1 // Copyright 2006-2008 the V8 project authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 // The common functionality when building with or without snapshots.
10 #include "src/base/platform/platform.h"
11 #include "src/full-codegen.h"
12 #include "src/snapshot.h"
17 bool Snapshot::HaveASnapshotToStartFrom() {
18 return SnapshotBlob().data != NULL;
23 bool Snapshot::SnapshotIsValid(v8::StartupData* snapshot_blob) {
24 return !Snapshot::ExtractStartupData(snapshot_blob).is_empty() &&
25 !Snapshot::ExtractContextData(snapshot_blob).is_empty();
30 bool Snapshot::EmbedsScript() {
31 if (!HaveASnapshotToStartFrom()) return false;
32 const v8::StartupData blob = SnapshotBlob();
33 return ExtractMetadata(&blob).embeds_script();
37 uint32_t Snapshot::SizeOfFirstPage(AllocationSpace space) {
38 DCHECK(space >= FIRST_PAGED_SPACE && space <= LAST_PAGED_SPACE);
39 if (!HaveASnapshotToStartFrom()) {
40 return static_cast<uint32_t>(MemoryAllocator::PageAreaSize(space));
43 int offset = kFirstPageSizesOffset + (space - FIRST_PAGED_SPACE) * kInt32Size;
44 memcpy(&size, SnapshotBlob().data + offset, kInt32Size);
49 bool Snapshot::Initialize(Isolate* isolate) {
50 if (!HaveASnapshotToStartFrom()) return false;
51 base::ElapsedTimer timer;
52 if (FLAG_profile_deserialization) timer.Start();
54 const v8::StartupData blob = SnapshotBlob();
55 Vector<const byte> startup_data = ExtractStartupData(&blob);
56 SnapshotData snapshot_data(startup_data);
57 Deserializer deserializer(&snapshot_data);
58 bool success = isolate->Init(&deserializer);
59 if (FLAG_profile_deserialization) {
60 double ms = timer.Elapsed().InMillisecondsF();
61 int bytes = startup_data.length();
62 PrintF("[Deserializing isolate (%d bytes) took %0.3f ms]\n", bytes, ms);
68 MaybeHandle<Context> Snapshot::NewContextFromSnapshot(
69 Isolate* isolate, Handle<JSGlobalProxy> global_proxy,
70 Handle<FixedArray>* outdated_contexts_out) {
71 if (!HaveASnapshotToStartFrom()) return Handle<Context>();
72 base::ElapsedTimer timer;
73 if (FLAG_profile_deserialization) timer.Start();
75 const v8::StartupData blob = SnapshotBlob();
76 Vector<const byte> context_data = ExtractContextData(&blob);
77 SnapshotData snapshot_data(context_data);
78 Deserializer deserializer(&snapshot_data);
80 MaybeHandle<Object> maybe_context = deserializer.DeserializePartial(
81 isolate, global_proxy, outdated_contexts_out);
82 Handle<Object> result;
83 if (!maybe_context.ToHandle(&result)) return MaybeHandle<Context>();
84 CHECK(result->IsContext());
85 // If the snapshot does not contain a custom script, we need to update
86 // the global object for exactly one context.
87 CHECK(EmbedsScript() || (*outdated_contexts_out)->length() == 1);
88 if (FLAG_profile_deserialization) {
89 double ms = timer.Elapsed().InMillisecondsF();
90 int bytes = context_data.length();
91 PrintF("[Deserializing context (%d bytes) took %0.3f ms]\n", bytes, ms);
93 return Handle<Context>::cast(result);
97 void CalculateFirstPageSizes(bool is_default_snapshot,
98 const SnapshotData& startup_snapshot,
99 const SnapshotData& context_snapshot,
100 uint32_t* sizes_out) {
101 Vector<const SerializedData::Reservation> startup_reservations =
102 startup_snapshot.Reservations();
103 Vector<const SerializedData::Reservation> context_reservations =
104 context_snapshot.Reservations();
105 int startup_index = 0;
106 int context_index = 0;
107 for (int space = 0; space < i::Serializer::kNumberOfSpaces; space++) {
108 bool single_chunk = true;
109 while (!startup_reservations[startup_index].is_last()) {
110 single_chunk = false;
113 while (!context_reservations[context_index].is_last()) {
114 single_chunk = false;
118 uint32_t required = kMaxUInt32;
120 // If both the startup snapshot data and the context snapshot data on
121 // this space fit in a single page, then we consider limiting the size
122 // of the first page. For this, we add the chunk sizes and some extra
123 // allowance. This way we achieve a smaller startup memory footprint.
