-/** Constructs backedge information for irg in intraprocedural view.
- * @returns Maximal depth of loop tree. */
+/** 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.
+ *
+ * This algorithm destoyes the link field of block nodes.
+ *
+ * @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!
+ */