Re: RFA: frame id enhancement

[Andrew Cagney <ac131313@redhat.com>]

> @@ -288,6 +297,9 @@
>      eq = 0;
>    else if (l.stack_addr != r.stack_addr)
>      /* If .stack addresses are different, the frames are different.  */
> +    eq = 0;
> +  else if (l.special_addr != r.special_addr)
> +    /* If .special addresses are different, the frames are different.  */
>      eq = 0;
>    else if (l.code_addr == 0 || r.code_addr == 0)
>      /* A zero code addr is a wild card, always succeed.  */

Looking at the full code:

> int
> frame_id_eq (struct frame_id l, struct frame_id r)
> {
>   int eq;
>   if (l.stack_addr == 0 || r.stack_addr == 0)
>     /* Like a NaN, if either ID is invalid, the result is false.  */
>     eq = 0;
>   else if (l.stack_addr != r.stack_addr)
>     /* If .stack addresses are different, the frames are different.  */
>     eq = 0;
>   else if (l.code_addr == 0 || r.code_addr == 0)
>     /* A zero code addr is a wild card, always succeed.  */
>     eq = 1;
>   else if (l.code_addr == r.code_addr)
>     /* The .stack and .code are identical, the ID's are identical.  */
>     eq = 1;
>   else
>     /* No luck.  */
>     eq = 0;
>   if (frame_debug)
>     {
>       fprintf_unfiltered (gdb_stdlog, "{ frame_id_eq (l=");
>       fprint_frame_id (gdb_stdlog, l);
>       fprintf_unfiltered (gdb_stdlog, ",r=");
>       fprint_frame_id (gdb_stdlog, r);
>       fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", eq);
>     }
>   return eq;
> }

Is there a need to allow wild card SPECIAL_ADDRs here?  The user can 
specify:
	(gdb) frame <frame-id-stack-addr>
and on some architectures:
	(gdb) frame <frame-id.stack-addr> <frame-id.code-addr>
and have GDB jump to that frame.  It relies on the wild-card mechanism 
to give approx matches (otherwize the user will have to fully specify 
<stack-addr>, <code-addr> and <special-addr>).

Looking at:

> int
> frame_id_inner (struct frame_id l, struct frame_id r)
> {
>   int inner;
>   if (l.stack_addr == 0 || r.stack_addr == 0)
>     /* Like NaN, any operation involving an invalid ID always fails.  */
>     inner = 0;
>   else
>     /* Only return non-zero when strictly inner than.  Note that, per
>        comment in "frame.h", there is some fuzz here.  Frameless
>        functions are not strictly inner than (same .stack but
>        different .code).  */
>     inner = INNER_THAN (l.stack_addr, r.stack_addr);
>   if (frame_debug)
>     {
>       fprintf_unfiltered (gdb_stdlog, "{ frame_id_inner (l=");
>       fprint_frame_id (gdb_stdlog, l);
>       fprintf_unfiltered (gdb_stdlog, ",r=");
>       fprint_frame_id (gdb_stdlog, r);
>       fprintf_unfiltered (gdb_stdlog, ") -> %d }\n", inner);
>     }
>   return inner;
> }

does SPECIAL_ADDR add further ordering?  If it doesn't then the comment 
needs to be updated (and the description in "frame.h" clarified).

Andrew