What do you mean?

As Patrick mentions, ICC generates code that doesn't follow IEEE-754: https://news.ycombinator.com/item?id=20437375 (I should have mentioned I was talking about that rather than the C standard).

Oh I see, you're talking about floating point.

So basically ICC has -ffast-math (or -funsafe-math-optimizations) on by default, and you can turn it off with an explicit flag?

I see this as more of a philosophical difference than a material one since you can just add or remove the flag on either one...