CRPR calculation for multicycle path

[chevuturi]

Hello,

Will PrimeTime or any timing sign-off tool calculate CRPR differently for multicycle path as compared as Full-cycle path.

Thanks

 

[kaz1]

Google AI says yes. But I don't think so.
CRPR definition is "max delay - min delay, of common clock path" so nothing to do with multicycle.
However, CRPR will enter calculation of timing closure which is affected by multicycle.

 

[ThisIsNotSam]

STA will understand the multi cycle path, but no different computations will take place because of it. It still is a reg2reg path that must respect setup*N under different launch and capture times that may be calculated with pessimism removal.

 

[kaz1]

On a related note: why timing tools don't decide on pessimism removal themselves instead of asking user to decide.? any thoughts please.

 

[ThisIsNotSam]

When the feature was first introduced, it was considered experimental and turned off by default. I think it is now ON in Innovus, but I would have to double check.

 

[chevuturi]

STA will understand the multi cycle path, but no different computations will take place because of it. It still is a reg2reg path that must respect setup*N under different launch and capture times that may be calculated with pessimism removal.

So When it is trying to calculate with pessimism removal it will look into different launch edges and different capture edges and it will apply derates as per analysis. correct if i misunderstood ?
and is crosstalk analysis also same? will it treat as reg to reg when it comes to multicycle path ?