Index: libcxx/trunk/include/memory =================================================================== --- libcxx/trunk/include/memory +++ libcxx/trunk/include/memory @@ -3681,6 +3681,39 @@ #endif // _LIBCPP_STD_VER > 14 +// NOTE: Relaxed and acq/rel atomics (for increment and decrement respectively) +// should be sufficient for thread safety. +// See https://llvm.org/bugs/show_bug.cgi?id=22803 +#if defined(__clang__) && __has_builtin(__atomic_add_fetch) \ + && defined(__ATOMIC_RELAXED) \ + && defined(__ATOMIC_ACQ_REL) +# define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT +#elif !defined(__clang__) && defined(_GNUC_VER) && _GNUC_VER >= 407 +# define _LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT +#endif + +template +inline _LIBCPP_INLINE_VISIBILITY _Tp +__libcpp_atomic_refcount_increment(_Tp& __t) _NOEXCEPT +{ +#if defined(_LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT) && !defined(_LIBCPP_HAS_NO_THREADS) + return __atomic_add_fetch(&__t, 1, __ATOMIC_RELAXED); +#else + return __t += 1; +#endif +} + +template +inline _LIBCPP_INLINE_VISIBILITY _Tp +__libcpp_atomic_refcount_decrement(_Tp& __t) _NOEXCEPT +{ +#if defined(_LIBCPP_HAS_BUILTIN_ATOMIC_SUPPORT) && !defined(_LIBCPP_HAS_NO_THREADS) + return __atomic_add_fetch(&__t, -1, __ATOMIC_ACQ_REL); +#else + return __t -= 1; +#endif +} + class _LIBCPP_EXCEPTION_ABI bad_weak_ptr : public std::exception { @@ -3717,8 +3750,23 @@ explicit __shared_count(long __refs = 0) _NOEXCEPT : __shared_owners_(__refs) {} - void __add_shared() _NOEXCEPT; - bool __release_shared() _NOEXCEPT; +#ifdef _LIBCPP_BUILDING_MEMORY + _LIBCPP_FUNC_VIS void __add_shared() _NOEXCEPT; + _LIBCPP_FUNC_VIS bool __release_shared() _NOEXCEPT; +#else + _LIBCPP_INLINE_VISIBILITY + void __add_shared() _NOEXCEPT { + __libcpp_atomic_refcount_increment(__shared_owners_); + } + _LIBCPP_INLINE_VISIBILITY + bool __release_shared() _NOEXCEPT { + if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1) { + __on_zero_shared(); + return true; + } + return false; + } +#endif _LIBCPP_INLINE_VISIBILITY long use_count() const _NOEXCEPT { return __libcpp_relaxed_load(&__shared_owners_) + 1; @@ -3739,9 +3787,25 @@ virtual ~__shared_weak_count(); public: - void __add_shared() _NOEXCEPT; - void __add_weak() _NOEXCEPT; - void __release_shared() _NOEXCEPT; +#ifdef _LIBCPP_BUILDING_MEMORY + _LIBCPP_FUNC_VIS void __add_shared() _NOEXCEPT; + _LIBCPP_FUNC_VIS void __add_weak() _NOEXCEPT; + _LIBCPP_FUNC_VIS void __release_shared() _NOEXCEPT; +#else + _LIBCPP_INLINE_VISIBILITY + void __add_shared() _NOEXCEPT { + __shared_count::__add_shared(); + } + _LIBCPP_INLINE_VISIBILITY + void __add_weak() _NOEXCEPT { + __libcpp_atomic_refcount_increment(__shared_weak_owners_); + } + _LIBCPP_INLINE_VISIBILITY + void __release_shared() _NOEXCEPT { + if (__shared_count::__release_shared()) + __release_weak(); + } +#endif void __release_weak() _NOEXCEPT; _LIBCPP_INLINE_VISIBILITY long use_count() const _NOEXCEPT {return __shared_count::use_count();} Index: libcxx/trunk/src/memory.cpp =================================================================== --- libcxx/trunk/src/memory.cpp +++ libcxx/trunk/src/memory.cpp @@ -17,28 +17,6 @@ _LIBCPP_BEGIN_NAMESPACE_STD -namespace -{ - -// NOTE: Relaxed and acq/rel atomics (for increment and decrement respectively) -// should be sufficient for thread safety. -// See https://llvm.org/bugs/show_bug.cgi?id=22803 -template -inline T -increment(T& t) _NOEXCEPT -{ - return __libcpp_atomic_add(&t, 1, _AO_Relaxed); -} - -template -inline T -decrement(T& t) _NOEXCEPT -{ - return __libcpp_atomic_add(&t, -1, _AO_Acq_Rel); -} - -} // namespace - const allocator_arg_t allocator_arg = allocator_arg_t(); bad_weak_ptr::~bad_weak_ptr() _NOEXCEPT {} @@ -53,16 +31,20 @@ { } +__shared_weak_count::~__shared_weak_count() +{ +} + void __shared_count::__add_shared() _NOEXCEPT { - increment(__shared_owners_); + __libcpp_atomic_refcount_increment(__shared_owners_); } bool __shared_count::__release_shared() _NOEXCEPT { - if (decrement(__shared_owners_) == -1) + if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1) { __on_zero_shared(); return true; @@ -70,10 +52,6 @@ return false; } -__shared_weak_count::~__shared_weak_count() -{ -} - void __shared_weak_count::__add_shared() _NOEXCEPT { @@ -83,7 +61,7 @@ void __shared_weak_count::__add_weak() _NOEXCEPT { - increment(__shared_weak_owners_); + __libcpp_atomic_refcount_increment(__shared_weak_owners_); } void @@ -124,7 +102,7 @@ //__libcpp_atomic_store(&__shared_weak_owners_, -1, _AO_Release); __on_zero_shared_weak(); } - else if (decrement(__shared_weak_owners_) == -1) + else if (__libcpp_atomic_refcount_decrement(__shared_weak_owners_) == -1) __on_zero_shared_weak(); }