コミット: efb0ddc166fc1b07a0c4564bf75b8c1c8584b1ab - binutils_os216 (git)

GNU Binutils with patches for OS216

コミットメタ情報

• リビジョン: efb0ddc166fc1b07a0c4564bf75b8c1c8584b1ab (tree)
• 日時: 2008-10-08 09:26:50
• 作者: Michael Snyder <msnyder@vmwa...>
• コミッター: Michael Snyder

ログメッセージ

2008-10-07 Michael Snyder <[e-mail]>

* target.h (to_set_exec_direction, to_get_exec_direction): Remove.
(to_can_execute_reverse): New method.
(enum exec_direction_kind): Move to inferior.h.
* target.c (update_current_target): Inherit to_can_execute_reverse.
Remove to_set_exec_direction, to_get_exec_direction.
* inferior.h (enum exec_direction_kind): Move from target.h.

* infrun.c (set_exec_direction_func): Move here from reverse.c.
(show_exec_direction_func): Ditto.
(proceed): Consult global execution_direction instead of
target method.
(handle_inferior_event): Ditto.

* reverse.c (set_exec_direction_func): Move to infrun.c
(show_exec_direction_func): Ditto.
(exec_direction_default): Set infrun global variable.
(exec_reverse_once): Consult infrun global direction variable.

* infcmd.c (step_1): Consult infrun global direction variable.
(step_once): Ditto.
(until_next_command): Ditto.
(finish_command): Ditto.

* record.h (record_exec_direction): Delete.
(RECORD_IS_REPLAY): Consult infrun global direction variable.

* record.c: (record_wait_cleanups): Use infrun state variable.
(record_wait): Ditto.
(record_get_exec_direction, record_set_exec_direction): Remove.
(record_can_execute_reverse): New target method.

* remote.c (remote_resume): Use infrun state variable.
(remote_get_exec_direction, remote_set_exec_direction): Remove.
(remote_can_execute_reverse): New target method.

変更サマリ

• modified: gdb/ChangeLog
• modified: gdb/infcmd.c
• modified: gdb/inferior.h
• modified: gdb/infrun.c
• modified: gdb/record.c
• modified: gdb/record.h
• modified: gdb/remote.c
• modified: gdb/reverse.c
• modified: gdb/target.c
• modified: gdb/target.h

差分

--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,42 @@
 2008-10-07  Michael Snyder  <[e-mail]>
 
+	* target.h (to_set_exec_direction, to_get_exec_direction): Remove.
+	(to_can_execute_reverse): New method.
+	(enum exec_direction_kind): Move to inferior.h.
+	* target.c (update_current_target): Inherit to_can_execute_reverse.
+	Remove to_set_exec_direction, to_get_exec_direction.
+	* inferior.h (enum exec_direction_kind): Move from target.h.
+
+	* infrun.c (set_exec_direction_func): Move here from reverse.c.
+	(show_exec_direction_func): Ditto.
+	(proceed): Consult global execution_direction instead of 
+	target method.
+	(handle_inferior_event): Ditto.
+
+	* reverse.c (set_exec_direction_func): Move to infrun.c
+	(show_exec_direction_func): Ditto.
+	(exec_direction_default): Set infrun global variable.
+	(exec_reverse_once): Consult infrun global direction variable.
+
+	* infcmd.c (step_1): Consult infrun global direction variable.
+	(step_once): Ditto.
+	(until_next_command): Ditto.
+	(finish_command): Ditto.
+
+	* record.h (record_exec_direction): Delete.
+	(RECORD_IS_REPLAY): Consult infrun global direction variable.
+
+	* record.c: (record_wait_cleanups): Use infrun state variable.
+	(record_wait): Ditto.
+	(record_get_exec_direction, record_set_exec_direction): Remove.
+	(record_can_execute_reverse): New target method.
+
+	* remote.c (remote_resume): Use infrun state variable.
+	(remote_get_exec_direction, remote_set_exec_direction): Remove.
+	(remote_can_execute_reverse): New target method.
+
[phone]  Michael Snyder  <[e-mail]>
+
 	* infrun.c (stepped_into_function): Rename handle_step_into_function.
 	(stepped_into_function_backward): 
 	Rename handle_step_into_function_backward.

