On macro vs. function (was Re: [xml] XPath extension API)

["Peter Jacobi" <pj walter-graphtek com>]

Hi Daniel, All,

> > This is what I'm doing for EXSLT. Code is easier to read and functions
> > are easier to reuse.
>
>   Only drawback it make more function calls ... on the other hand it will
> probably make the code more compact, being nicer on the cache probably
> compensates the effect. And maintenance will be easier. Okay go for it !
 
My timings on various Intel boxes (Watcom compiler) show the function 
call overhead to be 6 to 7 cycles, 30ns on the slowest box. And I had to 
disable automatic inlining of short functions to see a difference at all.

(Processors without branch prediction or compilers without register 
argument passing may give significantly worse results)

So I would vote against the use of macros for everything which is not 
called at least once per character.

Regards,
Peter Jacobi