[VPlan] Remove getNumUsers(), replace with targeted helpers.

Most users of getNumUsers() only care about 3 case:
 * no users
 * one (unique) user
 * or more than one (unique) user

Instead of providing getNumUsers, provide helpers that accurately
check for the 3 cases above, handling duplicates.

Author: fhahn

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -4174,7 +4174,7 @@ VectorizationFactor LoopVectorizationPlanner::selectVectorizationFactor() {
           // divisors.
           case Instruction::Select: {
             VPValue *VPV = VPI->getVPSingleValue();
-            if (VPV->getNumUsers() == 1) {
+            if (VPV->hasOneUser()) {
               if (auto *WR = dyn_cast<VPWidenRecipe>(*VPV->user_begin())) {
                 switch (WR->getOpcode()) {
                 case Instruction::UDiv:

llvm/lib/Transforms/Vectorize/VPlan.cpp

@@ -1066,25 +1066,25 @@ const VPRegionBlock *VPlan::getVectorLoopRegion() const {
 void VPlan::printLiveIns(raw_ostream &O) const {
   VPSlotTracker SlotTracker(this);
 
-  if (VF.getNumUsers() > 0) {
+  if (VF.hasUsers()) {
     O << "\nLive-in ";
     VF.printAsOperand(O, SlotTracker);
     O << " = VF";
   }
 
-  if (VFxUF.getNumUsers() > 0) {
+  if (VFxUF.hasUsers()) {
     O << "\nLive-in ";
     VFxUF.printAsOperand(O, SlotTracker);
     O << " = VF * UF";
   }
 
-  if (VectorTripCount.getNumUsers() > 0) {
+  if (VectorTripCount.hasUsers()) {
     O << "\nLive-in ";
     VectorTripCount.printAsOperand(O, SlotTracker);
     O << " = vector-trip-count";
   }
 
-  if (BackedgeTakenCount && BackedgeTakenCount->getNumUsers()) {
+  if (BackedgeTakenCount && BackedgeTakenCount->hasUsers()) {
     O << "\nLive-in ";
     BackedgeTakenCount->printAsOperand(O, SlotTracker);
     O << " = backedge-taken count";
@@ -1502,9 +1502,9 @@ void VPSlotTracker::assignName(const VPValue *V) {
 }
 
 void VPSlotTracker::assignNames(const VPlan &Plan) {
-  if (Plan.VF.getNumUsers() > 0)
+  if (Plan.VF.hasUsers())
     assignName(&Plan.VF);
-  if (Plan.VFxUF.getNumUsers() > 0)
+  if (Plan.VFxUF.hasUsers())
     assignName(&Plan.VFxUF);
   assignName(&Plan.VectorTripCount);
   if (Plan.BackedgeTakenCount)

llvm/lib/Transforms/Vectorize/VPlan.h

@@ -4218,7 +4218,7 @@ class VPlan {
   /// Resets the trip count for the VPlan. The caller must make sure all uses of
   /// the original trip count have been replaced.
   void resetTripCount(VPValue *NewTripCount) {
-    assert(TripCount && NewTripCount && TripCount->getNumUsers() == 0 &&
+    assert(TripCount && NewTripCount && TripCount->hasNoUsers() &&
            "TripCount must be set when resetting");
     TripCount = NewTripCount;
   }

llvm/lib/Transforms/Vectorize/VPlanConstruction.cpp

@@ -888,7 +888,7 @@ bool VPlanTransforms::handleMaxMinNumReductions(VPlan &Plan) {
     if (VecV == RdxResult)
       continue;
     if (auto *DerivedIV = dyn_cast<VPDerivedIVRecipe>(VecV)) {
-      if (DerivedIV->getNumUsers() == 1 &&
+      if (DerivedIV->hasOneUser() &&
           DerivedIV->getOperand(1) == &Plan.getVectorTripCount()) {
         auto *NewSel = Builder.createSelect(AnyNaN, Plan.getCanonicalIV(),
                                             &Plan.getVectorTripCount());

