The issue is that someone has to initially write the code to emit the native assembly/machine code for each architecture that a given compiler supports. (i.e. a

The issue is that someone has to initially write the code to emit the native assembly/machine code for each architecture that a given compiler supports. (i.e. assuming it actually emits native code and not code for another compiled language like C/C++) The flag simply means that someone has already done that work for a particular language on a particular architecture.