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

[Michael Snyder <msnyder@redhat.com>]

Elena Zannoni wrote:
> 
> Michael Snyder writes:
>  > Elena Zannoni wrote:
>  > >
>  > > Michael Snyder writes:
>  >
>  > >  > If you say "until <line>", and the line is inside the current function,
>  > >  > you can impose the frame restriction.  If the line (or address) is outside
>  > >  > the current function, or if you give a function name or something else,
>  > >  > you can't.  And I don't think we can code that distinction at runtime.
>  > >
>  > > I think we should come up with a behavior matrix, something like:
>  > >
>  > > until:
>  > >  continue until next source line is reached. If already at the last line
>  > >  of current function, continue until current frame pops.
>  > >
>  > > until line:
>  > >  a. line in current function (1) --> continue until the line is reached.
>  >
>  > Agreed, with the qualification given.
>  >
>  > >  b. line in function in inner frame --> continue until the line is reached.
>  >
>  > Agreed.
>  >
>  > >  c. line in function not in inner frame --> continue until current frame pops.
>  >
>  > Agreed.
>  >
>  > > (1) However if current function is recursive, a. should become like
>  > >     b. But we want to enforce a different behavior, because we don't
>  > >     want to stop in the inner frame.
>  >
>  > I think this could be stated simply as "continue until the line
>  > is reached by the current execution frame".
>  >
>  > > --> this is the main problem,
>  > >     because the condition is basically impossible to figure out at run
>  > >     time.
>  >
>  > If we can figure it out at runtime, you would agree to it?
>  >
>  > > until funcname:
>  > >  d. funcname called from current frame (2) --> continue until func is reached
>  >
>  > Agreed.
>  >
>  > >  e. funcname not called from current frame --> cont until current frame pops.
>  >
>  > Agreed.
>  >
>  > > (2) if current function is recursive and funcame == current function
>  > >     we want to stop at the next inner invocation of funcname
>  >
>  > Ow, not obvious.  But since it clearly isn't specified now,
>  > I suppose we could make up such a stipulation if we choose to.
>  > I don't even know what the traditional behavior would be in
>  > this case.
>  >
>  >
>  > > The 'continue until current frame pops' behavior is already there. It
>  > > always puts another bp_until at the caller.
>  >
>  > Yep.
>  >
>  > So AFAICT, we have only one corner case to agree upon.
>  > "until factorial".
> 
> yes yes yes!

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?

Daniel?  Michael?

Anyone else?