /*ignore_off_by_one*/);
      else if (TREE_CODE (t) == MEM_REF)
        check_mem_ref (location, t, true /*ignore_off_by_one*/);

      t = TREE_OPERAND (t, 0);
    }
  while (handled_component_p (t) || TREE_CODE (t) == MEM_REF);

  if (TREE_CODE (t) != MEM_REF
      || TREE_CODE (TREE_OPERAND (t, 0)) != ADDR_EXPR
      || TREE_NO_WARNING (t))
    return;

  tree tem = TREE_OPERAND (TREE_OPERAND (t, 0), 0);
  tree low_bound, up_bound, el_sz;
  if (TREE_CODE (TREE_TYPE (tem)) != ARRAY_TYPE
      || TREE_CODE (TREE_TYPE (TREE_TYPE (tem))) == ARRAY_TYPE
      || !TYPE_DOMAIN (TREE_TYPE (tem)))
    return;

  low_bound = TYPE_MIN_VALUE (TYPE_DOMAIN (TREE_TYPE (tem)));
  up_bound = TYPE_MAX_VALUE (TYPE_DOMAIN (TREE_TYPE (tem)));
  el_sz = TYPE_SIZE_UNIT (TREE_TYPE (TREE_TYPE (tem)));
  if (!low_bound
      || TREE_CODE (low_bound) != INTEGER_CST
      || !up_bound
      || TREE_CODE (up_bound) != INTEGER_CST
      || !el_sz
      || TREE_CODE (el_sz) != INTEGER_CST)
    return;

  offset_int idx;
  if (!mem_ref_offset (t).is_constant (&idx))
    return;

  bool warned = false;
  idx = wi::sdiv_trunc (idx, wi::to_offset (el_sz));
  if (idx < 0)
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
        {
          fprintf (dump_file, "Array bound warning for ");
          dump_generic_expr (MSG_NOTE, TDF_SLIM, t);
          fprintf (dump_file, "\n");
        }
      warned = warning_at (location, OPT_Warray_bounds,
                           "array subscript %wi is below "
                           "array bounds of %qT",
                           idx.to_shwi (), TREE_TYPE (tem));
    }
  else if (idx > (wi::to_offset (up_bound)
                  - wi::to_offset (low_bound) + 1))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
        {
          fprintf (dump_file, "Array bound warning for ");
          dump_generic_expr (MSG_NOTE, TDF_SLIM, t);
          fprintf (dump_file, "\n");
        }
      warned = warning_at (location, OPT_Warray_bounds,
                           "array subscript %wu is above "
                           "array bounds of %qT",
                           idx.to_uhwi (), TREE_TYPE (tem));
    }

  if (warned)
    {
      if (DECL_P (t))
        inform (DECL_SOURCE_LOCATION (t), "while referencing %qD", t);

      TREE_NO_WARNING (t) = 1;
    }
}

/* walk_tree() callback that checks if *TP is
   an ARRAY_REF inside an ADDR_EXPR (in which an array
   subscript one outside the valid range is allowed). Call
   check_array_ref for each ARRAY_REF found. The location is
   passed in DATA.  */

static tree
check_array_bounds (tree *tp, int *walk_subtree, void *data)
{
  tree t = *tp;
  struct walk_stmt_info *wi = (struct walk_stmt_info *) data;
  location_t location;

  if (EXPR_HAS_LOCATION (t))
    location = EXPR_LOCATION (t);
  else
    location = gimple_location (wi->stmt);

  *walk_subtree = TRUE;

  vrp_prop *vrp_prop = (class vrp_prop *)wi->info;
  if (TREE_CODE (t) == ARRAY_REF)
    vrp_prop->check_array_ref (location, t, false /*ignore_off_by_one*/);
  else if (TREE_CODE (t) == MEM_REF)
    vrp_prop->check_mem_ref (location, t, false /*ignore_off_by_one*/);
  else if (TREE_CODE (t) == ADDR_EXPR)
    {
      vrp_prop->search_for_addr_array (t, location);
      *walk_subtree = FALSE;
    }

  return NULL_TREE;
}

/* A dom_walker subclass for use by vrp_prop::check_all_array_refs,
   to walk over all statements of all reachable BBs and call
   check_array_bounds on them.  */

class check_array_bounds_dom_walker : public dom_walker
{
 public:
  check_array_bounds_dom_walker (vrp_prop *prop)
    : dom_walker (CDI_DOMINATORS,
                  /* Discover non-executable edges, preserving EDGE_EXECUTABLE
                     flags, so that we can merge in information on
                     non-executable edges from vrp_folder .  */
                  REACHABLE_BLOCKS_PRESERVING_FLAGS),
      m_prop (prop) {}
  ~check_array_bounds_dom_walker () {}

  edge before_dom_children (basic_block) FINAL OVERRIDE;

 private:
  vrp_prop *m_prop;
};

/* Implementation of dom_walker::before_dom_children.

   Walk over all statements of BB and call check_array_bounds on them,
   and determine if there's a unique successor edge.  */

edge
check_array_bounds_dom_walker::before_dom_children (basic_block bb)
{
  gimple_stmt_iterator si;
  for (si = gsi_start_bb (bb); !gsi_end_p (si); gsi_next (&si))
    {
      gimple *stmt = gsi_stmt (si);
      struct walk_stmt_info wi;
      if (!gimple_has_location (stmt)
          || is_gimple_debug (stmt))
        continue;

      memset (&wi, 0, sizeof (wi));

      wi.info = m_prop;

      walk_gimple_op (stmt, check_array_bounds, &wi);
    }

  /* Determine if there's a unique successor edge, and if so, return
     that back to dom_walker, ensuring that we don't visit blocks that
     became unreachable during the VRP propagation
     (PR tree-optimization/83312).  */
  return find_taken_edge (bb, NULL_TREE);
}

/* Walk over all statements of all reachable BBs and call check_array_bounds
   on them.  */

void
vrp_prop::check_all_array_refs ()
{
  check_array_bounds_dom_walker w (this);
  w.walk (ENTRY_BLOCK_PTR_FOR_FN (cfun));
}

/* Return true if all imm uses of VAR are either in STMT, or
   feed (optionally through a chain of single imm uses) GIMPLE_COND
   in basic block COND_BB.  */

static bool
all_imm_uses_in_stmt_or_feed_cond (tree var, gimple *stmt, basic_block cond_bb)
{
  use_operand_p use_p, use2_p;
  imm_use_iterator iter;

  FOR_EACH_IMM_USE_FAST (use_p, iter, var)
    if (USE_STMT (use_p) != stmt)
      {
        gimple *use_stmt = USE_STMT (use_p), *use_stmt2;
        if (is_gimple_debug (use_stmt))
          continue;
        while (is_gimple_assign (use_stmt)
               && TREE_CODE (gimple_assign_lhs (use_stmt)) == SSA_NAME
               && single_imm_use (gimple_assign_lhs (use_stmt),
                                  &use2_p, &use_stmt2))
          use_stmt = use_stmt2;
        if (gimple_code (use_stmt) != GIMPLE_COND
            || gimple_bb (use_stmt) != cond_bb)
          return false;
      }
  return true;
}

/* Handle
   _4 = x_3 & 31;
   if (_4 != 0)
     goto <bb 6>;
   else
     goto <bb 7>;
   <bb 6>:
   __builtin_unreachable ();
   <bb 7>:
   x_5 = ASSERT_EXPR <x_3, ...>;
   If x_3 has no other immediate uses (checked by caller),
   var is the x_3 var from ASSERT_EXPR, we can clear low 5 bits
   from the non-zero bitmask.  */

void
maybe_set_nonzero_bits (edge e, tree var)
{
  basic_block cond_bb = e->src;
  gimple *stmt = last_stmt (cond_bb);
  tree cst;

  if (stmt == NULL
      || gimple_code (stmt) != GIMPLE_COND
      || gimple_cond_code (stmt) != ((e->flags & EDGE_TRUE_VALUE)
                                     ? EQ_EXPR : NE_EXPR)
      || TREE_CODE (gimple_cond_lhs (stmt)) != SSA_NAME
      || !integer_zerop (gimple_cond_rhs (stmt)))
    return;

  stmt = SSA_NAME_DEF_STMT (gimple_cond_lhs (stmt));
  if (!is_gimple_assign (stmt)
      || gimple_assign_rhs_code (stmt) != BIT_AND_EXPR
      || TREE_CODE (gimple_assign_rhs2 (stmt)) != INTEGER_CST)
    return;
  if (gimple_assign_rhs1 (stmt) != var)
    {
      gimple *stmt2;

      if (TREE_CODE (gimple_assign_rhs1 (stmt)) != SSA_NAME)
        return;
      stmt2 = SSA_NAME_DEF_STMT (gimple_assign_rhs1 (stmt));
      if (!gimple_assign_cast_p (stmt2)
          || gimple_assign_rhs1 (stmt2) != var
          || !CONVERT_EXPR_CODE_P (gimple_assign_rhs_code (stmt2))
          || (TYPE_PRECISION (TREE_TYPE (gimple_assign_rhs1 (stmt)))
                              != TYPE_PRECISION (TREE_TYPE (var))))
        return;
    }
  cst = gimple_assign_rhs2 (stmt);
  set_nonzero_bits (var, wi::bit_and_not (get_nonzero_bits (var),
                                          wi::to_wide (cst)));
}

/* Convert range assertion expressions into the implied copies and
   copy propagate away the copies.  Doing the trivial copy propagation
   here avoids the need to run the full copy propagation pass after
   VRP.

