diff options
Diffstat (limited to 'contrib/llvm-project/libcxx/src/memory.cpp')
| -rw-r--r-- | contrib/llvm-project/libcxx/src/memory.cpp | 229 |
1 files changed, 85 insertions, 144 deletions
diff --git a/contrib/llvm-project/libcxx/src/memory.cpp b/contrib/llvm-project/libcxx/src/memory.cpp index 4b2a369d89f1..7a1c283d885e 100644 --- a/contrib/llvm-project/libcxx/src/memory.cpp +++ b/contrib/llvm-project/libcxx/src/memory.cpp @@ -8,7 +8,7 @@ #include <__config> #ifdef _LIBCPP_DEPRECATED_ABI_LEGACY_LIBRARY_DEFINITIONS_FOR_INLINE_FUNCTIONS -# define _LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS +# define _LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS #endif #include <memory> @@ -27,118 +27,79 @@ _LIBCPP_BEGIN_NAMESPACE_STD bad_weak_ptr::~bad_weak_ptr() noexcept {} -const char* -bad_weak_ptr::what() const noexcept -{ - return "bad_weak_ptr"; -} +const char* bad_weak_ptr::what() const noexcept { return "bad_weak_ptr"; } -__shared_count::~__shared_count() -{ -} +__shared_count::~__shared_count() {} -__shared_weak_count::~__shared_weak_count() -{ -} +__shared_weak_count::~__shared_weak_count() {} #if defined(_LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS) -void -__shared_count::__add_shared() noexcept -{ - __libcpp_atomic_refcount_increment(__shared_owners_); -} +void __shared_count::__add_shared() noexcept { __libcpp_atomic_refcount_increment(__shared_owners_); } -bool -__shared_count::__release_shared() noexcept -{ - if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1) - { - __on_zero_shared(); - return true; - } - return false; +bool __shared_count::__release_shared() noexcept { + if (__libcpp_atomic_refcount_decrement(__shared_owners_) == -1) { + __on_zero_shared(); + return true; + } + return false; } -void -__shared_weak_count::__add_shared() noexcept -{ - __shared_count::__add_shared(); -} +void __shared_weak_count::__add_shared() noexcept { __shared_count::__add_shared(); } -void -__shared_weak_count::__add_weak() noexcept -{ - __libcpp_atomic_refcount_increment(__shared_weak_owners_); -} +void __shared_weak_count::__add_weak() noexcept { __libcpp_atomic_refcount_increment(__shared_weak_owners_); } -void -__shared_weak_count::__release_shared() noexcept -{ - if (__shared_count::__release_shared()) - __release_weak(); +void __shared_weak_count::__release_shared() noexcept { + if (__shared_count::__release_shared()) + __release_weak(); } #endif // _LIBCPP_SHARED_PTR_DEFINE_LEGACY_INLINE_FUNCTIONS -void -__shared_weak_count::__release_weak() noexcept -{ - // NOTE: The acquire load here is an optimization of the very - // common case where a shared pointer is being destructed while - // having no other contended references. - // - // BENEFIT: We avoid expensive atomic stores like XADD and STREX - // in a common case. Those instructions are slow and do nasty - // things to caches. - // - // IS THIS SAFE? Yes. During weak destruction, if we see that we - // are the last reference, we know that no-one else is accessing - // us. If someone were accessing us, then they would be doing so - // while the last shared / weak_ptr was being destructed, and - // that's undefined anyway. - // - // If we see anything other than a 0, then we have possible - // contention, and need to use an atomicrmw primitive. - // The same arguments don't apply for increment, where it is legal - // (though inadvisable) to share shared_ptr references between - // threads, and have them all get copied at once. The argument - // also doesn't apply for __release_shared, because an outstanding - // weak_ptr::lock() could read / modify the shared count. - if (__libcpp_atomic_load(&__shared_weak_owners_, _AO_Acquire) == 0) - { - // no need to do this store, because we are about - // to destroy everything. - //__libcpp_atomic_store(&__shared_weak_owners_, -1, _AO_Release); - __on_zero_shared_weak(); - } - else if (__libcpp_atomic_refcount_decrement(__shared_weak_owners_) == -1) - __on_zero_shared_weak(); -} - -__shared_weak_count* -__shared_weak_count::lock() noexcept -{ - long object_owners = __libcpp_atomic_load(&__shared_owners_); - while (object_owners != -1) - { - if (__libcpp_atomic_compare_exchange(&__shared_owners_, - &object_owners, - object_owners+1)) - return this; - } - return nullptr; -} - -const void* -__shared_weak_count::__get_deleter(const type_info&) const noexcept -{ - return nullptr; -} +void __shared_weak_count::__release_weak() noexcept { + // NOTE: The acquire load here is an optimization of the very + // common case where a shared pointer is being destructed while + // having no other contended references. + // + // BENEFIT: We avoid expensive atomic stores like XADD and STREX + // in a common case. Those instructions are slow and do nasty + // things to caches. + // + // IS THIS