1 | /* intprops.h -- properties of integer types |
2 | |
3 | Copyright (C) 2001-2020 Free Software Foundation, Inc. |
4 | |
5 | This program is free software: you can redistribute it and/or modify it |
6 | under the terms of the GNU Lesser General Public License as published |
7 | by the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details. |
14 | |
15 | You should have received a copy of the GNU Lesser General Public License |
16 | along with this program. If not, see <https://www.gnu.org/licenses/>. */ |
17 | |
18 | /* Written by Paul Eggert. */ |
19 | |
20 | #ifndef _GL_INTPROPS_H |
21 | #define _GL_INTPROPS_H |
22 | |
23 | #include <limits.h> |
24 | |
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)) |
28 | |
29 | /* Act like _GL_INT_CONVERT (E, -V) but work around a bug in IRIX 6.5 cc; see |
30 | <https://lists.gnu.org/r/bug-gnulib/2011-05/msg00406.html>. */ |
31 | #define _GL_INT_NEGATE_CONVERT(e, v) ((1 ? 0 : (e)) - (v)) |
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 |
44 | signed or floating type. Do not evaluate E. */ |
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. |
51 | Do not evaluate T. |
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, |
63 | after integer promotion. E is not evaluated. */ |
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) \ |
73 | (((_GL_INT_CONVERT (e, 1) << (TYPE_WIDTH ((e) + 0) - 2)) - 1) * 2 + 1) |
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. |
84 | This assumption is tested by the intprops-tests module. */ |
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__ \ |
89 | || (1210 <= __IBMC__ && defined __IBM__TYPEOF__) \ |
90 | || (0x5110 <= __SUNPRO_C && !__STDC__)) |
91 | # define _GL_HAVE___TYPEOF__ 1 |
92 | #else |
93 | # define _GL_HAVE___TYPEOF__ 0 |
94 | #endif |
95 | |
96 | /* Return 1 if the integer type or expression T might be signed. Return 0 |
97 | if it is definitely unsigned. This macro does not evaluate its argument, |
98 | and expands to an integer constant expression. */ |
99 | #if _GL_HAVE___TYPEOF__ |
100 | # define _GL_SIGNED_TYPE_OR_EXPR(t) TYPE_SIGNED (__typeof__ (t)) |
101 | #else |
102 | # define _GL_SIGNED_TYPE_OR_EXPR(t) 1 |
103 | #endif |
104 | |
105 | /* Bound on length of the string representing an unsigned integer |
106 | value representable in B bits. log10 (2.0) < 146/485. The |
107 | smallest value of B where this bound is not tight is 2621. */ |
108 | #define INT_BITS_STRLEN_BOUND(b) (((b) * 146 + 484) / 485) |
109 | |
110 | /* Bound on length of the string representing an integer type or expression T. |
111 | Subtract 1 for the sign bit if T is signed, and then add 1 more for |
112 | a minus sign if needed. |
113 | |
114 | Because _GL_SIGNED_TYPE_OR_EXPR sometimes returns 1 when its argument is |
115 | unsigned, this macro may overestimate the true bound by one byte when |
116 | applied to unsigned types of size 2, 4, 16, ... bytes. */ |
117 | #define INT_STRLEN_BOUND(t) \ |
118 | (INT_BITS_STRLEN_BOUND (TYPE_WIDTH (t) - _GL_SIGNED_TYPE_OR_EXPR (t)) \ |
119 | + _GL_SIGNED_TYPE_OR_EXPR (t)) |
120 | |
121 | /* Bound on buffer size needed to represent an integer type or expression T, |
122 | including the terminating null. */ |
123 | #define INT_BUFSIZE_BOUND(t) (INT_STRLEN_BOUND (t) + 1) |
124 | |
125 | |
126 | /* Range overflow checks. |
127 | |
128 | The INT_<op>_RANGE_OVERFLOW macros return 1 if the corresponding C |
129 | operators might not yield numerically correct answers due to |
130 | arithmetic overflow. They do not rely on undefined or |
