[llvm] [LoopInterchange] Fix overflow in cost calculation (PR #111807)

[Min-Yih Hsu via llvm-commits]

https://github.com/mshockwave commented:

Generally LGTM. Personally I don't have any strong opinion on using CacheCostTy instead of InstructionCost.

@fhahn do you have any other comment?

https://github.com/llvm/llvm-project/pull/111807