When building avr-gcc from the CVS repository (trunk), configured as follows:
../gcc/configure --target=avr --enable-languages=c --disable-nls
I get an internal error:
/home/degay/avr-gcc-build/gcc/xgcc -B/home/degay/avr-gcc-build/gcc/
-B/usr/local/avr/bin/ -B/usr/local/avr/lib/ -isystem /usr/local/avr/include
-isystem /usr/local/avr/sys-include -O2  -DIN_GCC -DCROSS_COMPILE   -W -Wall
-Wwrite-strings -Wstrict-prototypes -Wmissing-prototypes -Wold-style-definition
 -isystem ./include  -DDF=SF -Dinhibit_libc -mcall-prologues -g  -DIN_LIBGCC2
-D__GCC_FLOAT_NOT_NEEDED -Dinhibit_libc -I. -I. -I../../gcc/gcc
-I../../gcc/gcc/. -I../../gcc/gcc/../include -I../../gcc/gcc/../libcpp/include 
-DL_fixdfdi -c ../../gcc/gcc/libgcc2.c -o libgcc/./_fixdfdi.o
../../gcc/gcc/libgcc2.c: In function '__fixdfdi':
../../gcc/gcc/libgcc2.c:1267: internal compiler error: in find_valid_class, at
reload.c:719