This is the error message I get
../../../im-alias-source/libiberty/regex.c: In function 'byte_regex_compile':
../../../im-alias-source/libiberty/regex.c:4221: error: unrecognizable insn:
(insn 160 159 161 3 ../../../im-alias-source/libiberty/regex.c:284 (set (reg:SI
326 [ ivtmp.838 ])
        (const:SI (plus:SI (symbol_ref:SI ("_ctype_") <var_decl 0x40162210 _ctype_>)
                (const_int 1 [0x1])))) -1 (nil)
    (nil))
../../../im-alias-source/libiberty/regex.c:4221: internal compiler error: in extract_insn, at recog.c:2084



This was on both im-alias branch and cvs version I checked  out on 10/27/05. 
Here are my configure options 
../im-alias-source/configure   --srcdir=../im-alias-source/ --target=mcore-elf --with-newlib --disable-threads --disable-multilib --disable-nls --prefix=/usr/local/gcc4-mcore --enable-languages=c

Here is the compiler line 
/home/sumesh/gcc4-mcore/im-alias/gcc_obj/./gcc/xgcc -B/home/sumesh/gcc4-mcore/im-alias/gcc_obj/./gcc/ -B/usr/local/gcc4-mcore/mcore-elf/bin/ -B/usr/local/gcc4-mcore/mcore-elf/lib/ -isystem /usr/local/gcc4-mcore/mcore-elf/include -isystem /usr/local/gcc4-mcore/mcore-elf/sys-include -c -DHAVE_CONFIG_H -O2 -g -O2   -I. -I../../../im-alias-source/libiberty/../include  -W -Wall -pedantic -Wwrite-strings -Wstrict-prototypes ../../../im-alias-source/libiberty/regex.c -o regex.o