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 E5D9B3858C33; Wed, 19 Jul 2023 07:18:50 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E5D9B3858C33
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org;
	s=default; t=1689751130;
	bh=aiGaFUaJTd3chLw8yaxntppMeime0JLFHmkVj5foc3E=;
	h=From:To:Subject:Date:From;
	b=H8QT6JlKb5hI8x8jKMFQ5ni8mTNtjB6akAHv94KTKPXtnBuBOsajECXVYoLQcNkLJ
	 7iW7NDFFQRYUFFcRhsFgsPXazvuh8eMaM5spn+h8IVcK4xMc4VFhICeUUn9bEUyx8Q
	 UF3ZV8FHrdNlFbpr5B0TLpFFmndhJWEEdd16c6+8=
From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/110731] New: [11/12/13/14 Regression]
 Wrong-code because of wide-int division since r5-424
Date: Wed, 19 Jul 2023 07:18:50 +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: 14.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jakub 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-110731-4@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
List-Id: <gcc-bugs.sourceware.org>

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D110731

            Bug ID: 110731
           Summary: [11/12/13/14 Regression] Wrong-code because of
                    wide-int division since r5-424
           Product: gcc
           Version: 14.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: jakub at gcc dot gnu.org
  Target Milestone: ---

Since r5-424-g807e902eea17f313 (merge of wide-int) we miscompile following
testcase
(noticed it first with _BitInt(119)):

__int128
foo (void)
{
  struct S { __int128 f : 119; } s =3D { ((__int128) -18014398509481984) <<=
 64 };
  return s.f / 2;
}

int
main ()
{
  if (foo () !=3D (((__int128) -9007199254740992) << 64))
    __builtin_abort ();
}

The result of dividing (-332306998946228968225951765070086143wb - 1) by 2 is
-166153499473114484112975882535043072wb but we return
166153499473114484112975882535043072wb instead (in hex that is
0, 0xffc0000000000000 signed 119 pair divided by 2 resulting in
0, 0x0020000000000000 signed 119 pair rather than
0, 0xffe0000000000000.=