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);
}
}
}
/**
* This method performs two kinds of cleanup:
*
* <ol>
* <li>marking as unreachable certain code-paths, as described in {@link
* com.oracle.graal.phases.common.cfs.BaseReduction.PostponedDeopt}
* <li>Removing nodes not in use that were added during this phase, as described next.
* </ol>
*
* <p>Methods like {@link
* com.oracle.graal.phases.common.cfs.FlowUtil#replaceInPlace(com.oracle.graal.graph.Node,
* com.oracle.graal.graph.Node, com.oracle.graal.graph.Node)} may result in old inputs becoming
* disconnected from the graph. It's not advisable to {@link
* com.oracle.graal.nodes.util.GraphUtil#tryKillUnused(com.oracle.graal.graph.Node)} at that
* moment, because one of the inputs that might get killed is one of {@link #nullConstant}, {@link
* #falseConstant}, or {@link #trueConstant}; which thus could get killed too early, before
* another invocation of {@link
* com.oracle.graal.phases.common.cfs.EquationalReasoner#deverbosify(com.oracle.graal.graph.Node)}
* needs them. To recap, {@link
* com.oracle.graal.nodes.util.GraphUtil#tryKillUnused(com.oracle.graal.graph.Node)} also
* recursively visits the inputs of the its argument.
*
* <p>This method goes over all of the nodes that deverbosification might have added, which are
* either:
*
* <ul>
* <li>{@link com.oracle.graal.nodes.calc.FloatingNode}, added by {@link
* com.oracle.graal.phases.common.cfs.EquationalReasoner#deverbosifyFloatingNode(com.oracle.graal.nodes.calc.FloatingNode)}
* ; or
* <li>{@link com.oracle.graal.nodes.java.MethodCallTargetNode}, added by {@link
* #deverbosifyInputsCopyOnWrite(com.oracle.graal.nodes.java.MethodCallTargetNode)}
* </ul>
*
* Checking if they aren't in use, proceeding to remove them in that case.
*/
@Override
public void finished() {
if (!postponedDeopts.isEmpty()) {
for (PostponedDeopt postponed : postponedDeopts) {
postponed.doRewrite(falseConstant);
}
new DeadCodeEliminationPhase(Optional).apply(graph);
}
for (MethodCallTargetNode mcn : graph.getNodes().filter(MethodCallTargetNode.class)) {
if (mcn.isAlive() && FlowUtil.lacksUsages(mcn)) {
mcn.safeDelete();
}
}
for (Node n : graph.getNodes().filter(FloatingNode.class)) {
GraphUtil.tryKillUnused(n);
}
assert !isAliveWithoutUsages(trueConstant);
assert !isAliveWithoutUsages(falseConstant);
assert !isAliveWithoutUsages(nullConstant);
super.finished();
}
public void removeIfUnused(Node node) {
GraphUtil.tryKillUnused(node);
}
public void deleteBranch(Node branch) {
branch.predecessor().replaceFirstSuccessor(branch, null);
GraphUtil.killCFG(branch, this);
}