Track heap objects.

src/property-details.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.
 //     * 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 65 matching lines @@
 };
 
 
 class Representation {
  public:
   enum Kind {
     kNone,
     kSmi,
     kInteger32,
     kDouble,
+    kHeapObject,
     kTagged,
     kExternal,
     kNumRepresentations
   };
 
   Representation() : kind_(kNone) { }
 
   static Representation None() { return Representation(kNone); }
   static Representation Tagged() { return Representation(kTagged); }
   static Representation Smi() { return Representation(kSmi); }
   static Representation Integer32() { return Representation(kInteger32); }
   static Representation Double() { return Representation(kDouble); }
+  static Representation HeapObject() { return Representation(kHeapObject); }
   static Representation External() { return Representation(kExternal); }
 
   static Representation FromKind(Kind kind) { return Representation(kind); }
 
   bool Equals(const Representation& other) const {
     return kind_ == other.kind_;
   }
 
   bool IsCompatibleForLoad(const Representation& other) const {
     return (IsDouble() && other.IsDouble()) ||
         (!IsDouble() && !other.IsDouble());
   }
 
   bool is_more_general_than(const Representation& other) const {
     ASSERT(kind_ != kExternal);
     ASSERT(other.kind_ != kExternal);
+    if (IsHeapObject()) return other.IsDouble();
     return kind_ > other.kind_;
   }
 
   bool fits_into(const Representation& other) const {
     return other.is_more_general_than(*this) || other.Equals(*this);
   }
 
   Representation generalize(Representation other) {
-    if (is_more_general_than(other)) {
-      return *this;
-    } else {
-      return other;
-    }
+    if (other.fits_into(*this)) return *this;
+    if (other.is_more_general_than(*this)) return other;
+    return Representation::Tagged();
   }
 
   Kind kind() const { return static_cast<Kind>(kind_); }
   bool IsNone() const { return kind_ == kNone; }
   bool IsTagged() const { return kind_ == kTagged; }
   bool IsSmi() const { return kind_ == kSmi; }
   bool IsInteger32() const { return kind_ == kInteger32; }
   bool IsDouble() const { return kind_ == kDouble; }
+  bool IsHeapObject() const { return kind_ == kHeapObject; }
   bool IsExternal() const { return kind_ == kExternal; }
   bool IsSpecialization() const {
     return kind_ == kInteger32 || kind_ == kDouble;
   }
   const char* Mnemonic() const;
 
  private:
   explicit Representation(Kind k) : kind_(k) { }
 
   // Make sure kind fits in int8.
@@ skipping 90 matching lines @@
     value_ = RepresentationField::update(
         value, EncodeRepresentation(representation));
   }
 
   uint32_t value_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_PROPERTY_DETAILS_H_