[VPlan] Add VPRecipeBase::getRegion helper (NFC).

Multiple places retrieve the region for a recipe. Add a helper to make
the code more compact and clearer.

Author: fhahn

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -407,6 +407,10 @@ class LLVM_ABI_FOR_TEST VPRecipeBase
   VPBasicBlock *getParent() { return Parent; }
   const VPBasicBlock *getParent() const { return Parent; }
 
+  /// \return the VPRegionBlock which the recipe belongs to.
+  VPRegionBlock *getRegion();
+  const VPRegionBlock *getRegion() const;
+
   /// The method which generates the output IR instructions that correspond to
   /// this VPRecipe, thereby "executing" the VPlan.
   virtual void execute(VPTransformState &State) = 0;
@@ -4075,6 +4079,14 @@ class LLVM_ABI_FOR_TEST VPRegionBlock : public VPBlockBase {
   }
 };
 
+inline VPRegionBlock *VPRecipeBase::getRegion() {
+  return getParent()->getParent();
+}
+
+inline const VPRegionBlock *VPRecipeBase::getRegion() const {
+  return getParent()->getParent();
+}
+
 /// VPlan models a candidate for vectorization, encoding various decisions take
 /// to produce efficient output IR, including which branches, basic-blocks and
 /// output IR instructions to generate, and their cost. VPlan holds a

llvm/lib/Transforms/Vectorize/VPlanAnalysis.cpp

@@ -377,7 +377,7 @@ bool VPDominatorTree::properlyDominates(const VPRecipeBase *A,
 
 #ifndef NDEBUG
   auto GetReplicateRegion = [](VPRecipeBase *R) -> VPRegionBlock * {
-    auto *Region = dyn_cast_or_null<VPRegionBlock>(R->getParent()->getParent());
+    VPRegionBlock *Region = R->getRegion();
     if (Region && Region->isReplicator()) {
       assert(Region->getNumSuccessors() == 1 &&
              Region->getNumPredecessors() == 1 && "Expected SESE region!");

llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp

@@ -2352,7 +2352,7 @@ bool VPWidenIntOrFpInductionRecipe::isCanonical() const {
     return false;
   auto *StepC = dyn_cast<ConstantInt>(getStepValue()->getLiveInIRValue());
   auto *StartC = dyn_cast<ConstantInt>(getStartValue()->getLiveInIRValue());
-  auto *CanIV = getParent()->getParent()->getCanonicalIV();
+  auto *CanIV = getRegion()->getCanonicalIV();
   return StartC && StartC->isZero() && StepC && StepC->isOne() &&
          getScalarType() == CanIV->getScalarType();
 }
@@ -3076,7 +3076,7 @@ static void scalarizeInstruction(const Instruction *Instr,
     State.AC->registerAssumption(II);
 
   assert(
-      (RepRecipe->getParent()->getParent() ||
+      (RepRecipe->getRegion() ||
        !RepRecipe->getParent()->getPlan()->getVectorLoopRegion() ||
        all_of(RepRecipe->operands(),
               [](VPValue *Op) { return Op->isDefinedOutsideLoopRegions(); })) &&
@@ -3268,7 +3268,7 @@ InstructionCost VPReplicateRecipe::computeCost(ElementCount VF,
                                               to_vector(operands()), VF);
     // If the recipe is not predicated (i.e. not in a replicate region), return
     // the scalar cost. Otherwise handle predicated cost.
-    if (!getParent()->getParent()->isReplicator())
+    if (!getRegion()->isReplicator())
       return ScalarCost;
 
     // Account for the phi nodes that we will create.
@@ -3284,7 +3284,7 @@ InstructionCost VPReplicateRecipe::computeCost(ElementCount VF,
   case Instruction::Store: {
     // TODO: See getMemInstScalarizationCost for how to handle replicating and
     // predicated cases.
-    const VPRegionBlock *ParentRegion = getParent()->getParent();
+    const VPRegionBlock *ParentRegion = getRegion();
     if (ParentRegion && ParentRegion->isReplicator())
       break;
 

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -1858,8 +1858,8 @@ static bool hoistPreviousBeforeFORUsers(VPFirstOrderRecurrencePHIRecipe *FOR,
       return nullptr;
     VPRegionBlock *EnclosingLoopRegion =
         HoistCandidate->getParent()->getEnclosingLoopRegion();
-    assert((!HoistCandidate->getParent()->getParent() ||
-            HoistCandidate->getParent()->getParent() == EnclosingLoopRegion) &&
+    assert((!HoistCandidate->getRegion() ||
+            HoistCandidate->getRegion() == EnclosingLoopRegion) &&
            "CFG in VPlan should still be flat, without replicate regions");
     // Hoist candidate was already visited, no need to hoist.
     if (!Visited.insert(HoistCandidate).second)
@@ -2898,7 +2898,7 @@ void VPlanTransforms::replaceSymbolicStrides(
   // evolution.
   auto CanUseVersionedStride = [&Plan](VPUser &U, unsigned) {
     auto *R = cast<VPRecipeBase>(&U);
-    return R->getParent()->getParent() ||
+    return R->getRegion() ||
            R->getParent() == Plan.getVectorLoopRegion()->getSinglePredecessor();
   };
   ValueToSCEVMapTy RewriteMap;
@@ -3803,8 +3803,7 @@ void VPlanTransforms::materializeBuildVectors(VPlan &Plan) {
         continue;
       auto *DefR = cast<VPRecipeWithIRFlags>(&R);
       auto UsesVectorOrInsideReplicateRegion = [DefR, LoopRegion](VPUser *U) {
-        VPRegionBlock *ParentRegion =
-            cast<VPRecipeBase>(U)->getParent()->getParent();
+        VPRegionBlock *ParentRegion = cast<VPRecipeBase>(U)->getRegion();
         return !U->usesScalars(DefR) || ParentRegion != LoopRegion;
       };
       if ((isa<VPReplicateRecipe>(DefR) &&

llvm/lib/Transforms/Vectorize/VPlanUtils.h

@@ -64,7 +64,7 @@ inline bool isSingleScalar(const VPValue *VPV) {
     return true;
 
   if (auto *Rep = dyn_cast<VPReplicateRecipe>(VPV)) {
-    const VPRegionBlock *RegionOfR = Rep->getParent()->getParent();
+    const VPRegionBlock *RegionOfR = Rep->getRegion();
     // Don't consider recipes in replicate regions as uniform yet; their first
     // lane cannot be accessed when executing the replicate region for other
     // lanes.