Improve string library performance. String concat and indexOf.

runtime/lib/string.cc

 // Copyright (c) 2011, 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/bootstrap_natives.h"
 
 #include "vm/exceptions.h"
 #include "vm/native_entry.h"
 #include "vm/object.h"
 #include "vm/symbols.h"
@@ skipping 192 matching lines @@
 }
 
 
 DEFINE_NATIVE_ENTRY(String_toUpperCase, 1) {
   const String& receiver = String::CheckedHandle(arguments->NativeArgAt(0));
   ASSERT(!receiver.IsNull());
   return String::ToUpperCase(receiver);
 }
 
 
-DEFINE_NATIVE_ENTRY(Strings_concatAll, 3) {
+DEFINE_NATIVE_ENTRY(String_concatRange, 3) {
   GET_NON_NULL_NATIVE_ARGUMENT(Instance, argument, arguments->NativeArgAt(0));
   GET_NON_NULL_NATIVE_ARGUMENT(Smi, start, arguments->NativeArgAt(1));
   GET_NON_NULL_NATIVE_ARGUMENT(Smi, end, arguments->NativeArgAt(2));
   const intptr_t start_ix = start.Value();
   const intptr_t end_ix = end.Value();
   if (start_ix < 0) {
     Exceptions::ThrowArgumentError(start);
   }
   Array& strings = Array::Handle();
   intptr_t length = -1;
@@ skipping 37 matching lines @@
       ? String::Handle(OneByteString::New(length_value, Heap::kNew))
       : String::Handle(TwoByteString::New(length_value, Heap::kNew));
   NoGCScope no_gc;
 
   uint16_t* data_position = reinterpret_cast<uint16_t*>(codeUnits.DataAddr(0));
   String::Copy(result, 0, data_position, length_value);
   return result.raw();
 }
 
 }  // namespace dart