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

[Madhur Amilkanthwar via llvm-commits]

madhur13490 wrote:

Hi @nikic , I'm changing a few tests in the PR, but if we think MemorySSA is good to test, I will change other tests too. Given that MemorySSA is off by default, I am not sure if we want to ensure they are passing.  

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