Start using the overwrite mode from the full codegens to generate...

src/ast.h

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 183 matching lines @@
   // Symbols that cannot be parsed as array indices are considered property
   // names.  We do not treat symbols that can be array indexes as property
   // names because [] for string objects is handled only by keyed ICs.
   virtual bool IsPropertyName() { return false; }
 
   // Mark the expression as being compiled as an expression
   // statement. This is used to transform postfix increments to
   // (faster) prefix increments.
   virtual void MarkAsStatement() { /* do nothing */ }
 
+  // True iff the result can be safely overwritten (to avoid allocation).
+  // False for operations that can return one of their operands.
+  virtual bool ResultOverwriteAllowed() { return false; }
+
   // Static type information for this expression.
   StaticType* type() { return &type_; }
 
   // True if the expression is a loop condition.
   bool is_loop_condition() const {
     return LoopConditionField::decode(bitfields_);
   }
   void set_is_loop_condition(bool flag) {
     bitfields_ = (bitfields_ & ~LoopConditionField::mask()) |
         LoopConditionField::encode(flag);
@@ skipping 966 matching lines @@
 
 
 class UnaryOperation: public Expression {
  public:
   UnaryOperation(Token::Value op, Expression* expression)
       : op_(op), expression_(expression) {
     ASSERT(Token::IsUnaryOp(op));
   }
 
   virtual void Accept(AstVisitor* v);
+  virtual bool ResultOverwriteAllowed();
 
   // Type testing & conversion
   virtual UnaryOperation* AsUnaryOperation() { return this; }
 
   Token::Value op() const { return op_; }
   Expression* expression() const { return expression_; }
 
  private:
   Token::Value op_;
   Expression* expression_;
 };
 
 
 class BinaryOperation: public Expression {
  public:
   BinaryOperation(Token::Value op,
                   Expression* left,
                   Expression* right,
                   int pos)
       : op_(op), left_(left), right_(right), pos_(pos) {
     ASSERT(Token::IsBinaryOp(op));
   }
 
   // Create the binary operation corresponding to a compound assignment.
   explicit BinaryOperation(Assignment* assignment);
 
   virtual void Accept(AstVisitor* v);
+  virtual bool ResultOverwriteAllowed();
 
   // Type testing & conversion
   virtual BinaryOperation* AsBinaryOperation() { return this; }
 
-  // True iff the result can be safely overwritten (to avoid allocation).
-  // False for operations that can return one of their operands.
-  bool ResultOverwriteAllowed() {
-    switch (op_) {
-      case Token::COMMA:
-      case Token::OR:
-      case Token::AND:
-        return false;
-      case Token::BIT_OR:
-      case Token::BIT_XOR:
-      case Token::BIT_AND:
-      case Token::SHL:
-      case Token::SAR:
-      case Token::SHR:
-      case Token::ADD:
-      case Token::SUB:
-      case Token::MUL:
-      case Token::DIV:
-      case Token::MOD:
-        return true;
-      default:
-        UNREACHABLE();
-    }
-    return false;
-  }
-
   Token::Value op() const { return op_; }
   Expression* left() const { return left_; }
   Expression* right() const { return right_; }
   int position() const { return pos_; }
 
  private:
   Token::Value op_;
   Expression* left_;
   Expression* right_;
   int pos_;
@@ skipping 685 matching lines @@
   AST_NODE_LIST(DEF_VISIT)
 #undef DEF_VISIT
 
  private:
   bool stack_overflow_;
 };
 
 } }  // namespace v8::internal
 
 #endif  // V8_AST_H_