Precision or Peril: Evaluating Code Quality from Quantized Large Language Models

When scaled to hundreds of billions of parameters, Large Language Models (LLMs) such as GPT-4 and LLaMA-405b have demonstrated remarkable capabilities in tasks such as code generation, code completion, and writing test cases. However, scaling up model sizes results in exponentially higher computational cost and energy consumption, leaving a large carbon footprint and making these models difficult to use by academic researchers and small businesses. Quantization has emerged as a way to mitigate the memory overhead of LLMs, allowing them to run on smaller hardware for lower prices. Quantization, however, may have detrimental effects on a model's output and it's effects on LLM generated code quality remains understudied and requires constant evaluation as LLMs are improved. This study aims to evaluate the current code generation capabilities of smaller LLMs using various metrics, exploring the impact of quantization on code quality, and identifying prevalent quality issues in the generated code. Method: We conducted a comprehensive evaluation of four smaller open-source LLMs across two benchmarks and code similarity scores. The impact of 8-bit and 4-bit quantization was analyzed, and a static analysis tool was utilized to scrutinize the generated code's quality. Our findings reveal that while the tested LLMs exhibit potential, these smaller LLMs produce code with subpar performance on established benchmarks. The effects of quantization on code quality are inconsistent, and the generated code frequently exhibits recurring quality and maintainability issues. This study underscores the necessity for careful scrutiny and validation of LLM-generated code before its adoption in software projects. While smaller LLMs can generate code, their output requires careful monitoring and validation by practitioners before integration into software projects.