Crashing a lot when running with jprof

I'm trying to profile some stuff, and firefox is being very crashy when run with 
jprof. The crashes only happen when profiling is actually happening, not when 
it's paused. The console prints out a simple
./run-mozilla.sh: line 131:  6657 Segmentation fault      "$prog" ${1+"$@"}
when the crash happens.

I'm using the following .mozconfig:

. $topsrcdir/browser/config/mozconfig
mk_add_options MOZ_OBJDIR=@TOPSRCDIR@/obj-@CONFIG_GUESS@
ac_add_options --enable-optimize
ac_add_options --disable-debug
ac_add_options --enable-jprof

...and gcc 4.1.2 on Gentoo.

http://developer.mozilla.org/en/docs/Building_on_Fedora_Core_5 says to try
ac_add_options --enable-optimize="-O2 -fno-omit-frame-pointer"
I did, it didn't help.

Does anyone know what's wrong? Should I file a bug?

-- 
dolphinling
<http://dolphinling.net/>