PPC R01 "Wse PodWR Fre PodWW" (* Allowed by PLDI, Forbiden by CAV *) {0:r2=y; 0:r4=x; 1:r2=x; 1:r4=y;} P0 | P1 ; li r1,2 | li r1,1 ; stw r1,0(r2) | stw r1,0(r2) ; sync | lwsync ; lwz r3,0(r4) | li r3,1 ; | stw r3,0(r4) ; Observed 0:r3=0; y=2;