Core Concepts
Basilisk, an optimized application-specific integrated circuit (ASIC) implementation and design flow, achieves competitive performance by enhancing open-source electronic design automation (EDA) tools and the physical design of the Iguana RISC-V SoC.
Abstract
The paper introduces Basilisk, an optimized ASIC implementation and design flow based on the open-source Iguana RISC-V system-on-chip (SoC). The authors present several improvements to the synthesis and physical design stages to enhance the quality of results (QoR) compared to the baseline Iguana design.
Synthesis Improvements:
- Optimized part-select operations by replacing shift-based implementations with more efficient block-multiplexer trees.
- Overhauled the ABC logic optimization scripts to leverage recent research for better QoR.
- Integrated adders into the Booth multiplier's CSA tree to create fused multiply-add (FMA) units, reducing the critical path.
Physical Design Improvements:
- Redesigned the power grid by reducing the width and increasing the count of power stripes on the top metal layer to ease routing congestion.
- Tuned the hyper-parameters of the routability-driven global placement engine in OpenROAD to improve the placement of dense blocks and achieve a routable design without design rule check (DRC) violations.
The optimized Basilisk design achieves a 2.3x improvement in operating frequency (77 MHz) compared to the baseline Iguana design (33 MHz), while reducing the logic area from 1.8 MGE to 1.1 MGE. The core utilization is also increased from 50% to 55%.
The authors collaborated with EDA tool developers and domain experts to identify and address issues in the open-source synthesis and place-and-route tools, exemplifying a synergistic effort towards competitive open-source EDA tools for research and industry applications.
Stats
Iguana: 33 MHz, 1.8 MGE, 182 logic levels
Basilisk: 77 MHz, 1.1 MGE, 51 logic levels
Quotes
"Basilisk exemplifies a synergistic effort towards competitive open-source electronic design automation (EDA) tools for research and industry applications."