Unified Lookup-Table Inference with Signed-Digit K/V Caches for Ternary LLMs

Abstract

Ternary LLMs make their weight-dominated projections compact and efficient, but attention remains a mismatch: its K/V cache is created online and is typically processed by a separate higher-precision engine. Compressing this cache alone does not resolve the mismatch. To execute attention with the same lookup-table machinery as ternary projections, values accumulated in one reduction must retain a compatible representation and scale. This requirement also differs for keys and values during causal decoding, because newly generated values may belong to an unfinished cache block. This work develops a unified lookup-table inference approach for ternary LLMs. It stores runtime K/V states as scaled multi-plane signed digits organized around the reduction structure of attention. The resulting digit planes are consumed directly by activation-derived tables, avoiding dense K/V materialization between cache storage and attention computation. The design combines online K/V formation, bounded handling of incomplete value blocks, and a shared multi-stream datapath for Linear projections and attention. A constraint-guided search selects the representation and execution policy for a target quality--efficiency trade-off. Experiments on native and post-training ternary models validate the approach across cache capacity, model quality, and hardware efficiency.