opt -p flag

I wanted to see where some transforms were happening in the standard
compilation passes, so I tried using "-p" flag to opt along with
"-std-compile-opts" but it didn't work, as the print pass doesn't get
added for the passes from std-compile-opts.

Is it expected/intended that -p only works with user supplied pass
arguments? If so, the docs for opt should probably state that.

You can use -debug-pass=Executions to see what passes are being executed.

I am not sure why -p doesn't do anything. Please file a bug. Thanks.