Add an unreachable to silence warning - the switch is actually

fully enumerated.

llvm-svn: 117647

llvm/lib/Target/ARM/AsmParser/ARMAsmParser.cpp

@@ -797,6 +797,8 @@ MatchAndEmitInstruction(SMLoc IDLoc,
   case Match_MnemonicFail:
     return Error(IDLoc, "unrecognized instruction mnemonic");
   }
+  
+  llvm_unreachable("Implement any new match types added!");
 }