1 /*
2 * Copyright (c) 2017, 2019, 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_implementation/shenandoah/shenandoahSharedVariables.hpp"
29 #include "gc_implementation/shenandoah/shenandoahPadding.hpp"
30 #include "memory/allocation.hpp"
31 #include "memory/iterator.hpp"
32
33 class ShenandoahHeap;
34 class ShenandoahHeapRegion;
35 class ShenandoahCodeRootsLock;
36
37 class ShenandoahParallelCodeCacheIterator VALUE_OBJ_CLASS_SPEC {
38 friend class CodeCache;
39 private:
40 shenandoah_padding(0);
41 volatile int _claimed_idx;
42 volatile bool _finished;
43 shenandoah_padding(1);
44
45 // Noncopyable.
46 ShenandoahParallelCodeCacheIterator(const ShenandoahParallelCodeCacheIterator& o);
47 ShenandoahParallelCodeCacheIterator& operator=(const ShenandoahParallelCodeCacheIterator& o);
48 public:
49 ShenandoahParallelCodeCacheIterator();
50 void parallel_blobs_do(CodeBlobClosure* f);
51 };
52
53 // ShenandoahNMethod tuple records the internal locations of oop slots within the nmethod.
54 // This allows us to quickly scan the oops without doing the nmethod-internal scans, that
55 // sometimes involves parsing the machine code. Note it does not record the oops themselves,
56 // because it would then require handling these tuples as the new class of roots.
57 class ShenandoahNMethod : public CHeapObj<mtGC> {
58 private:
59 nmethod* _nm;
60 oop** _oops;
61 int _oops_count;
62
63 public:
64 ShenandoahNMethod(nmethod *nm, GrowableArray<oop*>* oops);
65 ~ShenandoahNMethod();
66
67 nmethod* nm() {
68 return _nm;
69 }
70
71 bool has_cset_oops(ShenandoahHeap* heap);
72
73 void assert_alive_and_correct() NOT_DEBUG_RETURN;
74 void assert_same_oops(GrowableArray<oop*>* oops) NOT_DEBUG_RETURN;
75
76 static bool find_with_nmethod(void* nm, ShenandoahNMethod* other) {
77 return other->_nm == nm;
78 }
79 };
80
81 class ShenandoahCodeRootsIterator VALUE_OBJ_CLASS_SPEC {
82 friend class ShenandoahCodeRoots;
83 protected:
84 ShenandoahHeap* _heap;
85 ShenandoahParallelCodeCacheIterator _par_iterator;
86 ShenandoahSharedFlag _seq_claimed;
87 char _pad0[DEFAULT_CACHE_LINE_SIZE];
88 volatile jlong _claimed;
89 char _pad1[DEFAULT_CACHE_LINE_SIZE];
90 protected:
91 ShenandoahCodeRootsIterator();
92 ~ShenandoahCodeRootsIterator();
93
94 template<bool CSET_FILTER>
95 void dispatch_parallel_blobs_do(CodeBlobClosure *f);
96
97 template<bool CSET_FILTER>
98 void fast_parallel_blobs_do(CodeBlobClosure *f);
99 };
100
101 class ShenandoahAllCodeRootsIterator : public ShenandoahCodeRootsIterator {
102 public:
103 ShenandoahAllCodeRootsIterator() : ShenandoahCodeRootsIterator() {};
104 void possibly_parallel_blobs_do(CodeBlobClosure *f);
105 };
106
107 class ShenandoahCsetCodeRootsIterator : public ShenandoahCodeRootsIterator {
108 public:
109 ShenandoahCsetCodeRootsIterator() : ShenandoahCodeRootsIterator() {};
110 void possibly_parallel_blobs_do(CodeBlobClosure* f);
111 };
112
113 class ShenandoahCodeRoots : public AllStatic {
114 friend class ShenandoahHeap;
115 friend class ShenandoahCodeRootsLock;
116 friend class ShenandoahCodeRootsIterator;
117
118 public:
119 static void initialize();
120 static void add_nmethod(nmethod* nm);
121 static void remove_nmethod(nmethod* nm);
122
123 private:
124 struct PaddedLock {
125 char _pad0[DEFAULT_CACHE_LINE_SIZE];
126 volatile int _lock;
127 char _pad1[DEFAULT_CACHE_LINE_SIZE];
128 };
129
130 static PaddedLock _recorded_nms_lock;
131 static GrowableArray<ShenandoahNMethod*>* _recorded_nms;
132
133 static void acquire_lock(bool write) {
134 volatile int* loc = &_recorded_nms_lock._lock;
135 if (write) {
136 while ((OrderAccess::load_acquire(loc) != 0) ||
137 Atomic::cmpxchg(-1, loc, 0) != 0) {
138 SpinPause();
139 }
140 assert (*loc == -1, "acquired for write");
141 } else {
142 while (true) {
143 jint cur = OrderAccess::load_acquire(loc);
144 if (cur >= 0) {
145 if (Atomic::cmpxchg(cur + 1, loc, cur) == cur) {
146 // Success!
147 assert (*loc > 0, "acquired for read");
148 return;
149 }
150 }
151 SpinPause();
152 }
153 }
154 }
155
156 static void release_lock(bool write) {
157 volatile int* loc = &ShenandoahCodeRoots::_recorded_nms_lock._lock;
158 if (write) {
159 OrderAccess::release_store_fence(loc, 0);
160 } else {
161 Atomic::dec(loc);
162 }
163 }
164 };
165
166 // Very simple unranked read-write lock
167 class ShenandoahCodeRootsLock : public StackObj {
168 friend class ShenandoahCodeRoots;
169 private:
170 const bool _write;
171 public:
172 ShenandoahCodeRootsLock(bool write) : _write(write) {
173 ShenandoahCodeRoots::acquire_lock(write);
174 }
175
176 ~ShenandoahCodeRootsLock() {
177 ShenandoahCodeRoots::release_lock(_write);
178 }
179 };
180
181 #endif //SHARE_VM_GC_SHENANDOAH_SHENANDOAHCODEROOTS_HPP