Thanks for the reference, that is much better than my vague recollections. What I remembered having seen advertised (presented as an improvement, of course) is

Thanks for the reference, that is much better than my vague recollections. What I remembered having seen advertised (presented as an improvement, of course) is new early-exit paths for the easier arguments to division. The marketing brochure emphasised the novelty, so I must have wrongly inferred that division took constant time before that. Considering paragraph 2.2 in http://users.elis.ugent.be/~brdsutte/research/publications/2012TACOvancleemput.pdf http://users.elis.ugent.be/~brdsutte/research/publications/2... , I may have been remembering a new division algorithm in Nehalem. I will cite that article from now on.