From: Joseph Myers <joseph@codesourcery.com>
To: Bernd Edlinger <bernd.edlinger@hotmail.de>
Cc: "gcc-patches@gcc.gnu.org" <gcc-patches@gcc.gnu.org>,
Jason Merrill <jason@redhat.com>
Subject: Re: [PATCHv2] Add a warning for suspicious use of conditional expressions in boolean context
Date: Mon, 05 Sep 2016 11:41:00 -0000 [thread overview]
Message-ID: <alpine.DEB.2.20.1609051122070.30482@digraph.polyomino.org.uk> (raw)
In-Reply-To: <AM4PR0701MB2162C862449B51EF27F6AC52E4E70@AM4PR0701MB2162.eurprd07.prod.outlook.com>
On Sun, 4 Sep 2016, Bernd Edlinger wrote:
> good to have as well. But this code would still be suspicious
> even if (x << y) is put in parentheses, because the shift count does
> not change the result of the condition, as the integer overflow is
> undefined behavior, and if it does not have side effects or does
> not throw something, it can even be optimized away.
It's defined in GNU C (when the shift count is nonnegative and less than
the width of the type) - we document that we do not optimize on the basis
of it being undefined (although ubsan will still detect it).
--
Joseph S. Myers
joseph@codesourcery.com
next prev parent reply other threads:[~2016-09-05 11:23 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-02 18:53 [PATCH] " Bernd Edlinger
2016-09-04 8:45 ` [PATCHv2] " Bernd Edlinger
2016-09-05 11:41 ` Joseph Myers [this message]
2016-09-05 14:59 ` Bernd Edlinger
2016-09-05 16:57 ` Joseph Myers
[not found] ` <CAPWdEev7VW5LT47iPh-0EgAJz5ELEnoZ_snLtg-F5ZR+etLimg@mail.gmail.com>
2016-09-05 20:03 ` Bernd Edlinger
2016-09-12 19:40 ` [PATCH] " Jeff Law
2016-09-12 20:02 ` Bernd Edlinger
2016-09-12 20:18 ` Jeff Law
2016-09-12 21:28 ` Bernd Edlinger
2016-09-14 16:14 ` [PATCH, updated] " Bernd Edlinger
2016-09-14 16:50 ` Jason Merrill
2016-09-14 17:41 ` Bernd Edlinger
2016-09-14 19:04 ` Jason Merrill
[not found] ` <AM4PR0701MB2162B5B8246F8A10B4B6E42CE4F10@AM4PR0701MB2162.eurprd07.prod.outlook.com>
2016-09-14 20:17 ` [PATCHv3] " Bernd Edlinger
2016-09-15 15:52 ` [PATCH, updated] " Jeff Law
2016-09-15 16:20 ` Bernd Edlinger
2016-09-15 16:36 ` Jeff Law
2016-09-15 16:51 ` Bernd Edlinger
2016-09-15 19:21 ` Joseph Myers
2016-09-15 20:34 ` Jason Merrill
2016-09-15 20:45 ` Bernd Edlinger
2016-09-14 17:54 ` Steve Kargl
2016-09-14 17:56 ` Bernd Edlinger
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