/*
 * Copyright (c) 2013, 2015, 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.nodes.debug;

import org.graalvm.compiler.graph.NodeClass;
import org.graalvm.compiler.graph.spi.Simplifiable;
import org.graalvm.compiler.graph.spi.SimplifierTool;
import org.graalvm.compiler.nodeinfo.NodeInfo;
import org.graalvm.compiler.nodes.ConstantNode;
import org.graalvm.compiler.nodes.FixedNode;
import org.graalvm.compiler.nodes.StructuredGraph;
import org.graalvm.compiler.nodes.ValueNode;
import org.graalvm.compiler.nodes.calc.FloatingNode;
import org.graalvm.compiler.nodes.spi.Virtualizable;
import org.graalvm.compiler.nodes.spi.VirtualizerTool;
import org.graalvm.compiler.nodes.virtual.VirtualObjectNode;

This is a special version of the dynamic counter node that removes itself as soon as it's the
only usage of the associated node. This way it only increments the counter if the node is
actually executed.
/**
 * This is a special version of the dynamic counter node that removes itself as soon as it's the
 * only usage of the associated node. This way it only increments the counter if the node is
 * actually executed.
 */
@NodeInfo
public final class WeakCounterNode extends DynamicCounterNode implements Simplifiable, Virtualizable {

    public static final NodeClass<WeakCounterNode> TYPE = NodeClass.create(WeakCounterNode.class);
    @Input ValueNode checkedValue;

    public WeakCounterNode(String group, String name, ValueNode increment, boolean addContext, ValueNode checkedValue) {
        super(TYPE, group, name, increment, addContext);
        this.checkedValue = checkedValue;
    }

    @Override
    public void simplify(SimplifierTool tool) {
        if (checkedValue instanceof FloatingNode && checkedValue.getUsageCount() == 1) {
            tool.addToWorkList(checkedValue);
            graph().removeFixed(this);
        }
    }

    @Override
    public void virtualize(VirtualizerTool tool) {
        ValueNode alias = tool.getAlias(checkedValue);
        if (alias instanceof VirtualObjectNode) {
            tool.delete();
        }
    }

    public static void addCounterBefore(String group, String name, long increment, boolean addContext, ValueNode checkedValue, FixedNode position) {
        StructuredGraph graph = position.graph();
        WeakCounterNode counter = graph.add(new WeakCounterNode(name, group, ConstantNode.forLong(increment, graph), addContext, checkedValue));
        graph.addBeforeFixed(position, counter);
    }
}