[libcxx] r273076 - Enable building and using atomic shared_ptr for GCC.

[Eric Fiselier via cfe-commits]

Author: ericwf
Date: Fri Jun 17 21:12:53 2016
New Revision: 273076

URL: http://llvm.org/viewvc/llvm-project?rev=273076&view=rev
Log:
Enable building and using atomic shared_ptr for GCC.

Summary:
Currently the  implementation of [util.smartptr.shared.atomic] is provided only when using Clang, and not with GCC. This is a relic of not having a GCC implementation of <atomic>, even though <atomic> isn't actually used in the implementation. This patch enables support for atomic shared_ptr functions when using GCC.

Note that this is not a header only change. Previously only Clang builds of libc++.so would provide the required symbols. There is no reason  for this restriction.
After this change both Clang and GCC builds should be binary compatible with each other WRT these symbols.


Reviewers: mclow.lists, rmaprath, EricWF

Subscribers: cfe-commits

Differential Revision: http://reviews.llvm.org/D21407

Modified:
    libcxx/trunk/include/memory
    libcxx/trunk/src/memory.cpp

Modified: libcxx/trunk/include/memory
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/include/memory?rev=273076&r1=273075&r2=273076&view=diff
==============================================================================
--- libcxx/trunk/include/memory (original)
+++ libcxx/trunk/include/memory Fri Jun 17 21:12:53 2016
@@ -5464,9 +5464,8 @@ inline _LIBCPP_INLINE_VISIBILITY
 basic_ostream<_CharT, _Traits>&
 operator<<(basic_ostream<_CharT, _Traits>& __os, shared_ptr<_Yp> const& __p);
 
-// TODO(EricWF): Enable this for both Clang and GCC. Currently it is only
-// enabled with clang.
-#if defined(_LIBCPP_HAS_C_ATOMIC_IMP) && !defined(_LIBCPP_HAS_NO_THREADS)
+
+#if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
 
 class _LIBCPP_TYPE_VIS __sp_mut
 {
@@ -5595,7 +5594,7 @@ atomic_compare_exchange_weak_explicit(sh
     return atomic_compare_exchange_weak(__p, __v, __w);
 }
 
-#endif  // defined(_LIBCPP_HAS_C_ATOMIC_IMP) && !defined(_LIBCPP_HAS_NO_THREADS)
+#endif  // !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
 
 //enum class
 struct _LIBCPP_TYPE_VIS pointer_safety

Modified: libcxx/trunk/src/memory.cpp
URL: http://llvm.org/viewvc/llvm-project/libcxx/trunk/src/memory.cpp?rev=273076&r1=273075&r2=273076&view=diff
==============================================================================
--- libcxx/trunk/src/memory.cpp (original)
+++ libcxx/trunk/src/memory.cpp Fri Jun 17 21:12:53 2016
@@ -124,7 +124,7 @@ __shared_weak_count::__get_deleter(const
 
 #endif  // _LIBCPP_NO_RTTI
 
-#if defined(_LIBCPP_HAS_C_ATOMIC_IMP) && !defined(_LIBCPP_HAS_NO_THREADS)
+#if !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
 
 static const std::size_t __sp_mut_count = 16;
 static __libcpp_mutex_t mut_back_imp[__sp_mut_count] =
@@ -177,7 +177,7 @@ __get_sp_mut(const void* p)
     return muts[hash<const void*>()(p) & (__sp_mut_count-1)];
 }
 
-#endif // defined(_LIBCPP_HAS_C_ATOMIC_IMP) && !defined(_LIBCPP_HAS_NO_THREADS)
+#endif // !defined(_LIBCPP_HAS_NO_ATOMIC_HEADER)
 
 void
 declare_reachable(void*)