Logic Difference Optimization for Incremental Synthesis

  • Smita Krishnaswamy
  • Haoxing Ren
  • Nilesh Modi
  • Ruchir Puri
Chapter

Abstract

During the IC design process, functional specifications are often modified late in the design cycle, often after placement and routing are completed. However, designers are left either to manually process such modifications by hand or to restart the design process from scratch–a very costly option. In order to address this issue, we present DeltaSyn, a tool and methodology for generating a highly optimized logic difference between a modified high-level specification and an implemented design. DeltaSyn has the ability to locate similar logic in the original design which can be reused to realize the modified specification through several analysis techniques that are applied in sequence. The first phase employs fast functional and structural analysis techniques to identify equivalent signals between the original and the modified circuits. The second phase uses a novel topologically-guided dynamic matching algorithm to locate reusable portions of logic close to the primary outputs. The third phase utilizes functional hashing to locate similar chunks of logic throughout the remainder of the circuit. Experiments on industrial designs show that, together, these techniques successfully implement incremental changes while preserving an average of 97% of the pre-existing logic. Unlike previous approaches, bit-parallel simulation and dynamic programming enable fast performance and scalability. A typical design of around 10  gates is processed and verified in about 200 s or less.

Keywords

Boolean Function Difference Model Symmetry Class Logic Difference Primary Output 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  • Smita Krishnaswamy
    • 1
  • Haoxing Ren
    • 1
  • Nilesh Modi
    • 1
  • Ruchir Puri
    • 1
  1. 1.IBM TJ Watson Research CenterYorktown HeightsUSA

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