1C ISA2+pooncerelease+poacquirerelease+poacquireonce
2
3(*
4 * Result: Never
5 *
6 * This litmus test demonstrates that a release-acquire chain suffices
7 * to order P0()'s initial write against P2()'s final read.  The reason
8 * that the release-acquire chain suffices is because in all but one
9 * case (P2() to P0()), each process reads from the preceding process's
10 * write.  In memory-model-speak, there is only one non-reads-from
11 * (AKA non-rf) link, so release-acquire is all that is needed.
12 *)
13
14{}
15
16P0(int *x, int *y)
17{
18	WRITE_ONCE(*x, 1);
19	smp_store_release(y, 1);
20}
21
22P1(int *y, int *z)
23{
24	int r0;
25
26	r0 = smp_load_acquire(y);
27	smp_store_release(z, 1);
28}
29
30P2(int *x, int *z)
31{
32	int r0;
33	int r1;
34
35	r0 = smp_load_acquire(z);
36	r1 = READ_ONCE(*x);
37}
38
39exists (1:r0=1 /\ 2:r0=1 /\ 2:r1=0)
40