1C MP+poonceonces
 2
 3(*
 4 * Result: Sometimes
 5 *
 6 * Can the counter-intuitive message-passing outcome be prevented with
 7 * no ordering at all?
 8 *)
 9
10{}
11
12P0(int *buf, int *flag) // Producer
13{
14	WRITE_ONCE(*buf, 1);
15	WRITE_ONCE(*flag, 1);
16}
17
18P1(int *buf, int *flag) // Consumer
19{
20	int r0;
21	int r1;
22
23	r0 = READ_ONCE(*flag);
24	r1 = READ_ONCE(*buf);
25}
26
27exists (1:r0=1 /\ 1:r1=0) (* Bad outcome. *)

 1C MP+poonceonces
 2
 3(*
 4 * Result: Sometimes
 5 *
 6 * Can the counter-intuitive message-passing outcome be prevented with
 7 * no ordering at all?
 8 *)
 9
10{}
11
12P0(int *buf, int *flag) // Producer
13{
14	WRITE_ONCE(*buf, 1);
15	WRITE_ONCE(*flag, 1);
16}
17
18P1(int *buf, int *flag) // Consumer
19{
20	int r0;
21	int r1;
22
23	r0 = READ_ONCE(*flag);
24	r1 = READ_ONCE(*buf);
25}
26
27exists (1:r0=1 /\ 1:r1=0) (* Bad outcome. *)