+/** Analyses a rough estimation of the possible call graph.
+ *
+ * Determines for each Call node the set of possibly called methods.
+ * Stores the result in the field 'callees' of the Call node. If the
+ * address can not be analysed, e.g. because it is loaded from a
+ * variable, the array contains the unknown_entity. (See
+ * "set_Call_callee"). cgana returns the set of 'free' methods, i.e.,
+ * the methods that can be called from external or via function
+ * pointers. This datastructure must be freed with 'free()' by the
+ * caller of cgana.
+ *
+ * cgana sets the callee_info_state of each graph and the program to
+ * consistent.
+ *
+ * The algorithm implements roughly Static Class Hierarchy Analysis
+ * as described in "Optimization of Object-Oriented Programs Using
+ * Static Class Hierarchy Analysis" by Jeffrey Dean and David Grove
+ * and Craig Chambers.
+ *
+ * Performs some optimizations possible by the analysed information:
+ * - Replace SymConst-name nodes by SymConst-entity nodes if possible.
+ * - Replace (Sel-method(Alloc)) by SymConst-entity.
+ * - Replaces Sel nodes by Bad if there is no implementation for the
+ * selected entity.
+ * - Replaces Sel-method by SymConst-entity if the method is never overwritten.
+ * - Replaces Calls by Tuple containing Bads if callee array is empty
+ * (there is no implementation to call)
+ *
+ * Leaves Bad control predecessors in the graph!
+ */
+void cgana(int *len, ir_entity ***free_methods);