From cbda14deaf49b48450207cfb0990c71c11d07a64 Mon Sep 17 00:00:00 2001 From: Andrew Burgess Date: Wed, 2 Nov 2022 13:48:42 +0000 Subject: [PATCH] gdb: new $_inferior_thread_count convenience variable Add a new convenience variable $_inferior_thread_count that contains the number of live (non-exited) threads in the current inferior. This can be used in command scripts, or breakpoint conditions, etc to adjust the behaviour for multi-threaded inferiors. This value is only stable in all-stop mode. In non-stop mode, where new threads can be started, and existing threads exit, at any time, this convenience variable can give a different value each time it is evaluated. --- gdb/NEWS | 3 +++ gdb/doc/gdb.texinfo | 14 ++++++++++++-- gdb/testsuite/gdb.base/default.exp | 1 + gdb/testsuite/gdb.multi/tids.exp | 20 ++++++++++++++++++++ gdb/thread.c | 26 ++++++++++++++++++++++++++ gdbsupport/iterator-range.h | 4 ++++ 6 files changed, 66 insertions(+), 2 deletions(-) diff --git a/gdb/NEWS b/gdb/NEWS index 3f31515297c..424e5ffd829 100644 --- a/gdb/NEWS +++ b/gdb/NEWS @@ -78,6 +78,9 @@ re-enable styling using the new "set style tui-current-position" command. +* New convenience variable $_inferior_thread_count contains the number + of live threads in the current inferior. + * New commands maintenance set ignore-prologue-end-flag on|off diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo index a41f0f7ccef..bb7b2764408 100644 --- a/gdb/doc/gdb.texinfo +++ b/gdb/doc/gdb.texinfo @@ -3642,8 +3642,15 @@ The debugger convenience variables @samp{$_thread} and @samp{$_gthread} contain, respectively, the per-inferior thread number and the global thread number of the current thread. You may find this useful in writing breakpoint conditional expressions, command scripts, -and so forth. @xref{Convenience Vars,, Convenience Variables}, for -general information on convenience variables. +and so forth. The convenience variable @samp{$_inferior_thread_count} +contains the number of live threads in the current inferior. +@xref{Convenience Vars,, Convenience Variables}, for general +information on convenience variables. + +When running in non-stop mode (@pxref{Non-Stop Mode}), where new +threads can be created, and existing threads exit, at any time, +@samp{$_inferior_thread_count} could return a different value each +time it is evaluated. If @value{GDBN} detects the program is multi-threaded, it augments the usual message about stopping at a breakpoint with the ID and name of @@ -12655,6 +12662,9 @@ The thread number of the current thread. @xref{thread numbers}. @item $_gthread The global number of the current thread. @xref{global thread numbers}. +@item $_inferior_thread_count +The number of live threads in the current inferior. @xref{Threads}. + @item $_gdb_major @itemx $_gdb_minor @vindex $_gdb_major@r{, convenience variable} diff --git a/gdb/testsuite/gdb.base/default.exp b/gdb/testsuite/gdb.base/default.exp index 29e76642830..f3e4b2867ef 100644 --- a/gdb/testsuite/gdb.base/default.exp +++ b/gdb/testsuite/gdb.base/default.exp @@ -584,6 +584,7 @@ set show_conv_list \ {$_thread = 0} \ {$_gthread = 0} \ {$_inferior = 1} \ + {$_inferior_thread_count = 0} \ {$_exception = } \ {$_probe_argc = } \ {$_probe_arg0 = } \ diff --git a/gdb/testsuite/gdb.multi/tids.exp b/gdb/testsuite/gdb.multi/tids.exp index fb7c2a29a71..23668caf18f 100644 --- a/gdb/testsuite/gdb.multi/tids.exp +++ b/gdb/testsuite/gdb.multi/tids.exp @@ -123,6 +123,8 @@ with_test_prefix "single inferior" { info_threads "" "1" gdb_test "thread" "Current thread is 1 .