[turbofan] Base more write barrier decisions on machine representation.

src/compiler/js-native-context-specialization.cc

 // Copyright 2015 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 "src/compiler/js-native-context-specialization.h"
 
 #include "src/accessors.h"
 #include "src/code-factory.h"
 #include "src/compilation-dependencies.h"
 #include "src/compiler/access-builder.h"
@@ skipping 948 matching lines @@
         value = effect = graph()->NewNode(simplified()->CheckTaggedPointer(),
                                           value, effect, control);
         Handle<Map> field_map;
         if (access_info.field_map().ToHandle(&field_map)) {
           // Emit a map check for the value.
           effect = graph()->NewNode(simplified()->CheckMaps(1), value,
                                     jsgraph()->HeapConstant(field_map), effect,
                                     control);
         }
       } else {
-        // DCHECK(field_type->Is(Type::Tagged()));
         DCHECK(rep == MachineRepresentation::kTagged);
       }
       Handle<Map> transition_map;
       if (access_info.transition_map().ToHandle(&transition_map)) {
         effect = graph()->NewNode(
             common()->BeginRegion(RegionObservability::kObservable), effect);
         effect = graph()->NewNode(
             simplified()->StoreField(AccessBuilder::ForMap()), receiver,
             jsgraph()->Constant(transition_map), effect, control);
       }
@@ skipping 501 matching lines @@
 }
 
 
 SimplifiedOperatorBuilder* JSNativeContextSpecialization::simplified() const {
   return jsgraph()->simplified();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8