1/*
2 * Copyright (C) 2011-2019 Apple Inc. All rights reserved.
3 *
4 * Redistribution and use in source and binary forms, with or without
5 * modification, are permitted provided that the following conditions
6 * are met:
7 * 1. Redistributions of source code must retain the above copyright
8 * notice, this list of conditions and the following disclaimer.
9 * 2. Redistributions in binary form must reproduce the above copyright
10 * notice, this list of conditions and the following disclaimer in the
11 * documentation and/or other materials provided with the distribution.
12 *
13 * THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
14 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
15 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
16 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
17 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
18 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
19 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
20 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
21 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
22 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
23 * THE POSSIBILITY OF SUCH DAMAGE.
24 */
25
26#pragma once
27
28#include "HandleTypes.h"
29#include "IterationStatus.h"
30#include "MarkStack.h"
31#include "VisitRaceKey.h"
32#include <wtf/Forward.h>
33#include <wtf/MonotonicTime.h>
34#include <wtf/SharedTask.h>
35#include <wtf/text/CString.h>
36
37namespace JSC {
38
39class ConservativeRoots;
40class GCThreadSharedData;
41class Heap;
42class HeapCell;
43class HeapAnalyzer;
44class MarkedBlock;
45class MarkingConstraint;
46class MarkingConstraintSolver;
47template<typename T> class Weak;
48template<typename T, typename Traits> class WriteBarrierBase;
49
50typedef uint32_t HeapVersion;
51
52class SlotVisitor {
53 WTF_MAKE_NONCOPYABLE(SlotVisitor);
54 WTF_MAKE_FAST_ALLOCATED;
55
56 friend class SetCurrentCellScope;
57 friend class Heap;
58
59public:
60 enum RootMarkReason {
61 None,
62 ConservativeScan,
63 StrongReferences,
64 ProtectedValues,
65 MarkListSet,
66 VMExceptions,
67 StrongHandles,
68 Debugger,
69 JITStubRoutines,
70 WeakSets,
71 Output,
72 DFGWorkLists,
73 CodeBlocks,
74 DOMGCOutput,
75 };
76
77 SlotVisitor(Heap&, CString codeName);
78 ~SlotVisitor();
79
80 MarkStackArray& collectorMarkStack() { return m_collectorStack; }
81 MarkStackArray& mutatorMarkStack() { return m_mutatorStack; }
82 const MarkStackArray& collectorMarkStack() const { return m_collectorStack; }
83 const MarkStackArray& mutatorMarkStack() const { return m_mutatorStack; }
84
85 VM& vm();
86 const VM& vm() const;
87 Heap* heap() const;
88
89 void append(const ConservativeRoots&);
90
91 template<typename T, typename Traits> void append(const WriteBarrierBase<T, Traits>&);
92 template<typename T, typename Traits> void appendHidden(const WriteBarrierBase<T, Traits>&);
93 template<typename Iterator> void append(Iterator begin , Iterator end);
94 void appendValues(const WriteBarrierBase<Unknown, DumbValueTraits<Unknown>>*, size_t count);
95 void appendValuesHidden(const WriteBarrierBase<Unknown, DumbValueTraits<Unknown>>*, size_t count);
96
97 // These don't require you to prove that you have a WriteBarrier<>. That makes sense
98 // for:
99 //
100 // - roots.
101 // - sophisticated data structures that barrier through other means (like DFG::Plan and
102 // friends).
103 //
104 // If you are not a root and you don't know what kind of barrier you have, then you
105 // shouldn't call these methods.
106 void appendUnbarriered(JSValue);
107 void appendUnbarriered(JSValue*, size_t);
108 void appendUnbarriered(JSCell*);
109
110 template<typename T>
111 void append(const Weak<T>& weak);
112
113 void appendHiddenUnbarriered(JSValue);
114 void appendHiddenUnbarriered(JSCell*);
115
116 bool addOpaqueRoot(void*); // Returns true if the root was new.
