gdbtui updates the source window for non-stopping conditional breakpoints. This unnecessarily slows things down. Repro: #include <stdlib.h> void foo (int x) { } void bar (int x) { } int main () { int i; for (i = 0; i < 1000; ++i) { if (i % 2 == 0) { foo (i); bar (i); } else { bar (i); foo (i); } sleep (1); } return 0; } bash$ gdbtui a.out (gdb) b foo if x == 42 (gdb) b bar if x == 52 (gdb) run and watch the cursor bounce back and forth between foo and bar.
I haven't tried recently, but in the past I saw this with gdb in emacs, using annotations, too. The emacs modeline would flicker between running/stopped as gdb evaluated breakpoint conditions and then continued on.
The master branch has been updated by Patrick Palka <ppalka@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=b5fca6d7284b2cd2e90efc556eb6a29a1b177476 commit b5fca6d7284b2cd2e90efc556eb6a29a1b177476 Author: Patrick Palka <patrick@parcs.ath.cx> Date: Fri Jun 26 20:38:30 2015 -0400 Be lazy about refreshing the windows in tui_show_frame_info (PR tui/13378) tui_show_frame_info is responsible for updating the visible windows following a change in frame information (that being the currently selected frame, PC, line number, etc). Currently it always redraws and refreshes each window even if frame information has not changed. This behavior is inefficient and helps contribute to the occassional flickering of the TUI as described in the mentioned PR. This patch makes tui_show_frame_info refresh the windows only if frame information has changed. Determining whether frame information has changed is done indirectly by determining whether the locator has changed. This approach is convenient and yet sensible because the locator contains all the relevant info we need to check anyway: the current PC, the line number, the name of the executable and the name of the current function. Probably only the PC is really necessary to check, but it doesn't hurt to check every field. Effectively, with this patch, consecutive calls to select_frame with the same frame/PC no longer cause TUI's frame information to be updated multiple times. gdb/ChangeLog: PR tui/13378 * tui/tui-stack.c (tui_set_locator_info): Change prototype to return an int instead of void. Return whether the locator window has changed. (tui_show_frame_info): If the locator info has not changed, then bail out early to avoid refreshing the windows.
The master branch has been updated by Patrick Palka <ppalka@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=0986c744dfecb8177de90020646090e9ed23cfe7 commit 0986c744dfecb8177de90020646090e9ed23cfe7 Author: Patrick Palka <patrick@parcs.ath.cx> Date: Tue Jun 30 13:56:49 2015 -0400 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.
Should be fixed!
The master branch has been updated by Patrick Palka <ppalka@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=bbcbf914a6ad801bfa7d4e56150217a1d53e07af commit bbcbf914a6ad801bfa7d4e56150217a1d53e07af Author: Patrick Palka <patrick@parcs.ath.cx> Date: Wed Jul 1 08:02:09 2015 -0400 TUI: Make sure to update registers if frame information has changed When I replaced TUI's frame_changed hook to fix PR tui/13378 I assumed that there's no reason to refresh register information following a call to "up", "down" or "frame". This assumption was made to fix the problem of refreshing frame information twice following a sync-execution normal stop (once in tui_normal_stop and then in tui_before_prompt) -- the second refresh removing any highlights made by the first. I was wrong about that -- GDB's snapshot of register information is per-frame, and when the frame changes, registers do too (most prominently the %rip and %rsp registers). So e.g. GDB 7.8 would highlight such register changes after invoking "up", "down" or "frame", and current GDB does not. To fix this regression, this patch adds another (sufficient) condition for refreshing register information: in tui_refresh_frame_and_register_information, always refresh register information if frame information has changed. This makes register information get refreshed following a call to "up", "down" or "frame" while still avoiding the "double refresh" issue following a normal stop. This condition may seem to obsolete the existing registers_too_p parameter, but it does not: following a normal stop, it is possible that registers may have changed while frame information had not. We could be on the exact same PC with different register values. The new condition would not catch such a case, but the registers_too_p condition will. So both conditions seem necessary (and either one is sufficient). gdb/ChangeLog: * tui/tui-hooks.c (tui_refresh_frame_and_register_information): Update commentary. Always refresh the registers when frame information has changed. * tui/tui-stack.c (tui_show_frame_info): Update commentary. Change return type to int. Return 1 if frame information has changed, 1 otherwise. (tui_before_prompt): Update commentary. * tui/tui-stack.h (tui_show_frame_info): Change return type to int.