Re: frame cache

Michael Eager
2007-07-24T17:08:31Z

Michael Eager wrote:
> I have a couple questions about the <target>_frame_cache
> structure and functions.
>
> 1) This appears to be a single-entry cache. Why not keep
> multiple entries?
>
> 2) The data in the frame cache seems to be of two different
> types:
> a) Fixed, based on analyzing the code: register offsets,
> stack alignment, framelessness, etc.
> b) Variable, based on the call: return pc, frame base
>
> It looks to me that the object code is analyzed repeatedly
> and this fixed information is discarded along with the
> variable information.
>
> Why not keep a persistent cache of function specific fixed
> data and only discard the call-specific data when the frame
> cache is cleared?
>
> Is there any documentation about what target-specific data
> the frame cache is supposed to contain or how the functions are
> supposed to work?

And one more question:

3) In <target>_skip_prologue(), an dummy <target>_frame_cache is
created to be passed to <target>_analyze_prologue(). This
dummy cache entry is discarded. Why not retain this info?

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