Improve ValueSerializer perf regression after 96635558

src/value-serializer.cc

 // Copyright 2016 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.
 
 #include "src/value-serializer.h"
 
 #include <type_traits>
 
 #include "src/base/logging.h"
 #include "src/conversions.h"
@@ skipping 214 matching lines @@
 void ValueSerializer::WriteRawBytes(const void* source, size_t length) {
   uint8_t* dest;
   if (ReserveRawBytes(length).To(&dest)) {
     memcpy(dest, source, length);
   }
 }
 
 Maybe<uint8_t*> ValueSerializer::ReserveRawBytes(size_t bytes) {
   size_t old_size = buffer_size_;
   size_t new_size = old_size + bytes;
-  if (new_size > buffer_capacity_) {
+  if (V8_UNLIKELY(new_size > buffer_capacity_)) {
     bool ok;
     if (!ExpandBuffer(new_size).To(&ok)) {
       return Nothing<uint8_t*>();
     }
   }
   buffer_size_ = new_size;
   return Just(&buffer_[old_size]);
 }
 
 Maybe<bool> ValueSerializer::ExpandBuffer(size_t required_capacity) {
@@ skipping 1688 matching lines @@
   if (stack.size() != 1) {
     isolate_->Throw(*isolate_->factory()->NewError(
         MessageTemplate::kDataCloneDeserializationError));
     return MaybeHandle<Object>();
   }
   return scope.CloseAndEscape(stack[0]);
 }
 
 }  // namespace internal
 }  // namespace v8