[VPlan] Make VPRecipeBase inherit from VPDef.

[fhahn]

Summary

This patch makes VPRecipeBase a direct subclass of VPDef, moving the
SubclassID to VPDef.

[fhahn]

Small changes to fix remaining test failures.

[fhahn]

Remove toVPUser, which is unnecessary now

[fhahn]

Updated to keep converted recipes as VPValues.

[fhahn]

Update after VPDef does not inherit from VPUser directly.

[fhahn]

Another round of re-basing

[gilr]

llvm/lib/Transforms/Vectorize/VPlan.cpp

113

IIUC this is still necessary since VPInstruction doesn't register itself as a VPValue in its VPDef (ownership issue?). Does this mean that using the VPDef::defined_values() API won't work when VPInstructions are involved?

[fhahn]

llvm/lib/Transforms/Vectorize/VPlan.cpp

113

IIUC this is still necessary since VPInstruction doesn't register itself as a VPValue in its VPDef (ownership issue?). Does this mean that using the VPDef::defined_values() API won't work when VPInstructions are involved?

Using VPDef for VPInstruction required a bit of extra churn in the original version of the patches. That is why the patch turning VPInstruction into a VPDef is a bit out-of-order. D90565 turns VPInstruction into a VPDef and allows us to get rid of toVPValue. I just updated the patch to do so. With that patch, definedValues should work as expected for all recipes.

[gilr]

llvm/lib/Transforms/Vectorize/VPlan.h

622

Should there be a VPRecipeBase::classof(VPDef *) to support dyn_cast from VPDef to VPRecipeBase?

693

Recipe -> Def

710

Worth documenting here too the importance of the inheritance order.

[fhahn]

Address comments

[fhahn]

llvm/lib/Transforms/Vectorize/VPlan.h

622

yes I added one. For now, it just returns true, as all VPDefs are also VPRecipeBases at the moment. If they diverge, we need to check the IDs.

693

I also updated the other classof calls which were using VPDef *V.

710

I added a comment to VPRecipeBase. Otherwise we would have to add the same comment to all subclasses of VPRecipeBase. Do you think that is sufficient or should I add the comment to the subclasses?

[gilr]

LGTM, tx!

[fhahn]

In D90564#2414165, @gilr wrote:

LGTM, tx!

Great thanks! This depends on a set of patches turning individual recipes into VPDefs. They should be linked correctly in Phabricator now.

[fhahn]

rebase after landing parent changes.

llvm/lib/Transforms/Vectorize/VPlan.h

bool isLegalToHoistInto() {
     // There are currently no constraints that prevent an instruction to be
     // hoisted into a VPBlockBase.
     return true;
   }
 };
 
 /// VPRecipeBase is a base class modeling a sequence of one or more output IR
 /// instructions.
-class VPRecipeBase : public ilist_node_with_parent<VPRecipeBase, VPBasicBlock> {
+class VPRecipeBase : public ilist_node_with_parent<VPRecipeBase, VPBasicBlock>,
+                     public VPDef {
   friend VPBasicBlock;
   friend class VPBlockUtils;
 
-  const unsigned char SubclassID; ///< Subclass identifier (for isa/dyn_cast).
 
   /// Each VPRecipe belongs to a single VPBasicBlock.
   VPBasicBlock *Parent = nullptr;
 
 public:
-  /// An enumeration for keeping track of the concrete subclass of VPRecipeBase
-  /// that is actually instantiated. Values of this enumeration are kept in the
-  /// SubclassID field of the VPRecipeBase objects. They are used for concrete
-  /// type identification.
-  using VPRecipeTy = enum {
-    VPBlendSC,
-    VPBranchOnMaskSC,
-    VPInstructionSC,
-    VPInterleaveSC,
-    VPPredInstPHISC,
-    VPReductionSC,
-    VPReplicateSC,
-    VPWidenCallSC,
-    VPWidenCanonicalIVSC,
-    VPWidenGEPSC,
-    VPWidenIntOrFpInductionSC,
-    VPWidenMemoryInstructionSC,
-    VPWidenPHISC,
-    VPWidenSC,
-    VPWidenSelectSC
-  };
-
-  VPRecipeBase(const unsigned char SC) : SubclassID(SC) {}
+  VPRecipeBase(const unsigned char SC) : VPDef(SC) {}
   virtual ~VPRecipeBase() = default;
 
-  /// \return an ID for the concrete type of this object.
-  /// This is used to implement the classof checks. This should not be used
-  /// for any other purpose, as the values may change as LLVM evolves.
-  unsigned getVPRecipeID() const { return SubclassID; }
-
   /// \return the VPBasicBlock which this VPRecipe belongs to.
   VPBasicBlock *getParent() { return Parent; }
   const VPBasicBlock *getParent() const { return Parent; }
 
