Re: PATCH: resume + threads + software stepping == boom

[Michael Snyder <msnyder at cygnus dot com>]

Michael Snyder wrote:
> 
> Daniel Jacobowitz wrote:
> >
> > resume () in infrun.c has this block:
> >
> >   if (SOFTWARE_SINGLE_STEP_P () && step)
> >     {
> >       /* Do it the hard way, w/temp breakpoints */
> >       SOFTWARE_SINGLE_STEP (sig, 1 /*insert-breakpoints */ );
> >       /* ...and don't ask hardware to do it.  */
> >       step = 0;
> >
> > Then, further down, if (use_thread_step_needed && thread_step_needed)
> > and there's already a breakpoint at the PC, is this:
> >
> >               if (!step)
> >                 {
> >                   warning ("Internal error, changing continue to step.");
> >
> > That blows up, because step will always be zero here if
> > SOFTWARE_SINGLE_STEP_P ().  Is this patch OK?  It seems to work in my tests
> > here.
> 
> I like the problem analysis, but not the implementation of the solution.
> If we are going to always set step to zero for SOFTWARE_SINGLE_STEP_P,
> then it does not make sense to set it to one again, even if the code
> will never be reached (in theory).  I would rather see it made explicit
> that this code should never be reached if SOFTWARE_SINGLE_STEP_P is true.
> Something like this:
> 
> <       if (!step)
> ---
> >       if (!(step && SOFTWARE_SINGLE_STEP_P()))

Err, my logic is wrong, but you get the idea...  maybe I meant
	if (!step && !SOFTWARE_SINGLE_STEP_P())