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

1 files changed, 50 insertions, 0 deletions

diff --git a/configure.ac b/configure.ac
index 8e9f7807..fea7c063 100644
--- a/configure.ac
+++ b/configure.ac
@@ -107,6 +107,56 @@ AC_TRY_COMPILE([
 	AC_MSG_RESULT(no; defined as 64)
 )
 
+# check for availability of atomic operations
+# rgerhards, 2008-09-18, added based on 
+# http://svn.apache.org/repos/asf/apr/apr/trunk/configure.in
+
+AC_CACHE_CHECK([whether the compiler provides atomic builtins], [ap_cv_atomic_builtins],
+[AC_TRY_RUN([
+int main()
+{
+    unsigned long val = 1010, tmp, *mem = &val;
+
+    if (__sync_fetch_and_add(&val, 1010) != 1010 || val != 2020)
+        return 1;
+
+    tmp = val;
+
+    if (__sync_fetch_and_sub(mem, 1010) != tmp || val != 1010)
+        return 1;
+
+    if (__sync_sub_and_fetch(&val, 1010) != 0 || val != 0)
+        return 1;
+
+    tmp = 3030;
+
+    if (__sync_val_compare_and_swap(mem, 0, tmp) != 0 || val != tmp)
+        return 1;
+
+    if (__sync_lock_test_and_set(&val, 4040) != 3030)
+        return 1;
+
+    mem = &tmp;
+
+    if (__sync_val_compare_and_swap(&mem, &tmp, &val) != &tmp)
+        return 1;
+
+    __sync_synchronize();
+
+    if (mem != &val)
+        return 1;
+
+    return 0;
+}], [ap_cv_atomic_builtins=yes], [ap_cv_atomic_builtins=no], [ap_cv_atomic_builtins=no])])
+
+if test "$ap_cv_atomic_builtins" = "yes"; then
+    AC_DEFINE(HAVE_ATOMIC_BUILTINS, 1, [Define if compiler provides atomic builtins])
+fi
+
+
+
+
+
 # Large file support
 AC_ARG_ENABLE(largefile,
         [AS_HELP_STRING([--enable-largefile],[Enable large file support @<:@default=yes@:>@])],