Re: [patch v7 05/24] frame: artificial frame id's

[Pedro Alves <palves at redhat dot com>]

Can you please add a rationale to the patch's intro?

I suppose one should find it digging around for the history
of the series, but one shouldn't have to.

Why wasn't this a problem before?

On 11/29/2013 02:38 PM, Markus Metzger wrote:
> 2013-11-29  Markus Metzger  <markus.t.metzger@intel.com>
> 
> 	* frame.h (frame_id_build_artificial): New.
> 	* frame.c (frame_id_build_artificial): New.
> 	(frame_id_p): An artificial frame is valid.
> 	(frame_id_eq): A frame is equal to itself.
> ---
>  gdb/frame.c | 28 +++++++++++++++++++++-------
>  gdb/frame.h |  6 ++++++
>  2 files changed, 27 insertions(+), 7 deletions(-)
> 
> diff --git a/gdb/frame.c b/gdb/frame.c
> index bd31d87..931a33c 100644
> --- a/gdb/frame.c
> +++ b/gdb/frame.c
> @@ -504,6 +504,19 @@ frame_id_build_wild (CORE_ADDR stack_addr)
>    return id;
>  }
>  
> +struct frame_id
> +frame_id_build_artificial (CORE_ADDR code_addr,
> +			   CORE_ADDR special_addr)
> +{
> +  struct frame_id id = null_frame_id;
> +
> +  id.code_addr = code_addr;
> +  id.code_addr_p = 1;
> +  id.special_addr = special_addr;
> +  id.special_addr_p = 1;
> +  return id;
> +}
> +
>  int
>  frame_id_p (struct frame_id l)
>  {
> @@ -514,6 +527,9 @@ frame_id_p (struct frame_id l)
>    /* outer_frame_id is also valid.  */
>    if (!p && memcmp (&l, &outer_frame_id, sizeof (l)) == 0)
>      p = 1;
> +  /* An artificial frame is also valid.  */
> +  if (!p && l.code_addr_p && l.special_addr_p)
> +    p = 1;
>    if (frame_debug)
>      {
>        fprintf_unfiltered (gdb_stdlog, "{ frame_id_p (l=");
> @@ -537,13 +553,11 @@ frame_id_eq (struct frame_id l, struct frame_id r)
>  {
>    int eq;
>  
> -  if (!l.stack_addr_p && l.special_addr_p
> -      && !r.stack_addr_p && r.special_addr_p)
> -    /* The outermost frame marker is equal to itself.  This is the
> -       dodgy thing about outer_frame_id, since between execution steps
> -       we might step into another function - from which we can't
> -       unwind either.  More thought required to get rid of
> -       outer_frame_id.  */
> +  if (memcmp (&l, &r, sizeof (l)) == 0)
> +    /* Every frame is equal to itself.
> +       This is the dodgy thing about outer_frame_id, since between execution
> +       steps we might step into another function - from which we can't unwind
> +       either.  More thought required to get rid of outer_frame_id.  */
>      eq = 1;
>    else if (!l.stack_addr_p || !r.stack_addr_p)
>      /* Like a NaN, if either ID is invalid, the result is false.
> diff --git a/gdb/frame.h b/gdb/frame.h
> index 3302645..29c3d16 100644
> --- a/gdb/frame.h
> +++ b/gdb/frame.h
> @@ -174,6 +174,12 @@ extern struct frame_id frame_id_build_special (CORE_ADDR stack_addr,
>     as the special identifier address are set to indicate wild cards.  */
>  extern struct frame_id frame_id_build_wild (CORE_ADDR stack_addr);
>  
> +/* Construct an artificial frame ID.  The first parameter is the frame's
> +   constant code address (typically the entry point), and the second the
> +   frame's special identifier address.  */
> +extern struct frame_id frame_id_build_artificial (CORE_ADDR code_addr,
> +						  CORE_ADDR special_addr);
> +
>  /* Returns non-zero when L is a valid frame (a valid frame has a
>     non-zero .base).  The outermost frame is valid even without an
>     ID.  */
> 


-- 
Pedro Alves