Use thread_info and inferior pointers more throughout

This is more preparation bits for multi-target support.

In a multi-target scenario, we need to address the case of different
processes/threads running on different targets that happen to have the
same PID/PTID.  E.g., we can have both process 123 in target 1, and
process 123 in target 2, while they're in reality different processes
running on different machines.  Or maybe we've loaded multiple
instances of the same core file.  Etc.

To address this, in my WIP multi-target branch, threads and processes
are uniquely identified by the (process_stratum target_ops *, ptid_t)
and (process_stratum target_ops *, pid) tuples respectively.  I.e.,
each process_stratum instance has its own thread/process number space.

As you can imagine, that requires passing around target_ops * pointers
in a number of functions where we're currently passing only a ptid_t
or an int.  E.g., when we look up a thread_info object by ptid_t in
find_thread_ptid, the ptid_t alone isn't sufficient.

In many cases though, we already have the thread_info or inferior
pointer handy, but we "lose" it somewhere along the call stack, only
to look it up again by ptid_t/pid.  Since thread_info or inferior
objects know their parent target, if we pass around thread_info or
inferior pointers when possible, we avoid having to add extra
target_ops parameters to many functions, and also, we eliminate a
number of by ptid_t/int lookups.

So that's what this patch does.  In a bit more detail:

- Changes a number of functions and methods to take a thread_info or
  inferior pointer instead of a ptid_t or int parameter.

- Changes a number of structure fields from ptid_t/int to inferior or
  thread_info pointers.

- Uses the inferior_thread() function whenever possible instead of
  inferior_ptid.

- Uses thread_info pointers directly when possible instead of the
  is_running/is_stopped etc. routines that require a lookup.

- A number of functions are eliminated along the way, such as:

  int valid_gdb_inferior_id (int num);
  int pid_to_gdb_inferior_id (int pid);
  int gdb_inferior_id_to_pid (int num);
  int in_inferior_list (int pid);

- A few structures and places hold a thread_info pointer across
  inferior execution, so now they take a strong reference to the
  (refcounted) thread_info object to avoid the thread_info pointer
  getting stale.  This is done in enable_thread_stack_temporaries and
  in the infcall.c code.

- Related, there's a spot in infcall.c where using a RAII object to
  handle the refcount would be handy, so a gdb::ref_ptr specialization
  for thread_info is added (thread_info_ref, in gdbthread.h), along
  with a gdb_ref_ptr policy that works for all refcounted_object types
  (in common/refcounted-object.h).

