/*

 * Copyright (c) 2017, 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.

 *

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 */

/**

 * @test

 * @bug 8172751

 * @summary OSR compilation at unreachable bci causes C1 crash

 *

 * @run main/othervm -XX:-BackgroundCompilation compiler.c1.Test8172751

 */

package compiler.c1;

import java.lang.invoke.MethodHandle;

import java.lang.invoke.MethodHandles;

import java.lang.invoke.MutableCallSite;

public class Test8172751 {

    private static final MethodHandle CONSTANT_TRUE = MethodHandles.constant(boolean.class, true);

    private static final MethodHandle CONSTANT_FALSE = MethodHandles.constant(boolean.class, false);

    private static final MutableCallSite CALL_SITE = new MutableCallSite(CONSTANT_FALSE);

    private static final int LIMIT = 1_000_000;

    private static volatile int counter;

    private static boolean doSomething() {

        return counter++ < LIMIT;

    }

    private static void executeLoop() {

        /*

         * Start off with executing the first loop, then change the call site

         * target so as to switch over to the second loop but continue running

         * in the first loop. Eventually, an OSR compilation of the first loop

         * is triggered. Yet C1 will not find the OSR entry, since it will

         * have optimized out the first loop already during parsing.

         */

        if (CALL_SITE.getTarget() == CONSTANT_FALSE) {

            int count = 0;

            while (doSomething()) {

                if (count++ == 1) {

                    flipSwitch();

                }

            }

        } else {

            while (doSomething()) {

            }

        }

    }

    private static void flipSwitch() {

        CALL_SITE.setTarget(CONSTANT_TRUE);

    }

    public static void main(String[] args) {

        executeLoop();

    }

}