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1 : : /* Language-level data type conversion for GNU C.
2 : : Copyright (C) 1987-2024 Free Software Foundation, Inc.
3 : :
4 : : This file is part of GCC.
5 : :
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
9 : : version.
10 : :
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
14 : : for more details.
15 : :
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/>. */
19 : :
20 : :
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. */
25 : :
26 : : #include "config.h"
27 : : #include "system.h"
28 : : #include "coretypes.h"
29 : : #include "target.h"
30 : : #include "c-tree.h"
31 : : #include "convert.h"
32 : : #include "langhooks.h"
33 : : #include "ubsan.h"
34 : : #include "stringpool.h"
35 : : #include "attribs.h"
36 : : #include "asan.h"
37 : :
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.
41 : :
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.
45 : :
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. */
54 : :
55 : : /* Subroutines of `convert'. */
56 : :
57 : :
58 : :
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). */
67 : :
68 : : static tree
69 : 600838801 : c_convert (tree type, tree expr, bool init_const)
70 : : {
71 : 600838801 : tree e = expr;
72 : 600838801 : enum tree_code code = TREE_CODE (type);
73 : 600838801 : const char *invalid_conv_diag;
74 : 600838801 : tree ret;
75 : 600838801 : location_t loc = EXPR_LOCATION (expr);
76 : :
77 : 600838801 : if (type == error_mark_node
78 : 600838801 : || error_operand_p (expr))
79 : : return error_mark_node;
80 : :
81 : 1201677410 : if ((invalid_conv_diag
82 : 600838705 : = targetm.invalid_conversion (TREE_TYPE (expr), type)))
83 : : {
84 : 2 : error (invalid_conv_diag);
85 : 2 : return error_mark_node;
86 : : }
87 : :
88 : 600838703 : if (type == TREE_TYPE (expr))
89 : : return expr;
90 : 218066447 : ret = targetm.convert_to_type (type, expr);
91 : 218066447 : if (ret)
92 : : return ret;
93 : :
94 : 218099189 : STRIP_TYPE_NOPS (e);
95 : :
96 : 218066447 : if (TYPE_MAIN_VARIANT (type) == TYPE_MAIN_VARIANT (TREE_TYPE (expr))
97 : 218066447 : && (TREE_CODE (TREE_TYPE (expr)) != COMPLEX_TYPE
98 : 35224 : || TREE_CODE (e) == COMPLEX_EXPR))
99 : 56723419 : return fold_convert_loc (loc, type, expr);
100 : 161343028 : if (TREE_CODE (TREE_TYPE (expr)) == ERROR_MARK)
101 : 0 : return error_mark_node;
102 : 161343028 : if (VOID_TYPE_P (TREE_TYPE (expr)))
103 : : {
104 : 0 : error ("void value not ignored as it ought to be");
105 : 0 : return error_mark_node;
106 : : }
107 : :
108 : 161343028 : {
109 : 161343028 : tree false_value, true_value;
110 : 161343028 : if (c_hardbool_type_attr (type, &false_value, &true_value))
111 : : {
112 : 4284 : bool save = in_late_binary_op;
113 : 4284 : in_late_binary_op = true;
114 : 4284 : expr = c_objc_common_truthvalue_conversion (input_location, expr);
115 : 4284 : in_late_binary_op = save;
116 : :
117 : 4284 : return fold_build3_loc (loc, COND_EXPR, type,
118 : 4284 : expr, true_value, false_value);
119 : : }
120 : : }
121 : :
122 : 161338744 : switch (code)
123 : : {
124 : 63408 : case VOID_TYPE:
125 : 63408 : return fold_convert_loc (loc, type, e);
126 : :
127 : 114753 : case ENUMERAL_TYPE:
128 : 114753 : if (ENUM_UNDERLYING_TYPE (type) != NULL_TREE
129 : 114753 : && TREE_CODE (ENUM_UNDERLYING_TYPE (type)) == BOOLEAN_TYPE)
130 : 165 : goto convert_to_boolean;
131 : 49829690 : gcc_fallthrough ();
132 : :
133 : 49829690 : case INTEGER_TYPE:
134 : 49829690 : case BITINT_TYPE:
135 : 49829690 : if (sanitize_flags_p (SANITIZE_FLOAT_CAST)
136 : 87219 : && current_function_decl != NULL_TREE
137 : 87219 : && SCALAR_FLOAT_TYPE_P (TREE_TYPE (expr))
138 : 49841414 : && COMPLETE_TYPE_P (type))
139 : : {
140 : 11724 : expr = save_expr (expr);
141 : 11724 : expr = c_fully_fold (expr, init_const, NULL);
142 : 11724 : tree check = ubsan_instrument_float_cast (loc, type, expr);
143 : 11724 : expr = fold_build1 (FIX_TRUNC_EXPR, type, expr);
144 : 11724 : if (check == NULL_TREE)
145 : : return expr;
146 : 7128 : return fold_build2 (COMPOUND_EXPR, TREE_TYPE (expr), check, expr);
147 : : }
148 : 49817966 : ret = convert_to_integer (type, e);
149 : 49817966 : goto maybe_fold;
150 : :
151 : 37286 : case BOOLEAN_TYPE:
152 : 37286 : convert_to_boolean:
