Re: frame cache

[Michael Eager <eager at eagercon dot com>]

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