deps/v8/src/heap/objects-visiting.cc
// Copyright 2011 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.
#include "src/v8.h"
#include "src/heap/objects-visiting.h"
#include "src/ic-inl.h"
namespace v8 {
namespace internal {
StaticVisitorBase::VisitorId StaticVisitorBase::GetVisitorId(
int instance_type, int instance_size) {
if (instance_type < FIRST_NONSTRING_TYPE) {
switch (instance_type & kStringRepresentationMask) {
case kSeqStringTag:
if ((instance_type & kStringEncodingMask) == kOneByteStringTag) {
return kVisitSeqOneByteString;
} else {
return kVisitSeqTwoByteString;
}
case kConsStringTag:
if (IsShortcutCandidate(instance_type)) {
return kVisitShortcutCandidate;
} else {
return kVisitConsString;
}
case kSlicedStringTag:
return kVisitSlicedString;
case kExternalStringTag:
return GetVisitorIdForSize(kVisitDataObject, kVisitDataObjectGeneric,
instance_size);
}
UNREACHABLE();
}
switch (instance_type) {
case BYTE_ARRAY_TYPE:
return kVisitByteArray;
case FREE_SPACE_TYPE:
return kVisitFreeSpace;
case FIXED_ARRAY_TYPE:
return kVisitFixedArray;
case FIXED_DOUBLE_ARRAY_TYPE:
return kVisitFixedDoubleArray;
case CONSTANT_POOL_ARRAY_TYPE:
return kVisitConstantPoolArray;
case ODDBALL_TYPE:
return kVisitOddball;
case MAP_TYPE:
return kVisitMap;
case CODE_TYPE:
return kVisitCode;
case CELL_TYPE:
return kVisitCell;
case PROPERTY_CELL_TYPE:
return kVisitPropertyCell;
case JS_SET_TYPE:
return GetVisitorIdForSize(kVisitStruct, kVisitStructGeneric,
JSSet::kSize);
case JS_MAP_TYPE:
return GetVisitorIdForSize(kVisitStruct, kVisitStructGeneric,
JSMap::kSize);
case JS_WEAK_MAP_TYPE:
case JS_WEAK_SET_TYPE:
return kVisitJSWeakCollection;
case JS_REGEXP_TYPE:
return kVisitJSRegExp;
case SHARED_FUNCTION_INFO_TYPE:
return kVisitSharedFunctionInfo;
case JS_PROXY_TYPE:
return GetVisitorIdForSize(kVisitStruct, kVisitStructGeneric,
JSProxy::kSize);
case JS_FUNCTION_PROXY_TYPE:
return GetVisitorIdForSize(kVisitStruct, kVisitStructGeneric,
JSFunctionProxy::kSize);
case FOREIGN_TYPE:
return GetVisitorIdForSize(kVisitDataObject, kVisitDataObjectGeneric,
Foreign::kSize);
case SYMBOL_TYPE:
return kVisitSymbol;
case FILLER_TYPE:
return kVisitDataObjectGeneric;
case JS_ARRAY_BUFFER_TYPE:
return kVisitJSArrayBuffer;
case JS_TYPED_ARRAY_TYPE:
return kVisitJSTypedArray;
case JS_DATA_VIEW_TYPE:
return kVisitJSDataView;
case JS_OBJECT_TYPE:
case JS_CONTEXT_EXTENSION_OBJECT_TYPE:
case JS_GENERATOR_OBJECT_TYPE:
case JS_MODULE_TYPE:
case JS_VALUE_TYPE:
case JS_DATE_TYPE:
case JS_ARRAY_TYPE:
case JS_GLOBAL_PROXY_TYPE:
case JS_GLOBAL_OBJECT_TYPE:
case JS_BUILTINS_OBJECT_TYPE:
case JS_MESSAGE_OBJECT_TYPE:
case JS_SET_ITERATOR_TYPE:
case JS_MAP_ITERATOR_TYPE:
return GetVisitorIdForSize(kVisitJSObject, kVisitJSObjectGeneric,
instance_size);
case JS_FUNCTION_TYPE:
return kVisitJSFunction;
case HEAP_NUMBER_TYPE:
case MUTABLE_HEAP_NUMBER_TYPE:
#define EXTERNAL_ARRAY_CASE(Type, type, TYPE, ctype, size) \
case EXTERNAL_##TYPE##_ARRAY_TYPE:
TYPED_ARRAYS(EXTERNAL_ARRAY_CASE)
return GetVisitorIdForSize(kVisitDataObject, kVisitDataObjectGeneric,
instance_size);
#undef EXTERNAL_ARRAY_CASE
case FIXED_UINT8_ARRAY_TYPE:
case FIXED_INT8_ARRAY_TYPE:
case FIXED_UINT16_ARRAY_TYPE:
case FIXED_INT16_ARRAY_TYPE:
case FIXED_UINT32_ARRAY_TYPE:
case FIXED_INT32_ARRAY_TYPE:
case FIXED_FLOAT32_ARRAY_TYPE:
case FIXED_UINT8_CLAMPED_ARRAY_TYPE:
return kVisitFixedTypedArray;
case FIXED_FLOAT64_ARRAY_TYPE:
return kVisitFixedFloat64Array;
#define MAKE_STRUCT_CASE(NAME, Name, name) case NAME##_TYPE:
STRUCT_LIST(MAKE_STRUCT_CASE)
#undef MAKE_STRUCT_CASE
if (instance_type == ALLOCATION_SITE_TYPE) {
return kVisitAllocationSite;
}
return GetVisitorIdForSize(kVisitStruct, kVisitStructGeneric,
instance_size);
default:
UNREACHABLE();
return kVisitorIdCount;
}
}
// We don't record weak slots during marking or scavenges. Instead we do it
// once when we complete mark-compact cycle. Note that write barrier has no
// effect if we are already in the middle of compacting mark-sweep cycle and we
// have to record slots manually.
