Re: frame cache

[Michael Eager <eager@eagercon.com>]

Daniel Jacobowitz wrote:
> On Tue, Jul 24, 2007 at 10:35:59AM -0700, Michael Eager wrote:
>> I don't see any links to the <target>_frame_cache in frame_info.
>> I don't see anything in frame.c which looks like it searches
>> for the correct <target>_frame_cache.  Can you point me at the
>> right place?
> 
> Sure:
> 
>   /* The frame's low-level unwinder and corresponding cache.  The
>      low-level unwinder is responsible for unwinding register values
>      for the previous frame.  The low-level unwind methods are
>      selected based on the presence, or otherwise, of register unwind
>      information such as CFI.  */
>   void *prologue_cache;
>   const struct frame_unwind *unwind;

I missed that prologue_cache ==> <target>_frame_cache.
I only saw that it was set by sentinel_frame_cache, but
now I see that it is passed to frame_unwind_find_by_frame()
and on from there.  (Bad void pointer, bad, bad.)

>> When I put debugging code in <target>_analyze_prologue(), I see
>> that it is called over and over while executing a "next" command.
>> All those bits going back and forth over the serial line to the
>> target.
> 
> I like to use GDB's built in data caching and/or set
> trust-readonly-sections.  I hope we can make the data caching more
> aggressive by default at some point.

Perhaps you or someone could write some documentation for this?  :-)

-- 
Michael Eager	 eager@eagercon.com
1960 Park Blvd., Palo Alto, CA 94306  650-325-8077