[turbofan] Clean up cached nodes in JSGraph.

src/compiler/js-graph.h

 // 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.
 
 #ifndef V8_COMPILER_JS_GRAPH_H_
 #define V8_COMPILER_JS_GRAPH_H_
 
 #include "src/compiler/common-node-cache.h"
 #include "src/compiler/common-operator.h"
 #include "src/compiler/graph.h"
@@ skipping 12 matching lines @@
 // constants, and various helper methods.
 class JSGraph : public ZoneObject {
  public:
   JSGraph(Isolate* isolate, Graph* graph, CommonOperatorBuilder* common,
           JSOperatorBuilder* javascript, MachineOperatorBuilder* machine)
       : isolate_(isolate),
         graph_(graph),
         common_(common),
         javascript_(javascript),
         machine_(machine),
-        cache_(zone()) {}
+        cache_(zone()) {
+    for (int i = 0; i < kNumCachedNodes; i++) cached_nodes_[i] = nullptr;
+  }
 
   // Canonicalized global constants.
   Node* CEntryStubConstant(int result_size);
   Node* UndefinedConstant();
   Node* TheHoleConstant();
   Node* TrueConstant();
   Node* FalseConstant();
   Node* NullConstant();
   Node* ZeroConstant();
   Node* OneConstant();
@@ skipping 77 matching lines @@
   CommonOperatorBuilder* common() const { return common_; }
   MachineOperatorBuilder* machine() const { return machine_; }
   Graph* graph() const { return graph_; }
   Zone* zone() const { return graph()->zone(); }
   Isolate* isolate() const { return isolate_; }
   Factory* factory() const { return isolate()->factory(); }
 
   void GetCachedNodes(NodeVector* nodes);
 
  private:
+  enum CachedNode {
+    kCEntryStubConstant,
+    kUndefinedConstant,
+    kTheHoleConstant,
+    kTrueConstant,
+    kFalseConstant,
+    kNullConstant,
+    kZeroConstant,
+    kOneConstant,
+    kNaNConstant,
+    kEmptyFrameState,
+    kDeadControl,
+    kNumCachedNodes  // Must remain last.
+  };
+
   Isolate* isolate_;
   Graph* graph_;
   CommonOperatorBuilder* common_;
   JSOperatorBuilder* javascript_;
   MachineOperatorBuilder* machine_;
-
-  // TODO(titzer): make this into a simple array.
-  SetOncePointer<Node> c_entry_stub_constant_;
-  SetOncePointer<Node> undefined_constant_;
-  SetOncePointer<Node> the_hole_constant_;
-  SetOncePointer<Node> true_constant_;
-  SetOncePointer<Node> false_constant_;
-  SetOncePointer<Node> null_constant_;
-  SetOncePointer<Node> zero_constant_;
-  SetOncePointer<Node> one_constant_;
-  SetOncePointer<Node> nan_constant_;
-  SetOncePointer<Node> empty_frame_state_;
-  SetOncePointer<Node> dead_control_;
-
   CommonNodeCache cache_;
+  Node* cached_nodes_[kNumCachedNodes];
 
   Node* ImmovableHeapConstant(Handle<HeapObject> value);
   Node* NumberConstant(double value);
 
   DISALLOW_COPY_AND_ASSIGN(JSGraph);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif