Create private_thread_info hierarchy

There are multiple definitions of the private_thread_info structure
compiled in the same GDB build.  Because of the one definition rule, we
need to change this if we want to be able to make them non-POD (e.g. use
std::vector fields).  This patch creates a class hierarchy, with
private_thread_info being an abstract base class, and all the specific
implementations inheriting from it.

In order to poison XNEW/xfree for non-POD types, it is also needed to
get rid of the xfree in thread_info::~thread_info, which operates on an
opaque type.  This is replaced by thread_info::priv now being a
unique_ptr, which calls the destructor of the private_thread_info
subclass when the thread is being destroyed.

Including gdbthread.h from darwin-nat.h gave these errors:

/Users/simark/src/binutils-gdb/gdb/gdbthread.h:609:3: error: must use 'class' tag to refer to type 'thread_info' in this scope
  thread_info *m_thread;
  ^
  class
/usr/include/mach/thread_act.h:240:15: note: class 'thread_info' is hidden by a non-type declaration of 'thread_info' here
kern_return_t thread_info
              ^

It turns out that there is a thread_info function in the Darwin/XNU/mach API:

  http://web.mit.edu/darwin/src/modules/xnu/osfmk/man/thread_info.html

Therefore, I had to add the class keyword at a couple of places in gdbthread.h,
I don't really see a way around it.

gdb/ChangeLog:

	* gdbthread.h (private_thread_info): Define structure type, add
	virtual pure destructor.
	(thread_info) <priv>: Change type to unique_ptr.
	<private_dtor>: Remove.
	* thread.c (add_thread_with_info): Adjust to use of unique_ptr.
	(private_thread_info::~private_thread_info): Provide default
	implementation.
	(thread_info::~thread_info): Don't call private_dtor nor
	manually free priv.
	* aix-thread.c (private_thread_info): Rename to ...
	(aix_thread_info): ... this.
	(get_aix_thread_info): New.
	(sync_threadlists): Adjust.
	(iter_tid): Adjust.
	(aix_thread_resume): Adjust.
	(aix_thread_fetch_registers): Adjust.
	(aix_thread_store_registers): Adjust.
	(aix_thread_extra_thread_info): Adjust.
	* darwin-nat.h (private_thread_info): Rename to ...
	(darwin_thread_info): ... this.
	(get_darwin_thread_info): New.
	* darwin-nat.c (darwin_init_thread_list): Adjust.
	(darwin_check_new_threads): Adjust.
	(thread_info_from_private_thread_info): Adjust.
	* linux-thread-db.c (private_thread_info): Rename to ...
	(thread_db_thread_info): ... this, initialize fields.
	(get_thread_db_thread_info): New.
	<dying>: Change type to bool.
	(update_thread_state): Adjust to type rename.
	(record_thread): Adjust to type rename an use of unique_ptr.
	(thread_db_pid_to_str): Likewise.
	(thread_db_extra_thread_info): Likewise.
	(thread_db_thread_handle_to_thread_info): Likewise.
	(thread_db_get_thread_local_address): Likewise.
	* nto-tdep.h (private_thread_info): Rename to ...
	(nto_thread_info): ... this, initialize fields.
	(get_nto_thread_info): New.
	<name>: Change type to std::string.
	* nto-tdep.c (nto_extra_thread_info): Adjust to type rename and
	use of unique_ptr.
	* nto-procfs.c (update_thread_private_data_name): Adjust to
	std::string change, allocate nto_private_thread_info with new.
	(update_thread_private_data): Adjust to unique_ptr.
	* remote.c (private_thread_info): Rename to ...
	(remote_thread_info): ... this, initialize data members with
	default values.
	<extra, name>: Change type to std::string.
	<thread_handle>: Change type to non-pointer.
	(free_private_thread_info): Remove.
	(get_private_info_thread): Rename to...
	(get_remote_thread_info): ... this, change return type, adjust to
	use of unique_ptr, use remote_thread_info constructor.
	(remote_add_thread): Adjust.
	(get_private_info_ptid): Rename to...
	(get_remote_thread_info): ...this, change return type.
	(remote_thread_name): Use get_remote_thread_info, adjust to
	change to std::string.
	(struct thread_item) <~thread_item>: Remove.
	<thread_handle>: Make non pointer.
	(start_thread): Adjust to thread_item::thread_handle type
	change.
	(remote_update_thread_list): Adjust to type name change, move
	strings from temporary to long-lived object instead of
	duplicating.
	(remote_threads_extra_info): Use get_remote_thread_info.
	(process_initial_stop_replies): Likewise.
	(resume_clear_thread_private_info): Likewise.
	(remote_resume): Adjust to type name change.
	(remote_commit_resume): Use get_remote_thread_info.
	(process_stop_reply): Adjust to type name change.
	(remote_stopped_by_sw_breakpoint): Use get_remote_thread_info.
	(remote_stopped_by_hw_breakpoint): Likewise.
	(remote_stopped_by_watchpoint): Likewise.
	(remote_stopped_data_address): Likewise.
	(remote_core_of_thread): Likewise.
	(remote_thread_handle_to_thread_info): Use
	get_private_info_thread, adjust to thread_handle field type
	change.

