-ffast-math and floating point reordering

[Robert Dewar]

Dale Johannesen wrote:
> One point I haven't seen yet:
> A couple of strict-constructionists have asserted that people
> who want reassociation done in a nonstandard way can easily rewrite their
> code to achieve this.  This is not really true, because such expressions
> often arise as a result of other optimizations, in a way that isn't obvious
> from the source.  Offhand, inlining, unrolling, and constant/copy 
> propagation
> can all do it, and there are probably more.

Well in the absence of the (very annoying) extra precision phenomenon,
none of these optimizations should have observable effects.