[llvm] [SLP]Add cost estimation for gather node reshuffling (PR #115201)

[Simon Pilgrim via llvm-commits]

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@@ -10296,10 +10296,10 @@ class BoUpSLP::ShuffleCostEstimator : public BaseShuffleAnalysis {
             Idx = EMask[Idx];
         }
         CommonVF = E->Scalars.size();
-      } else if (std::optional<unsigned> Factor = E->getInterleaveFactor();
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RKSimon wrote:

Remove the useless std::optional as a pre-commit

https://github.com/llvm/llvm-project/pull/115201