[interpreter] Reduce move operations for wide register support.

src/interpreter/register-translator.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_REGISTER_TRANSLATOR_H_
 #define V8_INTERPRETER_REGISTER_TRANSLATOR_H_
 
 #include "src/interpreter/bytecodes.h"
 
 namespace v8 {
@@ skipping 72 matching lines @@
   RegisterMover* mover() const { return mover_; }
 
   // Entity to perform register moves necessary to translate registers
   // and ensure reachability.
   RegisterMover* mover_;
 
   // Flag to avoid re-entrancy when emitting move bytecodes for
   // translation.
   bool emitting_moves_;
 
-  // State for restoring registers after bytecode.
-  Register window_registers_[kTranslationWindowLength];
+  // Number of window registers in use.
   int window_registers_count_;
+
+  // State for restoring register moves emitted by TranslateOutputRegisters.
+  std::pair<Register, Register> output_moves_[kTranslationWindowLength];
+  int output_moves_count_;
 };
 
 // Interface for RegisterTranslator helper class that will emit
 // register move bytecodes at the translator's behest.
 class RegisterMover {
  public:
   virtual ~RegisterMover() {}
 
   // Move register |from| to register |to| with no translation.
   // returns false if either register operand is invalid. Implementations
   // of this method must be aware that register moves with bad
   // register values are a security hole.
   virtual void MoveRegisterUntranslated(Register from, Register to) = 0;
 
   // Returns true if the register operand can be moved into the
   // translation window.
   virtual bool RegisterOperandIsMovable(Bytecode bytecode,
                                         int operand_index) = 0;
 };
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_INTERPRETER_REGISTER_TRANSLATOR_H_