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The GraalVM compiler and the Graal-truffle optimizer.

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/*
 * Copyright (c) 2009, 2018, 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.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * 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
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 */
package jdk.graal.compiler.bytecode;

/**
 * A utility for processing {@link Bytecodes#LOOKUPSWITCH} bytecodes.
 */
public class BytecodeLookupSwitch extends BytecodeSwitch {

    private static final int OFFSET_TO_NUMBER_PAIRS = 4;
    private static final int OFFSET_TO_FIRST_PAIR_MATCH = 8;
    private static final int OFFSET_TO_FIRST_PAIR_OFFSET = 12;
    private static final int PAIR_SIZE = 8;

    /**
     * Constructor for a {@link BytecodeStream}.
     *
     * @param stream the {@code BytecodeStream} containing the switch instruction
     * @param bci the index in the stream of the switch instruction
     */
    public BytecodeLookupSwitch(BytecodeStream stream, int bci) {
        super(stream, bci);
    }

    @Override
    public int offsetAt(int i) {
        return stream.readInt(alignedBci + OFFSET_TO_FIRST_PAIR_OFFSET + PAIR_SIZE * i);
    }

    @Override
    public int keyAt(int i) {
        return stream.readInt(alignedBci + OFFSET_TO_FIRST_PAIR_MATCH + PAIR_SIZE * i);
    }

    @Override
    public int numberOfCases() {
        return stream.readInt(alignedBci + OFFSET_TO_NUMBER_PAIRS);
    }

    @Override
    public int size() {
        return alignedBci + OFFSET_TO_FIRST_PAIR_MATCH + PAIR_SIZE * numberOfCases() - bci;
    }
}