[llvm] [LV] Reuse VPReplicateRecipe to handle scalar stores in exit block. (PR #106342)

[Florian Hahn via llvm-commits]

================
@@ -9430,11 +9416,17 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
     auto *FinalReductionResult = new VPInstruction(
         VPInstruction::ComputeReductionResult, {PhiR, NewExitingVPV}, ExitDL);
     FinalReductionResult->insertBefore(*MiddleVPBB, IP);
-    OrigExitingVPV->replaceUsesWithIf(FinalReductionResult, [](VPUser &User,
-                                                               unsigned) {
-      return match(&User, m_Binary<VPInstruction::ExtractFromEnd>(m_VPValue(),
-                                                                  m_VPValue()));
-    });
+    OrigExitingVPV->replaceUsesWithIf(
+        FinalReductionResult, [IntermediateStore](VPUser &User, unsigned) {
+          return match(&User, m_Binary<VPInstruction::ExtractFromEnd>(
+                                  m_VPValue(), m_VPValue())) ||
+                 (isa<VPReplicateRecipe>(&User) &&
+                  cast<VPReplicateRecipe>(&User)->getUnderlyingValue() ==
+                      IntermediateStore &&
+                  cast<VPReplicateRecipe>(&User)
+                      ->getOperand(1)
+                      ->isDefinedOutsideVectorRegions());
+        });
----------------
fhahn wrote:

```suggestion
     auto *FinalReductionResult = new VPInstruction( 
        VPInstruction::ComputeReductionResult, {PhiR, NewExitingVPV}, ExitDL);
    // Update all users outside the vector region.
    OrigExitingVPV->replaceUsesWithIf(
        FinalReductionResult, [](VPUser &User, unsigned) {
        auto *Parent = cast<VPRecipeBase>(&User)->getParent();
          return Parent && !Parent->getParent();
        });
    FinalReductionResult->insertBefore(*MiddleVPBB, IP);
```

https://github.com/llvm/llvm-project/pull/106342