Test bb8

PPC bb8 (BBEight)
"3 proc, st/st ld/ld, isync/sync barriers simplification of ppc/ccv3 test"
{
0:r5=x ;
1:r5=x ; 1:r6=y;
2:r5=x ; 2:r6=y;
}
P0           |P1          |P2           ;
li r1,1      |lwz r1,0(r5)|li r1,1      ;
stw r1,0(r5) |isync       |stw r1,0(r6) ;
             |lwz r2,0(r6)|sync         ;
             |            |li r2,2      ;
             |            |stw r2,0(r5) ;
Observed
    1:r1=2; 1:r2=0; x=1;
and 1:r1=2; 1:r2=0; x=2;