Tinghuan Chen

Physical design flow through associated electronic design automation (EDA) tools plays an imperative role in the advanced integrated circuit design. Mostly, the parameters fed into physical design tools are mainly manually picked based on the domain knowledge of the experts. Nevertheless, owing to the ever-shrinking scaling down of technology nodes and the complexity of the design space spanned by combinations of the parameters, even coupled with the time-consuming simulation process, such manual explorations for parameter configurations of physical design tools have become extremely laborious. There exist a few works in the field of design flow parameter tuning. However, very limited prior arts explore the complex correlations among multiple quality-of-result (QoR) metrics of interest (e.g., delay, power, and area) and explicitly optimize these goals simultaneously. To overcome these weaknesses and seek effective parameter settings of physical design tools, in this article, we propose a multi-objective Bayesian optimization (BO) framework with a multi-task Gaussian model as the surrogate model. An information gain-based acquisition function is adopted to sequentially choose candidates for tool simulation to efficiently approximate the Pareto-optimal parameter configurations. The experimental results on three industrial benchmarks under the 7-nm technology node demonstrate the superiority of the proposed framework compared to the cutting-edge works.

High-level synthesis (HLS) tools have gained great attention in recent years because it emancipates engineers from the complicated and heavy hardware description language writing and facilitates the implementations of modern applications (e.g., deep learning models) on Field-programmable Gate Array (FPGA) , by using high-level languages and HLS directives. However, finding good HLS directives is challenging, due to the time-consuming design processes, the balances among different design objectives, and the diverse fidelities (accuracies of data) of the performance values between the consecutive FPGA design stages. To find good HLS directives, a novel automatic optimization algorithm is proposed to explore the Pareto designs of the multiple objectives while making full use of the data with different fidelities from different FPGA design stages. Firstly, a non-linear Gaussian process (GP) is proposed to model the relationships among the different FPGA design stages. Secondly, for the first time, the GP model is enhanced as correlated GP (CGP) by considering the correlations between the multiple design objectives, to find better Pareto designs. Furthermore, we extend our model to be a deep version deep CGP (DCGP) by using the deep neural network to improve the kernel functions in Gaussian process models, to improve the characterization capability of the models, and learn better feature representations. We test our design method on some public benchmarks (including general matrix multiplication and sparse matrix-vector multiplication) and deep learning-based object detection model iSmart2 on FPGA. Experimental results show that our methods outperform the baselines significantly and facilitate the deep learning designs on FPGA.

High-level synthesis (HLS) tools have gained great attention in recent years because it emancipates engineers from the complicated and heavy hardware description language writing, by using high-level languages and HLS directives. However, previous works seem powerless, due to the time-consuming design processes, the contradictions among design objectives, and the accuracy difference between the three stages (fidelities). To find good HLS directives, in this paper, a novel correlated multi-objective non-linear optimization algorithm is proposed to explore the Pareto solutions while making full use of data from different fidelities. A non-linear Gaussian process is proposed to model relationships among the analysis reports from different fidelities for the same objective. For the first time, correlated multivariate Gaussian process models are introduced into this domain to characterize the complex relationships of multiple objectives in each design fidelity. A tree-based method is proposed to erase invalid solutions and obviously non-optimal solutions. Experimental results show that our non-linear and pioneering correlated models can approximate the Pareto-frontier of the directive design space in a shorter time with much better performance and good stability, compared with the state-of-the-art.