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 * 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

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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

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/*

 * This file is available under and governed by the GNU General Public

 * License version 2 only, as published by the Free Software Foundation.

 * However, the following notice accompanied the original version of this

 * file:

 *

 * ASM: a very small and fast Java bytecode manipulation framework

 * Copyright (c) 2000-2011 INRIA, France Telecom

 * All rights reserved.

 *

 * Redistribution and use in source and binary forms, with or without

 * modification, are permitted provided that the following conditions

 * are met:

 * 1. Redistributions of source code must retain the above copyright

 *    notice, this list of conditions and the following disclaimer.

 * 2. Redistributions in binary form must reproduce the above copyright

 *    notice, this list of conditions and the following disclaimer in the

 *    documentation and/or other materials provided with the distribution.

 * 3. Neither the name of the copyright holders nor the names of its

 *    contributors may be used to endorse or promote products derived from

 *    this software without specific prior written permission.

 *

 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE

 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE

 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR

 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF

 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS

 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN

 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)

 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF

 * THE POSSIBILITY OF SUCH DAMAGE.

 */

package jdk.internal.org.objectweb.asm.tree.analysis;

import java.util.ArrayList;

import java.util.List;

import jdk.internal.org.objectweb.asm.tree.JumpInsnNode;

import jdk.internal.org.objectweb.asm.tree.LabelNode;

/**

 * A method subroutine (corresponds to a JSR instruction).

 *

 * @author Eric Bruneton

 */

final class Subroutine {

    /** The start of this subroutine. */

    final LabelNode start;

    /**

      * The local variables that are read or written by this subroutine. The i-th element is true if

      * and only if the local variable at index i is read or written by this subroutine.

      */

    final boolean[] localsUsed;

    /** The JSR instructions that jump to this subroutine. */

    final List<JumpInsnNode> callers;

    /**

      * Constructs a new {@link Subroutine}.

      *

      * @param start the start of this subroutine.

      * @param maxLocals the local variables that are read or written by this subroutine.

      * @param caller a JSR instruction that jump to this subroutine.

      */

    Subroutine(final LabelNode start, final int maxLocals, final JumpInsnNode caller) {

        this.start = start;

        this.localsUsed = new boolean[maxLocals];

        this.callers = new ArrayList<>();

        callers.add(caller);

    }

    /**

      * Constructs a copy of the given {@link Subroutine}.

      *

      * @param subroutine the subroutine to copy.

      */

    Subroutine(final Subroutine subroutine) {

        this.start = subroutine.start;

        this.localsUsed = subroutine.localsUsed.clone();

        this.callers = new ArrayList<>(subroutine.callers);

    }

    /**

      * Merges the given subroutine into this subroutine. The local variables read or written by the

      * given subroutine are marked as read or written by this one, and the callers of the given

      * subroutine are added as callers of this one (if both have the same start).

      *

      * @param subroutine another subroutine. This subroutine is left unchanged by this method.

      * @return whether this subroutine has been modified by this method.

      */

    public boolean merge(final Subroutine subroutine) {

        boolean changed = false;

        for (int i = 0; i < localsUsed.length; ++i) {

            if (subroutine.localsUsed[i] && !localsUsed[i]) {

                localsUsed[i] = true;

                changed = true;

            }

        }

        if (subroutine.start == start) {

            for (int i = 0; i < subroutine.callers.size(); ++i) {

                JumpInsnNode caller = subroutine.callers.get(i);

                if (!callers.contains(caller)) {

                    callers.add(caller);

                    changed = true;

                }

            }

        }

        return changed;

    }

}