/*

Original JDK 9

Benchmark                    Mode  Cnt  Score   Error  Units
SwitchBench.enumConstIf      avgt   10  1.994 ± 0.006  ns/op
SwitchBench.enumConstSwitch  avgt   10  2.533 ± 0.006  ns/op
SwitchBench.enumVarIf        avgt   10  2.529 ± 0.004  ns/op
SwitchBench.enumVarSwitch    avgt   10  2.706 ± 0.005  ns/op
SwitchBench.intConstIf       avgt   10  1.988 ± 0.001  ns/op
SwitchBench.intConstSwitch   avgt   10  1.996 ± 0.034  ns/op
SwitchBench.intVarIf         avgt   10  2.464 ± 0.003  ns/op
SwitchBench.intVarSwitch     avgt   10  2.123 ± 0.002  ns/op

Original JDK 10

Benchmark                    Mode  Cnt  Score   Error  Units
SwitchBench.enumConstIf      avgt   10  2.125 ± 0.002  ns/op
SwitchBench.enumConstSwitch  avgt   10  2.501 ± 0.025  ns/op
SwitchBench.enumVarIf        avgt   10  2.593 ± 0.004  ns/op
SwitchBench.enumVarSwitch    avgt   10  2.862 ± 0.053  ns/op
SwitchBench.intConstIf       avgt   10  2.123 ± 0.003  ns/op
SwitchBench.intConstSwitch   avgt   10  2.125 ± 0.001  ns/op
SwitchBench.intVarIf         avgt   10  2.458 ± 0.019  ns/op
SwitchBench.intVarSwitch     avgt   10  2.439 ± 0.039  ns/op

@Stable Enum.ordinal in JDK 10

Benchmark                    Mode  Cnt  Score   Error  Units
SwitchBench.enumConstIf      avgt   10  2.126 ± 0.007  ns/op
SwitchBench.enumConstSwitch  avgt   10  2.159 ± 0.003  ns/op
SwitchBench.enumVarIf        avgt   10  2.593 ± 0.004  ns/op
SwitchBench.enumVarSwitch    avgt   10  2.842 ± 0.006  ns/op
SwitchBench.intConstIf       avgt   10  2.123 ± 0.002  ns/op
SwitchBench.intConstSwitch   avgt   10  2.123 ± 0.002  ns/op
SwitchBench.intVarIf         avgt   10  2.451 ± 0.002  ns/op
SwitchBench.intVarSwitch     avgt   10  2.274 ± 0.012  ns/op

Original JDK 10 + Graal

Benchmark                    Mode  Cnt  Score   Error  Units
SwitchBench.enumConstIf      avgt   10  2.349 ± 0.011  ns/op
SwitchBench.enumConstSwitch  avgt   10  2.345 ± 0.005  ns/op
SwitchBench.enumVarIf        avgt   10  2.612 ± 0.015  ns/op
SwitchBench.enumVarSwitch    avgt   10  2.862 ± 0.005  ns/op
SwitchBench.intConstIf       avgt   10  2.345 ± 0.015  ns/op
SwitchBench.intConstSwitch   avgt   10  2.347 ± 0.009  ns/op
SwitchBench.intVarIf         avgt   10  2.607 ± 0.010  ns/op
SwitchBench.intVarSwitch     avgt   10  2.435 ± 0.006  ns/op

@Stable Enum.ordinal in JDK 10 + Graal

Benchmark                    Mode  Cnt  Score   Error  Units
SwitchBench.enumConstIf      avgt   10  2.352 ± 0.010  ns/op
SwitchBench.enumConstSwitch  avgt   10  2.342 ± 0.007  ns/op
SwitchBench.enumVarIf        avgt   10  2.889 ± 0.012  ns/op
SwitchBench.enumVarSwitch    avgt   10  2.652 ± 0.069  ns/op
SwitchBench.intConstIf       avgt   10  2.346 ± 0.005  ns/op
SwitchBench.intConstSwitch   avgt   10  2.346 ± 0.004  ns/op
SwitchBench.intVarIf         avgt   10  2.886 ± 0.009  ns/op
SwitchBench.intVarSwitch     avgt   10  2.499 ± 0.004  ns/op

*/

package jdk.test;

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.Scope;
import org.openjdk.jmh.annotations.State;
import org.openjdk.jmh.annotations.Threads;
import org.openjdk.jmh.annotations.Warmup;

import java.util.concurrent.TimeUnit;

@BenchmarkMode(Mode.AverageTime)
@Fork(value = 1)
@Warmup(iterations = 5)
@Measurement(iterations = 10)
@Threads(1)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
@State(Scope.Benchmark)
public class SwitchBench {

    int i = 2;
    E e = E.B;

    enum E {
        A, B, C
    }

    @Benchmark
    public int intConstSwitch() {
        return intSwitch(2);
    }

    @Benchmark
    public int intVarSwitch() {
        return intSwitch(i);
    }

    @Benchmark
    public int enumConstSwitch() {
        return enumSwitch(E.B);
    }

    @Benchmark
    public int enumVarSwitch() {
        return enumSwitch(e);
    }

    @Benchmark
    public int intConstIf() {
        return intIf(2);
    }

    @Benchmark
    public int intVarIf() {
        return intIf(i);
    }

    @Benchmark
    public int enumConstIf() {
        return enumIf(E.B);
    }

    @Benchmark
    public int enumVarIf() {
        return enumIf(e);
    }

    private int intSwitch(int i) {
        switch (i) {
            case 1:
                return 11;
            case 2:
                return 22;
            case 3:
                return 33;
            default:
                return 0;
        }
    }

    private int enumSwitch(E e) {
        switch (e) {
            case A:
                return 11;
            case B:
                return 22;
            case C:
                return 33;
            default:
                return 0;
        }
    }

    private int intIf(int i) {
        if (i == 1) {
            return 11;
        } else if (i == 2) {
            return 22;
        } else if (i == 3) {
            return 33;
        } else {
            return 0;
        }
    }

    private int enumIf(E e) {
        if (e == E.A) {
            return 11;
        } else if (e == E.B) {
            return 22;
        } else if (e == E.C) {
            return 33;
        } else {
            return 0;
        }
    }
}