1 /* Language-level data type conversion for GNU C.
2 Copyright (C) 1987, 1988, 1991, 1998, 2002, 2003, 2004, 2005, 2007, 2008,
3 2009, 2010, 2011, 2012 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 3, 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 COPYING3. If not see
19 <http://www.gnu.org/licenses/>. */
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. */
29 #include "coretypes.h"
34 #include "c-family/c-common.h"
36 #include "langhooks.h"
39 /* Change of width--truncation and extension of integers or reals--
40 is represented with NOP_EXPR. Proper functioning of many things
41 assumes that no other conversions can be NOP_EXPRs.
43 Conversion between integer and pointer is represented with CONVERT_EXPR.
44 Converting integer to real uses FLOAT_EXPR
45 and real to integer uses FIX_TRUNC_EXPR.
47 Here is a list of all the functions that assume that widening and
48 narrowing is always done with a NOP_EXPR:
49 In convert.c, convert_to_integer.
50 In c-typeck.c, build_binary_op (boolean ops), and
51 c_common_truthvalue_conversion.
52 In expr.c: expand_expr, for operands of a MULT_EXPR.
53 In fold-const.c: fold.
54 In tree.c: get_narrower and get_unwidened. */
56 /* Subroutines of `convert'. */
60 /* Create an expression whose value is that of EXPR,
61 converted to type TYPE. The TREE_TYPE of the value
62 is always TYPE. This function implements all reasonable
63 conversions; callers should filter out those that are
64 not permitted by the language being compiled. */
67 convert (tree type, tree expr)
70 enum tree_code code = TREE_CODE (type);
71 const char *invalid_conv_diag;
73 location_t loc = EXPR_LOCATION (expr);
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))
89 ret = targetm.convert_to_type (type, expr);
95 if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr))
96 && (TREE_CODE (TREE_TYPE (expr)) != COMPLEX_TYPE
97 || TREE_CODE (e) == COMPLEX_EXPR))
98 return fold_convert_loc (loc, type, expr);
99 if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
100 return error_mark_node;
101 if (TREE_CODE (TREE_TYPE (expr)) == VOID_TYPE)
103 error ("void value not ignored as it ought to be");
104 return error_mark_node;
110 return fold_convert_loc (loc, type, e);
114 ret = convert_to_integer (type, e);
118 return fold_convert_loc
119 (loc, type, c_objc_common_truthvalue_conversion (input_location, expr));
123 ret = convert_to_pointer (type, e);
127 ret = convert_to_real (type, e);
130 case FIXED_POINT_TYPE:
131 ret = convert_to_fixed (type, e);
135 /* If converting from COMPLEX_TYPE to a different COMPLEX_TYPE
136 and e is not COMPLEX_EXPR, convert_to_complex uses save_expr,
137 but for the C FE c_save_expr needs to be called instead. */
138 if (TREE_CODE (TREE_TYPE (e)) == COMPLEX_TYPE)
140 if (TREE_CODE (e) != COMPLEX_EXPR)
142 tree subtype = TREE_TYPE (type);
143 tree elt_type = TREE_TYPE (TREE_TYPE (e));
145 if (in_late_binary_op)
150 = fold_build2_loc (loc, COMPLEX_EXPR, type,
152 fold_build1 (REALPART_EXPR,
155 fold_build1 (IMAGPART_EXPR,
160 ret = convert_to_complex (type, e);
164 ret = convert_to_vector (type, e);
169 if (lang_hooks.types_compatible_p (type, TREE_TYPE (expr)))
177 if (TREE_CODE (ret) != C_MAYBE_CONST_EXPR)
182 error ("conversion to non-scalar type requested");
183 return error_mark_node;