   /// The method which generates the output IR instructions that correspond to
   /// this VPRecipe, thereby "executing" the VPlan.
   virtual void execute(struct VPTransformState &State) = 0;
 
public:
   }
   const Instruction *getUnderlyingInstr() const {
     if (auto *VPV = toVPValue())
       return cast_or_null<Instruction>(VPV->getUnderlyingValue());
     return nullptr;
   }
 };
 
-inline bool VPUser::classof(const VPRecipeBase *Recipe) {
-  return Recipe->getVPRecipeID() == VPRecipeBase::VPInstructionSC ||
-         Recipe->getVPRecipeID() == VPRecipeBase::VPWidenSC ||
-         Recipe->getVPRecipeID() == VPRecipeBase::VPWidenCallSC ||
-         Recipe->getVPRecipeID() == VPRecipeBase::VPWidenSelectSC ||
-         Recipe->getVPRecipeID() == VPRecipeBase::VPWidenGEPSC ||
-         Recipe->getVPRecipeID() == VPRecipeBase::VPBlendSC ||
-         Recipe->getVPRecipeID() == VPRecipeBase::VPInterleaveSC ||
-         Recipe->getVPRecipeID() == VPRecipeBase::VPReplicateSC ||
-         Recipe->getVPRecipeID() == VPRecipeBase::VPBranchOnMaskSC ||
-         Recipe->getVPRecipeID() == VPRecipeBase::VPWidenMemoryInstructionSC;
+inline bool VPUser::classof(const VPDef *Recipe) {
+  return Recipe->getVPDefID() == VPRecipeBase::VPInstructionSC ||
+         Recipe->getVPDefID() == VPRecipeBase::VPWidenSC ||
+         Recipe->getVPDefID() == VPRecipeBase::VPWidenCallSC ||
+         Recipe->getVPDefID() == VPRecipeBase::VPWidenSelectSC ||
+         Recipe->getVPDefID() == VPRecipeBase::VPWidenGEPSC ||
+         Recipe->getVPDefID() == VPRecipeBase::VPBlendSC ||
+         Recipe->getVPDefID() == VPRecipeBase::VPInterleaveSC ||
+         Recipe->getVPDefID() == VPRecipeBase::VPReplicateSC ||
+         Recipe->getVPDefID() == VPRecipeBase::VPBranchOnMaskSC ||
+         Recipe->getVPDefID() == VPRecipeBase::VPWidenMemoryInstructionSC;
 }
 
 /// This is a concrete Recipe that models a single VPlan-level instruction.
 /// While as any Recipe it may generate a sequence of IR instructions when
 /// executed, these instructions would always form a single-def expression as
 /// the VPInstruction is also a single def-use vertex.
-class VPInstruction : public VPUser, public VPValue, public VPRecipeBase {
+class VPInstruction : public VPValue, public VPUser, public VPRecipeBase {
   friend class VPlanSlp;
 
 public:
   /// VPlan opcodes, extending LLVM IR with idiomatics instructions.
   enum {
     Not = Instruction::OtherOpsEnd + 1,
     ICmpULE,
     SLPLoad,
private:
   /// modeled instruction.
   void generateInstruction(VPTransformState &State, unsigned Part);
 
 protected:
   void setUnderlyingInstr(Instruction *I) { setUnderlyingValue(I); }
 
 public:
   VPInstruction(unsigned Opcode, ArrayRef<VPValue *> Operands)
-      : VPUser(Operands), VPValue(VPValue::VPInstructionSC),
+      : VPValue(VPValue::VPInstructionSC), VPUser(Operands),
         VPRecipeBase(VPRecipeBase::VPInstructionSC), Opcode(Opcode) {}
 
+  VPInstruction(unsigned Opcode, ArrayRef<VPInstruction *> Operands)
+      : VPValue(VPValue::VPInstructionSC), VPUser({}),
+        VPRecipeBase(VPRecipeBase::VPInstructionSC), Opcode(Opcode) {
+    for (auto *I : Operands)
+      addOperand(I->getVPValue());
+  }
+
   VPInstruction(unsigned Opcode, std::initializer_list<VPValue *> Operands)
       : VPInstruction(Opcode, ArrayRef<VPValue *>(Operands)) {}
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
   static inline bool classof(const VPValue *V) {
     return V->getVPValueID() == VPValue::VPInstructionSC;
   }
 
   VPInstruction *clone() const {
     SmallVector<VPValue *, 2> Operands(operands());
     return new VPInstruction(Opcode, Operands);
   }
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *R) {
-    return R->getVPRecipeID() == VPRecipeBase::VPInstructionSC;
+  static inline bool classof(const VPDef *R) {
+    return R->getVPDefID() == VPRecipeBase::VPInstructionSC;
   }
 
   unsigned getOpcode() const { return Opcode; }
 
   /// Generate the instruction.
   /// TODO: We currently execute only per-part unless a specific instance is
   /// provided.
   void execute(VPTransformState &State) override;

