# define EXECL_LIKE(ntrail) __attribute__((__sentinel__(ntrail)))
#endif
+#if GCC_VERSION_P(2, 7)
+# define LAUNDER(x) \
+ ({ __typeof__(x) _y; __asm__("" : "=g"(_y) : "0"(x)); _y; })
+# define RELAX do __asm__ __volatile__("" ::: "memory"); while (0)
+#endif
+
#if CLANG_VERSION_P(3, 3)
# define MLIB__PRAGMA_HACK(x) _Pragma(#x)
# define MUST_CHECK
#endif
+#ifndef LAUNDER
+# define LAUNDER
+#endif
+
+#ifndef RELAX
+# define RELAX
+#endif
+
#ifndef GCC_WARNING
# define GCC_WARNING(warn)
#endif