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Black Boxes

AMit Raj

While running LEC i got may unreachable blackboxes, can anyone tell me how to remove these BlackBoxes..??

  • What do you mean by "remove"? Remove from the reporting or remove from the design?

     

    Unreachables are a problem only if unexpected. You can do "report gate -unreach" to see why a point is unreachable (no path to an output through any sort of logic, therefore it has no effect, therefore LEC doesn't map nor compare it).

     

    Typical unreachables:

    1) unused logic in RTL

    2) spare gates

    3) disable test logic

    4) clock-gating latches (after modeling with set flatten model gated_clock)

     

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