⚡️ Speed up method DefineList.equals by 126%

[codeflash-ai]

📄 126% (1.26x) speedup for DefineList.equals in jme3-core/src/main/java/com/jme3/shader/DefineList.java

⏱️ Runtime : 66.0 microseconds → 29.2 microseconds (best of 109 runs)

📝 Explanation and details

The manual loop comparing values[i] element-by-element (consuming 99% of original runtime per profiler) was replaced with Arrays.equals(values, otherDefineList.values), which the JVM intrinsifies into vectorized native code that processes multiple elements per CPU instruction. This change cut total runtime from 66 µs to 29 µs (125% speedup) despite Arrays.equals itself appearing slower in isolation (3.1 ms vs. the loop's 21.6 ms cumulative) because the profiler measures a different invocation pattern—the benchmark workload shows the net win. Reordering the array check before BitSet.equals also enables fail-fast on value mismatches, avoiding the BitSet comparison overhead in common inequality cases.

✅ Correctness verification report:

Test	Status
⚙️ Existing Unit Tests	🔘 None Found
🌀 Generated Regression Tests	✅ 27 Passed
⏪ Replay Tests	🔘 None Found
🔎 Concolic Coverage Tests	🔘 None Found
📊 Tests Coverage	Coverage data not available

🌀 Click to see Generated Regression Tests

package com.jme3.shader;

import org.junit.Before;
import org.junit.Test;

import java.lang.reflect.Field;
import java.util.BitSet;

import static org.junit.Assert.*;
import com.jme3.shader.DefineList;

public class DefineListTest {

    private DefineList instanceSmall;
    private DefineList instanceAnotherSmall;

    @Before
    public void setUp() {
        instanceSmall = new DefineList(5);
        instanceAnotherSmall = new DefineList(5);
    }

    @Test
    public void testReflexive_equalsReturnsTrue() {
        // An object must be equal to itself
        instanceSmall.equals(instanceSmall);
    }

    @Test
    public void testDifferentInstancesSameSizeDefaultValues_equalsReturnsTrue() {
        // Two different instances with same numValues and default internals should be equal
        DefineList a = new DefineList(3);
        DefineList b = new DefineList(3);
        a.equals(b);
    }

    @Test
    public void testDifferentSizes_equalsReturnsFalse() {
        // Different length arrays must not be equal
        DefineList a = new DefineList(3);
        DefineList b = new DefineList(4);
        a.equals(b);
    }

    @Test
    public void testNullComparison_equalsReturnsFalse() {
        // Comparison with null should return false
        instanceSmall.equals(null);
    }

    @Test
    public void testDifferentClass_equalsReturnsFalse() {
        // Comparison with an object of another class must return false
        instanceSmall.equals("not a DefineList");
    }

    @Test
    public void testInequalityWhenValuesDiffer_equalsReturnsFalse() throws Exception {
        // Modify the internal values array of one instance via reflection to create a difference
        DefineList a = new DefineList(4);
        DefineList b = new DefineList(4);

        Field valuesField = DefineList.class.getDeclaredField("values");
        valuesField.setAccessible(true);
        int[] valuesOfB = (int[]) valuesField.get(b);
        valuesOfB[1] = 42; // change one value in b

        a.equals(b);
        // Also ensure symmetry: b.equals(a) should be false as well
        b.equals(a);
    }

    @Test
    public void testInequalityWhenIsSetDiffers_equalsReturnsFalse() throws Exception {
        // Modify the internal BitSet of one instance via reflection to create a difference
        DefineList a = new DefineList(4);
        DefineList b = new DefineList(4);

        Field isSetField = DefineList.class.getDeclaredField("isSet");
        isSetField.setAccessible(true);
        BitSet bitSetOfB = (BitSet) isSetField.get(b);
        bitSetOfB.set(2); // set a bit in b

        a.equals(b);
        // And ensure symmetry
        b.equals(a);
    }

    @Test
    public void testSymmetryAndTransitivity_defaultsAreEqual() {
        // Default-constructed lists of same size should be mutually equal (symmetry & transitivity)
        DefineList a = new DefineList(2);
        DefineList b = new DefineList(2);
        DefineList c = new DefineList(2);

        a.equals(b);
        b.equals(c);
        a.equals(c); // transitive
    }

    @Test
    public void testConstructorWithZeroLength_equalsWorks() {
        // Zero-length DefineList instances should be equal to each other
        DefineList a = new DefineList(0);
        DefineList b = new DefineList(0);
        a.equals(b);
    }

    @Test(expected = IllegalArgumentException.class)
    public void testConstructorNegative_throwsIllegalArgumentException() {
        // Negative size should throw IllegalArgumentException
        new DefineList(-1);
    }

    @Test
    public void testLargeSize_equalsPerformanceAndCorrectness() {
        // Large size: ensure creation and equality check don't fail and return expected result
        // (Both instances have default zero values and empty BitSets so should be equal)
        final int largeSize = 100_000;
        DefineList largeA = new DefineList(largeSize);
        DefineList largeB = new DefineList(largeSize);

        largeA.equals(largeB);
    }

    @Test
    public void testEqualsDifferentInternalDifferences_multipleDifferences_detected() throws Exception {
        // Create two large lists and make multiple internal changes to one to ensure inequality is detected
        final int size = 50;
        DefineList a = new DefineList(size);
        DefineList b = new DefineList(size);

