ARM cost model: Add costs for vector selects

Vector selects are cheap on NEON. They get lowered to a vbsl instruction.

radar://13158753

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@174631 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 15 insertions, 0 deletions

diff --git a/lib/Target/ARM/ARMTargetTransformInfo.cpp b/lib/Target/ARM/ARMTargetTransformInfo.cpp
index bf83d51..1f91e0e 100644
--- a/lib/Target/ARM/ARMTargetTransformInfo.cpp
+++ b/lib/Target/ARM/ARMTargetTransformInfo.cpp
@@ -117,6 +117,8 @@ public:
   unsigned getCastInstrCost(unsigned Opcode, Type *Dst,
                                       Type *Src) const;
 
+  unsigned getCmpSelInstrCost(unsigned Opcode, Type *ValTy, Type *CondTy) const;
+
   unsigned getVectorInstrCost(unsigned Opcode, Type *Val, unsigned Index) const;
   /// @}
 };
@@ -311,3 +313,16 @@ unsigned ARMTTI::getVectorInstrCost(unsigned Opcode, Type *ValTy,
 
   return TargetTransformInfo::getVectorInstrCost(Opcode, ValTy, Index);
 }
+
+unsigned ARMTTI::getCmpSelInstrCost(unsigned Opcode, Type *ValTy,
+                                    Type *CondTy) const {
+
+  int ISD = TLI->InstructionOpcodeToISD(Opcode);
+  // On NEON a a vector select gets lowered to vbsl.
+  if (ST->hasNEON() && ValTy->isVectorTy() && ISD == ISD::SELECT) {
+    std::pair<unsigned, MVT> LT = TLI->getTypeLegalizationCost(ValTy);
+    return LT.first;
+  }
+
+  return TargetTransformInfo::getCmpSelInstrCost(Opcode, ValTy, CondTy);
+}