[llvm] [VPlan] Introduce ComputeReductionResult VPInstruction opcode. (PR #70253)

[via llvm-commits]

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@@ -9034,7 +8894,7 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
       VPRecipeBase *Cur = Worklist[I];
       for (VPUser *U : Cur->getVPSingleValue()->users()) {
         auto *UserRecipe = dyn_cast<VPRecipeBase>(U);
-        if (!UserRecipe)
+        if (!UserRecipe || UserRecipe == FinalReductionResult)
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ayalz wrote:

Must the reduction chain now terminate at FinalReductionResult? I.e., assert that `UserRecipe` is non-null by (non-dyn) casting `U` into a recipe. 

https://github.com/llvm/llvm-project/pull/70253