Minor optimization to v8::internal::Factory::InternalizeOneByteString.

src/factory.cc

 // Copyright 2014 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/factory.h"
 
 #include "src/accessors.h"
 #include "src/allocation-site-scopes.h"
 #include "src/ast/ast.h"
 #include "src/base/bits.h"
@@ skipping 253 matching lines @@
   return info;
 }
 
 
 // Internalized strings are created in the old generation (data space).
 Handle<String> Factory::InternalizeUtf8String(Vector<const char> string) {
   Utf8StringKey key(string, isolate()->heap()->HashSeed());
   return InternalizeStringWithKey(&key);
 }
 
+namespace {
+
+class OneByteStringKeyExpectingSequential final : public OneByteStringKey {
+  using OneByteStringKey::OneByteStringKey;
+
+  bool IsMatch(Object* string) final {
+    if (V8_LIKELY(StringShape(String::cast(string)).IsSequentialOneByte())) {
+      SeqOneByteString* seq_one_byte = SeqOneByteString::cast(string);
+      return seq_one_byte->length() == string_.length() &&
+             memcmp(seq_one_byte->GetChars(), string_.start(),
+                    string_.length()) == 0;
+    }
+    return OneByteStringKey::IsMatch(string);
+  }
+};
+
+}  // namespace
 
 Handle<String> Factory::InternalizeOneByteString(Vector<const uint8_t> string) {
-  OneByteStringKey key(string, isolate()->heap()->HashSeed());
+  OneByteStringKeyExpectingSequential key(string,
+                                          isolate()->heap()->HashSeed());
   return InternalizeStringWithKey(&key);
 }
 
 
 Handle<String> Factory::InternalizeOneByteString(
     Handle<SeqOneByteString> string, int from, int length) {
   SeqOneByteSubStringKey key(string, from, length);
   return InternalizeStringWithKey(&key);
 }
 
@@ skipping 2598 matching lines @@
     Handle<AccessorInfo> prototype =
         Accessors::FunctionPrototypeInfo(isolate(), rw_attribs);
     Descriptor d = Descriptor::AccessorConstant(
         Handle<Name>(Name::cast(prototype->name())), prototype, rw_attribs);
     map->AppendDescriptor(&d);
   }
 }
 
 }  // namespace internal
 }  // namespace v8