* breakpoint.h (bp_location_p): New typedef.

	Register a vector of bp_location_p.
	* breakpoint.c (always_inserted_mode)
	(show_always_inserted_mode): New.
	(unlink_locations_from_global_list): Remove.
	(update_global_location_list)
	(update_global_location_list_nothrow): New.
	(update_watchpoint): Don't free locations.
	(should_insert_location): New.
	(insert_bp_location): Use should_insert_location.
	(insert_breakpoint_locations): Copied from
	insert_breakpoints.
	(insert_breakpoint): Use insert_breakpoint_locations.
	(bpstat_stop_status): Call update_global_location_list
	when disabling breakpoint.
	(allocate_bp_location): Don't add to bp_location_chain.
	(set_raw_breakpoint)
	(create_longjmp_breakpoint, enable_longjmp_breakpoint)
	(disable_longjmp_breakpoint, create_overlay_event_breakpoint)
	(enable_overlay_breakpoints, disable_overlay_breakpoints)
	(set_longjmp_resume_breakpoint)
	(enable_watchpoints_after_interactive_call_stop)
	(disable_watchpoints_before_interactive_call_start)
	(create_internal_breakpoint)
	(create_fork_vfork_event_catchpoint)
	(create_exec_event_catchpoint, set_momentary_breakpoint)
	(create_breakpoints, break_command_1, watch_command_1)
	(create_exception_catchpoint)
	(handle_gnu_v3_exceptions)
	(disable_breakpoint, breakpoint_re_set_one)
	(create_thread_event_breakpoint, create_solib_event_breakpoint)
	(create_ada_exception_breakpoint): : Don't call check_duplicates.
	Call update_global_location_list.
	(delete_breakpoint): Don't remove locations and don't
	try to reinsert them. Call update_global_location_list.
	(update_breakpoint_locations): Likewise.
	(restore_always_inserted_mode): New.
	(update_breakpoints_after_exec): Temporary disable
	always inserted mode.
	* Makefile.in: Update dependencies.

	* infrun.c (proceed): Remove breakpoints while stepping
	over breakpoint.
	(handle_inferior_event): Don't remove or insert
	breakpoints.
	* linux-fork.c (checkpoint_command): Remove breakpoints
	before fork and insert after.
	(linux_fork_context): Remove breakpoints before switch
	and insert after.
	* target.c (target_disconnect, target_detach): Remove
	breakpoints from target.

13 files changed, 474 insertions, 211 deletions

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index f9742dcf7db..806173c9189 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,60 @@
 2008-04-24  Vladimir Prus  <vladimir@codesourcery.com>
 
+	* breakpoint.h (bp_location_p): New typedef.
+	Register a vector of bp_location_p.
+	* breakpoint.c (always_inserted_mode)
+	(show_always_inserted_mode): New.
+	(unlink_locations_from_global_list): Remove.
+	(update_global_location_list)
+	(update_global_location_list_nothrow): New.
+	(update_watchpoint): Don't free locations.
+	(should_insert_location): New.
+	(insert_bp_location): Use should_insert_location.
+	(insert_breakpoint_locations): Copied from
+	insert_breakpoints.
+	(insert_breakpoint): Use insert_breakpoint_locations.
+	(bpstat_stop_status): Call update_global_location_list
+	when disabling breakpoint.
+	(allocate_bp_location): Don't add to bp_location_chain.
+	(set_raw_breakpoint)
+	(create_longjmp_breakpoint, enable_longjmp_breakpoint)
+	(disable_longjmp_breakpoint, create_overlay_event_breakpoint)
+	(enable_overlay_breakpoints, disable_overlay_breakpoints)
+	(set_longjmp_resume_breakpoint)
+	(enable_watchpoints_after_interactive_call_stop)
+	(disable_watchpoints_before_interactive_call_start)
+	(create_internal_breakpoint)
+	(create_fork_vfork_event_catchpoint)
+	(create_exec_event_catchpoint, set_momentary_breakpoint)
+	(create_breakpoints, break_command_1, watch_command_1)
+	(create_exception_catchpoint)
+	(handle_gnu_v3_exceptions)
+	(disable_breakpoint, breakpoint_re_set_one)
+	(create_thread_event_breakpoint, create_solib_event_breakpoint)
+	(create_ada_exception_breakpoint): : Don't call check_duplicates.
+	Call update_global_location_list.
+	(delete_breakpoint): Don't remove locations and don't
+	try to reinsert them. Call update_global_location_list.
+	(update_breakpoint_locations): Likewise.
+	(restore_always_inserted_mode): New.
+	(update_breakpoints_after_exec): Temporary disable
+	always inserted mode.
+	* Makefile.in: Update dependencies.
+
+	* infrun.c (proceed): Remove breakpoints while stepping
+	over breakpoint.
+	(handle_inferior_event): Don't remove or insert
+	breakpoints.
+	* linux-fork.c (checkpoint_command): Remove breakpoints
+	before fork and insert after.
+	(linux_fork_context): Remove breakpoints before switch
+	and insert after.
+	* target.c (target_disconnect, target_detach): Remove
+	breakpoints from target.
+
+	
+2008-04-24  Vladimir Prus  <vladimir@codesourcery.com>
+
 	* breakpoint.c (print_one_breakpoint_location): In MI
 	mode, report the location string the breakpoint was
 	originally created with.
diff --git a/gdb/Makefile.in b/gdb/Makefile.in
index ba5f6aca907..9304bc2f586 100644
--- a/gdb/Makefile.in
+++ b/gdb/Makefile.in
@@ -1974,7 +1974,8 @@ breakpoint.o: breakpoint.c $(defs_h) $(symtab_h) $(frame_h) $(breakpoint_h) \
 	$(objfiles_h) $(source_h) $(linespec_h) $(completer_h) $(gdb_h) \
 	$(ui_out_h) $(cli_script_h) $(gdb_assert_h) $(block_h) $(solib_h) \
 	$(solist_h) $(observer_h) $(exceptions_h) $(gdb_events_h) \
-	$(mi_common_h) $(memattr_h) $(ada_lang_h) $(top_h) $(hashtab_h)
+	$(mi_common_h) $(memattr_h) $(ada_lang_h) $(top_h) $(hashtab_h) \
+	$(gdb_stdint_h)
 bsd-kvm.o: bsd-kvm.c $(defs_h) $(cli_cmds_h) $(command_h) $(frame_h) \
 	$(regcache_h) $(target_h) $(value_h) $(gdbcore_h) $(gdb_assert_h) \
 	$(readline_h) $(bsd_kvm_h)
diff --git a/gdb/NEWS b/gdb/NEWS
index 2af9883954d..fcda6d1646a 100644
--- a/gdb/NEWS
+++ b/gdb/NEWS
@@ -43,6 +43,12 @@ show multiple-symbols
   when an expression or a breakpoint location contains an ambiguous symbol
   name (an overloaded function name, for instance).
   
