void ChangeEdgeStatus(ControlFlowEdge edge, DefiniteAssignmentStatus newStatus)
{
DefiniteAssignmentStatus oldStatus = edgeStatus[edge];
if (oldStatus == newStatus)
{
return;
}
// Ensure that status can cannot change back to CodeUnreachable after it once was reachable.
// Also, don't ever use AssignedAfter... for statements.
if (newStatus == DefiniteAssignmentStatus.CodeUnreachable ||
newStatus == DefiniteAssignmentStatus.AssignedAfterFalseExpression ||
newStatus == DefiniteAssignmentStatus.AssignedAfterTrueExpression)
{
throw new InvalidOperationException();
}
// Note that the status can change from DefinitelyAssigned
// back to PotentiallyAssigned as unreachable input edges are
// discovered to be reachable.
edgeStatus[edge] = newStatus;
DefiniteAssignmentNode targetNode = (DefiniteAssignmentNode)edge.To;
if (analyzedRangeStart <= targetNode.Index && targetNode.Index <= analyzedRangeEnd)
{
// TODO: potential optimization: visit previously unreachable nodes with higher priority
// (e.g. use Deque and enqueue previously unreachable nodes at the front, but
// other nodes at the end)
nodesWithModifiedInput.Enqueue(targetNode);
}
}
internal ControlFlowEdge Connect(ControlFlowNode from, ControlFlowNode to, ControlFlowEdgeType type = ControlFlowEdgeType.Normal)
{
if (from == null || to == null)
{
return(null);
}
ControlFlowEdge edge = builder.CreateEdge(from, to, type);
from.Outgoing.Add(edge);
to.Incoming.Add(edge);
return(edge);
}