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

[via llvm-commits]

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@@ -1028,6 +1013,40 @@ void VPIRInstruction::extractLastLaneOfOperand(VPBuilder &Builder) {
 void VPIRInstruction::print(raw_ostream &O, const Twine &Indent,
                             VPSlotTracker &SlotTracker) const {
   O << Indent << "IR " << I;
+}
+#endif
+
+void VPIRPhi::execute(VPTransformState &State) {
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ayalz wrote:

Are VPIRPhi recipes expected to have at-least one operand?
```suggestion
void VPIRPhi::execute(VPTransformState &State) {
  assert(getNumOperands() > 0 && "VPIRPhi recipes must have operands");
```

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