[llvm] [WIP][SLP] SLP's copyable elements based upon Main/Alt operations. (PR #124242)

[Alexey Bataev via llvm-commits]

================
@@ -3298,6 +3462,7 @@ class BoUpSLP {
                          ///< complex node like select/cmp to minmax, mul/add to
                          ///< fma, etc. Must be used for the following nodes in
                          ///< the pattern, not the very first one.
+      CopyableVectorize, ///< The node for copyable elements.
----------------
alexey-bataev wrote:

Why do you need this new state?

https://github.com/llvm/llvm-project/pull/124242