[web snapshot] Make ValueSerializer an inline member

We can avoid a pointer deref if the ValueSerializer is inlined in
WebSnapshotDeserializer.

Bug: v8:11525
Change-Id: I92d8cac37af3fdbe04a66465f97761bf5a9fd705
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3417433Reviewed-by: Marja Hölttä <marja@chromium.org>
Commit-Queue: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#78830}

src/api/api.cc

@@ -2087,8 +2087,10 @@ MaybeLocal<Value> Script::Run(Local<Context> context,
         handle(fun->shared().script(), isolate);
     if (maybe_script->IsScript() &&
         i::Script::cast(*maybe_script).type() == i::Script::TYPE_WEB_SNAPSHOT) {
-      i::WebSnapshotDeserializer deserializer(v8_isolate);
-      deserializer.UseWebSnapshot(i::Handle<i::Script>::cast(maybe_script));
+      i::WebSnapshotDeserializer deserializer(
+          reinterpret_cast<i::Isolate*>(v8_isolate),
+          i::Handle<i::Script>::cast(maybe_script));
+      deserializer.Deserialize();
       RETURN_ON_FAILED_EXECUTION(Value);
       Local<Value> result = v8::Undefined(v8_isolate);
       RETURN_ESCAPED(result);

src/d8/d8.cc

@@ -1443,9 +1443,9 @@ bool Shell::ExecuteWebSnapshot(Isolate* isolate, const char* file_name) {
   if (length == 0) {
     isolate->ThrowError("Could not read the web snapshot file");
   } else {
-    i::WebSnapshotDeserializer deserializer(isolate);
-    success = deserializer.UseWebSnapshot(snapshot_data.get(),
-                                          static_cast<size_t>(length));
+    i::WebSnapshotDeserializer deserializer(isolate, snapshot_data.get(),
+                                            static_cast<size_t>(length));
+    success = deserializer.Deserialize();
   }
   if (!success) {
     CHECK(try_catch.HasCaught());
@@ -2003,9 +2003,10 @@ void Shell::RealmUseWebSnapshot(
   // Deserialize the snapshot in the specified Realm.
   {
     PerIsolateData::ExplicitRealmScope realm_scope(data, index);
-    i::WebSnapshotDeserializer deserializer(isolate);
-    bool success = deserializer.UseWebSnapshot(
-        snapshot_data_shared->buffer, snapshot_data_shared->buffer_size);
+    i::WebSnapshotDeserializer deserializer(isolate,
+                                            snapshot_data_shared->buffer,
+                                            snapshot_data_shared->buffer_size);
+    bool success = deserializer.Deserialize();
     args.GetReturnValue().Set(success);
   }
 }

src/web-snapshot/web-snapshot.h

@@ -228,10 +228,11 @@ class V8_EXPORT WebSnapshotSerializer
 class V8_EXPORT WebSnapshotDeserializer
     : public WebSnapshotSerializerDeserializer {
  public:
-  explicit WebSnapshotDeserializer(v8::Isolate* v8_isolate);
+  WebSnapshotDeserializer(v8::Isolate* v8_isolate, const uint8_t* data,
+                          size_t buffer_size);
+  WebSnapshotDeserializer(Isolate* isolate, Handle<Script> snapshot_as_script);
   ~WebSnapshotDeserializer();
-  bool UseWebSnapshot(const uint8_t* data, size_t buffer_size);
-  bool UseWebSnapshot(Handle<Script> snapshot_as_script);
+  bool Deserialize();
 
   // For inspecting the state after deserializing a snapshot.
   uint32_t string_count() const { return string_count_; }
@@ -243,7 +244,10 @@ class V8_EXPORT WebSnapshotDeserializer
   uint32_t object_count() const { return object_count_; }
 
  private:
-  bool Deserialize();
+  WebSnapshotDeserializer(Isolate* isolate, Handle<Object> script_name,
+                          base::Vector<const uint8_t> buffer);
+  base::Vector<const uint8_t> ExtractScriptBuffer(
+      Isolate* isolate, Handle<Script> snapshot_as_script);
   bool DeserializeSnapshot();
   bool DeserializeScript();
 
@@ -305,7 +309,7 @@ class V8_EXPORT WebSnapshotDeserializer
   uint32_t object_count_ = 0;
   uint32_t current_object_count_ = 0;
 
-  std::unique_ptr<ValueDeserializer> deserializer_;
+  ValueDeserializer deserializer_;
 
   bool deserialized_ = false;
 };

test/cctest/test-web-snapshots.cc

@@ -47,9 +47,9 @@ void TestWebSnapshotExtensive(
     v8::HandleScope scope(isolate);
     v8::Local<v8::Context> new_context = CcTest::NewContext();
     v8::Context::Scope context_scope(new_context);
-    WebSnapshotDeserializer deserializer(isolate);
-    CHECK(deserializer.UseWebSnapshot(snapshot_data.buffer,
-                                      snapshot_data.buffer_size));
+    WebSnapshotDeserializer deserializer(isolate, snapshot_data.buffer,
+                                         snapshot_data.buffer_size);
+    CHECK(deserializer.Deserialize());
     CHECK(!deserializer.has_error());
     tester(isolate, new_context);
     CHECK_EQ(string_count, deserializer.string_count());
@@ -343,9 +343,9 @@ TEST(SFIDeduplication) {
   {
     v8::Local<v8::Context> new_context = CcTest::NewContext();
     v8::Context::Scope context_scope(new_context);
-    WebSnapshotDeserializer deserializer(isolate);
-    CHECK(deserializer.UseWebSnapshot(snapshot_data.buffer,
-                                      snapshot_data.buffer_size));
+    WebSnapshotDeserializer deserializer(isolate, snapshot_data.buffer,
+                                         snapshot_data.buffer_size);
+    CHECK(deserializer.Deserialize());
     CHECK(!deserializer.has_error());
 
