Logic rewriting serves as a robust optimization technique that enhances Boolean networks by substituting small segments with more effective implementations. The incorporation of don’t cares in this process often yields superior optimization results. Nevertheless, the calculation of don’t cares within a Boolean network can be resourceintensive. Therefore, it is crucial to develop effective strategies that mitigate the computational costs associated with don’t cares while simultaneously facilitating the exploration of improved optimization outcomes. To address these challenges, this paper proposes DCLOG, a don’t cares-based logic optimization framework, to efficiently and effectively optimize a given Boolean network. DCLOG leverages a pretrained graph neural network model to filter out cuts without don’t cares and then performs an incremental window simulation to calculate don’t cares for each cut. Experimental results demonstrate the effectiveness and efficiency of DCLOG on large Boolean networks, specifically average size reductions of 15.64 % and 1.44 % while requiring less than 23.84 % and $44.70 \%$ of the average runtime compared with state-of-the-art methods for the majority-inverter graph (MIG), respectively.

Face-to-face (F2F) stacked three-dimensional (3D) IC is a promising alternative for scaling beyond Moore’s Law. In F2F 3D ICs, dies are connected through bonding terminals whose positions can significantly impact routing performance. Further, there exists resource competition among all the 3D nets due to the constrained bonding terminal number. In advanced technology nodes, traditional bonding terminal planning may also introduce legality challenges of bonding terminals, as the metal pitches can be much smaller than the sizes of bonding terminals. Previous works attempt to insert bonding terminals automatically using existing 2D commercial P&R tools and then consider interdie connection legality, but they fail to take the legality and routing performance into account simultaneously. In this article, we provide a novel bonding terminal assignment formulation for effective routing-aware bonding terminal planning. We explore the generalized assignment formulation and provide the routability guidance in our hybrid bonding terminal assignment problem. Our framework, BTAssign , offers a strict legality guarantee and an iterative solution. We provide two versions of the BTAssign framework, BTAssign-WL [ 1 ] and BTAssign-R, which BTAssign-R extends BTAssign-WL [ 1 ] by considering routability. The experiments are conducted on 18 open source designs with various 3D net densities and the most advanced bonding scale. The results reveal that all the testing cases with different partitioning and placement strategies could gain benefits from our BTAssign framework.

Device sizing is a critical yet challenging step in analog and mixed-signal circuit design, requiring careful optimization to meet diverse performance specifications. This challenge is further amplified under process, voltage, and temperature (PVT) variations, which cause circuit behavior to shift across different corners. While reinforcement learning (RL) has shown promise in automating sizing for fixed targets, training a generalized policy that can adapt to a wide range of design specifications under PVT variations requires much more training samples and resources. To address these challenges, we propose a Goal-conditioned RL framework that enables efficient policy training for analog device sizing across PVT corners, with strong generalization capability. To improve sample efficiency, we introduce Pareto-front Dominance Goal Sampling, which constructs an automatic curriculum by sampling goals from the Pareto frontier of previously achieved goals. This strategy is further enhanced by integrating Conservative Hindsight Experience Replay to stabilize training and accelerate convergence. To reduce simulation overhead, our framework incorporates a Skip-on-Fail simulation strategy. Experiments on benchmark circuits demonstrate ∼1.6× improvement in sample efficiency and ∼4.1× improvement in simulation efficiency compared to existing sizing methods. Code and benchmarks are publicly available HERE.

Accurate and swift pre-synthesis timing estimation is crucial for early-stage timing optimization and design space exploration. Recent advances in machine learning have shown significant promise in improving pre-synthesis timing prediction accuracy. However, existing learning-driven methods have overlooked the complexities introduced by the trending hierarchical design paradigm, specifically non-uniform input arrival times (NUIAT). In this paper, we present NUA-Timer, a novel pre-synthesis timing prediction framework designed to address the unique challenges posed by NUIAT in hierarchical timing prediction. To capture the complex long-range timing dependencies under varying NUIAT, NUA-Timer employs a novel bidirectional propagation neural network (BPN), which enables the quantification of timing dependencies using a correlation matrix. Furthermore, we introduce a tailored loss function that leverages post-synthesis critical path labels, thereby aligning the correlation matrix with actual post-synthesis timing dependencies. Comprehensive experiments on both synthetic and open-source designs demonstrate the superiority of our method compared to the state-of-the-art (SOTA) pre-synthesis timing evaluators.

