Use weak cell in LoadGlobal handler.

src/ic/x64/handler-compiler-x64.cc

 // Copyright 2014 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"
 
 #if V8_TARGET_ARCH_X64
 
 #include "src/ic/call-optimization.h"
 #include "src/ic/handler-compiler.h"
@@ skipping 694 matching lines @@
 Handle<Code> NamedLoadHandlerCompiler::CompileLoadGlobal(
     Handle<PropertyCell> cell, Handle<Name> name, bool is_configurable) {
   Label miss;
   if (IC::ICUseVector(kind())) {
     PushVectorAndSlot();
   }
   FrontendHeader(receiver(), name, &miss);
 
   // Get the value from the cell.
   Register result = StoreDescriptor::ValueRegister();
-  __ Move(result, cell);
+  Handle<WeakCell> weak_cell = factory()->NewWeakCell(cell);
+  __ LoadWeakValue(result, weak_cell, &miss);
   __ movp(result, FieldOperand(result, PropertyCell::kValueOffset));
 
   // Check for deleted property if property can actually be deleted.
   if (is_configurable) {
     __ CompareRoot(result, Heap::kTheHoleValueRootIndex);
     __ j(equal, &miss);
   } else if (FLAG_debug_code) {
     __ CompareRoot(result, Heap::kTheHoleValueRootIndex);
     __ Check(not_equal, kDontDeleteCellsCannotContainTheHole);
   }
@@ skipping 10 matching lines @@
   // Return the generated code.
   return GetCode(kind(), Code::NORMAL, name);
 }
 
 
 #undef __
 }
 }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64