Another real.* tweak.  This time, adding a real_iszero() entry point
to match the real_isnegzero.  I could combine this patch with the
negative infinity one in this thread if y'all would prefer.

OK pending tests?

p.s. I'd really like to go and benchmark all this real.* stuff
(later), because I think we could inline a bunch of these functions in
the header file.

On Tue, Aug 23, 2022 at 12:33 PM Aldy Hernandez <aldyh@redhat.com> wrote:
>
> 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
>