Consider MethodHandle for fn import/export

[andreas-karlsson]

I'm currently writing the interop layer for a project using Chicory, and it seems to me it'd be very nice (and more performant) to have MethodHandles as an option for both imports and exports. Is this something you have considered? Would you welcome a PR?

[andreaTP]

Hi @andreas-karlsson and thanks for your interest in Chicory!
Yes, we have entertained the idea of using MethodHandles in the past for import and export, we are using them at a lower level in the runtime compiler too.
Sadly they have quirks with compatibility, especially wrt Android and native-image where support starts to become challenging.

That said, if you attempted, do you have numbers around performance?
The current bindings are extremely cheap, they are designed to be inlined/optimized by the JVM and the expectation(supported on flamegraphs) is that any delta in perf should be minimal to none compared to MH.

Do you want to expand on the "interop layer"?
Depending on the use case we might have helpers/alternatives.
For example, if the annoying part is the manual wiring, the annotation processors should have you covered (e.g. WasmModuleInterface), documentation is not great but the integration tests and looking at the generated code should be enough to get you started. Feel free to ask questions though!

[andreaTP]

If I can guess something from the GH activity, I'm happy to help in turning this to something closer to this.

[andreas-karlsson]

No I don't have any numbers and agree it's probably negligible. I'm experimenting with using ByteBuddy to implement a Java interface for the module, which plays really well with MH. So I guess the conversions to long[] is mostly an eyesore atm.

If I can guess something from the GH activity...

🙂 You guessed the source right, but I'm not aware of the other project you mention. We're still in early days with this, and it's a little rough around the edges still, but I think we have a clear path forward. Was there something in particular you were thinking about?

[andreas-karlsson]

Also, I should mention; Thanks for all the work you have put into this! It's a really cool project!

[andreaTP]

I'm experimenting with using ByteBuddy to implement a Java interface for the module

Cannot wait to see what you come up with, keep us posted 🙏

which plays really well with MH

If your goal is to target only pure JVM mode and the runtime compiler, I believe you can have a lot of fun, and maybe optimization options, on top of the generated class.
Please consider that the generated ABI might change and is not exposed as public API.

You guessed the source right

Yes, but much easier to talk in front of a code snippet, let me hack something to give you context and we can continue from there 🙂

[andreaTP]

@andreas-karlsson followed up here, take it as an inspiration and to demonstrate the options I proposed, let me know your thoughts!

[andreaTP]

Feel free to re-open when necessary, I believe we have answered here.