Re: [PATCH] x86-64: Add memchr/rawmemchr/wmemchr optimized with SSE2/AVX2

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Fri, Jun 2, 2017 at 12:47 PM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Thu, Jun 1, 2017 at 8:44 AM, H.J. Lu <hongjiu.lu@intel.com> wrote:
>> SSE2 memchr is extended to support wmemchr.  AVX2 memchr/rawmemchr/wmemchr
>> are added to search 32 bytes with a single vector compare instruction.
>> AVX2 memchr/rawmemchr/wmemchr are as fast as SSE2 memchr/rawmemchr/wmemchr
>> for small sizes and up to 1.5X faster for larger sizes on Haswell and
>> Skylake.  Select AVX2 memchr/rawmemchr/wmemchr on AVX2 machines where
>> vzeroupper is preferred and AVX unaligned load is fast.
>>
>> Any comments?
>>
>> H.J.
>> ---
>>         * sysdeps/x86_64/memchr.S (MEMCHR): New.  Depending on if
>>         USE_AS_WMEMCHR is defined.
>>         (PCMPEQ): Likewise.
>>         (memchr): Renamed to ...
>>         (MEMCHR): This.  Support wmemchr if USE_AS_WMEMCHR is defined.
>>         Replace pcmpeqb with PCMPEQ.
>>         * sysdeps/x86_64/multiarch/Makefile (sysdep_routines): Add
>>         memchr-avx2, rawmemchr-avx2 and wmemchr-avx2.
>>         * sysdeps/x86_64/multiarch/ifunc-impl-list.c
>>         (__libc_ifunc_impl_list): Test __memchr_avx2, __memchr_sse2,
>>         __rawmemchr_avx2, __rawmemchr_sse2, __wmemchr_avx2 and
>>         __wmemchr_sse2.
>>         * sysdeps/x86_64/multiarch/memchr-avx2.S: New file.
>>         * sysdeps/x86_64/multiarch/memchr.S: Likewise.
>>         * sysdeps/x86_64/multiarch/rawmemchr-avx2.S: Likewise.
>>         * sysdeps/x86_64/multiarch/rawmemchr.S: Likewise.
>>         * sysdeps/x86_64/multiarch/wmemchr-avx2.S: Likewise.
>>         * sysdeps/x86_64/multiarch/wmemchr.S: Likewise.
>>         * sysdeps/x86_64/wmemchr.S: Likewise.
>
> Updated patch to implement IFUNC selector in C.
>
> --
> H.J.

I will check it in.

-- 
H.J.