131 | implementation-defined behavior. Their implementations are simple |
132 | and straightforward, but they are a bit harder to use than the |
133 | INT_<op>_OVERFLOW macros described below. |
134 | |
135 | Example usage: |
136 | |
137 | long int i = ...; |
138 | long int j = ...; |
139 | if (INT_MULTIPLY_RANGE_OVERFLOW (i, j, LONG_MIN, LONG_MAX)) |
140 | printf ("multiply would overflow"); |
141 | else |
142 | printf ("product is %ld", i * j); |
143 | |
144 | Restrictions on *_RANGE_OVERFLOW macros: |
145 | |
146 | These macros do not check for all possible numerical problems or |
147 | undefined or unspecified behavior: they do not check for division |
148 | by zero, for bad shift counts, or for shifting negative numbers. |
149 | |
150 | These macros may evaluate their arguments zero or multiple times, |
151 | so the arguments should not have side effects. The arithmetic |
152 | arguments (including the MIN and MAX arguments) must be of the same |
153 | integer type after the usual arithmetic conversions, and the type |
154 | must have minimum value MIN and maximum MAX. Unsigned types should |
155 | use a zero MIN of the proper type. |
156 | |
157 | These macros are tuned for constant MIN and MAX. For commutative |
158 | operations such as A + B, they are also tuned for constant B. */ |
159 | |
160 | /* Return 1 if A + B would overflow in [MIN,MAX] arithmetic. |
161 | See above for restrictions. */ |
162 | #define INT_ADD_RANGE_OVERFLOW(a, b, min, max) \ |
163 | ((b) < 0 \ |
164 | ? (a) < (min) - (b) \ |
165 | : (max) - (b) < (a)) |
166 | |
167 | /* Return 1 if A - B would overflow in [MIN,MAX] arithmetic. |
168 | See above for restrictions. */ |
169 | #define INT_SUBTRACT_RANGE_OVERFLOW(a, b, min, max) \ |
170 | ((b) < 0 \ |
171 | ? (max) + (b) < (a) \ |
172 | : (a) < (min) + (b)) |
173 | |
174 | /* Return 1 if - A would overflow in [MIN,MAX] arithmetic. |
175 | See above for restrictions. */ |
176 | #define INT_NEGATE_RANGE_OVERFLOW(a, min, max) \ |
177 | ((min) < 0 \ |
178 | ? (a) < - (max) \ |
179 | : 0 < (a)) |
180 | |
181 | /* Return 1 if A * B would overflow in [MIN,MAX] arithmetic. |
182 | See above for restrictions. Avoid && and || as they tickle |
183 | bugs in Sun C 5.11 2010/08/13 and other compilers; see |
184 | <https://lists.gnu.org/r/bug-gnulib/2011-05/msg00401.html>. */ |
185 | #define INT_MULTIPLY_RANGE_OVERFLOW(a, b, min, max) \ |
186 | ((b) < 0 \ |
187 | ? ((a) < 0 \ |
188 | ? (a) < (max) / (b) \ |
189 | : (b) == -1 \ |
190 | ? 0 \ |
191 | : (min) / (b) < (a)) \ |
192 | : (b) == 0 \ |
193 | ? 0 \ |
194 | : ((a) < 0 \ |
195 | ? (a) < (min) / (b) \ |
196 | : (max) / (b) < (a))) |
197 | |
198 | /* Return 1 if A / B would overflow in [MIN,MAX] arithmetic. |
199 | See above for restrictions. Do not check for division by zero. */ |
200 | #define INT_DIVIDE_RANGE_OVERFLOW(a, b, min, max) \ |
201 | ((min) < 0 && (b) == -1 && (a) < - (max)) |
202 | |
203 | /* Return 1 if A % B would overflow in [MIN,MAX] arithmetic. |
204 | See above for restrictions. Do not check for division by zero. |
205 | Mathematically, % should never overflow, but on x86-like hosts |
206 | INT_MIN % -1 traps, and the C standard permits this, so treat this |
207 | as an overflow too. */ |
208 | #define INT_REMAINDER_RANGE_OVERFLOW(a, b, min, max) \ |
209 | INT_DIVIDE_RANGE_OVERFLOW (a, b, min, max) |
210 | |
211 | /* Return 1 if A << B would overflow in [MIN,MAX] arithmetic. |
212 | See above for restrictions. Here, MIN and MAX are for A only, and B need |
213 | not be of the same type as the other arguments. The C standard says that |
