ref: 1d0f8a7e512e5abfea9c5d2fdf2fb4c05efc720b 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