Re: frame cache

Michael Eager
2007-07-24T18:45:18Z

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