AArch64 MP+CAS-rfi-ctrl+acq { 0:X0=x; 0:X4=y; 1:X1=y; 1:X3=x; } P0 | P1 ; MOV W1,#0 | LDAR W0,[X1] ; MOV W2,#1 | LDR W2,[X3] ; CAS W1,W2,[X0] | ; CBNZ W1,out | ; MOV W3,#1 | ; STR W3,[X4] | ; out: | ; Observed x=1; 1:X2=0; 1:X0=1;