1 files changed, 44 insertions, 0 deletions
diff --git a/cmake/FindAtomic.cmake b/cmake/FindAtomic.cmake
new file mode 100644
index 0000000000..91cee62046
--- /dev/null
+++ b/cmake/FindAtomic.cmake
@@ -0,0 +1,44 @@
+# We can't create the same interface imported target multiple times, CMake will complain if we do
+# that. This can happen if the find_package call is done in multiple different subdirectories.
+if(TARGET Atomic)
+    set(Atomic_FOUND ON)
+    return()
+endif()
+
+include(CheckCXXSourceCompiles)
+
+set (atomic_test_sources "#include <atomic>
+#include <cstdint>
+
+void test(volatile std::atomic<std::int64_t> &a)
+{
+    std::int64_t v = a.load(std::memory_order_acquire);
+    while (!a.compare_exchange_strong(v, v + 1,
+                                      std::memory_order_acq_rel,
+                                      std::memory_order_acquire)) {
+        v = a.exchange(v - 1);
+    }
+    a.store(v + 1, std::memory_order_release);
+}
+
+int main(int, char **)
+{
+    void *ptr = (void*)0xffffffc0; // any random pointer
+    test(*reinterpret_cast<std::atomic<std::int64_t> *>(ptr));
+    return 0;
+}")
+
+check_cxx_source_compiles("${atomic_test_sources}" HAVE_STDATOMIC)
+if(NOT HAVE_STDATOMIC)
+    set(_req_libraries "${CMAKE_REQUIRE_LIBRARIES}")
+    set(CMAKE_REQUIRE_LIBRARIES "atomic")
+    check_cxx_source_compiles("${atomic_test_sources}" HAVE_STDATOMIC_WITH_LIB)
+    set(CMAKE_REQUIRE_LIBRARIES "${_req_libraries}")
+endif()
+
+add_library(Atomic INTERFACE IMPORTED)
+if(HAVE_STDATOMIC_WITH_LIB)
+    target_link_libraries(Atomic INTERFACE atomic)
+endif()
+
+set(Atomic_FOUND 1)