## What this adds

[ubsasi]

What this adds

Calls out to modules with wasm-opt's --asyncify pass to unwind and rewind the module's call stack when we want to put Swift execution to sleep while allowing incoming events to be handled by JavaScript.

Further Reading

Alon Zakai's Blog
Alon Zakai's Talk
Binaryen Docs
Experimental JS wrapper from Google

Concerns

• This adds a bit of complexity on the JS runtime side, especially the need to provide a 'restart' method for re-entering module execution. Should not affect existing usage as all additions are optional.
• At Swift build time, there is no way of knowing if module will be asyncified so no way to block usage of new methods. The Asyncify pass is extremely slow as well, so not a good candidate to add e.g. to carton's build process.

Originally posted by @yonihemi in swiftwasm/JavaScriptKit#107