Re: [PATCH] Rewrite NAN and sign handling in frange

[Richard Biener <richard.guenther@gmail.com>]

On Thu, Sep 15, 2022 at 7:41 AM Aldy Hernandez <aldyh@redhat.com> wrote:
>
> Hi Richard.  Hi all.
>
> The attatched patch rewrites the NAN and sign handling, dropping both
> tristates in favor of a pair of boolean flags for NANs, and nothing at
> all for signs.  The signs are tracked in the range itself, so now it's
> possible to describe things like [-0.0, +0.0] +NAN, [+0, +0], [-5, +0],
> [+0, 3] -NAN, etc.
>
> There are a lot of changes, as the tristate was quite pervasive.  I
> could use another pair of eyes.  The code IMO is cleaner and handles
> all the cases we discussed.
>
> Here is an example of the various ranges and how they are displayed:
>
>     [frange] float VARYING NAN ;; Varying includes NAN
>     [frange] UNDEFINED                      ;; Empty set as always
>     [frange] float [] NAN                   ;; Unknown sign NAN
>     [frange] float [] -NAN                  ;; -NAN
>     [frange] float [] +NAN                  ;; +NAN
>     [frange] float [-0.0, 0.0]              ;; All zeros.
>     [frange] float [-0.0, -0.0] NAN         ;; -0 or NAN.
>     [frange] float [-5.0e+0, -1.0e+0] +NAN  ;; [-5, -1] or +NAN
>     [frange] float [-5.0e+0, -0.0] NAN      ;; [-5, -0] or +-NAN
>     [frange] float [-5.0e+0, -0.0]          ;; [-5, -0]
>     [frange] float [5.0e+0, 1.0e+1]         ;; [5, 10]
>
> We could represent an unknown sign with +NAN -NAN if preferred.

maybe -+NAN or +-NAN?  I prefer to somehow show both signs for clarity

>
> Notice the NAN signs are decoupled from the range, so we can represent
> a negative range with a positive NAN.  For this range,
> frange::known_bit() would return false, as only when the signs of the
> NANs and range agree can we be certain.
>
> There is no longer any pessimization of ranges for intersects
> involving NANs.  Also, union and intersect work with signed zeros:
>
> //   [-0,  x] U [+0,  x] => [-0,  x]
> //   [ x, -0] U [ x, +0] => [ x, +0]
> //   [-0,  x] ^ [+0,  x] => [+0,  x]
> //   [ x, -0] ^ [ x, +0] => [ x, -0]
>
> The special casing for signed zeros in the singleton code is gone in
> favor of just making sure the signs in the range agree, that is
> [-0, -0] for example.
>
> I have removed the idea that a known NAN is a "range", so a NAN is no
> longer in the endpoints itself.  Requesting the bound of a known NAN
> is a hard fail.  For that matter, we don't store the actual NAN in the
> range.  The only information we have are the set of boolean flags.
> This way we make sure nothing seeps into the frange.  This also means
> it's explicit that we don't track anything but the sign in NANs.  We
> can revisit this if we desire to track signalling or whatever
> concoction y'all can imagine.
>
> All in all, I'm quite happy with this.  It does look better, and we
> handle all the corner cases we couldn't before.  Thanks for the
> suggestion.
>
> Regstrapped with mpfr tests on x86-64 and ppc64le Linux.  Selftests
> were also run with -ffinite-math-only on x86-64.
>
> At Jakub's suggestion, I built lapack with associated tests.  They
> pass on x86-64 and ppc64le Linux with no regressions from mainline.
> As a sanity check, I also ran them for -ffinite-math-only on x86 which
> (as expected) returned:
>
>         NaN arithmetic did not perform per the ieee spec
>
> Otherwise, all tests pass for -ffinite-math-only.
>
> How does this look?

Overall it looks good.

Reading ::intersect and ::union I find it less clear to spread out the _nan
cases into separate functions.

Can you add a comment to frange that its representation is
a single value-range specified by m_type, m_min, m_max
unioned with the set of { -NaN, +NaN }?  Because somehow
the ::undefined_p vs. m_type == VR_UNDEFINED checks are
a bit confusing to the occasional reader can we instead use
::nan_p to complement ::undefined_p?

Brain dump: maybe having a NaN-less frange with m_type, m_min, m_max
and then frange_with_nan having a frange member plus the nan bits
would make a better distinction?  Maybe we can use m_type == VR_RANGE
when the actual range is empty but we have NaNs somehow?  That we
need m_type to represent an empty range and VR_VARYING for the full
range is somehow duplicate - ]0,0[ would be an empty range as well,
but then we'd need inclusive/exclusive ranges.  NULL m_min/max might
be another (bad) representation.  Having m_type makes for efficient
checking as well, so that's a pro.  Maybe have m_type == VR_NAN for
the case of empty range but NaNs, leaving VR_UNDEFINED to the
true empty set?

Anyway, I think the patch is OK as-is with the NaN printing adjusted
and maybe avoiding the bare m_type == VR_UNDEFINED checks
(in all but the abstraction).

Thanks,
Richard.

>
> gcc/ChangeLog:
>
>         * range-op-float.cc (frange_add_zeros): Replace set_signbit with
>         union of zero.
>         * value-query.cc (range_query::get_tree_range): Remove set_signbit
>         use.
>         * value-range-pretty-print.cc (vrange_printer::print_frange_prop):
>         Remove.
>         (vrange_printer::print_frange_nan): New.
>         * value-range-pretty-print.h (print_frange_prop): Remove.
>         (print_frange_nan): New.
>         * value-range-storage.cc (frange_storage_slot::set_frange): Set
>         kind and NAN fields.
>         (frange_storage_slot::get_frange): Restore kind and NAN fields.
>         * value-range-storage.h (class frange_storage_slot): Add kind and
>         NAN fields.
>         * value-range.cc (frange::update_nan): Remove.
>         (frange::set_signbit): Remove.
>         (frange::set): Adjust for NAN fields.
>         (frange::normalize_kind): Remove m_props.
>         (frange::combine_zeros): New.
>         (frange::union_nans): New.
>         (frange::union_): Handle new NAN fields.
>         (frange::intersect_nans): New.
>         (frange::intersect): Handle new NAN fields.
>         (frange::operator=): Same.
>         (frange::operator==): Same.
>         (frange::contains_p): Same.
>         (frange::singleton_p): Remove special case for signed zeros.
>         (frange::verify_range): Adjust for new NAN fields.
>         (frange::set_zero): Handle signed zeros.
>         (frange::set_nonnegative): Same.
>         (range_tests_nan): Adjust tests.
>         (range_tests_signed_zeros): Same.
>         (range_tests_signbit): Same.
>         (range_tests_floats): Same.
>         * value-range.h (class fp_prop): Remove.
>         (FP_PROP_ACCESSOR): Remove.
>         (class frange_props): Remove
>         (frange::lower_bound): NANs don't have endpoints.
>         (frange::upper_bound): Same.
>         (frange_props::operator==): Remove.
>         (frange_props::union_): Remove.
>         (frange_props::intersect): Remove.
>         (frange::update_nan): New.
>         (frange::clear_nan): New.
>         (frange::undefined_p): New.
>         (frange::set_nan): New.
