[llvm] [LV][EVL] Support in-loop reduction using tail folding with EVL. (PR #90184)

[Florian Hahn via llvm-commits]

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@@ -1446,23 +1454,39 @@ bool VPlanTransforms::tryAddExplicitVectorLength(VPlan &Plan) {
 
   for (VPValue *HeaderMask : collectAllHeaderMasks(Plan)) {
     for (VPUser *U : collectUsersRecursively(HeaderMask)) {
-      auto *MemR = dyn_cast<VPWidenMemoryRecipe>(U);
-      if (!MemR)
+      VPRecipeBase *NewRecipe = nullptr;
+      auto *CurRecipe = dyn_cast<VPRecipeBase>(U);
+      if (!CurRecipe || CurRecipe->getNumDefinedValues() > 1)
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fhahn wrote:

why is the NumDefinedValues check needed?

https://github.com/llvm/llvm-project/pull/90184