+set breakpoint always-inserted
+show breakpoint always-inserted
+  Keep breakpoints always inserted in the target, as opposed to inserting
+  them when resuming the target, and removing them when the target stops.
+  This option can improve debugger performance on slow remote targets.
+
 *** Changes in GDB 6.8
 
 * New native configurations
diff --git a/gdb/breakpoint.c b/gdb/breakpoint.c
index 1ba957080e7..84802efffff 100644
--- a/gdb/breakpoint.c
+++ b/gdb/breakpoint.c
@@ -60,6 +60,8 @@
 #include "gdb-events.h"
 #include "mi/mi-common.h"
 
+#include "gdb_stdint.h"
+
 /* Prototypes for local functions. */
 
 static void until_break_command_continuation (struct continuation_arg *arg);
@@ -205,11 +207,13 @@ static void mark_breakpoints_out (void);
 static struct bp_location *
 allocate_bp_location (struct breakpoint *bpt, enum bptype bp_type);
 
-static void
-unlink_locations_from_global_list (struct breakpoint *bpt);
+static void update_global_location_list (void);
 
-static int
-is_hardware_watchpoint (struct breakpoint *bpt);
+static void update_global_location_list_nothrow (void);
+
+static int is_hardware_watchpoint (struct breakpoint *bpt);
+
+static void insert_breakpoint_locations (void);
 
 static const char *
 bpdisp_text (enum bpdisp disp)
@@ -265,6 +269,18 @@ Automatic usage of hardware breakpoints is %s.\n"),
 		    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 
+show_always_inserted_mode (struct ui_file *file, int from_tty,
+			   struct cmd_list_element *c, const char *value)
+{
+  fprintf_filtered (file, _("Always inserted breakpoint mode is %s.\n"), value);
+}
+
 
 void _initialize_breakpoint (void);
 
@@ -875,14 +891,10 @@ update_watchpoint (struct breakpoint *b, int reparse)
   struct bp_location *loc;
   bpstat bs;
 
-  unlink_locations_from_global_list (b);
-  for (loc = b->loc; loc;)
-    {
-      struct bp_location *loc_next = loc->next;
-      remove_breakpoint (loc, mark_uninserted);
-      xfree (loc);
-      loc = loc_next;
-    }
+  /* We don't free locations.  They are stored in
+     bp_location_chain and update_global_locations will
+     eventually delete them and remove breakpoints if
+     needed.  */
   b->loc = NULL;
 
   if (b->disposition == disp_del_at_next_stop)
@@ -1020,6 +1032,23 @@ in which its expression is valid.\n"),
 }
 
 
+/* Returns 1 iff breakpoint location should be
+   inserted in the inferior.  */
+static int
+should_be_inserted (struct bp_location *bpt)
+{
+  if (!breakpoint_enabled (bpt->owner))
+    return 0;
+
+  if (bpt->owner->disposition == disp_del_at_next_stop)
+    return 0;
+
+  if (!bpt->enabled || bpt->shlib_disabled || bpt->duplicate)
+    return 0;
+
+  return 1;
+}
+
 /* Insert a low-level "breakpoint" of some type.  BPT is the breakpoint.
    Any error messages are printed to TMP_ERROR_STREAM; and DISABLED_BREAKS,
    PROCESS_WARNING, and HW_BREAKPOINT_ERROR are used to report problems.
@@ -1034,10 +1063,7 @@ insert_bp_location (struct bp_location *bpt,
 {
   int val = 0;
 
-  if (!breakpoint_enabled (bpt->owner))
-    return 0;
-
-  if (!bpt->enabled || bpt->shlib_disabled || bpt->inserted || bpt->duplicate)
+  if (!should_be_inserted (bpt) || bpt->inserted)
     return 0;
 
   /* Initialize the target-specific information.  */
@@ -1238,13 +1264,35 @@ Note: automatically using hardware breakpoints for read-only addresses.\n"));
   return 0;
 }
 
+/* Make sure all breakpoints are inserted in inferior.
+   Throws exception on any error.
+   A breakpoint that is already inserted won't be inserted
+   again, so calling this function twice is safe.  */
+void
+insert_breakpoints (void)
+{
+  struct breakpoint *bpt;
+
+  ALL_BREAKPOINTS (bpt)
+    if (is_hardware_watchpoint (bpt))
+      update_watchpoint (bpt, 0 /* don't reparse. */);
+
+  update_global_location_list ();
+
+  if (!always_inserted_mode && target_has_execution)
+    /* update_global_location_list does not insert breakpoints
+       when always_inserted_mode is not enabled.  Explicitly
+       insert them now.  */
+    insert_breakpoint_locations ();
+}
+
 /* insert_breakpoints is used when starting or continuing the program.
    remove_breakpoints is used when the program stops.
    Both return zero if successful,
    or an `errno' value if could not write the inferior.  */
 
