Test m4s

PPC m4s (mFours)
"rwc with syncs (see also rwcv1.litmus)"
{
0:r5=x;
1:r5=x; 1:r6=y;
2:r5=x; 2:r6=y;
0:r1=1;
2:r1=1;
}
P0          |P1          |P2          ;
stw r1,0(r5)|lwz r1,0(r5)|stw r1,0(r6);
            |sync        |sync        ;
            |lwz r2,0(r6)|lwz r3,0(r5);
exists (1:r1=1 /\ 1:r2=0 /\ 2:r3=0)