Silicon compiler

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A silicon compiler is a specialized electronic design automation (EDA) tool that automates the process of creating an integrated circuit (IC) design from a high-level behavioral description. The tool takes a specification, often written in a high-level programming language like C++ or a specialized domain-specific language (DSL), and generates a set of layout files (such as GDSII) that can be sent to a semiconductor foundry for manufacturing. [1]

Contents

The primary goal of a silicon compiler is to raise the level of design abstraction, allowing engineers to focus on the desired functionality of a circuit rather than the low-level details of its implementation. This process, sometimes called hardware compilation, significantly increases design productivity, similar to how modern software compilers freed programmers from writing assembly code. [2]

History

The concept of the silicon compiler was first formally described in 1979 by David L. Johannsen in his Ph.D. thesis at the Caltech, under the guidance of his adviser, Carver Mead. [3] This work led to the founding of Silicon Compilers Inc. (SCI) in 1981 by Johannsen, Mead, and Edmund K. Cheng.

One of the first major successes of this approach was the design of an Ethernet Data Link Controller chip in 1982. The project went from specification to tape-out in just five months, a significant acceleration of the design cycle at the time. [4] Shortly after, in 1983–84, the SCI team designed the data-path chip for the DEC MicroVAX in seven months. The chip contained 37,000 transistors, a level of complexity that typically required around three years to design manually. [5]

Compilation process

Silicon compilation transforms a high-level description into a physical layout through several major stages.

High-level synthesis

The process begins with a behavioral description of the hardware, often written in a language like C, C++, or SystemC. This stage, known as High-level synthesis (HLS), translates the high-level code into a structural representation, typically a register-transfer level (RTL) description. HLS allows designers to explore different architectures quickly by modifying the source code, rather than manually re-writing RTL code. [2]

Intermediate representation

To bridge the gap between high-level programming languages and low-level hardware details, compilers often use an intermediate representation (IR). An IR provides a standardized format that allows for modular, hardware-focused optimizations. Modern open-source projects have introduced specialized IRs to improve the compilation process.

Logic synthesis

The logic synthesis stage takes the RTL description and converts it into a gate-level netlist. This netlist is a detailed map of simple logic gates (like AND, OR, NOT) and the connections between them that implement the functionality specified in the RTL.

Physical design

Physical design is the final stage, where the abstract gate-level netlist is converted into a geometric layout. This layout specifies the exact location of every component and wire on the final chip. This stage includes several complex steps:

Design paradigms and optimization

Intelligent compilation

Early silicon compilers evolved to include more sophisticated design exploration capabilities. The concept of “intelligent compilation” introduced a design paradigm that separates decision-making from the synthesis process. In this model, designers use a “knobs and gauges” approach.

This allows a human designer or an expert system to explore trade-offs by adjusting the knobs and observing the effect on the gauges, without needing to understand the low-level details of the synthesis process. [1]

Role of AI and machine learning

Modern silicon compilers increasingly incorporate artificial intelligence (AI) and machine learning (ML) to manage the immense complexity of chip design. These techniques are used to automate and optimize various stages of the compilation process, particularly physical design. For example, deep reinforcement learning has been used to solve chip floorplanning and placement problems, where an AI agent learns through experience to arrange components on a chip more effectively than many human experts and traditional automated tools. [11] [12]

Comparison with manual RTL design

The use of silicon compilers presents a fundamental trade-off between design productivity and the final quality of the hardware.

Advantages:

Disadvantages:

Open source movement

In recent years, the field of silicon compilation has seen a significant push towards open-source tools and collaborative development, aiming to democratize chip design and accelerate innovation.

See also

References

  1. 1 2 Pangrle, B.M.; Gajski, D.D. (November 1987). "Design Tools for Intelligent Silicon Compilation". IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems. 6 (6): 1098–1112. doi:10.1109/TCAD.1987.1270350. ISSN   1937-4151.
  2. 1 2 3 4 Lahti, Sakari; Sjövall, Panu; Vanne, Jarno; Hämäläinen, Timo D. (May 2019). "Are We There Yet? A Study on the State of High-Level Synthesis". IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems. 38 (5): 898–911. doi:10.1109/TCAD.2018.2834439. ISSN   1937-4151.
  3. Johannsen, Dave (1998). "Bristle blocks: A silicon compiler". Papers on Twenty-five years of electronic design automation. pp. 195–196. doi:10.1145/62882.62903. ISBN   0-89791-267-5.
  4. Edmund K. Cheng, "The Design of an Ethernet Data Link Controller Chip", 26th IEEE Computer Society International Conference, COMPCON Spring 83, San Francisco, Feb 25-Mar 3, 1983, pp. 157–160.
  5. "Silicon compiler lets systems engineers design their own VLSI chips", article by Stephen C. Johnson of Silicon Compilers Inc. in "Electronic Design" magazine, October 4, 1984, pp. 167–181.
  6. "CIRCT". circt.llvm.org. Retrieved 2025-06-14.
  7. 1 2 Lattner, Chris; Lenharth, Andrew (November 17, 2021). CIRCT: Lifting hardware development out of the 20th century (PDF). LLVM Developer Meeting.
  8. Nigam, Rachit; Thomas, Samuel; Li, Zhijing; Sampson, Adrian (2021-04-17). "A compiler infrastructure for accelerator generators". Proceedings of the 26th ACM International Conference on Architectural Support for Programming Languages and Operating Systems. ASPLOS '21. New York, NY, USA: Association for Computing Machinery. pp. 804–817. arXiv: 2102.09713 . doi:10.1145/3445814.3446712. ISBN   978-1-4503-8317-2.
  9. Singh, Rajendra Bahadur; Baghel, Anurag Singh; Agarwal, Ayush (March 2016). "A review on VLSI floorplanning optimization using metaheuristic algorithms". 2016 International Conference on Electrical, Electronics, and Optimization Techniques (ICEEOT). pp. 4198–4202. doi:10.1109/ICEEOT.2016.7755508. ISBN   978-1-4673-9939-5.
  10. Posser, Gracieli; Young, Evangeline F.Y.; Held, Stephan; Li, Yih-Lang; Pan, David Z. (2022-04-13). "Challenges and Approaches in VLSI Routing". Proceedings of the 2022 International Symposium on Physical Design. ISPD '22. New York, NY, USA: Association for Computing Machinery. pp. 185–192. doi:10.1145/3505170.3511477. ISBN   978-1-4503-9210-5.
  11. Malhotra, Archika; Singh, Aditi (March 2022). "Implementation of AI in the field of VLSI: A Review". 2022 Second International Conference on Power, Control and Computing Technologies (ICPC2T). pp. 1–5. doi:10.1109/ICPC2T53885.2022.9776845. ISBN   978-1-6654-5858-0.
  12. Wei, Qingye (June 2025). "A Review on Meta-Heuristic and Reinforcement Learning for VLSI Floor Planning". International Core Journal of Engineering. 11 (6): 462–470. doi:10.6919/ICJE.202506_11(6).0050.
  13. Demme, John; Schuiki, Fabian; Urbach, Mike; Young, Andrew (2021). Charting CIRCT: The Present and Future Landscape (PDF). LLVM Developer Meeting.
  14. "Welcome to SiliconCompiler's Documentation! — SiliconCompiler v0.33.2 Manual". docs.siliconcompiler.com. Retrieved 2025-06-14.