[AMDGPU] Initialize instruction itinerary from GCNSubtarget

[rampitec]

Summary

I need to use it in the GCN codegen.

[kzhuravl]

LGTM

llvm/trunk/lib/Target/AMDGPU/AMDGPUSubtarget.h

private:
   std::unique_ptr<LegalizerInfo> Legalizer;
   std::unique_ptr<RegisterBankInfo> RegBankInfo;
 
 protected:
   // Basic subtarget description.
   Triple TargetTriple;
   unsigned Gen;
   unsigned IsaVersion;
+  InstrItineraryData InstrItins;
   int LDSBankCount;
   unsigned MaxPrivateElementSize;
 
   // Possibly statically set by tablegen, but may want to be overridden.
   bool FastFMAF32;
   bool HalfRate64Ops;
 
   // Dynamially set bits that enable features.
const RegisterBankInfo *getRegBankInfo() const override {
     return RegBankInfo.get();
   }
 
   // Nothing implemented, just prevent crashes on use.
   const SelectionDAGTargetInfo *getSelectionDAGInfo() const override {
     return &TSInfo;
   }
 
+  const InstrItineraryData *getInstrItineraryData() const override {
+    return &InstrItins;
+  }
+
   void ParseSubtargetFeatures(StringRef CPU, StringRef FS);
 
   Generation getGeneration() const {
     return (Generation)Gen;
   }
 
   unsigned getWavefrontSizeLog2() const {
     return Log2_32(WavefrontSize);

llvm/trunk/lib/Target/AMDGPU/AMDGPUSubtarget.cpp

 
 GCNSubtarget::GCNSubtarget(const Triple &TT, StringRef GPU, StringRef FS,
                            const GCNTargetMachine &TM) :
     AMDGPUGenSubtargetInfo(TT, GPU, FS),
     AMDGPUSubtarget(TT),
     TargetTriple(TT),
     Gen(SOUTHERN_ISLANDS),
     IsaVersion(ISAVersion0_0_0),
+    InstrItins(getInstrItineraryForCPU(GPU)),
     LDSBankCount(0),
     MaxPrivateElementSize(0),
 
     FastFMAF32(false),
     HalfRate64Ops(false),
 
     FP64FP16Denormals(false),
     DX10Clamp(false),