Introduce HObjectAccess, which is used by LoadNamedField and StoreNamedField to denote what parts

src/hydrogen.cc

 // Copyright 2012 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 1177 matching lines @@
 
   environment()->Push(elements);
   capacity_checker.End();
 
   if (is_js_array) {
     HValue* new_length = AddInstruction(
         HAdd::New(zone, context, length, graph_->GetConstant1()));
     new_length->AssumeRepresentation(Representation::Integer32());
     new_length->ClearFlag(HValue::kCanOverflow);
 
-    Factory* factory = isolate()->factory();
     Representation representation = IsFastElementsKind(kind)
         ? Representation::Smi() : Representation::Tagged();
-    HInstruction* length_store = AddInstruction(new(zone) HStoreNamedField(
-        object,
-        factory->length_field_string(),
-        new_length, true,
-        representation,
-        JSArray::kLengthOffset));
-    length_store->SetGVNFlag(kChangesArrayLengths);
+    AddStore(object, HObjectAccess::ForArrayLength(), new_length,
+        representation);
   }
 
   length_checker.Else();
 
   AddBoundsCheck(key, length, ALLOW_SMI_KEY);
   environment()->Push(elements);
 
   length_checker.End();
 
   return environment()->Pop();
@@ skipping 61 matching lines @@
   HValue* elements = AddLoadElements(object, mapcheck);
   if (is_store && (fast_elements || fast_smi_only_elements) &&
       store_mode != STORE_NO_TRANSITION_HANDLE_COW) {
     HCheckMaps* check_cow_map = HCheckMaps::New(
         elements, isolate()->factory()->fixed_array_map(), zone);
     check_cow_map->ClearGVNFlag(kDependsOnElementsKind);
     AddInstruction(check_cow_map);
   }
   HInstruction* length = NULL;
   if (is_js_array) {
-    length = AddInstruction(
-        HLoadNamedField::NewArrayLength(zone, object, mapcheck, HType::Smi()));
+    length = AddLoad(object, HObjectAccess::ForArrayLength(), mapcheck,
+        Representation::Smi());
+    length->set_type(HType::Smi());
   } else {
     length = AddInstruction(new(zone) HFixedArrayBaseLength(elements));
   }
   HValue* checked_key = NULL;
   if (IsExternalArrayElementsKind(elements_kind)) {
     if (store_mode == STORE_NO_TRANSITION_IGNORE_OUT_OF_BOUNDS) {
       NoObservableSideEffectsScope no_effects(this);
       HLoadExternalArrayPointer* external_elements =
           new(zone) HLoadExternalArrayPointer(elements);
       AddInstruction(external_elements);
@@ skipping 105 matching lines @@
   HValue* elements =
       AddInstruction(new(zone) HAllocate(context, total_size,
                                          HType::JSArray(), flags));
   return elements;
 }
 
 
 void HGraphBuilder::BuildInitializeElements(HValue* elements,
                                             ElementsKind kind,
                                             HValue* capacity) {
-  Zone* zone = this->zone();
   Factory* factory = isolate()->factory();
   Handle<Map> map = IsFastDoubleElementsKind(kind)
       ? factory->fixed_double_array_map()
       : factory->fixed_array_map();
-  BuildStoreMap(elements, map);
 
-  Handle<String> fixed_array_length_field_name = factory->length_field_string();
+  AddStoreMapConstant(elements, map);
   Representation representation = IsFastElementsKind(kind)
       ? Representation::Smi() : Representation::Tagged();
-  HInstruction* store_length =
-      new(zone) HStoreNamedField(elements, fixed_array_length_field_name,
-                                 capacity, true, representation,
-                                 FixedArray::kLengthOffset);
-  AddInstruction(store_length);
+  AddStore(elements, HObjectAccess::ForFixedArrayLength(), capacity,
+      representation);
 }
 
 
 HValue* HGraphBuilder::BuildAllocateAndInitializeElements(HValue* context,
                                                           ElementsKind kind,
                                                           HValue* capacity) {
   HValue* new_elements = BuildAllocateElements(context, kind, capacity);
   BuildInitializeElements(new_elements, kind, capacity);
   return new_elements;
 }
 
 
 HInnerAllocatedObject* HGraphBuilder::BuildJSArrayHeader(HValue* array,
     HValue* array_map,
     AllocationSiteMode mode,
     HValue* allocation_site_payload,
     HValue* length_field) {
 
-  BuildStoreMap(array, array_map);
+  AddStore(array, HObjectAccess::ForMap(), array_map);
 
   HConstant* empty_fixed_array =
       new(zone()) HConstant(
           Handle<FixedArray>(isolate()->heap()->empty_fixed_array()),
           Representation::Tagged());
   AddInstruction(empty_fixed_array);
 
-  AddInstruction(new(zone()) HStoreNamedField(array,
-      isolate()->factory()->properties_field_symbol(),
-      empty_fixed_array,
-      true,
-      Representation::Tagged(),
-      JSArray::kPropertiesOffset));
-
-  HInstruction* length_store = AddInstruction(
-      new(zone()) HStoreNamedField(array,
-                                   isolate()->factory()->length_field_string(),
-                                   length_field,
-                                   true,
-                                   Representation::Tagged(),
-                                   JSArray::kLengthOffset));
-  length_store->SetGVNFlag(kChangesArrayLengths);
+  HObjectAccess access = HObjectAccess::ForPropertiesPointer();
+  AddStore(array, access, empty_fixed_array);
+  AddStore(array, HObjectAccess::ForArrayLength(), length_field);
 
   if (mode == TRACK_ALLOCATION_SITE) {
     BuildCreateAllocationSiteInfo(array,
                                   JSArray::kSize,
                                   allocation_site_payload);
   }
 
   int elements_location = JSArray::kSize;
   if (mode == TRACK_ALLOCATION_SITE) {
     elements_location += AllocationSiteInfo::kSize;
   }
 
