//--//
public static bool IsAncestor(ITreeNode <FC> node,
ITreeNode <FC> child)
{
while (child != null)
{
if (node == child)
{
return(true);
}
ITreeNode <FC> nodeNext = null;
foreach (ITreeEdge <FC> edge in child.Predecessors)
{
if (edge.EdgeClass == EdgeClass.TreeEdge)
{
nodeNext = (ITreeNode <FC>)edge.Predecessor;
break;
}
}
CHECKS.ASSERT(nodeNext != null || child.Predecessors.Length == 0, "Child not a member of a spanning tree");
child = nodeNext;
}
return(false);
}
//--//
public ExpressionTree(T v)
{
CHECKS.ASSERT(v != null, "Cannot insert a null node is an expression tree!");
Left = Right = null;
Value = v;
}
private void ComputeImmediatePostDominators( )
{
int len = m_nodes.Length;
BitVector[] tmp = BitVector.AllocateBitVectors(len, len);
for (int n = 0; n < len; n++)
{
// Tmp(n) := PostDomin(n) - {n}
tmp[n].Assign(m_postDominance[n]);
tmp[n].Clear(n);
}
for (int n = 0; n < len; n++) // Walk the basic blocks in pre-order.
{
// for each n in N do
BitVector tmpN = tmp[n];
for (int s = 0; s < len; s++)
{
if (tmpN[s])
{
// for each s in Tmp(n) do
BitVector tmpS = tmp[s];
for (int t = 0; t < len; t++)
{
if (t != s && tmpN[t])
{
// for each t in Tmp(n) - {s} do
if (tmpS[t])
{
// if t in Tmp(s) then Tmp(n) -= {t}
tmpN.Clear(t);
}
}
}
}
}
}
m_immediatePostDominators = new N[len];
for (int n = 0; n < len; n++)
{
bool fGot = false;
foreach (int idom in tmp[n])
{
CHECKS.ASSERT(fGot == false, "Internal failure, found more than one immediate post dominators");
m_immediatePostDominators[n] = m_nodes[idom];
fGot = true;
}
}
}
//
// Helper Methods
//
private void ComputeDominators( )
{
//
// This is an implementation of the algorithm in "A Simple, Fast Dominance Algorithm", by Keith D. Cooper, Timothy J. Harvey, and Ken Kennedy.
//
// "for all nodes, b /* initialize the dominators array */
// doms[b] = Undefined
// doms[start_node] = start_node
// Changed = true
// while (Changed)
// Changed = false
// for all nodes, b, in reverse postorder (except start node)
// new_idom = first (processed) predecessor of b /* (pick one) */
// for all other predecessors, p, of b
// if doms[p] != Undefined /* i.e., if doms[p] already calculated */
// new_idom = intersect(p, new_idom)
// if doms[b] != new_idom
// doms[b] = new_idom
// Changed = true
//
// function intersect(b1, b2) returns node
// finger1 = b1
// finger2 = b2
// while (finger1 != finger2)
// while (finger1 < finger2)
// finger1 = doms[finger1]
// while (finger2 < finger1)
// finger2 = doms[finger2]
// return finger1"
//
int num = m_nodesPostOrder.Length;
m_immediateDominancePostOrder = new N[num];
N startNode = m_nodesSpanningTree[0];
SetIDom(startNode, startNode);
while (true)
{
bool fChanged = false;
for (int pos = num - 1; --pos >= 0;)
{
N nodeB = m_nodesPostOrder[pos];
CHECKS.ASSERT(!(nodeB is IEntryTreeNode <FC>), "Start node should not be processed by ImmediateDominance algorithm");
CHECKS.ASSERT(nodeB.Predecessors.Length > 0, "Node 'b' should have a predecessor: {0}", nodeB);
N first = null;
foreach (ITreeEdge <FC> edge in nodeB.Predecessors)
{
N node = (N)edge.Predecessor;
if (GetIDom(node) != null)
{
first = node;
break;
}
}
CHECKS.ASSERT(first != null, "Cannot find first (processed) predecessor of 'b'");
N new_idom = first;
foreach (ITreeEdge <FC> edge in nodeB.Predecessors)
{
N nodeP = (N)edge.Predecessor;
if (nodeP != first)
{
if (GetIDom(nodeP) != null)
{
new_idom = Intersect(nodeP, new_idom);
}
}
}
if (GetIDom(nodeB) != new_idom)
{
SetIDom(nodeB, new_idom);
fChanged = true;
}
}
if (!fChanged)
{
break;
}
}
//--//
//
// Finally, convert to an array in spanning-tree order.
//
m_immediateDominanceSpanningTree = new N[num];
for (int pos = 0; pos < num; pos++)
{
m_immediateDominanceSpanningTree[pos] = GetIDom(m_nodesSpanningTree[pos]);
}
}