1 /* Language-level data type conversion for GNU C.
2 Copyright (C) 1987-2015 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 3, 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 COPYING3. If not see
18 <http://www.gnu.org/licenses/>. */
21 /* This file contains the functions for converting C expressions
22 to different data types. The only entry point is `convert'.
23 Every language front end must have a `convert' function
24 but what kind of conversions it does will depend on the language. */
28 #include "coretypes.h"
35 #include "c-family/c-common.h"
37 #include "langhooks.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. */
69 convert (tree type
, tree expr
)
72 enum tree_code code
= TREE_CODE (type
);
73 const char *invalid_conv_diag
;
75 location_t loc
= EXPR_LOCATION (expr
);
77 if (type
== error_mark_node
78 || error_operand_p (expr
))
79 return error_mark_node
;
81 if ((invalid_conv_diag
82 = targetm
.invalid_conversion (TREE_TYPE (expr
), type
)))
84 error (invalid_conv_diag
);
85 return error_mark_node
;
88 if (type
== TREE_TYPE (expr
))
90 ret
= targetm
.convert_to_type (type
, expr
);
96 if (TYPE_MAIN_VARIANT (type
) == TYPE_MAIN_VARIANT (TREE_TYPE (expr
))
97 && (TREE_CODE (TREE_TYPE (expr
)) != COMPLEX_TYPE
98 || TREE_CODE (e
) == COMPLEX_EXPR
))
99 return fold_convert_loc (loc
, type
, expr
);
100 if (TREE_CODE (TREE_TYPE (expr
)) == ERROR_MARK
)
101 return error_mark_node
;
102 if (TREE_CODE (TREE_TYPE (expr
)) == VOID_TYPE
)
104 error ("void value not ignored as it ought to be");
105 return error_mark_node
;
111 return fold_convert_loc (loc
, type
, e
);
115 if (flag_sanitize
& SANITIZE_FLOAT_CAST
116 && TREE_CODE (TREE_TYPE (expr
)) == REAL_TYPE
117 && COMPLETE_TYPE_P (type
)
118 && do_ubsan_in_current_function ())
121 if (in_late_binary_op
)
123 expr
= save_expr (expr
);
128 expr
= c_save_expr (expr
);
129 arg
= c_fully_fold (expr
, false, NULL
);
131 tree check
= ubsan_instrument_float_cast (loc
, type
, expr
, arg
);
132 expr
= fold_build1 (FIX_TRUNC_EXPR
, type
, expr
);
135 return fold_build2 (COMPOUND_EXPR
, TREE_TYPE (expr
), check
, expr
);
137 ret
= convert_to_integer (type
, e
);
141 return fold_convert_loc
142 (loc
, type
, c_objc_common_truthvalue_conversion (input_location
, expr
));
146 ret
= convert_to_pointer (type
, e
);
150 ret
= convert_to_real (type
, e
);
153 case FIXED_POINT_TYPE
:
154 ret
= convert_to_fixed (type
, e
);
158 /* If converting from COMPLEX_TYPE to a different COMPLEX_TYPE
159 and e is not COMPLEX_EXPR, convert_to_complex uses save_expr,
160 but for the C FE c_save_expr needs to be called instead. */
161 if (TREE_CODE (TREE_TYPE (e
)) == COMPLEX_TYPE
)
163 if (TREE_CODE (e
) != COMPLEX_EXPR
)
165 tree subtype
= TREE_TYPE (type
);
166 tree elt_type
= TREE_TYPE (TREE_TYPE (e
));
168 if (in_late_binary_op
)
173 = fold_build2_loc (loc
, COMPLEX_EXPR
, type
,
175 fold_build1 (REALPART_EXPR
,
178 fold_build1 (IMAGPART_EXPR
,
183 ret
= convert_to_complex (type
, e
);
187 ret
= convert_to_vector (type
, e
);
192 if (lang_hooks
.types_compatible_p (type
, TREE_TYPE (expr
)))
200 if (TREE_CODE (ret
) != C_MAYBE_CONST_EXPR
)
205 error ("conversion to non-scalar type requested");
206 return error_mark_node
;