   HInnerAllocatedObject* elements = new(zone()) HInnerAllocatedObject(
-      array,
-      elements_location);
+      array, elements_location);
   AddInstruction(elements);
 
-  HInstruction* elements_store = AddInstruction(
-      new(zone()) HStoreNamedField(
-          array,
-          isolate()->factory()->elements_field_string(),
-          elements,
-          true,
-          Representation::Tagged(),
-          JSArray::kElementsOffset));
-  elements_store->SetGVNFlag(kChangesElementsPointer);
-
+  AddStore(array, HObjectAccess::ForElementsPointer(), elements);
   return elements;
 }
 
 
-HInstruction* HGraphBuilder::BuildStoreMap(HValue* object,
-                                           HValue* map) {
-  Zone* zone = this->zone();
-  Factory* factory = isolate()->factory();
-  Handle<String> map_field_name = factory->map_field_string();
-  HInstruction* store_map =
-      new(zone) HStoreNamedField(object, map_field_name, map,
-                                 true, Representation::Tagged(),
-                                 JSObject::kMapOffset);
-  store_map->ClearGVNFlag(kChangesInobjectFields);
-  store_map->SetGVNFlag(kChangesMaps);
-  AddInstruction(store_map);
-  return store_map;
+HLoadNamedField* HGraphBuilder::AddLoadElements(HValue* object,
+                                                HValue* typecheck) {
+  return AddLoad(object, HObjectAccess::ForElementsPointer(), typecheck);
 }
 
 
-HInstruction* HGraphBuilder::BuildStoreMap(HValue* object,
-                                           Handle<Map> map) {
-  Zone* zone = this->zone();
-  HValue* map_constant =
-      AddInstruction(new(zone) HConstant(map, Representation::Tagged()));
-  return BuildStoreMap(object, map_constant);
-}
-
-
-HLoadNamedField* HGraphBuilder::AddLoadElements(HValue* object,
-    HValue* typecheck) {
-  HLoadNamedField* instr = new(zone()) HLoadNamedField(object, true,
-      Representation::Tagged(), JSObject::kElementsOffset, typecheck);
-  AddInstruction(instr);
-  instr->SetGVNFlag(kDependsOnElementsPointer);
-  instr->ClearGVNFlag(kDependsOnMaps);
-  instr->ClearGVNFlag(kDependsOnInobjectFields);
-  return instr;
-}
-
-
 HValue* HGraphBuilder::BuildNewElementsCapacity(HValue* context,
                                                 HValue* old_capacity) {
   Zone* zone = this->zone();
   HValue* half_old_capacity =
       AddInstruction(HShr::New(zone, context, old_capacity,
                                graph_->GetConstant1()));
   half_old_capacity->AssumeRepresentation(Representation::Integer32());
   half_old_capacity->ClearFlag(HValue::kCanOverflow);
 
   HValue* new_capacity = AddInstruction(
@@ skipping 29 matching lines @@
                  HBoundsCheck(length, max_size_constant,
                               DONT_ALLOW_SMI_KEY, Representation::Integer32()));
 }
 
 
 HValue* HGraphBuilder::BuildGrowElementsCapacity(HValue* object,
                                                  HValue* elements,
                                                  ElementsKind kind,
                                                  HValue* length,
                                                  HValue* new_capacity) {
-  Zone* zone = this->zone();
   HValue* context = environment()->LookupContext();
 
   BuildNewSpaceArrayCheck(new_capacity, kind);
 
   HValue* new_elements =
       BuildAllocateAndInitializeElements(context, kind, new_capacity);
 
   BuildCopyElements(context, elements, kind,
                     new_elements, kind,
                     length, new_capacity);
 
-  Factory* factory = isolate()->factory();
-  HInstruction* elements_store = AddInstruction(new(zone) HStoreNamedField(
-      object,
-      factory->elements_field_string(),
-      new_elements, true, Representation::Tagged(),
-      JSArray::kElementsOffset));
-  elements_store->SetGVNFlag(kChangesElementsPointer);
+  AddStore(object, HObjectAccess::ForElementsPointer(), new_elements);
 
   return new_elements;
 }
 
 
 void HGraphBuilder::BuildFillElementsWithHole(HValue* context,
                                               HValue* elements,
                                               ElementsKind elements_kind,
                                               HValue* from,
                                               HValue* to) {
@@ skipping 84 matching lines @@
   }
 }
 
 
 HValue* HGraphBuilder::BuildCloneShallowArray(HContext* context,
                                               HValue* boilerplate,
                                               AllocationSiteMode mode,
                                               ElementsKind kind,
                                               int length) {
   Zone* zone = this->zone();
-  Factory* factory = isolate()->factory();
 
   NoObservableSideEffectsScope no_effects(this);
 
   // All sizes here are multiples of kPointerSize.
   int size = JSArray::kSize;
   if (mode == TRACK_ALLOCATION_SITE) {
     size += AllocationSiteInfo::kSize;
   }
   int elems_offset = size;
   if (length > 0) {
     size += IsFastDoubleElementsKind(kind)
         ? FixedDoubleArray::SizeFor(length)
         : FixedArray::SizeFor(length);
   }
 
   HAllocate::Flags allocate_flags = HAllocate::DefaultFlags(kind);
   // Allocate both the JS array and the elements array in one big
   // allocation. This avoids multiple limit checks.
   HValue* size_in_bytes =
       AddInstruction(new(zone) HConstant(size, Representation::Integer32()));
   HInstruction* object =
       AddInstruction(new(zone) HAllocate(context,
                                          size_in_bytes,
                                          HType::JSObject(),
                                          allocate_flags));
 
