This appeared during compile of the last weekly 4.4.0 snapshot in libjava compilation:

libtool: compile:  /var/tmp/portage/sys-devel/gcc-4.4.0_alpha20090215/work/build/./gcc/xgcc -B/var/tmp/portage/sys-devel/gcc-4.4.0_alpha20090215/work/build/./gcc/ -B/usr/x86_64-pc-linux-gnu/bin/ -B/usr/x86_64-pc-linux-gnu/lib/ -isystem /usr/x86_64-pc-linux-gnu/include -isystem /usr/x86_64-pc-linux-gnu/sys-include -DHAVE_CONFIG_H -I. -I/var/tmp/portage/sys-devel/gcc-4.4.0_alpha20090215/work/gcc-4.4-20090215/libjava/classpath/native/fdlibm -I../../include -fexceptions -fasynchronous-unwind-tables -g -O2 -march=nocona -pipe -MT dtoa.lo -MD -MP -MF .deps/dtoa.Tpo -c /var/tmp/portage/sys-devel/gcc-4.4.0_alpha20090215/work/gcc-4.4-20090215/libjava/classpath/native/fdlibm/dtoa.c  -fPIC -DPIC -o .libs/dtoa.o
/var/tmp/portage/sys-devel/gcc-4.4.0_alpha20090215/work/gcc-4.4-20090215/libjava/classpath/native/fdlibm/dtoa.c: In function ‘_Jv_dtoa_r’:
/var/tmp/portage/sys-devel/gcc-4.4.0_alpha20090215/work/gcc-4.4-20090215/libjava/classpath/native/fdlibm/dtoa.c:885: error: insn does not satisfy its constraints:
(insn 2428 2427 687 103 /var/tmp/portage/sys-devel/gcc-4.4.0_alpha20090215/work/gcc-4.4-20090215/libjava/classpath/native/fdlibm/dtoa.c:536 (set (reg:DF 26 xmm5 [orig:233 D.3242 ] [233])
        (mult:DF (reg:DF 26 xmm5 [orig:233 D.3242 ] [233])
            (reg:DF 0 ax))) 722 {*fop_df_comm_sse} (nil))
/var/tmp/portage/sys-devel/gcc-4.4.0_alpha20090215/work/gcc-4.4-20090215/libjava/classpath/native/fdlibm/dtoa.c:885: internal compiler error: in copyprop_hardreg_forward_1, at regrename.c:1603
Please submit a full bug report,
with preprocessed source if appropriate.

Reproducible on the preprocessed source using:

/var/tmp/portage/sys-devel/gcc-4.4.0_alpha20090215/work/build/./gcc/xgcc -B/var/tmp/portage/sys-devel/gcc-4.4.0_alpha20090215/work/build/./gcc/ -o dtoa.o dtoa.i -O2 -march=nocona