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Conformal LEC hier_compare only on 1 module

Matt Hutson

Hi,  so having a long history of using another vendors tools I am re/learning cadence ones.

Basically I have done an ECO at a sub-module.

I have rtl with the ECO and 1 big netlist of the top with the ECO. Luckily from a intermediate RC step with hierarchy.

So I tried an elaborate of the sub module. Which shows that the altered endpoints are ok, but fails for other optimized outputs across the hierarchy.

The full run takes 39 to 68 hours with heir_compare. The sub module takes 3 minutes.


Just need a clue as to what command to look at to analyze the sub module in context of the top.

Obviously I am now re-running the full top check to make sure nothing else has been affected.

Regards,

  Matt 

  • Well answering my own post. I found a couple of commands.
    ----------------
    write hier_compare  -noexact_pin_match -constraint -usage -replace -balanced_extraction -input_output_pin_equivalence \
    -MODULE <golden_module> <revised_module>
    &
    run hier_compare -ROOT_module <golden_module> <revised_module>
    -----------------
    For this design it has the similar affect as previous run:
    elaborate design -golden -root <golden_module>  -rootonly
    ----------------
    The heir_compare might mean some constraints would be passed down,
    and less modification to script for constraints at higher level though.

    However bit surprised the constant/unused flop removal is not worked out before heir compare.

    Of course I could still have missed some extra commands that might help.

  • Well answering my own post. I found a couple of commands.
    ----------------
    write hier_compare     -noexact_pin_match -constraint -usage -replace -balanced_extraction -input_output_pin_equivalence \
    -MODULE <golden_module> <revised_module>
    &
    run hier_compare -ROOT_module <golden_module> <revised_module>
    -----------------
    This has a similar affect as :
    elaborate design -golden -root <golden_module>  -rootonly
    and compare.
    ----------------
    With heir_compare the script does not need to be changed so much at least.
    I was hoping that the constraints would also be passed down.

    However was a bit surprised the constant/unused flop removal is not worked out before heir compare.
    Of course I could still have missed some extra commands that might help ignore the unused outputs.

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