   // Copy the JS array part.
   for (int i = 0; i < JSArray::kSize; i += kPointerSize) {
     if ((i != JSArray::kElementsOffset) || (length == 0)) {
-      HInstruction* value = AddInstruction(new(zone) HLoadNamedField(
-          boilerplate, true, Representation::Tagged(), i));
-      if (i != JSArray::kMapOffset) {
-        AddInstruction(new(zone) HStoreNamedField(object,
-                                                  factory->empty_string(),
-                                                  value, true,
-                                                  Representation::Tagged(), i));
-      } else {
-        BuildStoreMap(object, value);
-      }
+      HObjectAccess access = HObjectAccess::ForJSArrayOffset(i);
+      AddStore(object, access, AddLoad(boilerplate, access));
     }
   }
 
   // Create an allocation site info if requested.
   if (mode == TRACK_ALLOCATION_SITE) {
     BuildCreateAllocationSiteInfo(object, JSArray::kSize, boilerplate);
   }
 
   if (length > 0) {
     // Get hold of the elements array of the boilerplate and setup the
     // elements pointer in the resulting object.
     HValue* boilerplate_elements = AddLoadElements(boilerplate);
     HValue* object_elements =
         AddInstruction(new(zone) HInnerAllocatedObject(object, elems_offset));
-    AddInstruction(new(zone) HStoreNamedField(object,
-                                              factory->elements_field_string(),
-                                              object_elements, true,
-                                              Representation::Tagged(),
-                                              JSObject::kElementsOffset));
+    AddStore(object, HObjectAccess::ForElementsPointer(), object_elements);
 
     // Copy the elements array header.
     for (int i = 0; i < FixedArrayBase::kHeaderSize; i += kPointerSize) {
-      HInstruction* value =
-          AddInstruction(new(zone) HLoadNamedField(
-              boilerplate_elements, true, Representation::Tagged(), i));
-      AddInstruction(new(zone) HStoreNamedField(object_elements,
-                                                factory->empty_string(),
-                                                value, true,
-                                                Representation::Tagged(), i));
+      HObjectAccess access = HObjectAccess::ForFixedArrayHeader(i);
+      AddStore(object_elements, access, AddLoad(boilerplate_elements, access));
     }
 
     // Copy the elements array contents.
     // TODO(mstarzinger): Teach HGraphBuilder::BuildCopyElements to unfold
     // copying loops with constant length up to a given boundary and use this
     // helper here instead.
     for (int i = 0; i < length; i++) {
       HValue* key_constant =
           AddInstruction(new(zone) HConstant(i, Representation::Integer32()));
       HInstruction* value =
@@ skipping 59 matching lines @@
 }
 
 
 HValue* HGraphBuilder::BuildCreateAllocationSiteInfo(HValue* previous_object,
                                                      int previous_object_size,
                                                      HValue* payload) {
   HInnerAllocatedObject* alloc_site = new(zone())
         HInnerAllocatedObject(previous_object, previous_object_size);
   AddInstruction(alloc_site);
   Handle<Map> alloc_site_map(isolate()->heap()->allocation_site_info_map());
-  BuildStoreMap(alloc_site, alloc_site_map);
-  AddInstruction(new(zone()) HStoreNamedField(alloc_site,
-      isolate()->factory()->payload_string(),
-      payload,
-      true,
-      Representation::Tagged(),
-      AllocationSiteInfo::kPayloadOffset));
+  AddStoreMapConstant(alloc_site, alloc_site_map);
+  HObjectAccess access = HObjectAccess::ForAllocationSitePayload();
+  AddStore(alloc_site, access, payload);
   return alloc_site;
 }
 
 
 HInstruction* HGraphBuilder::BuildGetNativeContext(HValue* context) {
+  // Get the global context, then the native context
   HInstruction* global_object = AddInstruction(new(zone())
-                                               HGlobalObject(context));
-  HInstruction* native_context = AddInstruction(new(zone())
-      HLoadNamedField(global_object, true, Representation::Tagged(),
-                      GlobalObject::kNativeContextOffset));
-  return native_context;
+      HGlobalObject(context));
+  HObjectAccess access = HObjectAccess::ForJSObjectOffset(
+      GlobalObject::kNativeContextOffset);
+  return AddLoad(global_object, access);
 }
 
 
 HInstruction* HGraphBuilder::BuildGetArrayFunction(HValue* context) {
   HInstruction* native_context = BuildGetNativeContext(context);
-  int offset = Context::kHeaderSize +
-      kPointerSize * Context::ARRAY_FUNCTION_INDEX;
-  HInstruction* array_function = AddInstruction(new(zone())
-      HLoadNamedField(native_context, true, Representation::Tagged(), offset));
-  return array_function;
+  HInstruction* index = AddInstruction(new(zone())
+      HConstant(Context::ARRAY_FUNCTION_INDEX, Representation::Integer32()));
+
+  return AddInstruction(new (zone())
+      HLoadKeyed(native_context, index, NULL, FAST_ELEMENTS));
 }
 
 
 HGraphBuilder::JSArrayBuilder::JSArrayBuilder(HGraphBuilder* builder,
                                               ElementsKind kind,
                                               HValue* allocation_site_payload,
                                               AllocationSiteMode mode) :
         builder_(builder),
         kind_(kind),
         allocation_site_payload_(allocation_site_payload) {
   if (mode == DONT_TRACK_ALLOCATION_SITE) {
     mode_ = mode;
   } else {
     mode_ = AllocationSiteInfo::GetMode(kind);
   }
 }
 
