[llvm] [VPlan] Model branch cond to enter scalar epilogue in VPlan. (PR #92651)

[via llvm-commits]

================
@@ -9114,8 +9067,8 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
     // also modeled in VPlan.
     auto *FinalReductionResult = new VPInstruction(
         VPInstruction::ComputeReductionResult, {PhiR, NewExitingVPV}, ExitDL);
-    cast<VPBasicBlock>(VectorLoopRegion->getSingleSuccessor())
-        ->appendRecipe(FinalReductionResult);
+    FinalReductionResult->insertBefore(*MiddleVPBB, IP);
+    IP = std::next(FinalReductionResult->getIterator());
----------------
ayalz wrote:

Is this std::next needed - having inserted FinalReductionResult before IP implies that the latter already follows the former?

https://github.com/llvm/llvm-project/pull/92651