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Re: [PATCH] Rename __memcmp_sse4_2 to __memcmp_sse4_1.
- From: Matt Turner <mattst88 at gmail dot com>
- To: "H.J. Lu" <hjl dot tools at gmail dot com>
- Cc: Andreas Jaeger <aj at suse dot com>, GNU C Library <libc-alpha at sourceware dot org>, Liubov Dmitrieva <liubov dot dmitrieva at gmail dot com>
- Date: Wed, 10 Jul 2013 11:19:36 -0700
- Subject: Re: [PATCH] Rename __memcmp_sse4_2 to __memcmp_sse4_1.
- References: <CAMe9rOreowCOEH+6zRaRNk_p9sYe3T2bhwPRbKpybW9cO0BhJA at mail dot gmail dot com> <1373419029-19125-1-git-send-email-mattst88 at gmail dot com> <51DCE51F dot 7000001 at suse dot com> <CAMe9rOqb3_DnhSh0jPh9=suJo5c+WjegxfDh1+1go6pY+7+PLA at mail dot gmail dot com> <CAEdQ38Go4UY=k==nYT_6S86-tsOoxOO=Wn=8_pNk+LkkxSxU_Q at mail dot gmail dot com> <CAMe9rOpgaNgGSdoM5rXdhLT-TqVEJjGMyHgKRP=t+2LrSTpFAA at mail dot gmail dot com>
On Wed, Jul 10, 2013 at 11:16 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Wed, Jul 10, 2013 at 10:41 AM, Matt Turner <mattst88@gmail.com> wrote:
>> On Wed, Jul 10, 2013 at 8:30 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
>>> On Tue, Jul 9, 2013 at 9:37 PM, Andreas Jaeger <aj@suse.com> wrote:
>>>> On 07/10/2013 03:17 AM, Matt Turner wrote:
>>>>> It uses SSE 4.1 instructions (ptest) but no SSE 4.2 instructions.
>>>>
>>>> There are two parts to this: It should only run on cpus with those
>>>> instructions but we also need to ensure that it gives a better
>>>> performance on such cpus. HJ, Matt, please do run performance tests on a
>>>> variety of affected cpus to show that this change really helps in all cases,
>>>>
>>>> Andreas
>>>
>>> Only Penryn has SSE4.1 without SSE4.2. Liubov, can
>>> you compare performance of memcmp-sse4.S vs
>>> memcmp-ssse3.S on Penryn?
>>
>> Is it also the case that this path would now be used on Silvermont?
>
> It is used on Silvermont since it supports SSE4.2
>
> --
> H.J.
To confirm, setting bit_Slow_SSE4_2 on Silvermont (which we do)
wouldn't prevent this path from executing?