 
 HValue* HGraphBuilder::JSArrayBuilder::EmitMapCode(HValue* context) {
   HInstruction* native_context = builder()->BuildGetNativeContext(context);
-  int offset = Context::kHeaderSize +
-      kPointerSize * Context::JS_ARRAY_MAPS_INDEX;
-  HInstruction* map_array = AddInstruction(new(zone())
-      HLoadNamedField(native_context, true, Representation::Tagged(), offset));
-  offset = kind_ * kPointerSize + FixedArrayBase::kHeaderSize;
-  return AddInstruction(new(zone()) HLoadNamedField(
-      map_array, true, Representation::Tagged(), offset));
+
+  HInstruction* index = builder()->AddInstruction(new(zone())
+      HConstant(Context::JS_ARRAY_MAPS_INDEX, Representation::Integer32()));
+
+  HInstruction* map_array = builder()->AddInstruction(new(zone())
+      HLoadKeyed(native_context, index, NULL, FAST_ELEMENTS));
+
+  HInstruction* kind_index = builder()->AddInstruction(new(zone())
+      HConstant(kind_, Representation::Integer32()));
+
+  return builder()->AddInstruction(new(zone())
+      HLoadKeyed(map_array, kind_index, NULL, FAST_ELEMENTS));
 }
 
 
 HValue* HGraphBuilder::JSArrayBuilder::EstablishAllocationSize(
     HValue* length_node) {
   HValue* context = builder()->environment()->LookupContext();
   ASSERT(length_node != NULL);
 
   int base_size = JSArray::kSize;
   if (mode_ == TRACK_ALLOCATION_SITE) {
@@ skipping 88 matching lines @@
 
   if (fill_with_hole) {
     builder()->BuildFillElementsWithHole(context, elements_location_, kind_,
                                          graph()->GetConstant0(), capacity);
   }
 
   return new_object;
 }
 
 
+HStoreNamedField* HGraphBuilder::AddStore(HValue *object,
+                                          HObjectAccess access,
+                                          HValue *val,
+                                          Representation representation) {
+  HStoreNamedField *instr = new(zone())
+      HStoreNamedField(object, access, val, representation);
+  AddInstruction(instr);
+  return instr;
+}
+
+
+HLoadNamedField* HGraphBuilder::AddLoad(HValue *object,
+                                        HObjectAccess access,
+                                        HValue *typecheck,
+                                        Representation representation) {
+  HLoadNamedField *instr =
+      new(zone()) HLoadNamedField(object, access, typecheck, representation);
+  AddInstruction(instr);
+  return instr;
+}
+
+
+HStoreNamedField* HGraphBuilder::AddStoreMapConstant(HValue *object,
+                                                     Handle<Map> map) {
+  HValue* constant =
+      AddInstruction(new(zone()) HConstant(map, Representation::Tagged()));
+  HStoreNamedField *instr =
+      new(zone()) HStoreNamedField(object, HObjectAccess::ForMap(), constant);
+  AddInstruction(instr);
+  return instr;
+}
+
+
 HOptimizedGraphBuilder::HOptimizedGraphBuilder(CompilationInfo* info,
                                                TypeFeedbackOracle* oracle)
     : HGraphBuilder(info),
       function_state_(NULL),
       initial_function_state_(this, info, oracle, NORMAL_RETURN),
       ast_context_(NULL),
       break_scope_(NULL),
       inlined_count_(0),
       globals_(10, info->zone()),
       inline_bailout_(false) {
@@ skipping 4346 matching lines @@
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
   return Bailout("DebuggerStatement");
 }
 
 
 static Handle<SharedFunctionInfo> SearchSharedFunctionInfo(
     Code* unoptimized_code, FunctionLiteral* expr) {
   int start_position = expr->start_position();
   RelocIterator it(unoptimized_code);
-  for (;!it.done(); it.next()) {
+  for (; !it.done(); it.next()) {
     RelocInfo* rinfo = it.rinfo();
     if (rinfo->rmode() != RelocInfo::EMBEDDED_OBJECT) continue;
     Object* obj = rinfo->target_object();
     if (obj->IsSharedFunctionInfo()) {
       SharedFunctionInfo* shared = SharedFunctionInfo::cast(obj);
       if (shared->start_position() == start_position) {
         return Handle<SharedFunctionInfo>(shared);
       }
     }
   }
@@ skipping 655 matching lines @@
   if (!is_store) return false;
 
   // 2nd chance: A store into a non-existent field can still be inlined if we
   // have a matching transition and some room left in the object.
   type->LookupTransition(NULL, *name, lookup);
   return lookup->IsTransitionToField(*type) &&
       (type->unused_property_fields() > 0);
 }
 
 
-static int ComputeLoadStoreFieldIndex(Handle<Map> type,
-                                      LookupResult* lookup) {
-  ASSERT(lookup->IsField() || lookup->IsTransitionToField(*type));
-  if (lookup->IsField()) {
-    return lookup->GetLocalFieldIndexFromMap(*type);
-  } else {
-    Map* transition = lookup->GetTransitionMapFromMap(*type);
-    int descriptor = transition->LastAdded();
-    int index = transition->instance_descriptors()->GetFieldIndex(descriptor);
-    return index - type->inobject_properties();
-  }
-}
-
-
 static Representation ComputeLoadStoreRepresentation(Handle<Map> type,
                                                      LookupResult* lookup) {
   if (lookup->IsField()) {
     return lookup->representation();
   } else {
     Map* transition = lookup->GetTransitionMapFromMap(*type);
     int descriptor = transition->LastAdded();
     PropertyDetails details =
         transition->instance_descriptors()->GetDetails(descriptor);
     return details.representation();
@@ skipping 44 matching lines @@
       }
       ASSERT(proto->GetPrototype(isolate())->IsNull());
     }
     ASSERT(proto->IsJSObject());
     AddInstruction(new(zone()) HCheckPrototypeMaps(
         Handle<JSObject>(JSObject::cast(map->prototype())),
         Handle<JSObject>(JSObject::cast(proto)),
         zone()));
   }
 
