Re: [PATCH v3 7/7] Add $_gthread convenience variable

[Simon Marchi <simon dot marchi at ericsson dot com>]

On 16-01-06 08:03 AM, Pedro Alves wrote:
> This commit adds a new $_gthread convenience variable, that is like
> $_thread, but holds the current thread's global thread id.
> 
> gdb/ChangeLog:
> 2016-01-06  Pedro Alves  <palves@redhat.com>
> 
> 	* NEWS: Mention $_gthread.
> 	* gdbthread.h (struct thread_info) <global_num>: Mention
> 	$_gthread.
> 	* thread.c (thread_num_make_value_helper): New function.
> 	(thread_id_make_value): Delete.
> 	(thread_id_per_inf_num_make_value, global_thread_id_make_value):
> 	New.
> 	(thread_funcs): Adjust.
> 	(gthread_funcs): New.
> 	(_initialize_thread): Register $_gthread variable.
> 
> gdb/testsuite/ChangeLog:
> 2016-01-06  Pedro Alves  <palves@redhat.com>
> 
> 	* gdb.base/default.exp: Expect $_gthread as well.
> 	* gdb.multi/tids.exp: Test $_gthread.
> 	* gdb.threads/thread-specific.exp: Test $_gthread.
> 
> gdb/doc/ChangeLog:
> 2016-01-06  Pedro Alves  <palves@redhat.com>
> 
> 	* gdb.texinfo (Threads): Document the $_gthread convenience
> 	variable.
> 	(Convenience Vars): Likewise.
> ---
>  gdb/NEWS                                      |  5 ++-
>  gdb/doc/gdb.texinfo                           |  9 +++--
>  gdb/gdbthread.h                               |  3 +-
>  gdb/testsuite/gdb.base/default.exp            |  1 +
>  gdb/testsuite/gdb.multi/tids.exp              |  3 +-
>  gdb/testsuite/gdb.threads/thread-specific.exp |  5 +++
>  gdb/thread.c                                  | 49 +++++++++++++++++++++++----
>  7 files changed, 64 insertions(+), 11 deletions(-)
> 
> diff --git a/gdb/NEWS b/gdb/NEWS
> index 32e7bd3..e4791cd 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -22,7 +22,7 @@
>  
>    GDB now maintains a second thread ID per thread, referred to as the
>    global thread ID, which is the new equivalent of thread numbers in
> -  previous releases.
> +  previous releases.  See also $_gthread below.
>  
>    For backwards compatibility, MI's thread IDs always refer to global
>    IDs.
> @@ -37,6 +37,9 @@
>  * You can use "info threads -gid" to display the global thread ID of
>    all threads.
>  
> +* The new convenience variable $_gthread holds the global number of
> +  the current thread.
> +
>  * The new convenience variable $_inferior holds the number of the
>    current inferior.
>  
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index 8ce3b01..f1e5aab 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -2937,8 +2937,10 @@ thread.  In other words, @value{GDBN} assigns a thread number to the
>  program's ``main thread'' even if the program is not multi-threaded.
>  
>  @vindex $_thread@r{, convenience variable}
> -The debugger convenience variable @samp{$_thread} contains the
> -per-inferior thread number of the current thread.  You may find this
> +@vindex $_gthread@r{, convenience variable}
> +The debugger convenience variables @samp{$_thread} and
> +@samp{$_gthread} contain, respectively, the per-inferior thread number
> +and the global thread number of the current thread.  You may find this
>  useful in writing breakpoint conditional expressions, command scripts,
>  and so forth.  @xref{Convenience Vars,, Convenience Variables}, for
>  general information on convenience variables.
> @@ -10459,6 +10461,9 @@ Programs, ,Debugging Multiple Inferiors and Programs}.
>  @item $_thread
>  The thread number of the current thread.  @xref{thread numbers}.
>  
> +@item $_gthread
> +The global number of the current thread.  @xref{global thread numbers}.
> +
>  @end table
>  
>  @node Convenience Funs
> diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
> index b8d5ac2..f021c65 100644
> --- a/gdb/gdbthread.h
> +++ b/gdb/gdbthread.h
> @@ -217,7 +217,8 @@ struct thread_info
>       thread has its own unique global ID.  */
>  
>    /* The thread's global GDB thread number.  This is exposed to MI,
> -     Python/Scheme and visible with "info threads -gid".  */
> +     Python/Scheme, visible with "info threads -gid", and is also what
> +     the $_gthread convenience variable is bound to.  */
>    int global_num;
>  
>    /* The per-inferior thread number.  This is unique in the inferior
> diff --git a/gdb/testsuite/gdb.base/default.exp b/gdb/testsuite/gdb.base/default.exp
> index fec2cde..10739ca 100644
> --- a/gdb/testsuite/gdb.base/default.exp
> +++ b/gdb/testsuite/gdb.base/default.exp
> @@ -587,6 +587,7 @@ set show_conv_list \
>  	{$_sdata = void} \
>  	{$_siginfo = void} \
>  	{$_thread = 0} \
