Re: [RFA] enable software single step on alpha-osf

[Kevin Buettner <kevinb at redhat dot com>]

On Aug 16,  3:26pm, Daniel Jacobowitz wrote:

> > Expressions like:
> > 
> > /* Pass TRUE if our reason for stopping is something other
> >    than hitting a breakpoint.  We do this by checking that
> >    1) stepping is going on and 2) we didn't hit a breakpoint
> >    in a signal handler without an intervening stop in
> >    sigtramp, which is detected by a new stack pointer value
> >    below any usual function calling stack adjustments.  */
> > (currently_stepping (ecs)
> >  && prev_pc != stop_pc - DECR_PC_AFTER_BREAK
> >  && !(step_range_end && INNER_THAN (read_sp (),(step_sp - 16)))));
> 
> Which reminds me - does that use of INNER_THAN make even the slightest
> sense on stack-grows-up architectures?  I don't think it does.

I don't think so either.

Also, that magical value of 16 just can't be right for all architectures.

But this is one of those areas where we have to be *very* careful.
We can attempt to make well-meaning changes and then discover many
months later that we've broken something that used work.

For the above, I think we need to figure out the intent behind the
condition

    INNER_THAN (read_sp (),(step_sp - 16),

and then write an architecture dependent method for it.

Kevin