Align stack of all threads created by libhb

This is a preemptive measure to prevent any future crashes in SSE code
that requires 16 byte stack alignment.

git-svn-id: svn://localhost/HandBrake/trunk@4358 b64f7644-9d1e-0410-96f1-a4d463321fa5

libhb/common.h

@@ -18,6 +18,17 @@
 #include <sys/stat.h>
 #include <dirent.h>
 
+/*
+ * It seems WinXP doesn't align the stack of new threads to 16 bytes.
+ * To prevent crashes in SSE functions, we need to force stack alignement
+ * of new threads.
+ */
+#if defined( __GNUC__ ) && (defined( _WIN32 ) || defined( __MINGW32__ ))
+#    define attribute_align_thread __attribute__((force_align_arg_pointer))
+#else
+#    define attribute_align_thread
+#endif
+
 #if defined( __GNUC__ ) && !(defined( _WIN32 ) || defined( __MINGW32__ ))
 #   define HB_WPRINTF(s,v) __attribute__((format(printf,s,v)))
 #else

libhb/ports.c

@@ -342,7 +342,7 @@ static uint64_t hb_thread_to_integer( const hb_thread_t* t )
  *  + Get informed when the thread exits, so we know whether
  *    hb_thread_close() will block or not.
  ***********************************************************************/
-static void hb_thread_func( void * _t )
+static void attribute_align_thread hb_thread_func( void * _t )
 {
     hb_thread_t * t = (hb_thread_t *) _t;