Replace HeapNumber as doublebox with an explicit MutableHeapNumber.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index c292a176792f410f4461121aaa3be77dacb14923..11643dee7bed582222c260756eae8ba5c2a9c10b 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -5372,7 +5372,8 @@ HInstruction* HOptimizedGraphBuilder::BuildStoreNamedField(
           HType::HeapNumber(),
           pretenure_flag,
           HEAP_NUMBER_TYPE);

[Igor Sheludko, 2014/03/27 11:30:16]

MUTABLE_HEAP_NUMBER_TYPE?

-      AddStoreMapConstant(heap_number, isolate()->factory()->heap_number_map());
+      AddStoreMapConstant(
+          heap_number, isolate()->factory()->mutable_heap_number_map());
       Add<HStoreNamedField>(heap_number, HObjectAccess::ForHeapNumberValue(),
                             value);
       instr = New<HStoreNamedField>(checked_object->ActualValue(),
@@ -9911,9 +9912,12 @@ void HOptimizedGraphBuilder::BuildEmitInObjectProperties(
             Add<HAllocate>(heap_number_constant, HType::HeapNumber(),

[Igor Sheludko, 2014/03/27 11:30:16]

Don't we need a HType::MutableHeapNumber() thing?

                 pretenure_flag, HEAP_NUMBER_TYPE);

[Igor Sheludko, 2014/03/27 11:30:16]

MUTABLE_HEAP_NUMBER_TYPE?

         AddStoreMapConstant(double_box,
-            isolate()->factory()->heap_number_map());
-        Add<HStoreNamedField>(double_box, HObjectAccess::ForHeapNumberValue(),
-                              Add<HConstant>(value));
+            isolate()->factory()->mutable_heap_number_map());
+        // Unwrap the mutable heap number from the boilerplate.
+        HValue* double_value =
+            Add<HConstant>(Handle<HeapNumber>::cast(value)->value());

[Igor Sheludko, 2014/03/27 11:30:16]

value->Number()

+        Add<HStoreNamedField>(
+            double_box, HObjectAccess::ForHeapNumberValue(), double_value);
         value_instruction = double_box;
       } else if (representation.IsSmi()) {
         value_instruction = value->IsUninitialized()