[turbofan] Avoid creating singleton state-values for the accumulator.

src/compiler/js-graph.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/js-graph.h"
 
 #include "src/code-stubs.h"
 #include "src/compiler/node-properties.h"
 #include "src/compiler/typer.h"
 #include "src/objects-inl.h"
@@ skipping 262 matching lines @@
 
 Node* JSGraph::ExternalConstant(Runtime::FunctionId function_id) {
   return ExternalConstant(ExternalReference(function_id, isolate()));
 }
 
 Node* JSGraph::EmptyStateValues() {
   return CACHED(kEmptyStateValues, graph()->NewNode(common()->StateValues(
                                        0, SparseInputMask::Dense())));
 }
 
+Node* JSGraph::SingleDeadTypedStateValues() {
+  return CACHED(kSingleDeadTypedStateValues,
+                graph()->NewNode(common()->TypedStateValues(
+                    new (graph()->zone()->New(sizeof(ZoneVector<MachineType>)))
+                        ZoneVector<MachineType>(0, graph()->zone()),
+                    SparseInputMask(SparseInputMask::kEndMarker << 1))));
+}
+
 Node* JSGraph::Dead() {
   return CACHED(kDead, graph()->NewNode(common()->Dead()));
 }
 
 
 void JSGraph::GetCachedNodes(NodeVector* nodes) {
   cache_.GetCachedNodes(nodes);
   for (size_t i = 0; i < arraysize(cached_nodes_); i++) {
     if (Node* node = cached_nodes_[i]) {
       if (!node->IsDead()) nodes->push_back(node);
     }
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8