[llvm] [CodeGen] Update for scalable MemoryType in MMO (PR #70452)

[David Green via llvm-commits]

davemgreen wrote:

Do you mean if we changed it internally too? Yeah that would lose the info I think. I'm not sure if it could come from the type of the load/store instead?

This patch is just adding extra external interfaces though, the internal type is still a LLT, and can still be accessed directly through GISel.

https://github.com/llvm/llvm-project/pull/70452