[Turbofan] Make GenericLowering operate concurrently.

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/base/compiler-specific.h"
 #include "src/compiler/common-node-cache.h"
 #include "src/compiler/common-operator.h"
@@ skipping 144 matching lines @@
   Isolate* isolate() const { return isolate_; }
   Factory* factory() const { return isolate()->factory(); }
 
   void GetCachedNodes(NodeVector* nodes);
 
  private:
   enum CachedNode {
     kAllocateInNewSpaceStubConstant,
     kAllocateInOldSpaceStubConstant,
     kToNumberBuiltinConstant,
-    kCEntryStubConstant,
-    kCEntryStubWithBuiltinExitFrameConstant,
+    kCEntryStub1Constant,
+    kCEntryStub2Constant,
+    kCEntryStub3Constant,
+    kCEntryStub1WithBuiltinExitFrameConstant,
     kEmptyFixedArrayConstant,
     kEmptyLiteralsArrayConstant,
     kEmptyStringConstant,
     kFixedArrayMapConstant,
     kFixedDoubleArrayMapConstant,
     kHeapNumberMapConstant,
     kOptimizedOutConstant,
     kStaleRegisterConstant,
     kUndefinedConstant,
     kTheHoleConstant,
@@ skipping 20 matching lines @@
   Node* NumberConstant(double value);
 
   DISALLOW_COPY_AND_ASSIGN(JSGraph);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif