[Interpreter] Add support for Load / Store to Lookup slots.

src/runtime/runtime-interpreter.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/runtime/runtime-utils.h"
 
 #include "src/arguments.h"
 #include "src/isolate-inl.h"
 
 namespace v8 {
@@ skipping 200 matching lines @@
 
 
 // TODO(rmcilroy): Remove this once the interpreter supports runtime functions
 // which return a pair.
 RUNTIME_FUNCTION(Runtime_InterpreterLoadLookupSlotReceiver) {
   ObjectPair result =
       Runtime_LoadLookupSlot(args.length(), args.arguments(), isolate);
   return result.y;
 }
 
+
+// Declared in runtime.cc.
+// TODO(mythria): Remove this once the interpreter supports projecting out
+// unnecessary outputs.
+ObjectPair Runtime_LoadLookupSlotNoReferenceError(int args_length,
+                                                  Object** args_object,
+                                                  Isolate* isolate);
+
+
+// TODO(mythria): Remove this once the interpreter supports projecting out
+// unnecessary outputs.
+RUNTIME_FUNCTION(Runtime_InterpreterLoadLookupSlotNoReferenceErrorValue) {

[Michael Starzinger, 2015/12/14 21:25:04]

The first projection should actually be usable without any special support.
IIRC, the result register for a runtime function with one result value coincides
with the first result of a runtime with a pair as a result value. So I think
this wrapper is not necessary.

+  ObjectPair result = Runtime_LoadLookupSlotNoReferenceError(
+      args.length(), args.arguments(), isolate);
+  return result.x;

[Michael Starzinger, 2015/12/14 21:25:04]

This won't compile on 32-bit architectures.

+}
+
 }  // namespace internal
 }  // namespace v8