ref: d5f2d2cc3fc7c2d3701e906df5d2d53781c4ee9c 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