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

[via llvm-commits]

xortoast wrote:

Would it be beneficial to expand this pass to all types (where possible), not just reference types?

The main argument against unconditionally running `mem2reg` was that it causes debug info to be handled differently or lost. AFAIK this should not be an issue here, since we are keeping all the loads and stores the same and just modifying the allocas.

In fact, this would make debugging easier (especially in situations where DWARF debug info is not available), as well as produce simpler and faster code in unoptimized builds.

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