@inproceedings{cheng-etal-2026-sdar,
title = "{SDAR}: A Synergistic Diffusion-{A}uto{R}egression Paradigm for Scalable Sequence Generation",
author = "Cheng, Shuang and
Bian, Yihan and
Liu, Dawei and
Jiang, Yuhua and
Liu, Yihao and
Zhang, Linfeng and
Yao, Qian and
Tian, Zhongbo and
Wang, Wenhai and
Guo, Qipeng and
Chen, Kai and
Qi, Biqing and
Zhou, Bowen",
editor = "Liakata, Maria and
Moreira, Viviane P. and
Zhang, Jiajun and
Jurgens, David",
booktitle = "Findings of the {A}ssociation for {C}omputational {L}inguistics: {ACL} 2026",
month = jul,
year = "2026",
address = "San Diego, California, United States",
publisher = "Association for Computational Linguistics",
url = "https://aclanthology.org/2026.findings-acl.1110/",
pages = "22058--22075",
ISBN = "979-8-89176-395-1",
abstract = "Autoregressive (AR) language modeling remains the dominant paradigm due to its dense supervision signal and highly optimized serving infrastructure, but its strictly causal, token-by-token decoding limits parallelism and non-causal modeling. While masked diffusion offers a promising path toward parallel generation, it faces two critical bottlenecks: training inefficiency stemming from sparse masked objectives, and high latency caused by iterative whole-sequence denoising. We present a systematic study of blockwise discrete diffusion, a pragmatic middle ground that preserves AR-compatible serving while enabling parallel intra-block generation. Our study proceeds in four steps: (i) a \textbf{controlled, compute- and scale-matched comparison} revealing that AR is a more effective backbone for blockwise hybrids than masked diffusion objectives; (ii) a \textbf{scalable conversion recipe, SDAR}, validating that AR models spanning 1.7B to 30B parameters can be adapted into block diffusion models with minimal compute while preserving backbone capabilities; and (iii) a \textbf{systematic characterization of decoding dynamics}, which reveals a virtuous cycle where larger models enable more aggressive parallel decoding, achieving {theoretical speedups over 5$\times$} and {wall-clock speedups of 2.3$\times$} on H200 GPUs in latency-critical regimes; and (iv) an \textbf{investigation of local non-causal modeling capabilities}, showing that SDAR{'}s local bidirectional attention overcomes causal bottlenecks in scientific domains (e.g., chemistry) and enables robust test-time scaling. We release the full model suite, the training framework, and our inference engines for further innovation in non-autoregressive generative paradigms."
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<abstract>Autoregressive (AR) language modeling remains the dominant paradigm due to its dense supervision signal and highly optimized serving infrastructure, but its strictly causal, token-by-token decoding limits parallelism and non-causal modeling. While masked diffusion offers a promising path toward parallel generation, it faces two critical bottlenecks: training inefficiency stemming from sparse masked objectives, and high latency caused by iterative whole-sequence denoising. We present a systematic study of blockwise discrete diffusion, a pragmatic middle ground that preserves AR-compatible serving while enabling parallel intra-block generation. Our study proceeds in four steps: (i) a controlled, compute- and scale-matched comparison revealing that AR is a more effective backbone for blockwise hybrids than masked diffusion objectives; (ii) a scalable conversion recipe, SDAR, validating that AR models spanning 1.7B to 30B parameters can be adapted into block diffusion models with minimal compute while preserving backbone capabilities; and (iii) a systematic characterization of decoding dynamics, which reveals a virtuous cycle where larger models enable more aggressive parallel decoding, achieving theoretical speedups over 5\times and wall-clock speedups of 2.3\times on H200 GPUs in latency-critical regimes; and (iv) an investigation of local non-causal modeling capabilities, showing that SDAR’s local bidirectional attention overcomes causal bottlenecks in scientific domains (e.g., chemistry) and enables robust test-time scaling. We release the full model suite, the training framework, and our inference engines for further innovation in non-autoregressive generative paradigms.</abstract>
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%0 Conference Proceedings
%T SDAR: A Synergistic Diffusion-AutoRegression Paradigm for Scalable Sequence Generation
%A Cheng, Shuang
%A Bian, Yihan
%A Liu, Dawei
%A Jiang, Yuhua
%A Liu, Yihao
%A Zhang, Linfeng
%A Yao, Qian
%A Tian, Zhongbo
%A Wang, Wenhai
%A Guo, Qipeng
%A Chen, Kai
%A Qi, Biqing
%A Zhou, Bowen
%Y Liakata, Maria
%Y Moreira, Viviane P.
%Y Zhang, Jiajun
%Y Jurgens, David
%S Findings of the Association for Computational Linguistics: ACL 2026
%D 2026
%8 July
%I Association for Computational Linguistics
%C San Diego, California, United States
%@ 979-8-89176-395-1
%F cheng-etal-2026-sdar
%X Autoregressive (AR) language modeling remains the dominant paradigm due to its dense supervision signal and highly optimized serving infrastructure, but its strictly causal, token-by-token decoding limits parallelism and non-causal modeling. While masked diffusion offers a promising path toward parallel generation, it faces two critical bottlenecks: training inefficiency stemming from sparse masked objectives, and high latency caused by iterative whole-sequence denoising. We present a systematic study of blockwise discrete diffusion, a pragmatic middle ground that preserves AR-compatible serving while enabling parallel intra-block generation. Our study proceeds in four steps: (i) a controlled, compute- and scale-matched comparison revealing that AR is a more effective backbone for blockwise hybrids than masked diffusion objectives; (ii) a scalable conversion recipe, SDAR, validating that AR models spanning 1.7B to 30B parameters can be adapted into block diffusion models with minimal compute while preserving backbone capabilities; and (iii) a systematic characterization of decoding dynamics, which reveals a virtuous cycle where larger models enable more aggressive parallel decoding, achieving theoretical speedups over 5\times and wall-clock speedups of 2.3\times on H200 GPUs in latency-critical regimes; and (iv) an investigation of local non-causal modeling capabilities, showing that SDAR’s local bidirectional attention overcomes causal bottlenecks in scientific domains (e.g., chemistry) and enables robust test-time scaling. We release the full model suite, the training framework, and our inference engines for further innovation in non-autoregressive generative paradigms.
%U https://aclanthology.org/2026.findings-acl.1110/
%P 22058-22075
Markdown (Informal)
[SDAR: A Synergistic Diffusion-AutoRegression Paradigm for Scalable Sequence Generation](https://aclanthology.org/2026.findings-acl.1110/) (Cheng et al., Findings 2026)
ACL
- Shuang Cheng, Yihan Bian, Dawei Liu, Yuhua Jiang, Yihao Liu, Linfeng Zhang, Qian Yao, Zhongbo Tian, Wenhai Wang, Qipeng Guo, Kai Chen, Biqing Qi, and Bowen Zhou. 2026. SDAR: A Synergistic Diffusion-AutoRegression Paradigm for Scalable Sequence Generation. In Findings of the Association for Computational Linguistics: ACL 2026, pages 22058–22075, San Diego, California, United States. Association for Computational Linguistics.