Design Compiler warning OPT-1206

[jayTudu]

opt-1206

Hi designerAll,

Can any one suggest me how to avoid the warning OPT-1206 in design compiler.
The OPT-1206 defination is: " The register Ro is constant and will be removed ".
This warns that some of the flipflop from my design are getting removed as a result
of optimization, but I donot want any of the filpflop to be removed from my design.
Is ther any command which can serve this purpose ?

Thanks n Regards,
JAY...

 

[dcreddy1980]

the register is a constant design compiler

To preserve Flip flop from being removed by DC, apply the below command :

set hdlin_preserve_sequential true

 

[aravind]

various warnings design compiler

I have another question, how to avoid sequential merging in DC. Is DC doing sequential merge across hieriarchy?

Thanks
Aravind

 

[jayTudu]

design compiler warnings

Thanks dcreddy... I will try this command
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Hi Aravind can you just explain what is sequential merging, I may try to search for an answer for you.

 

[raju3295]

design compiler boundary optimization

i dont think so,, any tool will merge the hierarchies and do the optimizations across the hierarchies,, untill u ask to do so,,, so sequential merge across hieriarchy may not occur

 

[D Saurabh]

design compiler

The switch -boundary_optimization (compile -boundary_optimization) will result in optimization across hierarchies. Make sure u don't include it in case u want to prevent it.

 

[eeeraghu]

design compiler -edges

after boundary optimization use set register merging as false for that particular register inorder not to remove or merge that particular register for particular reasons.