private void RemoveBackEdgesFromSwitchConstructs(ILogicalConstruct theConstruct)
{
V_0 = DFSTBuilder.BuildTree(theConstruct).get_BackEdges().GetEnumerator();
try
{
while (V_0.MoveNext())
{
V_1 = V_0.get_Current();
V_2 = V_1.get_Start().get_Construct() as ILogicalConstruct;
if (V_2 as ConditionLogicalConstruct != null)
{
continue;
}
V_3 = V_2 as CFGBlockLogicalConstruct;
if (V_3 == null || V_3.get_TheBlock().get_Last().get_OpCode().get_Code() != 68)
{
continue;
}
this.MarkAsGotoEdge(V_2, V_1.get_End().get_Construct() as ILogicalConstruct);
}
}
finally
{
((IDisposable)V_0).Dispose();
}
return;
}
/// <summary>
/// Analyzes <paramref name="interval"/> and makes a loop from it, if possible.
/// </summary>
/// <param name="interval">The interval to be analyzed.</param>
/// <returns>Returns true if a loop was made.</returns>
private bool TryMakeLoop(IntervalConstruct interval, DominatorTree dominatorTree)
{
DFSTree dfsTree = DFSTBuilder.BuildTree(interval);
if (dfsTree.BackEdges.Count == 0)
{
/// No back edges in the interval, so no loop can be made.
return(false);
}
HashSet <ILogicalConstruct> loopBody;
HashSet <ILogicalConstruct> possibleLatchingNodes = BuildLoop(dfsTree, out loopBody);
ConditionLogicalConstruct loopCondition;
LoopType typeOfLoop = DetermineLoopType(loopBody, possibleLatchingNodes, interval, dominatorTree, out loopCondition);
if (loopBody.Count > 0)
{
LoopLogicalConstruct loop = new LoopLogicalConstruct(interval.Entry as ILogicalConstruct, loopBody, typeOfLoop, loopCondition, typeSystem);
CleanUpEdges(loop); /// Covers the case in IrregularbackedgeExitLoop
UpdateDominatorTree(dominatorTree, loop);
return(true);
}
else
{
/// Empty loops should not be created. Instead, backedges that form such loops will be marked as goto.
foreach (DFSTEdge backedge in dfsTree.BackEdges)
{
MarkAsGotoEdge(backedge.Start.Construct as ILogicalConstruct, backedge.End.Construct as ILogicalConstruct);
}
}
return(false);
}
private bool TryMakeLoop(IntervalConstruct interval, DominatorTree dominatorTree)
{
V_0 = DFSTBuilder.BuildTree(interval);
if (V_0.get_BackEdges().get_Count() == 0)
{
return(false);
}
V_2 = this.BuildLoop(V_0, out V_1);
V_4 = this.DetermineLoopType(V_1, V_2, interval, dominatorTree, out V_3);
if (V_1.get_Count() > 0)
{
V_5 = new LoopLogicalConstruct(interval.get_Entry() as ILogicalConstruct, V_1, V_4, V_3, this.typeSystem);
this.CleanUpEdges(V_5);
this.UpdateDominatorTree(dominatorTree, V_5);
return(true);
}
V_6 = V_0.get_BackEdges().GetEnumerator();
try
{
while (V_6.MoveNext())
{
V_7 = V_6.get_Current();
this.MarkAsGotoEdge(V_7.get_Start().get_Construct() as ILogicalConstruct, V_7.get_End().get_Construct() as ILogicalConstruct);
}
}
finally
{
((IDisposable)V_6).Dispose();
}
return(false);
}
private List <IntervalConstruct> SortIntervalList(List <IntervalConstruct> intervals)
{
V_0 = new IntervalConstruct(intervals.get_Item(0));
V_2 = intervals.GetEnumerator();
try
{
while (V_2.MoveNext())
{
V_3 = V_2.get_Current();
dummyVar0 = V_0.get_Children().Add(V_3);
}
}
finally
{
((IDisposable)V_2).Dispose();
}
stackVariable15 = DFSTBuilder.BuildTree(V_0);
V_1 = new List <IntervalConstruct>();
V_4 = stackVariable15.get_ReversePostOrder().GetEnumerator();
try
{
while (V_4.MoveNext())
{
V_5 = V_4.get_Current();
V_1.Add(V_5.get_Construct() as IntervalConstruct);
}
}
finally
{
((IDisposable)V_4).Dispose();
}
return(V_1);
}
private void CleanUpEdges(LoopLogicalConstruct loopConstruct)
{
