[RFA] Clarify infrun variable naming.

Vladimir Prus
2007-11-23T13:23:24Z

The infrun.c file has a variable named trap_expected, which
is a bit misleading -- after all, most times when we resume
inferior, we get SIGTRAP. As it turns out, that variable
is set when we're stepping over breakpoints, so a better
name would be stepping_over_breakpoint. Likewise,
ecs->another_trap also indicates that keep_going should
be stepping over breakpoint. The attached patch clarifies
the naming and adds comments, and has no behaviour changes.
(The patch is on top of my previous breakpoints_inserted
removing patch).
OK?

- Volodya

* infrun.c (trap_expected): Rename
to stepping_over_breakpoint. Document.
(struct execution_control_state): Rename
the another_trap field to stepping_over_breakpoint.
(struct inferior_status): Rename the trap_expected
field to stepping_over_breakpoint.
(clear_proceed_status, proceed)
(init_execution_control_state, context_switch)
(handle_inferior_event, currently_stepping)
(keep_going, save_inferior_status)
(restore_inferior_status): Adjust.
* gdbthread.h (struct thread_info): Rename the
trap_expected field to stepping_over_breakpoint.
* thread.c (load_infrun_state, save_infrun_state):
Adjust.
---
gdb/gdbthread.h | 2 +-
gdb/infrun.c | 91 ++++++++++++++++++++++++++++++++++--------------------
gdb/thread.c | 8 ++--
3 files changed, 62 insertions(+), 39 deletions(-)

diff --git a/gdb/gdbthread.h b/gdb/gdbthread.h
index aeb4a40..12e0bcc 100644
--- a/gdb/gdbthread.h
+++ b/gdb/gdbthread.h
@@ -49,7 +49,7 @@ struct thread_info
struct symtab *current_symtab;
int trap_expected;
int handling_longjmp;
- int another_trap;
+ int stepping_over_breakpoint;

/* This is set TRUE when a catchpoint of a shared library event
triggers. Since we don't wish to leave the inferior in the
diff --git a/gdb/infrun.c b/gdb/infrun.c
index 08b0cf3..05b2743 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -218,9 +218,30 @@ static struct cmd_list_element *stop_command;

static struct symbol *step_start_function;

-/* Nonzero if we are expecting a trace trap and should proceed from it. */
+/* Nonzero if we are presenting stepping over breakpoint.

-static int trap_expected;
+ If we hit a breakpoint or watchpoint, and then continue,
+ we need to single step the current thread with breakpoints
+ disabled, so that to avoid hitting the same breakpoint or
+ watchpoint again. And we should step just a single
+ thread and keep other threads stopped, so that
+ other threads don't miss breakpoints while they are removed.
+
+ So, this variable simultaneously means that we need to single
+ step current thread, keep other threads stopped, and that
+ breakpoints should be removed while we step.
+
+ This variable is set either:
+ - in proceed, when we resume inferior on explicit user's request
+ - in keep_going, if handle_inferior_event decides we need to
+ step over breakpoint.
+
+ The variable is cleared in clear_proceed_status, called every
+ time before we call proceed. The proceed calls wait_for_inferior,
+ which calls handle_inferior_event in a loop, and until
+ wait_for_inferior exits, this variable is changed only by keep_going. */
+
+static int stepping_over_breakpoint;

/* Nonzero if we want to give control to the user when we're notified
of shared library events by the dynamic linker. */
@@ -646,7 +667,7 @@ a command like `return' or `jump' to continue execution."));
void
clear_proceed_status (void)
{
- trap_expected = 0;
+ stepping_over_breakpoint = 0;
step_range_start = 0;
step_range_end = 0;
step_frame_id = null_frame_id;
@@ -777,7 +798,7 @@ proceed (CORE_ADDR addr, enum target_signal siggnal, int step)
if (oneproc)
/* We will get a trace trap after one instruction.
Continue it automatically and insert breakpoints then. */
- trap_expected = 1;
+ stepping_over_breakpoint = 1;
else
insert_breakpoints ();