>         (frange::known_finite): Adjust for new NAN representation.
>         (frange::maybe_nan): Same.
>         (frange::known_nan): Same.
>         (frange::known_signbit): Same.
> ---
>  gcc/range-op-float.cc           |   6 +-
>  gcc/value-query.cc              |  11 +-
>  gcc/value-range-pretty-print.cc |  45 +--
>  gcc/value-range-pretty-print.h  |   2 +-
>  gcc/value-range-storage.cc      |   9 +-
>  gcc/value-range-storage.h       |   7 +-
>  gcc/value-range.cc              | 554 ++++++++++++++++----------------
>  gcc/value-range.h               | 212 ++++++------
>  8 files changed, 415 insertions(+), 431 deletions(-)
>
> diff --git a/gcc/range-op-float.cc b/gcc/range-op-float.cc
> index fbc14a730ad..270490010e2 100644
> --- a/gcc/range-op-float.cc
> +++ b/gcc/range-op-float.cc
> @@ -218,7 +218,11 @@ frange_add_zeros (frange &r, tree type)
>
>    if (HONOR_SIGNED_ZEROS (type)
>        && (real_iszero (&r.lower_bound ()) || real_iszero (&r.upper_bound ())))
> -    r.set_signbit (fp_prop::VARYING);
> +    {
> +      frange zero;
> +      zero.set_zero (type);
> +      r.union_ (zero);
> +    }
>  }
>
>  // Build a range that is <= VAL and store it in R.
> diff --git a/gcc/value-query.cc b/gcc/value-query.cc
> index ea6e4b979ad..0bdd670982b 100644
> --- a/gcc/value-query.cc
> +++ b/gcc/value-query.cc
> @@ -219,17 +219,8 @@ range_query::get_tree_range (vrange &r, tree expr, gimple *stmt)
>        {
>         frange &f = as_a <frange> (r);
>         f.set (expr, expr);
> -
> -       // Singletons from the tree world have known properties.
> -       REAL_VALUE_TYPE *rv = TREE_REAL_CST_PTR (expr);
> -       if (real_isnan (rv))
> -         f.update_nan (fp_prop::YES);
> -       else
> +       if (!real_isnan (TREE_REAL_CST_PTR (expr)))
>           f.clear_nan ();
> -       if (real_isneg (rv))
> -         f.set_signbit (fp_prop::YES);
> -       else
> -         f.set_signbit (fp_prop::NO);
>         return true;
>        }
>
> diff --git a/gcc/value-range-pretty-print.cc b/gcc/value-range-pretty-print.cc
> index b124e46cb9e..49b16d6a5b1 100644
> --- a/gcc/value-range-pretty-print.cc
> +++ b/gcc/value-range-pretty-print.cc
> @@ -134,34 +134,39 @@ vrange_printer::visit (const frange &r) const
>    if (r.varying_p ())
>      {
>        pp_string (pp, "VARYING");
> +      print_frange_nan (r);
>        return;
>      }
>    pp_character (pp, '[');
> -  dump_generic_node (pp,
> -                    build_real (type, r.lower_bound ()), 0, TDF_NONE, false);
> -  pp_string (pp, ", ");
> -  dump_generic_node (pp,
> -                    build_real (type, r.upper_bound ()), 0, TDF_NONE, false);
> -  pp_string (pp, "] ");
> -
> -  print_frange_prop ("NAN", r.get_nan ());
> -  print_frange_prop ("SIGN", r.get_signbit ());
> +  bool has_endpoints = !r.known_nan ();
> +  if (has_endpoints)
> +    {
> +      dump_generic_node (pp,
> +                        build_real (type, r.lower_bound ()), 0, TDF_NONE, false);
> +      pp_string (pp, ", ");
> +      dump_generic_node (pp,
> +                        build_real (type, r.upper_bound ()), 0, TDF_NONE, false);
> +    }
> +  pp_character (pp, ']');
> +  print_frange_nan (r);
>  }
>
> -// Print the FP properties in an frange.
> +// Print the NAN info for an frange.
>
>  void
> -vrange_printer::print_frange_prop (const char *str, const fp_prop &prop) const
> +vrange_printer::print_frange_nan (const frange &r) const
>  {
> -  if (prop.varying_p ())
> -    return;
> -
> -  if (prop.yes_p ())
> -    pp_string (pp, str);
> -  else if (prop.no_p ())
> +  if (r.maybe_nan ())
>      {
> -      pp_character (pp, '!');
> -      pp_string (pp, str);
> +      if (r.m_pos_nan && r.m_neg_nan)
> +       {
> +         pp_string (pp, " NAN");
> +         return;
> +       }
> +      bool nan_sign = r.m_neg_nan;
> +      if (nan_sign)
> +       pp_string (pp, " -NAN");
> +      else
> +       pp_string (pp, " +NAN");
>      }
> -  pp_character (pp, ' ');
>  }
> diff --git a/gcc/value-range-pretty-print.h b/gcc/value-range-pretty-print.h
> index ad06c93c044..20c26598fe7 100644
> --- a/gcc/value-range-pretty-print.h
> +++ b/gcc/value-range-pretty-print.h
> @@ -31,7 +31,7 @@ public:
>  private:
>    void print_irange_bound (const wide_int &w, tree type) const;
>    void print_irange_bitmasks (const irange &) const;
> -  void print_frange_prop (const char *str, const fp_prop &) const;
> +  void print_frange_nan (const frange &) const;
>
>    pretty_printer *pp;
>  };
> diff --git a/gcc/value-range-storage.cc b/gcc/value-range-storage.cc
> index b7a23fa9825..de7575ed48d 100644
> --- a/gcc/value-range-storage.cc
> +++ b/gcc/value-range-storage.cc
> @@ -253,9 +253,11 @@ frange_storage_slot::set_frange (const frange &r)
>    gcc_checking_assert (fits_p (r));
>    gcc_checking_assert (!r.undefined_p ());
>
> +  m_kind = r.m_kind;
>    m_min = r.m_min;
>    m_max = r.m_max;
> -  m_props = r.m_props;
> +  m_pos_nan = r.m_pos_nan;
> +  m_neg_nan = r.m_neg_nan;
>  }
>
>  void
> @@ -264,11 +266,12 @@ frange_storage_slot::get_frange (frange &r, tree type) const
>    gcc_checking_assert (r.supports_type_p (type));
>
>    r.set_undefined ();
> -  r.m_kind = VR_RANGE;
> -  r.m_props = m_props;
> +  r.m_kind = m_kind;
>    r.m_type = type;
>    r.m_min = m_min;
>    r.m_max = m_max;
> +  r.m_pos_nan = m_pos_nan;
> +  r.m_neg_nan = m_neg_nan;
>    r.normalize_kind ();
>
>    if (flag_checking)
> diff --git a/gcc/value-range-storage.h b/gcc/value-range-storage.h
> index f506789f3d1..0cf95ebf7c1 100644
> --- a/gcc/value-range-storage.h
> +++ b/gcc/value-range-storage.h
> @@ -113,12 +113,11 @@ class GTY (()) frange_storage_slot
>    frange_storage_slot (const frange &r) { set_frange (r); }
>    DISABLE_COPY_AND_ASSIGN (frange_storage_slot);
>
> -  // We can get away with just storing the properties and the
> -  // endpoints because the type can be gotten from the SSA, and
> -  // UNDEFINED is unsupported, so it can only be a VR_RANGE.
