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6ec2e0f5 SDJ |
1 | /* intprops.h -- properties of integer types |
2 | ||
9c9d63b1 | 3 | Copyright (C) 2001-2021 Free Software Foundation, Inc. |
6ec2e0f5 SDJ |
4 | |
5 | This program is free software: you can redistribute it and/or modify it | |
6 | under the terms of the GNU General Public License as published | |
7 | by the Free Software Foundation; either version 3 of the License, or | |
8 | (at your option) any later version. | |
9 | ||
10 | This program is distributed in the hope that it will be useful, | |
11 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
12 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
13 | GNU General Public License for more details. | |
14 | ||
15 | You should have received a copy of the GNU General Public License | |
c0c3707f | 16 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
6ec2e0f5 SDJ |
17 | |
18 | /* Written by Paul Eggert. */ | |
19 | ||
20 | #ifndef _GL_INTPROPS_H | |
21 | #define _GL_INTPROPS_H | |
22 | ||
23 | #include <limits.h> | |
5e8754f9 | 24 | |
c0c3707f CB |
25 | /* Return a value with the common real type of E and V and the value of V. |
26 | Do not evaluate E. */ | |
27 | #define _GL_INT_CONVERT(e, v) ((1 ? 0 : (e)) + (v)) | |
6ec2e0f5 SDJ |
28 | |
29 | /* Act like _GL_INT_CONVERT (E, -V) but work around a bug in IRIX 6.5 cc; see | |
c0c3707f CB |
30 | <https://lists.gnu.org/r/bug-gnulib/2011-05/msg00406.html>. */ |
31 | #define _GL_INT_NEGATE_CONVERT(e, v) ((1 ? 0 : (e)) - (v)) | |
6ec2e0f5 SDJ |
32 | |
33 | /* The extra casts in the following macros work around compiler bugs, | |
34 | e.g., in Cray C 5.0.3.0. */ | |
35 | ||
36 | /* True if the arithmetic type T is an integer type. bool counts as | |
37 | an integer. */ | |
38 | #define TYPE_IS_INTEGER(t) ((t) 1.5 == 1) | |
39 | ||
40 | /* True if the real type T is signed. */ | |
41 | #define TYPE_SIGNED(t) (! ((t) 0 < (t) -1)) | |
42 | ||
43 | /* Return 1 if the real expression E, after promotion, has a | |
c0c3707f | 44 | signed or floating type. Do not evaluate E. */ |
6ec2e0f5 SDJ |
45 | #define EXPR_SIGNED(e) (_GL_INT_NEGATE_CONVERT (e, 1) < 0) |
46 | ||
47 | ||
48 | /* Minimum and maximum values for integer types and expressions. */ | |
49 | ||
50 | /* The width in bits of the integer type or expression T. | |
9c9d63b1 | 51 | Do not evaluate T. T must not be a bit-field expression. |
6ec2e0f5 SDJ |
52 | Padding bits are not supported; this is checked at compile-time below. */ |
53 | #define TYPE_WIDTH(t) (sizeof (t) * CHAR_BIT) | |
54 | ||
55 | /* The maximum and minimum values for the integer type T. */ | |
56 | #define TYPE_MINIMUM(t) ((t) ~ TYPE_MAXIMUM (t)) | |
57 | #define TYPE_MAXIMUM(t) \ | |
58 | ((t) (! TYPE_SIGNED (t) \ | |
59 | ? (t) -1 \ | |
60 | : ((((t) 1 << (TYPE_WIDTH (t) - 2)) - 1) * 2 + 1))) | |
61 | ||
62 | /* The maximum and minimum values for the type of the expression E, | |
c0c3707f | 63 | after integer promotion. E is not evaluated. */ |
6ec2e0f5 SDJ |
64 | #define _GL_INT_MINIMUM(e) \ |
65 | (EXPR_SIGNED (e) \ | |
66 | ? ~ _GL_SIGNED_INT_MAXIMUM (e) \ | |
67 | : _GL_INT_CONVERT (e, 0)) | |
68 | #define _GL_INT_MAXIMUM(e) \ | |
69 | (EXPR_SIGNED (e) \ | |
70 | ? _GL_SIGNED_INT_MAXIMUM (e) \ | |
71 | : _GL_INT_NEGATE_CONVERT (e, 1)) | |
72 | #define _GL_SIGNED_INT_MAXIMUM(e) \ | |
9c9d63b1 | 73 | (((_GL_INT_CONVERT (e, 1) << (TYPE_WIDTH (+ (e)) - 2)) - 1) * 2 + 1) |
6ec2e0f5 SDJ |
74 | |
75 | /* Work around OpenVMS incompatibility with C99. */ | |
76 | #if !defined LLONG_MAX && defined __INT64_MAX | |
77 | # define LLONG_MAX __INT64_MAX | |
78 | # define LLONG_MIN __INT64_MIN | |
79 | #endif | |
80 | ||
81 | /* This include file assumes that signed types are two's complement without | |
82 | padding bits; the above macros have undefined behavior otherwise. | |
83 | If this is a problem for you, please let us know how to fix it for your host. | |
