ref: 6c7d0aeb7d937a3dcf924f1ef2952ee6c7aa9eb3 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