Changes in v2:
* Make a global function __syncbuf_get_mutex, not an extern template
instantiation.
This patch creates a global function __syncbuf_get_mutex, gated by
_GLIBCXX_HAS_GTHREADS, replacing a static instantiated member
_S_get_mutex used in syncbuf<> construction, and makes the global
symbol visible. A static local table of 16 mutexes is shared among
all specializations of syncbuf<>, chosen on construction by a hash
of the wrapped streambuf's address.
It detaches the implementation of _S_get_mutex from the C++20 ABI.
libstdc++-v3/ChangeLog:
* include/std/syncstream: (syncbuf<>::__mutex) Remove _S_get_mutex,
use extern function instead.
* src/c++20/syncbuf.cc: Define global __syncbuf_get_mutex.
* src/c++20/Makefile.am: Mention syncbuf.cc.
* src/c++20/Makefile.in: Regenerate.
* config/abi/pre/gnu.ver: Mention mangled __syncbuf_get_mutex.
---
libstdc++-v3/config/abi/pre/gnu.ver | 3 ++
libstdc++-v3/include/std/syncstream | 19 ++++--------
libstdc++-v3/src/c++20/Makefile.am | 2 +-
libstdc++-v3/src/c++20/Makefile.in | 2 +-
libstdc++-v3/src/c++20/syncbuf.cc | 45 +++++++++++++++++++++++++++++
5 files changed, 56 insertions(+), 15 deletions(-)
create mode 100644 libstdc++-v3/src/c++20/syncbuf.cc
diff --git a/libstdc++-v3/config/abi/pre/gnu.ver
b/libstdc++-v3/config/abi/pre/gnu.ver
index e1601dc39d2..2e48241d51f 100644
--- a/libstdc++-v3/config/abi/pre/gnu.ver
+++ b/libstdc++-v3/config/abi/pre/gnu.ver
@@ -2559,6 +2559,9 @@ GLIBCXX_3.4.35 {
_ZNSt6chrono9gps_clock3nowEv;
_ZNSt6chrono9tai_clock3nowEv;
+ # mutex& __syncbuf_get_mutex(void*)
+ _ZSt19__syncbuf_get_mutexPv;
+
# __gnu_debug::_Safe_iterator_base and _Safe_sequence_base const
_ZN11__gnu_debug19_Safe_iterator_base9_M_attachEPKNS_19_Safe_sequence_baseEb;
_ZN11__gnu_debug19_Safe_iterator_base16_M_attach_singleEPKNS_19_Safe_sequence_baseEb;
diff --git a/libstdc++-v3/include/std/syncstream
b/libstdc++-v3/include/std/syncstream
index e2b5a199ec9..649756b2581 100644
--- a/libstdc++-v3/include/std/syncstream
+++ b/libstdc++-v3/include/std/syncstream
@@ -46,13 +46,17 @@
#include <bits/alloc_traits.h>
#include <bits/allocator.h>
#include <bits/functexcept.h>
-#include <bits/functional_hash.h>
#include <bits/std_mutex.h>
namespace std _GLIBCXX_VISIBILITY(default)
{
_GLIBCXX_BEGIN_NAMESPACE_VERSION
+#if _GLIBCXX_HAS_GTHREADS
+ extern mutex&
+ __syncbuf_get_mutex(void*); // in src/c++20/syncbuf.cc
+#endif
+
template<typename _CharT, typename _Traits, typename _Alloc>
class basic_syncbuf : public __syncbuf_base<_CharT, _Traits>
{
@@ -202,7 +206,7 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
mutex* _M_mtx;
__mutex(void* __t)
- : _M_mtx(__t ? &_S_get_mutex(__t) : nullptr)
+ : _M_mtx(__t ? &__syncbuf_get_mutex(__t) : nullptr)
{ }
void
@@ -220,17 +224,6 @@ _GLIBCXX_BEGIN_NAMESPACE_VERSION
{
_M_mtx->unlock();
}
-
- // FIXME: This should be put in the .so
- static mutex&
- _S_get_mutex(void* __t)
- {
- const unsigned char __mask = 0xf;
- static mutex __m[__mask + 1];
-
- auto __key = _Hash_impl::hash(__t) & __mask;
- return __m[__key];
- }
#else
__mutex(void*) { }
void swap(__mutex&&) noexcept { }
diff --git a/libstdc++-v3/src/c++20/Makefile.am
b/libstdc++-v3/src/c++20/Makefile.am
index 736558ff24a..384990aed77 100644
--- a/libstdc++-v3/src/c++20/Makefile.am
+++ b/libstdc++-v3/src/c++20/Makefile.am
@@ -36,7 +36,7 @@ else
inst_sources =
endif
-sources = tzdb.cc format.cc atomic.cc clock.cc
+sources = tzdb.cc format.cc atomic.cc clock.cc syncbuf.cc
vpath % $(top_srcdir)/src/c++20
diff --git a/libstdc++-v3/src/c++20/Makefile.in
b/libstdc++-v3/src/c++20/Makefile.in
index 3cb6d6fea5f..1e005ae3c14 100644
--- a/libstdc++-v3/src/c++20/Makefile.in
+++ b/libstdc++-v3/src/c++20/Makefile.in
@@ -432,7 +432,7 @@ headers =
@ENABLE_EXTERN_TEMPLATE_TRUE@inst_sources = \
@ENABLE_EXTERN_TEMPLATE_TRUE@ sstream-inst.cc
-sources = tzdb.cc format.cc atomic.cc clock.cc
+sources = tzdb.cc format.cc atomic.cc clock.cc syncbuf.cc
@GLIBCXX_HOSTED_FALSE@libc__20convenience_la_SOURCES =
@GLIBCXX_HOSTED_TRUE@libc__20convenience_la_SOURCES = $(sources)
$(inst_sources)
diff --git a/libstdc++-v3/src/c++20/syncbuf.cc
b/libstdc++-v3/src/c++20/syncbuf.cc
new file mode 100644
index 00000000000..150ba5e3ce4
--- /dev/null
+++ b/libstdc++-v3/src/c++20/syncbuf.cc
@@ -0,0 +1,45 @@
+// Explicit instantiation file.
+
+// Copyright (C) 2020-2025 Free Software Foundation, Inc.
+//
+// This file is part of the GNU ISO C++ Library. This library is free
+// software; you can redistribute it and/or modify it under the
+// terms of the GNU General Public License as published by the
+// Free Software Foundation; either version 3, or (at your option)
+// any later version.
+
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+
+// Under Section 7 of GPL version 3, you are granted additional
+// permissions described in the GCC Runtime Library Exception, version
+// 3.1, as published by the Free Software Foundation.
+
+// You should have received a copy of the GNU General Public License and
+// a copy of the GCC Runtime Library Exception along with this program;
+// see the files COPYING3 and COPYING.RUNTIME respectively. If not, see
+// <http://www.gnu.org/licenses/>.
+
+#include <syncstream>
+#include <bits/functional_hash.h>
+
+#if _GLIBCXX_HAS_GTHREADS
+namespace std _GLIBCXX_VISIBILITY(default)
+{
+_GLIBCXX_BEGIN_NAMESPACE_VERSION
+
+mutex&
+__syncbuf_get_mutex(void* __t)
+ {
+ const unsigned char __mask = 0xf;
+ static mutex __m[__mask + 1];
+
+ auto __key = _Hash_impl::hash(__t) & __mask;
+ return __m[__key];
+ }
+
+_GLIBCXX_END_NAMESPACE_VERSION
+}
+#endif // GTHREADS
--
2.50.1