V_0 = DFSTBuilder.BuildTree(loopConstruct.get_Parent()).get_ConstructToNodeMap().get_Item(loopConstruct);
if (V_0.get_BackEdgeSuccessors().get_Count() == 0)
{
return;
}
V_1 = V_0.get_BackEdgeSuccessors().GetEnumerator();
try
{
while (V_1.MoveNext())
{
V_2 = V_1.get_Current();
if (V_2.get_Construct() as ILogicalConstruct as ConditionLogicalConstruct != null)
{
continue;
}
this.MarkAsGotoEdge(loopConstruct, V_2.get_Construct() as ILogicalConstruct);
}
}
finally
{
((IDisposable)V_1).Dispose();
}
return;
}
private Dictionary <ILogicalConstruct, HashSet <ISingleEntrySubGraph> > GetValidCases(DominatorTree dominatorTree, ILogicalConstruct switchCFGBlock)
{
V_0 = new SwitchBuilder.u003cu003ec__DisplayClass9_0();
V_0.caseEntriesToDominatedNodesMap = new Dictionary <ILogicalConstruct, HashSet <ISingleEntrySubGraph> >();
V_1 = new HashSet <ISingleEntrySubGraph>();
dummyVar0 = V_1.Add(switchCFGBlock);
V_4 = switchCFGBlock.get_SameParentSuccessors().GetEnumerator();
try
{
while (V_4.MoveNext())
{
V_5 = (ILogicalConstruct)V_4.get_Current();
if (V_5 == switchCFGBlock || dominatorTree.GetImmediateDominator(V_5) != switchCFGBlock)
{
continue;
}
V_6 = dominatorTree.GetDominatedNodes(V_5);
V_0.caseEntriesToDominatedNodesMap.Add(V_5, V_6);
V_1.UnionWith(V_6);
}
}
finally
{
((IDisposable)V_4).Dispose();
}
stackVariable34 = DFSTBuilder.BuildTree(switchCFGBlock.get_Parent(), switchCFGBlock).get_ReversePostOrder();
stackVariable35 = SwitchBuilder.u003cu003ec.u003cu003e9__9_0;
if (stackVariable35 == null)
{
dummyVar1 = stackVariable35;
stackVariable35 = new Func <DFSTNode, ILogicalConstruct>(SwitchBuilder.u003cu003ec.u003cu003e9.u003cGetValidCasesu003eb__9_0);
SwitchBuilder.u003cu003ec.u003cu003e9__9_0 = stackVariable35;
}
V_2 = new List <ILogicalConstruct>(stackVariable34.Select <DFSTNode, ILogicalConstruct>(stackVariable35).Where <ILogicalConstruct>(new Func <ILogicalConstruct, bool>(V_0.u003cGetValidCasesu003eb__1)));
do
{
V_3 = false;
V_7 = V_2.GetEnumerator();
try
{
while (V_7.MoveNext())
{
V_8 = V_7.get_Current();
if (!V_0.caseEntriesToDominatedNodesMap.TryGetValue(V_8, out V_9) || this.IsCaseValid(V_8, V_1))
{
continue;
}
V_1.ExceptWith(V_9);
dummyVar2 = V_0.caseEntriesToDominatedNodesMap.Remove(V_8);
V_3 = true;
}
}
finally
{
((IDisposable)V_7).Dispose();
}
}while (V_3);
return(V_0.caseEntriesToDominatedNodesMap);
}
/// <summary>
/// Builds if constructs in the specified construct.
/// </summary>
/// <param name="construct"></param>
private void BuildIfConstructs(ILogicalConstruct construct)
{
DominatorTree dominatorTree = GetDominatorTreeFromContext(construct);
DFSTree dfsTree = DFSTBuilder.BuildTree(construct);
foreach (ConditionLogicalConstruct condition in GetPostOrderedIfConditionCandidates(dfsTree))
{
TryBuildIfConstruct(condition, dominatorTree, dfsTree);
}
}
private void ProcessSwitchConstructs(ILogicalConstruct parent, List <CFGBlockLogicalConstruct> switchBlocks)
{
DominatorTree dominatorTree = GetDominatorTreeFromContext(parent);
DFSTree dfsTree = DFSTBuilder.BuildTree(parent);
switchBlocks.Sort((x, y) => dfsTree.ConstructToNodeMap[y].ReversePostOrderIndex.CompareTo(dfsTree.ConstructToNodeMap[x].ReversePostOrderIndex));
foreach (CFGBlockLogicalConstruct switchBlock in switchBlocks)
{
CreateSwitchConstruct(switchBlock, parent, this.logicalContext.CFG.SwitchBlocksInformation[switchBlock.TheBlock], dominatorTree);
}
}
/// <summary>
/// Creates a subgraph of the specified <paramref name="graph"/>.
/// </summary>
/// <remarks>
/// The subgraph has the same vertices as the original. The difference is that the subgraph does not contain the back edges
/// found by the dfs traversal of the <paramref name="graph"/>.
/// </remarks>
/// <param name="graph"></param>
private void GetVerticesAndAdjacencyMatrix(ILogicalConstruct graph)
{
DFSTree dfsTree = DFSTBuilder.BuildTree(graph);
orderedVertexArray = new ILogicalConstruct[dfsTree.ReversePostOrder.Count];
for (int i = 0; i < orderedVertexArray.Length; i++)
{
orderedVertexArray[i] = dfsTree.ReversePostOrder[i].Construct as ILogicalConstruct;
}
BuildAdjacencyMatrix(dfsTree);
}
/// <summary>
/// Gets the CFGBlockLC children of theBlock sorted in reverse post order.
/// </summary>
private void GetOrderedCFGNodes()
{
DFSTree dfsTree = DFSTBuilder.BuildTree(theBlock);
foreach (DFSTNode node in dfsTree.ReversePostOrder)
{
CFGBlockLogicalConstruct cfgConstruct = node.Construct as CFGBlockLogicalConstruct;
if (cfgConstruct != null)
{
orderedCFGNodes.Add(cfgConstruct);
}
}
}
private void GetVerticesAndAdjacencyMatrix(ILogicalConstruct graph)
{
V_0 = DFSTBuilder.BuildTree(graph);
this.orderedVertexArray = new ILogicalConstruct[V_0.get_ReversePostOrder().get_Count()];
V_1 = 0;
while (V_1 < (int)this.orderedVertexArray.Length)
{
this.orderedVertexArray[V_1] = V_0.get_ReversePostOrder().get_Item(V_1).get_Construct() as ILogicalConstruct;
V_1 = V_1 + 1;
}
this.BuildAdjacencyMatrix(V_0);
return;
}
private void RemoveBlockingEdges(List <IntervalConstruct> intervals)
{
V_0 = new IntervalConstruct(intervals.get_Item(0));
V_5 = 1;
while (V_5 < intervals.get_Count())
{
dummyVar0 = V_0.get_Children().Add(intervals.get_Item(V_5));
V_5 = V_5 + 1;
}
V_1 = DFSTBuilder.BuildTree(V_0);
V_2 = V_1.get_BackEdges().FirstOrDefault <DFSTEdge>();
if (V_2 == null)
{
V_2 = V_1.get_CrossEdges().FirstOrDefault <DFSTEdge>();
}
V_3 = V_2.get_Start().get_Construct() as IntervalConstruct;
V_4 = V_2.get_End().get_Construct() as IntervalConstruct;
V_6 = V_4.get_Entry().get_SameParentPredecessors().GetEnumerator();
try
{
while (V_6.MoveNext())
{
V_7 = (ILogicalConstruct)V_6.get_Current();
if (!V_3.get_Children().Contains(V_7))
{
continue;
}
V_8 = V_7;
V_9 = V_4.get_Entry() as ILogicalConstruct;
if (this.removedEdges.TryGetValue(V_8, out V_10) && V_10.Contains(V_9))
{
continue;
}
this.MarkAsGotoEdge(V_8, V_9);
goto Label0;
}
}
finally
{
((IDisposable)V_6).Dispose();
}
Label0:
return;
}
protected override void FindImmediateDominators()
{
List <DFSTNode> reversePostOrderMap = DFSTBuilder.BuildTree(originalGraph).ReversePostOrder;
List <DFSTNode>[] predecessorsCache = InitializePredecessors(reversePostOrderMap);
int count = reversePostOrderMap.Count;
InitializeDominators(count);
bool changed;
do
{
changed = false;
for (int i = 1; i < count; i++)
{
List <DFSTNode> predecessors = predecessorsCache[i];
int newImmDom = GetPredecessor(predecessors, node => node.ReversePostOrderIndex != i && dominators[node.ReversePostOrderIndex] != -1);
foreach (DFSTNode predecessor in predecessors)
{
int index = predecessor.ReversePostOrderIndex;
if (index != i && dominators[index] != -1)
{
newImmDom = Intersect(index, newImmDom);
}
}
if (dominators[i] != newImmDom)
{
dominators[i] = newImmDom;
changed = true;
}
}
}while (changed);
for (int i = 1; i < count; i++)
{
DTNode node = constructToNodeMap[reversePostOrderMap[i].Construct];
DTNode immDom = constructToNodeMap[reversePostOrderMap[dominators[i]].Construct];
node.Predecessor = immDom;
immDom.TreeEdgeSuccessors.Add(node);
}
}
/// <summary>
/// Sorts the intervals in Reverse post order.
