Re: [RFA] Displaced stepping just enable in non-stop mode

[teawater <teawater@gmail.com>]

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Hi Joel,

According to your mail, I make a new patch.

2008-10-08  Hui Zhu  <teawater@gmail.com>

	Displaced stepping can be set to
	auto (enable in non-stop mode), on, off.

	* infrun.c (can_use_displaced_stepping): Change type to const
	char pointer.
	(can_use_displaced_stepping_auto): New string.
	(can_use_displaced_stepping_on): New string.
	(can_use_displaced_stepping_off): New string.
	(can_use_displaced_stepping_enum): New array.
	(use_displaced_stepping): Return non-zero if displaced stepping
 	is auto, and can be used with GDBARCH, and in non-stop mode.
	Return non-zero if displaced stepping is on, and can be used
	with GDBARCH.
	(_initialize_infrun): "can-use-displaced-stepping" function
	change to add_setshow_enum_cmd.

Thanks,
Hui

On Tue, Oct 7, 2008 at 20:17, Joel Brobecker <brobecker@adacore.com> wrote:
>> 2008-10-07  Hui Zhu  <teawater@gmail.com>
>>
>>       * infrun.c (use_displaced_stepping): Displaced stepping just
>>       enable in non-stop mode.
>
> There is still a piece missing. Namely, allow the user to force
> displaced-stepping in a mode that is not non-stop.  Pedro suggested that
> we either change the maint command, or add a new one. How about changing
> the maint command into a mainstream command that's a tri-state:
>
>  set use-displaced-stepping (auto|on|off)
>
> By default, it's "auto" which means that the debugger tries to determine
> from the situation whether it's necessary or not (basically if non-stop).
> But the user can then override the decision either way.
>
> --
> Joel
>

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--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,21 @@
+2008-10-08  Hui Zhu  <teawater@gmail.com>
+
+	Displaced stepping can be set to
+	auto (enable in non-stop mode), on, off.
+
+	* infrun.c (can_use_displaced_stepping): Change type to const
+	char pointer.
+	(can_use_displaced_stepping_auto): New string.
+	(can_use_displaced_stepping_on): New string.
+	(can_use_displaced_stepping_off): New string.
+	(can_use_displaced_stepping_enum): New array.
+	(use_displaced_stepping): Return non-zero if displaced stepping
+ 	is auto, and can be used with GDBARCH, and in non-stop mode.
+	Return non-zero if displaced stepping is on, and can be used
+	with GDBARCH.
+	(_initialize_infrun): "can-use-displaced-stepping" function
+	change to add_setshow_enum_cmd.
+
 2008-10-06  Doug Evans  <dje@google.com>
 
 	* dwarf2read.c (dwarf2_die_debug): New static global.
--- a/infrun.c
+++ b/infrun.c
@@ -553,10 +553,22 @@ static CORE_ADDR displaced_step_original
 /* Saved contents of copy area.  */
 static gdb_byte *displaced_step_saved_copy;
 
-/* When this is non-zero, we are allowed to use displaced stepping, if
-   the architecture supports it.  When this is zero, we use
+/* When this is auto, we are allowed to use displaced stepping,
+   If the architecture supports it and in non-stop mode.
+   When this is on, we are allowed to use displaced stepping, if
+   the architecture supports it.  When this is off, we use
    traditional the hold-and-step approach.  */
-int can_use_displaced_stepping = 1;
+const char can_use_displaced_stepping_auto[] = "auto";
+const char can_use_displaced_stepping_on[] = "on";
+const char can_use_displaced_stepping_off[] = "off";
+const char *can_use_displaced_stepping_enum[] =
+{
+  can_use_displaced_stepping_auto,
+  can_use_displaced_stepping_on,
+  can_use_displaced_stepping_off,
+  NULL,
+};
+const char *can_use_displaced_stepping = can_use_displaced_stepping_auto;
 static void
 show_can_use_displaced_stepping (struct ui_file *file, int from_tty,
 				 struct cmd_list_element *c,
@@ -567,12 +579,16 @@ Debugger's willingness to use displaced 
 "breakpoints is %s.\n"), value);
 }
 
-/* Return non-zero if displaced stepping is enabled, and can be used
+/* Return non-zero if displaced stepping is auto, and can be used
+   with GDBARCH, and in non-stop mode.
+   Return non-zero if displaced stepping is on, and can be used
    with GDBARCH.  */
 static int
 use_displaced_stepping (struct gdbarch *gdbarch)
 {
-  return (can_use_displaced_stepping
+  return (((can_use_displaced_stepping == can_use_displaced_stepping_auto
+	    && non_stop)
+	   || can_use_displaced_stepping == can_use_displaced_stepping_on)
 	  && gdbarch_displaced_step_copy_insn_p (gdbarch));
 }
 
@@ -4857,11 +4873,14 @@ function is skipped and the step command
 			   show_step_stop_if_no_debug,
 			   &setlist, &showlist);
 
-  add_setshow_boolean_cmd ("can-use-displaced-stepping", class_maintenance,
+  add_setshow_enum_cmd ("can-use-displaced-stepping", class_maintenance,
+			   can_use_displaced_stepping_enum,
 			   &can_use_displaced_stepping, _("\
 Set debugger's willingness to use displaced stepping."), _("\
 Show debugger's willingness to use displaced stepping."), _("\
-If zero, gdb will not use displaced stepping to step over\n\
+If auto, gdb will auto use displaced stepping if it need (in non-stop mode).\n\
+If on, gdb will use displaced stepping if such is supported by the target.\n\
+If off, gdb will not use displaced stepping to step over\n\
 breakpoints, even if such is supported by the target."),
 			   NULL,
 			   show_can_use_displaced_stepping,