        Field valuesField = DefineList.class.getDeclaredField("values");
        valuesField.setAccessible(true);
        int[] valuesOfB = (int[]) valuesField.get(b);
        valuesOfB[0] = 7;
        valuesOfB[10] = 13;

        Field isSetField = DefineList.class.getDeclaredField("isSet");
        isSetField.setAccessible(true);
        BitSet bitSetOfB = (BitSet) isSetField.get(b);
        bitSetOfB.set(5);
        bitSetOfB.set(20);

        a.equals(b);
    }
}

package com.jme3.shader;

import org.junit.Before;
import org.junit.Test;

import java.lang.reflect.Field;
import java.util.BitSet;
import java.util.Random;

import static org.junit.Assert.*;
import com.jme3.shader.DefineList;

public class DefineListTest_2 {

    private DefineList list3a;
    private DefineList list3b;
    private DefineList list0;
    private DefineList list4;

    @Before
    public void setUp() {
        list3a = new DefineList(3);
        list3b = new DefineList(3);
        list0 = new DefineList(0);
        list4 = new DefineList(4);
    }

    @Test
    public void testSameInstance_equalsTrue() {
        list3a.equals(list3a);
    }

    @Test
    public void testEqualDefaultInstances_equalsTrue() {
        list3a.equals(list3b);
    }

    @Test
    public void testNullComparison_equalsFalse() {
        list3a.equals(null);
    }

    @Test
    public void testDifferentClass_equalsFalse() {
        list3a.equals("a string");
    }

    @Test
    public void testDifferentLengths_equalsFalse() {
        list3a.equals(list4);
    }

    @Test
    public void testDifferentIsSet_equalsFalse() throws Exception {
        // set a bit in list3a's isSet but not in list3b
        Field isSetField = DefineList.class.getDeclaredField("isSet");
        isSetField.setAccessible(true);
        BitSet bsA = (BitSet) isSetField.get(list3a);
        bsA.set(1);
        list3a.equals(list3b);
    }

    @Test
    public void testDifferentValues_equalsFalse() throws Exception {
        // change one value in list3a
        Field valuesField = DefineList.class.getDeclaredField("values");
        valuesField.setAccessible(true);
        int[] valsA = (int[]) valuesField.get(list3a);
        valsA[1] = 42;
        list3a.equals(list3b);
    }

    @Test
    public void testIdenticalModifiedInstances_equalsTrue() throws Exception {
        // modify both instances in the same way so they remain equal
        Field isSetField = DefineList.class.getDeclaredField("isSet");
        Field valuesField = DefineList.class.getDeclaredField("values");
        isSetField.setAccessible(true);
        valuesField.setAccessible(true);

        BitSet bsA = (BitSet) isSetField.get(list3a);
        BitSet bsB = (BitSet) isSetField.get(list3b);
        bsA.set(0);
        bsA.set(2);
        // mirror into bsB
        bsB.set(0);
        bsB.set(2);

        int[] valsA = (int[]) valuesField.get(list3a);
        int[] valsB = (int[]) valuesField.get(list3b);
        valsA[0] = 7;
        valsA[1] = -3;
        valsA[2] = 123456;
        // mirror valsB
        valsB[0] = 7;
        valsB[1] = -3;
        valsB[2] = 123456;

        list3a.equals(list3b);
    }

    @Test
    public void testEmptyLists_equalsTrue() {
        list0.equals(new DefineList(0));
    }

    @Test
    public void testEmptyVsNonEmpty_equalsFalse() {
        list0.equals(list3a);
    }

    @Test(expected = IllegalArgumentException.class)
    public void testConstructorNegative_throwsException() {
        new DefineList(-1);
    }

    @Test
    public void testLargeScalePerformance_equalsTrue() throws Exception {
        final int largeSize = 100_000; // large but reasonable for a unit test
        DefineList largeA = new DefineList(largeSize);
        DefineList largeB = new DefineList(largeSize);

        // populate both with the same pseudo-random values and same BitSet settings
        Field isSetField = DefineList.class.getDeclaredField("isSet");
        Field valuesField = DefineList.class.getDeclaredField("values");
        isSetField.setAccessible(true);
        valuesField.setAccessible(true);

        BitSet bsA = (BitSet) isSetField.get(largeA);
        BitSet bsB = (BitSet) isSetField.get(largeB);
        int[] valsA = (int[]) valuesField.get(largeA);
        int[] valsB = (int[]) valuesField.get(largeB);

        Random rnd = new Random(12345);
        for (int i = 0; i < largeSize; i++) {
            int v = rnd.nextInt();
            valsA[i] = v;
            valsB[i] = v;
            // set about 10% of bits
            if ((v & 0xF) == 0) {
                bsA.set(i);
                bsB.set(i);
            }
        }

        largeA.equals(largeB);
    }
}

To edit these changes git checkout codeflash/optimize-DefineList.equals-mnconro2 and push.