Re: [PATCH] More Coccinelli cleanups

On Fri, Oct 29, 2010 at 7:33 PM, Marti Raudsepp <marti(at)juffo(dot)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 examples should 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
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