I think the biggest thing is that programmers can safely assume that a floating point `x-y` is nonzero if `x != y`. You can actually go farther and know that it's an exact computation (with no error) if the two are close [1]. But both results only hold if subnormals don't flush to or behave like zero.
It's not too hard to imagine how an algorithm might depend upon that — there could be a branch for the case where `x == y` and then a branch that relies upon dividing by `(x-y)` and assumes that it's not a division by zero.
It's not too hard to imagine how an algorithm might depend upon that — there could be a branch for the case where `x == y` and then a branch that relies upon dividing by `(x-y)` and assumes that it's not a division by zero.
1. https://en.wikipedia.org/wiki/Sterbenz_lemma