eval.c

早期freebsd实现

	    {
	      arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
	    }
	  /* Now, say which argument to start evaluating from */
	  tem = 2;
	}
      else
	{
	  nargs = longest_to_int (exp->elts[pc + 1].longconst);
	  tem = 0;
	}
      argvec = (value *) alloca (sizeof (value) * (nargs + 2));
      for (; tem <= nargs; tem++)
	/* Ensure that array expressions are coerced into pointer objects. */
	argvec[tem] = evaluate_subexp_with_coercion (exp, pos, noside);

      /* signal end of arglist */
      argvec[tem] = 0;

      if (op == STRUCTOP_STRUCT || op == STRUCTOP_PTR)
	{
	  int static_memfuncp;
	  value temp = arg2;

	  argvec[1] = arg2;
	  argvec[0] =
	    value_struct_elt (&temp, argvec+1, &exp->elts[pc2 + 1].string,
			      &static_memfuncp,
			      op == STRUCTOP_STRUCT
			      ? "structure" : "structure pointer");
	  if (VALUE_OFFSET (temp))
	    {
	      arg2 = value_from_longest (lookup_pointer_type (VALUE_TYPE (temp)),
				      value_as_long (arg2)+VALUE_OFFSET (temp));
	      argvec[1] = arg2;
	    }
	  if (static_memfuncp)
	    {
	      argvec[1] = argvec[0];
	      nargs--;
	      argvec++;
	    }
	}
      else if (op == STRUCTOP_MEMBER || op == STRUCTOP_MPTR)
	{
	  argvec[1] = arg2;
	  argvec[0] = arg1;
	}

      if (noside == EVAL_SKIP)
	goto nosideret;
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
	{
	  /* If the return type doesn't look like a function type, call an
	     error.  This can happen if somebody tries to turn a variable into
	     a function call. This is here because people often want to
	     call, eg, strcmp, which gdb doesn't know is a function.  If
	     gdb isn't asked for it's opinion (ie. through "whatis"),
	     it won't offer it. */

	  struct type *ftype =
	    TYPE_TARGET_TYPE (VALUE_TYPE (argvec[0]));

	  if (ftype)
	    return allocate_value (TYPE_TARGET_TYPE (VALUE_TYPE (argvec[0])));
	  else
	    error ("Expression of type other than \"Function returning ...\" used as function");
	}
      return call_function_by_hand (argvec[0], nargs, argvec + 1);

    case STRUCTOP_STRUCT:
      tem = strlen (&exp->elts[pc + 1].string);
      (*pos) += 2 + ((tem + sizeof (union exp_element))
		     / sizeof (union exp_element));
      /* Try to convert "foo.bar" into "(&foo)->bar" so we won't copy
         the entire contents of a large struct just to extract one
	 value from it. */
      if (noside == EVAL_NORMAL && exp->elts[*pos].opcode == OP_VAR_VALUE
	  && value_has_lval(exp->elts[*pos + 1].symbol))
	arg1 = evaluate_subexp_for_address(exp, pos, noside);
      else
        arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);

      if (noside == EVAL_SKIP)
	goto nosideret;
      if (noside == EVAL_AVOID_SIDE_EFFECTS) {
	register struct type *type = VALUE_TYPE (arg1);
	if (TYPE_CODE (type) == TYPE_CODE_PTR)
	  type = TYPE_TARGET_TYPE (type);
	return value_zero (lookup_struct_elt_type (type,
						   &exp->elts[pc + 1].string,
						   1),
			   lval_memory);
	}
      else
	{
	  value temp = arg1;
	  return value_struct_elt (&temp, (value *)0, &exp->elts[pc + 1].string,
				   (int *) 0, "structure");
	}

    case STRUCTOP_PTR:
      tem = strlen (&exp->elts[pc + 1].string);
      (*pos) += 2 + (tem + sizeof (union exp_element)) / sizeof (union exp_element);
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
	return value_zero (lookup_struct_elt_type (TYPE_TARGET_TYPE
						   (VALUE_TYPE (arg1)),
						   &exp->elts[pc + 1].string,
						   0),
			   lval_memory);
      else
	{
	  value temp = arg1;
	  return value_struct_elt (&temp, (value *)0, &exp->elts[pc + 1].string,
				   (int *) 0, "structure pointer");
	}

    case STRUCTOP_MEMBER:
      arg1 = evaluate_subexp_for_address (exp, pos, noside);
      goto handle_pointer_to_member;
    case STRUCTOP_MPTR:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
    handle_pointer_to_member:
      arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      if (TYPE_CODE (VALUE_TYPE (arg2)) != TYPE_CODE_PTR)
	goto bad_pointer_to_member;
      type = TYPE_TARGET_TYPE (VALUE_TYPE (arg2));
      if (TYPE_CODE (type) == TYPE_CODE_METHOD)
	error ("not implemented: pointer-to-method in pointer-to-member construct");
      if (TYPE_CODE (type) != TYPE_CODE_MEMBER)
	goto bad_pointer_to_member;
      /* Now, convert these values to an address.  */
      arg1 = value_cast (lookup_pointer_type (TYPE_DOMAIN_TYPE (type)),
			 arg1);
      arg3 = value_from_longest (lookup_pointer_type (TYPE_TARGET_TYPE (type)),
				 value_as_long (arg1) + value_as_long (arg2));
      return value_ind (arg3);
    bad_pointer_to_member:
      error("non-pointer-to-member value used in pointer-to-member construct");

    case BINOP_ASSIGN:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP || noside == EVAL_AVOID_SIDE_EFFECTS)
	return arg1;
      if (binop_user_defined_p (op, arg1, arg2))
	return value_x_binop (arg1, arg2, op, OP_NULL);
      else
	return value_assign (arg1, arg2);