214 | behavior is undefined for shifts unless 0 <= B < wordwidth, and that when |
215 | A is negative then A << B has undefined behavior and A >> B has |
216 | implementation-defined behavior, but do not check these other |
217 | restrictions. */ |
218 | #define INT_LEFT_SHIFT_RANGE_OVERFLOW(a, b, min, max) \ |
219 | ((a) < 0 \ |
220 | ? (a) < (min) >> (b) \ |
221 | : (max) >> (b) < (a)) |
222 | |
223 | /* True if __builtin_add_overflow (A, B, P) and __builtin_sub_overflow |
224 | (A, B, P) work when P is non-null. */ |
225 | #if 5 <= __GNUC__ && !defined __ICC |
226 | # define _GL_HAS_BUILTIN_ADD_OVERFLOW 1 |
227 | #elif defined __has_builtin |
228 | # define _GL_HAS_BUILTIN_ADD_OVERFLOW __has_builtin (__builtin_add_overflow) |
229 | #else |
230 | # define _GL_HAS_BUILTIN_ADD_OVERFLOW 0 |
231 | #endif |
232 | |
233 | /* True if __builtin_mul_overflow (A, B, P) works when P is non-null. */ |
234 | #ifdef __clang__ |
235 | /* Work around Clang bug <https://bugs.llvm.org/show_bug.cgi?id=16404>. */ |
236 | # define _GL_HAS_BUILTIN_MUL_OVERFLOW 0 |
237 | #else |
238 | # define _GL_HAS_BUILTIN_MUL_OVERFLOW _GL_HAS_BUILTIN_ADD_OVERFLOW |
239 | #endif |
240 | |
241 | /* True if __builtin_add_overflow_p (A, B, C) works, and similarly for |
242 | __builtin_mul_overflow_p and __builtin_mul_overflow_p. */ |
243 | #define _GL_HAS_BUILTIN_OVERFLOW_P (7 <= __GNUC__) |
244 | |
245 | /* The _GL*_OVERFLOW macros have the same restrictions as the |
246 | *_RANGE_OVERFLOW macros, except that they do not assume that operands |
247 | (e.g., A and B) have the same type as MIN and MAX. Instead, they assume |
248 | that the result (e.g., A + B) has that type. */ |
249 | #if _GL_HAS_BUILTIN_OVERFLOW_P |
250 | # define _GL_ADD_OVERFLOW(a, b, min, max) \ |
251 | __builtin_add_overflow_p (a, b, (__typeof__ ((a) + (b))) 0) |
252 | # define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \ |
253 | __builtin_sub_overflow_p (a, b, (__typeof__ ((a) - (b))) 0) |
254 | # define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \ |
255 | __builtin_mul_overflow_p (a, b, (__typeof__ ((a) * (b))) 0) |
256 | #else |
257 | # define _GL_ADD_OVERFLOW(a, b, min, max) \ |
258 | ((min) < 0 ? INT_ADD_RANGE_OVERFLOW (a, b, min, max) \ |
259 | : (a) < 0 ? (b) <= (a) + (b) \ |
260 | : (b) < 0 ? (a) <= (a) + (b) \ |
261 | : (a) + (b) < (b)) |
262 | # define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \ |
263 | ((min) < 0 ? INT_SUBTRACT_RANGE_OVERFLOW (a, b, min, max) \ |
264 | : (a) < 0 ? 1 \ |
265 | : (b) < 0 ? (a) - (b) <= (a) \ |
266 | : (a) < (b)) |
267 | # define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \ |
268 | (((min) == 0 && (((a) < 0 && 0 < (b)) || ((b) < 0 && 0 < (a)))) \ |
269 | || INT_MULTIPLY_RANGE_OVERFLOW (a, b, min, max)) |
270 | #endif |
271 | #define _GL_DIVIDE_OVERFLOW(a, b, min, max) \ |
272 | ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \ |
273 | : (a) < 0 ? (b) <= (a) + (b) - 1 \ |
274 | : (b) < 0 && (a) + (b) <= (a)) |
275 | #define _GL_REMAINDER_OVERFLOW(a, b, min, max) \ |
276 | ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \ |
277 | : (a) < 0 ? (a) % (b) != ((max) - (b) + 1) % (b) \ |
278 | : (b) < 0 && ! _GL_UNSIGNED_NEG_MULTIPLE (a, b, max)) |
279 | |
280 | /* Return a nonzero value if A is a mathematical multiple of B, where |
281 | A is unsigned, B is negative, and MAX is the maximum value of A's |
282 | type. A's type must be the same as (A % B)'s type. Normally (A % |
283 | -B == 0) suffices, but things get tricky if -B would overflow. */ |