gdb/ChangeLog:
2018-06-21  Pedro Alves  <palves@redhat.com>

	* ada-lang.h (ada_get_task_number): Take a thread_info pointer
	instead of a ptid_t.  All callers adjusted.
	* ada-tasks.c (ada_get_task_number): Likewise.  All callers
	adjusted.
	(print_ada_task_info, display_current_task_id, task_command_1):
	Adjust.
	* breakpoint.c (watchpoint_in_thread_scope): Adjust to use
	inferior_thread.
	(breakpoint_kind): Adjust.
	(remove_breakpoints_pid): Rename to ...
	(remove_breakpoints_inf): ... this.  Adjust to take an inferior
	pointer.  All callers adjusted.
	(bpstat_clear_actions): Use inferior_thread.
	(get_bpstat_thread): New.
	(bpstat_do_actions): Use it.
	(bpstat_check_breakpoint_conditions, bpstat_stop_status): Adjust
	to take a thread_info pointer.  All callers adjusted.
	(set_longjmp_breakpoint_for_call_dummy, set_momentary_breakpoint)
	(breakpoint_re_set_thread): Use inferior_thread.
	* breakpoint.h (struct inferior): Forward declare.
	(bpstat_stop_status): Update.
	(remove_breakpoints_pid): Delete.
	(remove_breakpoints_inf): New.
	* bsd-uthread.c (bsd_uthread_target::wait)
	(bsd_uthread_target::update_thread_list): Use find_thread_ptid.
	* btrace.c (btrace_add_pc, btrace_enable, btrace_fetch)
	(maint_btrace_packet_history_cmd)
	(maint_btrace_clear_packet_history_cmd): Adjust.
	(maint_btrace_clear_cmd, maint_info_btrace_cmd): Adjust to use
	inferior_thread.
	* cli/cli-interp.c: Include "inferior.h".
	* common/refcounted-object.h (struct
	refcounted_object_ref_policy): New.
	* compile/compile-object-load.c: Include gdbthread.h.
	(store_regs): Use inferior_thread.
	* corelow.c (core_target::close): Use current_inferior.
	(core_target_open): Adjust to use first_thread_of_inferior and use
	the current inferior.
	* ctf.c (ctf_target::close): Adjust to use current_inferior.
	* dummy-frame.c (dummy_frame_id) <ptid>: Delete, replaced by ...
	<thread>: ... this new field.  All references adjusted.
	(dummy_frame_pop, dummy_frame_discard, register_dummy_frame_dtor):
	Take a thread_info pointer instead of a ptid_t.
	* dummy-frame.h (dummy_frame_push, dummy_frame_pop)
	(dummy_frame_discard, register_dummy_frame_dtor): Take a
	thread_info pointer instead of a ptid_t.
	* elfread.c: Include "inferior.h".
	(elf_gnu_ifunc_resolver_stop, elf_gnu_ifunc_resolver_return_stop):
	Use inferior_thread.
	* eval.c (evaluate_subexp): Likewise.
	* frame.c (frame_pop, has_stack_frames, find_frame_sal): Use
	inferior_thread.
	* gdb_proc_service.h (struct thread_info): Forward declare.
	(struct ps_prochandle) <ptid>: Delete, replaced by ...
	<thread>: ... this new field.  All references adjusted.
	* gdbarch.h, gdbarch.c: Regenerate.
	* gdbarch.sh (get_syscall_number): Replace 'ptid' parameter with a
	'thread' parameter.  All implementations and callers adjusted.
	* gdbthread.h (thread_info) <set_running>: New method.
	(delete_thread, delete_thread_silent): Take a thread_info pointer
	instead of a ptid.
	(global_thread_id_to_ptid, ptid_to_global_thread_id): Delete.
	(first_thread_of_process): Delete, replaced by ...
	(first_thread_of_inferior): ... this new function.  All callers
	adjusted.
	(any_live_thread_of_process): Delete, replaced by ...
	(any_live_thread_of_inferior): ... this new function.  All callers
	adjusted.
	(switch_to_thread, switch_to_no_thread): Declare.
	(is_executing): Delete.
	(enable_thread_stack_temporaries): Update comment.
	<enable_thread_stack_temporaries>: Take a thread_info pointer
	instead of a ptid_t.  Incref the thread.
	<~enable_thread_stack_temporaries>: Decref the thread.
	<m_ptid>: Delete
	<m_thr>: New.
	(thread_stack_temporaries_enabled_p, push_thread_stack_temporary)
	(get_last_thread_stack_temporary)
	(value_in_thread_stack_temporaries, can_access_registers_thread):
	Take a thread_info pointer instead of a ptid_t.  All callers
	adjusted.
	* infcall.c (get_call_return_value): Use inferior_thread.
	(run_inferior_call): Work with thread pointers instead of ptid_t.
	(call_function_by_hand_dummy): Work with thread pointers instead
	of ptid_t.  Use thread_info_ref.
	* infcmd.c (proceed_thread_callback): Access thread's state
	directly.
	(ensure_valid_thread, ensure_not_running): Use inferior_thread,
	access thread's state directly.
	(continue_command): Use inferior_thread.
	(info_program_command): Use find_thread_ptid and access thread
	state directly.
	(proceed_after_attach_callback): Use thread state directly.
	(notice_new_inferior): Take a thread_info pointer instead of a
	ptid_t.  All callers adjusted.
	(exit_inferior): Take an inferior pointer instead of a pid.  All
