Practical Aspects for a Working Compile Time Garbage Collection System for Mercury

TL;DR

This paper presents a practical implementation of a compile-time garbage collection system for Mercury, demonstrating significant memory savings and performance improvements through a series of design decisions and benchmark evaluations.

Contribution

It introduces a working, high-performance CTGC system integrated into the Melbourne Mercury Compiler, advancing the practical adoption of compile-time garbage collection in logic programming.

Findings

Substantial memory savings observed in benchmarks

Noticeable reduction in execution time

Effective design decisions enabling practical CTGC implementation

Abstract

Compile-time garbage collection (CTGC) is still a very uncommon feature within compilers. In previous work we have developed a compile-time structure reuse system for Mercury, a logic programming language. This system indicates which datastructures can safely be reused at run-time. As preliminary experiments were promising, we have continued this work and have now a working and well performing near-to-ship CTGC-system built into the Melbourne Mercury Compiler (MMC). In this paper we present the multiple design decisions leading to this system, we report the results of using CTGC for a set of benchmarks, including a real-world program, and finally we discuss further possible improvements. Benchmarks show substantial memory savings and a noticeable reduction in execution time.