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 88EBA3858408; Thu,  3 Feb 2022 11:57:32 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 88EBA3858408
From: "bjorn@xn--rombobjrn-67a.se" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug lto/104366] New: Regression: infinite loop in
 add_sibling_attributes
Date: Thu, 03 Feb 2022 11:57:32 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: lto
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: bjorn@xn--rombobjrn-67a.se
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 cc target_milestone
 attachments.created
Message-ID: <bug-104366-4@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 Feb 2022 11:57:32 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104366

            Bug ID: 104366
           Summary: Regression: infinite loop in add_sibling_attributes
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: lto
          Assignee: unassigned at gcc dot gnu.org
          Reporter: bjorn@xn--rombobjrn-67a.se
                CC: marxin at gcc dot gnu.org
  Target Milestone: ---

Created attachment 52339
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=3D52339&action=3Dedit
source code for reproducing the problem

Compiling certain Ada source files with -g -flto -ffat-lto-objects triggers
what looks like infinite tail recursion in add_sibling_attributes in
dwarf2out.c. This began when GCC 12 landed in Fedora Rawhide. It does not
happen in GCC 11. Removing either -g, -flto or -ffat-lto-objects, or append=
ing
-fno-lto, works around the problem.

It seems to be specific to 64-bit arches. Builds consistently continue runn=
ing
indefinitely on all of Fedora's four 64-bit arches, but not on the two 32-b=
it
arches. I have investigated only on x86-64.

It's probably more or less specific to Ada, because otherwise it would have
caused lots and lots of failures in the recent Fedora mass rebuild.

# gcc --version
gcc (GCC) 12.0.1 20220129 (Red Hat 12.0.1-0)

# rpm -q gcc-gnat
gcc-gnat-12.0.1-0.4.fc36.x86_64

To reproduce:
gnatchop sources.ada
gcc -c -g -flto -ffat-lto-objects posix-process_environment.adb=