   FIXME, this will eventually lead to copy propagation removing the
   names that had useful range information attached to them.  For
   instance, if we had the assertion N_i = ASSERT_EXPR <N_j, N_j > 3>,
   then N_i will have the range [3, +INF].

   However, by converting the assertion into the implied copy
   operation N_i = N_j, we will then copy-propagate N_j into the uses
   of N_i and lose the range information.  We may want to hold on to
   ASSERT_EXPRs a little while longer as the ranges could be used in
   things like jump threading.

   The problem with keeping ASSERT_EXPRs around is that passes after
   VRP need to handle them appropriately.

   Another approach would be to make the range information a first
   class property of the SSA_NAME so that it can be queried from
   any pass.  This is made somewhat more complex by the need for
   multiple ranges to be associated with one SSA_NAME.  */

static void
remove_range_assertions (void)
{
  basic_block bb;
  gimple_stmt_iterator si;
  /* 1 if looking at ASSERT_EXPRs immediately at the beginning of
     a basic block preceeded by GIMPLE_COND branching to it and
     __builtin_trap, -1 if not yet checked, 0 otherwise.  */
  int is_unreachable;

  /* Note that the BSI iterator bump happens at the bottom of the
     loop and no bump is necessary if we're removing the statement
     referenced by the current BSI.  */
  FOR_EACH_BB_FN (bb, cfun)
    for (si = gsi_after_labels (bb), is_unreachable = -1; !gsi_end_p (si);)
      {
        gimple *stmt = gsi_stmt (si);

        if (is_gimple_assign (stmt)
            && gimple_assign_rhs_code (stmt) == ASSERT_EXPR)
          {
            tree lhs = gimple_assign_lhs (stmt);
            tree rhs = gimple_assign_rhs1 (stmt);
            tree var;

            var = ASSERT_EXPR_VAR (rhs);

            if (TREE_CODE (var) == SSA_NAME
                && !POINTER_TYPE_P (TREE_TYPE (lhs))
                && SSA_NAME_RANGE_INFO (lhs))
              {
                if (is_unreachable == -1)
                  {
                    is_unreachable = 0;
                    if (single_pred_p (bb)
                        && assert_unreachable_fallthru_edge_p
                                                    (single_pred_edge (bb)))
                      is_unreachable = 1;
                  }
                /* Handle
                   if (x_7 >= 10 && x_7 < 20)
                     __builtin_unreachable ();
                   x_8 = ASSERT_EXPR <x_7, ...>;
                   if the only uses of x_7 are in the ASSERT_EXPR and
                   in the condition.  In that case, we can copy the
                   range info from x_8 computed in this pass also
                   for x_7.  */
                if (is_unreachable
                    && all_imm_uses_in_stmt_or_feed_cond (var, stmt,
                                                          single_pred (bb)))
                  {
                    set_range_info (var, SSA_NAME_RANGE_TYPE (lhs),
                                    SSA_NAME_RANGE_INFO (lhs)->get_min (),
                                    SSA_NAME_RANGE_INFO (lhs)->get_max ());
                    maybe_set_nonzero_bits (single_pred_edge (bb), var);
                  }
              }

            /* Propagate the RHS into every use of the LHS.  For SSA names
               also propagate abnormals as it merely restores the original
               IL in this case (an replace_uses_by would assert).  */
            if (TREE_CODE (var) == SSA_NAME)
              {
                imm_use_iterator iter;
                use_operand_p use_p;
                gimple *use_stmt;
                FOR_EACH_IMM_USE_STMT (use_stmt, iter, lhs)
                  FOR_EACH_IMM_USE_ON_STMT (use_p, iter)
                    SET_USE (use_p, var);
              }
            else
              replace_uses_by (lhs, var);

            /* And finally, remove the copy, it is not needed.  */
            gsi_remove (&si, true);
            release_defs (stmt);
          }
        else
          {
            if (!is_gimple_debug (gsi_stmt (si)))
              is_unreachable = 0;
            gsi_next (&si);
          }
      }
}

/* Return true if STMT is interesting for VRP.  */

bool
stmt_interesting_for_vrp (gimple *stmt)
{
  if (gimple_code (stmt) == GIMPLE_PHI)
    {
      tree res = gimple_phi_result (stmt);
      return (!virtual_operand_p (res)
              && (INTEGRAL_TYPE_P (TREE_TYPE (res))
                  || POINTER_TYPE_P (TREE_TYPE (res))));
    }
  else if (is_gimple_assign (stmt) || is_gimple_call (stmt))
    {
      tree lhs = gimple_get_lhs (stmt);

      /* In general, assignments with virtual operands are not useful
         for deriving ranges, with the obvious exception of calls to
         builtin functions.  */
      if (lhs && TREE_CODE (lhs) == SSA_NAME
          && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
              || POINTER_TYPE_P (TREE_TYPE (lhs)))
          && (is_gimple_call (stmt)
              || !gimple_vuse (stmt)))
        return true;
      else if (is_gimple_call (stmt) && gimple_call_internal_p (stmt))
        switch (gimple_call_internal_fn (stmt))
          {
          case IFN_ADD_OVERFLOW:
          case IFN_SUB_OVERFLOW:
          case IFN_MUL_OVERFLOW:
          case IFN_ATOMIC_COMPARE_EXCHANGE:
            /* These internal calls return _Complex integer type,
               but are interesting to VRP nevertheless.  */
            if (lhs && TREE_CODE (lhs) == SSA_NAME)
              return true;
            break;
          default:
            break;
          }
    }
  else if (gimple_code (stmt) == GIMPLE_COND
           || gimple_code (stmt) == GIMPLE_SWITCH)
    return true;

  return false;
}

/* Initialization required by ssa_propagate engine.  */

void
vrp_prop::vrp_initialize ()
{
  basic_block bb;

  FOR_EACH_BB_FN (bb, cfun)
    {
      for (gphi_iterator si = gsi_start_phis (bb); !gsi_end_p (si);
           gsi_next (&si))
        {
          gphi *phi = si.phi ();
          if (!stmt_interesting_for_vrp (phi))
            {
              tree lhs = PHI_RESULT (phi);
              set_value_range_to_varying (get_value_range (lhs));
              prop_set_simulate_again (phi, false);
            }
          else
            prop_set_simulate_again (phi, true);
        }

      for (gimple_stmt_iterator si = gsi_start_bb (bb); !gsi_end_p (si);
           gsi_next (&si))
        {
          gimple *stmt = gsi_stmt (si);

          /* If the statement is a control insn, then we do not
             want to avoid simulating the statement once.  Failure
             to do so means that those edges will never get added.  */
          if (stmt_ends_bb_p (stmt))
            prop_set_simulate_again (stmt, true);
          else if (!stmt_interesting_for_vrp (stmt))
            {
              set_defs_to_varying (stmt);
              prop_set_simulate_again (stmt, false);
            }
          else
            prop_set_simulate_again (stmt, true);
        }
    }
}

/* Searches the case label vector VEC for the index *IDX of the CASE_LABEL
   that includes the value VAL.  The search is restricted to the range
   [START_IDX, n - 1] where n is the size of VEC.

   If there is a CASE_LABEL for VAL, its index is placed in IDX and true is
   returned.

   If there is no CASE_LABEL for VAL and there is one that is larger than VAL,
   it is placed in IDX and false is returned.

   If VAL is larger than any CASE_LABEL, n is placed on IDX and false is
   returned. */

bool
find_case_label_index (gswitch *stmt, size_t start_idx, tree val, size_t *idx)
{
  size_t n = gimple_switch_num_labels (stmt);
  size_t low, high;

  /* Find case label for minimum of the value range or the next one.
     At each iteration we are searching in [low, high - 1]. */

  for (low = start_idx, high = n; high != low; )
    {
      tree t;
      int cmp;
      /* Note that i != high, so we never ask for n. */
      size_t i = (high + low) / 2;
      t = gimple_switch_label (stmt, i);

      /* Cache the result of comparing CASE_LOW and val.  */
      cmp = tree_int_cst_compare (CASE_LOW (t), val);

      if (cmp == 0)
        {
          /* Ranges cannot be empty. */
          *idx = i;
          return true;
        }
      else if (cmp > 0)
        high = i;
      else
        {
          low = i + 1;
          if (CASE_HIGH (t) != NULL
              && tree_int_cst_compare (CASE_HIGH (t), val) >= 0)
            {
              *idx = i;
              return true;
            }
        }
    }

  *idx = high;
  return false;
}

/* Searches the case label vector VEC for the range of CASE_LABELs that is used
   for values between MIN and MAX. The first index is placed in MIN_IDX. The
   last index is placed in MAX_IDX. If the range of CASE_LABELs is empty
   then MAX_IDX < MIN_IDX.
   Returns true if the default label is not needed. */

bool
find_case_label_range (gswitch *stmt, tree min, tree max, size_t *min_idx,
                       size_t *max_idx)
{
  size_t i, j;
  bool min_take_default = !find_case_label_index (stmt, 1, min, &i);
  bool max_take_default = !find_case_label_index (stmt, i, max, &j);

  if (i == j
      && min_take_default
      && max_take_default)
    {
      /* Only the default case label reached.
         Return an empty range. */
      *min_idx = 1;
      *max_idx = 0;
      return false;
    }
  else
    {
      bool take_default = min_take_default || max_take_default;
      tree low, high;
      size_t k;

      if (max_take_default)
        j--;

      /* If the case label range is continuous, we do not need
         the default case label.  Verify that.  */
      high = CASE_LOW (gimple_switch_label (stmt, i));
      if (CASE_HIGH (gimple_switch_label (stmt, i)))
        high = CASE_HIGH (gimple_switch_label (stmt, i));
      for (k = i + 1; k <= j; ++k)
        {
          low = CASE_LOW (gimple_switch_label (stmt, k));
          if (!integer_onep (int_const_binop (MINUS_EXPR, low, high)))
            {
              take_default = true;
              break;
            }
          high = low;
          if (CASE_HIGH (gimple_switch_label (stmt, k)))
            high = CASE_HIGH (gimple_switch_label (stmt, k));
        }

      *min_idx = i;
      *max_idx = j;
      return !take_default;
    }
}

/* Evaluate statement STMT.  If the statement produces a useful range,
   return SSA_PROP_INTERESTING and record the SSA name with the
   interesting range into *OUTPUT_P.

