[rfc 7/8] record: add "record backtrace" command

[markus dot t dot metzger at intel dot com]

From: Markus Metzger <markus.t.metzger@intel.com>

Add a "record backtrace" command to print a backtrace of recorded functions.

The command supports iterating over the execution log similar to the "list"
command.

This command provides a quick high-level overview over the recorded execution
log without having to reverse-step.

2013-02-14 Markus Metzger <markus.t.metzger@intel.com>

	* target.c (target_backtrace_record): New.
	(target_backtrace_record_range): New.
	* target.h (target_ops) <to_backtrace_record,
	to_backtrace_record_range>: New fields.
	(target_disas_record, target_disas_record_range): New declaration.
	* record.c (get_insn_range, get_backtrace_modifiers,
	cmd_record_backtrace, record_backtrace_size): New.
	(_initialize_record): Add the "record backtrace" command.
	Add an alias "record bt" to it. Add "set/show record
	backtrace-size" commands.
	* record.h (record_print_flag): New.


---
 gdb/record.c |  145 ++++++++++++++++++++++++++++++++++++++++++++++++++-------
 gdb/record.h |    7 +++
 gdb/target.c |   34 ++++++++++++++
 gdb/target.h |   13 +++++
 4 files changed, 181 insertions(+), 18 deletions(-)

diff --git a/gdb/record.c b/gdb/record.c
index 3ac4765..925e4c1 100644
--- a/gdb/record.c
+++ b/gdb/record.c
@@ -35,6 +35,9 @@ unsigned int record_debug = 0;
 /* The number of instructions to disassemble in "record disas".  */
 static unsigned int record_disas_size = 10;
 
+/* The number of functions to print in "record backtrace".  */
+static unsigned int record_backtrace_size = 10;
+
 struct cmd_list_element *record_cmdlist = NULL;
 struct cmd_list_element *set_record_cmdlist = NULL;
 struct cmd_list_element *show_record_cmdlist = NULL;
@@ -317,6 +320,42 @@ get_insn_number (char **arg)
   return number;
 }
 
+/* Read an instruction range from an argument string.  */
+
+static void
+get_insn_range (char **arg, unsigned int context,
+		ULONGEST *pbegin, ULONGEST *pend)
+{
+  ULONGEST begin, end;
+
+  begin = get_insn_number (arg);
+
+  if (**arg == ',')
+    {
+      *arg += 1;
+      end = get_insn_number (arg);
+    }
+  else
+    {
+      ULONGEST before;
+
+      /* If the execution log does not start at zero, we might not
+	 cover the entire context.  */
+      before = context / 2;
+      if (begin < before)
+	before = begin;
+
+      begin -= before;
+      end = begin + context;
+    }
+
+  if (**arg != 0)
+    error (_("Junk after argument: %s."), *arg);
+
+  *pbegin = begin;
+  *pend = end;
+}
+
 /* Read disassembly modifiers from an argument string.  */
 
 static int
@@ -396,32 +435,80 @@ cmd_record_disas (char *arg, int from_tty)
     {
       ULONGEST begin, end;
 
-      begin = get_insn_number (&arg);
+      get_insn_range (&arg, record_disas_size, &begin, &end);
+      target_disas_record_range (begin, end, flags);
+    }
+}
+
+/* Read backtrace modifiers from an argument string.  */
+
+static int
+get_backtrace_modifiers (char **arg)
+{
+  int modifiers;
+  char *args;
+
+  modifiers = 0;
+  args = *arg;
+
+  if (args == NULL)
+    return modifiers;
+
+  while (*args == '/')
+    {
+      ++args;
 
-      if (*arg == ',')
+      if (*args == '\0')
+	error (_("Missing modifier."));
+
+      for (; *args; ++args)
 	{
-	  ++arg;
-	  end = get_insn_number (&arg);
+	  if (isspace (*args))
+	    break;
+
+	  if (*args == '/')
+	    continue;
+
+	  switch (*args)
+	    {
+	    case 'l':
+	      modifiers |= record_print_src_line;
+	      break;
+	    default:
+	      error (_("Invalid modifier: %c."), *args);
+	    }
 	}
-      else
-	{
-	  ULONGEST before;
 
-	  /* If the execution log does not start at zero, we might not
-	     disassemble the entire record_disas_size instructions.  */
+      args = skip_spaces (args);
+    }
 
-	  before = record_disas_size / 2;
-	  if (begin < before)
-	    before = begin;
+  /* Update the argument string.  */
+  *arg = args;
 
-	  begin -= before;
-	  end = begin + record_disas_size;
-	}
+  return modifiers;
+}
 
-      if (*arg != 0)
-	error (_("Junk after argument: %s."), arg);
+/* The "record backtrace" command.  */
 
-      target_disas_record_range (begin, end, flags);
+static void
+cmd_record_backtrace (char *arg, int from_tty)
+{
+  int flags;
+
+  require_record_target ();
+
+  flags = get_backtrace_modifiers (&arg);
+
+  if (arg == NULL || *arg == 0 || strcmp (arg, "+") == 0)
+    target_backtrace_record ((int) record_backtrace_size, flags);
+  else if (strcmp (arg, "-") == 0)
+    target_backtrace_record (- (int) record_backtrace_size, flags);
+  else
+    {
+      ULONGEST begin, end;
+
+      get_insn_range (&arg, record_backtrace_size, &begin, &end);
+      target_backtrace_record_range (begin, end, flags);
     }
 }
 
