[llvm] [SLP]Represent SLP graph as a tree (PR #126771)

[Alexey Bataev via llvm-commits]

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@@ -5951,6 +5985,67 @@ static void combineOrders(MutableArrayRef<unsigned> Order,
   }
 }
 
+bool BoUpSLP::isProfitableToReorder() const {
+  constexpr unsigned TinyVF = 2;
+  constexpr unsigned TinyTree = 10;
+  if (VectorizableTree.size() <= TinyTree)
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alexey-bataev wrote:

MinTreeSize can be modified and in some cases we may overcome it. MinTreeSize controls, if the tree should be vectorized at all, here we decide if it worth to o try to rotate it before the vectorization

https://github.com/llvm/llvm-project/pull/126771