11 files changed, 256 insertions, 169 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index 7165ec3..3696c5c 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,86 @@
 2017-11-24  Simon Marchi  <simon.marchi@polymtl.ca>
 
+	* gdbthread.h (private_thread_info): Define structure type, add
+	virtual pure destructor.
+	(thread_info) <priv>: Change type to unique_ptr.
+	<private_dtor>: Remove.
+	* thread.c (add_thread_with_info): Adjust to use of unique_ptr.
+	(private_thread_info::~private_thread_info): Provide default
+	implementation.
+	(thread_info::~thread_info): Don't call private_dtor nor
+	manually free priv.
+	* aix-thread.c (private_thread_info): Rename to ...
+	(aix_thread_info): ... this.
+	(get_aix_thread_info): New.
+	(sync_threadlists): Adjust.
+	(iter_tid): Adjust.
+	(aix_thread_resume): Adjust.
+	(aix_thread_fetch_registers): Adjust.
+	(aix_thread_store_registers): Adjust.
+	(aix_thread_extra_thread_info): Adjust.
+	* darwin-nat.h (private_thread_info): Rename to ...
+	(darwin_thread_info): ... this.
+	(get_darwin_thread_info): New.
+	* darwin-nat.c (darwin_init_thread_list): Adjust.
+	(darwin_check_new_threads): Adjust.
+	(thread_info_from_private_thread_info): Adjust.
+	* linux-thread-db.c (private_thread_info): Rename to ...
+	(thread_db_thread_info): ... this, initialize fields.
+	(get_thread_db_thread_info): New.
+	<dying>: Change type to bool.
+	(update_thread_state): Adjust to type rename.
+	(record_thread): Adjust to type rename an use of unique_ptr.
+	(thread_db_pid_to_str): Likewise.
+	(thread_db_extra_thread_info): Likewise.
+	(thread_db_thread_handle_to_thread_info): Likewise.
+	(thread_db_get_thread_local_address): Likewise.
+	* nto-tdep.h (private_thread_info): Rename to ...
+	(nto_thread_info): ... this, initialize fields.
+	(get_nto_thread_info): New.
+	<name>: Change type to std::string.
+	* nto-tdep.c (nto_extra_thread_info): Adjust to type rename and
+	use of unique_ptr.
+	* nto-procfs.c (update_thread_private_data_name): Adjust to
+	std::string change, allocate nto_private_thread_info with new.
+	(update_thread_private_data): Adjust to unique_ptr.
+	* remote.c (private_thread_info): Rename to ...
+	(remote_thread_info): ... this, initialize data members with
+	default values.
+	<extra, name>: Change type to std::string.
+	<thread_handle>: Change type to non-pointer.
+	(free_private_thread_info): Remove.
+	(get_private_info_thread): Rename to...
+	(get_remote_thread_info): ... this, change return type, adjust to
+	use of unique_ptr, use remote_thread_info constructor.
+	(remote_add_thread): Adjust.
+	(get_private_info_ptid): Rename to...
+	(get_remote_thread_info): ...this, change return type.
+	(remote_thread_name): Use get_remote_thread_info, adjust to
+	change to std::string.
+	(struct thread_item) <~thread_item>: Remove.
+	<thread_handle>: Make non pointer.
+	(start_thread): Adjust to thread_item::thread_handle type
+	change.
+	(remote_update_thread_list): Adjust to type name change, move
+	strings from temporary to long-lived object instead of
+	duplicating.
+	(remote_threads_extra_info): Use get_remote_thread_info.
+	(process_initial_stop_replies): Likewise.
+	(resume_clear_thread_private_info): Likewise.
+	(remote_resume): Adjust to type name change.
+	(remote_commit_resume): Use get_remote_thread_info.
+	(process_stop_reply): Adjust to type name change.
+	(remote_stopped_by_sw_breakpoint): Use get_remote_thread_info.
+	(remote_stopped_by_hw_breakpoint): Likewise.
+	(remote_stopped_by_watchpoint): Likewise.
+	(remote_stopped_data_address): Likewise.
+	(remote_core_of_thread): Likewise.
+	(remote_thread_handle_to_thread_info): Use
+	get_private_info_thread, adjust to thread_handle field type
+	change.
+
+2017-11-24  Simon Marchi  <simon.marchi@polymtl.ca>
+
 	* remote.c (struct thread_item): Add constructor, disable copy
 	construction and copy assignment, define default move
 	construction and move assignment.
diff --git a/gdb/aix-thread.c b/gdb/aix-thread.c
index b5c9f3b..1a1d769 100644
--- a/gdb/aix-thread.c
+++ b/gdb/aix-thread.c
@@ -84,11 +84,20 @@ static int debug_aix_thread;
 
 /* Private data attached to each element in GDB's thread list.  */
 
-struct private_thread_info {
+struct aix_thread_info : public private_thread_info
+{
   pthdb_pthread_t pdtid;	 /* thread's libpthdebug id */
   pthdb_tid_t tid;			/* kernel thread id */
 };
 
