[interpreter] Add a fast path for dynamic local load

src/interpreter/interpreter-assembler.h

 // Copyright 2015 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_INTERPRETER_INTERPRETER_ASSEMBLER_H_
 #define V8_INTERPRETER_INTERPRETER_ASSEMBLER_H_
 
 #include "src/allocation.h"
 #include "src/builtins/builtins.h"
 #include "src/code-stub-assembler.h"
@@ skipping 38 matching lines @@
   compiler::Node* BytecodeOperandIntrinsicId(int operand_index);
 
   // Accumulator.
   compiler::Node* GetAccumulator();
   void SetAccumulator(compiler::Node* value);
 
   // Context.
   compiler::Node* GetContext();
   void SetContext(compiler::Node* value);
 
-  // Context at |depth| in the context chain starting at |context|
+  // Context at |depth| in the context chain starting at |context|.
   compiler::Node* GetContextAtDepth(compiler::Node* context,
                                     compiler::Node* depth);
 
+  // Goto the given |target| if the context chain starting at |context| has any
+  // extensions up to the given |depth|.
+  void GotoIfHasContextExtensionUpToDepth(compiler::Node* context,
+                                          compiler::Node* depth, Label* target);
+
   // Number of registers.
   compiler::Node* RegisterCount();
 
   // Backup/restore register file to/from a fixed array of the correct length.
   compiler::Node* ExportRegisterFile(compiler::Node* array);
   compiler::Node* ImportRegisterFile(compiler::Node* array);
 
   // Loads from and stores to the interpreter register file.
   compiler::Node* LoadRegister(Register reg);
   compiler::Node* LoadRegister(compiler::Node* reg_index);
@@ skipping 230 matching lines @@
   compiler::Node* stack_pointer_before_call_;
 
   DISALLOW_COPY_AND_ASSIGN(InterpreterAssembler);
 };
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_INTERPRETER_INTERPRETER_ASSEMBLER_H_