Patchwork PATCH to libstdc++ to use __cxa_thread_atexit_impl if available

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Submitter Jason Merrill
Date Jan. 19, 2013, 5:22 p.m.
Message ID <50FAD64F.4040604@redhat.com>
Download mbox | patch
Permalink /patch/213878/
State New
Headers show

Comments

Jason Merrill - Jan. 19, 2013, 5:22 p.m.
Siddhesh has a patch to implement the thread atexit functionality in 
glibc in order to integrate better with the dynamic loader and run the 
cleanups in the correct order.  Once it's available there, this patch 
will make the copy in libsupc++ use it.  The main __cxa_thread_atexit 
function will always live in libsupc++, however, in order to maintain 
ABI compatibility between releases of libstdc++.

Does this configure change look right, or should it go in linkage.m4 
somewhere?

I think I'll hold off checking this in until Siddhesh's patch goes into 
glibc.
Jakub Jelinek - Jan. 21, 2013, 2:29 p.m.
On Sat, Jan 19, 2013 at 12:22:23PM -0500, Jason Merrill wrote:
> Siddhesh has a patch to implement the thread atexit functionality in
> glibc in order to integrate better with the dynamic loader and run
> the cleanups in the correct order.  Once it's available there, this
> patch will make the copy in libsupc++ use it.  The main
> __cxa_thread_atexit function will always live in libsupc++, however,
> in order to maintain ABI compatibility between releases of
> libstdc++.
> 
> Does this configure change look right, or should it go in linkage.m4
> somewhere?
> 
> I think I'll hold off checking this in until Siddhesh's patch goes
> into glibc.

Yeah, it should make it into glibc first (no idea why is it taking so long),
otherwise we can't be sure it won't be implemented differently in glibc.

	Jakub
Jason Merrill - Feb. 26, 2013, 4:38 a.m.
On 01/19/2013 12:22 PM, Jason Merrill wrote:
> I think I'll hold off checking this in until Siddhesh's patch goes into
> glibc.

It's in now, so I'm going to go ahead and check in my patch.

Patch

commit cba5e8c2535f5950d1c78a6c35a2f83d549f37dc
Author: Jason Merrill <jason@redhat.com>
Date:   Sat Jan 19 12:08:25 2013 -0500

    	* configure.ac: Check for __cxa_thread_atexit_impl.
    	* libsupc++/atexit_thread.cc (__cxa_thread_atexit): Just forward
    	to it if available.
    	* config.h.in, configure: Regenerate.

diff --git a/libstdc++-v3/config.h.in b/libstdc++-v3/config.h.in
index dd14b91..c14862d 100644
--- a/libstdc++-v3/config.h.in
+++ b/libstdc++-v3/config.h.in
@@ -652,6 +652,9 @@ 
 /* Define to 1 if you have the `_tanl' function. */
 #undef HAVE__TANL
 
+/* Define to 1 if you have the `__cxa_thread_atexit_impl' function. */
+#undef HAVE___CXA_THREAD_ATEXIT_IMPL
+
 /* Define as const if the declaration of iconv() needs const. */
 #undef ICONV_CONST
 
diff --git a/libstdc++-v3/configure b/libstdc++-v3/configure
index a4cf5c9..f53b9cf 100755
--- a/libstdc++-v3/configure
+++ b/libstdc++-v3/configure
@@ -26584,6 +26584,18 @@  $as_echo "#define HAVE_TLS 1" >>confdefs.h
 
   fi
 
+  for ac_func in __cxa_thread_atexit_impl
+do :
+  ac_fn_c_check_func "$LINENO" "__cxa_thread_atexit_impl" "ac_cv_func___cxa_thread_atexit_impl"
+if test "x$ac_cv_func___cxa_thread_atexit_impl" = x""yes; then :
+  cat >>confdefs.h <<_ACEOF
+#define HAVE___CXA_THREAD_ATEXIT_IMPL 1
+_ACEOF
+
+fi
+done
+
+
   # For iconv support.
 
       if test "X$prefix" = "XNONE"; then
diff --git a/libstdc++-v3/configure.ac b/libstdc++-v3/configure.ac
index 66164a2..a64fee2 100644
--- a/libstdc++-v3/configure.ac
+++ b/libstdc++-v3/configure.ac
@@ -235,6 +235,8 @@  if $GLIBCXX_IS_NATIVE; then
   # For TLS support.
   GCC_CHECK_TLS
 
+  AC_CHECK_FUNCS(__cxa_thread_atexit_impl)
+
   # For iconv support.
   AM_ICONV
 
diff --git a/libstdc++-v3/libsupc++/atexit_thread.cc b/libstdc++-v3/libsupc++/atexit_thread.cc
index 95bdcf0..ce26717 100644
--- a/libstdc++-v3/libsupc++/atexit_thread.cc
+++ b/libstdc++-v3/libsupc++/atexit_thread.cc
@@ -26,6 +26,20 @@ 
 #include <new>
 #include "bits/gthr.h"
 
+#if HAVE___CXA_THREAD_ATEXIT_IMPL
+
+extern "C" int __cxa_thread_atexit_impl (void (*func) (void *),
+					 void *arg, void *d);
+extern "C" int
+__cxxabiv1::__cxa_thread_atexit (void (*dtor)(void *),
+				 void *obj, void *dso_handle)
+  _GLIBCXX_NOTHROW
+{
+  return __cxa_thread_atexit_impl (dtor, obj, dso_handle);
+}
+
+#else /* HAVE___CXA_THREAD_ATEXIT_IMPL */
+
 namespace {
   // One element in a singly-linked stack of cleanups.
   struct elt
@@ -116,3 +130,5 @@  __cxxabiv1::__cxa_thread_atexit (void (*dtor)(void *), void *obj, void */*dso_ha
 
   return 0;
 }
+
+#endif /* HAVE___CXA_THREAD_ATEXIT_IMPL */