--- a/gdb/infcmd.c
+++ b/gdb/infcmd.c
@@ -824,7 +824,7 @@ step_1 (int skip_subroutines, int single_inst, char *count_string)
 	    error (_("No current frame"));
 	  step_frame_id = get_frame_id (frame);
 
-	  if (target_get_execution_direction () == EXEC_REVERSE)
+	  if (execution_direction == EXEC_REVERSE)
 	    {
 	      frame = get_prev_frame (frame);
 	      if (frame)
@@ -942,7 +942,7 @@ step_once (int skip_subroutines, int single_inst, int count, int thread)
 	error (_("No current frame"));
       step_frame_id = get_frame_id (frame);
 
-      if (target_get_execution_direction () == EXEC_REVERSE)
+      if (execution_direction == EXEC_REVERSE)
         {
           frame = get_prev_frame (frame);
           if (frame)
@@ -1221,7 +1221,7 @@ until_next_command (int from_tty)
   step_over_calls = STEP_OVER_ALL;
   step_frame_id = get_frame_id (frame);
 
-  if (target_get_execution_direction () == EXEC_REVERSE)
+  if (execution_direction == EXEC_REVERSE)
     {
       frame = get_prev_frame (frame);
       if (frame)
@@ -1501,7 +1501,7 @@ finish_command (char *arg, int from_tty)
     error (_("Asynchronous execution not supported on this target."));
 
   /* Don't try to async in reverse.  */
-  if (async_exec && target_get_execution_direction () == EXEC_REVERSE)
+  if (async_exec && execution_direction == EXEC_REVERSE)
     error (_("Asynchronous 'finish' not supported in reverse."));
 
   /* If we are not asked to run in the bg, then prepare to run in the
@@ -1531,7 +1531,7 @@ finish_command (char *arg, int from_tty)
      source.  */
   if (from_tty)
     {
-      if (target_get_execution_direction () == EXEC_REVERSE)
+      if (execution_direction == EXEC_REVERSE)
 	printf_filtered (_("Run back to call of "));
       else
 	printf_filtered (_("Run till exit from "));
@@ -1539,7 +1539,7 @@ finish_command (char *arg, int from_tty)
       print_stack_frame (get_selected_frame (NULL), 1, LOCATION);
     }
 
-  if (target_get_execution_direction () == EXEC_REVERSE)
+  if (execution_direction == EXEC_REVERSE)
     {
       /* Split off at this point.  */
       finish_backward (function);

--- a/gdb/inferior.h
+++ b/gdb/inferior.h
@@ -386,6 +386,16 @@ enum stop_kind
 
 extern enum stop_kind stop_soon;
 
+/* Reverse execution.  */
+enum exec_direction_kind
+  {
+    EXEC_FORWARD,
+    EXEC_REVERSE,
+    EXEC_ERROR
+  };
+
+extern enum exec_direction_kind execution_direction;
+
 /* Nonzero if proceed is being used for a "finish" command or a similar
    situation when stop_registers should be saved.  */
 