	callers adjusted.
	(exit_inferior_silent): New.
	(detach_inferior): Delete.
	(valid_gdb_inferior_id, pid_to_gdb_inferior_id)
	(gdb_inferior_id_to_pid, in_inferior_list): Delete.
	(detach_inferior_command, kill_inferior_command): Use
	find_inferior_id instead of valid_gdb_inferior_id and
	gdb_inferior_id_to_pid.
	(inferior_command): Use inferior and thread pointers.
	* inferior.h (struct thread_info): Forward declare.
	(notice_new_inferior): Take a thread_info pointer instead of a
	ptid_t.  All callers adjusted.
	(detach_inferior): Delete declaration.
	(exit_inferior, exit_inferior_silent): Take an inferior pointer
	instead of a pid.  All callers adjusted.
	(gdb_inferior_id_to_pid, pid_to_gdb_inferior_id, in_inferior_list)
	(valid_gdb_inferior_id): Delete.
	* infrun.c (follow_fork_inferior, proceed_after_vfork_done)
	(handle_vfork_child_exec_or_exit, follow_exec): Adjust.
	(struct displaced_step_inferior_state) <pid>: Delete, replaced by
	...
	<inf>: ... this new field.
	<step_ptid>: Delete, replaced by ...
	<step_thread>: ... this new field.
	(get_displaced_stepping_state): Take an inferior pointer instead
	of a pid.  All callers adjusted.
	(displaced_step_in_progress_any_inferior): Adjust.
	(displaced_step_in_progress_thread): Take a thread pointer instead
	of a ptid_t.  All callers adjusted.
	(displaced_step_in_progress, add_displaced_stepping_state): Take
	an inferior pointer instead of a pid.  All callers adjusted.
	(get_displaced_step_closure_by_addr): Adjust.
	(remove_displaced_stepping_state): Take an inferior pointer
	instead of a pid.  All callers adjusted.
	(displaced_step_prepare_throw, displaced_step_prepare)
	(displaced_step_fixup): Take a thread pointer instead of a ptid_t.
	All callers adjusted.
	(start_step_over): Adjust.
	(infrun_thread_ptid_changed): Remove bit updating ptids in the
	displaced step queue.
	(do_target_resume): Adjust.
	(fetch_inferior_event): Use inferior_thread.
	(context_switch, get_inferior_stop_soon): Take an
	execution_control_state pointer instead of a ptid_t.  All callers
	adjusted.
	(switch_to_thread_cleanup): Delete.
	(stop_all_threads): Use scoped_restore_current_thread.
	* inline-frame.c: Include "gdbthread.h".
	(inline_state) <inline_state>: Take a thread pointer instead of a
	ptid_t.  All callers adjusted.
	<ptid>: Delete, replaced by ...
	<thread>: ... this new field.
	(find_inline_frame_state): Take a thread pointer instead of a
	ptid_t.  All callers adjusted.
	(skip_inline_frames, step_into_inline_frame)
	(inline_skipped_frames, inline_skipped_symbol): Take a thread
	pointer instead of a ptid_t.  All callers adjusted.
	* inline-frame.h (skip_inline_frames, step_into_inline_frame)
	(inline_skipped_frames, inline_skipped_symbol): Likewise.
	* linux-fork.c (delete_checkpoint_command): Adjust to use thread
	pointers directly.
	* linux-nat.c (get_detach_signal): Likewise.
	* linux-thread-db.c (thread_from_lwp): New 'stopped' parameter.
	(thread_db_notice_clone): Adjust.
	(thread_db_find_new_threads_silently)
	(thread_db_find_new_threads_2, thread_db_find_new_threads_1): Take
	a thread pointer instead of a ptid_t.  All callers adjusted.
	* mi/mi-cmd-var.c: Include "inferior.h".
	(mi_cmd_var_update_iter): Update to use thread pointers.
	* mi/mi-interp.c (mi_new_thread): Update to use the thread's
	inferior directly.
	(mi_output_running_pid, mi_inferior_count): Delete, bits factored
	out to ...
	(mi_output_running): ... this new function.
	(mi_on_resume_1): Adjust to use it.
	(mi_user_selected_context_changed): Adjust to use inferior_thread.
	* mi/mi-main.c (proceed_thread): Adjust to use thread pointers
	directly.
	(interrupt_thread_callback): : Adjust to use thread and inferior
	pointers.
	* proc-service.c: Include "gdbthread.h".
	(ps_pglobal_lookup): Adjust to use the thread's inferior directly.
	* progspace-and-thread.c: Include "inferior.h".
	* progspace.c: Include "inferior.h".
	* python/py-exitedevent.c (create_exited_event_object): Adjust to
	hold a reference to an inferior_object.
	* python/py-finishbreakpoint.c (bpfinishpy_init): Adjust to use
	inferior_thread.
	* python/py-inferior.c (struct inferior_object): Give the type a
	tag name instead of a typedef.
	(python_on_normal_stop): No need to check if the current thread is
	listed.
	(inferior_to_inferior_object): Change return type to
	inferior_object.  All callers adjusted.
	(find_thread_object): Delete, bits factored out to ...
	(thread_to_thread_object): ... this new function.
	* python/py-infthread.c (create_thread_object): Use
	inferior_to_inferior_object.
