public inbox for gcc-bugs@sourceware.org
help / color / mirror / Atom feed
From: "rguenth at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/114872] [13/14/15 Regression] Miscompilation with -O2 after commit r13-8037
Date: Wed, 08 May 2024 08:27:35 +0000 [thread overview]
Message-ID: <bug-114872-4-8iaeGMwVdP@http.gcc.gnu.org/bugzilla/> (raw)
In-Reply-To: <bug-114872-4@http.gcc.gnu.org/bugzilla/>
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114872
--- Comment #24 from Richard Biener <rguenth at gcc dot gnu.org> ---
(In reply to Sergei Trofimovich from comment #23)
[...]
> Why did `gcc` generate unconditional NULL dereference here? I suspect it
> somehow inferred that `__pyx_t_6 = NULL;` in that branch, but not before
> comparison.
That's what happens if we isolate an unreachable path because of a NULL
dereference (like if exposed by jump-threading). We make the NULL
dereference volatile so it stays but DCE/DSE can cleanup code on the path
leading to it.
If you run into such path the this might suggest that jump-threading triggered
a problem with the setjmp/longjmp, so it's then likely some condition that's
evaluated in a wrong way after the longjmp, either because a dependent
value wasn't properly preserved or by GCC breaking that. Seeing stack memory
arguments used on a call in a previous comment I wondered if POSIX suggests
that even non-register variables need to be made volatile and thus whether
SRA or FRE might impose problems with code using setjmp/longjmp.
next prev parent reply other threads:[~2024-05-08 8:27 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-27 18:57 [Bug c/114872] New: Miscompilation with -O2 after commit 049ec9b981d1f4f97736061d5cf7d0ae990b57d7 arojas at archlinux dot org
2024-04-27 18:59 ` [Bug c/114872] " arojas at archlinux dot org
2024-04-27 19:03 ` pinskia at gcc dot gnu.org
2024-04-27 19:05 ` pinskia at gcc dot gnu.org
2024-04-27 19:06 ` arojas at archlinux dot org
2024-04-27 20:00 ` [Bug tree-optimization/114872] [13/14/15 Regression] Miscompilation with -O2 after commit r13-8037 pinskia at gcc dot gnu.org
2024-04-29 15:53 ` sjames at gcc dot gnu.org
2024-04-29 16:00 ` jakub at gcc dot gnu.org
2024-04-29 20:05 ` arojas at archlinux dot org
2024-05-01 1:00 ` sjames at gcc dot gnu.org
2024-05-01 1:01 ` sjames at gcc dot gnu.org
2024-05-01 1:01 ` sjames at gcc dot gnu.org
2024-05-01 1:03 ` sjames at gcc dot gnu.org
2024-05-03 11:07 ` dima.pasechnik at cs dot ox.ac.uk
2024-05-03 11:26 ` dima.pasechnik at cs dot ox.ac.uk
2024-05-06 13:53 ` slyfox at gcc dot gnu.org
2024-05-06 17:29 ` jakub at gcc dot gnu.org
2024-05-06 17:59 ` jakub at gcc dot gnu.org
2024-05-06 21:41 ` slyfox at gcc dot gnu.org
2024-05-06 22:08 ` slyfox at gcc dot gnu.org
2024-05-06 22:45 ` dima.pasechnik at cs dot ox.ac.uk
2024-05-07 10:45 ` jakub at gcc dot gnu.org
2024-05-07 11:05 ` slyfox at gcc dot gnu.org
2024-05-07 22:13 ` slyfox at gcc dot gnu.org
2024-05-08 8:18 ` slyfox at gcc dot gnu.org
2024-05-08 8:27 ` rguenth at gcc dot gnu.org [this message]
2024-05-08 18:10 ` slyfox at gcc dot gnu.org
2024-05-08 19:17 ` dima.pasechnik at cs dot ox.ac.uk
2024-05-08 19:35 ` pinskia at gcc dot gnu.org
2024-05-08 19:58 ` jakub at gcc dot gnu.org
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=bug-114872-4-8iaeGMwVdP@http.gcc.gnu.org/bugzilla/ \
--to=gcc-bugzilla@gcc.gnu.org \
--cc=gcc-bugs@gcc.gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).