@@ -841,7 +862,7 @@ start_remote (int from_tty)
init_thread_list ();
init_wait_for_inferior ();
stop_soon = STOP_QUIETLY_REMOTE;
- trap_expected = 0;
+ stepping_over_breakpoint = 0;

/* Always go on waiting for the target, regardless of the mode. */
/* FIXME: cagney/1999-09-23: At present it isn't possible to
@@ -923,7 +944,9 @@ struct execution_control_state
{
struct target_waitstatus ws;
struct target_waitstatus *wp;
- int another_trap;
+ /* Should we step over breakpoint next time keep_going
+ is called? */
+ int stepping_over_breakpoint;
int random_signal;
CORE_ADDR stop_func_start;
CORE_ADDR stop_func_end;
@@ -1084,7 +1107,7 @@ fetch_inferior_event (void *client_data)
void
init_execution_control_state (struct execution_control_state *ecs)
{
- ecs->another_trap = 0;
+ ecs->stepping_over_breakpoint = 0;
ecs->random_signal = 0;
ecs->step_after_step_resume_breakpoint = 0;
ecs->handling_longjmp = 0; /* FIXME */
@@ -1139,20 +1162,20 @@ context_switch (struct execution_control_state *ecs)
{ /* Perform infrun state context switch: */
/* Save infrun state for the old thread. */
save_infrun_state (inferior_ptid, prev_pc,
- trap_expected, step_resume_breakpoint,
+ stepping_over_breakpoint, step_resume_breakpoint,
step_range_start,
step_range_end, &step_frame_id,
- ecs->handling_longjmp, ecs->another_trap,
+ ecs->handling_longjmp, ecs->stepping_over_breakpoint,
ecs->stepping_through_solib_after_catch,
ecs->stepping_through_solib_catchpoints,
ecs->current_line, ecs->current_symtab);

/* Load infrun state for the new thread. */
load_infrun_state (ecs->ptid, &prev_pc,
- &trap_expected, &step_resume_breakpoint,
+ &stepping_over_breakpoint, &step_resume_breakpoint,
&step_range_start,
&step_range_end, &step_frame_id,
- &ecs->handling_longjmp, &ecs->another_trap,
+ &ecs->handling_longjmp, &ecs->stepping_over_breakpoint,
&ecs->stepping_through_solib_after_catch,
&ecs->stepping_through_solib_catchpoints,
&ecs->current_line, &ecs->current_symtab);
@@ -1770,7 +1793,7 @@ handle_inferior_event (struct execution_control_state *ecs)
context_switch (ecs);
ecs->waiton_ptid = ecs->ptid;
ecs->wp = &(ecs->ws);
- ecs->another_trap = 1;
+ ecs->stepping_over_breakpoint = 1;

ecs->infwait_state = infwait_thread_hop_state;
keep_going (ecs);
@@ -1864,7 +1887,7 @@ handle_inferior_event (struct execution_control_state *ecs)
&ecs->stop_func_start, &ecs->stop_func_end);
ecs->stop_func_start
+= gdbarch_deprecated_function_start_offset (current_gdbarch);
- ecs->another_trap = 0;
+ ecs->stepping_over_breakpoint = 0;
bpstat_clear (&stop_bpstat);
stop_step = 0;
stop_stack_dummy = 0;
@@ -1873,7 +1896,7 @@ handle_inferior_event (struct execution_control_state *ecs)
stopped_by_random_signal = 0;

if (stop_signal == TARGET_SIGNAL_TRAP
- && trap_expected
+ && stepping_over_breakpoint
&& gdbarch_single_step_through_delay_p (current_gdbarch)
&& currently_stepping (ecs))
{
@@ -1891,7 +1914,7 @@ handle_inferior_event (struct execution_control_state *ecs)
{
/* The user issued a continue when stopped at a breakpoint.
Set up for another trap and get out of here. */
- ecs->another_trap = 1;
+ ecs->stepping_over_breakpoint = 1;
keep_going (ecs);
return;
}
@@ -1900,10 +1923,10 @@ handle_inferior_event (struct execution_control_state *ecs)
/* The user issued a step when stopped at a breakpoint.
Maybe we should stop, maybe we should not - the delay
slot *might* correspond to a line of source. In any
- case, don't decide that here, just set ecs->another_trap,
- making sure we single-step again before breakpoints are
- re-inserted. */
- ecs->another_trap = 1;
+ case, don't decide that here, just set
+ ecs->stepping_over_breakpoint, making sure we
+ single-step again before breakpoints are re-inserted. */
+ ecs->stepping_over_breakpoint = 1;
}
}

