+/**
+ * The type of the debug info merge function.
+ *
+ * @param new_node the new ir node
+ * @param old_node the old ir node
+ * @param action the action that triggers the merge
+ *
+ * @see dbg_init()
+ */
+typedef void merge_pair_func(ir_node *new_node, ir_node *old_node, dbg_action action);
+
+/**
+ * The type of the debug info merge sets function.
+ *
+ * @param new_node_array array of new nodes
+ * @param new_num_entries number of entries in new_node_array
+ * @param old_node_array array of old nodes
+ * @param old_num_entries number of entries in old_node_array
+ * @param action the action that triggers the merge
+ *
+ * @see dbg_init()
+ */
+typedef void merge_sets_func(ir_node **new_node_array, int new_num_entries, ir_node **old_node_array, int old_num_entries, dbg_action action);
+
+/**
+ * The type of the debug info to human readable string function.
+ *
+ * @param buf pointer to a buffer that will hold the info
+ * @param len length of the buffer
+ * @param dbg the debug info
+ *
+ * @return Number of written characters to the buffer.
+ *
+ * @see dbg_init()
+ */
+typedef unsigned snprint_dbg_func(char *buf, unsigned len, const dbg_info *dbg);
+
+/**
+ * Initializes the debug support.
+ *
+ * @param dbg_info_merge_pair see function description
+ * @param dbg_info_merge_sets see function description
+ * @param snprint_dbg see function description
+ *
+ * This function takes Pointers to two functions that merge the
+ * debug information when a
+ * transformation of a firm graph is performed.
+ * Firm transformations call one of these functions.
+ *
+ * - dbg_info_merge_pair() is called in the following situation:
+ * The optimization replaced the old node by the new one. The new node
+ * might be a recent allocated node not containing any debug information,
+ * or just another node from somewhere in the graph with the same
+ * semantics.
+ * - dbg_info_merge_sets() is called in the following situation:
+ * The optimization replaced a subgraph by another subgraph. There is no
+ * obviously mapping between single nodes in both subgraphs. The optimization
+ * simply passes two lists to the debug module, one containing the nodes in
+ * the old subgraph, the other containing the nodes in the new subgraph.
+ * The same node can be in both lists.
+ *
+ * Further both functions pass an enumeration indicating the action
+ * performed by the transformation, e.g. the kind of optimization performed.
+ *
+ * The third argument snprint_dbg is called to convert a debug info into a human readable string.
+ * This string is the dumped in the dumper functions.
+ *
+ * Note that if NULL is passed for dbg_info_merge_pair or dbg_info_merge_sets, the default
+ * implementations default_dbg_info_merge_pair() and default_dbg_info_merge_sets() are used.
+ * NULL passed for snprint_dbg means no output.
+ */
+void dbg_init(merge_pair_func *dbg_info_merge_pair, merge_sets_func *dbg_info_merge_sets, snprint_dbg_func *snprint_dbg);
+
+/** @} */
+
+/**
+ * The default merge_pair_func implementation, simply copies the debug info
+ * from old to new.
+ */
+void default_dbg_info_merge_pair(ir_node *nw, ir_node *old, dbg_action info);
+
+/**
+ * The default merge_sets_func implementation, does nothing
+ */
+void default_dbg_info_merge_sets(ir_node **new_nodes, int n_new_nodes,
+ ir_node **old_nodes, int n_old_nodes,
+ dbg_action info);
+
+#ifdef __cplusplus
+}
+#endif