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 static void checkRedundantProxy(ProxyNode vpn) {
AbstractBeginNode proxyPoint = vpn.proxyPoint();
if (proxyPoint instanceof LoopExitNode) {
LoopExitNode exit = (LoopExitNode) proxyPoint;
LoopBeginNode loopBegin = exit.loopBegin();
ValueNode vpnValue = vpn.value();
for (ValueNode v : loopBegin.stateAfter().values()) {
ValueNode v2 = v;
if (loopBegin.isPhiAtMerge(v2)) {
v2 = ((PhiNode) v2).valueAt(loopBegin.forwardEnd());
}
if (vpnValue == v2) {
Collection<PhiNode> phiUsages = vpn.usages().filter(PhiNode.class).snapshot();
Collection<ProxyNode> proxyUsages = vpn.usages().filter(ProxyNode.class).snapshot();
vpn.graph().replaceFloating(vpn, vpnValue);
for (PhiNode phi : phiUsages) {
checkRedundantPhi(phi);
}
for (ProxyNode proxy : proxyUsages) {
checkRedundantProxy(proxy);
}
return;
}
}
}
}
private void visitForward(NodeBitMap visited, Node node) {
if (node != null && !visited.isMarked(node)) {
visited.mark(node);
if (node.predecessor() != null) {
visitForward(visited, node.predecessor());
}
if (node instanceof MergeNode) {
// make sure that the cfg predecessors of a MergeNode are processed first
MergeNode merge = (MergeNode) node;
for (int i = 0; i < merge.forwardEndCount(); i++) {
visitForward(visited, merge.forwardEndAt(i));
}
}
for (Node input : node.inputs()) {
visitForward(visited, input);
}
if (node instanceof LoopBeginNode) {
LoopBeginNode loopBegin = (LoopBeginNode) node;
for (LoopEndNode loopEnd : loopBegin.loopEnds()) {
visitForward(visited, loopEnd);
}
}
nodes.add(node);
}
}
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);
}
}
public static void normalizeLoopBegin(LoopBeginNode begin) {
// Delete unnecessary loop phi functions, i.e., phi functions where all inputs are either
// the same or the phi itself.
for (PhiNode phi : begin.phis().snapshot()) {
GraphUtil.checkRedundantPhi(phi);
}
for (LoopExitNode exit : begin.loopExits()) {
for (ProxyNode vpn : exit.proxies().snapshot()) {
GraphUtil.checkRedundantProxy(vpn);
}
}
}
public void reduceTrivialMerge(AbstractMergeNode merge) {
assert merge.forwardEndCount() == 1;
assert !(merge instanceof LoopBeginNode) || ((LoopBeginNode) merge).loopEnds().isEmpty();
for (PhiNode phi : merge.phis().snapshot()) {
assert phi.valueCount() == 1;
ValueNode singleValue = phi.valueAt(0);
phi.replaceAtUsagesAndDelete(singleValue);
}
// remove loop exits
if (merge instanceof LoopBeginNode) {
((LoopBeginNode) merge).removeExits();
}
AbstractEndNode singleEnd = merge.forwardEndAt(0);
FixedNode sux = merge.next();
FrameState stateAfter = merge.stateAfter();
// evacuateGuards
merge.prepareDelete((FixedNode) singleEnd.predecessor());
merge.safeDelete();
if (stateAfter != null && stateAfter.isAlive() && stateAfter.hasNoUsages()) {
GraphUtil.killWithUnusedFloatingInputs(stateAfter);
}
if (sux == null) {
singleEnd.replaceAtPredecessor(null);
singleEnd.safeDelete();
} else {
singleEnd.replaceAndDelete(sux);
}
}
public void detectedCountedLoops() {
for (LoopEx loop : loops()) {
InductionVariables ivs = new InductionVariables(loop);
LoopBeginNode loopBegin = loop.loopBegin();
FixedNode next = loopBegin.next();
while (next instanceof FixedGuardNode || next instanceof ValueAnchorNode) {
next = ((FixedWithNextNode) next).next();
}
if (next instanceof IfNode) {
IfNode ifNode = (IfNode) next;
boolean negated = false;
if (!loopBegin.isLoopExit(ifNode.falseSuccessor())) {
if (!loopBegin.isLoopExit(ifNode.trueSuccessor())) {
continue;
}
negated = true;
}
LogicNode ifTest = ifNode.condition();
if (!(ifTest instanceof IntegerLessThanNode)) {
if (ifTest instanceof IntegerBelowThanNode) {
Debug.log("Ignored potential Counted loop at %s with |<|", loopBegin);
}
continue;
}
IntegerLessThanNode lessThan = (IntegerLessThanNode) ifTest;
Condition condition = null;
InductionVariable iv = null;
ValueNode limit = null;
if (loop.isOutsideLoop(lessThan.x())) {
iv = ivs.get(lessThan.y());
if (iv != null) {
condition = lessThan.condition().mirror();
limit = lessThan.x();
}
} else if (loop.isOutsideLoop(lessThan.y())) {
iv = ivs.get(lessThan.x());
if (iv != null) {
condition = lessThan.condition();
limit = lessThan.y();
}
}
if (condition == null) {
continue;
}
if (negated) {
condition = condition.negate();
}
boolean oneOff = false;
switch (condition) {
case LE:
oneOff = true; // fall through
case LT:
if (iv.direction() != Direction.Up) {
continue;
}
break;
case GE:
oneOff = true; // fall through
case GT:
if (iv.direction() != Direction.Down) {
continue;
}
break;
default:
throw GraalInternalError.shouldNotReachHere();
}
loop.setCounted(
new CountedLoopInfo(
loop,
iv,
limit,
oneOff,
negated ? ifNode.falseSuccessor() : ifNode.trueSuccessor()));
}
}
}
