C ISA2+pooncerelease+poacquirerelease+poacquireonce
(*
* Result: Never
*
* This litmus test demonstrates that a release-acquire chain suffices
* to order P0()'s initial write against P2()'s final read. The reason
* that the release-acquire chain suffices is because in all but one
* case (P2() to P0()), each process reads from the preceding process's
* write. In memory-model-speak, there is only one non-reads-from
* (AKA non-rf) link, so release-acquire is all that is needed.
*)
{}
P0(int *x, int *y)
{
WRITE_ONCE(*x, 1);
smp_store_release(y, 1);
}
P1(int *y, int *z)
int r0;
r0 = smp_load_acquire(y);
smp_store_release(z, 1);
P2(int *x, int *z)
int r1;
r0 = smp_load_acquire(z);
r1 = READ_ONCE(*x);
exists (1:r0=1 /\ 2:r0=1 /\ 2:r1=0)
