[turbofan] Introduce DeadValue and DeadEffect operators.

src/compiler/pipeline.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 "src/compiler/pipeline.h"
 
 #include <fstream>  // NOLINT(readability/streams)
 #include <sstream>
 
 #include "src/base/adapters.h"
@@ skipping 389 matching lines @@
   Reducer* const reducer_;
   SourcePositionTable* const table_;
 
   DISALLOW_COPY_AND_ASSIGN(SourcePositionWrapper);
 };
 
 
 class JSGraphReducer final : public GraphReducer {
  public:
   JSGraphReducer(JSGraph* jsgraph, Zone* zone)
-      : GraphReducer(zone, jsgraph->graph(), jsgraph->TheHoleConstant(),
+      : GraphReducer(zone, jsgraph->graph(), jsgraph->DeadValue(),
                      jsgraph->DeadControl()) {}
   ~JSGraphReducer() final {}
 };
 
 
 void AddReducer(PipelineData* data, GraphReducer* graph_reducer,
                 Reducer* reducer) {
   if (data->info()->is_source_positions_enabled()) {
     void* const buffer = data->graph_zone()->New(sizeof(SourcePositionWrapper));
     SourcePositionWrapper* const wrapper =
@@ skipping 940 matching lines @@
     tcf << AsC1VRegisterAllocationData("CodeGen",
                                        data->register_allocation_data());
   }
 
   data->DeleteRegisterAllocationZone();
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8