Release RTL bodies after compilation (sometimes)

[Geoffrey Keating]

David Edelsohn <dje@watson.ibm.com> writes:

> 	Using lots of memory in an inefficient manner slows down the
> compiler.  We should not turn the compile-time performance into a fixation
> on reducing memory usage as a goal in isolation.

This is an important point.  I don't believe that freeing memory gives
significant compile speed benefits except in unusual cases, and in
general it slows the compile down because of the overhead of doing the
freeing.

When we speak of 'reducing memory usage' here at Apple, we do not mean
'allocating as much memory as before and then freeing it'.  We mean
allocating less memory than before, and preferably doing this by
allocating fewer objects rather than the same number of smaller ones.