A better way to silence the warning in MSVC (replaces r190304).

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@190308 91177308-0d34-0410-b5e6-96231b3b80d8

lib/Target/XCore/XCoreLowerThreadLocal.cpp

@@ -120,9 +120,8 @@ createReplacementInstr(ConstantExpr *CE, Instruction *Instr) {
                                      CE->getOperand(0), CE->getType(),
                                      CE->getName()));
     default:
-      assert(0 && "Unhandled constant expression!\n");
+      llvm_unreachable("Unhandled constant expression!\n");
   }
-  llvm_unreachable("Unhandled constant expression!\n");
 }
 
 static bool replaceConstantExprOp(ConstantExpr *CE) {