Re: [PATCH] xdiff: optimise for no whitespace difference when ignoring whitespace.

From: Dylan Reid <dgreid@gmail.com>
Date: Jul 5, 2010, 12:34 UTC
Message-ID: <AANLkTinmdeTSRVCTblnGrG5lGpNKCiYIb8BO8jMhajXW@mail.gmail.com>
In-Reply-To: <4C319931.4020603@drmicha.warpmail.net>

On Mon, Jul 5, 2010 at 4:34 AM, Michael J Gruber <git@drmicha.warpmail.net> wrote:

Show 11 quoted lines

> Dylan Reid venit, vidit, dixit 05.07.2010 08:06:
>> Invert the order of the memcmp and flag check are done in xdl_recmatch,
>
> I was wondering whether you describe old (before patch) or new (after
> patch) here. Maybe one of the following is clearer:
>
> "Invert the order of the memcmp and flag check which are done in
> xdl_recmatch,"
>
> "Invert the order of the memcmp and flag check in xdl_recmatch,"
>

I'll make that more clear.

Show 5 quoted lines

>> +     if (s1 == s2 && !memcmp(l1, l2, s1))
>> +             return 1;
>> +     else if (!(flags & XDF_WHITESPACE_FLAGS))
>
> You can do without the "else" here.

sure can, will do.

Show 9 quoted lines

>> +             return 0;
>>
>>       i1 = 0;
>>       i2 = 0;
>
> BTW: How did you find this? Are you profiling parts of git?
>
> Michael
>

I was looking to add an unrelated feature and just happened to notice this. It was a really cheap change for a good speedup.

Thanks,

Dylan