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diff --git a/modules/CheckAtomic.cmake b/modules/CheckAtomic.cmake
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+++ b/modules/CheckAtomic.cmake
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+#.rst:
+# CheckAtomic
+# -----------
+#
+# Check if the compiler supports std:atomic out of the box or if libatomic is
+# needed for atomic support. If it is needed libatomicis added to
+# CMAKE_REQUIRED_LIBRARIES. So after running CheckAtomic you can use
+# std:atomic.
+#
+# Since 5.XX.0.
+
+#=============================================================================
+# SPDX-FileCopyrightText: 2003-2018 University of Illinois at Urbana-Champaign.
+#
+# SPDX-License-Identifier: BSD-3-Clause
+#=============================================================================
+
+include(CheckCXXSourceCompiles)
+include(CheckLibraryExists)
+
+# Sometimes linking against libatomic is required for atomic ops, if
+# the platform doesn't support lock-free atomics.
+
+function(check_working_cxx_atomics varname)
+  set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
+  set(CMAKE_REQUIRED_FLAGS "${CMAKE_REQUIRED_FLAGS} -std=c++11")
+  check_cxx_source_compiles("
+  #include <atomic>
+  std::atomic<int> x;
+  int main() {
+    return std::atomic_is_lock_free(&x);
+  }
+  " ${varname})
+  set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
+endfunction()
+
+function(check_working_cxx_atomics64 varname)
+  set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
+  set(CMAKE_REQUIRED_FLAGS "-std=c++11 ${CMAKE_REQUIRED_FLAGS}")
+  check_cxx_source_compiles("
+  #include <atomic>
+  #include <cstdint>
+  std::atomic<uint64_t> x (0);
+  int main() {
+    uint64_t i = x.load(std::memory_order_relaxed);
+    return std::atomic_is_lock_free(&x);
+  }
+  " ${varname})
+  set(CMAKE_REQUIRED_FLAGS ${OLD_CMAKE_REQUIRED_FLAGS})
+endfunction()
+
+
+# This isn't necessary on MSVC, so avoid command-line switch annoyance
+# by only running on GCC-like hosts.
+if (LLVM_COMPILER_IS_GCC_COMPATIBLE)
+  # First check if atomics work without the library.
+  check_working_cxx_atomics(HAVE_CXX_ATOMICS_WITHOUT_LIB)
+  # If not, check if the library exists, and atomics work with it.
+  if(NOT HAVE_CXX_ATOMICS_WITHOUT_LIB)
+     check_library_exists(atomic __atomic_fetch_add_4 "" HAVE_LIBATOMIC)
+     if(HAVE_LIBATOMIC)
+        list(APPEND CMAKE_REQUIRED_LIBRARIES "atomic")
+        check_working_cxx_atomics(HAVE_CXX_ATOMICS_WITH_LIB)
+        if (NOT HAVE_CXX_ATOMICS_WITH_LIB)
+           message(FATAL_ERROR "Host compiler must support std::atomic!")
+        endif()
+     else()
+        message(FATAL_ERROR "Host compiler appears to require libatomic, but cannot find it.")
+     endif()
+  endif()
+endif()
+
+# Check for 64 bit atomic operations.
+if(MSVC)
+  set(HAVE_CXX_ATOMICS64_WITHOUT_LIB True)
+else()
+  check_working_cxx_atomics64(HAVE_CXX_ATOMICS64_WITHOUT_LIB)
+endif()
+
+# If not, check if the library exists, and atomics work with it.
+if(NOT HAVE_CXX_ATOMICS64_WITHOUT_LIB)
+  check_library_exists(atomic __atomic_load_8 "" HAVE_CXX_LIBATOMICS64)
+  if(HAVE_CXX_LIBATOMICS64)
+     list(APPEND CMAKE_REQUIRED_LIBRARIES "atomic")
+     check_working_cxx_atomics64(HAVE_CXX_ATOMICS64_WITH_LIB)
+     if (NOT HAVE_CXX_ATOMICS64_WITH_LIB)
+        message(FATAL_ERROR "Host compiler must support std::atomic!")
+     endif()
+  else()
+     message(FATAL_ERROR "Host compiler appears to require libatomic, but cannot find it.")
+  endif()
+endif()