[Gcl-devel] Re: Two word cons

[Paul F. Dietz]

Camm Maguire wrote:
> Greetings, and thanks for the feedback!
>
> "Paul F. Dietz" <address@hidden> writes:
>
>
> > Camm,
> >
> >   Judging by the space allocation numbers from TIME, objects
> > are also constrained to be an even number of words in Allegro CL
> > and in SBCL.  I think this is a common idea.
> >
> >   If you have an extra field in some objects, consider uses for
> > it.  For example, we might want to precompute a hash key
> > for symbols (based on the package and symbol-name) if we're not
> > doing this already.  This could speed up SXHASH and EQ/EQL hash tables,
> > as well as CASE forms on symbols (switch on the hash key).
>
>
> Great ideas!  Do I take it that you feel such a change (along the
> lines described below) is beneficial on both 32bit and 64bit machines?
> Am I missing anything key/important in the design considerations?

I think it would be.  SBCL does it for both sizes.  They cache
the SXHASH for symbols into the symbol rather than precomputing
it (and the hash doesn't depend on the package), but the idea
is similar.

        Paul