[LV] Improve code in collectInstsToScalarize (NFC) (#130643)

Author: artagnon

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -5391,12 +5391,12 @@ void LoopVectorizationCostModel::collectInstsToScalarize(ElementCount VF) {
           ScalarCostsVF.insert(ScalarCosts.begin(), ScalarCosts.end());
           // Check if we decided to scalarize a call. If so, update the widening
           // decision of the call to CM_Scalarize with the computed scalar cost.
-          for (const auto &[I, _] : ScalarCosts) {
+          for (const auto &[I, Cost] : ScalarCosts) {
             auto *CI = dyn_cast<CallInst>(I);
             if (!CI || !CallWideningDecisions.contains({CI, VF}))
               continue;
             CallWideningDecisions[{CI, VF}].Kind = CM_Scalarize;
-            CallWideningDecisions[{CI, VF}].Cost = ScalarCosts[CI];
+            CallWideningDecisions[{CI, VF}].Cost = Cost;
           }
         }
         // Remember that BB will remain after vectorization.