ref: 65e0e1c3e37c966d0c18178ad8a4c54c0c0fbce9 dir: /sys/src/libc/386/387/tan.s/
TEXT tan(SB), $0 FMOVD a+0(FP), F0 FPTAN FMOVDP F0, F0 /* get rid of extra 1.0 */ RET