ref: bc1cc79225f0b006dd66d4fd81030d06f83bfca2 dir: /sys/src/libc/386/387/sqrt.s/
TEXT sqrt(SB), $0 FMOVD a+0(FP), F0 FTST WAIT FSTSW AX SAHF JLO bad FSQRT RET bad: FMOVDP F0, F0 CALL NaN(SB) RET