> Of course, everyone should be running 64-bit MAME anyway, we can't guarantee MAME > will run much longer in 32-bit environments. > > Can you give some example where/how 64-bit code differs from 32-bit code. Is it not, > or can it not be, just a compiler option settings?
64-bit code is about 20% faster overall for free in emulation environments, and it often provides similar benefits to PC games. There are 16 registers instead of 3 to 5 and more instructions work on all of them (instead of MUL always putting the results in specific registers) so the compiler can generate much more optimal code.
Also, we're looking to start emulating things (like certain newer handhelds) where the ROMs are 2/3/4 GB, which has trouble fitting at all in a 32-bit system.