8282664: Unroll by hand StringUTF16 and StringLatin1 polynomial hash loops

Co-authored-by: Sandhya Viswanathan <sviswanathan@openjdk.org>
Co-authored-by: Ludovic Henry <luhenry@openjdk.org>
Co-authored-by: Claes Redestad <redestad@openjdk.org>
Reviewed-by: vlivanov, sviswanathan, luhenry

test/micro/org/openjdk/bench/java/util/ArraysHashCode.java

@@ -0,0 +1,157 @@
+/*
+ * Copyright (c) 2022, 2023, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+package org.openjdk.bench.java.lang;
+
+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.OperationsPerInvocation;
+import org.openjdk.jmh.annotations.OutputTimeUnit;
+import org.openjdk.jmh.annotations.Param;
+import org.openjdk.jmh.annotations.Scope;
+import org.openjdk.jmh.annotations.Setup;
+import org.openjdk.jmh.annotations.State;
+import org.openjdk.jmh.annotations.Warmup;
+import org.openjdk.jmh.infra.Blackhole;
+
+import java.util.Arrays;
+import java.util.Random;
+import java.util.concurrent.TimeUnit;
+import java.io.UnsupportedEncodingException;
+import java.lang.invoke.MethodHandle;
+import java.lang.invoke.MethodHandles;
+import java.lang.reflect.Method;
+
+/**
+ * Performance test of Arrays.hashCode() methods
+ */
+@BenchmarkMode(Mode.AverageTime)
+@OutputTimeUnit(TimeUnit.NANOSECONDS)
+@State(Scope.Thread)
+@Warmup(iterations = 5, time = 1)
+@Measurement(iterations = 5, time = 1)
+@Fork(value = 3)
+public class ArraysHashCode {
+
+    @Param({"1", "10", "100", "10000"})
+    private int size;
+
+    private byte[] bytes;
+    private char[] chars;
+    private short[] shorts;
+    private int[] ints;
+    private byte[][] multibytes;
+    private char[][] multichars;
+    private short[][] multishorts;
+    private int[][] multiints;
+
+    @Setup
+    public void setup() throws UnsupportedEncodingException, ClassNotFoundException, NoSuchMethodException, Throwable {
+        Random rnd = new Random(42);
+
+        bytes = new byte[size];
+        chars = new char[size];
+        shorts = new short[size];
+        ints = new int[size];
+        for (int i = 0; i < size; i++) {
+            int next = rnd.nextInt();
+            bytes[i] = (byte)next;
+            chars[i] = (char)next;
+            shorts[i] = (short)next;
+            ints[i] = next;
+        }
+
+        multibytes = new byte[100][];
+        multichars = new char[100][];
+        multishorts = new short[100][];
+        multiints = new int[100][];
+        for (int i = 0; i < 100; i++) {
+            int next = rnd.nextInt(size + 1);
+            multibytes[i] = new byte[next];
+            multichars[i] = new char[next];
+            multishorts[i] = new short[next];
+            multiints[i] = new int[next];
+            for (int j = 0; j < next; j++) {
+                int nextj = rnd.nextInt();
+                multibytes[i][j] = (byte)nextj;
+                multichars[i][j] = (char)nextj;
+                multishorts[i][j] = (short)nextj;
+                multiints[i][j] = nextj;
+            }
+        }
+    }
+
+    @Benchmark
+    public int bytes() throws Throwable {
+        return Arrays.hashCode(bytes);
+    }
+
+    @Benchmark
+    public int chars() throws Throwable {
+        return Arrays.hashCode(chars);
+    }
+
+    @Benchmark
+    public int shorts() throws Throwable {
+        return Arrays.hashCode(shorts);
+    }
+
+    @Benchmark
+    public int ints() throws Throwable {
+        return Arrays.hashCode(ints);
+    }
+
+    @Benchmark
+    @OperationsPerInvocation(100)
+    public void multibytes(Blackhole bh) throws Throwable {
+        for (int i = 0; i < multibytes.length; i++) {
+            bh.consume(Arrays.hashCode(multibytes[i]));
+        }
+    }
+
+    @Benchmark
+    @OperationsPerInvocation(100)
+    public void multichars(Blackhole bh) throws Throwable {
+        for (int i = 0; i < multichars.length; i++) {
+            bh.consume(Arrays.hashCode(multichars[i]));
+        }
+    }
+
+    @Benchmark
+    @OperationsPerInvocation(100)
+    public void multishorts(Blackhole bh) throws Throwable {
+        for (int i = 0; i < multishorts.length; i++) {
+            bh.consume(Arrays.hashCode(multishorts[i]));
+        }
+    }
+
+    @Benchmark
+    @OperationsPerInvocation(100)
+    public void multiints(Blackhole bh) throws Throwable {
+        for (int i = 0; i < multibytes.length; i++) {
+            bh.consume(Arrays.hashCode(multiints[i]));
+        }
+    }
+}