Re: coccinelle: merge two rules from flex_alloc.cocci

From: Junio C Hamano <gitster@pobox.com>
Date: Nov 15, 2019, 05:13 UTC
Message-ID: <xmqq5zjl90y3.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <20191114163527.GT4348@szeder.dev>

SZEDER Gábor <szeder.dev@gmail.com> writes:

Show 16 quoted lines

> On Thu, Nov 14, 2019 at 09:15:47AM +0100, Markus Elfring wrote:
>> > If you could have some before/after numbers, that would be cool.
>> 
>> Does any test infrastructure (or benchmarks) exist which you would trust for
>> corresponding comparisons of software run time characteristics?
>
> Yes, just run:
>
>   make cocciclean
>   time make contrib/coccinelle/flex_alloc.cocci.patch
>
> before and after your changes, and include the timing results in the
> commit message if there is a notable difference.  If it gets faster,
> great!  If it gets slower, then update the commit message with a
> convincing argument about why the change is worth the performance
> penalty.

Also, the contents of the *.patch file before and after the change needs to match, but for that test to be meaningful, you'd need to resurrect the problems we fixed with the help of the existing cocci scripts (otherwise, the resulting *.patch file being empty does not prove much---our source may now be too clean to demonstrate the difference of the before/after rules).

Thanks.