gpl: use odb starting positions

[gudeh]

Description

Currently gpl only uses the existing odb starting position of instances if skipIO is activated.

OpenROAD/src/gpl/src/initialPlace.cpp

Lines 154 to 159 in 974d64f

	} else if (pbc_->isSkipIoMode() && db_inst->isPlaced()) {
	// It is helpful to pick up the placement from mpl if available,
	// particularly when you are going to run skip_io.
	const auto bbox = db_inst->getBBox()->getBox();
	inst->setCenterLocation(bbox.xCenter(), bbox.yCenter());
	++count_db_location;

A user was trying to perform two gpl runs, the first one using regions and a early stop to better guide the start of nesterov on the second run, but he would always get the starting position of instances in the center of the core because of the existing behavior.

Maybe we want a flag to explicitly use existing odb positions to avoid this issue and allow for a second nesterov run that matches the user expectation.

Suggested Solution

No response

Additional Context

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