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 CC494385800F; Tue,  6 Apr 2021 15:42:48 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org CC494385800F
From: "jakub at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/99927] [11 Regression] Maybe wrong code since
 r11-39-gf9e1ea10e657af9f
Date: Tue, 06 Apr 2021 15:42:48 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: tree-optimization
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: wrong-code
X-Bugzilla-Severity: normal
X-Bugzilla-Who: jakub at gcc dot gnu.org
X-Bugzilla-Status: NEW
X-Bugzilla-Resolution: 
X-Bugzilla-Priority: P1
X-Bugzilla-Assigned-To: unassigned at gcc dot gnu.org
X-Bugzilla-Target-Milestone: 11.0
X-Bugzilla-Flags: 
X-Bugzilla-Changed-Fields: 
Message-ID: <bug-99927-4-dKvnvObwmF@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-99927-4@http.gcc.gnu.org/bugzilla/>
References: <bug-99927-4@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: Tue, 06 Apr 2021 15:42:48 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99927

--- Comment #8 from Jakub Jelinek <jakub at gcc dot gnu.org> ---
distribute_notes has:
          /* If this register is set or clobbered in I3, put the note there
             unless there is one already.  */
          if (reg_set_p (XEXP (note, 0), PATTERN (i3)))
            {
              if (from_insn !=3D i3)
                break;

              if (! (REG_P (XEXP (note, 0))
                     ? find_regno_note (i3, REG_UNUSED, REGNO (XEXP (note, =
0)))
                     : find_reg_note (i3, REG_UNUSED, XEXP (note, 0))))
                place =3D i3;
            }
          /* Otherwise, if this register is used by I3, then this register
             now dies here, so we must put a REG_DEAD note here unless there
             is one already.  */
          else if (reg_referenced_p (XEXP (note, 0), PATTERN (i3))
                   && ! (REG_P (XEXP (note, 0))
                         ? find_regno_note (i3, REG_DEAD,
                                            REGNO (XEXP (note, 0)))
                         : find_reg_note (i3, REG_DEAD, XEXP (note, 0))))
            {
              PUT_REG_NOTE_KIND (note, REG_DEAD);
              place =3D i3;
            }
the if (reg_set_p (...)) is false, as flags is not set by the insn, it is u=
sed.
But the else if is clearly not true, at least when XEXP (note, 0) is set in
instructions in between i3 and i2 (or from whatever insn the notes come fro=
m).=