Implement missing features to run Hello world! on simulated ARM.

runtime/vm/intermediate_language_x64.cc

 // Copyright (c) 2013, 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/globals.h"  // Needed here to get TARGET_ARCH_X64.
 #if defined(TARGET_ARCH_X64)
 
 #include "vm/intermediate_language.h"
 
 #include "lib/error.h"
@@ skipping 1970 matching lines @@
   // Instantiate non-null type arguments.
   if (type_arguments().IsUninstantiatedIdentity()) {
     // TODO(regis): The following emitted code is duplicated in
     // VisitExtractConstructorTypeArguments above. The reason is that the code
     // is split between two computations, so that each one produces a
     // single value, rather than producing a pair of values.
     // If this becomes an issue, we should expose these tests at the IL level.
 
     // Check if the instantiator type argument vector is a TypeArguments of a
     // matching length and, if so, use it as the instantiated type_arguments.
-    // No need to check the instantiator (RAX) for null here, because a null
-    // instantiator will have the wrong class (Null instead of TypeArguments).
+    // No need to check the instantiator ('instantiator_reg') for null here,
+    // because a null instantiator will have the wrong class (Null instead of
+    // TypeArguments).
     __ CompareClassId(instantiator_reg, kTypeArgumentsCid);
     __ j(NOT_EQUAL, &done, Assembler::kNearJump);
     const Immediate& arguments_length =
         Immediate(Smi::RawValue(type_arguments().Length()));
     __ cmpq(FieldAddress(instantiator_reg, TypeArguments::length_offset()),
         arguments_length);
     __ j(NOT_EQUAL, &done, Assembler::kNearJump);
     // The instantiator was used in VisitExtractConstructorTypeArguments as the
     // instantiated type arguments, no proper instantiator needed.
     __ movq(instantiator_reg,
@@ skipping 1605 matching lines @@
                          PcDescriptors::kOther,
                          locs());
   __ Drop(2);  // Discard type arguments and receiver.
 }
 
 }  // namespace dart
 
 #undef __
 
 #endif  // defined TARGET_ARCH_X64