+/**
+ * Get the register requirements for a node.
+ * @param env The architecture environment.
+ * @param req A pointer to a requirements structure, where the data can
+ * be put into.
+ * @param irn The node.
+ * @param pos The position of the operand you're interested in.
+ * @return A pointer to the register requirements which may <b>not</b>
+ * neccessarily be equal to @p req. If NULL is returned, the
+ * operand was no register operand.
+ */
+extern const arch_register_req_t *
+arch_get_register_req(const arch_env_t *env, arch_register_req_t *req,
+ const ir_node *irn, int pos);