284 | #define _GL_UNSIGNED_NEG_MULTIPLE(a, b, max) \ |
285 | (((b) < -_GL_SIGNED_INT_MAXIMUM (b) \ |
286 | ? (_GL_SIGNED_INT_MAXIMUM (b) == (max) \ |
287 | ? (a) \ |
288 | : (a) % (_GL_INT_CONVERT (a, _GL_SIGNED_INT_MAXIMUM (b)) + 1)) \ |
289 | : (a) % - (b)) \ |
290 | == 0) |
291 | |
292 | /* Check for integer overflow, and report low order bits of answer. |
293 | |
294 | The INT_<op>_OVERFLOW macros return 1 if the corresponding C operators |
295 | might not yield numerically correct answers due to arithmetic overflow. |
296 | The INT_<op>_WRAPV macros compute the low-order bits of the sum, |
297 | difference, and product of two C integers, and return 1 if these |
298 | low-order bits are not numerically correct. |
299 | These macros work correctly on all known practical hosts, and do not rely |
300 | on undefined behavior due to signed arithmetic overflow. |
301 | |
302 | Example usage, assuming A and B are long int: |
303 | |
304 | if (INT_MULTIPLY_OVERFLOW (a, b)) |
305 | printf ("result would overflow\n"); |
306 | else |
307 | printf ("result is %ld (no overflow)\n", a * b); |
308 | |
309 | Example usage with WRAPV flavor: |
310 | |
311 | long int result; |
312 | bool overflow = INT_MULTIPLY_WRAPV (a, b, &result); |
313 | printf ("result is %ld (%s)\n", result, |
314 | overflow ? "after overflow" : "no overflow"); |
315 | |
316 | Restrictions on these macros: |
317 | |
318 | These macros do not check for all possible numerical problems or |
319 | undefined or unspecified behavior: they do not check for division |
320 | by zero, for bad shift counts, or for shifting negative numbers. |
321 | |
322 | These macros may evaluate their arguments zero or multiple times, so the |
323 | arguments should not have side effects. |
324 | |
325 | The WRAPV macros are not constant expressions. They support only |
326 | +, binary -, and *. Because the WRAPV macros convert the result, |
327 | they report overflow in different circumstances than the OVERFLOW |
328 | macros do. |
329 | |
330 | These macros are tuned for their last input argument being a constant. |
331 | |
332 | Return 1 if the integer expressions A * B, A - B, -A, A * B, A / B, |
333 | A % B, and A << B would overflow, respectively. */ |
334 | |
335 | #define INT_ADD_OVERFLOW(a, b) \ |
336 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_ADD_OVERFLOW) |
337 | #define INT_SUBTRACT_OVERFLOW(a, b) \ |
338 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_SUBTRACT_OVERFLOW) |
339 | #if _GL_HAS_BUILTIN_OVERFLOW_P |
340 | # define INT_NEGATE_OVERFLOW(a) INT_SUBTRACT_OVERFLOW (0, a) |
341 | #else |
342 | # define INT_NEGATE_OVERFLOW(a) \ |
343 | INT_NEGATE_RANGE_OVERFLOW (a, _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a)) |
344 | #endif |
345 | #define INT_MULTIPLY_OVERFLOW(a, b) \ |
346 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_MULTIPLY_OVERFLOW) |
347 | #define INT_DIVIDE_OVERFLOW(a, b) \ |
348 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_DIVIDE_OVERFLOW) |
349 | #define INT_REMAINDER_OVERFLOW(a, b) \ |
350 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_REMAINDER_OVERFLOW) |
351 | #define INT_LEFT_SHIFT_OVERFLOW(a, b) \ |
352 | INT_LEFT_SHIFT_RANGE_OVERFLOW (a, b, \ |
353 | _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a)) |
354 | |
355 | /* Return 1 if the expression A <op> B would overflow, |
356 | where OP_RESULT_OVERFLOW (A, B, MIN, MAX) does the actual test, |
357 | assuming MIN and MAX are the minimum and maximum for the result type. |
