[PATCH] x86-64: Optimize strrchr/wcsrchr with AVX2

[H.J. Lu]

On Thu, Jun 1, 2017 at 11:42 AM, Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
> On 01/06/2017 15:14, H.J. Lu wrote:
>> Optimize strrchr/wcsrchr with AVX2 to check 32 bytes with vector
>> instructions.  It is as fast as SSE2 version for small data sizes
>> and up to 1X faster for large data sizes on Haswell.  Select AVX2
>> version 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
>>       strrchr-avx2 and wcsrchr-avx2.
>>       * sysdeps/x86_64/multiarch/ifunc-impl-list.c
>>       (__libc_ifunc_impl_list): Add tests for __strrchr_avx2,
>>       __strrchr_sse2, __wcsrchr_avx2 and __wcsrchr_sse2.
>>       * sysdeps/x86_64/multiarch/strrchr-avx2.S: New file.
>>       * sysdeps/x86_64/multiarch/strrchr.S: Likewise.
>
> I think this could be an opportunity to avoid adding more assembly ifunc
> written in assembly and use C implementation instead.

Good idea.  Here is the updated patch.

Thanks.

-- 
H.J.
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