[llvm] [LV] Bundle partial reductions inside VPExpressionRecipe (PR #147302)

[Sander de Smalen via llvm-commits]

================
@@ -350,19 +353,20 @@ VPPartialReductionRecipe::computeCost(ElementCount VF,
     }
   };
 
-  if (isa<VPWidenCastRecipe>(OpR)) {
+  if (isa_and_nonnull<VPWidenCastRecipe>(OpR)) {
----------------
sdesmalen-arm wrote:

I don't think this case, or the cases below, will ever result in a `nullptr` so those changes seem unnecessary to me.

https://github.com/llvm/llvm-project/pull/147302