358 | Arguments should be free of side effects. */ |
359 | #define _GL_BINARY_OP_OVERFLOW(a, b, op_result_overflow) \ |
360 | op_result_overflow (a, b, \ |
361 | _GL_INT_MINIMUM (_GL_INT_CONVERT (a, b)), \ |
362 | _GL_INT_MAXIMUM (_GL_INT_CONVERT (a, b))) |
363 | |
364 | /* Store the low-order bits of A + B, A - B, A * B, respectively, into *R. |
365 | Return 1 if the result overflows. See above for restrictions. */ |
366 | #if _GL_HAS_BUILTIN_ADD_OVERFLOW |
367 | # define INT_ADD_WRAPV(a, b, r) __builtin_add_overflow (a, b, r) |
368 | # define INT_SUBTRACT_WRAPV(a, b, r) __builtin_sub_overflow (a, b, r) |
369 | #else |
370 | # define INT_ADD_WRAPV(a, b, r) \ |
371 | _GL_INT_OP_WRAPV (a, b, r, +, _GL_INT_ADD_RANGE_OVERFLOW) |
372 | # define INT_SUBTRACT_WRAPV(a, b, r) \ |
373 | _GL_INT_OP_WRAPV (a, b, r, -, _GL_INT_SUBTRACT_RANGE_OVERFLOW) |
374 | #endif |
375 | #if _GL_HAS_BUILTIN_MUL_OVERFLOW |
376 | /* Work around GCC bug 91450. */ |
377 | # define INT_MULTIPLY_WRAPV(a, b, r) \ |
378 | ((!_GL_SIGNED_TYPE_OR_EXPR (*(r)) && EXPR_SIGNED (a) && EXPR_SIGNED (b) \ |
379 | && _GL_INT_MULTIPLY_RANGE_OVERFLOW (a, b, 0, (__typeof__ (*(r))) -1)) \ |
380 | ? ((void) __builtin_mul_overflow (a, b, r), 1) \ |
381 | : __builtin_mul_overflow (a, b, r)) |
382 | #else |
383 | # define INT_MULTIPLY_WRAPV(a, b, r) \ |
384 | _GL_INT_OP_WRAPV (a, b, r, *, _GL_INT_MULTIPLY_RANGE_OVERFLOW) |
385 | #endif |
386 | |
387 | /* Nonzero if this compiler has GCC bug 68193 or Clang bug 25390. See: |
388 | https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68193 |
389 | https://llvm.org/bugs/show_bug.cgi?id=25390 |
390 | For now, assume all versions of GCC-like compilers generate bogus |
391 | warnings for _Generic. This matters only for compilers that |
392 | lack relevant builtins. */ |
393 | #if __GNUC__ |
394 | # define _GL__GENERIC_BOGUS 1 |
395 | #else |
396 | # define _GL__GENERIC_BOGUS 0 |
397 | #endif |
398 | |
399 | /* Store the low-order bits of A <op> B into *R, where OP specifies |
400 | the operation and OVERFLOW the overflow predicate. Return 1 if the |
401 | result overflows. See above for restrictions. */ |
402 | #if 201112 <= __STDC_VERSION__ && !_GL__GENERIC_BOGUS |
403 | # define _GL_INT_OP_WRAPV(a, b, r, op, overflow) \ |
404 | (_Generic \ |
405 | (*(r), \ |
406 | signed char: \ |
407 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |
408 | signed char, SCHAR_MIN, SCHAR_MAX), \ |
409 | unsigned char: \ |
410 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |
411 | unsigned char, 0, UCHAR_MAX), \ |
412 | short int: \ |
413 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |
414 | short int, SHRT_MIN, SHRT_MAX), \ |
415 | unsigned short int: \ |
416 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |
417 | unsigned short int, 0, USHRT_MAX), \ |
418 | int: \ |
419 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |
420 | int, INT_MIN, INT_MAX), \ |
421 | unsigned int: \ |
422 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |
423 | unsigned int, 0, UINT_MAX), \ |
424 | long int: \ |
425 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ |
426 | long int, LONG_MIN, LONG_MAX), \ |
427 | unsigned long int: \ |
428 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ |
429 | unsigned long int, 0, ULONG_MAX), \ |
430 | long long int: \ |
431 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \ |
432 | long long int, LLONG_MIN, LLONG_MAX), \ |
433 | unsigned long long int: \ |
434 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \ |
435 | unsigned long long int, 0, ULLONG_MAX))) |