   If STMT is a conditional branch and we can determine its truth
   value, the taken edge is recorded in *TAKEN_EDGE_P.

   If STMT produces a varying value, return SSA_PROP_VARYING.  */

enum ssa_prop_result
vrp_prop::visit_stmt (gimple *stmt, edge *taken_edge_p, tree *output_p)
{
  value_range vr = VR_INITIALIZER;
  tree lhs = gimple_get_lhs (stmt);
  extract_range_from_stmt (stmt, taken_edge_p, output_p, &vr);

  if (*output_p)
    {
      if (update_value_range (*output_p, &vr))
        {
          if (dump_file && (dump_flags & TDF_DETAILS))
            {
              fprintf (dump_file, "Found new range for ");
              print_generic_expr (dump_file, *output_p);
              fprintf (dump_file, ": ");
              dump_value_range (dump_file, &vr);
              fprintf (dump_file, "\n");
            }

          if (vr.type == VR_VARYING)
            return SSA_PROP_VARYING;

          return SSA_PROP_INTERESTING;
        }
      return SSA_PROP_NOT_INTERESTING;
    }

  if (is_gimple_call (stmt) && gimple_call_internal_p (stmt))
    switch (gimple_call_internal_fn (stmt))
      {
      case IFN_ADD_OVERFLOW:
      case IFN_SUB_OVERFLOW:
      case IFN_MUL_OVERFLOW:
      case IFN_ATOMIC_COMPARE_EXCHANGE:
        /* These internal calls return _Complex integer type,
           which VRP does not track, but the immediate uses
           thereof might be interesting.  */
        if (lhs && TREE_CODE (lhs) == SSA_NAME)
          {
            imm_use_iterator iter;
            use_operand_p use_p;
            enum ssa_prop_result res = SSA_PROP_VARYING;

            set_value_range_to_varying (get_value_range (lhs));

            FOR_EACH_IMM_USE_FAST (use_p, iter, lhs)
              {
                gimple *use_stmt = USE_STMT (use_p);
                if (!is_gimple_assign (use_stmt))
                  continue;
                enum tree_code rhs_code = gimple_assign_rhs_code (use_stmt);
                if (rhs_code != REALPART_EXPR && rhs_code != IMAGPART_EXPR)
                  continue;
                tree rhs1 = gimple_assign_rhs1 (use_stmt);
                tree use_lhs = gimple_assign_lhs (use_stmt);
                if (TREE_CODE (rhs1) != rhs_code
                    || TREE_OPERAND (rhs1, 0) != lhs
                    || TREE_CODE (use_lhs) != SSA_NAME
                    || !stmt_interesting_for_vrp (use_stmt)
                    || (!INTEGRAL_TYPE_P (TREE_TYPE (use_lhs))
                        || !TYPE_MIN_VALUE (TREE_TYPE (use_lhs))
                        || !TYPE_MAX_VALUE (TREE_TYPE (use_lhs))))
                  continue;

                /* If there is a change in the value range for any of the
                   REALPART_EXPR/IMAGPART_EXPR immediate uses, return
                   SSA_PROP_INTERESTING.  If there are any REALPART_EXPR
                   or IMAGPART_EXPR immediate uses, but none of them have
                   a change in their value ranges, return
                   SSA_PROP_NOT_INTERESTING.  If there are no
                   {REAL,IMAG}PART_EXPR uses at all,
                   return SSA_PROP_VARYING.  */
                value_range new_vr = VR_INITIALIZER;
                extract_range_basic (&new_vr, use_stmt);
                const value_range *old_vr = get_value_range (use_lhs);
                if (old_vr->type != new_vr.type
                    || !vrp_operand_equal_p (old_vr->min, new_vr.min)
                    || !vrp_operand_equal_p (old_vr->max, new_vr.max)
                    || !vrp_bitmap_equal_p (old_vr->equiv, new_vr.equiv))
                  res = SSA_PROP_INTERESTING;
                else
                  res = SSA_PROP_NOT_INTERESTING;
                BITMAP_FREE (new_vr.equiv);
                if (res == SSA_PROP_INTERESTING)
                  {
                    *output_p = lhs;
                    return res;
                  }
              }

            return res;
          }
        break;
      default:
        break;
      }

  /* All other statements produce nothing of interest for VRP, so mark
     their outputs varying and prevent further simulation.  */
  set_defs_to_varying (stmt);

  return (*taken_edge_p) ? SSA_PROP_INTERESTING : SSA_PROP_VARYING;
}

/* Union the two value-ranges { *VR0TYPE, *VR0MIN, *VR0MAX } and
   { VR1TYPE, VR0MIN, VR0MAX } and store the result
   in { *VR0TYPE, *VR0MIN, *VR0MAX }.  This may not be the smallest
   possible such range.  The resulting range is not canonicalized.  */

static void
union_ranges (enum value_range_type *vr0type,
              tree *vr0min, tree *vr0max,
              enum value_range_type vr1type,
              tree vr1min, tree vr1max)
{
  bool mineq = vrp_operand_equal_p (*vr0min, vr1min);
  bool maxeq = vrp_operand_equal_p (*vr0max, vr1max);