-  int index = ComputeLoadStoreFieldIndex(map, lookup);
-  bool is_in_object = index < 0;
+  HObjectAccess field_access = HObjectAccess::ForField(map, lookup, name);
   Representation representation = ComputeLoadStoreRepresentation(map, lookup);
-  int offset = index * kPointerSize;
-  if (index < 0) {
-    // Negative property indices are in-object properties, indexed
-    // from the end of the fixed part of the object.
-    offset += map->instance_size();
-  } else {
-    offset += FixedArray::kHeaderSize;
-  }
   bool transition_to_field = lookup->IsTransitionToField(*map);
+
+  HStoreNamedField *instr;
   if (FLAG_track_double_fields && representation.IsDouble()) {
     if (transition_to_field) {
+      // The store requires a mutable HeapNumber to be allocated.
       NoObservableSideEffectsScope no_side_effects(this);
       HInstruction* heap_number_size = AddInstruction(new(zone()) HConstant(
           HeapNumber::kSize, Representation::Integer32()));
       HInstruction* double_box = AddInstruction(new(zone()) HAllocate(
           environment()->LookupContext(), heap_number_size,
           HType::HeapNumber(), HAllocate::CAN_ALLOCATE_IN_NEW_SPACE));
-      BuildStoreMap(double_box, isolate()->factory()->heap_number_map());
-      AddInstruction(new(zone()) HStoreNamedField(
-          double_box, name, value, true,
-          Representation::Double(), HeapNumber::kValueOffset));
-      value = double_box;
-      representation = Representation::Tagged();
+      AddStoreMapConstant(double_box, isolate()->factory()->heap_number_map());
+      AddStore(double_box, HObjectAccess::ForHeapNumberValue(),
+          value, Representation::Double());
+      instr = new(zone()) HStoreNamedField(object, field_access, double_box);
     } else {
-      HInstruction* double_box = AddInstruction(new(zone()) HLoadNamedField(
-          object, is_in_object, Representation::Tagged(), offset));
+      // Already holds a HeapNumber; load the box and write its value field.
+      HInstruction* double_box = AddLoad(object, field_access);
       double_box->set_type(HType::HeapNumber());
-      return new(zone()) HStoreNamedField(
-          double_box, name, value, true,
-          Representation::Double(), HeapNumber::kValueOffset);
+      instr = new(zone()) HStoreNamedField(double_box,
+          HObjectAccess::ForHeapNumberValue(), value, Representation::Double());
     }
+  } else {
+    // This is a non-double store.
+    instr = new(zone()) HStoreNamedField(
+        object, field_access, value, representation);
   }
-  HStoreNamedField* instr = new(zone()) HStoreNamedField(
-      object, name, value, is_in_object, representation, offset);
+
   if (transition_to_field) {
     Handle<Map> transition(lookup->GetTransitionMapFromMap(*map));
     instr->set_transition(transition);
     // 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);
   }
   return instr;
 }
 
@@ skipping 49 matching lines @@
     Handle<String> name) {
   if (!name->Equals(isolate()->heap()->length_string())) return false;
 
   for (int i = 0; i < types->length(); i++) {
     if (types->at(i)->instance_type() != JS_ARRAY_TYPE) return false;
   }
 
   BuildCheckNonSmi(object);
 
   HInstruction* typecheck =
-    AddInstruction(HCheckMaps::New(object, types, zone()));
-  HInstruction* instr =
-    HLoadNamedField::NewArrayLength(zone(), object, typecheck);
+      AddInstruction(HCheckMaps::New(object, types, zone()));
+  HInstruction* instr = new(zone())
+      HLoadNamedField(object, HObjectAccess::ForArrayLength(), typecheck);
+
   instr->set_position(expr->position());
   ast_context()->ReturnInstruction(instr, expr->id());
   return true;
 }
 
 
 void HOptimizedGraphBuilder::HandlePolymorphicLoadNamedField(Property* expr,
     HValue* object,
     SmallMapList* types,
     Handle<String> name) {
 
   if (HandlePolymorphicArrayLengthLoad(expr, object, types, name))
     return;
 
   BuildCheckNonSmi(object);
 
   // Use monomorphic load if property lookup results in the same field index
   // for all maps. Requires special map check on the set of all handled maps.
   HInstruction* instr = NULL;
-  if (types->length() > 0 && types->length() <= kMaxLoadPolymorphism) {
-    LookupResult lookup(isolate());
-    int previous_field_offset = 0;
-    bool previous_field_is_in_object = false;
-    Representation representation = Representation::None();
-    int count;
-    for (count = 0; count < types->length(); ++count) {
-      Handle<Map> map = types->at(count);
-      if (!ComputeLoadStoreField(map, name, &lookup, false)) break;
+  LookupResult lookup(isolate());
+  int count;
+  Representation representation = Representation::None();
+  HObjectAccess access = HObjectAccess::ForMap();  // initial value unused.
+  for (count = 0;
+       count < types->length() && count < kMaxLoadPolymorphism;
+       ++count) {
+    Handle<Map> map = types->at(count);
+    if (!ComputeLoadStoreField(map, name, &lookup, false)) break;
 
-      int index = ComputeLoadStoreFieldIndex(map, &lookup);
-      Representation new_representation =
-          ComputeLoadStoreRepresentation(map, &lookup);
-      bool is_in_object = index < 0;
-      int offset = index * kPointerSize;
+    HObjectAccess new_access = HObjectAccess::ForField(map, &lookup, name);
+    Representation new_representation =
+        ComputeLoadStoreRepresentation(map, &lookup);
 
