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 D6183385802D; Mon, 23 Nov 2020 17:13:02 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org D6183385802D
From: "acoplan at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/97960] New: [8/9/10/11 Regression] Wrong code
 at -O3 since r8-6511-g3ae129323d
Date: Mon, 23 Nov 2020 17:13:02 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: acoplan at gcc dot gnu.org
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
 bug_severity priority component assigned_to reporter target_milestone
Message-ID: <bug-97960-4@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: Mon, 23 Nov 2020 17:13:02 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D97960

            Bug ID: 97960
           Summary: [8/9/10/11 Regression] Wrong code at -O3 since
                    r8-6511-g3ae129323d
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: acoplan at gcc dot gnu.org
  Target Milestone: ---

GCC miscompiles the following C++ testcase at -O3 (reproduced on both x86 a=
nd
aarch64):

const int &c(const int &d, const int &f) {
  if (d < f)
    return f;
  return d;
}

short a[575];
unsigned b[25];
unsigned char g;
int main()
{
  for (int e =3D 0; e < 23; ++e)
    a[e * 23] =3D 16137;
  for (signed char h =3D c(g, 253) + 3; h < 24; h++)
    b[h] =3D 1064739102;
  for (int e =3D 0; e < 23; ++e)
    if (a[e * 23] !=3D 16137)
      __builtin_abort();
}

When compiled with -O{0,g,s,1,2} (with or without -ftree-vectorize), the
program exits cleanly, but aborts when compiled with -O3 since the above
revision. The program also exits cleanly when compiled with clang on x86 and
aarch64 at various optimization levels.=