--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -1223,7 +1223,7 @@ proceed (CORE_ADDR addr, enum target_signal siggnal, int step)
   if (addr == (CORE_ADDR) -1)
     {
       if (pc == stop_pc && breakpoint_here_p (pc) 
-	  && target_get_execution_direction () != EXEC_REVERSE)
+	  && execution_direction != EXEC_REVERSE)
 	/* There is a breakpoint at the address we will resume at,
 	   step one instruction before inserting breakpoints so that
 	   we do not stop right away (and report a second hit at this
@@ -2642,7 +2642,7 @@ targets should add new threads to the thread list themselves in non-stop mode.")
 	  = !(bpstat_explains_signal (stop_bpstat)
 	      || stepping_over_breakpoint
 	      || (step_range_end && step_resume_breakpoint == NULL)
-	      || (target_get_execution_direction () == EXEC_REVERSE)
+	      || (execution_direction == EXEC_REVERSE)
 	      || RECORD_IS_USED);
       else
 	{
@@ -2882,7 +2882,7 @@ infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME (!gdbarch_get_longjmp_target)\n");
 	    return;
 	  }
 	if (stop_pc == ecs->stop_func_start
-	    && target_get_execution_direction () == EXEC_REVERSE)
+	    && execution_direction == EXEC_REVERSE)
 	  {
 	    /* We are stepping over a function call in reverse, and
 	       just hit the step-resume breakpoint at the start
@@ -3063,7 +3063,7 @@ infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME (!gdbarch_get_longjmp_target)\n");
 	 keep going back to the call point).  */
       if (stop_pc == step_range_start
 	  && stop_pc != ecs->stop_func_start
-	  && target_get_execution_direction () == EXEC_REVERSE)
+	  && execution_direction == EXEC_REVERSE)
 	{
 	  stop_step = 1;
 	  print_stop_reason (END_STEPPING_RANGE, 0);
@@ -3172,7 +3172,7 @@ infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME (!gdbarch_get_longjmp_target)\n");
 	     get there, we'll need to single-step back to the
 	     caller.  */
 
-	  if (target_get_execution_direction () == EXEC_REVERSE)
+	  if (execution_direction == EXEC_REVERSE)
 	    {
 	      if (ecs->stop_func_start == 0)
 	        {
@@ -3244,7 +3244,7 @@ infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME (!gdbarch_get_longjmp_target)\n");
 	tmp_sal = find_pc_line (ecs->stop_func_start, 0);
 	if (tmp_sal.line != 0)
 	  {
-	    if (target_get_execution_direction () == EXEC_REVERSE)
+	    if (execution_direction == EXEC_REVERSE)
 	      handle_step_into_function_backward (ecs);
 	    else
 	      handle_step_into_function (ecs);
@@ -3263,7 +3263,7 @@ infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME (!gdbarch_get_longjmp_target)\n");
 	  return;
 	}
 
-      if (target_get_execution_direction () == EXEC_REVERSE)
+      if (execution_direction == EXEC_REVERSE)
 	{
 	  /* Set a breakpoint at callee's start address.
 	     From there we can step once and be back in the caller.  */
@@ -3407,7 +3407,7 @@ infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME (!gdbarch_get_longjmp_target)\n");
       if (debug_infrun)
 	 fprintf_unfiltered (gdb_stdlog, "infrun: no line number info\n");
 
-      if (target_get_execution_direction () == EXEC_REVERSE)
+      if (execution_direction == EXEC_REVERSE)
 	{
 	  /* Set a breakpoint at callee's start address.
 	     From there we can step once and be back in the caller.  */
@@ -3446,7 +3446,7 @@ infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME (!gdbarch_get_longjmp_target)\n");
       return;
     }
 
-  if (target_get_execution_direction () == EXEC_REVERSE
+  if (execution_direction == EXEC_REVERSE
       && frame_id_eq (get_frame_id (get_current_frame ()),
 		      step_prev_frame_id))
     {
@@ -3462,11 +3462,11 @@ infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME (!gdbarch_get_longjmp_target)\n");
     }
 