llvm/lib/Transforms/Vectorize/VPlanRecipes.cpp

@@ -2285,7 +2285,7 @@ InstructionCost VPWidenCastRecipe::computeCost(ElementCount VF,
   TTI::CastContextHint CCH = TTI::CastContextHint::None;
   // For Trunc/FPTrunc, get the context from the only user.
   if ((Opcode == Instruction::Trunc || Opcode == Instruction::FPTrunc) &&
-      !hasMoreThanOneUniqueUser() && getNumUsers() > 0) {
+      hasOneUser()) {
     if (auto *StoreRecipe = dyn_cast<VPRecipeBase>(*user_begin()))
       CCH = ComputeCCH(StoreRecipe);
   }

llvm/lib/Transforms/Vectorize/VPlanSLP.cpp

@@ -156,8 +156,7 @@ bool VPlanSlp::areVectorizable(ArrayRef<VPValue *> Operands) const {
     return false;
   }
 
-  if (any_of(Operands,
-             [](VPValue *Op) { return Op->hasMoreThanOneUniqueUser(); })) {
+  if (any_of(Operands, [](VPValue *Op) { return !Op->hasNoOrOneUser(); })) {
     LLVM_DEBUG(dbgs() << "VPSLP: Some operands have multiple users.\n");
     return false;
   }

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

@@ -316,7 +316,7 @@ static bool mergeReplicateRegionsIntoSuccessors(VPlan &Plan) {
       });
 
       // Remove phi recipes that are unused after merging the regions.
-      if (Phi1ToMove.getVPSingleValue()->getNumUsers() == 0) {
+      if (Phi1ToMove.getVPSingleValue()->hasNoUsers()) {
         Phi1ToMove.eraseFromParent();
         continue;
       }
@@ -363,7 +363,7 @@ static VPRegionBlock *createReplicateRegion(VPReplicateRecipe *PredRecipe,
       Plan.createVPBasicBlock(Twine(RegionName) + ".if", RecipeWithoutMask);
 
   VPPredInstPHIRecipe *PHIRecipe = nullptr;
-  if (PredRecipe->getNumUsers() != 0) {
+  if (!PredRecipe->hasNoUsers()) {
     PHIRecipe = new VPPredInstPHIRecipe(RecipeWithoutMask,
                                         RecipeWithoutMask->getDebugLoc());
     PredRecipe->replaceAllUsesWith(PHIRecipe);
@@ -546,8 +546,7 @@ static bool isDeadRecipe(VPRecipeBase &R) {
     return false;
 
   // Recipe is dead if no user keeps the recipe alive.
-  return all_of(R.definedValues(),
-                [](VPValue *V) { return V->getNumUsers() == 0; });
+  return all_of(R.definedValues(), [](VPValue *V) { return V->hasNoUsers(); });
 }
 
 void VPlanTransforms::removeDeadRecipes(VPlan &Plan) {
@@ -563,11 +562,11 @@ void VPlanTransforms::removeDeadRecipes(VPlan &Plan) {
 
       // Check if R is a dead VPPhi <-> update cycle and remove it.
       auto *PhiR = dyn_cast<VPPhi>(&R);
-      if (!PhiR || PhiR->getNumOperands() != 2 || PhiR->getNumUsers() != 1)
+      if (!PhiR || PhiR->getNumOperands() != 2 || !PhiR->hasOneUser())
         continue;
       VPValue *Incoming = PhiR->getOperand(1);
       if (*PhiR->user_begin() != Incoming->getDefiningRecipe() ||
-          Incoming->getNumUsers() != 1)
+          !Incoming->hasOneUser())
         continue;
       PhiR->replaceAllUsesWith(PhiR->getOperand(0));
       PhiR->eraseFromParent();
@@ -658,7 +657,7 @@ static void legalizeAndOptimizeInductions(VPlan &Plan) {
       auto *RepR = dyn_cast<VPReplicateRecipe>(U);
       // Skip recipes that shouldn't be narrowed.
       if (!Def || !isa<VPReplicateRecipe, VPWidenRecipe>(Def) ||
-          Def->getNumUsers() == 0 || !Def->getUnderlyingValue() ||
+          Def->hasNoUsers() || !Def->getUnderlyingValue() ||
           (RepR && (RepR->isSingleScalar() || RepR->isPredicated())))
         continue;
 
