This file will contain an overview of the `middle end' of the
compiler.

See ~gjr/work/liar94/text/passes.txt

It will also describe how a `generic' rewriting phase works.

There is a file for each rewriting phase describing:

 . The input language
 . The ouput language
 . How it works (e.g two pass, substitute mumble for mumble)
 . Details of how it works, including any trick, use of assumptions etc.