c0c3707f | 84 | This assumption is tested by the intprops-tests module. */ |
6ec2e0f5 SDJ |
85 | |
86 | /* Does the __typeof__ keyword work? This could be done by | |
87 | 'configure', but for now it's easier to do it by hand. */ | |
88 | #if (2 <= __GNUC__ \ | |
9c9d63b1 | 89 | || (4 <= __clang_major__) \ |
6ec2e0f5 SDJ |
90 | || (1210 <= __IBMC__ && defined __IBM__TYPEOF__) \ |
91 | || (0x5110 <= __SUNPRO_C && !__STDC__)) | |
92 | # define _GL_HAVE___TYPEOF__ 1 | |
93 | #else | |
94 | # define _GL_HAVE___TYPEOF__ 0 | |
95 | #endif | |
96 | ||
97 | /* Return 1 if the integer type or expression T might be signed. Return 0 | |
9c9d63b1 PM |
98 | if it is definitely unsigned. T must not be a bit-field expression. |
99 | This macro does not evaluate its argument, and expands to an | |
100 | integer constant expression. */ | |
6ec2e0f5 SDJ |
101 | #if _GL_HAVE___TYPEOF__ |
102 | # define _GL_SIGNED_TYPE_OR_EXPR(t) TYPE_SIGNED (__typeof__ (t)) | |
103 | #else | |
104 | # define _GL_SIGNED_TYPE_OR_EXPR(t) 1 | |
105 | #endif | |
106 | ||
107 | /* Bound on length of the string representing an unsigned integer | |
108 | value representable in B bits. log10 (2.0) < 146/485. The | |
109 | smallest value of B where this bound is not tight is 2621. */ | |
110 | #define INT_BITS_STRLEN_BOUND(b) (((b) * 146 + 484) / 485) | |
111 | ||
112 | /* Bound on length of the string representing an integer type or expression T. | |
9c9d63b1 PM |
113 | T must not be a bit-field expression. |
114 | ||
6ec2e0f5 SDJ |
115 | Subtract 1 for the sign bit if T is signed, and then add 1 more for |
116 | a minus sign if needed. | |
117 | ||
c0c3707f CB |
118 | Because _GL_SIGNED_TYPE_OR_EXPR sometimes returns 1 when its argument is |
119 | unsigned, this macro may overestimate the true bound by one byte when | |
6ec2e0f5 SDJ |
120 | applied to unsigned types of size 2, 4, 16, ... bytes. */ |
121 | #define INT_STRLEN_BOUND(t) \ | |
122 | (INT_BITS_STRLEN_BOUND (TYPE_WIDTH (t) - _GL_SIGNED_TYPE_OR_EXPR (t)) \ | |
123 | + _GL_SIGNED_TYPE_OR_EXPR (t)) | |
124 | ||
125 | /* Bound on buffer size needed to represent an integer type or expression T, | |
9c9d63b1 | 126 | including the terminating null. T must not be a bit-field expression. */ |
6ec2e0f5 SDJ |
127 | #define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1) |
128 | ||
129 | ||
130 | /* Range overflow checks. | |
131 | ||
132 | The INT_<op>_RANGE_OVERFLOW macros return 1 if the corresponding C | |
133 | operators might not yield numerically correct answers due to | |
134 | arithmetic overflow. They do not rely on undefined or | |
135 | implementation-defined behavior. Their implementations are simple | |
136 | and straightforward, but they are a bit harder to use than the | |
137 | INT_<op>_OVERFLOW macros described below. | |
138 | ||
139 | Example usage: | |
140 | ||
141 | long int i = ...; | |
142 | long int j = ...; | |
143 | if (INT_MULTIPLY_RANGE_OVERFLOW (i, j, LONG_MIN, LONG_MAX)) | |
144 | printf ("multiply would overflow"); | |
145 | else | |
146 | printf ("product is %ld", i * j); | |
147 | ||
148 | Restrictions on *_RANGE_OVERFLOW macros: | |
149 | ||
150 | These macros do not check for all possible numerical problems or | |
151 | undefined or unspecified behavior: they do not check for division | |
152 | by zero, for bad shift counts, or for shifting negative numbers. | |
153 | ||
154 | These macros may evaluate their arguments zero or multiple times, | |
155 | so the arguments should not have side effects. The arithmetic | |
156 | arguments (including the MIN and MAX arguments) must be of the same | |
157 | integer type after the usual arithmetic conversions, and the type | |
158 | must have minimum value MIN and maximum MAX. Unsigned types should | |
159 | use a zero MIN of the proper type. | |
160 | ||
161 | These macros are tuned for constant MIN and MAX. For commutative | |
162 | operations such as A + B, they are also tuned for constant B. */ | |
