Re: i386 inline-asm string functions - some questions

[Daniel Jacobowitz <drow@mvista.com>]

On Sun, Dec 28, 2003 at 07:56:54PM -0800, Zack Weinberg wrote:
> Ulrich Drepper <drepper@redhat.com> writes:
> 
> > Zack Weinberg wrote:
> >> I once tried to get Uli to take them out again, with
> >> hard numbers to back me up, but he ignored me.
> >
> > I have absolutely no problem taking out the inlines once gcc is able to
> > perform the same optimizations.  Problem is that nobody spent the time
> > so far to complete the task in gcc.
> 
> This is true - I believe Joseph Myers put a list of yet-to-be-done
> optimizations on the GCC projects page ...
> 
> > As far as I know each function we still have has an advantage over
> > the gcc code.
> 
> ... however, that advantage is only theoretical.  Experiments such as
> Peter Zaitsev's just now, and mine several years ago, demonstrate that
> the bits/string.h and bits/string2.h inlines make code worse, not better.
> Therefore they should be removed.

Funny, I conducted this experiment last week and found quite the
opposite.  Compiling the demangler and a smallish yacc parser
with -D__NO_STRING_INLINES cost about 20% in runtime.

I'm not convinced.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer