Test l4

PPC l4 (BasicLFour)
{
0:r4=x; 0:r5=y;
1:r4=x; 1:r5=y;
2:r5=y;
0:r1=1;
1:r2=2; 1:r1=1;
2:r1=1;
}
P0           |P1          |P2          ;
lwz r2,0(r5) |stw r2,0(r4)|stw r1,0(r5);
xor r9,r2,r2 |sync        |            ;
stwx r1,r9,r4|lwz r1,0(r5)|            ;
locations [0:r2; 1:r1; x;]
exists (0:r2=1 /\ 1:r1=0 /\ x=2) ;