  /* [] is vr0, () is vr1 in the following classification comments.  */
  if (mineq && maxeq)
    {
      /* [(  )] */
      if (*vr0type == vr1type)
        /* Nothing to do for equal ranges.  */
        ;
      else if ((*vr0type == VR_RANGE
                && vr1type == VR_ANTI_RANGE)
               || (*vr0type == VR_ANTI_RANGE
                   && vr1type == VR_RANGE))
        {
          /* For anti-range with range union the result is varying.  */
          goto give_up;
        }
      else
        gcc_unreachable ();
    }
  else if (operand_less_p (*vr0max, vr1min) == 1
           || operand_less_p (vr1max, *vr0min) == 1)
    {
      /* [ ] ( ) or ( ) [ ]
         If the ranges have an empty intersection, result of the union
         operation is the anti-range or if both are anti-ranges
         it covers all.  */
      if (*vr0type == VR_ANTI_RANGE
          && vr1type == VR_ANTI_RANGE)
        goto give_up;
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_RANGE)
        ;
      else if (*vr0type == VR_RANGE
               && vr1type == VR_ANTI_RANGE)
        {
          *vr0type = vr1type;
          *vr0min = vr1min;
          *vr0max = vr1max;
        }
      else if (*vr0type == VR_RANGE
               && vr1type == VR_RANGE)
        {
          /* The result is the convex hull of both ranges.  */
          if (operand_less_p (*vr0max, vr1min) == 1)
            {
              /* If the result can be an anti-range, create one.  */
              if (TREE_CODE (*vr0max) == INTEGER_CST
                  && TREE_CODE (vr1min) == INTEGER_CST
                  && vrp_val_is_min (*vr0min)
                  && vrp_val_is_max (vr1max))
                {
                  tree min = int_const_binop (PLUS_EXPR,
                                              *vr0max,
                                              build_int_cst (TREE_TYPE (*vr0max), 1));
                  tree max = int_const_binop (MINUS_EXPR,
                                              vr1min,
                                              build_int_cst (TREE_TYPE (vr1min), 1));
                  if (!operand_less_p (max, min))
                    {
                      *vr0type = VR_ANTI_RANGE;
                      *vr0min = min;
                      *vr0max = max;
                    }
                  else
                    *vr0max = vr1max;
                }
              else
                *vr0max = vr1max;
            }
          else
            {
              /* If the result can be an anti-range, create one.  */
              if (TREE_CODE (vr1max) == INTEGER_CST
                  && TREE_CODE (*vr0min) == INTEGER_CST
                  && vrp_val_is_min (vr1min)
                  && vrp_val_is_max (*vr0max))
                {
                  tree min = int_const_binop (PLUS_EXPR,
                                              vr1max,
                                              build_int_cst (TREE_TYPE (vr1max), 1));
                  tree max = int_const_binop (MINUS_EXPR,
                                              *vr0min,
                                              build_int_cst (TREE_TYPE (*vr0min), 1));
                  if (!operand_less_p (max, min))
                    {
                      *vr0type = VR_ANTI_RANGE;
                      *vr0min = min;
                      *vr0max = max;
                    }
                  else
                    *vr0min = vr1min;
                }
              else
                *vr0min = vr1min;
            }
        }
      else
        gcc_unreachable ();
    }
  else if ((maxeq || operand_less_p (vr1max, *vr0max) == 1)
           && (mineq || operand_less_p (*vr0min, vr1min) == 1))
    {
      /* [ (  ) ] or [(  ) ] or [ (  )] */
      if (*vr0type == VR_RANGE
          && vr1type == VR_RANGE)
        ;
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_ANTI_RANGE)
        {
          *vr0type = vr1type;
          *vr0min = vr1min;
          *vr0max = vr1max;
        }
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_RANGE)
        {
          /* Arbitrarily choose the right or left gap.  */
          if (!mineq && TREE_CODE (vr1min) == INTEGER_CST)
            *vr0max = int_const_binop (MINUS_EXPR, vr1min,
                                       build_int_cst (TREE_TYPE (vr1min), 1));
          else if (!maxeq && TREE_CODE (vr1max) == INTEGER_CST)
            *vr0min = int_const_binop (PLUS_EXPR, vr1max,
                                       build_int_cst (TREE_TYPE (vr1max), 1));
          else
            goto give_up;
        }
      else if (*vr0type == VR_RANGE
               && vr1type == VR_ANTI_RANGE)
        /* The result covers everything.  */
        goto give_up;
      else
        gcc_unreachable ();
    }
  else if ((maxeq || operand_less_p (*vr0max, vr1max) == 1)
           && (mineq || operand_less_p (vr1min, *vr0min) == 1))
    {
      /* ( [  ] ) or ([  ] ) or ( [  ]) */
      if (*vr0type == VR_RANGE
          && vr1type == VR_RANGE)
        {
          *vr0type = vr1type;
          *vr0min = vr1min;
          *vr0max = vr1max;
        }
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_ANTI_RANGE)
        ;
      else if (*vr0type == VR_RANGE
               && vr1type == VR_ANTI_RANGE)
        {
          *vr0type = VR_ANTI_RANGE;
          if (!mineq && TREE_CODE (*vr0min) == INTEGER_CST)
            {
              *vr0max = int_const_binop (MINUS_EXPR, *vr0min,
                                         build_int_cst (TREE_TYPE (*vr0min), 1));
              *vr0min = vr1min;
            }
          else if (!maxeq && TREE_CODE (*vr0max) == INTEGER_CST)
            {
              *vr0min = int_const_binop (PLUS_EXPR, *vr0max,
                                         build_int_cst (TREE_TYPE (*vr0max), 1));
              *vr0max = vr1max;
            }
          else
            goto give_up;
        }
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_RANGE)
        /* The result covers everything.  */
        goto give_up;
      else
        gcc_unreachable ();
    }
  else if ((operand_less_p (vr1min, *vr0max) == 1
            || operand_equal_p (vr1min, *vr0max, 0))
           && operand_less_p (*vr0min, vr1min) == 1
           && operand_less_p (*vr0max, vr1max) == 1)
    {
      /* [  (  ]  ) or [   ](   ) */
      if (*vr0type == VR_RANGE
          && vr1type == VR_RANGE)
        *vr0max = vr1max;
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_ANTI_RANGE)
        *vr0min = vr1min;
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_RANGE)
        {
          if (TREE_CODE (vr1min) == INTEGER_CST)
            *vr0max = int_const_binop (MINUS_EXPR, vr1min,
                                       build_int_cst (TREE_TYPE (vr1min), 1));
          else
            goto give_up;
        }
      else if (*vr0type == VR_RANGE
               && vr1type == VR_ANTI_RANGE)
        {
          if (TREE_CODE (*vr0max) == INTEGER_CST)
            {
              *vr0type = vr1type;
              *vr0min = int_const_binop (PLUS_EXPR, *vr0max,
                                         build_int_cst (TREE_TYPE (*vr0max), 1));
              *vr0max = vr1max;
            }
          else
            goto give_up;
        }
      else
        gcc_unreachable ();
    }
  else if ((operand_less_p (*vr0min, vr1max) == 1
            || operand_equal_p (*vr0min, vr1max, 0))
           && operand_less_p (vr1min, *vr0min) == 1
           && operand_less_p (vr1max, *vr0max) == 1)
    {
      /* (  [  )  ] or (   )[   ] */
      if (*vr0type == VR_RANGE
          && vr1type == VR_RANGE)
        *vr0min = vr1min;
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_ANTI_RANGE)
        *vr0max = vr1max;
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_RANGE)
        {
          if (TREE_CODE (vr1max) == INTEGER_CST)
            *vr0min = int_const_binop (PLUS_EXPR, vr1max,
                                       build_int_cst (TREE_TYPE (vr1max), 1));
          else
            goto give_up;
        }
      else if (*vr0type == VR_RANGE
               && vr1type == VR_ANTI_RANGE)
        {
          if (TREE_CODE (*vr0min) == INTEGER_CST)
            {
              *vr0type = vr1type;
              *vr0max = int_const_binop (MINUS_EXPR, *vr0min,
                                         build_int_cst (TREE_TYPE (*vr0min), 1));
              *vr0min = vr1min;
            }
          else
            goto give_up;
        }
      else
        gcc_unreachable ();
    }
  else
    goto give_up;

  return;

give_up:
  *vr0type = VR_VARYING;
  *vr0min = NULL_TREE;
  *vr0max = NULL_TREE;
}

/* Intersect the two value-ranges { *VR0TYPE, *VR0MIN, *VR0MAX } and
   { VR1TYPE, VR0MIN, VR0MAX } and store the result
   in { *VR0TYPE, *VR0MIN, *VR0MAX }.  This may not be the smallest
   possible such range.  The resulting range is not canonicalized.  */

static void
intersect_ranges (enum value_range_type *vr0type,
                  tree *vr0min, tree *vr0max,
                  enum value_range_type vr1type,
                  tree vr1min, tree vr1max)
{
  bool mineq = vrp_operand_equal_p (*vr0min, vr1min);
  bool maxeq = vrp_operand_equal_p (*vr0max, vr1max);