> +  enum value_range_kind m_kind;
>    REAL_VALUE_TYPE m_min;
>    REAL_VALUE_TYPE m_max;
> -  frange_props m_props;
> +  bool m_pos_nan;
> +  bool m_neg_nan;
>  };
>
>  class obstack_vrange_allocator final: public vrange_allocator
> diff --git a/gcc/value-range.cc b/gcc/value-range.cc
> index d759fcf178c..1c6061649b5 100644
> --- a/gcc/value-range.cc
> +++ b/gcc/value-range.cc
> @@ -267,91 +267,6 @@ tree_compare (tree_code code, tree op1, tree op2)
>    return !integer_zerop (fold_build2 (code, integer_type_node, op1, op2));
>  }
>
> -// Set the NAN property.  Adjust the range if appopriate.
> -
> -void
> -frange::update_nan (fp_prop::kind k)
> -{
> -  if (k == fp_prop::YES)
> -    {
> -      if (!maybe_nan ())
> -       {
> -         set_undefined ();
> -         return;
> -       }
> -      gcc_checking_assert (!undefined_p ());
> -      set_nan (m_type);
> -      return;
> -    }
> -
> -  if (k == fp_prop::NO && known_nan ())
> -    {
> -      set_undefined ();
> -      return;
> -    }
> -
> -  // Setting VARYING on an obviously NAN range is a no-op.
> -  if (k == fp_prop::VARYING && real_isnan (&m_min))
> -    return;
> -
> -  m_props.set_nan (k);
> -  normalize_kind ();
> -  if (flag_checking)
> -    verify_range ();
> -}
> -
> -// Set the SIGNBIT property.  Adjust the range if appropriate.
> -
> -void
> -frange::set_signbit (fp_prop::kind k)
> -{
> -  gcc_checking_assert (m_type);
> -
> -  // No additional adjustments are needed for a NAN.
> -  if (known_nan ())
> -    {
> -      m_props.set_signbit (k);
> -      return;
> -    }
> -  // Ignore sign changes when they're set correctly.
> -  if (!maybe_nan ())
> -    {
> -      // It's negative and we're trying to make it negative or varying.
> -      if (real_less (&m_max, &dconst0) && (k == fp_prop::YES
> -                                          || k == fp_prop::VARYING))
> -       return;
> -      // It's positive and we're trying to make it positive or varying.
> -      if (real_less (&dconst0, &m_min) && (k == fp_prop::NO
> -                                          || k == fp_prop::VARYING))
> -       return;
> -    }
> -  // Adjust the range depending on the sign bit.
> -  if (k == fp_prop::YES)
> -    {
> -      // Crop the range to [-INF, 0].
> -      frange crop (m_type, dconstninf, dconst0);
> -      intersect (crop);
> -      if (!undefined_p ())
> -       m_props.set_signbit (fp_prop::YES);
> -    }
> -  else if (k == fp_prop::NO)
> -    {
> -      // Crop the range to [0, +INF].
> -      frange crop (m_type, dconst0, dconstinf);
> -      intersect (crop);
> -      if (!undefined_p ())
> -       m_props.set_signbit (fp_prop::NO);
> -    }
> -  else
> -    {
> -      m_props.set_signbit (fp_prop::VARYING);
> -      normalize_kind ();
> -    }
> -
> -  if (flag_checking)
> -    verify_range ();
> -}
> -
>  // Setter for franges.
>
>  void
> @@ -375,24 +290,23 @@ frange::set (tree min, tree max, value_range_kind kind)
>        gcc_checking_assert (real_identical (TREE_REAL_CST_PTR (min),
>                                            TREE_REAL_CST_PTR (max)));
>        tree type = TREE_TYPE (min);
> -      set_nan (type);
> +      bool sign = real_isneg (TREE_REAL_CST_PTR (min));
> +      set_nan (type, sign);
>        return;
>      }
>
>    m_kind = kind;
>    m_type = TREE_TYPE (min);
> -  m_props.set_varying ();
>    m_min = *TREE_REAL_CST_PTR (min);
>    m_max = *TREE_REAL_CST_PTR (max);
> -
> -  // Set SIGNBIT property for positive and negative ranges.
> -  if (real_less (&m_max, &dconst0))
> -    m_props.signbit_set_yes ();
> -  else if (real_less (&dconst0, &m_min))
> -    m_props.signbit_set_no ();
> +  m_pos_nan = true;
> +  m_neg_nan = true;
>
>    if (!HONOR_NANS (m_type))
> -    m_props.nan_set_no ();
> +    {
> +      m_pos_nan = false;
> +      m_neg_nan = false;
> +    }
>
>    // Check for swapped ranges.
>    gcc_checking_assert (tree_compare (LE_EXPR, min, max));
> @@ -423,18 +337,11 @@ frange::set (tree type,
>  bool
>  frange::normalize_kind ()
>  {
> -  // Undefined is viral.
> -  if (m_props.nan_undefined_p () || m_props.signbit_undefined_p ())
> -    {
> -      set_undefined ();
> -      return true;
> -    }
>    if (m_kind == VR_RANGE
>        && real_isinf (&m_min, 1)
>        && real_isinf (&m_max, 0))
>      {
> -      // No FP properties set means varying.
> -      if (m_props.varying_p ())
> +      if (m_pos_nan && m_neg_nan)
>         {
>           set_varying (m_type);
>           return true;
> @@ -442,8 +349,7 @@ frange::normalize_kind ()
>      }
>    else if (m_kind == VR_VARYING)
>      {
> -      // If a VARYING has any FP properties, it's no longer VARYING.
> -      if (!m_props.varying_p ())
> +      if (!m_pos_nan || !m_neg_nan)
>         {
>           m_kind = VR_RANGE;
>           m_min = dconstninf;
> @@ -454,6 +360,60 @@ frange::normalize_kind ()
>    return false;
>  }
>
> +// Union or intersect the zero endpoints of two ranges.  For example:
> +//   [-0,  x] U [+0,  x] => [-0,  x]
> +//   [ x, -0] U [ x, +0] => [ x, +0]
> +//   [-0,  x] ^ [+0,  x] => [+0,  x]
> +//   [ x, -0] ^ [ x, +0] => [ x, -0]
> +//
> +// UNION_P is true when performing a union, or false when intersecting.
> +
> +bool
> +frange::combine_zeros (const frange &r, bool union_p)
> +{
> +  bool changed = false;
> +  if (real_iszero (&m_min) && real_iszero (&r.m_min)
> +      && real_isneg (&m_min) != real_isneg (&r.m_min))
> +    {
> +      m_min.sign = union_p;
> +      changed = true;
> +    }
> +  if (real_iszero (&m_max) && real_iszero (&r.m_max)
> +      && real_isneg (&m_max) != real_isneg (&r.m_max))
> +    {
> +      m_max.sign = !union_p;
> +      changed = true;
> +    }
> +  // If the signs are swapped, the resulting range is empty.
> +  if (m_min.sign == 0 && m_max.sign == 1)
> +    {
> +      m_kind = VR_UNDEFINED;
> +      changed = true;
> +    }
> +  return changed;
> +}
> +
> +// Union two ranges when one is known to be a NAN.
