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 9EBB23858D3C; Mon, 24 Jan 2022 08:36:23 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 9EBB23858D3C
From: "ro at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug rtl-optimization/104198] New: [12 regression] ifcvf change
 breaks 64-bit SPARC bootstrap
Date: Mon, 24 Jan 2022 08:36:23 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: rtl-optimization
X-Bugzilla-Version: 12.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: ro 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 cc target_milestone
 cf_gcctarget
Message-ID: <bug-104198-4@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: Mon, 24 Jan 2022 08:36:23 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104198

            Bug ID: 104198
           Summary: [12 regression] ifcvf change breaks 64-bit SPARC
                    bootstrap
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: rtl-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: ro at gcc dot gnu.org
                CC: ebotcazou at gcc dot gnu.org, rdapp at gcc dot gnu.org
  Target Milestone: ---
            Target: sparcv9-sun-solaris2.11

Between 20220114 (89b4e316a02be9fda3b793a7be871f7c7913cd58) and 20220121
(6f45deb2aed804b185e7dabd2392bfbe14e9bb57)
64-bit Solaris/SPARC bootstrap got broken.  The issue can already be seen in
the
first C++ configure test for stage 2 libstdc++:

$ cat conftest.cpp
class Foo
{
public:
  Foo (void) { a =3D 0; }
private:
  int a;
};
$ ./xgcc -B./ -c conftest.cpp
../conftest.cpp:6:7: error: function definition does not declare parameters
    6 |   int a;
      |       ^
../conftest.cpp: In constructor =E2=80=98Foo::Foo()=E2=80=99:
../conftest.cpp:4:16: error: =E2=80=98a=E2=80=99 was not declared in this s=
cope
    4 |   Foo (void) { a =3D 0; }
      |                ^

Looks like a miscompilation and completely breaks the libstdc++ build.

A reghunt identified this patch

commit aa8cfe785953a0e87d2472311e1260cd98c605c0
Author: Robin Dapp <rdapp@linux.ibm.com>
Date:   Wed Jan 19 17:36:36 2022 +0100

    ifcvt: Try re-using CC for conditional moves.

As the culprit.

32-bit Solaris/SPARC (sparc-sun-solaris2.11) is unaffected, however.=