# define unlikely(x) __builtin_expect(!!(x), 0)
# define inline inline __attribute__((always_inline))
# define prefetch(x) __builtin_prefetch(x)
+# define is_constant(x) __builtin_constant_p(x)
#else
# define WIMLIBAPI
# define _always_inline_attribute inline
# define likely(x) (x)
# define unlikely(x) (x)
# define prefetch(x)
+# define is_constant(x) (0)
#endif /* __GNUC__ */
#endif /* _WIMLIB_COMPILER_H */