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gdb/mi: preserve user selected thread and frame when invoking MI commands

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Fix for PR gdb/20684.  When invoking MI commands with --thread and/or
--frame, the user selected thread and frame was not preserved:

  (gdb)
  info thread
  &"info thread\n"
  ~"  Id   Target Id                                           Frame \n"
  ~"* 1    Thread 0x7ffff7c30740 (LWP 19302) \"user-selected-c\" main () at /home/uuu/gdb/gdb/testsuite/gdb.mi/user-selected-context-sync.c:60\n"
  ~"  2    Thread 0x7ffff7c2f700 (LWP 19306) \"user-selected-c\" child_sub_function () at /home/uuu/gdb/gdb/testsuite/gdb.mi/user-selected-context-sync.c:30\n"
  ~"  3    Thread 0x7ffff742e700 (LWP 19307) \"user-selected-c\" child_sub_function () at /home/uuu/gdb/gdb/testsuite/gdb.mi/user-selected-context-sync.c:30\n"
  ^done
  (gdb)
  info frame
  &"info frame\n"
  ~"Stack level 0, frame at 0x7fffffffdf90:\n"
  ~" rip = 0x555555555207 in main (/home/uuu/gdb/gdb/testsuite/gdb.mi/user-selected-context-sync.c:60); saved rip = 0x7ffff7c5709b\n"
  ~" source language c.\n"
  ~" Arglist at 0x7fffffffdf80, args: \n"
  ~" Locals at 0x7fffffffdf80, Previous frame's sp is 0x7fffffffdf90\n"
  ~" Saved registers:\n "
  ~" rbp at 0x7fffffffdf80, rip at 0x7fffffffdf88\n"
  ^done
  (gdb)
  -stack-info-depth --thread 3
  ^done,depth="4"
  (gdb)
  info thread
  &"info thread\n"
  ~"  Id   Target Id                                           Frame \n"
  ~"  1    Thread 0x7ffff7c30740 (LWP 19302) \"user-selected-c\" main () at /home/uuu/gdb/gdb/testsuite/gdb.mi/user-selected-context-sync.c:60\n"
  ~"  2    Thread 0x7ffff7c2f700 (LWP 19306) \"user-selected-c\" child_sub_function () at /home/uuu/gdb/gdb/testsuite/gdb.mi/user-selected-context-sync.c:30\n"
  ~"* 3    Thread 0x7ffff742e700 (LWP 19307) \"user-selected-c\" child_sub_function () at /home/uuu/gdb/gdb/testsuite/gdb.mi/user-selected-context-sync.c:30\n"
  ^done
  (gdb)
  info frame
  &"info frame\n"
  ~"Stack level 0, frame at 0x7ffff742dee0:\n"
  ~" rip = 0x555555555169 in child_sub_function (/home/uuu/gdb/gdb/testsuite/gdb.mi/user-selected-context-sync.c:30); saved rip = 0x555555555188\n"
  ~" called by frame at 0x7ffff742df00\n"
  ~" source language c.\n"
  ~" Arglist at 0x7ffff742ded0, args: \n"
  ~" Locals at 0x7ffff742ded0, Previous frame's sp is 0x7ffff742dee0\n"
  ~" Saved registers:\n "
  ~" rbp at 0x7ffff742ded0, rip at 0x7ffff742ded8\n"
  ^done
  (gdb)

This caused problems for frontends that provide access to CLI because UI
may silently change the context for CLI commands (as demonstrated above).

This commit fixes the problem by restoring thread and frame in
mi_cmd_execute (). With this change, there are only two GDB/MI commands
that can change user selected context: -thread-select and -stack-select-frame.
This allows us to remove all and rather complicated logic of notifying
about user selected context change from mi_execute_command (), leaving it
to these two commands themselves to notify.

Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=20684
This commit is contained in:
Jan Vrany 2022-03-02 13:23:30 +00:00 • committed by Andrew Burgess
parent 807310c5c7
commit a9c82bc13c
4 changed files with 191 additions and 63 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

11
gdb/mi/mi-cmd-stack.c
View file

@ -36,6 +36,8 @@
#include "mi-parse.h"
#include "gdbsupport/gdb_optional.h"
#include "safe-ctype.h"
#include "inferior.h"
#include "observable.h"
enum what_to_list { locals, arguments, all };
@ -756,7 +758,16 @@ mi_cmd_stack_select_frame (const char *command, char **argv, int argc)
if (argc == 0 || argc > 1)
error (_("-stack-select-frame: Usage: FRAME_SPEC"));
ptid_t previous_ptid = inferior_ptid;
select_frame_for_mi (parse_frame_specification (argv[0]));
/* Notify if the thread has effectively changed. */
if (inferior_ptid != previous_ptid)
{
gdb::observers::user_selected_context_changed.notify
(USER_SELECTED_THREAD | USER_SELECTED_FRAME);
}
}
void

