On Wed, 2020-04-22 at 11:20 -0700, Carl Love wrote:
> GCC maintainers:
>
Hi,
> The following is a trivial patch to fix a comment describing the
> intrinsic function _mm_movemask_epi8. The comment was expanded to
> clarify the layout of the returned result.
Something seems wrong there, see below.
>
> The patch does not make any functional changes.
>
> Please let me know if the patch is OK for mainline and backporting as
> appropriate.
>
> Thanks.
>
> Carl Love
> -------------------------------------------
> rs6000, Fix header comment for intrinsic function _mm_movemask_epi8
>
> gcc/ChangeLog
>
> 2020-04-22 Carl Love <c...@us.ibm.com>
>
> * config/rs6000/emmintrin.h (_mm_movemask_epi8): Fix comment
> for the
> function.
drop /for the function/
>
> Signed-off-by: Carl Love <ca...@us.ibm.com>
> ---
> gcc/config/rs6000/emmintrin.h | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/gcc/config/rs6000/emmintrin.h
> b/gcc/config/rs6000/emmintrin.h
> index 2462cf5bdac..0872a75c0de 100644
> --- a/gcc/config/rs6000/emmintrin.h
> +++ b/gcc/config/rs6000/emmintrin.h
> @@ -2033,7 +2033,9 @@ _mm_min_epu8 (__m128i __A, __m128i __B)
> #ifdef _ARCH_PWR8
> /* Intrinsic functions that require PowerISA 2.07 minimum. */
>
> -/* Creates a 4-bit mask from the most significant bits of the SPFP
> values. */
> +/* Creates a 16-bit mask from the most significant bits of the
> sixteen 8-bit
> + values. The 16-bit result is placed in bits[48:63], bits [0:47]
> and
> + bits [64:127] are set to zero. */
That function returns an int out of one of the elements of the result
vector.
extern __inline int __attribute__((__gnu_inline__, __always_inline__,
__artificial__))
_mm_movemask_epi8 (__m128i __A)
{
...
__vector unsigned long long result;
...
So the description of the intermediate __vector unsigned long long
variable, if actually needed, would fit better near the assignment to
result.
result = ((__vector unsigned long long)
vec_vbpermq ((__vector unsigned char) __A,
(__vector unsigned char) perm_mask));
But then you would probably want to clarify that the return is only one
of those long long vector elements.
#ifdef __LITTLE_ENDIAN__
return result[1];
#else
return result[0];
#end
if
thanks,
-Will
> extern __inline int __attribute__((__gnu_inline__,
> __always_inline__, __artificial__))
> _mm_movemask_epi8 (__m128i __A)
> {