/// </summary>
/// <param name="intervals">The intervals to be sorted.</param>
/// <returns>Returns sorted list of intervals.</returns>
private List <IntervalConstruct> SortIntervalList(List <IntervalConstruct> intervals)
{
IntervalConstruct intervalGraph = new IntervalConstruct(intervals[0]);
foreach (ISingleEntrySubGraph interval in intervals)
{
intervalGraph.Children.Add(interval);
}
DFSTree dfsTree = DFSTBuilder.BuildTree(intervalGraph);
List <IntervalConstruct> sortedList = new List <IntervalConstruct>();
foreach (DFSTNode node in dfsTree.ReversePostOrder)
{
sortedList.Add(node.Construct as IntervalConstruct);
}
return(sortedList);
}
/// <summary>
/// Removes back edges from switch blocks. Switch cases can not form a loop. If the control flow forms a loop, it should be represented by goto-label contructs.
/// </summary>
/// <param name="theConstruct">The construct, that might contain switches.</param>
private void RemoveBackEdgesFromSwitchConstructs(ILogicalConstruct theConstruct)
{
DFSTree dfsTree = DFSTBuilder.BuildTree(theConstruct);
foreach (DFSTEdge edge in dfsTree.BackEdges)
{
ILogicalConstruct startConstruct = edge.Start.Construct as ILogicalConstruct;
if (startConstruct is ConditionLogicalConstruct)
{
continue;
}
CFGBlockLogicalConstruct startCfgConstruct = startConstruct as CFGBlockLogicalConstruct;
if ((startCfgConstruct != null && startCfgConstruct.TheBlock.Last.OpCode.Code == Mono.Cecil.Cil.Code.Switch))
{
MarkAsGotoEdge(startConstruct, edge.End.Construct as ILogicalConstruct);
}
}
}
/// <summary>
/// Removes and edge, that is preventing the reducibillity of the graph.
/// </summary>
/// <param name="intervals">The graph, that can't be reduced.</param>
private void RemoveBlockingEdges(List <IntervalConstruct> intervals)
{
//Creating this interval, so that it holds the interval tree
//This way we can use the DFSTree.
IntervalConstruct allIntervals = new IntervalConstruct(intervals[0]);
for (int i = 1; i < intervals.Count; i++)
{
allIntervals.Children.Add(intervals[i]);
}
DFSTree dfsTree = DFSTBuilder.BuildTree(allIntervals);
/// Blocking edge can be either cross edge or back edge.
/// If a backedge is detected, that means it wasn't converted in loop, so it must be marked as goto.
DFSTEdge edgeToDelete = dfsTree.BackEdges.FirstOrDefault();
if (edgeToDelete == null)
{
edgeToDelete = dfsTree.CrossEdges.FirstOrDefault();
}
//both should not be null, since the DFS was ran onto intervals tree
IntervalConstruct edgeStart = edgeToDelete.Start.Construct as IntervalConstruct;
IntervalConstruct edgeEnd = edgeToDelete.End.Construct as IntervalConstruct;
//Find all logical constructs that make the intervals have this edge between them.
foreach (ILogicalConstruct edgeEndPredecessor in edgeEnd.Entry.SameParentPredecessors)
{
if (edgeStart.Children.Contains(edgeEndPredecessor))
{
ILogicalConstruct constructEdgeStart = edgeEndPredecessor;
ILogicalConstruct constructEdgeEnd = edgeEnd.Entry as ILogicalConstruct;
HashSet <ILogicalConstruct> removedEdgeInfo;
if (!removedEdges.TryGetValue(constructEdgeStart, out removedEdgeInfo) || !removedEdgeInfo.Contains(constructEdgeEnd))
{
MarkAsGotoEdge(constructEdgeStart, constructEdgeEnd);
return;
}
}
}
}
/// <summary>
/// Removes backedges exiting from <paramref name="loopConstruct"/>.
