/*
 * 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 com.oracle.max.graal.compiler.phases;

import com.oracle.max.graal.compiler.*;
import com.oracle.max.graal.compiler.debug.*;
import com.oracle.max.graal.compiler.ir.*;
import com.oracle.max.graal.graph.*;

public class ReadEliminationPhase extends Phase {

    @Override
    protected void run(Graph graph) {
        for (ReadNode n : graph.getNodes(ReadNode.class)) {
            if (n.dependencies().size() > 0) {
                Node memoryInput = n.dependencies().get(0);
                if (memoryInput instanceof WriteNode) {
                    WriteNode other = (WriteNode) memoryInput;
                    if (other.object() == n.object() && other.location() == n.location()) {
                        if (GraalOptions.TraceReadElimination) {
                            TTY.println("Eliminated memory read " + n + "and replaced with node " + other.value());
                        }
                        n.replaceAndDelete(other.value());
                    }
                }
            }
        }
    }
}