extra 3-in 2-out instructions, similar to Intel's
[shld](https://www.felixcloutier.com/x86/shld)
and [shrd](https://www.felixcloutier.com/x86/shrd),
-`mulx` and
+[mulx](https://www.felixcloutier.com/x86/mulx) and
[divq](https://www.felixcloutier.com/x86/div),
to be efficient.
The same instruction (`maddedu`) is used in both