[llvm] [VPlan] Remove non-reductions after simplifications. (PR #176795)

[via llvm-commits]

================
@@ -162,6 +163,7 @@ bool VPRecipeBase::mayHaveSideEffects() const {
     return cast<VPExpressionRecipe>(this)->mayHaveSideEffects();
   case VPDerivedIVSC:
   case VPFirstOrderRecurrencePHISC:
+  case VPReductionPHISC:
   case VPPredInstPHISC:
----------------
ayalz wrote:

```suggestion
  case VPPredInstPHISC:
  case VPReductionPHISC:
```

https://github.com/llvm/llvm-project/pull/176795