private static void ConnectNodesWithExceptionHandlers(ControlFlowGraph cfg, IEnumerable <ProtectedBlock> protectedBlocks, IDictionary <string, CFGNode> leaders)
{
var activeProtectedBlocks = new HashSet <ProtectedBlock>();
var protectedBlocksStart = protectedBlocks.ToLookup(pb => pb.Start);
var protectedBlocksEnd = protectedBlocks.ToLookup(pb => pb.End);
foreach (var entry in leaders)
{
var label = entry.Key;
var node = entry.Value;
if (protectedBlocksStart.Contains(label))
{
var startingProtectedBlocks = protectedBlocksStart[label];
activeProtectedBlocks.UnionWith(startingProtectedBlocks);
}
if (protectedBlocksEnd.Contains(label))
{
var endingProtectedBlocks = protectedBlocksEnd[label];
activeProtectedBlocks.ExceptWith(endingProtectedBlocks);
}
// Connect each node inside a try block to the first corresponding handler block
foreach (var block in activeProtectedBlocks)
{
var target = leaders[block.Handler.Start];
cfg.ConnectNodes(node, target);
}
}
}
public static ControlFlowGraph GenerateNormalControlFlow(MethodBody method)
{
var instructions = ControlFlowGraph.FilterExceptionHandlers(method);
var leaders = ControlFlowGraph.CreateNodes(instructions);
var cfg = ControlFlowGraph.ConnectNodes(instructions, leaders);
return(cfg);
}
public static ControlFlowGraph GenerateExceptionalControlFlow(MethodBody method)
{
var instructions = method.Instructions;
var leaders = ControlFlowGraph.CreateNodes(instructions);
var cfg = ControlFlowGraph.ConnectNodes(instructions, leaders);
ControlFlowGraph.ConnectNodesWithExceptionHandlers(cfg, method.ProtectedBlocks, leaders);
return(cfg);
}
private static ControlFlowGraph ConnectNodes(IEnumerable <Instruction> instructions, IDictionary <string, CFGNode> leaders)
{
var cfg = new ControlFlowGraph();
var connectWithPreviousNode = true;
var current = cfg.Entry;
CFGNode previous;
foreach (var instruction in instructions)
{
if (leaders.ContainsKey(instruction.Label))
{
previous = current;
current = leaders[instruction.Label];
// A node cannot fallthrough itself,
// unless it contains another
// instruction with the same label
// of the node's leader instruction
if (connectWithPreviousNode && previous.Id != current.Id)
{
cfg.ConnectNodes(previous, current);
}
}
connectWithPreviousNode = true;
current.Instructions.Add(instruction);
if (instruction is BranchInstruction)
{
var branch = instruction as BranchInstruction;
var target = leaders[branch.Target];
cfg.ConnectNodes(current, target);
if (branch is UnconditionalBranchInstruction)
{
connectWithPreviousNode = false;
}
}
else if (instruction is SwitchInstruction)
{
var branch = instruction as SwitchInstruction;
foreach (var label in branch.Targets)
{
var target = leaders[label];
cfg.ConnectNodes(current, target);
}
}
else if (instruction is ReturnInstruction ||
instruction is ThrowInstruction)
{
//TODO: not always connect to exit, could exists a catch or finally block
cfg.ConnectNodes(current, cfg.Exit);
}
}
cfg.ConnectNodes(current, cfg.Exit);
return(cfg);
}
