947c79bcadb3e9ce891a8715b30b1ecec481028e
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 GCC.
6 GCC is free software; you can redistribute it and/or modify it under
7 the terms of the GNU General Public License as published by the Free
8 Software Foundation; either version 2, or (at your option) any later
11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
12 WARRANTY; without even the implied warranty of MERCHANTABILITY or
13 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
16 You should have received a copy of the GNU General Public License
17 along with GCC; see the file COPYING. If not, write to the Free
18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
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. */
34 /* Change of width--truncation and extension of integers or reals--
35 is represented with NOP_EXPR. Proper functioning of many things
36 assumes that no other conversions can be NOP_EXPRs.
38 Conversion between integer and pointer is represented with CONVERT_EXPR.
39 Converting integer to real uses FLOAT_EXPR
40 and real to integer uses FIX_TRUNC_EXPR.
42 Here is a list of all the functions that assume that widening and
43 narrowing is always done with a NOP_EXPR:
44 In convert.c, convert_to_integer.
45 In c-typeck.c, build_binary_op (boolean ops), and truthvalue_conversion.
46 In expr.c: expand_expr, for operands of a MULT_EXPR.
47 In fold-const.c: fold.
48 In tree.c: get_narrower and get_unwidened. */
50 /* Subroutines of `convert'. */
54 /* Create an expression whose value is that of EXPR,
55 converted to type TYPE. The TREE_TYPE of the value
56 is always TYPE. This function implements all reasonable
57 conversions; callers should filter out those that are
58 not permitted by the language being compiled. */
65 enum tree_code code
= TREE_CODE (type
);
67 if (type
== TREE_TYPE (expr
)
68 || TREE_CODE (expr
) == ERROR_MARK
69 || code
== ERROR_MARK
|| TREE_CODE (TREE_TYPE (expr
)) == ERROR_MARK
)
72 if (TYPE_MAIN_VARIANT (type
) == TYPE_MAIN_VARIANT (TREE_TYPE (expr
)))
73 return fold (build1 (NOP_EXPR
, type
, expr
));
74 if (TREE_CODE (TREE_TYPE (expr
)) == ERROR_MARK
)
75 return error_mark_node
;
76 if (TREE_CODE (TREE_TYPE (expr
)) == VOID_TYPE
)
78 error ("void value not ignored as it ought to be");
79 return error_mark_node
;
81 if (code
== VOID_TYPE
)
82 return build1 (CONVERT_EXPR
, type
, e
);
84 /* This is incorrect. A truncation can't be stripped this way.
85 Extensions will be stripped by the use of get_unwidened. */
86 if (TREE_CODE (expr
) == NOP_EXPR
)
87 return convert (type
, TREE_OPERAND (expr
, 0));
89 if (code
== INTEGER_TYPE
|| code
== ENUMERAL_TYPE
)
90 return fold (convert_to_integer (type
, e
));
91 if (code
== BOOLEAN_TYPE
)
93 tree t
= truthvalue_conversion (expr
);
94 /* If truthvalue_conversion returns a NOP_EXPR, we must fold it here
95 to avoid infinite recursion between fold () and convert (). */
96 if (TREE_CODE (t
) == NOP_EXPR
)
97 return fold (build1 (NOP_EXPR
, type
, TREE_OPERAND (t
, 0)));
99 return fold (build1 (NOP_EXPR
, type
, t
));
101 if (code
== POINTER_TYPE
|| code
== REFERENCE_TYPE
)
102 return fold (convert_to_pointer (type
, e
));
103 if (code
== REAL_TYPE
)
104 return fold (convert_to_real (type
, e
));
105 if (code
== COMPLEX_TYPE
)
106 return fold (convert_to_complex (type
, e
));
107 if (code
== VECTOR_TYPE
)
108 return fold (convert_to_vector (type
, e
));
110 error ("conversion to non-scalar type requested");
111 return error_mark_node
;