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

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);

gcc/ChangeLog:

	* real.cc (real_isinf): New overload.
	(real_inf): Add sign argument.
	* real.h (real_isinf): New overload.
	(real_inf): Add sign argument.

1 files changed, 4 insertions, 1 deletions

diff --git a/gcc/real.h b/gcc/real.h
index 845ef29..e01f9ed 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 *, bool 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 *, bool sign = false);
 
 extern bool real_nan (REAL_VALUE_TYPE *, const char *, int, format_helper);