[boost] Re: call_traits vs type_traits

From: John Maddock (John_Maddock_at_[hidden])
Date: 1999-12-02 07:55:09

Howard -

>My x86 assembly is a little rusty.  I don't see the loop (where is EDX 
getting decremented?).  If this is the loop body and you've edited out 
the loop, then the by-value looks like a very big win to me for this 
platform.  Is this with optimizations turned on?<

Yes thats just the loop body for the 

*out = value;

assignment, everything else was the same for the byref/byvalue versions,
and yes that's with all optimisations turned on.

> Of course, it's possible to generate (or at least write by hand) _much_
faster code for an Intel CPU than this, in this specific case (using
REP STOSx ), but I don't know how many compiler optimisers are currently
that smart. (But then again, what we're doing here is trying to "design in"
optimiser hints, isn't it? :-)<

Exactly, I really wish that Wintel standard library ports included
specialisations for std::copy/fill/fill_n/unitialized_copy/unitialised_fill
etc etc, some of these could be much much more efficiently dealt with in
assembly for built in types - and it wouldn't actually require many
assembly functions either.  Still I can dream I guess :-)

- John.