[PATCH] Remove frame_observer_target_changed

[Yao Qi <yao at codesourcery dot com>]

Hi,
At the bottom of valops.c:value_assign, we have code to call
reinit_frame_cache,

  /* Assigning to the stack pointer, frame pointer, and other
     (architecture and calling convention specific) registers may
     cause the frame cache to be out of date.  Assigning to memory
     also can.  We just do this on all assignments to registers or
     memory, for simplicity's sake; I doubt the slowdown matters.  */
  switch (VALUE_LVAL (toval))
    {
    case lval_memory:
    case lval_register:
    case lval_computed:

      reinit_frame_cache ();

in the switch block above, observer_notify_target_changed will be
called.

  switch (VALUE_LVAL (toval))
....
    case lval_register:
      {
...
	observer_notify_target_changed (&current_target);

However, frame_observer_target_changed is attached to 'target_changed'
observer in frame.c:_initialize_frame, which calls reinit_frame_cache.
In this path, reinit_frame_cache is called twice.  As
observer_notify_target_changed is only used in valops.c:value_assign,
so we can remove frame_observer_target_changed and don't attach to
observer 'target_changed'.  This is what this patch tries to do.

Regression tested on x86_64-linux.  OK?

gdb:

2012-09-12  Yao Qi  <yao@codesourcery.com>

	* frame.c: Remove inclusion of "observer.h".
	(frame_observer_target_changed): Remove.
	(_initialize_frame): Don't call
	observer_attach_target_changed.
---
 gdb/frame.c |   11 -----------
 1 files changed, 0 insertions(+), 11 deletions(-)

diff --git a/gdb/frame.c b/gdb/frame.c
index 9ed49f6..a4dcb59 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -37,7 +37,6 @@
 #include "frame-base.h"
 #include "command.h"
 #include "gdbcmd.h"
-#include "observer.h"
 #include "objfiles.h"
 #include "exceptions.h"
 #include "gdbthread.h"
@@ -1514,14 +1513,6 @@ get_next_frame (struct frame_info *this_frame)
     return NULL;
 }
 
-/* Observer for the target_changed event.  */
-
-static void
-frame_observer_target_changed (struct target_ops *target)
-{
-  reinit_frame_cache ();
-}
-
 /* Flush the entire frame cache.  */
 
 void
@@ -2449,8 +2440,6 @@ _initialize_frame (void)
 {
   obstack_init (&frame_cache_obstack);
 
-  observer_attach_target_changed (frame_observer_target_changed);
-
   add_prefix_cmd ("backtrace", class_maintenance, set_backtrace_cmd, _("\
 Set backtrace specific variables.\n\
 Configure backtrace variables such as the backtrace limit"),
-- 
1.7.7.6