    case BINOP_ASSIGN_MODIFY:
      (*pos) += 2;
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP || noside == EVAL_AVOID_SIDE_EFFECTS)
	return arg1;
      op = exp->elts[pc + 1].opcode;
      if (binop_user_defined_p (op, arg1, arg2))
	return value_x_binop (arg1, arg2, BINOP_ASSIGN_MODIFY, op);
      else if (op == BINOP_ADD)
	arg2 = value_add (arg1, arg2);
      else if (op == BINOP_SUB)
	arg2 = value_sub (arg1, arg2);
      else
	arg2 = value_binop (arg1, arg2, op);
      return value_assign (arg1, arg2);

    case BINOP_ADD:
      arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
      arg2 = evaluate_subexp_with_coercion (exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
	return value_x_binop (arg1, arg2, op, OP_NULL);
      else
	return value_add (arg1, arg2);

    case BINOP_SUB:
      arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
      arg2 = evaluate_subexp_with_coercion (exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
	return value_x_binop (arg1, arg2, op, OP_NULL);
      else
	return value_sub (arg1, arg2);

    case BINOP_MUL:
    case BINOP_DIV:
    case BINOP_REM:
    case BINOP_LSH:
    case BINOP_RSH:
    case BINOP_LOGAND:
    case BINOP_LOGIOR:
    case BINOP_LOGXOR:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
	return value_x_binop (arg1, arg2, op, OP_NULL);
      else
	if (noside == EVAL_AVOID_SIDE_EFFECTS
	    && (op == BINOP_DIV || op == BINOP_REM))
	  return value_zero (VALUE_TYPE (arg1), not_lval);
      else
	return value_binop (arg1, arg2, op);

    case BINOP_SUBSCRIPT:
      arg1 = evaluate_subexp_with_coercion (exp, pos, noside);
      arg2 = evaluate_subexp_with_coercion (exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      if (noside == EVAL_AVOID_SIDE_EFFECTS)
	{
	  /* If the user attempts to subscript something that has no target
	     type (like a plain int variable for example), then report this
	     as an error. */

	  type = TYPE_TARGET_TYPE (VALUE_TYPE (arg1));
	  if (type)
	    return value_zero (type, VALUE_LVAL (arg1));
	  else
	    error ("cannot subscript something of type `%s'",
		   TYPE_NAME (VALUE_TYPE (arg1)));
	}
			   
      if (binop_user_defined_p (op, arg1, arg2))
	return value_x_binop (arg1, arg2, op, OP_NULL);
      else
	return value_subscript (arg1, arg2);
      
    case BINOP_AND:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
	{
	  arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
	  goto nosideret;
	}
      
      oldpos = *pos;
      arg2 = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
      *pos = oldpos;
      
      if (binop_user_defined_p (op, arg1, arg2)) 
	{
	  arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
	  return value_x_binop (arg1, arg2, op, OP_NULL);
	}
      else
	{
	  tem = value_zerop (arg1);
	  arg2 = evaluate_subexp (NULL_TYPE, exp, pos,
				  (tem ? EVAL_SKIP : noside));
	  return value_from_longest (builtin_type_int,
				  (LONGEST) (!tem && !value_zerop (arg2)));
	}

    case BINOP_OR:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      if (noside == EVAL_SKIP)
	{
	  arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
	  goto nosideret;
	}
      
      oldpos = *pos;
      arg2 = evaluate_subexp (NULL_TYPE, exp, pos, EVAL_AVOID_SIDE_EFFECTS);
      *pos = oldpos;
      
      if (binop_user_defined_p (op, arg1, arg2)) 
	{
	  arg2 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
	  return value_x_binop (arg1, arg2, op, OP_NULL);
	}
      else
	{
	  tem = value_zerop (arg1);
	  arg2 = evaluate_subexp (NULL_TYPE, exp, pos,
				  (!tem ? EVAL_SKIP : noside));
	  return value_from_longest (builtin_type_int,
				  (LONGEST) (!tem || !value_zerop (arg2)));
	}

    case BINOP_EQUAL:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
	{
	  return value_x_binop (arg1, arg2, op, OP_NULL);
	}
      else
	{
	  tem = value_equal (arg1, arg2);
	  return value_from_longest (builtin_type_int, (LONGEST) tem);
	}

    case BINOP_NOTEQUAL:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
	{
	  return value_x_binop (arg1, arg2, op, OP_NULL);
	}
      else
	{
	  tem = value_equal (arg1, arg2);
	  return value_from_longest (builtin_type_int, (LONGEST) ! tem);
	}

    case BINOP_LESS:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
	{
	  return value_x_binop (arg1, arg2, op, OP_NULL);
	}
      else
	{
	  tem = value_less (arg1, arg2);
	  return value_from_longest (builtin_type_int, (LONGEST) tem);
	}

    case BINOP_GTR:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
	{
	  return value_x_binop (arg1, arg2, op, OP_NULL);
	}
      else
	{
	  tem = value_less (arg2, arg1);
	  return value_from_longest (builtin_type_int, (LONGEST) tem);
	}

    case BINOP_GEQ:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
	{
	  return value_x_binop (arg1, arg2, op, OP_NULL);
	}
      else
	{
	  tem = value_less (arg2, arg1) || value_equal (arg1, arg2);
	  return value_from_longest (builtin_type_int, (LONGEST) tem);
	}

    case BINOP_LEQ:
      arg1 = evaluate_subexp (NULL_TYPE, exp, pos, noside);
      arg2 = evaluate_subexp (VALUE_TYPE (arg1), exp, pos, noside);
      if (noside == EVAL_SKIP)
	goto nosideret;
      if (binop_user_defined_p (op, arg1, arg2))
	{
	  return value_x_binop (arg1, arg2, op, OP_NULL);