12
gdb/mi/mi-cmds.h
View file

@ -23,6 +23,7 @@
#define MI_MI_CMDS_H
#include "gdbsupport/gdb_optional.h"
#include "mi/mi-main.h"
enum print_values {
PRINT_NO_VALUES,
@ -163,6 +164,17 @@ struct mi_command
wrong. */
void invoke (struct mi_parse *parse) const;
/* Return whether this command preserves user selected context (thread
and frame). */
bool preserve_user_selected_context () const
{
/* Here we exploit the fact that if MI command is supposed to change
user context, then it should not emit change notifications. Therefore if
command does not suppress user context change notifications, then it should
preserve the context. */
return m_suppress_notification != &mi_suppress_notification.user_selected_context;
}
protected:
/* The core of command invocation, this needs to be overridden in each

74
gdb/mi/mi-main.c
View file

@ -1918,34 +1918,6 @@ mi_print_exception (const char *token, const struct gdb_exception &exception)
fputs_unfiltered ("\n", mi->raw_stdout);
}
/* Determine whether the parsed command already notifies the
user_selected_context_changed observer. */
static int
command_notifies_uscc_observer (struct mi_parse *command)
{
if (command->op == CLI_COMMAND)
{
/* CLI commands "thread" and "inferior" already send it. */
return (startswith (command->command, "thread ")
|| startswith (command->command, "inferior "));
}
else /* MI_COMMAND */
{
if (strcmp (command->command, "interpreter-exec") == 0
&& command->argc > 1)
{
/* "thread" and "inferior" again, but through -interpreter-exec. */
return (startswith (command->argv[1], "thread ")
|| startswith (command->argv[1], "inferior "));
}
else
/* -thread-select already sends it. */
return strcmp (command->command, "thread-select") == 0;
}
}
void
mi_execute_command (const char *cmd, int from_tty)
{
@ -1971,8 +1943,6 @@ mi_execute_command (const char *cmd, int from_tty)
if (command != NULL)
{
ptid_t previous_ptid = inferior_ptid;
command->token = token;
if (do_timings)
@ -2002,37 +1972,6 @@ mi_execute_command (const char *cmd, int from_tty)
bpstat_do_actions ();
if (/* The notifications are only output when the top-level
interpreter (specified on the command line) is MI. */
top_level_interpreter ()->interp_ui_out ()->is_mi_like_p ()
/* Don't try report anything if there are no threads --
the program is dead. */
&& any_thread_p ()
/* If the command already reports the thread change, no need to do it
again. */
&& !command_notifies_uscc_observer (command.get ()))
{
int report_change = 0;
if (command->thread == -1)
{
report_change = (previous_ptid != null_ptid
&& inferior_ptid != previous_ptid
&& inferior_ptid != null_ptid);
}
else if (inferior_ptid != null_ptid)
{
struct thread_info *ti = inferior_thread ();
report_change = (ti->global_num != command->thread);
}
if (report_change)
{
gdb::observers::user_selected_context_changed.notify
(USER_SELECTED_THREAD | USER_SELECTED_FRAME);
}
}
}
}
@ -2076,6 +2015,7 @@ mi_cmd_execute (struct mi_parse *parse)
set_current_program_space (inf->pspace);
}
gdb::optional<scoped_restore_current_thread> thread_saver;
if (parse->thread != -1)
{
thread_info *tp = find_thread_global_id (parse->thread);
@ -2086,9 +2026,13 @@ mi_cmd_execute (struct mi_parse *parse)
if (tp->state == THREAD_EXITED)
error (_("Thread id: %d has terminated"), parse->thread);
if (parse->cmd->preserve_user_selected_context ())
thread_saver.emplace ();
switch_to_thread (tp);
}
gdb::optional<scoped_restore_selected_frame> frame_saver;
if (parse->frame != -1)
{
struct frame_info *fid;
@ -2096,8 +2040,12 @@ mi_cmd_execute (struct mi_parse *parse)
fid = find_relative_frame (get_current_frame (), &frame);
if (frame == 0)
/* find_relative_frame was successful */
select_frame (fid);
{
if (parse->cmd->preserve_user_selected_context ())
frame_saver.emplace ();
select_frame (fid);
}
else
error (_("Invalid frame id: %d"), frame);
}