163 | ||
164 | /* Return 1 if A + B would overflow in [MIN,MAX] arithmetic. | |
165 | See above for restrictions. */ | |
166 | #define INT_ADD_RANGE_OVERFLOW(a, b, min, max) \ | |
167 | ((b) < 0 \ | |
168 | ? (a) < (min) - (b) \ | |
169 | : (max) - (b) < (a)) | |
170 | ||
171 | /* Return 1 if A - B would overflow in [MIN,MAX] arithmetic. | |
172 | See above for restrictions. */ | |
173 | #define INT_SUBTRACT_RANGE_OVERFLOW(a, b, min, max) \ | |
174 | ((b) < 0 \ | |
175 | ? (max) + (b) < (a) \ | |
176 | : (a) < (min) + (b)) | |
177 | ||
178 | /* Return 1 if - A would overflow in [MIN,MAX] arithmetic. | |
179 | See above for restrictions. */ | |
180 | #define INT_NEGATE_RANGE_OVERFLOW(a, min, max) \ | |
181 | ((min) < 0 \ | |
182 | ? (a) < - (max) \ | |
183 | : 0 < (a)) | |
184 | ||
185 | /* Return 1 if A * B would overflow in [MIN,MAX] arithmetic. | |
186 | See above for restrictions. Avoid && and || as they tickle | |
187 | bugs in Sun C 5.11 2010/08/13 and other compilers; see | |
c0c3707f | 188 | <https://lists.gnu.org/r/bug-gnulib/2011-05/msg00401.html>. */ |
6ec2e0f5 SDJ |
189 | #define INT_MULTIPLY_RANGE_OVERFLOW(a, b, min, max) \ |
190 | ((b) < 0 \ | |
191 | ? ((a) < 0 \ | |
192 | ? (a) < (max) / (b) \ | |
193 | : (b) == -1 \ | |
194 | ? 0 \ | |
195 | : (min) / (b) < (a)) \ | |
196 | : (b) == 0 \ | |
197 | ? 0 \ | |
198 | : ((a) < 0 \ | |
199 | ? (a) < (min) / (b) \ | |
200 | : (max) / (b) < (a))) | |
201 | ||
202 | /* Return 1 if A / B would overflow in [MIN,MAX] arithmetic. | |
203 | See above for restrictions. Do not check for division by zero. */ | |
204 | #define INT_DIVIDE_RANGE_OVERFLOW(a, b, min, max) \ | |
205 | ((min) < 0 && (b) == -1 && (a) < - (max)) | |
206 | ||
207 | /* Return 1 if A % B would overflow in [MIN,MAX] arithmetic. | |
208 | See above for restrictions. Do not check for division by zero. | |
209 | Mathematically, % should never overflow, but on x86-like hosts | |
210 | INT_MIN % -1 traps, and the C standard permits this, so treat this | |
211 | as an overflow too. */ | |
212 | #define INT_REMAINDER_RANGE_OVERFLOW(a, b, min, max) \ | |
213 | INT_DIVIDE_RANGE_OVERFLOW (a, b, min, max) | |
214 | ||
215 | /* Return 1 if A << B would overflow in [MIN,MAX] arithmetic. | |
216 | See above for restrictions. Here, MIN and MAX are for A only, and B need | |
217 | not be of the same type as the other arguments. The C standard says that | |
218 | behavior is undefined for shifts unless 0 <= B < wordwidth, and that when | |
219 | A is negative then A << B has undefined behavior and A >> B has | |
220 | implementation-defined behavior, but do not check these other | |
221 | restrictions. */ | |
222 | #define INT_LEFT_SHIFT_RANGE_OVERFLOW(a, b, min, max) \ | |
223 | ((a) < 0 \ | |
224 | ? (a) < (min) >> (b) \ | |
225 | : (max) >> (b) < (a)) | |
226 | ||
c0c3707f CB |
227 | /* True if __builtin_add_overflow (A, B, P) and __builtin_sub_overflow |
228 | (A, B, P) work when P is non-null. */ | |
9c9d63b1 PM |
229 | /* __builtin_{add,sub}_overflow exists but is not reliable in GCC 5.x and 6.x, |
230 | see <https://gcc.gnu.org/bugzilla/show_bug.cgi?id=98269>. */ | |
231 | #if 7 <= __GNUC__ && !defined __ICC | |
c0c3707f CB |
232 | # define _GL_HAS_BUILTIN_ADD_OVERFLOW 1 |
233 | #elif defined __has_builtin | |
234 | # define _GL_HAS_BUILTIN_ADD_OVERFLOW __has_builtin (__builtin_add_overflow) | |
235 | #else | |
236 | # define _GL_HAS_BUILTIN_ADD_OVERFLOW 0 | |
237 | #endif | |
238 | ||
239 | /* True if __builtin_mul_overflow (A, B, P) works when P is non-null. */ | |
240 | #ifdef __clang__ | |
241 | /* Work around Clang bug <https://bugs.llvm.org/show_bug.cgi?id=16404>. */ | |
242 | # define _GL_HAS_BUILTIN_MUL_OVERFLOW 0 | |
243 | #else | |
244 | # define _GL_HAS_BUILTIN_MUL_OVERFLOW _GL_HAS_BUILTIN_ADD_OVERFLOW | |
245 | #endif | |
6ec2e0f5 | 246 | |
c0c3707f | 247 | /* True if __builtin_add_overflow_p (A, B, C) works, and similarly for |
9c9d63b1 PM |
