[llvm] [VPlan] Consolidate logic for narrow to single scalars (PR #151506)

[Florian Hahn via llvm-commits]

================
@@ -1238,21 +1214,19 @@ static void narrowToSingleScalarRecipes(VPlan &Plan) {
       if (RepR && (RepR->isSingleScalar() || RepR->isPredicated()))
         continue;
 
-      auto *RepOrWidenR = cast<VPSingleDefRecipe>(&R);
-      // Skip recipes that aren't single scalars or don't have only their
-      // scalar results used. In the latter case, we would introduce extra
-      // broadcasts.
-      if (!vputils::isSingleScalar(RepOrWidenR) ||
-          any_of(RepOrWidenR->users(), [RepOrWidenR](VPUser *U) {
-            return !U->usesScalars(RepOrWidenR);
-          }))
+      auto *Def = cast<VPSingleDefRecipe>(&R);
+      // Skip recipes that aren't single scalars or that don't have users or
+      // that don't have only their scalar results used (would introduce extra
+      // broadcasts in this case).
+      if (!vputils::isSingleScalar(Def) || Def->getNumUsers() == 0 ||
+          any_of(Def->users(),
+                 [Def](VPUser *U) { return !U->usesScalars(Def); }))
         continue;
 
-      auto *Clone = new VPReplicateRecipe(RepOrWidenR->getUnderlyingInstr(),
-                                          RepOrWidenR->operands(),
-                                          true /*IsSingleScalar*/);
-      Clone->insertBefore(RepOrWidenR);
-      RepOrWidenR->replaceAllUsesWith(Clone);
+      auto *Clone = new VPReplicateRecipe(
+          Def->getUnderlyingInstr(), Def->operands(), true /*IsSingleScalar*/);
+      Clone->insertBefore(Def);
+      Def->replaceAllUsesWith(Clone);
----------------
fhahn wrote:

Why change the code here? The original name `RepOrWidenR` seems more accurate?

https://github.com/llvm/llvm-project/pull/151506