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
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
// 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_PTR_COMPR_INL_H_
#define V8_PTR_COMPR_INL_H_
#if V8_TARGET_ARCH_64_BIT
#include "src/objects/heap-object-inl.h"
#include "src/ptr-compr.h"
namespace v8 {
namespace internal {
// Compresses full-pointer representation of a tagged value to on-heap
// representation.
V8_INLINE Tagged_t CompressTagged(Address tagged) {
return static_cast<Tagged_t>(static_cast<uint32_t>(tagged));
}
// Calculates isolate root value from any on-heap address.
V8_INLINE Address GetRootFromOnHeapAddress(Address addr) {
return RoundDown(addr + kPtrComprIsolateRootBias,
kPtrComprIsolateRootAlignment);
}
// Decompresses weak or strong heap object pointer or forwarding pointer,
// preserving both weak- and smi- tags.
V8_INLINE Address DecompressTaggedPointer(Address on_heap_addr,
Tagged_t raw_value) {
static_assert(kTaggedSize == kSystemPointerSize, "has to be updated");
static_assert(!std::is_same<int32_t, Tagged_t>::value, "remove cast below");
int32_t value = static_cast<int32_t>(raw_value);
Address root = GetRootFromOnHeapAddress(on_heap_addr);
// Current compression scheme requires value to be sign-extended to inptr_t
// before adding the |root|.
return root + static_cast<Address>(static_cast<intptr_t>(value));
}
// Decompresses any tagged value, preserving both weak- and smi- tags.
V8_INLINE Address DecompressTaggedAny(Address on_heap_addr,
Tagged_t raw_value) {
static_assert(kTaggedSize == kSystemPointerSize, "has to be updated");
static_assert(!std::is_same<int32_t, Tagged_t>::value, "remove cast below");
int32_t value = static_cast<int32_t>(raw_value);
// |root_mask| is 0 if the |value| was a smi or -1 otherwise.
Address root_mask = -static_cast<Address>(value & kSmiTagMask);
Address root_or_zero = root_mask & GetRootFromOnHeapAddress(on_heap_addr);
// Current compression scheme requires value to be sign-extended to inptr_t
// before adding the |root_or_zero|.
return root_or_zero + static_cast<Address>(static_cast<intptr_t>(value));
}
STATIC_ASSERT(kPtrComprHeapReservationSize ==
Internals::kPtrComprHeapReservationSize);
STATIC_ASSERT(kPtrComprIsolateRootBias == Internals::kPtrComprIsolateRootBias);
STATIC_ASSERT(kPtrComprIsolateRootAlignment ==
Internals::kPtrComprIsolateRootAlignment);
//
// CompressedObjectSlot implementation.
//
CompressedObjectSlot::CompressedObjectSlot(Object* object)
: SlotBase(reinterpret_cast<Address>(&object->ptr_)) {}
Object CompressedObjectSlot::operator*() const {
Tagged_t value = *location();
return Object(DecompressTaggedAny(address(), value));
}
void CompressedObjectSlot::store(Object value) const {
*location() = CompressTagged(value->ptr());
}
Object CompressedObjectSlot::Acquire_Load() const {
AtomicTagged_t value = AsAtomicTagged::Acquire_Load(location());
return Object(DecompressTaggedAny(address(), value));
}
Object CompressedObjectSlot::Relaxed_Load() const {
AtomicTagged_t value = AsAtomicTagged::Relaxed_Load(location());
return Object(DecompressTaggedAny(address(), value));
}
void CompressedObjectSlot::Relaxed_Store(Object value) const {
Tagged_t ptr = CompressTagged(value->ptr());
AsAtomicTagged::Relaxed_Store(location(), ptr);
}
void CompressedObjectSlot::Release_Store(Object value) const {
Tagged_t ptr = CompressTagged(value->ptr());
AsAtomicTagged::Release_Store(location(), ptr);
}
Object CompressedObjectSlot::Release_CompareAndSwap(Object old,
Object target) const {
Tagged_t old_ptr = CompressTagged(old->ptr());
Tagged_t target_ptr = CompressTagged(target->ptr());
Tagged_t result =
AsAtomicTagged::Release_CompareAndSwap(location(), old_ptr, target_ptr);
return Object(DecompressTaggedAny(address(), result));
}
//
// CompressedMapWordSlot implementation.
