Minor cleanup of deepHashCode / deepEquals.

These methods used equals() comparisons where identity
checks would've sufficient. As expected, this results in a
small but measurable performance increase on both art
& dalvik.

---------------------- After --------------
ART:
    arrayLength    benchmark      us linear runtime
              1 DeepHashCode    8.08 =
              1       Equals   17.68 =
              4 DeepHashCode    8.63 =
              4       Equals   18.20 =
             16 DeepHashCode   19.59 =
             16       Equals   41.19 =
            256 DeepHashCode  255.41 =
            256       Equals  483.61 ==
           2048 DeepHashCode 2321.91 ==============
           2048       Equals 4932.40 ==============================
Dalvik:
    arrayLength    benchmark      us linear runtime
              1 DeepHashCode    32.7 =
              1       Equals    65.3 =
              4 DeepHashCode    34.4 =
              4       Equals    67.7 =
             16 DeepHashCode    76.0 =
             16       Equals   142.8 =
            256 DeepHashCode   755.6 =
            256       Equals  1515.6 ===
           2048 DeepHashCode  6915.4 ===============
           2048       Equals 13786.6 ==============================

------------------------ Before --------------------
Art:
    arrayLength    benchmark      us linear runtime
              1 DeepHashCode    8.13 =
              1       Equals   17.86 =
              4 DeepHashCode    8.63 =
              4       Equals   18.92 =
             16 DeepHashCode   19.59 =
             16       Equals   40.89 =
            256 DeepHashCode  253.88 =
            256       Equals  477.02 ==
           2048 DeepHashCode 2795.26 ================
           2048       Equals 4962.11 ==============================

Dalvik:
    arrayLength    benchmark      us linear runtime
              1 DeepHashCode    32.8 =
              1       Equals    66.7 =
              4 DeepHashCode    34.4 =
              4       Equals    70.1 =
             16 DeepHashCode    74.1 =
             16       Equals   147.9 =
            256 DeepHashCode   805.0 =
            256       Equals  1573.2 ===
           2048 DeepHashCode  7253.4 ===============
           2048       Equals 14349.8 ==============================

bug: 9320068

Change-Id: Id73bf38dd0777b2ec9004a2941523d082bbc74c9

1 files changed, 148 insertions, 0 deletions

diff --git a/benchmarks/src/benchmarks/DeepArrayOpsBenchmark.java b/benchmarks/src/benchmarks/DeepArrayOpsBenchmark.java
new file mode 100644
index 0000000..09b3186
--- /dev/null
+++ b/benchmarks/src/benchmarks/DeepArrayOpsBenchmark.java
@@ -0,0 +1,148 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License
+ */
+
+package benchmarks;
+
+import com.google.caliper.Param;
+import com.google.caliper.SimpleBenchmark;
+
+import java.lang.reflect.Array;
+import java.lang.reflect.Constructor;
+import java.util.Arrays;
+
+public class DeepArrayOpsBenchmark extends SimpleBenchmark {
+    @Param({"1", "4", "16", "256", "2048"}) int arrayLength;
+
+    private Object[] array;
+    private Object[] array2;
+
+    private Object[] array3;
+    private Object[] array4;
+
+    protected void setUp() throws Exception {
+        array = new Object[arrayLength * 13];
+        array2 = new Object[arrayLength * 13];
+        for (int i = 0; i < arrayLength; i += 13) {
+            array[i] = new IntWrapper(i);
+            array2[i] = new IntWrapper(i);
+
+            array[i + 1] = new16ElementObjectarray();
+            array2[i + 1] = new16ElementObjectarray();
+
+            array[i + 2] = new boolean[16];
+            array2[i + 2] = new boolean[16];
+
+            array[i + 3] = new byte[16];
+            array2[i + 3] = new byte[16];
+
+            array[i + 4] = new char[16];
+            array2[i + 4] = new char[16];
+
+            array[i + 5] = new short[16];
+            array2[i + 5] = new short[16];
+
+            array[i + 6] = new float[16];
+            array2[i + 6] = new float[16];
+
+            array[i + 7] = new long[16];
+            array2[i + 7] = new long[16];
+
+            array[i + 8] = new int[16];
+            array2[i + 8] = new int[16];
+
+            array[i + 9] = new double[16];
+            array2[i + 9] = new double[16];
+
+            // Subarray types are concrete objects.
+            array[i + 10] = new16ElementArray(String.class, String.class);
+            array2[i + 10] = new16ElementArray(String.class, String.class);
+
+            array[i + 11] = new16ElementArray(Integer.class, Integer.class);
+            array2[i + 11] = new16ElementArray(Integer.class, Integer.class);
+
+            // Subarray types is an interface.
+            array[i + 12] = new16ElementArray(CharSequence.class, String.class);
+            array2[i + 12] = new16ElementArray(CharSequence.class, String.class);
+        }
+    }
+
+    public void timeDeepHashCode(int reps) {
+        for (int i = 0; i < reps; ++i) {
+            Arrays.deepHashCode(array);
+        }
+    }
+
+    public void timeEquals(int reps) {
+        for (int i = 0; i < reps; ++i) {
+            Arrays.deepEquals(array, array2);
+        }
+    }
+
+    private static final Object[] new16ElementObjectarray() {
+        Object[] array = new Object[16];
+        for (int i = 0; i < 16; ++i) {
+            array[i] = new IntWrapper(i);
+        }
+
+        return array;
+    }
+
+    @SuppressWarnings("unchecked")
+    private static final <T, V> T[] new16ElementArray(Class<T> arrayType, Class<V> type)
+            throws Exception {
+        T[] array = (T []) Array.newInstance(type, 16);
+        if (!arrayType.isAssignableFrom(type)) {
+            throw new IllegalArgumentException(arrayType + " is not assignable from " + type);
+        }
+
+        Constructor<V> constructor = type.getDeclaredConstructor(String.class);
+        for (int i = 0; i < 16; ++i) {
+            array[i] = (T) constructor.newInstance(String.valueOf(i + 1000));
+        }
+
+        return array;
+    }
+
+    /**
+     * A class that provides very basic equals() and hashCode() operations
+     * and doesn't resort to memoization tricks like {@link java.lang.Integer}.
+     *
+     * Useful for providing equal objects that aren't the same (a.equals(b) but
+     * a != b).
+     */
+    public static final class IntWrapper {
+        private final int wrapped;
+
+        public IntWrapper(int wrap) {
+            wrapped = wrap;
+        }
+
+        @Override
+        public int hashCode() {
+            return wrapped;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (!(o instanceof IntWrapper)) {
+                return false;
+            }
+
+            return ((IntWrapper) o).wrapped == this.wrapped;
+        }
+    }
+}
+