Split up HLoadNamedField and HStoreNamedField.

src/hydrogen.cc

Index: src/hydrogen.cc
diff --git a/src/hydrogen.cc b/src/hydrogen.cc
index 176dd9fa77a04f8c401cef6fd8da191bd736cefa..911ff266e6f096ef5ebe48498fea902c80fc647a 100644
--- a/src/hydrogen.cc
+++ b/src/hydrogen.cc
@@ -5236,6 +5236,11 @@ HInstruction* HOptimizedGraphBuilder::BuildStoreNamedField(
   bool transition_to_field = lookup->IsTransitionToField(*map);
 
   HStoreNamedField *instr;
+  HValue* store_target = checked_object->ActualValue();
+  if (!field_access.IsInobject()) {
+    store_target = Add<HLoadNamedField>(
+        store_target, HObjectAccess::ForBackingStore());
+  }
   if (FLAG_track_double_fields && field_access.representation().IsDouble()) {
     HObjectAccess heap_number_access =
         field_access.WithRepresentation(Representation::Tagged());
@@ -5249,32 +5254,27 @@ HInstruction* HOptimizedGraphBuilder::BuildStoreNamedField(
       AddStoreMapConstant(heap_number, isolate()->factory()->heap_number_map());
       Add<HStoreNamedField>(heap_number, HObjectAccess::ForHeapNumberValue(),
                             value);
-      instr = New<HStoreNamedField>(checked_object->ActualValue(),
-                                    heap_number_access,
-                                    heap_number);
+      instr = New<HStoreNamedField>(
+          store_target, heap_number_access, heap_number);
     } else {
       // Already holds a HeapNumber; load the box and write its value field.
-      HInstruction* heap_number = Add<HLoadNamedField>(checked_object,
-                                                       heap_number_access);
+      HInstruction* heap_number = Add<HLoadNamedField>(
+          store_target, heap_number_access);
       heap_number->set_type(HType::HeapNumber());
-      instr = New<HStoreNamedField>(heap_number,
-                                    HObjectAccess::ForHeapNumberValue(),
-                                    value);
+      instr = New<HStoreNamedField>(
+          heap_number, HObjectAccess::ForHeapNumberValue(), value);
     }
   } else {
     // This is a normal store.
-    instr = New<HStoreNamedField>(checked_object->ActualValue(),
-                                  field_access,
-                                  value);
+    instr = New<HStoreNamedField>(store_target, field_access, value);
   }
 
   if (transition_to_field) {
     Handle<Map> transition(lookup->GetTransitionMapFromMap(*map));
     HConstant* transition_constant = Add<HConstant>(transition);
-    instr->SetTransition(transition_constant, top_info());
-    // TODO(fschneider): Record the new map type of the object in the IR to
-    // enable elimination of redundant checks after the transition store.
-    instr->SetGVNFlag(kChangesMaps);
+    Add<HStoreNamedField>(
+        checked_object, HObjectAccess::ForMap(), transition_constant);
+    instr->SetTransition(transition, top_info());
   }
   return instr;
 }
@@ -6125,6 +6125,9 @@ void HOptimizedGraphBuilder::VisitThrow(Throw* expr) {
 
 HLoadNamedField* HGraphBuilder::BuildLoadNamedField(HValue* object,
                                                     HObjectAccess access) {
+  if (!access.IsInobject()) {
+    object = Add<HLoadNamedField>(object, HObjectAccess::ForBackingStore());
+  }
   if (FLAG_track_double_fields && access.representation().IsDouble()) {
     // load the heap number
     HLoadNamedField* heap_number = Add<HLoadNamedField>(