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[Bug math/3268] fma for all targets without hardware fma instructions is incorrect.


------- Additional Comments From jakub at redhat dot com  2007-02-05 20:50 -------
Why do you need a soft-fp fmaf other than generic
float fmaf (float x, float y, float z)
{
  return ((double) x * y) + z;
}
?

As DFmode has more than twice as wide mantissa as SFmode and bigger exponent
range as well, (double) x * (double) y will be IMHO always precise, so no
rounding will ever happen there.
Similarly for fma and IEEE quad long double.
Only fmal needs soft-fp or gmp implementation, on all architectures that don't
have it in hardware, and fma for IEEE extended long double or IBM 2x double long
double.

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=3268

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