Revert 21720: "Introduce FieldIndex to unify and abstract property/field offset"

src/code-stubs.h

Index: src/code-stubs.h
diff --git a/src/code-stubs.h b/src/code-stubs.h
index 55d8b885c842326f219eb816289bb42e3f36c965..4a93f9920ad7409b70448c216a789864264a6ada 100644
--- a/src/code-stubs.h
+++ b/src/code-stubs.h
@@ -897,9 +897,11 @@ class HandlerStub: public HICStub {
 
 class LoadFieldStub: public HandlerStub {
  public:
-  LoadFieldStub(Isolate* isolate, FieldIndex index)
-    : HandlerStub(isolate), index_(index) {
-    Initialize(Code::LOAD_IC);
+  LoadFieldStub(Isolate* isolate,
+                bool inobject,
+                int index, Representation representation)
+      : HandlerStub(isolate) {
+    Initialize(Code::LOAD_IC, inobject, index, representation);
   }
 
   virtual Handle<Code> GenerateCode() V8_OVERRIDE;
@@ -916,30 +918,42 @@ class LoadFieldStub: public HandlerStub {
     return KindBits::decode(bit_field_);
   }
 
-  FieldIndex index() const { return index_; }
+  bool is_inobject() {
+    return InobjectBits::decode(bit_field_);
+  }
+
+  int offset() {
+    int index = IndexBits::decode(bit_field_);
+    int offset = index * kPointerSize;
+    if (is_inobject()) return offset;
+    return FixedArray::kHeaderSize + offset;
+  }
 
   bool unboxed_double() {
-    return index_.is_double();
+    return UnboxedDoubleBits::decode(bit_field_);
   }
 
   virtual Code::StubType GetStubType() { return Code::FAST; }
 
  protected:
-  explicit LoadFieldStub(Isolate* isolate);
+  explicit LoadFieldStub(Isolate* isolate) : HandlerStub(isolate) { }
 
-  void Initialize(Code::Kind kind) {
-    int property_index_key = index_.GetLoadFieldStubKey();
-    // Save a copy of the essence of the property index into the bit field to
-    // make sure that hashing of unique stubs works correctly..
-    bit_field_ = KindBits::encode(kind) |
-        EncodedLoadFieldByIndexBits::encode(property_index_key);
+  void Initialize(Code::Kind kind,
+                  bool inobject,
+                  int index,
+                  Representation representation) {
+    bit_field_ = KindBits::encode(kind)
+        | InobjectBits::encode(inobject)
+        | IndexBits::encode(index)
+        | UnboxedDoubleBits::encode(representation.IsDouble());
   }
 
  private:
   STATIC_ASSERT(KindBits::kSize == 4);
-  class EncodedLoadFieldByIndexBits: public BitField<int, 4, 13> {};
+  class InobjectBits: public BitField<bool, 4, 1> {};
+  class IndexBits: public BitField<int, 5, 11> {};
+  class UnboxedDoubleBits: public BitField<bool, 16, 1> {};
   virtual CodeStub::Major MajorKey() { return LoadField; }
-  FieldIndex index_;
 };
 
 
@@ -1084,9 +1098,11 @@ class CallApiGetterStub : public PlatformCodeStub {
 
 class KeyedLoadFieldStub: public LoadFieldStub {
  public:
-  KeyedLoadFieldStub(Isolate* isolate, FieldIndex index)
-      : LoadFieldStub(isolate, index) {
-    Initialize(Code::KEYED_LOAD_IC);
+  KeyedLoadFieldStub(Isolate* isolate,
+                     bool inobject,
+                     int index, Representation representation)
+      : LoadFieldStub(isolate) {
+    Initialize(Code::KEYED_LOAD_IC, inobject, index, representation);
   }
 
   virtual void InitializeInterfaceDescriptor(