After a long break to wait for the atomic spec to settle, this completes the library part of <atomic>. It currently won't even parse as it depends on the existence of the intrinsics specified at http://libcxx.llvm.org/atomic_design_a.html. Everything has been tested using fake intrinsics which have now been removed. As the intrinsics come online, the ATOMIC_* macros will need to be adjusted to reflect which operations are lock-free. These macros will probably need to be #ifdef'd for each supported platform.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@121267 91177308-0d34-0410-b5e6-96231b3b80d8

test/atomics/atomics.fences/atomic_signal_fence.pass.cpp

@@ -0,0 +1,19 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <atomic>
+
+// void atomic_signal_fence(memory_order m);
+
+#include <atomic>
+
+int main()
+{
+    std::atomic_signal_fence(std::memory_order_seq_cst);
+}