Remove write barriers for cells on x64, ARM and MIPS.

src/mips/lithium-codegen-mips.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 2123 matching lines @@
   // it as no longer deleted.
   if (instr->hydrogen()->RequiresHoleCheck()) {
     __ lw(scratch2,
           FieldMemOperand(scratch, JSGlobalPropertyCell::kValueOffset));
     __ LoadRoot(at, Heap::kTheHoleValueRootIndex);
     DeoptimizeIf(eq, instr->environment(), scratch2, Operand(at));
   }
 
   // Store the value.
   __ sw(value, FieldMemOperand(scratch, JSGlobalPropertyCell::kValueOffset));
-
-  // Cells are always in the remembered set.
-  if (instr->hydrogen()->NeedsWriteBarrier()) {
-    HType type = instr->hydrogen()->value()->type();
-    SmiCheck check_needed =
-        type.IsHeapObject() ? OMIT_SMI_CHECK : INLINE_SMI_CHECK;
-    __ RecordWriteField(scratch,
-                        JSGlobalPropertyCell::kValueOffset,
-                        value,
-                        scratch2,
-                        kRAHasBeenSaved,
-                        kSaveFPRegs,
-                        OMIT_REMEMBERED_SET,
-                        check_needed);
-  }
+  // Cells are always rescanned, so no write barrier here.
 }
 
 
 void LCodeGen::DoStoreGlobalGeneric(LStoreGlobalGeneric* instr) {
   ASSERT(ToRegister(instr->global_object()).is(a1));
   ASSERT(ToRegister(instr->value()).is(a0));
 
   __ li(a2, Operand(instr->name()));
   Handle<Code> ic = (instr->strict_mode_flag() == kStrictMode)
       ? isolate()->builtins()->StoreIC_Initialize_Strict()
@@ skipping 2476 matching lines @@
   ASSERT(!environment->HasBeenRegistered());
   RegisterEnvironmentForDeoptimization(environment, Safepoint::kNoLazyDeopt);
   ASSERT(osr_pc_offset_ == -1);
   osr_pc_offset_ = masm()->pc_offset();
 }
 
 
 #undef __
 
 } }  // namespace v8::internal