+
+/** @{ Register selection callback.
+ *
+ * The register allocator can use either one of two built-in register
+ * selection behaviors (ie. lowest-available or round-robin), or the
+ * user can implement it's own selection policy by setting an register
+ * selection callback. The parameters to the callback are:
+ *
+ * - n the graph node, ie. the virtual variable to select a
+ * register for
+ * - regs bitset of available registers to choose; this bitset
+ * contains *all* registers, but registers of different
+ * classes will not have their corresponding bit set.
+ * - data callback data specified in ra_set_select_reg_callback()
+ */
+typedef unsigned int (*ra_select_reg_callback)(
+ unsigned int n, /* virtual variable to choose a physical reg for */
+ BITSET_WORD *regs, /* available physical regs to choose from */
+ void *data);
+