1 files changed, 15 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp b/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp
index 9c4b49aa7c3..24aa1abffa5 100644
--- a/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp
+++ b/llvm/lib/CodeGen/BasicTargetTransformInfo.cpp
@@ -113,6 +113,7 @@ public:
                                          ArrayRef<Type*> Tys) const;
   virtual unsigned getNumberOfParts(Type *Tp) const;
   virtual unsigned getAddressComputationCost(Type *Ty, bool IsComplex) const;
+  virtual unsigned getReductionCost(unsigned Opcode, Type *Ty, bool IsPairwise) const;
 
   /// @}
 };
@@ -510,3 +511,17 @@ unsigned BasicTTI::getNumberOfParts(Type *Tp) const {
 unsigned BasicTTI::getAddressComputationCost(Type *Ty, bool IsComplex) const {
   return 0;
 }
+
+unsigned BasicTTI::getReductionCost(unsigned Opcode, Type *Ty,
+                                    bool IsPairwise) const {
+  assert(Ty->isVectorTy() && "Expect a vector type");
+  unsigned NumVecElts = Ty->getVectorNumElements();
+  unsigned NumReduxLevels = Log2_32(NumVecElts);
+  unsigned ArithCost = NumReduxLevels *
+    TopTTI->getArithmeticInstrCost(Opcode, Ty);
+  // Assume the pairwise shuffles add a cost.
+  unsigned ShuffleCost =
+      NumReduxLevels * (IsPairwise + 1) *
+      TopTTI->getShuffleCost(SK_ExtractSubvector, Ty, NumVecElts / 2, Ty);
+  return ShuffleCost + ArithCost + getScalarizationOverhead(Ty, false, true);
+}