1 /*
2 * Copyright (c) 2019, 2020, Red Hat, Inc. 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_GC_SHENANDOAH_SHENANDOAHNMETHOD_HPP
26 #define SHARE_GC_SHENANDOAH_SHENANDOAHNMETHOD_HPP
27
28 #include "code/nmethod.hpp"
29 #include "gc/shenandoah/shenandoahHeap.hpp"
30 #include "gc/shenandoah/shenandoahLock.hpp"
31 #include "gc/shenandoah/shenandoahPadding.hpp"
32 #include "memory/allocation.hpp"
33 #include "runtime/atomic.hpp"
34 #include "utilities/growableArray.hpp"
35
36 // Use ShenandoahReentrantLock as ShenandoahNMethodLock
37 typedef ShenandoahReentrantLock<ShenandoahSimpleLock> ShenandoahNMethodLock;
38 typedef ShenandoahLocker<ShenandoahNMethodLock> ShenandoahNMethodLocker;
39
40 struct ShenandoahNMethodBarrier {
41 int32_t _rel_pc;
42 int32_t _rel_target_pc;
43 char _gc_state;
44 bool _jump_when_state;
45 };
46
47 // ShenandoahNMethod tuple records the internal locations of oop slots within reclocation stream in
48 // the nmethod. This allows us to quickly scan the oops without doing the nmethod-internal scans,
49 // that sometimes involves parsing the machine code. Note it does not record the oops themselves,
50 // because it would then require handling these tuples as the new class of roots.
51 class ShenandoahNMethod : public CHeapObj<mtGC> {
52 private:
53 nmethod* const _nm;
54 oop** _oops;
55 int _oops_count;
56 ShenandoahNMethodBarrier* _barriers;
57 int _barriers_count;
58 bool _has_non_immed_oops;
59 bool _unregistered;
60 ShenandoahNMethodLock _lock;
61 ShenandoahNMethodLock _ic_lock;
62
63 public:
64 ShenandoahNMethod(nmethod *nm);
65 ~ShenandoahNMethod();
66
67 static bool decode_reloc_jump_when_state(uint16_t reloc) {
68 return (reloc & (1 << 8)) != 0;
69 }
70
71 static char decode_reloc_gc_state(uint16_t reloc) {
72 return (reloc & 0xFF);
73 }
74
75 static uint16_t encode_to_reloc(char gc_state, bool jump_when_state) {
76 uint16_t res = (gc_state & 0xFF) | (jump_when_state ? (1 << 8) : 0);
77 assert(decode_reloc_jump_when_state(res) == jump_when_state, "Round-trip");
78 assert(decode_reloc_gc_state(res) == gc_state, "Round-trip");
79 return res;
80 }
81
82 inline nmethod* nm() const;
83 inline ShenandoahNMethodLock* lock();
84 inline ShenandoahNMethodLock* ic_lock();
85 inline void oops_do(OopClosure* oops, bool fix_relocations = false);
86 // Update oops when the nmethod is re-registered
87 void update();
88
89 inline bool is_unregistered() const;
90
91 static ShenandoahNMethod* for_nmethod(nmethod* nm);
92 static inline ShenandoahNMethodLock* lock_for_nmethod(nmethod* nm);
93 static inline ShenandoahNMethodLock* ic_lock_for_nmethod(nmethod* nm);
94
95 static bool handle_oops(nmethod* nm);
96 static bool handle_barriers(nmethod* nm);
97 static inline void heal_nmethod_metadata(ShenandoahNMethod* nmethod_data);
98 static inline void disarm_nmethod(nmethod* nm);
99
100 static inline ShenandoahNMethod* gc_data(nmethod* nm);
101 static inline void attach_gc_data(nmethod* nm, ShenandoahNMethod* gc_data);
102
103 void assert_correct() NOT_DEBUG_RETURN;
104 void assert_same_oops() NOT_DEBUG_RETURN;
105
106 bool has_barriers() {
107 return _barriers_count > 0;
108 }
109
110 private:
111 void init_from(nmethod* nm);
112 static void parse(nmethod* nm, GrowableArray<oop*>& oops, bool& _has_non_immed_oops, GrowableArray<ShenandoahNMethodBarrier>& barriers);
113 static bool patch_barrier(address pc, address target_pc, bool should_jump);
114 };
115
116 class ShenandoahNMethodTable;
117
118 // ShenandoahNMethodList holds registered nmethod data. The list is reference counted.