   if (!frame_id_eq (get_frame_id (get_current_frame ()), step_frame_id)
-      && (target_get_execution_direction () == EXEC_REVERSE
+      && (execution_direction == EXEC_REVERSE
 	  || RECORD_IS_USED))
     {
       if (stop_pc != stop_pc_sal.pc
-	   && target_get_execution_direction () == EXEC_REVERSE
+	   && execution_direction == EXEC_REVERSE
 	   && step_over_calls == STEP_OVER_ALL)
 	{
 	  if (debug_infrun)
@@ -3489,9 +3489,9 @@ infrun: BPSTAT_WHAT_SET_LONGJMP_RESUME (!gdbarch_get_longjmp_target)\n");
     } 
 #if 0
   if (((stop_pc == stop_pc_sal.pc
-	&& target_get_execution_direction () != EXEC_REVERSE)
+	&& execution_direction != EXEC_REVERSE)
        || (stop_pc >= stop_pc_sal.pc && stop_pc < stop_pc_sal.end
-	   && target_get_execution_direction () == EXEC_REVERSE))
+	   && execution_direction == EXEC_REVERSE))
       && (tss->current_line != stop_pc_sal.line
 	  || tss->current_symtab != stop_pc_sal.symtab))
     {
@@ -4917,6 +4917,55 @@ save_inferior_ptid (void)
 }
 
 
+/* User interface for reverse debugging:
+   Set exec-direction / show exec-direction commands
+   (returns error unless target implements to_set_exec_direction method).  */
+
+enum exec_direction_kind execution_direction = EXEC_FORWARD;
+static const char exec_forward[] = "forward";
+static const char exec_reverse[] = "reverse";
+static const char *exec_direction = exec_forward;
+static const char *exec_direction_names[] = {
+  exec_forward,
+  exec_reverse,
+  NULL
+};
+
+static void
+set_exec_direction_func (char *args, int from_tty,
+			 struct cmd_list_element *cmd)
+{
+  if (target_can_execute_reverse)
+    {
+      if (!strcmp (exec_direction, exec_forward))
+	execution_direction = EXEC_FORWARD;
+      else if (!strcmp (exec_direction, exec_reverse))
+	execution_direction = EXEC_REVERSE;
+    }
+}
+
+static void
+show_exec_direction_func (struct ui_file *out, int from_tty,
+			  struct cmd_list_element *cmd, const char *value)
+{
+  switch (execution_direction) {
+  case EXEC_FORWARD:
+    fprintf_filtered (out, _("Forward.\n"));
+    break;
+  case EXEC_REVERSE:
+    fprintf_filtered (out, _("Reverse.\n"));
+    break;
+  case EXEC_ERROR:
+  default:
+    fprintf_filtered (out, 
+		      _("Forward (target `%s' does not support exec-direction).\n"),
+		      target_shortname);
+    break;
+  }
+}
+
+/* User interface for non-stop mode.  */
+
 int non_stop = 0;
 static int non_stop_1 = 0;
 
@@ -5142,6 +5191,14 @@ breakpoints, even if such is supported by the target."),
 			   &maintenance_set_cmdlist,
 			   &maintenance_show_cmdlist);
 
+  add_setshow_enum_cmd ("exec-direction", class_run, exec_direction_names,
+			&exec_direction, _("Set direction of execution.\n\
+Options are 'forward' or 'reverse'."),
+			_("Show direction of execution (forward/reverse)."),
+			_("Tells gdb whether to execute forward or backward."),
+			set_exec_direction_func, show_exec_direction_func,
+			&setlist, &showlist);
+
   /* ptid initializations */
   null_ptid = ptid_build (0, 0, 0);
   minus_one_ptid = ptid_build (-1, 0, 0);

--- a/gdb/record.c
+++ b/gdb/record.c
@@ -44,7 +44,6 @@ static int record_insn_num = 0;
 
 struct target_ops record_ops;
 int record_resume_step = 0;
-enum exec_direction_kind record_exec_direction = EXEC_FORWARD;
 static int record_get_sig = 0;
 static sigset_t record_maskall;
 static int record_not_record = 0;
@@ -416,7 +415,6 @@ record_open (char *name, int from_tty)
 
