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

[Aldy Hernandez <aldyh@redhat.com>]

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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
>

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From 8bedd64a6b8df23caf78f5f411dc17e30ad35e88 Mon Sep 17 00:00:00 2001
From: Aldy Hernandez <aldyh@redhat.com>
Date: Fri, 26 Aug 2022 16:57:09 +0200
Subject: [PATCH] Add real_iszero to real.*

We have real_isnegzero but no real_iszero.  We could memcmp with 0,
but that's just ugly.

gcc/ChangeLog:

	* real.cc (real_iszero): New.
	* real.h (real_iszero): New.
---
 gcc/real.cc | 16 ++++++++++++++++
 gcc/real.h  |  6 ++++++
 2 files changed, 22 insertions(+)

diff --git a/gcc/real.cc b/gcc/real.cc
index f570ca8e85b..d362680fe9b 100644
--- a/gcc/real.cc
+++ b/gcc/real.cc
@@ -1272,6 +1272,22 @@ real_isneg (const REAL_VALUE_TYPE *r)
   return r->sign;
 }
 
+/* Determine whether a floating-point value X is plus or minus zero.  */
+
+bool
+real_iszero (const REAL_VALUE_TYPE *r)
+{
+  return r->cl == rvc_zero;
+}
+
+/* Determine whether a floating-point value X is zero with SIGN.  */
+
+bool
+real_iszero (const REAL_VALUE_TYPE *r, int sign)
+{
+  return real_iszero (r) && r->sign == sign;
+}
+
 /* Determine whether a floating-point value X is minus zero.  */
 
 bool
diff --git a/gcc/real.h b/gcc/real.h
index 76360b603fb..20d85378855 100644
--- a/gcc/real.h
+++ b/gcc/real.h
@@ -295,6 +295,12 @@ extern bool real_isneg (const REAL_VALUE_TYPE *);
 /* Determine whether a floating-point value X is minus zero.  */
 extern bool real_isnegzero (const REAL_VALUE_TYPE *);
 
+/* Determine whether a floating-point value X is plus or minus zero.  */
+extern bool real_iszero (const REAL_VALUE_TYPE *);
+
+/* Determine whether a floating-point value X is zero with SIGN.  */
+extern bool real_iszero (const REAL_VALUE_TYPE *, int sign);
+
 /* Test relationships between reals.  */
 extern bool real_identical (const REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *);
 extern bool real_equal (const REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *);
-- 
2.37.1