ref: 8ea31ae7b21e9f0c8991b2b861bc51ea3d67c3cd 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