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 823B73848432; Thu, 29 Apr 2021 20:10:11 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 823B73848432
From: "zsojka at seznam dot cz" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug target/100342] New: [10/11 Regression] wrong code with -O2
 -fno-dse -fno-forward-propagate -mno-sse2
Date: Thu, 29 Apr 2021 20:10:11 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: target
X-Bugzilla-Version: 11.1.1
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: zsojka at seznam dot cz
X-Bugzilla-Status: UNCONFIRMED
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: bug_id short_desc product version bug_status
 keywords bug_severity priority component assigned_to reporter
 target_milestone cf_gcchost cf_gcctarget attachments.created
Message-ID: <bug-100342-4@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: Thu, 29 Apr 2021 20:10:11 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D100342

            Bug ID: 100342
           Summary: [10/11 Regression] wrong code with -O2 -fno-dse
                    -fno-forward-propagate -mno-sse2
           Product: gcc
           Version: 11.1.1
            Status: UNCONFIRMED
          Keywords: wrong-code
          Severity: normal
          Priority: P3
         Component: target
          Assignee: unassigned at gcc dot gnu.org
          Reporter: zsojka at seznam dot cz
  Target Milestone: ---
              Host: x86_64-pc-linux-gnu
            Target: x86_64-pc-linux-gnu

Created attachment 50712
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D50712&action=3Dedit
semi-reduced testcase

I am failing to further reduce the testcase. I checked the code and I think=
 the
behavior is fully defined. Also I am unable to find out what exactly goes
wrong; please close the PR if you don't want to spend time on this.

On master, it stopped failing between r12-100 (BAD) and r12-159 (OK); but it
might have been just papered over.

$ x86_64-pc-linux-gnu-gcc -O2 -fno-dse -fno-forward-propagate -mno-sse2
testcase.c -Wno-psabi
$ ./a.out=20
Aborted

$ x86_64-pc-linux-gnu-gcc -v
Using built-in specs.
COLLECT_GCC=3D/repo/gcc-11-branch/binary-latest-amd64/bin/x86_64-pc-linux-g=
nu-gcc
COLLECT_LTO_WRAPPER=3D/repo/gcc-11-branch/binary-11-branch-20210427124134-g=
fb7c736c2f1-checking-yes-rtl-df-extra-amd64/bin/../libexec/gcc/x86_64-pc-li=
nux-gnu/11.1.1/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: /repo/gcc-11-branch//configure --enable-languages=3Dc,c++
--disable-nls --enable-checking=3Dyes,rtl,df,extra --with-cloog --with-ppl
--with-isl --build=3Dx86_64-pc-linux-gnu --host=3Dx86_64-pc-linux-gnu
--target=3Dx86_64-pc-linux-gnu --with-ld=3D/usr/bin/x86_64-pc-linux-gnu-ld
--with-as=3D/usr/bin/x86_64-pc-linux-gnu-as --disable-libsanitizer
--disable-libstdcxx-pch
--prefix=3D/repo/gcc-11-branch//binary-11-branch-20210427124134-gfb7c736c2f=
1-checking-yes-rtl-df-extra-amd64
Thread model: posix
Supported LTO compression algorithms: zlib zstd
gcc version 11.1.1 20210427 (GCC)=