Test LB+dmb.sy+poxp

AArch64 LB+dmb.sy+poxp
"DMB.SYdRW RfePX PodRWXP Rfe"
Prefetch=0:x=F,0:y=W,1:y=F,1:x=W
Com=Rf Rf
Orig=DMB.SYdRW RfePX PodRWXP Rfe
{ ok=1;
0:X1=x; 0:X3=y;
1:X0=y; 1:X4=x; 1:X6=ok;
}
 P0          | P1              ;
 LDR W0,[X1] | LDXR W1,[X0]    ;
 DMB SY      | STXR W2,W1,[X0] ;
 MOV W2,#1   | CBNZ W2,Fail1   ;
 STR W2,[X3] | MOV W3,#1       ;
             | STR W3,[X4]     ;
             | B Exit1         ;
             | Fail1:          ;
             | MOV W5,#0       ;
             | STR W5,[X6]     ;
             | Exit1:          ;
exists
(ok=1 /\ y=1 /\ 0:X0=1 /\ 1:X1=1)