How does OpenROAD compute the die_area and core_area while using core_utilization, instance_area, and instance_count?

[danissimo8]

Hello, I have a question out of pure curiosity: how does OpenROAD compute the die_area and core_area while using core_utilization, instance_area, and instance_count?

[maliberty]

Instance count is irrelevant. We just add up the area of all the instances in the netlist and the of calculation is pretty simple, see

OpenROAD/src/ifp/src/InitFloorplan.cc

Line 123 in 6645a53

const double design_area = designArea();

[danissimo8]

Thank you for your response! However, my question is specifically about die_area, not design_area. I understand that design_area is just the sum of all instance_area. But how does OpenROAD compute die_area based on core_utilization, instance_area, and other parameters? Is there a specific formula used in the code for this?

[danissimo8]

And also: how does OpenROAD calculate ux, lx, uy and ly values? I realized that they are taken from .def files, so could you tell me the path to the script in which these values ​​are calculated in order to be further used in .def?

[maliberty]

The answer is in the code

You just expand the core area by the core-to-die space and position it at 0,0

[maliberty]

I don't know why you are posting code from OpenLane here. Questions about OL should be posed in that repo.