/// </summary>
/// <param name="loopConstruct">The loop construct.</param>
private void CleanUpEdges(LoopLogicalConstruct loopConstruct)
{
DFSTree dfsTree = DFSTBuilder.BuildTree(loopConstruct.Parent);
DFSTNode loopNode = dfsTree.ConstructToNodeMap[loopConstruct];
if (loopNode.BackEdgeSuccessors.Count == 0)
{
return;
}
foreach (DFSTNode backedgeSuccessor in loopNode.BackEdgeSuccessors)
{
ILogicalConstruct edgeEndConstruct = backedgeSuccessor.Construct as ILogicalConstruct;
if (!(edgeEndConstruct is ConditionLogicalConstruct)) /// if the target is ConditionLogicalConstruct, it can probably be a header of outer loop
{
MarkAsGotoEdge(loopConstruct, backedgeSuccessor.Construct as ILogicalConstruct);
}
}
}
private void ProcessSwitchConstructs(ILogicalConstruct parent, List <CFGBlockLogicalConstruct> switchBlocks)
{
V_0 = new SwitchBuilder.u003cu003ec__DisplayClass5_0();
V_1 = this.GetDominatorTreeFromContext(parent);
V_0.dfsTree = DFSTBuilder.BuildTree(parent);
switchBlocks.Sort(new Comparison <CFGBlockLogicalConstruct>(V_0.u003cProcessSwitchConstructsu003eb__0));
V_2 = switchBlocks.GetEnumerator();
try
{
while (V_2.MoveNext())
{
V_3 = V_2.get_Current();
this.CreateSwitchConstruct(V_3, parent, this.logicalContext.get_CFG().get_SwitchBlocksInformation().get_Item(V_3.get_TheBlock()), V_1);
}
}
finally
{
((IDisposable)V_2).Dispose();
}
return;
}
private void GetOrderedCFGNodes()
{
V_0 = DFSTBuilder.BuildTree(this.theBlock).get_ReversePostOrder().GetEnumerator();
try
{
while (V_0.MoveNext())
{
V_1 = V_0.get_Current().get_Construct() as CFGBlockLogicalConstruct;
if (V_1 == null)
{
continue;
}
this.orderedCFGNodes.Add(V_1);
}
}
finally
{
((IDisposable)V_0).Dispose();
}
return;
}
private Dictionary <ILogicalConstruct, HashSet <ISingleEntrySubGraph> > GetValidCases(DominatorTree dominatorTree, ILogicalConstruct switchCFGBlock)
{
Dictionary <ILogicalConstruct, HashSet <ISingleEntrySubGraph> > caseEntriesToDominatedNodesMap = new Dictionary <ILogicalConstruct, HashSet <ISingleEntrySubGraph> >();
HashSet <ISingleEntrySubGraph> legalPredecessors = new HashSet <ISingleEntrySubGraph>();
legalPredecessors.Add(switchCFGBlock);
foreach (ILogicalConstruct successor in switchCFGBlock.SameParentSuccessors)
{
if (successor != switchCFGBlock && dominatorTree.GetImmediateDominator(successor) == switchCFGBlock)
{
HashSet <ISingleEntrySubGraph> dominatedNodes = dominatorTree.GetDominatedNodes(successor);
caseEntriesToDominatedNodesMap.Add(successor, dominatedNodes);
legalPredecessors.UnionWith(dominatedNodes);
}
}
DFSTree dfsTree = DFSTBuilder.BuildTree(switchCFGBlock.Parent, switchCFGBlock);
List <ILogicalConstruct> orderedCaseEntries =
new List <ILogicalConstruct>(dfsTree.ReversePostOrder.Select(node => node.Construct as ILogicalConstruct).Where(construct => caseEntriesToDominatedNodesMap.ContainsKey(construct)));
bool changed;
do
{
changed = false;
foreach (ILogicalConstruct caseEntry in orderedCaseEntries)
{
HashSet <ISingleEntrySubGraph> dominatedNodes;
