1 /*
2 * Copyright (c) 1998, 2012, 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 #ifndef SHARE_VM_CODE_OOPRECORDER_HPP
26 #define SHARE_VM_CODE_OOPRECORDER_HPP
27
28 #include "memory/universe.hpp"
29 #include "runtime/handles.hpp"
30 #include "utilities/growableArray.hpp"
31
32 // Recording and retrieval of either oop relocations or metadata in compiled code.
33
34 class CodeBlob;
35
36 template <class T> class ValueRecorder : public StackObj {
37 public:
38 // A two-way mapping from positive indexes to oop handles.
39 // The zero index is reserved for a constant (sharable) null.
40 // Indexes may not be negative.
41
42 // Use the given arena to manage storage, if not NULL.
43 // By default, uses the current ResourceArea.
44 ValueRecorder(Arena* arena = NULL);
45
46 // Generate a new index on which nmethod::oop_addr_at will work.
47 // allocate_index and find_index never return the same index,
48 // and allocate_index never returns the same index twice.
49 // In fact, two successive calls to allocate_index return successive ints.
50 int allocate_index(T h) {
51 return add_handle(h, false);
52 }
53
54 // For a given jobject or Metadata*, this will return the same index
55 // repeatedly. The index can later be given to nmethod::oop_at or
56 // metadata_at to retrieve the oop.
57 // However, the oop must not be changed via nmethod::oop_addr_at.
58 int find_index(T h) {
59 int index = maybe_find_index(h);
60 if (index < 0) { // previously unallocated
61 index = add_handle(h, true);
62 }
63 return index;
64 }
65
66 // returns the size of the generated oop/metadata table, for sizing the
67 // CodeBlob. Must be called after all oops are allocated!
68 int size();
69
70 // Retrieve the value at a given index.
71 T at(int index);
72
73 int count() {
74 if (_handles == NULL) return 0;
75 // there is always a NULL virtually present as first object
76 return _handles->length() + first_index;
77 }
78
79 // Helper function; returns false for NULL or Universe::non_oop_word().
80 bool is_real(T h) {
81 return h != NULL && h != (T)Universe::non_oop_word();
82 }
83
84 // copy the generated table to nmethod
85 void copy_values_to(nmethod* nm);
86
87 bool is_unused() { return _handles == NULL && !_complete; }
88 #ifdef ASSERT
89 bool is_complete() { return _complete; }
90 #endif
91
92 private:
93 // variant of find_index which does not allocate if not found (yields -1)
94 int maybe_find_index(T h);
95
96 // leaky hash table of handle => index, to help detect duplicate insertion
97 template <class X> class IndexCache : public ResourceObj {
98 // This class is only used by the ValueRecorder class.
99 friend class ValueRecorder;
100 enum {
101 _log_cache_size = 9,
102 _cache_size = (1<<_log_cache_size),
103 // Index entries are ints. The LSBit is a collision indicator.
104 _collision_bit_shift = 0,
105 _collision_bit = 1,
106 _index_shift = _collision_bit_shift+1
107 };
108 int _cache[_cache_size];
109 static juint cache_index(X handle) {
110 juint ci = (int) (intptr_t) handle;
111 ci ^= ci >> (BitsPerByte*2);
112 ci += ci >> (BitsPerByte*1);
113 return ci & (_cache_size-1);
114 }
115 int* cache_location(X handle) {
116 return &_cache[ cache_index(handle) ];
117 }
118 static bool cache_location_collision(int* cloc) {
119 return ((*cloc) & _collision_bit) != 0;
120 }
121 static int cache_location_index(int* cloc) {
122 return (*cloc) >> _index_shift;
123 }
124 static void set_cache_location_index(int* cloc, int index) {
125 int cval0 = (*cloc);
126 int cval1 = (index << _index_shift);
127 if (cval0 != 0 && cval1 != cval0) cval1 += _collision_bit;
128 (*cloc) = cval1;
129 }
130 IndexCache();
131 };
132
133 void maybe_initialize();
134 int add_handle(T h, bool make_findable);
135
136 enum { null_index = 0, first_index = 1, index_cache_threshold = 20 };
137
138 GrowableArray<T>* _handles; // ordered list (first is always NULL)
139 GrowableArray<int>* _no_finds; // all unfindable indexes; usually empty
140 IndexCache<T>* _indexes; // map: handle -> its probable index
141 Arena* _arena;
142 bool _complete;
143
144 #ifdef ASSERT
145 static int _find_index_calls, _hit_indexes, _missed_indexes;
146 #endif
147 };
148
149 class OopRecorder : public ResourceObj {
150 private:
151 ValueRecorder<jobject> _oops;
152 ValueRecorder<Metadata*> _metadata;
153 public:
154 OopRecorder(Arena* arena = NULL): _oops(arena), _metadata(arena) {}
155
156 int allocate_oop_index(jobject h) {
157 return _oops.allocate_index(h);
158 }
159 int find_index(jobject h) {
160 return _oops.find_index(h);
161 }
162 jobject oop_at(int index) {
163 return _oops.at(index);
164 }
165 int oop_size() {
166 return _oops.size();
167 }
168 int oop_count() {
169 return _oops.count();
170 }
171 bool is_real(jobject h) {
172 return _oops.is_real(h);
173 }
174
175 int allocate_metadata_index(Metadata* oop) {
176 return _metadata.allocate_index(oop);
177 }
178 int find_index(Metadata* h) {
179 return _metadata.find_index(h);
180 }
181 Metadata* metadata_at(int index) {
182 return _metadata.at(index);
183 }
184 int metadata_size() {
185 return _metadata.size();
186 }
187 int metadata_count() {
188 return _metadata.count();
189 }
190 bool is_real(Metadata* h) {
191 return _metadata.is_real(h);
192 }
193
194 bool is_unused() {
195 return _oops.is_unused() && _metadata.is_unused();
196 }
197
198 void freeze() {
199 _oops.size();
200 _metadata.size();
201 }
202
203 void copy_values_to(nmethod* nm) {
204 if (!_oops.is_unused()) {
205 _oops.copy_values_to(nm);
206 }
207 if (!_metadata.is_unused()) {
208 _metadata.copy_values_to(nm);
209 }
210 }
211
212 #ifdef ASSERT
213 bool is_complete() {
214 assert(_oops.is_complete() == _metadata.is_complete(), "must agree");
215 return _oops.is_complete();
216 }
217 #endif
218 };
219
220
221 #endif // SHARE_VM_CODE_OOPRECORDER_HPP