 /// where each ingredient transforms into a vectorized version of itself.
 class VPWidenRecipe : public VPRecipeBase, public VPUser {
   /// Hold the instruction to be widened.
   Instruction &Ingredient;
 
 public:
   template <typename IterT>
   VPWidenRecipe(Instruction &I, iterator_range<IterT> Operands)
-      : VPRecipeBase(VPWidenSC), VPUser(Operands), Ingredient(I) {}
+      : VPRecipeBase(VPWidenSC), VPUser(Operands), Ingredient(I) {
+    new VPValue(&I, this);
+  }
 
   ~VPWidenRecipe() override = default;
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPWidenSC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPWidenSC;
   }
 
   /// Produce widened copies of all Ingredients.
   void execute(VPTransformState &State) override;
 
   /// Print the recipe.
   void print(raw_ostream &O, const Twine &Indent,
              VPSlotTracker &SlotTracker) const override;
 };
 
 /// A recipe for widening Call instructions.
-class VPWidenCallRecipe : public VPRecipeBase,
-                          public VPDef,
-                          public VPUser,
-                          public VPValue {
+class VPWidenCallRecipe : public VPRecipeBase, public VPUser, public VPValue {
 
 public:
   template <typename IterT>
   VPWidenCallRecipe(CallInst &I, iterator_range<IterT> CallArguments)
       : VPRecipeBase(VPRecipeBase::VPWidenCallSC), VPUser(CallArguments),
         VPValue(VPValue::VPVWidenCallSC, &I, this) {}
 
   ~VPWidenCallRecipe() override = default;
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPWidenCallSC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPWidenCallSC;
   }
 
   /// Produce a widened version of the call instruction.
   void execute(VPTransformState &State) override;
 
   /// Print the recipe.
   void print(raw_ostream &O, const Twine &Indent,
              VPSlotTracker &SlotTracker) const override;
 };
 
 /// A recipe for widening select instructions.
-class VPWidenSelectRecipe : public VPRecipeBase,
-                            public VPDef,
-                            public VPUser,
-                            public VPValue {
+class VPWidenSelectRecipe : public VPRecipeBase, public VPUser, public VPValue {
 
   /// Is the condition of the select loop invariant?
   bool InvariantCond;
 
 public:
   template <typename IterT>
   VPWidenSelectRecipe(SelectInst &I, iterator_range<IterT> Operands,
                       bool InvariantCond)
       : VPRecipeBase(VPRecipeBase::VPWidenSelectSC), VPUser(Operands),
         VPValue(VPValue::VPVWidenSelectSC, &I, this),
         InvariantCond(InvariantCond) {}
 
   ~VPWidenSelectRecipe() override = default;
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPWidenSelectSC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPWidenSelectSC;
   }
 
   /// Produce a widened version of the select instruction.
   void execute(VPTransformState &State) override;
 
   /// Print the recipe.
   void print(raw_ostream &O, const Twine &Indent,
              VPSlotTracker &SlotTracker) const override;
 };
 
 /// A recipe for handling GEP instructions.
 class VPWidenGEPRecipe : public VPRecipeBase,
-                         public VPDef,
                          public VPUser,
                          public VPValue {
   bool IsPtrLoopInvariant;
   SmallBitVector IsIndexLoopInvariant;
 
 public:
   template <typename IterT>
   VPWidenGEPRecipe(GetElementPtrInst *GEP, iterator_range<IterT> Operands)
VPWidenGEPRecipe(GetElementPtrInst *GEP, iterator_range<IterT> Operands,
     IsPtrLoopInvariant = OrigLoop->isLoopInvariant(GEP->getPointerOperand());
     for (auto Index : enumerate(GEP->indices()))
       IsIndexLoopInvariant[Index.index()] =
           OrigLoop->isLoopInvariant(Index.value().get());
   }
   ~VPWidenGEPRecipe() override = default;
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPWidenGEPSC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPWidenGEPSC;
   }
 
   /// Generate the gep nodes.
   void execute(VPTransformState &State) override;
 
   /// Print the recipe.
   void print(raw_ostream &O, const Twine &Indent,
              VPSlotTracker &SlotTracker) const override;
 };
 
 /// A recipe for handling phi nodes of integer and floating-point inductions,
 /// producing their vector and scalar values.
 class VPWidenIntOrFpInductionRecipe : public VPRecipeBase {
   PHINode *IV;
   TruncInst *Trunc;
 
 public:
   VPWidenIntOrFpInductionRecipe(PHINode *IV, TruncInst *Trunc = nullptr)
-      : VPRecipeBase(VPWidenIntOrFpInductionSC), IV(IV), Trunc(Trunc) {}
+      : VPRecipeBase(VPWidenIntOrFpInductionSC), IV(IV), Trunc(Trunc) {
+    if (Trunc)
+      new VPValue(Trunc, this);
+    else
+      new VPValue(IV, this);
+  }
   ~VPWidenIntOrFpInductionRecipe() override = default;
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPWidenIntOrFpInductionSC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPWidenIntOrFpInductionSC;
   }
 
