[llvm] [NFC][LoopVectorize] Make replaceVPBBWithIRVPBB more efficient (PR #111514)

[via llvm-commits]

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@@ -3862,6 +3882,19 @@ class VPBlockUtils {
     To->removePredecessor(From);
   }
 
+  /// Reassociate all the blocks connected to \p Old so that they now point to
+  /// \p New.
+  static void reassociateBlocks(VPBlockBase *Old, VPBlockBase *New) {
+    for (auto *Pred : to_vector(Old->getPredecessors()))
+      Pred->replaceSuccessor(Old, New);
+    for (auto *Succ : to_vector(Old->getSuccessors()))
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ayalz wrote:

Is this to_vector() needed, given that Old's successors remain intact?

https://github.com/llvm/llvm-project/pull/111514