Test auto/LB-GRR+R-Dd+OB-O+R-Oc

LISA auto/LB-GRR+R-Dd+OB-O+R-Oc
(*
 * Result: Sometimes
 * P1-P2 rf OB-O: Never->Maybe: Note lack of C11 guarantee, no synchronizes-with
 * P2-P3 rf R-Oc: Note lack of C11 guarantee, control dependency
 * P3 Oc,GRR: Maybe->Sometimes: Control dependencies do not order trailing reads
 *)
{
 0:r3=x2; x1=y1; 3:r4=1;
}
 P0               | P1             | P2              | P3                 | P4           ;
 r[once] r1 u0    | r[deref] r1 x1 | r[once] r1 x2   | r[once] r1 x3      | w[once] v0 1 ;
 w[release] x1 r3 | f[mb]          | w[release] x3 1 | mov r4 (neq r1 r4) | f[mb]        ;
                  | w[once] r1 1   |                 | b[] r4 CTRL3       | w[once] u0 1 ;
                  |                |                 | r[once] r2 v0      |              ;
                  |                |                 | CTRL3:             |              ;
Observed
    3:r2=0; 3:r1=1; 2:r1=1; 1:r1=x2; 0:r1=1;