Re: [PATCH] 2.4.22pre10: {,un}likely_p() macros for pointers

[Albert Cahalan]

On Mon, 2003-08-11 at 14:55, Andrew Morton wrote:
> Albert Cahalan <albert@xxxxxxxxxxxxxxxxxxxxx> wrote:
> >
> > -#define likely(x)	__builtin_expect((x),1)
> > -#define unlikely(x)	__builtin_expect((x),0)
> > +#define likely(x)	__builtin_expect(!!(x),1)
> > +#define unlikely(x)	__builtin_expect(!!(x),0)
> 
> Odd.  I thought we fixed that ages ago.
> 
> Being a simple soul, I prefer __builtin_expect((x) != 0, 1).

That's much harder to read. The !! is a nice
neat idiom. The other way requires a bit of thought.
(is that == or !=, a 0 or 1, and what does that
compute to?)

The !! is visually distinctive. It has only one use.
When you see it, you instantly know that a value is
being converted to the pure boolean form.



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