153 : 37286 : return c_objc_common_truthvalue_conversion (input_location, expr, type);
154 : :
155 : 6276369 : case POINTER_TYPE:
156 : : /* The type nullptr_t may be converted to a pointer type. The result is
157 : : a null pointer value. */
158 : 6276369 : if (NULLPTR_TYPE_P (TREE_TYPE (e)))
159 : : {
160 : : /* To make sure that (void *)nullptr is not a null pointer constant,
161 : : build_c_cast will create an additional NOP_EXPR around the result
162 : : of this conversion. */
163 : 650 : if (TREE_SIDE_EFFECTS (e))
164 : 16 : ret = build2 (COMPOUND_EXPR, type, e, build_int_cst (type, 0));
165 : : else
166 : 634 : ret = build_int_cst (type, 0);
167 : 650 : goto maybe_fold;
168 : : }
169 : 6275719 : gcc_fallthrough ();
170 : 6275719 : case REFERENCE_TYPE:
171 : 6275719 : ret = convert_to_pointer (type, e);
172 : 6275719 : goto maybe_fold;
173 : :
174 : 9 : case NULLPTR_TYPE:
175 : : /* A null pointer constant or value of type nullptr_t may be
176 : : converted to nullptr_t. The latter case has already been
177 : : handled. build_c_cast will create an additional NOP_EXPR to
178 : : ensure the result of the conversion is not itself a null
179 : : pointer constant. */
180 : 9 : if (null_pointer_constant_p (expr))
181 : : {
182 : 7 : ret = build_int_cst (type, 0);
183 : 7 : goto maybe_fold;
184 : : }
185 : : break;
186 : :
187 : 991566 : case REAL_TYPE:
188 : 991566 : ret = convert_to_real (type, e);
189 : 991566 : goto maybe_fold;
190 : :
191 : 0 : case FIXED_POINT_TYPE:
192 : 0 : ret = convert_to_fixed (type, e);
193 : 0 : goto maybe_fold;
194 : :
195 : 130872 : case COMPLEX_TYPE:
196 : 130872 : ret = convert_to_complex (type, e);
197 : 130872 : goto maybe_fold;
198 : :
199 : 104009517 : case VECTOR_TYPE:
200 : 104009517 : if (gnu_vector_type_p (type)
201 : 0 : || gnu_vector_type_p (TREE_TYPE (e))
202 : : /* Allow conversions between compatible non-GNU vector types
203 : : when -flax-vector-conversions is passed. The whole purpose
204 : : of the option is to bend the normal type rules and accept
205 : : nonconforming code. */
206 : 104009517 : || (flag_lax_vector_conversions
207 : 0 : && VECTOR_TYPE_P (TREE_TYPE (e))
208 : 0 : && vector_types_convertible_p (type, TREE_TYPE (e), false)))
209 : : {
210 : 104009517 : ret = convert_to_vector (type, e);
211 : 104009517 : goto maybe_fold;
212 : : }
213 : : break;
214 : :
215 : 27 : case RECORD_TYPE:
216 : 27 : case UNION_TYPE:
217 : 27 : if (lang_hooks.types_compatible_p (type, TREE_TYPE (expr)))
218 : : return e;
219 : : break;
220 : :
221 : : default:
222 : : break;
223 : :
224 : 161226297 : maybe_fold:
225 : 161226297 : if (TREE_CODE (ret) != C_MAYBE_CONST_EXPR)
226 : 161226283 : ret = init_const ? fold_init (ret) : fold (ret);
227 : : return ret;
228 : : }
229 : :
230 : : /* If we are converting to nullptr_t, don't say "non-scalar type" because
231 : : the nullptr_t type is a scalar type. Only nullptr_t or a null pointer
232 : : constant shall be converted to nullptr_t. */
233 : 8 : if (code == NULLPTR_TYPE)
234 : : {
235 : 2 : error ("conversion from %qT to %qT", TREE_TYPE (e), type);
236 : 2 : inform (input_location,
237 : : "only %qT or a null pointer constant can be converted to %qT",
238 : : type, type);
239 : : }
240 : : else
241 : 6 : error ("conversion to non-scalar type requested");
242 : 8 : return error_mark_node;
243 : : }
244 : :
245 : : /* Create an expression whose value is that of EXPR, converted to type TYPE.
246 : : The TREE_TYPE of the value is always TYPE. This function implements all
247 : : reasonable conversions; callers should filter out those that are not
248 : : permitted by the language being compiled. */
249 : :
250 : : tree
251 : 600293623 : convert (tree type, tree expr)
252 : : {
253 : 600293623 : return c_convert (type, expr, false);
254 : : }
255 : :
256 : : /* Create an expression whose value is that of EXPR, converted to type TYPE, in
257 : : a static initializer. The TREE_TYPE of the value is always TYPE. This
258 : : function implements all reasonable conversions; callers should filter out
259 : : those that are not permitted by the language being compiled. */
260 : :
261 : : tree
262 : 545178 : convert_init (tree type, tree expr)
263 : : {
264 : 545178 : return c_convert (type, expr, true);
265 : : }
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