ref: 0d7e3fd4a27a8494d8e513b43cac12b7d9b9dea6 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