[llvm] [VPlan] Move tail folding out of VPlanPredicator. NFC (PR #176143)

[Luke Lau via llvm-commits]

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@@ -232,15 +205,22 @@ void VPPredicator::createSwitchEdgeMasks(VPInstruction *SI) {
 void VPPredicator::convertPhisToBlends(VPBasicBlock *VPBB) {
   SmallVector<VPPhi *> Phis;
   for (VPRecipeBase &R : VPBB->phis())
-    Phis.push_back(cast<VPPhi>(&R));
+    if (auto *PhiR = dyn_cast<VPPhi>(&R))
+      Phis.push_back(PhiR);
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lukel97 wrote:

I removed this part of the diff by keeping the `if (VPBB == Header) continue` part

https://github.com/llvm/llvm-project/pull/176143