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 fall-through 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);
}
}
current.Instructions.Add(instruction);
connectWithPreviousNode = instruction.CanFallThroughNextInstruction();
IList <string> targets;
var isBranch = instruction.IsBranch(out targets);
var isExitingMethod = instruction.IsExitingMethod();
if (isBranch)
{
foreach (var label in targets)
{
var target = leaders[label];
cfg.ConnectNodes(current, target);
}
}
else if (isExitingMethod)
{
//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);
}
private void ConnectNodesWithExceptionHandlers(ControlFlowGraph cfg, IDictionary <string, CFGNode> leaders)
{
var activeProtectedBlocks = new HashSet <ProtectedBlock>();
var protectedBlocksStart = methodBody.ExceptionInformation.ToLookup(pb => pb.Start);
var protectedBlocksEnd = methodBody.ExceptionInformation.ToLookup(pb => pb.End);
var orderedLeaders = from entry in leaders
where entry.Value.Instructions.Any()
orderby entry.Value.StartOffset()
select entry;
foreach (var entry in orderedLeaders)
{
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);
}
}
}
