strcspn(3) complexity improvement

[Brooks Davis]

On Tue, Apr 05, 2005 at 08:46:50PM -0700, Matthew Dillon wrote:
> :The real question I have is, how long does the string need to be before
> :this is a win and how much does it hurt for typical string lengths?
> :I've written code with strcspn that needed to perform well, but it was
> :parsing 80-column punch card derived formats.
> 
>      I think the answer is to not use strcspn() in cases where it *really*
>      matters.

Certainly.  strcspn() wasn't worth optimizing out after I replaced the
hand coded crap that used getc to parse files up to 100MB is size and
did a realloc for each character!  That got me a 50% speedup in overall
execution time and the function dropped from #1 to <#50 in the
profiling numbers.  At that point FPU intensive code was at the top
where it belonged.

My main point was to avoid a purely theoretical "optimization".

-- Brooks

-- 
Any statement of the form "X is the one, true Y" is FALSE.
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