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libsupc++: try cxa_thread_atexit_impl at runtime

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g++.dg/tls/thread_local-order2.C fails when the toolchain is built for
a platform that lacks __cxa_thread_atexit_impl, even if the program is
built and run using that toolchain on a (later) platform that offers
__cxa_thread_atexit_impl.

This patch adds runtime testing for __cxa_thread_atexit_impl on select
platforms (GNU variants, for starters) that support weak symbols.


for  libstdc++-v3/ChangeLog

	PR libstdc++/112858
	* config/os/gnu-linux/os_defines.h
	(_GLIBCXX_MAY_HAVE___CXA_THREAD_ATEXIT_IMPL): Define.
	* libsupc++/atexit_thread.cc [__GXX_WEAK__ &&
	_GLIBCXX_MAY_HAVE___CXA_THREAD_ATEXIT_IMPL]
	(__cxa_thread_atexit): Add dynamic detection of
	__cxa_thread_atexit_impl.
This commit is contained in:
Alexandre Oliva
2023-12-07 00:38:14 -03:00
committed by Alexandre Oliva
parent 3b096bc439
commit 3d0f3382fa
2 changed files with 27 additions and 1 deletions
Download Patch File Download Diff File Expand all files Collapse all files

5
libstdc++-v3/config/os/gnu-linux/os_defines.h
View File

@@ -60,6 +60,11 @@
# define _GLIBCXX_HAVE_FLOAT128_MATH 1
#endif
// Enable __cxa_thread_atexit to rely on a (presumably libc-provided)
// __cxa_thread_atexit_impl, if it happens to be defined, even if
// configure couldn't find it during the build.
#define _GLIBCXX_MAY_HAVE___CXA_THREAD_ATEXIT_IMPL 1
#ifdef __linux__
// The following libpthread properties only apply to Linux, not GNU/Hurd.

23
libstdc++-v3/libsupc++/atexit_thread.cc
View File

@@ -138,11 +138,32 @@ namespace {
}
}
#if __GXX_WEAK__ && _GLIBCXX_MAY_HAVE___CXA_THREAD_ATEXIT_IMPL
extern "C"
int __attribute__ ((__weak__))
__cxa_thread_atexit_impl (void (_GLIBCXX_CDTOR_CALLABI *func) (void *),
void *arg, void *d);
#endif
// ??? We can't make it an ifunc, can we?
extern "C" int
__cxxabiv1::__cxa_thread_atexit (void (_GLIBCXX_CDTOR_CALLABI *dtor)(void *),
void *obj, void */*dso_handle*/)
void *obj, [[maybe_unused]] void *dso_handle)
_GLIBCXX_NOTHROW
{
#if __GXX_WEAK__ && _GLIBCXX_MAY_HAVE___CXA_THREAD_ATEXIT_IMPL
if (__cxa_thread_atexit_impl)
// Rely on a (presumably libc-provided) __cxa_thread_atexit_impl,
// if it happens to be defined, even if configure couldn't find it
// during the build. _GLIBCXX_MAY_HAVE___CXA_THREAD_ATEXIT_IMPL
// may be defined e.g. in os_defines.h on platforms where some
// versions of libc have a __cxa_thread_atexit_impl definition,
// but whose earlier versions didn't. This enables programs build
// by toolchains compatible with earlier libc versions to still
// benefit from a libc-provided __cxa_thread_atexit_impl.
return __cxa_thread_atexit_impl (dtor, obj, dso_handle);
#endif
// Do this initialization once.
if (__gthread_active_p ())
{