+/** The allowed parities */
+typedef enum {
+ oparity_invalid = 0,
+ oparity_unary, /**< an unary operator -- considering 'numeric' arguments. */
+ oparity_binary, /**< an binary operator -- considering 'numeric' arguments.*/
+ oparity_trinary, /**< an trinary operator -- considering 'numeric' arguments.*/
+ oparity_zero, /**< no operators, as e.g. Const. */
+ oparity_variable, /**< arity not fixed by opcode, but statically
+ known. E.g., number of arguments to call. */
+ oparity_dynamic, /**< arity depends on state of firm representation.
+ Can change by optimizations...
+ We must allocate a dynamic in array for the node! */
+ oparity_any, /**< other arity */
+} op_arity;
+
+
+/** The irop flags */
+typedef enum {
+ irop_flag_labeled = 0x00000001, /**< if set, Output edge labels on in-edges in vcg graph */
+ irop_flag_commutative = 0x00000002, /**< operation is commutative */
+ irop_flag_cfopcode = 0x00000004, /**< is a control flow operation */
+ irop_flag_ip_cfopcode = 0x00000008, /**< operation manipulates interprocedural control flow */
+ irop_flag_fragile = 0x00000010, /**< set if the operation can change the control flow because
+ of an exception */
+ irop_flag_forking = 0x00000020, /**< the operation is a forking control flow */
+} irop_flags;
+
+
+/**
+ * The compute value operation.
+ * This operation evaluates an IR node into a tarval if possible,
+ * returning tarval_bad otherwise.
+ */
+typedef tarval *(*computed_value_func)(ir_node *n);
+
+/**
+ * The equivalent node operation.
+ * This operation returns an equivalent node for the input node.
+ * 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., possible for Div).
+ */
+typedef ir_node *(*equivalent_node_func)(ir_node *n);
+
+/**
+ * The transform node operation.
+ * This operation tries several [inplace] [optimizing] transformations
+ * and returns an equivalent node.
+ * The difference to equivalent_node() is that these
+ * transformations _do_ generate new nodes, and thus the old node must
+ * not be freed even if the equivalent node isn't the old one.
+ */
+typedef ir_node *(*transform_node_func)(ir_node *n);
+
+/**
+ * The node attribute compare operation.
+ * Compares the nodes attributes of two nodes of identical opcode
+ * and returns 0 if the attributes are identical, 1 if they differ.
+ */
+typedef int (*node_cmp_attr_func)(ir_node *a, ir_node *b);
+
+/**
+ * The reassociation operation.
+ * Called from a walker. Returns non-zero if
+ * a reassociation rule was applied.
+ */
+typedef int (*reassociate_func)(ir_node *n);
+
+/**
+ * The copy attribute operation.
+ * Copy the node attributes from a 'old' node to a 'new' one.
+ */
+typedef void (*copy_attr_func)(const ir_node *old_node, ir_node *new_node);
+
+/** The type of an ir_op. */