1 files changed, 61 insertions, 0 deletions
diff --git a/m4/threads.m4 b/m4/threads.m4
new file mode 100644
index 0000000..d4ed7cd
--- /dev/null
+++ b/m4/threads.m4
@@ -0,0 +1,61 @@
+dnl file      : m4/threads.m4
+dnl author    : Boris Kolpackov <boris@codesynthesis.com>
+dnl copyright : Copyright (c) 2009-2011 Code Synthesis Tools CC
+dnl license   : GNU GPL v2; see accompanying LICENSE file
+dnl
+AC_DEFUN([THREADS],[
+
+threads_thread_keyword=no
+
+AC_ARG_ENABLE(
+  [threads],
+  AS_HELP_STRING([--disable-threads], [disable threads (enabled by default)]),
+  [AS_IF([test x"$enableval" = xno], [threads=none], [threads=check])],
+  [threads=check])
+
+# If thread support is not disabled by the user, figure out what we can use.
+#
+if test x$threads = xcheck; then
+  case $host_os in
+    windows* | mingw*)
+      case $host_os in
+        mingw*)
+          CXXFLAGS="$CXXFLAGS -mthreads"
+          ;;
+      esac
+      threads=win32
+      ;;
+    *)
+      ACX_PTHREAD
+
+      if test x$acx_pthread_ok = xyes; then
+        threads=posix
+        LIBS="$LIBS $PTHREAD_LIBS"
+        CXXFLAGS="$CXXFLAGS $PTHREAD_CXXFLAGS"
+
+        # Check if we can use the __thread keyword.
+        #
+        AC_MSG_CHECKING([for __thread keyword])
+
+        CXX_LIBTOOL_LINK_IFELSE(
+          AC_LANG_SOURCE([[
+            __thread int tls_var;
+
+            int
+            main ()
+            {
+              tls_var = 0;
+            }
+          ]]),
+          [threads_thread_keyword=yes])
+
+        AC_MSG_RESULT([$threads_thread_keyword])
+      fi
+      ;;
+  esac
+fi
+
+if test x$threads = xcheck; then
+  AC_MSG_ERROR([thread support not available; use --disable-threads to force single-threaded mode])
+fi
+])dnl