public static IRControlFlowGraph Build(IRMethod pMethod)
{
if (pMethod.Instructions.Count == 0) return null;
HashSet<IRInstruction> sourceNodeBreaks = new HashSet<IRInstruction>();
HashSet<IRInstruction> destinationNodeBreaks = new HashSet<IRInstruction>();
int lIRIdx = pMethod.Instructions.Count - 1;
foreach (IRInstruction instruction in pMethod.Instructions)
{
bool lastInstruction = instruction.IRIndex == lIRIdx;
switch (instruction.Opcode)
{
case IROpcode.Branch:
{
IRBranchInstruction branchInstruction = (IRBranchInstruction)instruction;
sourceNodeBreaks.Add(instruction);
destinationNodeBreaks.Add(branchInstruction.TargetIRInstruction);
break;
}
case IROpcode.Switch:
{
IRSwitchInstruction switchInstruction = (IRSwitchInstruction)instruction;
sourceNodeBreaks.Add(instruction);
switchInstruction.TargetIRInstructions.ForEach(i => destinationNodeBreaks.Add(i));
break;
}
case IROpcode.Leave:
{
IRLeaveInstruction leaveInstruction = (IRLeaveInstruction)instruction;
sourceNodeBreaks.Add(instruction);
destinationNodeBreaks.Add(leaveInstruction.TargetIRInstruction);
break;
}
case IROpcode.EndFinally:
{
IREndFinallyInstruction endFinallyInstruction = (IREndFinallyInstruction)instruction;
sourceNodeBreaks.Add(instruction);
if (!lastInstruction) destinationNodeBreaks.Add(pMethod.Instructions[instruction.IRIndex + 1]);
break;
}
case IROpcode.Throw:
case IROpcode.Rethrow:
case IROpcode.Return:
sourceNodeBreaks.Add(instruction);
break;
default: break;
}
}
IRControlFlowGraph cfg = new IRControlFlowGraph();
IRControlFlowGraphNode currentNode = new IRControlFlowGraphNode(0);
cfg.Nodes.Add(currentNode);
foreach (IRInstruction instruction in pMethod.Instructions)
{
bool lastInstruction = instruction.IRIndex == lIRIdx;
bool startFromSource = sourceNodeBreaks.Contains(instruction);
bool startFromDestination = destinationNodeBreaks.Contains(instruction);
if (startFromSource && startFromDestination)
{
if (currentNode.Instructions.Count > 0)
{
currentNode = new IRControlFlowGraphNode(cfg.Nodes.Count);
cfg.Nodes.Add(currentNode);
}
currentNode.Instructions.Add(instruction);
if (!lastInstruction)
{
currentNode = new IRControlFlowGraphNode(cfg.Nodes.Count);
cfg.Nodes.Add(currentNode);
}
}
else if (startFromSource)
{
currentNode.Instructions.Add(instruction);
if (!lastInstruction)
{
currentNode = new IRControlFlowGraphNode(cfg.Nodes.Count);
cfg.Nodes.Add(currentNode);
}
}
else if (startFromDestination)
{
if (currentNode.Instructions.Count > 0)
{
currentNode = new IRControlFlowGraphNode(cfg.Nodes.Count);
cfg.Nodes.Add(currentNode);
}
currentNode.Instructions.Add(instruction);
}
else currentNode.Instructions.Add(instruction);
}
foreach (IRControlFlowGraphNode node in cfg.Nodes)
{
IRInstruction instruction = node.Instructions[node.Instructions.Count - 1];
switch (instruction.Opcode)
{
case IROpcode.Branch:
{
IRBranchInstruction branchInstruction = (IRBranchInstruction)instruction;
IRControlFlowGraphNode childNode = cfg.Nodes.Find(n => n.Instructions[0] == branchInstruction.TargetIRInstruction);
if (childNode == null) throw new NullReferenceException();
if (branchInstruction.BranchCondition != IRBranchCondition.Always) node.LinkTo(cfg.Nodes[node.Index + 1]);
node.LinkTo(childNode);
