Re: [PATCH] memchr (trivial) optimization

[Ingo Oeser <ioe-lkml@rameria.de>]

On Wednesday 22 August 2007, lode leroy wrote:
> While profiling something completely unrelated, I noticed
> that on the workloads I used memchr for, I saw a 30%-40% improvement
> in performance, with the following trivial changes...
> (basically, it saves 3 operations for each call)

Yes, but then you could be a bit more explicit to the compiler
on what you are doing here:
 
void *memchr(const void *s, int c, size_t n)
{
	const unsigned char *p = s;

	for (; n != 0; n--, p++) {
               if ((unsigned char)c == *p) {
                       return (void *)p;
	}
	return NULL;
}

Now the compiler should see the loop more clearly.


Best Regards

Ingo Oeser