At the cross-GCC mailinglist I asked if it would be possible to port, and that we are just inventorizing what we could do... Their answer was, look at SDCC (is the compiler used by the GameBoy development kit, BTW). The main drawback of this one, it's not fully functional at the moment, no good optimizations, etc. But we even wanted to port GCC with our bare hands, so what are talking about?