| /* |
| * Copyright (c) 2012, 2017, 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. |
| static intptr_t object_hash(Klass* 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. |
| juint AltHashing::compute_seed() { |
| jlong nanos = os::javaTimeNanos(); |
| jlong now = os::javaTimeMillis(); |
| int SEED_MATERIAL[8] = { |
| (int) object_hash(SystemDictionary::String_klass()), |
| (int) object_hash(SystemDictionary::System_klass()), |
| os::random(), // current thread isn't a java thread |
| (int) (((julong)nanos) >> 32), |
| (int) nanos, |
| (int) (((julong)now) >> 32), |
| (int) now, |
| (int) (os::javaTimeNanos() >> 2) |
| }; |
| |
| return murmur3_32(SEED_MATERIAL, 8); |
| } |
| |
| |
| // Murmur3 hashing for Symbol |
| juint AltHashing::murmur3_32(juint seed, const jbyte* data, int len) { |
| juint h1 = seed; |
| int count = len; |
| int offset = 0; |
| |
| // body |
| while (count >= 4) { |
| juint 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) { |
| juint 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 ^= h1 >> 16; |
| h1 *= 0x85ebca6b; |
| h1 ^= h1 >> 13; |
| h1 *= 0xc2b2ae35; |
| h1 ^= h1 >> 16; |
| |
| return h1; |
| } |
| |
| // Murmur3 hashing for Strings |
| juint AltHashing::murmur3_32(juint seed, const jchar* data, int len) { |
| juint h1 = seed; |
| |
| int off = 0; |
| int count = len; |
| |
| // body |
| while (count >= 2) { |
| jchar d1 = data[off++] & 0xFFFF; |
| jchar d2 = data[off++]; |
| juint 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) { |
| juint k1 = (juint)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 ^= h1 >> 16; |
| h1 *= 0x85ebca6b; |
| h1 ^= h1 >> 13; |
| h1 *= 0xc2b2ae35; |
| h1 ^= h1 >> 16; |
| |
| return h1; |
| } |
| |
| // Hash used for the seed. |
| juint AltHashing::murmur3_32(juint seed, const int* data, int len) { |
| juint h1 = seed; |
| |
| int off = 0; |
| int end = len; |
| |
| // body |
| while (off < end) { |
| juint k1 = (juint)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 ^= h1 >> 16; |
| h1 *= 0x85ebca6b; |
| h1 ^= h1 >> 13; |
| h1 *= 0xc2b2ae35; |
| h1 ^= h1 >> 16; |
| |
| return h1; |
| } |
| |
| juint AltHashing::murmur3_32(const int* data, int len) { |
| return murmur3_32(0, data, len); |
| } |