if (caseEntriesToDominatedNodesMap.TryGetValue(caseEntry, out dominatedNodes) && !IsCaseValid(caseEntry, legalPredecessors))
{
legalPredecessors.ExceptWith(dominatedNodes);
caseEntriesToDominatedNodesMap.Remove(caseEntry);
changed = true;
}
}
} while (changed);
return(caseEntriesToDominatedNodesMap);
}
private void BuildIfConstructs(ILogicalConstruct construct)
{
V_0 = this.GetDominatorTreeFromContext(construct);
V_1 = DFSTBuilder.BuildTree(construct);
V_2 = this.GetPostOrderedIfConditionCandidates(V_1).GetEnumerator();
try
{
while (V_2.MoveNext())
{
V_3 = V_2.get_Current();
dummyVar0 = this.TryBuildIfConstruct(V_3, V_0, V_1);
}
}
finally
{
if (V_2 != null)
{
V_2.Dispose();
}
}
return;
}
private LoopType DetermineLoopType(HashSet <ILogicalConstruct> loopBody, HashSet <ILogicalConstruct> latchingNodes, IntervalConstruct interval, DominatorTree dominatorTree, out ConditionLogicalConstruct loopCondition)
{
V_0 = interval.get_Entry() as ILogicalConstruct;
V_1 = new HashSet <ILogicalConstruct>(latchingNodes);
dummyVar0 = V_1.Add(V_0);
V_2 = DFSTBuilder.BuildTree(V_0.get_Parent() as ILogicalConstruct);
V_3 = new HashSet <ILogicalConstruct>();
V_4 = loopBody.GetEnumerator();
try
{
while (V_4.MoveNext())
{
V_5 = V_4.get_Current();
V_6 = dominatorTree.GetDominanceFrontier(V_5).GetEnumerator();
try
{
while (V_6.MoveNext())
{
V_7 = (ILogicalConstruct)V_6.get_Current();
if (!interval.get_Children().Contains(V_7) || loopBody.Contains(V_7))
{
continue;
}
dummyVar1 = V_3.Add(V_7);
}
}
finally
{
((IDisposable)V_6).Dispose();
}
}
}
finally
{
((IDisposable)V_4).Dispose();
}
if (V_3.get_Count() == 0)
{
V_8 = V_2.get_ReversePostOrder().GetEnumerator();
try
{
while (V_8.MoveNext())
{
V_9 = V_8.get_Current().get_Construct() as ILogicalConstruct;
if (loopBody.Contains(V_9))
{
continue;
}
loopCondition = this.GetLoopConditionWithMaxIndex(V_2, loopBody, V_1, V_9);
if (loopCondition == null)
{
continue;
}
this.ExpandLoopBody(interval, loopBody, V_9);
if (loopCondition != V_0)
{
V_10 = 2;
goto Label1;
}
else
{
V_10 = 1;
goto Label1;
}
}
goto Label0;
}
finally
{
((IDisposable)V_8).Dispose();
}
Label1:
return(V_10);
}
V_11 = V_2.get_ReversePostOrder().get_Count();
V_4 = V_3.GetEnumerator();
try
{
while (V_4.MoveNext())
{
V_13 = V_4.get_Current();
V_14 = V_2.get_ConstructToNodeMap().get_Item(V_13).get_ReversePostOrderIndex();
if (V_14 >= V_11)
{
continue;
}
V_11 = V_14;
}
}
finally
{
((IDisposable)V_4).Dispose();
}
V_12 = V_2.get_ReversePostOrder().get_Item(V_11).get_Construct() as ILogicalConstruct;
loopCondition = this.GetLoopConditionWithMaxIndex(V_2, loopBody, V_1, V_12);
this.ExpandLoopBody(interval, loopBody, V_12);
if (loopCondition == null)
{
return(0);
}
if (loopCondition == V_0)
{
return(1);
}
return(2);
Label0:
if (!this.CanBeLoopCondition(V_0, loopBody))
{
loopCondition = null;
return(0);
}
loopCondition = V_0 as ConditionLogicalConstruct;
return(1);
}
/// <summary>
/// Determines the type of the loop and the condition of the loop. Adds additional nodes into the loop body.
