annotate src/share/vm/utilities/stringUtils.cpp @ 20543:e7d0505c8a30

8059758: Footprint regressions with JDK-8038423 Summary: Changes in JDK-8038423 always initialize (zero out) virtual memory used for auxiliary data structures. This causes a footprint regression for G1 in startup benchmarks. This is because they do not touch that memory at all, so the operating system does not actually commit these pages. The fix is to, if the initialization value of the data structures matches the default value of just committed memory (=0), do not do anything. Reviewed-by: jwilhelm, brutisso
author tschatzl
date Fri, 10 Oct 2014 15:51:58 +0200
parents 6e0cb14ce59b
children
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1 /*
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2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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4 *
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5 * This code is free software; you can redistribute it and/or modify it
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6 * under the terms of the GNU General Public License version 2 only, as
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7 * published by the Free Software Foundation.
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8 *
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
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10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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12 * version 2 for more details (a copy is included in the LICENSE file that
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13 * accompanied this code).
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14 *
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15 * You should have received a copy of the GNU General Public License version
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16 * 2 along with this work; if not, write to the Free Software Foundation,
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17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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18 *
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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20 * or visit www.oracle.com if you need additional information or have any
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21 * questions.
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22 *
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23 */
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24
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25 #include "precompiled.hpp"
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26 #include "utilities/stringUtils.hpp"
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27
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28 int StringUtils::replace_no_expand(char* string, const char* from, const char* to) {
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29 int replace_count = 0;
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30 size_t from_len = strlen(from);
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31 size_t to_len = strlen(to);
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32 assert(from_len >= to_len, "must not expand input");
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33
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34 for (char* dst = string; *dst && (dst = strstr(dst, from)) != NULL;) {
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35 char* left_over = dst + from_len;
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36 memmove(dst, to, to_len); // does not copy trailing 0 of <to>
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37 dst += to_len; // skip over the replacement.
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38 memmove(dst, left_over, strlen(left_over) + 1); // copies the trailing 0 of <left_over>
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39 ++ replace_count;
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40 }
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41
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42 return replace_count;
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43 }