Re: Question about AMD64 ABI

Again, most compilers are smart enough to perhaps `and reg, 0x0FFFF` or simply ignore the high bits on its own, but ultimately you do feed it the entire register in which if the callee expects to operate on 16-bits or smaller it better do so.

So I had better zero-extend it to 32 bit, right? Why not 64, because it’s already safe enough?
Or just because the higher 32 bits can be automatically cleared?