+/* Return the aix_thread_info attached to THREAD.  */
+
+static aix_thread_info *
+get_aix_thread_info (thread_info *thread)
+{
+  return static_cast<aix_thread_info *> (thread->priv.get ());
+}
+
 /* Information about a thread of which libpthdebug is aware.  */
 
 struct pd_thread {
@@ -756,10 +765,12 @@ sync_threadlists (void)
 	}
       else if (gi == gcount)
 	{
-	  thread = add_thread (ptid_build (infpid, 0, pbuf[pi].pthid));
-	  thread->priv = XNEW (struct private_thread_info);
-	  thread->priv->pdtid = pbuf[pi].pdtid;
-	  thread->priv->tid = pbuf[pi].tid;
+	  aix_thread_info *priv = new aix_thread_info;
+	  priv->pdtid = pbuf[pi].pdtid;
+	  priv->tid = pbuf[pi].tid;
+
+	  thread = add_thread_with_info (ptid_t (infpid, 0, pbuf[pi].pthid), priv);
+
 	  pi++;
 	}
       else
@@ -776,8 +787,10 @@ sync_threadlists (void)
 
 	  if (cmp_result == 0)
 	    {
-	      gbuf[gi]->priv->pdtid = pdtid;
-	      gbuf[gi]->priv->tid = tid;
+	      aix_thread_info *priv = get_aix_thread_info (gbuf[gi]);
+
+	      priv->pdtid = pdtid;
+	      priv->tid = tid;
 	      pi++;
 	      gi++;
 	    }
@@ -789,9 +802,11 @@ sync_threadlists (void)
 	  else
 	    {
 	      thread = add_thread (pptid);
-	      thread->priv = XNEW (struct private_thread_info);
-	      thread->priv->pdtid = pdtid;
-	      thread->priv->tid = tid;
+
+	      aix_thread_info *priv = new aix_thread_info;
+	      thread->priv.reset (priv);
+	      priv->pdtid = pdtid;
+	      priv->tid = tid;
 	      pi++;
 	    }
 	}
@@ -808,8 +823,9 @@ static int
 iter_tid (struct thread_info *thread, void *tidp)
 {
   const pthdb_tid_t tid = *(pthdb_tid_t *)tidp;
+  aix_thread_info *priv = get_aix_thread_info (thread);
 
-  return (thread->priv->tid == tid);
+  return priv->tid == tid;
 }
 
 /* Synchronize libpthdebug's state with the inferior and with GDB,
@@ -998,7 +1014,9 @@ aix_thread_resume (struct target_ops *ops,
 	error (_("aix-thread resume: unknown pthread %ld"),
 	       ptid_get_lwp (ptid));
 
-      tid[0] = thread->priv->tid;
+      aix_thread_info *priv = get_aix_thread_info (thread);
+
+      tid[0] = priv->tid;
       if (tid[0] == PTHDB_INVALID_TID)
 	error (_("aix-thread resume: no tid for pthread %ld"),
 	       ptid_get_lwp (ptid));
@@ -1314,10 +1332,11 @@ aix_thread_fetch_registers (struct target_ops *ops,
   else
     {
       thread = find_thread_ptid (regcache_get_ptid (regcache));
-      tid = thread->priv->tid;
+      aix_thread_info *priv = get_aix_thread_info (thread);
+      tid = priv->tid;
 
       if (tid == PTHDB_INVALID_TID)
-	fetch_regs_user_thread (regcache, thread->priv->pdtid);
+	fetch_regs_user_thread (regcache, priv->pdtid);
       else
 	fetch_regs_kernel_thread (regcache, regno, tid);
     }
@@ -1668,10 +1687,11 @@ aix_thread_store_registers (struct target_ops *ops,
   else
     {
       thread = find_thread_ptid (regcache_get_ptid (regcache));
-      tid = thread->priv->tid;
+      aix_thread_info *priv = get_aix_thread_info (thread);
+      tid = priv->tid;
 
       if (tid == PTHDB_INVALID_TID)
-	store_regs_user_thread (regcache, thread->priv->pdtid);
+	store_regs_user_thread (regcache, priv->pdtid);
       else
 	store_regs_kernel_thread (regcache, regno, tid);
     }
@@ -1759,9 +1779,10 @@ aix_thread_extra_thread_info (struct target_ops *self,
     return NULL;
 
   string_file buf;
+  aix_thread_info *priv = get_aix_thread_info (thread);
 
-  pdtid = thread->priv->pdtid;
-  tid = thread->priv->tid;
+  pdtid = priv->pdtid;
+  tid = priv->tid;
 
   if (tid != PTHDB_INVALID_TID)
     /* i18n: Like "thread-identifier %d, [state] running, suspended" */
diff --git a/gdb/darwin-nat.c b/gdb/darwin-nat.c
index ed195d9..5e708c6 100644
--- a/gdb/darwin-nat.c
+++ b/gdb/darwin-nat.c
@@ -363,9 +363,8 @@ darwin_check_new_threads (struct inferior *inf)
       if (new_ix < new_nbr && (old_ix == old_nbr || new_id < old_id))
 	{
 	  /* A thread was created.  */
-	  struct private_thread_info *pti;
+	  darwin_thread_info *pti = new darwin_thread_info;
 
-	  pti = XCNEW (darwin_thread_t);
 	  pti->gdb_port = new_id;
 	  pti->msg_state = DARWIN_RUNNING;
 
@@ -1692,16 +1691,18 @@ darwin_attach_pid (struct inferior *inf)
     push_target (darwin_ops);
 }
 
-/* Get the thread_info object corresponding to this private_thread_info.  */
+/* Get the thread_info object corresponding to this darwin_thread_info.  */
 
 static struct thread_info *
-thread_info_from_private_thread_info (private_thread_info *pti)
+thread_info_from_private_thread_info (darwin_thread_info *pti)
 {
   struct thread_info *it;
 
   ALL_THREADS (it)
     {
-      if (it->priv->gdb_port == pti->gdb_port)
+      darwin_thread_info *iter_pti = get_darwin_thread_info (it);
+
+      if (iter_pti->gdb_port == pti->gdb_port)
 	break;
     }
 
@@ -1719,7 +1720,7 @@ darwin_init_thread_list (struct inferior *inf)
 
   gdb_assert (!priv->threads.empty ());
 
-  private_thread_info *first_pti = priv->threads.front ();
+  darwin_thread_info *first_pti = priv->threads.front ();
   struct thread_info *first_thread
     = thread_info_from_private_thread_info (first_pti);
 
diff --git a/gdb/darwin-nat.h b/gdb/darwin-nat.h
index db72698..8c77923 100644
--- a/gdb/darwin-nat.h
+++ b/gdb/darwin-nat.h
@@ -18,6 +18,7 @@
 #define __DARWIN_NAT_H__
 
 #include <mach/mach.h>
+#include "gdbthread.h"
 
 /* Describe the mach exception handling state for a task.  This state is saved
    before being changed and restored when a process is detached.
@@ -69,7 +70,7 @@ enum darwin_msg_state
   DARWIN_MESSAGE
 };
 
-struct private_thread_info
+struct darwin_thread_info : public private_thread_info
 {
   /* The thread port from a GDB point of view.  */
   thread_t gdb_port;
@@ -92,7 +93,13 @@ struct private_thread_info
   /* The last exception received.  */
   struct darwin_exception_msg event;
 };
-typedef struct private_thread_info darwin_thread_t;
+typedef struct darwin_thread_info darwin_thread_t;
+
+static inline darwin_thread_info *
+get_darwin_thread_info (class thread_info *thread)
+{
+  return static_cast<darwin_thread_info *> (thread->priv.get ());
+}
 
 /* Describe an inferior.  */
 struct darwin_inferior : public private_inferior
diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
index 49fc80f..9a0de00 100644
--- a/gdb/gdbthread.h
+++ b/gdb/gdbthread.h
@@ -179,6 +179,12 @@ typedef struct value *value_ptr;
 DEF_VEC_P (value_ptr);
 typedef VEC (value_ptr) value_vec;
 
+/* Base class for target-specific thread data.  */
+struct private_thread_info
+{
+  virtual ~private_thread_info () = 0;
+};
+
 /* Threads are intrusively refcounted objects.  Being the
    user-selected thread is normally considered an implicit strong
    reference and is thus not accounted in the refcount, unlike
@@ -345,11 +351,7 @@ public:
   struct frame_id initiating_frame = null_frame_id;
 
   /* Private data used by the target vector implementation.  */
-  struct private_thread_info *priv = NULL;
-
-  /* Function that is called to free PRIVATE.  If this is NULL, then
-     xfree will be called on PRIVATE.  */
-  void (*private_dtor) (struct private_thread_info *) = NULL;
+  std::unique_ptr<private_thread_info> priv;
 
   /* Branch trace information for this thread.  */
   struct btrace_thread_info btrace {};
@@ -604,7 +606,9 @@ public:
   DISABLE_COPY_AND_ASSIGN (scoped_restore_current_thread);
 
 private:
-  thread_info *m_thread;
+  /* Use the "class" keyword here, because of a clash with a "thread_info"
+     function in the Darwin API.  */
+  class thread_info *m_thread;
   inferior *m_inf;
   frame_id m_selected_frame_id;
   int m_selected_frame_level;
@@ -683,7 +687,7 @@ extern void print_selected_thread_frame (struct ui_out *uiout,
    Selects thread THR.  TIDSTR is the original string the thread ID
    was parsed from.  This is used in the error message if THR is not
    alive anymore.  */
-extern void thread_select (const char *tidstr, thread_info *thr);
+extern void thread_select (const char *tidstr, class thread_info *thr);
 
 extern struct thread_info *thread_list;
 
diff --git a/gdb/linux-thread-db.c b/gdb/linux-thread-db.c
index ea032fc..27f9ce8 100644
--- a/gdb/linux-thread-db.c
+++ b/gdb/linux-thread-db.c
@@ -251,16 +251,21 @@ delete_thread_db_info (int pid)
 /* Use "struct private_thread_info" to cache thread state.  This is
    a substantial optimization.  */
 
-struct private_thread_info
+struct thread_db_thread_info : public private_thread_info
 {
   /* Flag set when we see a TD_DEATH event for this thread.  */
-  unsigned int dying:1;
+  bool dying = false;
 
   /* Cached thread state.  */
-  td_thrhandle_t th;
-  thread_t tid;
+  td_thrhandle_t th {};
+  thread_t tid {};
 };
-
+
+static thread_db_thread_info *
+get_thread_db_thread_info (thread_info *thread)
+{
+  return static_cast<thread_db_thread_info *> (thread->priv.get ());
+}
 
 static const char *
 thread_db_err_str (td_err_e err)
@@ -1040,7 +1045,7 @@ thread_db_inferior_created (struct target_ops *target, int from_tty)
    from libthread_db thread state information.  */
 
 static void
-update_thread_state (struct private_thread_info *priv,
+update_thread_state (thread_db_thread_info *priv,
 		     const td_thrinfo_t *ti_p)
 {
   priv->dying = (ti_p->ti_state == TD_THR_UNKNOWN
@@ -1057,8 +1062,6 @@ record_thread (struct thread_db_info *info,
 	       ptid_t ptid, const td_thrhandle_t *th_p,
 	       const td_thrinfo_t *ti_p)
 {
-  struct private_thread_info *priv;
-
   /* A thread ID of zero may mean the thread library has not
      initialized yet.  Leave private == NULL until the thread library
      has initialized.  */
@@ -1066,7 +1069,7 @@ record_thread (struct thread_db_info *info,
     return tp;
 
