Without an explicit volatile, aarch64 gcc will copy queue->tail into a
register outside the loop and then continuously compare two registers
against each other. The *(volatile LONG *)& forces gcc to re-read the
memory every iteration. Therefore, queue_is_empty as it is written will
only work from the CS thread.
Signed-off-by: Stefan Dösinger <stefan@codeweavers.com>
Signed-off-by: Henri Verbeet <hverbeet@codeweavers.com>
Signed-off-by: Alexandre Julliard <julliard@winehq.org>