1 /*
2 * Copyright (c) 2020, 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 "runtime/flags/jvmFlag.hpp"
27 #include "runtime/flags/jvmFlagLookup.hpp"
28 #include "utilities/defaultStream.hpp"
29
30 #define DO_FLAG(type, name,...) DO_HASH(FLAG_MEMBER_ENUM(name), XSTR(name))
31
32 #define DO_HASH(flag_enum, flag_name) { \
33 unsigned int hash = hash_code(flag_name); \
34 int bucket_index = (int)(hash % NUM_BUCKETS); \
35 _hashes[flag_enum] = (u2)(hash); \
36 _table[flag_enum] = _buckets[bucket_index]; \
37 _buckets[bucket_index] = (short)flag_enum; \
38 }
39
JVMFlagLookup()40 constexpr JVMFlagLookup::JVMFlagLookup() : _buckets(), _table(), _hashes() {
41 for (int i = 0; i < NUM_BUCKETS; i++) {
42 _buckets[i] = -1;
43 }
44
45 ALL_FLAGS(DO_FLAG,
46 DO_FLAG,
47 DO_FLAG,
48 DO_FLAG,
49 DO_FLAG,
50 IGNORE_RANGE,
51 IGNORE_CONSTRAINT)
52 }
53
54 constexpr JVMFlagLookup _flag_lookup_table;
55
find_impl(const char * name,size_t length) const56 JVMFlag* JVMFlagLookup::find_impl(const char* name, size_t length) const {
57 unsigned int hash = hash_code(name, length);
58 int bucket_index = (int)(hash % NUM_BUCKETS);
59 for (int flag_enum = _buckets[bucket_index]; flag_enum >= 0; ) {
60 if (_hashes[flag_enum] == (u2)hash) {
61 JVMFlag* flag = JVMFlag::flags + flag_enum;
62 if (strncmp(name, flag->name(), length) == 0) {
63 // We know flag->name() has at least <length> bytes.
64 // Make sure it has exactly <length> bytes
65 if (flag->name()[length] == 0) {
66 return flag;
67 }
68 }
69 }
70 flag_enum = (int)_table[flag_enum];
71 }
72
73 return NULL;
74 }
75
find(const char * name,size_t length)76 JVMFlag* JVMFlagLookup::find(const char* name, size_t length) {
77 return _flag_lookup_table.find_impl(name, length);
78 }
79