[VPlan] Add VPUserID to distinguish between recipes and others.

This allows cast/dyn_cast'ing from VPUser to recipes. This is needed
because there are VPUsers that are not recipes.

Reviewed By: gilr, a.elovikov

Differential Revision: https://reviews.llvm.org/D100257

llvm/lib/Transforms/Vectorize/VPlan.cpp

@@ -188,56 +188,26 @@ VPBlockBase *VPBlockBase::getEnclosingBlockWithPredecessors() {
   return Parent->getEnclosingBlockWithPredecessors();
 }
 
-static VPValue *getSingleOperandOrNull(VPUser &U) {
-  if (U.getNumOperands() == 1)
-    return U.getOperand(0);
-
-  return nullptr;
-}
-
-static const VPValue *getSingleOperandOrNull(const VPUser &U) {
-  if (U.getNumOperands() == 1)
-    return U.getOperand(0);
-
-  return nullptr;
-}
-
-static void resetSingleOpUser(VPUser &U, VPValue *NewVal) {
-  assert(U.getNumOperands() <= 1 && "Didn't expect more than one operand!");
-  if (!NewVal) {
-    if (U.getNumOperands() == 1)
-      U.removeLastOperand();
-    return;
-  }
-
-  if (U.getNumOperands() == 1)
-    U.setOperand(0, NewVal);
-  else
-    U.addOperand(NewVal);
-}
-
 VPValue *VPBlockBase::getCondBit() {
-  return getSingleOperandOrNull(CondBitUser);
+  return CondBitUser.getSingleOperandOrNull();
 }
 
 const VPValue *VPBlockBase::getCondBit() const {
-  return getSingleOperandOrNull(CondBitUser);
+  return CondBitUser.getSingleOperandOrNull();
 }
 
-void VPBlockBase::setCondBit(VPValue *CV) {
-  resetSingleOpUser(CondBitUser, CV);
-}
+void VPBlockBase::setCondBit(VPValue *CV) { CondBitUser.resetSingleOpUser(CV); }
 
 VPValue *VPBlockBase::getPredicate() {
-  return getSingleOperandOrNull(PredicateUser);
+  return PredicateUser.getSingleOperandOrNull();
 }
 
 const VPValue *VPBlockBase::getPredicate() const {
-  return getSingleOperandOrNull(PredicateUser);
+  return PredicateUser.getSingleOperandOrNull();
 }
 
 void VPBlockBase::setPredicate(VPValue *CV) {
-  resetSingleOpUser(PredicateUser, CV);
+  PredicateUser.resetSingleOpUser(CV);
 }
 
 void VPBlockBase::deleteCFG(VPBlockBase *Entry) {

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -341,6 +341,41 @@ struct VPTransformState {
   VPlan *Plan;
 };
 
+/// VPUsers instance used by VPBlockBase to manage CondBit and the block
+/// predicate. Currently VPBlockUsers are used in VPBlockBase for historical
+/// reasons, but in the future the only VPUsers should either be recipes or
+/// live-outs.VPBlockBase uses.
+struct VPBlockUser : public VPUser {
+  VPBlockUser() : VPUser({}, VPUserID::Block) {}
+
+  VPValue *getSingleOperandOrNull() {
+    if (getNumOperands() == 1)
+      return getOperand(0);
+
+    return nullptr;
+  }
+  const VPValue *getSingleOperandOrNull() const {
+    if (getNumOperands() == 1)
+      return getOperand(0);
+
+    return nullptr;
+  }
+
+  void resetSingleOpUser(VPValue *NewVal) {
+    assert(getNumOperands() <= 1 && "Didn't expect more than one operand!");
+    if (!NewVal) {
+      if (getNumOperands() == 1)
+        removeLastOperand();
+      return;
+    }
+
+    if (getNumOperands() == 1)
+      setOperand(0, NewVal);
+    else
+      addOperand(NewVal);
+  }
+};
+
 /// VPBlockBase is the building block of the Hierarchical Control-Flow Graph.
 /// A VPBlockBase can be either a VPBasicBlock or a VPRegionBlock.
 class VPBlockBase {
@@ -364,12 +399,12 @@ class VPBlockBase {
   /// Successor selector managed by a VPUser. For blocks with zero or one
   /// successors, there is no operand. Otherwise there is exactly one operand
   /// which is the branch condition.
-  VPUser CondBitUser;
+  VPBlockUser CondBitUser;
 
