arXiv subjects

Simantika Bhattacharjee Dristi

Publications and source records attributed to Simantika Bhattacharjee Dristi.

4 recordsLinked to original sources

arXiv2026

What Survives the Next Model? Benchmarking LLM-Based Techniques Against Single-Prompts

The software engineering research community has enthusiastically embraced the integration of Large Language Models (LLMs) into complex techniques to solve a wide variety of tasks. However, the extent to which this investment is strategic remains unclear, as the native capabilities of successive frontier model generations can rapidly render existing techniques obsolete. To assess this research investment, we analyze 35 LLM-based technique papers from ICSE 2026. We evaluate whether their complex tools can be outperformed by the simplest possible alternative: a single, automatically generated prompt executed on a newer generation model, without any iterative refinement. We find that for between 37% and 63% papers, a newer model with a single prompt natively outperforms the heavily engineered tooling proposed just a year prior. We identify that constructive techniques like code generation or repair are more amenable to substitution by a single-prompt. We also identify a surviving set of papers relying on strategies that provide additional insights to the model where newer LLMs will amplify the proposed technique. Our findings raise questions about the cost-benefit proposition of techniques designed as workarounds to temporary model deficits and the need to focus on enduring challenges that scale synergistically with future model generations. Our source codes and results are made publicly available at https://github.com/less-lab-uva/What-Survives-the-Next-Model.

cs.SE↗

arXiv2026

SONAR: Task-Aware Code Summary Evaluation for LLM Consumers Without References

Source code summaries have traditionally been evaluated from a human developer's perspective, with quality determined by how closely they resemble developer-written references and how well they align with human preferences. But this overlooks a growing reality: LLM-based tools and agents increasingly consume code summaries as inputs for software engineering (SE) tasks, and what makes a summary useful for a consuming agent on a task remains largely unexplored. To bridge this gap, we propose SONAR, a reference-free framework that evaluates source code summaries along four dimensions: Correctness, Abstraction, Conciseness, and Fluency. Rather than optimizing for a pre-written "gold standard", SONAR introduces a novel code regeneration-based approach that uses a summary to regenerate code and leverages that reconstruction as a quality signal of the summary. This provides an empirical grounding that requires neither a reference summary nor the subjective judgment of humans or LLMs. We evaluate SONAR's dimensions on their ability to influence LLM performance across four downstream SE tasks. We find that Correctness, followed by Abstraction, significantly correlates with LLM performance, with correlations up to 14X higher than the best baseline. Conciseness and Fluency, though widely valued by human developers, remain mostly insignificant to an LLM consumer, suggesting that what makes a summary useful is task- and consumer-dependent. Through a large-scale evaluation of 11 popular LLMs using SONAR, we further identify the strengths and weaknesses of different models across each quality dimension, while offering insights to facilitate future research on task-aware summarization.

cs.SE↗

arXiv2026

A Differential Fuzzing-Based Evaluation of Functional Equivalence in LLM-Generated Code Refactorings

With the rapid adoption of large language models (LLMs) in automated code refactoring, assessing and ensuring functional equivalence between LLM-generated refactoring and the original implementation becomes critical. While prior work typically relies on predefined test cases to evaluate correctness, in this work, we leverage differential fuzzing to check functional equivalence in LLM-generated code refactorings. Unlike test-based evaluation, a differential fuzzing-based equivalence checker needs no predefined test cases and can explore a much larger input space by executing and comparing thousands of automatically generated test inputs. In a large-scale evaluation of six LLMs (CodeLlama, Codestral, StarChat2, Qwen-2.5, Olmo-3, and GPT-4o) across three datasets and two refactoring types, we find that LLMs show a non-trivial tendency to alter program semantics, producing 19-35% functionally non-equivalent refactorings. Our experiments further demonstrate that about 21% of these non-equivalent refactorings remain undetected by the existing test suites of the three evaluated datasets. Collectively, the findings of this study imply that reliance on existing tests might overestimate functional equivalence in LLM-generated code refactorings, which remain prone to semantic divergence.

cs.SE↗

arXiv2025

Analyzing and Mitigating Surface Bias in Code Evaluation Metrics

With the increasing popularity of large language models (LLMs) and LLM-based agents, reliable and effective code evaluation metrics (CEMs) have become crucial for progress across several software engineering tasks. While popular benchmarks often provide test cases to assess the correctness of generated code, crafting and executing test cases is expensive. Reference-based CEMs provide a cheaper alternative by scoring a candidate program based on its functional similarity to a reference. Although prior research has focused on reporting the weak correlation between these CEMs and functional correctness, the causes are only assumed, and plausible solutions remain unexplored. In this work, we critically evaluate four state-of-the-art reference-based CEMs, revealing their strong bias towards surface-level features rather than code functionality. Despite this surface bias, current evaluation datasets for these CEMs rarely include code pairs that are surface-similar yet functionally dissimilar, or functionally similar yet surface-dissimilar. To mitigate this gap, we propose LoCaL (Looks Can Lie), a CEM evaluation benchmark, with 3117 code pairs at both the method and program levels. Each pair is labeled with a functional similarity score and aims to target regions where CEMs are likely to perform poorly. The functional similarity scores are calculated through differential fuzzing, which eliminates the need for predefined test cases and, at the same time, improves the reliability of the scores by executing an order of magnitude more tests than prior work. We find that all four CEMs show significant performance degradation on LoCaL, compared to the baselines. Finally, based on our findings, we draw the implication that exposing CEMs to LoCaL-like data might facilitate the development of metrics that are robust to surface bias.

cs.SE↗