9cb941662f2c15e1869b18d2caf82cba2de0d548
1 /* Language-level data type conversion for GNU C.
2 Copyright (C) 1987, 1988, 1991, 1998 Free Software Foundation, Inc.
4 This file is part of GNU CC.
6 GNU CC is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2, or (at your option)
11 GNU CC is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with GNU CC; see the file COPYING. If not, write to
18 the Free Software Foundation, 59 Temple Place - Suite 330,
19 Boston, MA 02111-1307, USA. */
22 /* This file contains the functions for converting C expressions
23 to different data types. The only entry point is `convert'.
24 Every language front end must have a `convert' function
25 but what kind of conversions it does will depend on the language. */
33 /* Change of width--truncation and extension of integers or reals--
34 is represented with NOP_EXPR. Proper functioning of many things
35 assumes that no other conversions can be NOP_EXPRs.
37 Conversion between integer and pointer is represented with CONVERT_EXPR.
38 Converting integer to real uses FLOAT_EXPR
39 and real to integer uses FIX_TRUNC_EXPR.
41 Here is a list of all the functions that assume that widening and
42 narrowing is always done with a NOP_EXPR:
43 In convert.c, convert_to_integer.
44 In c-typeck.c, build_binary_op (boolean ops), and truthvalue_conversion.
45 In expr.c: expand_expr, for operands of a MULT_EXPR.
46 In fold-const.c: fold.
47 In tree.c: get_narrower and get_unwidened. */
49 /* Subroutines of `convert'. */
53 /* Create an expression whose value is that of EXPR,
54 converted to type TYPE. The TREE_TYPE of the value
55 is always TYPE. This function implements all reasonable
56 conversions; callers should filter out those that are
57 not permitted by the language being compiled. */
63 register tree e
= expr
;
64 register enum tree_code code
= TREE_CODE (type
);
66 if (type
== TREE_TYPE (expr
)
67 || TREE_CODE (expr
) == ERROR_MARK
)
69 if (TYPE_MAIN_VARIANT (type
) == TYPE_MAIN_VARIANT (TREE_TYPE (expr
)))
70 return fold (build1 (NOP_EXPR
, type
, expr
));
71 if (TREE_CODE (TREE_TYPE (expr
)) == ERROR_MARK
)
72 return error_mark_node
;
73 if (TREE_CODE (TREE_TYPE (expr
)) == VOID_TYPE
)
75 error ("void value not ignored as it ought to be");
76 return error_mark_node
;
78 if (code
== VOID_TYPE
)
79 return build1 (CONVERT_EXPR
, type
, e
);
81 /* This is incorrect. A truncation can't be stripped this way.
82 Extensions will be stripped by the use of get_unwidened. */
83 if (TREE_CODE (expr
) == NOP_EXPR
)
84 return convert (type
, TREE_OPERAND (expr
, 0));
86 if (code
== INTEGER_TYPE
|| code
== ENUMERAL_TYPE
)
87 return fold (convert_to_integer (type
, e
));
88 if (code
== POINTER_TYPE
)
89 return fold (convert_to_pointer (type
, e
));
90 if (code
== REAL_TYPE
)
91 return fold (convert_to_real (type
, e
));
92 if (code
== COMPLEX_TYPE
)
93 return fold (convert_to_complex (type
, e
));
95 error ("conversion to non-scalar type requested");
96 return error_mark_node
;