Test ppob

PPC ppob (PPCPPOEleven)
"control for ppoa"
{
0:r7=y; 0:r8=z; 0:r9=x;
1:r7=y; 1:r8=z;
}
P0            |P1           ;
lwz r1,0(r7)  |li r1,1      ;
cmpwi r1,0    |stw r1,0(r8) ;
beq L00       |sync         ;
L00:          |li r2,1      ;
li r3,1       |stw r2,0(r7) ;
stw r3,0(r9)  |             ;
lwz r2,0(r9)  |             ;
xor r10,r2,r2 |             ;
isync         |             ;
lwzx r4,r10,r8|             ;
locations [0:r1; 0:r4;]
exists (0:r1=1 /\ 0:r4=0)