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Image redundant wire identification

Image redundant wire identification. Speaker: Yung-chih Chen. Outline. Introduction Previous work Possible approach Future work. == img != function. 0 0 1 1 0 1 0 1. 0 0 1 1 0 1 0 1. 0 1. 0 1. 0 0 1 0 1 1. Image eq. 0 0 1 0 1 1. Introduction. Image equivalence.

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Image redundant wire identification

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  1. Image redundant wire identification Speaker: Yung-chih Chen

  2. Outline • Introduction • Previous work • Possible approach • Future work

  3. ==img !=function 0 0 1 1 0 1 0 1 0 0 1 1 0 1 0 1 0 1 0 1 0 0 1 0 1 1 Image eq. 0 0 1 0 1 1 Introduction • Image equivalence Image redundant wire

  4. Random simulation flow chat Legal Vectors Reference Model Constraint circuit Optimized constraint circuit Output Comparator Random Vector Generator Design Under Verification (DUV) Coverage Feedback

  5. circuit DUV Optimized Circuit DUV optimize Problem formulation • Input • A constraint circuit A’ • Output • A optimized constraint circuit B’ • Objective • Size of B’ << size of A’ • B’ ==img A’

  6. Previous work • Remove tree structure • Use the rewiring technique to construct tree structure • Characteristic BDD • Circuit partition

  7. Tree structure No multiple fanouts Replace the tree structure by a primary input Remove tree structure

  8. Rewiring technique optimize

  9. y1 y1 y2 y2 Smoothing all input y2 x1 x1 1 0 x2 x2 1 0 Characteristic BDD • Use characteristic BDD and smoothing technique to verify image equivalence 1: legal output 0: illegal output

  10. Remove primary input • Assign constant value to PI to reduce circuit (cofactor) • Check • If Fxi=0 ==img org circuit, then we set constant 0 to PI xi, and optimize circuit. • If Fxi=1 ==img org circuit, then we set constant 1 to PI xi, and optimize circuit.

  11. x y y c x x c image b y y b b a a cofactor c=0 x 1 1 0 0 y y 1 0 b b b Image eq. a a image 1 0 Example Order: x < y < c < b < a a b c x y a b x y

  12. Vertical partition horizontal partition mixed partition Circuit partition • For each circuit, we can do vertical partition or horizontal partition into some subcircuit

  13. Summary • Remove tree structure • Use the rewiring technique to construct tree structure • Characteristic BDD • Iteratively remove PIs • Circuit partition

  14. Possible approach • Algorithm for image redundant wires identification • Iteratively remove PIs

  15. Example (1/2) optimize

  16. Example (2/2) optimize

  17. Idea • Img of F = Img of Fxi=0∪ Img of Fxi=1 • If Img of Fxi=0≤ Img of Fxi=1, then we set xi=1 and optimize the circuit • If Img of Fxi=1≤ Img of Fxi=0, then we set xi=0 and optimize the circuit

  18. Idea • Img of Fxi=0 = Img of Fxi=0, X-xi=A∪ Img of Fxi=0, X-xi=B • Img of Fxi=1 = Img of Fxi=1, X-xi=A∪ Img of Fxi=1, X-xi=B • Img of Fxi=0, X-xi=B= Img of Fxi=1, X-xi=B? A is the set of X-xi such that the effect xi can be propagated to POs B is the set of X-xi such that the effect xi cannot be propagated to POs

  19. Future work • Propose an algorithm for image redundant PIs identification • Analyze Img of Fxi=0and Img of Fxi=1

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