From: Jeff Law via Libc-alpha <libc-alpha@sourceware.org>
To: Aldy Hernandez <aldyh@redhat.com>,
Joseph Myers <joseph@codesourcery.com>
Cc: "MacLeod, Andrew" <amacleod@redhat.com>,
GCC Mailing List <gcc@gcc.gnu.org>,
Martin Sebor <msebor@redhat.com>,
libc-alpha@sourceware.org
Subject: Re: Failures building glibc with mainline GCC
Date: Fri, 30 Jul 2021 10:45:17 -0600 [thread overview]
Message-ID: <ff7f89db-9189-f8ce-ee1e-f64cfb01fbf3@gmail.com> (raw)
In-Reply-To: <CAGm3qMURZ-m37CpxAdkvao3Y3KbKPTmV0HYgFhsuMrkZJ17CbQ@mail.gmail.com>
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On 7/30/2021 10:19 AM, Aldy Hernandez via Libc-alpha wrote:
> There's a new jump threader in GCC which is much more aggressive, and
> may trigger latent problems with other warning passes, especially
> -Warray-bounds, -Woverflow, and -Wuninitialized.
[ ... ]
Ugh. First attempt got blocked as message was slightly too big.
I think this is pretty generic as I've seen it on multiple ports and
Joseph mentioned them as well.
With an s390-linux-gnu (not s390x!) cross compiler you should be able to
trigger:
bash-5.1# s390-linux-gnu-gcc -std=gnu99 -O2 -Wall -mlong-double-128 *.i
In file included from t.61.c:437:
In function 'from_t_61_single',
inlined from 'gconv' at ../iconv/skeleton.c:568:15:
../iconv/loop.c:440:22: warning: writing 1 byte into a region of size 0
[-Wstringop-overflow=]
In file included from t.61.c:437:
../iconv/loop.c: In function 'gconv':
../iconv/loop.c:382:17: note: at offset 2 into destination object
'bytebuf' of size 2
I don't know if it's a real failure or a false positive. I haven't even
bisected, but I suspect the new threader is the triggering change.
Ideally the threader threaded a path we hadn't previously and by some
chain of events exposed a out of bounds write that needs to be fixed.
Jeff
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next prev parent reply other threads:[~2021-07-30 16:49 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-30 15:30 Failures building glibc with mainline GCC Joseph Myers
2021-07-30 16:19 ` Aldy Hernandez via Libc-alpha
2021-07-30 16:22 ` Jeff Law via Libc-alpha
2021-07-30 16:45 ` Jeff Law via Libc-alpha [this message]
2021-07-30 17:28 ` Martin Sebor via Libc-alpha
2021-07-30 20:52 ` Joseph Myers
2021-08-02 20:20 ` Martin Sebor via Libc-alpha
2021-08-03 15:54 ` Joseph Myers
2021-08-03 16:20 ` Martin Sebor via Libc-alpha
2021-08-03 17:21 ` Joseph Myers
2021-08-03 17:39 ` Samuel Thibault via Libc-alpha
2021-08-03 22:33 ` Martin Sebor via Libc-alpha
2021-08-03 20:50 ` Segher Boessenkool
2021-08-03 21:00 ` Joseph Myers
2021-08-03 22:02 ` Segher Boessenkool
2021-08-03 22:59 ` Martin Sebor via Libc-alpha
2021-07-30 16:38 ` Joseph Myers
2021-07-30 16:43 ` Jakub Jelinek via Libc-alpha
2021-07-30 16:53 ` Martin Sebor via Libc-alpha
2021-07-30 17:02 ` Jakub Jelinek via Libc-alpha
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