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From: "public at timruffing dot de" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug middle-end/32667] block copy with exact overlap is expanded as memcpy
Date: Fri, 24 Nov 2023 08:19:35 +0000 [thread overview]
Message-ID: <bug-32667-4-ceqpCgjyAe@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-32667-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=32667
--- Comment #45 from Tim Ruffing <public at timruffing dot de> ---
Ha, I didn't want to move to discussion about restrict, but as a final remark:
The formal semantics of restrict are not easy to parse and understand (see
https://www.iso-9899.info/n3047.html#6.7.3.1 ). But just the sentence "If L is
used to access the value of the object X that it designates, and X is also
modified (by any means), then the following requirements apply ..." should make
clear that no requirement is made at all if no object is modified. And this is
clearly the case for `if (src==dest) return;`
Besides that, I agree with what Ralf said:
> I'm not a compiler dev nor a libc dev, I just want to make sure that my compiler and my libc use the same contract when talking to each other -- but I hope someone who is a compiler dev or a libc dev can go and actually test these hypotheses, rather than just speculating about it as has been happening so far.
next prev parent reply other threads:[~2023-11-24 8:19 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <bug-32667-4@http.gcc.gnu.org/bugzilla/>
2011-12-05 17:00 ` [Bug middle-end/32667] builtin operator= generates memcpy with overlapping memory regions lu_zero at gentoo dot org
2011-12-05 20:38 ` mans at mansr dot com
2011-12-06 8:46 ` [Bug middle-end/32667] block copy with exact overlap is expanded as memcpy rguenth at gcc dot gnu.org
2015-02-12 5:38 ` pinskia at gcc dot gnu.org
2015-02-12 9:00 ` rguenth at gcc dot gnu.org
2015-02-12 9:42 ` jakub at gcc dot gnu.org
2015-09-28 18:18 ` hugh at mimosa dot com
2021-06-09 18:50 ` public at timruffing dot de
2021-06-10 6:36 ` rguenther at suse dot de
2023-01-05 8:53 ` pinskia at gcc dot gnu.org
2023-01-05 9:19 ` nyh at math dot technion.ac.il
2023-01-06 18:48 ` lopresti at gmail dot com
2023-10-28 10:04 ` post+gcc at ralfj dot de
2023-11-21 15:57 ` bugdal at aerifal dot cx
2023-11-22 7:33 ` rguenther at suse dot de
2023-11-22 14:57 ` bugdal at aerifal dot cx
2023-11-22 15:06 ` jakub at gcc dot gnu.org
2023-11-22 19:07 ` bugdal at aerifal dot cx
2023-11-23 0:00 ` lopresti at gmail dot com
2023-11-23 7:44 ` post+gcc at ralfj dot de
2023-11-23 7:58 ` rguenth at gcc dot gnu.org
2023-11-23 8:03 ` fw at gcc dot gnu.org
2023-11-23 8:08 ` rguenther at suse dot de
2023-11-23 8:32 ` cvs-commit at gcc dot gnu.org
2023-11-23 8:39 ` jakub at gcc dot gnu.org
2023-11-23 13:54 ` bugdal at aerifal dot cx
2023-11-23 13:57 ` bugdal at aerifal dot cx
2023-11-23 14:41 ` public at timruffing dot de
2023-11-23 15:00 ` public at timruffing dot de
2023-11-23 15:01 ` sjames at gcc dot gnu.org
2023-11-23 15:29 ` post+gcc at ralfj dot de
2023-11-23 18:55 ` bugdal at aerifal dot cx
2023-11-23 19:04 ` post+gcc at ralfj dot de
2023-11-23 20:27 ` bugdal at aerifal dot cx
2023-11-24 8:19 ` public at timruffing dot de [this message]
2023-11-24 9:29 ` rguenth at gcc dot gnu.org
2023-11-24 10:09 ` jakub at gcc dot gnu.org
2023-11-24 19:08 ` post+gcc at ralfj dot de
2023-11-27 14:12 ` post+gcc at ralfj dot de
2023-11-27 23:32 ` joseph at codesourcery dot com
2023-11-28 7:17 ` post+gcc at ralfj dot de
2023-11-28 7:20 ` post+gcc at ralfj dot de
2023-11-28 10:58 ` rguenther at suse dot de
2023-11-28 11:03 ` rguenth at gcc dot gnu.org
2023-11-28 11:07 ` fw at gcc dot gnu.org
2024-01-04 12:52 ` rearnsha at gcc dot gnu.org
2024-01-04 13:22 ` bugdal at aerifal dot cx
2024-01-04 13:37 ` jakub at gcc dot gnu.org
2024-01-04 14:28 ` rearnsha at gcc dot gnu.org
2024-01-04 14:29 ` bugdal at aerifal dot cx
2024-01-04 14:41 ` rearnsha at gcc dot gnu.org
2024-01-04 14:44 ` bugdal at aerifal dot cx
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