MimIR: An Extensible and Type-Safe Intermediate Representation for the DSL Age

TL;DR

MimIR is a flexible, type-safe intermediate representation for DSL compilers that allows easy extension with new domain-specific operations, enabling optimized code generation across various application domains.

Contribution

MimIR introduces a typed lambda calculus-based IR that supports extensible, plugin-based addition of domain-specific operations with guaranteed type safety.

Findings

MimIR achieves state-of-the-art performance in three diverse case studies.

Plugins extend MimIR at various abstraction levels, demonstrating flexibility.

Code generated with MimIR is efficient across different application domains.

Abstract

Traditional compilers, designed for optimizing low-level code, fall short when dealing with modern, computation-heavy applications like image processing, machine learning, or numerical simulations. Optimizations should understand the primitive operations of the specific application domain and thus happen on that level. Domain-specific languages (DSLs) fulfill these requirements. However, DSL compilers reinvent the wheel over and over again as standard optimizations, code generators, and general infrastructure & boilerplate code must be reimplemented for each DSL compiler. This paper presents MimIR, an extensible, higher-order intermediate representation. At its core, MimIR is a pure type system and, hence, a form of a typed lambda calculus. Developers can declare the signatures of new (domain-specific) operations, called "axioms". An axiom can be the declaration of a function, a type constructor, or any other entity with a possibly polymorphic, polytypic, and/or dependent type. This way, developers can extend MimIR at any low or high level and bundle them in a "plugin". Plugins extend the compiler and take care of optimizing and lowering the plugins' axioms. We show the expressiveness and effectiveness of MimIR in three case studies: Low-level plugins that operate at the same level of abstraction as LLVM, a regular-expression matching plugin, and plugins for linear algebra and automatic differentiation. We show that in all three studies, MimIR produces code that has state-of-the-art performance.