PPC R+isync+sync "ISyncdWW Wse SyncdWR Fre" Cycle=Fre ISyncdWW Wse SyncdWR { 0:r2=x; 0:r4=y; 1:r2=y; 1:r4=x; } P0 | P1 ; li r1,1 | li r1,2 ; stw r1,0(r2) | stw r1,0(r2) ; isync | sync ; li r3,1 | lwz r3,0(r4) ; stw r3,0(r4) | ; exists (y=2 /\ 1:r3=0)