Modern very large-scale integration (VLSI) designs usually consist of modules with various topological structures and functionalities. To better optimize such large and heterogeneous logic networks, it is essential to identify the structural and functional characteristics of its modules, and represent them with appropriate DAG types (such as AIG, MIG, XAG, etc.) for logic optimization. This paper proposes HeLO, a hetero-DAG logic optimization framework empowered by hierarchical clustering and graph learning. HeLO leverages a hierarchical clustering algorithm, which splits the original Boolean network into sub-circuits by considering both topological and functional characteristics. A novel graph neural network model is customized to generate the topological-functional embedding (used for distance calculation in hierarchical clustering) and predict the best-fit DAG type of each sub-circuit. Experimental results demonstrate that HeLO outperforms LSOracle, the SOTA heterogeneous logic optimization framework, in terms of node-depth product (for technology-independent logic optimization) and delay-area product (for technology mapping) by 8.7% and 6.9%, respectively.

As chip fabrication technology advances, the capacitive effects between wires have become increasingly pronounced, making crosstalk-induced incremental delay a serious issue. Traditional static timing analysis involves complex and iterative calculations through timing windows, requiring precise alignment of aggressor and victim nets, along with delay and slew estimations, which significantly increase runtime and licensing costs. In our work, we develop a Graph Neural Network framework to predict crosstalk-affected delays, focusing on the impacts of the coupling effect and overlapping nets. Moreover, we employ a curriculum learning strategy that gradually integrates aggressors with victims, improving model convergence through progressively complex scenarios. Experimental results show that our framework precisely predicts crosstalk-affected delays, matching commercial tools' performance with a fivefold speedup.

Timing closure is considered across the circuit design flow. Generally, the early stage timing optimization can only focus on improving early timing metrics, e.g., rough timing estimation using linear RC model or prerouting path length, since obtaining sign-off performance needs a time-consuming routing flow. However, there is no consistency guarantee between early stage metrics and sign-off timing performance. Therefore, we utilize the power of deep learning techniques to bridge the gap between the early stage analysis and the sign-off analysis. A well-designed deep learning framework guides the adjustment of Steiner points to enable explicit early stage timing optimization. Cooperating with deep Steiner point adjustment, we propose the routing topology reconstruction to accelerate the convergence and hold a reasonable routing topology. Further, we also introduce Steiner point simplification as a post-processing technique to avoid unnecessary routing constraints. This article demonstrates the ability of the learning-assist framework to perform robust and efficient timing optimization in the early stage with comprehensive and convincing experimental results on real-world designs. With Steiner point adjustment alone, TSteinerPt, can help the state-of-the-art open-source router to obtain 11.2% and 7.1% improvement for the sign-off worst-negative slack and total negative slack, respectively. Under the additional joint optimization with routing topology reconstruction and simplification, TSteinerRec can further save 25.9% optimization duration with a better-sign-off performance.

Learning feasible representation from raw gate-level circuits is essential for incorporating machine learning techniques in logic synthesis, physical design, or verification. Existing structure-based learning methods tend to concentrate mainly on the graph topology, often neglecting logic functionality. This oversight frequently results in a failure to capture the underlying semantics, thereby limiting their overall applicability. To address the concern, we propose a novel circuit representation learning framework, FGNN2, that utilizes a contrastive scheme to effectively extract generic functionality knowledge. We construct a comprehensive pretraining dataset through a customized circuit augmentation scheme. We have also developed a novel contrastive loss function to capture the relative functional distance between different circuits, and to generate representations that are invariant to the input order. In addition, we employed a customized graph neural network (GNN) architecture to better align with the above framework. Comprehensive experiments on the multiple complex real-world designs demonstrate that our proposed solution significantly outperforms the state-of-the-art circuit representation learning flows.

Fast and accurate pre-routing timing prediction is crucial in the very-large-scale integration (VLSI) design flow. Existing machine learning (ML)-assisted pre-routing timing evaluators neglect the impact of timing optimization, which may render their approaches impractical in real circuit design flows. To address the challenges posed by timing optimization, we propose PRO-TIME, a pre-routing optimization-aware timing prediction framework that is driven by multimodal learning. Specifically, we propose a novel endpoint embedding framework that integrates both netlist and layout information. A customized graph neural network (GNN) model is used for extracting endpoint-wise netlist information, which is motivated by the delay propagation process. Meanwhile, we apply the U-net model with a masking strategy to extract endpoint-wise layout information. Furthermore, we propose an adaptive layout mask adjustment scheme to boost performance by leveraging the layout information more effectively. Comprehensive experiments on large-scale RISC-V designs with advanced 7-nm technology node demonstrate the superiority of our model compared to the state-of-the-art pre-routing timing evaluators.