   /* Reset */
   record_insn_num = 0;
-  record_exec_direction = EXEC_FORWARD;
   record_list = &record_first;
   record_list->next = NULL;
 
@@ -459,7 +457,7 @@ record_sig_handler (int signo)
 static void
 record_wait_cleanups (void *ignore)
 {
-  if (record_exec_direction == EXEC_REVERSE)
+  if (execution_direction == EXEC_REVERSE)
     {
       if (record_list->next)
 	{
@@ -517,7 +515,7 @@ record_wait (ptid_t ptid, struct target_waitstatus *status)
 
       /* In EXEC_FORWARD mode, record_list point to the tail of prev
          instruction.  */
-      if (record_exec_direction == EXEC_FORWARD && record_list->next)
+      if (execution_direction == EXEC_FORWARD && record_list->next)
         {
 	  record_list = record_list->next;
 	}
@@ -528,14 +526,14 @@ record_wait (ptid_t ptid, struct target_waitstatus *status)
       do
 	{
 	  /* Check for beginning and end of log.  */
-	  if (record_exec_direction == EXEC_REVERSE 
+	  if (execution_direction == EXEC_REVERSE 
 	      && record_list == &record_first)
 	    {
 	      /* Hit beginning of record log in reverse.  */
 	      status->kind = TARGET_WAITKIND_NO_HISTORY;
 	      break;
 	    }
-	  if (record_exec_direction != EXEC_REVERSE && !record_list->next)
+	  if (execution_direction != EXEC_REVERSE && !record_list->next)
 	    {
 	      /* Hit end of record log going forward.  */
 	      status->kind = TARGET_WAITKIND_NO_HISTORY;
@@ -603,7 +601,7 @@ record_wait (ptid_t ptid, struct target_waitstatus *status)
 				      record_list->u.need_dasm);
 		}
 
-	      if (record_exec_direction == EXEC_FORWARD)
+	      if (execution_direction == EXEC_FORWARD)
 		{
 		  need_dasm = record_list->u.need_dasm;
 		}
@@ -612,7 +610,7 @@ record_wait (ptid_t ptid, struct target_waitstatus *status)
 		  gdbarch_record_dasm (current_gdbarch);
 		}
 
-	      if (first_record_end && record_exec_direction == EXEC_REVERSE)
+	      if (first_record_end && execution_direction == EXEC_REVERSE)
 		{
 		  /* When reverse excute, the first record_end is the part of
 		     current instruction. */
@@ -666,7 +664,7 @@ record_wait (ptid_t ptid, struct target_waitstatus *status)
 			}
 		    }
 		}
-	      if (record_exec_direction == EXEC_REVERSE)
+	      if (execution_direction == EXEC_REVERSE)
 		{
 		  need_dasm = record_list->u.need_dasm;
 		}
@@ -675,7 +673,7 @@ record_wait (ptid_t ptid, struct target_waitstatus *status)
 next:
 	  if (continue_flag)
 	    {
-	      if (record_exec_direction == EXEC_REVERSE)
+	      if (execution_direction == EXEC_REVERSE)
 		{
 		  if (record_list->prev)
 		    record_list = record_list->prev;
@@ -951,29 +949,10 @@ record_remove_breakpoint (struct bp_target_info *bp_tgt)
   return 0;
 }
 
-static enum exec_direction_kind
-record_get_exec_direction (void)
-{
-  if (record_debug > 1)
-    printf_filtered ("Process record: exec_direction is %s\n",
-		     record_exec_direction == EXEC_FORWARD ? "forward" :
-		     record_exec_direction == EXEC_REVERSE ? "reverse" : "unknown");
-  return record_exec_direction;
-}
-
 static int
-record_set_exec_direction (enum exec_direction_kind dir)
+record_can_execute_reverse (void)
 {
-  if (record_debug)
-    printf_filtered ("Process record: set exec_direction: %s\n",
-		     dir == EXEC_FORWARD ? "forward" :
-		     dir == EXEC_REVERSE ? "reverse" : "bad direction");
-
-  /* FIXME: check target for capability.  */
-  if (dir == EXEC_FORWARD || dir == EXEC_REVERSE)
-    return (record_exec_direction = dir);
-  else
-    return EXEC_ERROR;
+  return 1;
 }
 
