https://gcc.gnu.org/bugzilla/show_bug.cgi?id=88856
--- Comment #10 from Jakub Jelinek <jakub at gcc dot gnu.org> --- I admit I have just a vague recollection of this, but I thought since df has been added, usually if a pass wants REG_DEAD notes, it needs to df_note_add_problem () and df_analyze should rebuild the REG_DEAD/REG_UNUSED notes.