248 | __builtin_sub_overflow_p and __builtin_mul_overflow_p. */ |
249 | #if defined __clang__ || defined __ICC | |
250 | /* Clang 11 lacks __builtin_mul_overflow_p, and even if it did it | |
251 | would presumably run afoul of Clang bug 16404. ICC 2021.1's | |
252 | __builtin_add_overflow_p etc. are not treated as integral constant | |
253 | expressions even when all arguments are. */ | |
254 | # define _GL_HAS_BUILTIN_OVERFLOW_P 0 | |
255 | #elif defined __has_builtin | |
256 | # define _GL_HAS_BUILTIN_OVERFLOW_P __has_builtin (__builtin_mul_overflow_p) | |
257 | #else | |
258 | # define _GL_HAS_BUILTIN_OVERFLOW_P (7 <= __GNUC__) | |
259 | #endif | |
6ec2e0f5 SDJ |
260 | |
261 | /* The _GL*_OVERFLOW macros have the same restrictions as the | |
262 | *_RANGE_OVERFLOW macros, except that they do not assume that operands | |
263 | (e.g., A and B) have the same type as MIN and MAX. Instead, they assume | |
264 | that the result (e.g., A + B) has that type. */ | |
265 | #if _GL_HAS_BUILTIN_OVERFLOW_P | |
266 | # define _GL_ADD_OVERFLOW(a, b, min, max) \ | |
267 | __builtin_add_overflow_p (a, b, (__typeof__ ((a) + (b))) 0) | |
268 | # define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \ | |
269 | __builtin_sub_overflow_p (a, b, (__typeof__ ((a) - (b))) 0) | |
270 | # define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \ | |
271 | __builtin_mul_overflow_p (a, b, (__typeof__ ((a) * (b))) 0) | |
272 | #else | |
273 | # define _GL_ADD_OVERFLOW(a, b, min, max) \ | |
274 | ((min) < 0 ? INT_ADD_RANGE_OVERFLOW (a, b, min, max) \ | |
275 | : (a) < 0 ? (b) <= (a) + (b) \ | |
276 | : (b) < 0 ? (a) <= (a) + (b) \ | |
277 | : (a) + (b) < (b)) | |
278 | # define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \ | |
279 | ((min) < 0 ? INT_SUBTRACT_RANGE_OVERFLOW (a, b, min, max) \ | |
280 | : (a) < 0 ? 1 \ | |
281 | : (b) < 0 ? (a) - (b) <= (a) \ | |
282 | : (a) < (b)) | |
283 | # define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \ | |
284 | (((min) == 0 && (((a) < 0 && 0 < (b)) || ((b) < 0 && 0 < (a)))) \ | |
285 | || INT_MULTIPLY_RANGE_OVERFLOW (a, b, min, max)) | |
286 | #endif | |
287 | #define _GL_DIVIDE_OVERFLOW(a, b, min, max) \ | |
288 | ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \ | |
289 | : (a) < 0 ? (b) <= (a) + (b) - 1 \ | |
290 | : (b) < 0 && (a) + (b) <= (a)) | |
291 | #define _GL_REMAINDER_OVERFLOW(a, b, min, max) \ | |
292 | ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \ | |
293 | : (a) < 0 ? (a) % (b) != ((max) - (b) + 1) % (b) \ | |
294 | : (b) < 0 && ! _GL_UNSIGNED_NEG_MULTIPLE (a, b, max)) | |
295 | ||
296 | /* Return a nonzero value if A is a mathematical multiple of B, where | |
297 | A is unsigned, B is negative, and MAX is the maximum value of A's | |
298 | type. A's type must be the same as (A % B)'s type. Normally (A % | |
299 | -B == 0) suffices, but things get tricky if -B would overflow. */ | |
300 | #define _GL_UNSIGNED_NEG_MULTIPLE(a, b, max) \ | |
301 | (((b) < -_GL_SIGNED_INT_MAXIMUM (b) \ | |
302 | ? (_GL_SIGNED_INT_MAXIMUM (b) == (max) \ | |
303 | ? (a) \ | |
304 | : (a) % (_GL_INT_CONVERT (a, _GL_SIGNED_INT_MAXIMUM (b)) + 1)) \ | |
305 | : (a) % - (b)) \ | |
306 | == 0) | |
307 | ||
308 | /* Check for integer overflow, and report low order bits of answer. | |
309 | ||
310 | The INT_<op>_OVERFLOW macros return 1 if the corresponding C operators | |
311 | might not yield numerically correct answers due to arithmetic overflow. | |
c0c3707f CB |
312 | The INT_<op>_WRAPV macros compute the low-order bits of the sum, |
313 | difference, and product of two C integers, and return 1 if these | |
314 | low-order bits are not numerically correct. | |
6ec2e0f5 SDJ |
315 | These macros work correctly on all known practical hosts, and do not rely |
316 | on undefined behavior due to signed arithmetic overflow. | |
317 | ||
318 | Example usage, assuming A and B are long int: | |
319 | ||
320 | if (INT_MULTIPLY_OVERFLOW (a, b)) | |