124 required = (startup_reservations[startup_index].chunk_size() +
125 2 * context_reservations[context_index].chunk_size()) +
126 Page::kObjectStartOffset;
128 // We expect the vanilla snapshot to only require on page per space.
129 DCHECK(!is_default_snapshot);
132 if (space >= FIRST_PAGED_SPACE && space <= LAST_PAGED_SPACE) {
134 MemoryAllocator::PageAreaSize(static_cast<AllocationSpace>(space));
135 sizes_out[space - FIRST_PAGED_SPACE] = Min(required, max_size);
137 DCHECK(single_chunk);
143 DCHECK_EQ(startup_reservations.length(), startup_index);
144 DCHECK_EQ(context_reservations.length(), context_index);
148 v8::StartupData Snapshot::CreateSnapshotBlob(
149 const i::StartupSerializer& startup_ser,
150 const i::PartialSerializer& context_ser, Snapshot::Metadata metadata) {
151 SnapshotData startup_snapshot(startup_ser);
152 SnapshotData context_snapshot(context_ser);
153 Vector<const byte> startup_data = startup_snapshot.RawData();
154 Vector<const byte> context_data = context_snapshot.RawData();
156 uint32_t first_page_sizes[kNumPagedSpaces];
158 CalculateFirstPageSizes(metadata.embeds_script(), startup_snapshot,
159 context_snapshot, first_page_sizes);
161 int startup_length = startup_data.length();
162 int context_length = context_data.length();
163 int context_offset = ContextOffset(startup_length);
165 int length = context_offset + context_length;
166 char* data = new char[length];
168 memcpy(data + kMetadataOffset, &metadata.RawValue(), kInt32Size);
169 memcpy(data + kFirstPageSizesOffset, first_page_sizes,
170 kNumPagedSpaces * kInt32Size);
171 memcpy(data + kStartupLengthOffset, &startup_length, kInt32Size);
172 memcpy(data + kStartupDataOffset, startup_data.begin(), startup_length);
173 memcpy(data + context_offset, context_data.begin(), context_length);
174 v8::StartupData result = {data, length};
179 Snapshot::Metadata Snapshot::ExtractMetadata(const v8::StartupData* data) {
181 memcpy(&raw, data->data + kMetadataOffset, kInt32Size);
182 return Metadata(raw);
186 Vector<const byte> Snapshot::ExtractStartupData(const v8::StartupData* data) {
187 DCHECK_LT(kIntSize, data->raw_size);
189 memcpy(&startup_length, data->data + kStartupLengthOffset, kInt32Size);
190 DCHECK_LT(startup_length, data->raw_size);
191 const byte* startup_data =
192 reinterpret_cast<const byte*>(data->data + kStartupDataOffset);
193 return Vector<const byte>(startup_data, startup_length);
197 Vector<const byte> Snapshot::ExtractContextData(const v8::StartupData* data) {
198 DCHECK_LT(kIntSize, data->raw_size);
200 memcpy(&startup_length, data->data + kStartupLengthOffset, kIntSize);
201 int context_offset = ContextOffset(startup_length);
202 const byte* context_data =
203 reinterpret_cast<const byte*>(data->data + context_offset);
204 DCHECK_LT(context_offset, data->raw_size);
205 int context_length = data->raw_size - context_offset;
206 return Vector<const byte>(context_data, context_length);
208 } } // namespace v8::internal