Обсуждение: [PATCH] More Coccinelli cleanups

Hi list,

Since my previous Coccinelle cleanup patches have gained positive
feedback I decided to try some more.

This time I wrote my own spatches.

patch 0001 turns (a - b == 0) into (a == b) and similarly with !=
patch 0002 applies the same to operators >, >=, <, <=

I'm well aware that there's a point where code cleanups defeat their
purpose and become a burden. So this will probably be my last one,
I'll go to doing productive things instead. :)

Regards,
Marti

On Fri, Oct 29, 2010 at 7:33 PM, Marti Raudsepp <marti@juffo.org> wrote:
> Since my previous Coccinelle cleanup patches have gained positive
> feedback I decided to try some more.
>
> This time I wrote my own spatches.
>
> patch 0001 turns (a - b == 0) into (a == b) and similarly with !=
> patch 0002 applies the same to operators >, >=, <, <=
>
> I'm well aware that there's a point where code cleanups defeat their
> purpose and become a burden. So this will probably be my last one,
> I'll go to doing productive things instead. :)

I like the 0002 patch better than the 0001 patch.  For example, consider:

-       while (q - (uint8 *) keybuf - 8)
+       while (q - (uint8 *) keybuf != 8)

That's pretty darn inscrutable either way, and the loop that follows
does absolutely nothing to clear anything up.  What's so special about
8?  Are we counting up to 8 or down to 8?  Most of these examples
involve an additive constant, or (in the case of zic.c) are parallel
to surrounding code that does similar tests with an additive constant.I'm pretty much inclined to think that these
examplesshould either
 
be left alone or given a more substantial face lift.  On the other
hand, most of the stuff in the 0002 patch takes this form:

-       if (p - tmpbuf > 0)
+       if (p > tmpbuf)

IMHO, that's an improvement.  However, I think that this rewrite
changes the overflow behavior.  There's a comment not too far from the
bgwriter.c change that seems to imply that the test is written the way
that it is specifically to produce a certain overflow behavior.  The
others all look OK, though, as far as I can tell.

-- 
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

Robert Haas <robertmhaas@gmail.com> writes:
> On Fri, Oct 29, 2010 at 7:33 PM, Marti Raudsepp <marti@juffo.org> wrote:
>> patch 0001 turns (a - b == 0) into (a == b) and similarly with !=
>> patch 0002 applies the same to operators >, >=, <, <=
>> 
>> I'm well aware that there's a point where code cleanups defeat their
>> purpose and become a burden. So this will probably be my last one,
>> I'll go to doing productive things instead. :)

> I like the 0002 patch better than the 0001 patch.

I'm not really thrilled with either of them, as I don't think they are
doing much to improve readability.  As for 0002, as you say, at least
the change in bgwriter.c is actively breaking things.  I'm not eager to
go through and see which of the other changes there might be affecting
overflow or signed-vs-unsigned comparison behavior.
        regards, tom lane