What is acceptable for -ffast-math? (Was: associative law incombine)

[Gabriel Dos_Reis]

The transformations in question aren't documented.  So, those having
"valid reasons to request them" don't even know what there are
requesting with -fdubious-math.

Right now, we're discussing the ability of the compiler to transform
something like a/b/c into a/(b*c).  Some argue on the ground of speed
considerations, that the programmer would expect the compiler to do
that. But then, if they would have written that form in the first 
place.

The issue isn't about "freedom vs. no-freedom".

-- Gaby