Re: [PATCH] gdb/mi: add no-history stop reason

Andrew Burgess via Gdb-patches
2023-01-03T12:04:27Z

Bruno Larsen via Gdb-patches <gdb-patches@sourceware.org> writes:

> When executing in reverse and runs out of recorded history, GDB prints
> a warning to the user, but does not add a reason in the stopped record,
> for example:
>
> *stopped,frame={addr="0x000000000040113e",func="main",args=[],file="/home/blarsen/Documents/fsf_build/gdb/testsuite/../../../binutils-gdb/gdb/testsuite/gdb.reverse/solib-reverse.c",fullname="/home/blarsen/Documents/binutils-gdb/gdb/testsuite/gdb.reverse/solib-reverse.c",line="27",arch="i386:x86-64"},thread-id="1",stopped-threads="all",core="1"
>
> This problem was reported as record/29260.
>
> This commit adds the reason no-history to the record, making it easier
> for interfaces using the mi interpreter to report the result.
>
> Bug: https://sourceware.org/bugzilla/show_bug.cgi?id=29260
> ---
> gdb/NEWS | 5 +++++
> gdb/doc/gdb.texinfo | 2 ++
> gdb/infrun.c | 5 ++++-
> 3 files changed, 11 insertions(+), 1 deletion(-)

I think this should have a test added to gdb.reverse/.

>
> diff --git a/gdb/NEWS b/gdb/NEWS
> index e61f06081de..3673bed8f46 100644
> --- a/gdb/NEWS
> +++ b/gdb/NEWS
> @@ -5,6 +5,11 @@
>
> * MI version 1 has been removed.
>
> +* MI changes
> +
> +** mi now reports 'no_history' as a stop reason when hitting the end of the

s/no_history/no-history/

> + reverse execution history.
> +
> *** Changes in GDB 13
>
> * MI version 1 is deprecated, and will be removed in GDB 14.
> diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
> index a72b2b9eb26..8982151a7e3 100644
> --- a/gdb/doc/gdb.texinfo
> +++ b/gdb/doc/gdb.texinfo
> @@ -30851,6 +30851,8 @@ The inferior returned from a system call. This is reported when
> @item exec
> The inferior called @code{exec}. This is reported when @code{catch exec}
> (@pxref{Set Catchpoints}) has been used.
> +@item no-history
> +There isn't enough history recorded to continue reverse execution.
> @end table
>
> The @var{id} field identifies the global thread ID of the thread
> diff --git a/gdb/infrun.c b/gdb/infrun.c
> index d5f97e33625..601d1a54701 100644
> --- a/gdb/infrun.c
> +++ b/gdb/infrun.c
> @@ -8406,7 +8406,10 @@ print_signal_received_reason (struct ui_out *uiout, enum gdb_signal siggnal)
> void
> print_no_history_reason (struct ui_out *uiout)
> {
> - uiout->text ("\nNo more reverse-execution history.\n");
> + if (uiout->is_mi_like_p ())
> + uiout->field_string ("reason", "no-history");

If we look at how similar cases are handled in e.g. breakpoint.c, then
we see that GDB looks up all these stop reason strings by calling
async_reason_lookup.

So, I think we should add a new reason to 'enum async_reply_reason' in
mi/mi-common.h. The 'no-history' string should be added to
'async_reason_string_lookup' in mi-common.c, and then you should call
async_reason_lookup here.

Thanks,
Andrew
> + else
> + uiout->text ("\nNo more reverse-execution history.\n");
> }
>
> /* Print current location without a level number, if we have changed
> --
> 2.39.0