+typedef struct _arch_register_req_t {
+ arch_register_req_type_t type; /**< The type of the constraint. */
+ const arch_register_class_t *cls; /**< The register class this constraint belongs to. */
+
+ void (*limited)(void *limited_env, bitset_t *bs);
+ /**< In case of the 'limited'
+ constraint, this function
+ must put all allowable
+ registers in the bitset and
+ return the number of registers
+ in the bitset. */
+
+ void *limited_env; /**< This is passed to limited. */
+
+ ir_node *other; /**< In case of "should be equal"
+ or should be different, this gives
+ the node to whose register this
+ one's should be the same/different. */
+} arch_register_req_t;
+
+/**
+ * Certain node classes which are relevant for the register allocator.
+ */
+typedef enum _arch_irn_class_t {
+ arch_irn_class_normal,
+ arch_irn_class_spill,
+ arch_irn_class_reload,
+ arch_irn_class_copy,
+ arch_irn_class_perm,
+ arch_irn_class_branch,
+ arch_irn_class_call
+} arch_irn_class_t;
+
+/**
+ * Some flags describing a node in more detail.
+ */
+typedef enum _arch_irn_flags_t {
+ arch_irn_flags_dont_spill = 1, /**< This must not be spilled. */
+ arch_irn_flags_rematerializable = 2, /**< This should be replicated instead of spilled/reloaded. */
+ arch_irn_flags_ignore = 4, /**< Do not consider the node during register allocation. */
+} arch_irn_flags_t;
+
+struct _arch_irn_ops_if_t {
+
+ /**
+ * Get the register requirements for a given operand.
+ * @param self The self pointer.
+ * @param irn The node.
+ * @param pos The operand's position
+ * (-1 for the result of the node, 0..n for the input
+ * operands).
+ * @return The register requirements for the selected operand.
+ * The pointer returned is never NULL.
+ */
+ const arch_register_req_t *(*get_irn_reg_req)(const void *self,
+ arch_register_req_t *req, const ir_node *irn, int pos);
+
+ /**
+ * Set the register for an output operand.
+ * @param irn The node.
+ * @param reg The register allocated to that operand.
+ * @note If the operand is not a register operand,
+ * the call is ignored.
+ */
+ void (*set_irn_reg)(const void *self, ir_node *irn, const arch_register_t *reg);
+
+ /**
+ * Get the register allocated for an output operand.
+ * @param irn The node.
+ * @return The register allocated at that operand. NULL, if
+ * the operand was no register operand or
+ * @c arch_register_invalid, if no register has yet been
+ * allocated for this node.
+ */
+ const arch_register_t *(*get_irn_reg)(const void *self, const ir_node *irn);
+
+ /**
+ * Classify the node.
+ * @param irn The node.
+ * @return A classification.
+ */
+ arch_irn_class_t (*classify)(const void *self, const ir_node *irn);
+
+ /**
+ * Get the flags of a node.
+ * @param self The irn ops themselves.
+ * @param irn The node.
+ * @return A set of flags.
+ */
+ arch_irn_flags_t (*get_flags)(const void *self, const ir_node *irn);
+