tracepoint->step_count fixes

tracepoint->step_count fixes

If a tracepoint's actions list includes a while-stepping action, and
then the actions are changed to a list without any while-stepping
action, the tracepoint's step_count will be left with a stale value.
For example:

 (gdb) trace subr
 Tracepoint 1 at 0x4004d9: file ../../../src/gdb/testsuite//actions-changed.c, line 31.
 (gdb) actions
 Enter actions for tracepoint 1, one per line.
 End with a line saying just "end".
 >collect $reg
 >end
 (gdb) set debug remote 1
 (gdb) tstart
 Sending packet: $QTinit#59...Packet received: OK
 Sending packet: $QTDP:1:00000000004004d9:E:0:0-#a3...Packet received: OK
 Sending packet: $QTDP:-1:00000000004004d9:R03FFFFFFFFFFFFFFFFFF#2b...Packet received: OK
 (gdb) tstop
 Sending packet: $QTStop#4b...Packet received: OK
 Sending packet: $QTNotes:#e8...Packet received: OK
 (gdb) actions
 Enter actions for tracepoint 1, one per line.
 End with a line saying just "end".
 >collect $reg
 >while-stepping 1
   >collect $reg
   >end
 >end
 (gdb) tstart
 Sending packet: $QTinit#59...Packet received: OK
 Sending packet: $QTDP:1:00000000004004d9:E:1:0-#a4...Packet received: OK
 Sending packet: $QTDP:-1:00000000004004d9:R03FFFFFFFFFFFFFFFFFF-#58...Packet received: OK
 Sending packet: $QTDP:-1:00000000004004d9:SR03FFFFFFFFFFFFFFFFFF#7e...Packet received: OK
 (gdb) tstop
 Sending packet: $QTStop#4b...Packet received: OK
 Sending packet: $QTNotes:#e8...Packet received: OK
 (gdb) actions
 Enter actions for tracepoint 1, one per line.
 End with a line saying just "end".
 >collect $regs
 >end
 (gdb) tstart
 Sending packet: $QTinit#59...Packet received: OK
 Sending packet: $QTDP:1:00000000004004d9:E:1:0-#a4...Packet received: OK
 Sending packet: $QTDP:-1:00000000004004d9:R03FFFFFFFFFFFFFFFFFF#2b...Packet received: OK

The last "$QTDP:1:00000000004004d9:E:1:0-#a4" should be "$QTDP:1:00000000004004d9:E:0:0-#a3".
In pseudo-diff:

  -$QTDP:1:00000000004004d9:E:1:0-#a4
  +$QTDP:1:00000000004004d9:E:0:0-#a3

A related issue is that the "commands" command actually supports
setting commands to a range of breakpoints/tracepoints at once.  But,
hacking "maint info breakpoints" to print t->step_count, reveals:

 (gdb) trace main
 Tracepoint 5 at 0x45a2ab: file ../../src/gdb/gdb.c, line 29.
 (gdb) trace main
 Note: breakpoint 5 also set at pc 0x45a2ab.
 Tracepoint 6 at 0x45a2ab: file ../../src/gdb/gdb.c, line 29.
 (gdb) commands 5-6
 Type commands for breakpoint(s) 5-6, one per line.
 End with a line saying just "end".
 > while-stepping 5
  >end
 > end
 (gdb) maint info breakpoints 5
 Num     Type           Disp Enb Address            What
 5       tracepoint     keep y   0x000000000045a2ab in main at ../../src/gdb/gdb.c:29 inf 1
         step_count=5
         ^^^^^^^^^^^^
         while-stepping 5
         end
         not installed on target
 (gdb) maint info breakpoints 6
 Num     Type           Disp Enb Address            What
 6       tracepoint     keep y   0x000000000045a2ab in main at ../../src/gdb/gdb.c:29 inf 1
         step_count=0
         ^^^^^^^^^^^^
         while-stepping 5
         end
         not installed on target
 (gdb)

that tracepoint 6 doesn't end up with the correct step_count.

The issue is that here:

 static void
 do_map_commands_command (struct breakpoint *b, void *data)
 {
  struct commands_info *info = data;

  if (info->cmd == NULL)
    {
      struct command_line *l;

      if (info->control != NULL)
	l = copy_command_lines (info->control->body_list[0]);
      else
	{
	  struct cleanup *old_chain;
	  char *str;

	  str = xstrprintf (_("Type commands for breakpoint(s) "
			      "%s, one per line."),
			    info->arg);

	  old_chain = make_cleanup (xfree, str);

	  l = read_command_lines (str,
				  info->from_tty, 1,
				  (is_tracepoint (b)
				   ? check_tracepoint_command : 0),
				  b);

	  do_cleanups (old_chain);
	}

      info->cmd = alloc_counted_command_line (l);
    }

validate_actionline is never called for tracepoints other than the
first (the copy_command_lines path).  Right below, we have:

  /* If a breakpoint was on the list more than once, we don't need to
     do anything.  */
  if (b->commands != info->cmd)
    {
      validate_commands_for_breakpoint (b, info->cmd->commands);
      incref_counted_command_line (info->cmd);
      decref_counted_command_line (&b->commands);
      b->commands = info->cmd;
      observer_notify_breakpoint_modified (b);
    }

And validate_commands_for_breakpoint looks like the right place to put
a call; if we reset step_count there too, we have a nice central fix
for the first issue as well, because trace_actions_command calls
breakpoint_set_commands that also calls
validate_commands_for_breakpoint.

We end up calling validate_actionline twice for the first tracepoint,
since read_command_lines calls it too, through
check_tracepoint_command, but that should be harmless.

2013-04-04  Pedro Alves  <palves@redhat.com>
	    Hui Zhu  <hui@codesourcery.com>

	* breakpoint.c (validate_commands_for_breakpoint): If validating a
	tracepoint, reset its STEP_COUNT and call validate_actionline.

2013-04-04  Stan Shebs  <stan@codesourcery.com>
	    Pedro Alves  <palves@redhat.com>

	* gdb.trace/Makefile.in (PROGS): Add actions-changed.
	* gdb.trace/actions-changed.c: New file.
	* gdb.trace/actions-changed.exp: New file.
	* lib/trace-support.exp (gdb_trace_setactions): Rename to ...
	(gdb_trace_setactions_command): ... this.  Add "actions_command"
	parameter, and handle it.
	(gdb_trace_setactions, gdb_trace_setcommands): New procedures.