@@ -1103,8 +1102,8 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
                               m_LogicalAnd(m_Deferred(X), m_VPValue(Z)))) &&
       // Simplify only if one of the operands has one use to avoid creating an
       // extra recipe.
-      (!Def->getOperand(0)->hasMoreThanOneUniqueUser() ||
-       !Def->getOperand(1)->hasMoreThanOneUniqueUser()))
+      (Def->getOperand(0)->hasNoOrOneUser() ||
+       Def->getOperand(1)->hasNoOrOneUser()))
     return Def->replaceAllUsesWith(
         Builder.createLogicalAnd(X, Builder.createOr(Y, Z)));
 
@@ -1130,7 +1129,7 @@ static void simplifyRecipe(VPRecipeBase &R, VPTypeAnalysis &TypeInfo) {
   // further.
   if (match(Def, m_LogicalAnd(m_LogicalAnd(m_VPValue(X), m_VPValue(Y)),
                               m_VPValue(Z))) &&
-      X->hasMoreThanOneUniqueUser())
+      !X->hasNoOrOneUser())
     return Def->replaceAllUsesWith(
         Builder.createLogicalAnd(X, Builder.createLogicalAnd(Y, Z)));
 
@@ -1383,7 +1382,7 @@ static void simplifyBlends(VPlan &Plan) {
         // TODO: Find the most expensive mask that can be deadcoded, or a mask
         // that's used by multiple blends where it can be removed from them all.
         VPValue *Mask = Blend->getMask(I);
-        if (Mask->getNumUsers() == 1 && !match(Mask, m_False())) {
+        if (Mask->hasOneUser() && !match(Mask, m_False())) {
           StartIndex = I;
           break;
         }
@@ -1419,7 +1418,7 @@ static void simplifyBlends(VPlan &Plan) {
         NewBlend->setOperand(0, Inc1);
         NewBlend->setOperand(1, Inc0);
         NewBlend->setOperand(2, NewMask);
-        if (OldMask->getNumUsers() == 0)
+        if (OldMask->hasNoUsers())
           cast<VPInstruction>(OldMask)->eraseFromParent();
       }
     }
@@ -1466,8 +1465,7 @@ static bool optimizeVectorInductionWidthForTCAndVFUF(VPlan &Plan,
     // Currently only handle canonical IVs as it is trivial to replace the start
     // and stop values, and we currently only perform the optimization when the
     // IV has a single use.
-    if (!WideIV || !WideIV->isCanonical() ||
-        WideIV->hasMoreThanOneUniqueUser() ||
+    if (!WideIV || !WideIV->isCanonical() || !WideIV->hasNoOrOneUser() ||
         NewIVTy == WideIV->getScalarType())
       continue;
 
@@ -2611,7 +2609,7 @@ static void transformRecipestoEVLRecipes(VPlan &Plan, VPValue &EVL) {
     ToErase.push_back(CurRecipe);
   }
   // Remove dead EVL mask.
-  if (EVLMask->getNumUsers() == 0)
+  if (EVLMask->hasNoUsers())
     ToErase.push_back(EVLMask->getDefiningRecipe());
 
   for (VPRecipeBase *R : reverse(ToErase)) {
@@ -3590,7 +3588,7 @@ void VPlanTransforms::materializeBroadcasts(VPlan &Plan) {
 #endif
 
   SmallVector<VPValue *> VPValues;
-  if (Plan.getOrCreateBackedgeTakenCount()->getNumUsers() > 0)
+  if (Plan.getOrCreateBackedgeTakenCount()->hasUsers())
     VPValues.push_back(Plan.getOrCreateBackedgeTakenCount());
   append_range(VPValues, Plan.getLiveIns());
   for (VPRecipeBase &R : *Plan.getEntry())
@@ -3659,7 +3657,7 @@ void VPlanTransforms::materializeConstantVectorTripCount(
 void VPlanTransforms::materializeBackedgeTakenCount(VPlan &Plan,
                                                     VPBasicBlock *VectorPH) {
   VPValue *BTC = Plan.getOrCreateBackedgeTakenCount();
-  if (BTC->getNumUsers() == 0)
+  if (BTC->hasNoUsers())
     return;
 
