[PATCH v3 05/19] btrace: split record_btrace_step_thread

Markus Metzger
2015-09-17T14:10:24Z

The code for BTHR_STEP and BTHR_CONT is fairly similar. Extract the common
parts into a new function record_btrace_single_step_forward. The function
returns TARGET_WAITKIND_SPURIOUS to indicate that the single-step completed
without triggering a trap.

Same for BTHR_RSTEP and BTHR_RCONT.

2015-09-17 Markus Metzger <markus.t.metzger@intel.com>

gdb/
* record-btrace.c (btrace_step_spurious)
(record_btrace_single_step_forward)
(record_btrace_single_step_backward): New.
(record_btrace_step_thread): Call record_btrace_single_step_forward
and record_btrace_single_step_backward.
---
gdb/record-btrace.c | 187 +++++++++++++++++++++++++++++-----------------------
1 file changed, 105 insertions(+), 82 deletions(-)

diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 77494ba..fdf7afb 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -1971,6 +1971,18 @@ btrace_step_stopped_on_request (void)
return status;
}

+/* Return a target_waitstatus indicating a spurious stop. */
+
+static struct target_waitstatus
+btrace_step_spurious (void)
+{
+ struct target_waitstatus status;
+
+ status.kind = TARGET_WAITKIND_SPURIOUS;
+
+ return status;
+}
+
/* Clear the record histories. */

static void
@@ -2011,20 +2023,86 @@ record_btrace_replay_at_breakpoint (struct thread_info *tp)
&btinfo->stop_reason);
}

-/* Step a single thread. */
+/* Step one instruction in forward direction. */

static struct target_waitstatus
-record_btrace_step_thread (struct thread_info *tp)
+record_btrace_single_step_forward (struct thread_info *tp)
{
struct btrace_insn_iterator *replay, end;
struct btrace_thread_info *btinfo;
- enum btrace_thread_flag flags;
- unsigned int steps;

+ btinfo = &tp->btrace;
+ replay = btinfo->replay;
+
+ /* We're done if we're not replaying. */
+ if (replay == NULL)
+ return btrace_step_no_history ();
+
+ /* Skip gaps during replay. */
+ do
+ {
+ unsigned int steps;
+
+ steps = btrace_insn_next (replay, 1);
+ if (steps == 0)
+ {
+ record_btrace_stop_replaying (tp);
+ 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. */
+ if (btrace_insn_cmp (replay, &end) == 0)
+ record_btrace_stop_replaying (tp);
+
+ return btrace_step_spurious ();
+}
+
+/* Step one instruction in backward direction. */
+
+static struct target_waitstatus
+record_btrace_single_step_backward (struct thread_info *tp)
+{
+ struct btrace_insn_iterator *replay;
+ struct btrace_thread_info *btinfo;

btinfo = &tp->btrace;
replay = btinfo->replay;

+ /* Start replaying if we're not already doing so. */
+ if (replay == NULL)
+ replay = record_btrace_start_replaying (tp);
+
+ /* If we can't step any further, we reached the end of the history.
+ Skip gaps during replay. */
+ do
+ {
+ unsigned int steps;
+
+ steps = btrace_insn_prev (replay, 1);
+ if (steps == 0)
+ return btrace_step_no_history ();
+ }
+ while (btrace_insn_get (replay) == NULL);
+
+ return btrace_step_spurious ();
+}
+
+/* Step a single thread. */
+
+static struct target_waitstatus
+record_btrace_step_thread (struct thread_info *tp)
+{
+ struct btrace_thread_info *btinfo;
+ struct target_waitstatus status;
+ enum btrace_thread_flag flags;
+
+ btinfo = &tp->btrace;
+
flags = btinfo->flags & (BTHR_MOVE | BTHR_STOP);
btinfo->flags &= ~(BTHR_MOVE | BTHR_STOP);

