public void OnRelease(object[] qubitsTraceData)
{
OperationCallRecord opRec = operationCallStack.Peek();
opRec.ReleasedQubitsAvailableTime = Max(
opRec.ReleasedQubitsAvailableTime,
MaxAvailableTime(qubitsTraceData.Cast <QubitTimeMetrics>()));
if (optimizeDepth)
{
// Performing width computation and applying reuse heuristics.
// First we fix busy time periods for all qubits involved.
foreach (QubitTimeMetrics q in qubitsTraceData.Cast <QubitTimeMetrics>())
{
// If qubit is not fixed in time we fix it at zero.
if (q.StartTime.IsEqualTo(ComplexTime.MinValue))
{
q.StartTime = ComplexTime.Zero;
}
}
// Then we sort qubits ascending by the start of busy time. This would result in optimal reuse if:
// (1) We were not allowed to move gates in time.
// (2) We were sorting all qubits of the cirquit, not just this block.
// In reality these statements aren't true, so this is only a heuristic rather than the optimal reuse of qubits.
Array.Sort(qubitsTraceData, CompareAsQubitTimeMetricsByStartTime);
// Reuse qubits if possible or increase count of qubits used.
foreach (QubitTimeMetrics q in qubitsTraceData.Cast <QubitTimeMetrics>())
{
// If qubit wasn't used in any gate. We don't allocate it.
if (q.EndTime.IsEqualTo(ComplexTime.Zero))
{
continue;
}
// Then we find if we can reuse existing qubits.
bool reuseExistingAfterNew = qubitStartTimes.FindBound(q.EndTime, getLowerBound: false, out ComplexTime existingStart);
bool reuseNewAfterExising = qubitEndTimes.FindBound(q.StartTime, getLowerBound: true, out ComplexTime existingEnd);
if (reuseNewAfterExising && reuseExistingAfterNew)
{
// If we can do both, see which reuse creates a shorter gap and leave it for reuse.
if (ComplexTime.Compare(q.StartTime.Subtract(existingEnd), existingStart.Subtract(q.EndTime)) > 0)
{
reuseNewAfterExising = false;
}
else
{
reuseExistingAfterNew = false;
}
}
if (reuseNewAfterExising)
{
// If we place new qubit after existing - update end time of existing qubit
long idToReuse = qubitEndTimes.Remove(existingEnd);
qubitEndTimes.Add(idToReuse, q.EndTime);
}
else if (reuseExistingAfterNew)
{
// If we place new qubit before existing - update start time of existing qubit
long idToReuse = qubitStartTimes.Remove(existingStart);
qubitStartTimes.Add(idToReuse, q.StartTime);
}
else
{
// We cannot reuse existing qubits. Use new qubit.
long id = maxQubitId;
maxQubitId++;
qubitStartTimes.Add(id, q.StartTime);
qubitEndTimes.Add(id, q.EndTime);
}
}
}
}
public void OnRelease(object[] qubitsTraceData)
{
OperationCallRecord opRec = operationCallStack.Peek();
opRec.ReleasedQubitsAvailableTime = Max(
opRec.ReleasedQubitsAvailableTime,
MaxAvailableTime(qubitsTraceData.Cast <QubitTimeMetrics>()));
if (optimizeDepth)
{
// Doing width reuse heuristics and width computation.
foreach (QubitTimeMetrics q in qubitsTraceData.Cast <QubitTimeMetrics>())
{
// If qubit wasn't used in any gate. We don't allocate it.
if (q.EndTime.IsEqualTo(ComplexTime.Zero))
{
continue;
}
// If qubit is not fixed in time we fix it at zero.
if (q.StartTime.IsEqualTo(ComplexTime.MinValue))
{
q.StartTime = ComplexTime.Zero;
}
// Then we find if we can reuse existing qubits.
bool reuseExistingAfterNew = qubitStartTimes.FindBound(q.EndTime, getLowerBound: false, out ComplexTime existingStart);
bool reuseNewAfterExising = qubitEndTimes.FindBound(q.StartTime, getLowerBound: true, out ComplexTime existingEnd);
if (reuseNewAfterExising && reuseExistingAfterNew)
{
// If we can do both, see which reuse creates a shorter gap and leave it for reuse.
if (ComplexTime.Compare(q.StartTime.Subtract(existingEnd), existingStart.Subtract(q.EndTime)) > 0)
{
reuseNewAfterExising = false;
}
else
{
reuseExistingAfterNew = false;
}
}
if (reuseNewAfterExising)
{
// If we place new qubit after existing - update end time of existing qubit
long idToReuse = qubitEndTimes.Remove(existingEnd);
qubitEndTimes.Add(idToReuse, q.EndTime);
}
else if (reuseExistingAfterNew)
{
// If we place new qubit before existing - update start time of existing qubit
long idToReuse = qubitStartTimes.Remove(existingStart);
qubitStartTimes.Add(idToReuse, q.StartTime);
}
else
{
// We cannot reuse existing qubits. Use new qubit.
long id = maxQubitId;
maxQubitId++;
qubitStartTimes.Add(id, q.StartTime);
qubitEndTimes.Add(id, q.EndTime);
}
}
}
}