117
118 bool containsOpaqueRoot(void*) const;
119
120 bool isEmpty() { return m_collectorStack.isEmpty() && m_mutatorStack.isEmpty(); }
121
122 bool isFirstVisit() const { return m_isFirstVisit; }
123
124 void didStartMarking();
125 void reset();
126 void clearMarkStacks();
127
128 size_t bytesVisited() const { return m_bytesVisited; }
129 size_t visitCount() const { return m_visitCount; }
130
131 void addToVisitCount(size_t value) { m_visitCount += value; }
132
133 void donate();
134 void drain(MonotonicTime timeout = MonotonicTime::infinity());
135 void donateAndDrain(MonotonicTime timeout = MonotonicTime::infinity());
136
137 enum SharedDrainMode { SlaveDrain, MasterDrain };
138 enum class SharedDrainResult { Done, TimedOut };
139 SharedDrainResult drainFromShared(SharedDrainMode, MonotonicTime timeout = MonotonicTime::infinity());
140
141 SharedDrainResult drainInParallel(MonotonicTime timeout = MonotonicTime::infinity());
142 SharedDrainResult drainInParallelPassively(MonotonicTime timeout = MonotonicTime::infinity());
143
144 SharedDrainResult waitForTermination(MonotonicTime timeout = MonotonicTime::infinity());
145
146 // Attempts to perform an increment of draining that involves only walking `bytes` worth of data. This
147 // is likely to accidentally walk more or less than that. It will usually mark more than bytes. It may
148 // mark less than bytes if we're reaching termination or if the global worklist is empty (which may in
149 // rare cases happen temporarily even if we're not reaching termination).
150 size_t performIncrementOfDraining(size_t bytes);
151
152 // This informs the GC about auxiliary of some size that we are keeping alive. If you don't do
153 // this then the space will be freed at end of GC.
154 void markAuxiliary(const void* base);
155
156 void reportExtraMemoryVisited(size_t);
157#if ENABLE(RESOURCE_USAGE)
158 void reportExternalMemoryVisited(size_t);
159#endif
160
161 void dump(PrintStream&) const;
162
163 bool isAnalyzingHeap() const { return !!m_heapAnalyzer; }
164 HeapAnalyzer* heapAnalyzer() const { return m_heapAnalyzer; }
165
166 RootMarkReason rootMarkReason() const { return m_rootMarkReason; }
167 void setRootMarkReason(RootMarkReason reason) { m_rootMarkReason = reason; }
168
169 HeapVersion markingVersion() const { return m_markingVersion; }
170
171 bool mutatorIsStopped() const { return m_mutatorIsStopped; }
172
173 Lock& rightToRun() { return m_rightToRun; }
174
175 void updateMutatorIsStopped(const AbstractLocker&);
176 void updateMutatorIsStopped();
177
178 bool hasAcknowledgedThatTheMutatorIsResumed() const;
179 bool mutatorIsStoppedIsUpToDate() const;
180
181 void optimizeForStoppedMutator();
182
183 void didRace(const VisitRaceKey&);
184 void didRace(JSCell* cell, const char* reason) { didRace(VisitRaceKey(cell, reason)); }
185
186 void visitAsConstraint(const JSCell*);
187
188 bool didReachTermination();
189
190 void setIgnoreNewOpaqueRoots(bool value) { m_ignoreNewOpaqueRoots = value; }
191
192 void donateAll();
193
194 const char* codeName() const { return m_codeName.data(); }
195
196 JS_EXPORT_PRIVATE void addParallelConstraintTask(RefPtr<SharedTask<void(SlotVisitor&)>>);
197
198private:
