tor, and not just
a leak detector.  We initially assume that it is used in stop-the-world,
non-incremental mode, though the presence of the incremental collector
will be apparent in the design.
We assume the default finalization model, but the code affected by that
is very localized.
<H2> Introduction </h2>
The garbage collector uses a modified mark-sweep algorithm.  Conceptually
it operates roughly in four phases, which are performed occasionally
as part of a memory allocation:

<OL>

<LI>
<I>Preparation</