Test n2

PPC n2  (PPCNTwo)
"super iriw, no barriers"
{
P0:r4=x ; P0:r5=y ;
P1:r6=z ; P1:r7=t ;
P2:r5=y ; P2:r6=z ;
P3:r7=t ; P3:r4=x ;
P2:r1=1 ; P2:r2=1 ;
P3:r2=1 ; P3:r1=1 ;
}

P0           |P1           |P2           |P3           ;
lwz r1,0(r4) |lwz r1,0(r6) |stw r2,0(r5) |stw r2,0(r7) ; 
lwz r2,0(r5) |lwz r2,0(r7) |stw r1,0(r6) |stw r1,0(r4) ;
locations [0:r1; 0:r2; 1:r1; 1:r2;]
exists(0:r1=1 /\ 1:r1=1 /\ 0:r2=0 /\ 1:r2=0)
(* Perfect octogon *)