[llvm] [InstCombine] Allow load to store forwarding for scalable structs (PR #123908)

[David Green via llvm-commits]

davemgreen wrote:

> Could you provide some more detail on what the problem with this approach is? I'd expect this to work (not for InstCombine alone, but in conjunction with GVN for example).

This is before and after Instcombine + before gvn with the patch I have that generated i8 geps for the scalable vectors: https://godbolt.org/z/hMnP111qM. GVN wasn't printing much debug info, but I think it might not be allowing scalable vectors here: https://github.com/llvm/llvm-project/blob/6b1db79887df19bc8e8c946108966aa6021c8b87/llvm/lib/Transforms/Utils/VNCoercion.cpp#L26

https://github.com/llvm/llvm-project/pull/123908