[binutils-gdb] Replace TUI's select_frame hook (PR tui/13378)

[sergiodj+buildbot at redhat dot com]

*** TEST RESULTS FOR COMMIT 0986c744dfecb8177de90020646090e9ed23cfe7 ***

Author: Patrick Palka <patrick@parcs.ath.cx>
Branch: master
Commit: 0986c744dfecb8177de90020646090e9ed23cfe7

Replace TUI's select_frame hook (PR tui/13378)
The select_frame hook is used by TUI to update TUI's frame and register
information following changes to the selected frame.  The problem with
this hook is that it gets called after every single frame change, even
if the frame change is only temporary or internal.  This is the primary
cause of flickering and slowdown when running the inferior under TUI
with conditional breakpoints set.  Internal GDB events are the source of
many calls to select_frame and these internal events are triggered
frequently, especially when a few conditional breakpoints are set.

This patch removes the select_frame hook altogether and instead makes
the frame and register information get updated in two key places (using
observers): after an inferior stops, and right before displaying a
prompt.  The latter hook covers the case when frame information must be
updated following a call to "up", "down" or "frame", and the former
covers the case when frame and register information must be updated
after a call to "continue", "step", etc. or after the inferior stops in
async execution mode.  Together these hooks should cover all the cases
when frame information ought to be refreshed (and when the relevant
windows ought to be subsequently updated).

The print_frame_info_listing hook is also effectively obsolete now, but
it still must be set while the TUI is active because its caller
print_frame_info will otherwise assume that the CLI is active, and will
print the frame informaion accordingly.  So this patch also sets the
print_frame_info_listing hook to a dummy callback, in lieu of outright
removing it yet.

Effectively, with this patch, frame/PC changes that do not immediately
precede an inferior-stop event or a prompt display event no longer cause
TUI's frame and register information to be updated.

And as a result of this change and of the previous change to
tui_show_frame_info, the TUI is much more disciplined about updating the
screen, and so the flicker as described in the PR is totally gone.

gdb/ChangeLog:

	PR tui/13378
	* frame.c (select_frame): Remove reference to
	deprecated_selected_frame_level_changed_hook.
	* frame.h (deprecated_selected_frame_level_changed_hook): Remove
	declaration.
	* stack.c (deprecated_selected_frame_level_changed_hook):
	Likewise.
	* tui/tui-hooks.c (tui_selected_frame_level_changed_hook):
	Rename to ...
	(tui_refresh_frame_and_register_information): ... this.  Bail
	out if there is no stack.  Don't update register information
	unless registers_too_p is true.
	(tui_print_frame_info_listing_hook): Rename to ...
	(tui_dummy_print_frame_info_listing_hook): ... this.
	(tui_before_prompt): New function.
	(tui_normal_stop): New function.
	(tui_before_prompt_observer): New observer.
	(tui_normal_stop_observer): New observer.
	(tui_install_hooks): Set
	deprecated_print_frame_info_listing_hook to
	tui_dummy_print_frame_info_listing_hook.  Register
	tui_before_prompt_observer to call tui_before_prompt and
	tui_normal_stop_observer to call tui_normal_stop.  Remove
	reference to deprecated_selected_frame_level_changed_hook.
	(tui_remove_hooks): Detach and unset tui_before_prompt_observer
	and tui_normal_stop_observer.  Remove reference to
	deprecated_selected_frame_level_changed_hook.