RE: [patch v8 05/24] frame: artificial frame id's

["Metzger, Markus T" <markus dot t dot metzger at intel dot com>]

> -----Original Message-----
> From: Jan Kratochvil [mailto:jan.kratochvil@redhat.com]
> Sent: Thursday, December 12, 2013 8:56 PM

Thanks for your feedback, Pedro.

Jan already answered some of your questions.
[...]

> > Looks like frame_ id_eq (null_frame_id, null_frame_id) now
> > returns true, while it returns false before.  If you discussed
> > all this and came to the conclusion it's OK, please document
> > it in the commit log.  In any case (I'm not sure offhand if
> > that's OK), the NaN comment above is no longer correct,
> > and neither is this one:
> 
> That was not needed / intentional so it would be better to keep the original
> behavior.

Would it be OK to have no frame be equal to null_frame_id?

diff --git a/gdb/frame.c b/gdb/frame.c
index 37d780e..efda1cc 100644
--- a/gdb/frame.c
+++ b/gdb/frame.c
@@ -577,16 +577,17 @@ frame_id_eq (struct frame_id l, struct frame_id r)
 {
   int eq;
 
-  if (memcmp (&l, &r, sizeof (l)) == 0)
-    /* Every frame is equal to itself.
+  if (memcmp (&l, &null_frame_id, sizeof (l)) == 0
+      || memcmp (&r, &null_frame_id, sizeof (r)) == 0)
+    /* Like a NaN, if either ID is invalid, the result is false.
+       Note that a frame ID is invalid iff it is the null frame ID.  */
+    eq = 0;
+  else if (memcmp (&l, &r, sizeof (l)) == 0)
+    /* Every valid 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.
-       Note that a frame ID is invalid iff it is the null frame ID.  */
-    eq = 0;
   else if (l.stack_addr != r.stack_addr)
     /* If .stack addresses are different, the frames are different.  */
     eq = 0;


Regards,
Markus.

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