void  set_result(Value x, LIR_Opr opr)           {
   assert(opr->is_valid(), "must set to valid value");
   assert(x->operand()->is_illegal(), "operand should never change");
   assert(!opr->is_register() || opr->is_virtual(), "should never set result to a physical register");
   x->set_operand(opr);
   assert(opr == x->operand(), "must be");
   if (opr->is_virtual()) {
     _instruction_for_operand.at_put_grow(opr->vreg_number(), x, NULL);
   }
 }
 bool is_vreg_flag_set(LIR_Opr opr,  VregFlag f) { return is_vreg_flag_set(opr->vreg_number(), f); }
 void set_vreg_flag   (LIR_Opr opr,  VregFlag f) { set_vreg_flag(opr->vreg_number(), f); }