From 6171ecee13aea76d474919235568509835b25d98 Mon Sep 17 00:00:00 2001
From: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Date: Sat, 1 Dec 2018 10:34:01 +0100
Subject: Link against libatomic on platforms missing 64-bit atomics

Some architectures require linking against libatomic for
using 64-bit atomic operations like __atomic_load_8. Due
to a bug in gcc, linking against libatomic is not happening
automatically when using C11 code.

See: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81358

Atomics libraries are now global.

Rework of global check to include compile and link by Daniel
Black.

Tested on AIX7.1

cmake -UHAVE_ATOMIC_ADD_FETCH_WITH_LIBATOMIC  -UHAVE_ATOMIC_ADD_FETCH .
-- Running cmake version 3.16.0
-- MariaDB 10.3.25
getconf: specified variable is not valid on this system
-- Performing Test HAVE_ATOMIC_ADD_FETCH
-- Performing Test HAVE_ATOMIC_ADD_FETCH - Failed
-- Performing Test HAVE_ATOMIC_ADD_FETCH_WITH_LIBATOMIC
-- Performing Test HAVE_ATOMIC_ADD_FETCH_WITH_LIBATOMIC - Success

closes #979
---
 configure.cmake               | 26 ++++++++++++++++++++++++++
 unittest/mysys/CMakeLists.txt |  3 ++-
 2 files changed, 28 insertions(+), 1 deletion(-)

diff --git a/configure.cmake b/configure.cmake
index 75a02d2edc3..1916165b668 100644
--- a/configure.cmake
+++ b/configure.cmake
@@ -887,6 +887,32 @@ int main()
 }"
 HAVE_GCC_ATOMIC_BUILTINS)
 CHECK_CXX_SOURCE_COMPILES("
+#include <cstdint>
+int main() {
+  uint64_t x = 1;
+  __atomic_add_fetch(&x, 0, __ATOMIC_RELAXED);
+  return x;
+}
+" HAVE_ATOMIC_ADD_FETCH)
+IF(NOT HAVE_ATOMIC_ADD_FETCH)
+  SET(SAVE_CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES})
+  SET(CMAKE_REQUIRED_LIBRARIES ${CMAKE_REQUIRED_LIBRARIES} atomic)
+  CHECK_CXX_SOURCE_COMPILES("
+  #include <cstdint>
+  int main() {
+    uint64_t x = 1;
+    __atomic_add_fetch(&x, 0, __ATOMIC_RELAXED);
+    return x;
+  }
+  " HAVE_ATOMIC_ADD_FETCH_WITH_LIBATOMIC)
+  IF(HAVE_ATOMIC_ADD_FETCH_WITH_LIBATOMIC)
+    SET(LIBATOMIC atomic)
+  ELSE()
+    # revert the required libraries if unsuccessful
+    SET(CMAKE_REQUIRED_LIBRARIES ${SAVE_CMAKE_REQUIRED_LIBRARIES})
+  ENDIF()
+ENDIF()
+CHECK_CXX_SOURCE_COMPILES("
 int main()
 {
   long long int var= 1;
diff --git a/unittest/mysys/CMakeLists.txt b/unittest/mysys/CMakeLists.txt
index 984b033e7aa..4019bd3dd00 100644
--- a/unittest/mysys/CMakeLists.txt
+++ b/unittest/mysys/CMakeLists.txt
@@ -13,11 +13,12 @@
 # along with this program; if not, write to the Free Software
 # Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1335 USA
 
-MY_ADD_TESTS(bitmap base64 my_atomic my_rdtsc lf my_malloc my_getopt dynstring
+MY_ADD_TESTS(bitmap base64 my_rdtsc lf my_malloc my_getopt dynstring
              byte_order
              queues stacktrace LINK_LIBRARIES mysys)
 MY_ADD_TESTS(my_vsnprintf LINK_LIBRARIES strings mysys)
 MY_ADD_TESTS(aes LINK_LIBRARIES  mysys mysys_ssl)
+MY_ADD_TESTS(my_atomic LINK_LIBRARIES mysys ${LIBATOMIC})
 ADD_DEFINITIONS(${SSL_DEFINES})
 
 MY_ADD_TESTS(ma_dyncol LINK_LIBRARIES  mysys)
-- 
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