-void
-insert_breakpoints (void)
+static void
+insert_breakpoint_locations (void)
 {
   struct breakpoint *bpt;
   struct bp_location *b, *temp;
@@ -1256,18 +1304,14 @@ insert_breakpoints (void)
 
   struct ui_file *tmp_error_stream = mem_fileopen ();
   make_cleanup_ui_file_delete (tmp_error_stream);
-
+  
   /* Explicitly mark the warning -- this will only be printed if
      there was an error.  */
   fprintf_unfiltered (tmp_error_stream, "Warning:\n");
-
-  ALL_BREAKPOINTS (bpt)
-    if (is_hardware_watchpoint (bpt))
-      update_watchpoint (bpt, 0 /* don't reparse */);      
 	
   ALL_BP_LOCATIONS_SAFE (b, temp)
     {
-      if (!breakpoint_enabled (b->owner))
+      if (!should_be_inserted (b) || b->inserted)
 	continue;
 
       /* There is no point inserting thread-specific breakpoints if the
@@ -1295,6 +1339,9 @@ insert_breakpoints (void)
 
       if (bpt->enable_state != bp_enabled)
 	continue;
+
+      if (bpt->disposition == disp_del_at_next_stop)
+	continue;
       
       for (loc = bpt->loc; loc; loc = loc->next)
 	if (!loc->inserted)
@@ -1402,17 +1449,31 @@ reattach_breakpoints (int pid)
   return 0;
 }
 
+static void
+restore_always_inserted_mode (void *p)
+{
+  always_inserted_mode = (uintptr_t) p;
+}
+
 void
 update_breakpoints_after_exec (void)
 {
   struct breakpoint *b;
   struct breakpoint *temp;
+  struct cleanup *cleanup;
 
   /* Doing this first prevents the badness of having delete_breakpoint()
      write a breakpoint's current "shadow contents" to lift the bp.  That
      shadow is NOT valid after an exec()! */
   mark_breakpoints_out ();
 
+  /* The binary we used to debug is now gone, and we're updating
+     breakpoints for the new binary.  Until we're done, we should not
+     try to insert breakpoints.  */
+  cleanup = make_cleanup (restore_always_inserted_mode, 
+			  (void *) (uintptr_t) always_inserted_mode);
+  always_inserted_mode = 0;
+
   ALL_BREAKPOINTS_SAFE (b, temp)
   {
     /* Solib breakpoints must be explicitly reset after an exec(). */
@@ -1494,6 +1555,7 @@ update_breakpoints_after_exec (void)
   }
   /* FIXME what about longjmp breakpoints?  Re-create them here?  */
   create_overlay_event_breakpoint ("_ovly_debug_event");
+  do_cleanups (cleanup);
 }
 
 int
@@ -1533,9 +1595,9 @@ remove_breakpoint (struct bp_location *b, insertion_state_t is)
     /* Permanent breakpoints cannot be inserted or removed.  */
     return 0;
 
-  if (b->owner->type == bp_none)
-    warning (_("attempted to remove apparently deleted breakpoint #%d?"), 
-	     b->owner->number);
+  /* The type of none suggests that owner is actually deleted.
+     This should not ever happen.  */
+  gdb_assert (b->owner->type != bp_none);
 
   if (b->loc_type == bp_loc_software_breakpoint
       || b->loc_type == bp_loc_hardware_breakpoint)
@@ -2968,7 +3030,10 @@ bpstat_stop_status (CORE_ADDR bp_addr, ptid_t ptid)
 	  {
 	    /* We will stop here */
 	    if (b->disposition == disp_disable)
-	      b->enable_state = bp_disabled;
+	      {
+		b->enable_state = bp_disabled;
+		update_global_location_list ();
+	      }
 	    if (b->silent)
 	      bs->print = 0;
 	    bs->commands = b->commands;
@@ -4203,18 +4268,6 @@ allocate_bp_location (struct breakpoint *bpt, enum bptype bp_type)
       internal_error (__FILE__, __LINE__, _("unknown breakpoint type"));
     }
 
-  /* Add this breakpoint to the end of the chain.  */
-
-  loc_p = bp_location_chain;
-  if (loc_p == 0)
-    bp_location_chain = loc;
-  else
-    {
-      while (loc_p->global_next)
-	loc_p = loc_p->global_next;
-      loc_p->global_next = loc;
-    }
-
   return loc;
 }
 
@@ -4222,6 +4275,10 @@ static void free_bp_location (struct bp_location *loc)
 {
   if (loc->cond)
     xfree (loc->cond);
+
+  if (loc->function_name)
+    xfree (loc->function_name);
+  
   xfree (loc);
 }
 
@@ -4326,7 +4383,6 @@ set_raw_breakpoint (struct symtab_and_line sal, enum bptype bptype)
 
   set_breakpoint_location_function (b->loc);
 
-  check_duplicates (b);
   breakpoints_changed ();
 
   return b;
@@ -4390,6 +4446,7 @@ create_longjmp_breakpoint (char *func_name)
   b->silent = 1;
   if (func_name)
     b->addr_string = xstrdup (func_name);
+  update_global_location_list ();
 }
 
 /* Call this routine when stepping and nexting to enable a breakpoint
@@ -4405,7 +4462,7 @@ enable_longjmp_breakpoint (void)
     if (b->type == bp_longjmp)
     {
       b->enable_state = bp_enabled;
-      check_duplicates (b);
+      update_global_location_list ();
     }
 }
 
@@ -4419,7 +4476,7 @@ disable_longjmp_breakpoint (void)
 	|| b->type == bp_longjmp_resume)
     {
       b->enable_state = bp_disabled;
-      check_duplicates (b);
+      update_global_location_list ();
     }
 }
 
@@ -4446,6 +4503,7 @@ create_overlay_event_breakpoint (char *func_name)
       b->enable_state = bp_disabled;
       overlay_events_enabled = 0;
     }
+  update_global_location_list ();
 }
 
 void
@@ -4457,7 +4515,7 @@ enable_overlay_breakpoints (void)
     if (b->type == bp_overlay_event)
     {
       b->enable_state = bp_enabled;
-      check_duplicates (b);
+      update_global_location_list ();
       overlay_events_enabled = 1;
     }
 }
@@ -4471,7 +4529,7 @@ disable_overlay_breakpoints (void)
     if (b->type == bp_overlay_event)
     {
       b->enable_state = bp_disabled;
-      check_duplicates (b);
+      update_global_location_list ();
       overlay_events_enabled = 0;
     }
 }
@@ -4487,6 +4545,8 @@ create_thread_event_breakpoint (CORE_ADDR address)
   /* addr_string has to be used or breakpoint_re_set will delete me.  */
   b->addr_string = xstrprintf ("*0x%s", paddr (b->loc->address));
 
+  update_global_location_list_nothrow ();
+
   return b;
 }
 
@@ -4531,6 +4591,7 @@ create_solib_event_breakpoint (CORE_ADDR address)
   struct breakpoint *b;
 
   b = create_internal_breakpoint (address, bp_shlib_event);
+  update_global_location_list_nothrow ();
   return b;
 }
 
@@ -4628,6 +4689,8 @@ create_fork_vfork_event_catchpoint (int tempflag, char *cond_string,
   b->enable_state = bp_enabled;
   b->disposition = tempflag ? disp_del : disp_donttouch;
   b->forked_inferior_pid = 0;
+  update_global_location_list ();
+
 
   mention (b);
 }
@@ -4665,6 +4728,7 @@ create_exec_event_catchpoint (int tempflag, char *cond_string)
   b->addr_string = NULL;
   b->enable_state = bp_enabled;
   b->disposition = tempflag ? disp_del : disp_donttouch;
+  update_global_location_list ();
 
   mention (b);
 }
@@ -4725,7 +4789,7 @@ set_longjmp_resume_breakpoint (CORE_ADDR pc, struct frame_id frame_id)
                                                    b->type);
       b->enable_state = bp_enabled;
       b->frame_id = frame_id;
-      check_duplicates (b);
+      update_global_location_list ();
       return;
     }
 }
@@ -4744,7 +4808,7 @@ disable_watchpoints_before_interactive_call_start (void)
 	&& breakpoint_enabled (b))
       {
 	b->enable_state = bp_call_disabled;
-	check_duplicates (b);
+	update_global_location_list ();
       }
   }
 }
@@ -4763,7 +4827,7 @@ enable_watchpoints_after_interactive_call_stop (void)
 	&& (b->enable_state == bp_call_disabled))
       {
 	b->enable_state = bp_enabled;
-	check_duplicates (b);
+	update_global_location_list ();
       }
   }
 }
@@ -4789,6 +4853,8 @@ set_momentary_breakpoint (struct symtab_and_line sal, struct frame_id frame_id,
   if (in_thread_list (inferior_ptid))
     b->thread = pid_to_thread_id (inferior_ptid);
 
+  update_global_location_list_nothrow ();
+
   return b;
 }
 
@@ -5192,6 +5258,8 @@ create_breakpoints (struct symtabs_and_lines sals, char **addr_string,
 			 cond_string, type, disposition,
 			 thread, ignore_count, from_tty);
     }
+
+  update_global_location_list ();
 }
 
 /* Parse ARG which is assumed to be a SAL specification possibly
@@ -5509,6 +5577,8 @@ break_command_really (char *arg, char *cond_string, int thread,
       b->ignore_count = ignore_count;
       b->disposition = tempflag ? disp_del : disp_donttouch;
       b->condition_not_parsed = 1;
+
+      update_global_location_list ();
       mention (b);
     }
   
@@ -5935,6 +6005,7 @@ watch_command_1 (char *arg, int accessflag, int from_tty)
 
   value_free_to_mark (mark);
   mention (b);
+  update_global_location_list ();
 }
 
 /* Return count of locations need to be watched and can be handled
@@ -6493,6 +6564,7 @@ handle_gnu_v3_exceptions (int tempflag, char *cond_string,
 
   xfree (sals.sals);
   mention (b);
+  update_global_location_list ();
   return 1;
 }
 
@@ -6565,6 +6637,7 @@ create_ada_exception_breakpoint (struct symtab_and_line sal,
   b->ops = ops;
 
   mention (b);
+  update_global_location_list ();
 }
 
 /* Implement the "catch exception" command.  */
@@ -6886,33 +6959,124 @@ breakpoint_auto_delete (bpstat bs)
   }
 }
 
-/* Remove locations of breakpoint BPT from
-   the global list of breakpoint locations.  */
-
 static void
-unlink_locations_from_global_list (struct breakpoint *bpt)
+update_global_location_list (void)
 {
-  /* This code assumes that the locations
-     of a breakpoint are found in the global list
-     in the same order,  but not necessary adjacent.  */
-  struct bp_location **tmp = &bp_location_chain;
-  struct bp_location *here = bpt->loc;
-
-  if (here == NULL)
-    return;
+  struct breakpoint *b;
+  struct bp_location **next = &bp_location_chain;
+  struct bp_location *loc;
+  struct bp_location *loc2;
+  struct gdb_exception e;
+  VEC(bp_location_p) *old_locations = NULL;
+  int ret;
+  int ix;
+  
+  /* Store old locations for future reference.  */
+  for (loc = bp_location_chain; loc; loc = loc->global_next)
+    VEC_safe_push (bp_location_p, old_locations, loc);
 
