ref: 267e3cc41aa9aed63f2b9f7e9b69ef0b49f3c7c7 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