> +
> +bool
> +frange::union_nans (const frange &r)
> +{
> +  gcc_checking_assert (known_nan () || r.known_nan ());
> +
> +  if (known_nan ())
> +    {
> +      m_kind = r.m_kind;
> +      m_min = r.m_min;
> +      m_max = r.m_max;
> +    }
> +  m_pos_nan |= r.m_pos_nan;
> +  m_neg_nan |= r.m_neg_nan;
> +  normalize_kind ();
> +  if (flag_checking)
> +    verify_range ();
> +  return true;
> +}
> +
>  bool
>  frange::union_ (const vrange &v)
>  {
> @@ -467,29 +427,18 @@ frange::union_ (const vrange &v)
>        return true;
>      }
>
> -  // If one side has a NAN, the union is the other side, plus the union
> -  // of the properties and the possibility of a NAN.
> -  if (known_nan ())
> -    {
> -      frange_props save = m_props;
> -      *this = r;
> -      m_props = save;
> -      m_props.union_ (r.m_props);
> -      update_nan (fp_prop::VARYING);
> -      if (flag_checking)
> -       verify_range ();
> -      return true;
> -    }
> -  if (r.known_nan ())
> +  // Combine NAN info.
> +  if (known_nan () || r.known_nan ())
> +    return union_nans (r);
> +  bool changed = false;
> +  if (m_pos_nan != r.m_pos_nan || m_neg_nan != r.m_neg_nan)
>      {
> -      m_props.union_ (r.m_props);
> -      update_nan (fp_prop::VARYING);
> -      if (flag_checking)
> -       verify_range ();
> -      return true;
> +      m_pos_nan |= r.m_pos_nan;
> +      m_neg_nan |= r.m_neg_nan;
> +      changed = true;
>      }
>
> -  bool changed = m_props.union_ (r.m_props);
> +  // Combine endpoints.
>    if (real_less (&r.m_min, &m_min))
>      {
>        m_min = r.m_min;
> @@ -500,13 +449,38 @@ frange::union_ (const vrange &v)
>        m_max = r.m_max;
>        changed = true;
>      }
> -  changed |= normalize_kind ();
>
> +  if (HONOR_SIGNED_ZEROS (m_type))
> +    changed |= combine_zeros (r, true);
> +
> +  changed |= normalize_kind ();
>    if (flag_checking)
>      verify_range ();
>    return changed;
>  }
>
> +// Intersect two ranges when one is known to be a NAN.
> +
> +bool
> +frange::intersect_nans (const frange &r)
> +{
> +  gcc_checking_assert (known_nan () || r.known_nan ());
> +
> +  m_kind = VR_UNDEFINED;
> +  m_pos_nan &= r.m_pos_nan;
> +  m_neg_nan &= r.m_neg_nan;
> +  if (!maybe_nan ())
> +    {
> +      // If the NAN was intersected out, the resulting range is empty.
> +      set_undefined ();
> +      return true;
> +    }
> +  normalize_kind ();
> +  if (flag_checking)
> +    verify_range ();
> +  return true;
> +}
> +
>  bool
>  frange::intersect (const vrange &v)
>  {
> @@ -525,25 +499,18 @@ frange::intersect (const vrange &v)
>        return true;
>      }
>
> -  // If two NANs are not exactly the same, drop to an unknown NAN,
> -  // otherwise there's nothing to do.
> -  if (known_nan () && r.known_nan ())
> -    {
> -      if (m_props == r.m_props)
> -       return false;
> -
> -      set_nan (m_type);
> -      return true;
> -    }
> -  // ?? Perhaps the intersection of a NAN and anything is a NAN ??.
> +  // Combine NAN info.
>    if (known_nan () || r.known_nan ())
> +    return intersect_nans (r);
> +  bool changed = false;
> +  if (m_pos_nan != r.m_pos_nan || m_neg_nan != r.m_neg_nan)
>      {
> -      set_varying (m_type);
> -      return true;
> +      m_pos_nan &= r.m_pos_nan;
> +      m_neg_nan &= r.m_neg_nan;
> +      changed = true;
>      }
>
> -  bool changed = m_props.intersect (r.m_props);
> -
> +  // Combine endpoints.
>    if (real_less (&m_min, &r.m_min))
>      {
>        m_min = r.m_min;
> @@ -554,14 +521,25 @@ frange::intersect (const vrange &v)
>        m_max = r.m_max;
>        changed = true;
>      }
> -  // If the endpoints are swapped, the ranges are disjoint.
>    if (real_less (&m_max, &m_min))
>      {
> +      // If the endpoints are swapped, the resulting range is empty.
> +      if (maybe_nan ())
> +       {
> +         // An empty range with a NAN is just a NAN.
> +         m_kind = VR_UNDEFINED;
> +         if (flag_checking)
> +           verify_range ();
> +         return true;
> +       }
>        set_undefined ();
>        return true;
>      }
> -  changed |= normalize_kind ();
>
> +  if (HONOR_SIGNED_ZEROS (m_type))
> +    changed |= combine_zeros (r, false);
> +
> +  changed |= normalize_kind ();
>    if (flag_checking)
>      verify_range ();
>    return changed;
> @@ -574,7 +552,8 @@ frange::operator= (const frange &src)
>    m_type = src.m_type;
>    m_min = src.m_min;
>    m_max = src.m_max;
> -  m_props = src.m_props;
> +  m_pos_nan = src.m_pos_nan;
> +  m_neg_nan = src.m_neg_nan;
>
>    if (flag_checking)
>      verify_range ();
> @@ -597,7 +576,8 @@ frange::operator== (const frange &src) const
>
>        return (real_identical (&m_min, &src.m_min)
>               && real_identical (&m_max, &src.m_max)
> -             && m_props == src.m_props
> +             && m_pos_nan == src.m_pos_nan
> +             && m_neg_nan == src.m_neg_nan
>               && types_compatible_p (m_type, src.m_type));
>      }
>    return false;
> @@ -617,21 +597,24 @@ frange::contains_p (tree cst) const
>    if (varying_p ())
>      return true;
>
> +  if (real_isnan (rv))
> +    {
> +      // No NAN in range.
> +      if (!m_pos_nan && !m_neg_nan)
> +       return false;
> +      // Both +NAN and -NAN are present.
> +      if (m_pos_nan && m_neg_nan)
> +       return true;
> +      return m_neg_nan == rv->sign;
> +    }
> +  if (known_nan ())
> +    return false;
>
>    if (real_compare (GE_EXPR, rv, &m_min) && real_compare (LE_EXPR, rv, &m_max))
>      {
> +      // Make sure the signs are equal for signed zeros.
>        if (HONOR_SIGNED_ZEROS (m_type) && real_iszero (rv))
> -       {
> -         // FIXME: This is still using get_signbit() instead of
> -         // known_signbit() because the latter bails on possible NANs
> -         // (for now).
