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 B2066387085E; Sat, 27 Feb 2021 03:21:03 +0000 (GMT)
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org B2066387085E
From: "thiago at kde dot org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug libstdc++/99277] C++2a synchronisation is inefficient in GCC 11
Date: Sat, 27 Feb 2021 03:21:03 +0000
X-Bugzilla-Reason: CC
X-Bugzilla-Type: changed
X-Bugzilla-Watch-Reason: None
X-Bugzilla-Product: gcc
X-Bugzilla-Component: libstdc++
X-Bugzilla-Version: 11.0
X-Bugzilla-Keywords: ABI
X-Bugzilla-Severity: normal
X-Bugzilla-Who: thiago at kde dot org
X-Bugzilla-Status: UNCONFIRMED
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-99277-4-ZnMcQ1rqR9@http.gcc.gnu.org/bugzilla/>
In-Reply-To: <bug-99277-4@http.gcc.gnu.org/bugzilla/>
References: <bug-99277-4@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: Sat, 27 Feb 2021 03:21:03 -0000

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D99277

--- Comment #6 from Thiago Macieira <thiago at kde dot org> ---
We don't have to delay the release. Either of these two patches give us one
more year to get it right:

--- libstdc++-v3/include/bits/atomic_wait.h
+++ libstdc++-v3/include/bits/atomic_wait.h
@@ -32,9 +32,9 @@

 #pragma GCC system_header

 #include <bits/c++config.h>
-#if defined _GLIBCXX_HAS_GTHREADS || defined _GLIBCXX_HAVE_LINUX_FUTEX
+#if defined _GLIBCXX_ENABLE_EXPERIMENTAL_ATOMIC_WAIT && (defined
_GLIBCXX_HAS_GTHREADS || defined _GLIBCXX_HAVE_LINUX_FUTEX)
 #include <bits/functional_hash.h>
 #include <bits/gthr.h>
 #include <ext/numeric_traits.h>

Or

--- libstdc++-v3/include/bits/atomic_base.h
+++ libstdc++-v3/include/bits/atomic_base.h
@@ -36,9 +36,9 @@
 #include <stdint.h>
 #include <bits/atomic_lockfree_defines.h>
 #include <bits/move.h>

-#if __cplusplus > 201703L
+#if __cplusplus > 201703L && defined _GLIBCXX_ENABLE_EXPERIMENTAL_ATOMIC_W=
AIT
 #include <bits/atomic_wait.h>
 #endif

 #ifndef _GLIBCXX_ALWAYS_INLINE=