/**
* given a DelayabilityAnalysis and the computations of each unit, calculates the latest
* computation-point for each expression.<br>
* the <code>equivRhsMap</code> could be calculated on the fly, but it is <b>very</b> likely that
* it already exists (as similar maps are used for calculating Earliestness, Delayed,...<br>
* the shared set allows more efficient set-operations, when they the computation is merged with
* other analyses/computations.
*
* @param dg a ExceptionalUnitGraph
* @param delayed the delayability-analysis of the same graph.
* @param equivRhsMap all computations of the graph
* @param set the shared flowSet
*/
public LatestComputation(
UnitGraph unitGraph, DelayabilityAnalysis delayed, Map equivRhsMap, BoundedFlowSet set) {
unitToLatest = new HashMap<Unit, FlowSet>(unitGraph.size() + 1, 0.7f);
Iterator unitIt = unitGraph.iterator();
while (unitIt.hasNext()) {
/* create a new Earliest-list for each unit */
Unit currentUnit = (Unit) unitIt.next();
/* basically the latest-set is:
* (delayed) INTERSECT (comp UNION (UNION_successors ~Delayed)) =
* (delayed) MINUS ((INTERSECTION_successors Delayed) MINUS comp).
*/
FlowSet delaySet = (FlowSet) delayed.getFlowBefore(currentUnit);
/* Calculate (INTERSECTION_successors Delayed) */
FlowSet succCompSet = (FlowSet) set.topSet();
List succList = unitGraph.getSuccsOf(currentUnit);
Iterator succIt = succList.iterator();
while (succIt.hasNext()) {
Unit successor = (Unit) succIt.next();
succCompSet.intersection((FlowSet) delayed.getFlowBefore(successor), succCompSet);
}
/* remove the computation of this set: succCompSet is then:
* ((INTERSECTION_successors Delayed) MINUS comp) */
if (equivRhsMap.get(currentUnit) != null) succCompSet.remove(equivRhsMap.get(currentUnit));
/* make the difference: */
FlowSet latest = (FlowSet) delaySet.emptySet();
delaySet.difference(succCompSet, latest);
unitToLatest.put(currentUnit, latest);
}
}
