[PATCH v2 2/5] x86 long double: Support pseudo numbers in isnanl

[Adhemerval Zanella]

On 23/12/2020 08:55, Siddhesh Poyarekar wrote:
> This syncs up isnanl behaviour with gcc.  Also move the isnanl
> implementation to sysdeps/x86 and remove the sysdeps/x86_64 version.

LGTM, thanks.

Reviewed-by: Adhemerval Zanella  <adhemerval.zanella@linaro.org>

> ---
>  sysdeps/{i386 => x86}/fpu/s_isnanl.c | 12 +++++++-----
>  sysdeps/x86_64/fpu/s_isnanl.c        |  1 -
>  2 files changed, 7 insertions(+), 6 deletions(-)
>  rename sysdeps/{i386 => x86}/fpu/s_isnanl.c (76%)
>  delete mode 100644 sysdeps/x86_64/fpu/s_isnanl.c
> 
> diff --git a/sysdeps/i386/fpu/s_isnanl.c b/sysdeps/x86/fpu/s_isnanl.c
> similarity index 76%
> rename from sysdeps/i386/fpu/s_isnanl.c
> rename to sysdeps/x86/fpu/s_isnanl.c
> index fb97317bc9..45541df08a 100644
> --- a/sysdeps/i386/fpu/s_isnanl.c
> +++ b/sysdeps/x86/fpu/s_isnanl.c
> @@ -28,16 +28,18 @@ static char rcsid[] = "$NetBSD: $";
>  
>  int __isnanl(long double x)
>  {
> -	int32_t se,hx,lx;
> +	int32_t se,hx,lx,pn;
>  	GET_LDOUBLE_WORDS(se,hx,lx,x);
>  	se = (se & 0x7fff) << 1;
> -	/* The additional & 0x7fffffff is required because Intel's
> -	   extended format has the normally implicit 1 explicit
> -	   present.  Sigh!  */
> +	/* Detect pseudo-normal numbers, i.e. exponent is non-zero and the top
> +	   bit of the significand is not set.   */
> +	pn = (uint32_t)((~hx & 0x80000000) & (se|(-se)))>>31;
> +	/* Clear the significand bit when computing mantissa.  */
>  	lx |= hx & 0x7fffffff;
>  	se |= (uint32_t)(lx|(-lx))>>31;
>  	se = 0xfffe - se;
> -	return (int)((uint32_t)(se))>>16;
> +
> +	return (int)(((uint32_t)(se)) >> 16) | pn;
>  }
>  hidden_def (__isnanl)
>  weak_alias (__isnanl, isnanl)
> diff --git a/sysdeps/x86_64/fpu/s_isnanl.c b/sysdeps/x86_64/fpu/s_isnanl.c
> deleted file mode 100644
> index 06e69c3aeb..0000000000
> --- a/sysdeps/x86_64/fpu/s_isnanl.c
> +++ /dev/null
> @@ -1 +0,0 @@
> -#include <sysdeps/i386/fpu/s_isnanl.c>
>