GCC fails with -O2 for own Target

[Jens Mehler <jens.mehler@xxxxxxxxxx>]

Hallo everyone,

I have ported the GCC (v4.5.3) to a new target (32-bit RISC processor).
So far everything went fine. I wrote my own little C-Lib with basic 
input output and tested it worked.
Until today I never actually tried optimization passes (maybe that was 
the mistake that lead to this)
Anyway:
During porting and building Newlib I ran into an error that I tracked 
down to the following code:

unsigned char hexdig[256];

static void htinit ( unsigned char *h , unsigned char *s , int inc)
{
    int i, j;
    for(i = 0; (j = s[i]) !=0; i++)
        h[j] = i + inc;
}

void
hexdig_init ()
{
    htinit(hexdig, (unsigned char *) "0123456789", 0x10);
    htinit(hexdig, (unsigned char *) "abcdef", 0x10 + 10);
    htinit(hexdig, (unsigned char *) "ABCDEF", 0x10 + 10);
}

Compiling this code without optimization works like a charm, however 
compiling it with -O2 leads to the following error:
test1.c: In function 'hexdig_init':
test1.c:11:1: internal compiler error: in gen_lowpart_general, at 
rtlhooks.c:59

Tried with:
eco32-gcc -O2 -S test1.c

My question in short is:
Could this be a targe- backend-error or just some configuration I have 
missed while building GCC?
Any pointers into the right direction are welcome.

With best regards,
Jens Mehler