C SB+rfionceonce-poonceonces

(*
 * Result: Sometimes
 *
 * This litmus test demonstrates that LKMM is not fully multicopy atomic.
 *)

{
	int x;
	int y;
}

P0(int *x, int *y)
{
	int r1;
	int r2;

	WRITE_ONCE(*x, 1);
	r1 = READ_ONCE(*x);
	r2 = READ_ONCE(*y);
}

P1(int *x, int *y)
{
	int r3;
	int r4;

	WRITE_ONCE(*y, 1);
	r3 = READ_ONCE(*y);
	r4 = READ_ONCE(*x);
}

locations [0:r1; 1:r3; x; y] (* Debug aid: Print things not in "exists". *)
exists (0:r2=0 /\ 1:r4=0)