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From: "rguenther at suse dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c++/97474] [8/9/10/11 Regression] produces wrong code with references to another field
Date: Tue, 26 Jan 2021 08:29:44 +0000 [thread overview]
Message-ID: <bug-97474-4-K52vdBgYCQ@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-97474-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97474
--- Comment #13 from rguenther at suse dot de <rguenther at suse dot de> ---
On Mon, 25 Jan 2021, jason at gcc dot gnu.org wrote:
> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=97474
>
> --- Comment #12 from Jason Merrill <jason at gcc dot gnu.org> ---
> Yeah, adding restrict there is just wrong; the constructor is called outside
> the function, and could e.g. stash a pointer to the object in a global
> variable. What we actually want is to treat this reference parameter like a
> value parameter. Is that information actually useful to the optimizers?
It's a layout hint PTA can use but without restricting who can point
to said object it's not going to affect precision much (in fact I'd
have to double check that giving hinting a wrong object size by
passing the base "value" of a derived class object won't cause issues).
ISTR we've explored keying on REFERENCE_TYPE only (for said layout hint)
in the past.
next prev parent reply other threads:[~2021-01-26 8:29 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-17 20:42 [Bug c++/97474] New: Regression: optimization produces wrong code sfranzen85 at hotmail dot com
2020-10-17 21:21 ` [Bug c++/97474] " pinskia at gcc dot gnu.org
2020-10-17 21:31 ` [Bug tree-optimization/97474] [8/9/10/11 Regression] produces wrong code with references to another field pinskia at gcc dot gnu.org
2020-10-17 21:40 ` jakub at gcc dot gnu.org
2020-10-19 7:33 ` rguenth at gcc dot gnu.org
2020-10-19 7:49 ` rguenth at gcc dot gnu.org
2020-10-19 8:35 ` rguenth at gcc dot gnu.org
2020-10-19 8:36 ` rguenth at gcc dot gnu.org
2020-10-19 21:32 ` joseph at codesourcery dot com
2020-10-20 6:39 ` [Bug c++/97474] " rguenth at gcc dot gnu.org
2020-10-20 6:47 ` jakub at gcc dot gnu.org
2020-10-20 6:50 ` jakub at gcc dot gnu.org
2021-01-25 16:32 ` jason at gcc dot gnu.org
2021-01-26 8:29 ` rguenther at suse dot de [this message]
2021-01-26 21:12 ` jason at gcc dot gnu.org
2021-01-26 22:11 ` cvs-commit at gcc dot gnu.org
2021-01-27 9:12 ` rguenther at suse dot de
2021-01-29 16:00 ` cvs-commit at gcc dot gnu.org
2021-02-03 15:56 ` [Bug c++/97474] [8/9 " jakub at gcc dot gnu.org
2021-05-14 9:54 ` [Bug c++/97474] [9 " jakub at gcc dot gnu.org
2021-06-01 8:18 ` rguenth at gcc dot gnu.org
2022-05-11 20:05 ` jason at gcc dot gnu.org
2022-05-11 20:13 ` pinskia at gcc dot gnu.org
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