Index: generic/gentclAPI.tcl
===================================================================
diff -u -ra54313f558be3d0e7c909fa76cdee874f1880ef3 -rc558f89e9d37ecf8bed1a65fe26ff620bc8b9c96
--- generic/gentclAPI.tcl	(.../gentclAPI.tcl)	(revision a54313f558be3d0e7c909fa76cdee874f1880ef3)
+++ generic/gentclAPI.tcl	(.../gentclAPI.tcl)	(revision c558f89e9d37ecf8bed1a65fe26ff620bc8b9c96)
@@ -476,6 +476,20 @@
  * This source code file was generated by the C-code generator gentclAPI.tcl, 
  * part of the Next Scripting Framework.
  */
+
+#if !defined(likely) 
+# if defined(__GNUC__) && __GNUC__ > 2
+/* Use gcc branch prediction hint to minimize cost of e.g. DTrace
+ * ENABLED checks. 
+ */
+#  define unlikely(x) (__builtin_expect((x), 0))
+#  define likely(x) (__builtin_expect((x), 1))
+# else
+#  define unlikely(x) (x)
+#  define likely(x) (x)
+# endif
+#endif
+
 }
 genstubs
 puts stderr "[array size ::definitions] parsing stubs generated"