1 /* Language-level data type conversion for GNU C.
2 Copyright (C) 1987, 1988, 1991, 1998, 2002, 2003, 2004, 2005
3 Free Software Foundation, Inc.
5 This file is part of GCC.
7 GCC is free software; you can redistribute it and/or modify it under
8 the terms of the GNU General Public License as published by the Free
9 Software Foundation; either version 2, or (at your option) any later
12 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
13 WARRANTY; without even the implied warranty of MERCHANTABILITY or
14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
17 You should have received a copy of the GNU General Public License
18 along with GCC; see the file COPYING. If not, write to the Free
19 Software Foundation, 51 Franklin Street, Fifth Floor, Boston, MA
23 /* This file contains the functions for converting C expressions
24 to different data types. The only entry point is `convert'.
25 Every language front end must have a `convert' function
26 but what kind of conversions it does will depend on the language. */
30 #include "coretypes.h"
37 #include "langhooks.h"
40 /* Change of width--truncation and extension of integers or reals--
41 is represented with NOP_EXPR. Proper functioning of many things
42 assumes that no other conversions can be NOP_EXPRs.
44 Conversion between integer and pointer is represented with CONVERT_EXPR.
45 Converting integer to real uses FLOAT_EXPR
46 and real to integer uses FIX_TRUNC_EXPR.
48 Here is a list of all the functions that assume that widening and
49 narrowing is always done with a NOP_EXPR:
50 In convert.c, convert_to_integer.
51 In c-typeck.c, build_binary_op (boolean ops), and
52 c_common_truthvalue_conversion.
53 In expr.c: expand_expr, for operands of a MULT_EXPR.
54 In fold-const.c: fold.
55 In tree.c: get_narrower and get_unwidened. */
57 /* Subroutines of `convert'. */
61 /* Create an expression whose value is that of EXPR,
62 converted to type TYPE. The TREE_TYPE of the value
63 is always TYPE. This function implements all reasonable
64 conversions; callers should filter out those that are
65 not permitted by the language being compiled. */
68 convert (tree type
, tree expr
)
71 enum tree_code code
= TREE_CODE (type
);
73 if (type
== TREE_TYPE (expr
)
74 || TREE_CODE (expr
) == ERROR_MARK
75 || code
== ERROR_MARK
|| TREE_CODE (TREE_TYPE (expr
)) == ERROR_MARK
)
78 if (TYPE_MAIN_VARIANT (type
) == TYPE_MAIN_VARIANT (TREE_TYPE (expr
)))
79 return fold (build1 (NOP_EXPR
, type
, expr
));
80 if (TREE_CODE (TREE_TYPE (expr
)) == ERROR_MARK
)
81 return error_mark_node
;
82 if (TREE_CODE (TREE_TYPE (expr
)) == VOID_TYPE
)
84 error ("void value not ignored as it ought to be");
85 return error_mark_node
;
87 if (code
== VOID_TYPE
)
88 return build1 (CONVERT_EXPR
, type
, e
);
90 /* This is incorrect. A truncation can't be stripped this way.
91 Extensions will be stripped by the use of get_unwidened. */
92 if (TREE_CODE (expr
) == NOP_EXPR
)
93 return convert (type
, TREE_OPERAND (expr
, 0));
95 if (code
== INTEGER_TYPE
|| code
== ENUMERAL_TYPE
)
96 return fold (convert_to_integer (type
, e
));
97 if (code
== BOOLEAN_TYPE
)
99 tree t
= c_objc_common_truthvalue_conversion (expr
);
100 if (TREE_CODE (t
) == ERROR_MARK
)
103 /* If it returns a NOP_EXPR, we must fold it here to avoid
104 infinite recursion between fold () and convert (). */
105 if (TREE_CODE (t
) == NOP_EXPR
)
106 return fold (build1 (NOP_EXPR
, type
, TREE_OPERAND (t
, 0)));
108 return fold (build1 (NOP_EXPR
, type
, t
));
110 if (code
== POINTER_TYPE
|| code
== REFERENCE_TYPE
)
111 return fold (convert_to_pointer (type
, e
));
112 if (code
== REAL_TYPE
)
113 return fold (convert_to_real (type
, e
));
114 if (code
== COMPLEX_TYPE
)
115 return fold (convert_to_complex (type
, e
));
116 if (code
== VECTOR_TYPE
)
117 return fold (convert_to_vector (type
, e
));
118 if ((code
== RECORD_TYPE
|| code
== UNION_TYPE
)
119 && lang_hooks
.types_compatible_p (type
, TREE_TYPE (expr
)))
122 error ("conversion to non-scalar type requested");
123 return error_mark_node
;