1 /* Language-level data type conversion for GNU C.
2 Copyright (C) 1987-2022 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"
34 #include "stringpool.h"
38 /* Change of width--truncation and extension of integers or reals--
39 is represented with NOP_EXPR. Proper functioning of many things
40 assumes that no other conversions can be NOP_EXPRs.
42 Conversion between integer and pointer is represented with CONVERT_EXPR.
43 Converting integer to real uses FLOAT_EXPR
44 and real to integer uses FIX_TRUNC_EXPR.
46 Here is a list of all the functions that assume that widening and
47 narrowing is always done with a NOP_EXPR:
48 In convert.cc, convert_to_integer.
49 In c-typeck.cc, build_binary_op (boolean ops), and
50 c_common_truthvalue_conversion.
51 In expr.cc: expand_expr, for operands of a MULT_EXPR.
52 In fold-const.cc: fold.
53 In tree.cc: get_narrower and get_unwidened. */
55 /* Subroutines of `convert'. */
59 /* Create an expression whose value is that of EXPR,
60 converted to type TYPE. The TREE_TYPE of the value
61 is always TYPE. This function implements all reasonable
62 conversions; callers should filter out those that are
63 not permitted by the language being compiled.
64 INIT_CONST is true if the conversion is for arithmetic types for a static
65 initializer and folding must apply accordingly (discarding floating-point
66 exceptions and assuming the default rounding mode is in effect). */
69 c_convert (tree type
, tree expr
, bool init_const
)
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 (sanitize_flags_p (SANITIZE_FLOAT_CAST
)
116 && current_function_decl
!= NULL_TREE
117 && TREE_CODE (TREE_TYPE (expr
)) == REAL_TYPE
118 && COMPLETE_TYPE_P (type
))
120 expr
= save_expr (expr
);
121 expr
= c_fully_fold (expr
, init_const
, NULL
);
122 tree check
= ubsan_instrument_float_cast (loc
, type
, expr
);
123 expr
= fold_build1 (FIX_TRUNC_EXPR
, type
, expr
);
124 if (check
== NULL_TREE
)
126 return fold_build2 (COMPOUND_EXPR
, TREE_TYPE (expr
), check
, expr
);
128 ret
= convert_to_integer (type
, e
);
132 return fold_convert_loc
133 (loc
, type
, c_objc_common_truthvalue_conversion (input_location
, expr
));
137 ret
= convert_to_pointer (type
, e
);
141 ret
= convert_to_real (type
, e
);
144 case FIXED_POINT_TYPE
:
145 ret
= convert_to_fixed (type
, e
);
149 ret
= convert_to_complex (type
, e
);
153 if (gnu_vector_type_p (type
)
154 || gnu_vector_type_p (TREE_TYPE (e
))
155 /* Allow conversions between compatible non-GNU vector types
156 when -flax-vector-conversions is passed. The whole purpose
157 of the option is to bend the normal type rules and accept
158 nonconforming code. */
159 || (flag_lax_vector_conversions
160 && VECTOR_TYPE_P (TREE_TYPE (e
))
161 && vector_types_convertible_p (type
, TREE_TYPE (e
), false)))
163 ret
= convert_to_vector (type
, e
);
170 if (lang_hooks
.types_compatible_p (type
, TREE_TYPE (expr
)))
178 if (TREE_CODE (ret
) != C_MAYBE_CONST_EXPR
)
179 ret
= init_const
? fold_init (ret
) : fold (ret
);
183 error ("conversion to non-scalar type requested");
184 return error_mark_node
;
187 /* Create an expression whose value is that of EXPR, converted to type TYPE.
188 The TREE_TYPE of the value is always TYPE. This function implements all
189 reasonable conversions; callers should filter out those that are not
190 permitted by the language being compiled. */
193 convert (tree type
, tree expr
)
195 return c_convert (type
, expr
, false);
198 /* Create an expression whose value is that of EXPR, converted to type TYPE, in
199 a static initializer. The TREE_TYPE of the value is always TYPE. This
200 function implements all reasonable conversions; callers should filter out
201 those that are not permitted by the language being compiled. */
204 convert_init (tree type
, tree expr
)
206 return c_convert (type
, expr
, true);