gdb: add some additional thread status debug output

While working on this patch:

  https://sourceware.org/pipermail/gdb-patches/2022-January/185109.html

I found it really useful to print the executing/resumed status of all
threads (or all threads in a particular inferior) at various
places (e.g. when a new inferior is started, when GDB attaches, etc).

This debug was originally part of the above patch, but I wanted to
rewrite this as a separate patch and move the code into a new function
in infrun.h, which is what this patch does.

Unless 'set debug infrun on' is in effect, then there should be no
user visible changes after this commit.

3 files changed, 37 insertions, 11 deletions

diff --git a/gdb/infcmd.c b/gdb/infcmd.c
index 53c9e3d..e909d4d 100644
--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -238,6 +238,9 @@ post_create_inferior (int from_tty)
   /* Be sure we own the terminal in case write operations are performed.  */ 
   target_terminal::ours_for_output ();
 
+  infrun_debug_show_threads ("threads in the newly created inferior",
+			     current_inferior ()->non_exited_threads ());
+
   /* If the target hasn't taken care of this already, do it now.
      Targets which need to access registers during to_open,
      to_create_inferior, or to_attach should do it earlier; but many
@@ -454,6 +457,9 @@ run_command_1 (const char *args, int from_tty, enum run_how run_how)
      shouldn't refer to run_target again.  */
   run_target = NULL;
 
+  infrun_debug_show_threads ("immediately after create_process",
+			     current_inferior ()->non_exited_threads ());
+
   /* We're starting off a new process.  When we get out of here, in
      non-stop mode, finish the state of all threads of that process,
      but leave other threads alone, as they may be stopped in internal
@@ -2589,17 +2595,8 @@ attach_command (const char *args, int from_tty)
      shouldn't refer to attach_target again.  */
   attach_target = NULL;
 
-  if (debug_infrun)
-    {
-      infrun_debug_printf ("immediately after attach:");
-      for (thread_info *thread : inferior->non_exited_threads ())
-	infrun_debug_printf ("  thread %s, executing = %d, resumed = %d, "
-			     "state = %s",
-			     thread->ptid.to_string ().c_str (),
-			     thread->executing (),
-			     thread->resumed (),
-			     thread_state_string (thread->state));
-    }
+  infrun_debug_show_threads ("immediately after attach",
+			     current_inferior ()->non_exited_threads ());
 
   /* Enable async mode if it is supported by the target.  */
   if (target_can_async_p ())
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 531d398..02c98b5 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -5063,6 +5063,9 @@ stop_all_threads (const char *reason, inferior *inf)
   INFRUN_SCOPED_DEBUG_START_END ("reason=%s, inf=%d", reason,
 				 inf != nullptr ? inf->num : -1);
 
+  infrun_debug_show_threads ("non-exited threads",
+			     all_non_exited_threads ());
+
   scoped_restore_current_thread restore_thread;
 
   /* Enable thread events on relevant targets.  */
diff --git a/gdb/infrun.h b/gdb/infrun.h
index 9685f3a..0c7c55e 100644
--- a/gdb/infrun.h
+++ b/gdb/infrun.h
@@ -48,6 +48,32 @@ extern bool debug_infrun;
 #define INFRUN_SCOPED_DEBUG_ENTER_EXIT \
   scoped_debug_enter_exit (debug_infrun, "infrun")
 
+/* A infrun debug helper routine to print out all the threads in the set
+   THREADS (which should be a range type that returns thread_info*
+   objects).
+
+   The TITLE is a string that is printed before the list of threads.
+
+   Output is only produced when 'set debug infrun on'.  */
+
+template<typename ThreadRange>
+static inline void
+infrun_debug_show_threads (const char *title, ThreadRange threads)
+{
+  if (debug_infrun)
+    {
+      infrun_debug_printf ("%s:", title);
+      for (thread_info *thread : threads)
+	infrun_debug_printf ("  thread %s, executing = %d, resumed = %d, "
+			     "state = %s",
+			     thread->ptid.to_string ().c_str (),
+			     thread->executing (),
+			     thread->resumed (),
+			     thread_state_string (thread->state));
+    }
+}
+
+
 /* Nonzero if we want to give control to the user when we're notified
    of shared library events by the dynamic linker.  */
 extern int stop_on_solib_events;