@@ -1911,7 +1934,7 @@ handle_inferior_event (struct execution_control_state *ecs)
The alternatives are:
1) break; to really stop and return to the debugger,
2) drop through to start up again
- (set ecs->another_trap to 1 to single step once)
+ (set ecs->stepping_over_breakpoint to 1 to single step once)
3) set ecs->random_signal to 1, and the decision between 1 and 2
will be made according to the signal handling tables. */

@@ -1967,7 +1990,7 @@ handle_inferior_event (struct execution_control_state *ecs)

/* Don't even think about breakpoints if just proceeded over a
breakpoint. */
- if (stop_signal == TARGET_SIGNAL_TRAP && trap_expected)
+ if (stop_signal == TARGET_SIGNAL_TRAP && stepping_over_breakpoint)
{
if (debug_infrun)
fprintf_unfiltered (gdb_stdlog, "infrun: trap expected\n");
@@ -2006,7 +2029,7 @@ handle_inferior_event (struct execution_control_state *ecs)
if (stop_signal == TARGET_SIGNAL_TRAP)
ecs->random_signal
= !(bpstat_explains_signal (stop_bpstat)
- || trap_expected
+ || stepping_over_breakpoint
|| (step_range_end && step_resume_breakpoint == NULL));
else
{
@@ -2167,7 +2190,7 @@ process_event_stop_test:
if (debug_infrun)
fprintf_unfiltered (gdb_stdlog, "infrun: BPSTAT_WHAT_SINGLE\n");
remove_breakpoints ();
- ecs->another_trap = 1;
+ ecs->stepping_over_breakpoint = 1;
/* Still need to check other stuff, at least the case
where we are stepping and step out of the right range. */
break;
@@ -2228,7 +2251,7 @@ process_event_stop_test:
to doing that. */
ecs->step_after_step_resume_breakpoint = 0;
remove_breakpoints ();
- ecs->another_trap = 1;
+ ecs->stepping_over_breakpoint = 1;
keep_going (ecs);
return;
}
@@ -2313,13 +2336,13 @@ process_event_stop_test:

/* Be sure to lift all breakpoints, so the inferior does
actually step past this point... */
- ecs->another_trap = 1;
+ ecs->stepping_over_breakpoint = 1;
break;
}
else
{
/* We want to step over this breakpoint, then keep going. */
- ecs->another_trap = 1;
+ ecs->stepping_over_breakpoint = 1;
break;
}
}
@@ -2350,7 +2373,7 @@ process_event_stop_test:
{
if (debug_infrun)
fprintf_unfiltered (gdb_stdlog, "infrun: stepping in dynamic linker\n");
- ecs->another_trap = 1;
+ ecs->stepping_over_breakpoint = 1;
keep_going (ecs);
return;
}
@@ -2746,7 +2769,7 @@ currently_stepping (struct execution_control_state *ecs)
{
return ((!ecs->handling_longjmp
&& ((step_range_end && step_resume_breakpoint == NULL)
- || trap_expected))
+ || stepping_over_breakpoint))
|| ecs->stepping_through_solib_after_catch
|| bpstat_should_step ());
}
@@ -2925,7 +2948,7 @@ keep_going (struct execution_control_state *ecs)
/* If we did not do break;, it means we should keep running the
inferior and not return to debugger. */

