[llvm] [VPlan] Add new VPIRPhi overlay for VPIRInsts wrapping phi nodes (NFC). (PR #129387)

[via llvm-commits]

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@@ -1086,6 +1089,27 @@ class VPIRInstruction : public VPRecipeBase {
   void extractLastLaneOfOperand(VPBuilder &Builder);
 };
 
+/// An overlay for VPIRInstructions wrapping PHI nodes enabling convenient use
+/// cast/dyn_cast/isa and execute() implementation.
+struct VPIRPhi : public VPIRInstruction {
+  VPIRPhi(PHINode &PN) : VPIRInstruction(PN) {}
+
+  static inline bool classof(const VPRecipeBase *U) {
+    auto *R = dyn_cast<VPIRInstruction>(U);
+    return R && isa<PHINode>(R->getInstruction());
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ayalz wrote:

This is needed because VPIRPhi reuses VPIRInstruction's VPDEF::VPIRInstructionSC rather than defining its own?

https://github.com/llvm/llvm-project/pull/129387