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package org.openjdk.bench.vm.compiler;

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

import java.util.concurrent.TimeUnit;

/**
 * Tests speed of adding a series of additions of the same operand.
 */
@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Thread)
@Warmup(iterations = 4, time = 2, timeUnit = TimeUnit.SECONDS)
@Measurement(iterations = 4, time = 2, timeUnit = TimeUnit.SECONDS)
@Fork(value = 3)
public class SerialAdditions {
    private int a = 0xBADB0BA;
    private long b = 0x900dba51l;

    @Benchmark
    public int addIntsTo02() {
        return a + a; // baseline, still a + a
    }

    @Benchmark
    public int addIntsTo04() {
        return a + a + a + a; // a*4 => a<<2
    }

    @Benchmark
    public int addIntsTo05() {
        return a + a + a + a + a; // a*5 => (a<<2) + a
    }

    @Benchmark
    public int addIntsTo06() {
        return a + a + a + a + a + a; // a*6 => (a<<1) + (a<<2)
    }

    @Benchmark
    public int addIntsTo08() {
        return a + a + a + a + a + a + a + a; // a*8 => a<<3
    }

    @Benchmark
    public int addIntsTo16() {
        return a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a + a + a; // a*16 => a<<4
    }

    @Benchmark
    public int addIntsTo23() {
        return a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a + a + a + a + a + a + a //
                + a + a + a; // a*23
    }

    @Benchmark
    public int addIntsTo32() {
        return a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a + a + a + a + a + a + a //
                + a + a; // a*32 => a<<5
    }

    @Benchmark
    public int addIntsTo42() {
        return a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a + a + a + a + a + a + a //
                + a + a; // a*42
    }

    @Benchmark
    public int addIntsTo64() {
        return a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a + a + a + a + a + a + a //
                + a + a + a + a; // 64 * a => a << 6
    }

    @Benchmark
    public void addIntsMixed(Blackhole blackhole) {
        blackhole.consume(addIntsTo02());
        blackhole.consume(addIntsTo04());
        blackhole.consume(addIntsTo05());
        blackhole.consume(addIntsTo06());
        blackhole.consume(addIntsTo08());
        blackhole.consume(addIntsTo16());
        blackhole.consume(addIntsTo23());
        blackhole.consume(addIntsTo32());
        blackhole.consume(addIntsTo42());
        blackhole.consume(addIntsTo64());
    }

    @Benchmark
    public long addLongsTo02() {
        return b + b; // baseline, still a + a
    }

    @Benchmark
    public long addLongsTo04() {
        return b + b + b + b; // a*4 => a<<2
    }

    @Benchmark
    public long addLongsTo05() {
        return b + b + b + b + b; // a*5 => (a<<2) + a
    }

    @Benchmark
    public long addLongsTo06() {
        return b + b + b + b + b + b; // a*6 => (a<<1) + (a<<2)
    }

    @Benchmark
    public long addLongsTo08() {
        return b + b + b + b + b + b + b + b; // a*8 => a<<3
    }

    @Benchmark
    public long addLongsTo16() {
        return b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b + b + b; // a*16 => a<<4
    }

    @Benchmark
    public long addLongsTo23() {
        return b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b + b + b + b + b + b + b //
                + b + b + b; // a*23
    }

    @Benchmark
    public long addLongsTo32() {
        return b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b + b + b + b + b + b + b //
                + b + b; // a*32 => a<<5
    }

    @Benchmark
    public long addLongsTo42() {
        return b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b + b + b + b + b + b + b //
                + b + b; // a*42
    }

    @Benchmark
    public long addLongsTo64() {
        return b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b + b + b + b + b + b + b //
                + b + b + b + b; // 64 * a => a << 6
    }

    @Benchmark
    public void addLongsMixed(Blackhole blackhole) {
        blackhole.consume(addLongsTo02());
        blackhole.consume(addLongsTo04());
        blackhole.consume(addLongsTo05());
        blackhole.consume(addLongsTo06());
        blackhole.consume(addLongsTo08());
        blackhole.consume(addLongsTo16());
        blackhole.consume(addLongsTo23());
        blackhole.consume(addLongsTo32());
        blackhole.consume(addLongsTo42());
        blackhole.consume(addLongsTo64());
    }
}