[llvm] MemCpyOpt: replace an AA query with MSSA query (NFC) (PR #108535)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

> A disadvantage of using MSSA is that we'll scan for clobbers higher than the load instruction. This is a general problem with MSSA clobber walks though, it would be nice if they have an option to specify a "stop access" so we don't waste time scanning higher.

Yes, I saw this being noted in a TODO in the file. Does it walk through non-memory instructions as well, or does it keep a representation of just the memory instructions?

https://github.com/llvm/llvm-project/pull/108535