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Misc switch_back_to_stepped_thread cleanups

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Several misc cleanups that prepare the tail end of this function, the
part that actually re-resumes the stepped thread.

The most non-obvious would be the currently_stepping change, I guess.
That's because it isn't ever correct to pass step=1 to target_resume
on software single-step targets, and currently_stepping works at a
conceptual higher level, it returns step=true even on software step
targets.  It doesn't really matter on hardware step targets, as the
breakpoint will be hit immediately, but it's just wrong on software
step targets.  I tested it against my x86 software single-step branch,
and it indeed fixes failed assertions (that catch spurious
PTRACE_SINGLESTEP requests) there.

gdb/ChangeLog:
2015-08-07  Pedro Alves  <palves@redhat.com>

	* infrun.c (switch_back_to_stepped_thread): Use ecs->ptid instead
	of inferior_ptid.  If the stepped thread vanished, return 0
	instead of resuming here.  Use reset_ecs.  Print the prev_pc and
	the current stop_pc in log message.  Clear trap_expected if the
	thread advanced.  Don't pass currently_stepping to
	do_target_resume.
This commit is contained in:
Pedro Alves 2015-08-07 17:23:58 +01:00
parent 4d9d9d0423
commit 1afd5965ed
2 changed files with 27 additions and 15 deletions
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9
gdb/ChangeLog
View file

@ -1,3 +1,12 @@
2015-08-07 Pedro Alves <palves@redhat.com>
* infrun.c (switch_back_to_stepped_thread): Use ecs->ptid instead
of inferior_ptid. If the stepped thread vanished, return 0
instead of resuming here. Use reset_ecs. Print the prev_pc and
the current stop_pc in log message. Clear trap_expected if the
thread advanced. Don't pass currently_stepping to
do_target_resume.
2015-08-07 Pedro Alves <palves@redhat.com>
* gdbthread.h (struct thread_info) <prev_pc>: Extend comment.

33
gdb/infrun.c
View file

@ -5717,7 +5717,7 @@ switch_back_to_stepped_thread (struct execution_control_state *ecs)
{
/* Ignore threads of processes we're not resuming. */
if (!sched_multi
&& ptid_get_pid (tp->ptid) != ptid_get_pid (inferior_ptid))
&& ptid_get_pid (tp->ptid) != ptid_get_pid (ecs->ptid))
continue;
/* When stepping over a breakpoint, we lock all threads
@ -5781,19 +5781,17 @@ switch_back_to_stepped_thread (struct execution_control_state *ecs)
"stepped thread, it has vanished\n");
delete_thread (tp->ptid);
keep_going (ecs);
return 1;
return 0;
}
if (debug_infrun)
fprintf_unfiltered (gdb_stdlog,
"infrun: switching back to stepped thread\n");
ecs->event_thread = tp;
ecs->ptid = tp->ptid;
context_switch (ecs->ptid);
reset_ecs (ecs, tp);
switch_to_thread (tp->ptid);
stop_pc = regcache_read_pc (get_thread_regcache (ecs->ptid));
stop_pc = regcache_read_pc (get_thread_regcache (tp->ptid));
frame = get_current_frame ();
gdbarch = get_frame_arch (frame);
@ -5817,23 +5815,28 @@ switch_back_to_stepped_thread (struct execution_control_state *ecs)
if (debug_infrun)
fprintf_unfiltered (gdb_stdlog,
"infrun: expected thread advanced also\n");
"infrun: expected thread advanced also "
"(%s -> %s)\n",
paddress (target_gdbarch (), tp->prev_pc),
paddress (target_gdbarch (), stop_pc));
/* Clear the info of the previous step-over, as it's no
longer valid. It's what keep_going would do too, if
we called it. Must do this before trying to insert
the sss breakpoint, otherwise if we were previously
trying to step over this exact address in another
thread, the breakpoint ends up not installed. */
longer valid (if the thread was trying to step over a
breakpoint, it has already succeeded). It's what
keep_going would do too, if we called it. Do this
before trying to insert the sss breakpoint, otherwise
if we were previously trying to step over this exact
address in another thread, the breakpoint is
skipped. */
clear_step_over_info ();
tp->control.trap_expected = 0;
insert_single_step_breakpoint (get_frame_arch (frame),
get_frame_address_space (frame),
stop_pc);
resume_ptid = user_visible_resume_ptid (tp->control.stepping_command);
do_target_resume (resume_ptid,
currently_stepping (tp), GDB_SIGNAL_0);
do_target_resume (resume_ptid, 0, GDB_SIGNAL_0);
prepare_to_wait (ecs);
}
else