Re: [reverse/record] adjust_pc_after_break in reverse execution mode?

[teawater <teawater@gmail.com>]

Sorry I send too much Email. I found that:

      if (singlestep_breakpoints_inserted_p
	  || !ptid_equal (ecs->ptid, inferior_ptid)
	  || !currently_stepping (ecs->event_thread)
	  || ecs->event_thread->prev_pc == breakpoint_pc)
	regcache_write_pc (regcache, breakpoint_pc);

Before write_pc, there are a lot of thing to check. Do we  need to
check it in record_wait?
If so, it actually useless cause it will be set back in adjust_pc_after_break?
Maybe we can let adjust_pc_after_break disable in replay mode.

How do you think?




On Tue, Oct 21, 2008 at 08:21, Pedro Alves <pedro@codesourcery.com> wrote:
> On Tuesday 21 October 2008 00:36:12, teawater wrote:
>> I think your mean is check breakpoint in address
>> read_pc()+gdbarch_decr_pc_after_break (gdbarch) in record_wait, right?
>
> Taking x86 as an example, when you're doing normal debugging and you
> hit a breakpoint (SIGTRAP), the first read_pc GDB does to check where
> what breakpoint was hit, will read back `breakpoint_PC + 1' --- GDB takes care
> getting rid of that `+ 1' offset in infrun.c:adjust_pc_after_break.  The
> idea is for you to do the same as the kernel/hardware would --- still
> check for breakpoints at read_pc, but increment PC by 1 before reporting the
> breakpoint to GDB's core.  E.g., see the `pc += gdbarch...' line from
> the patch I posted previously, something like:
>
> record.c:record_wait ()
> {
> ...
> +         /* Check for breakpoint hits in forward execution.  */
> +         pc = read_pc ();
> +         if (execution_direction == EXEC_FORWARD
> +             && regular_breakpoint_inserted_here_p (pc)
> +             /* && !single-stepping */)
> +           {
> +             status->kind = TARGET_WAITKIND_STOPPED;
> +             status->value.sig = TARGET_SIGNAL_TRAP;
> +             if (software_breakpoint_inserted_here_p (pc))
> +               {
> +                 pc += gdbarch_decr_pc_after_break (gdbarch);
> +                 write_pc (pc);
> +               }
> +
>
> --
> Pedro Alves
>