jdk-24/test/micro/org/openjdk/bench/java/lang/Longs.java

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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
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 *
 * 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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package org.openjdk.bench.java.lang;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Fork;
import org.openjdk.jmh.annotations.Measurement;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.annotations.Param;
import org.openjdk.jmh.annotations.Scope;
import org.openjdk.jmh.annotations.Setup;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Warmup;
import org.openjdk.jmh.infra.Blackhole;

import java.util.concurrent.ThreadLocalRandom;
import java.util.concurrent.TimeUnit;

@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.MICROSECONDS)
@State(Scope.Thread)
@Warmup(iterations = 10, time = 500, timeUnit = TimeUnit.MILLISECONDS)
@Measurement(iterations = 5, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
@Fork(3)
public class Longs {

    @Param("500")
    private int size;

    private long bound;
    private long[] res;
    private String[] strings;
    private long[] longArraySmall;
    private long[] longArrayBig;

    @Setup
    public void setup() {
        var random = ThreadLocalRandom.current();
        bound = 20000L;
        strings = new String[size];
        res = new long[size];
        longArraySmall = new long[size];
        longArrayBig = new long[size];
        for (int i = 0; i < size; i++) {
            strings[i] = "" + (random.nextLong(10000) - 5000);
            longArraySmall[i] = 100L * i + i + 103L;
            longArrayBig[i] = ((100L * i + i) << 32) + 4543 + i * 4L;
        }
    }

    /** Performs toString on small values, just a couple of digits. */
    @Benchmark
    public void toStringSmall(Blackhole bh) {
        for (long value : longArraySmall) {
            bh.consume(Long.toString(value));
        }
    }

    @Benchmark
    public void decode(Blackhole bh) {
        for (String s : strings) {
            bh.consume(Long.decode(s));
        }
    }

    /** Performs toString on large values, around 10 digits. */
    @Benchmark
    public void toStringBig(Blackhole bh) {
        for (long value : longArrayBig) {
            bh.consume(Long.toString(value));
        }
    }

    /** Performs expand on small values */
    @Benchmark
    public void expand(Blackhole bh) {
        for (long i : longArraySmall) {
            bh.consume(Long.expand(i, 0xFF00F0F0F0000000L));
        }
    }

    /** Performs compress on large values */
    @Benchmark
    public void compress(Blackhole bh) {
        for (long i : longArrayBig) {
            bh.consume(Long.compress(i, 0x000000000F0F0F1FL));
        }
    }

    /*
     * Have them public to avoid total unrolling
     */
    public int innerLoops = 1500;

    @Benchmark
    public long repetitiveSubtraction() {
        long x = 127, dx = 0;

        for (int i = 0; i < innerLoops; i++) {
            x -= dx;
            dx = (dx - x);
        }
        return x;
    }

    @Benchmark
    public void shiftRight(Blackhole bh) {
        for (int i = 0; i < size; i++) {
            bh.consume(longArrayBig[i] >> longArraySmall[i]);
        }
    }

    @Benchmark
    public void shiftURight(Blackhole bh) {
        for (int i = 0; i < size; i++) {
            bh.consume(longArrayBig[i] >>> longArraySmall[i]);
        }
    }

    @Benchmark
    public void shiftLeft(Blackhole bh) {
        for (int i = 0; i < size; i++) {
            bh.consume(longArrayBig[i] << longArraySmall[i]);
        }
    }

    @Benchmark
    public void compareUnsignedIndirect(Blackhole bh) {
        for (int i = 0; i < size; i++) {
            int r = (Long.compareUnsigned(longArraySmall[i], bound - 16) < 0) ? 1 : 0;
            bh.consume(r);
        }
    }

    @Benchmark
    public void compareUnsignedDirect(Blackhole bh) {
        for (int i = 0; i < size; i++) {
            int r = Long.compareUnsigned(longArraySmall[i], bound - 16);
            bh.consume(r);
        }
    }

    @Benchmark
    public void reverseBytes() {
        for (int i = 0; i < size; i++) {
            res[i] = Long.reverseBytes(longArraySmall[i]);
        }
    }

    @Benchmark
    public void reverse() {
        for (int i = 0; i < size; i++) {
            res[i] = Long.reverse(longArraySmall[i]);
        }
    }
}