/* Language-level data type conversion for GNU C.
   Copyright (C) 1987, 1988, 1991, 1998, 2002 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 2, 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 COPYING.  If not, write to the Free
Software Foundation, 59 Temple Place - Suite 330, Boston, MA
02111-1307, USA.  */


/* 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.  */

/* copied from the f77 frontend I think */

/* copied from c-convert.c without significant modification*/
/* 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.
*/

/* I've added support for WITH_RECORD_EXPR.  */


#include "trans.h"
#include "convert.h"


/*
   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.  */

/* We are assuming that given a SIMPLE val, the result will be a SIMPLE rhs.
   If this is not the case, we will abort with an internal error.  */

tree convert(tree type, tree expr) {
  tree e = expr;
  enum tree_code code = TREE_CODE(type);

  if (type == TREE_TYPE(expr)
      || TREE_CODE(expr) == ERROR_MARK
      || code == ERROR_MARK || TREE_CODE(TREE_TYPE(expr)) == ERROR_MARK)
    return expr;

  if (TYPE_MAIN_VARIANT(type) == TYPE_MAIN_VARIANT(TREE_TYPE(expr)))
    return fold(build1(NOP_EXPR, 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;
  }

  if (code == VOID_TYPE)
    return build1(CONVERT_EXPR, type, e);
#if 0
  /* This is incorrect.  A truncation can't be stripped this way.
     Extensions will be stripped by the use of get_unwidened.  */
  if (TREE_CODE(expr) == NOP_EXPR)
    return convert(type, TREE_OPERAND(expr, 0));
#endif
  if (code == INTEGER_TYPE || code == ENUMERAL_TYPE)
    return fold(convert_to_integer(type, e));

  if (code == BOOLEAN_TYPE) {
    tree t = g95_truthvalue_conversion(expr);

    /* If it returns a NOP_EXPR, we must fold it here to avoid
       infinite recursion between fold () and convert ().  */
    if (TREE_CODE(t) == NOP_EXPR)
      return fold(build1(NOP_EXPR, type, TREE_OPERAND(t, 0)));
    else
      return fold(build1(NOP_EXPR, type, t));
  }

  if (code == POINTER_TYPE || code == REFERENCE_TYPE)
    return fold(convert_to_pointer (type, e));

  if (code == REAL_TYPE)
    return fold(convert_to_real (type, e));

  if (code == COMPLEX_TYPE)
    return fold(convert_to_complex (type, e));

  if (code == VECTOR_TYPE)
    return fold(convert_to_vector (type, e));

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