ref: 0ed8a3bd7b1bbe2a3857f2abcaabdc4edd2d8b05 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