The security closure of integrated circuits (ICs) is an emerging area of research within the very large scale integration (VLSI) community. Malicious third parties, referred to as “attackers,” can employ various techniques to leak, alter, or manipulate the logic of a circuit. When targeting a completed layout, their primary goal is often the insertion of hardware trojans. In this work, we present algorithms that strengthen placement solutions against hardware trojan attacks. While state-of-the-art methods rely on exhaustive placement algorithms, we propose a clustering-based placement approach that reduces the number of moved cells by up to 17%. Additionally, we introduce a cell movement heuristic aimed at preventing increases in wirelength. Our methods reduce vulnerable placement sites by up to 78% while maintaining minimal impact on design performance. Compared to other approaches, our solution decreases the amount of moved cells to an average of 8%, mitigating the impact on wirelength to an average of 0.5%.

The OpenROAD project is an ambitious initiative seeking to develop an automated, open-source RTL-to-GDSII flow. To build its complex toolset, OpenROAD brings together a team of industry experts, veteran scholars, and enthusiastic students from different schools and different countries. This paper first presents our path to becoming OpenROAD contributors, highlighting the nature of the OpenROAD project, the recruitment process, and the necessary logistics. We then summarize the contributions of the Brazilian team to the OpenROAD project; these comprise the development of five tools and more than 10K lines of released code, along with authorship or co-authorship of two publications in the research literature. We also summarize our experiences from working in a large software project: (i) working environment and relationship with people from around the world; (ii) task management and short turnaround times; (iii) continuous integration and testing; etc. Finally, we highlight the challenges of "refurbishing" academic research codes for use in the design of production ICs.

In advanced technology nodes, IC implementation faces increasing design complexity as well as ever-more demanding design schedule requirements. This raises the need for new decomposition approaches that can help reduce problem complexity, in conjunction with new predictive methodologies that can help avoid bottlenecks and loops in the physical implementation flow. Notably, with modern design methodologies it would be very valuable to better predict final placement of the gate-level netlist: this would enable more accurate early assessment of performance, congestion and floorplan viability in the SOC floorplanning/RTL planning stages of design. In this work, we study a new criterion for the classic challenge of VLSI netlist clustering: how well netlist clusters "stay together" through final implementation. We propose use of several evaluators of this criterion. We also explore the use of modularity-driven clustering to identify natural clusters in a given graph without the tuning of parameters and size balance constraints typically required by VLSI CAD partitioning methods. We find that the netlist hypergraph-to-graph mapping can significantly affect quality of results, and we experimentally identify an effective recipe for weighting that also comprehends topological proximity to I/Os. Further, we empirically demonstrate that modularity-based clustering achieves better correlation to actual netlist placements than traditional VLSI CAD methods (our method is also 4X faster than use of hMetis for our largest testcases). Finally, we show a potential flow with fast "blob placement" of clusters to evaluate netlist and floorplan viability in early design stages; this flow can predict gate-level placement of 370K cells in 200 seconds on a single core.

We describe the planned Alpha release of OpenROAD, an open-source end-to-end silicon compiler. OpenROAD will help realize the goal of "democratization of hardware design", by reducing cost, expertise, schedule and risk barriers that confront system designers today. The development of open-source, self-driving design tools is in and of itself a "moon shot" with numerous technical and cultural challenges. The open-source flow incorporates a compatible open-source set of tools that span logic synthesis, floorplanning, placement, clock tree synthesis, global routing and detailed routing. The flow also incorporates analysis and support tools for static timing analysis, parasitic extraction, power integrity analysis, and cloud deployment. We also note several observed challenges, or "lessons learned", with respect to development of open-source EDA tools and flows.

Due to the advanced stage of development on EDA science, it has been increasingly difficult to implement realistic software infrastructures in academia so that new problems and solutions are tested in a meaningful and consistent way. In this paper we present Rsyn, a free and open-source C++ framework for physical synthesis research and development comprising an elegant netlist data model, analysis tools (e.g. timing analysis, congestion), optimization methods (e.g. placement, sizing, buffering) and a graphical user interface. It is designed to be very modular and incrementally extensible. New components can be easily integrated making Rsyn increasingly valuable as a framework to leverage research in physical design. Standard and third party components can be mixed together via code or script language to create a comprehensive design flow, which can be used to better assess the quality of results of the research being conducted. The netlist data model uses the new features of C++11 providing a simple but efficient way to traverse and modify the netlist. Attributes can be seamlessly added to objects and a notification system alerts components about changes in the netlist. The flexibility of the netlist inspired the name Rsyn, which comes from the word resynthesis. Rsyn is created to allow researchers to focus on what is really important to their research spending less time on the infrastructure development. Allowing the sharing and reusability of common components is also one of the main contributions of the Rsyn framework. In this paper, the key concepts of Rsyn are presented. Examples of use are drawn, the important standard components (e.g. physical layer, timing) are detailed and some case studies based on recent Electronic Design Automation (EDA) contests are analyzed. Rsyn is available at http://rsyn.design.

As the interconnections dominate the circuit delay in nanometer technologies, placement plays a major role to achieve timing closure since it is a main step that defines the interconnection lengths. In initial stages of the physical design flow, the placement goal is to reduce the total wirelength, however total wirelength minimization only roughly addresses timing. A timing-driven placement incorporates timing information to remove or alleviate timing violations. In this work, we present an incremental timing-driven placement flow to further optimize timing violations via single-cell movements.For late violations, we developed techniques to reduce the load capacitance on critical nets and to obtain load capacitance balancing using drive strength. For early violations, we present techniques that rely on clock skew optimization, register swap and interconnection increase. Our flow is experimentally evaluated using the ICCAD 2015 Incremental Timing-Driven Contest infrastructure. Experimental results show that our flow can significantly reduce timing violations. On average, for long maximum displacement, the quality of results is improved by 67.8% with late WNS and TNS being improved by 2.31% and 10.84%, respectively, early WNS and TNS improved by 68.92% and 76.42%, respectively and congestion metric ABU improved by 74.9% compared to the 1st place in the contest. The impact on Steiner tree wirelength is less than 2.5%.

In this work, we present a flow for the Incremental Timing-Driven Placement problem. Given a legal placement, the aim is to reduce the circuit's timing violations without changing significantly the cell density, subject to a maximum displacement constraint. Our flow consists of two core steps: useful clock skew optimization and critical path fine tuning. During useful clock skew optimization, sequential cells are replaced, seeking to minimize clock skew. After that, a quadratic formulation is used to further reduce critical path delays. An incremental legalization tool is also presented, which supports the methods developed in this work. Our Incremental Timing-Driven Placement flow can achieve, on average, 0.3%, 26.2%, 8.7% and 23.7% of the normalized quality score improvement compared to state-of-the-art algorithms.