1C WRC+poonceonces+Once 2 3{} 4 5P0(int *x) 6{ 7 WRITE_ONCE(*x, 1); 8} 9 10P1(int *x, int *y) 11{ 12 int r0; 13 14 r0 = READ_ONCE(*x); 15 WRITE_ONCE(*y, 1); 16} 17 18P2(int *x, int *y) 19{ 20 int r0; 21 int r1; 22 23 r0 = READ_ONCE(*y); 24 r1 = READ_ONCE(*x); 25} 26 27exists (1:r0=1 /\ 2:r0=1 /\ 2:r1=0) 28