static bool MustRecordSlots(Heap* heap) {
return heap->gc_state() == Heap::MARK_COMPACT &&
heap->mark_compact_collector()->is_compacting();
}
template <class T>
struct WeakListVisitor;
template <class T>
Object* VisitWeakList(Heap* heap, Object* list, WeakObjectRetainer* retainer) {
Object* undefined = heap->undefined_value();
Object* head = undefined;
T* tail = NULL;
MarkCompactCollector* collector = heap->mark_compact_collector();
bool record_slots = MustRecordSlots(heap);
while (list != undefined) {
// Check whether to keep the candidate in the list.
T* candidate = reinterpret_cast<T*>(list);
Object* retained = retainer->RetainAs(list);
if (retained != NULL) {
if (head == undefined) {
// First element in the list.
head = retained;
} else {
// Subsequent elements in the list.
DCHECK(tail != NULL);
WeakListVisitor<T>::SetWeakNext(tail, retained);
if (record_slots) {
Object** next_slot =
HeapObject::RawField(tail, WeakListVisitor<T>::WeakNextOffset());
collector->RecordSlot(next_slot, next_slot, retained);
}
}
// Retained object is new tail.
DCHECK(!retained->IsUndefined());
candidate = reinterpret_cast<T*>(retained);
tail = candidate;
// tail is a live object, visit it.
WeakListVisitor<T>::VisitLiveObject(heap, tail, retainer);
} else {
WeakListVisitor<T>::VisitPhantomObject(heap, candidate);
}
// Move to next element in the list.
list = WeakListVisitor<T>::WeakNext(candidate);
}
// Terminate the list if there is one or more elements.
if (tail != NULL) {
WeakListVisitor<T>::SetWeakNext(tail, undefined);
}
return head;
}
template <class T>
static void ClearWeakList(Heap* heap, Object* list) {
Object* undefined = heap->undefined_value();
while (list != undefined) {
T* candidate = reinterpret_cast<T*>(list);
list = WeakListVisitor<T>::WeakNext(candidate);
WeakListVisitor<T>::SetWeakNext(candidate, undefined);
}
}
template <>
struct WeakListVisitor<JSFunction> {
static void SetWeakNext(JSFunction* function, Object* next) {
function->set_next_function_link(next);
}
static Object* WeakNext(JSFunction* function) {
return function->next_function_link();
}
static int WeakNextOffset() { return JSFunction::kNextFunctionLinkOffset; }
static void VisitLiveObject(Heap*, JSFunction*, WeakObjectRetainer*) {}
static void VisitPhantomObject(Heap*, JSFunction*) {}
};
template <>
struct WeakListVisitor<Code> {
static void SetWeakNext(Code* code, Object* next) {
code->set_next_code_link(next);
}
static Object* WeakNext(Code* code) { return code->next_code_link(); }
static int WeakNextOffset() { return Code::kNextCodeLinkOffset; }
static void VisitLiveObject(Heap*, Code*, WeakObjectRetainer*) {}
static void VisitPhantomObject(Heap*, Code*) {}
};
template <>
struct WeakListVisitor<Context> {
static void SetWeakNext(Context* context, Object* next) {
context->set(Context::NEXT_CONTEXT_LINK, next, UPDATE_WRITE_BARRIER);
}
static Object* WeakNext(Context* context) {
return context->get(Context::NEXT_CONTEXT_LINK);
}
static int WeakNextOffset() {
return FixedArray::SizeFor(Context::NEXT_CONTEXT_LINK);
}
static void VisitLiveObject(Heap* heap, Context* context,
WeakObjectRetainer* retainer) {
// Process the three weak lists linked off the context.
