Test RDW

PPC RDW (PPCPPOThree)
"is RR to same location in ppo?, intervening write variation"
{
1:r6=x; 1:r7=y; 1:r8=z;
0:r7=y; 0:r8=z;
2:r6=x;
}
P0           |P1            |P2           ;
li r1,1      |lwz r1,0(r7)  |li r1,1      ;
stw r1,0(r8) |xor r9,r1,r1  |stw r1,0(r6) ;
sync         |lwzx r3,r9,r6 |             ;
li r2,2      |lwz r4,0(r6)  |             ;
stw r2,0(r7) |xor r10,r4,r4 |             ;
             |lwzx r2,r10,r8|             ;

Observed
    1:r1=2; 1:r2=0; 1:r3=0; 1:r4=1;