Test LB+addr+addrpx-poxp+VAR

AArch64 LB+addr+addrpx-poxp+VAR
"does STXR need to resolve its address before it can fail?
based on: DpAddrdW Rfe DpAddrdWPX PodWWXP Rfe"
{
0:X1=x; 0:X4=y;
1:X1=y; 1:X3=z; 1:X9=x;
}
 P0                  | P1                ;
 LDR W0,[X1]         | LDR W0,[X1]       ;
 EOR W2,W0,W0        | EOR W2,W0,W0      ;
 MOV W3,#1           | MOV W5,#1         ;
 STR W3,[X4,W2,SXTW] | ADD X4,X3,W2,SXTW ;
                     | STXR W7,W5,[X4]   ;
                     | MOV W8,#1         ;
                     | STR W8,[X9]       ;
Observed
    z=0; 1:X7=1; 1:X0=1; 0:X0=1;