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/*
* Copyright (C) 2011-2019 Apple Inc. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
* THE POSSIBILITY OF SUCH DAMAGE.
*/
#pragma once
#include "HandleTypes.h"
#include "IterationStatus.h"
#include "MarkStack.h"
#include "VisitRaceKey.h"
#include <wtf/Forward.h>
#include <wtf/MonotonicTime.h>
#include <wtf/SharedTask.h>
#include <wtf/text/CString.h>
namespace JSC {
class ConservativeRoots;
class GCThreadSharedData;
class Heap;
class HeapCell;
class HeapAnalyzer;
class MarkedBlock;
class MarkingConstraint;
class MarkingConstraintSolver;
template<typename T> class Weak;
template<typename T, typename Traits> class WriteBarrierBase;
typedef uint32_t HeapVersion;
class SlotVisitor {
WTF_MAKE_NONCOPYABLE(SlotVisitor);
WTF_MAKE_FAST_ALLOCATED;
friend class SetCurrentCellScope;
friend class Heap;
public:
enum RootMarkReason {
None,
ConservativeScan,
StrongReferences,
ProtectedValues,
MarkListSet,
VMExceptions,
StrongHandles,
Debugger,
JITStubRoutines,
WeakSets,
Output,
DFGWorkLists,
CodeBlocks,
DOMGCOutput,
};
SlotVisitor(Heap&, CString codeName);
~SlotVisitor();
MarkStackArray& collectorMarkStack() { return m_collectorStack; }
MarkStackArray& mutatorMarkStack() { return m_mutatorStack; }
const MarkStackArray& collectorMarkStack() const { return m_collectorStack; }
const MarkStackArray& mutatorMarkStack() const { return m_mutatorStack; }
VM& vm();
const VM& vm() const;
Heap* heap() const;
void append(const ConservativeRoots&);
template<typename T, typename Traits> void append(const WriteBarrierBase<T, Traits>&);
template<typename T, typename Traits> void appendHidden(const WriteBarrierBase<T, Traits>&);
template<typename Iterator> void append(Iterator begin , Iterator end);
void appendValues(const WriteBarrierBase<Unknown, DumbValueTraits<Unknown>>*, size_t count);
void appendValuesHidden(const WriteBarrierBase<Unknown, DumbValueTraits<Unknown>>*, size_t count);
// These don't require you to prove that you have a WriteBarrier<>. That makes sense
// for:
//
// - roots.
// - sophisticated data structures that barrier through other means (like DFG::Plan and
// friends).
//
// If you are not a root and you don't know what kind of barrier you have, then you
// shouldn't call these methods.
void appendUnbarriered(JSValue);
void appendUnbarriered(JSValue*, size_t);
void appendUnbarriered(JSCell*);
template<typename T>
void append(const Weak<T>& weak);
void appendHiddenUnbarriered(JSValue);
void appendHiddenUnbarriered(JSCell*);
bool addOpaqueRoot(void*); // Returns true if the root was new.
bool containsOpaqueRoot(void*) const;
bool isEmpty() { return m_collectorStack.isEmpty() && m_mutatorStack.isEmpty(); }
bool isFirstVisit() const { return m_isFirstVisit; }
void didStartMarking();
void reset();
void clearMarkStacks();
size_t bytesVisited() const { return m_bytesVisited; }
size_t visitCount() const { return m_visitCount; }
void addToVisitCount(size_t value) { m_visitCount += value; }
void donate();
void drain(MonotonicTime timeout = MonotonicTime::infinity());
void donateAndDrain(MonotonicTime timeout = MonotonicTime::infinity());
enum SharedDrainMode { HelperDrain, MainDrain };
enum class SharedDrainResult { Done, TimedOut };
SharedDrainResult drainFromShared(SharedDrainMode, MonotonicTime timeout = MonotonicTime::infinity());
SharedDrainResult drainInParallel(MonotonicTime timeout = MonotonicTime::infinity());
SharedDrainResult drainInParallelPassively(MonotonicTime timeout = MonotonicTime::infinity());
SharedDrainResult waitForTermination(MonotonicTime timeout = MonotonicTime::infinity());
// Attempts to perform an increment of draining that involves only walking `bytes` worth of data. This
// is likely to accidentally walk more or less than that. It will usually mark more than bytes. It may
// mark less than bytes if we're reaching termination or if the global worklist is empty (which may in
// rare cases happen temporarily even if we're not reaching termination).
size_t performIncrementOfDraining(size_t bytes);
// This informs the GC about auxiliary of some size that we are keeping alive. If you don't do
// this then the space will be freed at end of GC.
