[llvm] [LV][VPlan] Introduce VPScalarStore recipe to handle scalar stores in exit block. (PR #93148)

[Florian Hahn via llvm-commits]

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@@ -9130,8 +9102,9 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
         VPInstruction::ComputeReductionResult, {PhiR, NewExitingVPV}, ExitDL);
     FinalReductionResult->insertBefore(*MiddleVPBB, IP);
     OrigExitingVPV->replaceUsesWithIf(
-        FinalReductionResult,
-        [](VPUser &User, unsigned) { return isa<VPLiveOut>(&User); });
+        FinalReductionResult, [](VPUser &User, unsigned) {
+          return isa<VPLiveOut>(&User) || isa<VPScalarStoreRecipe>(&User);
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fhahn wrote:

better to also assert that VPScalarStoreRecipe is outside the vector loop region?

https://github.com/llvm/llvm-project/pull/93148