[PATCH v8 04/10] btrace: Handle stepping and goto for auxiliary instructions.

[Felix Willgerodt]

Print the auxiliary data when stepping. Don't allow to goto an auxiliary
instruction.

This patch is in preparation for the new ptwrite feature, which is based on
auxiliary instructions.
---
 gdb/record-btrace.c | 67 ++++++++++++++++++++++++++++++++++++---------
 1 file changed, 54 insertions(+), 13 deletions(-)

diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 9ec7eb1b415..22687e889ec 100644
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -2378,9 +2378,13 @@ record_btrace_single_step_forward (struct thread_info *tp)
     return btrace_step_stopped ();
 
   /* Skip gaps during replay.  If we end up at a gap (at the end of the trace),
-     jump back to the instruction at which we started.  */
+     jump back to the instruction at which we started.  If we're stepping a
+     BTRACE_INSN_AUX instruction, print the auxiliary data and skip the
+     instruction.  */
+
   start = *replay;
-  do
+
+  for (;;)
     {
       unsigned int steps;
 
@@ -2388,12 +2392,27 @@ record_btrace_single_step_forward (struct thread_info *tp)
 	 of the execution history.  */
       steps = btrace_insn_next (replay, 1);
       if (steps == 0)
+        {
+          *replay = start;
+          return btrace_step_no_history ();
+        }
+
+      const struct btrace_insn *insn = btrace_insn_get (replay);
+      if (insn == nullptr)
+	continue;
+
+      /* If we're stepping a BTRACE_INSN_AUX instruction, print the auxiliary
+	 data and skip the instruction.  */
+      if (insn->iclass == BTRACE_INSN_AUX)
 	{
-	  *replay = start;
-	  return btrace_step_no_history ();
+	  gdb_printf ("[%s]\n",
+		      btinfo->aux_data.at (insn->aux_data_index).c_str ());
+	  continue;
 	}
+
+      /* We have an instruction, we are done.  */
+      break;
     }
-  while (btrace_insn_get (replay) == NULL);
 
   /* Determine the end of the instruction trace.  */
   btrace_insn_end (&end, btinfo);
@@ -2424,9 +2443,12 @@ record_btrace_single_step_backward (struct thread_info *tp)
 
   /* If we can't step any further, we reached the end of the history.
      Skip gaps during replay.  If we end up at a gap (at the beginning of
-     the trace), jump back to the instruction at which we started.  */
+     the trace), jump back to the instruction at which we started.
+     If we're stepping a BTRACE_INSN_AUX instruction, print the auxiliary
+     data and skip the instruction.  */
   start = *replay;
-  do
+
+  for (;;)
     {
       unsigned int steps;
 
@@ -2436,8 +2458,22 @@ record_btrace_single_step_backward (struct thread_info *tp)
 	  *replay = start;
 	  return btrace_step_no_history ();
 	}
+
+      const struct btrace_insn *insn = btrace_insn_get (replay);
+      if (insn == nullptr)
+	continue;
+
+      /* Check if we're stepping a BTRACE_INSN_AUX instruction and skip it.  */
+      if (insn->iclass == BTRACE_INSN_AUX)
+	{
+	  gdb_printf ("[%s]\n",
+		      btinfo->aux_data.at (insn->aux_data_index).c_str ());
+	  continue;
+	}
+
+      /* We have an instruction, we are done.  */
+      break;
     }
-  while (btrace_insn_get (replay) == NULL);
 
   /* Check if we're stepping a breakpoint.
 
@@ -2859,25 +2895,30 @@ record_btrace_target::goto_record_end ()
 /* The goto_record method of target record-btrace.  */
 
 void
-record_btrace_target::goto_record (ULONGEST insn)
+record_btrace_target::goto_record (ULONGEST insn_number)
 {
   struct thread_info *tp;
   struct btrace_insn_iterator it;
   unsigned int number;
   int found;
 
-  number = insn;
+  number = insn_number;
 
   /* Check for wrap-arounds.  */
-  if (number != insn)
+  if (number != insn_number)
     error (_("Instruction number out of range."));
 
   tp = require_btrace_thread ();
 
   found = btrace_find_insn_by_number (&it, &tp->btrace, number);
 
-  /* Check if the instruction could not be found or is a gap.  */
-  if (found == 0 || btrace_insn_get (&it) == NULL)
+  /* Check if the instruction could not be found or is a gap or an
+     auxilliary instruction.  */
+  if (found == 0)
+    error (_("No such instruction."));
+
+  const struct btrace_insn *insn = btrace_insn_get (&it);
+  if ((insn == NULL) || (insn->iclass == BTRACE_INSN_AUX))
     error (_("No such instruction."));
 
   record_btrace_set_replay (tp, &it);
-- 
2.39.2

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