[llvm] [LoopVectorize] Fix divide-by-zero bug (#80836) (PR #81721)

[Florian Hahn via llvm-commits]

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@@ -2106,18 +2106,20 @@ class GeneratedRTChecks {
               BestTripCount = *EstimatedTC;
           }
 
-          InstructionCost NewMemCheckCost = MemCheckCost / BestTripCount;
+          if (BestTripCount > 1) {
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fhahn wrote:

Simpler to just force `BestTripCount` to be at least one using `std::max`?

https://github.com/llvm/llvm-project/pull/81721