PPC rich4 (PPCRichFour) { 0:r5=x ; 0:r6=y; 1:r5=x ; 1:r6=y; 1:r1=1 ; 1:r2=2; } P0 | P1 ; lwz r1,0(r5) |stw r2,0(r6) ; li r2,3 |lwsync ; xor r9,r1,r1 | ; stwx r2,r9,r6|stw r1,0(r5) ; locations [0:r1; y;] exists (true)