Test MP+rel+isb

AArch64 MP+rel+isb
{
0:X1=x; 0:X3=y;
1:X0=y; 1:X2=x;
}
 P0           | P1          ;
 MOV W0,#1    | LDR W1,[X0] ;
 STR W0,[X1]  | ISB         ;
 MOV W2,#1    | LDR W3,[X2] ;
 STLR W2,[X3] |             ;
Observed
    1:X3=0; 1:X1=1;