Use the return value of vm native methods to set the return value,

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 23 matching lines @@
       GrowableArray<const Object*> args;
       Exceptions::ThrowByType(Exceptions::kIllegalArgument, args);
     } else if (value > 0xFFFF) {
       is_one_byte_string = false;
       is_two_byte_string = false;
     } else if (value > 0xFF) {
       is_one_byte_string = false;
     }
     temp[i] = value;
   }
-  String& result = String::Handle(isolate);
   if (is_one_byte_string) {
-    result ^= OneByteString::New(temp, len, Heap::kNew);
+    return OneByteString::New(temp, len, Heap::kNew);
   } else if (is_two_byte_string) {
-    result ^= TwoByteString::New(temp, len, Heap::kNew);
+    return TwoByteString::New(temp, len, Heap::kNew);
   } else {
-    result ^= FourByteString::New(temp, len, Heap::kNew);
+    return FourByteString::New(temp, len, Heap::kNew);
   }
-  arguments->SetReturn(result);
 }
 
 
 DEFINE_NATIVE_ENTRY(StringBase_substringUnchecked, 3) {
   GET_NATIVE_ARGUMENT(String, receiver, arguments->At(0));
   GET_NATIVE_ARGUMENT(Smi, start_obj, arguments->At(1));
   GET_NATIVE_ARGUMENT(Smi, end_obj, arguments->At(2));
 
   intptr_t start = start_obj.Value();
   intptr_t end = end_obj.Value();
-
-  const String& result = String::Handle(
-      isolate, String::SubString(receiver, start, (end - start)));
-  arguments->SetReturn(result);
+  return String::SubString(receiver, start, (end - start));
 }
 
 
 DEFINE_NATIVE_ENTRY(String_hashCode, 1) {
   const String& receiver = String::CheckedHandle(arguments->At(0));
   intptr_t hash_val = receiver.Hash();
   ASSERT(hash_val > 0);
   ASSERT(Smi::IsValid(hash_val));
-  const Smi& hash_smi = Smi::Handle(Smi::New(hash_val));
-  arguments->SetReturn(hash_smi);
+  return Smi::New(hash_val);
 }
 
 
 DEFINE_NATIVE_ENTRY(String_getLength, 1) {
   const String& receiver = String::CheckedHandle(arguments->At(0));
-  arguments->SetReturn(Smi::Handle(Smi::New(receiver.Length())));
+  return Smi::New(receiver.Length());
 }
 
 
 static int32_t StringValueAt(const String& str, const Integer& index) {
   if (index.IsSmi()) {
     Smi& smi = Smi::Handle();
     smi ^= index.raw();
     int32_t index = smi.Value();
     if ((index < 0) || (index >= str.Length())) {
       GrowableArray<const Object*> arguments;
       arguments.Add(&smi);
       Exceptions::ThrowByType(Exceptions::kIndexOutOfRange, arguments);
     }
     return str.CharAt(index);
   } else {
     // An index larger than Smi is always illegal.
     GrowableArray<const Object*> arguments;
     arguments.Add(&index);
     Exceptions::ThrowByType(Exceptions::kIndexOutOfRange, arguments);
     return 0;
   }
 }
 
 
 DEFINE_NATIVE_ENTRY(String_charAt, 2) {
   const String& receiver = String::CheckedHandle(arguments->At(0));
   GET_NATIVE_ARGUMENT(Integer, index, arguments->At(1));
   uint32_t value = StringValueAt(receiver, index);
   ASSERT(value <= 0x10FFFF);
-  arguments->SetReturn(String::Handle(Symbols::New(&value, 1)));
+  return Symbols::New(&value, 1);
 }
 
 DEFINE_NATIVE_ENTRY(String_charCodeAt, 2) {
   const String& receiver = String::CheckedHandle(arguments->At(0));
   GET_NATIVE_ARGUMENT(Integer, index, arguments->At(1));
   int32_t value = StringValueAt(receiver, index);
   ASSERT(value >= 0);
   ASSERT(value <= 0x10FFFF);
-  arguments->SetReturn(Smi::Handle(Smi::New(value)));
+  return Smi::New(value);
 }
 
 
 DEFINE_NATIVE_ENTRY(String_concat, 2) {
   const String& receiver = String::CheckedHandle(arguments->At(0));
   GET_NATIVE_ARGUMENT(String, b, arguments->At(1));
-  const String& result = String::Handle(String::Concat(receiver, b));
-  arguments->SetReturn(result);
+  return String::Concat(receiver, b);
 }
 
 
 DEFINE_NATIVE_ENTRY(String_toLowerCase, 1) {
   const String& receiver = String::CheckedHandle(arguments->At(0));
   ASSERT(!receiver.IsNull());
-  const String& result = String::Handle(String::ToLowerCase(receiver));
-  arguments->SetReturn(result);
+  return String::ToLowerCase(receiver);
 }
 
 
 DEFINE_NATIVE_ENTRY(String_toUpperCase, 1) {
   const String& receiver = String::CheckedHandle(arguments->At(0));
   ASSERT(!receiver.IsNull());
-  const String& result = String::Handle(String::ToUpperCase(receiver));
-  arguments->SetReturn(result);
+  return String::ToUpperCase(receiver);
 }
 
 
 DEFINE_NATIVE_ENTRY(Strings_concatAll, 1) {
   GET_NATIVE_ARGUMENT(Array, strings, arguments->At(0));
   ASSERT(!strings.IsNull());
   // Check that the array contains strings.
   Instance& elem = Instance::Handle();
   for (intptr_t i = 0; i < strings.Length(); i++) {
     elem ^= strings.At(i);
     if (elem.IsNull()) {
       GrowableArray<const Object*> args;
       Exceptions::ThrowByType(Exceptions::kNullPointer, args);
     }
     if (!elem.IsString()) {
       GrowableArray<const Object*> args;
       args.Add(&elem);
       Exceptions::ThrowByType(Exceptions::kIllegalArgument, args);
     }
   }
-  const String& result = String::Handle(String::ConcatAll(strings));
-  arguments->SetReturn(result);
+  return String::ConcatAll(strings);
 }
 
 }  // namespace dart