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

[Adhemerval Zanella]

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.