In place Optimization Steps

Include script with back annotation information, that is, a dc shell sct joad script with load information for all nets in the design and an SDF file. 

Write out the hierarchical db file. Use this for future re-runs. This helps, since the setjoad script is usually long and takes a significant time to complete, depending on the size of the design. 

Include the area script to set area values for the different cells. This script essentially specifies lower area values for low drive cells. For this script, one must have a list of all the low drive cells in the library. This information will have to be obtained from the ASIC vendor, unless the vendor follows a particular naming convention for low drive cells. 

Set the dont touch attribute on any blocks in the design which you wish to remain unchanged during IPO. 

Set current design to the top level block, and ungroup all the levels below it. The dont touched blocks will not be ungrouped. 

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