AArch64 LB-ldxr-stxr-rel { 0:X1=x; 0:X3=y; 0:X10=z; 1:X1=y; 1:X3=x; } P0 | P1 ; LDR W0,[X1] | LDR W0,[X1] ; LDXR W12,[X10] | MOV W2,#1 ; STXR W11,W0,[X10] | STLR W2,[X3] ; EOR W22, W12, W12 | ; ADD W2, W22, #1 | ; STR W2,[X3] | ; Observed z=1; 1:X0=1; 0:X0=1; and z=0; 1:X0=1; 0:X0=1;