Add one-char string table for faster String.charAt to the VM.

runtime/vm/object.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/object.h"
 
 #include "include/dart_api.h"
 #include "platform/assert.h"
 #include "vm/assembler.h"
 #include "vm/bigint_operations.h"
@@ skipping 390 matching lines @@
 
   ASSERT(class_class() != null_);
 
   // Pre-allocate the Array and OneByteString class in the vm isolate so that
   // we can create a symbol table and populate it with some frequently used
   // strings as symbols.
   cls = Class::New<Array>();
   isolate->object_store()->set_array_class(cls);
   cls = Class::NewStringClass(kOneByteStringCid);
   isolate->object_store()->set_one_byte_string_class(cls);
+  cls = Class::NewStringClass(kTwoByteStringCid);
+  isolate->object_store()->set_two_byte_string_class(cls);
 
   // Allocate and initialize the empty_array instance.
   {
     uword address = heap->Allocate(Array::InstanceSize(0), Heap::kOld);
     empty_array_ = reinterpret_cast<RawArray*>(address + kHeapObjectTag);
     InitializeObject(address, kArrayCid, Array::InstanceSize(0));
     empty_array_->ptr()->length_ = Smi::New(0);
   }
 }
 
@@ skipping 162 matching lines @@
   cls = Class::New<Type>();
   object_store->set_type_class(cls);
 
   cls = Class::New<TypeParameter>();
   object_store->set_type_parameter_class(cls);
 
   // Pre-allocate the OneByteString class needed by the symbol table.
   cls = Class::NewStringClass(kOneByteStringCid);
   object_store->set_one_byte_string_class(cls);
 
+  // Pre-allocate the TwoByteString class needed by the symbol table.
+  cls = Class::NewStringClass(kTwoByteStringCid);
+  object_store->set_two_byte_string_class(cls);
+
   // Setup the symbol table for the symbols created in the isolate.
   Symbols::SetupSymbolTable(isolate);
 
   // Set up the libraries array before initializing the core library.
   const GrowableObjectArray& libraries =
       GrowableObjectArray::Handle(GrowableObjectArray::New(Heap::kOld));
   object_store->set_libraries(libraries);
 
   // Basic infrastructure has been setup, initialize the class dictionary.
   Library::InitCoreLibrary(isolate);
@@ skipping 40 matching lines @@
   ASSERT(object_store->immutable_array_class() != object_store->array_class());
   name = Symbols::ImmutableArray();
   RegisterPrivateClass(cls, name, core_lib);
   pending_classes.Add(cls, Heap::kOld);
 
   cls = object_store->one_byte_string_class();  // Was allocated above.
   name = Symbols::OneByteString();
   RegisterPrivateClass(cls, name, core_lib);
   pending_classes.Add(cls, Heap::kOld);
 
-  cls = Class::NewStringClass(kTwoByteStringCid);
-  object_store->set_two_byte_string_class(cls);
+  cls = object_store->two_byte_string_class();  // Was allocated above.
   name = Symbols::TwoByteString();
   RegisterPrivateClass(cls, name, core_lib);
   pending_classes.Add(cls, Heap::kOld);
 
   cls = Class::NewStringClass(kExternalOneByteStringCid);
   object_store->set_external_one_byte_string_class(cls);
   name = Symbols::ExternalOneByteString();
   RegisterPrivateClass(cls, name, core_lib);
   pending_classes.Add(cls, Heap::kOld);
 
@@ skipping 11421 matching lines @@
   }
   return result.raw();
 }
 
 
 const char* WeakProperty::ToCString() const {
   return "_WeakProperty";
 }
 
 }  // namespace dart