http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57558
Richard Biener <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Blocks| |53947
--- Comment #1 from Richard Biener <rguenth at gcc dot gnu.org> ---
That's because the first variant can loop infinitely for n == ULONG_MAX
and that "infinite" cannot be represented using new induction variable
as the vectorizer wants to. Well, not easily at least.
