private void CreateNodes(ControlFlowGraph <TInstruction> graph, IInstructionTraversalResult <TInstruction> traversalResult)
{
ControlFlowNode <TInstruction> currentNode = null;
foreach (var instruction in traversalResult.GetAllInstructions())
{
// Check if we reached a new block header.
long offset = Architecture.GetOffset(instruction);
if (currentNode == null || traversalResult.IsBlockHeader(offset))
{
// We arrived at a new basic block header. Create a new node for it.
currentNode = new ControlFlowNode <TInstruction>(offset);
graph.Nodes.Add(currentNode);
}
// Add the current instruction to the current block that we're populating.
currentNode.Contents.Instructions.Add(instruction);
// Edge case: Blocks might not come straight after each other. If we see that the next instruction
// does not exist, or the previous algorithm has decided the next instruction is a block header,
// we can create a new block in the next iteration.
long nextOffset = offset + Architecture.GetSize(instruction);
if (!traversalResult.ContainsInstruction(nextOffset) || traversalResult.IsBlockHeader(nextOffset))
{
currentNode = null;
}
}
}
private void ConnectNodes(ControlFlowGraph <TInstruction> graph, IInstructionTraversalResult <TInstruction> traversalResult)
{
var successorsBufferPool = ArrayPool <SuccessorInfo> .Shared;
var successorsBuffer = successorsBufferPool.Rent(2);
try
{
foreach (var node in graph.Nodes)
{
// Get the successors of the last instruction in the current block.
var block = node.Contents;
long footerOffset = Architecture.GetOffset(block.Instructions[block.Instructions.Count - 1]);
// Ensure the size of the successors buffer is big enough.
int successorCount = traversalResult.GetSuccessorCount(footerOffset);
if (successorsBuffer.Length < successorCount)
{
successorsBufferPool.Return(successorsBuffer);
successorsBuffer = successorsBufferPool.Rent(successorCount);
}
// Read successors.
var successorsBufferSlice = new Span <SuccessorInfo>(successorsBuffer, 0, successorCount);
int actualCount = traversalResult.GetSuccessors(footerOffset, successorsBufferSlice);
if (actualCount > successorCount)
{
throw new InvalidOperationException();
}
// Add edges accordingly.
for (int i = 0; i < actualCount; i++)
{
var successor = successorsBuffer[i];
var successorNode = graph.GetNodeByOffset(successor.DestinationAddress);
if (successorNode == null)
{
throw new ArgumentException($"Instruction at address {footerOffset:X8} refers to a non-existing node.");
}
node.ConnectWith(successorNode, successor.EdgeType);
}
}
}
finally
{
successorsBufferPool.Return(successorsBuffer);
}
}