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

[Paul Zimmermann]

       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.

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
> 
>