//
bool CompressedMapWordSlot::contains_value(Address raw_value) const {
AtomicTagged_t value = AsAtomicTagged::Relaxed_Load(location());
return static_cast<uint32_t>(value) ==
static_cast<uint32_t>(static_cast<Tagged_t>(raw_value));
}
Object CompressedMapWordSlot::operator*() const {
Tagged_t value = *location();
return Object(DecompressTaggedPointer(address(), value));
}
void CompressedMapWordSlot::store(Object value) const {
*location() = CompressTagged(value.ptr());
}
Object CompressedMapWordSlot::Relaxed_Load() const {
AtomicTagged_t value = AsAtomicTagged::Relaxed_Load(location());
return Object(DecompressTaggedPointer(address(), value));
}
void CompressedMapWordSlot::Relaxed_Store(Object value) const {
Tagged_t ptr = CompressTagged(value.ptr());
AsAtomicTagged::Relaxed_Store(location(), ptr);
}
Object CompressedMapWordSlot::Acquire_Load() const {
AtomicTagged_t value = AsAtomicTagged::Acquire_Load(location());
return Object(DecompressTaggedPointer(address(), value));
}
void CompressedMapWordSlot::Release_Store(Object value) const {
Tagged_t ptr = CompressTagged(value->ptr());
AsAtomicTagged::Release_Store(location(), ptr);
}
Object CompressedMapWordSlot::Release_CompareAndSwap(Object old,
Object target) const {
Tagged_t old_ptr = CompressTagged(old->ptr());
Tagged_t target_ptr = CompressTagged(target->ptr());
Tagged_t result =
AsAtomicTagged::Release_CompareAndSwap(location(), old_ptr, target_ptr);
return Object(DecompressTaggedPointer(address(), result));
}
//
// CompressedMaybeObjectSlot implementation.
//
MaybeObject CompressedMaybeObjectSlot::operator*() const {
Tagged_t value = *location();
return MaybeObject(DecompressTaggedAny(address(), value));
}
void CompressedMaybeObjectSlot::store(MaybeObject value) const {
*location() = CompressTagged(value->ptr());
}
MaybeObject CompressedMaybeObjectSlot::Relaxed_Load() const {
AtomicTagged_t value = AsAtomicTagged::Relaxed_Load(location());
return MaybeObject(DecompressTaggedAny(address(), value));
}
void CompressedMaybeObjectSlot::Relaxed_Store(MaybeObject value) const {
Tagged_t ptr = CompressTagged(value->ptr());
AsAtomicTagged::Relaxed_Store(location(), ptr);
}
void CompressedMaybeObjectSlot::Release_CompareAndSwap(
MaybeObject old, MaybeObject target) const {
Tagged_t old_ptr = CompressTagged(old->ptr());
Tagged_t target_ptr = CompressTagged(target->ptr());
AsAtomicTagged::Release_CompareAndSwap(location(), old_ptr, target_ptr);
}
//
// CompressedHeapObjectSlot implementation.
//
HeapObjectReference CompressedHeapObjectSlot::operator*() const {
Tagged_t value = *location();
return HeapObjectReference(DecompressTaggedPointer(address(), value));
}
void CompressedHeapObjectSlot::store(HeapObjectReference value) const {
*location() = CompressTagged(value.ptr());
}
HeapObject CompressedHeapObjectSlot::ToHeapObject() const {
Tagged_t value = *location();
DCHECK_EQ(value & kHeapObjectTagMask, kHeapObjectTag);
return HeapObject::cast(Object(DecompressTaggedPointer(address(), value)));
}
void CompressedHeapObjectSlot::StoreHeapObject(HeapObject value) const {
*location() = CompressTagged(value->ptr());
}
} // namespace internal
} // namespace v8
#endif // V8_TARGET_ARCH_64_BIT
#endif // V8_PTR_COMPR_INL_H_
|
