From 6354451c6afeb6f4aa493a440cd59c11c2be6517 Mon Sep 17 00:00:00 2001
From: Evgeniy Stepanov <eugeni.stepanov@gmail.com>
Date: Fri, 12 Sep 2014 11:08:59 +0000
Subject: [PATCH] Add CMake check for libatomic.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217666 91177308-0d34-0410-b5e6-96231b3b80d8
---
 cmake/modules/CheckAtomic.cmake       | 5 +++++
 cmake/modules/HandleLLVMOptions.cmake | 3 ---
 lib/Support/CMakeLists.txt            | 3 +++
 3 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/cmake/modules/CheckAtomic.cmake b/cmake/modules/CheckAtomic.cmake
index 0d63a82b97a..2ed48197728 100644
--- a/cmake/modules/CheckAtomic.cmake
+++ b/cmake/modules/CheckAtomic.cmake
@@ -2,6 +2,11 @@
 
 INCLUDE(CheckCXXSourceCompiles)
 
+check_library_exists(atomic __atomic_fetch_add_4 "" HAVE_LIBATOMIC)
+if (HAVE_LIBATOMIC)
+  list(APPEND CMAKE_REQUIRED_LIBRARIES "atomic")
+endif()
+
 CHECK_CXX_SOURCE_COMPILES("
 #ifdef _MSC_VER
 #include <windows.h>
diff --git a/cmake/modules/HandleLLVMOptions.cmake b/cmake/modules/HandleLLVMOptions.cmake
index 8b665d3b3c6..9b98848ae70 100644
--- a/cmake/modules/HandleLLVMOptions.cmake
+++ b/cmake/modules/HandleLLVMOptions.cmake
@@ -25,9 +25,6 @@ if(NOT LLVM_FORCE_USE_OLD_TOOLCHAIN)
       set(OLD_CMAKE_REQUIRED_FLAGS ${CMAKE_REQUIRED_FLAGS})
       set(OLD_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
       set(CMAKE_REQUIRED_FLAGS "-std=c++0x")
-      if (ANDROID)
-        set(CMAKE_REQUIRED_LIBRARIES "atomic")
-      endif()
       check_cxx_source_compiles("
 #include <atomic>
 std::atomic<float> x(0.0f);
diff --git a/lib/Support/CMakeLists.txt b/lib/Support/CMakeLists.txt
index df5caf48099..6ed5416bb7f 100644
--- a/lib/Support/CMakeLists.txt
+++ b/lib/Support/CMakeLists.txt
@@ -132,6 +132,9 @@ if( NOT MSVC )
         set(system_libs ${system_libs} ${TERMINFO_LIBS})
       endif()
     endif()
+    if( LLVM_ENABLE_THREADS AND HAVE_LIBATOMIC )
+      set(system_libs ${system_libs} atomic)
+    endif()
     if( LLVM_ENABLE_THREADS AND HAVE_LIBPTHREAD )
       set(system_libs ${system_libs} pthread)
     endif()
-- 
2.34.1