To Diff or Not to Diff? Structure-Aware and Adaptive Output Formats for Efficient LLM-based Code Editing

Fuente: arXiv
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Autori principali: Cheng, Wei, Cao, Yongchang, Shen, Chen, Li, Binhua, Chen, Jue, Li, Yongbin, Hu, Wei
Natura: Preprint
Pubblicazione: 2026
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author Cheng, Wei
Cao, Yongchang
Shen, Chen
Li, Binhua
Chen, Jue
Li, Yongbin
Hu, Wei
author_facet Cheng, Wei
Cao, Yongchang
Shen, Chen
Li, Binhua
Chen, Jue
Li, Yongbin
Hu, Wei
contents Large Language Models (LLMs) are increasingly used for code editing, yet the prevalent full-code generation paradigm suffers from severe efficiency bottlenecks, posing challenges for interactive coding assistants that demand low latency and cost. Despite the predominant focus on scaling model capabilities, the edit format itself has been largely overlooked in model training. In this paper, we begin with a systematic study of conventional diff formats and reveal that fragile offsets and fragmented hunks make generation highly unnatural for LLMs. To address it, we introduce BlockDiff and FuncDiff, two structure-aware diff formats that represent changes as block-level rewrites of syntactically coherent units such as control structures and functions. Furthermore, we propose AdaEdit, a general adaptive edit strategy that trains LLMs to dynamically choose the most token-efficient format between a given diff format and full code. Extensive experiments demonstrate that AdaEdit paired with structure-aware diff formats consistently matches the accuracy of full-code generation, while reducing both latency and cost by over 30% on long-code editing tasks.
format Preprint
id arxiv_https___arxiv_org_abs_2604_27296
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle To Diff or Not to Diff? Structure-Aware and Adaptive Output Formats for Efficient LLM-based Code Editing
Cheng, Wei
Cao, Yongchang
Shen, Chen
Li, Binhua
Chen, Jue
Li, Yongbin
Hu, Wei
Software Engineering
Computation and Language
Large Language Models (LLMs) are increasingly used for code editing, yet the prevalent full-code generation paradigm suffers from severe efficiency bottlenecks, posing challenges for interactive coding assistants that demand low latency and cost. Despite the predominant focus on scaling model capabilities, the edit format itself has been largely overlooked in model training. In this paper, we begin with a systematic study of conventional diff formats and reveal that fragile offsets and fragmented hunks make generation highly unnatural for LLMs. To address it, we introduce BlockDiff and FuncDiff, two structure-aware diff formats that represent changes as block-level rewrites of syntactically coherent units such as control structures and functions. Furthermore, we propose AdaEdit, a general adaptive edit strategy that trains LLMs to dynamically choose the most token-efficient format between a given diff format and full code. Extensive experiments demonstrate that AdaEdit paired with structure-aware diff formats consistently matches the accuracy of full-code generation, while reducing both latency and cost by over 30% on long-code editing tasks.
title To Diff or Not to Diff? Structure-Aware and Adaptive Output Formats for Efficient LLM-based Code Editing
topic Software Engineering
Computation and Language
url https://arxiv.org/abs/2604.27296