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From: Vladimir Prus <ghost@cs.msu.su>
To: Eli Zaretskii <eliz@gnu.org>
Subject: Re: $thread convenience variable
Date: Fri, 03 Feb 2006 11:10:00 -0000
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On Friday 03 February 2006 13:58, Eli Zaretskii wrote:
> > From:  Vladimir Prus <ghost@cs.msu.su>
> > Date:  Mon, 30 Jan 2006 16:31:34 +0300
> >
> >    breakpoint foo.cpp:10 if $thread==1 || $thread==2
> >
> > If I understand correctly, at the moment gdb can't specify arbitrary
> > condition on thread number for breakpoint. A breakpoint is either global,
> > or for one thread.
> >
> > If such variable does not exist, does it look like a good addition?
>
> I'd support adding such a variable.

I have it working by this patch :

--- infrun.c    (revision 1696)
+++ infrun.c    (working copy)
@@ -1836,10 +1854,17 @@

       /* Don't even think about breakpoints if just proceeded over a
          breakpoint.  */
       if (stop_signal == TARGET_SIGNAL_TRAP && trap_expected)
        bpstat_clear (&stop_bpstat);
       else
        {
+
+      set_internalvar (lookup_internalvar ("thread"),
+                      value_from_longest (builtin_type_int,
+                                          (LONGEST) inferior_ptid.pid));
+

With it, the $thread variable will mean the last thread where we've stopped, 
as opposed to the current one -- that is, does not change after "thread XXX" 
command. This might be confusing to users, or might not.

Also, I'm not sure about "inferior_ptid.pid" above. For remote target (with 
multiple threads) 'pid' is the only field with reasonable value. The value of 
'tid' field is always zero. But for native target, I suppose 'pid' is the 
same for all threads in a program, but "inferior.tid" varies. I'm a bit lost 
on this one.


- Volodya