> +	{$_gthread = 0} \
>  	{$_inferior = 1} \
>  	{$_exception = <error: No frame selected>} \
>  	{$_probe_argc = <error: No frame selected>} \
> diff --git a/gdb/testsuite/gdb.multi/tids.exp b/gdb/testsuite/gdb.multi/tids.exp
> index badb1f1..cc5f487 100644
> --- a/gdb/testsuite/gdb.multi/tids.exp
> +++ b/gdb/testsuite/gdb.multi/tids.exp
> @@ -158,8 +158,9 @@ with_test_prefix "two inferiors" {
>  	     "  2\.1 +2 +.*" \
>  	     "  2\.2 +3 +.* thread_function1 .* at .*$srcfile:.*"]
>  
> -    # Confirm the convenience variable show the expected number.
> +    # Confirm the convenience variables show the expected numbers.
>      gdb_test "p \$_thread == 2" " = 1"
> +    gdb_test "p \$_gthread == 4" " = 1"
>  
>      # Without an explicit inferior component, GDB defaults to the
>      # current inferior.  Make sure we don't refer to a thread by
> diff --git a/gdb/testsuite/gdb.threads/thread-specific.exp b/gdb/testsuite/gdb.threads/thread-specific.exp
> index 2b75b60..8f61f88 100644
> --- a/gdb/testsuite/gdb.threads/thread-specific.exp
> +++ b/gdb/testsuite/gdb.threads/thread-specific.exp
> @@ -66,7 +66,10 @@ clean_restart ${binfile}
>  gdb_test_no_output "set print sevenbit-strings"
>  gdb_test_no_output "set width 0"
>  
> +# As this test only runs a single inferior, $_thread and $_gthread
> +# should match throughout.
>  gdb_test {print $_thread} ".* = 0" "thread var when not running"
> +gdb_test {print $_gthread} ".* = 0" "gthread var when not running"
>  
>  runto_main
>  
> @@ -82,6 +85,7 @@ if {[llength $threads] == 0} {
>  }
>  
>  gdb_test {print $_thread} ".* = [lindex $threads 0]" "thread var in main"
> +gdb_test {print $_gthread} ".* = [lindex $threads 0]" "gthread var in main"
>  
>  gdb_test_multiple "break $line thread [lindex $threads 0]" \
>    "breakpoint $line main thread" {
> @@ -120,6 +124,7 @@ if { $this_breakpoint != -1 } {
>  
>  if { $this_thread != -1 } {
>      gdb_test {print $_thread} ".* = $this_thread" "thread var at break"
> +    gdb_test {print $_gthread} ".* = $this_thread" "gthread var at break"
>  } else {
>      untested "thread var at break"
>  }
> diff --git a/gdb/thread.c b/gdb/thread.c
> index 24eb83e..43441ee 100644
> --- a/gdb/thread.c
> +++ b/gdb/thread.c
> @@ -2061,18 +2061,45 @@ update_thread_list (void)
>    update_threads_executing ();
>  }
>  
> +/* Return a new value for the selected thread's id.  Return a value of
> +   0 if no thread is selected.  If GLOBAL is true, return the thread's
> +   global number.  Otherwise return the per-inferior number.  */
> +
> +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)
> +    int_val = 0;
> +  else 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);
> +}
> +
>  /* Return a new value for the selected thread's per-inferior thread
>     number.  Return a value of 0 if no thread is selected, or no
>     threads exist.  */
>  
>  static struct value *
> -thread_id_make_value (struct gdbarch *gdbarch, struct internalvar *var,
> -		      void *ignore)
> +thread_id_per_inf_num_make_value (struct gdbarch *gdbarch, struct internalvar *var,
> +				  void *ignore)
>  {
> -  struct thread_info *tp = find_thread_ptid (inferior_ptid);
> +  return thread_num_make_value_helper (gdbarch, 0);
> +}
> +
> +/* Return a new value for the selected thread's global id.  Return a
> +   value of 0 if no thread is selected, or no threads exist.  */
>  
> -  return value_from_longest (builtin_type (gdbarch)->builtin_int,
> -			     (tp ? tp->per_inf_num : 0));
> +static struct value *
> +global_thread_id_make_value (struct gdbarch *gdbarch, struct internalvar *var,
> +			     void *ignore)
> +{
> +  return thread_num_make_value_helper (gdbarch, 1);
>  }
>  
>  /* Commands with a prefix of `thread'.  */
> @@ -2082,7 +2109,16 @@ struct cmd_list_element *thread_cmd_list = NULL;
>  
>  static const struct internalvar_funcs thread_funcs =
>  {
> -  thread_id_make_value,
> +  thread_id_per_inf_num_make_value,
> +  NULL,
> +  NULL
> +};
> +
> +/* Implementation of `gthread' variable.  */
> +
> +static const struct internalvar_funcs gthread_funcs =
> +{
> +  global_thread_id_make_value,
>    NULL,
>    NULL
>  };
> @@ -2140,6 +2176,7 @@ Show printing of thread events (such as thread start and exit)."), NULL,
>           &setprintlist, &showprintlist);
>  
>    create_internalvar_type_lazy ("_thread", &thread_funcs, NULL);
> +  create_internalvar_type_lazy ("_gthread", &gthread_funcs, NULL);
>  
>    observer_attach_thread_ptid_changed (restore_current_thread_ptid_changed);
>  }
> 

LGTM.