Test LISA2Rec1G

LISA LISA2Rec1G
(*
 * Result: Never
 *
 * One RCU grace period with a pair of RCU read-side critical sections,
 * but with P0's memory barrier and RCU read-side critical section
 * having effect.  Cycle forbidden.
 *)
{
x0 = 0;
x1 = 0;
x2 = 0;
x3 = 0;
}
 P0                 | P1            | P2                 ;
 f[rcu_read_lock]   | r[once] r1 x1 | f[rcu_read_lock]   ;
 r[once] r2 x0      | f[sync]       | r[once] r2 x3      ;
 f[mb]              | w[once] x3 1  | w[once] x0 1       ;
 w[once] x1 1       | r[once] r3 x2 | f[rcu_read_unlock] ;
 w[once] x2      1  |               |                    ;
 f[rcu_read_unlock] |               |                    ;
Observed
    2:r2=1; 1:r3=1; 1:r1=0; 0:r2=1;