binutils-gdb/gdb/tui/tui-status.h
Simon Marchi 8480a37e14 gdb: pass frames as const frame_info_ptr &
We currently pass frames to function by value, as `frame_info_ptr`.
This is somewhat expensive:

 - the size of `frame_info_ptr` is 64 bytes, which is a bit big to pass
   by value
 - the constructors and destructor link/unlink the object in the global
   `frame_info_ptr::frame_list` list.  This is an `intrusive_list`, so
   it's not so bad: it's just assigning a few points, there's no memory
   allocation as if it was `std::list`, but still it's useless to do
   that over and over.

As suggested by Tom Tromey, change many function signatures to accept
`const frame_info_ptr &` instead of `frame_info_ptr`.

Some functions reassign their `frame_info_ptr` parameter, like:

  void
  the_func (frame_info_ptr frame)
  {
    for (; frame != nullptr; frame = get_prev_frame (frame))
      {
        ...
      }
  }

I wondered what to do about them, do I leave them as-is or change them
(and need to introduce a separate local variable that can be
re-assigned).  I opted for the later for consistency.  It might not be
clear why some functions take `const frame_info_ptr &` while others take
`frame_info_ptr`.  Also, if a function took a `frame_info_ptr` because
it did re-assign its parameter, I doubt that we would think to change it
to `const frame_info_ptr &` should the implementation change such that
it doesn't need to take `frame_info_ptr` anymore.  It seems better to
have a simple rule and apply it everywhere.

Change-Id: I59d10addef687d157f82ccf4d54f5dde9a963fd0
Approved-By: Andrew Burgess <aburgess@redhat.com>
2024-02-20 10:42:25 -05:00

57 lines
1.5 KiB
C++

/* TUI status line.
Copyright (C) 1998-2024 Free Software Foundation, Inc.
Contributed by Hewlett-Packard Company.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>. */
#ifndef TUI_TUI_STATUS_H
#define TUI_TUI_STATUS_H
#include "tui/tui-data.h"
class frame_info_ptr;
/* Locator window class. */
struct tui_status_window
: public tui_nofocus_window, tui_noscroll_window, tui_oneline_window,
tui_nobox_window
{
tui_status_window () = default;
const char *name () const override
{
return STATUS_NAME;
}
void rerender () override;
private:
/* Create the status line to display as much information as we can
on this single line: target name, process number, current
function, current line, current PC, SingleKey mode. */
std::string make_status_line () const;
};
extern void tui_show_status_content (void);
extern void tui_show_frame_info (const frame_info_ptr &);
#endif /* TUI_TUI_STATUS_H */