   /// Generate the vectorized and scalarized versions of the phi node as
   /// needed by their users.
   void execute(VPTransformState &State) override;
 
   /// Print the recipe.
   void print(raw_ostream &O, const Twine &Indent,
              VPSlotTracker &SlotTracker) const override;
 };
 
 /// A recipe for handling all phi nodes except for integer and FP inductions.
 class VPWidenPHIRecipe : public VPRecipeBase {
   PHINode *Phi;
 
 public:
-  VPWidenPHIRecipe(PHINode *Phi) : VPRecipeBase(VPWidenPHISC), Phi(Phi) {}
+  VPWidenPHIRecipe(PHINode *Phi) : VPRecipeBase(VPWidenPHISC), Phi(Phi) {
+    new VPValue(Phi, this);
+  }
   ~VPWidenPHIRecipe() override = default;
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPWidenPHISC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPWidenPHISC;
   }
 
   /// Generate the phi/select nodes.
   void execute(VPTransformState &State) override;
 
   /// Print the recipe.
   void print(raw_ostream &O, const Twine &Indent,
              VPSlotTracker &SlotTracker) const override;
 };
 
 /// A recipe for vectorizing a phi-node as a sequence of mask-based select
 /// instructions.
 class VPBlendRecipe : public VPRecipeBase, public VPUser {
   PHINode *Phi;
 
 public:
   /// The blend operation is a User of the incoming values and of their
   /// respective masks, ordered [I0, M0, I1, M1, ...]. Note that a single value
   /// might be incoming with a full mask for which there is no VPValue.
   VPBlendRecipe(PHINode *Phi, ArrayRef<VPValue *> Operands)
       : VPRecipeBase(VPBlendSC), VPUser(Operands), Phi(Phi) {
+    new VPValue(Phi, this);
     assert(Operands.size() > 0 &&
            ((Operands.size() == 1) || (Operands.size() % 2 == 0)) &&
            "Expected either a single incoming value or a positive even number "
            "of operands");
   }
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPBlendSC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPBlendSC;
   }
 
   /// Return the number of incoming values, taking into account that a single
   /// incoming value has no mask.
   unsigned getNumIncomingValues() const { return (getNumOperands() + 1) / 2; }
 
   /// Return incoming value number \p Idx.
   VPValue *getIncomingValue(unsigned Idx) const { return getOperand(Idx * 2); }
 
   /// Return mask number \p Idx.
   VPValue *getMask(unsigned Idx) const { return getOperand(Idx * 2 + 1); }
 
   /// Generate the phi/select nodes.
   void execute(VPTransformState &State) override;
 
   /// Print the recipe.
   void print(raw_ostream &O, const Twine &Indent,
              VPSlotTracker &SlotTracker) const override;
 };
 
 /// VPInterleaveRecipe is a recipe for transforming an interleave group of load
 /// or stores into one wide load/store and shuffles.
-class VPInterleaveRecipe : public VPRecipeBase, public VPDef, public VPUser {
+class VPInterleaveRecipe : public VPRecipeBase, public VPUser {
   const InterleaveGroup<Instruction> *IG;
 
 public:
   VPInterleaveRecipe(const InterleaveGroup<Instruction> *IG, VPValue *Addr,
                      VPValue *Mask)
       : VPRecipeBase(VPInterleaveSC), VPUser(Addr), IG(IG) {
     for (unsigned i = 0; i < IG->getFactor(); ++i)
       if (Instruction *I = IG->getMember(i)) {
         if (I->getType()->isVoidTy())
           continue;
         new VPValue(I, this);
       }
 
     if (Mask)
       addOperand(Mask);
   }
   ~VPInterleaveRecipe() override = default;
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPInterleaveSC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPInterleaveSC;
   }
 
   /// Return the address accessed by this recipe.
   VPValue *getAddr() const {
     return getOperand(0); // Address is the 1st, mandatory operand.
   }
 
   /// Return the mask used by this recipe. Note that a full mask is represented
class VPReductionRecipe : public VPRecipeBase {
   /// Pointer to the TTI, needed to create the target reduction
   const TargetTransformInfo *TTI;
 
 public:
   VPReductionRecipe(RecurrenceDescriptor *R, Instruction *I, VPValue *ChainOp,
                     VPValue *VecOp, VPValue *CondOp, bool NoNaN,
                     const TargetTransformInfo *TTI)
       : VPRecipeBase(VPReductionSC), RdxDesc(R), I(I), VecOp(VecOp),
-        ChainOp(ChainOp), CondOp(CondOp), NoNaN(NoNaN), TTI(TTI) {}
+        ChainOp(ChainOp), CondOp(CondOp), NoNaN(NoNaN), TTI(TTI) {
+    new VPValue(I, this);
+  }
 
