Add a third mode to "breakpoints always-inserted", and make it the default

[Pedro Alves <pedro at codesourcery dot com>]

Non-stop mode requires that breakpoints always be inserted
in the inferior.  We currently set that with "set breakpoints always-inserted"
prior to switching to non-stop mode with "set non-stop on".

The default setting of "set breakpoints always-inserted" is "off",
as that is how GDB has been behaving for ages.

Since non-stop requires breakpoints always-in, its just cumbersome
to have to issue more than one command to enable non-stop mode.

So, this patch changes the "set breakpoints always-inserted" setting to
be a three-state.  on and off, the same as before, and a new mode,
"follow-non-stop".  In the latter mode, GDB will behave as "on", if
we're in non-stop mode, and as "off" if we're in all-stop mode.

This mode will be the default.

 (gdb) show non-stop
 Controlling the inferior in non-stop mode is off.

We're in all-stop.

 (gdb) show breakpoint always-inserted
 Always inserted breakpoint mode is follow-non-stop (currently off).

GDB shows that the effect is as if "off".

 (gdb) set non-stop on

Turns non-stop on.

 (gdb) show breakpoint always-inserted
 Always inserted breakpoint mode is follow-non-stop (currently on).

GDB shows that the effect is as if "on".

 (gdb) set non-stop off

Back to all-stop.

 (gdb) set breakpoint always-inserted on

Force "on".  Useful for testing.

 (gdb) show breakpoint always-inserted
 Always inserted breakpoint mode is on.

Now GDB shows that "on", independently of the non-stop mode.

What do you think?

If the idea is sound, does the patch look ok?
How about the docs?

-- 
Pedro Alves

gdb/
2008-08-12  Pedro Alves  <pedro@codesourcery.com>

	* breakpoint.c (always_inserted_follow_non_stop)
	(always_inserted_on, always_inserted_off, always_inserted_enums):
	New.
	(always_inserted_mode): Change type to char* and point to
	always_inserted_follow_non_stop.
	(show_always_inserted_mode): In follow-non-stop mode, also show
	the current effect of the option.
	(breakpoints_always_inserted_mode): Adjust for the new
	follow_non_stop mode mode.
	(_initialize_breakpoint): Make the "set breakpoints
	always-inserted" command an enum command.  Extend help to describe
	the follow-non-stop mode.

gdb/doc/
2008-08-12  Pedro Alves  <pedro@codesourcery.com>

	* gdb.texinfo (breakpoint always-inserted) Describe the
	follow-non-stop mode setting, and make it the default.
	
---
 gdb/breakpoint.c    |   61 +++++++++++++++++++++++++++++++++++-----------------
 gdb/doc/gdb.texinfo |    8 +++++-
 2 files changed, 49 insertions(+), 20 deletions(-)

Index: src/gdb/breakpoint.c
===================================================================
--- src.orig/gdb/breakpoint.c	2008-08-11 23:25:14.000000000 +0100
+++ src/gdb/breakpoint.c	2008-08-12 00:28:50.000000000 +0100
@@ -249,18 +249,41 @@ Automatic usage of hardware breakpoints 
 		    value);
 }
 
