Scott A Crosby <crosby at qwes.math.cmu.edu> wrote:
> On Mon, 4 Feb 2002, Tim Rowledge wrote:
> > Anyone wanting to evaluate the difference in performance and space can
> > do so by looking at the 'private' prococol of Behavior - you can make
> > all the currently compact classes non-compact without any vm changes.
> > check the image size profile and performance before and after.
> 
> I tried that, as the first part in building a VM with no compact classes
> at all; it doesn't work.
> 
>     CompiledMethod BlockContext MethodContext
> 
> override basicNew to error; there may be a way to uncompact them, but the
> normal technique does not work. Removing the failure messages and trying
> again leads to VM failure.

The VM hard codes certain compact class indexes for speed (avoiding
special objects lookup).  See Interpreter >> #isContextHeader: and its
senders.

Cheers,
Anthony