Test safe460

PPC safe460
"SyncdWW Rfe LwSyncdRR Fre"
Cycle=SyncdWW Rfe LwSyncdRR Fre
Relax=
Safe=Fre LwSyncdRR BCSyncdWW
{
0:r2=x; 0:r4=y;
1:r2=y; 1:r4=x;
}
 P0           | P1           ;
 lwz r1,0(r2) | li r1,1      ;
 lwsync       | stw r1,0(r2) ;
 lwz r3,0(r4) | sync         ;
              | li r3,1      ;
              | stw r3,0(r4) ;
exists
(0:r1=1 /\ 0:r3=0)