[Bug tree-optimization/53265] Warn when undefined behavior implies smaller iteration count

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=53265

--- Comment #7 from Richard Biener <rguenth at gcc dot gnu.org> 2013-03-11 14:17:28 UTC ---
When warnings are disabled the whole function can be skipped and
both estimate and bound be initialized by the result from
number_of_latch_executions (if that returns a constant).