[llvm] [GVN] Add MemorySSA checks in tests 1/N (PR #130261)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

This looks reasonable to me now. @antoniofrighetto Any concerns with testing MSSA? Also, do you think it would make sense to make `gvn<memoryssa>` work by having it imply `no-memdep`?

https://github.com/llvm/llvm-project/pull/130261