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 1829A3850426; Wed, 26 Jan 2022 16:43:54 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 1829A3850426
From: "mathieu.malaterre at gmail dot com" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug c/104248] New: armel: C11 atomics requires to be linked with
 libatomic.a explicitly
Date: Wed, 26 Jan 2022 16:43:53 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: new
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: c
X-Bugzilla-Version: 11.2.0
X-Bugzilla-Keywords: 
X-Bugzilla-Severity: normal
X-Bugzilla-Who: mathieu.malaterre at gmail dot com
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-104248-4@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: Wed, 26 Jan 2022 16:43:54 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D104248

            Bug ID: 104248
           Summary: armel: C11 atomics requires to be linked with
                    libatomic.a explicitly
           Product: gcc
           Version: 11.2.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: c
          Assignee: unassigned at gcc dot gnu.org
          Reporter: mathieu.malaterre at gmail dot com
  Target Milestone: ---

Consider the following c11 code (lib + executable):

```
::::::::::::::
foo.c
::::::::::::::
_Atomic(long long) ll;

int foo(void)
{
        ++ll;
        return 42;
}
::::::::::::::
prog.c
::::::::::::::
int foo(void);

int main(int argc, char* argv[])
{
  return foo();
}
```

On Debian armel arch, most built system will fail to compile the above. The
error reported is:

```
/usr/bin/ld: libfoo.a(foo.c.o): in function `foo':
foo.c:(.text+0x40): undefined reference to `__atomic_fetch_add_8'
```

One need to carefully pass `atomic` library on the compilation line. So if =
you
are lucky this is just:

LDFLAGS=3D-latomic ...

some other time this more complex as in this above case where a static libr=
ary
is build, thus one needs to:

```
cc -rdynamic prog.o -o prog libfoo.a -Wl,-Bstatic -latomic -Wl,-Bdynamic
```

---

I see that on some other arch (riscv), the spec file for gcc has been updat=
ed
to pass automatically (?) the proper flag: `--as-needed -latomic` [1]

Could someone from gcc/arm team please describe what is the reason for not
doing something equivalent for the spec file in armel case ? Thanks for your
time.

[1] https://github.com/riscv-collab/riscv-gcc/issues/12#issuecomment-276587=
351=