bug#17229: [PATCH 2/2] grep: speed-up by using memchr() in Boyer-Moore searching

[Paul Eggert]

On 04/09/2014 06:54 AM, Norihiro Tanaka wrote:
> memchr() of glibc is faster than seeking by delta1 on some platforms.
> So, when there is no chance to match for a while, use it on them.
>
> Speed-up about 3x in best case, 10% in normal case by this patch.
>
> It's still available only for x86 and x86-64 platform.

Thanks, I have some questions about this one.

What benchmark did you use to time this?

THe patch refers to a variable called 'trans' that is not in the current 
savannah git master.  Is there some other patch that establishes this 
variable, a patch that is a prerequisite for this one?  If trans is a 
cached copy of kwset->trans, isn't that guaranteed to be NULL here?

What is delta1?  It's mentioned in a comment but not in the code.

It'd be simpler to use memchr on all platforms; is there a major 
performance downside to that?  For example, what about the attached 
patch instead?  It also simplifies things a bit to avoid a label and its 
associated gotos, under the assumption that trans is NULL here.

memchr.diff
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