Nashorn contains an undocumented --print-mem-usage option that allows to print the memory size of the IR after each compile step. This feature is broken in JDK9 because it requires deep reflection on all modules used in in the AST. There is no practical way to specify --add-opens options for all packages that may be used by the AST. Since the feature is not often used, hard to to test and maintain, and can possibly be replaced by other tools such as memory profilers, we think the right solution is to remove the feature from Nashorn code.