TargetInstrInfo: add virtual function getInstSizeInBytes

This adds a target hook getInstSizeInBytes to TargetInstrInfo that a lot of
subclasses already implement.

Differential Revision: https://reviews.llvm.org/D22885

llvm-svn: 277126
diff --git a/llvm/lib/Target/AVR/AVRInstrInfo.h b/llvm/lib/Target/AVR/AVRInstrInfo.h
index b8d946f..2bcbe01 100644
--- a/llvm/lib/Target/AVR/AVRInstrInfo.h
+++ b/llvm/lib/Target/AVR/AVRInstrInfo.h
@@ -70,7 +70,7 @@
   const MCInstrDesc &getBrCond(AVRCC::CondCodes CC) const;
   AVRCC::CondCodes getCondFromBranchOpc(unsigned Opc) const;
   AVRCC::CondCodes getOppositeCondition(AVRCC::CondCodes CC) const;
-  unsigned getInstSizeInBytes(const MachineInstr *MI) const;
+  unsigned getInstSizeInBytes(const MachineInstr *MI) const override;
 
   void copyPhysReg(MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
                    const DebugLoc &DL, unsigned DestReg, unsigned SrcReg,