From: Segher Boessenkool <segher@kernel.crashing.org>
To: Marc Glisse via Gcc-help <gcc-help@gcc.gnu.org>
Cc: Gabriel Ravier <gabravier@gmail.com>,
Marc Glisse <marc.glisse@inria.fr>,
Xi Ruoyao <xry111@xry111.site>,
Jonathan Wakely <jwakely.gcc@gmail.com>,
Jonny Grant <jg@jguk.org>
Subject: Re: std::string add nullptr attribute
Date: Mon, 20 Feb 2023 05:28:38 -0600 [thread overview]
Message-ID: <20230220112838.GO25951@gate.crashing.org> (raw)
In-Reply-To: <7e54f0b6-0c58-e340-46a3-b46fa321a201@inria.fr>
On Mon, Feb 20, 2023 at 12:18:36PM +0100, Marc Glisse via Gcc-help wrote:
> On Mon, 20 Feb 2023, Gabriel Ravier via Gcc-help wrote:
>
> >This is the kind of thing that makes me wonder why there isn't some kind
> >of `__builtin_unreachable_do_not_optimize()` builtin that allows one to
> >mark places in code that should never be reached and should thus be warned
> >about if such a thing happens while at the same time never doing any
> >optimization on the basis of the presence of the call.
>
> -fsanitize=unreachable -fsanitize=null and others prevent the kind of
> optimization you are worried about.
Or even just __builtin_trap(), or abort(), or similar. Just a printf()
thing if you really want to just warn.
"Never doing any optimisation" based on <anything> is of course not a
reasonable expectation; but you *can* ask for reachable code not to be
optimised away. This is the default, just don't mark reachable code as
unreachable :-)
Segher
next prev parent reply other threads:[~2023-02-20 11:29 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-02-09 13:26 Jonny Grant
2023-02-09 14:56 ` Jonathan Wakely
2023-02-09 16:30 ` Xi Ruoyao
2023-02-09 17:52 ` Jonathan Wakely
2023-02-10 21:30 ` Jonny Grant
2023-02-10 22:03 ` Jonathan Wakely
2023-02-10 22:38 ` Jonny Grant
2023-02-11 0:32 ` Jonathan Wakely
2023-02-13 22:02 ` Jonny Grant
2023-02-19 20:43 ` Jonny Grant
2023-02-19 21:33 ` Jonny Grant
2023-02-20 10:26 ` Xi Ruoyao
2023-02-20 10:37 ` Jonathan Wakely
2023-02-20 10:54 ` Xi Ruoyao
2023-02-20 11:10 ` Gabriel Ravier
2023-02-20 11:18 ` Marc Glisse
2023-02-20 11:28 ` Segher Boessenkool [this message]
2023-02-20 12:00 ` Jonny Grant
2023-02-20 14:50 ` Gabriel Ravier
2023-02-20 11:44 ` Jonny Grant
2023-02-21 15:02 ` Jonny Grant
2023-02-20 11:38 ` Jonny Grant
2023-02-20 11:30 ` Jonny Grant
2023-02-20 12:59 ` Xi Ruoyao
2023-02-20 13:44 ` Jonathan Wakely
2023-02-20 19:21 ` Jonny Grant
2023-02-20 19:35 ` Jonathan Wakely
2023-02-20 19:39 ` Jonny Grant
2023-02-22 20:27 ` Jonny Grant
2023-02-21 15:04 ` Jonny Grant
2023-02-21 22:48 ` Jonny Grant
2023-03-04 15:00 ` Jonny Grant
2023-02-20 11:25 ` Jonny Grant
2023-03-12 22:10 ` Jonny Grant
2023-03-13 10:10 ` Jonathan Wakely
2023-03-13 19:55 ` Jonny Grant
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