/**
* Remove critical edges. A critical edge is an edge from a block with more than one successor to
* a block with more than one predecessor. Critical edges can hinder code motion and should be
* removed.
*/
private void removeCriticalEdges() {
LinkedList list = new LinkedList();
for (BasicBlock bb = firstBB; bb != null; bb = bb.getNext()) {
if (bb.getOutEdgesNumber() > 1) {
Iterator outEdges = bb.getOutEdges();
while (outEdges.hasNext()) {
Edge outEdge = (Edge) outEdges.next();
BasicBlock succ = (BasicBlock) outEdge.getTarget();
if (succ.getInEdgesNumber() > 1
&& !succ.isFirstBlockSubroutine()
&& !succ.isCatchBlock()) {
list.addLast(outEdge);
}
}
}
}
while (!list.isEmpty()) {
Edge edge = (Edge) list.removeFirst();
BasicBlock source = (BasicBlock) edge.getSource();
BasicBlock target = (BasicBlock) edge.getTarget();
if (source.getOutEdgesNumber() > 1 && target.getInEdgesNumber() > 1) {
// insert a new block in the CFG between source and target
BasicBlock insert = new BasicBlock(graph);
edge.getSource().changeEdgeTarget(edge, insert);
insert.addDefaultNextBlock(target);
// insert the new block before target in the trace
target.insertBefore(insert);
for (int i = 0; i < exceptionHandlers.length; ++i) {
if (exceptionHandlers[i].contains(target)) {
exceptionHandlers[i].addProtectedBlock(insert);
insert.addExceptionNextBlock(target);
}
}
}
}
}
