Call ScheduleDAGInstrs::buildSchedGraph with register pressure tracking enabled. This sets up three trackers. RPTracker will cover the entire DAG region, TopTracker and BottomTracker will be initialized to the top and bottom of the DAG region without covereing any unscheduled instruction.
Declared in <llvm/CodeGen/MachineScheduler.h>
void
buildDAGWithRegPressure();