[llvm] [ConstraintElim] Preserve analyses when IR is unchanged. (PR #128588)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:


> Not sure how to/if possible to add a test for this.

You might be able to use something like 

`opt -S -passes='require<scalar-evolution>,constraint-elimination' -debug-pass-manager` to check that scalar-evolution is preserved with the change

https://github.com/llvm/llvm-project/pull/128588