harmony-scoping: Implement LoadIC handler for loads from global contexts.

src/code-stubs-hydrogen.cc

 // Copyright 2012 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/v8.h"
 
 #include "src/bailout-reason.h"
 #include "src/code-stubs.h"
 #include "src/field-index.h"
 #include "src/hydrogen.h"
@@ skipping 496 matching lines @@
   return feedback_vector;
 }
 
 
 Handle<Code> CreateAllocationSiteStub::GenerateCode() {
   return DoGenerateCode(this);
 }
 
 
 template <>
+HValue* CodeStubGraphBuilder<LoadGlobalContextFieldStub>::BuildCodeStub() {
+  int context_index = casted_stub()->context_index();
+  int slot_index = casted_stub()->slot_index();
+
+  HValue* native_context = BuildGetNativeContext();
+  HValue* global_context_table = Add<HLoadNamedField>(
+      native_context, static_cast<HValue*>(NULL),
+      HObjectAccess::ForContextSlot(Context::GLOBAL_CONTEXT_TABLE_INDEX));
+  HValue* global_context =
+      Add<HLoadNamedField>(global_context_table, static_cast<HValue*>(NULL),
+                           HObjectAccess::ForGlobalContext(context_index));
+  return Add<HLoadNamedField>(global_context, static_cast<HValue*>(NULL),
+                              HObjectAccess::ForContextSlot(slot_index));
+}
+
+
+Handle<Code> LoadGlobalContextFieldStub::GenerateCode() {
+  return DoGenerateCode(this);
+}
+
+
+template <>
 HValue* CodeStubGraphBuilder<LoadFastElementStub>::BuildCodeStub() {
   HInstruction* load = BuildUncheckedMonomorphicElementAccess(
       GetParameter(LoadDescriptor::kReceiverIndex),
       GetParameter(LoadDescriptor::kNameIndex), NULL,
       casted_stub()->is_js_array(), casted_stub()->elements_kind(), LOAD,
       NEVER_RETURN_HOLE, STANDARD_STORE);
   return load;
 }
 
 
@@ skipping 1480 matching lines @@
 
   // Probe the stub cache.
   Code::Flags flags = Code::RemoveTypeAndHolderFromFlags(
       Code::ComputeHandlerFlags(Code::LOAD_IC));
   Add<HTailCallThroughMegamorphicCache>(receiver, name, flags);
 
   // We never continue.
   return graph()->GetConstant0();
 }
 } }  // namespace v8::internal