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

[Florian Hahn via llvm-commits]

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@@ -31,7 +32,7 @@ class ScalarEvolution;
 class SCEV;
 class TargetTransformInfo;
 
-using CacheCostTy = int64_t;
+using CacheCostTy = InstructionCost;
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fhahn wrote:

Personally I find it more inconvenient to hide the actual type behind another level of indirection, but changing it in this patch would unnecessarily increase the diff.

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