Add an unreachable to silence warning - the switch is actually

fully enumerated.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@117647 91177308-0d34-0410-b5e6-96231b3b80d8

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!");
 }