> -         if (get_signbit ().yes_p ())
> -           return real_isneg (rv);
> -         else if (get_signbit ().no_p ())
> -           return !real_isneg (rv);
> -         else
> -           return true;
> -       }
> +       return m_min.sign == m_max.sign && m_min.sign == rv->sign;
>        return true;
>      }
>    return false;
> @@ -651,26 +634,6 @@ frange::singleton_p (tree *result) const
>        if (HONOR_NANS (m_type) && maybe_nan ())
>         return false;
>
> -      // Return the appropriate zero if known.
> -      if (HONOR_SIGNED_ZEROS (m_type) && zero_p ())
> -       {
> -         bool signbit;
> -         if (known_signbit (signbit))
> -           {
> -             if (signbit)
> -               {
> -                 if (result)
> -                   *result = build_real (m_type, real_value_negate (&dconst0));
> -               }
> -             else
> -               {
> -                 if (result)
> -                   *result = build_real (m_type, dconst0);
> -               }
> -             return true;
> -           }
> -         return false;
> -       }
>        if (result)
>         *result = build_real (m_type, m_min);
>        return true;
> @@ -687,57 +650,31 @@ frange::supports_type_p (const_tree type) const
>  void
>  frange::verify_range ()
>  {
> -  if (undefined_p ())
> -    {
> -      gcc_checking_assert (m_props.undefined_p ());
> -      return;
> -    }
> -  gcc_checking_assert (!m_props.undefined_p ());
> -
> +  if (m_kind == VR_UNDEFINED)
> +    return;
>    if (varying_p ())
>      {
> -      gcc_checking_assert (m_props.varying_p ());
> +      gcc_checking_assert (m_pos_nan && m_neg_nan);
> +      gcc_checking_assert (real_isinf (&m_min, 1));
> +      gcc_checking_assert (real_isinf (&m_max, 0));
>        return;
>      }
>
> +  // NANs cannot appear in the endpoints of a range.
> +  gcc_checking_assert (!real_isnan (&m_min) && !real_isnan (&m_max));
> +
>    // We don't support the inverse of an frange (yet).
>    gcc_checking_assert (m_kind == VR_RANGE);
>
> -  bool is_nan = real_isnan (&m_min) || real_isnan (&m_max);
> -  if (is_nan)
> -    {
> -      // If either is a NAN, both must be a NAN.
> -      gcc_checking_assert (real_identical (&m_min, &m_max));
> -      gcc_checking_assert (known_nan ());
> -    }
> -  else
> -    // Make sure we don't have swapped ranges.
> -    gcc_checking_assert (!real_less (&m_max, &m_min));
> +  // Make sure we don't have swapped ranges.
> +  gcc_checking_assert (!real_less (&m_max, &m_min));
>
> -  // If we're absolutely sure we have a NAN, the endpoints should
> -  // reflect this, otherwise we'd have more than one way to represent
> -  // a NAN.
> -  if (known_nan ())
> -    {
> -      gcc_checking_assert (real_isnan (&m_min));
> -      gcc_checking_assert (real_isnan (&m_max));
> -    }
> -  else
> -    {
> -      // Make sure the signbit and range agree.
> -      bool signbit;
> -      if (known_signbit (signbit))
> -       {
> -         if (signbit)
> -           gcc_checking_assert (real_compare (LE_EXPR, &m_max, &dconst0));
> -         else
> -           gcc_checking_assert (real_compare (GE_EXPR, &m_min, &dconst0));
> -       }
> -    }
> +  // [ +0.0, -0.0 ] is nonsensical.
> +  gcc_checking_assert (!(real_iszero (&m_min, 0) && real_iszero (&m_max, 1)));
>
>    // If all the properties are clear, we better not span the entire
>    // domain, because that would make us varying.
> -  if (m_props.varying_p ())
> +  if (m_pos_nan && m_neg_nan)
>      gcc_checking_assert (!real_isinf (&m_min, 1) || !real_isinf (&m_max, 0));
>  }
>
> @@ -755,16 +692,24 @@ frange::nonzero_p () const
>    return false;
>  }
>
> -// Set range to [+0.0, +0.0].
> +// Set range to [+0.0, +0.0] if honoring signed zeros, or [0.0, 0.0]
> +// otherwise.
>
>  void
>  frange::set_zero (tree type)
>  {
> -  tree zero = build_zero_cst (type);
> -  set (zero, zero);
> +  if (HONOR_SIGNED_ZEROS (type))
> +    {
> +      REAL_VALUE_TYPE dconstm0 = dconst0;
> +      dconstm0.sign = 1;
> +      set (type, dconstm0, dconst0);
> +      clear_nan ();
> +    }
> +  else
> +    set (type, dconst0, dconst0);
>  }
>
> -// Return TRUE for any [0.0, 0.0] regardless of sign.
> +// Return TRUE for any zero regardless of sign.
>
>  bool
>  frange::zero_p () const
> @@ -777,9 +722,7 @@ frange::zero_p () const
>  void
>  frange::set_nonnegative (tree type)
>  {
> -  tree zero = build_zero_cst (type);
> -  tree inf = vrp_val_max (type);
> -  set (zero, inf);
> +  set (type, dconst0, dconstinf);
>  }
>
>  // Here we copy between any two irange's.  The ranges can be legacy or
> @@ -3637,8 +3580,21 @@ range_tests_nan ()
>        ASSERT_EQ (r0, r1);
>        r0.clear_nan ();
>        ASSERT_NE (r0, r1);
> +      r0.update_nan ();
> +      ASSERT_EQ (r0, r1);
> +
> +      // [10, 20] NAN ^ [30, 40] NAN = NAN.
> +      r0 = frange_float ("10", "20");
> +      r1 = frange_float ("30", "40");
> +      r0.intersect (r1);
> +      ASSERT_TRUE (r0.known_nan ());
> +
> +      // [3,5] U [5,10] NAN = ... NAN
> +      r0 = frange_float ("3", "5");
>        r0.clear_nan ();
> -      ASSERT_NE (r0, r1);
> +      r1 = frange_float ("5", "10");
> +      r0.union_ (r1);
> +      ASSERT_TRUE (r0.maybe_nan ());
>      }
>
>    // NAN ranges are not equal to each other.
> @@ -3663,15 +3619,15 @@ range_tests_nan ()
>    r0.set_nan (float_type_node);
>    r1.set_nan (float_type_node);
>    r0.union_ (r1);
> -  ASSERT_TRUE (real_isnan (&r0.lower_bound ()));
> -  ASSERT_TRUE (real_isnan (&r1.upper_bound ()));
>    ASSERT_TRUE (r0.known_nan ());
>
> -  // [INF, INF] ^ NAN = VARYING
> +  // [INF, INF] NAN ^ NAN = NAN
>    r0.set_nan (float_type_node);
>    r1 = frange_float ("+Inf", "+Inf");
> +  if (!HONOR_NANS (float_type_node))
> +    r1.update_nan ();
>    r0.intersect (r1);
> -  ASSERT_TRUE (r0.varying_p ());
> +  ASSERT_TRUE (r0.known_nan ());
>
>    // NAN ^ NAN = NAN
>    r0.set_nan (float_type_node);
> @@ -3679,18 +3635,48 @@ range_tests_nan ()
>    r0.intersect (r1);
>    ASSERT_TRUE (r0.known_nan ());
>
> +  // +NAN ^ -NAN = UNDEFINED
> +  r0.set_nan (float_type_node, false);
> +  r1.set_nan (float_type_node, true);
> +  r0.intersect (r1);
> +  ASSERT_TRUE (r0.undefined_p ());
> +
>    // VARYING ^ NAN = NAN.
