arXiv subjects

Jiaping Tang

Publications and source records attributed to Jiaping Tang.

5 recordsLinked to original sources

arXiv2026

ARMOR: Accelerating RTL Simulation by Mitigating the Front-End Bottleneck Using Node Compression

RTL simulation is indispensable in chip design. High-performance simulators typically lower each node in the RTL graph into an instruction sequence. Although this per-node lowering enables aggressive compiler optimizations, it dramatically increases the code footprint, severely exceeding instruction cache capacity and causing front-end bottlenecks. Our profiling reveals that over 50% of pipeline stalls are caused by the CPU front-end, becoming a key performance bottleneck in state-of-the-art RTL simulators. However, reaping the optimization benefits of fully unrolling the RTL graph while simultaneously reducing the code footprint to mitigate front-end bottlenecks remains highly challenging. In this paper, we propose ARMOR, an efficient RTL simulator designed to alleviate the front-end bottleneck through node compression. The key idea is to exploit the data parallelism exposed by the unrolling RTL graph and the insufficient bit-space utilization revealed by per-node lowering, leveraging bit-level data parallelism to compress multiple nodes simultaneously, so that a single instruction sequence can serve multiple nodes instead of one per node. To achieve profitable node compression, we first propose a module-aware isomorphic subgraph identification method that leverages structural isomorphism across module instances to systematically identify compression opportunities at the subgraph level. We then propose an alignment-aware dense packing strategy that groups nodes into packs according to dataflow dependencies while preserving data reuse, complemented by greedy merging strategies to enhance bit-space utilization. Finally, we implement a unified bit-level parallelism scheme to support bit-level parallel execution of compressed nodes. Experimental results show that ARMOR achieves 1.6x speedup on CPU designs and 2.7x speedup on AI accelerators compared to state-of-the-art simulators.

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arXiv2026

Pecker: Bug Localization Framework for Sequential Designs via Causal Chain Reconstruction

Debugging represents a time-consuming and labor-intensive task in hardware design, with bug localization constituting a substantial portion of this process. While spectrum-based bug localization techniques have achieved remarkable success in software domains and shown promise for hardware description languages, their effectiveness severely degrades in sequential designs. Unlike software programs, hardware designs exhibit intrinsic temporal characteristics that create fundamental challenges: timing misalignment between bug activation and observation, and progressive error propagation through state elements that obscures the root cause. To address these limitations, we propose Pecker, a novel bug localization framework that reconstructs the broken causal chain in sequential designs. Our approach introduces two key innovations: temporal backtracking using Estimated Minimal Propagation Cycles to identify potential activation cycles, strategic trace pruning to eliminate state pollution effects. We evaluate Pecker on comprehensive benchmarks comprising both combinational and sequential circuits. Experimental results demonstrate that Pecker effectively localizes 51%/80%/85% bugs within Top-1/3/5 ranks respectively, significantly outperforming state-of-the-art techniques. Notably, Pecker maintains robust performance across circuit complexities while existing methods exhibit severe degradation on sequential designs.

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arXiv2025

RIROS: A Parallel RTL Fault SImulation FRamework with TwO-Dimensional Parallelism and Unified Schedule

With the rapid development of safety-critical applications such as autonomous driving and embodied intelligence, the functional safety of the corresponding electronic chips becomes more critical. Ensuring chip functional safety requires performing a large number of time-consuming RTL fault simulations during the design phase, significantly increasing the verification cycle. To meet time-to-market demands while ensuring thorough chip verification, parallel acceleration of RTL fault simulation is necessary. Due to the dynamic nature of fault propagation paths and varying fault propagation capabilities, task loads in RTL fault simulation are highly imbalanced, making traditional singledimension parallel methods, such as structural-level parallelism, ineffective. Through an analysis of fault propagation paths and task loads, we identify two types of tasks in RTL fault simulation: tasks that are few in number but high in load, and tasks that are numerous but low in load. Based on this insight, we propose a two-dimensional parallel approach that combines structurallevel and fault-level parallelism to minimize bubbles in RTL fault simulation. Structural-level parallelism combining with workstealing mechanism is used to handle the numerous low-load tasks, while fault-level parallelism is applied to split the high-load tasks. Besides, we deviate from the traditional serial execution model of computation and global synchronization in RTL simulation by proposing a unified computation/global synchronization scheduling approach, which further eliminates bubbles. Finally, we implemented a parallel RTL fault simulation framework, RIROS. Experimental results show a performance improvement of 7.0 times and 11.0 times compared to the state-of-the-art RTL fault simulation and a commercial tool.

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arXiv2025

Extend IVerilog to Support Batch RTL Fault Simulation

The advancement of functional safety has made RTL-level fault simulation increasingly important to achieve iterative efficiency in the early stages of design and to ensure compliance with functional safety standards. In this paper, we extend IVerilog to support batch RTL fault simulation and integrate the event-driven algorithm and the concurrent fault simulation algorithm. Comparative experiments with a state-of-the-art commercial simulator and an open-source RTL fault simulator demonstrate that our simulator achieves a performance improvement of 2.2$\times$ and 3.4$\times$, respectively.

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arXiv2025

ERASER: Efficient RTL FAult Simulation Framework with Trimmed Execution Redundancy

As intelligent computing devices increasingly integrate into human life, ensuring the functional safety of the corresponding electronic chips becomes more critical. A key metric for functional safety is achieving a sufficient fault coverage. To meet this requirement, extensive time-consuming fault simulation of the RTL code is necessary during the chip design phase.The main overhead in RTL fault simulation comes from simulating behavioral nodes (always blocks). Due to the limited fault propagation capacity, fault simulation results often match the good simulation results for many behavioral nodes. A key strategy for accelerating RTL fault simulation is the identification and elimination of redundant simulations. Existing methods detect redundant executions by examining whether the fault inputs to each RTL node are consistent with the good inputs. However, we observe that this input comparison mechanism overlooks a significant amount of implicit redundant execution: although the fault inputs differ from the good inputs, the node's execution results remain unchanged. Our experiments reveal that this overlooked redundant execution constitutes nearly half of the total execution overhead of behavioral nodes, becoming a significant bottleneck in current RTL fault simulation. The underlying reason for this overlooked redundancy is that, in these cases, the true execution paths within the behavioral nodes are not affected by the changes in input values. In this work, we propose a behavior-level redundancy detection algorithm that focuses on the true execution paths. Building on the elimination of redundant executions, we further developed an efficient RTL fault simulation framework, Eraser.Experimental results show that compared to commercial tools, under the same fault coverage, our framework achieves a 3.9 $\times$ improvement in simulation performance on average.

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