2 files changed, 46 insertions, 2 deletions

diff --git a/llvm/lib/Target/ARM/ARMTargetMachine.h b/llvm/lib/Target/ARM/ARMTargetMachine.h
index be6bec75928..d4caf5ca6e1 100644
--- a/llvm/lib/Target/ARM/ARMTargetMachine.h
+++ b/llvm/lib/Target/ARM/ARMTargetMachine.h
@@ -46,6 +46,10 @@ public:
 
   virtual       ARMJITInfo       *getJITInfo()         { return &JITInfo; }
   virtual const ARMSubtarget  *getSubtargetImpl() const { return &Subtarget; }
+  virtual const ARMTargetLowering *getTargetLowering() const {
+    // Implemented by derived classes
+    llvm_unreachable("getTargetLowering not implemented");
+  }
   virtual const InstrItineraryData *getInstrItineraryData() const {
     return &InstrItins;
   }
diff --git a/llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp b/llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
index 404a6fff117..61cb1f6b9a3 100644
--- a/llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
+++ b/llvm/lib/Target/ARM/ARMTargetTransformInfo.cpp
@@ -20,6 +20,7 @@
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Target/TargetLowering.h"
+#include "llvm/Target/CostTable.h"
 using namespace llvm;
 
 // Declare the pass initialization routine locally as target-specific passes
@@ -34,18 +35,20 @@ namespace {
 class ARMTTI : public ImmutablePass, public TargetTransformInfo {
   const ARMBaseTargetMachine *TM;
   const ARMSubtarget *ST;
+  const ARMTargetLowering *TLI;
 
   /// Estimate the overhead of scalarizing an instruction. Insert and Extract
   /// are set if the result needs to be inserted and/or extracted from vectors.
   unsigned getScalarizationOverhead(Type *Ty, bool Insert, bool Extract) const;
 
 public:
-  ARMTTI() : ImmutablePass(ID), TM(0), ST(0) {
+  ARMTTI() : ImmutablePass(ID), TM(0), ST(0), TLI(0) {
     llvm_unreachable("This pass cannot be directly constructed");
   }
 
   ARMTTI(const ARMBaseTargetMachine *TM)
-      : ImmutablePass(ID), TM(TM), ST(TM->getSubtargetImpl()) {
+      : ImmutablePass(ID), TM(TM), ST(TM->getSubtargetImpl()),
+        TLI(TM->getTargetLowering()) {
     initializeARMTTIPass(*PassRegistry::getPassRegistry());
   }
 
@@ -111,6 +114,9 @@ public:
     return 1;
   }
 
+  unsigned getCastInstrCost(unsigned Opcode, Type *Dst,
+                                      Type *Src) const;
+
   /// @}
 };
 
@@ -157,3 +163,37 @@ unsigned ARMTTI::getIntImmCost(const APInt &Imm, Type *Ty) const {
   }
   return 2;
 }
+
+unsigned ARMTTI::getCastInstrCost(unsigned Opcode, Type *Dst,
+                                    Type *Src) const {
+  int ISD = TLI->InstructionOpcodeToISD(Opcode);
+  assert(ISD && "Invalid opcode");
+
+  EVT SrcTy = TLI->getValueType(Src);
+  EVT DstTy = TLI->getValueType(Dst);
+
+  if (!SrcTy.isSimple() || !DstTy.isSimple())
+    return TargetTransformInfo::getCastInstrCost(Opcode, Dst, Src);
+
+  // Some arithmetic, load and store operations have specific instructions
+  // to cast up/down their types automatically at no extra cost
+  // TODO: Get these tables to know at least what the related operations are
+  static const TypeConversionCostTblEntry<MVT> NEONConversionTbl[] = {
+    { ISD::SIGN_EXTEND, MVT::v4i32, MVT::v4i16, 0 },
+    { ISD::ZERO_EXTEND, MVT::v4i32, MVT::v4i16, 0 },
+    { ISD::SIGN_EXTEND, MVT::v2i64, MVT::v2i32, 1 },
+    { ISD::ZERO_EXTEND, MVT::v2i64, MVT::v2i32, 1 },
+    { ISD::TRUNCATE,    MVT::v4i32, MVT::v4i64, 0 },
+    { ISD::TRUNCATE,    MVT::v4i16, MVT::v4i32, 1 },
+  };
+
+  if (ST->hasNEON()) {
+    int Idx = ConvertCostTableLookup<MVT>(NEONConversionTbl,
+                                array_lengthof(NEONConversionTbl),
+                                ISD, DstTy.getSimpleVT(), SrcTy.getSimpleVT());
+    if (Idx != -1)
+      return NEONConversionTbl[Idx].Cost;
+  }
+
+  return TargetTransformInfo::getCastInstrCost(Opcode, Dst, Src);
+}