| /* |
| * Copyright (c) 2011, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. |
| * |
| * This code is distributed in the hope that it will be useful, but WITHOUT |
| * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| package org.graalvm.compiler.phases.common; |
| |
| import org.graalvm.compiler.debug.Debug; |
| import org.graalvm.compiler.debug.DebugCounter; |
| import org.graalvm.compiler.graph.Node; |
| import org.graalvm.compiler.graph.NodeFlood; |
| import org.graalvm.compiler.nodes.AbstractEndNode; |
| import org.graalvm.compiler.nodes.StructuredGraph; |
| import org.graalvm.compiler.options.Option; |
| import org.graalvm.compiler.options.OptionType; |
| import org.graalvm.compiler.options.OptionValue; |
| import org.graalvm.compiler.phases.Phase; |
| |
| public class DeadCodeEliminationPhase extends Phase { |
| |
| public static class Options { |
| |
| // @formatter:off |
| @Option(help = "Disable optional dead code eliminations", type = OptionType.Debug) |
| public static final OptionValue<Boolean> ReduceDCE = new OptionValue<>(true); |
| // @formatter:on |
| } |
| |
| private static final DebugCounter counterNodesRemoved = Debug.counter("NodesRemoved"); |
| |
| public enum Optionality { |
| Optional, |
| Required; |
| } |
| |
| /** |
| * Creates a dead code elimination phase that will be run irrespective of |
| * {@link Options#ReduceDCE}. |
| */ |
| public DeadCodeEliminationPhase() { |
| this(Optionality.Required); |
| } |
| |
| /** |
| * Creates a dead code elimination phase that will be run only if it is |
| * {@linkplain Optionality#Required non-optional} or {@link Options#ReduceDCE} is false. |
| */ |
| public DeadCodeEliminationPhase(Optionality optionality) { |
| this.optional = optionality == Optionality.Optional; |
| } |
| |
| private final boolean optional; |
| |
| @Override |
| public void run(StructuredGraph graph) { |
| if (optional && Options.ReduceDCE.getValue()) { |
| return; |
| } |
| |
| NodeFlood flood = graph.createNodeFlood(); |
| int totalNodeCount = graph.getNodeCount(); |
| flood.add(graph.start()); |
| iterateSuccessorsAndInputs(flood); |
| int totalMarkedCount = flood.getTotalMarkedCount(); |
| if (totalNodeCount == totalMarkedCount) { |
| // All nodes are live => nothing more to do. |
| return; |
| } else { |
| // Some nodes are not marked alive and therefore dead => proceed. |
| assert totalNodeCount > totalMarkedCount; |
| } |
| |
| deleteNodes(flood, graph); |
| } |
| |
| private static void iterateSuccessorsAndInputs(NodeFlood flood) { |
| Node.EdgeVisitor consumer = new Node.EdgeVisitor() { |
| @Override |
| public Node apply(Node n, Node succOrInput) { |
| assert succOrInput.isAlive() : "dead successor or input " + succOrInput + " in " + n; |
| flood.add(succOrInput); |
| return succOrInput; |
| } |
| }; |
| for (Node current : flood) { |
| if (current instanceof AbstractEndNode) { |
| AbstractEndNode end = (AbstractEndNode) current; |
| flood.add(end.merge()); |
| } else { |
| current.applySuccessors(consumer); |
| current.applyInputs(consumer); |
| } |
| } |
| } |
| |
| private static void deleteNodes(NodeFlood flood, StructuredGraph graph) { |
| Node.EdgeVisitor consumer = new Node.EdgeVisitor() { |
| @Override |
| public Node apply(Node n, Node input) { |
| if (input.isAlive() && flood.isMarked(input)) { |
| input.removeUsage(n); |
| } |
| return input; |
| } |
| }; |
| |
| for (Node node : graph.getNodes()) { |
| if (!flood.isMarked(node)) { |
| node.markDeleted(); |
| node.applyInputs(consumer); |
| counterNodesRemoved.increment(); |
| } |
| } |
| } |
| } |