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 3F34F386102D; Thu,  3 Jun 2021 04:52:44 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 3F34F386102D
From: "pinskia at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/78528] Recursion not optimized for structs
Date: Thu, 03 Jun 2021 04:52:44 +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: 7.0
X-Bugzilla-Keywords: missed-optimization
X-Bugzilla-Severity: enhancement
X-Bugzilla-Who: pinskia at gcc dot gnu.org
X-Bugzilla-Status: NEW
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: 
Message-ID: <bug-78528-4-YzWUcWlLri@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-78528-4@http.gcc.gnu.org/bugzilla/>
References: <bug-78528-4@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, 03 Jun 2021 04:52:49 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D78528

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
tailr1:
  D.2500 =3D strlen (_2);

  <bb 5> :
  lhs$m_value_10 =3D D.2500.m_value;
  _14 =3D lhs$m_value_10 + 1;
  D.2496.m_value =3D _14;

  <bb 6> :
  return D.2496;

For tailr on structures we only allow for structure copies and nothing else.
For an example, if we remove the + 1 part, we do get the tail recursion.  N=
ow
the question becomes is it worth the effect in doing it.

clang can handle this case because they handle structures at a lower level =
than
GCC does.=