   /* Construct the thread's private data.  */
-  priv = XCNEW (struct private_thread_info);
+  thread_db_thread_info *priv = new thread_db_thread_info;
 
   priv->th = *th_p;
   priv->tid = ti_p->ti_tid;
@@ -1078,7 +1081,7 @@ record_thread (struct thread_db_info *info,
   if (tp == NULL || tp->state == THREAD_EXITED)
     tp = add_thread_with_info (ptid, priv);
   else
-    tp->priv = priv;
+    tp->priv.reset (priv);
 
   if (target_has_execution)
     check_thread_signals ();
@@ -1381,11 +1384,10 @@ thread_db_pid_to_str (struct target_ops *ops, ptid_t ptid)
   if (thread_info != NULL && thread_info->priv != NULL)
     {
       static char buf[64];
-      thread_t tid;
+      thread_db_thread_info *priv = get_thread_db_thread_info (thread_info);
 
-      tid = thread_info->priv->tid;
       snprintf (buf, sizeof (buf), "Thread 0x%lx (LWP %ld)",
-		(unsigned long) tid, ptid_get_lwp (ptid));
+		(unsigned long) priv->tid, ptid_get_lwp (ptid));
 
       return buf;
     }
@@ -1404,7 +1406,9 @@ thread_db_extra_thread_info (struct target_ops *self,
   if (info->priv == NULL)
     return NULL;
 
-  if (info->priv->dying)
+  thread_db_thread_info *priv = get_thread_db_thread_info (info);
+
+  if (priv->dying)
     return "Exiting";
 
   return NULL;
@@ -1434,7 +1438,9 @@ thread_db_thread_handle_to_thread_info (struct target_ops *ops,
 
   ALL_NON_EXITED_THREADS (tp)
     {
-      if (tp->inf == inf && tp->priv != NULL && handle_tid == tp->priv->tid)
+      thread_db_thread_info *priv = get_thread_db_thread_info (tp);
+
+      if (tp->inf == inf && priv != NULL && handle_tid == priv->tid)
         return tp;
     }
 
@@ -1464,9 +1470,8 @@ thread_db_get_thread_local_address (struct target_ops *ops,
     {
       td_err_e err;
       psaddr_t address;
-      struct thread_db_info *info;
-
-      info = get_thread_db_info (ptid_get_pid (ptid));
+      thread_db_info *info = get_thread_db_info (ptid_get_pid (ptid));
+      thread_db_thread_info *priv = get_thread_db_thread_info (thread_info);
 
       /* Finally, get the address of the variable.  */
       if (lm != 0)
@@ -1479,7 +1484,7 @@ thread_db_get_thread_local_address (struct target_ops *ops,
 	  /* Note the cast through uintptr_t: this interface only works if
 	     a target address fits in a psaddr_t, which is a host pointer.
 	     So a 32-bit debugger can not access 64-bit TLS through this.  */
-	  err = info->td_thr_tls_get_addr_p (&thread_info->priv->th,
+	  err = info->td_thr_tls_get_addr_p (&priv->th,
 					     (psaddr_t)(uintptr_t) lm,
 					     offset, &address);
 	}
@@ -1497,8 +1502,7 @@ thread_db_get_thread_local_address (struct target_ops *ops,
 	     PR libc/16831 due to GDB PR threads/16954 LOAD_MODULE is also NULL.
 	     The constant number 1 depends on GNU __libc_setup_tls
 	     initialization of l_tls_modid to 1.  */
-	  err = info->td_thr_tlsbase_p (&thread_info->priv->th,
-					1, &address);
+	  err = info->td_thr_tlsbase_p (&priv->th, 1, &address);
 	  address = (char *) address + offset;
 	}
 
diff --git a/gdb/nto-procfs.c b/gdb/nto-procfs.c
index 1da1a98..04f2213 100644
--- a/gdb/nto-procfs.c
+++ b/gdb/nto-procfs.c
@@ -248,38 +248,24 @@ static void
 update_thread_private_data_name (struct thread_info *new_thread,
 				 const char *newname)
 {
-  int newnamelen;
-  struct private_thread_info *pti;
+  nto_thread_info *pti = get_nto_thread_info (new_thread);
 
   gdb_assert (newname != NULL);
   gdb_assert (new_thread != NULL);
-  newnamelen = strlen (newname);
-  if (!new_thread->priv)
-    {
-      new_thread->priv = xmalloc (offsetof (struct private_thread_info,
-					       name)
-				     + newnamelen + 1);
-      memcpy (new_thread->priv->name, newname, newnamelen + 1);
-    }
-  else if (strcmp (newname, new_thread->priv->name) != 0)
+
+  if (pti)
     {
-      /* Reallocate if neccessary.  */
-      int oldnamelen = strlen (new_thread->priv->name);
-
-      if (oldnamelen < newnamelen)
-	new_thread->priv = xrealloc (new_thread->priv,
-					offsetof (struct private_thread_info,
-						  name)
-					+ newnamelen + 1);
-      memcpy (new_thread->priv->name, newname, newnamelen + 1);
+      pti = new nto_thread_info;
+      new_thread->priv.reset (pti);
     }
+
+  pti->name = newname;
 }
 
 static void 
 update_thread_private_data (struct thread_info *new_thread, 
 			    pthread_t tid, int state, int flags)
 {
-  struct private_thread_info *pti;
   procfs_info pidinfo;
   struct _thread_name *tn;
   procfs_threadctl tctl;
@@ -306,7 +292,7 @@ update_thread_private_data (struct thread_info *new_thread,
 
   update_thread_private_data_name (new_thread, tn->name_buf);
 
