[PATCH] Add set/get functions for negative infinity in real.*

[Aldy Hernandez via Gcc-patches]

For the frange implementation with endpoints I'm about to contribute,
we need to set REAL_VALUE_TYPEs with negative infinity.  The support
is already there in real.cc, but it is awkward to get at.  One could
call real_inf() and then negate the value, but I've added the ability
to pass the sign argument like many of the existing real.* functions.

I've declared the functions in such a way to avoid changes to the
existing code base:

// Unchanged function returning true for either +-INF.
bool real_isinf (const REAL_VALUE_TYPE *r);
// New overload to be able to specify the sign.
bool real_isinf (const REAL_VALUE_TYPE *r, int sign);
// Replacement function for setting INF, defaults to +INF.
void real_inf (REAL_VALUE_TYPE *, int sign = 0);

Tested on x86-64 Linux.

OK?

gcc/ChangeLog:

        * real.cc (real_isinf): New overload.
        (real_inf): Add sign argument.
        * real.h (real_isinf): New overload.
        (real_inf): Add sign argument.
---
 gcc/real.cc | 14 +++++++++++---
 gcc/real.h  |  5 ++++-
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/gcc/real.cc b/gcc/real.cc
index 4e63b1449c5..f570ca8e85b 100644
--- a/gcc/real.cc
+++ b/gcc/real.cc
@@ -1234,6 +1234,14 @@ real_isinf (const REAL_VALUE_TYPE *r)
   return (r->cl == rvc_inf);
 }
 
+/* Determine whether a floating-point value X is infinite with SIGN.  */
+
+bool
+real_isinf (const REAL_VALUE_TYPE *r, int sign)
+{
+  return real_isinf (r) && r->sign == sign;
+}
+
 /* Determine whether a floating-point value X is a NaN.  */
 
 bool
@@ -2484,12 +2492,12 @@ dconst_sqrt2_ptr (void)
   return &value;
 }
 
-/* Fills R with +Inf.  */
+/* Fills R with Inf with SIGN.  */
 
 void
-real_inf (REAL_VALUE_TYPE *r)
+real_inf (REAL_VALUE_TYPE *r, int sign)
 {
-  get_inf (r, 0);
+  get_inf (r, sign);
 }
 
 /* Fills R with a NaN whose significand is described by STR.  If QUIET,
diff --git a/gcc/real.h b/gcc/real.h
index 845ef29e3a4..76360b603fb 100644
--- a/gcc/real.h
+++ b/gcc/real.h
@@ -277,6 +277,9 @@ extern bool real_compare (int, const REAL_VALUE_TYPE *, 
const REAL_VALUE_TYPE *)
 /* Determine whether a floating-point value X is infinite.  */
 extern bool real_isinf (const REAL_VALUE_TYPE *);
 
+/* Determine whether a floating-point value X is infinite with SIGN.  */
+extern bool real_isinf (const REAL_VALUE_TYPE *, int sign);
+
 /* Determine whether a floating-point value X is a NaN.  */
 extern bool real_isnan (const REAL_VALUE_TYPE *);
 
@@ -331,7 +334,7 @@ extern long real_to_target (long *, const REAL_VALUE_TYPE 
*, format_helper);
 extern void real_from_target (REAL_VALUE_TYPE *, const long *,
                              format_helper);
 
-extern void real_inf (REAL_VALUE_TYPE *);
+extern void real_inf (REAL_VALUE_TYPE *, int sign = 0);
 
 extern bool real_nan (REAL_VALUE_TYPE *, const char *, int, format_helper);
 
-- 
2.37.1