[Interpreter] Bytecodes for exchanging registers.

src/compiler/bytecode-graph-builder.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_COMPILER_BYTECODE_GRAPH_BUILDER_H_
 #define V8_COMPILER_BYTECODE_GRAPH_BUILDER_H_
 
 #include "src/compiler.h"
 #include "src/compiler/bytecode-branch-analysis.h"
 #include "src/compiler/js-graph.h"
@@ skipping 249 matching lines @@
 class BytecodeGraphBuilder::Environment : public ZoneObject {
  public:
   Environment(BytecodeGraphBuilder* builder, int register_count,
               int parameter_count, Node* control_dependency, Node* context);
 
   int parameter_count() const { return parameter_count_; }
   int register_count() const { return register_count_; }
 
   void BindRegister(interpreter::Register the_register, Node* node);
   Node* LookupRegister(interpreter::Register the_register) const;
+  void ExchangeRegisters(interpreter::Register reg0,
+                         interpreter::Register reg1);
 
   void BindAccumulator(Node* node, FrameStateBeforeAndAfter* states = nullptr);
   Node* LookupAccumulator() const;
 
   void RecordAfterState(Node* node, FrameStateBeforeAndAfter* states);
 
   bool IsMarkedAsUnreachable() const;
   void MarkAsUnreachable();
 
   // Effect dependency tracked by this environment.
@@ skipping 53 matching lines @@
   Node* accumulator_state_values_;
   int register_base_;
   int accumulator_base_;
 };
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_BYTECODE_GRAPH_BUILDER_H_