#if defined(__GNUC__) && !defined(LUA_NOBUILTIN)
#define luai_likely(x)    (__builtin_expect(((x) != 0), 1))
#define luai_unlikely(x)   (__builtin_expect(((x) != 0), 0))
#else
#define luai_likely(x)    (x)
#define luai_unlikely(x)   (x)
#endif



#define LIKELY(x) __builtin_expect(!!(x),1) 
#define UNLIKELY(x) __builtin_expect(!!(x),0)


https://blog.csdn.net/GrubLinux/article/details/37543489

unlikely