-      if (index < 0) {
-        // Negative property indices are in-object properties, indexed
-        // from the end of the fixed part of the object.
-        offset += map->instance_size();
-      } else {
-        offset += FixedArray::kHeaderSize;
-      }
-
-      if (count == 0) {
-        previous_field_offset = offset;
-        previous_field_is_in_object = is_in_object;
-        representation = new_representation;
-      } else if (offset != previous_field_offset ||
-                 is_in_object != previous_field_is_in_object ||
-                 (FLAG_track_fields &&
-                  !representation.IsCompatibleForLoad(new_representation))) {
-        break;
-      }
-
-      representation = representation.generalize(new_representation);
-    }
-
-    if (count == types->length()) {
-      AddInstruction(HCheckMaps::New(object, types, zone()));
-      instr = DoBuildLoadNamedField(
-          object, previous_field_is_in_object,
-          representation, previous_field_offset);
+    if (count == 0) {
+      // First time through the loop; set access and representation.
+      access = new_access;
+      representation = new_representation;
+    } else if (!representation.IsCompatibleForLoad(new_representation)) {
+      // Representations did not match.
+      break;
+    } else if (access.offset() != new_access.offset()) {
+      // Offsets did not match.
+      break;
+    } else if (access.IsInobject() != new_access.IsInobject()) {
+      // In-objectness did not match.
+      break;
     }
   }
 
-  if (instr == NULL) {
+  if (count == types->length()) {
+    // Everything matched; can use monomorphic load.
+    AddInstruction(HCheckMaps::New(object, types, zone()));
+    instr = BuildLoadNamedField(object, access, representation);
+  } else {
+    // Something did not match; must use a polymorphic load.
     HValue* context = environment()->LookupContext();
     instr = new(zone()) HLoadNamedFieldPolymorphic(
         context, object, types, name, zone());
   }
 
   instr->set_position(expr->position());
   return ast_context()->ReturnInstruction(instr, expr->id());
 }
 
 
@@ skipping 536 matching lines @@
   HValue* value = environment()->Pop();
   HThrow* instr = new(zone()) HThrow(context, value);
   instr->set_position(expr->position());
   AddInstruction(instr);
   AddSimulate(expr->id());
   current_block()->FinishExit(new(zone()) HAbnormalExit);
   set_current_block(NULL);
 }
 
 
-HLoadNamedField* HOptimizedGraphBuilder::BuildLoadNamedField(
+HLoadNamedField* HGraphBuilder::BuildLoadNamedField(
     HValue* object,
-    Handle<Map> map,
-    LookupResult* lookup) {
-  int index = lookup->GetLocalFieldIndexFromMap(*map);
-  // Negative property indices are in-object properties, indexed from the end of
-  // the fixed part of the object. Non-negative property indices are in the
-  // properties array.
-  int inobject = index < 0;
-  Representation representation = lookup->representation();
-  int offset = inobject
-      ? index * kPointerSize + map->instance_size()
-      : index * kPointerSize + FixedArray::kHeaderSize;
-  return DoBuildLoadNamedField(object, inobject, representation, offset);
-}
-
-
-HLoadNamedField* HGraphBuilder::DoBuildLoadNamedField(
-    HValue* object,
-    bool inobject,
-    Representation representation,
-    int offset) {
+    HObjectAccess access,
+    Representation representation) {
   bool load_double = false;
   if (representation.IsDouble()) {
     representation = Representation::Tagged();
     load_double = FLAG_track_double_fields;
   }
   HLoadNamedField* field =
-      new(zone()) HLoadNamedField(object, inobject, representation, offset);
+      new(zone()) HLoadNamedField(object, access, NULL, representation);
   if (load_double) {
     AddInstruction(field);
     field->set_type(HType::HeapNumber());
-    return new(zone()) HLoadNamedField(
-        field, true, Representation::Double(), HeapNumber::kValueOffset);
+    return new(zone()) HLoadNamedField(field,
+        HObjectAccess::ForHeapNumberValue(), NULL, Representation::Double());
   }
   return field;
 }
 
 
 HInstruction* HOptimizedGraphBuilder::BuildLoadNamedGeneric(
     HValue* object,
     Handle<String> name,
     Property* expr) {
   if (expr->IsUninitialized()) {
@@ skipping 20 matching lines @@
     Handle<String> name,
     Property* expr,
     Handle<Map> map) {
   // Handle a load from a known field.
   ASSERT(!map->is_dictionary_map());
 
   // Handle access to various length properties
   if (name->Equals(isolate()->heap()->length_string())) {
     if (map->instance_type() == JS_ARRAY_TYPE) {
       AddCheckMapsWithTransitions(object, map);
-      return HLoadNamedField::NewArrayLength(zone(), object, object);
+      return new(zone()) HLoadNamedField(object,
+          HObjectAccess::ForArrayLength());
     }
   }
 
   LookupResult lookup(isolate());
   map->LookupDescriptor(NULL, *name, &lookup);
   if (lookup.IsField()) {
     AddCheckMap(object, map);
-    return BuildLoadNamedField(object, map, &lookup);
+    return BuildLoadNamedField(object,
+        HObjectAccess::ForField(map, &lookup, name),
+        ComputeLoadStoreRepresentation(map, &lookup));
   }
 
   // Handle a load of a constant known function.
   if (lookup.IsConstantFunction()) {
     AddCheckMap(object, map);
     Handle<JSFunction> function(lookup.GetConstantFunctionFromMap(*map));
     return new(zone()) HConstant(function, Representation::Tagged());
   }
 