  /* [] is vr0, () is vr1 in the following classification comments.  */
  if (mineq && maxeq)
    {
      /* [(  )] */
      if (*vr0type == vr1type)
        /* Nothing to do for equal ranges.  */
        ;
      else if ((*vr0type == VR_RANGE
                && vr1type == VR_ANTI_RANGE)
               || (*vr0type == VR_ANTI_RANGE
                   && vr1type == VR_RANGE))
        {
          /* For anti-range with range intersection the result is empty.  */
          *vr0type = VR_UNDEFINED;
          *vr0min = NULL_TREE;
          *vr0max = NULL_TREE;
        }
      else
        gcc_unreachable ();
    }
  else if (operand_less_p (*vr0max, vr1min) == 1
           || operand_less_p (vr1max, *vr0min) == 1)
    {
      /* [ ] ( ) or ( ) [ ]
         If the ranges have an empty intersection, the result of the
         intersect operation is the range for intersecting an
         anti-range with a range or empty when intersecting two ranges.  */
      if (*vr0type == VR_RANGE
          && vr1type == VR_ANTI_RANGE)
        ;
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_RANGE)
        {
          *vr0type = vr1type;
          *vr0min = vr1min;
          *vr0max = vr1max;
        }
      else if (*vr0type == VR_RANGE
               && vr1type == VR_RANGE)
        {
          *vr0type = VR_UNDEFINED;
          *vr0min = NULL_TREE;
          *vr0max = NULL_TREE;
        }
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_ANTI_RANGE)
        {
          /* If the anti-ranges are adjacent to each other merge them.  */
          if (TREE_CODE (*vr0max) == INTEGER_CST
              && TREE_CODE (vr1min) == INTEGER_CST
              && operand_less_p (*vr0max, vr1min) == 1
              && integer_onep (int_const_binop (MINUS_EXPR,
                                                vr1min, *vr0max)))
            *vr0max = vr1max;
          else if (TREE_CODE (vr1max) == INTEGER_CST
                   && TREE_CODE (*vr0min) == INTEGER_CST
                   && operand_less_p (vr1max, *vr0min) == 1
                   && integer_onep (int_const_binop (MINUS_EXPR,
                                                     *vr0min, vr1max)))
            *vr0min = vr1min;
          /* Else arbitrarily take VR0.  */
        }
    }
  else if ((maxeq || operand_less_p (vr1max, *vr0max) == 1)
           && (mineq || operand_less_p (*vr0min, vr1min) == 1))
    {
      /* [ (  ) ] or [(  ) ] or [ (  )] */
      if (*vr0type == VR_RANGE
          && vr1type == VR_RANGE)
        {
          /* If both are ranges the result is the inner one.  */
          *vr0type = vr1type;
          *vr0min = vr1min;
          *vr0max = vr1max;
        }
      else if (*vr0type == VR_RANGE
               && vr1type == VR_ANTI_RANGE)
        {
          /* Choose the right gap if the left one is empty.  */
          if (mineq)
            {
              if (TREE_CODE (vr1max) != INTEGER_CST)
                *vr0min = vr1max;
              else if (TYPE_PRECISION (TREE_TYPE (vr1max)) == 1
                       && !TYPE_UNSIGNED (TREE_TYPE (vr1max)))
                *vr0min
                  = int_const_binop (MINUS_EXPR, vr1max,
                                     build_int_cst (TREE_TYPE (vr1max), -1));
              else
                *vr0min
                  = int_const_binop (PLUS_EXPR, vr1max,
                                     build_int_cst (TREE_TYPE (vr1max), 1));
            }
          /* Choose the left gap if the right one is empty.  */
          else if (maxeq)
            {
              if (TREE_CODE (vr1min) != INTEGER_CST)
                *vr0max = vr1min;
              else if (TYPE_PRECISION (TREE_TYPE (vr1min)) == 1
                       && !TYPE_UNSIGNED (TREE_TYPE (vr1min)))
                *vr0max
                  = int_const_binop (PLUS_EXPR, vr1min,
                                     build_int_cst (TREE_TYPE (vr1min), -1));
              else
                *vr0max
                  = int_const_binop (MINUS_EXPR, vr1min,
                                     build_int_cst (TREE_TYPE (vr1min), 1));
            }
          /* Choose the anti-range if the range is effectively varying.  */
          else if (vrp_val_is_min (*vr0min)
                   && vrp_val_is_max (*vr0max))
            {
              *vr0type = vr1type;
              *vr0min = vr1min;
              *vr0max = vr1max;
            }
          /* Else choose the range.  */
        }
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_ANTI_RANGE)
        /* If both are anti-ranges the result is the outer one.  */
        ;
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_RANGE)
        {
          /* The intersection is empty.  */
          *vr0type = VR_UNDEFINED;
          *vr0min = NULL_TREE;
          *vr0max = NULL_TREE;
        }
      else
        gcc_unreachable ();
    }
  else if ((maxeq || operand_less_p (*vr0max, vr1max) == 1)
           && (mineq || operand_less_p (vr1min, *vr0min) == 1))
    {
      /* ( [  ] ) or ([  ] ) or ( [  ]) */
      if (*vr0type == VR_RANGE
          && vr1type == VR_RANGE)
        /* Choose the inner range.  */
        ;
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_RANGE)
        {
          /* Choose the right gap if the left is empty.  */
          if (mineq)
            {
              *vr0type = VR_RANGE;
              if (TREE_CODE (*vr0max) != INTEGER_CST)
                *vr0min = *vr0max;
              else if (TYPE_PRECISION (TREE_TYPE (*vr0max)) == 1
                       && !TYPE_UNSIGNED (TREE_TYPE (*vr0max)))
                *vr0min
                  = int_const_binop (MINUS_EXPR, *vr0max,
                                     build_int_cst (TREE_TYPE (*vr0max), -1));
              else
                *vr0min
                  = int_const_binop (PLUS_EXPR, *vr0max,
                                     build_int_cst (TREE_TYPE (*vr0max), 1));
              *vr0max = vr1max;
            }
          /* Choose the left gap if the right is empty.  */
          else if (maxeq)
            {
              *vr0type = VR_RANGE;
              if (TREE_CODE (*vr0min) != INTEGER_CST)
                *vr0max = *vr0min;
              else if (TYPE_PRECISION (TREE_TYPE (*vr0min)) == 1
                       && !TYPE_UNSIGNED (TREE_TYPE (*vr0min)))
                *vr0max
                  = int_const_binop (PLUS_EXPR, *vr0min,
                                     build_int_cst (TREE_TYPE (*vr0min), -1));
              else
                *vr0max
                  = int_const_binop (MINUS_EXPR, *vr0min,
                                     build_int_cst (TREE_TYPE (*vr0min), 1));
              *vr0min = vr1min;
            }
          /* Choose the anti-range if the range is effectively varying.  */
          else if (vrp_val_is_min (vr1min)
                   && vrp_val_is_max (vr1max))
            ;
          /* Choose the anti-range if it is ~[0,0], that range is special
             enough to special case when vr1's range is relatively wide.
             At least for types bigger than int - this covers pointers
             and arguments to functions like ctz.  */
          else if (*vr0min == *vr0max
                   && integer_zerop (*vr0min)
                   && ((TYPE_PRECISION (TREE_TYPE (*vr0min))
                        >= TYPE_PRECISION (integer_type_node))
                       || POINTER_TYPE_P (TREE_TYPE (*vr0min)))
                   && TREE_CODE (vr1max) == INTEGER_CST
                   && TREE_CODE (vr1min) == INTEGER_CST
                   && (wi::clz (wi::to_wide (vr1max) - wi::to_wide (vr1min))
                       < TYPE_PRECISION (TREE_TYPE (*vr0min)) / 2))
            ;
          /* Else choose the range.  */
          else
            {
              *vr0type = vr1type;
              *vr0min = vr1min;
              *vr0max = vr1max;
            }
        }
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_ANTI_RANGE)
        {
          /* If both are anti-ranges the result is the outer one.  */
          *vr0type = vr1type;
          *vr0min = vr1min;
          *vr0max = vr1max;
        }
      else if (vr1type == VR_ANTI_RANGE
               && *vr0type == VR_RANGE)
        {
          /* The intersection is empty.  */
          *vr0type = VR_UNDEFINED;
          *vr0min = NULL_TREE;
          *vr0max = NULL_TREE;
        }
      else
        gcc_unreachable ();
    }
  else if ((operand_less_p (vr1min, *vr0max) == 1
            || operand_equal_p (vr1min, *vr0max, 0))
           && operand_less_p (*vr0min, vr1min) == 1)
    {
      /* [  (  ]  ) or [  ](  ) */
      if (*vr0type == VR_ANTI_RANGE
          && vr1type == VR_ANTI_RANGE)
        *vr0max = vr1max;
      else if (*vr0type == VR_RANGE
               && vr1type == VR_RANGE)
        *vr0min = vr1min;
      else if (*vr0type == VR_RANGE
               && vr1type == VR_ANTI_RANGE)
        {
          if (TREE_CODE (vr1min) == INTEGER_CST)
            *vr0max = int_const_binop (MINUS_EXPR, vr1min,
                                       build_int_cst (TREE_TYPE (vr1min), 1));
          else
            *vr0max = vr1min;
        }
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_RANGE)
        {
          *vr0type = VR_RANGE;
          if (TREE_CODE (*vr0max) == INTEGER_CST)
            *vr0min = int_const_binop (PLUS_EXPR, *vr0max,
                                       build_int_cst (TREE_TYPE (*vr0max), 1));
          else
            *vr0min = *vr0max;
          *vr0max = vr1max;
        }
      else
        gcc_unreachable ();
    }
  else if ((operand_less_p (*vr0min, vr1max) == 1
            || operand_equal_p (*vr0min, vr1max, 0))
           && operand_less_p (vr1min, *vr0min) == 1)
    {
      /* (  [  )  ] or (  )[  ] */
      if (*vr0type == VR_ANTI_RANGE
          && vr1type == VR_ANTI_RANGE)
        *vr0min = vr1min;
      else if (*vr0type == VR_RANGE
               && vr1type == VR_RANGE)
        *vr0max = vr1max;
      else if (*vr0type == VR_RANGE
               && vr1type == VR_ANTI_RANGE)
        {
          if (TREE_CODE (vr1max) == INTEGER_CST)
            *vr0min = int_const_binop (PLUS_EXPR, vr1max,
                                       build_int_cst (TREE_TYPE (vr1max), 1));
          else
            *vr0min = vr1max;
        }
      else if (*vr0type == VR_ANTI_RANGE
               && vr1type == VR_RANGE)
        {
          *vr0type = VR_RANGE;
          if (TREE_CODE (*vr0min) == INTEGER_CST)
            *vr0max = int_const_binop (MINUS_EXPR, *vr0min,
                                       build_int_cst (TREE_TYPE (*vr0min), 1));
          else
            *vr0max = *vr0min;
          *vr0min = vr1min;
        }
      else
        gcc_unreachable ();
    }

  /* As a fallback simply use { *VRTYPE, *VR0MIN, *VR0MAX } as
     result for the intersection.  That's always a conservative
     correct estimate unless VR1 is a constant singleton range
     in which case we choose that.  */
  if (vr1type == VR_RANGE
      && is_gimple_min_invariant (vr1min)
      && vrp_operand_equal_p (vr1min, vr1max))
    {
      *vr0type = vr1type;
      *vr0min = vr1min;
      *vr0max = vr1max;
    }

  return;
}


/* Intersect the two value-ranges *VR0 and *VR1 and store the result
   in *VR0.  This may not be the smallest possible such range.  */

static void
vrp_intersect_ranges_1 (value_range *vr0, const value_range *vr1)
{
  value_range saved;

  /* If either range is VR_VARYING the other one wins.  */
  if (vr1->type == VR_VARYING)
    return;
  if (vr0->type == VR_VARYING)
    {
      copy_value_range (vr0, vr1);
      return;
    }

  /* When either range is VR_UNDEFINED the resulting range is
     VR_UNDEFINED, too.  */
  if (vr0->type == VR_UNDEFINED)
    return;
  if (vr1->type == VR_UNDEFINED)
    {
      set_value_range_to_undefined (vr0);
      return;
    }

  /* Save the original vr0 so we can return it as conservative intersection
     result when our worker turns things to varying.  */
  saved = *vr0;
  intersect_ranges (&vr0->type, &vr0->min, &vr0->max,
                    vr1->type, vr1->min, vr1->max);
  /* Make sure to canonicalize the result though as the inversion of a
     VR_RANGE can still be a VR_RANGE.  */
  set_and_canonicalize_value_range (vr0, vr0->type,
                                    vr0->min, vr0->max, vr0->equiv);
  /* If that failed, use the saved original VR0.  */
  if (vr0->type == VR_VARYING)
    {
      *vr0 = saved;
      return;
    }
  /* If the result is VR_UNDEFINED there is no need to mess with
     the equivalencies.  */
  if (vr0->type == VR_UNDEFINED)
    return;