@@ -2045,110 +2123,55 @@ record_btrace_step_thread (struct thread_info *tp)
return btrace_step_stopped_on_request ();

case BTHR_STEP:
- /* We're done if we're not replaying. */
- if (replay == NULL)
- return btrace_step_no_history ();
-
- /* Skip gaps during replay. */
- do
- {
- steps = btrace_insn_next (replay, 1);
- if (steps == 0)
- {
- record_btrace_stop_replaying (tp);
- 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. */
- if (btrace_insn_cmp (replay, &end) == 0)
- record_btrace_stop_replaying (tp);
+ status = record_btrace_single_step_forward (tp);
+ if (status.kind != TARGET_WAITKIND_SPURIOUS)
+ return status;

return btrace_step_stopped ();

case BTHR_RSTEP:
- /* Start replaying if we're not already doing so. */
- if (replay == NULL)
- replay = record_btrace_start_replaying (tp);
-
- /* If we can't step any further, we reached the end of the history.
- Skip gaps during replay. */
- do
- {
- steps = btrace_insn_prev (replay, 1);
- if (steps == 0)
- return btrace_step_no_history ();
-
- }
- while (btrace_insn_get (replay) == NULL);
+ status = record_btrace_single_step_backward (tp);
+ if (status.kind != TARGET_WAITKIND_SPURIOUS)
+ return status;

return btrace_step_stopped ();

case BTHR_CONT:
- /* We're done if we're not replaying. */
- if (replay == NULL)
- return btrace_step_no_history ();
-
- /* Determine the end of the instruction trace. */
- btrace_insn_end (&end, btinfo);
-
for (;;)
{
- const struct btrace_insn *insn;
+ status = record_btrace_single_step_forward (tp);
+ if (status.kind != TARGET_WAITKIND_SPURIOUS)
+ return status;

- /* Skip gaps during replay. */
- do
+ if (btinfo->replay != NULL)
{
- steps = btrace_insn_next (replay, 1);
- if (steps == 0)
- {
- record_btrace_stop_replaying (tp);
- return btrace_step_no_history ();
- }
+ const struct btrace_insn *insn;

- insn = btrace_insn_get (replay);
- }
- while (insn == NULL);
+ insn = btrace_insn_get (btinfo->replay);
+ gdb_assert (insn != NULL);

- /* We stop replaying if we reached the end of the trace. */
- if (btrace_insn_cmp (replay, &end) == 0)
- {
- record_btrace_stop_replaying (tp);
- return btrace_step_no_history ();
+ DEBUG ("stepping %d (%s) ... %s", tp->num,
+ target_pid_to_str (tp->ptid),
+ core_addr_to_string_nz (insn->pc));
}

- DEBUG ("stepping %d (%s) ... %s", tp->num,
- target_pid_to_str (tp->ptid),
- core_addr_to_string_nz (insn->pc));
-
if (record_btrace_replay_at_breakpoint (tp))
return btrace_step_stopped ();
}

case BTHR_RCONT:
- /* Start replaying if we're not already doing so. */
- if (replay == NULL)
- replay = record_btrace_start_replaying (tp);
-
for (;;)
{
const struct btrace_insn *insn;

- /* If we can't step any further, we reached the end of the history.
- Skip gaps during replay. */
- do
- {
- steps = btrace_insn_prev (replay, 1);
- if (steps == 0)
- return btrace_step_no_history ();
+ status = record_btrace_single_step_backward (tp);
+ if (status.kind != TARGET_WAITKIND_SPURIOUS)
+ return status;

- insn = btrace_insn_get (replay);
- }
- while (insn == NULL);
+ gdb_assert (btinfo->replay != NULL);
+
+ insn = btrace_insn_get (btinfo->replay);
+ gdb_assert (insn != NULL);

DEBUG ("reverse-stepping %d (%s) ... %s", tp->num,
target_pid_to_str (tp->ptid),
--
1.8.3.1