Re: [KJ] Correct imprecise >= comparisons

[Matthew Wilcox <matthew@wil.cx>]

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On Thu, Feb 09, 2006 at 01:20:07PM +0100, Andreas Mohr wrote:
> > > if (val >= max)
> > >   val = max;
> > > 
> > > which can instead be expressed as
> > > 
> > > if (val > max)
> > >   val = max;
> > >
> > > in order to cut down on both executed cycles and cache write invalidation.
> > 
> > I am wondering if it is actually worth the effort, since it seems to
> > me as if this would normally be an exception that val >= max. And
> > instead of returning with an error or aborting you normalize the value.
> 
> It probably is unlikely in several cases, but that makes it all the more a
> janitorial effort ;)
> It's just "unclean" to set a variable's limit if it didn't even actually
> step beyond the limit, which makes this more or less a janitorial task.

I wonder if we want a macro similar to min()/max().  Maybe we could
write it as:

limit(val, max);

which could be defined as:

#define limit(val, max)  { \
	typeof(val) _val = (val); typeof(max) _max = (max); \
	if (_val > _max) _val = _max; }

Thoughts?

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