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

[Florian Hahn via llvm-commits]

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@@ -9130,51 +9142,13 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
   using namespace VPlanPatternMatch;
   VPRegionBlock *VectorLoopRegion = Plan->getVectorLoopRegion();
   VPBasicBlock *Header = VectorLoopRegion->getEntryBasicBlock();
-  // Gather all VPReductionPHIRecipe and sort them so that Intermediate stores
-  // sank outside of the loop would keep the same order as they had in the
-  // original loop.
-  SmallVector<VPReductionPHIRecipe *> ReductionPHIList;
-  for (VPRecipeBase &R : Header->phis()) {
-    if (auto *ReductionPhi = dyn_cast<VPReductionPHIRecipe>(&R))
-      ReductionPHIList.emplace_back(ReductionPhi);
-  }
-  bool HasIntermediateStore = false;
-  stable_sort(ReductionPHIList,
-              [this, &HasIntermediateStore](const VPReductionPHIRecipe *R1,
-                                            const VPReductionPHIRecipe *R2) {
-                auto *IS1 = R1->getRecurrenceDescriptor().IntermediateStore;
-                auto *IS2 = R2->getRecurrenceDescriptor().IntermediateStore;
-                HasIntermediateStore |= IS1 || IS2;
-
-                // If neither of the recipes has an intermediate store, keep the
-                // order the same.
-                if (!IS1 && !IS2)
-                  return false;
-
-                // If only one of the recipes has an intermediate store, then
-                // move it towards the beginning of the list.
-                if (IS1 && !IS2)
-                  return true;
-
-                if (!IS1 && IS2)
-                  return false;
-
-                // If both recipes have an intermediate store, then the recipe
-                // with the later store should be processed earlier. So it
-                // should go to the beginning of the list.
-                return DT->dominates(IS2, IS1);
-              });
-
-  if (HasIntermediateStore && ReductionPHIList.size() > 1)
-    for (VPRecipeBase *R : ReductionPHIList)
-      R->moveBefore(*Header, Header->getFirstNonPhi());
-
   for (VPRecipeBase &R : Header->phis()) {
     auto *PhiR = dyn_cast<VPReductionPHIRecipe>(&R);
     if (!PhiR || !PhiR->isInLoop() || (MinVF.isScalar() && !PhiR->isOrdered()))
       continue;
 
     const RecurrenceDescriptor &RdxDesc = PhiR->getRecurrenceDescriptor();
+    StoreInst *IntermediateStore = RdxDesc.IntermediateStore;
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fhahn wrote:

only used in assertion, will need to by sunk into assert (preferable) or mark as potentially unused to avoid warning

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