1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
|
// Copyright 2006-2008 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_HANDLES_INL_H_
#define V8_HANDLES_INL_H_
#include "src/api.h"
#include "src/handles.h"
#include "src/heap/heap.h"
#include "src/isolate.h"
namespace v8 {
namespace internal {
template<typename T>
Handle<T>::Handle(T* obj) {
location_ = HandleScope::CreateHandle(obj->GetIsolate(), obj);
}
template<typename T>
Handle<T>::Handle(T* obj, Isolate* isolate) {
location_ = HandleScope::CreateHandle(isolate, obj);
}
template <typename T>
inline bool Handle<T>::is_identical_to(const Handle<T> o) const {
// Dereferencing deferred handles to check object equality is safe.
SLOW_DCHECK(
(location_ == NULL || IsDereferenceAllowed(NO_DEFERRED_CHECK)) &&
(o.location_ == NULL || o.IsDereferenceAllowed(NO_DEFERRED_CHECK)));
if (location_ == o.location_) return true;
if (location_ == NULL || o.location_ == NULL) return false;
return *location_ == *o.location_;
}
template <typename T>
inline T* Handle<T>::operator*() const {
SLOW_DCHECK(IsDereferenceAllowed(INCLUDE_DEFERRED_CHECK));
return *BitCast<T**>(location_);
}
template <typename T>
inline T** Handle<T>::location() const {
SLOW_DCHECK(location_ == NULL ||
IsDereferenceAllowed(INCLUDE_DEFERRED_CHECK));
return location_;
}
#ifdef DEBUG
template <typename T>
bool Handle<T>::IsDereferenceAllowed(DereferenceCheckMode mode) const {
DCHECK(location_ != NULL);
Object* object = *BitCast<T**>(location_);
if (object->IsSmi()) return true;
HeapObject* heap_object = HeapObject::cast(object);
Heap* heap = heap_object->GetHeap();
Object** handle = reinterpret_cast<Object**>(location_);
Object** roots_array_start = heap->roots_array_start();
if (roots_array_start <= handle &&
handle < roots_array_start + Heap::kStrongRootListLength &&
heap->RootCanBeTreatedAsConstant(
static_cast<Heap::RootListIndex>(handle - roots_array_start))) {
return true;
}
if (!AllowHandleDereference::IsAllowed()) return false;
if (mode == INCLUDE_DEFERRED_CHECK &&
!AllowDeferredHandleDereference::IsAllowed()) {
// Accessing cells, maps and internalized strings is safe.
if (heap_object->IsCell()) return true;
if (heap_object->IsMap()) return true;
if (heap_object->IsInternalizedString()) return true;
return !heap->isolate()->IsDeferredHandle(handle);
}
return true;
}
#endif
HandleScope::HandleScope(Isolate* isolate) {
HandleScopeData* current = isolate->handle_scope_data();
isolate_ = isolate;
prev_next_ = current->next;
prev_limit_ = current->limit;
current->level++;
}
HandleScope::~HandleScope() {
CloseScope(isolate_, prev_next_, prev_limit_);
}
void HandleScope::CloseScope(Isolate* isolate,
Object** prev_next,
Object** prev_limit) {
HandleScopeData* current = isolate->handle_scope_data();
std::swap(current->next, prev_next);
current->level--;
if (current->limit != prev_limit) {
current->limit = prev_limit;
DeleteExtensions(isolate);
#ifdef ENABLE_HANDLE_ZAPPING
ZapRange(current->next, prev_limit);
} else {
ZapRange(current->next, prev_next);
#endif
}
}
template <typename T>
Handle<T> HandleScope::CloseAndEscape(Handle<T> handle_value) {
HandleScopeData* current = isolate_->handle_scope_data();
T* value = *handle_value;
// Throw away all handles in the current scope.
CloseScope(isolate_, prev_next_, prev_limit_);
// Allocate one handle in the parent scope.
DCHECK(current->level > 0);
Handle<T> result(CreateHandle<T>(isolate_, value));
// Reinitialize the current scope (so that it's ready
// to be used or closed again).
prev_next_ = current->next;
prev_limit_ = current->limit;
current->level++;
return result;
}
template <typename T>
T** HandleScope::CreateHandle(Isolate* isolate, T* value) {
DCHECK(AllowHandleAllocation::IsAllowed());
HandleScopeData* current = isolate->handle_scope_data();
internal::Object** cur = current->next;
if (cur == current->limit) cur = Extend(isolate);
// Update the current next field, set the value in the created
// handle, and return the result.
DCHECK(cur < current->limit);
current->next = cur + 1;
T** result = reinterpret_cast<T**>(cur);
*result = value;
return result;
}
#ifdef DEBUG
inline SealHandleScope::SealHandleScope(Isolate* isolate) : isolate_(isolate) {
// Make sure the current thread is allowed to create handles to begin with.
CHECK(AllowHandleAllocation::IsAllowed());
HandleScopeData* current = isolate_->handle_scope_data();
// Shrink the current handle scope to make it impossible to do
// handle allocations without an explicit handle scope.
limit_ = current->limit;
current->limit = current->next;
level_ = current->level;
current->level = 0;
}
inline SealHandleScope::~SealHandleScope() {
// Restore state in current handle scope to re-enable handle
// allocations.
HandleScopeData* current = isolate_->handle_scope_data();
DCHECK_EQ(0, current->level);
current->level = level_;
DCHECK_EQ(current->next, current->limit);
current->limit = limit_;
}
#endif
} } // namespace v8::internal
#endif // V8_HANDLES_INL_H_
|