436 | #else |
437 | /* Store the low-order bits of A <op> B into *R, where OP specifies |
438 | the operation and OVERFLOW the overflow predicate. If *R is |
439 | signed, its type is ST with bounds SMIN..SMAX; otherwise its type |
440 | is UT with bounds U..UMAX. ST and UT are narrower than int. |
441 | Return 1 if the result overflows. See above for restrictions. */ |
442 | # if _GL_HAVE___TYPEOF__ |
443 | # define _GL_INT_OP_WRAPV_SMALLISH(a,b,r,op,overflow,st,smin,smax,ut,umax) \ |
444 | (TYPE_SIGNED (__typeof__ (*(r))) \ |
445 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, st, smin, smax) \ |
446 | : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, ut, 0, umax)) |
447 | # else |
448 | # define _GL_INT_OP_WRAPV_SMALLISH(a,b,r,op,overflow,st,smin,smax,ut,umax) \ |
449 | (overflow (a, b, smin, smax) \ |
450 | ? (overflow (a, b, 0, umax) \ |
451 | ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st), 1) \ |
452 | : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st)) < 0) \ |
453 | : (overflow (a, b, 0, umax) \ |
454 | ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st)) >= 0 \ |
455 | : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a,b,op,unsigned,st), 0))) |
456 | # endif |
457 | |
458 | # define _GL_INT_OP_WRAPV(a, b, r, op, overflow) \ |
459 | (sizeof *(r) == sizeof (signed char) \ |
460 | ? _GL_INT_OP_WRAPV_SMALLISH (a, b, r, op, overflow, \ |
461 | signed char, SCHAR_MIN, SCHAR_MAX, \ |
462 | unsigned char, UCHAR_MAX) \ |
463 | : sizeof *(r) == sizeof (short int) \ |
464 | ? _GL_INT_OP_WRAPV_SMALLISH (a, b, r, op, overflow, \ |
465 | short int, SHRT_MIN, SHRT_MAX, \ |
466 | unsigned short int, USHRT_MAX) \ |
467 | : sizeof *(r) == sizeof (int) \ |
468 | ? (EXPR_SIGNED (*(r)) \ |
469 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |
470 | int, INT_MIN, INT_MAX) \ |
471 | : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |
472 | unsigned int, 0, UINT_MAX)) \ |
473 | : _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow)) |
474 | # ifdef LLONG_MAX |
475 | # define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \ |
476 | (sizeof *(r) == sizeof (long int) \ |
477 | ? (EXPR_SIGNED (*(r)) \ |
478 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ |
479 | long int, LONG_MIN, LONG_MAX) \ |
480 | : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ |
481 | unsigned long int, 0, ULONG_MAX)) \ |
482 | : (EXPR_SIGNED (*(r)) \ |
483 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \ |
484 | long long int, LLONG_MIN, LLONG_MAX) \ |
485 | : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \ |
486 | unsigned long long int, 0, ULLONG_MAX))) |
487 | # else |
488 | # define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \ |
489 | (EXPR_SIGNED (*(r)) \ |
490 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ |
491 | long int, LONG_MIN, LONG_MAX) \ |
492 | : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ |
493 | unsigned long int, 0, ULONG_MAX)) |
494 | # endif |
495 | #endif |
496 | |
497 | /* Store the low-order bits of A <op> B into *R, where the operation |
498 | is given by OP. Use the unsigned type UT for calculation to avoid |
499 | overflow problems. *R's type is T, with extrema TMIN and TMAX. |
500 | T must be a signed integer type. Return 1 if the result overflows. */ |
501 | #define _GL_INT_OP_CALC(a, b, r, op, overflow, ut, t, tmin, tmax) \ |
502 | (overflow (a, b, tmin, tmax) \ |
503 | ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t), 1) \ |
504 | : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t), 0)) |