   /// If the block is predicated, its predicate is stored as an operand of this
   /// VPUser to maintain the def-use relations. Otherwise there is no operand
   /// here.
-  VPUser PredicateUser;
+  VPBlockUser PredicateUser;
 
   /// VPlan containing the block. Can only be set on the entry block of the
   /// plan.
@@ -621,17 +656,16 @@ class VPRecipeBase : public ilist_node_with_parent<VPRecipeBase, VPBasicBlock>,
   friend VPBasicBlock;
   friend class VPBlockUtils;
 
-
   /// Each VPRecipe belongs to a single VPBasicBlock.
   VPBasicBlock *Parent = nullptr;
 
 public:
   VPRecipeBase(const unsigned char SC, ArrayRef<VPValue *> Operands)
-      : VPDef(SC), VPUser(Operands) {}
+      : VPDef(SC), VPUser(Operands, VPUser::VPUserID::Recipe) {}
 
   template <typename IterT>
   VPRecipeBase(const unsigned char SC, iterator_range<IterT> Operands)
-      : VPDef(SC), VPUser(Operands) {}
+      : VPDef(SC), VPUser(Operands, VPUser::VPUserID::Recipe) {}
   virtual ~VPRecipeBase() = default;
 
   /// \return the VPBasicBlock which this VPRecipe belongs to.
@@ -683,6 +717,10 @@ public:
     return true;
   }
 
+  static inline bool classof(const VPUser *U) {
+    return U->getVPUserID() == VPUser::VPUserID::Recipe;
+  }
+
   /// Returns true if the recipe may have side-effects.
   bool mayHaveSideEffects() const;
 

llvm/lib/Transforms/Vectorize/VPlanValue.h

@@ -191,28 +191,42 @@ raw_ostream &operator<<(raw_ostream &OS, const VPValue &V);
 /// This class augments VPValue with operands which provide the inverse def-use
 /// edges from VPValue's users to their defs.
 class VPUser {
+public:
+  /// Subclass identifier (for isa/dyn_cast).
+  enum class VPUserID {
+    Recipe,
+    // TODO: Currently VPUsers are used in VPBlockBase, but in the future the
+    // only VPUsers should either be recipes or live-outs.
+    Block
+  };
+
+private:
   SmallVector<VPValue *, 2> Operands;
 
+  VPUserID ID;
+
 protected:
 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
   /// Print the operands to \p O.
   void printOperands(raw_ostream &O, VPSlotTracker &SlotTracker) const;
 #endif
 
+  VPUser(ArrayRef<VPValue *> Operands, VPUserID ID) : ID(ID) {
+    for (VPValue *Operand : Operands)
+      addOperand(Operand);
+  }
+
+  VPUser(std::initializer_list<VPValue *> Operands, VPUserID ID)
+      : VPUser(ArrayRef<VPValue *>(Operands), ID) {}
+
+  template <typename IterT>
+  VPUser(iterator_range<IterT> Operands, VPUserID ID) : ID(ID) {
+    for (VPValue *Operand : Operands)
+      addOperand(Operand);
+  }
+
 public:
-  VPUser() {}
-  VPUser(ArrayRef<VPValue *> Operands) {
-    for (VPValue *Operand : Operands)
-      addOperand(Operand);
-  }
-
-  VPUser(std::initializer_list<VPValue *> Operands)
-      : VPUser(ArrayRef<VPValue *>(Operands)) {}
-  template <typename IterT> VPUser(iterator_range<IterT> Operands) {
-    for (VPValue *Operand : Operands)
-      addOperand(Operand);
-  }
-
+  VPUser() = delete;
   VPUser(const VPUser &) = delete;
   VPUser &operator=(const VPUser &) = delete;
   virtual ~VPUser() {
@@ -220,6 +234,8 @@ public:
       Op->removeUser(*this);
   }
 
+  VPUserID getVPUserID() const { return ID; }
+
   void addOperand(VPValue *Operand) {
     Operands.push_back(Operand);
     Operand->addUser(*this);