extern void df_mark_solutions_dirty (void);
extern bool df_get_bb_dirty (basic_block);
extern void df_set_bb_dirty (basic_block);
-extern void df_set_bb_dirty_nonlr (basic_block);
extern void df_compact_blocks (void);
extern void df_bb_replace (int, basic_block);
extern void df_bb_delete (int);