ref: 056eb9f7d8b1a577f7029e3d0e6d40cf6c2e86b0 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