break;
}
case IROpcode.Switch:
{
IRSwitchInstruction switchInstruction = (IRSwitchInstruction)instruction;
node.LinkTo(cfg.Nodes[node.Index + 1]);
foreach (IRInstruction targetInstruction in switchInstruction.TargetIRInstructions)
{
IRControlFlowGraphNode childNode = cfg.Nodes.Find(n => n.Instructions[0] == targetInstruction);
if (childNode == null) throw new NullReferenceException();
node.LinkTo(childNode);
}
break;
}
case IROpcode.Leave:
{
IRLeaveInstruction leaveInstruction = (IRLeaveInstruction)instruction;
IRControlFlowGraphNode childNode = cfg.Nodes.Find(n => n.Instructions[0] == leaveInstruction.TargetIRInstruction);
if (childNode == null) throw new NullReferenceException();
node.LinkTo(childNode);
break;
}
case IROpcode.Throw:
case IROpcode.Rethrow:
case IROpcode.Return: continue;
default: if (cfg.Nodes.Count > node.Index + 1) node.LinkTo(cfg.Nodes[node.Index + 1]); break;
}
}
List<IRControlFlowGraphNode> allDeadNodes = new List<IRControlFlowGraphNode>(32);
List<IRControlFlowGraphNode> deadNodes = null;
while ((deadNodes = cfg.Nodes.FindAll(n => n.Index > 0 && n.ParentNodes.Count == 0)).Count > 0)
{
allDeadNodes.AddRange(deadNodes);
foreach (IRControlFlowGraphNode deadNode in deadNodes)
{
foreach (IRControlFlowGraphNode childNode in deadNode.ChildNodes) childNode.ParentNodes.Remove(deadNode);
cfg.Nodes.RemoveAt(deadNode.Index);
for (int nodeIndex = deadNode.Index; nodeIndex < cfg.Nodes.Count; ++nodeIndex)
{
IRControlFlowGraphNode node = cfg.Nodes[nodeIndex];
node.Index -= 1;
}
}
}
cfg.Nodes.ForEach(n => n.Dominators = new BitVector(cfg.Nodes.Count, true));
BitVector intersectedParentDominators = new BitVector(cfg.Nodes.Count);
HashSet<IRControlFlowGraphNode> todoSet = new HashSet<IRControlFlowGraphNode>();
HashSet<IRControlFlowGraphNode>.Enumerator todoSetEnumerator;
todoSet.Add(cfg.Nodes[0]);
while (todoSet.Count > 0)
{
todoSetEnumerator = todoSet.GetEnumerator();
todoSetEnumerator.MoveNext();
IRControlFlowGraphNode node = todoSetEnumerator.Current;
todoSet.Remove(node);
intersectedParentDominators.SetAll(node.ParentNodes.Count > 0);
node.ParentNodes.ForEach(n => intersectedParentDominators.AndEquals(n.Dominators));
intersectedParentDominators.Set(node.Index, true);
if (!intersectedParentDominators.Equals(node.Dominators))
{
node.Dominators = new BitVector(intersectedParentDominators);
node.ChildNodes.ForEach(n => todoSet.Add(n));
}
}
foreach (IRControlFlowGraphNode node in cfg.Nodes)
{
for (int index = 0; index < node.Dominators.Count; ++index)
{
if (node.Dominators.Get(index))
node.DominatorsCount++;
}
}
foreach (IRControlFlowGraphNode node in cfg.Nodes)
{
int max = -1;
foreach (IRControlFlowGraphNode innerNode in cfg.Nodes)
{
if (node.Dominators.Get(innerNode.Index) && node != innerNode && innerNode.DominatorsCount > max)
{
max = innerNode.DominatorsCount;
node.Dominator = innerNode;
}
}
}
cfg.Nodes[0].Dominator = cfg.Nodes[0];
foreach (IRControlFlowGraphNode node in cfg.Nodes)
{
if (node.ParentNodes.Count < 2) continue;
foreach (IRControlFlowGraphNode parentNode in node.ParentNodes)
{
IRControlFlowGraphNode treeNode = parentNode;
while (treeNode != node.Dominator)
{
treeNode.Frontiers.Add(node);
treeNode = treeNode.Dominator;
}
}
}
return cfg;
}