199 friend class ParallelModeEnabler;
200 friend class MarkingConstraintSolver;
201
202 void appendJSCellOrAuxiliary(HeapCell*);
203
204 JS_EXPORT_PRIVATE void appendSlow(JSCell*, Dependency);
205 JS_EXPORT_PRIVATE void appendHiddenSlow(JSCell*, Dependency);
206 void appendHiddenSlowImpl(JSCell*, Dependency);
207
208 template<typename ContainerType>
209 void setMarkedAndAppendToMarkStack(ContainerType&, JSCell*, Dependency);
210
211 void appendToMarkStack(JSCell*);
212
213 template<typename ContainerType>
214 void appendToMarkStack(ContainerType&, JSCell*);
215
216 void noteLiveAuxiliaryCell(HeapCell*);
217
218 void visitChildren(const JSCell*);
219
220 void propagateExternalMemoryVisitedIfNecessary();
221
222 void donateKnownParallel();
223 void donateKnownParallel(MarkStackArray& from, MarkStackArray& to);
224
225 void donateAll(const AbstractLocker&);
226
227 bool hasWork(const AbstractLocker&);
228 bool didReachTermination(const AbstractLocker&);
229
230#if CPU(X86_64)
231 NEVER_INLINE NO_RETURN_DUE_TO_CRASH NOT_TAIL_CALLED void reportZappedCellAndCrash(JSCell*);
232#endif
233
234 template<typename Func>
235 IterationStatus forEachMarkStack(const Func&);
236
237 MarkStackArray& correspondingGlobalStack(MarkStackArray&);
238
239 MarkStackArray m_collectorStack;
240 MarkStackArray m_mutatorStack;
241
242 size_t m_bytesVisited;
243 size_t m_visitCount;
244 size_t m_nonCellVisitCount { 0 }; // Used for incremental draining, ignored otherwise.
245 Checked<size_t, RecordOverflow> m_extraMemorySize { 0 };
246 bool m_isInParallelMode;
247 bool m_ignoreNewOpaqueRoots { false }; // Useful as a debugging mode.
248
249 HeapVersion m_markingVersion;
250
251 Heap& m_heap;
252
253 HeapAnalyzer* m_heapAnalyzer { nullptr };
254 JSCell* m_currentCell { nullptr };
255 RootMarkReason m_rootMarkReason { RootMarkReason::None };
256 bool m_isFirstVisit { false };
257 bool m_mutatorIsStopped { false };
258 bool m_canOptimizeForStoppedMutator { false };
259 Lock m_rightToRun;
260
261 CString m_codeName;
262
263 MarkingConstraint* m_currentConstraint { nullptr };
264 MarkingConstraintSolver* m_currentSolver { nullptr };
265
266 // Put padding here to mitigate false sharing between multiple SlotVisitors.
267 char padding[64];
268public:
269#if !ASSERT_DISABLED
270 bool m_isCheckingForDefaultMarkViolation;
271 bool m_isDraining;
272#endif
273};
274
275class ParallelModeEnabler {
276public:
277 ParallelModeEnabler(SlotVisitor& stack)
278 : m_stack(stack)
279 {
280 ASSERT(!m_stack.m_isInParallelMode);
281 m_stack.m_isInParallelMode = true;
282 }
283
284 ~ParallelModeEnabler()
285 {
286 ASSERT(m_stack.m_isInParallelMode);
287 m_stack.m_isInParallelMode = false;
288 }
289
290private:
291 SlotVisitor& m_stack;
292};
293
294class SetRootMarkReasonScope {
295public:
296 SetRootMarkReasonScope(SlotVisitor& visitor, SlotVisitor::RootMarkReason reason)
297 : m_visitor(visitor)
298 , m_previousReason(visitor.rootMarkReason())
299 {
300 m_visitor.setRootMarkReason(reason);
301 }
302
303 ~SetRootMarkReasonScope()
304 {
305 m_visitor.setRootMarkReason(m_previousReason);
306 }
307
308private:
309 SlotVisitor& m_visitor;
310 SlotVisitor::RootMarkReason m_previousReason;
311};
312
313} // namespace JSC
314