2008-10-17 Michael Snyder <msnyder@vmware.com>

Target interface for reverse debugging.
	* target.h (enum target_waitkind):
	Add new wait event, TARGET_WAITKIND_NO_HISTORY.
	(struct target_ops): New method to_can_execute_reverse.
	(target_can_execute_reverse): New macro.
	* target.c (update_current_target): Inherit to_can_execute_reverse.

	Remote interface for reverse debugging.
	* remote.c (remote_can_execute_reverse): New target method.
	(remote_resume): Check for reverse exec direction, and send
	appropriate command to target.
	(remote_wait_as): Check target response for NO_HISTORY status.
	Also check for empty reply (target doesn't understand "bs" or "bc).
	(remote_vcont_resume): Jump out if attempting reverse execution.

	Event handling interface for reverse debugging.
	* infrun.c (execution_direction): New state variable.
	(enum inferior_stop_reason): Add NO_HISTORY reason.
	(handle_inferior_event): Handle TARGET_WAITKIND_NO_HISTORY.
	Handle stepping over a function call in reverse.
	Handle stepping thru a line range in reverse.
	Handle setting a step-resume breakpoint in reverse.
	Handle stepping into a function in reverse.
	Handle stepping between line ranges in reverse.
	(print_stop_reason): Print reason for NO_HISTORY.
	(step_into_function): Rename to handle_step_into_function.
	(handle_step_into_function_backward): New function.
	(set_exec_direction_func, show_exec_direction_func): New funcs.
	(proceed): No need to singlestep over a breakpoint
	when resuming in reverse.

	* inferior.h (enum exec_direction_kind): New enum.
	(execution_direction): Export new execution state variable.

	* breakpoint.c (make_breakpoint_silent): New function.
	* breakpoint.h (make_breakpoint_silent): Export.
	* infcmd.c (finish_command): Check for reverse exec direction.
	(finish_backward): New function, handle finish cmd in reverse.

	User interface for reverse execution.
	* Makefile.in (reverse.c): New file.
	* reverse.c: New file.  User interface for reverse execution.

gdb/reverse.c

@@ -0,0 +1,143 @@
+/* Reverse execution and reverse debugging.
+
+   Copyright (C) 2006, 2007, 2008 Free Software Foundation, Inc.
+
+   This file is part of GDB.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 2 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, write to the Free Software
+   Foundation, Inc., 51 Franklin Street, Fifth Floor,
+   Boston, MA 02110-1301, USA.  */
+
+#include "defs.h"
+#include "gdb_string.h"
+#include "target.h"
+#include "top.h"
+#include "cli/cli-cmds.h"
+#include "cli/cli-decode.h"
+#include "inferior.h"
+
+/* User interface:
+   reverse-step, reverse-next etc.  */
+
+static void exec_direction_default (void *notused)
+{
+  /* Return execution direction to default state.  */
+  execution_direction = EXEC_FORWARD;
+}
+
+/* exec_reverse_once -- accepts an arbitrary gdb command (string), 
+   and executes it with exec-direction set to 'reverse'.
+
+   Used to implement reverse-next etc. commands.  */
+
+static void
+exec_reverse_once (char *cmd, char *args, int from_tty)
+{
+  char *reverse_command;
+  enum exec_direction_kind dir = execution_direction;
+  struct cleanup *old_chain;
+
+  if (dir == EXEC_ERROR)
+    error (_("Target %s does not support this command."), target_shortname);
+
+  if (dir == EXEC_REVERSE)
+    error (_("Already in reverse mode.  Use '%s' or 'set exec-dir forward'."),
+	   cmd);
+
+  if (!target_can_execute_reverse)
+    error (_("Target %s does not support this command."), target_shortname);
+
+  reverse_command = xstrprintf ("%s %s", cmd, args ? args : "");
+  old_chain = make_cleanup (exec_direction_default, NULL);
+  make_cleanup (xfree, reverse_command);
+  execution_direction = EXEC_REVERSE;
+  execute_command (reverse_command, from_tty);
+  do_cleanups (old_chain);
+}
+
+static void
+reverse_step (char *args, int from_tty)
+{
+  exec_reverse_once ("step", args, from_tty);
+}
+
+static void
+reverse_stepi (char *args, int from_tty)
+{
+  exec_reverse_once ("stepi", args, from_tty);
+}
+
+static void
+reverse_next (char *args, int from_tty)
+{
+  exec_reverse_once ("next", args, from_tty);
+}
+
+static void
+reverse_nexti (char *args, int from_tty)
+{
+  exec_reverse_once ("nexti", args, from_tty);
+}
+
+static void
+reverse_continue (char *args, int from_tty)
+{
+  exec_reverse_once ("continue", args, from_tty);
+}
+
+static void
+reverse_finish (char *args, int from_tty)
+{
+  exec_reverse_once ("finish", args, from_tty);
+}
+
+void
+_initialize_reverse (void)
+{
+  add_com ("reverse-step", class_run, reverse_step, _("\
+Step program backward until it reaches the beginning of another source line.\n\
+Argument N means do this N times (or till program stops for another reason).")
+	   );
+  add_com_alias ("rs", "reverse-step", class_alias, 1);
+
+  add_com ("reverse-next", class_run, reverse_next, _("\
+Step program backward, proceeding through subroutine calls.\n\
+Like the \"reverse-step\" command as long as subroutine calls do not happen;\n\
+when they do, the call is treated as one instruction.\n\
+Argument N means do this N times (or till program stops for another reason).")
+	   );
+  add_com_alias ("rn", "reverse-next", class_alias, 1);
+
+  add_com ("reverse-stepi", class_run, reverse_stepi, _("\
+Step backward exactly one instruction.\n\
+Argument N means do this N times (or till program stops for another reason).")
+	   );
+  add_com_alias ("rsi", "reverse-stepi", class_alias, 0);
+
+  add_com ("reverse-nexti", class_run, reverse_nexti, _("\
+Step backward one instruction, but proceed through called subroutines.\n\
+Argument N means do this N times (or till program stops for another reason).")
+	   );
+  add_com_alias ("rni", "reverse-nexti", class_alias, 0);
+
+  add_com ("reverse-continue", class_run, reverse_continue, _("\
+Continue program being debugged but run it in reverse.\n\
+If proceeding from breakpoint, a number N may be used as an argument,\n\
+which means to set the ignore count of that breakpoint to N - 1 (so that\n\
+the breakpoint won't break until the Nth time it is reached)."));
+  add_com_alias ("rc", "reverse-continue", class_alias, 0);
+
+  add_com ("reverse-finish", class_run, reverse_finish, _("\
+Execute backward until just before selected stack frame is called."));
+}