VectorTest.java

import jdk.incubator.vector.*;
/*
javac14 src/main/java/VectorTest.java \
    --add-modules jdk.incubator.vector \
    -d out/

java14 -cp out/ VectorTest

@see http://cr.openjdk.java.net/~kkharbas/vector-api/CSR/javadoc.02/jdk.incubator.vector/jdk/incubator/vector/package-summary.html
@see https://nowokay.hatenablog.com/entry/2019/09/05/015537
*/
public class VectorTest {
    private static void test1() {
        System.out.println("test1()");
        float[] a = new float[]{1,2,3,4,5,6,7,8};
        float[] b = new float[]{1,1,1,1,1,1,1,1};

        float s = 0.0f;
        for (int i = 0; i < a.length; i++) {
            s += a[i] * b[i];
        }
        System.out.println("s=" + s);


        var SP = FloatVector.SPECIES_256;

        int limit = a.length;
        var fv_sum = FloatVector.fromValues(SP, 0, 0, 0, 0, 0, 0, 0, 0);
        for (int i = 0; i < limit; i += 8) {
            var fv_a = FloatVector.fromArray(SP, a, i);
            var fv_b = FloatVector.fromArray(SP, b, i);
            fv_sum = fv_a.fma(fv_b, fv_sum);
        }

        float[] outArray = new float[8];
        fv_sum.intoArray(outArray, 0);

        float sum = 0;
        for (float f: outArray) {
            sum += f;
        }
        System.out.println("sum=" + sum);
    }
    private static void test2() {
        System.out.println("test2()");
        float[] a = new float[]{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16};
        float[] b = new float[]{1,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1};

        float s = 0.0f;
        for (int i = 0; i < a.length; i++) {
            s += a[i] * b[i];
        }
        System.out.println("s=" + s);


        var SP = FloatVector.SPECIES_256;

        int limit = a.length;
        var fv_sum = FloatVector.fromValues(SP, 0, 0, 0, 0, 0, 0, 0, 0);
        for (int i = 0; i < limit; i += 8) {
            var fv_a = FloatVector.fromArray(SP, a, i);
            var fv_b = FloatVector.fromArray(SP, b, i);
            fv_sum = fv_a.fma(fv_b, fv_sum);
        }

        float[] outArray = new float[8];
        fv_sum.intoArray(outArray, 0);

        float sum = 0;
        for (float f: outArray) {
            sum += f;
        }
        System.out.println("sum=" + sum);
    }

    private static void test3() {
        System.out.println("test3()");
        float[] a = new float[]{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15};
        float[] b = new float[]{1,1,1,1,1,1,1,1,2,2,2,2,2,2,2};

        float s = 0.0f;
        for (int i = 0; i < a.length; i++) {
            s += a[i] * b[i];
        }
        System.out.println("s=" + s);


        var SP = FloatVector.SPECIES_256;

        int limit = a.length - a.length % 8;
        var fv_sum = FloatVector.fromValues(SP, 0, 0, 0, 0, 0, 0, 0, 0);
        for (int i = 0; i < limit; i += 8) {
            var fv_a = FloatVector.fromArray(SP, a, i);
            var fv_b = FloatVector.fromArray(SP, b, i);
            fv_sum = fv_a.fma(fv_b, fv_sum);
        }

        float[] outArray = new float[8];
        fv_sum.intoArray(outArray, 0);

        float sum = 0;
        for (float f: outArray) {
            sum += f;
        }

        for (int i = limit; i < a.length; i += 1) {
            sum += a[i] * b[i];
        }
        System.out.println("sum=" + sum);
    }
    public static void main(String[] args) {
        test1();
        test2();
        test3();
    }
}