Function atomic_xadd 

pub const unsafe fn atomic_xadd<T: Copy, U: Copy, const ORD: AtomicOrdering>(
    dst: *mut T,
    src: U,
) -> T

🔬This is a nightly-only experimental API. (core_intrinsics)

Adds to the current value, returning the previous value. T must be an integer or pointer type. U must be the same as T if that is an integer type, or usize if T is a pointer type.

Safety

• If T is an integer type, this is equivalent to Atomic<T>::from_ptr followed by Atomic<T>::fetch_add. Refer to the documentation of Atomic<T>::from_ptr for safety requirements.

• If T is a pointer type, this is equivalent to AtomicPtr<P>::from_ptr followed by AtomicPtr<P>::fetch_byte_add, where P is the pointee type of the pointer. Refer to the documentation of AtomicPtr<P>::from_ptr for safety requirements.

The stabilized version of this intrinsic is available on the atomic types via the fetch_add method. For example, AtomicIsize::fetch_add.