Test hh4

PPC hh4 (BasicHHFour)
{
x=0 ; y=0;
0:r4=x ; 0:r5=y;
1:r4=x ; 1:r5=y;
0:r1=1 ; 0:r2=2 ; 1:r1=1;
2:r5=y ; 2:r2=2 ;
}

P0           |     P1        |P2           ;
stw r2,0(r4) | lwz r2,0(r5)  |stw r2,0(r5) ;
lwsync       | xor r9,r2,r2  |             ;
stw r1,0(r5) | stwx r1,r9,r4 |             ;

locations [1:r2; x; y;]
exists (
(1:r2=2 /\ x=2 /\ y=2)
)