1 /*
2 * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
3 *
4 * This code is free software; you can redistribute it and/or modify it
5 * under the terms of the GNU General Public License version 2 only, as
6 * published by the Free Software Foundation.
7 *
8 * This code is distributed in the hope that it will be useful, but WITHOUT
9 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
10 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
11 * version 2 for more details (a copy is included in the LICENSE file that
12 * accompanied this code).
13 *
14 * You should have received a copy of the GNU General Public License version
15 * 2 along with this work; if not, write to the Free Software Foundation,
16 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
17 *
18 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
19 * or visit www.oracle.com if you need additional information or have any
20 * questions.
21 *
22 */
23
24 #ifndef SHARE_VM_GC_SHENANDOAH_SHENANDOAHCODEROOTS_HPP
25 #define SHARE_VM_GC_SHENANDOAH_SHENANDOAHCODEROOTS_HPP
26
27 #include "code/codeCache.hpp"
28 #include "gc/shenandoah/shenandoahSharedVariables.hpp"
29 #include "memory/allocation.hpp"
30 #include "memory/iterator.hpp"
31
32 class ShenandoahHeap;
33 class ShenandoahHeapRegion;
34 class ShenandoahCodeRootsLock;
35
36 class ShenandoahParallelCodeHeapIterator {
37 friend class CodeCache;
38 private:
39 CodeHeap* _heap;
40 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile int));
41 volatile int _claimed_idx;
42 volatile bool _finished;
43 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
44 public:
45 ShenandoahParallelCodeHeapIterator(CodeHeap* heap);
46 void parallel_blobs_do(CodeBlobClosure* f);
47 };
48
49 class ShenandoahParallelCodeCacheIterator {
50 friend class CodeCache;
51 private:
52 ShenandoahParallelCodeHeapIterator* _iters;
53 int _length;
54 public:
55 ShenandoahParallelCodeCacheIterator(const GrowableArray<CodeHeap*>* heaps);
56 ~ShenandoahParallelCodeCacheIterator();
57 void parallel_blobs_do(CodeBlobClosure* f);
58 };
59
60 // ShenandoahNMethod tuple records the internal locations of oop slots within the nmethod.
61 // This allows us to quickly scan the oops without doing the nmethod-internal scans, that
62 // sometimes involves parsing the machine code. Note it does not record the oops themselves,
63 // because it would then require handling these tuples as the new class of roots.
64 class ShenandoahNMethod : public CHeapObj<mtGC> {
65 private:
66 nmethod* _nm;
67 oop** _oops;
68 int _oops_count;
69
70 public:
71 ShenandoahNMethod(nmethod *nm, GrowableArray<oop*>* oops);
72 ~ShenandoahNMethod();
73
74 nmethod* nm() {
75 return _nm;
76 }
77
78 bool has_cset_oops(ShenandoahHeap* heap);
79
80 void assert_alive_and_correct() PRODUCT_RETURN;
81 void assert_same_oops(GrowableArray<oop*>* oops) PRODUCT_RETURN;
82
83 static bool find_with_nmethod(void* nm, ShenandoahNMethod* other) {
84 return other->_nm == nm;
85 }
86 };
87
88 class ShenandoahCodeRootsIterator {
89 friend class ShenandoahCodeRoots;
90 protected:
91 ShenandoahHeap* _heap;
92 ShenandoahParallelCodeCacheIterator _par_iterator;
93 ShenandoahSharedFlag _seq_claimed;
94 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile size_t));
95 volatile size_t _claimed;
96 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
97 protected:
98 ShenandoahCodeRootsIterator();
99 ~ShenandoahCodeRootsIterator();
100
101 template<bool CSET_FILTER>
102 void dispatch_parallel_blobs_do(CodeBlobClosure *f);
103
104 template<bool CSET_FILTER>
105 void fast_parallel_blobs_do(CodeBlobClosure *f);
106 };
107
108 class ShenandoahAllCodeRootsIterator : public ShenandoahCodeRootsIterator {
109 public:
110 ShenandoahAllCodeRootsIterator() : ShenandoahCodeRootsIterator() {};
111 void possibly_parallel_blobs_do(CodeBlobClosure *f);
112 };
113
114 class ShenandoahCsetCodeRootsIterator : public ShenandoahCodeRootsIterator {
115 public:
116 ShenandoahCsetCodeRootsIterator() : ShenandoahCodeRootsIterator() {};
117 void possibly_parallel_blobs_do(CodeBlobClosure* f);
118 };
119
120 class ShenandoahCodeRoots : public CHeapObj<mtGC> {
121 friend class ShenandoahHeap;
122 friend class ShenandoahCodeRootsLock;
123 friend class ShenandoahCodeRootsIterator;
124
125 public:
126 static void initialize();
127 static void add_nmethod(nmethod* nm);
128 static void remove_nmethod(nmethod* nm);
129
130 /**
131 * Provides the iterator over all nmethods in the code cache that have oops.
132 * @return
133 */
134 static ShenandoahAllCodeRootsIterator iterator();
135
136 /**
137 * Provides the iterator over nmethods that have at least one oop in collection set.
138 * @return
139 */
140 static ShenandoahCsetCodeRootsIterator cset_iterator();
141
142 private:
143 struct PaddedLock {
144 DEFINE_PAD_MINUS_SIZE(0, DEFAULT_CACHE_LINE_SIZE, sizeof(volatile int));
145 volatile int _lock;
146 DEFINE_PAD_MINUS_SIZE(1, DEFAULT_CACHE_LINE_SIZE, 0);
147 };
148
149 static PaddedLock _recorded_nms_lock;
150 static GrowableArray<ShenandoahNMethod*>* _recorded_nms;
151
152 static void acquire_lock(bool write) {
153 volatile int* loc = &_recorded_nms_lock._lock;
154 if (write) {
155 while ((OrderAccess::load_acquire(loc) != 0) ||
156 Atomic::cmpxchg(-1, loc, 0) != 0) {
157 SpinPause();
158 }
159 assert (*loc == -1, "acquired for write");
160 } else {
161 while (true) {
162 int cur = OrderAccess::load_acquire(loc);
163 if (cur >= 0) {
164 if (Atomic::cmpxchg(cur + 1, loc, cur) == cur) {
165 // Success!
166 assert (*loc > 0, "acquired for read");
167 return;
168 }
169 }
170 SpinPause();
171 }
172 }
173 }
174
175 static void release_lock(bool write) {
176 volatile int* loc = &ShenandoahCodeRoots::_recorded_nms_lock._lock;
177 if (write) {
178 OrderAccess::release_store_fence(loc, 0);
179 } else {
180 Atomic::dec(loc);
181 }
182 }
183 };
184
185 // Very simple unranked read-write lock
186 class ShenandoahCodeRootsLock : public StackObj {
187 friend class ShenandoahCodeRoots;
188 private:
189 const bool _write;
190 public:
191 ShenandoahCodeRootsLock(bool write) : _write(write) {
192 ShenandoahCodeRoots::acquire_lock(write);
193 }
194
195 ~ShenandoahCodeRootsLock() {
196 ShenandoahCodeRoots::release_lock(_write);
197 }
198 };
199
200 #endif //SHARE_VM_GC_SHENANDOAH_SHENANDOAHCODEROOTS_HPP