+/** Returns the number of elements contained in loop. */
+int get_loop_n_elements (ir_loop *loop);
+/** Returns a loop element. A loop element can be interpreted as a
+ kind pointer, an ir_node* or an ir_loop*. */
+loop_element get_loop_element (ir_loop *loop, int pos);
+
+/** Returns the element number of the loop son in loop.
+ * Returns -1 if not found. O(|elements|). */
+int get_loop_element_pos(ir_loop *loop, void *le);
+
+/** Returns a unique node number for the loop node to make output
+ readable. If libfirm_debug is not set it returns the loop cast to
+ int. */
+int get_loop_loop_nr(ir_loop *loop);
+
+/** A field to connect additional information to a loop. Only valid
+ if libfirm_debug is set, else returns NULL. */
+void set_loop_link (ir_loop *loop, void *link);
+void *get_loop_link (const ir_loop *loop);
+
+/* ------------------------------------------------------------------- */
+/* Constructing and destructing the loop/backedge information. */
+/* ------------------------------------------------------------------- */
+
+/** Constructs backedge information and loop tree for a graph in intraprocedural view.
+ *
+ * The algorithm views the program representation as a pure graph.
+ * It assumes that only block and phi nodes may be loop headers.
+ * The resulting loop tree is a possible visiting order for dataflow
+ * analysis.
+ *
+ * @returns Maximal depth of loop tree.
+ *
+ * @remark
+ * One assumes, the Phi nodes in a block with a backedge have backedges
+ * at the same positions as the block. This is not the case, as
+ * the scc algorithms does not respect the program semantics in this case.
+ * Take a swap in a loop (t = i; i = j; j = t;) This results in two Phi
+ * nodes. They form a cycle. Once the scc algorithm deleted one of the
+ * edges, the cycle is removed. The second Phi node does not get a
+ * backedge!
+ */
+/* @@@ Well, maybe construct_loop_information or analyze_loops ? */
+int construct_backedges(ir_graph *irg);
+
+/** Constructs backedges for all irgs in interprocedural view.
+ *
+ * @see As construct_backedges(), but for interprocedural view.
+ *
+ * @remark
+ * All loops in the graph will be marked as such, not only
+ * realizeable loops and recursions in the program. E.g., if the
+ * same funcion is called twice, there is a loop between the first
+ * function return and the second call.
+ *
+ * @returns Maximal depth of loop tree.
+*/
+int construct_ip_backedges(void);
+
+/** Construct loop tree only for control flow.
+ *
+ * This constructs loop information resembling the program structure.
+ * It is useful for loop optimizations and analyses, as, e.g., finding
+ * iteration variables or loop invariant code motion.
+ *
+ * This algorithm computes only back edge information for Block nodes, not
+ * for Phi nodes.
+ *
+ * @returns Maximal depth of loop tree. */
+int construct_cf_backedges(ir_graph *irg);
+
+/** Construct interprocedural loop tree for control flow.
+ *
+ * @see construct_cf_backedges() and construct_ip_backedges().
+ */
+int construct_ip_cf_backedges (void);
+
+/** Removes all loop information.
+ * Resets all backedges. Works for any construction algorithm.
+ */
+void free_loop_information(ir_graph *irg);
+void free_all_loop_information (void);
+
+
+
+
+/* ------------------------------------------------------------------- */
+/* Simple analyses based on the loop information */
+/* ------------------------------------------------------------------- */
+
+/** Test whether a value is loop invariant.
+ *
+ * @param n The node to be tested.
+ * @param block A block node.
+ *
+ * Returns non-zero, if the node n is not changed in the loop block
+ * belongs to or in inner loops of this block. */
+int is_loop_invariant(ir_node *n, ir_node *block);