@@ -447,6 +534,13 @@ Show number of instructions to print in \"record disassemble\"."),
 			    NULL, NULL, NULL, &set_record_cmdlist,
 			    &show_record_cmdlist);
 
+  add_setshow_uinteger_cmd ("backtrace-size", no_class,
+			    &record_backtrace_size, _("\
+Set number of function to print in \"record backtrace\"."), _("\
+Show number of functions to print in \"record backtrace\"."),
+			    NULL, NULL, NULL, &set_record_cmdlist,
+			    &show_record_cmdlist);
+
   c = add_prefix_cmd ("record", class_obscure, cmd_record_start,
 		      _("Start recording."),
 		      &record_cmdlist, "record ", 0, &cmdlist);
@@ -505,4 +599,19 @@ disassemble.\n\
 The number of instructions to disassemble can be defined with \"set record \
 disas-size\"."),
            &record_cmdlist);
+
+  add_cmd ("backtrace", class_obscure, cmd_record_backtrace, _("\
+Print a backtrace of recorded functions.\n\
+With a /l modifier, the source file and line number is included.\n\
+With no argument, prints ten more functions after or around the previous \
+backtrace.\n\
+\"backtrace -\" prints ten functions before a previous ten-line backtrace.\n\
+One argument specifies an instruction, and a ten function backtrace is \
+printed starting at that instruction.\n\
+Two arguments with comma between specify starting and ending instructions. \
+Prints all functions in this range.\n\
+The number of functions to print can be defined with \"set record \
+backtrace-size\"."),
+           &record_cmdlist);
+  add_alias_cmd ("bt", "backtrace", class_obscure, 1, &record_cmdlist);
 }
diff --git a/gdb/record.h b/gdb/record.h
index 04d6b4a..e9d4bcd 100644
--- a/gdb/record.h
+++ b/gdb/record.h
@@ -32,6 +32,13 @@ extern struct cmd_list_element *set_record_cmdlist;
 extern struct cmd_list_element *show_record_cmdlist;
 extern struct cmd_list_element *info_record_cmdlist;
 
+/* A list of flags specifying what record target methods should print.  */
+enum record_print_flag
+  {
+    /* Print the source file and line (if applicable).  */
+    record_print_src_line = (1 << 0)
+  };
+
 /* Wrapper for target_read_memory that prints a debug message if
    reading memory fails.  */
 extern int record_read_memory (struct gdbarch *gdbarch,
diff --git a/gdb/target.c b/gdb/target.c
index 3a03f69..940e6b8 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -4394,6 +4394,40 @@ target_disas_record_range (ULONGEST begin, ULONGEST end, int flags)
   tcomplain ();
 }
 
+/* See target.h.  */
+
+void
+target_backtrace_record (int size, int flags)
+{
+  struct target_ops *t;
+
+  for (t = current_target.beneath; t != NULL; t = t->beneath)
+    if (t->to_backtrace_record != NULL)
+      {
+	t->to_backtrace_record (size, flags);
+	return;
+      }
+
+  tcomplain ();
+}
+
+/* See target.h.  */
+
+void
+target_backtrace_record_range (ULONGEST begin, ULONGEST end, int flags)
+{
+  struct target_ops *t;
+
+  for (t = current_target.beneath; t != NULL; t = t->beneath)
+    if (t->to_backtrace_record_range != NULL)
+      {
+	t->to_backtrace_record_range (begin, end, flags);
+	return;
+      }
+
+  tcomplain ();
+}
+
 static void
 debug_to_prepare_to_store (struct regcache *regcache)
 {
diff --git a/gdb/target.h b/gdb/target.h
index 4100bb9..b670660 100644
--- a/gdb/target.h
+++ b/gdb/target.h
@@ -903,6 +903,12 @@ struct target_ops
     /* Disassemble a section of the recorded execution trace.  */
     void (*to_disas_record_range) (ULONGEST begin, ULONGEST end, int flags);
 
+    /* Print a function trace of the recorded execution trace.  */
+    void (*to_backtrace_record) (int size, int flags);
+
+    /* Print a function trace of an execution trace section.  */
+    void (*to_backtrace_record_range) (ULONGEST begin, ULONGEST end, int flags);
+
     int to_magic;
     /* Need sub-structure for target machine related rather than comm related?
      */
@@ -1995,4 +2001,11 @@ extern void target_disas_record (int size, int flags);
 /* See to_disas_record_range.  */
 extern void target_disas_record_range (ULONGEST begin, ULONGEST end, int flags);
 
+/* See to_backtrace_record.  */
+extern void target_backtrace_record (int size, int flags);
+
+/* See to_backtrace_record_range.  */
+extern void target_backtrace_record_range (ULONGEST begin, ULONGEST end,
+					   int flags);
+
 #endif /* !defined (TARGET_H) */
-- 
1.7.1