-  for (; *tmp && here;)
+  bp_location_chain = NULL;
+  ALL_BREAKPOINTS (b)
     {
-      if (*tmp == here)
+      for (loc = b->loc; loc; loc = loc->next)
 	{
-	  *tmp = here->global_next;
-	  here = here->next;
+	  *next = loc;
+	  next = &(loc->global_next);
+	  *next = NULL;
 	}
-      else
+    }
+
+  /* Identify bp_location instances that are no longer present in the new
+     list, and therefore should be freed.  Note that it's not necessary that
+     those locations should be removed from inferior -- if there's another
+     location at the same address (previously marked as duplicate),
+     we don't need to remove/insert the location.  */
+  for (ix = 0; VEC_iterate(bp_location_p, old_locations, ix, loc); ++ix)
+    {
+      /* Tells if 'loc' is found amoung the new locations.  If not, we
+	 have to free it.  */
+      int found_object = 0;
+      for (loc2 = bp_location_chain; loc2; loc2 = loc2->global_next)
+	if (loc2 == loc)
+	  {
+	    found_object = 1;
+	    break;
+	  }
+
+      /* If this location is no longer present, and inserted, look if there's
+	 maybe a new location at the same address.  If so, mark that one 
+	 inserted, and don't remove this one.  This is needed so that we 
+	 don't have a time window where a breakpoint at certain location is not
+	 inserted.  */
+
+      if (loc->inserted)
 	{
-	  tmp = &((*tmp)->global_next);
+	  /* If the location is inserted now, we might have to remove it.  */
+	  int keep = 0;
+
+	  if (found_object && should_be_inserted (loc))
+	    {
+	      /* The location is still present in the location list, and still
+		 should be inserted.  Don't do anything.  */
+	      keep = 1;
+	    }
+	  else
+	    {
+	      /* The location is either no longer present, or got disabled.
+		 See if there's another location at the same address, in which 
+		 case we don't need to remove this one from the target.  */
+	      if (breakpoint_address_is_meaningful (loc->owner))
+		for (loc2 = bp_location_chain; loc2; loc2 = loc2->global_next)
+		  {
+		    /* For the sake of should_insert_location.  The
+		       call to check_duplicates will fix up this later.  */
+		    loc2->duplicate = 0;
+		    if (should_be_inserted (loc2)
+			&& loc2 != loc && loc2->address == loc->address)
+		      {		  
+			loc2->inserted = 1;
+			loc2->target_info = loc->target_info;
+			keep = 1;
+			break;
+		      }
+		  }
+	    }
+
+	  if (!keep)
+	    if (remove_breakpoint (loc, mark_uninserted))
+	      {
+		/* This is just about all we can do.  We could keep this
+		   location on the global list, and try to remove it next
+		   time, but there's no particular reason why we will
+		   succeed next time.  
+
+		   Note that at this point, loc->owner is still valid,
+		   as delete_breakpoint frees the breakpoint only
+		   after calling us.  */
+		printf_filtered (_("warning: Error removing breakpoint %d\n"), 
+				 loc->owner->number);
+	      }
 	}
+
+      if (!found_object)
+	free_bp_location (loc);
+    }
+    
+  ALL_BREAKPOINTS (b)
+    {
+      check_duplicates (b);
     }
+
+  if (always_inserted_mode && target_has_execution)
+    insert_breakpoint_locations ();
+}
+
+static void
+update_global_location_list_nothrow (void)
+{
+  struct gdb_exception e;
+  TRY_CATCH (e, RETURN_MASK_ERROR)
+    update_global_location_list ();
 }
 
 /* Delete a breakpoint and clean up all traces of it in the data
@@ -6923,7 +7087,7 @@ delete_breakpoint (struct breakpoint *bpt)
 {
   struct breakpoint *b;
   bpstat bs;
-  struct bp_location *loc;
+  struct bp_location *loc, *next;
 
   gdb_assert (bpt != NULL);
 
@@ -6947,18 +7111,6 @@ delete_breakpoint (struct breakpoint *bpt)
     deprecated_delete_breakpoint_hook (bpt);
   breakpoint_delete_event (bpt->number);
 
-  for (loc = bpt->loc; loc; loc = loc->next)
-    {
-      if (loc->inserted)
-	remove_breakpoint (loc, mark_inserted);
-      
-      if (loc->cond)
-	xfree (loc->cond);
-
-      if (loc->function_name)
-	xfree (loc->function_name);
-    }
-
   if (breakpoint_chain == bpt)
     breakpoint_chain = bpt->next;
 
@@ -6969,85 +7121,6 @@ delete_breakpoint (struct breakpoint *bpt)
       break;
     }
 
-  unlink_locations_from_global_list (bpt);
-
-  check_duplicates (bpt);
-
-  if (bpt->type != bp_hardware_watchpoint
-      && bpt->type != bp_read_watchpoint
-      && bpt->type != bp_access_watchpoint
-      && bpt->type != bp_catch_fork
-      && bpt->type != bp_catch_vfork
-      && bpt->type != bp_catch_exec)
-    for (loc = bpt->loc; loc; loc = loc->next)
-      {
-	/* If this breakpoint location was inserted, and there is 
-	   another breakpoint at the same address, we need to 
-	   insert the other breakpoint.  */
-	if (loc->inserted)
-	  {
-	    struct bp_location *loc2;
-	    ALL_BP_LOCATIONS (loc2)
-	      if (loc2->address == loc->address
-		  && loc2->section == loc->section
-		  && !loc->duplicate
-		  && loc2->owner->enable_state != bp_disabled
-		  && loc2->enabled 
-		  && !loc2->shlib_disabled
-		  && loc2->owner->enable_state != bp_call_disabled)
-		{
-		  int val;
-
-		  /* We should never reach this point if there is a permanent
-		     breakpoint at the same address as the one being deleted.
-		     If there is a permanent breakpoint somewhere, it should
-		     always be the only one inserted.  */
-		  if (loc2->owner->enable_state == bp_permanent)
-		    internal_error (__FILE__, __LINE__,
-				    _("another breakpoint was inserted on top of "
-				      "a permanent breakpoint"));
-
-		  memset (&loc2->target_info, 0, sizeof (loc2->target_info));
-		  loc2->target_info.placed_address = loc2->address;
-		  if (b->type == bp_hardware_breakpoint)
-		    val = target_insert_hw_breakpoint (&loc2->target_info);
-		  else
-		    val = target_insert_breakpoint (&loc2->target_info);
-
-		  /* If there was an error in the insert, print a message, then stop execution.  */
-		  if (val != 0)
-		    {
-		      struct ui_file *tmp_error_stream = mem_fileopen ();
-		      make_cleanup_ui_file_delete (tmp_error_stream);
-		      
-		      
-		      if (b->type == bp_hardware_breakpoint)
-			{
-			  fprintf_unfiltered (tmp_error_stream, 
-					      "Cannot insert hardware breakpoint %d.\n"
-					      "You may have requested too many hardware breakpoints.\n",
-					      b->number);
-			}
-		      else
-			{
-			  fprintf_unfiltered (tmp_error_stream, "Cannot insert breakpoint %d.\n", b->number);
-			  fprintf_filtered (tmp_error_stream, "Error accessing memory address ");
-			  fputs_filtered (paddress (loc2->address),
-					  tmp_error_stream);
-			  fprintf_filtered (tmp_error_stream, ": %s.\n",
-					    safe_strerror (val));
-			}
-		      
-		      fprintf_unfiltered (tmp_error_stream,"The same program may be running in another process.");
-		      target_terminal_ours_for_output ();
-		      error_stream(tmp_error_stream); 
-		    }
-		  else
-		    loc2->inserted = 1;
-		}
-	  }
-      }
-
   free_command_lines (&bpt->commands);
   if (bpt->cond_string != NULL)
     xfree (bpt->cond_string);
@@ -7084,16 +7157,22 @@ delete_breakpoint (struct breakpoint *bpt)
 	bs->old_val = NULL;
 	/* bs->commands will be freed later.  */
       }
+
+  /* Now that breakpoint is removed from breakpoint
+     list, update the global location list.  This
+     will remove locations that used to belong to
+     this breakpoint.  Do this before freeing
+     the breakpoint itself, since remove_breakpoint
+     looks at location's owner.  It might be better
+     design to have location completely self-contained,
+     but it's not the case now.  */
+  update_global_location_list ();
+
+
   /* On the chance that someone will soon try again to delete this same
      bp, we mark it as deleted before freeing its storage. */
   bpt->type = bp_none;
 
