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/* Language-level data type conversion for GNU C.
Copyright (C) 1987, 1988, 1991, 1998, 2002, 2003, 2004
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. */
#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 "langhooks.h"
#include "toplev.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);
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 = lang_hooks.truthvalue_conversion (expr);
if (TREE_CODE (t) == ERROR_MARK)
return t;
/* 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));
if ((code == RECORD_TYPE || code == UNION_TYPE)
&& lang_hooks.types_compatible_p (type, TREE_TYPE (expr)))
return e;
error ("conversion to non-scalar type requested");
return error_mark_node;
}
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