ref: 17a9a0291b51a6f1bf84e8ee5fdb2f46db8519bb 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