[llvm] [VPlan] Use ResumePhi to create reduction resume phis. (PR #110004)

[via llvm-commits]

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@@ -7617,11 +7600,12 @@ DenseMap<const SCEV *, Value *> LoopVectorizationPlanner::executePlan(
   // 2.5 Collect reduction resume values.
   auto *ExitVPBB =
       cast<VPBasicBlock>(BestVPlan.getVectorLoopRegion()->getSingleSuccessor());
-  for (VPRecipeBase &R : *ExitVPBB) {
-    createAndCollectMergePhiForReduction(
-        dyn_cast<VPInstruction>(&R), State, OrigLoop,
-        State.CFG.VPBB2IRBB[ExitVPBB], ExpandedSCEVs);
-  }
+  if (IsEpilogueVectorization)
+    for (VPRecipeBase &R : *ExitVPBB) {
+      updateAndCollectMergePhiForReductionForEpilogueVectorization(
+          dyn_cast<VPInstruction>(&R), State, OrigLoop,
+          State.CFG.VPBB2IRBB[ExitVPBB], ExpandedSCEVs);
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ayalz wrote:

`ExpandedSCEVs` passed as last parameter received as `bool VectorizingEpilogue` (also in existing code), becomes redundant given above guard of `IsEpilogueVectorization`?
Assert ExpandedSCEVs matches IsEpilogueVectorization?

https://github.com/llvm/llvm-project/pull/110004