C++11 thread_local destructors support

This feature is specifically for the C++ compiler to offload calling
thread_local object destructors on thread program exit, to glibc.
This is to overcome the possible complication of destructors of
thread_local objects getting called after the DSO in which they're
defined is unloaded by the dynamic linker.  The DSO is marked as
'unloadable' if it has a constructed thread_local object and marked as
'unloadable' again when all the constructed thread_local objects
defined in it are destroyed.

1 files changed, 36 insertions, 0 deletions

diff --git a/stdlib/tst-tls-atexit-lib.c b/stdlib/tst-tls-atexit-lib.c
new file mode 100644
index 0000000000..aab28bb607
--- /dev/null
+++ b/stdlib/tst-tls-atexit-lib.c
@@ -0,0 +1,36 @@
+/* Verify that DSO is unloaded only if its TLS objects are destroyed - the DSO.
+   Copyright (C) 2012 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C 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
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+extern void *__dso_handle;
+
+typedef struct
+{
+  void *val;
+} A;
+
+/* We only care about the destructor.  */
+void A_dtor (void *obj)
+{
+  ((A *)obj)->val = obj;
+}
+
+void do_foo (void)
+{
+  static __thread A b;
+  __cxa_thread_atexit_impl (A_dtor, &b, __dso_handle);
+}