#include "infrun.h"
#include "event-loop.h"
#include "inf-loop.h"
+#include "vec.h"
/* The target_ops of record-btrace. */
static struct target_ops record_btrace_ops;
registers_changed_ptid (tp->ptid);
}
+/* Stop replaying TP if it is at the end of its execution history. */
+
+static void
+record_btrace_stop_replaying_at_end (struct thread_info *tp)
+{
+ struct btrace_insn_iterator *replay, end;
+ struct btrace_thread_info *btinfo;
+
+ btinfo = &tp->btrace;
+ replay = btinfo->replay;
+
+ if (replay == NULL)
+ return;
+
+ btrace_insn_end (&end, btinfo);
+
+ if (btrace_insn_cmp (replay, &end) == 0)
+ record_btrace_stop_replaying (tp);
+}
+
/* The to_resume method of target record-btrace. */
static void
btrace_thread_flag_to_str (flags));
tp->btrace.flags &= ~(BTHR_MOVE | BTHR_STOP);
-}
-
-/* Find a thread to move. */
-
-static struct thread_info *
-record_btrace_find_thread_to_move (ptid_t ptid)
-{
- struct thread_info *tp;
-
- /* First check the parameter thread. */
- tp = find_thread_ptid (ptid);
- if (tp != NULL && (tp->btrace.flags & (BTHR_MOVE | BTHR_STOP)) != 0)
- return tp;
-
- /* Otherwise, find one other thread that has been resumed. */
- ALL_NON_EXITED_THREADS (tp)
- if ((tp->btrace.flags & (BTHR_MOVE | BTHR_STOP)) != 0)
- return tp;
-
- return NULL;
+ record_btrace_stop_replaying_at_end (tp);
}
/* Return a target_waitstatus indicating that we ran out of history. */
return status;
}
+/* Return a target_waitstatus indicating that the thread was not resumed. */
+
+static struct target_waitstatus
+btrace_step_no_resumed (void)
+{
+ struct target_waitstatus status;
+
+ status.kind = TARGET_WAITKIND_NO_RESUMED;
+
+ return status;
+}
+
+/* Return a target_waitstatus indicating that we should wait again. */
+
+static struct target_waitstatus
+btrace_step_again (void)
+{
+ struct target_waitstatus status;
+
+ status.kind = TARGET_WAITKIND_IGNORE;
+
+ return status;
+}
+
/* Clear the record histories. */
static void
{
unsigned int steps;
+ /* We will bail out here if we continue stepping after reaching the end
+ of the execution history. */
steps = btrace_insn_next (replay, 1);
if (steps == 0)
- {
- record_btrace_stop_replaying (tp);
- return btrace_step_no_history ();
- }
+ return btrace_step_no_history ();
}
while (btrace_insn_get (replay) == NULL);
/* Determine the end of the instruction trace. */
btrace_insn_end (&end, btinfo);
- /* We stop replaying if we reached the end of the trace. */
+ /* The execution trace contains (and ends with) the current instruction.
+ This instruction has not been executed, yet, so the trace really ends
+ one instruction earlier. */
if (btrace_insn_cmp (replay, &end) == 0)
- {
- record_btrace_stop_replaying (tp);
- return btrace_step_no_history ();
- }
+ return btrace_step_no_history ();
return btrace_step_spurious ();
}
case BTHR_STEP:
status = record_btrace_single_step_forward (tp);
if (status.kind != TARGET_WAITKIND_SPURIOUS)
- return status;
+ break;
return btrace_step_stopped ();
case BTHR_RSTEP:
status = record_btrace_single_step_backward (tp);
if (status.kind != TARGET_WAITKIND_SPURIOUS)
- return status;
+ break;
return btrace_step_stopped ();
case BTHR_CONT:
- for (;;)
- {
- status = record_btrace_single_step_forward (tp);
- if (status.kind != TARGET_WAITKIND_SPURIOUS)
- return status;
-
- if (btinfo->replay != NULL)
- {
- const struct btrace_insn *insn;
-
- insn = btrace_insn_get (btinfo->replay);
- gdb_assert (insn != NULL);
+ status = record_btrace_single_step_forward (tp);
+ if (status.kind != TARGET_WAITKIND_SPURIOUS)
+ break;
- DEBUG ("stepping %d (%s) ... %s", tp->num,
- target_pid_to_str (tp->ptid),
- core_addr_to_string_nz (insn->pc));
- }
- }
+ btinfo->flags |= flags;
+ return btrace_step_again ();
case BTHR_RCONT:
- for (;;)
- {
- const struct btrace_insn *insn;
-
- status = record_btrace_single_step_backward (tp);
- if (status.kind != TARGET_WAITKIND_SPURIOUS)
- return status;
+ status = record_btrace_single_step_backward (tp);
+ if (status.kind != TARGET_WAITKIND_SPURIOUS)
+ break;
- gdb_assert (btinfo->replay != NULL);
+ btinfo->flags |= flags;
+ return btrace_step_again ();
+ }
- insn = btrace_insn_get (btinfo->replay);
- gdb_assert (insn != NULL);
+ /* We keep threads moving at the end of their execution history. The to_wait
+ method will stop the thread for whom the event is reported. */
+ if (status.kind == TARGET_WAITKIND_NO_HISTORY)
+ btinfo->flags |= flags;
- DEBUG ("reverse-stepping %d (%s) ... %s", tp->num,
- target_pid_to_str (tp->ptid),
- core_addr_to_string_nz (insn->pc));
- }
- }
