[turbofan] Avoid unnecessary copying of nodes during inlining.

src/compiler/ast-graph-builder.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_AST_GRAPH_BUILDER_H_
 #define V8_COMPILER_AST_GRAPH_BUILDER_H_
 
 #include "src/ast/ast.h"
 #include "src/compiler/js-graph.h"
 #include "src/compiler/liveness-analyzer.h"
@@ skipping 88 matching lines @@
   int try_catch_nesting_level_;
   int try_nesting_level_;
 
   // Temporary storage for building node input lists.
   int input_buffer_size_;
   Node** input_buffer_;
 
   // Optimization to cache loaded feedback vector.
   SetOncePointer<Node> feedback_vector_;
 
+  // Optimization to cache empty frame state.
+  SetOncePointer<Node> empty_frame_state_;
+
   // Control nodes that exit the function body.
   ZoneVector<Node*> exit_controls_;
 
   // Result of loop assignment analysis performed before graph creation.
   LoopAssignmentAnalysis* loop_assignment_analysis_;
 
   // Result of type hint analysis performed before graph creation.
   TypeHintAnalysis* type_hint_analysis_;
 
   // Cache for StateValues nodes for frame states.
@@ skipping 41 matching lines @@
   // Get or create the node that represents the incoming function closure.
   Node* GetFunctionClosureForContext();
   Node* GetFunctionClosure();
 
   // Get or create the node that represents the incoming function context.
   Node* GetFunctionContext();
 
   // Get or create the node that represents the incoming new target value.
   Node* GetNewTarget();
 
+  // Get or create the node that represents the empty frame state.
+  Node* GetEmptyFrameState();
+
   // Node creation helpers.
   Node* NewNode(const Operator* op, bool incomplete = false) {
     return MakeNode(op, 0, static_cast<Node**>(nullptr), incomplete);
   }
 
   Node* NewNode(const Operator* op, Node* n1) {
     return MakeNode(op, 1, &n1, false);
   }
 
   Node* NewNode(const Operator* op, Node* n1, Node* n2) {
@@ skipping 412 matching lines @@
 
   // Prepare environment to be used as loop header.
   void PrepareForLoop(BitVector* assigned, bool is_osr = false);
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_AST_GRAPH_BUILDER_H_