321 | printf ("result would overflow\n"); | |
322 | else | |
323 | printf ("result is %ld (no overflow)\n", a * b); | |
324 | ||
325 | Example usage with WRAPV flavor: | |
326 | ||
327 | long int result; | |
328 | bool overflow = INT_MULTIPLY_WRAPV (a, b, &result); | |
329 | printf ("result is %ld (%s)\n", result, | |
330 | overflow ? "after overflow" : "no overflow"); | |
331 | ||
332 | Restrictions on these macros: | |
333 | ||
334 | These macros do not check for all possible numerical problems or | |
335 | undefined or unspecified behavior: they do not check for division | |
336 | by zero, for bad shift counts, or for shifting negative numbers. | |
337 | ||
338 | These macros may evaluate their arguments zero or multiple times, so the | |
339 | arguments should not have side effects. | |
340 | ||
341 | The WRAPV macros are not constant expressions. They support only | |
c0c3707f CB |
342 | +, binary -, and *. Because the WRAPV macros convert the result, |
343 | they report overflow in different circumstances than the OVERFLOW | |
344 | macros do. | |
6ec2e0f5 | 345 | |
c0c3707f | 346 | These macros are tuned for their last input argument being a constant. |
6ec2e0f5 SDJ |
347 | |
348 | Return 1 if the integer expressions A * B, A - B, -A, A * B, A / B, | |
349 | A % B, and A << B would overflow, respectively. */ | |
350 | ||
351 | #define INT_ADD_OVERFLOW(a, b) \ | |
352 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_ADD_OVERFLOW) | |
353 | #define INT_SUBTRACT_OVERFLOW(a, b) \ | |
354 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_SUBTRACT_OVERFLOW) | |
355 | #if _GL_HAS_BUILTIN_OVERFLOW_P | |
356 | # define INT_NEGATE_OVERFLOW(a) INT_SUBTRACT_OVERFLOW (0, a) | |
357 | #else | |
358 | # define INT_NEGATE_OVERFLOW(a) \ | |
359 | INT_NEGATE_RANGE_OVERFLOW (a, _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a)) | |
360 | #endif | |
361 | #define INT_MULTIPLY_OVERFLOW(a, b) \ | |
362 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_MULTIPLY_OVERFLOW) | |
363 | #define INT_DIVIDE_OVERFLOW(a, b) \ | |
364 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_DIVIDE_OVERFLOW) | |
365 | #define INT_REMAINDER_OVERFLOW(a, b) \ | |
366 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_REMAINDER_OVERFLOW) | |
367 | #define INT_LEFT_SHIFT_OVERFLOW(a, b) \ | |
368 | INT_LEFT_SHIFT_RANGE_OVERFLOW (a, b, \ | |
369 | _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a)) | |
370 | ||
371 | /* Return 1 if the expression A <op> B would overflow, | |
372 | where OP_RESULT_OVERFLOW (A, B, MIN, MAX) does the actual test, | |
373 | assuming MIN and MAX are the minimum and maximum for the result type. | |
374 | Arguments should be free of side effects. */ | |
375 | #define _GL_BINARY_OP_OVERFLOW(a, b, op_result_overflow) \ | |
376 | op_result_overflow (a, b, \ | |
c0c3707f CB |
377 | _GL_INT_MINIMUM (_GL_INT_CONVERT (a, b)), \ |
378 | _GL_INT_MAXIMUM (_GL_INT_CONVERT (a, b))) | |
6ec2e0f5 SDJ |
379 | |
380 | /* Store the low-order bits of A + B, A - B, A * B, respectively, into *R. | |
381 | Return 1 if the result overflows. See above for restrictions. */ | |
c0c3707f CB |
382 | #if _GL_HAS_BUILTIN_ADD_OVERFLOW |
383 | # define INT_ADD_WRAPV(a, b, r) __builtin_add_overflow (a, b, r) | |
384 | # define INT_SUBTRACT_WRAPV(a, b, r) __builtin_sub_overflow (a, b, r) | |
385 | #else | |
386 | # define INT_ADD_WRAPV(a, b, r) \ | |
387 | _GL_INT_OP_WRAPV (a, b, r, +, _GL_INT_ADD_RANGE_OVERFLOW) | |
388 | # define INT_SUBTRACT_WRAPV(a, b, r) \ | |
389 | _GL_INT_OP_WRAPV (a, b, r, -, _GL_INT_SUBTRACT_RANGE_OVERFLOW) | |
390 | #endif | |
391 | #if _GL_HAS_BUILTIN_MUL_OVERFLOW | |
9c9d63b1 PM |
392 | # if ((9 < __GNUC__ + (3 <= __GNUC_MINOR__) \ |
393 | || (__GNUC__ == 8 && 4 <= __GNUC_MINOR__)) \ | |
394 | && !defined __ICC) | |
c0c3707f CB |
395 | # define INT_MULTIPLY_WRAPV(a, b, r) __builtin_mul_overflow (a, b, r) |
396 | # else | |