>    r0.set_nan (float_type_node);
>    r1.set_varying (float_type_node);
>    r0.intersect (r1);
>    ASSERT_TRUE (r0.known_nan ());
>
> -  // Setting the NAN bit to yes, forces to range to [NAN, NAN].
> +  // [3,4] ^ NAN = UNDEFINED.
> +  r0 = frange_float ("3", "4");
> +  r0.clear_nan ();
> +  r1.set_nan (float_type_node);
> +  r0.intersect (r1);
> +  ASSERT_TRUE (r0.undefined_p ());
> +
> +  // [-3, 5] ^ NAN = UNDEFINED
> +  r0 = frange_float ("-3", "5");
> +  r0.clear_nan ();
> +  r1.set_nan (float_type_node);
> +  r0.intersect (r1);
> +  ASSERT_TRUE (r0.undefined_p ());
> +
> +  // Setting the NAN bit to yes does not make us a known NAN.
>    r0.set_varying (float_type_node);
> -  r0.update_nan (fp_prop::YES);
> -  ASSERT_TRUE (r0.known_nan ());
> -  ASSERT_TRUE (real_isnan (&r0.lower_bound ()));
> -  ASSERT_TRUE (real_isnan (&r0.upper_bound ()));
> +  r0.update_nan ();
> +  ASSERT_FALSE (r0.known_nan ());
> +
> +  // NAN is in a VARYING.
> +  r0.set_varying (float_type_node);
> +  real_nan (&r, "", 1, TYPE_MODE (float_type_node));
> +  tree nan = build_real (float_type_node, r);
> +  ASSERT_TRUE (r0.contains_p (nan));
> +
> +  // -NAN is in a VARYING.
> +  r0.set_varying (float_type_node);
> +  q = real_value_negate (&r);
> +  tree neg_nan = build_real (float_type_node, q);
> +  ASSERT_TRUE (r0.contains_p (neg_nan));
>  }
>
>  static void
> @@ -3702,49 +3688,84 @@ range_tests_signed_zeros ()
>    frange r0, r1;
>    bool signbit;
>
> -  // Since -0.0 == +0.0, a range of [-0.0, -0.0] should contain +0.0
> -  // and vice versa.
> +  // [0,0] contains [0,0] but not [-0,-0] and vice versa.
>    r0 = frange (zero, zero);
>    r1 = frange (neg_zero, neg_zero);
>    ASSERT_TRUE (r0.contains_p (zero));
> -  ASSERT_TRUE (r0.contains_p (neg_zero));
> -  ASSERT_TRUE (r1.contains_p (zero));
> +  ASSERT_TRUE (!r0.contains_p (neg_zero));
>    ASSERT_TRUE (r1.contains_p (neg_zero));
> +  ASSERT_TRUE (!r1.contains_p (zero));
>
>    // Test contains_p() when we know the sign of the zero.
> -  r0 = frange(zero, zero);
> -  r0.set_signbit (fp_prop::NO);
> +  r0 = frange (zero, zero);
>    ASSERT_TRUE (r0.contains_p (zero));
>    ASSERT_FALSE (r0.contains_p (neg_zero));
> -  r0.set_signbit (fp_prop::YES);
> +  r0 = frange (neg_zero, neg_zero);
>    ASSERT_TRUE (r0.contains_p (neg_zero));
>    ASSERT_FALSE (r0.contains_p (zero));
>
> -  // The intersection of zeros that differ in sign is the empty set.
> -  r0 = frange (zero, zero);
> -  r0.set_signbit (fp_prop::YES);
> +  // The intersection of zeros that differ in sign is a NAN (or
> +  // undefined if not honoring NANs).
> +  r0 = frange (neg_zero, neg_zero);
>    r1 = frange (zero, zero);
> -  r1.set_signbit (fp_prop::NO);
>    r0.intersect (r1);
> -  ASSERT_TRUE (r0.undefined_p ());
> +  if (HONOR_NANS (float_type_node))
> +    ASSERT_TRUE (r0.known_nan ());
> +  else
> +    ASSERT_TRUE (r0.undefined_p ());
>
>    // The union of zeros that differ in sign is a zero with unknown sign.
>    r0 = frange (zero, zero);
> -  r0.set_signbit (fp_prop::NO);
> -  r1 = frange (zero, zero);
> -  r1.set_signbit (fp_prop::YES);
> +  r1 = frange (neg_zero, neg_zero);
>    r0.union_ (r1);
>    ASSERT_TRUE (r0.zero_p () && !r0.known_signbit (signbit));
>
> -  // NAN U [5,6] should be [5,6] with no sign info.
> +  // [-0, +0] has an unknown sign.
> +  r0 = frange (neg_zero, zero);
> +  ASSERT_TRUE (r0.zero_p () && !r0.known_signbit (signbit));
> +
> +  // [-0, +0] ^ [0, 0] is [0, 0]
> +  r0 = frange (neg_zero, zero);
> +  r1 = frange (zero, zero);
> +  r0.intersect (r1);
> +  ASSERT_TRUE (r0.zero_p ());
> +
> +  // NAN U [5,6] should be [5,6] NAN.
>    r0.set_nan (float_type_node);
>    r1 = frange_float ("5", "6");
> +  r1.clear_nan ();
>    r0.union_ (r1);
>    real_from_string (&q, "5");
>    real_from_string (&r, "6");
>    ASSERT_TRUE (real_identical (&q, &r0.lower_bound ()));
>    ASSERT_TRUE (real_identical (&r, &r0.upper_bound ()));
>    ASSERT_TRUE (!r0.known_signbit (signbit));
> +  ASSERT_TRUE (r0.maybe_nan ());
> +
> +  r0 = frange_float ("+0", "5");
> +  r0.clear_nan ();
> +  ASSERT_TRUE (r0.known_signbit (signbit) && !signbit);
> +
> +  r0 = frange_float ("-0", "5");
> +  r0.clear_nan ();
> +  ASSERT_TRUE (!r0.known_signbit (signbit));
> +
> +  r0 = frange_float ("-0", "10");
> +  r1 = frange_float ("0", "5");
> +  r0.intersect (r1);
> +  ASSERT_TRUE (real_iszero (&r0.lower_bound (), false));
> +
> +  r0 = frange_float ("-0", "5");
> +  r1 = frange_float ("0", "5");
> +  r0.union_ (r1);
> +  ASSERT_TRUE (real_iszero (&r0.lower_bound (), true));
> +
> +  r0 = frange_float ("-5", "-0");
> +  r0.update_nan ();
> +  r1 = frange_float ("0", "0");
> +  r1.update_nan ();
> +  r0.intersect (r1);
> +  ASSERT_TRUE (r0.known_nan ());
>  }
>
>  static void
> @@ -3753,22 +3774,6 @@ range_tests_signbit ()
>    frange r0, r1;
>    bool signbit;
>
> -  // Setting the signbit drops the range to [-INF, 0].