505 | |
506 | /* Return the low-order bits of A <op> B, where the operation is given |
507 | by OP. Use the unsigned type UT for calculation to avoid undefined |
508 | behavior on signed integer overflow, and convert the result to type T. |
509 | UT is at least as wide as T and is no narrower than unsigned int, |
510 | T is two's complement, and there is no padding or trap representations. |
511 | Assume that converting UT to T yields the low-order bits, as is |
512 | done in all known two's-complement C compilers. E.g., see: |
513 | https://gcc.gnu.org/onlinedocs/gcc/Integers-implementation.html |
514 | |
515 | According to the C standard, converting UT to T yields an |
516 | implementation-defined result or signal for values outside T's |
517 | range. However, code that works around this theoretical problem |
518 | runs afoul of a compiler bug in Oracle Studio 12.3 x86. See: |
519 | https://lists.gnu.org/r/bug-gnulib/2017-04/msg00049.html |
520 | As the compiler bug is real, don't try to work around the |
521 | theoretical problem. */ |
522 | |
523 | #define _GL_INT_OP_WRAPV_VIA_UNSIGNED(a, b, op, ut, t) \ |
524 | ((t) ((ut) (a) op (ut) (b))) |
525 | |
526 | /* Return true if the numeric values A + B, A - B, A * B fall outside |
527 | the range TMIN..TMAX. Arguments should be integer expressions |
528 | without side effects. TMIN should be signed and nonpositive. |
529 | TMAX should be positive, and should be signed unless TMIN is zero. */ |
530 | #define _GL_INT_ADD_RANGE_OVERFLOW(a, b, tmin, tmax) \ |
531 | ((b) < 0 \ |
532 | ? (((tmin) \ |
533 | ? ((EXPR_SIGNED (_GL_INT_CONVERT (a, (tmin) - (b))) || (b) < (tmin)) \ |
534 | && (a) < (tmin) - (b)) \ |
535 | : (a) <= -1 - (b)) \ |
536 | || ((EXPR_SIGNED (a) ? 0 <= (a) : (tmax) < (a)) && (tmax) < (a) + (b))) \ |
537 | : (a) < 0 \ |
538 | ? (((tmin) \ |
539 | ? ((EXPR_SIGNED (_GL_INT_CONVERT (b, (tmin) - (a))) || (a) < (tmin)) \ |
540 | && (b) < (tmin) - (a)) \ |
541 | : (b) <= -1 - (a)) \ |
542 | || ((EXPR_SIGNED (_GL_INT_CONVERT (a, b)) || (tmax) < (b)) \ |
543 | && (tmax) < (a) + (b))) \ |
544 | : (tmax) < (b) || (tmax) - (b) < (a)) |
545 | #define _GL_INT_SUBTRACT_RANGE_OVERFLOW(a, b, tmin, tmax) \ |
546 | (((a) < 0) == ((b) < 0) \ |
547 | ? ((a) < (b) \ |
548 | ? !(tmin) || -1 - (tmin) < (b) - (a) - 1 \ |
549 | : (tmax) < (a) - (b)) \ |
550 | : (a) < 0 \ |
551 | ? ((!EXPR_SIGNED (_GL_INT_CONVERT ((a) - (tmin), b)) && (a) - (tmin) < 0) \ |
552 | || (a) - (tmin) < (b)) \ |
553 | : ((! (EXPR_SIGNED (_GL_INT_CONVERT (tmax, b)) \ |
554 | && EXPR_SIGNED (_GL_INT_CONVERT ((tmax) + (b), a))) \ |
555 | && (tmax) <= -1 - (b)) \ |
556 | || (tmax) + (b) < (a))) |
557 | #define _GL_INT_MULTIPLY_RANGE_OVERFLOW(a, b, tmin, tmax) \ |
558 | ((b) < 0 \ |
559 | ? ((a) < 0 \ |
560 | ? (EXPR_SIGNED (_GL_INT_CONVERT (tmax, b)) \ |
561 | ? (a) < (tmax) / (b) \ |
562 | : ((INT_NEGATE_OVERFLOW (b) \ |
563 | ? _GL_INT_CONVERT (b, tmax) >> (TYPE_WIDTH (b) - 1) \ |
564 | : (tmax) / -(b)) \ |
565 | <= -1 - (a))) \ |
566 | : INT_NEGATE_OVERFLOW (_GL_INT_CONVERT (b, tmin)) && (b) == -1 \ |
567 | ? (EXPR_SIGNED (a) \ |
568 | ? 0 < (a) + (tmin) \ |
569 | : 0 < (a) && -1 - (tmin) < (a) - 1) \ |
570 | : (tmin) / (b) < (a)) \ |
571 | : (b) == 0 \ |
572 | ? 0 \ |
573 | : ((a) < 0 \ |
574 | ? (INT_NEGATE_OVERFLOW (_GL_INT_CONVERT (a, tmin)) && (a) == -1 \ |
575 | ? (EXPR_SIGNED (b) ? 0 < (b) + (tmin) : -1 - (tmin) < (b) - 1) \ |
576 | : (tmin) / (a) < (b)) \ |
577 | : (tmax) / (b) < (a))) |
578 | |
579 | #endif /* _GL_INTPROPS_H */ |
580 | |