+/**
+ * The value_of operation.
+ * This operation returns for every IR node an associated tarval if existing,
+ * returning tarval_bad otherwise.
+ * No calculations are done here, just a lookup.
+ */
+typedef ir_tarval *(*value_of_func)(const ir_node *self);
+
+extern value_of_func value_of_ptr;
+
+/**
+ * Set a new value_of function.
+ *
+ * @param func the function, NULL restores the default behavior
+ */
+void set_value_of_func(value_of_func func);
+
+/**
+ * Returns the associated tarval of a node.
+ */
+static inline ir_tarval *value_of(const ir_node *n)
+{
+ return value_of_ptr(n);
+}
+
+/**
+ * returns true if a value becomes zero when converted to mode @p mode
+ */
+bool ir_zero_when_converted(const ir_node *node, ir_mode *dest_mode);
+
+int ir_mux_is_abs(const ir_node *sel, const ir_node *mux_false,
+ const ir_node *mux_true);
+
+ir_node *ir_get_abs_op(const ir_node *sel, ir_node *mux_false,
+ ir_node *mux_true);
+
+/**
+ * return true if the Mux node will be optimized away. This can be used for
+ * the if-conversion callback. Allowing these Muxes should be always safe, even
+ * if the backend cannot handle them.
+ */
+bool ir_is_optimizable_mux(const ir_node *sel, const ir_node *mux_false,
+ const ir_node *mux_true);