[llvm] [SLP][REVEC] Make ShuffleCostEstimator and ShuffleInstructionBuilder can vectorize vector instructions. (PR #99606)

[Han-Kuan Chen via llvm-commits]

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@@ -8833,6 +8852,8 @@ class BoUpSLP::ShuffleCostEstimator : public BaseShuffleAnalysis {
     } else if (!V1 && V2) {
       // Shuffle vector and tree node.
       unsigned VF = cast<FixedVectorType>(V2->getType())->getNumElements();
+      if (auto *VecTy = dyn_cast<FixedVectorType>(ScalarTy))
+        VF /= VecTy->getNumElements();
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HanKuanChen wrote:

Add assertion in `GetVF`.

https://github.com/llvm/llvm-project/pull/99606