-  for (loc = bpt->loc; loc;)
-    {
-      struct bp_location *loc_next = loc->next;
-      xfree (loc);
-      loc = loc_next;
-    }
   xfree (bpt);
 }
 
@@ -7225,7 +7304,6 @@ update_breakpoint_locations (struct breakpoint *b,
   if (all_locations_are_pending (existing_locations) && sals.nelts == 0)
     return;
 
-  unlink_locations_from_global_list (b);
   b->loc = NULL;
 
   for (i = 0; i < sals.nelts; ++i)
@@ -7304,12 +7382,7 @@ update_breakpoint_locations (struct breakpoint *b,
       }
   }
 
-  while (existing_locations)
-    {
-      struct bp_location *next = existing_locations->next;
-      free_bp_location (existing_locations);
-      existing_locations = next;
-    }
+  update_global_location_list ();
 }
 
 
@@ -7405,10 +7478,6 @@ breakpoint_re_set_one (void *bint)
       expanded = expand_line_sal_maybe (sals.sals[0]);
       update_breakpoint_locations (b, expanded);
 
-      /* Now that this is re-enabled, check_duplicates
-	 can be used. */
-      check_duplicates (b);
-
       xfree (sals.sals);
       break;
 
@@ -7708,7 +7777,7 @@ disable_breakpoint (struct breakpoint *bpt)
 
   bpt->enable_state = bp_disabled;
 
-  check_duplicates (bpt);
+  update_global_location_list ();
 
   if (deprecated_modify_breakpoint_hook)
     deprecated_modify_breakpoint_hook (bpt);
@@ -7747,7 +7816,7 @@ disable_command (char *args, int from_tty)
       struct bp_location *loc = find_location_by_number (args);
       if (loc)
 	loc->enabled = 0;
-      check_duplicates (loc->owner);
+      update_global_location_list ();
     }
   else
     map_breakpoint_numbers (args, disable_breakpoint);
@@ -7832,7 +7901,7 @@ have been allocated for other watchpoints.\n"), bpt->number);
   if (bpt->enable_state != bp_permanent)
     bpt->enable_state = bp_enabled;
   bpt->disposition = disposition;
-  check_duplicates (bpt);
+  update_global_location_list ();
   breakpoints_changed ();
   
   if (deprecated_modify_breakpoint_hook)
@@ -7883,7 +7952,7 @@ enable_command (char *args, int from_tty)
       struct bp_location *loc = find_location_by_number (args);
       if (loc)
 	loc->enabled = 1;
-      check_duplicates (loc->owner);
+      update_global_location_list ();
     }
   else
     map_breakpoint_numbers (args, enable_breakpoint);
@@ -8051,6 +8120,11 @@ single_step_breakpoint_inserted_here_p (CORE_ADDR pc)
   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.
@@ -8452,6 +8526,19 @@ a warning will be emitted for such breakpoints."),
 			   show_automatic_hardware_breakpoints,
 			   &breakpoint_set_cmdlist,
 			   &breakpoint_show_cmdlist);
+
+  add_setshow_boolean_cmd ("always-inserted", class_support,
+			   &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."),
+			   NULL,
+			   &show_always_inserted_mode,
+			   &breakpoint_set_cmdlist,
+			   &breakpoint_show_cmdlist);
   
   automatic_hardware_breakpoints = 1;
 }
diff --git a/gdb/breakpoint.h b/gdb/breakpoint.h
index 537645570e4..ed76f30d0ff 100644
--- a/gdb/breakpoint.h
+++ b/gdb/breakpoint.h
@@ -331,6 +331,9 @@ enum watchpoint_triggered
   watch_triggered_yes  
 };
 
+typedef struct bp_location *bp_location_p;
+DEF_VEC_P(bp_location_p);
+
 /* Note that the ->silent field is not currently used by any commands
    (though the code is in there if it was to be, and set_raw_breakpoint
    does set it to 0).  I implemented it because I thought it would be
@@ -864,4 +867,6 @@ int watchpoints_triggered (struct target_waitstatus *);
 void breakpoint_restore_shadows (gdb_byte *buf, ULONGEST memaddr, 
 				 LONGEST len);
 
+extern int breakpoints_always_inserted_mode (void);
+
 #endif /* !defined (BREAKPOINT_H) */
diff --git a/gdb/doc/gdb.texinfo b/gdb/doc/gdb.texinfo
index 633779049c6..e422d44b53c 100644
--- a/gdb/doc/gdb.texinfo
+++ b/gdb/doc/gdb.texinfo
@@ -3209,6 +3209,30 @@ type.  If the target provides a memory map, @value{GDBN} will warn when
 trying to set software breakpoint at a read-only address.
 @end table
 