DoWeakList<JSFunction>(heap, context, retainer,
Context::OPTIMIZED_FUNCTIONS_LIST);
DoWeakList<Code>(heap, context, retainer, Context::OPTIMIZED_CODE_LIST);
DoWeakList<Code>(heap, context, retainer, Context::DEOPTIMIZED_CODE_LIST);
}
template <class T>
static void DoWeakList(Heap* heap, Context* context,
WeakObjectRetainer* retainer, int index) {
// Visit the weak list, removing dead intermediate elements.
Object* list_head = VisitWeakList<T>(heap, context->get(index), retainer);
// Update the list head.
context->set(index, list_head, UPDATE_WRITE_BARRIER);
if (MustRecordSlots(heap)) {
// Record the updated slot if necessary.
Object** head_slot =
HeapObject::RawField(context, FixedArray::SizeFor(index));
heap->mark_compact_collector()->RecordSlot(head_slot, head_slot,
list_head);
}
}
static void VisitPhantomObject(Heap* heap, Context* context) {
ClearWeakList<JSFunction>(heap,
context->get(Context::OPTIMIZED_FUNCTIONS_LIST));
ClearWeakList<Code>(heap, context->get(Context::OPTIMIZED_CODE_LIST));
ClearWeakList<Code>(heap, context->get(Context::DEOPTIMIZED_CODE_LIST));
}
};
template <>
struct WeakListVisitor<JSArrayBufferView> {
static void SetWeakNext(JSArrayBufferView* obj, Object* next) {
obj->set_weak_next(next);
}
static Object* WeakNext(JSArrayBufferView* obj) { return obj->weak_next(); }
static int WeakNextOffset() { return JSArrayBufferView::kWeakNextOffset; }
static void VisitLiveObject(Heap*, JSArrayBufferView*, WeakObjectRetainer*) {}
static void VisitPhantomObject(Heap*, JSArrayBufferView*) {}
};
template <>
struct WeakListVisitor<JSArrayBuffer> {
static void SetWeakNext(JSArrayBuffer* obj, Object* next) {
obj->set_weak_next(next);
}
static Object* WeakNext(JSArrayBuffer* obj) { return obj->weak_next(); }
static int WeakNextOffset() { return JSArrayBuffer::kWeakNextOffset; }
static void VisitLiveObject(Heap* heap, JSArrayBuffer* array_buffer,
WeakObjectRetainer* retainer) {
Object* typed_array_obj = VisitWeakList<JSArrayBufferView>(
heap, array_buffer->weak_first_view(), retainer);
array_buffer->set_weak_first_view(typed_array_obj);
if (typed_array_obj != heap->undefined_value() && MustRecordSlots(heap)) {
Object** slot = HeapObject::RawField(array_buffer,
JSArrayBuffer::kWeakFirstViewOffset);
heap->mark_compact_collector()->RecordSlot(slot, slot, typed_array_obj);
}
}
static void VisitPhantomObject(Heap* heap, JSArrayBuffer* phantom) {
Runtime::FreeArrayBuffer(heap->isolate(), phantom);
}
};
template <>
struct WeakListVisitor<AllocationSite> {
static void SetWeakNext(AllocationSite* obj, Object* next) {
obj->set_weak_next(next);
}
static Object* WeakNext(AllocationSite* obj) { return obj->weak_next(); }
static int WeakNextOffset() { return AllocationSite::kWeakNextOffset; }
static void VisitLiveObject(Heap*, AllocationSite*, WeakObjectRetainer*) {}
static void VisitPhantomObject(Heap*, AllocationSite*) {}
};
template Object* VisitWeakList<Code>(Heap* heap, Object* list,
WeakObjectRetainer* retainer);
template Object* VisitWeakList<JSFunction>(Heap* heap, Object* list,
WeakObjectRetainer* retainer);
template Object* VisitWeakList<Context>(Heap* heap, Object* list,
WeakObjectRetainer* retainer);
template Object* VisitWeakList<JSArrayBuffer>(Heap* heap, Object* list,
WeakObjectRetainer* retainer);
template Object* VisitWeakList<AllocationSite>(Heap* heap, Object* list,
WeakObjectRetainer* retainer);
}
} // namespace v8::internal