(FC4) x86_64 GCC and building 32bit apps

[Marcus Hartig]

Hello,

after reading the article "GNU Compiler Collection: Performance under 
Linux" in the actual c't magazine http://www.heise.de/ct/
I decided to recompile my 32bit Fedora firefox 1.0.1 with better CFLAGS 
like in the big GCC test read. And -Os was very slow there...

They have better performance results with FC3 GCC 3.4.3 and e.g LAME with 
the SSE extensions on 32bit. About 3 min. faster LAME encoding 17 wavs 
with SSE activated....

So I have installed all needed i386 pkgs (i think) from X11, glibc to 
required gnome things on my up2date x86_64 FC4 rawhide. But I get always 
errors compiling firefox or building the rpm about the ld complaining an 
uncompatible 64bit obj or not finding the X11 extensions.

Why is the GCC 3.4.3-20 not using the 32bit libs, I see he use the 64bit 
gnome ones while compiling, when I give him -m32 in mozconfig and or tried 
in the firefox spec file:

[...]
ac_add_options --enable-optimize="-O2 -m32 -msse2 -mtune=athlon64 
-march=athlon-xp"
...
ac_add_options --x-libraries=/usr/X11R6/lib
ac_add_options --libdir=/usr/lib
ac_add_options --x-includes=/usr/X11R6/include

What is here wrong? Or which switch is needed for GCC building and 
searching 32bit libs/apps? Why is it searching in ../lib64?


Greetings,
Marcus