[web snapshot] Implement WriteByte

Bug: v8:11525
Change-Id: I227f0bb852e56551ec0333db52061842664c47c9
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3706963
Commit-Queue: 王澳 <wangao.james@bytedance.com>
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81259}

src/objects/value-serializer.cc

@@ -384,6 +384,13 @@ Maybe<bool> ValueSerializer::ExpandBuffer(size_t required_capacity) {
   }
 }
 
+void ValueSerializer::WriteByte(uint8_t value) {
+  uint8_t* dest;
+  if (ReserveRawBytes(sizeof(uint8_t)).To(&dest)) {
+    *dest = value;
+  }
+}
+
 void ValueSerializer::WriteUint32(uint32_t value) {
   WriteVarint<uint32_t>(value);
 }
@@ -1337,6 +1344,13 @@ Maybe<base::Vector<const uint8_t>> ValueDeserializer::ReadRawBytes(
   return Just(base::Vector<const uint8_t>(start, size));
 }
 
+bool ValueDeserializer::ReadByte(uint8_t* value) {
+  if (static_cast<size_t>(end_ - position_) < sizeof(uint8_t)) return false;
+  *value = *position_;
+  position_++;
+  return true;
+}
+
 bool ValueDeserializer::ReadUint32(uint32_t* value) {
   return ReadVarint<uint32_t>().To(value);
 }

src/objects/value-serializer.h

@@ -84,6 +84,7 @@ class ValueSerializer {
   void WriteUint64(uint64_t value);
   void WriteRawBytes(const void* source, size_t length);
   void WriteDouble(double value);
+  void WriteByte(uint8_t value);
 
   /*
    * Indicate whether to treat ArrayBufferView objects as host objects,
@@ -239,6 +240,7 @@ class ValueDeserializer {
   bool ReadUint64(uint64_t* value) V8_WARN_UNUSED_RESULT;
   bool ReadDouble(double* value) V8_WARN_UNUSED_RESULT;
   bool ReadRawBytes(size_t length, const void** data) V8_WARN_UNUSED_RESULT;
+  bool ReadByte(uint8_t* value) V8_WARN_UNUSED_RESULT;
 
  private:
   friend class WebSnapshotDeserializer;

src/web-snapshot/web-snapshot.h

@@ -96,19 +96,19 @@ class WebSnapshotSerializerDeserializer {
 
   enum PropertyAttributesType : uint8_t { DEFAULT, CUSTOM };
 
-  uint32_t FunctionKindToFunctionFlags(FunctionKind kind);
-  FunctionKind FunctionFlagsToFunctionKind(uint32_t flags);
-  bool IsFunctionOrMethod(uint32_t flags);
-  bool IsConstructor(uint32_t flags);
+  uint8_t FunctionKindToFunctionFlags(FunctionKind kind);
+  FunctionKind FunctionFlagsToFunctionKind(uint8_t flags);
+  bool IsFunctionOrMethod(uint8_t flags);
+  bool IsConstructor(uint8_t flags);
 
-  uint32_t GetDefaultAttributeFlags();
-  uint32_t AttributesToFlags(PropertyDetails details);
-  PropertyAttributes FlagsToAttributes(uint32_t flags);
+  uint8_t GetDefaultAttributeFlags();
+  uint8_t AttributesToFlags(PropertyDetails details);
+  PropertyAttributes FlagsToAttributes(uint8_t flags);
 
-  uint32_t ArrayBufferViewKindToFlags(
+  uint8_t ArrayBufferViewKindToFlags(
       Handle<JSArrayBufferView> array_buffer_view);
 
-  uint32_t ArrayBufferKindToFlags(Handle<JSArrayBuffer> array_buffer);
+  uint8_t ArrayBufferKindToFlags(Handle<JSArrayBuffer> array_buffer);
 
   // The maximum count of items for each value type (strings, objects etc.)
   static constexpr uint32_t kMaxItemCount =
@@ -135,7 +135,7 @@ class WebSnapshotSerializerDeserializer {
 
   // Encode JSArrayBufferFlags, including was_detached, is_shared, is_resizable.
   // DetachedBitField indicates whether the ArrayBuffer was detached.
-  using DetachedBitField = base::BitField<bool, 0, 1>;
+  using DetachedBitField = base::BitField<bool, 0, 1, uint8_t>;
   // SharedBitField indicates whether the ArrayBuffer is SharedArrayBuffer.
   using SharedBitField = DetachedBitField::Next<bool, 1>;
   // ResizableBitField indicates whether the ArrayBuffer is ResizableArrayBuffer
@@ -147,7 +147,7 @@ class WebSnapshotSerializerDeserializer {
   // LengthTrackingBitField indicates whether the ArrayBufferView should track
   // the length of the backing buffer, that is whether the ArrayBufferView is
   // constructed without the specified length argument.
-  using LengthTrackingBitField = base::BitField<bool, 0, 1>;
+  using LengthTrackingBitField = base::BitField<bool, 0, 1, uint8_t>;
 
  private:
   WebSnapshotSerializerDeserializer(const WebSnapshotSerializerDeserializer&) =
@@ -155,9 +155,7 @@ class WebSnapshotSerializerDeserializer {
   WebSnapshotSerializerDeserializer& operator=(
       const WebSnapshotSerializerDeserializer&) = delete;
 
-  // Keep most common function kinds in the 7 least significant bits to make the
-  // flags fit in 1 byte.
-  using AsyncFunctionBitField = base::BitField<bool, 0, 1>;
+  using AsyncFunctionBitField = base::BitField<bool, 0, 1, uint8_t>;
   using GeneratorFunctionBitField = AsyncFunctionBitField::Next<bool, 1>;
   using ArrowFunctionBitField = GeneratorFunctionBitField::Next<bool, 1>;
   using MethodBitField = ArrowFunctionBitField::Next<bool, 1>;
@@ -166,7 +164,7 @@ class WebSnapshotSerializerDeserializer {
   using DefaultConstructorBitField = ClassConstructorBitField::Next<bool, 1>;
   using DerivedConstructorBitField = DefaultConstructorBitField::Next<bool, 1>;
 
-  using ReadOnlyBitField = base::BitField<bool, 0, 1>;
+  using ReadOnlyBitField = base::BitField<bool, 0, 1, uint8_t>;
   using ConfigurableBitField = ReadOnlyBitField::Next<bool, 1>;
   using EnumerableBitField = ConfigurableBitField::Next<bool, 1>;
 };
@@ -464,7 +462,7 @@ class V8_EXPORT WebSnapshotDeserializer
                                     bool has_inlined_local_names);
   Handle<JSFunction> CreateJSFunction(int index, uint32_t start,
                                       uint32_t length, uint32_t parameter_count,
-                                      uint32_t flags, uint32_t context_id);
+                                      uint8_t flags, uint32_t context_id);
   void DeserializeFunctionData(uint32_t count, uint32_t current_count);
   void DeserializeFunctions();
   void DeserializeClasses();