1/*
2 * Copyright (c) 2013, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 */
23package org.graalvm.compiler.nodes.debug;
24
25import org.graalvm.compiler.graph.NodeClass;
26import org.graalvm.compiler.graph.spi.Simplifiable;
27import org.graalvm.compiler.graph.spi.SimplifierTool;
28import org.graalvm.compiler.nodeinfo.NodeInfo;
29import org.graalvm.compiler.nodes.ConstantNode;
30import org.graalvm.compiler.nodes.FixedNode;
31import org.graalvm.compiler.nodes.StructuredGraph;
32import org.graalvm.compiler.nodes.ValueNode;
33import org.graalvm.compiler.nodes.calc.FloatingNode;
34import org.graalvm.compiler.nodes.spi.Virtualizable;
35import org.graalvm.compiler.nodes.spi.VirtualizerTool;
36import org.graalvm.compiler.nodes.virtual.VirtualObjectNode;
37
38/**
39 * This is a special version of the dynamic counter node that removes itself as soon as it's the
40 * only usage of the associated node. This way it only increments the counter if the node is
41 * actually executed.
42 */
43@NodeInfo
44public final class WeakCounterNode extends DynamicCounterNode implements Simplifiable, Virtualizable {
45
46    public static final NodeClass<WeakCounterNode> TYPE = NodeClass.create(WeakCounterNode.class);
47    @Input ValueNode checkedValue;
48
49    public WeakCounterNode(String group, String name, ValueNode increment, boolean addContext, ValueNode checkedValue) {
50        super(TYPE, group, name, increment, addContext);
51        this.checkedValue = checkedValue;
52    }
53
54    @Override
55    public void simplify(SimplifierTool tool) {
56        if (checkedValue instanceof FloatingNode && checkedValue.getUsageCount() == 1) {
57            tool.addToWorkList(checkedValue);
58            graph().removeFixed(this);
59        }
60    }
61
62    @Override
63    public void virtualize(VirtualizerTool tool) {
64        ValueNode alias = tool.getAlias(checkedValue);
65        if (alias instanceof VirtualObjectNode) {
66            tool.delete();
67        }
68    }
69
70    public static void addCounterBefore(String group, String name, long increment, boolean addContext, ValueNode checkedValue, FixedNode position) {
71        StructuredGraph graph = position.graph();
72        WeakCounterNode counter = graph.add(new WeakCounterNode(name, group, ConstantNode.forLong(increment, graph), addContext, checkedValue));
73        graph.addBeforeFixed(position, counter);
74    }
75}
76