[VPlan] Use createSelect in adjustRecipesForReductions (NFCI).

Simplify the code and rename Result->NewExitingVPV as suggested by
@ayalz in llvm#70253.

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorizationPlanner.h

@@ -167,9 +167,14 @@ class VPBuilder {
   }
 
   VPValue *createSelect(VPValue *Cond, VPValue *TrueVal, VPValue *FalseVal,
-                        DebugLoc DL, const Twine &Name = "") {
-    return createNaryOp(Instruction::Select, {Cond, TrueVal, FalseVal}, DL,
-                        Name);
+                        DebugLoc DL, const Twine &Name = "",
+                        std::optional<FastMathFlags> FMFs = std::nullopt) {
+    auto *Select =
+        FMFs ? new VPInstruction(Instruction::Select, {Cond, TrueVal, FalseVal},
+                                 *FMFs, DL, Name)
+             : new VPInstruction(Instruction::Select, {Cond, TrueVal, FalseVal},
+                                 DL, Name);
+    return tryInsertInstruction(Select);
   }
 
   /// Create a new ICmp VPInstruction with predicate \p Pred and operands \p A

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -9141,7 +9141,7 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
       continue;
 
     const RecurrenceDescriptor &RdxDesc = PhiR->getRecurrenceDescriptor();
-    auto *Result = PhiR->getBackedgeValue()->getDefiningRecipe();
+    auto *NewExitingVPV = PhiR->getBackedgeValue();
     // If tail is folded by masking, introduce selects between the phi
     // and the live-out instruction of each reduction, at the beginning of the
     // dedicated latch block.
@@ -9151,21 +9151,20 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
       VPValue *Red = PhiR->getBackedgeValue();
       assert(Red->getDefiningRecipe()->getParent() != LatchVPBB &&
              "reduction recipe must be defined before latch");
-      FastMathFlags FMFs = RdxDesc.getFastMathFlags();
       Type *PhiTy = PhiR->getOperand(0)->getLiveInIRValue()->getType();
-      Result =
+      std::optional<FastMathFlags> FMFs =
           PhiTy->isFloatingPointTy()
-              ? new VPInstruction(Instruction::Select, {Cond, Red, PhiR}, FMFs)
-              : new VPInstruction(Instruction::Select, {Cond, Red, PhiR});
-      Result->insertBefore(&*Builder.getInsertPoint());
-      Red->replaceUsesWithIf(
-          Result->getVPSingleValue(),
-          [](VPUser &U, unsigned) { return isa<VPLiveOut>(&U); });
+              ? std::make_optional(RdxDesc.getFastMathFlags())
+              : std::nullopt;
+      NewExitingVPV = Builder.createSelect(Cond, Red, PhiR, {}, "", FMFs);
+      Red->replaceUsesWithIf(NewExitingVPV, [](VPUser &U, unsigned) {
+        return isa<VPLiveOut>(&U);
+      });
       if (PreferPredicatedReductionSelect ||
           TTI.preferPredicatedReductionSelect(
               PhiR->getRecurrenceDescriptor().getOpcode(), PhiTy,
               TargetTransformInfo::ReductionFlags()))
-        PhiR->setOperand(1, Result->getVPSingleValue());
+        PhiR->setOperand(1, NewExitingVPV);
     }
     // If the vector reduction can be performed in a smaller type, we truncate
     // then extend the loop exit value to enable InstCombine to evaluate the
@@ -9174,17 +9173,17 @@ void LoopVectorizationPlanner::adjustRecipesForReductions(
     if (MinVF.isVector() && PhiTy != RdxDesc.getRecurrenceType()) {
       assert(!PhiR->isInLoop() && "Unexpected truncated inloop reduction!");
       Type *RdxTy = RdxDesc.getRecurrenceType();
-      auto *Trunc = new VPWidenCastRecipe(Instruction::Trunc,
-                                          Result->getVPSingleValue(), RdxTy);
+      auto *Trunc =
+          new VPWidenCastRecipe(Instruction::Trunc, NewExitingVPV, RdxTy);
       auto *Extnd =
           RdxDesc.isSigned()
               ? new VPWidenCastRecipe(Instruction::SExt, Trunc, PhiTy)
               : new VPWidenCastRecipe(Instruction::ZExt, Trunc, PhiTy);
 
-      Trunc->insertAfter(Result);
+      Trunc->insertAfter(NewExitingVPV->getDefiningRecipe());
       Extnd->insertAfter(Trunc);
-      Result->getVPSingleValue()->replaceAllUsesWith(Extnd);
-      Trunc->setOperand(0, Result->getVPSingleValue());
+      NewExitingVPV->replaceAllUsesWith(Extnd);
+      Trunc->setOperand(0, NewExitingVPV);
     }
   }