	(thpy_is_stopped): Use thread pointer directly.
	(gdbpy_selected_thread): Use inferior_thread.
	* python/py-record-btrace.c (btpy_list_object) <ptid>: Delete
	field, replaced with ...
	<thread>: ... this new field.  All users adjusted.
	(btpy_insn_or_gap_new): Drop const.
	(btpy_list_new): Take a thread pointer instead of a ptid_t.  All
	callers adjusted.
	* python/py-record.c: Include "gdbthread.h".
	(recpy_insn_new, recpy_func_new): Take a thread pointer instead of
	a ptid_t.  All callers adjusted.
	(gdbpy_current_recording): Use inferior_thread.
	* python/py-record.h (recpy_record_object) <ptid>: Delete
	field, replaced with ...
	<thread>: ... this new field.  All users adjusted.
	(recpy_element_object) <ptid>: Delete
	field, replaced with ...
	<thread>: ... this new field.  All users adjusted.
	(recpy_insn_new, recpy_func_new): Take a thread pointer instead of
	a ptid_t.  All callers adjusted.
	* python/py-threadevent.c: Include "gdbthread.h".
	(get_event_thread): Use thread_to_thread_object.
	* python/python-internal.h (struct inferior_object): Forward
	declare.
	(find_thread_object, find_inferior_object): Delete declarations.
	(thread_to_thread_object, inferior_to_inferior_object): New
	declarations.
	* record-btrace.c: Include "inferior.h".
	(require_btrace_thread): Use inferior_thread.
	(record_btrace_frame_sniffer)
	(record_btrace_tailcall_frame_sniffer): Use inferior_thread.
	(get_thread_current_frame): Use scoped_restore_current_thread and
	switch_to_thread.
	(get_thread_current_frame): Use thread pointer directly.
	(record_btrace_replay_at_breakpoint): Use thread's inferior
	pointer directly.
	* record-full.c: Include "inferior.h".
	* regcache.c: Include "gdbthread.h".
	(get_thread_arch_regcache): Use the inferior's address space
	directly.
	(get_thread_regcache, registers_changed_thread): New.
	* regcache.h (get_thread_regcache(thread_info *thread)): New
	overload.
	(registers_changed_thread): New.
	(remote_target) <remote_detach_1>: Swap order of parameters.
	(remote_add_thread): <remote_add_thread>: Return the new thread.
	(get_remote_thread_info(ptid_t)): New overload.
	(remote_target::remote_notice_new_inferior): Use thread pointers
	directly.
	(remote_target::process_initial_stop_replies): Use
	thread_info::set_running.
	(remote_target::remote_detach_1, remote_target::detach)
	(extended_remote_target::detach): Adjust.
	* stack.c (frame_show_address): Use inferior_thread.
	* target-debug.h (target_debug_print_thread_info_pp): New.
	* target-delegates.c: Regenerate.
	* target.c (default_thread_address_space): Delete.
	(memory_xfer_partial_1): Use current_inferior.
	(target_detach): Use current_inferior.
	(target_thread_address_space): Delete.
	(generic_mourn_inferior): Use current_inferior.
	* target.h (struct target_ops) <thread_address_space>: Delete.
	(target_thread_address_space): Delete.
	* thread.c (init_thread_list): Use ALL_THREADS_SAFE.  Use thread
	pointers directly.
	(delete_thread_1, delete_thread, delete_thread_silent): Take a
	thread pointer instead of a ptid_t.  Adjust all callers.
	(ptid_to_global_thread_id, global_thread_id_to_ptid): Delete.
	(first_thread_of_process): Delete, replaced by ...
	(first_thread_of_inferior): ... this new function.  All callers
	adjusted.
	(any_thread_of_process): Rename to ...
	(any_thread_of_inferior): ... this, and take an inferior pointer.
	(any_live_thread_of_process): Rename to ...
	(any_live_thread_of_inferior): ... this, and take an inferior
	pointer.
	(thread_stack_temporaries_enabled_p, push_thread_stack_temporary)
	(value_in_thread_stack_temporaries)
	(get_last_thread_stack_temporary): Take a thread pointer instead
	of a ptid_t.  Adjust all callers.
	(thread_info::set_running): New.
	(validate_registers_access): Use inferior_thread.
	(can_access_registers_ptid): Rename to ...
	(can_access_registers_thread): ... this, and take a thread
	pointer.
	(print_thread_info_1): Adjust to compare thread pointers instead
	of ptids.
	(switch_to_no_thread, switch_to_thread): Make extern.
	(scoped_restore_current_thread::~scoped_restore_current_thread):
	Use m_thread pointer directly.
	(scoped_restore_current_thread::scoped_restore_current_thread):
	Use inferior_thread.
	(thread_command): Use thread pointer directly.
	(thread_num_make_value_helper): Use inferior_thread.
	* top.c (execute_command): Use inferior_thread.
	* tui/tui-interp.c: Include "inferior.h".
	* varobj.c (varobj_create): Use inferior_thread.
	(value_of_root_1): Use find_thread_global_id instead of
	global_thread_id_to_ptid.

