1 files changed, 61 insertions, 0 deletions
diff --git a/libcxx/src/random_shuffle.cpp b/libcxx/src/random_shuffle.cpp
new file mode 100644
index 000000000000..be2c47fa0def
--- /dev/null
+++ b/libcxx/src/random_shuffle.cpp
@@ -0,0 +1,61 @@
+//===----------------------- random_shuffle.cpp ---------------------------===//
+//
+// 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 "algorithm"
+#include "random"
+#ifndef _LIBCPP_HAS_NO_THREADS
+#   include "mutex"
+#   if defined(__ELF__) && defined(_LIBCPP_LINK_PTHREAD_LIB)
+#       pragma comment(lib, "pthread")
+#   endif
+#endif
+
+_LIBCPP_BEGIN_NAMESPACE_STD
+
+#ifndef _LIBCPP_HAS_NO_THREADS
+_LIBCPP_SAFE_STATIC static __libcpp_mutex_t __rs_mut = _LIBCPP_MUTEX_INITIALIZER;
+#endif
+unsigned __rs_default::__c_ = 0;
+
+__rs_default::__rs_default()
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    __libcpp_mutex_lock(&__rs_mut);
+#endif
+    __c_ = 1;
+}
+
+__rs_default::__rs_default(const __rs_default&)
+{
+    ++__c_;
+}
+
+__rs_default::~__rs_default()
+{
+#ifndef _LIBCPP_HAS_NO_THREADS
+    if (--__c_ == 0)
+       __libcpp_mutex_unlock(&__rs_mut);
+#else
+    --__c_;
+#endif
+}
+
+__rs_default::result_type
+__rs_default::operator()()
+{
+    static mt19937 __rs_g;
+    return __rs_g();
+}
+
+__rs_default
+__rs_get()
+{
+    return __rs_default();
+}
+
+_LIBCPP_END_NAMESPACE_STD