Re: -ffast-math option live up to its name?

[Ian Lance Taylor <iant at google dot com>]

kevin diggs <diggskevin38@gmail.com> writes:

> Does the -ffast-math option speed up operations enough to make
> fighting with mozilla/firefox source worth the trouble? I think the
> main problem is identifying NaNs.

As with all such questions, the real answer is: it depends.

If your code uses a lot of floating point operations, then -ffast-math
can speed things up quite a bit on some processors, notably 32-bit x86
processors.  E.g., if your code is dominated by calls to sin, then
-ffast-math could give you as much as a 50% speed improvement on that
platform.  But of course not much code is dominated by calls to sin, and
the actual speedup is going to depend on the actual code.

Ian