   // Handle a load from a known field somewhere in the prototype chain.
   LookupInPrototypes(map, name, &lookup);
   if (lookup.IsField()) {
     Handle<JSObject> prototype(JSObject::cast(map->prototype()));
     Handle<JSObject> holder(lookup.holder());
     Handle<Map> holder_map(holder->map());
     AddCheckMap(object, map);
     AddInstruction(
         new(zone()) HCheckPrototypeMaps(prototype, holder, zone()));
-    HValue* holder_value = AddInstruction(
-            new(zone()) HConstant(holder, Representation::Tagged()));
-    return BuildLoadNamedField(holder_value, holder_map, &lookup);
+    HValue* holder_value = AddInstruction(new(zone())
+        HConstant(holder, Representation::Tagged()));
+    return BuildLoadNamedField(holder_value,
+        HObjectAccess::ForField(holder_map, &lookup, name),
+        ComputeLoadStoreRepresentation(map, &lookup));
   }
 
   // Handle a load of a constant function somewhere in the prototype chain.
   if (lookup.IsConstantFunction()) {
     Handle<JSObject> prototype(JSObject::cast(map->prototype()));
     Handle<JSObject> holder(lookup.holder());
     Handle<Map> holder_map(holder->map());
     AddCheckMap(object, map);
     AddInstruction(new(zone()) HCheckPrototypeMaps(prototype, holder, zone()));
     Handle<JSFunction> function(lookup.GetConstantFunctionFromMap(*holder_map));
@@ skipping 255 matching lines @@
         //     it's a keyed property) and registered in the full codegen.
         HBasicBlock* if_jsarray = graph()->CreateBasicBlock();
         HBasicBlock* if_fastobject = graph()->CreateBasicBlock();
         HHasInstanceTypeAndBranch* typecheck =
             new(zone()) HHasInstanceTypeAndBranch(object, JS_ARRAY_TYPE);
         typecheck->SetSuccessorAt(0, if_jsarray);
         typecheck->SetSuccessorAt(1, if_fastobject);
         current_block()->Finish(typecheck);
 
         set_current_block(if_jsarray);
-        HInstruction* length;
-        length = AddInstruction(
-            HLoadNamedField::NewArrayLength(zone(), object, typecheck,
-                                            HType::Smi()));
+        HInstruction* length = AddLoad(object, HObjectAccess::ForArrayLength(),
+            typecheck, Representation::Smi());
+        length->set_type(HType::Smi());
+
         checked_key = AddBoundsCheck(key, length, ALLOW_SMI_KEY);
         access = AddInstruction(BuildFastElementAccess(
             elements, checked_key, val, elements_kind_branch,
             elements_kind, is_store, NEVER_RETURN_HOLE, STANDARD_STORE));
         if (!is_store) {
           Push(access);
         }
 
         *has_side_effects |= access->HasObservableSideEffects();
         // The caller will use has_side_effects and add correct Simulate.
@@ skipping 2622 matching lines @@
 }
 
 
 void HOptimizedGraphBuilder::BuildEmitDeepCopy(
     Handle<JSObject> boilerplate_object,
     Handle<JSObject> original_boilerplate_object,
     HInstruction* target,
     int* offset,
     AllocationSiteMode mode) {
   Zone* zone = this->zone();
-  Factory* factory = isolate()->factory();
 
   HInstruction* original_boilerplate = AddInstruction(new(zone) HConstant(
       original_boilerplate_object, Representation::Tagged()));
 
   bool create_allocation_site_info = mode == TRACK_ALLOCATION_SITE &&
       boilerplate_object->map()->CanTrackAllocationSite();
 
   // Only elements backing stores for non-COW arrays need to be copied.
   Handle<FixedArrayBase> elements(boilerplate_object->elements());
   Handle<FixedArrayBase> original_elements(
@@ skipping 28 matching lines @@
 
   for (int i = 0; i < limit; i++) {
     PropertyDetails details = descriptors->GetDetails(i);
     if (details.type() != FIELD) continue;
     int index = descriptors->GetFieldIndex(i);
     int property_offset = boilerplate_object->GetInObjectPropertyOffset(index);
     Handle<Name> name(descriptors->GetKey(i));
     Handle<Object> value =
         Handle<Object>(boilerplate_object->InObjectPropertyAt(index),
         isolate());
+
+    // The access for the store depends on the type of the boilerplate.
+    HObjectAccess access = boilerplate_object->IsJSArray() ?
+        HObjectAccess::ForJSArrayOffset(property_offset) :
+        HObjectAccess::ForJSObjectOffset(property_offset);
+
     if (value->IsJSObject()) {
       Handle<JSObject> value_object = Handle<JSObject>::cast(value);
       Handle<JSObject> original_value_object = Handle<JSObject>::cast(
           Handle<Object>(original_boilerplate_object->InObjectPropertyAt(index),
               isolate()));
       HInstruction* value_instruction =
           AddInstruction(new(zone) HInnerAllocatedObject(target, *offset));
-      AddInstruction(new(zone) HStoreNamedField(
-          object_properties, name, value_instruction, true,
-          Representation::Tagged(), property_offset));
+
+      AddStore(object_properties, access, value_instruction);
+
       BuildEmitDeepCopy(value_object, original_value_object, target,
-                        offset, DONT_TRACK_ALLOCATION_SITE);
+          offset, DONT_TRACK_ALLOCATION_SITE);
     } else {
       Representation representation = details.representation();
       HInstruction* value_instruction = AddInstruction(new(zone) HConstant(
           value, Representation::Tagged()));
+
       if (representation.IsDouble()) {
+        // Allocate a HeapNumber box and store the value into it.
         HInstruction* double_box =
             AddInstruction(new(zone) HInnerAllocatedObject(target, *offset));
-        BuildStoreMap(double_box, factory->heap_number_map());
-        AddInstruction(new(zone) HStoreNamedField(
-            double_box, name, value_instruction, true,
-            Representation::Double(), HeapNumber::kValueOffset));
+        AddStoreMapConstant(double_box,
+            isolate()->factory()->heap_number_map());
+        AddStore(double_box, HObjectAccess::ForHeapNumberValue(),
+            value_instruction, Representation::Double());
         value_instruction = double_box;
         *offset += HeapNumber::kSize;
       }
-      AddInstruction(new(zone) HStoreNamedField(
-          object_properties, name, value_instruction, true,
-          Representation::Tagged(), property_offset));
+
+      AddStore(object_properties, access, value_instruction);
     }
   }
 
