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

src/objects.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 5681 matching lines @@
   // Computes the size for an AsciiString instance of a given length.
   static int SizeFor(int length) {
     return OBJECT_POINTER_ALIGN(kHeaderSize + length * kCharSize);
   }
 
   // Layout description.
   static const int kHeaderSize = String::kSize;
   static const int kAlignedSize = POINTER_SIZE_ALIGN(kHeaderSize);
 
   // Maximal memory usage for a single sequential ASCII string.
-  static const int kMaxSize = 512 * MB;
+  static const int kMaxSize = 512 * MB - 1;
   // Maximal length of a single sequential ASCII string.
   // Q.v. String::kMaxLength which is the maximal size of concatenated strings.
   static const int kMaxLength = (kMaxSize - kHeaderSize);
 
   // Support for StringInputBuffer.
   inline void SeqAsciiStringReadBlockIntoBuffer(ReadBlockBuffer* buffer,
                                                 unsigned* offset,
                                                 unsigned chars);
   inline const unibrow::byte* SeqAsciiStringReadBlock(unsigned* remaining,
                                                       unsigned* offset,
@@ skipping 33 matching lines @@
   // Computes the size for a TwoByteString instance of a given length.
   static int SizeFor(int length) {
     return OBJECT_POINTER_ALIGN(kHeaderSize + length * kShortSize);
   }
 
   // Layout description.
   static const int kHeaderSize = String::kSize;
   static const int kAlignedSize = POINTER_SIZE_ALIGN(kHeaderSize);
 
   // Maximal memory usage for a single sequential two-byte string.
-  static const int kMaxSize = 512 * MB;
+  static const int kMaxSize = 512 * MB - 1;
   // Maximal length of a single sequential two-byte string.
   // Q.v. String::kMaxLength which is the maximal size of concatenated strings.
   static const int kMaxLength = (kMaxSize - kHeaderSize) / sizeof(uint16_t);
 
   // Support for StringInputBuffer.
   inline void SeqTwoByteStringReadBlockIntoBuffer(ReadBlockBuffer* buffer,
                                                   unsigned* offset_ptr,
                                                   unsigned chars);
 
  private:
@@ skipping 988 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_