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Factor out code to re-resume stepped thread
Just a code refactor, no funcionality change intended. gdb/ChangeLog: 2015-08-07 Pedro Alves <palves@redhat.com> * infrun.c (keep_going_stepped_thread): New function, factored out from ... (switch_back_to_stepped_thread): ... here.
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Pedro Alves
parent
8b06156348
commit
2ac7589cfe
@ -1,3 +1,9 @@
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2015-08-07 Pedro Alves <palves@redhat.com>
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* infrun.c (keep_going_stepped_thread): New function, factored out
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from ...
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(switch_back_to_stepped_thread): ... here.
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2015-08-07 Pedro Alves <palves@redhat.com>
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* infrun.c (currently_stepping): Extend intro comment.
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202
gdb/infrun.c
202
gdb/infrun.c
@ -1877,6 +1877,7 @@ reset_ecs (struct execution_control_state *ecs, struct thread_info *tp)
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static void keep_going_pass_signal (struct execution_control_state *ecs);
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static void prepare_to_wait (struct execution_control_state *ecs);
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static int keep_going_stepped_thread (struct thread_info *tp);
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static int thread_still_needs_step_over (struct thread_info *tp);
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/* Are there any pending step-over requests? If so, run all we can
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@ -5748,112 +5749,125 @@ switch_back_to_stepped_thread (struct execution_control_state *ecs)
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if (stepping_thread != NULL)
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{
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struct frame_info *frame;
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struct gdbarch *gdbarch;
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tp = stepping_thread;
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/* If the stepping thread exited, then don't try to switch
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back and resume it, which could fail in several different
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ways depending on the target. Instead, just keep going.
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We can find a stepping dead thread in the thread list in
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two cases:
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- The target supports thread exit events, and when the
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target tries to delete the thread from the thread list,
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inferior_ptid pointed at the exiting thread. In such
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case, calling delete_thread does not really remove the
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thread from the list; instead, the thread is left listed,
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with 'exited' state.
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- The target's debug interface does not support thread
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exit events, and so we have no idea whatsoever if the
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previously stepping thread is still alive. For that
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reason, we need to synchronously query the target
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now. */
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if (is_exited (tp->ptid)
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|| !target_thread_alive (tp->ptid))
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{
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if (debug_infrun)
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fprintf_unfiltered (gdb_stdlog,
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"infrun: not switching back to "
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"stepped thread, it has vanished\n");
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delete_thread (tp->ptid);
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return 0;
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}
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if (debug_infrun)
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fprintf_unfiltered (gdb_stdlog,
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"infrun: switching back to stepped thread\n");
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reset_ecs (ecs, tp);
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switch_to_thread (tp->ptid);
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stop_pc = regcache_read_pc (get_thread_regcache (tp->ptid));
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frame = get_current_frame ();
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gdbarch = get_frame_arch (frame);
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/* If the PC of the thread we were trying to single-step has
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changed, then that thread has trapped or been signaled,
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but the event has not been reported to GDB yet. Re-poll
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the target looking for this particular thread's event
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(i.e. temporarily enable schedlock) by:
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- setting a break at the current PC
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- resuming that particular thread, only (by setting
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trap expected)
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This prevents us continuously moving the single-step
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breakpoint forward, one instruction at a time,
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overstepping. */
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if (stop_pc != tp->prev_pc)
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if (keep_going_stepped_thread (stepping_thread))
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{
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ptid_t resume_ptid;
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if (debug_infrun)
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fprintf_unfiltered (gdb_stdlog,
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"infrun: expected thread advanced also "
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"(%s -> %s)\n",
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paddress (target_gdbarch (), tp->prev_pc),
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paddress (target_gdbarch (), stop_pc));
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/* Clear the info of the previous step-over, as it's no
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longer valid (if the thread was trying to step over a
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breakpoint, it has already succeeded). It's what
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keep_going would do too, if we called it. Do this
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before trying to insert the sss breakpoint, otherwise
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if we were previously trying to step over this exact
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address in another thread, the breakpoint is
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skipped. */
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clear_step_over_info ();
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tp->control.trap_expected = 0;
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insert_single_step_breakpoint (get_frame_arch (frame),
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get_frame_address_space (frame),
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stop_pc);
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resume_ptid = user_visible_resume_ptid (tp->control.stepping_command);
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do_target_resume (resume_ptid, 0, GDB_SIGNAL_0);
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prepare_to_wait (ecs);
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return 1;
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}
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else
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{
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if (debug_infrun)
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fprintf_unfiltered (gdb_stdlog,
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"infrun: expected thread still "
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"hasn't advanced\n");
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keep_going_pass_signal (ecs);
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}
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return 1;
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}
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}
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return 0;
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}
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/* Set a previously stepped thread back to stepping. Returns true on
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success, false if the resume is not possible (e.g., the thread
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vanished). */
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static int
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keep_going_stepped_thread (struct thread_info *tp)
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{
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struct frame_info *frame;
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struct gdbarch *gdbarch;
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struct execution_control_state ecss;
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struct execution_control_state *ecs = &ecss;
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/* If the stepping thread exited, then don't try to switch back and
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resume it, which could fail in several different ways depending
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on the target. Instead, just keep going.
