Fix missing write barrier in store field stub.

src/x64/lithium-x64.cc

 // Copyright 2012 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 2018 matching lines @@
         new(zone()) LTransitionElementsKind(object,
                                             new_map_reg,
                                             fixed_object_reg);
     return MarkAsCall(DefineFixed(result, rax), instr);
   }
 }
 
 
 LInstruction* LChunkBuilder::DoStoreNamedField(HStoreNamedField* instr) {
   bool needs_write_barrier = instr->NeedsWriteBarrier();
+  bool needs_write_barrier_for_map = !instr->transition().is_null() &&
+      instr->NeedsWriteBarrierForMap();
 
-  LOperand* obj = needs_write_barrier
-      ? UseTempRegister(instr->object())
-      : UseRegisterAtStart(instr->object());
+  LOperand* obj;
+  if (needs_write_barrier) {
+    obj = instr->is_in_object()
+        ? UseRegister(instr->object())
+        : UseTempRegister(instr->object());
+  } else {
+    obj = needs_write_barrier_for_map
+        ? UseRegister(instr->object())
+        : UseRegisterAtStart(instr->object());
+  }
 
   LOperand* val = needs_write_barrier
       ? UseTempRegister(instr->value())
       : UseRegister(instr->value());
 
   // We only need a scratch register if we have a write barrier or we
   // have a store into the properties array (not in-object-property).
-  LOperand* temp = (!instr->is_in_object() || needs_write_barrier)
-      ? TempRegister() : NULL;
+  LOperand* temp = (!instr->is_in_object() || needs_write_barrier ||
+      needs_write_barrier_for_map) ? TempRegister() : NULL;
 
   return new(zone()) LStoreNamedField(obj, val, temp);
 }
 
 
 LInstruction* LChunkBuilder::DoStoreNamedGeneric(HStoreNamedGeneric* instr) {
   LOperand* object = UseFixed(instr->object(), rdx);
   LOperand* value = UseFixed(instr->value(), rax);
 
   LStoreNamedGeneric* result = new(zone()) LStoreNamedGeneric(object, value);
@@ skipping 254 matching lines @@
 LInstruction* LChunkBuilder::DoLoadFieldByIndex(HLoadFieldByIndex* instr) {
   LOperand* object = UseRegister(instr->object());
   LOperand* index = UseTempRegister(instr->index());
   return DefineSameAsFirst(new(zone()) LLoadFieldByIndex(object, index));
 }
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64