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does lec pass, if there is inverted-equivalent point?

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FredXu

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lec inverted equivalent

The lec report is as below, does it mean the compare pass? Thanks,

0 compared point(s) reported
=====================================================
Compared points PO DFF DLAT BBOX Total
--------------------------------------------------------------------------------
Equivalent 2013 79746 5200 60 87019
--------------------------------------------------------------------------------
Inverted-equivalent 0 2 0 0 2
=====================================================
 

inverted equivalent

It should be a problem.. I think to meet the timing DC has moved the inverter from input to output side ie it has used a flop output QN instead of Q.. (default behaviour.. if you want to remove it you might need to use -no_seq_output_inversion with compile_ultra command).
 

    F

    FredXu

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inverted-equivalent

Thanks.
One more question:
How can I find out which DFFs are inverted in lec run? Which command can report it?
 

dc with compile_ultra

I dont have an answer for this.. but it should get reported which you report the matched points explicitly..
 

matching of registers used qn output lec

I used DC with compile_ultra -no_seq_output_inversion,
but the "Inverted-equivalent" is still reported, look it's not caused by DC.
Any other suggestion?
 

dc compile_ultra lec

Hello FredXu,
"Inverted Equivalent" is actually ok! It is completely equivalent
You don't need to do anything. I have put an LEC flow in our company and we see this occassionally when DC performs inverter push on the design or when libraries are coded with only their Q_Bar output as available.
-- ay
 

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    FredXu

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lec invertdff

Thanks, Adam. Reall appreciate your help.
 

lec invert equivalent

Hi,

There is a switch while reporting the equivalent point in lec so u can specified it and can see the flops which are inverted equivalent. or in gui also u can see in the matching point window and anlyze them using schematic or with code also.

It may help u.

Thanks..

HAK..
 

    F

    FredXu

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Thanks, HAK,
I used lec to report the inverted equivalent point and make sure it's OK for FV.
 

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