-/* If 1, gdb will keep breakpoints inserted even as inferior is stopped, 
-   and immediately insert any new breakpoints.  If 0, gdb will insert 
-   breakpoints into inferior only when resuming it, and will remove 
-   breakpoints upon stop.  */
-static int always_inserted_mode = 0;
-static void 
+/* If on, gdb will keep breakpoints inserted even as inferior is
+   stopped, and immediately insert any new breakpoints.  If off, gdb
+   will insert breakpoints into inferior only when resuming it, and
+   will remove breakpoints upon stop.  If follow-non-stop, GDB will
+   behave as ON if in non-stop mode, and as OFF if all-stop mode.*/
+
+static const char always_inserted_follow_non_stop[] = "follow-non-stop";
+static const char always_inserted_on[] = "on";
+static const char always_inserted_off[] = "off";
+static const char *always_inserted_enums[] = {
+  always_inserted_follow_non_stop,
+  always_inserted_off,
+  always_inserted_on,
+  NULL
+};
+static const char *always_inserted_mode = always_inserted_follow_non_stop;
+static void
 show_always_inserted_mode (struct ui_file *file, int from_tty,
-			   struct cmd_list_element *c, const char *value)
+		     struct cmd_list_element *c, const char *value)
 {
-  fprintf_filtered (file, _("Always inserted breakpoint mode is %s.\n"), value);
+  if (always_inserted_mode == always_inserted_follow_non_stop)
+    fprintf_filtered (file,
+		      _("Always inserted breakpoint mode is %s (currently %s).\n"),
+		      value, non_stop ? "on" : "off");
+  else
+    fprintf_filtered (file, _("Always inserted breakpoint mode is %s.\n"), value);
 }
 
+int
+breakpoints_always_inserted_mode (void)
+{
+  return (always_inserted_mode == always_inserted_on
+	  || (always_inserted_mode == always_inserted_follow_non_stop
+	      && non_stop));
+}
 
 void _initialize_breakpoint (void);
 
@@ -8197,11 +8220,6 @@ single_step_breakpoint_inserted_here_p (
   return 0;
 }
 
-int breakpoints_always_inserted_mode (void)
-{
-  return always_inserted_mode;
-}
-
 
 /* This help string is used for the break, hbreak, tbreak and thbreak commands.
    It is defined as a macro to prevent duplication.
@@ -8604,14 +8622,19 @@ a warning will be emitted for such break
 			   &breakpoint_set_cmdlist,
 			   &breakpoint_show_cmdlist);
 
-  add_setshow_boolean_cmd ("always-inserted", class_support,
-			   &always_inserted_mode, _("\
+  add_setshow_enum_cmd ("always-inserted", class_support,
+			always_inserted_enums, &always_inserted_mode, _("\
 Set mode for inserting breakpoints."), _("\
 Show mode for inserting breakpoints."), _("\
-When this mode is off (which is the default), breakpoints are inserted in\n\
-inferior when it is resumed, and removed when execution stops.  When this\n\
-mode is on, breakpoints are inserted immediately and removed only when\n\
-the user deletes the breakpoint."),
+When this mode is off, breakpoints are inserted in inferior when it is\n\
+resumed, and removed when execution stops.  When this mode is on,\n\
+breakpoints are inserted immediately and removed only when the user\n\
+deletes the breakpoint.  When this mode is follow-non-stop\n\
+(which is the default), the behaviour depends on the non-stop\n\
+setting (see help set non-stop).  In this case, if gdb is controlling\n\
+the inferior in non-stop mode, gdb behaves as if always-inserted mode\n\
+is on; if gdb is controlling the inferior in all-stop mode, gdb behaves\n\
+as if always-inserted mode is off."),
 			   NULL,
 			   &show_always_inserted_mode,
 			   &breakpoint_set_cmdlist,
Index: src/gdb/doc/gdb.texinfo
===================================================================
--- src.orig/gdb/doc/gdb.texinfo	2008-08-11 23:56:19.000000000 +0100
+++ src/gdb/doc/gdb.texinfo	2008-08-12 00:30:55.000000000 +0100
@@ -3321,8 +3321,14 @@ This behavior can be controlled with the
 @kindex set breakpoint always-inserted
 @kindex show breakpoint always-inserted
 @table @code
+@item set breakpoint always-inserted follow-non-stop
+This is the default mode.  If gdb is controlling the inferior in
+non-stop mode (@pxref{Non-Stop Mode}), gdb behaves as if
+always-inserted mode is on.  If gdb is controlling the inferior in
+all-stop mode, gdb behaves as if always-inserted mode is off.
+
 @item set breakpoint always-inserted off
-This is the default behaviour.  All breakpoints, including newly added
+All breakpoints, including newly added
 by the user, are inserted in the target only when the target is
 resumed.  All breakpoints are removed from the target when it stops.