/*

 * Copyright (c) 2014 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.openjdk.bench.vm.compiler;

import org.openjdk.jmh.annotations.Benchmark;

import org.openjdk.jmh.annotations.BenchmarkMode;

import org.openjdk.jmh.annotations.Mode;

import org.openjdk.jmh.annotations.OutputTimeUnit;

import org.openjdk.jmh.annotations.Scope;

import org.openjdk.jmh.annotations.Setup;

import org.openjdk.jmh.annotations.State;

import java.util.concurrent.TimeUnit;

/**

 * Benchmark measuring the gain of removing array bound checks in various cases

 */

@BenchmarkMode(Mode.AverageTime)

@OutputTimeUnit(TimeUnit.NANOSECONDS)

@State(Scope.Thread)

public class ArrayBoundCheckRemoval {

    private int[] a;

    private int j, u, v;

    @Setup

    public void setup() {

        a = new int[200];

    }

    @Benchmark

    public int[] testForLoopAccess() throws Exception {

        int[] a = this.a;

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

            a[i] = i;

        }

        return a;

    }

    @Benchmark

    public int[] testBubblesortStripped() throws Exception {

        int[] a = this.a;

        int limit = a.length;

        int st = -1;

        while (st < limit) {

            st++;

            limit--;

            for (j = st; j < limit; j++) {

                u = a[j];

                v = a[j + 1];

            }

        }

        return a;

    }

    @Benchmark

    public int[] testBubblesort() throws Exception {

        int[] a = this.a;

        int j1;

        int limit = a.length;

        int st = -1;

        while (st < limit) {

            boolean flipped = false;

            st++;

            limit--;

            for (j1 = st; j1 < limit; j1++) {

                if (a[j1] > a[j1 + 1]) {

                    int T = a[j1];

                    a[j1] = a[j1 + 1];

                    a[j1 + 1] = T;

                    flipped = true;

                }

            }

            if (!flipped) {

                return a;

            }

            flipped = false;

            for (j1 = limit; --j1 >= st; ) {

                if (a[j1] > a[j1 + 1]) {

                    int T = a[j1];

                    a[j1] = a[j1 + 1];

                    a[j1 + 1] = T;

                    flipped = true;

                }

            }

            if (!flipped) {

                return a;

            }

        }

        return a;

    }

}