119 class ShenandoahNMethodList : public CHeapObj<mtGC> {
120 private:
121 ShenandoahNMethod** _list;
122 const int _size;
123 uint _ref_count;
124
125 private:
126 ~ShenandoahNMethodList();
127
128 public:
129 ShenandoahNMethodList(int size);
130
131 // Reference counting with CoceCache_lock held
132 ShenandoahNMethodList* acquire();
133 void release();
134
135 // Transfer content from other list to 'this' list, up to the limit
136 void transfer(ShenandoahNMethodList* const other, int limit);
137
138 inline int size() const;
139 inline ShenandoahNMethod** list() const;
140 inline ShenandoahNMethod* at(int index) const;
141 inline void set(int index, ShenandoahNMethod* snm);
142 };
143
144 // An opaque snapshot of current nmethod table for iteration
145 class ShenandoahNMethodTableSnapshot : public CHeapObj<mtGC> {
146 friend class ShenandoahNMethodTable;
147 private:
148 ShenandoahHeap* const _heap;
149 ShenandoahNMethodList* _list;
150 /* snapshot iteration limit */
151 int _limit;
152
153 shenandoah_padding(0);
154 Atomic<size_t> _claimed;
155 shenandoah_padding(1);
156
157 public:
158 ShenandoahNMethodTableSnapshot(ShenandoahNMethodTable* table);
159 ~ShenandoahNMethodTableSnapshot();
160
161 void parallel_nmethods_do(NMethodClosure *f);
162 void concurrent_nmethods_do(NMethodClosure* cl);
163 };
164
165 class ShenandoahNMethodTable : public CHeapObj<mtGC> {
166 friend class ShenandoahNMethodTableSnapshot;
167 private:
168 enum {
169 minSize = 1024
170 };
171
172 ShenandoahHeap* const _heap;
173 ShenandoahNMethodList* _list;
174
175 int _index;
176 ShenandoahLock _lock;
177 int _itr_cnt;
178
179 public:
180 ShenandoahNMethodTable();
181 ~ShenandoahNMethodTable();
182
183 void register_nmethod(nmethod* nm);
184 void unregister_nmethod(nmethod* nm);
185
186 bool contain(nmethod* nm) const;
187 int length() const { return _index; }
188
189 // Table iteration support
190 ShenandoahNMethodTableSnapshot* snapshot_for_iteration();
191 void finish_iteration(ShenandoahNMethodTableSnapshot* snapshot);
192
193 void assert_nmethods_correct() NOT_DEBUG_RETURN;
194 private:
195 // Rebuild table and replace current one
196 void rebuild(int size);
197
198 bool is_full() const {
199 assert(_index <= _list->size(), "Sanity");
200 return _index == _list->size();
201 }
202
203 ShenandoahNMethod* at(int index) const;
204 int index_of(nmethod* nm) const;
205 void remove(int index);
206 void append(ShenandoahNMethod* snm);
207
208 inline bool iteration_in_progress() const;
209 void wait_until_concurrent_iteration_done();
210
211 // Logging support
212 void log_register_nmethod(nmethod* nm);
213 void log_unregister_nmethod(nmethod* nm);
214 };
215
216 class ShenandoahConcurrentNMethodIterator {
217 private:
218 ShenandoahNMethodTable* const _table;
219 ShenandoahNMethodTableSnapshot* _table_snapshot;
220 uint _started_workers;
221 uint _finished_workers;
222
223 public:
224 ShenandoahConcurrentNMethodIterator(ShenandoahNMethodTable* table);
225
226 void nmethods_do(NMethodClosure* cl);
227 };
228
229 #endif // SHARE_GC_SHENANDOAH_SHENANDOAHNMETHOD_HPP