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On Heuristic Solutions to the Simple Offset Assignment Problem in Address-Code Optimization

Published:01 September 2012Publication History
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Abstract

The increasing demand for more functionality in embedded systems applications nowadays requires efficient generation of compact code for embedded DSP processors. Because such processors have highly irregular data-paths, compilers targeting those processors are challenged with the automatic generation of optimized code with competent quality comparable to hand-crafted code. A major issue in code-generation is to optimize the placement of program variables in ROM relative to each other so as to reduce the overhead instructions dedicated for address computations. Modern DSP processors are typically shipped with a feature called Address Generation Unit (AGU) that provides efficient address-generation instructions for accessing program variables. Compilers targeting those processors are expected to exploit the AGU to optimize variables assignment. This article focuses on one of the basic offset-assignment problems; the Simple Offset Assignment (SOA) problem, where the AGU has only one Address Register and no Modify Registers. The notion of Tie-Break Function, TBF, introduced by Leupers and Marwedel [1996], has been used to guide the placement of variables in memory.

In this article, we introduce a more effective form of the TBF; the Effective Tie-Breaking Function, ETBF, and show that the ETBF is better at guiding the variables placement process. Underpinning ETBF is the fact that program variables are placed in memory in sequence, with each variable having only two neighbors. We applied our technique to randomly generated graphs as well as to real-world code from the OffsetStone testbench [2010]).

In previous work [Ali et al. 2008], our technique showed up to 7% reduction in overhead when applied to randomly-generated problem instances. We report in this article on a further experiment of our technique on real-code from the Offsetstone testbench. Despite the substantial improvement our technique has achieved when applied to random problem instances, we found that it shows slight overhead reduction when applied to real-world instances in OffsetStone, which agrees with similar existing experiments. We analyze these results and show that the ETBF defaults to TBF.

References

  1. Ali, H., El-Boghdadi, H. and Shaheen, S. 2008. A new heuristic for SOA problem based on effective tie break function. In Proceedings of the 11th International Workshop on Software & Compilers for Embedded Systems (SCOPES’’08). Google ScholarGoogle Scholar
  2. Atri, S., Ramanujam, J., and Kandemir, M. 2001. Improving Offset Assignment for Embedded Processors. Springer, 158--172. Google ScholarGoogle ScholarDigital LibraryDigital Library
  3. Bartley, D. 1992. Optimizing stack frame accesses for processors with restricted addressing modes. Softw. Pract. Exper. 22, 2, 101--110. Google ScholarGoogle ScholarDigital LibraryDigital Library
  4. Choi, Y. and Kim, T. 2002. Address assignment combined with scheduling in DSP code generation. In Proceedings of the 39th Design Automation Conference. Google ScholarGoogle ScholarDigital LibraryDigital Library
  5. Falk, H. and Marwedel, P. 2004. Source Code Optimization Techniques for Data Flow Dominated Embedded Software Source Level Optimizations. Springer.Google ScholarGoogle Scholar
  6. Hong, J. 2002. Memory optimization techniques for embedded systems. Ph.D. thesis, LSU, Dept. of ECE. Google ScholarGoogle ScholarDigital LibraryDigital Library
  7. Hong, J. and Ramanujam, J. 2007. Memory offset assignment for DSPs. In Proceedings of the 3rd International Conference on Embedded Software and Systems. Springer. Google ScholarGoogle ScholarDigital LibraryDigital Library
  8. Leupers, R. 2000. Code Optimization Techniques for Embedded Processors: Methods, Algorithms, and Tools. Kluwer Academic Publisher. Google ScholarGoogle ScholarDigital LibraryDigital Library
  9. Leupers, R. 2003. Offset assignment showdown: Evaluation of DSP address code optimization algorithms. In Proceedings of the 12th International Conference on Compiler Construction, Lecture Notes in Computer Science, vol. 2622. Springer. Google ScholarGoogle ScholarDigital LibraryDigital Library
  10. Leupers, R. and Marwedel, P. 1996. Algorithms for address assignment in DSP code generation. In Proceedings of the IEEE/ACM International Conference on Computer-Aided Design. 109--112. Google ScholarGoogle ScholarDigital LibraryDigital Library
  11. Liao, S. 1996. Code generation and optimization for embedded digital signal processors. Ph.D. thesis, MIT Department of EECS. Google ScholarGoogle ScholarDigital LibraryDigital Library
  12. OffsetStone. 2010. Address code optimization benchmark. http://www.address-code-optimization.org.Google ScholarGoogle Scholar
  13. Ramanujam, J., Hong, J., Kandemir, M., and Atri, S. 2001. Address register-oriented optimizations for embedded processors. In Proceedings of the 9th Workshop on Compilers for Parallel Computers. 281--290.Google ScholarGoogle Scholar
  14. Rao, A. and Pande, S. 1999. Storage assignment optimizations to generate compact and efficient code on embedded DSPs. ACM SIGPLAN Not, 128--138. Google ScholarGoogle ScholarDigital LibraryDigital Library
  15. Salamy, H. and Ramanujam, J. 2007. An effective heuristic for simple offset assignment with variable coalescing. In Proceedings of the 19th International Workshop on Languages and Compilers for Parallel Computing, Lecture Notes in Computer Science, vol. 4382, Springer. Google ScholarGoogle ScholarDigital LibraryDigital Library
  16. Udayanar, S. and Chakrabarti, C. 2001. Address code generation for digital signal processors. In Proceedings of the 38th Annual Design Automation Conference. ACM. Google ScholarGoogle ScholarDigital LibraryDigital Library
  17. Zivoinovic, V., Martinez, J., Schlager, C., and Meyr, H. 1994, DSPstone: A DSP-oriented benchmarking methodology. In Proceedings of the International Conference on Signal Processing Applications and Technology.Google ScholarGoogle Scholar

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