Automerge: [TTI] Remove Args argument from getOperandsScalarizationOverhead (NFC). (#154126)

Remove the ArrayRef<const Value*> Args operand from
getOperandsScalarizationOverhead and require that the callers
de-duplicate arguments and filter constant operands.

Removing the Value * based Args argument enables callers where no Value
* operands are available to use the function in a follow-up: computing
the scalarization cost directly for a VPlan recipe.

It also allows more accurate cost-estimates in the future: for example,
when vectorizing a loop, we could also skip operands that are live-ins,
as those also do not require scalarization.

PR: llvm/llvm-project#154126

Author: fhahn

llvm/include/llvm/Analysis/TargetTransformInfo.h

@@ -961,12 +961,10 @@ class TargetTransformInfo {
       TTI::TargetCostKind CostKind, bool ForPoisonSrc = true,
       ArrayRef<Value *> VL = {}) const;
 
-  /// Estimate the overhead of scalarizing an instructions unique
-  /// non-constant operands. The (potentially vector) types to use for each of
-  /// argument are passes via Tys.
+  /// Estimate the overhead of scalarizing operands with the given types. The
+  /// (potentially vector) types to use for each of argument are passes via Tys.
   LLVM_ABI InstructionCost getOperandsScalarizationOverhead(
-      ArrayRef<const Value *> Args, ArrayRef<Type *> Tys,
-      TTI::TargetCostKind CostKind) const;
+      ArrayRef<Type *> Tys, TTI::TargetCostKind CostKind) const;
 
   /// If target has efficient vector element load/store instructions, it can
   /// return true here so that insertion/extraction costs are not added to

llvm/include/llvm/Analysis/TargetTransformInfoImpl.h

@@ -459,8 +459,7 @@ class TargetTransformInfoImplBase {
   }
 
   virtual InstructionCost
-  getOperandsScalarizationOverhead(ArrayRef<const Value *> Args,
-                                   ArrayRef<Type *> Tys,
+  getOperandsScalarizationOverhead(ArrayRef<Type *> Tys,
                                    TTI::TargetCostKind CostKind) const {
     return 0;
   }

llvm/include/llvm/CodeGen/BasicTTIImpl.h

@@ -18,6 +18,7 @@
 
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/BitVector.h"
+#include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/Analysis/LoopInfo.h"
@@ -347,6 +348,21 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
     return Cost;
   }
 
+  /// Filter out constant and duplicated entries in \p Ops and return a vector
+  /// containing the types from \p Tys corresponding to the remaining operands.
+  static SmallVector<Type *, 4>
+  filterConstantAndDuplicatedOperands(ArrayRef<const Value *> Ops,
+                                      ArrayRef<Type *> Tys) {
+    SmallPtrSet<const Value *, 4> UniqueOperands;
+    SmallVector<Type *, 4> FilteredTys;
+    for (const auto &[Op, Ty] : zip_equal(Ops, Tys)) {
+      if (isa<Constant>(Op) || !UniqueOperands.insert(Op).second)
+        continue;
+      FilteredTys.push_back(Ty);
+    }
+    return FilteredTys;
+  }
+
 protected:
   explicit BasicTTIImplBase(const TargetMachine *TM, const DataLayout &DL)
       : BaseT(DL) {}
@@ -935,29 +951,21 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
                                              CostKind);
   }
 
-  /// Estimate the overhead of scalarizing an instructions unique
-  /// non-constant operands. The (potentially vector) types to use for each of
+  /// Estimate the overhead of scalarizing an instruction's
+  /// operands. The (potentially vector) types to use for each of
   /// argument are passes via Tys.
   InstructionCost getOperandsScalarizationOverhead(
-      ArrayRef<const Value *> Args, ArrayRef<Type *> Tys,
-      TTI::TargetCostKind CostKind) const override {
-    assert(Args.size() == Tys.size() && "Expected matching Args and Tys");
-
+      ArrayRef<Type *> Tys, TTI::TargetCostKind CostKind) const override {
     InstructionCost Cost = 0;
-    SmallPtrSet<const Value*, 4> UniqueOperands;
-    for (int I = 0, E = Args.size(); I != E; I++) {
+    for (Type *Ty : Tys) {
       // Disregard things like metadata arguments.
-      const Value *A = Args[I];
-      Type *Ty = Tys[I];
       if (!Ty->isIntOrIntVectorTy() && !Ty->isFPOrFPVectorTy() &&
           !Ty->isPtrOrPtrVectorTy())
         continue;
 