  /* The resulting set of equivalences for range intersection is the union of
     the two sets.  */
  if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
    bitmap_ior_into (vr0->equiv, vr1->equiv);
  else if (vr1->equiv && !vr0->equiv)
    {
      /* All equivalence bitmaps are allocated from the same obstack.  So
         we can use the obstack associated with VR to allocate vr0->equiv.  */
      vr0->equiv = BITMAP_ALLOC (vr1->equiv->obstack);
      bitmap_copy (vr0->equiv, vr1->equiv);
    }
}

void
vrp_intersect_ranges (value_range *vr0, const value_range *vr1)
{
  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "Intersecting\n  ");
      dump_value_range (dump_file, vr0);
      fprintf (dump_file, "\nand\n  ");
      dump_value_range (dump_file, vr1);
      fprintf (dump_file, "\n");
    }
  vrp_intersect_ranges_1 (vr0, vr1);
  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "to\n  ");
      dump_value_range (dump_file, vr0);
      fprintf (dump_file, "\n");
    }
}

/* Meet operation for value ranges.  Given two value ranges VR0 and
   VR1, store in VR0 a range that contains both VR0 and VR1.  This
   may not be the smallest possible such range.  */

static void
vrp_meet_1 (value_range *vr0, const value_range *vr1)
{
  value_range saved;

  if (vr0->type == VR_UNDEFINED)
    {
      set_value_range (vr0, vr1->type, vr1->min, vr1->max, vr1->equiv);
      return;
    }

  if (vr1->type == VR_UNDEFINED)
    {
      /* VR0 already has the resulting range.  */
      return;
    }

  if (vr0->type == VR_VARYING)
    {
      /* Nothing to do.  VR0 already has the resulting range.  */
      return;
    }

  if (vr1->type == VR_VARYING)
    {
      set_value_range_to_varying (vr0);
      return;
    }

  saved = *vr0;
  union_ranges (&vr0->type, &vr0->min, &vr0->max,
                vr1->type, vr1->min, vr1->max);
  if (vr0->type == VR_VARYING)
    {
      /* Failed to find an efficient meet.  Before giving up and setting
         the result to VARYING, see if we can at least derive a useful
         anti-range.  */
      if (range_includes_zero_p (&saved) == 0
          && range_includes_zero_p (vr1) == 0)
        {
          set_value_range_to_nonnull (vr0, TREE_TYPE (saved.min));

          /* Since this meet operation did not result from the meeting of
             two equivalent names, VR0 cannot have any equivalences.  */
          if (vr0->equiv)
            bitmap_clear (vr0->equiv);
          return;
        }

      set_value_range_to_varying (vr0);
      return;
    }
  set_and_canonicalize_value_range (vr0, vr0->type, vr0->min, vr0->max,
                                    vr0->equiv);
  if (vr0->type == VR_VARYING)
    return;

  /* The resulting set of equivalences is always the intersection of
     the two sets.  */
  if (vr0->equiv && vr1->equiv && vr0->equiv != vr1->equiv)
    bitmap_and_into (vr0->equiv, vr1->equiv);
  else if (vr0->equiv && !vr1->equiv)
    bitmap_clear (vr0->equiv);
}

void
vrp_meet (value_range *vr0, const value_range *vr1)
{
  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "Meeting\n  ");
      dump_value_range (dump_file, vr0);
      fprintf (dump_file, "\nand\n  ");
      dump_value_range (dump_file, vr1);
      fprintf (dump_file, "\n");
    }
  vrp_meet_1 (vr0, vr1);
  if (dump_file && (dump_flags & TDF_DETAILS))
    {
      fprintf (dump_file, "to\n  ");
      dump_value_range (dump_file, vr0);
      fprintf (dump_file, "\n");
    }
}


/* Visit all arguments for PHI node PHI that flow through executable
   edges.  If a valid value range can be derived from all the incoming
   value ranges, set a new range for the LHS of PHI.  */

enum ssa_prop_result
vrp_prop::visit_phi (gphi *phi)
{
  tree lhs = PHI_RESULT (phi);
  value_range vr_result = VR_INITIALIZER;
  extract_range_from_phi_node (phi, &vr_result);
  if (update_value_range (lhs, &vr_result))
    {
      if (dump_file && (dump_flags & TDF_DETAILS))
        {
          fprintf (dump_file, "Found new range for ");
          print_generic_expr (dump_file, lhs);
          fprintf (dump_file, ": ");
          dump_value_range (dump_file, &vr_result);
          fprintf (dump_file, "\n");
        }

      if (vr_result.type == VR_VARYING)
        return SSA_PROP_VARYING;

      return SSA_PROP_INTERESTING;
    }

  /* Nothing changed, don't add outgoing edges.  */
  return SSA_PROP_NOT_INTERESTING;
}

class vrp_folder : public substitute_and_fold_engine
{
 public:
  tree get_value (tree) FINAL OVERRIDE;
  bool fold_stmt (gimple_stmt_iterator *) FINAL OVERRIDE;
  bool fold_predicate_in (gimple_stmt_iterator *);

  class vr_values *vr_values;

  /* Delegators.  */
  tree vrp_evaluate_conditional (tree_code code, tree op0,
                                 tree op1, gimple *stmt)
    { return vr_values->vrp_evaluate_conditional (code, op0, op1, stmt); }
  bool simplify_stmt_using_ranges (gimple_stmt_iterator *gsi)
    { return vr_values->simplify_stmt_using_ranges (gsi); }
 tree op_with_constant_singleton_value_range (tree op)
    { return vr_values->op_with_constant_singleton_value_range (op); }
};

/* If the statement pointed by SI has a predicate whose value can be
   computed using the value range information computed by VRP, compute
   its value and return true.  Otherwise, return false.  */

bool
vrp_folder::fold_predicate_in (gimple_stmt_iterator *si)
{
  bool assignment_p = false;
  tree val;
  gimple *stmt = gsi_stmt (*si);

  if (is_gimple_assign (stmt)
      && TREE_CODE_CLASS (gimple_assign_rhs_code (stmt)) == tcc_comparison)
    {
      assignment_p = true;
      val = vrp_evaluate_conditional (gimple_assign_rhs_code (stmt),
                                      gimple_assign_rhs1 (stmt),
                                      gimple_assign_rhs2 (stmt),
                                      stmt);
    }
  else if (gcond *cond_stmt = dyn_cast <gcond *> (stmt))
    val = vrp_evaluate_conditional (gimple_cond_code (cond_stmt),
                                    gimple_cond_lhs (cond_stmt),
                                    gimple_cond_rhs (cond_stmt),
                                    stmt);
  else
    return false;

  if (val)
    {
      if (assignment_p)
        val = fold_convert (gimple_expr_type (stmt), val);

      if (dump_file)
        {
          fprintf (dump_file, "Folding predicate ");
          print_gimple_expr (dump_file, stmt, 0);
          fprintf (dump_file, " to ");
          print_generic_expr (dump_file, val);
          fprintf (dump_file, "\n");
        }

      if (is_gimple_assign (stmt))
        gimple_assign_set_rhs_from_tree (si, val);
      else
        {
          gcc_assert (gimple_code (stmt) == GIMPLE_COND);
          gcond *cond_stmt = as_a <gcond *> (stmt);
          if (integer_zerop (val))
            gimple_cond_make_false (cond_stmt);
          else if (integer_onep (val))
            gimple_cond_make_true (cond_stmt);
          else
            gcc_unreachable ();
        }

      return true;
    }

  return false;
}

/* Callback for substitute_and_fold folding the stmt at *SI.  */

bool
vrp_folder::fold_stmt (gimple_stmt_iterator *si)
{
  if (fold_predicate_in (si))
    return true;

  return simplify_stmt_using_ranges (si);
}

/* If OP has a value range with a single constant value return that,
   otherwise return NULL_TREE.  This returns OP itself if OP is a
   constant.

   Implemented as a pure wrapper right now, but this will change.  */

tree
vrp_folder::get_value (tree op)
{
  return op_with_constant_singleton_value_range (op);
}

/* Return the LHS of any ASSERT_EXPR where OP appears as the first
   argument to the ASSERT_EXPR and in which the ASSERT_EXPR dominates
   BB.  If no such ASSERT_EXPR is found, return OP.  */

static tree
lhs_of_dominating_assert (tree op, basic_block bb, gimple *stmt)
{
  imm_use_iterator imm_iter;
  gimple *use_stmt;
  use_operand_p use_p;

  if (TREE_CODE (op) == SSA_NAME)
    {
      FOR_EACH_IMM_USE_FAST (use_p, imm_iter, op)
        {
          use_stmt = USE_STMT (use_p);
          if (use_stmt != stmt
              && gimple_assign_single_p (use_stmt)
              && TREE_CODE (gimple_assign_rhs1 (use_stmt)) == ASSERT_EXPR
              && TREE_OPERAND (gimple_assign_rhs1 (use_stmt), 0) == op
              && dominated_by_p (CDI_DOMINATORS, bb, gimple_bb (use_stmt)))
            return gimple_assign_lhs (use_stmt);
        }
    }
  return op;
}

/* A hack.  */
static class vr_values *x_vr_values;

/* A trivial wrapper so that we can present the generic jump threading
   code with a simple API for simplifying statements.  STMT is the
   statement we want to simplify, WITHIN_STMT provides the location
   for any overflow warnings.  */

static tree
simplify_stmt_for_jump_threading (gimple *stmt, gimple *within_stmt,
    class avail_exprs_stack *avail_exprs_stack ATTRIBUTE_UNUSED,
    basic_block bb)
{
  /* First see if the conditional is in the hash table.  */
  tree cached_lhs = avail_exprs_stack->lookup_avail_expr (stmt, false, true);
  if (cached_lhs && is_gimple_min_invariant (cached_lhs))
    return cached_lhs;

  vr_values *vr_values = x_vr_values;
  if (gcond *cond_stmt = dyn_cast <gcond *> (stmt))
    {
      tree op0 = gimple_cond_lhs (cond_stmt);
      op0 = lhs_of_dominating_assert (op0, bb, stmt);

      tree op1 = gimple_cond_rhs (cond_stmt);
      op1 = lhs_of_dominating_assert (op1, bb, stmt);

      return vr_values->vrp_evaluate_conditional (gimple_cond_code (cond_stmt),
                                                  op0, op1, within_stmt);
    }

