private static void killEnd(AbstractEndNode end) {
MergeNode merge = end.merge();
if (merge != null) {
merge.removeEnd(end);
StructuredGraph graph = end.graph();
if (merge instanceof LoopBeginNode && merge.forwardEndCount() == 0) { // dead loop
for (PhiNode phi : merge.phis().snapshot()) {
propagateKill(phi);
}
LoopBeginNode begin = (LoopBeginNode) merge;
// disconnect and delete loop ends & loop exits
for (LoopEndNode loopend : begin.loopEnds().snapshot()) {
loopend.predecessor().replaceFirstSuccessor(loopend, null);
loopend.safeDelete();
}
begin.removeExits();
FixedNode loopBody = begin.next();
if (loopBody != null) { // for small infinite loops, the body may be killed while
// killing the loop ends
killCFG(loopBody);
}
begin.safeDelete();
} else if (merge instanceof LoopBeginNode
&& ((LoopBeginNode) merge).loopEnds().isEmpty()) { // not
// a
// loop
// anymore
graph.reduceDegenerateLoopBegin((LoopBeginNode) merge);
} else if (merge.phiPredecessorCount() == 1) { // not a merge anymore
graph.reduceTrivialMerge(merge);
}
}
}
public void reduceDegenerateLoopBegin(LoopBeginNode begin) {
assert begin.loopEnds().isEmpty() : "Loop begin still has backedges";
if (begin.forwardEndCount() == 1) { // bypass merge and remove
reduceTrivialMerge(begin);
} else { // convert to merge
AbstractMergeNode merge = this.add(new MergeNode());
this.replaceFixedWithFixed(begin, merge);
}
}