#ifdef __GNUC__
# define likely(x) __builtin_expect((x),1)
# define unlikely(x) __builtin_expect((x),0)
+# ifdef __clang__
+# define noinline __attribute__((noinline))
+# else
+# define noinline __attribute__((noinline,noclone))
+# endif
+# define unused __attribute__((unused))
#else
# define likely(x) (x)
# define unlikely(x) (x)
+# define noinline
+# define unused
#endif
#ifndef __has_builtin
#define __has_builtin(x) 0
#endif
+#if __has_builtin(__builtin_add_overflow) || (defined(__GNUC__) && __GNUC__ >= 5)
+#define add_overflow(a, b, r) __builtin_add_overflow(a, b, &(r))
+#define sub_overflow(a, b, r) __builtin_sub_overflow(a, b, &(r))
+#else
+#define add_overflow(a, b, r) ({r = (u32)a + (u32)b; (a ^ ~b) & (a ^ r) & (1u<<31);})
+#define sub_overflow(a, b, r) ({r = (u32)a - (u32)b; (a ^ b) & (a ^ r) & (1u<<31);})
+#endif
+