The attached code causes the compiler to crash when compiled as follows:

pluto> gcc -c -O1 -ftree-vectorize m.c
m.c: In function ‘C’:
m.c:7: internal compiler error: Segmentation fault
Please submit a full bug report,
with preprocessed source if appropriate.
See <URL:http://gcc.gnu.org/bugs.html> for instructions.
pluto> gcc -v
Using built-in specs.
Target: x86_64-unknown-linux-gnu
Configured with: ../gcc/configure --prefix=/usr/local/gcc410
--enable-languages=c,c++,f95
Thread model: posix
gcc version 4.1.0 20050725 (experimental)

The code compiles OK with gcc 4.0.1