   ~VPReductionRecipe() override = default;
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPReductionSC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPReductionSC;
   }
 
   /// Generate the reduction in the loop
   void execute(VPTransformState &State) override;
 
   /// Print the recipe.
   void print(raw_ostream &O, const Twine &Indent,
              VPSlotTracker &SlotTracker) const override;
VPReplicateRecipe(Instruction *I, iterator_range<IterT> Operands,
       : VPRecipeBase(VPReplicateSC), VPUser(Operands), Ingredient(I),
         IsUniform(IsUniform), IsPredicated(IsPredicated) {
     // Retain the previous behavior of predicateInstructions(), where an
     // insert-element of a predicated instruction got hoisted into the
     // predicated basic block iff it was its only user. This is achieved by
     // having predicated instructions also pack their values into a vector by
     // default unless they have a replicated user which uses their scalar value.
     AlsoPack = IsPredicated && !I->use_empty();
+    new VPValue(I, this);
   }
 
   ~VPReplicateRecipe() override = default;
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPReplicateSC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPReplicateSC;
   }
 
   /// Generate replicas of the desired Ingredient. Replicas will be generated
   /// for all parts and lanes unless a specific part and lane are specified in
   /// the \p State.
   void execute(VPTransformState &State) override;
 
   void setAlsoPack(bool Pack) { AlsoPack = Pack; }
 
   /// Print the recipe.
   void print(raw_ostream &O, const Twine &Indent,
              VPSlotTracker &SlotTracker) const override;
 };
 
 /// A recipe for generating conditional branches on the bits of a mask.
 class VPBranchOnMaskRecipe : public VPRecipeBase, public VPUser {
 public:
   VPBranchOnMaskRecipe(VPValue *BlockInMask) : VPRecipeBase(VPBranchOnMaskSC) {
+    new VPValue(nullptr, this);
     if (BlockInMask) // nullptr means all-one mask.
       addOperand(BlockInMask);
   }
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPBranchOnMaskSC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPBranchOnMaskSC;
   }
 
   /// Generate the extraction of the appropriate bit from the block mask and the
   /// conditional branch.
   void execute(VPTransformState &State) override;
 
   /// Print the recipe.
   void print(raw_ostream &O, const Twine &Indent,

 /// This recipe works in concert with VPBranchOnMaskRecipe.
 class VPPredInstPHIRecipe : public VPRecipeBase {
   Instruction *PredInst;
 
 public:
   /// Construct a VPPredInstPHIRecipe given \p PredInst whose value needs a phi
   /// nodes after merging back from a Branch-on-Mask.
   VPPredInstPHIRecipe(Instruction *PredInst)
-      : VPRecipeBase(VPPredInstPHISC), PredInst(PredInst) {}
+      : VPRecipeBase(VPPredInstPHISC), PredInst(PredInst) {
+    new VPValue(PredInst, this);
+  }
   ~VPPredInstPHIRecipe() override = default;
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPPredInstPHISC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPPredInstPHISC;
   }
 
   /// Generates phi nodes for live-outs as needed to retain SSA form.
   void execute(VPTransformState &State) override;
 
   /// Print the recipe.
   void print(raw_ostream &O, const Twine &Indent,
              VPSlotTracker &SlotTracker) const override;
 };
 
 /// A Recipe for widening load/store operations.
 /// The recipe uses the following VPValues:
 /// - For load: Address, optional mask
 /// - For store: Address, stored value, optional mask
 /// TODO: We currently execute only per-part unless a specific instance is
 /// provided.
 class VPWidenMemoryInstructionRecipe : public VPRecipeBase,
-                                       public VPDef,
                                        public VPUser,
                                        public VPValue {
   void setMask(VPValue *Mask) {
     if (!Mask)
       return;
     addOperand(Mask);
   }
 
public:
   VPWidenMemoryInstructionRecipe(StoreInst &Store, VPValue *Addr,
                                  VPValue *StoredValue, VPValue *Mask)
       : VPRecipeBase(VPWidenMemoryInstructionSC), VPUser({Addr, StoredValue}),
         VPValue(VPValue::VPMemoryInstructionSC, &Store, this) {
     setMask(Mask);
   }
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPWidenMemoryInstructionSC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPWidenMemoryInstructionSC;
   }
 
   /// Return the address accessed by this recipe.
   VPValue *getAddr() const {
     return getOperand(0); // Address is the 1st, mandatory operand.
   }
 
   /// Return the mask used by this recipe. Note that a full mask is represented
public:
 
   /// Print the recipe.
   void print(raw_ostream &O, const Twine &Indent,
              VPSlotTracker &SlotTracker) const override;
 };
 
