Domino: Decoupling Causal Modeling from Autoregressive Drafting in Speculative Decoding

Jianuo Huang, Yaojie Zhang, Qituan Zhang, Hao Lin, Hanlin xu, Linfeng Zhang


Abstract
Speculative decoding accelerates LLM inference by drafting multiple tokens and verifying them in parallel with the target model. However, its practical speedup is constrained by the trade-off between draft quality and drafting cost: autoregressive drafters model causal dependencies among draft tokens but incur sequential overhead, while parallel drafters reduce drafting cost but weaken intra-block dependency modeling. In this paper, we propose Domino, a speculative decoding framework that decouples causal dependency modeling from expensive autoregressive draft execution. Domino first uses a parallel draft backbone to produce preliminary draft distributions for the entire block, and then applies a lightweight Domino head to refine them with prefix-dependent causal information. To stabilize teacher-forced causal encoding, we further introduce a base-anchored training curriculum that first strengthens the parallel backbone and then gradually shifts optimization toward the causally corrected final distribution. Experiments on Qwen3 models show that Domino achieves up to (5.49×) end-to-end speedup under the Transformers backend and up to (5.8×) throughput speedup under SGLang serving. Code and checkpoints are provided in the supplementary material.
Anthology ID:
2026.emnlp-main.1015
Volume:
Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing
Month:
October
Year:
2026
Address:
Budapest, Hungary
Editors:
Hung-Yi Lee, Sunipa Dev, Jessy Li, Desmond Elliott
Venue:
EMNLP
SIG:
SIGDAT
Publisher:
Association for Computational Linguistics
Note:
Pages:
23346–23356
Language:
URL:
https://aclanthology.org/2026.emnlp-main.1015/
DOI:
Bibkey:
Cite (ACL):
Jianuo Huang, Yaojie Zhang, Qituan Zhang, Hao Lin, Hanlin xu, and Linfeng Zhang. 2026. Domino: Decoupling Causal Modeling from Autoregressive Drafting in Speculative Decoding. In Proceedings of the 2026 Conference on Empirical Methods in Natural Language Processing, pages 23346–23356, Budapest, Hungary. Association for Computational Linguistics.
Cite (Informal):
Domino: Decoupling Causal Modeling from Autoregressive Drafting in Speculative Decoding (Huang et al., EMNLP 2026)
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PDF:
https://aclanthology.org/2026.emnlp-main.1015.pdf