3CPS: The Design of an Environment-Focussed Intermediate Representation

We describe the design of 3CPS, a compiler intermediate representation (IR) we have developed for use in compiling call-by-value functional languages such as SML, OCaml, Scheme, and Lisp. The language is a low-level form designed in tandem with a matching suite of static analyses. It reflects our belief that the core task of an optimising compiler for a functional language is to reason about the environment structure of the program. Our IR is distinguished by the presence of extent annotations, added to all variables (and verified by static analysis). These annotations are defined in terms of the semantics of the IR, but they directly tell the compiler what machine resources are needed to implement the environment structure of each annotated variable.