SAFE? Yes. During weak destruction, if we see that we + // are the last reference, we know that no-one else is accessing + // us. If someone were accessing us, then they would be doing so + // while the last shared / weak_ptr was being destructed, and + // that's undefined anyway. + // + // If we see anything other than a 0, then we have possible + // contention, and need to use an atomicrmw primitive. + // The same arguments don't apply for increment, where it is legal + // (though inadvisable) to share shared_ptr references between + // threads, and have them all get copied at once. The argument + // also doesn't apply for __release_shared, because an outstanding + // weak_ptr::lock() could read / modify the shared count. + if (__libcpp_atomic_load(&__shared_weak_owners_, _AO_Acquire) == 0) { + // no need to do this store, because we are about + // to destroy everything. + //__libcpp_atomic_store(&__shared_weak_owners_, -1, _AO_Release); + __on_zero_shared_weak(); + } else if (__libcpp_atomic_refcount_decrement(__shared_weak_owners_) == -1) + __on_zero_shared_weak(); +} + +__shared_weak_count* __shared_weak_count::lock() noexcept { + long object_owners = __libcpp_atomic_load(&__shared_owners_); + while (object_owners != -1) { + if (__libcpp_atomic_compare_exchange(&__shared_owners_, &object_owners, object_owners + 1)) + return this; + } + return nullptr; +} + +const void* __shared_weak_count::__get_deleter(const type_info&) const noexcept { return nullptr; } #if !defined(_LIBCPP_HAS_NO_THREADS) -static constexpr std::size_t __sp_mut_count = 32; -static constinit __libcpp_mutex_t mut_back[__sp_mut_count] = -{ +static constexpr std::size_t __sp_mut_count = 32; +static constinit __libcpp_mutex_t mut_back[__sp_mut_count] = { _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, @@ -146,62 +107,42 @@ static constinit __libcpp_mutex_t mut_back[__sp_mut_count] = _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, - _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER -}; + _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER, _LIBCPP_MUTEX_INITIALIZER}; -constexpr __sp_mut::__sp_mut(void* p) noexcept - : __lx_(p) -{ -} +constexpr __sp_mut::__sp_mut(void* p) noexcept : __lx_(p) {} -void -__sp_mut::lock() noexcept -{ - auto m = static_cast<__libcpp_mutex_t*>(__lx_); - __libcpp_mutex_lock(m); +void __sp_mut::lock() noexcept { + auto m = static_cast<__libcpp_mutex_t*>(__lx_); + __libcpp_mutex_lock(m); } -void -__sp_mut::unlock() noexcept -{ - __libcpp_mutex_unlock(static_cast<__libcpp_mutex_t*>(__lx_)); -} +void __sp_mut::unlock() noexcept { __libcpp_mutex_unlock(static_cast<__libcpp_mutex_t*>(__lx_)); } -__sp_mut& -__get_sp_mut(const void* p) -{ - static constinit __sp_mut muts[__sp_mut_count] = { - &mut_back[ 0], &mut_back[ 1], &mut_back[ 2], &mut_back[ 3], - &mut_back[ 4], &mut_back[ 5], &mut_back[ 6], &mut_back[ 7], - &mut_back[ 8], &mut_back[ 9], &mut_back[10], &mut_back[11], - &mut_back[12], &mut_back[13], &mut_back[14], &mut_back[15], - &mut_back[16], &mut_back[17], &mut_back[18], &mut_back[19], - &mut_back[20], &mut_back[21], &mut_back[22], &mut_back[23], - &mut_back[24], &mut_back[25], &mut_back[26], &mut_back[27], - &mut_back[28], &mut_back[29], &mut_back[30], &mut_back[31] - }; - return muts[hash<const void*>()(p) & (__sp_mut_count-1)]; +__sp_mut& __get_sp_mut(const void* p) { + static constinit __sp_mut muts[__sp_mut_count] = { + &mut_back[0], &mut_back[1], &mut_back[2], &mut_back[3], &mut_back[4], &mut_back[5], &mut_back[6], + &mut_back[7], &mut_back[8], &mut_back[9], &mut_back[10], &mut_back[11], &mut_back[12], &mut_back[13], + &mut_back[14], &mut_back[15], &mut_back[16], &mut_back[17], &mut_back[18], &mut_back[19], &mut_back[20], + &mut_back[21], &mut_back[22], &mut_back[23], &mut_back[24], &mut_back[25], &mut_back[26], &mut_back[27], + &mut_back[28], &mut_back[29], &mut_back[30], &mut_back[31]}; + return muts[hash<const void*>()(p) & (__sp_mut_count - 1)]; } #endif // !defined(_LIBCPP_HAS_NO_THREADS) -void* -align(size_t alignment, size_t size, void*& ptr, size_t& space) -{ - void* r = nullptr; - if (size <= space) - { - char* p1 = static_cast<char*>(ptr); - char* p2 = reinterpret_cast<char*>(reinterpret_cast<uintptr_t>(p1 + (alignment - 1)) & -alignment); - size_t d = static_cast<size_t>(p2 - p1); - if (d <= space - size) - { - r = p2; - ptr = r; - space -= d; - } +void* align(size_t alignment, size_t size, void*& ptr, size_t& space) { + void* r = nullptr; + if (size <= space) { + char* p1 = static_cast<char*>(ptr); + char* p2 = reinterpret_cast<char*>(reinterpret_cast<uintptr_t>(p1 + (alignment - 1)) & -alignment); + size_t d = static_cast<size_t>(p2 - p1); + if (d <= space - size) { + r = p2; + ptr = r; + space -= d; } - return r; + } + return r; } _LIBCPP_END_NAMESPACE_STD |