jdk/test/micro/org/openjdk/bench/vm/compiler/LeadingZeros.java

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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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package org.openjdk.bench.vm.compiler;

import org.openjdk.jmh.annotations.*;
import org.openjdk.jmh.infra.Blackhole;

import java.util.Random;
import java.util.concurrent.TimeUnit;

@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@Measurement(iterations = 5, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
@Warmup(iterations = 5, time = 1000, timeUnit = TimeUnit.MILLISECONDS)
@Fork(3)
public class LeadingZeros {
    private static final int SIZE = 512;

    @Benchmark
    public void testInt(Blackhole blackhole, BenchState state) {
        for (int i = 0; i < SIZE; i++) {
            state.result[i] = Integer.numberOfLeadingZeros(state.ints[i]);
        }

        blackhole.consume(state.result);
    }

    @Benchmark
    public void testLong(Blackhole blackhole, BenchState state) {
        for (int i = 0; i < SIZE; i++) {
            state.result[i] = Long.numberOfLeadingZeros(state.longs[i]);
        }

        blackhole.consume(state.result);
    }

    @State(Scope.Benchmark)
    public static class BenchState {
        private final int[] ints = new int[SIZE];
        private final long[] longs = new long[SIZE];

        private final int[] result = new int[SIZE];

        private Random random;

        public BenchState() {
        }

        @Setup
        public void setup() {
            this.random = new Random(1000);

            for (int i = 0; i < SIZE; i++) {
                ints[i] = this.random.nextInt();

                longs[i] = this.random.nextLong();
            }
        }
    }
}