Update libcxx to 18 Dec 3b0705827dbe711788c6b6bec3afa94205db1ce8

commit_hash:875d8582c26b8bf016af25e00ad77d9bbf081948

1 files changed, 89 insertions, 0 deletions

diff --git a/contrib/libs/cxxsupp/libcxx/src/call_once.cpp b/contrib/libs/cxxsupp/libcxx/src/call_once.cpp
new file mode 100644
index 0000000000..a4fb1c35f1
--- /dev/null
+++ b/contrib/libs/cxxsupp/libcxx/src/call_once.cpp
@@ -0,0 +1,89 @@
+//===----------------------------------------------------------------------===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <__mutex/once_flag.h>
+#include <__utility/exception_guard.h>
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+#  include <__threading_support>
+#endif
+
+#include "include/atomic_support.h"
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+// If dispatch_once_f ever handles C++ exceptions, and if one can get to it
+// without illegal macros (unexpected macros not beginning with _UpperCase or
+// __lowercase), and if it stops spinning waiting threads, then call_once should
+// call into dispatch_once_f instead of here. Relevant radar this code needs to
+// keep in sync with:  7741191.
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+static constinit __libcpp_mutex_t mut = _LIBCPP_MUTEX_INITIALIZER;
+static constinit __libcpp_condvar_t cv = _LIBCPP_CONDVAR_INITIALIZER;
+#endif
+
+#ifdef _LIBCPP_ABI_MICROSOFT
+void __call_once(volatile std::atomic<once_flag::_State_type>& flag, void* arg,
+                 void (*func)(void*))
+#else
+void __call_once(volatile once_flag::_State_type& flag, void* arg,
+                 void (*func)(void*))
+#endif
+{
+#if defined(_LIBCPP_HAS_NO_THREADS)
+
+    if (flag == once_flag::_Unset) {
+        auto guard = std::__make_exception_guard([&flag] { flag = once_flag::_Unset; });
+        flag = once_flag::_Pending;
+        func(arg);
+        flag = once_flag::_Complete;
+        guard.__complete();
+    }
+
+#else // !_LIBCPP_HAS_NO_THREADS
+
+    __libcpp_mutex_lock(&mut);
+    while (flag == once_flag::_Pending)
+        __libcpp_condvar_wait(&cv, &mut);
+    if (flag == once_flag::_Unset) {
+        auto guard = std::__make_exception_guard([&flag] {
+            __libcpp_mutex_lock(&mut);
+#ifdef _LIBCPP_ABI_MICROSOFT
+            flag.store(once_flag::_Unset);
+#else
+            __libcpp_relaxed_store(&flag, once_flag::_Unset);
+#endif
+            __libcpp_mutex_unlock(&mut);
+            __libcpp_condvar_broadcast(&cv);
+        });
+
+#ifdef _LIBCPP_ABI_MICROSOFT
+        flag.store(once_flag::_Pending, memory_order_relaxed);
+#else
+        __libcpp_relaxed_store(&flag, once_flag::_Pending);
+#endif
+        __libcpp_mutex_unlock(&mut);
+        func(arg);
+        __libcpp_mutex_lock(&mut);
+#ifdef _LIBCPP_ABI_MICROSOFT
+        flag.store(once_flag::_Complete, memory_order_release);
+#else
+        __libcpp_atomic_store(&flag, once_flag::_Complete, _AO_Release);
+#endif
+        __libcpp_mutex_unlock(&mut);
+        __libcpp_condvar_broadcast(&cv);
+        guard.__complete();
+    } else {
+        __libcpp_mutex_unlock(&mut);
+    }
+
+#endif // !_LIBCPP_HAS_NO_THREADS
+}
+
+_LIBCPP_END_NAMESPACE_STD