[llvm] [CodeGen] [LIT] Pre-commit tests added for Early Program return optimization (PR #102128)

[Matt Arsenault via llvm-commits]

https://github.com/arsenm requested changes to this pull request.

We need to see end to end IR tests. At this stage I don't know if MIR tests are useful for this. This requires the cooperation of the full pass pipeline 

https://github.com/llvm/llvm-project/pull/102128