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[Bug tree-optimization/55616] bogus warning about undefined overflow after overflow check
- From: "rguenth at gcc dot gnu.org" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Thu, 31 Jan 2013 10:47:55 +0000
- Subject: [Bug tree-optimization/55616] bogus warning about undefined overflow after overflow check
- Auto-submitted: auto-generated
- References: <bug-55616-4@http.gcc.gnu.org/bugzilla/>
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55616
--- Comment #5 from Richard Biener <rguenth at gcc dot gnu.org> 2013-01-31 10:47:55 UTC ---
(In reply to comment #4)
> (In reply to comment #3)
> > I don't see anything bogus on the warning, it is useful to inform the developer
> > about potentially unintended optimization removing some conditional.
>
> Neither programmer wrote (X + c) < X, this pattern does not occur in Okular nor
> Qt. I'm open to labeling the warning as "very difficult to diagnose" or
> "unhelpful" in these cases, and not "bogus". But I think it's a problem
> because it distracts from the real problems this warning intends to catch.
Well, but the possible overflow is present in the literal
'number_of_elements_in_path+100'. Yes, hard to track the warning down to
that possible issue, but I don't think we can improve much on that front.