-  pti = (struct private_thread_info *) new_thread->priv;
+  nto_thread_info *pti = get_nto_thread_info (new_thread);
   pti->tid = tid;
   pti->state = state;
   pti->flags = flags;
diff --git a/gdb/nto-tdep.c b/gdb/nto-tdep.c
index 27bd191..8286db2 100644
--- a/gdb/nto-tdep.c
+++ b/gdb/nto-tdep.c
@@ -380,9 +380,13 @@ static const char *nto_thread_state_str[] =
 const char *
 nto_extra_thread_info (struct target_ops *self, struct thread_info *ti)
 {
-  if (ti && ti->priv
-      && ti->priv->state < ARRAY_SIZE (nto_thread_state_str))
-    return (char *)nto_thread_state_str [ti->priv->state];
+  if (ti != NULL && ti->priv != NULL)
+    {
+      nto_thread_info *priv = get_nto_thread_info (ti);
+
+      if (priv->state < ARRAY_SIZE (nto_thread_state_str))
+	return nto_thread_state_str [priv->state];
+    }
   return "";
 }
 
diff --git a/gdb/nto-tdep.h b/gdb/nto-tdep.h
index afe3452..f63f13c 100644
--- a/gdb/nto-tdep.h
+++ b/gdb/nto-tdep.h
@@ -134,14 +134,20 @@ typedef struct _debug_regs
   qnx_reg64 padding[1024];
 } nto_regset_t;
 
-struct private_thread_info
+struct nto_thread_info : public private_thread_info
 {
-  short tid;
-  unsigned char state;
-  unsigned char flags;
-  char name[1];
+  short tid = 0;
+  unsigned char state = 0;
+  unsigned char flags = 0;
+  std::string name;
 };
 
+static inline nto_thread_info *
+get_nto_thread_info (thread_info *thread)
+{
+  return static_cast<nto_thread_info *> (thread->priv.get ());
+}
+
 /* Per-inferior data, common for both procfs and remote.  */
 struct nto_inferior_data
 {
diff --git a/gdb/remote.c b/gdb/remote.c
index 8c76b7e..0a62ae0 100644
--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -439,23 +439,23 @@ struct remote_state
   struct readahead_cache readahead_cache;
 };
 
-/* Private data that we'll store in (struct thread_info)->private.  */
-struct private_thread_info
+/* Private data that we'll store in (struct thread_info)->priv.  */
+struct remote_thread_info : public private_thread_info
 {
-  char *extra;
-  char *name;
-  int core;
+  std::string extra;
+  std::string name;
+  int core = -1;
 
   /* Thread handle, perhaps a pthread_t or thread_t value, stored as a
      sequence of bytes.  */
-  gdb::byte_vector *thread_handle;
+  gdb::byte_vector thread_handle;
 
   /* Whether the target stopped for a breakpoint/watchpoint.  */
-  enum target_stop_reason stop_reason;
+  enum target_stop_reason stop_reason = TARGET_STOPPED_BY_NO_REASON;
 
   /* This is set to the data address of the access causing the target
      to stop for a watchpoint.  */
-  CORE_ADDR watch_data_address;
+  CORE_ADDR watch_data_address = 0;
 
   /* Fields used by the vCont action coalescing implemented in
      remote_resume / remote_commit_resume.  remote_resume stores each
@@ -465,26 +465,17 @@ struct private_thread_info
 
   /* True if the last target_resume call for this thread was a step
      request, false if a continue request.  */
-  int last_resume_step;
+  int last_resume_step = 0;
 
   /* The signal specified in the last target_resume call for this
      thread.  */
-  enum gdb_signal last_resume_sig;
+  gdb_signal last_resume_sig = GDB_SIGNAL_0;
 
   /* Whether this thread was already vCont-resumed on the remote
      side.  */
-  int vcont_resumed;
+  int vcont_resumed = 0;
 };
 
-static void
-free_private_thread_info (struct private_thread_info *info)
-{
-  xfree (info->extra);
-  xfree (info->name);
-  delete info->thread_handle;
-  xfree (info);
-}
-
 /* This data could be associated with a target, but we do not always
    have access to the current target when we need it, so for now it is
    static.  This will be fine for as long as only one target is in use
@@ -1826,8 +1817,7 @@ remote_add_inferior (int fake_pid_p, int pid, int attached,
   return inf;
 }
 
-static struct private_thread_info *
-  get_private_info_thread (struct thread_info *info);
+static remote_thread_info *get_remote_thread_info (thread_info *thread);
 
 /* Add thread PTID to GDB's thread list.  Tag it as executing/running
    according to RUNNING.  */
@@ -1849,7 +1839,7 @@ remote_add_thread (ptid_t ptid, int running, int executing)
   else
     thread = add_thread (ptid);
 
-  get_private_info_thread (thread)->vcont_resumed = executing;
+  get_remote_thread_info (thread)->vcont_resumed = executing;
   set_executing (ptid, executing);
   set_running (ptid, running);
 }
@@ -1946,39 +1936,25 @@ remote_notice_new_inferior (ptid_t currthread, int executing)
 
