First steps towards better code generation for LBranch:

src/ast.h

 // Copyright 2011 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 192 matching lines @@
     // code generation.
     kUninitialized,
     // Evaluated for its side effects.
     kEffect,
     // Evaluated for its value (and side effects).
     kValue,
     // Evaluated for control flow (and side effects).
     kTest
   };
 
-  Expression() : id_(GetNextId()) {}
+  Expression() : id_(GetNextId()), test_id_(GetNextId()) {}
 
   virtual int position() const {
     UNREACHABLE();
     return 0;
   }
 
   virtual Expression* AsExpression()  { return this; }
 
   virtual bool IsTrivial() { return false; }
   virtual bool IsValidLeftHandSide() { return false; }
@@ skipping 38 matching lines @@
   }
 
   ExternalArrayType external_array_type() const {
     return external_array_type_;
   }
   void set_external_array_type(ExternalArrayType array_type) {
     external_array_type_ = array_type;
   }
 
   unsigned id() const { return id_; }
+  unsigned test_id() const { return test_id_; }
 
  private:
   ExternalArrayType external_array_type_;
   unsigned id_;
+  unsigned test_id_;
 };
 
 
 /**
  * A sentinel used during pre parsing that represents some expression
  * that is a valid left hand side without having to actually build
  * the expression.
  */
 class ValidLeftHandSideSentinel: public Expression {
  public:
@@ skipping 1866 matching lines @@
 
  private:
   Isolate* isolate_;
   bool stack_overflow_;
 };
 
 
 } }  // namespace v8::internal
 
 #endif  // V8_AST_H_