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

src/hydrogen.h

 // 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.
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@@ skipping 1004 matching lines @@
       HValue* object,
       HValue* key,
       HValue* val,
       HCheckMaps* mapcheck,
       bool is_js_array,
       ElementsKind elements_kind,
       bool is_store,
       KeyedAccessStoreMode store_mode,
       Representation checked_index_representation = Representation::None());
 
-  HInstruction* BuildStoreMap(HValue* object, HValue* map);
-  HInstruction* BuildStoreMap(HValue* object, Handle<Map> map);
+  HLoadNamedField * AddLoad(HValue *object, HObjectAccess* access,
+      HValue *typecheck = NULL);
+  HStoreNamedField* AddStore(HValue *object, HObjectAccess* access,
+      HValue *val, Representation representation = Representation::Tagged());
+  HStoreNamedField* AddStoreMapConstant(HValue *object, Handle<Map>);
+
+  HObjectAccess* AccessArrayHeader(int offset);
+  HObjectAccess* AccessArrayLength();
+  HObjectAccess* AccessElements();
+  HObjectAccess* AccessFixedArrayLength();
+  HObjectAccess* AccessMap();
+  HObjectAccess* AccessField(Handle<Map> map, Handle<String> name,
+     LookupResult* lookup);
+  HObjectAccess* AccessInobject(Handle<String> name, int offset);

[danno, 2013/05/02 14:16:47]

Why not have this as a constructor for HObjectAccess so it can be allocated on
the stack? Prevents having to allocate lots of temporary objects that don't have
to live very long anyway. 

[titzer, 2013/05/03 09:18:41]

Because the HObjectAccess pointers are actually being stored in the load/store
instructions and thus live longer than the graph builder's stack.

 
   class IfBuilder {
    public:
     explicit IfBuilder(HGraphBuilder* builder,
                        int position = RelocInfo::kNoPosition);
     IfBuilder(HGraphBuilder* builder,
               HIfContinuation* continuation);
 
     ~IfBuilder() {
       if (!finished_) End();
@@ skipping 966 matching lines @@
   EmbeddedVector<char, 64> filename_;
   HeapStringAllocator string_allocator_;
   StringStream trace_;
   int indent_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_HYDROGEN_H_