[tb,ffi] Implement Rust FFI and testbench integration

[ethanuppal]

I'm not good at fud2 stuff but I think I'm on the right track

[ethanuppal]

Ideally I'd like to move the logic in the tb tool into fud2, but I don't really see that being possible.

[ethanuppal]

Also closes #2162

[ethanuppal]

A TODO thing would be to take advantage of the fact that the verilog incoming is calyx and write a new tester that allows you to interface with calyx components preserving the invariants (in addition to just being able to use cocotb and verilator as currently)

[ethanuppal]

Waiting on #2193

[ethanuppal]

fud2 tests failing because of I hack I added before multi-input ops were a thing. @jku20, I assume they are now?

[ethanuppal]

For some reason, it seems all my commits became unverified?

[ethanuppal]

Now they're verified again...

[rachitnigam]

@ethanuppal what's the status of this PR and what would it take to get it merged?

[ethanuppal]

@rachitnigam I've been working with @EclecticGriffin on using cider2 programmatically; once I have the adder component test working (under tools/tb/examples/calyx/), I'll fix all the issues so that it can be merged.

[ethanuppal]

This is blocked on there being no usable support for relative paths in procedural macros.

[rachitnigam]

There are two options:

1. We figure out a different approach for the testbench that does not rely on the macro magic but is still useful for users writing complex testbenches, or
2. We require users to provide a shim of the component they want to test and generate the ports based on that

I also have a broader question: there are currently no users of this harness. Is there any buy-in from the various teams to use this? That might better inform which use cases actually matter.

[rachitnigam]

Marking this as stale. @ethanuppal feel free to remove and add thoughts if on how we can get this merged without the nightly features.

[ethanuppal]

I'm going to remove stale since we found a way to get relative paths working.

[ethanuppal]

@EclecticGriffin when you get a chance, could you take a look at why the interpreter tests are failing? Is it the fix I made to subtraction (which is fuzz-tested to be correct in an example I wrote through calyx FFI!) breaking it due to subtraction underflow?

[EclecticGriffin]

This tool is out of date with respect to the way values work in Cider currently. We replaced the janky Value implementation with baa::BitVecValue. You'll need to merge in the mainline changes but that should fix this