/// <summary>
/// Constructs the dominators for the given control flow graph.
/// </summary>
/// <param name="cfg">The control flow graph.</param>
private Dominators(CFG cfg)
{
CFG = cfg ?? throw new ArgumentNullException(nameof(cfg));
idomsInRPO = new int[cfg.Count];
nodesInRPO = new CFG.Node[cfg.Count];
idomsInRPO[0] = 0;
for (int i = 1, e = idomsInRPO.Length; i < e; ++i)
{
idomsInRPO[i] = -1;
}
bool changed;
do
{
changed = false;
using (var enumerator = cfg.GetEnumerator())
{
enumerator.MoveNext();
var node = enumerator.Current;
nodesInRPO[node.RPONumber] = node;
while (enumerator.MoveNext())
{
node = enumerator.Current;
nodesInRPO[node.RPONumber] = node;
int currentIdom = -1;
foreach (var pred in node.Predecessors)
{
var predRPO = pred.RPONumber;
if (idomsInRPO[predRPO] != -1)
{
currentIdom = predRPO;
break;
}
}
Debug.Assert(currentIdom != -1, "Invalid idom");
foreach (var pred in node.Predecessors)
{
var predRPO = pred.RPONumber;
if (idomsInRPO[predRPO] != -1)
{
currentIdom = Intersect(currentIdom, predRPO);
}
}
var rpoNumber = node.RPONumber;
if (idomsInRPO[rpoNumber] != currentIdom)
{
idomsInRPO[rpoNumber] = currentIdom;
changed = true;
}
}
}
}while (changed);
}
/// <summary>
/// Constructs the dominators for the given control-flow graph.
/// </summary>
/// <param name="cfg">The parent graph.</param>
private Dominators(CFG <DominanceOrder, TDirection> cfg)
{
idomsInRPO = new int[cfg.Count];
nodesInRPO = new BasicBlock[cfg.Count];
CFG = cfg;
Root = cfg.Root;
idomsInRPO[0] = 0;
for (int i = 1, e = idomsInRPO.Length; i < e; ++i)
{
idomsInRPO[i] = -1;
}
bool changed;
do
{
changed = false;
var enumerator = cfg.GetEnumerator();
enumerator.MoveNext();
var node = enumerator.Current;
nodesInRPO[node.TraversalIndex] = node;
while (enumerator.MoveNext())
{
node = enumerator.Current;
nodesInRPO[node.TraversalIndex] = node;
int currentIdom = -1;
foreach (var pred in node.Predecessors)
{
var predRPO = pred.TraversalIndex;
if (idomsInRPO[predRPO] != -1)
{
currentIdom = predRPO;
break;
}
}
Debug.Assert(currentIdom != -1, "Invalid idom");
foreach (var pred in node.Predecessors)
{
var predRPO = pred.TraversalIndex;
if (idomsInRPO[predRPO] != -1)
{
currentIdom = Intersect(currentIdom, predRPO);
}
}
var rpoNumber = node.TraversalIndex;
if (idomsInRPO[rpoNumber] != currentIdom)
{
idomsInRPO[rpoNumber] = currentIdom;
changed = true;
}
}
}while (changed);
}