Propagating constants past software to hardware peripherals in fixed-application embedded systems

ABSTRACT

Many embedded systems include a microprocessor that executes a single program for the lifetime of the system. These programs often contain constants used to initialize control registers in peripheral hardware components. Now that peripherals are often purchased in intellectual property (core) form and synthesized along with the microprocessor onto a single chip, new optimization opportunities exist. We introduce one such optimization, which involves propagating the initialization constants past the microprocessor to the peripheral, such that synthesis can further propagate the constants inside the peripheral core. While constant propagation in synthesis tools is commonly done, this work illustrates the benefits of recognizing initialization constants from the software as really being constants for hardware. We describe results that demonstrate 23 times reductions in peripheral size, and 10.30% savings in power, on several common peripheral examples.

REFERENCES

• 1: Alfred V. Aho , Ravi Sethi , Jeffrey D. Ullman, Compilers: principles, techniques, and tools, Addison-Wesley Longman Publishing Co., Inc., Boston, MA, 1986
• 2: Escalade Corporation, http://www.escalade.com/.
• 3: Rajesh K. Gupta , Yervant Zorian, Introducing Core-Based System Design, IEEE Design & Test, v.14 n.4, p.15-25, October 1997 [doi>10.1109/54.632877 ]
• 4: Inventra core library, Mentor Graphics, http://www.mentor.com/inventra/.
• 5: Platform Express. Mentor Graphics, http://www.mentor.com/soc/platform_ex/.
• 6: Greg Stitt , Frank Vahid , Tony Givargis , Roman Lysecky, A first-step towards an architecture tuning methodology for low power, Proceedings of the 2000 international conference on Compilers, architecture, and synthesis for embedded systems, p.187-192, November 17-19, 2000, San Jose, California, United States [doi>10.1145/354880.354906]
• 7: The UCR Dalton project: http://www.cs.ucr.edu/-dalton.
• 8: Frank Vahid , Tony Givargis, Platform Tuning for Embedded Systems Design, Computer, v.34 n.3, p.112-114, March 2001 [doi>10.1109/2.901171 ]
• 9: Virtual Socket Interface Association, Architecture Document, http://www.vsi.org, 1997.
• 10: Mark N. Wegman , F. Kenneth Zadeck, Constant propagation with conditional branches, ACM Transactions on Programming Languages and Systems (TOPLAS), v.13 n.2, p.181-210, April 1991 [doi>10.1145/103135.103136]

INDEX TERMS

Primary Classification:
  C. Computer Systems Organization
  C.3 SPECIAL-PURPOSE AND APPLICATION-BASED SYSTEMS
      Subjects: Real-time and embedded systems

Additional Classification:
  C. Computer Systems Organization
  C.0 GENERAL
      Subjects: Hardware/software interfaces

General Terms:
Algorithms, Design, Experimentation, Performance

Keywords:
constant propagation, cores, embedded systems, intellectual property, low power, platforms, synthesis, system-on-a-chip, tuning