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Re: [PATCH] Rename __memcmp_sse4_2 to __memcmp_sse4_1.


On Wed, Jul 10, 2013 at 11:19 AM, Matt Turner <mattst88@gmail.com> wrote:
> 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?

I don't think so.  Liubov, can you verify it?

--
H.J.


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