 /// A Recipe for widening the canonical induction variable of the vector loop.
 class VPWidenCanonicalIVRecipe : public VPRecipeBase {
-  /// A VPValue representing the canonical vector IV.
-  VPValue Val;
-
 public:
-  VPWidenCanonicalIVRecipe() : VPRecipeBase(VPWidenCanonicalIVSC) {}
-  ~VPWidenCanonicalIVRecipe() override = default;
+  VPWidenCanonicalIVRecipe() : VPRecipeBase(VPWidenCanonicalIVSC) {
+    new VPValue(nullptr, this);
+  }
 
-  /// Return the VPValue representing the canonical vector induction variable of
-  /// the vector loop.
-  const VPValue *getVPValue() const { return &Val; }
-  VPValue *getVPValue() { return &Val; }
+  ~VPWidenCanonicalIVRecipe() override = default;
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *V) {
-    return V->getVPRecipeID() == VPRecipeBase::VPWidenCanonicalIVSC;
+  static inline bool classof(const VPDef *V) {
+    return V->getVPDefID() == VPRecipeBase::VPWidenCanonicalIVSC;
   }
 
   /// Generate a canonical vector induction variable of the vector loop, with
   /// start = {<Part*VF, Part*VF+1, ..., Part*VF+VF-1> for 0 <= Part < UF}, and
   /// step = <VF*UF, VF*UF, ..., VF*UF>.
   void execute(VPTransformState &State) override;
 
   /// Print the recipe.

llvm/lib/Transforms/Vectorize/VPlan.cpp

VPUser *VPRecipeBase::toVPUser() {
   if (auto *U = dyn_cast<VPBranchOnMaskRecipe>(this))
     return U;
   if (auto *U = dyn_cast<VPWidenMemoryInstructionRecipe>(this))
     return U;
   return nullptr;
 }
 
 VPValue *VPRecipeBase::toVPValue() {
+  if (getNumDefinedValues() == 1)
+    return getVPValue();
   if (auto *V = dyn_cast<VPInstruction>(this))
     return V;
-  if (auto *V = dyn_cast<VPWidenMemoryInstructionRecipe>(this))
-    return V;
-  if (auto *V = dyn_cast<VPWidenCallRecipe>(this))
-    return V;
-  if (auto *V = dyn_cast<VPWidenSelectRecipe>(this))
-    return V;
-  if (auto *V = dyn_cast<VPWidenGEPRecipe>(this))
-    return V;
   return nullptr;
 }
 
 const VPValue *VPRecipeBase::toVPValue() const {
+  if (getNumDefinedValues() == 1)
+    return getVPValue();
   if (auto *V = dyn_cast<VPInstruction>(this))
     return V;
-  if (auto *V = dyn_cast<VPWidenMemoryInstructionRecipe>(this))
-    return V;
-  if (auto *V = dyn_cast<VPWidenCallRecipe>(this))
-    return V;
-  if (auto *V = dyn_cast<VPWidenSelectRecipe>(this))
-    return V;
-  if (auto *V = dyn_cast<VPWidenGEPRecipe>(this))
-    return V;
   return nullptr;
 }
 
 // Get the top-most entry block of \p Start. This is the entry block of the
 // containing VPlan. This function is templated to support both const and non-const blocks
 template <typename T> static T *getPlanEntry(T *Start) {
   T *Next = Start;
   T *Current = Start;

llvm/lib/Transforms/Vectorize/VPlanValue.h

 class VPValue {
   friend class VPBuilder;
   friend struct VPlanTransforms;
   friend class VPBasicBlock;
   friend class VPInterleavedAccessInfo;
   friend class VPSlotTracker;
   friend class VPRecipeBase;
   friend class VPDef;
+  friend class VPInstruction;
 
   const unsigned char SubclassID; ///< Subclass identifier (for isa/dyn_cast).
 
   SmallVector<VPUser *, 1> Users;
 
 protected:
   // Hold the underlying Value, if any, attached to this VPValue.
   Value *UnderlyingVal;
public:
   operand_iterator op_end() { return Operands.end(); }
   const_operand_iterator op_end() const { return Operands.end(); }
   operand_range operands() { return operand_range(op_begin(), op_end()); }
   const_operand_range operands() const {
     return const_operand_range(op_begin(), op_end());
   }
 
   /// Method to support type inquiry through isa, cast, and dyn_cast.
-  static inline bool classof(const VPRecipeBase *Recipe);
+  static inline bool classof(const VPDef *Recipe);
 };
 
 /// This class augment a recipe with a set of VPValues defined by the recipe. It
 /// allows recipes to define zero, one or multiple VPValues.
 class VPDef {
   friend class VPValue;
 
+  /// Subclass identifier (for isa/dyn_cast).
+  const unsigned char SubclassID;
+
   /// The VPValues defined by the VPDef.
   TinyPtrVector<VPValue *> DefinedValues;
 
