/// <summary>
/// Removed error/continue edges which we know cannot happen due to type info
/// </summary>
/// <param name="graph"></param>
/// <param name="types"></param>
/// <returns></returns>
public static IControlFlowGraph TypeDrivenEdgeTrimming(this IControlFlowGraph graph, ITypeAssignments types)
{
return(graph.Trim(edge => {
// Find last statement in previous block
var stmt = edge.Start.Statements.LastOrDefault();
var tass = stmt as TypedAssignment;
var err = stmt as ErrorStatement;
// If type is unassigned we can't make a judgement
if (tass?.Type == Execution.Type.Unassigned)
{
return true;
}
if (edge.Type == EdgeType.RuntimeError)
{
// If it's an error statement keep it
if (err != null)
{
return true;
}
// If there is no statement at all then it can't be an error
if (tass == null)
{
return false;
}
// Only keep edge if type has an error
return tass.Type.HasFlag(Execution.Type.Error);
}
else
{
// If it's an error statement remove it
if (err != null)
{
return false;
}
// If there is no typed assignment we can't judge
if (tass == null)
{
return true;
}
return tass.Type != Execution.Type.Error;
}
}));
}
/// <summary>
/// Remove blocks that cannot be reached from the entry node
/// </summary>
/// <param name="graph"></param>
/// <returns></returns>
public static IControlFlowGraph RemoveUnreachableBlocks(this IControlFlowGraph graph)
{
var reachable = new HashSet <IBasicBlock>();
var queue = new Queue <IBasicBlock>();
void Mark(IBasicBlock block)
{
if (reachable.Add(block))
{
foreach (var edge in block.Outgoing)
{
queue.Enqueue(edge.End);
}
}
}
queue.Enqueue(graph.Vertices.Single(v => v.Type == BasicBlockType.Entry));
while (queue.Count > 0)
{
Mark(queue.Dequeue());
}
return(graph.Trim(reachable.Contains));
}