private bool IntervalSplitAtFirstUseOrDef(LiveInterval liveInterval)
{
// last resort
if (liveInterval.IsEmpty)
return false;
SlotIndex at;
var firstUse = liveInterval.UsePositions.Count != 0 ? liveInterval.UsePositions[0] : null;
var firstDef = liveInterval.DefPositions.Count != 0 ? liveInterval.DefPositions[0] : null;
at = firstDef;
if (at == null)
at = firstUse;
else if (firstUse != null && firstUse < at)
at = firstUse;
var atNext = at.Next;
if (liveInterval.Start == at && liveInterval.End == atNext)
{
if (trace.Active) trace.Log(" Interval already smallest");
return false;
}
if (trace.Active) trace.Log(" Splitting around first use/def");
var virtualRegister = liveInterval.VirtualRegister;
virtualRegister.Remove(liveInterval);
if (liveInterval.Start != at)
{
var first = liveInterval.Split(liveInterval.Start, at);
CalculateSpillCost(first);
virtualRegister.Add(first);
AddPriorityQueue(first);
if (trace.Active) trace.Log(" First Split : " + first.ToString());
}
var middle = liveInterval.Split(at, atNext);
CalculateSpillCost(middle);
virtualRegister.Add(middle);
AddPriorityQueue(middle);
if (trace.Active) trace.Log(" Middle Split: " + middle.ToString());
if (liveInterval.End != atNext)
{
var last = liveInterval.Split(atNext, liveInterval.End);
CalculateSpillCost(last);
virtualRegister.Add(last);
AddPriorityQueue(last);
if (trace.Active) trace.Log(" Last Split : " + last.ToString());
}
return true;
}
private bool TrySimplePartialFreeIntervalSplit(LiveInterval liveInterval)
{
SlotIndex furthestUsed = null;
foreach (var track in liveIntervalTracks)
{
if (track.IsReserved)
continue;
if (track.IsFloatingPoint != liveInterval.VirtualRegister.IsFloatingPoint)
continue;
var next = track.GetNextLiveRange(liveInterval.Start);
if (next == null)
continue;
Debug.Assert(next > liveInterval.Start);
if (trace.Active) trace.Log(" Register " + track.ToString() + " free up to " + next.ToString());
if (furthestUsed == null || furthestUsed < next)
furthestUsed = next;
}
if (furthestUsed == null)
{
if (trace.Active) trace.Log(" No partial free space available");
return false;
}
if (furthestUsed < liveInterval.Minimum)
{
if (trace.Active) trace.Log(" No partial free space available");
return false;
}
//Debug.Assert(!furthestUsed.IsBlockStartInstruction);
if (furthestUsed.IsBlockStartInstruction)
{
return false;
}
var lastFree = furthestUsed.Previous;
if (lastFree <= liveInterval.Start)
{
if (trace.Active) trace.Log(" No partial free space available");
return false;
}
if (trace.Active) trace.Log(" Partial free up to: " + furthestUsed.ToString());
var low = GetLowOptimalSplitLocation(liveInterval, lastFree, true);
var high = GetHighOptimalSplitLocation(liveInterval, lastFree, true);
var first = liveInterval.Split(liveInterval.Start, low);
var last = liveInterval.Split(high, liveInterval.End);
var middle = (low != high) ? liveInterval.Split(low, high) : null;
if (trace.Active) trace.Log(" Low Split : " + first.ToString());
if (trace.Active) trace.Log(" Middle Split: " + (middle == null ? "n/a" : middle.ToString()));
if (trace.Active) trace.Log(" High Split : " + last.ToString());
var virtualRegister = liveInterval.VirtualRegister;
CalculateSpillCost(first);
CalculateSpillCost(last);
virtualRegister.Remove(liveInterval);
virtualRegister.Add(first);
virtualRegister.Add(last);
AddPriorityQueue(first);
AddPriorityQueue(last);
if (middle != null)
{
//middle.ForceSpilled = true;
CalculateSpillCost(middle);
virtualRegister.Add(middle);
AddPriorityQueue(middle);
}
return true;
}
