[VPlan] Move usesScalars/onlyFirstLaneUsed to VPUser.

[fhahn]

Summary

Those helpers model properties of a user and they should also be
available to non-recipe users. This will be used in D123537 for a new
exit value user.

[fhahn]

Remove casts from VPUser -> VPRecipeBase before accessing usesScalars/onlyFirstLaneUsed.

[fhahn]

Ping :)

[Ayal]

Looks good! Minor documentation update nits.

llvm/lib/Transforms/Vectorize/VPlanValue.h

291

nit: "recipe" >> "VPUser"?

299

ditto

[fhahn]

Address comments & aebase before landing.

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

void VPWidenPointerInductionRecipe::execute(VPTransformState &State) {
   assert(IndDesc.getKind() == InductionDescriptor::IK_PtrInduction &&
          "Not a pointer induction according to InductionDescriptor!");
   assert(cast<PHINode>(getUnderlyingInstr())->getType()->isPointerTy() &&
          "Unexpected type.");
 
   auto *IVR = getParent()->getPlan()->getCanonicalIV();
   PHINode *CanonicalIV = cast<PHINode>(State.get(IVR, 0));
 
-  if (all_of(users(), [this](const VPUser *U) {
-        return cast<VPRecipeBase>(U)->usesScalars(this);
-      })) {
+  if (all_of(users(),
+             [this](const VPUser *U) { return U->usesScalars(this); })) {
     // This is the normalized GEP that starts counting at zero.
     Value *PtrInd = State.Builder.CreateSExtOrTrunc(
         CanonicalIV, IndDesc.getStep()->getType());
     // Determine the number of scalars we need to generate for each unroll
     // iteration. If the instruction is uniform, we only need to generate the
     // first lane. Otherwise, we generate all VF values.
     bool IsUniform = vputils::onlyFirstLaneUsed(this);
     assert((IsUniform || !State.VF.isScalable()) &&

llvm/lib/Transforms/Vectorize/VPlan.h

public:
 
   /// Returns true if the recipe may write to memory.
   bool mayWriteToMemory() const;
 
   /// Returns true if the recipe may read from or write to memory.
   bool mayReadOrWriteMemory() const {
     return mayReadFromMemory() || mayWriteToMemory();
   }
-
-  /// Returns true if the recipe only uses the first lane of operand \p Op.
-  /// Conservatively returns false.
-  virtual bool onlyFirstLaneUsed(const VPValue *Op) const {
-    assert(is_contained(operands(), Op) &&
-           "Op must be an operand of the recipe");
-    return false;
-  }
-
-  /// Returns true if the recipe uses scalars of operand \p Op. Conservatively
-  /// returns if only first (scalar) lane is used, as default.
-  virtual bool usesScalars(const VPValue *Op) const {
-    assert(is_contained(operands(), Op) &&
-           "Op must be an operand of the recipe");
-    return onlyFirstLaneUsed(Op);
-  }
 };
 
 inline bool VPUser::classof(const VPDef *Def) {
   return Def->getVPDefID() == VPRecipeBase::VPInstructionSC ||
          Def->getVPDefID() == VPRecipeBase::VPWidenSC ||
          Def->getVPDefID() == VPRecipeBase::VPWidenCallSC ||
          Def->getVPDefID() == VPRecipeBase::VPWidenSelectSC ||
          Def->getVPDefID() == VPRecipeBase::VPWidenGEPSC ||

 #endif
 
   /// Returns true if the recipe only uses the first lane of operand \p Op.
   bool onlyFirstLaneUsed(const VPValue *Op) const override {
     assert(is_contained(operands(), Op) &&
            "Op must be an operand of the recipe");
     // Recursing through Blend recipes only, must terminate at header phi's the
     // latest.
-    return all_of(users(), [this](VPUser *U) {
-      return cast<VPRecipeBase>(U)->onlyFirstLaneUsed(this);
-    });
+    return all_of(users(),
+                  [this](VPUser *U) { return U->onlyFirstLaneUsed(this); });
   }
 };
 
