Test m6d

PPC m6d (PPCMSixDep)
"hexa, write-to_read causality, boehm adve PLDI'08 (Fig 5.)"
{
P0:r5=x;
P1:r5=x; P1:r6=y;
P2:r5=x; P2:r6=y;
P0:r1=1; P1:r1=1;
P3:r2=2; P3:r6=y;
} 
      P0    |       P1      |   P2         |P3          ;
stw r1,0,r5 | lwz r2,0,r5   | lwz r2,0,r6  |stw r2,0(r6);
            | xor r9,r2,r2  | xor r9,r2,r2 |            ;
            | stwx r1,r9,r6 | lwzx r1,r9,r5|            ;

locations [x;y;]
exists (1:r2=1 /\ 2:r2=2 /\ 2:r1=0 /\ y=2)