[llvm] [LV] Factor costInterleaveGatherScatter (NFC) (PR #215857)

[Luke Lau via llvm-commits]

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@@ -4416,50 +4485,13 @@ void LoopVectorizationCostModel::setCostBasedWideningDecision(ElementCount VF) {
       if (!Ptr)
         continue;
 
+      // Choose between Interleaving, Gather/Scatter or Scalarization.
+      auto [Decision, Cost] = costInterleaveGatherScatter(&I, VF);
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lukel97 wrote:

This is hoisted outside of isUniformMemOp so it will run more often now I think. Can we sink it?

https://github.com/llvm/llvm-project/pull/215857