Test wrcv6

PPC wrcv6 (PPCWRCSix)
"write-to_read causality, boehm adve PLDI'08 (Fig 5.)"
(Paul Mc Keene 'solution')
{
P0:r1=x;
P1:r1=x; P1:r2=y;
P2:r1=x; P2:r2=y;
P0:r9=1; P1:r9=1;
P3:r8=2; P3:r1=x;
} 
      P0    |       P1    |   P2         |P3         ;
stw r9,0,r1 | lwz r5,0,r1 | lwz r5,0,r2  |stw r8,0,r1;
            | lwsync      | cmpw r5,r5   |;
            | stw r9,0,r2 | bne L2       |;
            |             | isync        |;
            |             | lwz r6,0,r1  |;
            |             | L2:          |;
exists
 ( (P1:r5=1 /\ P2:r5=1 /\ P2:r6=0)
\/
(P1:r5=2 /\ P2:r5=1 /\ P2:r6=0) )