2006-03-15 Paul Brook <paul@codesourcery.com>
[official-gcc.git] / gcc / c-convert.c
blobbf306c8ea2fe7e55be4e199a8a1322fc06a245d6
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
10 version.
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
15 for more details.
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
20 02110-1301, USA. */
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. */
28 #include "config.h"
29 #include "system.h"
30 #include "coretypes.h"
31 #include "tm.h"
32 #include "tree.h"
33 #include "flags.h"
34 #include "convert.h"
35 #include "c-common.h"
36 #include "c-tree.h"
37 #include "langhooks.h"
38 #include "toplev.h"
39 #include "target.h"
41 /* Change of width--truncation and extension of integers or reals--
42 is represented with NOP_EXPR. Proper functioning of many things
43 assumes that no other conversions can be NOP_EXPRs.
45 Conversion between integer and pointer is represented with CONVERT_EXPR.
46 Converting integer to real uses FLOAT_EXPR
47 and real to integer uses FIX_TRUNC_EXPR.
49 Here is a list of all the functions that assume that widening and
50 narrowing is always done with a NOP_EXPR:
51 In convert.c, convert_to_integer.
52 In c-typeck.c, build_binary_op (boolean ops), and
53 c_common_truthvalue_conversion.
54 In expr.c: expand_expr, for operands of a MULT_EXPR.
55 In fold-const.c: fold.
56 In tree.c: get_narrower and get_unwidened. */
58 /* Subroutines of `convert'. */
62 /* Create an expression whose value is that of EXPR,
63 converted to type TYPE. The TREE_TYPE of the value
64 is always TYPE. This function implements all reasonable
65 conversions; callers should filter out those that are
66 not permitted by the language being compiled. */
68 tree
69 convert (tree type, tree expr)
71 tree e = expr;
72 enum tree_code code = TREE_CODE (type);
73 const char *invalid_conv_diag;
75 if (type == error_mark_node
76 || expr == error_mark_node
77 || TREE_TYPE (expr) == error_mark_node)
78 return error_mark_node;
80 if ((invalid_conv_diag
81 = targetm.invalid_conversion (TREE_TYPE (expr), type)))
83 error (invalid_conv_diag);
84 return error_mark_node;
87 if (type == TREE_TYPE (expr))
88 return expr;
90 if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr)))
91 return fold_convert (type, expr);
92 if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
93 return error_mark_node;
94 if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE)
96 error ("void value not ignored as it ought to be");
97 return error_mark_node;
99 if (code == VOID_TYPE)
100 return fold_convert (type, e);
101 if (code == INTEGER_TYPE || code == ENUMERAL_TYPE)
102 return fold (convert_to_integer (type, e));
103 if (code == BOOLEAN_TYPE)
104 return fold_convert (type, c_objc_common_truthvalue_conversion (expr));
105 if (code == POINTER_TYPE || code == REFERENCE_TYPE)
106 return fold (convert_to_pointer (type, e));
107 if (code == REAL_TYPE)
108 return fold (convert_to_real (type, e));
109 if (code == COMPLEX_TYPE)
110 return fold (convert_to_complex (type, e));
111 if (code == VECTOR_TYPE)
112 return fold (convert_to_vector (type, e));
113 if ((code == RECORD_TYPE || code == UNION_TYPE)
114 && lang_hooks.types_compatible_p (type, TREE_TYPE (expr)))
115 return e;
117 error ("conversion to non-scalar type requested");
118 return error_mark_node;