   /// Add \p V as a defined value by the VPDef.
   void addDefinedValue(VPValue *V) {
     assert(V->getDef() == this);
     DefinedValues.push_back(V);
   }
 
 public:
-  VPDef() {}
+  /// An enumeration for keeping track of the concrete subclass of VPRecipeBase
+  /// that is actually instantiated. Values of this enumeration are kept in the
+  /// SubclassID field of the VPRecipeBase objects. They are used for concrete
+  /// type identification.
+  using VPRecipeTy = enum {
+    VPBlendSC,
+    VPBranchOnMaskSC,
+    VPInstructionSC,
+    VPInterleaveSC,
+    VPPredInstPHISC,
+    VPReductionSC,
+    VPReplicateSC,
+    VPWidenCallSC,
+    VPWidenCanonicalIVSC,
+    VPWidenGEPSC,
+    VPWidenIntOrFpInductionSC,
+    VPWidenMemoryInstructionSC,
+    VPWidenPHISC,
+    VPWidenSC,
+    VPWidenSelectSC
+  };
+
+  VPDef(const unsigned char SC) : SubclassID(SC) {}
 
   virtual ~VPDef() {
     for (VPValue *D : DefinedValues) {
       assert(D->Def == this &&
              "all defined VPValues should point to the containing VPDef");
       assert(D->getNumUsers() == 0 &&
              "all defined VPValues should have no more users");
       D->Def = nullptr;
const VPValue *getVPValue(unsigned I = 0) const {
     return DefinedValues[I];
   }
 
   /// Returns an ArrayRef of the defined values by the VPDef.
   ArrayRef<VPValue *> defined_values() { return DefinedValues; }
 
   /// Returns the number of values defined by the VPDef.
   unsigned getNumDefinedValues() const { return DefinedValues.size(); }
+
+  /// \return an ID for the concrete type of this object.
+  /// This is used to implement the classof checks. This should not be used
+  /// for any other purpose, as the values may change as LLVM evolves.
+  unsigned getVPDefID() const { return SubclassID; }
 };
 
 class VPlan;
 class VPBasicBlock;
 class VPRegionBlock;
 
 /// This class can be used to assign consecutive numbers to all VPValues in a
 /// VPlan and allows querying the numbering for printing, similar to the

llvm/unittests/Transforms/Vectorize/VPlanTest.cpp

 
 TEST(VPRecipeTest, CastVPInstructionToVPUser) {
   VPValue Op1;
   VPValue Op2;
   VPInstruction Recipe(Instruction::Add, {&Op1, &Op2});
   EXPECT_TRUE(isa<VPUser>(&Recipe));
   VPRecipeBase *BaseR = &Recipe;
   EXPECT_TRUE(isa<VPUser>(BaseR));
-  EXPECT_EQ(&Recipe, BaseR->toVPUser());
+  EXPECT_EQ(&Recipe, BaseR);
 }
 
 TEST(VPRecipeTest, CastVPWidenRecipeToVPUser) {
   LLVMContext C;
 
   IntegerType *Int32 = IntegerType::get(C, 32);
   auto *AI =
       BinaryOperator::CreateAdd(UndefValue::get(Int32), UndefValue::get(Int32));
   VPValue Op1;
   VPValue Op2;
   SmallVector<VPValue *, 2> Args;
   Args.push_back(&Op1);
   Args.push_back(&Op1);
   VPWidenRecipe WidenR(*AI, make_range(Args.begin(), Args.end()));
   EXPECT_TRUE(isa<VPUser>(&WidenR));
   VPRecipeBase *WidenRBase = &WidenR;
   EXPECT_TRUE(isa<VPUser>(WidenRBase));
-  EXPECT_EQ(&WidenR, WidenRBase->toVPUser());
+  EXPECT_EQ(&WidenR, WidenRBase);
   delete AI;
 }
 
 TEST(VPRecipeTest, CastVPWidenCallRecipeToVPUser) {
   LLVMContext C;
 
   IntegerType *Int32 = IntegerType::get(C, 32);
   FunctionType *FTy = FunctionType::get(Int32, false);
   auto *Call = CallInst::Create(FTy, UndefValue::get(FTy));
   VPValue Op1;
   VPValue Op2;
   SmallVector<VPValue *, 2> Args;
   Args.push_back(&Op1);
   Args.push_back(&Op2);
   VPWidenCallRecipe Recipe(*Call, make_range(Args.begin(), Args.end()));
   EXPECT_TRUE(isa<VPUser>(&Recipe));
   VPRecipeBase *BaseR = &Recipe;
   EXPECT_TRUE(isa<VPUser>(BaseR));
-  EXPECT_EQ(&Recipe, BaseR->toVPUser());
+  EXPECT_EQ(&Recipe, BaseR);
   delete Call;
 }
 
 TEST(VPRecipeTest, CastVPWidenSelectRecipeToVPUser) {
   LLVMContext C;
 
