Re: [PATCH 1/5] gdb: Clean up remote.c:remote_resume

Luis Machado
2016-02-17T11:45:52Z

Just nits.

On 02/17/2016 12:44 AM, Pedro Alves wrote:
> Just some refactoring / TLC. Mainly split the old c/s/C/S packet
> handling to a separate function.
>
> gdb/ChangeLog:
> 2016-02-09 Pedro Alves <palves@redhat.com>
>
> * remote.c (remote_resume_with_hc): New function, factored out
> from ...
> (remote_resume): ... this. Always try vCont first.
> (remote_vcont_resume): Rename to ...
> (remote_resume_with_vcont): ... this. Bail out if execution
> direction is reverse.
> ---
> gdb/remote.c | 113 ++++++++++++++++++++++++++++++++---------------------------
> 1 file changed, 62 insertions(+), 51 deletions(-)
>
> diff --git a/gdb/remote.c b/gdb/remote.c
> index fa97e1e..60e2dda 100644
> --- a/gdb/remote.c
> +++ b/gdb/remote.c
> @@ -5460,6 +5460,58 @@ append_pending_thread_resumptions (char *p, char *endp, ptid_t ptid)
> return p;
> }
>
> +/* Set the target running, using the packets that use Hc
> + (c/s/C/S). */
> +
> +static void
> +remote_resume_with_hc (struct target_ops *ops,
> + ptid_t ptid, int step, enum gdb_signal siggnal)
> +{
> + struct remote_state *rs = get_remote_state ();
> + struct thread_info *thread;
> + char *buf;
> +
> + rs->last_sent_signal = siggnal;
> + rs->last_sent_step = step;
> +
> + /* The c/s/C/S resume packets use Hc, so set the continue
> + thread. */
> + if (ptid_equal (ptid, minus_one_ptid))
> + set_continue_thread (any_thread_ptid);
> + else
> + set_continue_thread (ptid);
> +
> + ALL_NON_EXITED_THREADS (thread)
> + resume_clear_thread_private_info (thread);
> +
> + buf = rs->buf;
> + if (execution_direction == EXEC_REVERSE)
> + {
> + /* We don't pass signals to the target in reverse exec mode. */
> + if (info_verbose && siggnal != GDB_SIGNAL_0)
> + warning (_(" - Can't pass signal %d to target in reverse: ignored."),
> + siggnal);
> +

Even though it is existing code, this reads a bit odd.

Should we update it to "... in reverse execution: ..." maybe?

> + if (step && packet_support (PACKET_bs) == PACKET_DISABLE)
> + error (_("Remote reverse-step not supported."));
> + if (!step && packet_support (PACKET_bc) == PACKET_DISABLE)
> + error (_("Remote reverse-continue not supported."));
> +
> + strcpy (buf, step ? "bs" : "bc");
> + }
> + else if (siggnal != GDB_SIGNAL_0)
> + {
> + buf[0] = step ? 'S' : 'C';
> + buf[1] = tohex (((int) siggnal >> 4) & 0xf);
> + buf[2] = tohex (((int) siggnal) & 0xf);
> + buf[3] = '\0';
> + }
> + else
> + strcpy (buf, step ? "s" : "c");
> +
> + putpkt (buf);
> +}
> +
> /* Resume the remote inferior by using a "vCont" packet. The thread
> to be resumed is PTID; STEP and SIGGNAL indicate whether the
> resumed thread should be single-stepped and/or signalled. If PTID
> @@ -5467,16 +5519,20 @@ append_pending_thread_resumptions (char *p, char *endp, ptid_t ptid)
> be stepped and/or signalled is given in the global INFERIOR_PTID.
> This function returns non-zero iff it resumes the inferior.
>
> - This function issues a strict subset of all possible vCont commands at the
> - moment. */
> + This function issues a strict subset of all possible vCont commands
> + at the moment. */
>
> static int
> -remote_vcont_resume (ptid_t ptid, int step, enum gdb_signal siggnal)
> +remote_resume_with_vcont (ptid_t ptid, int step, enum gdb_signal siggnal)
> {
> struct remote_state *rs = get_remote_state ();
> char *p;
> char *endp;
>
> + /* No reverse support (yet) for vCont. */
> + if (execution_direction == EXEC_REVERSE)
> + return 0;
> +

Same case as above. Also, do we need "(yet)"?

> if (packet_support (PACKET_vCont) == PACKET_SUPPORT_UNKNOWN)
> remote_vcont_probe (rs);
>
> @@ -5548,8 +5604,6 @@ remote_resume (struct target_ops *ops,
> ptid_t ptid, int step, enum gdb_signal siggnal)
> {
> struct remote_state *rs = get_remote_state ();
> - char *buf;
> - struct thread_info *thread;
>
> /* In all-stop, we can't mark REMOTE_ASYNC_GET_PENDING_EVENTS_TOKEN
> (explained in remote-notif.c:handle_notification) so
> @@ -5560,53 +5614,10 @@ remote_resume (struct target_ops *ops,
> if (!target_is_non_stop_p ())
> remote_notif_process (rs->notif_state, &notif_client_stop);
>
> - rs->last_sent_signal = siggnal;
> - rs->last_sent_step = step;
> -
> - /* The vCont packet doesn't need to specify threads via Hc. */
> - /* No reverse support (yet) for vCont. */
> - if (execution_direction != EXEC_REVERSE)
> - if (remote_vcont_resume (ptid, step, siggnal))
> - goto done;
> -
> - /* All other supported resume packets do use Hc, so set the continue
> - thread. */
> - if (ptid_equal (ptid, minus_one_ptid))
> - set_continue_thread (any_thread_ptid);
> - else
> - set_continue_thread (ptid);
> -
> - ALL_NON_EXITED_THREADS (thread)
> - resume_clear_thread_private_info (thread);
> -
> - buf = rs->buf;
> - if (execution_direction == EXEC_REVERSE)
> - {
> - /* We don't pass signals to the target in reverse exec mode. */
> - if (info_verbose && siggnal != GDB_SIGNAL_0)
> - warning (_(" - Can't pass signal %d to target in reverse: ignored."),
> - siggnal);
> -
> - if (step && packet_support (PACKET_bs) == PACKET_DISABLE)
> - error (_("Remote reverse-step not supported."));
> - if (!step && packet_support (PACKET_bc) == PACKET_DISABLE)
> - error (_("Remote reverse-continue not supported."));
> -
> - strcpy (buf, step ? "bs" : "bc");
> - }
> - else if (siggnal != GDB_SIGNAL_0)
> - {
> - buf[0] = step ? 'S' : 'C';
> - buf[1] = tohex (((int) siggnal >> 4) & 0xf);
> - buf[2] = tohex (((int) siggnal) & 0xf);
> - buf[3] = '\0';
> - }
> - else
> - strcpy (buf, step ? "s" : "c");
> -
> - putpkt (buf);
> + /* Prefer vCont, and fallback to s/c/S/C, which use Hc. */
> + if (!remote_resume_with_vcont (ptid, step, siggnal))
> + remote_resume_with_hc (ops, ptid, step, siggnal);
>
> - done:
> /* We are about to start executing the inferior, let's register it
> with the event loop. NOTE: this is the one place where all the
> execution commands end up. We could alternatively do this in each
>