/// </summary>
/// <param name="loopBody"></param>
/// <param name="header"></param>
/// <param name="latchingNodes"></param>
/// <param name="interval"></param>
/// <param name="loopCondition"></param>
/// <returns></returns>
private LoopType DetermineLoopType(HashSet <ILogicalConstruct> loopBody, HashSet <ILogicalConstruct> latchingNodes,
IntervalConstruct interval, DominatorTree dominatorTree, out ConditionLogicalConstruct loopCondition)
{
ILogicalConstruct header = interval.Entry as ILogicalConstruct;
HashSet <ILogicalConstruct> legalExits = new HashSet <ILogicalConstruct>(latchingNodes);
legalExits.Add(header);
ILogicalConstruct parentConstruct = header.Parent as ILogicalConstruct;
DFSTree dfsTree = DFSTBuilder.BuildTree(parentConstruct);
//B - nodes in the loop body (= loopBody)
//I - nodes in the interval (= interval.Children)
//U - union of all of the dominance frontiers of the nodes in B
//exitDominanceFrontier = (U n I) \ B
//If a node is in the exitDominanceFrontier, then it is dominated by the header and is a successor (not necessarily direct) of more than one
//node in the loop body.
HashSet <ILogicalConstruct> exitDominanceFrontier = new HashSet <ILogicalConstruct>();
foreach (ILogicalConstruct loopNode in loopBody)
{
foreach (ILogicalConstruct frontierNode in dominatorTree.GetDominanceFrontier(loopNode))
{
if (interval.Children.Contains(frontierNode) && !loopBody.Contains(frontierNode))
{
exitDominanceFrontier.Add(frontierNode);
}
}
}
//This is leftover heuristic, that was used for determining a suitable successor that is going to be follow node of the loop.
//Changing it now will break a good number of the tests. Since the produced output is acceptable, until a better heuristic is found
//there is no need to change it.
if (exitDominanceFrontier.Count == 0)
{
//If the exit dominance frontier is empty then we look for the node, with minimum post order index, that is a successor of a condition loop exit.
//The desired exit should be a condition in order to reduce the number of infinite loops (heuristic).
foreach (DFSTNode dfsNode in dfsTree.ReversePostOrder)
{
ILogicalConstruct construct = dfsNode.Construct as ILogicalConstruct;
if (loopBody.Contains(construct))
{
continue;
}
loopCondition = GetLoopConditionWithMaxIndex(dfsTree, loopBody, legalExits, construct);
//By taking the successor with the minimum post order index and the loop exit with the maximum post order index, we ensure that
//the produced construct will always be the same, since the post order in our case is a total order.
//There are other various ways of finding the exit-successor pair that can bring consistent output, but none of them is found to yield
//better results than the rest.
if (loopCondition != null)
{
//We expand the loop body only when we've found a condition successor of the loop.
//This is done in order to avoid adding all of the dominated nodes of an infinite loop to the body. (Better readability of the final code.)
//E.g.: An infinite loop on the top level of the logical tree (i.e. child of the method block construct). If it dominates all of its
//succeeding nodes then they will be in its interval, which means that they will be added to the loop. As a result there will
//be an infinite loop at the end of the method, that encloses a cood part of the code, for no apparent reason.
ExpandLoopBody(interval, loopBody, construct);
if (loopCondition == header)
{
return(LoopType.PreTestedLoop);
}
else
{
return(LoopType.PostTestedLoop);
}
}
}
if (CanBeLoopCondition(header, loopBody))
{
loopCondition = header as ConditionLogicalConstruct;
return(LoopType.PreTestedLoop);
}
else
{
loopCondition = null;
return(LoopType.InfiniteLoop);
}
}
else
{
//If there are nodes in the exitDominanceFrontier, then we choose the one with the minimum postorder index for successor of the loop.
//Then we try to find a condition exit of the loop, with maximum post order index, that is predecessor of the successor node.
int minOrderIndexOfSuccessor = dfsTree.ReversePostOrder.Count;
foreach (ILogicalConstruct successor in exitDominanceFrontier)
{
int currentOrderIndex = dfsTree.ConstructToNodeMap[successor].ReversePostOrderIndex;
if (currentOrderIndex < minOrderIndexOfSuccessor)
{
minOrderIndexOfSuccessor = currentOrderIndex;
}
}
ILogicalConstruct loopSuccessor = dfsTree.ReversePostOrder[minOrderIndexOfSuccessor].Construct as ILogicalConstruct;
loopCondition = GetLoopConditionWithMaxIndex(dfsTree, loopBody, legalExits, loopSuccessor);
ExpandLoopBody(interval, loopBody, loopSuccessor);
if (loopCondition != null)
{
if (loopCondition == header)
{
return(LoopType.PreTestedLoop);
}
else
{
return(LoopType.PostTestedLoop);
}
}
else
{
return(LoopType.InfiniteLoop);
}
}
}