btrace: Handle stepping and goto for auxiliary instructions.

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.

Approved-By: Markus Metzger <markus.t.metzger@intel.com>

diff --git a/gdb/record-btrace.c b/gdb/record-btrace.c
index 92c01dcf0157b6810178282d4deb796d568ea30a..8b1c9e1e4c84f01ed452e530cf58e0b3c650d288 100644 (file)
--- a/gdb/record-btrace.c
+++ b/gdb/record-btrace.c
@@ -2391,9 +2391,13 @@ 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;
 
@@ -2405,8 +2409,23 @@ record_btrace_single_step_forward (struct thread_info *tp)
          *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)
+       {
+         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);
@@ -2437,9 +2456,12 @@ 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;
 
@@ -2449,8 +2471,22 @@ 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.
 
@@ -2872,26 +2908,33 @@ 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
+     auxiliary instruction.  */
+  if (found == 0)
+    error (_("No such instruction."));
+
+  const struct btrace_insn *insn = btrace_insn_get (&it);
+  if (insn == NULL)
     error (_("No such instruction."));
+  if (insn->iclass == BTRACE_INSN_AUX)
+    error (_("Can't go to an auxiliary instruction."));
 
   record_btrace_set_replay (tp, &it);
 }