*" + + gdb_test "print \$_inferior_thread_count" " = 1" } # "info threads" while there are multiple inferiors should show @@ -140,8 +142,14 @@ with_test_prefix "two inferiors" { gdb_test "inferior 2" "Switching to inferior 2 .*" "switch to inferior 2" gdb_test "file ${binfile}" ".*" "load file in inferior 2" + gdb_test "print \$_inferior_thread_count" " = 0" \ + "no threads before we start the second inferior" + runto_main + gdb_test "print \$_inferior_thread_count" " = 1" \ + "no other threads started yet" + # Now that we've added another inferior, thread IDs now show the # inferior number. info_threads "" "1.1 2.1" \ @@ -153,8 +161,14 @@ with_test_prefix "two inferiors" { gdb_breakpoint "thread_function1" gdb_continue_to_breakpoint "once" + gdb_test "print \$_inferior_thread_count" " = 2" \ + "second thread started in inferior 2" gdb_test "inferior 1" "Switching to inferior 1 .*" + gdb_test "print \$_inferior_thread_count" " = 1" \ + "still only one thread in inferior 1" gdb_continue_to_breakpoint "twice" + gdb_test "print \$_inferior_thread_count" " = 2" \ + "second thread started in inferior 1" info_threads "" "1.1 1.2 2.1 2.2" \ "info threads again" @@ -187,9 +201,15 @@ with_test_prefix "two inferiors" { gdb_test "inferior 2" "Switching to inferior 2 .*" gdb_continue_to_breakpoint "once" + gdb_test "print \$_inferior_thread_count" " = 3" \ + "third thread started in inferior 2" gdb_test "inferior 1" "Switching to inferior 1 .*" + gdb_test "print \$_inferior_thread_count" " = 2" \ + "still only two threads in inferior 1" gdb_continue_to_breakpoint "twice" + gdb_test "print \$_inferior_thread_count" " = 3" \ + "third thread started in inferior 1" } thr_apply_info_thr "1" \ diff --git a/gdb/thread.c b/gdb/thread.c index 349fc01dd48..d176d1d9895 100644 --- a/gdb/thread.c +++ b/gdb/thread.c @@ -2123,6 +2123,22 @@ global_thread_id_make_value (struct gdbarch *gdbarch, struct internalvar *var, return thread_num_make_value_helper (gdbarch, 1); } +/* Return a new value for the number of non-exited threads in the current + inferior. If there are no threads in the current inferior return a + value of 0. */ + +static struct value * +inferior_thread_count_make_value (struct gdbarch *gdbarch, + struct internalvar *var, void *ignore) +{ + int int_val = 0; + + if (inferior_ptid != null_ptid) + int_val = current_inferior ()->non_exited_threads ().size (); + + return value_from_longest (builtin_type (gdbarch)->builtin_int, int_val); +} + /* Commands with a prefix of `thread'. */ struct cmd_list_element *thread_cmd_list = NULL; @@ -2142,6 +2158,14 @@ static const struct internalvar_funcs gthread_funcs = NULL, }; +/* Implementation of `_inferior_thread_count` convenience variable. */ + +static const struct internalvar_funcs inferior_thread_count_funcs = +{ + inferior_thread_count_make_value, + NULL, +}; + void _initialize_thread (); void _initialize_thread () @@ -2258,4 +2282,6 @@ When on messages about thread creation and deletion are printed."), create_internalvar_type_lazy ("_thread", &thread_funcs, NULL); create_internalvar_type_lazy ("_gthread", >hread_funcs, NULL); + create_internalvar_type_lazy ("_inferior_thread_count", + &inferior_thread_count_funcs, NULL); } diff --git a/gdbsupport/iterator-range.h b/gdbsupport/iterator-range.h index d35b03a3392..c99bdc8de07 100644 --- a/gdbsupport/iterator-range.h +++ b/gdbsupport/iterator-range.h @@ -53,6 +53,10 @@ struct iterator_range IteratorType end () const { return m_end; } + /* The number of items in this iterator_range. */ + std::size_t size () const + { return std::distance (m_begin, m_end); } + private: IteratorType m_begin, m_end; }; -- 2.30.2