Function swift_runtime_sys::root::swift::swift_retain

pub unsafe extern "C" fn swift_retain(
    object: *mut HeapObject,
) -> *mut HeapObject

Atomically increments the retain count of an object.

\param object - may be null, in which case this is a no-op

\return object - we return the object because this enables tail call optimization and the argument register to be live through the call on architectures whose argument and return register is the same register.

POSSIBILITIES: We may end up wanting a bunch of different variants:

• the general version which correctly handles null values, swift objects, and ObjC objects
  • a variant that assumes that its operand is a swift object
    • a variant that can safely use non-atomic operations
    • maybe a variant that can assume a non-null object It may also prove worthwhile to have this use a custom CC which preserves a larger set of registers.