- if (trap_expected && stop_signal != TARGET_SIGNAL_TRAP)
+ if (stepping_over_breakpoint && stop_signal != TARGET_SIGNAL_TRAP)
{
/* We took a signal (which we are supposed to pass through to
the inferior, else we'd have done a break above) and we
@@ -2947,7 +2970,7 @@ keep_going (struct execution_control_state *ecs)
already inserted breakpoints. Therefore, we don't
care if breakpoints were already inserted, or not. */

- if (!ecs->another_trap)
+ if (!ecs->stepping_over_breakpoint)
{
/* Stop stepping when inserting breakpoints
has failed. */
@@ -2958,7 +2981,7 @@ keep_going (struct execution_control_state *ecs)
}
}

- trap_expected = ecs->another_trap;
+ stepping_over_breakpoint = ecs->stepping_over_breakpoint;

/* Do not deliver SIGNAL_TRAP (except when the user explicitly
specifies that such a signal should be delivered to the
@@ -3676,7 +3699,7 @@ struct inferior_status
int stop_step;
int stop_stack_dummy;
int stopped_by_random_signal;
- int trap_expected;
+ int stepping_over_breakpoint;
CORE_ADDR step_range_start;
CORE_ADDR step_range_end;
struct frame_id step_frame_id;
@@ -3722,7 +3745,7 @@ save_inferior_status (int restore_stack_info)
inf_status->stop_step = stop_step;
inf_status->stop_stack_dummy = stop_stack_dummy;
inf_status->stopped_by_random_signal = stopped_by_random_signal;
- inf_status->trap_expected = trap_expected;
+ inf_status->stepping_over_breakpoint = stepping_over_breakpoint;
inf_status->step_range_start = step_range_start;
inf_status->step_range_end = step_range_end;
inf_status->step_frame_id = step_frame_id;
@@ -3774,7 +3797,7 @@ restore_inferior_status (struct inferior_status *inf_status)
stop_step = inf_status->stop_step;
stop_stack_dummy = inf_status->stop_stack_dummy;
stopped_by_random_signal = inf_status->stopped_by_random_signal;
- trap_expected = inf_status->trap_expected;
+ stepping_over_breakpoint = inf_status->stepping_over_breakpoint;
step_range_start = inf_status->step_range_start;
step_range_end = inf_status->step_range_end;
step_frame_id = inf_status->step_frame_id;
diff --git a/gdb/thread.c b/gdb/thread.c
index b6762e1..3c8644b 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -300,7 +300,7 @@ load_infrun_state (ptid_t ptid,
CORE_ADDR *step_range_end,
struct frame_id *step_frame_id,
int *handling_longjmp,
- int *another_trap,
+ int *stepping_over_breakpoint,
int *stepping_through_solib_after_catch,
bpstat *stepping_through_solib_catchpoints,
int *current_line,
@@ -321,7 +321,7 @@ load_infrun_state (ptid_t ptid,
*step_range_end = tp->step_range_end;
*step_frame_id = tp->step_frame_id;
*handling_longjmp = tp->handling_longjmp;
- *another_trap = tp->another_trap;
+ *stepping_over_breakpoint = tp->stepping_over_breakpoint;
*stepping_through_solib_after_catch =
tp->stepping_through_solib_after_catch;
*stepping_through_solib_catchpoints =
@@ -341,7 +341,7 @@ save_infrun_state (ptid_t ptid,
CORE_ADDR step_range_end,
const struct frame_id *step_frame_id,
int handling_longjmp,
- int another_trap,
+ int stepping_over_breakpoint,
int stepping_through_solib_after_catch,
bpstat stepping_through_solib_catchpoints,
int current_line,
@@ -362,7 +362,7 @@ save_infrun_state (ptid_t ptid,
tp->step_range_end = step_range_end;
tp->step_frame_id = (*step_frame_id);
tp->handling_longjmp = handling_longjmp;
- tp->another_trap = another_trap;
+ tp->stepping_over_breakpoint = stepping_over_breakpoint;
tp->stepping_through_solib_after_catch = stepping_through_solib_after_catch;
tp->stepping_through_solib_catchpoints = stepping_through_solib_catchpoints;
tp->current_line = current_line;
--
1.5.3.5