Cleavir

Cleavir is an implementation-independent framework for creating Common Lisp compilers. It is modular and extensible, so that CL implementations with different aims and backends can share the same code.

Getting started

The Example/ directory contains a worked example of a simplified Cleavir client, showing how Cleavir can be used to translate Common Lisp code into an intermediate representation, and how optimizations can be applied to this IR. The README there explains how to load and use that system.

Basic structure

Cleavir is not a single system. It is instead a collection of systems that can be incorporated together as subsystems of a compiler.

The CST-to-AST system parses Common Lisp source code, in the form of CSTs, into objects called Abstract Syntax Trees (ASTs). ASTs closely represent the original source as standard-objects. They are suitable for further compilation processing, but also for other purposes like code walking and some analysis.

The AST-to-BIR system generates a Block-based Intermediate Representation (BIR) from ASTs. The BIR makes program control and data flow explicit while remaining independent of the target machine. More information on BIR is available in the BIR/ directory.

The BIR-transformations system analyzes and applies various optimizations to BIR. More information on the transformations Cleavir defines are available in the BIR-transformations/ directory.

Clients may customize surface syntax by defining subclasses and methods at the AST level, and lower level operations by doing the same at the IR level. Individual modules can be used independently of one another, e.g. a code-walking application need not use anything below the AST level.

System Information

Subsystems

• cleavir-example

  Example frontend for the Cleavir toolkit.

• cleavir-cst-to-ast

  Compiler of source concrete syntax trees into abstract syntax trees.

• cleavir-environment

  Interface for managing lexical environments.

• cleavir-ast

  Abstract Syntax Tree representation for Common Lisp code.

• cleavir-ast-to-bir

  Compiler of abstract syntax trees into BIR.

• cleavir-bir

  Block-based Intermediate Representation for compiled Lisp code.

• cleavir-set

  A set data structure.

• cleavir-attributes

  Information about values not encompassed by the type system.

• cleavir-ctype

  Interface to client type systems.

• cleavir-primop

  Abstract Syntax Tree representation for Common Lisp code.

• cleavir-compilation-policy

  System for representing and interrogating compiler policies.

• cleavir-conditions

  Utilities for conditions signaled by compilers.

• cleavir-io

  Utilities for textual I/O of Lisp objects.

• cleavir-meter

  Utilities for measuring performance of compiler tools.

• cleavir-stealth-mixins

  Utilities for adding mixins to classes after they are defined.