> -  r0.set_varying (float_type_node);
> -  r0.set_signbit (fp_prop::YES);
> -  ASSERT_TRUE (real_isinf (&r0.lower_bound (), 1));
> -  ASSERT_TRUE (real_iszero (&r0.upper_bound ()));
> -
> -  // Setting the signbit for [-5, 10] crops the range to [-5, 0] with
> -  // the signbit property set.
> -  r0 = frange_float ("-5", "10");
> -  r0.set_signbit (fp_prop::YES);
> -  r0.clear_nan ();
> -  ASSERT_TRUE (r0.known_signbit (signbit) && signbit);
> -  r1 = frange_float ("-5", "0");
> -  ASSERT_TRUE (real_identical (&r0.lower_bound (), &r1.lower_bound ()));
> -  ASSERT_TRUE (real_identical (&r0.upper_bound (), &r1.upper_bound ()));
> -
>    // Negative numbers should have the SIGNBIT set.
>    r0 = frange_float ("-5", "-1");
>    r0.clear_nan ();
> @@ -3780,7 +3785,7 @@ range_tests_signbit ()
>    // Numbers containing zero should have an unknown SIGNBIT.
>    r0 = frange_float ("0", "10");
>    r0.clear_nan ();
> -  ASSERT_TRUE (!r0.known_signbit (signbit));
> +  ASSERT_TRUE (r0.known_signbit (signbit) && !signbit);
>    // Numbers spanning both positive and negative should have an
>    // unknown SIGNBIT.
>    r0 = frange_float ("-10", "10");
> @@ -3788,17 +3793,6 @@ range_tests_signbit ()
>    ASSERT_TRUE (!r0.known_signbit (signbit));
>    r0.set_varying (float_type_node);
>    ASSERT_TRUE (!r0.known_signbit (signbit));
> -
> -  // Ignore signbit changes when the sign bit is obviously known from
> -  // the range.
> -  r0 = frange_float ("5", "10");
> -  r0.clear_nan ();
> -  r0.set_signbit (fp_prop::VARYING);
> -  ASSERT_TRUE (r0.known_signbit (signbit) && !signbit);
> -  r0 = frange_float ("-5", "-1");
> -  r0.set_signbit (fp_prop::NO);
> -  r0.clear_nan ();
> -  ASSERT_TRUE (r0.undefined_p ());
>  }
>
>  static void
> @@ -3896,9 +3890,19 @@ range_tests_floats ()
>    r0.intersect (r1);
>    ASSERT_EQ (r0, frange_float ("15", "20"));
>
> +  // [10,20] NAN ^ [21,25] NAN = [NAN]
> +  r0 = frange_float ("10", "20");
> +  r0.update_nan ();
> +  r1 = frange_float ("21", "25");
> +  r1.update_nan ();
> +  r0.intersect (r1);
> +  ASSERT_TRUE (r0.known_nan ());
> +
>    // [10,20] ^ [21,25] = []
>    r0 = frange_float ("10", "20");
> +  r0.clear_nan ();
>    r1 = frange_float ("21", "25");
> +  r1.clear_nan ();
>    r0.intersect (r1);
>    ASSERT_TRUE (r0.undefined_p ());
>  }
> diff --git a/gcc/value-range.h b/gcc/value-range.h
> index 4392de84c8b..cbb6496f976 100644
> --- a/gcc/value-range.h
> +++ b/gcc/value-range.h
> @@ -93,7 +93,7 @@ public:
>    virtual bool fits_p (const vrange &r) const;
>
>    bool varying_p () const;
> -  bool undefined_p () const;
> +  virtual bool undefined_p () const;
>    vrange& operator= (const vrange &);
>    bool operator== (const vrange &) const;
>    bool operator!= (const vrange &r) const { return !(*this == r); }
> @@ -263,68 +263,6 @@ public:
>    virtual void accept (const vrange_visitor &v) const override;
>  };
>
> -// Floating point property to represent possible values of a NAN, INF, etc.
> -
> -class fp_prop
> -{
> -public:
> -  enum kind {
> -    UNDEFINED  = 0x0,          // Prop is impossible.
> -    YES                = 0x1,          // Prop is definitely set.
> -    NO         = 0x2,          // Prop is definitely not set.
> -    VARYING    = (YES | NO)    // Prop may hold.
> -  };
> -  fp_prop (kind f) : m_kind (f) { }
> -  bool varying_p () const { return m_kind == VARYING; }
> -  bool undefined_p () const { return m_kind == UNDEFINED; }
> -  bool yes_p () const { return m_kind == YES; }
> -  bool no_p () const { return m_kind == NO; }
> -private:
> -  unsigned char m_kind : 2;
> -};
> -
> -// Accessors for individual FP properties.
> -
> -#define FP_PROP_ACCESSOR(NAME) \
> -  void NAME##_set_varying () { u.bits.NAME = fp_prop::VARYING; }       \
> -  void NAME##_set_yes () { u.bits.NAME = fp_prop::YES; }       \
> -  void NAME##_set_no () { u.bits.NAME = fp_prop::NO; } \
> -  bool NAME##_varying_p () const { return u.bits.NAME == fp_prop::VARYING; } \
> -  bool NAME##_undefined_p () const { return u.bits.NAME == fp_prop::UNDEFINED; } \
> -  bool NAME##_yes_p () const { return u.bits.NAME == fp_prop::YES; }   \
> -  bool NAME##_no_p () const { return u.bits.NAME == fp_prop::NO; } \
> -  fp_prop get_##NAME () const                             \
> -  { return fp_prop ((fp_prop::kind) u.bits.NAME); } \
> -  void set_##NAME (fp_prop::kind f) { u.bits.NAME = f; }
> -
> -// Aggregate of all the FP properties in an frange packed into one
> -// structure to save space.  Using explicit fp_prop's in the frange,
> -// would take one byte per property because of padding.  Instead, we
> -// can save all properties into one byte.
> -
> -class frange_props
> -{
> -public:
> -  frange_props () { set_varying (); }
> -  void set_varying () { u.bytes = 0xff; }
> -  void set_undefined () { u.bytes = 0; }
> -  bool varying_p () { return u.bytes == 0xff; }
> -  bool undefined_p () { return u.bytes == 0; }
> -  bool union_ (const frange_props &other);
> -  bool intersect (const frange_props &other);
> -  bool operator== (const frange_props &other) const;
> -  FP_PROP_ACCESSOR(nan)
> -  FP_PROP_ACCESSOR(signbit)
> -private:
> -  union {
> -    struct {
> -      unsigned char nan : 2;
> -      unsigned char signbit : 2;
> -    } bits;
> -    unsigned char bytes;
> -  } u;
> -};
> -
>  // A floating point range.
>
>  class frange : public vrange
> @@ -349,8 +287,10 @@ public:
>    void set (tree type, const REAL_VALUE_TYPE &, const REAL_VALUE_TYPE &,
>             value_range_kind = VR_RANGE);
>    void set_nan (tree type);
> +  void set_nan (tree type, bool sign);
>    virtual void set_varying (tree type) override;
>    virtual void set_undefined () override;
> +  virtual bool undefined_p () const final override;
>    virtual bool union_ (const vrange &) override;
>    virtual bool intersect (const vrange &) override;
>    virtual bool contains_p (tree) const override;
> @@ -376,33 +316,33 @@ public:
>    bool known_nan () const;
>    bool known_signbit (bool &signbit) const;
>
> -  // Accessors for FP properties.