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We can find a stepping dead thread in the thread list in two
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cases:
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- The target supports thread exit events, and when the target
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tries to delete the thread from the thread list, inferior_ptid
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pointed at the exiting thread. In such case, calling
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delete_thread does not really remove the thread from the list;
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instead, the thread is left listed, with 'exited' state.
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- The target's debug interface does not support thread exit
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events, and so we have no idea whatsoever if the previously
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stepping thread is still alive. For that reason, we need to
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synchronously query the target now. */
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if (is_exited (tp->ptid)
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|| !target_thread_alive (tp->ptid))
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{
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if (debug_infrun)
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fprintf_unfiltered (gdb_stdlog,
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"infrun: not resuming previously "
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"stepped thread, it has vanished\n");
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delete_thread (tp->ptid);
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return 0;
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}
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if (debug_infrun)
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fprintf_unfiltered (gdb_stdlog,
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"infrun: resuming previously stepped thread\n");
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reset_ecs (ecs, tp);
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switch_to_thread (tp->ptid);
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stop_pc = regcache_read_pc (get_thread_regcache (tp->ptid));
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frame = get_current_frame ();
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gdbarch = get_frame_arch (frame);
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/* If the PC of the thread we were trying to single-step has
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changed, then that thread has trapped or been signaled, but the
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event has not been reported to GDB yet. Re-poll the target
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looking for this particular thread's event (i.e. temporarily
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enable schedlock) by:
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- setting a break at the current PC
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- resuming that particular thread, only (by setting trap
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expected)
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This prevents us continuously moving the single-step breakpoint
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forward, one instruction at a time, overstepping. */
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if (stop_pc != tp->prev_pc)
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{
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ptid_t resume_ptid;
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if (debug_infrun)
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fprintf_unfiltered (gdb_stdlog,
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"infrun: expected thread advanced also (%s -> %s)\n",
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paddress (target_gdbarch (), tp->prev_pc),
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paddress (target_gdbarch (), stop_pc));
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/* Clear the info of the previous step-over, as it's no longer
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valid (if the thread was trying to step over a breakpoint, it
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has already succeeded). It's what keep_going would do too,
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if we called it. Do this before trying to insert the sss
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breakpoint, otherwise if we were previously trying to step
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over this exact address in another thread, the breakpoint is
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skipped. */
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clear_step_over_info ();
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tp->control.trap_expected = 0;
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insert_single_step_breakpoint (get_frame_arch (frame),
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get_frame_address_space (frame),
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stop_pc);
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resume_ptid = user_visible_resume_ptid (tp->control.stepping_command);
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do_target_resume (resume_ptid, 0, GDB_SIGNAL_0);
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}
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else
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{
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if (debug_infrun)
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fprintf_unfiltered (gdb_stdlog,
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"infrun: expected thread still hasn't advanced\n");
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keep_going_pass_signal (ecs);
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}
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return 1;
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}
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/* Is thread TP in the middle of (software or hardware)
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single-stepping? (Note the result of this function must never be
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passed directly as target_resume's STEP parameter.) */
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