use atomic operations provided by the compiler if they are available (yay for gcc 4.1 users!)

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@33953 65c4cc65-6c06-0410-ace0-fbb531ad65f3

configure

@@ -26314,6 +26314,74 @@ fi
 done
 
 
+echo -n "checking for compiler atomic operations..."
+cat >conftest.$ac_ext <<_ACEOF
+/* confdefs.h.  */
+_ACEOF
+cat confdefs.h >>conftest.$ac_ext
+cat >>conftest.$ac_ext <<_ACEOF
+/* end confdefs.h.  */
+
+int
+main ()
+{
+int foo1; int foo2 = __sync_fetch_and_add(&foo1, 1);
+  ;
+  return 0;
+}
+_ACEOF
+rm -f conftest.$ac_objext
+if { (ac_try="$ac_compile"
+case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_compile") 2>conftest.er1
+  ac_status=$?
+  grep -v '^ *+' conftest.er1 >conftest.err
+  rm -f conftest.er1
+  cat conftest.err >&5
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); } &&
+	 { ac_try='test -z "$ac_c_werror_flag" || test ! -s conftest.err'
+  { (case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; } &&
+	 { ac_try='test -s conftest.$ac_objext'
+  { (case "(($ac_try" in
+  *\"* | *\`* | *\\*) ac_try_echo=\$ac_try;;
+  *) ac_try_echo=$ac_try;;
+esac
+eval "echo \"\$as_me:$LINENO: $ac_try_echo\"") >&5
+  (eval "$ac_try") 2>&5
+  ac_status=$?
+  echo "$as_me:$LINENO: \$? = $ac_status" >&5
+  (exit $ac_status); }; }; then
+  { echo "$as_me:$LINENO: result: yes" >&5
+echo "${ECHO_T}yes" >&6; }
+
+cat >>confdefs.h <<\_ACEOF
+#define HAVE_GCC_ATOMICS 1
+_ACEOF
+
+else
+  echo "$as_me: failed program was:" >&5
+sed 's/^/| /' conftest.$ac_ext >&5
+
+	{ echo "$as_me:$LINENO: result: no" >&5
+echo "${ECHO_T}no" >&6; }
+
+fi
+
+rm -f conftest.err conftest.$ac_objext conftest.$ac_ext
+
 ac_config_files="$ac_config_files build_tools/menuselect-deps makeopts"
 
 cat >confcache <<\_ACEOF

configure.ac

@@ -723,6 +723,14 @@ AC_FUNC_UTIME_NULL
 AC_FUNC_VPRINTF
 AC_CHECK_FUNCS([atexit bzero dup2 endpwent floor ftruncate getcwd gethostbyname gethostname gettimeofday inet_ntoa isascii localtime_r memchr memmove memset mkdir munmap pow putenv re_comp regcomp rint select setenv socket sqrt strcasecmp strchr strcspn strdup strerror strncasecmp strndup strnlen strrchr strsep strspn strstr strtol unsetenv utime strtoq strcasestr asprintf vasprintf])
 
+echo -n "checking for compiler atomic operations... "
+AC_COMPILE_IFELSE(
+AC_LANG_PROGRAM([], [int foo1; int foo2 = __sync_fetch_and_add(&foo1, 1);]),
+AC_MSG_RESULT(yes)
+AC_DEFINE([HAVE_GCC_ATOMICS], 1, [Define to 1 if your GCC C compiler provides atomic operations.]),
+AC_MSG_RESULT(no)
+)
+
 AC_CONFIG_FILES([build_tools/menuselect-deps makeopts])
 AC_OUTPUT
 

include/asterisk/autoconfig.h.in

@@ -94,6 +94,9 @@
 /* Define to 1 if you have the `ftruncate' function. */
 #undef HAVE_FTRUNCATE
 
+/* Define to 1 if your GCC C compiler provides atomic operations. */
+#undef HAVE_GCC_ATOMICS
+
 /* Define to 1 if you have the `getcwd' function. */
 #undef HAVE_GETCWD
 

include/asterisk/lock.h

@@ -738,12 +738,17 @@ int ast_atomic_fetchadd_int_slow(volatile int *p, int v);
 
 #include "asterisk/inline_api.h"
 
-/*! \brief Atomically add v to *pp and return * the previous value of *p.
+/*! \brief Atomically add v to *p and return * the previous value of *p.
  * This can be used to handle reference counts, and the return value
  * can be used to generate unique identifiers.
  */
 
-#if defined ( __i386__)
+#if defined(HAVE_GCC_ATOMICS)
+AST_INLINE_API(int ast_atomic_fetchadd_int(volatile int *p, int v),
+{
+	return __sync_fetch_and_add(p, v);
+})
+#elif defined ( __i386__)
 AST_INLINE_API(int ast_atomic_fetchadd_int(volatile int *p, int v),
 {
 	__asm __volatile (
@@ -763,12 +768,18 @@ AST_INLINE_API(int ast_atomic_fetchadd_int(volatile int *p, int v),
 /*! \brief decrement *p by 1 and return true if the variable has reached 0.
  * Useful e.g. to check if a refcount has reached 0.
  */
+#if defined(HAVE_GCC_ATOMICS)
+AST_INLINE_API(int ast_atomic_dec_and_test(volatile int *p),
+{
+	return __sync_sub_and_fetch(p, 1) == 0;
+})
+#else
 AST_INLINE_API(int ast_atomic_dec_and_test(volatile int *p),
 {
 	int a = ast_atomic_fetchadd_int(p, -1);
 	return a == 1; /* true if the value is 0 now (so it was 1 previously) */
-}
+})
-)
+#endif
 
 #ifndef DEBUG_CHANNEL_LOCKS
 /*! \brief Lock a channel. If DEBUG_CHANNEL_LOCKS is defined