[llvm] [MachinePipeliner] Fix store-store dependences (#72508) (PR #72575)

[via llvm-commits]

bcahoon wrote:

I updated the code to treat stores like loads in isLoopCarriedDep. This handles the case when there is a loop independent dependence between two memory operations. The function conservatively assumes there is a loop carried dependence unless it can be proven otherwise.
The case of loop carried dependence without an existing loop independent dependence will be handled in a subsequent patch, in a different place.

https://github.com/llvm/llvm-project/pull/72575