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From: "aldyh at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/103483] context-sensitive ranges change triggers stringop-overread
Date: Wed, 01 Dec 2021 16:38:26 +0000 [thread overview]
Message-ID: <bug-103483-4-sDWSl07FEi@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-103483-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103483
Aldy Hernandez <aldyh at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |aldyh at gcc dot gnu.org,
| |amacleod at redhat dot com,
| |jwakely.gcc at gmail dot com
--- Comment #6 from Aldy Hernandez <aldyh at gcc dot gnu.org> ---
(In reply to Martin Sebor from comment #4)
> I don't think this can be "fixed." Most middle end warnings work a single
> statement at a time and depend on optimization like constant propagation and
> dead code elimination to do their job. If one optimization exposes an
> invalid statement that would otherwise be eliminated by another optimization
> that doesn't take place, the warnings trigger. That's all by design and
> there's no way change that. In the test case in comment #0 where the
> precondition is that d be less than a, making it explicit (e.g., either as
> Andrew suggests in comment #1 or by adding an equivalen assert statement)
> seems like the best and only solution.
Oh, it totally could be fixed. Whether you want to or not, is a separate
issue. These false positives "by design" arguments are just a cop-out.
As Jonathan said, if the warning code can't handle the IL as presented, it
should give up, not assume code is wrong by default.
It seems we do very bad with a lot of these warnings at -O1. We should just
disable them at low optimization levels if we can't/won't take measures to
reduce the false positive rate here.
next prev parent reply other threads:[~2021-12-01 16:38 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-30 4:27 [Bug c++/103483] New: constexpr basic_string " john at mcfarlane dot name
2021-11-30 4:39 ` [Bug c++/103483] context-sensitive ranges change " pinskia at gcc dot gnu.org
2021-11-30 12:11 ` redi at gcc dot gnu.org
2021-11-30 17:56 ` [Bug middle-end/103483] " msebor at gcc dot gnu.org
2021-11-30 18:13 ` msebor at gcc dot gnu.org
2021-11-30 22:33 ` john at mcfarlane dot name
2021-12-01 16:38 ` aldyh at gcc dot gnu.org [this message]
2021-12-01 16:53 ` redi at gcc dot gnu.org
2021-12-01 23:38 ` pinskia at gcc dot gnu.org
2021-12-01 23:44 ` pinskia at gcc dot gnu.org
2021-12-02 22:14 ` msebor at gcc dot gnu.org
2021-12-09 23:24 ` cvs-commit at gcc dot gnu.org
2021-12-10 22:10 ` jason at gcc dot gnu.org
2021-12-11 0:56 ` msebor at gcc dot gnu.org
2021-12-11 22:43 ` jason at gcc dot gnu.org
2022-01-17 22:44 ` [Bug middle-end/103483] [12 regression] " jason at gcc dot gnu.org
2022-01-17 23:10 ` amacleod at redhat dot com
2022-01-18 0:47 ` msebor at gcc dot gnu.org
2022-01-28 2:02 ` pinskia at gcc dot gnu.org
2022-01-28 5:03 ` jason at gcc dot gnu.org
2022-01-28 6:38 ` law at gcc dot gnu.org
2022-01-28 7:48 ` redi at gcc dot gnu.org
2022-01-28 15:23 ` law at gcc dot gnu.org
2022-03-09 14:11 ` rguenth at gcc dot gnu.org
2022-03-14 23:58 ` msebor at gcc dot gnu.org
2022-05-06 8:32 ` [Bug middle-end/103483] [12/13 " jakub at gcc dot gnu.org
2022-10-19 9:43 ` rguenth at gcc dot gnu.org
2023-05-08 12:23 ` [Bug middle-end/103483] [12/13/14 " rguenth at gcc dot gnu.org
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