[PATCH 3/3] gdb: add a '-stopped' option to "info threads"

[Tankut Baris Aktemur <tankut.baris.aktemur@intel.com>]

Add a '-stopped' option to the "info threads" command to print stopped
threads only and skip the running ones.  This is a convenience flag to
filter out the running threads in programs that have many threads.

Suppose we have an application with 5 threads, 2 of which have hit a
breakpoint.  The "info threads" command in the non-stop mode gives:

  (gdb) info threads
    Id   Target Id             Frame
  * 1    Thread 0x7ffff7d99740 (running)
    2    Thread 0x7ffff7d98700 something () at file.c:30
    3    Thread 0x7ffff7597700 (running)
    4    Thread 0x7ffff6d96700 something () at file.c:30
    5    Thread 0x7ffff6595700 (running)
  (gdb)

Using the "-stopped" flag, we get

  (gdb) info threads -stopped
    Id   Target Id             Frame
    2    Thread 0x7ffff7d98700 something () at file.c:30
    4    Thread 0x7ffff6d96700 something () at file.c:30
  (gdb)

When combined with a thread ID, the behavior is as follows:

  (gdb) info threads 3
    Id   Target Id             Frame
    3    Thread 0x7ffff7597700 (running)
  (gdb) info threads -stopped 3
  No stopped threads match '3'.
  (gdb)

Regression-tested on X86_64 Linux.
---
 gdb/NEWS                                      |  7 ++
 gdb/doc/gdb.texinfo                           |  6 +-
 gdb/testsuite/gdb.base/options.exp            | 11 ++-
 .../gdb.threads/info-threads-stopped.c        | 78 +++++++++++++++++++
 .../gdb.threads/info-threads-stopped.exp      | 75 ++++++++++++++++++
 gdb/thread.c                                  | 17 +++-
 6 files changed, 190 insertions(+), 4 deletions(-)
 create mode 100644 gdb/testsuite/gdb.threads/info-threads-stopped.c
 create mode 100644 gdb/testsuite/gdb.threads/info-threads-stopped.exp

diff --git a/gdb/NEWS b/gdb/NEWS
index 10a1a70fa52..33b104fda72 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -96,6 +96,13 @@ info main
    $2 = 1
    (gdb) break func if $_shell("some command") == 0
 
+* Changed commands
+
+info threads [-gid] [-stopped] [ID]...
+  This command now takes an optional flag, '-stopped', that causes only
+  the stopped threads to be printed.  The flag can be useful to get a
+  reduced list when there is a large number of unstopped threads.
+
 * MI changes
 
 ** mi now reports 'no-history' as a stop reason when hitting the end of the
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index ed14888b77b..02f6a9eb49a 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -3678,7 +3678,7 @@ Thread 1 "main" received signal SIGINT, Interrupt.
 @table @code
 @anchor{info_threads}
 @kindex info threads
-@item info threads @r{[}-gid@r{]} @r{[}@var{thread-id-list}@r{]}
+@item info threads @r{[}-gid@r{]} @r{[}-stopped@r{]} @r{[}@var{thread-id-list}@r{]}
 
 Display information about one or more threads.  With no arguments
 displays information about all threads.  You can specify the list of
@@ -3728,6 +3728,10 @@ If you're debugging multiple inferiors, @value{GDBN} displays thread
 IDs using the qualified @var{inferior-num}.@var{thread-num} format.
 Otherwise, only @var{thread-num} is shown.
 
+If you specify the @samp{-stopped} option, @value{GDBN} displays the
+stopped threads only.  This can be helpful to reduce the output list
+if there is a large number of unstopped threads.
+
 If you specify the @samp{-gid} option, @value{GDBN} displays a column
 indicating each thread's global thread ID:
 
diff --git a/gdb/testsuite/gdb.base/options.exp b/gdb/testsuite/gdb.base/options.exp
index 6d90615710e..58c85567a4e 100644
--- a/gdb/testsuite/gdb.base/options.exp
+++ b/gdb/testsuite/gdb.base/options.exp
@@ -492,12 +492,21 @@ proc_with_prefix test-thread-apply {} {
 proc_with_prefix test-info-threads {} {
     test_gdb_complete_multiple "info threads " "" "" {
 	"-gid"
+	"-stopped"
 	"ID"
     }
 
+    test_gdb_complete_multiple "info threads " "-" "" {
+	"-gid"
+	"-stopped"
+    }
+
     test_gdb_complete_unique \
-	"info threads -" \
+	"info threads -g" \
 	"info threads -gid"
+    test_gdb_complete_unique \
+	"info threads -s" \
+	"info threads -stopped"
 
