[llvm] [SLP][NFC] Extract VectorizableTree into own ForestTree class (PR #222805)

[Alexey Bataev via llvm-commits]

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@@ -2393,7 +2416,7 @@ class slpvectorizer::BoUpSLP {
   /// \param Op2 second homogeneous scalars.
   /// \param ReorderIndices indices to reorder the scalars.
   /// \returns true if the node was successfully built.
-  bool canBuildSplitNode(ArrayRef<Value *> VL,
+  bool canBuildSplitNode(ForestTree *FT, ArrayRef<Value *> VL,
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alexey-bataev wrote:

Better to not pass pointers, always pass references

https://github.com/llvm/llvm-project/pull/222805