397 | /* Work around GCC bug 91450. */ | |
398 | # define INT_MULTIPLY_WRAPV(a, b, r) \ | |
399 | ((!_GL_SIGNED_TYPE_OR_EXPR (*(r)) && EXPR_SIGNED (a) && EXPR_SIGNED (b) \ | |
400 | && _GL_INT_MULTIPLY_RANGE_OVERFLOW (a, b, 0, (__typeof__ (*(r))) -1)) \ | |
401 | ? ((void) __builtin_mul_overflow (a, b, r), 1) \ | |
402 | : __builtin_mul_overflow (a, b, r)) | |
403 | # endif | |
404 | #else | |
405 | # define INT_MULTIPLY_WRAPV(a, b, r) \ | |
406 | _GL_INT_OP_WRAPV (a, b, r, *, _GL_INT_MULTIPLY_RANGE_OVERFLOW) | |
407 | #endif | |
6ec2e0f5 SDJ |
408 | |
409 | /* Nonzero if this compiler has GCC bug 68193 or Clang bug 25390. See: | |
410 | https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68193 | |
411 | https://llvm.org/bugs/show_bug.cgi?id=25390 | |
412 | For now, assume all versions of GCC-like compilers generate bogus | |
c0c3707f CB |
413 | warnings for _Generic. This matters only for compilers that |
414 | lack relevant builtins. */ | |
9c9d63b1 | 415 | #if __GNUC__ || defined __clang__ |
6ec2e0f5 SDJ |
416 | # define _GL__GENERIC_BOGUS 1 |
417 | #else | |
418 | # define _GL__GENERIC_BOGUS 0 | |
419 | #endif | |
420 | ||
421 | /* Store the low-order bits of A <op> B into *R, where OP specifies | |
c0c3707f CB |
422 | the operation and OVERFLOW the overflow predicate. Return 1 if the |
423 | result overflows. See above for restrictions. */ | |
424 | #if 201112 <= __STDC_VERSION__ && !_GL__GENERIC_BOGUS | |
425 | # define _GL_INT_OP_WRAPV(a, b, r, op, overflow) \ | |
6ec2e0f5 SDJ |
426 | (_Generic \ |
427 | (*(r), \ | |
428 | signed char: \ | |
c0c3707f | 429 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |
6ec2e0f5 | 430 | signed char, SCHAR_MIN, SCHAR_MAX), \ |
c0c3707f CB |
431 | unsigned char: \ |
432 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ | |
433 | unsigned char, 0, UCHAR_MAX), \ | |
6ec2e0f5 | 434 | short int: \ |
c0c3707f | 435 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |
6ec2e0f5 | 436 | short int, SHRT_MIN, SHRT_MAX), \ |
c0c3707f CB |
437 | unsigned short int: \ |
438 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ | |
439 | unsigned short int, 0, USHRT_MAX), \ | |
6ec2e0f5 SDJ |
440 | int: \ |
441 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ | |
442 | int, INT_MIN, INT_MAX), \ | |
c0c3707f CB |
443 | unsigned int: \ |
444 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ | |
445 | unsigned int, 0, UINT_MAX), \ | |
6ec2e0f5 SDJ |
446 | long int: \ |
447 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ | |
448 | long int, LONG_MIN, LONG_MAX), \ | |
c0c3707f CB |
449 | unsigned long int: \ |
450 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ | |
451 | unsigned long int, 0, ULONG_MAX), \ | |
6ec2e0f5 SDJ |
452 | long long int: \ |
453 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \ | |
c0c3707f CB |
454 | long long int, LLONG_MIN, LLONG_MAX), \ |
455 | unsigned long long int: \ | |
456 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \ | |
457 | unsigned long long int, 0, ULLONG_MAX))) | |
6ec2e0f5 | 458 | #else |
c0c3707f CB |
459 | /* Store the low-order bits of A <op> B into *R, where OP specifies |
460 | the operation and OVERFLOW the overflow predicate. If *R is | |
461 | signed, its type is ST with bounds SMIN..SMAX; otherwise its type | |
462 | is UT with bounds U..UMAX. ST and UT are narrower than int. | |
463 | Return 1 if the result overflows. See above for restrictions. */ | |
464 | # if _GL_HAVE___TYPEOF__ | |
465 | # define _GL_INT_OP_WRAPV_SMALLISH(a,b,r,op,overflow,st,smin,smax,ut,umax) \ | |
466 | (TYPE_SIGNED (__typeof__ (*(r))) \ | |
467 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, st, smin, smax) \ | |
468 | : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, ut, 0, umax)) | |
469 | # else | |
470 | # define _GL_INT_OP_WRAPV_SMALLISH(a,b,r,op,overflow,st,smin,smax,ut,umax) \ | |
471 | (overflow (a, b, smin, smax) \ | |
472 | ? (overflow (a, b, 0, umax) \ | |