  /* We simplify a switch statement by trying to determine which case label
     will be taken.  If we are successful then we return the corresponding
     CASE_LABEL_EXPR.  */
  if (gswitch *switch_stmt = dyn_cast <gswitch *> (stmt))
    {
      tree op = gimple_switch_index (switch_stmt);
      if (TREE_CODE (op) != SSA_NAME)
        return NULL_TREE;

      op = lhs_of_dominating_assert (op, bb, stmt);

      const value_range *vr = vr_values->get_value_range (op);
      if ((vr->type != VR_RANGE && vr->type != VR_ANTI_RANGE)
          || symbolic_range_p (vr))
        return NULL_TREE;

      if (vr->type == VR_RANGE)
        {
          size_t i, j;
          /* Get the range of labels that contain a part of the operand's
             value range.  */
          find_case_label_range (switch_stmt, vr->min, vr->max, &i, &j);

          /* Is there only one such label?  */
          if (i == j)
            {
              tree label = gimple_switch_label (switch_stmt, i);

              /* The i'th label will be taken only if the value range of the
                 operand is entirely within the bounds of this label.  */
              if (CASE_HIGH (label) != NULL_TREE
                  ? (tree_int_cst_compare (CASE_LOW (label), vr->min) <= 0
                     && tree_int_cst_compare (CASE_HIGH (label), vr->max) >= 0)
                  : (tree_int_cst_equal (CASE_LOW (label), vr->min)
                     && tree_int_cst_equal (vr->min, vr->max)))
                return label;
            }

          /* If there are no such labels then the default label will be
             taken.  */
          if (i > j)
            return gimple_switch_label (switch_stmt, 0);
        }

      if (vr->type == VR_ANTI_RANGE)
        {
          unsigned n = gimple_switch_num_labels (switch_stmt);
          tree min_label = gimple_switch_label (switch_stmt, 1);
          tree max_label = gimple_switch_label (switch_stmt, n - 1);

          /* The default label will be taken only if the anti-range of the
             operand is entirely outside the bounds of all the (non-default)
             case labels.  */
          if (tree_int_cst_compare (vr->min, CASE_LOW (min_label)) <= 0
              && (CASE_HIGH (max_label) != NULL_TREE
                  ? tree_int_cst_compare (vr->max, CASE_HIGH (max_label)) >= 0
                  : tree_int_cst_compare (vr->max, CASE_LOW (max_label)) >= 0))
          return gimple_switch_label (switch_stmt, 0);
        }

      return NULL_TREE;
    }

  if (gassign *assign_stmt = dyn_cast <gassign *> (stmt))
    {
      tree lhs = gimple_assign_lhs (assign_stmt);
      if (TREE_CODE (lhs) == SSA_NAME
          && (INTEGRAL_TYPE_P (TREE_TYPE (lhs))
              || POINTER_TYPE_P (TREE_TYPE (lhs)))
          && stmt_interesting_for_vrp (stmt))
        {
          edge dummy_e;
          tree dummy_tree;
          value_range new_vr = VR_INITIALIZER;
          vr_values->extract_range_from_stmt (stmt, &dummy_e,
                                              &dummy_tree, &new_vr);
          if (range_int_cst_singleton_p (&new_vr))
            return new_vr.min;
        }
    }

  return NULL_TREE;
}

class vrp_dom_walker : public dom_walker
{
public:
  vrp_dom_walker (cdi_direction direction,
                  class const_and_copies *const_and_copies,
                  class avail_exprs_stack *avail_exprs_stack)
    : dom_walker (direction, REACHABLE_BLOCKS),
      m_const_and_copies (const_and_copies),
      m_avail_exprs_stack (avail_exprs_stack),
      m_dummy_cond (NULL) {}

  virtual edge before_dom_children (basic_block);
  virtual void after_dom_children (basic_block);

  class vr_values *vr_values;

private:
  class const_and_copies *m_const_and_copies;
  class avail_exprs_stack *m_avail_exprs_stack;

  gcond *m_dummy_cond;

};

/* Called before processing dominator children of BB.  We want to look
   at ASSERT_EXPRs and record information from them in the appropriate
   tables.

   We could look at other statements here.  It's not seen as likely
   to significantly increase the jump threads we discover.  */

edge
vrp_dom_walker::before_dom_children (basic_block bb)
{
  gimple_stmt_iterator gsi;

  m_avail_exprs_stack->push_marker ();
  m_const_and_copies->push_marker ();
  for (gsi = gsi_start_nondebug_bb (bb); !gsi_end_p (gsi); gsi_next (&gsi))
    {
      gimple *stmt = gsi_stmt (gsi);
      if (gimple_assign_single_p (stmt)
         && TREE_CODE (gimple_assign_rhs1 (stmt)) == ASSERT_EXPR)
        {
          tree rhs1 = gimple_assign_rhs1 (stmt);
          tree cond = TREE_OPERAND (rhs1, 1);
          tree inverted = invert_truthvalue (cond);
          vec<cond_equivalence> p;
          p.create (3);
          record_conditions (&p, cond, inverted);
          for (unsigned int i = 0; i < p.length (); i++)
            m_avail_exprs_stack->record_cond (&p[i]);

          tree lhs = gimple_assign_lhs (stmt);
          m_const_and_copies->record_const_or_copy (lhs,
                                                    TREE_OPERAND (rhs1, 0));
          p.release ();
          continue;
        }
      break;
    }
  return NULL;
}

/* Called after processing dominator children of BB.  This is where we
   actually call into the threader.  */
void
vrp_dom_walker::after_dom_children (basic_block bb)
{
  if (!m_dummy_cond)
    m_dummy_cond = gimple_build_cond (NE_EXPR,
                                      integer_zero_node, integer_zero_node,
                                      NULL, NULL);

  x_vr_values = vr_values;
  thread_outgoing_edges (bb, m_dummy_cond, m_const_and_copies,
                         m_avail_exprs_stack, NULL,
                         simplify_stmt_for_jump_threading);
  x_vr_values = NULL;

  m_avail_exprs_stack->pop_to_marker ();
  m_const_and_copies->pop_to_marker ();
}

/* Blocks which have more than one predecessor and more than
   one successor present jump threading opportunities, i.e.,
   when the block is reached from a specific predecessor, we
   may be able to determine which of the outgoing edges will
   be traversed.  When this optimization applies, we are able
   to avoid conditionals at runtime and we may expose secondary
   optimization opportunities.

   This routine is effectively a driver for the generic jump
   threading code.  It basically just presents the generic code
   with edges that may be suitable for jump threading.

   Unlike DOM, we do not iterate VRP if jump threading was successful.
   While iterating may expose new opportunities for VRP, it is expected
   those opportunities would be very limited and the compile time cost
   to expose those opportunities would be significant.

   As jump threading opportunities are discovered, they are registered
   for later realization.  */

static void
identify_jump_threads (class vr_values *vr_values)
{
  /* Ugh.  When substituting values earlier in this pass we can
     wipe the dominance information.  So rebuild the dominator
     information as we need it within the jump threading code.  */
  calculate_dominance_info (CDI_DOMINATORS);

  /* We do not allow VRP information to be used for jump threading
     across a back edge in the CFG.  Otherwise it becomes too
     difficult to avoid eliminating loop exit tests.  Of course
     EDGE_DFS_BACK is not accurate at this time so we have to
     recompute it.  */
  mark_dfs_back_edges ();

  /* Allocate our unwinder stack to unwind any temporary equivalences
     that might be recorded.  */
  const_and_copies *equiv_stack = new const_and_copies ();

  hash_table<expr_elt_hasher> *avail_exprs
    = new hash_table<expr_elt_hasher> (1024);
  avail_exprs_stack *avail_exprs_stack
    = new class avail_exprs_stack (avail_exprs);

  vrp_dom_walker walker (CDI_DOMINATORS, equiv_stack, avail_exprs_stack);
  walker.vr_values = vr_values;
  walker.walk (cfun->cfg->x_entry_block_ptr);

  /* We do not actually update the CFG or SSA graphs at this point as
     ASSERT_EXPRs are still in the IL and cfg cleanup code does not yet
     handle ASSERT_EXPRs gracefully.  */
  delete equiv_stack;
  delete avail_exprs;
  delete avail_exprs_stack;
}

/* Traverse all the blocks folding conditionals with known ranges.  */

void
vrp_prop::vrp_finalize (bool warn_array_bounds_p)
{
  size_t i;

  /* We have completed propagating through the lattice.  */
  vr_values.set_lattice_propagation_complete ();

  if (dump_file)
    {
      fprintf (dump_file, "\nValue ranges after VRP:\n\n");
      vr_values.dump_all_value_ranges (dump_file);
      fprintf (dump_file, "\n");
    }

  /* Set value range to non pointer SSA_NAMEs.  */
  for (i = 0; i < num_ssa_names; i++)
    {
      tree name = ssa_name (i);
      if (!name)
        continue;

      const value_range *vr = get_value_range (name);
      if (!name
          || (vr->type == VR_VARYING)
          || (vr->type == VR_UNDEFINED)
          || (TREE_CODE (vr->min) != INTEGER_CST)
          || (TREE_CODE (vr->max) != INTEGER_CST))
        continue;

      if (POINTER_TYPE_P (TREE_TYPE (name))
          && range_includes_zero_p (vr) == 0)
        set_ptr_nonnull (name);
      else if (!POINTER_TYPE_P (TREE_TYPE (name)))
        set_range_info (name, vr->type,
                        wi::to_wide (vr->min),
                        wi::to_wide (vr->max));
    }

  /* If we're checking array refs, we want to merge information on
     the executability of each edge between vrp_folder and the
     check_array_bounds_dom_walker: each can clear the
     EDGE_EXECUTABLE flag on edges, in different ways.

