commit 9d547a7617fbcbc29f75ed85ff774807ddca5ce0
author Andrew Galante <spock128@gmail.com> Mon Jun 11 15:03:36 2018 -0700
committer Matt Turner <mattst88@gmail.com> Wed Jun 13 10:09:46 2018 -0700
tree 6b0535f8dacc10e73fbbea7c469fc193289a5336
parent b29b5a82a17e845e73ebef845176d9d1f44a2d00

meson: Test for __atomic_add_fetch in atomic checks

Some platforms have 64-bit __atomic_load_n but not 64-bit
__atomic_add_fetch, so test for both of them.

Bug: https://bugs.gentoo.org/655616
Reviewed-by: Matt Turner <mattst88@gmail.com>
Reviewed-by: Eric Engestrom <eric.engestrom@intel.com>
Reviewed-by: Dylan Baker <dylan@pnwbakers.com>

meson.build

diff --git a/meson.build b/meson.build
index 375751b..22e7a6d 100644
--- a/meson.build
+++ b/meson.build
@@ -835,7 +835,9 @@
                     struct {
                       uint64_t *v;
                     } x;
-                    return (int)__atomic_load_n(x.v, __ATOMIC_ACQUIRE);
+                    return (int)__atomic_load_n(x.v, __ATOMIC_ACQUIRE) &
+                           (int)__atomic_add_fetch(x.v, (uint64_t)1, __ATOMIC_ACQ_REL);
+
                   }''',
                name : 'GCC atomic builtins')
   pre_args += '-DUSE_GCC_ATOMIC_BUILTINS'
@@ -851,7 +853,8 @@
                        struct {
                          uint64_t *v;
                        } x;
-                       return (int)__atomic_load_n(x.v, __ATOMIC_ACQUIRE);
+                       return (int)__atomic_load_n(x.v, __ATOMIC_ACQUIRE) &
+                              (int)__atomic_add_fetch(x.v, (uint64_t)1, __ATOMIC_ACQ_REL);
                      }''',
                   name : 'GCC atomic builtins required -latomic')
     dep_atomic = cc.find_library('atomic')