2014-04-07  Richard Henderson  <rth@redhat.com>

	* common/config/aarch64/aarch64-common.c (TARGET_OPTION_INIT_STRUCT):
	Define.
	(aarch64_option_init_struct): New function.

--- gcc/common/config/aarch64/aarch64-common.c
+++ gcc/common/config/aarch64/aarch64-common.c
@@ -39,6 +39,9 @@
 #undef	TARGET_OPTION_OPTIMIZATION_TABLE
 #define TARGET_OPTION_OPTIMIZATION_TABLE aarch_option_optimization_table
 
+#undef TARGET_OPTION_INIT_STRUCT
+#define TARGET_OPTION_INIT_STRUCT aarch64_option_init_struct
+
 /* Set default optimization options.  */
 static const struct default_options aarch_option_optimization_table[] =
   {
@@ -47,6 +50,16 @@ static const struct default_options aarch_option_optimization_table[] =
     { OPT_LEVELS_NONE, 0, NULL, 0 }
   };
 
+/* Implement TARGET_OPTION_INIT_STRUCT.  */
+
+static void
+aarch64_option_init_struct (struct gcc_options *opts)
+{
+  /* By default, always emit DWARF-2 unwind info.  This allows debugging
+     without maintaining a stack frame back-chain.  */
+  opts->x_flag_asynchronous_unwind_tables = 1;
+}
+
 /* Implement TARGET_HANDLE_OPTION.
    This function handles the target specific options for CPU/target selection.