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schNetExprEvalNames issue inside bus-like instance

raduionescu

Hello,

I have a strange problem with some code I am maintaining (although did not write myself).

The code attempts to get the top most name of nets connected to pins with inherited connections. For this it uses schNetExprEvalNames  followed by geGetAdjustedPath. schNetExprEvalNames  seems to have a bug or issue if on the path there is a instance like I<1:2>.

I have two placements of a cell, once with bus once without, and lower in the hierarchy I have a device with an inherited pin

/TOP/I11/i_R/I0/I18/I3/I4/I1/ntrans11 is one

/TOP/I11/i_R/I0/I18/I1<1:2>/I4/I1/ntrans11 is the other.

the inherited term we have  dbGetTermNetExpr(term) -> "[@hSup:%:VSS!]"

what the code does is this, some differences in red

schNetExprEvalNames( ds list(/TOP/I11/i_R/I0/I18/I3/I4/I1/ntrans11 ) ?listCellView t) which returns a list including the net

((("/TOP/I11/i_RACS2/I0/I18/I3/I4/GND"1 1
        (("lib" "cell" "view" "lSup" "VSS!"
            1
        )
        ) nil
    )
    )
)

after which geGetAdjustedPath(designWindow "/TOP/I11/i_RACS2/I0/I18/I3/I4/GND") returns "/TOP/I11/vss_r_net"

but on the second instance:

schNetExprEvalNames( ds list(/TOP/I11/i_R/I0/I18/I1<1>/I4/I1/ntrans11 ) ?listCellView t) which returns a list including the net

((("/TOP/I11/i_RACS2/I0/I18/I1<18>/I4/GND"1 1
        (("lib" "cell" "view" "lSup" "VSS!"
            1
        )
        ) nil
    )
    )
)

I1<18> does not exist in the schematic, have no idea where the proc gets it. And off course the net does not exists.

what I did notice is if I skip schNetExprEvalNames and go to the level of the transistor and apply geGetAdjustedPath directly, I get the correct net

geGetAdjustedPath(designWindow "/TOP/I11/i_RACS2/I0/I18/I3/I4/I1/VSS!") returns "/TOP/I11/vss_r_net"

geGetAdjustedPath(designWindow "/TOP/I11/i_RACS2/I0/I18/I1<1>/I4/I1/VSS!") returns "/TOP/I11/vss_r_net"

So my question is: is there a reason I absolutely need schNetExprEvalNames or can I be confident that using geGetAdjustedPath gets me the results I want? Are there situations when only geGetAdjustedPath gives bad results?

Thank you.

Regards,


Radu

  • raduionescu

    I will answer my own question, depending on how netSet properties are used schNetExprEvalNames is in fact needed. Cannot be replaced with geGetAdjustedPath .

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