/* This only does forward analysis so far. We might need to make it
* do backward analysis at some point. */
public void Compute()
{
/* Initialize nodes */
foreach (Node node in cfg.Nodes)
{
outFact[node] = analysis.NewTop();
if (cfg.BeginsCatch((BasicBlock)node))
{
/* Catch nodes start with one thing on the stack. */
inFact[node] = analysis.NewCatch();
}
else if (cfg.Predecessors(node).Count > 0)
{
inFact[node] = analysis.NewTop();
}
else
{
inFact[node] = analysis.NewEntry();
}
}
DFS dfs = new DFS(cfg, cfg.EntryPoint);
dfs.Traverse();
/* Calculate the fixpoint of the dataflow equations. */
bool changed;
int iteration = 0;
do
{
if (Verbose)
{
Trace.WriteLine(string.Format("-------- iteration {0}", iteration));
}
iteration++;
changed = false;
foreach (object o in dfs.OrderedNodes)
{
Node node = (Node)o;
foreach (object pred in cfg.Predecessors(node))
{
analysis.MeetInto(inFact[node], outFact[pred], false);
}
object temp = ((ICloneable)inFact[node]).Clone();
analysis.Transfer(node, inFact[node], temp, false);
if (!temp.Equals(outFact[node]))
{
changed = true;
/* No need to assign new out fact unless changed. */
outFact[node] = temp;
}
}
} while(changed);
/* Run one final iteration with checking enabled. This is where
* warnings will be presented. Because nothing changed in the
* last iteration, nothing should change during this one. The
* loop iterates over the nodes in CFG order, rather than DFS
* order, so that messages will be sorted by location. */
if (Verbose)
{
Trace.WriteLine("-------- final iteration");
}
foreach (object o in cfg.Nodes)
{
Node node = (Node)o;
foreach (object pred in cfg.Predecessors(node))
{
analysis.MeetInto(inFact[node], outFact[pred], true);
}
object temp = ((ICloneable)inFact[node]).Clone();
analysis.Transfer(node, inFact[node], temp, true);
}
}
