[llvm] [WebAssembly] Fix lowering of (extending) loads from addrspace(1) globals (PR #155937)

[Derek Schuff via llvm-commits]

dschuff wrote:

> Are there any plans to migrate WASM to GlobalISel any time soon? If there's interest but not enough manpower, I wouldn't mind trying to set up the foundation myself (but that will still take up time from reviewers down the line). Or is it simply not worth it at all for this backend?
> 
> It seems like the plan is to _eventually_ phase out SelectionDAG and FastISel in favor of it...or am I misunderstanding its purpose?

Not currently. It is indeed more a matter of lack of engineering time (and unclear how much the benefit would be) than anything else. I wouldn't mind having someone work on this, but I expect it would be a long project to get it up to parity with SelectionDAG (although I would hope not as large as it's been for other architectures like ARM64, as the wasm backend is simpler... I'm still not sure what the status there is, probably @sparker-arm knows). I would hope we could do some investigation on the front end to have some confidence that there would be some benefit in the end (i.e. code quality, maintainability, etc). None of us on the wasm side are experts on GlobalISel, but if you're serious about this, then I wouldn't mind putting in the time it would probably take for competent review :)

https://github.com/llvm/llvm-project/pull/155937