According to Nick Burrett:
I have been experimenting over the past couple of weeks. Since gpc is based on the gcc 2.8.0 work, it is not compatible with egcs. Several weeks ago bytecode support was removed from egcs so a series of patches would be required that removed bytecode support from gpc.
The GPC frontend has not much to do with bytecode support. If the interface between the frontend and the backend did not change, GPC will not even notice that difference.
Greetings,
Peter