Even just mapping between the mnemonics is non-trivial. You want to think that it's just a matter of removing size suffixes from AT&T, but it's sadly not that

Even just mapping between the mnemonics is non-trivial. You want to think that it's just a matter of removing size suffixes from AT&T, but it's sadly not that simple. "movslq" in AT&T maps not to "movsl" or even "movs" in Intel, but "movsxd". How is anybody supposed to figure that out?