[PyCDE] FSM support more types inputs

[Dragon-Git]

I noticed that currently the FSM in pycde only supports i1 type inputs, performs type checking and throws an exception in MachineModuleBuilder.scan_cls. Besides the limitation of fsm.TransitionOp only supporting i1 type conditions, are there any other considerations? If it's just this reason, could type checking be performed in State.transition.__init__ to support other types of input?

[teqdruid]

Copying my comment in the PR here since it's the right place for it.

Only supporting i1 was specifically done to discourage complex combinatorial computations inside of the FSM itself. When creating hardware, it's better from an FMax perspective to (as much as possible) compute the inputs at least a cycle ahead of when it's actually needed. We don't have any ability to pipeline within an FSM, so the only way we can enforce this is by only accepting i1 as inputs and requiring users to do non-trivial computations externally and leave only the state transitions to the FSM.

There was much consternation about this. But the conclusion was to err on the side of discouraging users from creating non-performant hardware.