473 | ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st), 1) \ | |
474 | : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st)) < 0) \ | |
475 | : (overflow (a, b, 0, umax) \ | |
476 | ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st)) >= 0 \ | |
477 | : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st), 0))) | |
478 | # endif | |
479 | ||
480 | # define _GL_INT_OP_WRAPV(a, b, r, op, overflow) \ | |
6ec2e0f5 | 481 | (sizeof *(r) == sizeof (signed char) \ |
c0c3707f CB |
482 | ? _GL_INT_OP_WRAPV_SMALLISH (a, b, r, op, overflow, \ |
483 | signed char, SCHAR_MIN, SCHAR_MAX, \ | |
484 | unsigned char, UCHAR_MAX) \ | |
6ec2e0f5 | 485 | : sizeof *(r) == sizeof (short int) \ |
c0c3707f CB |
486 | ? _GL_INT_OP_WRAPV_SMALLISH (a, b, r, op, overflow, \ |
487 | short int, SHRT_MIN, SHRT_MAX, \ | |
488 | unsigned short int, USHRT_MAX) \ | |
6ec2e0f5 | 489 | : sizeof *(r) == sizeof (int) \ |
c0c3707f CB |
490 | ? (EXPR_SIGNED (*(r)) \ |
491 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ | |
492 | int, INT_MIN, INT_MAX) \ | |
493 | : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ | |
494 | unsigned int, 0, UINT_MAX)) \ | |
6ec2e0f5 SDJ |
495 | : _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow)) |
496 | # ifdef LLONG_MAX | |
497 | # define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \ | |
498 | (sizeof *(r) == sizeof (long int) \ | |
c0c3707f CB |
499 | ? (EXPR_SIGNED (*(r)) \ |
500 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ | |
501 | long int, LONG_MIN, LONG_MAX) \ | |
502 | : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ | |
503 | unsigned long int, 0, ULONG_MAX)) \ | |
504 | : (EXPR_SIGNED (*(r)) \ | |
505 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \ | |
506 | long long int, LLONG_MIN, LLONG_MAX) \ | |
507 | : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \ | |
508 | unsigned long long int, 0, ULLONG_MAX))) | |
6ec2e0f5 SDJ |
509 | # else |
510 | # define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \ | |
c0c3707f CB |
511 | (EXPR_SIGNED (*(r)) \ |
512 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ | |
513 | long int, LONG_MIN, LONG_MAX) \ | |
514 | : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ | |
515 | unsigned long int, 0, ULONG_MAX)) | |
6ec2e0f5 SDJ |
516 | # endif |
517 | #endif | |
518 | ||
519 | /* Store the low-order bits of A <op> B into *R, where the operation | |
520 | is given by OP. Use the unsigned type UT for calculation to avoid | |
c0c3707f CB |
521 | overflow problems. *R's type is T, with extrema TMIN and TMAX. |
522 | T must be a signed integer type. Return 1 if the result overflows. */ | |
6ec2e0f5 | 523 | #define _GL_INT_OP_CALC(a, b, r, op, overflow, ut, t, tmin, tmax) \ |
c0c3707f CB |
524 | (overflow (a, b, tmin, tmax) \ |
525 | ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t), 1) \ | |
526 | : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t), 0)) | |
527 | ||
528 | /* Return the low-order bits of A <op> B, where the operation is given | |
529 | by OP. Use the unsigned type UT for calculation to avoid undefined | |
530 | behavior on signed integer overflow, and convert the result to type T. | |
531 | UT is at least as wide as T and is no narrower than unsigned int, | |
532 | T is two's complement, and there is no padding or trap representations. | |
533 | Assume that converting UT to T yields the low-order bits, as is | |
534 | done in all known two's-complement C compilers. E.g., see: | |
535 | https://gcc.gnu.org/onlinedocs/gcc/Integers-implementation.html | |
536 | ||
537 | According to the C standard, converting UT to T yields an | |
538 | implementation-defined result or signal for values outside T's | |
539 | range. However, code that works around this theoretical problem | |
540 | runs afoul of a compiler bug in Oracle Studio 12.3 x86. See: | |
541 | https://lists.gnu.org/r/bug-gnulib/2017-04/msg00049.html | |
