[llvm] [LoopInterchange] Bail out for Scalar Dependencies (PR #119345)

[Sjoerd Meijer via llvm-commits]

sjoerdmeijer wrote:

Thanks for the review @kasuga-fj and @CongzheUalberta! I agree with your feedback, I made a mess of the logic. I have now simplified things, the idea is to simply reject S dependencies:

    This patch checks that the dependency matrix has no "S" direction as the leftmost non-"=" direction in any row.

I have updated the commit message / description of this patch with a better explanation. 

https://github.com/llvm/llvm-project/pull/119345