 static void
@@ -996,8 +975,7 @@ init_record_ops (void)
   record_ops.to_xfer_partial = record_xfer_partial;
   record_ops.to_insert_breakpoint = record_insert_breakpoint;
   record_ops.to_remove_breakpoint = record_remove_breakpoint;
-  record_ops.to_get_exec_direction = record_get_exec_direction;
-  record_ops.to_set_exec_direction = record_set_exec_direction;
+  record_ops.to_can_execute_reverse = record_can_execute_reverse;
   record_ops.to_stratum = record_stratum;
   record_ops.to_magic = OPS_MAGIC;
 }
@@ -1131,7 +1109,6 @@ _initialize_record (void)
   add_com_alias ("sr", "stoprecord", class_obscure, 1);
 
   /* Record instructions number limit command.  */
-  /* Teawater -- tell me if I got this one wrong.  MVS  */
   add_setshow_zinteger_cmd ("record-auto-delete", no_class,
 			    &record_insn_max_mode,
 			    _("Set record/replay auto delete mode."),

--- a/gdb/record.h
+++ b/gdb/record.h
@@ -23,7 +23,7 @@
 #define RECORD_IS_USED	\
      (current_target.beneath == &record_ops)
 #define RECORD_IS_REPLAY  \
-     (record_list->next || record_exec_direction == EXEC_REVERSE)
+     (record_list->next || execution_direction == EXEC_REVERSE)
 #define RECORD_TARGET_SUPPORT_RECORD_WAIT  \
      (record_ops.beneath->to_support_record_wait)
 
@@ -78,7 +78,6 @@ extern struct regcache *record_regcache;
 
 extern struct target_ops record_ops;
 extern int record_resume_step;
-extern enum exec_direction_kind record_exec_direction;
 
 extern int record_arch_list_add_reg (int num);
 extern int record_arch_list_add_mem (CORE_ADDR addr, int len);

--- a/gdb/remote.c
+++ b/gdb/remote.c
@@ -3210,7 +3210,7 @@ remote_resume (ptid_t ptid, int step, enum target_signal siggnal)
     set_continue_thread (ptid);
 
   buf = rs->buf;
-  if (target_get_execution_direction () == EXEC_REVERSE)
+  if (execution_direction == EXEC_REVERSE)
     {
       /* We don't pass signals to the target in reverse exec mode.  */
       if (info_verbose && siggnal != TARGET_SIGNAL_0)
@@ -7131,34 +7131,12 @@ remote_command (char *args, int from_tty)
   help_list (remote_cmdlist, "remote ", -1, gdb_stdout);
 }
 
-/* Reverse execution.
-   FIXME: set up as a capability.  */
-static enum exec_direction_kind remote_exec_direction = EXEC_FORWARD;
+static int remote_target_can_reverse = 1;
 
-static enum exec_direction_kind 
-remote_get_exec_direction (void)
-{
-  if (remote_debug && info_verbose)
-    printf_filtered ("remote exec_direction is %s\n",
-		     remote_exec_direction == EXEC_FORWARD ? _("forward") :
-		     remote_exec_direction == EXEC_REVERSE ? _("reverse") :
-		     _("unknown"));
-  return remote_exec_direction;
-}
-
-static int remote_set_exec_direction (enum exec_direction_kind dir)
+static int
+remote_can_execute_reverse (void)
 {
-  if (remote_debug && info_verbose)
-    printf_filtered ("Set remote exec_direction: %s\n",
-		     dir == EXEC_FORWARD ? _("forward") :
-		     dir == EXEC_REVERSE ? _("reverse") :
-		     _("bad direction"));
-
-  /* FIXME: check target for capability.  */
-  if (dir == EXEC_FORWARD || dir == EXEC_REVERSE)
-    return (remote_exec_direction = dir);
-  else
-    return EXEC_ERROR;
+  return remote_target_can_reverse;
 }
 
