Test ARM-rfn-obs-v2

AArch64 ARM-rfn-obs-v2
(*
   P0     P1
   Wx=3   Ry=1
   wmb    data dep
   Wy=1   Wx=1
          Rx=1
          Wx=2
*)
{
0:X0=3; 0:X1=x; 0:X2=1; 0:X3=y;
1:X1=y; 1:X3=x; 1:X4=2;
}
 P0          | P1          ;
 STR W0,[X1] | LDR W0,[X1] ;
 DMB ST      | STR W0,[X3] ;
 STR W2,[X3] | LDR W2,[X3] ;
             | STR W4,[X3] ;
exists (1:X0=1 /\ 1:X2=1 /\ x=3)