Re: [RFA/PATCH] breakpoint.c: fix until command

[Michael Snyder <msnyder at redhat dot com>]

Elena Zannoni wrote:
> 
> Daniel Jacobowitz writes:
>  > On Fri, Jan 03, 2003 at 04:05:11PM -0800, Michael Snyder wrote:
>  > > Well then...
>  > > 1) Use find_pc_partial_function to determine bounds and
>  > > distinguish between in-bounds and out-of-bounds locations.
>  > > 2) For func_start > loc >= func_end, use a frame-relative bp.
>  > > 3) For func_start == loc or loc < func_start or loc > func_end,
>  > > use a frameless bp.
>  > > 4) document, document, document!
>  > > Including the recursive corner case.
>  > >
>  > > Agreed, Elena?
>  >
>  > So you're saying:
>  >  - if the PC is in this function, only stop when this frame reaches it.
> 
> yes
> 
>  >  - if the PC is the _beginning_ of a function (what about prologue
>  >    skipping, does that come into this?  I don't remember if
>  >    decode_line_1 will skip the prologue, but I think it will.) or in
>  >    some other function, stop in any frame.
> 
> yes, but every time I think about this, I can find an example for
> which we get in trouble. Another case that comes to mind is until
> 0x12345 where the address is in the prologue of the same function.
> What to do in this case.

We've got to draw a line in the sand.  ;-)
Making "until factorial" an exception is a big enough concession.
I don't think the user can expect to do "until some-address-in-the-prologue"
and expect it to have a special meaning.

My suggestion remains:  
  if func_start > location >= func_end then frame_relative.


>  > > Daniel?  Michael?
>  >
>  > I'd be happier if those two behaviors had different names, but the
>  > logical name I'd give to both of them is "until", so I guess we'll just
>  > have to live with this.  (3) is meaningful when inside the function
>  > too, and with this scheme there's no way to express that without using
>  > breakpoints; but I think that's a small loss.
>  >
> 
> Actually I start to believe that we need 2 separate commands.  One
> would do the current behavior the other would be w/o frame check.  We
> already have 'jump' (and it means something different). Maybe 'goto'?
> I can't think of a decent name. 'reach', 'get to'?

run-to?
I like the idea of restricting "until" to the current function,
and using a separate command for locations outside the current function.
(or inside, if you want the effect of a temporary breakpoint).
This would remove the ambiguity.