Dramatically speed up detailed heap snapshot generation.

src/objects.h

 // Copyright 2010 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 1103 matching lines @@
   inline bool IsOverflowed();
 
   // Mutate this object's map pointer to indicate that the object is
   // overflowed.
   inline void SetOverflow();
 
   // Mutate this object's map pointer to remove the indication that the
   // object is overflowed (ie, partially restore the map pointer).
   inline void ClearOverflow();
 
+  // Returns address of the field at offset in obj.
+  inline Address GetFieldAddress(int offset);

[Vitaly Repeshko, 2011/03/17 16:52:00]

This is "obj->address() + offset". If a helper for this is really need, please
move it to the profiler code.

[mnaganov (inactive), 2011/03/17 17:37:18]

Removed.

+
   // Returns the field at offset in obj, as a read/write Object* reference.
   // Does no checking, and is safe to use during GC, while maps are invalid.
   // Does not invoke write barrier, so should only be assigned to
   // during marking GC.
   static inline Object** RawField(HeapObject* obj, int offset);
 
   // Casting.
   static inline HeapObject* cast(Object* obj);
 
   // Return the write barrier mode for this. Callers of this function
@@ skipping 446 matching lines @@
   bool HasRealNamedCallbackProperty(String* key);
 
   // Initializes the array to a certain length
   MUST_USE_RESULT MaybeObject* SetElementsLength(Object* length);
 
   // Get the header size for a JSObject.  Used to compute the index of
   // internal fields as well as the number of internal fields.
   inline int GetHeaderSize();
 
   inline int GetInternalFieldCount();
+  inline Address GetInternalFieldOffset(int index);

[Vitaly Repeshko, 2011/03/17 16:52:00]

Since it's called "...Offset" it should return an offset. Then a generic helper
can turn it into an address.

[mnaganov (inactive), 2011/03/17 17:37:18]

Fixed.

   inline Object* GetInternalField(int index);
   inline void SetInternalField(int index, Object* value);
 
   // Lookup a property.  If found, the result is valid and has
   // detailed information.
   void LocalLookup(String* name, LookupResult* result);
   void Lookup(String* name, LookupResult* result);
 
   // The following lookup functions skip interceptors.
   void LocalLookupRealNamedProperty(String* name, LookupResult* result);
@@ skipping 93 matching lines @@
   MUST_USE_RESULT MaybeObject* NormalizeElements();
 
   MUST_USE_RESULT MaybeObject* UpdateMapCodeCache(String* name, Code* code);
 
   // Transform slow named properties to fast variants.
   // Returns failure if allocation failed.
   MUST_USE_RESULT MaybeObject* TransformToFastProperties(
       int unused_property_fields);
 
   // Access fast-case object properties at index.
+  inline Address GetFastPropertyAddress(int index);

[Vitaly Repeshko, 2011/03/17 16:52:00]

I think this also should return an offset.

[mnaganov (inactive), 2011/03/17 17:37:18]

Done.

   inline Object* FastPropertyAt(int index);
   inline Object* FastPropertyAtPut(int index, Object* value);
 
   // Access to in object properties.
   inline Object* InObjectPropertyAt(int index);
   inline Object* InObjectPropertyAtPut(int index,
                                        Object* value,
                                        WriteBarrierMode mode
                                        = UPDATE_WRITE_BARRIER);
 
@@ skipping 4871 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_