Fetch_add

原子加

• x86平台

  static inline uint64
  pg_atomic_fetch_add_u64_impl(volatile pg_atomic_uint64 *ptr, int64 add_)
  {
          uint64 res;
          __asm__ __volatile__(
                  "       lock                            \n"
                  "       xaddq   %0,%1           \n"
  :               "=q"(res), "=m"(ptr->value)
  :               "0" (add_), "m"(ptr->value)
  :               "memory", "cc");
          return res;
  }

• AArch64平台

  static inline uint64
  pg_atomic_fetch_add_u64_impl(volatile pg_atomic_uint64 *ptr, int64 add_)
  {
          return __sync_fetch_and_add(&ptr->value, add_);
  }