How to make use of the Debug variable (public static boolean DEBUG = false)??

[sashankh]

Hi
I am a newbie to JikesRVM. I am going through the jikes code base and I come across this DEBUG variable which is checked while to display some additional information... How can I make use of this DEBUG variable.
Also I want to use the command line options to print the produced IR till a certain stage, I am using the command
 rvm -X:opt:<print_all_IR>=true classname
which will not work. It gives the error message as print_all_ir: no such file or directory.
Please help me on this.. Any suggestions are welcome.