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8170159: Improve the performance of BitSet traversal

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Reviewed-by: martin
This commit is contained in:
Paul Sandoz 2018-06-18 10:13:58 -07:00
parent 9d98befb04
commit 72a9d65a2c
1 changed files with 26 additions and 5 deletions
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31
src/java.base/share/classes/java/util/BitSet.java
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@ -1,5 +1,5 @@
/*
* Copyright (c) 1995, 2016, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 1995, 2018, 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
@ -1277,12 +1277,33 @@ public class BitSet implements Cloneable, java.io.Serializable {
int hi = getFence();
int i = index;
int v = wordIndex(hi - 1);
index = -1;
while (i >= 0 && i < hi) {
action.accept(i);
i = nextSetBit(i + 1, v);
if (i >= 0 && i < hi) {
action.accept(i++);
int u = wordIndex(i); // next lower word bound
int v = wordIndex(hi - 1); // upper word bound
words_loop:
for (; u <= v && i <= hi; u++, i = u << ADDRESS_BITS_PER_WORD) {
long word = words[u] & (WORD_MASK << i);
while (word != 0) {
i = (u << ADDRESS_BITS_PER_WORD) + Long.numberOfTrailingZeros(word);
if (i >= hi) {
// Break out of outer loop to ensure check of
// Integer.MAX_VALUE bit set
break words_loop;
}
// Flip the set bit
word &= ~(1L << i);
action.accept(i);
}
}
}
// Check if there is a final bit set for Integer.MAX_VALUE
if (i == Integer.MAX_VALUE && hi == Integer.MAX_VALUE) {
action.accept(Integer.MAX_VALUE);