Test bb3

PPC bb3 (BBThree)
"4 proc, st/st ld/ld, lwsync/sync barriers"
{
P0:r5=x ; P0:r2=2 ;
P1:r6=y ; P1:r1=1 ;
P2:r5=x ; P2:r6=y ; P2:r1=1 ;P2:r2=2;
P3:r5=x ; P3:r6=y ;
}
P0           |P1           |P2           |P3           ;
stw r2,0(r5) |stw r1,0(r6) |stw r1,0(r5) |lwz r1,0(r6) ;
             |             |lwsync       |sync         ;
             |             |stw r2,0(r6) |lwz r2,0(r5) ;
Observed
    3:r1=1; 3:r2=0; x=1; y=1;
and 3:r1=1; 3:r2=2; x=1; y=1;
and 3:r1=1; 3:r2=0; x=2; y=1;