     # "ID" isn't really something the user can type.
     test_gdb_complete_none "info threads I"
diff --git a/gdb/testsuite/gdb.threads/info-threads-stopped.c b/gdb/testsuite/gdb.threads/info-threads-stopped.c
new file mode 100644
index 00000000000..42ca8cf0b69
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/info-threads-stopped.c
@@ -0,0 +1,78 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2022-2023 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/>.  */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <pthread.h>
+
+#define NUM 4
+
+volatile int should_spin = 1;
+
+static void
+something ()
+{
+}
+
+static void
+spin ()
+{
+  while (should_spin)
+    usleep (1);
+}
+
+static void *
+work (void *arg)
+{
+  int id = *((int *) arg);
+
+  /* Sleep a bit to give the other threads a chance to run.  */
+  usleep (1);
+
+  if (id % 2 == 0)
+    something (); /* break-here */
+  else
+    spin ();
+
+  pthread_exit (NULL);
+}
+
+int
+main ()
+{
+  /* Ensure we stop if GDB crashes and DejaGNU fails to kill us.  */
+  alarm (10);
+
+  pthread_t threads[NUM];
+  void *thread_result;
+  int ids[NUM];
+
+  for (int i = 0; i < NUM; i++)
+    {
+      ids[i] = i + 2;
+      pthread_create (&threads[i], NULL, work, &(ids[i]));
+    }
+
+  sleep (10);
+  should_spin = 0;
+
+  for (int i = 0; i < NUM; i++)
+    pthread_join(threads[i], &thread_result);
+
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.threads/info-threads-stopped.exp b/gdb/testsuite/gdb.threads/info-threads-stopped.exp
new file mode 100644
index 00000000000..5643a513aff
--- /dev/null
+++ b/gdb/testsuite/gdb.threads/info-threads-stopped.exp
@@ -0,0 +1,75 @@
+# Copyright (C) 2022-2023 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 for the '-stopped' flag of the "info threads" command.
+
+standard_testfile
+
+if {[gdb_compile_pthreads "${srcdir}/${subdir}/${srcfile}" "${binfile}" \
+	 executable debug] != "" } {
+    return -1
+}
+
+save_vars { GDBFLAGS } {
+    append GDBFLAGS " -ex \"set non-stop on\""
+    clean_restart $binfile
+}
+
+gdb_breakpoint "something"
+gdb_run_cmd
+
+# Two threads hit the bp.
+set fill "\[^\r\n\]+"
+set num_hits 0
+gdb_test_multiple "" "hit the breakpoint" -lbl {
+    -re "\r\nThread ${fill} hit Breakpoint 1${fill}" {
+	incr num_hits
+	if {$num_hits < 2} {
+	    exp_continue
+	}
+    }
+    -re "\r\n$gdb_prompt " {
+	exp_continue
+    }
+}
+gdb_assert {$num_hits == 2} "two threads hit the bp"
+
+# Count the number of running/stopped threads reported
+# by the "info threads" command.
+foreach flag {"" "-stopped"} {
+    set num_running 0
+    set num_stopped 0
+    gdb_test_multiple "info threads $flag" "info threads $flag" {
+	-re "Id${fill}Target Id${fill}Frame${fill}" {
+	    exp_continue
+	}
+	-re "^\r\n. ${decimal}${fill}Thread ${fill}.running." {
+	    incr num_running
+	    exp_continue
+	}
+	-re "^\r\n. ${decimal}${fill}Thread ${fill}something ${fill}" {
+	    incr num_stopped
+	    exp_continue
+	}
+	-re "^\r\n$gdb_prompt $" {
+	    gdb_assert {$num_stopped == 2} "$gdb_test_name: num stopped"
+	    if {$flag eq ""} {
+		gdb_assert {$num_running == 3} "$gdb_test_name: num running"
+	    } else {
+		gdb_assert {$num_running == 0} "$gdb_test_name: num running"
+	    }
+	}
+    }
+}
diff --git a/gdb/thread.c b/gdb/thread.c
index 57b3f7611e2..8886bd45674 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -957,6 +957,8 @@ struct info_threads_opts
 {
   /* For "-gid".  */
   bool show_global_ids = false;
+  /* For "-stopped".  */
+  bool show_stopped_threads = false;
 };
 
 static const gdb::option::option_def info_threads_option_defs[] = {
@@ -966,6 +968,11 @@ static const gdb::option::option_def info_threads_option_defs[] = {
     [] (info_threads_opts *opts) { return &opts->show_global_ids; },
     N_("Show global thread IDs."),
   },
+  gdb::option::flag_option_def<info_threads_opts> {
+    "stopped",
+    [] (info_threads_opts *opts) { return &opts->show_stopped_threads; },
+    N_("Show stopped threads only."),
+  },
 
 };
 
@@ -1008,6 +1015,11 @@ should_print_thread (const char *requested_threads, int default_inf_num,
   if (thr->state == THREAD_EXITED)
     return false;
 
+  /* Skip a running thread if the user wants stopped threads only.  */
+  bool is_stopped = (thr->state == THREAD_STOPPED);
+  if (opts.show_stopped_threads && !is_stopped)
+    return false;
+
   return true;
 }
 
@@ -1094,7 +1106,8 @@ print_thread_info_1 (struct ui_out *uiout, const char *requested_threads,
 	    if (requested_threads == NULL || *requested_threads == '\0')
 	      uiout->message (_("No threads.\n"));
 	    else
-	      uiout->message (_("No threads match '%s'.\n"),
+	      uiout->message (_("No %sthreads match '%s'.\n"),
+			      (opts.show_stopped_threads ? "stopped " : ""),
 			      requested_threads);
 	    return;
 	  }
@@ -1219,7 +1232,7 @@ void
 print_thread_info (struct ui_out *uiout, const char *requested_threads,
 		   int pid)
 {
-  info_threads_opts opts {false};
+  info_threads_opts opts {false, false};
   print_thread_info_1 (uiout, requested_threads, 1, pid, opts);
 }
 
-- 
2.25.1

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