     const char* get_inner = "foo.inner";
@@ -399,9 +399,9 @@ TEST(SFIDeduplicationClasses) {
   {
     v8::Local<v8::Context> new_context = CcTest::NewContext();
     v8::Context::Scope context_scope(new_context);
-    WebSnapshotDeserializer deserializer(isolate);
-    CHECK(deserializer.UseWebSnapshot(snapshot_data.buffer,
-                                      snapshot_data.buffer_size));
+    WebSnapshotDeserializer deserializer(isolate, snapshot_data.buffer,
+                                         snapshot_data.buffer_size);
+    CHECK(deserializer.Deserialize());
     CHECK(!deserializer.has_error());
 
     const char* get_class = "foo.class";
@@ -464,9 +464,9 @@ TEST(SFIDeduplicationAfterBytecodeFlushing) {
     v8::HandleScope scope(isolate);
     v8::Local<v8::Context> new_context = CcTest::NewContext();
     v8::Context::Scope context_scope(new_context);
-    WebSnapshotDeserializer deserializer(isolate);
-    CHECK(deserializer.UseWebSnapshot(snapshot_data.buffer,
-                                      snapshot_data.buffer_size));
+    WebSnapshotDeserializer deserializer(isolate, snapshot_data.buffer,
+                                         snapshot_data.buffer_size);
+    CHECK(deserializer.Deserialize());
     CHECK(!deserializer.has_error());
 
     const char* get_outer = "foo.outer";
@@ -549,9 +549,9 @@ TEST(SFIDeduplicationAfterBytecodeFlushingClasses) {
     v8::HandleScope scope(isolate);
     v8::Local<v8::Context> new_context = CcTest::NewContext();
     v8::Context::Scope context_scope(new_context);
-    WebSnapshotDeserializer deserializer(isolate);
-    CHECK(deserializer.UseWebSnapshot(snapshot_data.buffer,
-                                      snapshot_data.buffer_size));
+    WebSnapshotDeserializer deserializer(isolate, snapshot_data.buffer,
+                                         snapshot_data.buffer_size);
+    CHECK(deserializer.Deserialize());
     CHECK(!deserializer.has_error());
 
     const char* get_create = "foo.create";
@@ -626,9 +626,9 @@ TEST(SFIDeduplicationOfFunctionsNotInSnapshot) {
   {
     v8::Local<v8::Context> new_context = CcTest::NewContext();
     v8::Context::Scope context_scope(new_context);
-    WebSnapshotDeserializer deserializer(isolate);
-    CHECK(deserializer.UseWebSnapshot(snapshot_data.buffer,
-                                      snapshot_data.buffer_size));
+    WebSnapshotDeserializer deserializer(isolate, snapshot_data.buffer,
+                                         snapshot_data.buffer_size);
+    CHECK(deserializer.Deserialize());
     CHECK(!deserializer.has_error());
 
     const char* create_new_inner = "foo.outer()";
@@ -738,8 +738,8 @@ TEST(Concatenation) {
     v8::HandleScope scope(isolate);
     v8::Local<v8::Context> new_context = CcTest::NewContext();
     v8::Context::Scope context_scope(new_context);
-    WebSnapshotDeserializer deserializer(isolate);
-    CHECK(deserializer.UseWebSnapshot(buffer.get(), buffer_size));
+    WebSnapshotDeserializer deserializer(isolate, buffer.get(), buffer_size);
+    CHECK(deserializer.Deserialize());
     CHECK(!deserializer.has_error());
     CHECK_EQ(kObjectCount, deserializer.object_count());
 
@@ -785,8 +785,8 @@ TEST(ConcatenationErrors) {
     v8::HandleScope scope(isolate);
     v8::Local<v8::Context> new_context = CcTest::NewContext();
     v8::Context::Scope context_scope(new_context);
-    WebSnapshotDeserializer deserializer(isolate);
-    CHECK(!deserializer.UseWebSnapshot(buffer.get(), buffer_size));
+    WebSnapshotDeserializer deserializer(isolate, buffer.get(), buffer_size);
+    CHECK(!deserializer.Deserialize());
   }
 }
 
@@ -819,9 +819,9 @@ TEST(CompactedSourceCode) {
   {
     v8::Local<v8::Context> new_context = CcTest::NewContext();
     v8::Context::Scope context_scope(new_context);
-    WebSnapshotDeserializer deserializer(isolate);
-    CHECK(deserializer.UseWebSnapshot(snapshot_data.buffer,
-                                      snapshot_data.buffer_size));
+    WebSnapshotDeserializer deserializer(isolate, snapshot_data.buffer,
+                                         snapshot_data.buffer_size);
+    CHECK(deserializer.Deserialize());
     CHECK(!deserializer.has_error());
 
     const char* get_function = "e[0]";