Hierarchical Context Pruning: Optimizing Real-World Code Completion with Repository-Level Pretrained Code LLMs

TL;DR

This paper introduces Hierarchical Context Pruning (HCP), a method that improves code completion accuracy for repository-level Code LLMs by maintaining topological dependencies and reducing irrelevant code content, thus optimizing prompt length and performance.

Contribution

The paper proposes HCP, a novel strategy that models code repositories at the function level to enhance code completion accuracy and efficiency in large language models.

Findings

HCP significantly improves completion accuracy across six Repo-Code LLMs.

HCP reduces input length while maintaining high informational content.

Pruning function implementations in dependent files does not significantly impact accuracy.

Abstract

Some recently developed code large language models (Code LLMs) have been pre-trained on repository-level code data (Repo-Code LLMs), enabling these models to recognize repository structures and utilize cross-file information for code completion. However, in real-world development scenarios, simply concatenating the entire code repository often exceeds the context window limits of these Repo-Code LLMs, leading to significant performance degradation. In this study, we conducted extensive preliminary experiments and analyses on six Repo-Code LLMs. The results indicate that maintaining the topological dependencies of files and increasing the code file content in the completion prompts can improve completion accuracy; pruning the specific implementations of functions in all dependent files does not significantly reduce the accuracy of completions. Based on these findings, we proposed a strategy named Hierarchical Context Pruning (HCP) to construct completion prompts with high informational code content. The HCP models the code repository at the function level, maintaining the topological dependencies between code files while removing a large amount of irrelevant code content, significantly reduces the input length for repository-level code completion. We applied the HCP strategy in experiments with six Repo-Code LLMs, and the results demonstrate that our proposed method can significantly enhance completion accuracy while substantially reducing the length of input. Our code and data are available at https://github.com/Hambaobao/HCP-Coder.