I found that when I emerged libcaca 0.99 beta 16, I got 2 ICEs in demo.c 
and demo0.c. After some code cutting I got down to [attached demo.i]. Note that 
draw_circle isn't defined, it was a "real" function in libcaca's 
demo.c. Also, the there's an "-O" flag, removing it causes an error on draw_circle (since it's not defined), adding this to the code below: 
     void draw_circle(int *a, int b, int c, int d, int e, int f){} 
will make the ICE go away (with or without -O). (I'm guessing it's not related to the ICE, which I believe is caused by -floop-block alone)

I have these versions of the graphite dependencies installed:
   dev-libs/ppl-0.10.2-r1     USE="pch -doc -test -watchdog" 
   dev-libs/cloog-ppl-0.15.8

Here's the commandline with it's output:
$ LC_ALL=C gcc -v -save-temps -O -floop-block demo.c                                                                    
Using built-in specs.                                                                                                                  
Target: x86_64-pc-linux-gnu                                                                                                            
Configured with: /var/tmp/portage/sys-devel/gcc-4.4.3/work/gcc-4.4.3/configure --prefix=/usr --bindir=/usr/x86_64-pc-linux-gnu/gcc-bin/4.4.3 --includedir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.4.3/include --datadir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.4.3 --mandir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.4.3/man --infodir=/usr/share/gcc-data/x86_64-pc-linux-gnu/4.4.3/info --with-gxx-include-dir=/usr/lib/gcc/x86_64-pc-linux-gnu/4.4.3/include/g++-v4 --host=x86_64-pc-linux-gnu --build=x86_64-pc-linux-gnu --disable-altivec --disable-fixed-point --with-ppl --with-cloog --enable-nls --without-included-gettext --with-system-zlib --disable-checking --disable-werror --enable-secureplt --enable-multilib --enable-libmudflap --disable-libssp --enable-libgomp --enable-cld --with-python-dir=/share/gcc-data/x86_64-pc-linux-gnu/4.4.3/python --disable-libgcj --enable-objc-gc --enable-languages=c,c++,objc,obj-c++,fortran --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --with-bugurl=http://bugs.gentoo.org/ --with-pkgversion='Gentoo 4.4.3 p1.0'    
Thread model: posix
gcc version 4.4.3 (Gentoo 4.4.3 p1.0)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O' '-floop-block' '-mtune=generic'
 /usr/libexec/gcc/x86_64-pc-linux-gnu/4.4.3/cc1 -E -quiet -v demo.c -D_FORTIFY_SOURCE=2 -mtune=generic -floop-block -O -fpch-preprocess -o demo.i
ignoring nonexistent directory "/usr/local/include"
ignoring nonexistent directory "/usr/lib/gcc/x86_64-pc-linux-gnu/4.4.3/../../../../x86_64-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-pc-linux-gnu/4.4.3/include
 /usr/lib/gcc/x86_64-pc-linux-gnu/4.4.3/include-fixed
 /usr/include
End of search list.
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O' '-floop-block' '-mtune=generic'
 /usr/libexec/gcc/x86_64-pc-linux-gnu/4.4.3/cc1 -fpreprocessed demo.i -quiet -dumpbase demo.c -mtune=generic -auxbase demo -O -version -floop-block -o demo.s
GNU C (Gentoo 4.4.3 p1.0) version 4.4.3 (x86_64-pc-linux-gnu)
        compiled by GNU C version 4.4.3, GMP version 4.3.1, MPFR version 2.4.1-p5.
GGC heuristics: --param ggc-min-expand=100 --param ggc-min-heapsize=131072
Compiler executable checksum: a82a244c7fb9c82fc087b2597e2d44f9
demo.c: In function 'main':
demo.c:2: internal compiler error: in expand_scalar_variables_expr, at graphite.c:4295
Please submit a full bug report,
with preprocessed source if appropriate.
See <http://bugs.gentoo.org/> for instructions.