[PATCH v2] x86: Remove __mmask intrinsics in strstr-avx512.c

[Sunil Pandey]

On Mon, Jul 11, 2022 at 3:38 PM Noah Goldstein via Libc-alpha
<libc-alpha@sourceware.org> wrote:
>
> Using standard operators generates and the same code and __mmask
> instrinsics are not available before GCC7.
>
> Removed:
>     _cvtmask64_u64
>     _kshiftri_mask64
>     _kand_mask64
> ---
>  sysdeps/x86_64/multiarch/strstr-avx512.c | 16 ++++++++++------
>  1 file changed, 10 insertions(+), 6 deletions(-)
>
> diff --git a/sysdeps/x86_64/multiarch/strstr-avx512.c b/sysdeps/x86_64/multiarch/strstr-avx512.c
> index 2ab9e96db8..e44c1a05dc 100644
> --- a/sysdeps/x86_64/multiarch/strstr-avx512.c
> +++ b/sysdeps/x86_64/multiarch/strstr-avx512.c
> @@ -26,6 +26,10 @@
>  #define ZMM_SIZE_IN_BYTES 64
>  #define PAGESIZE 4096
>
> +#define cvtmask64_u64(...) (uint64_t) (__VA_ARGS__)
> +#define kshiftri_mask64(x, y) ((x) >> (y))
> +#define kand_mask64(x, y) ((x) & (y))
> +
>  /*
>   Returns the index of the first edge within the needle, returns 0 if no edge
>   is found. Example: 'ab' is the first edge in 'aaaaaaaaaabaarddg'
> @@ -133,15 +137,15 @@ __strstr_avx512 (const char *haystack, const char *ned)
>    __m512i hay0 = _mm512_maskz_loadu_epi8 (loadmask, haystack + hay_index);
>    /* Search for NULL and compare only till null char */
>    uint64_t nullmask
> -      = _cvtmask64_u64 (_mm512_mask_testn_epi8_mask (loadmask, hay0, hay0));
> +      = cvtmask64_u64 (_mm512_mask_testn_epi8_mask (loadmask, hay0, hay0));
>    uint64_t cmpmask = nullmask ^ (nullmask - ONE_64BIT);
> -  cmpmask = cmpmask & _cvtmask64_u64 (loadmask);
> +  cmpmask = cmpmask & cvtmask64_u64 (loadmask);
>    /* Search for the 2 charaters of needle */
>    __mmask64 k0 = _mm512_cmpeq_epi8_mask (hay0, ned0);
>    __mmask64 k1 = _mm512_cmpeq_epi8_mask (hay0, ned1);
> -  k1 = _kshiftri_mask64 (k1, 1);
> +  k1 = kshiftri_mask64 (k1, 1);
>    /* k2 masks tell us if both chars from needle match */
> -  uint64_t k2 = _cvtmask64_u64 (_kand_mask64 (k0, k1)) & cmpmask;
> +  uint64_t k2 = cvtmask64_u64 (kand_mask64 (k0, k1)) & cmpmask;
>    /* For every match, search for the entire needle for a full match */
>    while (k2)
>      {
> @@ -178,13 +182,13 @@ __strstr_avx512 (const char *haystack, const char *ned)
>        hay0 = _mm512_loadu_si512 (haystack + hay_index);
>        hay1 = _mm512_load_si512 (haystack + hay_index
>                                  + 1); // Always 64 byte aligned
> -      nullmask = _cvtmask64_u64 (_mm512_testn_epi8_mask (hay1, hay1));
> +      nullmask = cvtmask64_u64 (_mm512_testn_epi8_mask (hay1, hay1));
>        /* Compare only till null char */
>        cmpmask = nullmask ^ (nullmask - ONE_64BIT);
>        k0 = _mm512_cmpeq_epi8_mask (hay0, ned0);
>        k1 = _mm512_cmpeq_epi8_mask (hay1, ned1);
>        /* k2 masks tell us if both chars from needle match */
> -      k2 = _cvtmask64_u64 (_kand_mask64 (k0, k1)) & cmpmask;
> +      k2 = cvtmask64_u64 (kand_mask64 (k0, k1)) & cmpmask;
>        /* For every match, compare full strings for potential match */
>        while (k2)
>          {
> --
> 2.34.1
>

LGTM

Reviewed-by: Sunil K Pandey <skpgkp2@gmail.com>