[COMMITTED] Add frange::maybe_isnan (bool sign).

[Aldy Hernandez via Gcc-patches]

It is useful to know if there's the possiblity of a NAN with a given
sign.  This is to complement maybe_isnan(void) which returns TRUE for a
NAN of any sign.

A follow-up patch implementing ABS will make use of this.

gcc/ChangeLog:

        * value-range.h (frange::maybe_isnan): New.
---
 gcc/value-range.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/gcc/value-range.h b/gcc/value-range.h
index 484f911bd90..07a2067898c 100644
--- a/gcc/value-range.h
+++ b/gcc/value-range.h
@@ -323,6 +323,7 @@ public:
   bool known_isnan () const;
   bool known_isinf () const;
   bool maybe_isnan () const;
+  bool maybe_isnan (bool sign) const;
   bool maybe_isinf () const;
   bool signbit_p (bool &signbit) const;
 private:
@@ -1295,6 +1296,18 @@ frange::maybe_isnan () const
   return m_pos_nan || m_neg_nan;
 }
 
+// Return TRUE if range is possibly a NAN with SIGN.
+
+inline bool
+frange::maybe_isnan (bool sign) const
+{
+  if (undefined_p ())
+    return false;
+  if (sign)
+    return m_neg_nan;
+  return m_pos_nan;
+}
+
 // Return TRUE if range is a +NAN or -NAN.
 
 inline bool
-- 
2.37.3