 static void
@@ -7209,8 +7187,7 @@ Specify the serial device it is connected to\n\
   remote_ops.to_has_registers = 1;
   remote_ops.to_has_execution = 1;
   remote_ops.to_has_thread_control = tc_schedlock;	/* can lock scheduler */
-  remote_ops.to_get_exec_direction = remote_get_exec_direction;
-  remote_ops.to_set_exec_direction = remote_set_exec_direction;
+  remote_ops.to_can_execute_reverse = remote_can_execute_reverse;
   remote_ops.to_magic = OPS_MAGIC;
   remote_ops.to_memory_map = remote_memory_map;
   remote_ops.to_flash_erase = remote_flash_erase;

--- a/gdb/reverse.c
+++ b/gdb/reverse.c
@@ -25,68 +25,15 @@
 #include "top.h"
 #include "cli/cli-cmds.h"
 #include "cli/cli-decode.h"
-
-/* User interface for reverse debugging:
-   Set exec-direction / show exec-direction commands
-   (returns error unless target implements to_set_exec_direction method).  */
-
-static const char exec_forward[] = "forward";
-static const char exec_reverse[] = "reverse";
-static const char *exec_direction = exec_forward;
-static const char *exec_direction_names[] = {
-  exec_forward,
-  exec_reverse,
-  NULL
-};
-
-static void
-set_exec_direction_func (char *args, int from_tty,
-			 struct cmd_list_element *cmd)
-{
-  if (target_get_execution_direction () != EXEC_ERROR)
-    {
-      enum exec_direction_kind dir = EXEC_ERROR;
-
-      if (!strcmp (exec_direction, exec_forward))
-	dir = EXEC_FORWARD;
-      else if (!strcmp (exec_direction, exec_reverse))
-	dir = EXEC_REVERSE;
-
-      if (target_set_execution_direction (dir) != EXEC_ERROR)
-	return;
-    }
-}
-
-static void
-show_exec_direction_func (struct ui_file *out, int from_tty,
-			  struct cmd_list_element *cmd, const char *value)
-{
-  enum exec_direction_kind dir = target_get_execution_direction ();
-
-  switch (dir) {
-  case EXEC_FORWARD:
-    fprintf_filtered (out, _("Forward.\n"));
-    break;
-  case EXEC_REVERSE:
-    fprintf_filtered (out, _("Reverse.\n"));
-    break;
-  case EXEC_ERROR:
-  default:
-    fprintf_filtered (out, 
-		      _("Forward (target `%s' does not support exec-direction).\n"),
-		      target_shortname);
-    break;
-  }
-}
+#include "inferior.h"
 
 /* User interface:
-   reverse-step, reverse-next etc.
-   (returns error unles target implements to_set_exec_direction method).  */
+   reverse-step, reverse-next etc.  */
 
 static void exec_direction_default (void *notused)
 {
   /* Return execution direction to default state.  */
-  target_set_execution_direction (EXEC_FORWARD);
+  execution_direction = EXEC_FORWARD;
 }
 
 /* exec_reverse_once -- accepts an arbitrary gdb command (string),
@@ -99,7 +46,7 @@ exec_reverse_once (char *cmd, char *args, int from_tty)
 {
   /* String buffer for command consing.  */
   char reverse_command[512];
-  enum exec_direction_kind dir = target_get_execution_direction ();
+  enum exec_direction_kind dir = execution_direction;
   struct cleanup *old_chain;
 
   if (dir == EXEC_ERROR)
@@ -109,11 +56,13 @@ exec_reverse_once (char *cmd, char *args, int from_tty)
     error (_("Already in reverse mode.  Use '%s' or 'set exec-dir forward'."),
 	   cmd);
 
