Stack types

[khagankhan]

Stack fixup

We currently have every instruction balanced itself (for example, if an op leaves a struct onto the stack it immediately calls a function that consumes that struct) like we did for our generative fuzzer. However, for mutation based fuzzers this may have some bias.

This PR removes that and fixes the stack in the end. It keeps abstract stack types and check the required types then fixes the actual stack.

+cc @fitzgen @eeide

[khagankhan]

@fitzgen Ready for review!

[github-actions[bot]]

Subscribe to Label Action

cc @fitzgen

This issue or pull request has been labeled: "fuzzing"

Thus the following users have been cc'd because of the following labels:

• fitzgen: fuzzing

To subscribe or unsubscribe from this label, edit the .github/subscribe-to-label.json configuration file.

Learn more.

[alexcrichton]

Thanks! Nick's out this week and I so far haven't had a chance to look at this. I may end up deferring this to Nick when he gets back as I'll otherwise have to boot back up on a lot of context here, but do you have other subsequent PRs ready to go which are built on this and so it'd be good to get this in sooner rather than later?

[khagankhan]

Hey Alex! I am mostly working on a repo on GitLab where I am ahead. The Wasmtime PRs tend to lag behind my current work because I address comments, failed tests etc. Since Nick and I meet weekly (except this week) and go over everything, I think it makes sense to defer this to him. Thank you for the comment!