Borrowed from Debian to make atomic detection easier

From: Debian MySQL Maintainers <pkg-mysql-maint@lists.alioth.debian.org>
Date: Thu, 10 Aug 2017 20:40:29 +0200
Subject: c11_atomics

---
 configure.cmake               | 23 +++++++++++++++++++++--
 include/atomic/gcc_builtins.h | 15 +++++++++++++++
 include/atomic/nolock.h       |  4 ++--
 mysys/CMakeLists.txt          |  4 ++++
 sql/CMakeLists.txt            |  4 ++++
 5 files changed, 46 insertions(+), 4 deletions(-)

diff --git a/configure.cmake b/configure.cmake
index 0057c7f..43ad114 100644
--- a/configure.cmake
+++ b/configure.cmake
@@ -128,7 +128,7 @@ IF(UNIX)
   ENDIF()
   FIND_PACKAGE(Threads)
 
-  SET(CMAKE_REQUIRED_LIBRARIES 
+  LIST(APPEND CMAKE_REQUIRED_LIBRARIES
     ${LIBM} ${LIBNSL} ${LIBBIND} ${LIBCRYPT} ${LIBSOCKET} ${LIBDL} ${CMAKE_THREAD_LIBS_INIT} ${LIBRT} ${LIBEXECINFO})
   # Need explicit pthread for gcc -fsanitize=address
   IF(CMAKE_USE_PTHREADS_INIT AND CMAKE_C_FLAGS MATCHES "-fsanitize=")
@@ -1028,7 +1028,26 @@ ELSEIF(NOT WITH_ATOMIC_OPS)
     long long int *ptr= &var;
     return (int)__atomic_load_n(ptr, __ATOMIC_SEQ_CST);
   }"
-  HAVE_GCC_C11_ATOMICS)
+  HAVE_GCC_C11_ATOMICS_WITHOUT_LIBATOMIC)
+  IF(HAVE_GCC_C11_ATOMICS_WITHOUT_LIBATOMIC)
+    SET(HAVE_GCC_C11_ATOMICS True)
+  ELSE()
+    SET(OLD_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
+    LIST(APPEND CMAKE_REQUIRED_LIBRARIES "atomic")
+    CHECK_CXX_SOURCE_COMPILES("
+    int main()
+    {
+      long long int var= 1;
+      long long int *ptr= &var;
+      return (int)__atomic_load_n(ptr, __ATOMIC_SEQ_CST);
+    }"
+    HAVE_GCC_C11_ATOMICS_WITH_LIBATOMIC)
+    IF(HAVE_GCC_C11_ATOMICS_WITH_LIBATOMIC)
+      SET(HAVE_GCC_C11_ATOMICS True)
+    ELSE()
+      SET(CMAKE_REQUIRED_LIBRARIES ${OLD_CMAKE_REQUIRED_LIBRARIES})
+    ENDIF()
+  ENDIF()
 ELSE()
   MESSAGE(FATAL_ERROR "${WITH_ATOMIC_OPS} is not a valid value for WITH_ATOMIC_OPS!")
 ENDIF()
diff --git a/include/atomic/gcc_builtins.h b/include/atomic/gcc_builtins.h
index 56a0323..044be2e 100644
--- a/include/atomic/gcc_builtins.h
+++ b/include/atomic/gcc_builtins.h
@@ -16,6 +16,7 @@
    along with this program; if not, write to the Free Software
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
+#if defined (HAVE_GCC_ATOMIC_BUILTINS)
 #define make_atomic_add_body(S)                     \
   v= __sync_fetch_and_add(a, v);
 #define make_atomic_fas_body(S)                     \
@@ -26,6 +27,20 @@
   sav= __sync_val_compare_and_swap(a, cmp_val, set);\
   if (!(ret= (sav == cmp_val))) *cmp= sav
 
+#elif defined(HAVE_GCC_C11_ATOMICS)
+
+#define make_atomic_add_body(S)                     \
+  v= __atomic_fetch_add(a, v, __ATOMIC_SEQ_CST)
+#define make_atomic_fas_body(S)                     \
+  v= __atomic_exchange_n(a, v, __ATOMIC_SEQ_CST)
+#define make_atomic_cas_body(S)                     \
+  int ## S sav;                                     \
+  ret= __atomic_compare_exchange_n(a, cmp, set,     \
+                                   0,               \
+                                   __ATOMIC_SEQ_CST,\
+                                   __ATOMIC_SEQ_CST);
+#endif
+
 #ifdef MY_ATOMIC_MODE_DUMMY
 #define make_atomic_load_body(S)   ret= *a
 #define make_atomic_store_body(S)  *a= v
diff --git a/include/atomic/nolock.h b/include/atomic/nolock.h
index 2137445..2ad7d98 100644
--- a/include/atomic/nolock.h
+++ b/include/atomic/nolock.h
@@ -17,7 +17,7 @@
    Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301  USA */
 
 #if defined(__i386__) || defined(_MSC_VER) || defined(__x86_64__)   \
-    || defined(HAVE_GCC_ATOMIC_BUILTINS) \
+    || defined(HAVE_GCC_ATOMIC_BUILTINS) || defined(HAVE_GCC_C11_ATOMICS) \
     || defined(HAVE_SOLARIS_ATOMIC)
 
 #  ifdef MY_ATOMIC_MODE_DUMMY
@@ -41,7 +41,7 @@
 #  elif __GNUC__
 #    if defined(HAVE_SOLARIS_ATOMIC)
 #      include "solaris.h"
-#    elif defined(HAVE_GCC_ATOMIC_BUILTINS)
+#    elif defined(HAVE_GCC_ATOMIC_BUILTINS) || defined(HAVE_GCC_C11_ATOMICS)
 #      include "gcc_builtins.h"
 #    elif defined(__i386__) || defined(__x86_64__)
 #      include "x86-gcc.h"
diff --git a/mysys/CMakeLists.txt b/mysys/CMakeLists.txt
index eb7f75e..a9221d7 100644
--- a/mysys/CMakeLists.txt
+++ b/mysys/CMakeLists.txt
@@ -78,6 +78,10 @@ IF(HAVE_BFD_H)
   TARGET_LINK_LIBRARIES(mysys bfd)  
 ENDIF(HAVE_BFD_H)
 
+IF(HAVE_GCC_C11_ATOMICS_WITH_LIBATOMIC)
+  TARGET_LINK_LIBRARIES(mysys atomic)
+ENDIF()
+
 IF (WIN32)
   TARGET_LINK_LIBRARIES(mysys IPHLPAPI)  
 ENDIF(WIN32)
diff --git a/sql/CMakeLists.txt b/sql/CMakeLists.txt
index b4acac5..8247714 100644
--- a/sql/CMakeLists.txt
+++ b/sql/CMakeLists.txt
@@ -165,6 +165,10 @@ TARGET_LINK_LIBRARIES(sql ${MYSQLD_STATIC_PLUGIN_LIBS}
   ${SSL_LIBRARIES}
   ${LIBSYSTEMD})
 
+IF(HAVE_GCC_C11_ATOMICS_WITH_LIBATOMIC)
+  TARGET_LINK_LIBRARIES(sql atomic)
+ENDIF()
+
 IF(WIN32)
   SET(MYSQLD_SOURCE main.cc nt_servc.cc message.rc)
   TARGET_LINK_LIBRARIES(sql psapi)