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Re: prev_pc problem on ia64
J. Johnston writes:
> Andrew Cagney wrote:
> > (I'll ignore the debug info :-)
> >
> >> > Same function compiled for i686:
> >> > > Special opcode 76: advance Address by 5 to 0x804839e and Line
> >> by 1 to 31
> >> > Special opcode 230: advance Address by 16 to 0x80483ae and Line
> >> by 1 to 32
> >> > Special opcode 146: advance Address by 10 to 0x80483b8 and Line
> >> by 1 to 33
> >> > Special opcode 160: advance Address by 11 to 0x80483c3 and Line
> >> by 1 to 34
> >> > > I have a patch whereby I reset prev_pc in
> >> infrun.c:init_execution_control_state():
> >> > > if (prev_pc != 0)
> >> > prev_pc = read_pc ();
> >> > > prior to setting the ecs->sal. This works for me in both
> >> scenarios. The check for
> >> > 0 was needed because I get a failure on the ia64 trying to read the
> >> pc too early when
> >> > the psr register was invalid.
> >> >
> >> maybe read_pc should return an error code? Ah wait, it errors out, so
> >> you should encapsulate that in a catch_errors().
> >
> >
> > The `prev_pc != 0' test is definitly wrong - that will only work when
> > GDB first starts. Provided the target_has_execution (?), there
> > shouldn't be an error (if there is, GDB's in bad shape :-), so the
> > change should always assign a value to prev_pc and, conditional on
> > target_has_execution, use the value of read_pc().
> >
>
> I tried to use target_has_execution but that did not work. The error
> I get is that the process does not exist. The read_pc() routine for the ia64 is doing
> a read_register_pid() and it appears that the inferior_ptid is not set up
> at a time when target_has_execution is set to true.
target_has_execution doesn't mean that the target is executing. It is
a total misnomer to indicate that the gdb target stratum is capable of
execution. I think what you want is target_has_registers.
elena
>
> Does this observation seem reasonable?
>
> > I'm also left wondering if the prev_func_name assignment in:
> >
> >> static void
> >> stop_stepping (struct execution_control_state *ecs)
> >> {
> >> if (target_has_execution)
> >> {
> >> /* Assuming the inferior still exists, set these up for next
> >> time, just like we did above if we didn't break out of the
> >> loop. */
> >> prev_pc = read_pc ();
> >> prev_func_name = ecs->stop_func_name;
> >> }
> >>
> >> /* Let callers know we don't want to wait for the inferior anymore. */
> >> ecs->wait_some_more = 0;
> >> }
> >
> >
> > should also be moved to init_execution_control_state, and both of those
> > assignments should be deleted.
> >
> > Is it possible to move both of these into the ECS state?
> >
> >> please post the patch to gdb-patches. It's hard to judge, like this.
> >
> >
> > Yes.
> >
> > Andrew
> >
> >
>