frame, cfa: check unwind stop reason first

Swap the unwind stop reason check and the unwinder check to allow
non-dwarf2 frame types to fail with a recoverable error.

gdb/
2013-02-11  Jan Kratochvil  <jan.kratochvil@redhat.com>

	* dwarf2-frame.c (dwarf2_frame_cfa): Move UNWIND_UNAVAILABLE check
	earlier.

gdb/ChangeLog

@@ -1,3 +1,8 @@
+2014-01-16  Jan Kratochvil  <jan.kratochvil@redhat.com>
+
+	* dwarf2-frame.c (dwarf2_frame_cfa): Move UNWIND_UNAVAILABLE check
+	earlier.
+
 2014-01-16  Jan Kratochvil  <jan.kratochvil@redhat.com>
 
 	* frame-unwind.c: Include target.h.

gdb/dwarf2-frame.c

@@ -1512,16 +1512,16 @@ dwarf2_frame_cfa (struct frame_info *this_frame)
 {
   while (get_frame_type (this_frame) == INLINE_FRAME)
     this_frame = get_prev_frame (this_frame);
+  if (get_frame_unwind_stop_reason (this_frame) == UNWIND_UNAVAILABLE)
+    throw_error (NOT_AVAILABLE_ERROR,
+                _("can't compute CFA for this frame: "
+                  "required registers or memory are unavailable"));
   /* This restriction could be lifted if other unwinders are known to
      compute the frame base in a way compatible with the DWARF
      unwinder.  */
   if (!frame_unwinder_is (this_frame, &dwarf2_frame_unwind)
       && !frame_unwinder_is (this_frame, &dwarf2_tailcall_frame_unwind))
     error (_("can't compute CFA for this frame"));
-  if (get_frame_unwind_stop_reason (this_frame) == UNWIND_UNAVAILABLE)
-    throw_error (NOT_AVAILABLE_ERROR,
-		 _("can't compute CFA for this frame: "
-		   "required registers or memory are unavailable"));
   return get_frame_base (this_frame);
 }