> -  void update_nan (fp_prop::kind f);
> -  void clear_nan () { update_nan (fp_prop::NO); }
> -  void set_signbit (fp_prop::kind);
> +  void update_nan ();
> +  void clear_nan ();
>  private:
> -  fp_prop get_nan () const { return m_props.get_nan (); }
> -  fp_prop get_signbit () const { return m_props.get_signbit (); }
>    void verify_range ();
>    bool normalize_kind ();
> +  bool union_nans (const frange &);
> +  bool intersect_nans (const frange &);
> +  bool combine_zeros (const frange &, bool union_p);
>
> -  frange_props m_props;
>    tree m_type;
>    REAL_VALUE_TYPE m_min;
>    REAL_VALUE_TYPE m_max;
> +  bool m_pos_nan;
> +  bool m_neg_nan;
>  };
>
>  inline const REAL_VALUE_TYPE &
>  frange::lower_bound () const
>  {
> -  gcc_checking_assert (!undefined_p ());
> +  gcc_checking_assert (!undefined_p () && !known_nan ());
>    return m_min;
>  }
>
>  inline const REAL_VALUE_TYPE &
>  frange::upper_bound () const
>  {
> -  gcc_checking_assert (!undefined_p ());
> +  gcc_checking_assert (!undefined_p () && !known_nan ());
>    return m_max;
>  }
>
> @@ -1082,30 +1022,6 @@ vrp_val_min (const_tree type)
>    return NULL_TREE;
>  }
>
> -// Supporting methods for frange.
> -
> -inline bool
> -frange_props::operator== (const frange_props &other) const
> -{
> -  return u.bytes == other.u.bytes;
> -}
> -
> -inline bool
> -frange_props::union_ (const frange_props &other)
> -{
> -  unsigned char saved = u.bytes;
> -  u.bytes |= other.u.bytes;
> -  return u.bytes != saved;
> -}
> -
> -inline bool
> -frange_props::intersect (const frange_props &other)
> -{
> -  unsigned char saved = u.bytes;
> -  u.bytes &= other.u.bytes;
> -  return u.bytes != saved;
> -}
> -
>  inline
>  frange::frange ()
>  {
> @@ -1154,15 +1070,52 @@ frange::set_varying (tree type)
>    m_type = type;
>    m_min = dconstninf;
>    m_max = dconstinf;
> -  m_props.set_varying ();
> +  m_pos_nan = true;
> +  m_neg_nan = true;
>  }
>
>  inline void
>  frange::set_undefined ()
>  {
>    m_kind = VR_UNDEFINED;
> -  m_type = NULL;
> -  m_props.set_undefined ();
> +  m_pos_nan = false;
> +  m_neg_nan = false;
> +  if (flag_checking)
> +    verify_range ();
> +}
> +
> +// Set the NAN bit and adjust the range.
> +
> +inline void
> +frange::update_nan ()
> +{
> +  gcc_checking_assert (!undefined_p ());
> +  m_pos_nan = true;
> +  m_neg_nan = true;
> +  normalize_kind ();
> +  if (flag_checking)
> +    verify_range ();
> +}
> +
> +// Clear the NAN bit and adjust the range.
> +
> +inline void
> +frange::clear_nan ()
> +{
> +  gcc_checking_assert (!undefined_p ());
> +  m_pos_nan = false;
> +  m_neg_nan = false;
> +  normalize_kind ();
> +  if (flag_checking)
> +    verify_range ();
> +}
> +
> +// Return TRUE if range is the empty set.
> +
> +inline bool
> +frange::undefined_p () const
> +{
> +  return m_kind == VR_UNDEFINED && !m_pos_nan && !m_neg_nan;
>  }
>
>  // Set R to maximum representable value for TYPE.
> @@ -1186,19 +1139,28 @@ real_min_representable (REAL_VALUE_TYPE *r, tree type)
>    *r = real_value_negate (r);
>  }
>
> -// Build a NAN of type TYPE.
> +// Build a signless NAN of type TYPE.
>
>  inline void
>  frange::set_nan (tree type)
>  {
> -  REAL_VALUE_TYPE r;
> -  gcc_assert (real_nan (&r, "", 1, TYPE_MODE (type)));
> -  m_kind = VR_RANGE;
> +  m_kind = VR_UNDEFINED;
> +  m_type = type;
> +  m_pos_nan = true;
> +  m_neg_nan = true;
> +  if (flag_checking)
> +    verify_range ();
> +}
> +
> +// Build a NAN of type TYPE with SIGN.
> +
> +inline void
> +frange::set_nan (tree type, bool sign)
> +{
> +  m_kind = VR_UNDEFINED;
>    m_type = type;
> -  m_min = r;
> -  m_max = r;
> -  m_props.set_varying ();
> -  m_props.nan_set_yes ();
> +  m_neg_nan = sign;
> +  m_pos_nan = !sign;
>    if (flag_checking)
>      verify_range ();
>  }
> @@ -1210,9 +1172,7 @@ frange::known_finite () const
>  {
>    if (undefined_p () || varying_p () || m_kind == VR_ANTI_RANGE)
>      return false;
> -  return (!real_isnan (&m_min)
> -         && !real_isinf (&m_min)
> -         && !real_isinf (&m_max));
> +  return (!maybe_nan () && !real_isinf (&m_min) && !real_isinf (&m_max));
>  }
>
>  // Return TRUE if range may be infinite.
> @@ -1242,7 +1202,7 @@ frange::known_inf () const
>  inline bool
>  frange::maybe_nan () const
>  {
> -  return !get_nan ().no_p ();
> +  return m_pos_nan || m_neg_nan;
>  }
>
>  // Return TRUE if range is a +NAN or -NAN.
> @@ -1250,7 +1210,7 @@ frange::maybe_nan () const
>  inline bool
>  frange::known_nan () const
>  {
> -  return get_nan ().yes_p ();
> +  return m_kind == VR_UNDEFINED && maybe_nan ();
>  }
>
>  // If the signbit for the range is known, set it in SIGNBIT and return
> @@ -1259,13 +1219,31 @@ frange::known_nan () const
>  inline bool
>  frange::known_signbit (bool &signbit) const
>  {
> -  // FIXME: Signed NANs are not supported yet.
> -  if (maybe_nan ())
> +  if (undefined_p ())
>      return false;
> -  if (get_signbit ().varying_p ())
> +
> +  // NAN with unknown sign.
> +  if (m_pos_nan && m_neg_nan)
>      return false;
> -  signbit = get_signbit ().yes_p ();
> -  return true;
> +  // No NAN.
> +  if (!m_pos_nan && !m_neg_nan)
> +    {
> +      if (m_min.sign == m_max.sign)
> +       {
> +         signbit = m_min.sign;
> +         return true;
> +       }
> +      return false;
> +    }
> +  // NAN with known sign.
> +  bool nan_sign = m_neg_nan;
> +  if (m_kind == VR_UNDEFINED
> +      || (nan_sign == m_min.sign && nan_sign == m_max.sign))
> +    {
> +      signbit = nan_sign;
> +      return true;
> +    }
> +  return false;
>  }
>
>  #endif // GCC_VALUE_RANGE_H
> --
> 2.37.1
>