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

[Sam Parker via llvm-commits]

sparker-arm wrote:

DAGCombiner::reduceLoadWidth doesn't work with vector types. Certainly when I was working in this area, it was all about optimisations for CoreMark :)

Does this need to be fixed during DAGCombine / Lowering? Could some tablegen patterns not just be added?

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