diff -r 4d399f013e5a -r e9140bf80b4a src/share/vm/classfile/altHashing.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/share/vm/classfile/altHashing.cpp	Wed Jun 13 19:52:59 2012 -0400
@@ -0,0 +1,304 @@
+/*
+ * Copyright (c) 2012, 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "classfile/altHashing.hpp"
+#include "classfile/symbolTable.hpp"
+#include "classfile/systemDictionary.hpp"
+#include "oops/markOop.hpp"
+#include "runtime/thread.hpp"
+
+// Get the hash code of the classes mirror if it exists, otherwise just
+// return a random number, which is one of the possible hash code used for
+// objects.  We don't want to call the synchronizer hash code to install
+// this value because it may safepoint.
+intptr_t object_hash(klassOop k) {
+  intptr_t hc = k->java_mirror()->mark()->hash();
+  return hc != markOopDesc::no_hash ? hc : os::random();
+}
+
+// Seed value used for each alternative hash calculated.
+jint AltHashing::compute_seed() {
+  jlong nanos = os::javaTimeNanos();
+  jlong now = os::javaTimeMillis();
+  jint SEED_MATERIAL[8] = {
+            (jint) object_hash(SystemDictionary::String_klass()),
+            (jint) object_hash(SystemDictionary::System_klass()),
+            (jint) os::random(),  // current thread isn't a java thread
+            (jint) (((julong)nanos) >> 32),
+            (jint) nanos,
+            (jint) (((julong)now) >> 32),
+            (jint) now,
+            (jint) (os::javaTimeNanos() >> 2)
+  };
+
+  return murmur3_32(SEED_MATERIAL, 8);
+}
+
+
+// Murmur3 hashing for Symbol
+jint AltHashing::murmur3_32(jint seed, const jbyte* data, int len) {
+  jint h1 = seed;
+  int count = len;
+  int offset = 0;
+
+  // body
+  while (count >= 4) {
+    jint k1 = (data[offset] & 0x0FF)
+        | (data[offset + 1] & 0x0FF) << 8
+        | (data[offset + 2] & 0x0FF) << 16
+        | data[offset + 3] << 24;
+
+    count -= 4;
+    offset += 4;
+
+    k1 *= 0xcc9e2d51;
+    k1 = Integer_rotateLeft(k1, 15);
+    k1 *= 0x1b873593;
+
+    h1 ^= k1;
+    h1 = Integer_rotateLeft(h1, 13);
+    h1 = h1 * 5 + 0xe6546b64;
+  }
+
+  // tail
+
+  if (count > 0) {
+    jint k1 = 0;
+
+    switch (count) {
+      case 3:
+        k1 ^= (data[offset + 2] & 0xff) << 16;
+      // fall through
+      case 2:
+        k1 ^= (data[offset + 1] & 0xff) << 8;
+      // fall through
+      case 1:
+        k1 ^= (data[offset] & 0xff);
+      // fall through
+      default:
+        k1 *= 0xcc9e2d51;
+        k1 = Integer_rotateLeft(k1, 15);
+        k1 *= 0x1b873593;
+        h1 ^= k1;
+    }
+  }
+
+  // finalization
+  h1 ^= len;
+
+  // finalization mix force all bits of a hash block to avalanche
+  h1 ^= ((unsigned int)h1) >> 16;
+  h1 *= 0x85ebca6b;
+  h1 ^= ((unsigned int)h1) >> 13;
+  h1 *= 0xc2b2ae35;
+  h1 ^= ((unsigned int)h1) >> 16;
+
+  return h1;
+}
+
+// Murmur3 hashing for Strings
+jint AltHashing::murmur3_32(jint seed, const jchar* data, int len) {
+  jint h1 = seed;
+
+  int off = 0;
+  int count = len;
+
+  // body
+  while (count >= 2) {
+    jchar d1 = data[off++] & 0xFFFF;
+    jchar d2 = data[off++];
+    jint k1 = (d1 | d2 << 16);
+
+    count -= 2;
+
+    k1 *= 0xcc9e2d51;
+    k1 = Integer_rotateLeft(k1, 15);
+    k1 *= 0x1b873593;
+
+    h1 ^= k1;
+    h1 = Integer_rotateLeft(h1, 13);
+    h1 = h1 * 5 + 0xe6546b64;
+  }
+
+  // tail
+
+  if (count > 0) {
+    int k1 = data[off];
+
+    k1 *= 0xcc9e2d51;
+    k1 = Integer_rotateLeft(k1, 15);
+    k1 *= 0x1b873593;
+    h1 ^= k1;
+  }
+
+  // finalization
+  h1 ^= len * 2; // (Character.SIZE / Byte.SIZE);
+
+  // finalization mix force all bits of a hash block to avalanche
+  h1 ^= ((unsigned int)h1) >> 16;
+  h1 *= 0x85ebca6b;
+  h1 ^= ((unsigned int)h1) >> 13;
+  h1 *= 0xc2b2ae35;
+  h1 ^= ((unsigned int)h1) >> 16;
+
+  return h1;
+}
+
+// Hash used for the seed.
