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/* Language-level data type conversion for GNU C.

   Copyright (C) 1987, 1988, 1991, 1998, 2002, 2003, 2004, 2005, 2007, 2008,

   2009 Free Software Foundation, Inc.

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free

Software Foundation; either version 3, or (at your option) any later

version.

GCC is distributed in the hope that it will be useful, but WITHOUT ANY

WARRANTY; without even the implied warranty of MERCHANTABILITY or

FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

for more details.

You should have received a copy of the GNU General Public License

along with GCC; see the file COPYING3.  If not see

<http://www.gnu.org/licenses/>.  */

/* This file contains the functions for converting C expressions

   to different data types.  The only entry point is `convert'.

   Every language front end must have a `convert' function

   but what kind of conversions it does will depend on the language.  */

#include "config.h"

#include "system.h"

#include "coretypes.h"

#include "tm.h"

#include "tree.h"

#include "flags.h"

#include "convert.h"

#include "c-common.h"

#include "c-tree.h"

#include "langhooks.h"

#include "toplev.h"

#include "target.h"

/* Change of width--truncation and extension of integers or reals--

   is represented with NOP_EXPR.  Proper functioning of many things

   assumes that no other conversions can be NOP_EXPRs.

   Conversion between integer and pointer is represented with CONVERT_EXPR.

   Converting integer to real uses FLOAT_EXPR

   and real to integer uses FIX_TRUNC_EXPR.

   Here is a list of all the functions that assume that widening and

   narrowing is always done with a NOP_EXPR:

     In convert.c, convert_to_integer.

     In c-typeck.c, build_binary_op (boolean ops), and

        c_common_truthvalue_conversion.

     In expr.c: expand_expr, for operands of a MULT_EXPR.

     In fold-const.c: fold.

     In tree.c: get_narrower and get_unwidened.  */

/* Subroutines of `convert'.  */

/* Create an expression whose value is that of EXPR,

   converted to type TYPE.  The TREE_TYPE of the value

   is always TYPE.  This function implements all reasonable

   conversions; callers should filter out those that are

   not permitted by the language being compiled.  */

tree

convert (tree type, tree expr)

{

  tree e = expr;

  enum tree_code code = TREE_CODE (type);

  const char *invalid_conv_diag;

  tree ret;

  location_t loc = EXPR_LOCATION (expr);

  if (type == error_mark_node

      || expr == error_mark_node

      || TREE_TYPE (expr) == error_mark_node)

    return error_mark_node;

  if ((invalid_conv_diag

       = targetm.invalid_conversion (TREE_TYPE (expr), type)))

    {

      error (invalid_conv_diag);

      return error_mark_node;

    }

  if (type == TREE_TYPE (expr))

    return expr;

  ret = targetm.convert_to_type (type, expr);

  if (ret)

      return ret;

  STRIP_TYPE_NOPS (e);

  if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)))

    return fold_convert_loc (loc, type, expr);

  if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)

    return error_mark_node;

  if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE)

    {

      error ("void value not ignored as it ought to be");

      return error_mark_node;

    }

  switch (code)

    {

    case VOID_TYPE:

      return fold_convert_loc (loc, type, e);

    case INTEGER_TYPE:

    case ENUMERAL_TYPE:

      ret = convert_to_integer (type, e);

      goto maybe_fold;

    case BOOLEAN_TYPE:

      return fold_convert_loc

        (loc, type, c_objc_common_truthvalue_conversion (input_location, expr));

    case POINTER_TYPE:

    case REFERENCE_TYPE:

      ret = convert_to_pointer (type, e);

      goto maybe_fold;

    case REAL_TYPE:

      ret = convert_to_real (type, e);

      goto maybe_fold;

    case FIXED_POINT_TYPE:

      ret = convert_to_fixed (type, e);

      goto maybe_fold;

    case COMPLEX_TYPE:

      ret = convert_to_complex (type, e);

      goto maybe_fold;

    case VECTOR_TYPE:

      ret = convert_to_vector (type, e);

      goto maybe_fold;

    case RECORD_TYPE:

    case UNION_TYPE:

      if (lang_hooks.types_compatible_p (type, TREE_TYPE (expr)))

        return e;

      break;

    default:

      break;

    maybe_fold:

      if (TREE_CODE (ret) != C_MAYBE_CONST_EXPR)

        ret = fold (ret);

      return ret;

    }

  error ("conversion to non-scalar type requested");

  return error_mark_node;

}