   // Build Allocation Site Info if desired
   if (create_allocation_site_info) {
     BuildCreateAllocationSiteInfo(target, JSArray::kSize, original_boilerplate);
   }
 
   if (object_elements != NULL) {
     HInstruction* boilerplate_elements = AddInstruction(new(zone) HConstant(
@@ skipping 51 matching lines @@
 
 
 HValue* HOptimizedGraphBuilder::BuildCopyObjectHeader(
     Handle<JSObject> boilerplate_object,
     HInstruction* target,
     int object_offset,
     int elements_offset,
     int elements_size) {
   ASSERT(boilerplate_object->properties()->length() == 0);
   Zone* zone = this->zone();
-  Factory* factory = isolate()->factory();
   HValue* result = NULL;
 
   HValue* object_header =
       AddInstruction(new(zone) HInnerAllocatedObject(target, object_offset));
   Handle<Map> boilerplate_object_map(boilerplate_object->map());
-  BuildStoreMap(object_header, boilerplate_object_map);
+  AddStoreMapConstant(object_header, boilerplate_object_map);
 
   HInstruction* elements;
   if (elements_size == 0) {
     Handle<Object> elements_field =
         Handle<Object>(boilerplate_object->elements(), isolate());
     elements = AddInstruction(new(zone) HConstant(
         elements_field, Representation::Tagged()));
   } else {
     elements = AddInstruction(new(zone) HInnerAllocatedObject(
         target, elements_offset));
     result = elements;
   }
-  HInstruction* elements_store = AddInstruction(new(zone) HStoreNamedField(
-      object_header,
-      factory->elements_field_string(),
-      elements,
-      true, Representation::Tagged(), JSObject::kElementsOffset));
-  elements_store->SetGVNFlag(kChangesElementsPointer);
+  AddStore(object_header, HObjectAccess::ForElementsPointer(), elements);
 
   Handle<Object> properties_field =
       Handle<Object>(boilerplate_object->properties(), isolate());
   ASSERT(*properties_field == isolate()->heap()->empty_fixed_array());
   HInstruction* properties = AddInstruction(new(zone) HConstant(
       properties_field, Representation::None()));
-  AddInstruction(new(zone) HStoreNamedField(object_header,
-                                            factory->empty_string(),
-                                            properties, true,
-                                            Representation::Tagged(),
-                                            JSObject::kPropertiesOffset));
+  HObjectAccess access = HObjectAccess::ForPropertiesPointer();
+  AddStore(object_header, access, properties);
 
   if (boilerplate_object->IsJSArray()) {
     Handle<JSArray> boilerplate_array =
         Handle<JSArray>::cast(boilerplate_object);
     Handle<Object> length_field =
         Handle<Object>(boilerplate_array->length(), isolate());
     HInstruction* length = AddInstruction(new(zone) HConstant(
         length_field, Representation::None()));
+
     ASSERT(boilerplate_array->length()->IsSmi());
     Representation representation =
         IsFastElementsKind(boilerplate_array->GetElementsKind())
         ? Representation::Smi() : Representation::Tagged();
-    HInstruction* length_store = AddInstruction(new(zone) HStoreNamedField(
-        object_header,
-        factory->length_field_string(),
-        length,
-        true, representation, JSArray::kLengthOffset));
-    length_store->SetGVNFlag(kChangesArrayLengths);
+    AddStore(object_header, HObjectAccess::ForArrayLength(),
+        length, representation);
   }
 
   return result;
 }
 
 
 void HOptimizedGraphBuilder::VisitThisFunction(ThisFunction* expr) {
   ASSERT(!HasStackOverflow());
   ASSERT(current_block() != NULL);
   ASSERT(current_block()->HasPredecessor());
@@ skipping 366 matching lines @@
       new(zone()) HHasInstanceTypeAndBranch(object, JS_VALUE_TYPE);
   HBasicBlock* if_js_value = graph()->CreateBasicBlock();
   HBasicBlock* not_js_value = graph()->CreateBasicBlock();
   typecheck->SetSuccessorAt(0, if_js_value);
   typecheck->SetSuccessorAt(1, not_js_value);
   current_block()->Finish(typecheck);
   not_js_value->Goto(join);
 
   // Create in-object property store to kValueOffset.
   set_current_block(if_js_value);
-  Handle<String> name = isolate()->factory()->undefined_string();
-  AddInstruction(new(zone()) HStoreNamedField(object,
-                                              name,
-                                              value,
-                                              true,  // in-object store.
-                                              Representation::Tagged(),
-                                              JSValue::kValueOffset));
+  AddStore(object,
+      HObjectAccess::ForJSObjectOffset(JSValue::kValueOffset), value);
   if_js_value->Goto(join);
   join->SetJoinId(call->id());
   set_current_block(join);
   return ast_context()->ReturnValue(value);
 }
 
 
 // Fast support for charCodeAt(n).
 void HOptimizedGraphBuilder::GenerateStringCharCodeAt(CallRuntime* call) {
   ASSERT(call->arguments()->length() == 2);
@@ skipping 954 matching lines @@
     }
   }
 
 #ifdef DEBUG
   if (graph_ != NULL) graph_->Verify(false);  // No full verify.
   if (allocator_ != NULL) allocator_->Verify();
 #endif
 }
 
 } }  // namespace v8::internal