ref: 1d563ec8e9a5a485597a9f9c24d1f5a698f2c8a3 dir: /sys/src/ape/lib/ap/386/tas.s/
TEXT tas(SB),$0 MOVL $0xdeadead,AX MOVL l+0(FP),BX XCHGL AX,(BX) RET