[PATCH 1/2] s_sincosf.h: Change pio4 type to float [BZ #28713]

[H.J. Lu]

On Tue, Dec 21, 2021 at 12:52 AM Paul Zimmermann
<Paul.Zimmermann@inria.fr> wrote:
>
>        Dear H.J.,
>
> I confirm the 6 failures with gcc12, and that they are fixed by that patch.
>
> I suggest one small change: replace pio4 = 0x1.921FB54442D18p-1 by
> pio4 = 0x1.921fb6p-1f, where 0x1.921fb6p-1 is pi/4 rounded to nearest
> in binary32, and the 'f' suffix denotes a float constant.
>
> LGTM with that small change.

This is the patch I am checking in with

-static const double pio4 = 0x1.921FB54442D18p-1;
+static const float pio4 = 0x1.921FB6p-1f;

Thanks.

> Paul
>
> > Date: Mon, 20 Dec 2021 15:18:16 -0800
> > From: "H.J. Lu via Libc-alpha" <libc-alpha@sourceware.org>
> > Cc: Joseph Myers <joseph@codesourcery.com>
> >
> > s_cosf.c and s_sinf.c have
> >
> >   if (abstop12 (y) < abstop12 (pio4))
> >
> > where abstop12 takes a float argument, but pio4 is static const double.
> > pio4 is used only in calls to abstop12 and never in arithmetic.  Change
> > it to float to fix:
> >
> > FAIL: math/test-float-cos
> > FAIL: math/test-float-sin
> > FAIL: math/test-float-sincos
> > FAIL: math/test-float32-cos
> > FAIL: math/test-float32-sin
> > FAIL: math/test-float32-sincos
> >
> > when compiling with GCC 12.
> > ---
> >  sysdeps/ieee754/flt-32/s_sincosf.h | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/sysdeps/ieee754/flt-32/s_sincosf.h b/sysdeps/ieee754/flt-32/s_sincosf.h
> > index 125ab7f846..0dadd6374e 100644
> > --- a/sysdeps/ieee754/flt-32/s_sincosf.h
> > +++ b/sysdeps/ieee754/flt-32/s_sincosf.h
> > @@ -24,7 +24,7 @@
> >  /* 2PI * 2^-64.  */
> >  static const double pi63 = 0x1.921FB54442D18p-62;
> >  /* PI / 4.  */
> > -static const double pio4 = 0x1.921FB54442D18p-1;
> > +static const float pio4 = 0x1.921FB54442D18p-1;
> >
> >  /* Polynomial data (the cosine polynomial is negated in the 2nd entry).  */
> >  extern const sincos_t __sincosf_table[2] attribute_hidden;
> > --
> > 2.33.1
> >
> >



-- 
H.J.
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