-  if (target_set_execution_direction (EXEC_REVERSE) == EXEC_ERROR)
+  if (!target_can_execute_reverse)
     error (_("Target %s does not support this command."), target_shortname);
 
   old_chain = make_cleanup (exec_direction_default, NULL);
   sprintf (reverse_command, "%s %s", cmd, args ? args : "");
+
+  execution_direction = EXEC_REVERSE;
   execute_command (reverse_command, from_tty);
   do_cleanups (old_chain);
 }
@@ -157,14 +106,6 @@ reverse_finish (char *args, int from_tty)
 void
 _initialize_reverse (void)
 {
-  add_setshow_enum_cmd ("exec-direction", class_run, exec_direction_names,
-			&exec_direction, _("Set direction of execution.\n\
-Options are 'forward' or 'reverse'."),
-			_("Show direction of execution (forward/reverse)."),
-			_("Tells gdb whether to execute forward or backward."),
-			set_exec_direction_func, show_exec_direction_func,
-			&setlist, &showlist);
-
   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).")

--- a/gdb/target.c
+++ b/gdb/target.c
@@ -486,8 +486,7 @@ update_current_target (void)
       INHERIT (to_find_memory_regions, t);
       INHERIT (to_make_corefile_notes, t);
       INHERIT (to_get_thread_local_address, t);
-      INHERIT (to_get_exec_direction, t);
-      INHERIT (to_set_exec_direction, t);
+      INHERIT (to_can_execute_reverse, t);
       /* Do not inherit to_read_description.  */
       /* Do not inherit to_search_memory.  */
       INHERIT (to_magic, t);

--- a/gdb/target.h
+++ b/gdb/target.h
@@ -152,14 +152,6 @@ struct target_waitstatus
     value;
   };
 
-/* Reverse execution.  */
-enum exec_direction_kind
-  {
-    EXEC_FORWARD,
-    EXEC_REVERSE,
-    EXEC_ERROR
-  };
-
 /* Possible types of events that the inferior handler will have to
    deal with.  */
 enum inferior_event_type
@@ -535,10 +527,8 @@ struct target_ops
 			     const gdb_byte *pattern, ULONGEST pattern_len,
 			     CORE_ADDR *found_addrp);
 
-    /* Set execution direction (forward/reverse).  */
-    int (*to_set_exec_direction) (enum exec_direction_kind);
-    /* Get execution direction (forward/reverse).  */
-    enum exec_direction_kind (*to_get_exec_direction) (void);
+    /* Can target execute in reverse?  */
+    int (*to_can_execute_reverse) ();
 
     /* Default value is 0. Mean that this target doesn't support record wait.
        Need the help of infrun.c(handle_inferior_event). Set to 1 if this
@@ -1143,17 +1133,10 @@ extern int target_stopped_data_address_p (struct target_ops *);
 #define target_watchpoint_addr_within_range(target, addr, start, length) \
   (*target.to_watchpoint_addr_within_range) (target, addr, start, length)
 
-/* Forward/reverse execution direction.
-   These will only be implemented by a target that supports reverse execution.
-*/
-#define target_get_execution_direction() \
-    (current_target.to_get_exec_direction ? \
-     (*current_target.to_get_exec_direction) () : EXEC_ERROR)
-
-#define target_set_execution_direction(DIR) \
-    (current_target.to_set_exec_direction ? \
-     (*current_target.to_set_exec_direction) (DIR) : EXEC_ERROR)
-
+/* Target can execute in reverse?  */
+#define target_can_execute_reverse \
+     (current_target.to_can_execute_reverse ? \
+      current_target.to_can_execute_reverse () : 0)
 
 extern const struct target_desc *target_read_description (struct target_ops *);