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// Copyright 2018 the V8 project authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef V8_OBJECTS_ALLOCATION_SITE_H_
#define V8_OBJECTS_ALLOCATION_SITE_H_
#include "src/objects/objects.h"
#include "src/objects/struct.h"
// Has to be the last include (doesn't have include guards):
#include "src/objects/object-macros.h"
namespace v8 {
namespace internal {
enum InstanceType : uint16_t;
class AllocationSite : public Struct {
public:
NEVER_READ_ONLY_SPACE
static const uint32_t kMaximumArrayBytesToPretransition = 8 * 1024;
static const double kPretenureRatio;
static const int kPretenureMinimumCreated = 100;
// Values for pretenure decision field.
enum PretenureDecision {
kUndecided = 0,
kDontTenure = 1,
kMaybeTenure = 2,
kTenure = 3,
kZombie = 4,
kLastPretenureDecisionValue = kZombie
};
const char* PretenureDecisionName(PretenureDecision decision);
// Contains either a Smi-encoded bitfield or a boilerplate. If it's a Smi the
// AllocationSite is for a constructed Array.
DECL_ACCESSORS(transition_info_or_boilerplate, Object)
DECL_ACCESSORS(boilerplate, JSObject)
DECL_INT_ACCESSORS(transition_info)
// nested_site threads a list of sites that represent nested literals
// walked in a particular order. So [[1, 2], 1, 2] will have one
// nested_site, but [[1, 2], 3, [4]] will have a list of two.
DECL_ACCESSORS(nested_site, Object)
// Bitfield containing pretenuring information.
DECL_INT32_ACCESSORS(pretenure_data)
DECL_INT32_ACCESSORS(pretenure_create_count)
DECL_ACCESSORS(dependent_code, DependentCode)
// heap->allocation_site_list() points to the last AllocationSite which form
// a linked list through the weak_next property. The GC might remove elements
// from the list by updateing weak_next.
DECL_ACCESSORS(weak_next, Object)
inline void Initialize();
// Checks if the allocation site contain weak_next field;
inline bool HasWeakNext() const;
// This method is expensive, it should only be called for reporting.
bool IsNested();
// transition_info bitfields, for constructed array transition info.
using ElementsKindBits = BitField<ElementsKind, 0, 5>;
using DoNotInlineBit = BitField<bool, 5, 1>;
// Unused bits 6-30.
// Bitfields for pretenure_data
using MementoFoundCountBits = BitField<int, 0, 26>;
using PretenureDecisionBits = BitField<PretenureDecision, 26, 3>;
using DeoptDependentCodeBit = BitField<bool, 29, 1>;
STATIC_ASSERT(PretenureDecisionBits::kMax >= kLastPretenureDecisionValue);
// Increments the mementos found counter and returns true when the first
// memento was found for a given allocation site.
inline bool IncrementMementoFoundCount(int increment = 1);
inline void IncrementMementoCreateCount();
AllocationType GetAllocationType() const;
void ResetPretenureDecision();
inline PretenureDecision pretenure_decision() const;
inline void set_pretenure_decision(PretenureDecision decision);
inline bool deopt_dependent_code() const;
inline void set_deopt_dependent_code(bool deopt);
inline int memento_found_count() const;
inline void set_memento_found_count(int count);
inline int memento_create_count() const;
inline void set_memento_create_count(int count);
// The pretenuring decision is made during gc, and the zombie state allows
// us to recognize when an allocation site is just being kept alive because
// a later traversal of new space may discover AllocationMementos that point
// to this AllocationSite.
inline bool IsZombie() const;
inline bool IsMaybeTenure() const;
inline void MarkZombie();
inline bool MakePretenureDecision(PretenureDecision current_decision,
double ratio, bool maximum_size_scavenge);
inline bool DigestPretenuringFeedback(bool maximum_size_scavenge);
inline ElementsKind GetElementsKind() const;
inline void SetElementsKind(ElementsKind kind);
inline bool CanInlineCall() const;
inline void SetDoNotInlineCall();
inline bool PointsToLiteral() const;
template <AllocationSiteUpdateMode update_or_check =
AllocationSiteUpdateMode::kUpdate>
static bool DigestTransitionFeedback(Handle<AllocationSite> site,
ElementsKind to_kind);
DECL_PRINTER(AllocationSite)
DECL_VERIFIER(AllocationSite)
DECL_CAST(AllocationSite)
static inline bool ShouldTrack(ElementsKind boilerplate_elements_kind);
static bool ShouldTrack(ElementsKind from, ElementsKind to);
static inline bool CanTrack(InstanceType type);
// Layout description.
// AllocationSite has to start with TransitionInfoOrboilerPlateOffset
// and end with WeakNext field.
#define ALLOCATION_SITE_FIELDS(V) \
V(kStartOffset, 0) \
V(kTransitionInfoOrBoilerplateOffset, kTaggedSize) \
V(kNestedSiteOffset, kTaggedSize) \
V(kDependentCodeOffset, kTaggedSize) \
V(kCommonPointerFieldEndOffset, 0) \
V(kPretenureDataOffset, kInt32Size) \
V(kPretenureCreateCountOffset, kInt32Size) \
/* Size of AllocationSite without WeakNext field */ \
V(kSizeWithoutWeakNext, 0) \
V(kWeakNextOffset, kTaggedSize) \
/* Size of AllocationSite with WeakNext field */ \
V(kSizeWithWeakNext, 0)
DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize, ALLOCATION_SITE_FIELDS)
#undef ALLOCATION_SITE_FIELDS
class BodyDescriptor;
private:
inline bool PretenuringDecisionMade() const;
OBJECT_CONSTRUCTORS(AllocationSite, Struct);
};
class AllocationMemento : public Struct {
public:
// Layout description.
DEFINE_FIELD_OFFSET_CONSTANTS(HeapObject::kHeaderSize,
TORQUE_GENERATED_ALLOCATION_MEMENTO_FIELDS)
DECL_ACCESSORS(allocation_site, Object)
inline bool IsValid() const;
inline AllocationSite GetAllocationSite() const;
inline Address GetAllocationSiteUnchecked() const;
DECL_PRINTER(AllocationMemento)
DECL_VERIFIER(AllocationMemento)
DECL_CAST(AllocationMemento)
OBJECT_CONSTRUCTORS(AllocationMemento, Struct);
};
} // namespace internal
} // namespace v8
#include "src/objects/object-macros-undef.h"
#endif // V8_OBJECTS_ALLOCATION_SITE_H_
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