[llvm] [SLP] Enable reordering for non-power-of-two vectors (PR #106638)

[Alexey Bataev via llvm-commits]

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@@ -5424,11 +5422,13 @@ BoUpSLP::getReorderingData(const TreeEntry &TE, bool TopToBottom) {
     }
     if (isSplat(TE.Scalars))
       return std::nullopt;
-    if (TE.Scalars.size() >= 4)
+    if (TE.Scalars.size() >= 3)
       if (std::optional<OrdersType> Order = findPartiallyOrderedLoads(TE))
         return Order;
-    if (std::optional<OrdersType> CurrentOrder = findReusedOrderedScalars(TE))
-      return CurrentOrder;
+
+    if (!TE.isNonPowOf2Vec())
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alexey-bataev wrote:

Add a FIXME to remove this check later

https://github.com/llvm/llvm-project/pull/106638