Incremental mode now works for x64. The only difference

src/x64/lithium-codegen-x64.cc

 // 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 2203 matching lines @@
 }
 
 
 void LCodeGen::DoStoreGlobalCell(LStoreGlobalCell* instr) {
   Register object = ToRegister(instr->TempAt(0));
   Register address = ToRegister(instr->TempAt(1));
   Register value = ToRegister(instr->InputAt(0));
   ASSERT(!value.is(object));
   Handle<JSGlobalPropertyCell> cell_handle(instr->hydrogen()->cell());
 
-  int offset = JSGlobalPropertyCell::kValueOffset;
   __ movq(address, cell_handle, RelocInfo::GLOBAL_PROPERTY_CELL);
 
   // If the cell we are storing to contains the hole it could have
   // been deleted from the property dictionary. In that case, we need
   // to update the property details in the property dictionary to mark
   // it as no longer deleted. We deoptimize in that case.
   if (instr->hydrogen()->check_hole_value()) {
     __ CompareRoot(Operand(address, 0), Heap::kTheHoleValueRootIndex);
     DeoptimizeIf(equal, instr->environment());
   }
 
   // Store the value.
   __ movq(Operand(address, 0), value);
 
   Label smi_store;
   __ JumpIfSmi(value, &smi_store, Label::kNear);
 
+  int offset = JSGlobalPropertyCell::kValueOffset - kHeapObjectTag;
   __ lea(object, Operand(address, -offset));
   // Cells are always in the remembered set.
   __ RecordWrite(object,
                  address,
                  value,
                  kSaveFPRegs,
                  OMIT_REMEMBERED_SET,
                  OMIT_SMI_CHECK);
   __ bind(&smi_store);
 }
@@ skipping 2017 matching lines @@
   RegisterEnvironmentForDeoptimization(environment);
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64