Re: [PATCH v3] gdb/record: fix missing "no history" message in some situations

[Guinevere Larsen <guinevere@redhat.com>]

I have pushed this patch. Let me know if this causes any further issues, 
and I'll be happy to fix them

On 10/26/26 3:38 PM, Guinevere Larsen wrote:
> Ping!
>
> If there are no further feedbacks on this, I plan to push this series 
> early thursday.
>
> On 10/19/26 3:56 PM, Guinevere Larsen wrote:
>> I recently noticed that the end of recorded history message wasn't
>> shown when replaying an inferior until the end for the first time, it
>> was only shown when trying to reverse past the start of
>> history. Executing forward past the end will not warn the user that
>> recording is going to start again, it just does so. This is the
>> behavior before the change:
>>
>>      (gdb) start
>>      Temporary breakpoint 1 at 0x40044a: file t.c, line 2.
>>      Starting program: /home/glarsen/a.out
>>      [Thread debugging using libthread_db enabled]
>>      Using host libthread_db library "/lib64/libthread_db.so.1".
>>
>>      Temporary breakpoint 1, main () at t.c:2
>>      2      int x = 0;
>>      (gdb) record
>>      (gdb) n
>>      3      x ++;
>>      (gdb) rn
>>      2      int x = 0;
>>      (gdb) rn
>>
>>      Reached end of recorded history; stopping.
>>      Backward execution from here not possible.
>>      main () at t.c:2
>>      2      int x = 0;
>>      (gdb) n
>>      3      x ++;
>>      (gdb) n
>>      4      return x;
>>
>> And this is the behavior after the change:
>>
>>      (gdb) start
>>      Temporary breakpoint 1 at 0x40044a: file t.c, line 2.
>>      Starting program: /home/glarsen/a.out
>>      [Thread debugging using libthread_db enabled]
>>      Using host libthread_db library "/lib64/libthread_db.so.1".
>>
>>      Temporary breakpoint 1, main () at t.c:2
>>      2      int x = 0;
>>      (gdb) record
>>      (gdb) n
>>      3      x ++;
>>      (gdb) rn
>>
>>      Reached end of recorded history; stopping.
>>      Backward execution from here not possible.
>>      main () at t.c:2
>>      2      int x = 0;
>>      (gdb) n
>>
>>      Reached end of recorded history; stopping.
>>      Following forward execution will be added to history.
>>      main () at t.c:3
>>      3      x ++;
>>      (gdb)
>>
>> This was happening because the out-of-history was only set when it
>> caused the execution loop to stop, so using "next" to reach the end of
>> history, for example, wouldn't trigger it as I expected.  This commit
>> fixes that to make out-of-history check only happen after the loop is
>> finished.
>>
>> Also add a test to ensure we don't regress again.
>> ---
>>
>> I seem to have forgotten to send or push this patch. I've fixed all 
>> comments from Andrew on v2, but seeing as it's been a while and he 
>> never replied with an explicit ok for pushing, I figure it's safer to 
>> send a v3, just to be sure.
>>
>> ---
>>   gdb/record-full.c                        | 21 +++++--------
>>   gdb/testsuite/gdb.reverse/no-history.c   | 26 +++++++++++++++
>>   gdb/testsuite/gdb.reverse/no-history.exp | 40 ++++++++++++++++++++++++
>>   3 files changed, 73 insertions(+), 14 deletions(-)
>>   create mode 100644 gdb/testsuite/gdb.reverse/no-history.c
>>   create mode 100644 gdb/testsuite/gdb.reverse/no-history.exp
>>
>> diff --git a/gdb/record-full.c b/gdb/record-full.c
>> index 50da022bb52..7b1d64069c7 100644
>> --- a/gdb/record-full.c
>> +++ b/gdb/record-full.c
>> @@ -1362,19 +1362,10 @@ record_full_wait_1 (struct target_ops *ops,
>>             /* Check for beginning and end of log.  */
>>             if (execution_direction == EXEC_REVERSE
>>             && record_full_next_insn < 0)
>> -        {
>> -          /* Hit beginning of record log in reverse.  */
>> -          status->set_no_history ();
>> -          record_full_next_insn = 0;
>> -          break;
>> -        }
>> -          if (execution_direction != EXEC_REVERSE
>> -          && record_full_next_insn == record_full_log.size ())
>> -        {
>> -          /* Hit end of record log going forward.  */
>> -          status->set_no_history ();
>> -          break;
>> -        }
>> +        break;
>> +          else if (execution_direction != EXEC_REVERSE
>> +               && record_full_next_insn == record_full_log.size ())
>> +        break;
>>               record_full_log[record_full_next_insn].exec_insn 
>> (regcache);
>>   @@ -1424,11 +1415,13 @@ record_full_wait_1 (struct target_ops *ops,
>>           {
>>             gdb_assert (execution_direction == EXEC_REVERSE);
>>             record_full_next_insn = 0;
>> +          status->set_no_history ();
>>           }
>> -      else if (record_full_next_insn > record_full_log.size ())
>> +      else if (record_full_next_insn >= record_full_log.size ())
>>           {
>>             gdb_assert (execution_direction == EXEC_FORWARD);
>>             record_full_next_insn = record_full_log.size ();
>> +          status->set_no_history ();
>>           }
>>         /* Reset the current instruction to point to the one to be 
>> replayed
>>            moving forward.  */
>> diff --git a/gdb/testsuite/gdb.reverse/no-history.c 
>> b/gdb/testsuite/gdb.reverse/no-history.c
>> new file mode 100644
>> index 00000000000..cb23e3b397e
>> --- /dev/null
>> +++ b/gdb/testsuite/gdb.reverse/no-history.c
>> @@ -0,0 +1,26 @@
>> +/* This testcase is part of GDB, the GNU debugger.
>> +
>> +   Copyright 2026 Free Software Foundation, Inc.
>> +
>> +   This program is free software; you can redistribute it and/or modify
>> +   it under the terms of the GNU General Public License as published by
>> +   the Free Software Foundation; either version 3 of the License, or
>> +   (at your option) any later version.
>> +
>> +   This program is distributed in the hope that it will be useful,
>> +   but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> +   GNU General Public License for more details.
>> +
>> +   You should have received a copy of the GNU General Public License
>> +   along with this program.  If not, see 
>> <http://www.gnu.org/licenses/>.  */
>> +
>> +/* Test that GDB is printing the no-history messages as it should.  */
>> +
>> +int
>> +main ()
>> +{
>> +  int x = 0;
>> +  x++;
>> +  return 0;
>> +}
>> diff --git a/gdb/testsuite/gdb.reverse/no-history.exp 
>> b/gdb/testsuite/gdb.reverse/no-history.exp
>> new file mode 100644
>> index 00000000000..264ca7f84bf
>> --- /dev/null
>> +++ b/gdb/testsuite/gdb.reverse/no-history.exp
>> @@ -0,0 +1,40 @@
>> +# Copyright 2026 Free Software Foundation, Inc.
>> +
>> +# This program is free software; you can redistribute it and/or modify
>> +# it under the terms of the GNU General Public License as published by
>> +# the Free Software Foundation; either version 3 of the License, or
>> +# (at your option) any later version.
>> +#
>> +# This program is distributed in the hope that it will be useful,
>> +# but WITHOUT ANY WARRANTY; without even the implied warranty of
>> +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> +# GNU General Public License for more details.
>> +#
>> +# You should have received a copy of the GNU General Public License
>> +# along with this program.  If not, see 
>> <http://www.gnu.org/licenses/>.  */
>> +
>> +# This file is part of the GDB testsuite.  It tests the printing of
>> +# the "out of history" warnings.
>> +
>> +require supports_reverse
>> +
>> +standard_testfile
>> +
>> +if { [prepare_for_testing "failed to prepare" $testfile $srcfile] } {
>> +    return
>> +}
>> +
>> +runto_main
>> +
>> +if {[supports_process_record]} {
>> +    # Activate process record/replay
>> +    gdb_test_no_output "record" "turn on process record"
>> +}
>> +
>> +gdb_test "next" "x\\\+\\\+;" "Record a line of execution"
>> +gdb_test "reverse-next" \
>> +    ".*Reached end of recorded history; stopping.*" \
>> +    "Reverse to start of history"
>> +gdb_test "next" \
>> +    ".*Reached end of recorded history; stopping.*" \
>> +    "Forward to end of history"
>>
>> base-commit: 91dc787c65d9f5f9aba59bcadbee8c3d14a53236
>
-- 
Cheers,
Guinevere Larsen
it/its
she/her (deprecated)