-      if (!isa<Constant>(A) && UniqueOperands.insert(A).second) {
-        if (auto *VecTy = dyn_cast<VectorType>(Ty))
-          Cost += getScalarizationOverhead(VecTy, /*Insert*/ false,
-                                           /*Extract*/ true, CostKind);
-      }
+      if (auto *VecTy = dyn_cast<VectorType>(Ty))
+        Cost += getScalarizationOverhead(VecTy, /*Insert*/ false,
+                                         /*Extract*/ true, CostKind);
     }
 
     return Cost;
@@ -974,7 +982,8 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
     InstructionCost Cost = getScalarizationOverhead(
         RetTy, /*Insert*/ true, /*Extract*/ false, CostKind);
     if (!Args.empty())
-      Cost += getOperandsScalarizationOverhead(Args, Tys, CostKind);
+      Cost += getOperandsScalarizationOverhead(
+          filterConstantAndDuplicatedOperands(Args, Tys), CostKind);
     else
       // When no information on arguments is provided, we add the cost
       // associated with one argument as a heuristic.
@@ -2170,8 +2179,9 @@ class BasicTTIImplBase : public TargetTransformInfoImplCRTPBase<T> {
               /*Insert=*/true, /*Extract=*/false, CostKind);
         }
       }
-      ScalarizationCost +=
-          getOperandsScalarizationOverhead(Args, ICA.getArgTypes(), CostKind);
+      ScalarizationCost += getOperandsScalarizationOverhead(
+          filterConstantAndDuplicatedOperands(Args, ICA.getArgTypes()),
+          CostKind);
     }
 
     IntrinsicCostAttributes Attrs(IID, RetTy, ICA.getArgTypes(), FMF, I,

llvm/lib/Analysis/TargetTransformInfo.cpp

@@ -637,9 +637,8 @@ InstructionCost TargetTransformInfo::getScalarizationOverhead(
 }
 
 InstructionCost TargetTransformInfo::getOperandsScalarizationOverhead(
-    ArrayRef<const Value *> Args, ArrayRef<Type *> Tys,
-    TTI::TargetCostKind CostKind) const {
-  return TTIImpl->getOperandsScalarizationOverhead(Args, Tys, CostKind);
+    ArrayRef<Type *> Tys, TTI::TargetCostKind CostKind) const {
+  return TTIImpl->getOperandsScalarizationOverhead(Tys, CostKind);
 }
 
 bool TargetTransformInfo::supportsEfficientVectorElementLoadStore() const {

llvm/lib/Transforms/Vectorize/LoopVectorize.cpp

@@ -1697,8 +1697,16 @@ class LoopVectorizationCostModel {
   /// Returns a range containing only operands needing to be extracted.
   SmallVector<Value *, 4> filterExtractingOperands(Instruction::op_range Ops,
                                                    ElementCount VF) const {
-    return SmallVector<Value *, 4>(make_filter_range(
-        Ops, [this, VF](Value *V) { return this->needsExtract(V, VF); }));
+
+    SmallPtrSet<const Value *, 4> UniqueOperands;
+    SmallVector<Value *, 4> Res;
+    for (Value *Op : Ops) {
+      if (isa<Constant>(Op) || !UniqueOperands.insert(Op).second ||
+          !needsExtract(Op, VF))
+        continue;
+      Res.push_back(Op);
+    }
+    return Res;
   }
 
 public:
@@ -5610,8 +5618,7 @@ LoopVectorizationCostModel::getScalarizationOverhead(Instruction *I,
   SmallVector<Type *> Tys;
   for (auto *V : filterExtractingOperands(Ops, VF))
     Tys.push_back(maybeVectorizeType(V->getType(), VF));
-  return Cost + TTI.getOperandsScalarizationOverhead(
-                    filterExtractingOperands(Ops, VF), Tys, CostKind);
+  return Cost + TTI.getOperandsScalarizationOverhead(Tys, CostKind);
 }
 
 void LoopVectorizationCostModel::setCostBasedWideningDecision(ElementCount VF) {