Incremental mode now works for x64. The only difference

src/arm/code-stubs-arm.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 515 matching lines @@
         if (candidate.is(r2)) continue;
         if (candidate.is(r3)) continue;
         return candidate;
       }
       UNREACHABLE();
       return no_reg;
     }
     friend class RecordWriteStub;
   };
 
+  enum OnNoNeedToInformIncrementalMarker {
+    kReturnOnNoNeedToInformIncrementalMarker,
+    kRememberedSetOnNoNeedToInformIncrementalMarker
+  };
+
   void Generate(MacroAssembler* masm);
+  void GenerateIncremental(MacroAssembler* masm);
+  void CheckNeedsToInformIncrementalMarker(
+      MacroAssembler* masm,
+      OnNoNeedToInformIncrementalMarker on_no_need);
+  void InformIncrementalMarker(MacroAssembler* masm);
 
   Major MajorKey() { return RecordWrite; }
 
   int MinorKey() {
     return ObjectBits::encode(object_.code()) |
         ValueBits::encode(value_.code()) |
         AddressBits::encode(address_.code()) |
         RememberedSetActionBits::encode(remembered_set_action_) |
         SaveFPRegsModeBits::encode(save_fp_regs_mode_);
   }
@@ skipping 250 matching lines @@
 
   class LookupModeBits: public BitField<LookupMode, 0, 1> {};
 
   LookupMode mode_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_ARM_CODE_STUBS_ARM_H_