1 files changed, 105 insertions, 124 deletions

diff --git a/gdb/thread.c b/gdb/thread.c
index f5a29f5cc14..2b471cd2925 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -220,16 +220,12 @@ set_thread_exited (thread_info *tp, int silent)
 void
 init_thread_list (void)
 {
-  struct thread_info *tp, *tpnext;
+  struct thread_info *tp, *tmp;
 
   highest_thread_num = 0;
 
-  if (!thread_list)
-    return;
-
-  for (tp = thread_list; tp; tp = tpnext)
+  ALL_THREADS_SAFE (tp, tmp)
     {
-      tpnext = tp->next;
       if (tp->deletable ())
 	delete tp;
       else
@@ -285,28 +281,28 @@ add_thread_silent (ptid_t ptid)
 
       if (inferior_ptid == ptid)
 	{
-	  tp = new_thread (inf, null_ptid);
+	  thread_info *new_thr = new_thread (inf, null_ptid);
 
 	  /* Make switch_to_thread not read from the thread.  */
-	  tp->state = THREAD_EXITED;
-	  switch_to_thread (null_ptid);
+	  new_thr->state = THREAD_EXITED;
+	  switch_to_no_thread ();
 
 	  /* Now we can delete it.  */
-	  delete_thread (ptid);
+	  delete_thread (tp);
 
 	  /* Now reset its ptid, and reswitch inferior_ptid to it.  */
-	  tp->ptid = ptid;
-	  tp->state = THREAD_STOPPED;
-	  switch_to_thread (ptid);
+	  new_thr->ptid = ptid;
+	  new_thr->state = THREAD_STOPPED;
+	  switch_to_thread (new_thr);
 
-	  gdb::observers::new_thread.notify (tp);
+	  gdb::observers::new_thread.notify (new_thr);
 
 	  /* All done.  */
-	  return tp;
+	  return new_thr;
 	}
       else
 	/* Just go ahead and delete it.  */
-	delete_thread (ptid);
+	delete_thread (tp);
     }
 
   tp = new_thread (inf, ptid);
@@ -436,17 +432,18 @@ thread_step_over_chain_remove (struct thread_info *tp)
   step_over_chain_remove (&step_over_queue_head, tp);
 }
 
-/* Delete thread PTID.  If SILENT, don't notify the observer of this
+/* Delete thread TP.  If SILENT, don't notify the observer of this
    exit.  */
+
 static void
-delete_thread_1 (ptid_t ptid, int silent)
+delete_thread_1 (thread_info *thr, bool silent)
 {
   struct thread_info *tp, *tpprev;
 
   tpprev = NULL;
 
   for (tp = thread_list; tp; tpprev = tp, tp = tp->next)
-    if (tp->ptid == ptid)
+    if (tp == thr)
       break;
 
   if (!tp)
@@ -468,20 +465,21 @@ delete_thread_1 (ptid_t ptid, int silent)
   delete tp;
 }
 
-/* Delete thread PTID and notify of thread exit.  If this is
-   inferior_ptid, don't actually delete it, but tag it as exited and
-   do the notification.  If PTID is the user selected thread, clear
+/* Delete thread THREAD and notify of thread exit.  If this is the
+   current thread, don't actually delete it, but tag it as exited and
+   do the notification.  If this is the user selected thread, clear
    it.  */
+
 void
-delete_thread (ptid_t ptid)
+delete_thread (thread_info *thread)
 {
-  delete_thread_1 (ptid, 0 /* not silent */);
+  delete_thread_1 (thread, false /* not silent */);
 }
 
 void
-delete_thread_silent (ptid_t ptid)
+delete_thread_silent (thread_info *thread)
 {
-  delete_thread_1 (ptid, 1 /* silent */);
+  delete_thread_1 (thread, true /* silent */);
 }
 
 struct thread_info *
@@ -602,29 +600,6 @@ valid_global_thread_id (int global_id)
 }
 
 int
-ptid_to_global_thread_id (ptid_t ptid)
-{
-  struct thread_info *tp;
-
-  for (tp = thread_list; tp; tp = tp->next)
-    if (tp->ptid == ptid)
-      return tp->global_num;
-
-  return 0;
-}
-
-ptid_t
-global_thread_id_to_ptid (int global_id)
-{
-  struct thread_info *thread = find_thread_global_id (global_id);
-
-  if (thread)
-    return thread->ptid;
-  else
-    return minus_one_ptid;
-}
-
-int
 in_thread_list (ptid_t ptid)
 {
   struct thread_info *tp;
@@ -636,51 +611,50 @@ in_thread_list (ptid_t ptid)
   return 0;			/* Never heard of 'im.  */
 }
 
-/* Finds the first thread of the inferior given by PID.  If PID is -1,
-   return the first thread in the list.  */
+/* Finds the first thread of the inferior.  */
 
-struct thread_info *
-first_thread_of_process (int pid)
+thread_info *
+first_thread_of_inferior (inferior *inf)
 {
   struct thread_info *tp, *ret = NULL;
 
   for (tp = thread_list; tp; tp = tp->next)
-    if (pid == -1 || ptid_get_pid (tp->ptid) == pid)
+    if (tp->inf == inf)
       if (ret == NULL || tp->global_num < ret->global_num)
 	ret = tp;
 
   return ret;
 }
 
-struct thread_info *
-any_thread_of_process (int pid)
+thread_info *
+any_thread_of_inferior (inferior *inf)
 {
   struct thread_info *tp;
 
-  gdb_assert (pid != 0);
+  gdb_assert (inf->pid != 0);
 
   /* Prefer the current thread.  */
-  if (ptid_get_pid (inferior_ptid) == pid)
+  if (inf == current_inferior ())
     return inferior_thread ();
 
   ALL_NON_EXITED_THREADS (tp)
-    if (ptid_get_pid (tp->ptid) == pid)
+    if (tp->inf == inf)
       return tp;
 
   return NULL;
 }
 
-struct thread_info *
-any_live_thread_of_process (int pid)
+thread_info *
+any_live_thread_of_inferior (inferior *inf)
 {
   struct thread_info *curr_tp = NULL;
   struct thread_info *tp;
   struct thread_info *tp_executing = NULL;
 
-  gdb_assert (pid != 0);
+  gdb_assert (inf != NULL && inf->pid != 0);
 
   /* Prefer the current thread if it's not executing.  */
-  if (ptid_get_pid (inferior_ptid) == pid)
+  if (inferior_ptid != null_ptid && current_inferior () == inf)
     {
       /* If the current thread is dead, forget it.  If it's not
 	 executing, use it.  Otherwise, still choose it (below), but
@@ -693,7 +667,7 @@ any_live_thread_of_process (int pid)
     }
 
   ALL_NON_EXITED_THREADS (tp)
-    if (ptid_get_pid (tp->ptid) == pid)
+    if (tp->inf == inf)
       {
 	if (!tp->executing)
 	  return tp;
@@ -731,7 +705,7 @@ prune_threads (void)
   ALL_THREADS_SAFE (tp, tmp)
     {
       if (!thread_alive (tp))
-	delete_thread (tp->ptid);
+	delete_thread (tp);
     }
 }
 
@@ -745,18 +719,16 @@ delete_exited_threads (void)
   ALL_THREADS_SAFE (tp, tmp)
     {
       if (tp->state == THREAD_EXITED)
-	delete_thread (tp->ptid);
+	delete_thread (tp);
     }
 }
 
 /* Return true value if stack temporaies are enabled for the thread
-   with id PTID.  */
+   TP.  */
 
 bool
-thread_stack_temporaries_enabled_p (ptid_t ptid)
+thread_stack_temporaries_enabled_p (thread_info *tp)
 {
-  struct thread_info *tp = find_thread_ptid (ptid);
-
   if (tp == NULL)
     return false;
   else
@@ -766,22 +738,18 @@ thread_stack_temporaries_enabled_p (ptid_t ptid)
 /* Push V on to the stack temporaries of the thread with id PTID.  */
 
 void
-push_thread_stack_temporary (ptid_t ptid, struct value *v)
+push_thread_stack_temporary (thread_info *tp, struct value *v)
 {
-  struct thread_info *tp = find_thread_ptid (ptid);
-
   gdb_assert (tp != NULL && tp->stack_temporaries_enabled);
   tp->stack_temporaries.push_back (v);
 }
 
 /* Return true if VAL is among the stack temporaries of the thread
-   with id PTID.  Return false otherwise.  */
+   TP.  Return false otherwise.  */
 
 bool
-value_in_thread_stack_temporaries (struct value *val, ptid_t ptid)
+value_in_thread_stack_temporaries (struct value *val, thread_info *tp)
 {
-  struct thread_info *tp = find_thread_ptid (ptid);
-
   gdb_assert (tp != NULL && tp->stack_temporaries_enabled);
   for (value *v : tp->stack_temporaries)
     if (v == val)
@@ -793,11 +761,10 @@ value_in_thread_stack_temporaries (struct value *val, ptid_t ptid)
 /* Return the last of the stack temporaries for thread with id PTID.
    Return NULL if there are no stack temporaries for the thread.  */
 
-struct value *
-get_last_thread_stack_temporary (ptid_t ptid)
+value *
+get_last_thread_stack_temporary (thread_info *tp)
 {
   struct value *lastval = NULL;
-  struct thread_info *tp = find_thread_ptid (ptid);
 
   gdb_assert (tp != NULL);
   if (!tp->stack_temporaries.empty ())
@@ -870,6 +837,15 @@ set_running_thread (struct thread_info *tp, int running)
   return started;
 }
 
+/* See gdbthread.h.  */
+
+void
+thread_info::set_running (bool running)
+{
+  if (set_running_thread (this, running))
+    gdb::observers::target_resumed.notify (this->ptid);
+}
+
 void
 set_running (ptid_t ptid, int running)
 {
@@ -1049,8 +1025,10 @@ validate_registers_access (void)
   if (inferior_ptid == null_ptid)
     error (_("No thread selected."));
 
+  thread_info *tp = inferior_thread ();
+
   /* Don't try to read from a dead thread.  */
-  if (is_exited (inferior_ptid))
+  if (tp->state == THREAD_EXITED)
     error (_("The current thread has terminated"));
 
   /* ... or from a spinning thread.  FIXME: This isn't actually fully
@@ -1058,25 +1036,25 @@ validate_registers_access (void)
      at the prompt) when a thread is not executing for some internal
      reason, but is marked running from the user's perspective.  E.g.,
      the thread is waiting for its turn in the step-over queue.  */
-  if (is_executing (inferior_ptid))
+  if (tp->executing)
     error (_("Selected thread is running."));
 }
 
 /* See gdbthread.h.  */
 
 bool
-can_access_registers_ptid (ptid_t ptid)
+can_access_registers_thread (thread_info *thread)
 {
   /* No thread, no registers.  */
-  if (ptid == null_ptid)
+  if (thread == NULL)
     return false;
 
   /* Don't try to read from a dead thread.  */
-  if (is_exited (ptid))
+  if (thread->state == THREAD_EXITED)
     return false;
 
   /* ... or from a spinning thread.  FIXME: see validate_registers_access.  */
-  if (is_executing (ptid))
+  if (thread->executing)
     return false;
 
   return true;
@@ -1139,13 +1117,19 @@ print_thread_info_1 (struct ui_out *uiout, const char *requested_threads,
 		     int show_global_ids)
 {
   struct thread_info *tp;
-  ptid_t current_ptid;
   const char *extra_info, *name, *target_id;
   struct inferior *inf;
   int default_inf_num = current_inferior ()->num;
 
   update_thread_list ();
-  current_ptid = inferior_ptid;
+
+  /* Whether we saw any thread.  */
+  bool any_thread = false;
+  /* Whether the current thread is exited.  */
+  bool current_exited = false;
+
+  thread_info *current_thread = (inferior_ptid != null_ptid
+				 ? inferior_thread () : NULL);
 
   {
     /* For backward compatibility, we make a list for MI.  A table is
@@ -1160,7 +1144,7 @@ print_thread_info_1 (struct ui_out *uiout, const char *requested_threads,
       {
 	int n_threads = 0;
 
-	for (tp = thread_list; tp; tp = tp->next)
+	ALL_THREADS (tp)
 	  {
 	    if (!should_print_thread (requested_threads, default_inf_num,
 				      global_ids, pid, tp))
@@ -1198,6 +1182,10 @@ print_thread_info_1 (struct ui_out *uiout, const char *requested_threads,
       {
 	int core;
 
+	any_thread = true;
+	if (tp == current_thread && tp->state == THREAD_EXITED)
+	  current_exited = true;
+
 	if (!should_print_thread (requested_threads, default_inf_num,
 				  global_ids, pid, tp))
 	  continue;
@@ -1206,7 +1194,7 @@ print_thread_info_1 (struct ui_out *uiout, const char *requested_threads,
 
 	if (!uiout->is_mi_like_p ())
 	  {
-	    if (tp->ptid == current_ptid)
+	    if (tp == current_thread)
 	      uiout->field_string ("current", "*");
 	    else
 	      uiout->field_skip ("current");
@@ -1259,7 +1247,7 @@ print_thread_info_1 (struct ui_out *uiout, const char *requested_threads,
 	  {
 	    /* The switch below puts us at the top of the stack (leaf
 	       frame).  */
-	    switch_to_thread (tp->ptid);
+	    switch_to_thread (tp);
 	    print_stack_frame (get_selected_frame (NULL),
 			       /* For MI output, print frame level.  */
 			       uiout->is_mi_like_p (),
@@ -1287,20 +1275,14 @@ print_thread_info_1 (struct ui_out *uiout, const char *requested_threads,
 
   if (pid == -1 && requested_threads == NULL)
     {
-      if (uiout->is_mi_like_p ()
-	  && inferior_ptid != null_ptid)
-	{
-	  int num = ptid_to_global_thread_id (inferior_ptid);
+      if (uiout->is_mi_like_p () && inferior_ptid != null_ptid)
+	uiout->field_int ("current-thread-id", current_thread->global_num);
 
-	  gdb_assert (num != 0);
-	  uiout->field_int ("current-thread-id", num);
-	}
-
-      if (inferior_ptid != null_ptid && is_exited (inferior_ptid))
+      if (inferior_ptid != null_ptid && current_exited)
 	uiout->message ("\n\
 The current thread <Thread ID %s> has terminated.  See `help thread'.\n",
 			print_thread_id (inferior_thread ()));
-      else if (thread_list != NULL && inferior_ptid == null_ptid)
+      else if (any_thread && inferior_ptid == null_ptid)
 	uiout->message ("\n\
 No selected thread.  See `help thread'.\n");
     }
@@ -1349,9 +1331,9 @@ switch_to_thread_no_regs (struct thread_info *thread)
   stop_pc = ~(CORE_ADDR) 0;
 }
 
-/* Switch to no thread selected.  */
+/* See gdbthread.h.  */
 
-static void
+void
 switch_to_no_thread ()
 {
   if (inferior_ptid == null_ptid)
@@ -1362,9 +1344,9 @@ switch_to_no_thread ()
   stop_pc = ~(CORE_ADDR) 0;
 }
 
-/* Switch from one thread to another.  */
+/* See gdbthread.h.  */
 
-static void
+void
 switch_to_thread (thread_info *thr)
 {
   gdb_assert (thr != NULL);
@@ -1381,18 +1363,16 @@ switch_to_thread (thread_info *thr)
      internal event.  */
   if (thr->state != THREAD_EXITED
       && !thr->executing)
-    stop_pc = regcache_read_pc (get_thread_regcache (thr->ptid));
+    stop_pc = regcache_read_pc (get_thread_regcache (thr));
 }
 
-/* See gdbthread.h.  */
+/* See common/common-gdbthread.h.  */
 
 void
 switch_to_thread (ptid_t ptid)
 {
-  if (ptid == null_ptid)
-    switch_to_no_thread ();
-  else
-    switch_to_thread (find_thread_ptid (ptid));
+  thread_info *thr = find_thread_ptid (ptid);
+  switch_to_thread (thr);
 }
 
 static void
@@ -1476,7 +1456,7 @@ scoped_restore_current_thread::~scoped_restore_current_thread ()
      changed, so we have to recheck it here.  */
   if (inferior_ptid != null_ptid
       && m_was_stopped
-      && is_stopped (inferior_ptid)
+      && m_thread->state == THREAD_STOPPED
       && target_has_registers
       && target_has_stack
       && target_has_memory)
@@ -1494,11 +1474,9 @@ scoped_restore_current_thread::scoped_restore_current_thread ()
 
   if (inferior_ptid != null_ptid)
     {
-      thread_info *tp = find_thread_ptid (inferior_ptid);
+      thread_info *tp = inferior_thread ();
       struct frame_info *frame;
 
-      gdb_assert (tp != NULL);
-
       m_was_stopped = tp->state == THREAD_STOPPED;
       if (m_was_stopped
 	  && target_has_registers
@@ -1638,7 +1616,7 @@ thread_apply_all_command (const char *cmd, int from_tty)
       for (thread_info *thr : thr_list_cpy)
 	if (thread_alive (thr))
 	  {
-	    switch_to_thread (thr->ptid);
+	    switch_to_thread (thr);
 	    printf_filtered (_("\nThread %s (%s):\n"),
 			     print_thread_id (thr),
 			     target_pid_to_str (inferior_ptid));
@@ -1725,7 +1703,7 @@ thread_apply_command (const char *tidlist, int from_tty)
 	  continue;
 	}
 
-      switch_to_thread (tp->ptid);
+      switch_to_thread (tp);
 
       printf_filtered (_("\nThread %s (%s):\n"), print_thread_id (tp),
 		       target_pid_to_str (inferior_ptid));
@@ -1747,7 +1725,7 @@ thread_command (const char *tidstr, int from_tty)
 	{
 	  struct thread_info *tp = inferior_thread ();
 
-	  if (is_exited (inferior_ptid))
+	  if (tp->state == THREAD_EXITED)
 	    printf_filtered (_("[Current thread is %s (%s) (exited)]\n"),
 			     print_thread_id (tp),
 			     target_pid_to_str (inferior_ptid));
@@ -1871,7 +1849,7 @@ thread_select (const char *tidstr, thread_info *tp)
   if (!thread_alive (tp))
     error (_("Thread ID %s has terminated."), tidstr);
 
-  switch_to_thread (tp->ptid);
+  switch_to_thread (tp);
 
   annotate_thread_changed ();
 
@@ -1954,15 +1932,18 @@ update_thread_list (void)
 static struct value *
 thread_num_make_value_helper (struct gdbarch *gdbarch, int global)
 {
-  struct thread_info *tp = find_thread_ptid (inferior_ptid);
   int int_val;
 
-  if (tp == NULL)
+  if (inferior_ptid == null_ptid)
     int_val = 0;
-  else if (global)
-    int_val = tp->global_num;
   else
-    int_val = tp->per_inf_num;
+    {
+      thread_info *tp = inferior_thread ();
+      if (global)
+	int_val = tp->global_num;
+      else
+	int_val = tp->per_inf_num;
+    }
 
   return value_from_longest (builtin_type (gdbarch)->builtin_int, int_val);
 }