[turbofan] Skip write barriers when storing smi.

test/cctest/compiler/test-simplified-lowering.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include <limits>
 
 #include "src/compiler/access-builder.h"
 #include "src/compiler/change-lowering.h"
 #include "src/compiler/control-builders.h"
 #include "src/compiler/graph-reducer.h"
@@ skipping 1445 matching lines @@
     CHECK_EQ(IrOpcode::kStore, store->opcode());
     CHECK_EQ(val, store->InputAt(2));
     CheckFieldAccessArithmetic(access, store);
 
     StoreRepresentation rep = OpParameter<StoreRepresentation>(store);
     if (kMachineReps[i] & kRepTagged) {
       CHECK_EQ(kFullWriteBarrier, rep.write_barrier_kind());
     }
     CHECK_EQ(kMachineReps[i], rep.machine_type());
   }
+
+  if (t.machine()->Is64()) {
+    FieldAccess access = {kTaggedBase, FixedArrayBase::kHeaderSize,
+                          Handle<Name>::null(), Type::Any(), kMachAnyTagged};
+    Node* val = t.graph()->NewNode(t.simplified()->ChangeInt32ToTagged(), t.p0);
+    Node* store = t.graph()->NewNode(t.simplified()->StoreField(access), t.p0,
+                                     val, t.start, t.start);
+    t.Effect(store);
+    t.Lower();
+    CHECK_EQ(IrOpcode::kStore, store->opcode());
+    CHECK_EQ(val, store->InputAt(2));
+    StoreRepresentation rep = OpParameter<StoreRepresentation>(store);
+    CHECK_EQ(kNoWriteBarrier, rep.write_barrier_kind());
+  }
 }
 
 
 TEST(LowerLoadElement_to_load) {
   TestingGraph t(Type::Any(), Type::Signed32());
 
   for (size_t i = 0; i < arraysize(kMachineReps); i++) {
     ElementAccess access = {kTaggedBase, FixedArrayBase::kHeaderSize,
                             Type::Any(), kMachineReps[i]};
 
@@ skipping 564 matching lines @@
     Bounds phi_bounds = Bounds::Either(Bounds(d.arg1), Bounds(d.arg2), z);
     NodeProperties::SetBounds(phi, phi_bounds);
 
     Node* use = t.Use(phi, d.use);
     t.Return(use);
     t.Lower();
 
     CHECK_EQ(d.expected, OpParameter<MachineType>(phi));
   }
 }