re-enabled gcc builtin atomic operations and added a proper ./configure check

1 files changed, 9 insertions, 9 deletions

diff --git a/runtime/atomic.h b/runtime/atomic.h
index 430ae7f0..d6811628 100644
--- a/runtime/atomic.h
+++ b/runtime/atomic.h
@@ -1,6 +1,6 @@
 /* This header supplies atomic operations. So far, we rely on GCC's
- * atomic builtins. I have no idea if we can check them via autotools,
- * but I am making the necessary provisioning to live without them if
+ * atomic builtins. During configure, we check if atomic operatons are
+ * available. If they are not, I am making the necessary provisioning to live without them if
  * they are not available. Please note that you should only use the macros
  * here if you think you can actually live WITHOUT an explicit atomic operation,
  * because in the non-presence of them, we simply do it without atomicitiy.
@@ -36,16 +36,16 @@
 #ifndef INCLUDED_ATOMIC_H
 #define INCLUDED_ATOMIC_H
 
-/* set the following to 1 if we have atomic operations (and #undef it otherwise) */
-/* #define DO_HAVE_ATOMICS 1 */
 /* for this release, we disable atomic calls because there seem to be some
  * portability problems and we can not fix that without destabilizing the build.
  * They simply came in too late. -- rgerhards, 2008-04-02
  */
-/* make sure they are not used!
-#define ATOMIC_INC(data) ((void) __sync_fetch_and_add(&data, 1))
-#define ATOMIC_DEC_AND_FETCH(data) __sync_sub_and_fetch(&data, 1)
-*/
-#define ATOMIC_INC(data) (++(data))
+#ifdef HAVE_ATOMIC_BUILTINS
+#	define ATOMIC_INC(data) ((void) __sync_fetch_and_add(&data, 1))
+#	define ATOMIC_DEC_AND_FETCH(data) __sync_sub_and_fetch(&data, 1)
+#else
+#	warning "atomic builtins not available, using nul operations"
+#	define ATOMIC_INC(data) (++(data))
+#endif
 
 #endif /* #ifndef INCLUDED_ATOMIC_H */