Add Wasmer's WAMR backend

[Robbepop]

@syrusakbary First, congrats to the Wasmer 5.0 update!

I have noticed that Wasmer 5.0 included WAMR as backend and wondered if it would make sense to add it as another Wasmer backend to wasmi-benchmarks? I have not yet included WAMR since it has no easy bindings for Rust but with Wasmer 5.0 this has probably changed.

Does Wasmer 5.0 use WAMR's fast-interpreter, classic-interpreter or one of its JITs? I'd be most interesting in its fast-interpreter backend from the Wasmi perspective.

[syrusakbary]

I think we used fast-interpreter (no JIT). I believe @xdoardo can probably follow up on this since he worked on that.
In any case, it should be possible to support all of those cases via feature flags

[xdoardo]

Hello! By default, we build WAMR with AOT disabled and FAST_INTERP enabled.

[Robbepop]

@syrusakbary @xdoardo okay thanks a lot for the information! Probably makes sense to integrate WAMR support via Wasmer 5.0. :) Looking forward to the results once integration is complete.

[Robbepop]

Copying here an answer from Wasmer Discord about building Wasmer 5.0 with multiple backends:

Sorry, I missed the notification. Unfortunately it's not possible right now, as they use two features that conflict with each other. In the near future we'll move to a different architecture that allows single binaries with (hopefully) all the backends available together.

So, depending on your needs, you can have:

• One build with cranelift, llvm, singlepass (or any combination)
• One build with wamr
• One build with v8
• One build with wasmi

Building Wasmer 5.0 with WAMR:

cargo build --package=wasmer --no-default-features --features=\
    wamr,\
    wasmer-artifact-create,\
    static-artifact-create,\
    wasmer-artifact-load,\
    static-artifact-load