Re: i386 inline-asm string functions - some questions

"Zack Weinberg" <[email protected]> Sun, 28 Dec 2003 21:55:33 -0800
Newsgroups org.kernel.vger.linux-gcc
Message-ID <[email protected]>
> > ... 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.

That's interesting.  My testing was with much larger programs where
str* / mem* aren't the bottleneck anyway.  I wonder if you would be
willing to take a look at the differences in the assembly language
and see where that 20% is coming from.

zw