 /* Return THREAD's private thread data, creating it if necessary.  */
 
-static struct private_thread_info *
-get_private_info_thread (struct thread_info *thread)
+static remote_thread_info *
+get_remote_thread_info (thread_info *thread)
 {
   gdb_assert (thread != NULL);
 
   if (thread->priv == NULL)
-    {
-      struct private_thread_info *priv = XNEW (struct private_thread_info);
-
-      thread->private_dtor = free_private_thread_info;
-      thread->priv = priv;
-
-      priv->core = -1;
-      priv->extra = NULL;
-      priv->name = NULL;
-      priv->name = NULL;
-      priv->last_resume_step = 0;
-      priv->last_resume_sig = GDB_SIGNAL_0;
-      priv->vcont_resumed = 0;
-      priv->thread_handle = nullptr;
-    }
+    thread->priv.reset (new remote_thread_info);
 
-  return thread->priv;
+  return static_cast<remote_thread_info *> (thread->priv.get ());
 }
 
 /* Return PTID's private thread data, creating it if necessary.  */
 
-static struct private_thread_info *
-get_private_info_ptid (ptid_t ptid)
+static remote_thread_info *
+get_remote_thread_info (ptid_t ptid)
 {
   struct thread_info *info = find_thread_ptid (ptid);
 
-  return get_private_info_thread (info);
+  return get_remote_thread_info (info);
 }
 
 /* Call this function as a result of
@@ -2294,7 +2270,7 @@ static const char *
 remote_thread_name (struct target_ops *ops, struct thread_info *info)
 {
   if (info->priv != NULL)
-    return info->priv->name;
+    return get_remote_thread_info (info)->name.c_str ();
 
   return NULL;
 }
@@ -2997,7 +2973,6 @@ struct thread_item
 
   /* The thread handle associated with the thread.  */
   gdb::byte_vector thread_handle;
-
 };
 
 /* Context passed around to the various methods listing remote
@@ -3285,7 +3260,6 @@ remote_update_thread_list (struct target_ops *ops)
 	{
 	  if (item.ptid != null_ptid)
 	    {
-	      struct private_thread_info *info;
 	      /* In non-stop mode, we assume new found threads are
 		 executing until proven otherwise with a stop reply.
 		 In all-stop, we can only get here if all threads are
@@ -3294,12 +3268,11 @@ remote_update_thread_list (struct target_ops *ops)
 
 	      remote_notice_new_inferior (item.ptid, executing);
 
-	      info = get_private_info_ptid (item.ptid);
+	      remote_thread_info *info = get_remote_thread_info (item.ptid);
 	      info->core = item.core;
-	      info->extra = xstrdup (item.extra.c_str ());
-	      info->name = xstrdup (item.name.c_str ());
-	      info->thread_handle
-		= new gdb::byte_vector (std::move (item.thread_handle));
+	      info->extra = std::move (item.extra);
+	      info->name = std::move (item.name);
+	      info->thread_handle = std::move (item.thread_handle);
 	    }
 	}
     }
@@ -3348,8 +3321,8 @@ remote_threads_extra_info (struct target_ops *self, struct thread_info *tp)
     {
       struct thread_info *info = find_thread_ptid (tp->ptid);
 
-      if (info && info->priv)
-	return info->priv->extra;
+      if (info != NULL && info->priv != NULL)
+	return get_remote_thread_info (info)->extra.c_str ();
       else
 	return NULL;
     }
@@ -3925,7 +3898,7 @@ process_initial_stop_replies (int from_tty)
 
       set_executing (event_ptid, 0);
       set_running (event_ptid, 0);
-      thread->priv->vcont_resumed = 0;
+      get_remote_thread_info (thread)->vcont_resumed = 0;
     }
 
   /* "Notice" the new inferiors before anything related to
@@ -5549,8 +5522,10 @@ resume_clear_thread_private_info (struct thread_info *thread)
 {
   if (thread->priv != NULL)
     {
-      thread->priv->stop_reason = TARGET_STOPPED_BY_NO_REASON;
-      thread->priv->watch_data_address = 0;
+      remote_thread_info *priv = get_remote_thread_info (thread);
+
+      priv->stop_reason = TARGET_STOPPED_BY_NO_REASON;
+      priv->watch_data_address = 0;
     }
 }
 
@@ -5730,12 +5705,13 @@ remote_resume (struct target_ops *ops,
      to do vCont action coalescing.  */
   if (target_is_non_stop_p () && execution_direction != EXEC_REVERSE)
     {
-      struct private_thread_info *remote_thr;
+      remote_thread_info *remote_thr;
 
       if (ptid_equal (minus_one_ptid, ptid) || ptid_is_pid (ptid))
-	remote_thr = get_private_info_ptid (inferior_ptid);
+	remote_thr = get_remote_thread_info (inferior_ptid);
       else
-	remote_thr = get_private_info_ptid (ptid);
+	remote_thr = get_remote_thread_info (ptid);
+
       remote_thr->last_resume_step = step;
       remote_thr->last_resume_sig = siggnal;
       return;
@@ -6001,7 +5977,7 @@ remote_commit_resume (struct target_ops *ops)
   /* Threads first.  */
   ALL_NON_EXITED_THREADS (tp)
     {
-      struct private_thread_info *remote_thr = tp->priv;
+      remote_thread_info *remote_thr = get_remote_thread_info (tp);
 
