[wasm] Transferrable modules

src/value-serializer.cc

Index: src/value-serializer.cc
diff --git a/src/value-serializer.cc b/src/value-serializer.cc
index 7b17275b014d5a9f210ad1d63e6fae134bddc840..b9471b84059c2d7d6c9eb903d108d7d98b3320ac 100644
--- a/src/value-serializer.cc
+++ b/src/value-serializer.cc
@@ -126,6 +126,8 @@ enum class SerializationTag : uint8_t {
   //  wasmWireByteLength:uint32_t, then raw data
   //  compiledDataLength:uint32_t, then raw data
   kWasmModule = 'W',
+  // A wasm module object transfer. next value is its index.
+  kWasmModuleTransfer = 'w',
   // The delegate is responsible for processing all following data.
   // This "escapes" to whatever wire format the delegate chooses.
   kHostObject = '\\',
@@ -803,6 +805,18 @@ Maybe<bool> ValueSerializer::WriteJSArrayBufferView(JSArrayBufferView* view) {
 }
 
 Maybe<bool> ValueSerializer::WriteWasmModule(Handle<JSObject> object) {
+  if (delegate_ != nullptr) {
+    Maybe<uint32_t> transfer_id = delegate_->GetWasmModuleTransferId(
+        reinterpret_cast<v8::Isolate*>(isolate_),
+        v8::Local<v8::WasmCompiledModule>::Cast(Utils::ToLocal(object)));
+    uint32_t id = 0;
+    if (transfer_id.To(&id)) {
+      WriteTag(SerializationTag::kWasmModuleTransfer);
+      WriteVarint<uint32_t>(id);
+      return Just(true);
+    }
+  }
+
   Handle<WasmCompiledModule> compiled_part(
       WasmCompiledModule::cast(object->GetInternalField(0)), isolate_);
   WasmEncodingTag encoding_tag = WasmEncodingTag::kRawBytes;
@@ -1054,6 +1068,18 @@ void ValueDeserializer::TransferArrayBuffer(
   }
 }
 
+void ValueDeserializer::TransferWasmModule(uint32_t transfer_id,
+                                           Handle<WasmModuleObject> module) {
+  // We don't realistically expect too many wasm modules to be posted around.
+  // See v8:6106 also.
+  size_t necessary_size = Max(transferred_wasm_modules_.size(),
+                              static_cast<size_t>(transfer_id + 1));
+  if (transferred_wasm_modules_.size() < necessary_size) {
+    transferred_wasm_modules_.resize(necessary_size);
+  }
+  transferred_wasm_modules_[transfer_id] = module;
+}
+
 MaybeHandle<Object> ValueDeserializer::ReadObject() {
   MaybeHandle<Object> result = ReadObjectInternal();
 
@@ -1150,6 +1176,8 @@ MaybeHandle<Object> ValueDeserializer::ReadObjectInternal() {
     }
     case SerializationTag::kWasmModule:
       return ReadWasmModule();
+    case SerializationTag::kWasmModuleTransfer:
+      return ReadWasmModuleTransfer();
     case SerializationTag::kHostObject:
       return ReadHostObject();
     default:
@@ -1595,8 +1623,27 @@ MaybeHandle<JSArrayBufferView> ValueDeserializer::ReadJSArrayBufferView(
   return typed_array;
 }
 
+MaybeHandle<JSObject> ValueDeserializer::ReadWasmModuleTransfer() {
+  if (FLAG_wasm_disable_structured_cloning || allow_inline_wasm()) {
+    return MaybeHandle<JSObject>();
+  }
+
+  uint32_t index = 0;
+  if (ReadVarint<uint32_t>().To(&index) &&
+      index < transferred_wasm_modules_.size()) {
+    Handle<JSObject> module = transferred_wasm_modules_[index];
+    uint32_t id = next_id_++;
+    AddObjectWithID(id, module);
+    return module;
+  } else {
+    return MaybeHandle<JSObject>();
+  }
+}
+
 MaybeHandle<JSObject> ValueDeserializer::ReadWasmModule() {
-  if (FLAG_wasm_disable_structured_cloning) return MaybeHandle<JSObject>();
+  if (FLAG_wasm_disable_structured_cloning || !allow_inline_wasm()) {
+    return MaybeHandle<JSObject>();
+  }
 
   Vector<const uint8_t> encoding_tag;
   if (!ReadRawBytes(sizeof(WasmEncodingTag)).To(&encoding_tag) ||
@@ -1625,21 +1672,22 @@ MaybeHandle<JSObject> ValueDeserializer::ReadWasmModule() {
   // Try to deserialize the compiled module first.
   ScriptData script_data(compiled_bytes.start(), compiled_bytes.length());
   Handle<FixedArray> compiled_part;
+  MaybeHandle<JSObject> result;
   if (WasmCompiledModuleSerializer::DeserializeWasmModule(
           isolate_, &script_data, wire_bytes)
           .ToHandle(&compiled_part)) {
-    return WasmModuleObject::New(
+    result = WasmModuleObject::New(
         isolate_, Handle<WasmCompiledModule>::cast(compiled_part));
-  }
-
-  // If that fails, recompile.
-  MaybeHandle<JSObject> result;
-  {
+  } else {
     wasm::ErrorThrower thrower(isolate_, "ValueDeserializer::ReadWasmModule");
     result = wasm::SyncCompile(isolate_, &thrower,
                                wasm::ModuleWireBytes(wire_bytes));
   }
   RETURN_EXCEPTION_IF_SCHEDULED_EXCEPTION(isolate_, JSObject);
+  uint32_t id = next_id_++;
+  if (!result.is_null()) {
+    AddObjectWithID(id, result.ToHandleChecked());
+  }
   return result;
 }