[llvm] [MemoryLocation] Teach MemoryLocation about llvm.experimental.memset.pattern (PR #120421)

[Philip Reames via llvm-commits]

preames wrote:

> Stacks on top of https://github.com/llvm/llvm-project/pull/120420.

I don't see any obvious dependency on this.  Why not separate this out so it can go in independently of that one?

https://github.com/llvm/llvm-project/pull/120421