   VPBuilder Builder(VectorPH, VectorPH->begin());
@@ -3725,7 +3723,7 @@ void VPlanTransforms::materializeVectorTripCount(VPlan &Plan,
   assert(VectorTC.isLiveIn() && "vector-trip-count must be a live-in");
   // There's nothing to do if there are no users of the vector trip count or its
   // IR value has already been set.
-  if (VectorTC.getNumUsers() == 0 || VectorTC.getLiveInIRValue())
+  if (VectorTC.hasNoUsers() || VectorTC.getLiveInIRValue())
     return;
 
   VPValue *TC = Plan.getTripCount();
@@ -3790,7 +3788,7 @@ void VPlanTransforms::materializeVFAndVFxUF(VPlan &Plan, VPBasicBlock *VectorPH,
 
   // If there are no users of the runtime VF, compute VFxUF by constant folding
   // the multiplication of VF and UF.
-  if (VF.getNumUsers() == 0) {
+  if (VF.hasNoUsers()) {
     VPValue *RuntimeVFxUF =
         Builder.createElementCount(TCTy, VFEC * Plan.getUF());
     VFxUF.replaceAllUsesWith(RuntimeVFxUF);

llvm/lib/Transforms/Vectorize/VPlanUnroll.cpp

@@ -535,7 +535,7 @@ void VPlanTransforms::replicateByVF(VPlan &Plan, ElementCount VF) {
         continue;
 
       VPBuilder Builder(RepR);
-      if (RepR->getNumUsers() == 0) {
+      if (RepR->hasNoUsers()) {
         if (isa<StoreInst>(RepR->getUnderlyingInstr()) &&
             vputils::isSingleScalar(RepR->getOperand(1))) {
           // Stores to invariant addresses need to store the last lane only.

llvm/lib/Transforms/Vectorize/VPlanValue.h

@@ -56,6 +56,8 @@ class LLVM_ABI_FOR_TEST VPValue {
 
   SmallVector<VPUser *, 1> Users;
 
+  unsigned getNumUsers() const { return Users.size(); }
+
 protected:
   // Hold the underlying Value, if any, attached to this VPValue.
   Value *UnderlyingVal;
@@ -110,7 +112,6 @@ class LLVM_ABI_FOR_TEST VPValue {
   void dump() const;
 #endif
 
-  unsigned getNumUsers() const { return Users.size(); }
   void addUser(VPUser &User) { Users.push_back(&User); }
 
   /// Remove a single \p User from the list of users.
@@ -136,17 +137,12 @@ class LLVM_ABI_FOR_TEST VPValue {
     return const_user_range(user_begin(), user_end());
   }
 
+  bool hasUsers() const { return !Users.empty(); }
+  bool hasNoUsers() const { return !hasUsers(); }
+  bool hasOneUser() const { return !hasNoUsers() && all_equal(Users); }
+
   /// Returns true if the value has more than one unique user.
-  bool hasMoreThanOneUniqueUser() const {
-    if (getNumUsers() == 0)
-      return false;
-
-    // Check if all users match the first user.
-    auto Current = std::next(user_begin());
-    while (Current != user_end() && *user_begin() == *Current)
-      Current++;
-    return Current != user_end();
-  }
+  bool hasNoOrOneUser() const { return hasNoUsers() || hasOneUser(); }
 
   void replaceAllUsesWith(VPValue *New);
 

llvm/lib/Transforms/Vectorize/VPlanVerifier.cpp

@@ -198,8 +198,8 @@ bool VPlanVerifier::verifyEVLRecipe(const VPInstruction &EVL) const {
           }
           // EVLIVIncrement is only used by EVLIV & BranchOnCount.
           // Having more than two users is unexpected.
-          if ((I->getNumUsers() != 1) &&
-              (I->getNumUsers() != 2 || none_of(I->users(), [&I](VPUser *U) {
+          if ((size(I->users()) != 1) &&
+              (size(I->users()) != 2 || none_of(I->users(), [&I](VPUser *U) {
                  using namespace llvm::VPlanPatternMatch;
                  return match(U, m_BranchOnCount(m_Specific(I), m_VPValue()));
                }))) {