Function std::intrinsics::atomic_xadd_relaxed

pub unsafe extern "rust-intrinsic" fn atomic_xadd_relaxed<T>(dst: *mut T,                                                             src: T)                                                             -> T

Add to the current value, returning the previous value. The stabilized version of this intrinsic is available on the std::sync::atomic types via the fetch_add method by passing Ordering::Relaxed as the order. For example, AtomicIsize::fetch_add.