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

[Han-Kuan Chen via llvm-commits]

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@@ -12179,6 +12217,8 @@ class BoUpSLP::ShuffleInstructionBuilder final : public BaseShuffleAnalysis {
         }
     }
     int VF = cast<FixedVectorType>(V1->getType())->getNumElements();
+    if (auto *VecTy = dyn_cast<FixedVectorType>(ScalarTy))
+      VF /= VecTy->getNumElements();
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HanKuanChen wrote:

We can make `getVF` into a protected member function of `BaseShuffleAnalysis`. However, `BaseShuffleAnalysis` would need to store `ScalarTy`. See https://github.com/llvm/llvm-project/pull/99606/commits/f1de612dbf027f53e1f7dff1616aa1a98f2acd26.

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