+@value{GDBN} normally implements breakpoints by replacing the program code
+at the breakpoint address with a special instruction, which, when
+executed, given control to the debugger.  By default, the program
+code is so modified only when the program is resumed.  As soon as
+the program stops, @value{GDBN} restores the original instructions.  This
+behaviour guards against leaving breakpoints inserted in the
+target should gdb abrubptly disconnect.  However, with slow remote
+targets, inserting and removing breakpoint can reduce the performance.
+This behavior can be controlled with the following commands::
+
+@kindex set breakpoint always-inserted
+@kindex show breakpoint always-inserted
+@table @code
+@item set breakpoint always-inserted off
+This is the default behaviour.  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.
+
+@item set breakpoint always-inserted on
+Causes all breakpoints to be inserted in the target at all times.  If
+the user adds a new breakpoint, or changes an existing breakpoint, the
+breakpoints in the target are updated immediately.  A breakpoint is
+removed from the target only when breakpoint itself is removed.
+@end table
 
 @cindex negative breakpoint numbers
 @cindex internal @value{GDBN} breakpoints
diff --git a/gdb/infrun.c b/gdb/infrun.c
index df042a1e2c1..da8c3e028eb 100644
--- a/gdb/infrun.c
+++ b/gdb/infrun.c
@@ -614,19 +614,18 @@ a command like `return' or `jump' to continue execution."));
 	}
 
       if ((step || singlestep_breakpoints_inserted_p)
-	  && breakpoint_here_p (read_pc ())
-	  && !breakpoint_inserted_here_p (read_pc ()))
+	  && stepping_over_breakpoint)
 	{
-	  /* We're stepping, have breakpoint at PC, and it's 
-	     not inserted.  Most likely, proceed has noticed that
-	     we have breakpoint and tries to single-step over it,
-	     so that it's not hit.  In which case, we need to
-	     single-step only this thread, and keep others stopped,
-	     as they can miss this breakpoint if allowed to run.  
-
-	     The current code either has all breakpoints inserted, 
-	     or all removed, so if we let other threads run,
-	     we can actually miss any breakpoint, not the one at PC.  */
+	  /* We're allowing a thread to run past a breakpoint it has
+	     hit, by single-stepping the thread with the breakpoint
+	     removed.  In which case, we need to single-step only this
+	     thread, and keep others stopped, as they can miss this
+	     breakpoint if allowed to run.
+
+	     The current code actually removes all breakpoints when
+	     doing this, not just the one being stepped over, so if we
+	     let other threads run, we can actually miss any
+	     breakpoint, not just the one at PC.  */
 	  resume_ptid = inferior_ptid;
 	}
 
@@ -787,9 +786,17 @@ proceed (CORE_ADDR addr, enum target_signal siggnal, int step)
     oneproc = 1;
 
   if (oneproc)
-    /* We will get a trace trap after one instruction.
-       Continue it automatically and insert breakpoints then.  */
-    stepping_over_breakpoint = 1;
+    {
+      /* We will get a trace trap after one instruction.
+	 Continue it automatically and insert breakpoints then.  */
+      stepping_over_breakpoint = 1;
+      /* FIXME: if breakpoints are always inserted, we'll trap
+       if trying to single-step over breakpoint.  Disable
+      all breakpoints.  In future, we'd need to invent some
+      smart way of stepping over breakpoint instruction without
+      hitting breakpoint.  */
+      remove_breakpoints ();
+    }
   else
     insert_breakpoints ();
 
@@ -1348,10 +1355,6 @@ handle_inferior_event (struct execution_control_state *ecs)
          established.  */
       if (stop_soon == NO_STOP_QUIETLY)
 	{
-	  /* Remove breakpoints, SOLIB_ADD might adjust
-	     breakpoint addresses via breakpoint_re_set.  */
-	  remove_breakpoints ();
-
 	  /* Check for any newly added shared libraries if we're
 	     supposed to be adding them automatically.  Switch
 	     terminal for any messages produced by
@@ -1391,9 +1394,6 @@ handle_inferior_event (struct execution_control_state *ecs)
 
 	  /* NOTE drow/2007-05-11: This might be a good place to check
 	     for "catch load".  */
-
-	  /* Reinsert breakpoints and continue.  */
-	  insert_breakpoints ();
 	}
 
       /* If we are skipping through a shell, or through shared library
@@ -1402,6 +1402,10 @@ handle_inferior_event (struct execution_control_state *ecs)
 	 we're attaching or setting up a remote connection.  */
       if (stop_soon == STOP_QUIETLY || stop_soon == NO_STOP_QUIETLY)
 	{
+	  /* Loading of shared libraries might have changed breakpoint
+	     addresses.  Make sure new breakpoints are inserted.  */
+	  if (!breakpoints_always_inserted_mode ())
+	    insert_breakpoints ();
 	  resume (0, TARGET_SIGNAL_0);
 	  prepare_to_wait (ecs);
 	  return;
@@ -2039,8 +2043,7 @@ process_event_stop_test:
 	stop_signal = TARGET_SIGNAL_0;
 
       if (prev_pc == read_pc ()
-	  && breakpoint_here_p (read_pc ())
-	  && !breakpoint_inserted_here_p (read_pc ())
+	  && stepping_over_breakpoint
 	  && step_resume_breakpoint == NULL)
 	{
 	  /* We were just starting a new sequence, attempting to
@@ -2216,10 +2219,6 @@ process_event_stop_test:
 	{
           if (debug_infrun)
 	    fprintf_unfiltered (gdb_stdlog, "infrun: BPSTAT_WHAT_CHECK_SHLIBS\n");
-	  /* Remove breakpoints, we eventually want to step over the
-	     shlib event breakpoint, and SOLIB_ADD might adjust
-	     breakpoint addresses via breakpoint_re_set.  */
-	  remove_breakpoints ();
 