Efficient functional verification is crucial in the very-large-scale integration (VLSI) design flow. Existing processor-based emulation systems suffer from low efficiency due to the gap between partitioning and scheduling during compilation. To address the above concern, we propose ParSGCN, a scheduling-friendly emulation compilation flow that considers the objective of scheduling during partitioning. To incorporate the hard-to-perceive look-ahead information about scheduling, we embed it into a net cut probability distribution, which is easier to utilize. We estimate this probability distribution using a tailored variant of graph convolutional network (GCN) that is trained through a customized loss function and a large dataset of real-world compilation solutions. Additionally, we have developed a set of novel techniques to guide the emulation partitioning process using the estimated probability distribution. The proposed method is integrated into an industrial emulator and evaluated on large-scale designs with up to over 100 million cells. Comprehensive experimental results demonstrate the effectiveness of ParSGCN, showcasing an average improvement of 16.38%, 26.04%, and 19.52% in the best, worst, and median solution quality, respectively, based on 50 runs.

In the domain of very-large-scale integration (VLSI) design, the accuracy of prerouting timing prediction is of paramount importance for ensuring the performance and reliability of integrated circuits. Traditional methods based on machine learning necessitate the availability of extensive and high-quality datasets. However, this requirement poses significant challenges for advanced technology nodes due to the laborious and time-intensive nature of data preparation. To address this critical issue, we introduce a novel transfer learning framework that leverages data from preceding technology nodes to facilitate learning and prediction on the target node. Our methodology commences with the disentanglement and alignment of timing path features across different nodes, ensuring the preservation and effective translation of intrinsic timing path properties. Subsequently, we employ a Bayesian-based model to predict the arrival times of individual timing paths. This model is particularly adept at managing the high-variability inherent in arrival times and exhibits strong generalization capabilities to novel design scenarios. Moreover, we propose a new algorithm to reweight the preceding node data during training by estimating their transferability through the cell type distribution. We validate the efficacy of our proposed framework through comprehensive experimental evaluations, demonstrating successful transfer learning from 130 or 45 to 7-nm technology nodes. The results underscore the potential of our approach to significantly mitigate the dependency on extensive data preparation while maintaining high accuracy in timing prediction for cutting-edge VLSI designs.

In VLSI design, accurate pre-routing timing prediction is paramount. Traditional machine learning-based methods require extensive data, posing challenges for advanced technology nodes due to the time-consuming data preparation. To mitigate this issue, we propose a novel transfer learning framework that uses data from previous nodes for learning on the target node. Our method initially disentangles and aligns timing path features across different nodes, then predicts each path's arrival time employing a Bayesian-based model capable of handling highly variable arrival time and generalizing to new designs. Experimental results on transfer learning from 130nm to 7nm nodes validate our method's effectiveness.

Face-to-face (F2F) stacked 3D IC is a promising alternative for scaling beyond Moore's Law. In F2F 3D ICs, dies are connected through bonding terminals whose positions can significantly impact routing performance. Further, there exists resource competition among all the 3D nets due to the constrained bonding terminal number. In advanced technology nodes, such 3D integration may also introduce legality challenges of bonding terminals, as the metal pitches can be much smaller than the sizes of bonding terminals. Previous works attempt to insert bonding terminals automatically using existing 2D commercial P&R tools and then consider inter-die connection legality, but they fail to take the legality and routing performance into account simultaneously. In this paper, we explore the formulation of the generalized assignment in the hybrid bonding terminal assignment problem. Our framework, BTAssign, offers a strict legality guarantee and an iterative solution. The experiments are conducted on 18 open-source designs with various 3D net densities and the most advanced bonding scale. The results reveal that BTAssign can achieve improvements in routed wirelength under all testing conditions from 1.0% to 5.0% with a tolerable runtime overhead.