157
gdb/testsuite/gdb.mi/mi-cmd-user-context.exp Normal file
View file

@ -0,0 +1,157 @@
# Copyright 2022 Free Software Foundation, Inc.
# 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/>.
# Test that GDB/MI commands preserve user selected context when
# passed --thread and/or --frame.
load_lib mi-support.exp
standard_testfile user-selected-context-sync.c
if {[build_executable $testfile.exp $testfile ${srcfile} "debug pthreads"] == -1} {
untested "failed to compile"
return -1
}
set main_break_line [gdb_get_line_number "main break line"]
set any "\[^\r\n\]*"
mi_clean_restart $binfile
mi_create_breakpoint "$srcfile:$main_break_line" "set breakpoint in main"
mi_run_cmd
mi_expect_stop "breakpoint-hit" "main" "" $srcfile $main_break_line \
{ "" "disp=\"keep\"" } "run to breakpoint in main"
mi_gdb_test "thread" \
".*Current thread is 1.*" \
"info thread 1"
# Run -stack-info-depth in a different thread, the current thread
# should not change.
mi_gdb_test "-stack-info-depth --thread 3" \
"\\^done,depth=.*" \
"-stack-info-depth --thread 3"
mi_gdb_test "thread" \
".*Current thread is 1.*" \
"info thread 2"
# Expect GDB to switch to thread 3.
mi_gdb_test "-thread-select 3" \
"\\^done,${any}new-thread-id=\"3\"${any}" \
"-thread-select 3"
mi_gdb_test "thread" \
".*Current thread is 3.*" \
"info thread 3"
# Expect GDB to switch to thread 1.
mi_gdb_test "-thread-select --thread 2 1" \
"\\^done,${any}new-thread-id=\"1\"${any}" \
"-thread-select --thread 2 1"
mi_gdb_test "thread" \
".*Current thread is 1.*" \
"info thread 4"
# Expect GDB to switch to thread 2.
mi_gdb_test "-thread-select --thread 2 2" \
"\\^done,.*" \
"-thread-select --thread 2 2"
mi_gdb_test "thread" \
".*Current thread is 2.*" \
"info thread 5"
# Check we're in frame 0.
mi_gdb_test "frame" \
".*#0 0x.*" \
"frame 1"
# Ask about a different frame in the current thread, the current frame
# should not change.
mi_gdb_test "-stack-info-frame --thread 2 --frame 1" \
"\\^done,frame=\{level=\"1\".*" \
"-stack-info-frame 1"
mi_gdb_test "thread" \
".*Current thread is 2.*" \
"info thread 6"
mi_gdb_test "frame" \
".*#0 0x.*" \
"frame 2"
# Ask about a different frame in a different thread. After this the
# current thread and frame should not have changed.
mi_gdb_test "-stack-info-frame --thread 3 --frame 1" \
"\\^done,frame=\{level=\"1\".*" \
"-stack-info-frame 2"
mi_gdb_test "thread" \
".*Current thread is 2.*" \
"info thread 7"
mi_gdb_test "frame" \
".*#0 0x.*" \
"frame 3"
# Select a different frame in the current thread. Despite the use of
# the --frame option, we do expect the currently selected frame to
# change.
mi_gdb_test "-stack-select-frame --thread 2 --frame 0 1" \
"\\^done" \
"--stack-select-frame 1"
mi_gdb_test "thread" \
".*Current thread is 2.*" \
"info thread 8"
mi_gdb_test "frame" \
".*#1 0x.*" \
"frame 4"
# Similar to the previous test, but this time the --frame option is
# the same as the frame we are selecting. We still expect GDB to
# update the currently selected frame.
mi_gdb_test "-stack-select-frame --thread 2 --frame 2 2" \
"\\^done" \
"--stack-select-frame 2"
mi_gdb_test "thread" \
".*Current thread is 2.*" \
"info thread 9"
mi_gdb_test "frame" \
".*#2 0x.*" \
"frame 5"
# Now select a frame in a different thread. We expect both the
# currently selected thread, and the currently selected frame to be
# updated.
mi_gdb_test "-stack-select-frame --thread 1 --frame 0 0" \
"\\^done" \
"--stack-select-frame 3"
mi_gdb_test "thread" \
".*Current thread is 1.*" \
"info thread 10"
mi_gdb_test "frame" \
".*#0 main.*" \
"frame 6"