 	  /* Check for any newly added shared libraries if we're
 	     supposed to be adding them automatically.  Switch
@@ -3120,7 +3119,7 @@ normal_stop (void)
        gdbarch_decr_pc_after_break needs to just go away.  */
     deprecated_update_frame_pc_hack (get_current_frame (), read_pc ());
 
-  if (target_has_execution)
+  if (!breakpoints_always_inserted_mode () && target_has_execution)
     {
       if (remove_breakpoints ())
 	{
diff --git a/gdb/linux-fork.c b/gdb/linux-fork.c
index 8c298273cf1..a9f5faecfbe 100644
--- a/gdb/linux-fork.c
+++ b/gdb/linux-fork.c
@@ -536,6 +536,10 @@ checkpoint_command (char *args, int from_tty)
   /* Make this temp var static, 'cause it's used in the error context.  */
   static int temp_detach_fork;
 
+  /* Remove breakpoints, so that they are not inserted
+     in the forked process.  */
+  remove_breakpoints ();
+
   /* Make the inferior fork, record its (and gdb's) state.  */
 
   if (lookup_minimal_symbol ("fork", NULL, NULL) != NULL)
@@ -576,6 +580,7 @@ checkpoint_command (char *args, int from_tty)
   if (!fp)
     error (_("Failed to find new fork"));
   fork_save_infrun_state (fp, 1);
+  insert_breakpoints ();
 }
 
 static void
@@ -593,7 +598,9 @@ linux_fork_context (struct fork_info *newfp, int from_tty)
     oldfp = add_fork (ptid_get_pid (inferior_ptid));
 
   fork_save_infrun_state (oldfp, 1);
+  remove_breakpoints ();
   fork_load_infrun_state (newfp);
+  insert_breakpoints ();
 
   printf_filtered (_("Switching to %s\n"), 
 		   target_pid_to_str (inferior_ptid));
diff --git a/gdb/target.c b/gdb/target.c
index 7f53944bacd..944d601659f 100644
--- a/gdb/target.c
+++ b/gdb/target.c
@@ -1676,6 +1676,10 @@ target_preopen (int from_tty)
 void
 target_detach (char *args, int from_tty)
 {
+  /* If we're in breakpoints-always-inserted mode, have to
+     remove them before detaching.  */
+  remove_breakpoints ();
+
   (current_target.to_detach) (args, from_tty);
 }
 
@@ -1684,6 +1688,10 @@ target_disconnect (char *args, int from_tty)
 {
   struct target_ops *t;
 
+  /* If we're in breakpoints-always-inserted mode, have to
+     remove them before disconnecting.  */  
+  remove_breakpoints ();
+
   for (t = current_target.beneath; t != NULL; t = t->beneath)
     if (t->to_disconnect != NULL)
 	{
diff --git a/gdb/testsuite/ChangeLog b/gdb/testsuite/ChangeLog
index 37855d52702..eb5023869ef 100644
--- a/gdb/testsuite/ChangeLog
+++ b/gdb/testsuite/ChangeLog
@@ -1,5 +1,12 @@
 2008-04-24  Vladimir Prus  <vladimir@codesourcery.com>
 
+	* lib/gdb.exp (gdb_continue_to_breakpoint): Allow the caller
+	to specify regexp for the location to stop at.
+	* gdb.base/break-always.c: New.
+	* gdb.base/break-always.exp: New.
+
+2008-04-24  Vladimir Prus  <vladimir@codesourcery.com>
+
 	* lib/mi-support.exp (mi_runto_helper): Adjust
 	for the original-location field.
 	(mi_create_breakpoint, mi_list_breakpoints): New.
diff --git a/gdb/testsuite/gdb.base/break-always.c b/gdb/testsuite/gdb.base/break-always.c
new file mode 100644
index 00000000000..6c5515def20
--- /dev/null
+++ b/gdb/testsuite/gdb.base/break-always.c
@@ -0,0 +1,32 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2008 Free Software Foundation, Inc.
+
+   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 3 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, see <http://www.gnu.org/licenses/>.  */
+
+int bar ()
+{
+  return 1; /* break in bar */
+}
+
+int foo ()
+{
+  return bar ();
+}
+
+int main ()
+{
+  foo ();
+  return 0;
+}
diff --git a/gdb/testsuite/gdb.base/break-always.exp b/gdb/testsuite/gdb.base/break-always.exp
new file mode 100644
index 00000000000..61619438c16
--- /dev/null
+++ b/gdb/testsuite/gdb.base/break-always.exp
@@ -0,0 +1,32 @@
+#   Copyright 2008 Free Software Foundation, Inc.
+
+# 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 3 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, see <http://www.gnu.org/licenses/>.
+
+# Test that 'set breakpoint always-inserted 1' is not a brick
+
+if { [prepare_for_testing break-always.exp break-always break-always.c] } {
+    return -1
+}
+
+set bar_location [gdb_get_line_number "break in bar" break-always.c]
+
+gdb_test "set breakpoint always-inserted 1" ""
+
+runto foo
+
+gdb_test "break bar" "Breakpoint 2.*" "set breakpoint on bar"
+gdb_continue_to_breakpoint "bar" ".*/break-always.c:$bar_location.*"
+
+
+
diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 8ad879289a2..bb9bd24f540 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -432,13 +432,13 @@ proc runto_main { } {
 ### worked.  Use NAME as part of the test name; each call to
 ### continue_to_breakpoint should use a NAME which is unique within
 ### that test file.
-proc gdb_continue_to_breakpoint {name} {
+proc gdb_continue_to_breakpoint {name {location_pattern .*}} {
     global gdb_prompt
     set full_name "continue to breakpoint: $name"
 
     send_gdb "continue\n"
     gdb_expect {
-	-re "Breakpoint .* at .*\r\n$gdb_prompt $" {
+	-re "Breakpoint .* at $location_pattern\r\n$gdb_prompt $" {
 	    pass $full_name
 	}
 	-re ".*$gdb_prompt $" {