Make the code flushing candidate field explicit in code objects.

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 3299 matching lines @@
   inline int instruction_size();
   inline void set_instruction_size(int value);
 
   // [relocation_info]: Code relocation information
   DECL_ACCESSORS(relocation_info, ByteArray)
   void InvalidateRelocation();
 
   // [deoptimization_data]: Array containing data for deopt.
   DECL_ACCESSORS(deoptimization_data, FixedArray)
 
+  // [code_flushing_candidate]: Field only used during garbage
+  // collection to hold code flushing candidates. The contents of this
+  // field does not have to be traced during garbage collection since
+  // it is only used by the garbage collector itself.
+  DECL_ACCESSORS(code_flushing_candidate, Object)
+
   // Unchecked accessors to be used during GC.
   inline ByteArray* unchecked_relocation_info();
   inline FixedArray* unchecked_deoptimization_data();
 
   inline int relocation_size();
 
   // [flags]: Various code flags.
   inline Flags flags();
   inline void set_flags(Flags flags);
 
@@ skipping 200 matching lines @@
 
   // Max loop nesting marker used to postpose OSR. We don't take loop
   // nesting that is deeper than 5 levels into account.
   static const int kMaxLoopNestingMarker = 6;
 
   // Layout description.
   static const int kInstructionSizeOffset = HeapObject::kHeaderSize;
   static const int kRelocationInfoOffset = kInstructionSizeOffset + kIntSize;
   static const int kDeoptimizationDataOffset =
       kRelocationInfoOffset + kPointerSize;
-  static const int kFlagsOffset = kDeoptimizationDataOffset + kPointerSize;
-  static const int kKindSpecificFlagsOffset  = kFlagsOffset + kIntSize;
+  static const int kCodeFlushingCandidateOffset =
+      kDeoptimizationDataOffset + kPointerSize;
+  static const int kFlagsOffset = kCodeFlushingCandidateOffset + kPointerSize;
 
+  static const int kKindSpecificFlagsOffset = kFlagsOffset + kIntSize;
   static const int kKindSpecificFlagsSize = 2 * kIntSize;
 
   static const int kHeaderPaddingStart = kKindSpecificFlagsOffset +
       kKindSpecificFlagsSize;
 
   // Add padding to align the instruction start following right after
   // the Code object header.
   static const int kHeaderSize =
       (kHeaderPaddingStart + kCodeAlignmentMask) & ~kCodeAlignmentMask;
 
@@ skipping 3159 matching lines @@
     } else {
       value &= ~(1 << bit_position);
     }
     return value;
   }
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_OBJECTS_H_