Test ccv4

PPC ccv4 (CCFour)
"Boehm/adve CC example (Fig.8), sync"
{
0:r1=1 ; 0:r5=x;
1:r5=x ; 1:r6=y;
2:r5=x ; 2:r6=y; 2:r1=1; 2:r2=2;
3:r5=x ;
}
P0          |P1          |P2          |P3          ;
stw r1,0(r5)|lwz r1,0(r5)|stw r1,0(r6)|lwz r1,0(r5);
            |sync        |sync        |sync        ;
            |lwz r2,0(r6)|stw r2,0(r5)|lwz r2,0(r5);

(*
  Must be seq const.
*)
locations [x; 3:r1; 3:r2]
~exists 
(1:r1=1 /\ 1:r2=0 /\ x=1 )