Re: Overhead for type conversions?

["Warren W. Gay VE3WWG" <ve3wwg@cogeco.ca>]

"Nick Roberts" <nickroberts@blueyonder.co.uk> wrote in message news:bfu83g$ibodl$1@ID-25716.news.uni-berlin.de...
> "Bobby D. Bryant" <bdbryant@mail.utexas.edu> wrote in message
> news:pan.2003.07.25.01.01.43.5699@mail.utexas.edu...
>
> > Given these declarations -
> >
> >    type f1 is new float;
> >    type f2 is new float;
> >
> >    function "*"( left : in f1; right : in f2 ) return f1 is
> >    begin
> >       return( left * f1( right ) );
> >    end "*";
> >
...
> I would also suggest that a function like this should be declared inline,
> since it is likely that the eliminated call and return code would be bigger
> (as well as much slower) than the intrinsic code for the multiplication
> anyway.

I once suggested something like this to Simon Wright regarding
some procedure/function calls within the Booch Components. He
did some profiling, and discovered that inlining that I suggested
actually worsened the performance slightly under Linux. I don't
know if he did more investigations along this line, but for
the examples that I suggested, it actually made things worse
(due to instruction caching reasons I expect).

So inlining should probably be tested before the conclusion is
made. Furthermore, inlining on one platform may hurt another
platform's performance (which is a difficult portability issue
to deal with in the source code without a preprocessor).

Perhaps a platform sensitive pragma Inline is called for? ;-)

-- 
Warren W. Gay VE3WWG
http://home.cogeco.ca/~ve3wwg