A big problem with -ffast-math is that it causes isnan and isinf to be completely, silently broken (gcc and clang).
Like, "oh you want faster FP operations? well then surely you have no need to ever be able to detect infinite or NaN values.."
> well then surely you have no need to ever be able to detect infinite or NaN values
Well yeah, maybe I actually don't.
If you don't, that's fine. But is it really necessary or desirable for -ffast-math to silently break isinf() and isnan()? I don't think it's inconceivable that some people might need those.
I mean, I can write my own implementations, but it seems kind of silly that I should need to in the first place.