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8033792: AltHashing used jint for imprecise bit shifting

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AltHashing used jint the way of juint in bit shifting which could lead loss of precision. Fix  by change _seed defined as juint.

Reviewed-by: coleenp, ccheung
This commit is contained in:
Yumin Qi 2014-02-10 21:29:14 -08:00 • committed by Yumin Qi
parent 35ff06e689
commit a90e842e0c
10 changed files with 66 additions and 65 deletions
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78
hotspot/src/share/vm/classfile/altHashing.cpp
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@ -1,5 +1,5 @@
/*
* Copyright (c) 2012, 2013, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2012, 2014, 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
@ -39,18 +39,18 @@ intptr_t object_hash(Klass* k) {
}
// Seed value used for each alternative hash calculated.
jint AltHashing::compute_seed() {
juint 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)
int SEED_MATERIAL[8] = {
(int) object_hash(SystemDictionary::String_klass()),
(int) object_hash(SystemDictionary::System_klass()),
(int) 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);
@ -58,14 +58,14 @@ jint AltHashing::compute_seed() {
// Murmur3 hashing for Symbol
jint AltHashing::murmur3_32(jint seed, const jbyte* data, int len) {
jint h1 = seed;
juint AltHashing::murmur3_32(juint seed, const jbyte* data, int len) {
juint h1 = seed;
int count = len;
int offset = 0;
// body
while (count >= 4) {
jint k1 = (data[offset] & 0x0FF)
juint k1 = (data[offset] & 0x0FF)
| (data[offset + 1] & 0x0FF) << 8
| (data[offset + 2] & 0x0FF) << 16
| data[offset + 3] << 24;
@ -85,7 +85,7 @@ jint AltHashing::murmur3_32(jint seed, const jbyte* data, int len) {
// tail
if (count > 0) {
jint k1 = 0;
juint k1 = 0;
switch (count) {
case 3:
@ -109,18 +109,18 @@ jint AltHashing::murmur3_32(jint seed, const jbyte* data, int len) {
h1 ^= len;
// finalization mix force all bits of a hash block to avalanche
h1 ^= ((unsigned int)h1) >> 16;
h1 ^= h1 >> 16;
h1 *= 0x85ebca6b;
h1 ^= ((unsigned int)h1) >> 13;
h1 ^= h1 >> 13;
h1 *= 0xc2b2ae35;
h1 ^= ((unsigned int)h1) >> 16;
h1 ^= h1 >> 16;
return h1;
}
// Murmur3 hashing for Strings
jint AltHashing::murmur3_32(jint seed, const jchar* data, int len) {
jint h1 = seed;
juint AltHashing::murmur3_32(juint seed, const jchar* data, int len) {
juint h1 = seed;
int off = 0;
int count = len;
@ -129,7 +129,7 @@ jint AltHashing::murmur3_32(jint seed, const jchar* data, int len) {
while (count >= 2) {
jchar d1 = data[off++] & 0xFFFF;
jchar d2 = data[off++];
jint k1 = (d1 | d2 << 16);
juint k1 = (d1 | d2 << 16);
count -= 2;
@ -145,7 +145,7 @@ jint AltHashing::murmur3_32(jint seed, const jchar* data, int len) {
// tail
if (count > 0) {
int k1 = data[off];
juint k1 = (juint)data[off];
k1 *= 0xcc9e2d51;
k1 = Integer_rotateLeft(k1, 15);
@ -157,25 +157,25 @@ jint AltHashing::murmur3_32(jint seed, const jchar* data, int len) {
h1 ^= len * 2; // (Character.SIZE / Byte.SIZE);
// finalization mix force all bits of a hash block to avalanche
h1 ^= ((unsigned int)h1) >> 16;
h1 ^= h1 >> 16;
h1 *= 0x85ebca6b;
h1 ^= ((unsigned int)h1) >> 13;
h1 ^= h1 >> 13;
h1 *= 0xc2b2ae35;
h1 ^= ((unsigned int)h1) >> 16;
h1 ^= h1 >> 16;
return h1;
}
// Hash used for the seed.
jint AltHashing::murmur3_32(jint seed, const int* data, int len) {
jint h1 = 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) {
jint k1 = data[off++];
juint k1 = (juint)data[off++];
k1 *= 0xcc9e2d51;
k1 = Integer_rotateLeft(k1, 15);
@ -193,26 +193,26 @@ jint AltHashing::murmur3_32(jint seed, const int* data, int len) {
h1 ^= len * 4; // (Integer.SIZE / Byte.SIZE);
// finalization mix force all bits of a hash block to avalanche
h1 ^= ((juint)h1) >> 16;
h1 ^= h1 >> 16;
h1 *= 0x85ebca6b;
h1 ^= ((juint)h1) >> 13;
h1 ^= h1 >> 13;
h1 *= 0xc2b2ae35;
h1 ^= ((juint)h1) >> 16;
h1 ^= h1 >> 16;
return h1;
}
jint AltHashing::murmur3_32(const int* data, int len) {
juint 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) {
juint AltHashing::murmur3_32(const jbyte* data, int len) {
return murmur3_32(0, data, len);
}
jint AltHashing::murmur3_32(const jchar* data, int len) {
juint AltHashing::murmur3_32(const jchar* data, int len) {
return murmur3_32(0, data, len);
}
@ -251,11 +251,11 @@ void AltHashing::testMurmur3_32_ByteArray() {
// 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);
juint 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);
hashes[i * 4 + 1] = (jbyte)(hash >> 8);
hashes[i * 4 + 2] = (jbyte)(hash >> 16);
hashes[i * 4 + 3] = (jbyte)(hash >> 24);
}
// hash to get const result.
@ -269,7 +269,7 @@ void AltHashing::testMurmur3_32_ByteArray() {
}
void AltHashing::testEquivalentHashes() {
jint jbytes, jchars, ints;
juint jbytes, jchars, ints;
// printf("testEquivalentHashes\n");