+unsigned ir_node_hash(const ir_node *node);
+
+/**
+ * equivalent_node() returns a node equivalent to input n. It skips all nodes that
+ * perform no actual computation, as, e.g., the Id nodes. It does not create
+ * new nodes. It is therefore safe to free n if the node returned is not n.
+ * If a node returns a Tuple we can not just skip it. If the size of the
+ * in array fits, we transform n into a tuple (e.g., Div).
+ */
+ir_node *equivalent_node(ir_node *n);