     Hence, if we're going to call check_all_array_refs, set
     the flag on every edge now, rather than in
     check_array_bounds_dom_walker's ctor; vrp_folder may clear
     it from some edges.  */
  if (warn_array_bounds && warn_array_bounds_p)
    set_all_edges_as_executable (cfun);

  class vrp_folder vrp_folder;
  vrp_folder.vr_values = &vr_values;
  vrp_folder.substitute_and_fold ();

  if (warn_array_bounds && warn_array_bounds_p)
    check_all_array_refs ();
}

/* Main entry point to VRP (Value Range Propagation).  This pass is
   loosely based on J. R. C. Patterson, ``Accurate Static Branch
   Prediction by Value Range Propagation,'' in SIGPLAN Conference on
   Programming Language Design and Implementation, pp. 67-78, 1995.
   Also available at http://citeseer.ist.psu.edu/patterson95accurate.html

   This is essentially an SSA-CCP pass modified to deal with ranges
   instead of constants.

   While propagating ranges, we may find that two or more SSA name
   have equivalent, though distinct ranges.  For instance,

     1  x_9 = p_3->a;
     2  p_4 = ASSERT_EXPR <p_3, p_3 != 0>
     3  if (p_4 == q_2)
     4    p_5 = ASSERT_EXPR <p_4, p_4 == q_2>;
     5  endif
     6  if (q_2)

   In the code above, pointer p_5 has range [q_2, q_2], but from the
   code we can also determine that p_5 cannot be NULL and, if q_2 had
   a non-varying range, p_5's range should also be compatible with it.

   These equivalences are created by two expressions: ASSERT_EXPR and
   copy operations.  Since p_5 is an assertion on p_4, and p_4 was the
   result of another assertion, then we can use the fact that p_5 and
   p_4 are equivalent when evaluating p_5's range.

   Together with value ranges, we also propagate these equivalences
   between names so that we can take advantage of information from
   multiple ranges when doing final replacement.  Note that this
   equivalency relation is transitive but not symmetric.

   In the example above, p_5 is equivalent to p_4, q_2 and p_3, but we
   cannot assert that q_2 is equivalent to p_5 because q_2 may be used
   in contexts where that assertion does not hold (e.g., in line 6).

   TODO, the main difference between this pass and Patterson's is that
   we do not propagate edge probabilities.  We only compute whether
   edges can be taken or not.  That is, instead of having a spectrum
   of jump probabilities between 0 and 1, we only deal with 0, 1 and
   DON'T KNOW.  In the future, it may be worthwhile to propagate
   probabilities to aid branch prediction.  */

static unsigned int
execute_vrp (bool warn_array_bounds_p)
{

  loop_optimizer_init (LOOPS_NORMAL | LOOPS_HAVE_RECORDED_EXITS);
  rewrite_into_loop_closed_ssa (NULL, TODO_update_ssa);
  scev_initialize ();

  /* ???  This ends up using stale EDGE_DFS_BACK for liveness computation.
     Inserting assertions may split edges which will invalidate
     EDGE_DFS_BACK.  */
  insert_range_assertions ();

  threadedge_initialize_values ();

  /* For visiting PHI nodes we need EDGE_DFS_BACK computed.  */
  mark_dfs_back_edges ();

  class vrp_prop vrp_prop;
  vrp_prop.vrp_initialize ();
  vrp_prop.ssa_propagate ();
  vrp_prop.vrp_finalize (warn_array_bounds_p);

  /* We must identify jump threading opportunities before we release
     the datastructures built by VRP.  */
  identify_jump_threads (&vrp_prop.vr_values);

  /* A comparison of an SSA_NAME against a constant where the SSA_NAME
     was set by a type conversion can often be rewritten to use the
     RHS of the type conversion.

     However, doing so inhibits jump threading through the comparison.
     So that transformation is not performed until after jump threading
     is complete.  */
  basic_block bb;
  FOR_EACH_BB_FN (bb, cfun)
    {
      gimple *last = last_stmt (bb);
      if (last && gimple_code (last) == GIMPLE_COND)
        vrp_prop.vr_values.simplify_cond_using_ranges_2 (as_a <gcond *> (last));
    }

  free_numbers_of_iterations_estimates (cfun);

  /* ASSERT_EXPRs must be removed before finalizing jump threads
     as finalizing jump threads calls the CFG cleanup code which
     does not properly handle ASSERT_EXPRs.  */
  remove_range_assertions ();

  /* If we exposed any new variables, go ahead and put them into
     SSA form now, before we handle jump threading.  This simplifies
     interactions between rewriting of _DECL nodes into SSA form
     and rewriting SSA_NAME nodes into SSA form after block
     duplication and CFG manipulation.  */
  update_ssa (TODO_update_ssa);

  /* We identified all the jump threading opportunities earlier, but could
     not transform the CFG at that time.  This routine transforms the
     CFG and arranges for the dominator tree to be rebuilt if necessary.

     Note the SSA graph update will occur during the normal TODO
     processing by the pass manager.  */
  thread_through_all_blocks (false);

  vrp_prop.vr_values.cleanup_edges_and_switches ();
  threadedge_finalize_values ();

  scev_finalize ();
  loop_optimizer_finalize ();
  return 0;
}

namespace {

const pass_data pass_data_vrp =
{
  GIMPLE_PASS, /* type */
  "vrp", /* name */
  OPTGROUP_NONE, /* optinfo_flags */
  TV_TREE_VRP, /* tv_id */
  PROP_ssa, /* properties_required */
  0, /* properties_provided */
  0, /* properties_destroyed */
  0, /* todo_flags_start */
  ( TODO_cleanup_cfg | TODO_update_ssa ), /* todo_flags_finish */
};

class pass_vrp : public gimple_opt_pass
{
public:
  pass_vrp (gcc::context *ctxt)
    : gimple_opt_pass (pass_data_vrp, ctxt), warn_array_bounds_p (false)
  {}

  /* opt_pass methods: */
  opt_pass * clone () { return new pass_vrp (m_ctxt); }
  void set_pass_param (unsigned int n, bool param)
    {
      gcc_assert (n == 0);
      warn_array_bounds_p = param;
    }
  virtual bool gate (function *) { return flag_tree_vrp != 0; }
  virtual unsigned int execute (function *)
    { return execute_vrp (warn_array_bounds_p); }

 private:
  bool warn_array_bounds_p;
}; // class pass_vrp

} // anon namespace

gimple_opt_pass *
make_pass_vrp (gcc::context *ctxt)
{
  return new pass_vrp (ctxt);
}


/* Worker for determine_value_range.  */

static void
determine_value_range_1 (value_range *vr, tree expr)
{
  if (BINARY_CLASS_P (expr))
    {
      value_range vr0 = VR_INITIALIZER, vr1 = VR_INITIALIZER;
      determine_value_range_1 (&vr0, TREE_OPERAND (expr, 0));
      determine_value_range_1 (&vr1, TREE_OPERAND (expr, 1));
      extract_range_from_binary_expr_1 (vr, TREE_CODE (expr), TREE_TYPE (expr),
                                        &vr0, &vr1);
    }
  else if (UNARY_CLASS_P (expr))
    {
      value_range vr0 = VR_INITIALIZER;
      determine_value_range_1 (&vr0, TREE_OPERAND (expr, 0));
      extract_range_from_unary_expr (vr, TREE_CODE (expr), TREE_TYPE (expr),
                                     &vr0, TREE_TYPE (TREE_OPERAND (expr, 0)));
    }
  else if (TREE_CODE (expr) == INTEGER_CST)
    set_value_range_to_value (vr, expr, NULL);
  else
    {
      value_range_type kind;
      wide_int min, max;
      /* For SSA names try to extract range info computed by VRP.  Otherwise
         fall back to varying.  */
      if (TREE_CODE (expr) == SSA_NAME
          && INTEGRAL_TYPE_P (TREE_TYPE (expr))
          && (kind = get_range_info (expr, &min, &max)) != VR_VARYING)
        set_value_range (vr, kind, wide_int_to_tree (TREE_TYPE (expr), min),
                         wide_int_to_tree (TREE_TYPE (expr), max), NULL);
      else
        set_value_range_to_varying (vr);
    }
}

/* Compute a value-range for EXPR and set it in *MIN and *MAX.  Return
   the determined range type.  */

value_range_type
determine_value_range (tree expr, wide_int *min, wide_int *max)
{
  value_range vr = VR_INITIALIZER;
  determine_value_range_1 (&vr, expr);
  if ((vr.type == VR_RANGE
       || vr.type == VR_ANTI_RANGE)
      && !symbolic_range_p (&vr))
    {
      *min = wi::to_wide (vr.min);
      *max = wi::to_wide (vr.max);
      return vr.type;
    }

  return VR_VARYING;
}