res->attr.block.backedge = new_backedge_arr(irg->obst, arity);
res->attr.block.in_cg = NULL;
res->attr.block.cg_backedge = NULL;
res->attr.block.backedge = new_backedge_arr(irg->obst, arity);
res->attr.block.in_cg = NULL;
res->attr.block.cg_backedge = NULL;