   IntegerType *Int1 = IntegerType::get(C, 1);
   IntegerType *Int32 = IntegerType::get(C, 32);
   auto *SelectI = SelectInst::Create(
       UndefValue::get(Int1), UndefValue::get(Int32), UndefValue::get(Int32));
   VPValue Op1;
   VPValue Op2;
   VPValue Op3;
   SmallVector<VPValue *, 4> Args;
   Args.push_back(&Op1);
   Args.push_back(&Op2);
   Args.push_back(&Op3);
   VPWidenSelectRecipe WidenSelectR(*SelectI,
                                    make_range(Args.begin(), Args.end()), false);
   EXPECT_TRUE(isa<VPUser>(&WidenSelectR));
   VPRecipeBase *BaseR = &WidenSelectR;
   EXPECT_TRUE(isa<VPUser>(BaseR));
-  EXPECT_EQ(&WidenSelectR, BaseR->toVPUser());
+  EXPECT_EQ(&WidenSelectR, BaseR);
   delete SelectI;
 }
 
 TEST(VPRecipeTest, CastVPWidenGEPRecipeToVPUser) {
   LLVMContext C;
 
   IntegerType *Int32 = IntegerType::get(C, 32);
   PointerType *Int32Ptr = PointerType::get(Int32, 0);
   auto *GEP = GetElementPtrInst::Create(Int32, UndefValue::get(Int32Ptr),
                                         UndefValue::get(Int32));
   VPValue Op1;
   VPValue Op2;
   SmallVector<VPValue *, 4> Args;
   Args.push_back(&Op1);
   Args.push_back(&Op2);
   VPWidenGEPRecipe Recipe(GEP, make_range(Args.begin(), Args.end()));
   EXPECT_TRUE(isa<VPUser>(&Recipe));
   VPRecipeBase *BaseR = &Recipe;
   EXPECT_TRUE(isa<VPUser>(BaseR));
-  EXPECT_EQ(&Recipe, BaseR->toVPUser());
+  EXPECT_EQ(&Recipe, BaseR);
   delete GEP;
 }
 
 TEST(VPRecipeTest, CastVPBlendRecipeToVPUser) {
   LLVMContext C;
 
   IntegerType *Int32 = IntegerType::get(C, 32);
   auto *Phi = PHINode::Create(Int32, 1);
TEST(VPRecipeTest, CastVPInterleaveRecipeToVPUser) {
 
   VPValue Addr;
   VPValue Mask;
   InterleaveGroup<Instruction> IG(4, false, Align(4));
   VPInterleaveRecipe Recipe(&IG, &Addr, &Mask);
   EXPECT_TRUE(isa<VPUser>(&Recipe));
   VPRecipeBase *BaseR = &Recipe;
   EXPECT_TRUE(isa<VPUser>(BaseR));
-  EXPECT_EQ(&Recipe, BaseR->toVPUser());
+  EXPECT_EQ(&Recipe, BaseR);
 }
 
 TEST(VPRecipeTest, CastVPReplicateRecipeToVPUser) {
   LLVMContext C;
 
   VPValue Op1;
   VPValue Op2;
   SmallVector<VPValue *, 4> Args;

 TEST(VPRecipeTest, CastVPBranchOnMaskRecipeToVPUser) {
   LLVMContext C;
 
   VPValue Mask;
   VPBranchOnMaskRecipe Recipe(&Mask);
   EXPECT_TRUE(isa<VPUser>(&Recipe));
   VPRecipeBase *BaseR = &Recipe;
   EXPECT_TRUE(isa<VPUser>(BaseR));
-  EXPECT_EQ(&Recipe, BaseR->toVPUser());
+  EXPECT_EQ(&Recipe, BaseR);
 }
 
 TEST(VPRecipeTest, CastVPWidenMemoryInstructionRecipeToVPUser) {
   LLVMContext C;
 
   IntegerType *Int32 = IntegerType::get(C, 32);
   PointerType *Int32Ptr = PointerType::get(Int32, 0);
   auto *Load =
       new LoadInst(Int32, UndefValue::get(Int32Ptr), "", false, Align(1));
   VPValue Addr;
   VPValue Mask;
   VPWidenMemoryInstructionRecipe Recipe(*Load, &Addr, &Mask);
   EXPECT_TRUE(isa<VPUser>(&Recipe));
   VPRecipeBase *BaseR = &Recipe;
   EXPECT_TRUE(isa<VPUser>(BaseR));
-  EXPECT_EQ(&Recipe, BaseR->toVPUser());
+  EXPECT_EQ(&Recipe, BaseR);
   delete Load;
 }
 
-struct VPMultiDef : public VPDef {
+struct VPMultiDef : public VPUser, public VPDef {
   SmallVector<VPValue *, 4> Defs;
 
-  VPMultiDef() : VPDef({}) {
+  VPMultiDef() : VPUser({}), VPDef(0) {
     new VPValue(nullptr, this);
     new VPValue(nullptr, this);
   }
 };
 
 TEST(VPMultiValueTest, traverseUseLists) {
   // Check that the def-use chains of a multi-def can be traversed in both
   // directions.