Re: RFC: Mostly kill FRAME_CHAIN_VALID, add user knob

[Daniel Jacobowitz <drow@mvista.com>]

On Thu, Jan 02, 2003 at 07:34:16PM +0000, Andrew Cagney wrote:
> >Pretty gross, neh?  Well, file vs. func is merely a question of whether we
> >stop at main or not, so I added "set backtrace-below-main" in order to let
> >the user choose.  Generic vs. not is a question of dummy frames, and the
> >generic versions work with non-generic dummy frames, so there's no reason
> >for that distinction earlier.  It won't harm those three m68k targets (if
> >they still work) to use a more comprehensive frame_chain_valid.  And the
> >five more specific ones up above can be retained, since they are only
> >_additional_ checks.  I'm not entirely convinced that the Interix one is
> >necessary but I left it alone.
> >
> >So, after this patch we have FRAME_CHAIN_VALID as a predicated function 
> >that
> >only five architectures define; everything else just uses the new
> >frame_chain_valid () function, which is a more general version of
> >generic_func_frame_chain_valid.
> >
> >I'm more confident I got the texinfo right this time :)  I tested the patch
> >and the new functionality on i386-linux and arm-elf, to make sure I got the
> >details of FRAME_CHAIN_VALID_P () right.
> >
> >I'll look to commit this in January, if no one has any comments.  Andrew,
> >would you rather this went in frame.c?  Since a purpose of that file seems
> >to be moving things from blockframe.c to it...
> 
> FYI,
> 
> Much of this is superseeded by the frame overhaul - in particular the 
> introduction of frame_id_unwind().  The new code doesn't even call frame 
> chain valid!
> 
> Perhaphs wait for the attached [wip] to be committed and then tweak that 
> to match your proposed policy (we can then just deprecate 
> FRAME_CHAIN_VALID_P :-).  However, making the change in parallel 
> wouldn't hurt.
> 
> Looking at my WIP, I'll need to tweak the code segment:
> 
> +  prev_frame->pc = frame_pc_unwind (next_frame);
> +  if (prev_frame->pc == 0)
> +    /* The allocated PREV_FRAME will be reclaimed when the frame
> +       obstack is next purged.  */
> +    return NULL;
> +  prev_frame->type = frame_type_from_pc (prev_frame->pc);
> 
> so that it checks for where the PC resides and abort accordingly.
> 
> The attached is WIP since I still need to see it working once :-)

[Small wonder if you haven't pushed the call to FRAME_CHAIN_VALID
somewhere... that's the same sort of thing that confuses me about all
of your frame changes...]

I've chosen to commit it instead, since your WIP isn't ready, and since
you understand better than I do how it'll fit into the New Order.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer