1 /*

     2  * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #include "precompiled.hpp"

    26 #include "classfile/altHashing.hpp"

    27 #include "classfile/symbolTable.hpp"

    28 #include "classfile/systemDictionary.hpp"

    29 #include "oops/markOop.hpp"

    30 #include "runtime/thread.hpp"

    31 

    32 // Get the hash code of the classes mirror if it exists, otherwise just

    33 // return a random number, which is one of the possible hash code used for

    34 // objects.  We don't want to call the synchronizer hash code to install

    35 // this value because it may safepoint.

    36 intptr_t object_hash(klassOop k) {

    37   intptr_t hc = k->java_mirror()->mark()->hash();

    38   return hc != markOopDesc::no_hash ? hc : os::random();

    39 }

    40 

    41 // Seed value used for each alternative hash calculated.

    42 jint AltHashing::compute_seed() {

    43   jlong nanos = os::javaTimeNanos();

    44   jlong now = os::javaTimeMillis();

    45   jint SEED_MATERIAL[8] = {

    46             (jint) object_hash(SystemDictionary::String_klass()),

    47             (jint) object_hash(SystemDictionary::System_klass()),

    48             (jint) os::random(),  // current thread isn't a java thread

    49             (jint) (((julong)nanos) >> 32),

    50             (jint) nanos,

    51             (jint) (((julong)now) >> 32),

    52             (jint) now,

    53             (jint) (os::javaTimeNanos() >> 2)

    54   };

    55 

    56   return murmur3_32(SEED_MATERIAL, 8);

    57 }

    58 

    59 

    60 // Murmur3 hashing for Symbol

    61 jint AltHashing::murmur3_32(jint seed, const jbyte* data, int len) {

    62   jint h1 = seed;

    63   int count = len;

    64   int offset = 0;

    65 

    66   // body

    67   while (count >= 4) {

    68     jint k1 = (data[offset] & 0x0FF)

    69         | (data[offset + 1] & 0x0FF) << 8

    70         | (data[offset + 2] & 0x0FF) << 16

    71         | data[offset + 3] << 24;

    72 

    73     count -= 4;

    74     offset += 4;

    75 

    76     k1 *= 0xcc9e2d51;

    77     k1 = Integer_rotateLeft(k1, 15);

    78     k1 *= 0x1b873593;

    79 

    80     h1 ^= k1;

    81     h1 = Integer_rotateLeft(h1, 13);

    82     h1 = h1 * 5 + 0xe6546b64;

    83   }

    84 

    85   // tail

    86 

    87   if (count > 0) {

    88     jint k1 = 0;

    89 

    90     switch (count) {

    91       case 3:

    92         k1 ^= (data[offset + 2] & 0xff) << 16;

    93       // fall through

    94       case 2:

    95         k1 ^= (data[offset + 1] & 0xff) << 8;

    96       // fall through

    97       case 1:

    98         k1 ^= (data[offset] & 0xff);

    99       // fall through

   100       default:

   101         k1 *= 0xcc9e2d51;

   102         k1 = Integer_rotateLeft(k1, 15);

   103         k1 *= 0x1b873593;

   104         h1 ^= k1;

   105     }

   106   }

   107 

   108   // finalization

   109   h1 ^= len;

   110 

   111   // finalization mix force all bits of a hash block to avalanche

   112   h1 ^= ((unsigned int)h1) >> 16;

   113   h1 *= 0x85ebca6b;

   114   h1 ^= ((unsigned int)h1) >> 13;

   115   h1 *= 0xc2b2ae35;

   116   h1 ^= ((unsigned int)h1) >> 16;

   117 

   118   return h1;

   119 }

   120 

   121 // Murmur3 hashing for Strings

   122 jint AltHashing::murmur3_32(jint seed, const jchar* data, int len) {

   123   jint h1 = seed;

   124 

   125   int off = 0;

   126   int count = len;

   127 

   128   // body

   129   while (count >= 2) {

   130     jchar d1 = data[off++] & 0xFFFF;

   131     jchar d2 = data[off++];

   132     jint k1 = (d1 | d2 << 16);

   133 

   134     count -= 2;

   135 

   136     k1 *= 0xcc9e2d51;

   137     k1 = Integer_rotateLeft(k1, 15);

   138     k1 *= 0x1b873593;

   139 

   140     h1 ^= k1;

   141     h1 = Integer_rotateLeft(h1, 13);

   142     h1 = h1 * 5 + 0xe6546b64;

   143   }

   144 

   145   // tail

   146 

   147   if (count > 0) {

   148     int k1 = data[off];

   149 

   150     k1 *= 0xcc9e2d51;

   151     k1 = Integer_rotateLeft(k1, 15);

   152     k1 *= 0x1b873593;

   153     h1 ^= k1;

   154   }

   155 

   156   // finalization

   157   h1 ^= len * 2; // (Character.SIZE / Byte.SIZE);

   158 

   159   // finalization mix force all bits of a hash block to avalanche

   160   h1 ^= ((unsigned int)h1) >> 16;

   161   h1 *= 0x85ebca6b;

   162   h1 ^= ((unsigned int)h1) >> 13;

   163   h1 *= 0xc2b2ae35;

   164   h1 ^= ((unsigned int)h1) >> 16;

   165 

   166   return h1;

   167 }

   168 

   169 // Hash used for the seed.

   170 jint AltHashing::murmur3_32(jint seed, const int* data, int len) {

   171   jint h1 = seed;

   172 

   173   int off = 0;

   174   int end = len;

   175 

   176   // body

   177   while (off < end) {

   178     jint k1 = data[off++];

   179 

   180     k1 *= 0xcc9e2d51;

   181     k1 = Integer_rotateLeft(k1, 15);

   182     k1 *= 0x1b873593;

   183 

   184     h1 ^= k1;

   185     h1 = Integer_rotateLeft(h1, 13);

   186     h1 = h1 * 5 + 0xe6546b64;

   187   }

   188 

   189   // tail (always empty, as body is always 32-bit chunks)

   190 

   191   // finalization

   192 

   193   h1 ^= len * 4; // (Integer.SIZE / Byte.SIZE);

   194 

   195   // finalization mix force all bits of a hash block to avalanche

   196   h1 ^= ((juint)h1) >> 16;

   197   h1 *= 0x85ebca6b;

   198   h1 ^= ((juint)h1) >> 13;

   199   h1 *= 0xc2b2ae35;

   200   h1 ^= ((juint)h1) >> 16;

   201 

   202   return h1;

   203 }

   204 

   205 jint AltHashing::murmur3_32(const int* data, int len) {

   206   return murmur3_32(0, data, len);

   207 }

   208 

   209 #ifndef PRODUCT

   210 // Overloaded versions for internal test.

   211 jint AltHashing::murmur3_32(const jbyte* data, int len) {

   212   return murmur3_32(0, data, len);

   213 }

   214 

   215 jint AltHashing::murmur3_32(const jchar* data, int len) {

   216   return murmur3_32(0, data, len);

   217 }

   218 

   219 // Internal test for alternate hashing.  Translated from JDK version

   220 // test/sun/misc/Hashing.java

   221 static const jbyte ONE_BYTE[] = { (jbyte) 0x80};

   222 static const jbyte TWO_BYTE[] = { (jbyte) 0x80, (jbyte) 0x81};

   223 static const jchar ONE_CHAR[] = { (jchar) 0x8180};

   224 static const jbyte THREE_BYTE[] = { (jbyte) 0x80, (jbyte) 0x81, (jbyte) 0x82};

   225 static const jbyte FOUR_BYTE[] = { (jbyte) 0x80, (jbyte) 0x81, (jbyte) 0x82, (jbyte) 0x83};

   226 static const jchar TWO_CHAR[] = { (jchar) 0x8180, (jchar) 0x8382};

   227 static const jint ONE_INT[] = { 0x83828180};

   228 static const jbyte SIX_BYTE[] = { (jbyte) 0x80, (jbyte) 0x81, (jbyte) 0x82, (jbyte) 0x83, (jbyte) 0x84, (jbyte) 0x85};

   229 static const jchar THREE_CHAR[] = { (jchar) 0x8180, (jchar) 0x8382, (jchar) 0x8584};

   230 static const jbyte EIGHT_BYTE[] = {

   231   (jbyte) 0x80, (jbyte) 0x81, (jbyte) 0x82,

   232   (jbyte) 0x83, (jbyte) 0x84, (jbyte) 0x85,

   233   (jbyte) 0x86, (jbyte) 0x87};

   234 static const jchar FOUR_CHAR[] = {

   235   (jchar) 0x8180, (jchar) 0x8382,

   236   (jchar) 0x8584, (jchar) 0x8786};

   237 

   238 static const jint TWO_INT[] = { 0x83828180, 0x87868584};

   239 

   240 static const juint MURMUR3_32_X86_CHECK_VALUE = 0xB0F57EE3;

   241 

   242 void AltHashing::testMurmur3_32_ByteArray() {

   243   // printf("testMurmur3_32_ByteArray\n");

   244 

   245   jbyte* vector = new jbyte[256];

   246   jbyte* hashes = new jbyte[4 * 256];

   247 

   248   for (int i = 0; i < 256; i++) {

   249     vector[i] = (jbyte) i;

   250   }

   251 

   252   // Hash subranges {}, {0}, {0,1}, {0,1,2}, ..., {0,...,255}

   253   for (int i = 0; i < 256; i++) {

   254     jint hash = murmur3_32(256 - i, vector, i);

   255     hashes[i * 4] = (jbyte) hash;

   256     hashes[i * 4 + 1] = (jbyte) (((juint)hash) >> 8);

   257     hashes[i * 4 + 2] = (jbyte) (((juint)hash) >> 16);

   258     hashes[i * 4 + 3] = (jbyte) (((juint)hash) >> 24);

   259   }

   260 

   261   // hash to get const result.

   262   juint final_hash = murmur3_32(hashes, 4*256);

   263 

   264   assert (MURMUR3_32_X86_CHECK_VALUE == final_hash,

   265     err_msg(

   266         "Calculated hash result not as expected. Expected %08X got %08X\n",

   267         MURMUR3_32_X86_CHECK_VALUE,

   268         final_hash));

   269 }

   270 

   271 void AltHashing::testEquivalentHashes() {

   272   jint jbytes, jchars, ints;

   273 

   274   // printf("testEquivalentHashes\n");

   275 

   276   jbytes = murmur3_32(TWO_BYTE, 2);

   277   jchars = murmur3_32(ONE_CHAR, 1);

   278   assert (jbytes == jchars,

   279     err_msg("Hashes did not match. b:%08x != c:%08x\n", jbytes, jchars));

   280 

   281   jbytes = murmur3_32(FOUR_BYTE, 4);

   282   jchars = murmur3_32(TWO_CHAR, 2);

   283   ints = murmur3_32(ONE_INT, 1);

   284   assert ((jbytes == jchars) && (jbytes == ints),

   285     err_msg("Hashes did not match. b:%08x != c:%08x != i:%08x\n", jbytes, jchars, ints));

   286 

   287   jbytes = murmur3_32(SIX_BYTE, 6);

   288   jchars = murmur3_32(THREE_CHAR, 3);

   289   assert (jbytes == jchars,

   290     err_msg("Hashes did not match. b:%08x != c:%08x\n", jbytes, jchars));

   291 

   292   jbytes = murmur3_32(EIGHT_BYTE, 8);

   293   jchars = murmur3_32(FOUR_CHAR, 4);

   294   ints = murmur3_32(TWO_INT, 2);

   295   assert ((jbytes == jchars) && (jbytes == ints),

   296     err_msg("Hashes did not match. b:%08x != c:%08x != i:%08x\n", jbytes, jchars, ints));

   297 }

   298 

   299 // Returns true if the alternate hashcode is correct

   300 void AltHashing::test_alt_hash() {

   301   testMurmur3_32_ByteArray();

   302   testEquivalentHashes();

   303 }

   304 #endif // PRODUCT