 /// VPInterleaveRecipe is a recipe for transforming an interleave group of load
 /// or stores into one wide load/store and shuffles. The first operand of a
 /// VPInterleave recipe is the address, followed by the stored values, followed
 /// by an optional mask.
 class VPInterleaveRecipe : public VPRecipeBase {

llvm/lib/Transforms/Vectorize/VPlan.cpp

if (isa<VPWidenPointerInductionRecipe>(&R) ||
       PHINode *Phi = nullptr;
       if (isa<VPWidenIntOrFpInductionRecipe>(&R)) {
         Phi = cast<PHINode>(State->get(R.getVPSingleValue(), 0));
       } else {
         auto *WidenPhi = cast<VPWidenPointerInductionRecipe>(&R);
         // TODO: Split off the case that all users of a pointer phi are scalar
         // from the VPWidenPointerInductionRecipe.
         if (all_of(WidenPhi->users(), [WidenPhi](const VPUser *U) {
-              return cast<VPRecipeBase>(U)->usesScalars(WidenPhi);
+              return U->usesScalars(WidenPhi);
             }))
           continue;
 
         auto *GEP = cast<GetElementPtrInst>(State->get(WidenPhi, 0));
         Phi = cast<PHINode>(GEP->getPointerOperand());
       }
 
       Phi->setIncomingBlock(1, VectorLatchBB);
void VPSlotTracker::assignSlots(const VPlan &Plan) {
   for (const VPBasicBlock *VPBB :
        VPBlockUtils::blocksOnly<const VPBasicBlock>(RPOT))
     for (const VPRecipeBase &Recipe : *VPBB)
       for (VPValue *Def : Recipe.definedValues())
         assignSlot(Def);
 }
 
 bool vputils::onlyFirstLaneUsed(VPValue *Def) {
-  return all_of(Def->users(), [Def](VPUser *U) {
-    return cast<VPRecipeBase>(U)->onlyFirstLaneUsed(Def);
-  });
+  return all_of(Def->users(),
+                [Def](VPUser *U) { return U->onlyFirstLaneUsed(Def); });
 }
 
 VPValue *vputils::getOrCreateVPValueForSCEVExpr(VPlan &Plan, const SCEV *Expr,
                                                 ScalarEvolution &SE) {
   if (auto *E = dyn_cast<SCEVConstant>(Expr))
     return Plan.getOrAddExternalDef(E->getValue());
   if (auto *E = dyn_cast<SCEVUnknown>(Expr))
     return Plan.getOrAddExternalDef(E->getValue());
 
   VPBasicBlock *Preheader = Plan.getEntry()->getEntryBasicBlock();
   VPValue *Step = new VPExpandSCEVRecipe(Expr, SE);
   Preheader->appendRecipe(cast<VPRecipeBase>(Step->getDef()));
   return Step;
 }

llvm/lib/Transforms/Vectorize/VPlanTransforms.cpp

if (!IV->needsVectorIV()) {
       IV->replaceAllUsesWith(Steps);
       continue;
     }
 
     // Otherwise only update scalar users of IV to use Step instead. Use
     // SetVector to ensure the list of users doesn't contain duplicates.
     SetVector<VPUser *> Users(IV->user_begin(), IV->user_end());
     for (VPUser *U : Users) {
-      VPRecipeBase *R = cast<VPRecipeBase>(U);
-      if (!R->usesScalars(IV))
+      if (!U->usesScalars(IV))
         continue;
-      for (unsigned I = 0, E = R->getNumOperands(); I != E; I++) {
-        if (R->getOperand(I) != IV)
+      for (unsigned I = 0, E = U->getNumOperands(); I != E; I++) {
+        if (U->getOperand(I) != IV)
           continue;
-        R->setOperand(I, Steps);
+        U->setOperand(I, Steps);
       }
     }
   }
 }
 
 void VPlanTransforms::removeRedundantExpandSCEVRecipes(VPlan &Plan) {
   DenseMap<const SCEV *, VPValue *> SCEV2VPV;
 

llvm/lib/Transforms/Vectorize/VPlanValue.h

public:
   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 VPDef *Recipe);
+
+  /// Returns true if the VPUser uses scalars of operand \p Op. Conservatively
+  /// returns if only first (scalar) lane is used, as default.
+  virtual bool usesScalars(const VPValue *Op) const {
+    assert(is_contained(operands(), Op) &&
+           "Op must be an operand of the recipe");
+    return onlyFirstLaneUsed(Op);
+  }
+
+  /// Returns true if the VPUser only uses the first lane of operand \p Op.
+  /// Conservatively returns false.
+  virtual bool onlyFirstLaneUsed(const VPValue *Op) const {
+    assert(is_contained(operands(), Op) &&
+           "Op must be an operand of the recipe");
+    return false;
+  }
 };
 
 /// This class augments a recipe with a set of VPValues defined by the recipe.
 /// It allows recipes to define zero, one or multiple VPValues. A VPDef owns
 /// the VPValues it defines and is responsible for deleting its defined values.
 /// Single-value VPDefs that also inherit from VPValue must make sure to inherit
 /// from VPDef before VPValue.
 class VPDef {