Dramatically speed up detailed heap snapshot generation.

src/objects-inl.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 1295 matching lines @@
 
 int JSObject::GetInternalFieldCount() {
   ASSERT(1 << kPointerSizeLog2 == kPointerSize);
   // Make sure to adjust for the number of in-object properties. These
   // properties do contribute to the size, but are not internal fields.
   return ((Size() - GetHeaderSize()) >> kPointerSizeLog2) -
          map()->inobject_properties();
 }
 
 
+int JSObject::GetInternalFieldOffset(int index) {
+  ASSERT(index < GetInternalFieldCount() && index >= 0);
+  return GetHeaderSize() + (kPointerSize * index);
+}
+
+
 Object* JSObject::GetInternalField(int index) {
   ASSERT(index < GetInternalFieldCount() && index >= 0);
   // Internal objects do follow immediately after the header, whereas in-object
   // properties are at the end of the object. Therefore there is no need
   // to adjust the index here.
   return READ_FIELD(this, GetHeaderSize() + (kPointerSize * index));
 }
 
 
 void JSObject::SetInternalField(int index, Object* value) {
   ASSERT(index < GetInternalFieldCount() && index >= 0);
   // Internal objects do follow immediately after the header, whereas in-object
   // properties are at the end of the object. Therefore there is no need
   // to adjust the index here.
   int offset = GetHeaderSize() + (kPointerSize * index);
   WRITE_FIELD(this, offset, value);
   WRITE_BARRIER(this, offset);
 }
 
 
 // Access fast-case object properties at index. The use of these routines
 // is needed to correctly distinguish between properties stored in-object and
 // properties stored in the properties array.
+int JSObject::GetFastPropertyOffset(int index) {

[Vitaly Repeshko, 2011/03/18 12:16:36]

This should be called "GetInObjectPropertyOffset". It should assert the index
does not exceed the number of inobject properties and its callers should make
sure not to trigger the assert.

[mnaganov (inactive), 2011/03/18 12:31:01]

Done.

+  // Adjust for the number of properties stored in the object.
+  index -= map()->inobject_properties();
+  return index < 0 ? map()->instance_size() + (index * kPointerSize) : -1;
+}
+
+
 Object* JSObject::FastPropertyAt(int index) {
   // Adjust for the number of properties stored in the object.
   index -= map()->inobject_properties();
   if (index < 0) {
     int offset = map()->instance_size() + (index * kPointerSize);
     return READ_FIELD(this, offset);
   } else {
     ASSERT(index < properties()->length());
     return properties()->get(index);
   }
@@ skipping 2587 matching lines @@
 #undef WRITE_INT_FIELD
 #undef READ_SHORT_FIELD
 #undef WRITE_SHORT_FIELD
 #undef READ_BYTE_FIELD
 #undef WRITE_BYTE_FIELD
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_INL_H_