void RegPressureTracker::recede(SmallVectorImpl<RegisterMaskPair> *LiveUses) {
recedeSkipDebugValues();
const MachineInstr &MI = *CurrPos;
RegisterOperands RegOpers;
RegOpers.collect(MI, *TRI, *MRI, TrackLaneMasks, false);
if (TrackLaneMasks) {
SlotIndex SlotIdx = LIS->getInstructionIndex(*CurrPos).getRegSlot();
RegOpers.adjustLaneLiveness(*LIS, *MRI, SlotIdx);
} else if (RequireIntervals) {
RegOpers.detectDeadDefs(MI, *LIS);
}
recede(RegOpers, LiveUses);
}
/// Record the upward impact of a single instruction on current register
/// pressure. Unlike the advance/recede pressure tracking interface, this does
/// not discover live in/outs.
///
/// This is intended for speculative queries. It leaves pressure inconsistent
/// with the current position, so must be restored by the caller.
void RegPressureTracker::bumpUpwardPressure(const MachineInstr *MI) {
assert(!MI->isDebugValue() && "Expect a nondebug instruction.");
SlotIndex SlotIdx;
if (RequireIntervals)
SlotIdx = LIS->getInstructionIndex(*MI).getRegSlot();
// Account for register pressure similar to RegPressureTracker::recede().
RegisterOperands RegOpers;
RegOpers.collect(*MI, *TRI, *MRI, TrackLaneMasks, /*IgnoreDead=*/true);
assert(RegOpers.DeadDefs.size() == 0);
if (TrackLaneMasks)
RegOpers.adjustLaneLiveness(*LIS, *MRI, SlotIdx);
else if (RequireIntervals)
RegOpers.detectDeadDefs(*MI, *LIS);
// Boost max pressure for all dead defs together.
// Since CurrSetPressure and MaxSetPressure
bumpDeadDefs(RegOpers.DeadDefs);
// Kill liveness at live defs.
for (const RegisterMaskPair &P : RegOpers.Defs) {
unsigned Reg = P.RegUnit;
LaneBitmask LiveLanes = LiveRegs.contains(Reg);
LaneBitmask UseLanes = getRegLanes(RegOpers.Uses, Reg);
LaneBitmask DefLanes = P.LaneMask;
LaneBitmask LiveAfter = (LiveLanes & ~DefLanes) | UseLanes;
decreaseRegPressure(Reg, LiveLanes, LiveAfter);
}
// Generate liveness for uses.
for (const RegisterMaskPair &P : RegOpers.Uses) {
unsigned Reg = P.RegUnit;
LaneBitmask LiveLanes = LiveRegs.contains(Reg);
LaneBitmask LiveAfter = LiveLanes | P.LaneMask;
increaseRegPressure(Reg, LiveLanes, LiveAfter);
}
}
