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"
32 #include "langhooks.h"
35 /* Change of width--truncation and extension of integers or reals--
36 is represented with NOP_EXPR. Proper functioning of many things
37 assumes that no other conversions can be NOP_EXPRs.
39 Conversion between integer and pointer is represented with CONVERT_EXPR.
40 Converting integer to real uses FLOAT_EXPR
41 and real to integer uses FIX_TRUNC_EXPR.
43 Here is a list of all the functions that assume that widening and
44 narrowing is always done with a NOP_EXPR:
45 In convert.c, convert_to_integer.
46 In c-typeck.c, build_binary_op (boolean ops), and
47 c_common_truthvalue_conversion.
48 In expr.c: expand_expr, for operands of a MULT_EXPR.
49 In fold-const.c: fold.
50 In tree.c: get_narrower and get_unwidened. */
52 /* Subroutines of `convert'. */
56 /* Create an expression whose value is that of EXPR,
57 converted to type TYPE. The TREE_TYPE of the value
58 is always TYPE. This function implements all reasonable
59 conversions; callers should filter out those that are
60 not permitted by the language being compiled. */
63 convert (tree type
, tree expr
)
66 enum tree_code code
= TREE_CODE (type
);
67 const char *invalid_conv_diag
;
69 location_t loc
= EXPR_LOCATION (expr
);
71 if (type
== error_mark_node
72 || error_operand_p (expr
))
73 return error_mark_node
;
75 if ((invalid_conv_diag
76 = targetm
.invalid_conversion (TREE_TYPE (expr
), type
)))
78 error (invalid_conv_diag
);
79 return error_mark_node
;
82 if (type
== TREE_TYPE (expr
))
84 ret
= targetm
.convert_to_type (type
, expr
);
90 if (TYPE_MAIN_VARIANT (type
) == TYPE_MAIN_VARIANT (TREE_TYPE (expr
))
91 && (TREE_CODE (TREE_TYPE (expr
)) != COMPLEX_TYPE
92 || TREE_CODE (e
) == COMPLEX_EXPR
))
93 return fold_convert_loc (loc
, type
, expr
);
94 if (TREE_CODE (TREE_TYPE (expr
)) == ERROR_MARK
)
95 return error_mark_node
;
96 if (TREE_CODE (TREE_TYPE (expr
)) == VOID_TYPE
)
98 error ("void value not ignored as it ought to be");
99 return error_mark_node
;
105 return fold_convert_loc (loc
, type
, e
);
109 if (flag_sanitize
& SANITIZE_FLOAT_CAST
110 && TREE_CODE (TREE_TYPE (expr
)) == REAL_TYPE
111 && COMPLETE_TYPE_P (type
)
112 && do_ubsan_in_current_function ())
115 if (in_late_binary_op
)
117 expr
= save_expr (expr
);
122 expr
= c_save_expr (expr
);
123 arg
= c_fully_fold (expr
, false, NULL
);
125 tree check
= ubsan_instrument_float_cast (loc
, type
, expr
, arg
);
126 expr
= fold_build1 (FIX_TRUNC_EXPR
, type
, expr
);
129 return fold_build2 (COMPOUND_EXPR
, TREE_TYPE (expr
), check
, expr
);
131 ret
= convert_to_integer (type
, e
);
135 return fold_convert_loc
136 (loc
, type
, c_objc_common_truthvalue_conversion (input_location
, expr
));
140 ret
= convert_to_pointer (type
, e
);
144 ret
= convert_to_real (type
, e
);
147 case FIXED_POINT_TYPE
:
148 ret
= convert_to_fixed (type
, e
);
152 /* If converting from COMPLEX_TYPE to a different COMPLEX_TYPE
153 and e is not COMPLEX_EXPR, convert_to_complex uses save_expr,
154 but for the C FE c_save_expr needs to be called instead. */
155 if (TREE_CODE (TREE_TYPE (e
)) == COMPLEX_TYPE
)
157 if (TREE_CODE (e
) != COMPLEX_EXPR
)
159 tree subtype
= TREE_TYPE (type
);
160 tree elt_type
= TREE_TYPE (TREE_TYPE (e
));
162 if (in_late_binary_op
)
167 = fold_build2_loc (loc
, COMPLEX_EXPR
, type
,
169 fold_build1 (REALPART_EXPR
,
172 fold_build1 (IMAGPART_EXPR
,
177 ret
= convert_to_complex (type
, e
);
181 ret
= convert_to_vector (type
, e
);
186 if (lang_hooks
.types_compatible_p (type
, TREE_TYPE (expr
)))
194 if (TREE_CODE (ret
) != C_MAYBE_CONST_EXPR
)
199 error ("conversion to non-scalar type requested");
200 return error_mark_node
;