Do fewer encoding checks in FlatStringReader used in the JSON stringifier.

src/objects-inl.h

 // Copyright 2012 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.
 //
 // Review notes:
 //
 // - The use of macros in these inline functions may seem superfluous
 // but it is absolutely needed to make sure gcc generates optimal
 // code. gcc is not happy when attempting to inline too deep.
 //
@@ skipping 455 matching lines @@
 bool StringShape::IsExternalTwoByte() {
   return full_representation_tag() == (kExternalStringTag | kTwoByteStringTag);
 }
 
 
 STATIC_ASSERT((kExternalStringTag | kTwoByteStringTag) ==
              Internals::kExternalTwoByteRepresentationTag);
 
 STATIC_ASSERT(v8::String::TWO_BYTE_ENCODING == kTwoByteStringTag);
 
+
 uc32 FlatStringReader::Get(int index) {
-  DCHECK(0 <= index && index <= length_);
   if (is_one_byte_) {
-    return static_cast<const byte*>(start_)[index];
+    return Get<uint8_t>(index);
   } else {
-    return static_cast<const uc16*>(start_)[index];
+    return Get<uc16>(index);
   }
 }
 
+
+template <typename Char>
+Char FlatStringReader::Get(int index) {
+  DCHECK_EQ(is_one_byte_, sizeof(Char) == 1);
+  DCHECK(0 <= index && index <= length_);
+  if (sizeof(Char) == 1) {
+    return static_cast<Char>(static_cast<const uint8_t*>(start_)[index]);
+  } else {
+    return static_cast<Char>(static_cast<const uc16*>(start_)[index]);
+  }
+}
+
 
 Handle<Object> StringTableShape::AsHandle(Isolate* isolate, HashTableKey* key) {
   return key->AsHandle(isolate);
 }
 
 
 Handle<Object> CompilationCacheShape::AsHandle(Isolate* isolate,
                                                HashTableKey* key) {
   return key->AsHandle(isolate);
 }
@@ skipping 6924 matching lines @@
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 #undef NOBARRIER_READ_BYTE_FIELD
 #undef NOBARRIER_WRITE_BYTE_FIELD
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_