Estimate a (close) upper bound on the size of black-marked objects on each page.

src/ia32/macro-assembler-ia32.h

 // Copyright 2011 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 119 matching lines @@
   // then we just fall through, since it is already live.  If it is white and
   // we can determine that it doesn't need to be scanned, then we just mark it
   // black and fall through.  For the rest we jump to the label so the
   // incremental marker can fix its assumptions.
   void EnsureNotWhite(Register object,
                       Register scratch1,
                       Register scratch2,
                       Label* object_is_white_and_not_data,
                       Label::Distance distance);
 
-  // Detects conservatively whether an object is data-only, ie it does need to
-  // be scanned by the garbage collector.
-  void JumpIfDataObject(Register value,
-                        Register scratch,
-                        Label* not_data_object,
-                        Label::Distance not_data_object_distance);
-
   // Notify the garbage collector that we wrote a pointer into an object.
   // |object| is the object being stored into, |value| is the object being
   // stored.  value and scratch registers are clobbered by the operation.
   // The offset is the offset from the start of the object, not the offset from
   // the tagged HeapObject pointer.  For use with FieldOperand(reg, off).
   void RecordWriteField(
       Register object,
       int offset,
       Register value,
       Register scratch,
@@ skipping 731 matching lines @@
   }                                                                       \
   masm->
 #else
 #define ACCESS_MASM(masm) masm->
 #endif
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_IA32_MACRO_ASSEMBLER_IA32_H_