+ return status;
}
+/* A vector of threads. */
+
+typedef struct thread_info * tp_t;
+DEF_VEC_P (tp_t);
+
/* The to_wait method of target record-btrace. */
static ptid_t
record_btrace_wait (struct target_ops *ops, ptid_t ptid,
struct target_waitstatus *status, int options)
{
- struct thread_info *tp, *other;
+ VEC (tp_t) *moving, *no_history;
+ struct thread_info *tp, *eventing;
+ struct cleanup *cleanups = make_cleanup (null_cleanup, NULL);
DEBUG ("wait %s (0x%x)", target_pid_to_str (ptid), options);
return ops->to_wait (ops, ptid, status, options);
}
- /* Let's find a thread to move. */
- tp = record_btrace_find_thread_to_move (ptid);
- if (tp == NULL)
+ moving = NULL;
+ no_history = NULL;
+
+ make_cleanup (VEC_cleanup (tp_t), &moving);
+ make_cleanup (VEC_cleanup (tp_t), &no_history);
+
+ /* Keep a work list of moving threads. */
+ ALL_NON_EXITED_THREADS (tp)
+ if (ptid_match (tp->ptid, ptid)
+ && ((tp->btrace.flags & (BTHR_MOVE | BTHR_STOP)) != 0))
+ VEC_safe_push (tp_t, moving, tp);
+
+ if (VEC_empty (tp_t, moving))
+ {
+ *status = btrace_step_no_resumed ();
+
+ DEBUG ("wait ended by %s: %s", target_pid_to_str (null_ptid),
+ target_waitstatus_to_string (status));
+
+ do_cleanups (cleanups);
+ return null_ptid;
+ }
+
+ /* Step moving threads one by one, one step each, until either one thread
+ reports an event or we run out of threads to step.
+
+ When stepping more than one thread, chances are that some threads reach
+ the end of their execution history earlier than others. If we reported
+ this immediately, all-stop on top of non-stop would stop all threads and
+ resume the same threads next time. And we would report the same thread
+ having reached the end of its execution history again.
+
+ In the worst case, this would starve the other threads. But even if other
+ threads would be allowed to make progress, this would result in far too
+ many intermediate stops.
+
+ We therefore delay the reporting of "no execution history" until we have
+ nothing else to report. By this time, all threads should have moved to
+ either the beginning or the end of their execution history. There will
+ be a single user-visible stop. */
+ eventing = NULL;
+ while ((eventing == NULL) && !VEC_empty (tp_t, moving))
+ {
+ unsigned int ix;
+
+ ix = 0;
+ while ((eventing == NULL) && VEC_iterate (tp_t, moving, ix, tp))
+ {
+ *status = record_btrace_step_thread (tp);
+
+ switch (status->kind)
+ {
+ case TARGET_WAITKIND_IGNORE:
+ ix++;
+ break;
+
+ case TARGET_WAITKIND_NO_HISTORY:
+ VEC_safe_push (tp_t, no_history,
+ VEC_ordered_remove (tp_t, moving, ix));
+ break;
+
+ default:
+ eventing = VEC_unordered_remove (tp_t, moving, ix);
+ break;
+ }
+ }
+ }
+
+ if (eventing == NULL)
{
- DEBUG ("wait %s: no thread", target_pid_to_str (ptid));
+ /* We started with at least one moving thread. This thread must have
+ either stopped or reached the end of its execution history.
- status->kind = TARGET_WAITKIND_IGNORE;
- return minus_one_ptid;
+ In the former case, EVENTING must not be NULL.
+ In the latter case, NO_HISTORY must not be empty. */
+ gdb_assert (!VEC_empty (tp_t, no_history));
+
+ /* We kept threads moving at the end of their execution history. Stop
+ EVENTING now that we are going to report its stop. */
+ eventing = VEC_unordered_remove (tp_t, no_history, 0);
+ eventing->btrace.flags &= ~BTHR_MOVE;
+
+ *status = btrace_step_no_history ();
}
- /* We only move a single thread. We're not able to correlate threads. */
- *status = record_btrace_step_thread (tp);
+ gdb_assert (eventing != NULL);
+
+ /* We kept threads replaying at the end of their execution history. Stop
+ replaying EVENTING now that we are going to report its stop. */
+ record_btrace_stop_replaying_at_end (eventing);
/* Stop all other threads. */
if (!target_is_non_stop_p ())
- ALL_NON_EXITED_THREADS (other)
- record_btrace_cancel_resume (other);
+ ALL_NON_EXITED_THREADS (tp)
+ record_btrace_cancel_resume (tp);
/* Start record histories anew from the current position. */
- record_btrace_clear_histories (&tp->btrace);
+ record_btrace_clear_histories (&eventing->btrace);
/* We moved the replay position but did not update registers. */
- registers_changed_ptid (tp->ptid);
+ registers_changed_ptid (eventing->ptid);
+
+ DEBUG ("wait ended by thread %d (%s): %s", eventing->num,
+ target_pid_to_str (eventing->ptid),
+ target_waitstatus_to_string (status));
- return tp->ptid;
+ do_cleanups (cleanups);
+ return eventing->ptid;
}
/* The to_stop method of target record-btrace. */
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