[PATCH] x86-64: Optimize memrchr with AVX2

[H.J. Lu]

On Thu, Jun 1, 2017 at 11:13 AM, H.J. Lu <hongjiu.lu@intel.com> wrote:
> Optimize memrchr with AVX2 to search 32 bytes with a single vector
> compare instruction.  It is as fast as SSE2 memrchr for small data
> sizes and up to 1X faster for large data sizes on Haswell.  Select
> AVX2 memrchr on AVX2 machines where vzeroupper is preferred and AVX
> unaligned load is fast.
>
> Any comments?
>
> H.J.
> --
>         * sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
>         memrchr-avx2.
>         * sysdeps/x86_64/multiarch/ifunc-impl-list.c
>         (__libc_ifunc_impl_list): Add tests for __memrchr_avx2 and
>         __memrchr_sse2.
>         * sysdeps/x86_64/multiarch/memrchr-avx2.S: New file.
>         * sysdeps/x86_64/multiarch/memrchr.S: Likewise.

Updated patch with IFUNC selector in C.


-- 
H.J.
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