ref: 0a8b50a42d13a1e56a8c8b1e966e1946d07431d8 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