void markAuxiliary(const void* base);
void reportExtraMemoryVisited(size_t);
#if ENABLE(RESOURCE_USAGE)
void reportExternalMemoryVisited(size_t);
#endif
void dump(PrintStream&) const;
bool isAnalyzingHeap() const { return !!m_heapAnalyzer; }
HeapAnalyzer* heapAnalyzer() const { return m_heapAnalyzer; }
RootMarkReason rootMarkReason() const { return m_rootMarkReason; }
void setRootMarkReason(RootMarkReason reason) { m_rootMarkReason = reason; }
HeapVersion markingVersion() const { return m_markingVersion; }
bool mutatorIsStopped() const { return m_mutatorIsStopped; }
Lock& rightToRun() { return m_rightToRun; }
void updateMutatorIsStopped(const AbstractLocker&);
void updateMutatorIsStopped();
bool hasAcknowledgedThatTheMutatorIsResumed() const;
bool mutatorIsStoppedIsUpToDate() const;
void optimizeForStoppedMutator();
void didRace(const VisitRaceKey&);
void didRace(JSCell* cell, const char* reason) { didRace(VisitRaceKey(cell, reason)); }
void visitAsConstraint(const JSCell*);
bool didReachTermination();
void setIgnoreNewOpaqueRoots(bool value) { m_ignoreNewOpaqueRoots = value; }
void donateAll();
const char* codeName() const { return m_codeName.data(); }
JS_EXPORT_PRIVATE void addParallelConstraintTask(RefPtr<SharedTask<void(SlotVisitor&)>>);
private:
friend class ParallelModeEnabler;
friend class MarkingConstraintSolver;
void appendJSCellOrAuxiliary(HeapCell*);
JS_EXPORT_PRIVATE void appendSlow(JSCell*, Dependency);
JS_EXPORT_PRIVATE void appendHiddenSlow(JSCell*, Dependency);
void appendHiddenSlowImpl(JSCell*, Dependency);
template<typename ContainerType>
void setMarkedAndAppendToMarkStack(ContainerType&, JSCell*, Dependency);
void appendToMarkStack(JSCell*);
template<typename ContainerType>
void appendToMarkStack(ContainerType&, JSCell*);
void noteLiveAuxiliaryCell(HeapCell*);
void visitChildren(const JSCell*);
void propagateExternalMemoryVisitedIfNecessary();
void donateKnownParallel();
void donateKnownParallel(MarkStackArray& from, MarkStackArray& to);
void donateAll(const AbstractLocker&);
bool hasWork(const AbstractLocker&);
bool didReachTermination(const AbstractLocker&);
template<typename Func>
IterationStatus forEachMarkStack(const Func&);
MarkStackArray& correspondingGlobalStack(MarkStackArray&);
MarkStackArray m_collectorStack;
MarkStackArray m_mutatorStack;
size_t m_bytesVisited;
size_t m_visitCount;
size_t m_nonCellVisitCount { 0 }; // Used for incremental draining, ignored otherwise.
CheckedSize m_extraMemorySize { 0 };
bool m_isInParallelMode;
bool m_ignoreNewOpaqueRoots { false }; // Useful as a debugging mode.
HeapVersion m_markingVersion;
Heap& m_heap;
HeapAnalyzer* m_heapAnalyzer { nullptr };
JSCell* m_currentCell { nullptr };
RootMarkReason m_rootMarkReason { RootMarkReason::None };
bool m_isFirstVisit { false };
bool m_mutatorIsStopped { false };
bool m_canOptimizeForStoppedMutator { false };
Lock m_rightToRun;
CString m_codeName;
MarkingConstraint* m_currentConstraint { nullptr };
MarkingConstraintSolver* m_currentSolver { nullptr };
// Put padding here to mitigate false sharing between multiple SlotVisitors.
char padding[64];
public:
#if ASSERT_ENABLED
bool m_isCheckingForDefaultMarkViolation;
bool m_isDraining;
#endif
};
class ParallelModeEnabler {
public:
ParallelModeEnabler(SlotVisitor& stack)
: m_stack(stack)
{
ASSERT(!m_stack.m_isInParallelMode);
m_stack.m_isInParallelMode = true;
}
~ParallelModeEnabler()
{
ASSERT(m_stack.m_isInParallelMode);
m_stack.m_isInParallelMode = false;
}
private:
SlotVisitor& m_stack;
};
class SetRootMarkReasonScope {
public:
SetRootMarkReasonScope(SlotVisitor& visitor, SlotVisitor::RootMarkReason reason)
: m_visitor(visitor)
, m_previousReason(visitor.rootMarkReason())
{
m_visitor.setRootMarkReason(reason);
}
~SetRootMarkReasonScope()
{
m_visitor.setRootMarkReason(m_previousReason);
}
private:
SlotVisitor& m_visitor;
SlotVisitor::RootMarkReason m_previousReason;
};
} // namespace JSC