[llvm] [WebAssembly] Add RefTypeMem2Local pass (PR #81965)

[via llvm-commits]

xortoast wrote:

@aheejin Sorry for the late reply.

> But it looks the MMI table only works with memory.

I was not aware of that.

> I also don't understand what situation you mean by "where DWARF debug info is not available".

I was referring to runtimes that don't support DWARF and cases where DWARF debug info is lost due to post-processing. In those cases you can only see raw locals and raw linear memory, and I think it's easier to work with the former.

> Are there other framework we use to cover variable debug info?

You can attach names to local variables with the [`name` custom section](https://webassembly.github.io/spec/core/appendix/custom.html#binary-localnamesec), but we do not (yet) support that.

In any case, my previous comment was based on some incorrect assumptions. You can merge this PR now, and we can continue this discussion later when the situation with debug info changes.

https://github.com/llvm/llvm-project/pull/81965