Replace the use CharacterStreams in Heap::AllocateSymbolInternal and String::ComputeHash

src/heap-inl.h

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 83 matching lines @@
     return AllocateStringFromOneByte(str, pretenure);
   }
   // Non-ASCII and we need to decode.
   return AllocateStringFromUtf8Slow(str, non_ascii_start, pretenure);
 }
 
 
 MaybeObject* Heap::AllocateSymbol(Vector<const char> str,
                                   int chars,
                                   uint32_t hash_field) {
-  unibrow::Utf8InputBuffer<> buffer(str.start(),
-                                    static_cast<unsigned>(str.length()));
-  return AllocateInternalSymbol(&buffer, chars, hash_field);
+  // Must be ascii.
+  if (chars == str.length()) return AllocateAsciiSymbol(str, hash_field);

[Yang, 2012/12/17 14:30:34]

Maybe we could encapsulate this logic by replacing the if-condition with
something like AllocateInternalSymbolHelper::IsOneByte(str, chars) and make sure
this gets inlined.

+  return AllocateInternalSymbol(str, chars, hash_field);
 }
 
 
 MaybeObject* Heap::AllocateAsciiSymbol(Vector<const char> str,
                                        uint32_t hash_field) {
   if (str.length() > SeqOneByteString::kMaxLength) {
     return Failure::OutOfMemoryException();
   }
   // Compute map and object size.
   Map* map = ascii_symbol_map();
@@ skipping 700 matching lines @@
 AssertNoAllocation::~AssertNoAllocation() { }
 DisableAssertNoAllocation::DisableAssertNoAllocation() { }
 DisableAssertNoAllocation::~DisableAssertNoAllocation() { }
 
 #endif
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HEAP_INL_H_