What is needed for phase 3?

[fgmccabe]

We would like to move the process for stack switching to phase 3 in the near future.

Please make suggestions as to what is needed.

[tlively]

The formal requirements are all around test suites:

1. Test suite has been updated to cover the feature in its forked repo.

2. The test suite should run against some implementation, though it need not be the reference interpreter.

The existing tests look fairly thorough, although I haven't gone over them for line-by-line coverage of the validation rules or anything like that. Besides the reference interpreter, we have implementations under way in V8 and binaryen, so I think we're good to go on that front.

Kotlin has a plan to experiment with the proposal, so we should hopefully get real performance numbers from them soon.

[fitzgen]

There is also a WIP implementation in Wasmtime, and although Wasmtime is not a Web engine, I don't believe that is required for phase 3, just phase 4.

[tlively]

It would be good to settle the design question in #117 before phase 3 because any change we decide to make to address it would be somewhat intrusive.