From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <gcc-bugzilla@gcc.gnu.org>
Received: by sourceware.org (Postfix, from userid 48)
 id C93CD3857BBA; Fri,  8 Jul 2022 17:24:34 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org C93CD3857BBA
From: "rearnsha at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/106187] armhf: Miscompilation at O2 level (O0 / O1 are
 working)
Date: Fri, 08 Jul 2022 17:24:34 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 10.4.0
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: rearnsha at gcc dot gnu.org
X-Bugzilla-Status: WAITING
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P3
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: ---
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-106187-4-YmdltSYhpq@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-106187-4@http.gcc.gnu.org/bugzilla/>
References: <bug-106187-4@http.gcc.gnu.org/bugzilla/>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
X-Bugzilla-URL: http://gcc.gnu.org/bugzilla/
Auto-Submitted: auto-generated
MIME-Version: 1.0
X-BeenThere: gcc-bugs@gcc.gnu.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: Gcc-bugs mailing list <gcc-bugs.gcc.gnu.org>
List-Unsubscribe: <https://gcc.gnu.org/mailman/options/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=unsubscribe>
List-Archive: <https://gcc.gnu.org/pipermail/gcc-bugs/>
List-Post: <mailto:gcc-bugs@gcc.gnu.org>
List-Help: <mailto:gcc-bugs-request@gcc.gnu.org?subject=help>
List-Subscribe: <https://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Fri, 08 Jul 2022 17:24:34 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D106187

--- Comment #21 from Richard Earnshaw <rearnsha at gcc dot gnu.org> ---
I've finally managed to reproduce the test failure (someone has turned off
emu128 in the sources I have).

Rebuilding the failing test with -fno-strict-aliasing causes the test to pa=
ss.=20
That strongly suggests (though doesn't prove) this is a problem in the sour=
ces
with aliasing violations, rather than a bug in GCC.  Aliasing problems can =
be
very hit-and-miss because the rules give more freedom to the compiler to mo=
ve
instructions around.  Indeed disabling the instruction scheduler passes also
causes the test to pass.=