+static void add_edge(ir_node *src, int pos, ir_node *tgt, ir_edge_kind_t kind,
+ ir_graph *irg)
+{
+ assert(edges_activated_kind(irg, kind));
+ irg_edge_info_t *info = get_irg_edge_info(irg, kind);
+ ir_edgeset_t *edges = &info->edges;
+
+ struct list_head *head = &get_irn_edge_info(tgt, kind)->outs_head;
+ assert(head->next && head->prev &&
+ "target list head must have been initialized");
+
+ /* The old target was NULL, thus, the edge is newly created. */
+ ir_edge_t *edge;
+ if (list_empty(&info->free_edges)) {
+ edge = OALLOC(&info->edges_obst, ir_edge_t);
+ } else {
+ edge = list_entry(info->free_edges.next, ir_edge_t, list);
+ list_del(&edge->list);
+ }
+
+ edge->src = src;
+ edge->pos = pos;
+#ifdef DEBUG_libfirm
+ edge->present = 0;
+#endif
+
+ ir_edge_t *new_edge = ir_edgeset_insert(edges, edge);
+ assert(new_edge == edge);
+ (void)new_edge;
+
+ list_add(&edge->list, head);
+
+ edge_change_cnt(tgt, kind, +1);
+}
+
+static void delete_edge(ir_node *src, int pos, ir_node *old_tgt,
+ ir_edge_kind_t kind, ir_graph *irg)
+{
+ assert(edges_activated_kind(irg, kind));
+
+ irg_edge_info_t *info = get_irg_edge_info(irg, kind);
+ ir_edgeset_t *edges = &info->edges;
+
+ /* Initialize the edge template to search in the set. */
+ ir_edge_t templ;
+ templ.src = src;
+ templ.pos = pos;
+
+ /* search the edge in the set. */
+ ir_edge_t *edge = ir_edgeset_find(edges, &templ);
+
+ /* mark the edge invalid if it was found */
+ if (edge == NULL)
+ return;
+
+ list_del(&edge->list);
+ ir_edgeset_remove(edges, edge);
+ list_add(&edge->list, &info->free_edges);
+ edge->pos = -2;
+ edge->src = NULL;
+ edge_change_cnt(old_tgt, kind, -1);
+}
+