-Os is implemented very bad

[Artem S. Tashkinov]

After comminiting some tests over gcc optimization flags I revealed that -Os flag is somewhat better than -O2 and -O3 flags due to decreased binaries sizes. But when I used this flag to compile QT 3.1.1 xfree library I got very unstable library: I got _numerous_ 'uic' segfaults by compiling KDE 3.1 (especially kdebase) and KDE itself segfaults almost after _every_ application exit.
I'm running RedHat 7.3 compatible distributive with glibc-2.2.5 and gcc-3.2.2. I used -Os flag to compile qt and -Os -mmmx -march=i686 to compile all other libraries (including libpng-1.2.5 and others). As far as I noticed _only_ KDE applications segfault and qt applications (uic and qtconfig). All other libraries work just fine (icculus Quake2, libpng, libxml2, libxslt, bzip2, zip, gzip, cups).
I can send you my binaries if you'd like to test them (though they are all stripped)

I hope you'll help me
Artem Tashkinov, system administrator