+jint AltHashing::murmur3_32(jint seed, const int* data, int len) {
+  jint h1 = seed;
+
+  int off = 0;
+  int end = len;
+
+  // body
+  while (off < end) {
+    jint k1 = data[off++];
+
+    k1 *= 0xcc9e2d51;
+    k1 = Integer_rotateLeft(k1, 15);
+    k1 *= 0x1b873593;
+
+    h1 ^= k1;
+    h1 = Integer_rotateLeft(h1, 13);
+    h1 = h1 * 5 + 0xe6546b64;
+  }
+
+  // tail (always empty, as body is always 32-bit chunks)
+
+  // finalization
+
+  h1 ^= len * 4; // (Integer.SIZE / Byte.SIZE);
+
+  // finalization mix force all bits of a hash block to avalanche
+  h1 ^= ((juint)h1) >> 16;
+  h1 *= 0x85ebca6b;
+  h1 ^= ((juint)h1) >> 13;
+  h1 *= 0xc2b2ae35;
+  h1 ^= ((juint)h1) >> 16;
+
+  return h1;
+}
+
+jint AltHashing::murmur3_32(const int* data, int len) {
+  return murmur3_32(0, data, len);
+}
+
+#ifndef PRODUCT
+// Overloaded versions for internal test.
+jint AltHashing::murmur3_32(const jbyte* data, int len) {
+  return murmur3_32(0, data, len);
+}
+
+jint AltHashing::murmur3_32(const jchar* data, int len) {
+  return murmur3_32(0, data, len);
+}
+
+// Internal test for alternate hashing.  Translated from JDK version
+// test/sun/misc/Hashing.java
+static const jbyte ONE_BYTE[] = { (jbyte) 0x80};
+static const jbyte TWO_BYTE[] = { (jbyte) 0x80, (jbyte) 0x81};
+static const jchar ONE_CHAR[] = { (jchar) 0x8180};
+static const jbyte THREE_BYTE[] = { (jbyte) 0x80, (jbyte) 0x81, (jbyte) 0x82};
+static const jbyte FOUR_BYTE[] = { (jbyte) 0x80, (jbyte) 0x81, (jbyte) 0x82, (jbyte) 0x83};
+static const jchar TWO_CHAR[] = { (jchar) 0x8180, (jchar) 0x8382};
+static const jint ONE_INT[] = { 0x83828180};
+static const jbyte SIX_BYTE[] = { (jbyte) 0x80, (jbyte) 0x81, (jbyte) 0x82, (jbyte) 0x83, (jbyte) 0x84, (jbyte) 0x85};
+static const jchar THREE_CHAR[] = { (jchar) 0x8180, (jchar) 0x8382, (jchar) 0x8584};
+static const jbyte EIGHT_BYTE[] = {
+  (jbyte) 0x80, (jbyte) 0x81, (jbyte) 0x82,
+  (jbyte) 0x83, (jbyte) 0x84, (jbyte) 0x85,
+  (jbyte) 0x86, (jbyte) 0x87};
+static const jchar FOUR_CHAR[] = {
+  (jchar) 0x8180, (jchar) 0x8382,
+  (jchar) 0x8584, (jchar) 0x8786};
+
+static const jint TWO_INT[] = { 0x83828180, 0x87868584};
+
+static const juint MURMUR3_32_X86_CHECK_VALUE = 0xB0F57EE3;
+
+void AltHashing::testMurmur3_32_ByteArray() {
+  // printf("testMurmur3_32_ByteArray\n");
+
+  jbyte* vector = new jbyte[256];
+  jbyte* hashes = new jbyte[4 * 256];
+
+  for (int i = 0; i < 256; i++) {
+    vector[i] = (jbyte) i;
+  }
+
+  // Hash subranges {}, {0}, {0,1}, {0,1,2}, ..., {0,...,255}
+  for (int i = 0; i < 256; i++) {
+    jint hash = murmur3_32(256 - i, vector, i);
+    hashes[i * 4] = (jbyte) hash;
+    hashes[i * 4 + 1] = (jbyte) (((juint)hash) >> 8);
+    hashes[i * 4 + 2] = (jbyte) (((juint)hash) >> 16);
+    hashes[i * 4 + 3] = (jbyte) (((juint)hash) >> 24);
+  }
+
+  // hash to get const result.
+  juint final_hash = murmur3_32(hashes, 4*256);
+
+  assert (MURMUR3_32_X86_CHECK_VALUE == final_hash,
+    err_msg(
+        "Calculated hash result not as expected. Expected %08X got %08X\n",
+        MURMUR3_32_X86_CHECK_VALUE,
+        final_hash));
+}
+
+void AltHashing::testEquivalentHashes() {
+  jint jbytes, jchars, ints;
+
+  // printf("testEquivalentHashes\n");
+
+  jbytes = murmur3_32(TWO_BYTE, 2);
+  jchars = murmur3_32(ONE_CHAR, 1);
+  assert (jbytes == jchars,
+    err_msg("Hashes did not match. b:%08x != c:%08x\n", jbytes, jchars));
+
+  jbytes = murmur3_32(FOUR_BYTE, 4);
+  jchars = murmur3_32(TWO_CHAR, 2);
+  ints = murmur3_32(ONE_INT, 1);
+  assert ((jbytes == jchars) && (jbytes == ints),
+    err_msg("Hashes did not match. b:%08x != c:%08x != i:%08x\n", jbytes, jchars, ints));
+
+  jbytes = murmur3_32(SIX_BYTE, 6);
+  jchars = murmur3_32(THREE_CHAR, 3);
+  assert (jbytes == jchars,
+    err_msg("Hashes did not match. b:%08x != c:%08x\n", jbytes, jchars));
+
+  jbytes = murmur3_32(EIGHT_BYTE, 8);
+  jchars = murmur3_32(FOUR_CHAR, 4);
+  ints = murmur3_32(TWO_INT, 2);
+  assert ((jbytes == jchars) && (jbytes == ints),
+    err_msg("Hashes did not match. b:%08x != c:%08x != i:%08x\n", jbytes, jchars, ints));
+}
+
+// Returns true if the alternate hashcode is correct
+void AltHashing::test_alt_hash() {
+  testMurmur3_32_ByteArray();
+  testEquivalentHashes();
+}
+#endif // PRODUCT