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

Pedro Alves
2013-12-11T12:24:26Z

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