542 | As the compiler bug is real, don't try to work around the | |
543 | theoretical problem. */ | |
544 | ||
545 | #define _GL_INT_OP_WRAPV_VIA_UNSIGNED(a, b, op, ut, t) \ | |
546 | ((t) ((ut) (a) op (ut) (b))) | |
547 | ||
548 | /* Return true if the numeric values A + B, A - B, A * B fall outside | |
549 | the range TMIN..TMAX. Arguments should be integer expressions | |
550 | without side effects. TMIN should be signed and nonpositive. | |
551 | TMAX should be positive, and should be signed unless TMIN is zero. */ | |
552 | #define _GL_INT_ADD_RANGE_OVERFLOW(a, b, tmin, tmax) \ | |
553 | ((b) < 0 \ | |
554 | ? (((tmin) \ | |
555 | ? ((EXPR_SIGNED (_GL_INT_CONVERT (a, (tmin) - (b))) || (b) < (tmin)) \ | |
556 | && (a) < (tmin) - (b)) \ | |
557 | : (a) <= -1 - (b)) \ | |
558 | || ((EXPR_SIGNED (a) ? 0 <= (a) : (tmax) < (a)) && (tmax) < (a) + (b))) \ | |
559 | : (a) < 0 \ | |
560 | ? (((tmin) \ | |
561 | ? ((EXPR_SIGNED (_GL_INT_CONVERT (b, (tmin) - (a))) || (a) < (tmin)) \ | |
562 | && (b) < (tmin) - (a)) \ | |
563 | : (b) <= -1 - (a)) \ | |
564 | || ((EXPR_SIGNED (_GL_INT_CONVERT (a, b)) || (tmax) < (b)) \ | |
565 | && (tmax) < (a) + (b))) \ | |
566 | : (tmax) < (b) || (tmax) - (b) < (a)) | |
567 | #define _GL_INT_SUBTRACT_RANGE_OVERFLOW(a, b, tmin, tmax) \ | |
568 | (((a) < 0) == ((b) < 0) \ | |
569 | ? ((a) < (b) \ | |
570 | ? !(tmin) || -1 - (tmin) < (b) - (a) - 1 \ | |
571 | : (tmax) < (a) - (b)) \ | |
572 | : (a) < 0 \ | |
573 | ? ((!EXPR_SIGNED (_GL_INT_CONVERT ((a) - (tmin), b)) && (a) - (tmin) < 0) \ | |
574 | || (a) - (tmin) < (b)) \ | |
575 | : ((! (EXPR_SIGNED (_GL_INT_CONVERT (tmax, b)) \ | |
576 | && EXPR_SIGNED (_GL_INT_CONVERT ((tmax) + (b), a))) \ | |
577 | && (tmax) <= -1 - (b)) \ | |
578 | || (tmax) + (b) < (a))) | |
579 | #define _GL_INT_MULTIPLY_RANGE_OVERFLOW(a, b, tmin, tmax) \ | |
580 | ((b) < 0 \ | |
581 | ? ((a) < 0 \ | |
582 | ? (EXPR_SIGNED (_GL_INT_CONVERT (tmax, b)) \ | |
583 | ? (a) < (tmax) / (b) \ | |
584 | : ((INT_NEGATE_OVERFLOW (b) \ | |
9c9d63b1 | 585 | ? _GL_INT_CONVERT (b, tmax) >> (TYPE_WIDTH (+ (b)) - 1) \ |
c0c3707f CB |
586 | : (tmax) / -(b)) \ |
587 | <= -1 - (a))) \ | |
588 | : INT_NEGATE_OVERFLOW (_GL_INT_CONVERT (b, tmin)) && (b) == -1 \ | |
589 | ? (EXPR_SIGNED (a) \ | |
590 | ? 0 < (a) + (tmin) \ | |
591 | : 0 < (a) && -1 - (tmin) < (a) - 1) \ | |
592 | : (tmin) / (b) < (a)) \ | |
593 | : (b) == 0 \ | |
594 | ? 0 \ | |
595 | : ((a) < 0 \ | |
596 | ? (INT_NEGATE_OVERFLOW (_GL_INT_CONVERT (a, tmin)) && (a) == -1 \ | |
597 | ? (EXPR_SIGNED (b) ? 0 < (b) + (tmin) : -1 - (tmin) < (b) - 1) \ | |
598 | : (tmin) / (a) < (b)) \ | |
599 | : (tmax) / (b) < (a))) | |
6ec2e0f5 | 600 | |
9c9d63b1 PM |
601 | /* The following macros compute A + B, A - B, and A * B, respectively. |
602 | If no overflow occurs, they set *R to the result and return 1; | |
603 | otherwise, they return 0 and may modify *R. | |
604 | ||
605 | Example usage: | |
606 | ||
607 | long int result; | |
608 | if (INT_ADD_OK (a, b, &result)) | |
609 | printf ("result is %ld\n", result); | |
610 | else | |
611 | printf ("overflow\n"); | |
612 | ||
613 | A, B, and *R should be integers; they need not be the same type, | |
614 | and they need not be all signed or all unsigned. | |
615 | ||
616 | These macros work correctly on all known practical hosts, and do not rely | |
617 | on undefined behavior due to signed arithmetic overflow. | |
618 | ||
619 | These macros are not constant expressions. | |
620 | ||
621 | These macros may evaluate their arguments zero or multiple times, so the | |
622 | arguments should not have side effects. | |
623 | ||
624 | These macros are tuned for B being a constant. */ | |
625 | ||
626 | #define INT_ADD_OK(a, b, r) ! INT_ADD_WRAPV (a, b, r) | |
627 | #define INT_SUBTRACT_OK(a, b, r) ! INT_SUBTRACT_WRAPV (a, b, r) | |
628 | #define INT_MULTIPLY_OK(a, b, r) ! INT_MULTIPLY_WRAPV (a, b, r) | |
629 | ||
6ec2e0f5 | 630 | #endif /* _GL_INTPROPS_H */ |