159     if (uhp == curbuf->b_u_curhead && ++seen_b_u_curhead > 1)  in u_check_tree()
218     if (curbuf->b_u_curhead != NULL && seen_b_u_curhead == 0)  in u_check()
219 	semsg("b_u_curhead invalid: 0x%x", curbuf->b_u_curhead);  in u_check()
525 	old_curhead = curbuf->b_u_curhead;  in u_savecommon()
529 	    curbuf->b_u_curhead = NULL;  in u_savecommon()
1262     put_header_ptr(bi, buf->b_u_curhead);  in serialize_header()
2144     curbuf->b_u_curhead = cur_idx < 0 ? NULL : uhp_table[cur_idx];  in u_read_undo()
2258 	    if (curbuf->b_u_curhead == NULL)		// first undo  in u_doit()
2259 		curbuf->b_u_curhead = curbuf->b_u_newhead;  in u_doit()
2262 		curbuf->b_u_curhead = curbuf->b_u_curhead->uh_next.ptr;  in u_doit()
2264 	    if (curbuf->b_u_numhead == 0 || curbuf->b_u_curhead == NULL)  in u_doit()
2267 		curbuf->b_u_curhead = curbuf->b_u_oldhead;  in u_doit()
2281 	    if (curbuf->b_u_curhead == NULL || get_undolevel() <= 0)  in u_doit()
2296 	    if (curbuf->b_u_curhead->uh_prev.ptr == NULL)  in u_doit()
2297 		curbuf->b_u_newhead = curbuf->b_u_curhead;  in u_doit()
2298 	    curbuf->b_u_curhead = curbuf->b_u_curhead->uh_prev.ptr;  in u_doit()
2362 		uhp = curbuf->b_u_curhead;  in undo_time()
2439 	if (curbuf->b_u_curhead == NULL)	// at leaf of the tree  in undo_time()
2442 	    uhp = curbuf->b_u_curhead;  in undo_time()
2506 		if (uhp == curbuf->b_u_curhead)  in undo_time()
2559 	    uhp = curbuf->b_u_curhead;  in undo_time()
2567 	    curbuf->b_u_curhead = uhp;  in undo_time()
2584 		uhp = curbuf->b_u_curhead;  in undo_time()
2619 		curbuf->b_u_curhead = uhp;  in undo_time()
2638 		curbuf->b_u_curhead = uhp->uh_prev.ptr;  in undo_time()
2684     u_header_T	*curhead = curbuf->b_u_curhead;  in u_undoredo()
3005     if (curbuf->b_u_curhead != NULL)  in u_undo_end()
3008 	if (absolute && curbuf->b_u_curhead->uh_next.ptr != NULL)  in u_undo_end()
3010 	    uhp = curbuf->b_u_curhead->uh_next.ptr;  in u_undo_end()
3014 	    uhp = curbuf->b_u_curhead;  in u_undo_end()
3016 	    uhp = curbuf->b_u_curhead->uh_next.ptr;  in u_undo_end()
3065 	curbuf->b_u_curhead = NULL;  in u_sync()
3183     if (curbuf->b_u_curhead != NULL)  in ex_undojoin()
3219     if (curbuf->b_u_curhead != NULL || uhp == NULL)  in u_find_first_changed()
3259     uhp = buf->b_u_curhead;  in u_update_save_nr()
3417     if (buf->b_u_curhead == uhp)  in u_freeentries()
3418 	buf->b_u_curhead = NULL;  in u_freeentries()
3458     buf->b_u_newhead = buf->b_u_oldhead = buf->b_u_curhead = NULL;  in u_clearall()
3626 	if (uhp == curbuf->b_u_curhead)  in u_eval_tree()