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 5B63B3851C27; Sat, 20 Jun 2020 10:13:13 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 5B63B3851C27
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
 s=default; t=1592647993;
 bh=A7rC5xYLKJG740Divk79XC1v4y9XacYLdpmHQpXUJbA=;
 h=From:To:Subject:Date:From;
 b=tqEKCG1v4dYmjrosUdipzo87QG05nJ9wge83/ogA+aq8PlUgT9UwHtvZwcUfC/UoA
 5UifVi5qngKCcITxIzKnQDlSWZlbhVE9NmblfD3XA0Sa0dyXW+c9Htu6v9Yo201UtI
 8dWVF1bOyxRHW23uIcB0j/d8eYwrQqkbGO+pTj5U=
From: "gabravier at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/95784] New: Failure to optimize usage of
 __builtin_add_overflow with return statement properly
Date: Sat, 20 Jun 2020 10:13:13 +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: gabravier at gmail dot com
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-95784-4@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: <http://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: <http://gcc.gnu.org/mailman/listinfo/gcc-bugs>,
 <mailto:gcc-bugs-request@gcc.gnu.org?subject=subscribe>
X-List-Received-Date: Sat, 20 Jun 2020 10:13:13 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D95784

            Bug ID: 95784
           Summary: Failure to optimize usage of __builtin_add_overflow
                    with return statement properly
           Product: gcc
           Version: 11.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: gabravier at gmail dot com
  Target Milestone: ---

int f(uint8_t operand, int8_t *result)
{
    if (__builtin_add_overflow(operand, 0, result))
    {
        *result =3D 0;
        return 10213;
    }
    return 0;
}

With -O3, LLVM outputs this :

f(unsigned char, signed char*): # @f(unsigned char, signed char*)
  movsx eax, dil
  xor ecx, ecx
  cmp edi, eax
  cmovne edi, ecx
  mov byte ptr [rsi], dil
  mov eax, 10213
  cmove eax, ecx
  ret

GCC outputs this :

f(unsigned char, signed char*):
  movzx eax, dil
  movsx di, dil
  cmp ax, di
  setne dl
  mov r8d, edx
  sal r8d, 31
  sar r8d, 31
  and r8d, 10213
  test dl, dl
  mov edx, 0
  cmovne eax, edx
  mov BYTE PTR [rsi], al
  mov eax, r8d
  ret=