Re: [PATCH v6 2/2] refs.c: SSE4.2 optimizations for check_refname_component

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 4, 2014, 21:46 UTC
Message-ID: <xmqqsinktkjv.fsf@gitster.dls.corp.google.com>
In-Reply-To: <1401916476.18134.165.camel@stross>

David Turner <dturner@twopensource.com> writes:

> On Wed, 2014-06-04 at 10:04 +0200, Torsten Bögershausen wrote:
> [snip discussion of compiler flags; I'll look into a cpuid approach]

Hmmmm, I am not sure if the complexity is really worth it.

In any case, [PATCH 1/2] is fairly uncontroversial, so I am inclined to queue it by itself early without waiting for the discussion on 2/2 to settle.

>> The name check_refname_component_1() doesn't tell too much,
>> (check_refname_component_sse42()  or check_refname_component_nonsse42() say more)
>
> I'll go with "_bytewise", since that's how it works.

That naming assumes that there will never be any alternative implementation of the bytewise checker other than the one that uses sse42, no?

Show 5 quoted lines

>> can I suggest to move all SSE code out to a file under compat/,
>> like compat/refs_sse42.c, or something similar ?
>
> Since this is a relatively small section of code, I think that would be
> overkill.  Does anyone else have an opinion?

If we foresee people on other architectures to invent different vectorized implementations on their favourite archs, we may end up separating it out into compat/. I have no opinion on how likely that will happen, though, and because this is a small piece of code right now, it shouldn't be too painful to reorganize when the time comes.