expose DWARF_LABEL opcode# so the branch folder can update debug info properly.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@31024 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Target/TargetInstrInfo.h

@@ -219,6 +219,13 @@ public:
     return get(Opcode).Flags & M_VARIABLE_OPS;
   }
 
+  /// getDWARF_LABELOpcode - Return the opcode of the target's DWARF_LABEL
+  /// instruction if it has one.  This is used by codegen passes that update
+  /// DWARF line number info as they modify the code.
+  virtual unsigned getDWARF_LABELOpcode() const {
+    return 0;
+  }
+  
   /// Return true if the instruction is a register to register move
   /// and leave the source and dest operands in the passed parameters.
   virtual bool isMoveInstr(const MachineInstr& MI,