Abstract Within the electronic design automation (EDA) domain, artificial intelligence (AI)-driven solutions have emerged as formidable tools, yet they typically augment rather than redefine existing methodologies. These solutions often repurpose deep learning models from other domains, such as vision, text, and graph analytics, applying them to circuit design without tailoring to the unique complexities of electronic circuits. Such an “AI4EDA” approach falls short of achieving a holistic design synthesis and understanding, overlooking the intricate interplay of electrical, logical, and physical facets of circuit data. This study argues for a paradigm shift from AI4EDA towards AI-rooted EDA from the ground up, integrating AI at the core of the design process. Pivotal to this vision is the development of a multimodal circuit representation learning technique, poised to provide a comprehensive understanding by harmonizing and extracting insights from varied data sources, such as functional specifications, register-transfer level (RTL) designs, circuit netlists, and physical layouts. We champion the creation of large circuit models (LCMs) that are inherently multimodal, crafted to decode and express the rich semantics and structures of circuit data, thus fostering more resilient, efficient, and inventive design methodologies. Embracing this AI-rooted philosophy, we foresee a trajectory that transcends the current innovation plateau in EDA, igniting a profound “shift-left” in electronic design methodology. The envisioned advancements herald not just an evolution of existing EDA tools but a revolution, giving rise to novel instruments of design-tools that promise to radically enhance design productivity and inaugurate a new epoch where the optimization of circuit performance, power, and area (PPA) is achieved not incrementally, but through leaps that redefine the benchmarks of electronic systems’ capabilities.

Timing closure is crucial across the circuit design flow. Since obtaining sign-off performance needs a time-consuming routing flow, all the previous early-stage timing optimization works only focus on improving early timing metrics, e.g., rough timing estimation using linear RC model or pre-routing path-length. However, there is no consistency guarantee between early-stage metrics and sign-off timing performance. To enable explicit early-stage optimization on the sign-off timing metrics, we propose a novel timing optimization framework, TSteiner. This paper demonstrates the ability of the learning framework to perform robust and efficient timing optimization in the early stage with comprehensive and convincing experimental results on real-world designs.

Fast and accurate pre-routing timing prediction is crucial in the very-large-scale integration (VLSI) design flow. Existing machine learning (ML)-assisted pre-routing timing evaluators neglect the impact of timing optimization, which may render their approaches impractical in real circuit design flows. To model the impact of timing optimization, we propose an endpoint embedding framework that integrates netlist-layout information via multimodal fusion. An end-to-end flow is further developed for pre-routing restructure-tolerant prediction on global timing metrics. Comprehensive experiments on large-scale RISC-V designs with advanced 7-nm technology node demonstrate the superiority of our model compared to the SOTA pre-routing timing evaluators.

Arithmetic block identification in gate-level netlists plays an essential role for various purposes, including malicious logic detection, functional verification, or macro-block optimization. However, current methods usually suffer from either low performance or poor scalability. To address the issue, we come up with a novel framework based on graph learning and network flow analysis, that extracts desired logic components from a complete circuit netlist. We design a novel asynchronous bidirectional graph neural network (ABGNN) dedicated to representation learning on directed acyclic graphs. In addition, we develop a convex cost network-flow-based datapath extraction approach to match the predicted block inputs with predicted block outputs. Experimental results on open-source RISC-V CPU designs demonstrate that our proposed solution significantly outperforms several state-of-the-art arithmetic block identification flows.

Learning feasible representation from raw gate-level netlists is essential for incorporating machine learning techniques in logic synthesis, physical design, or verification. Existing message-passing-based graph learning methodologies focus merely on graph topology while overlooking gate functionality, which often fails to capture underlying semantic, thus limiting their generalizability. To address the concern, we propose a novel netlist representation learning framework that utilizes a contrastive scheme to acquire generic functional knowledge from netlists effectively. We also propose a customized graph neural network (GNN) architecture that learns a set of independent aggregators to better cooperate with the above framework. Comprehensive experiments on multiple complex real-world designs demonstrate that our proposed solution significantly outperforms state-of-the-art netlist feature learning flows.

Arithmetic block identification in gate-level netlist is an essential procedure for malicious logic detection, functional verification, or macro-block optimization. We argue that existing methods suffer either scalability or performance issues. To address the problem, we propose a graph learning-based solution that promises to extract desired logic components from a complete design netlist. We further design a novel asynchronous bidirectional graph neural network (ABGNN) dedicated to representation learning on directed acyclic graphs. Experimental results on open-source RISC-V CPU designs demonstrate that our proposed solution significantly outperforms several state-of-the-art arithmetic block identification flows.