About compile_ultra and compile_ultra -incr

[hjacky]

Hi,

Does someone know the difference between the following flow in Design Compiler:

Flow 1: Netlist+sdc -> compile_ultra -> compile_ultra -incr -> final_compile_1.ddc
Flow 2: Netlist+sdc -> compile_ultra -> initial_compile.ddc -> compile_ultra -> final_compile_2.ddc

Thanks,

 

[sharath666]

I don't understand the 2nd flow. Why are you running compile_ultra 2 times?

 

[hjacky]

For the second flow, after i generated a ddc file from DC, i can use the ddc to generate DEF/FP files in ICC, then i can use the def and former ddc files as input data into DC (one of Design compiler topographical feature).

 

[sharath666]

Understood. That means in the 2nd case, you are invoking DC twice(one without def and one with def). The 2nd one yields more accurate results. I don't know of any other difference.