PPC g3 (BasicGThree) { x=0 ; y=0; 0:r4=x ; 0:r5=y; 1:r4=x ; 1:r5=y; 0:r1=1 ; 1:r2=2 ; } P0 | P1 ; stw r1,0(r4) | stw r2,0(r5) ; lwsync | sync ; stw r1,0(r5) | lwz r3,0(r4) ; Observed 1:r3=0; y=2;