       if (!tp->executing || remote_thr->vcont_resumed)
 	continue;
@@ -7218,8 +7194,6 @@ process_stop_reply (struct stop_reply *stop_reply,
       && status->kind != TARGET_WAITKIND_SIGNALLED
       && status->kind != TARGET_WAITKIND_NO_RESUMED)
     {
-      struct private_thread_info *remote_thr;
-
       /* Expedited registers.  */
       if (stop_reply->regcache)
 	{
@@ -7240,7 +7214,7 @@ process_stop_reply (struct stop_reply *stop_reply,
 	}
 
       remote_notice_new_inferior (ptid, 0);
-      remote_thr = get_private_info_ptid (ptid);
+      remote_thread_info *remote_thr = get_remote_thread_info (ptid);
       remote_thr->core = stop_reply->core;
       remote_thr->stop_reason = stop_reply->stop_reason;
       remote_thr->watch_data_address = stop_reply->watch_data_address;
@@ -10037,7 +10011,8 @@ remote_stopped_by_sw_breakpoint (struct target_ops *ops)
   struct thread_info *thread = inferior_thread ();
 
   return (thread->priv != NULL
-	  && thread->priv->stop_reason == TARGET_STOPPED_BY_SW_BREAKPOINT);
+	  && (get_remote_thread_info (thread)->stop_reason
+	      == TARGET_STOPPED_BY_SW_BREAKPOINT));
 }
 
 /* The to_supports_stopped_by_sw_breakpoint method of target
@@ -10057,7 +10032,8 @@ remote_stopped_by_hw_breakpoint (struct target_ops *ops)
   struct thread_info *thread = inferior_thread ();
 
   return (thread->priv != NULL
-	  && thread->priv->stop_reason == TARGET_STOPPED_BY_HW_BREAKPOINT);
+	  && (get_remote_thread_info (thread)->stop_reason
+	      == TARGET_STOPPED_BY_HW_BREAKPOINT));
 }
 
 /* The to_supports_stopped_by_hw_breakpoint method of target
@@ -10075,7 +10051,8 @@ remote_stopped_by_watchpoint (struct target_ops *ops)
   struct thread_info *thread = inferior_thread ();
 
   return (thread->priv != NULL
-	  && thread->priv->stop_reason == TARGET_STOPPED_BY_WATCHPOINT);
+	  && (get_remote_thread_info (thread)->stop_reason
+	      == TARGET_STOPPED_BY_WATCHPOINT));
 }
 
 static int
@@ -10084,9 +10061,10 @@ remote_stopped_data_address (struct target_ops *target, CORE_ADDR *addr_p)
   struct thread_info *thread = inferior_thread ();
 
   if (thread->priv != NULL
-      && thread->priv->stop_reason == TARGET_STOPPED_BY_WATCHPOINT)
+      && (get_remote_thread_info (thread)->stop_reason
+	  == TARGET_STOPPED_BY_WATCHPOINT))
     {
-      *addr_p = thread->priv->watch_data_address;
+      *addr_p = get_remote_thread_info (thread)->watch_data_address;
       return 1;
     }
 
@@ -12923,8 +12901,9 @@ remote_core_of_thread (struct target_ops *ops, ptid_t ptid)
 {
   struct thread_info *info = find_thread_ptid (ptid);
 
-  if (info && info->priv)
-    return info->priv->core;
+  if (info != NULL && info->priv != NULL)
+    return get_remote_thread_info (info)->core;
+
   return -1;
 }
 
@@ -13521,14 +13500,14 @@ remote_thread_handle_to_thread_info (struct target_ops *ops,
 
   ALL_NON_EXITED_THREADS (tp)
     {
-      struct private_thread_info *priv = get_private_info_thread (tp);
+      remote_thread_info *priv = get_remote_thread_info (tp);
 
       if (tp->inf == inf && priv != NULL)
         {
-	  if (handle_len != priv->thread_handle->size ())
+	  if (handle_len != priv->thread_handle.size ())
 	    error (_("Thread handle size mismatch: %d vs %zu (from remote)"),
-	           handle_len, priv->thread_handle->size ());
-	  if (memcmp (thread_handle, priv->thread_handle->data (),
+	           handle_len, priv->thread_handle.size ());
+	  if (memcmp (thread_handle, priv->thread_handle.data (),
 	              handle_len) == 0)
 	    return tp;
 	}
diff --git a/gdb/thread.c b/gdb/thread.c
index d71568e..052549a 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -316,11 +316,11 @@ add_thread_silent (ptid_t ptid)
 }
 
 struct thread_info *
-add_thread_with_info (ptid_t ptid, struct private_thread_info *priv)
+add_thread_with_info (ptid_t ptid, private_thread_info *priv)
 {
   struct thread_info *result = add_thread_silent (ptid);
 
-  result->priv = priv;
+  result->priv.reset (priv);
 
   if (print_thread_events)
     printf_unfiltered (_("[New %s]\n"), target_pid_to_str (ptid));
@@ -335,6 +335,8 @@ add_thread (ptid_t ptid)
   return add_thread_with_info (ptid, NULL);
 }
 
+private_thread_info::~private_thread_info () = default;
+
 thread_info::thread_info (struct inferior *inf_, ptid_t ptid_)
   : ptid (ptid_), inf (inf_)
 {
@@ -351,14 +353,6 @@ thread_info::thread_info (struct inferior *inf_, ptid_t ptid_)
 
 thread_info::~thread_info ()
 {
-  if (this->priv)
-    {
-      if (this->private_dtor)
-	this->private_dtor (this->priv);
-      else
-	xfree (this->priv);
-    }
-
   xfree (this->name);
 }