1 | /* intprops.h -- properties of integer types |
---|---|

2 | |

3 | Copyright (C) 2001-2019 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 0 when its argument is |

115 | signed, 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) works when P is non-null. */ |

224 | #if 5 <= __GNUC__ && !defined __ICC |

225 | # define _GL_HAS_BUILTIN_OVERFLOW 1 |

226 | #else |

227 | # define _GL_HAS_BUILTIN_OVERFLOW 0 |

228 | #endif |

229 | |

230 | /* True if __builtin_add_overflow_p (A, B, C) works. */ |

231 | #define _GL_HAS_BUILTIN_OVERFLOW_P (7 <= __GNUC__) |

232 | |

233 | /* The _GL*_OVERFLOW macros have the same restrictions as the |

234 | *_RANGE_OVERFLOW macros, except that they do not assume that operands |

235 | (e.g., A and B) have the same type as MIN and MAX. Instead, they assume |

236 | that the result (e.g., A + B) has that type. */ |

237 | #if _GL_HAS_BUILTIN_OVERFLOW_P |

238 | # define _GL_ADD_OVERFLOW(a, b, min, max) \ |

239 | __builtin_add_overflow_p (a, b, (__typeof__ ((a) + (b))) 0) |

240 | # define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \ |

241 | __builtin_sub_overflow_p (a, b, (__typeof__ ((a) - (b))) 0) |

242 | # define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \ |

243 | __builtin_mul_overflow_p (a, b, (__typeof__ ((a) * (b))) 0) |

244 | #else |

245 | # define _GL_ADD_OVERFLOW(a, b, min, max) \ |

246 | ((min) < 0 ? INT_ADD_RANGE_OVERFLOW (a, b, min, max) \ |

247 | : (a) < 0 ? (b) <= (a) + (b) \ |

248 | : (b) < 0 ? (a) <= (a) + (b) \ |

249 | : (a) + (b) < (b)) |

250 | # define _GL_SUBTRACT_OVERFLOW(a, b, min, max) \ |

251 | ((min) < 0 ? INT_SUBTRACT_RANGE_OVERFLOW (a, b, min, max) \ |

252 | : (a) < 0 ? 1 \ |

253 | : (b) < 0 ? (a) - (b) <= (a) \ |

254 | : (a) < (b)) |

255 | # define _GL_MULTIPLY_OVERFLOW(a, b, min, max) \ |

256 | (((min) == 0 && (((a) < 0 && 0 < (b)) || ((b) < 0 && 0 < (a)))) \ |

257 | || INT_MULTIPLY_RANGE_OVERFLOW (a, b, min, max)) |

258 | #endif |

259 | #define _GL_DIVIDE_OVERFLOW(a, b, min, max) \ |

260 | ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \ |

261 | : (a) < 0 ? (b) <= (a) + (b) - 1 \ |

262 | : (b) < 0 && (a) + (b) <= (a)) |

263 | #define _GL_REMAINDER_OVERFLOW(a, b, min, max) \ |

264 | ((min) < 0 ? (b) == _GL_INT_NEGATE_CONVERT (min, 1) && (a) < - (max) \ |

265 | : (a) < 0 ? (a) % (b) != ((max) - (b) + 1) % (b) \ |

266 | : (b) < 0 && ! _GL_UNSIGNED_NEG_MULTIPLE (a, b, max)) |

267 | |

268 | /* Return a nonzero value if A is a mathematical multiple of B, where |

269 | A is unsigned, B is negative, and MAX is the maximum value of A's |

270 | type. A's type must be the same as (A % B)'s type. Normally (A % |

271 | -B == 0) suffices, but things get tricky if -B would overflow. */ |

272 | #define _GL_UNSIGNED_NEG_MULTIPLE(a, b, max) \ |

273 | (((b) < -_GL_SIGNED_INT_MAXIMUM (b) \ |

274 | ? (_GL_SIGNED_INT_MAXIMUM (b) == (max) \ |

275 | ? (a) \ |

276 | : (a) % (_GL_INT_CONVERT (a, _GL_SIGNED_INT_MAXIMUM (b)) + 1)) \ |

277 | : (a) % - (b)) \ |

278 | == 0) |

279 | |

280 | /* Check for integer overflow, and report low order bits of answer. |

281 | |

282 | The INT_<op>_OVERFLOW macros return 1 if the corresponding C operators |

283 | might not yield numerically correct answers due to arithmetic overflow. |

284 | The INT_<op>_WRAPV macros also store the low-order bits of the answer. |

285 | These macros work correctly on all known practical hosts, and do not rely |

286 | on undefined behavior due to signed arithmetic overflow. |

287 | |

288 | Example usage, assuming A and B are long int: |

289 | |

290 | if (INT_MULTIPLY_OVERFLOW (a, b)) |

291 | printf ("result would overflow\n"); |

292 | else |

293 | printf ("result is %ld (no overflow)\n", a * b); |

294 | |

295 | Example usage with WRAPV flavor: |

296 | |

297 | long int result; |

298 | bool overflow = INT_MULTIPLY_WRAPV (a, b, &result); |

299 | printf ("result is %ld (%s)\n", result, |

300 | overflow ? "after overflow" : "no overflow"); |

301 | |

302 | Restrictions on these macros: |

303 | |

304 | These macros do not check for all possible numerical problems or |

305 | undefined or unspecified behavior: they do not check for division |

306 | by zero, for bad shift counts, or for shifting negative numbers. |

307 | |

308 | These macros may evaluate their arguments zero or multiple times, so the |

309 | arguments should not have side effects. |

310 | |

311 | The WRAPV macros are not constant expressions. They support only |

312 | +, binary -, and *. The result type must be signed. |

313 | |

314 | These macros are tuned for their last argument being a constant. |

315 | |

316 | Return 1 if the integer expressions A * B, A - B, -A, A * B, A / B, |

317 | A % B, and A << B would overflow, respectively. */ |

318 | |

319 | #define INT_ADD_OVERFLOW(a, b) \ |

320 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_ADD_OVERFLOW) |

321 | #define INT_SUBTRACT_OVERFLOW(a, b) \ |

322 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_SUBTRACT_OVERFLOW) |

323 | #if _GL_HAS_BUILTIN_OVERFLOW_P |

324 | # define INT_NEGATE_OVERFLOW(a) INT_SUBTRACT_OVERFLOW (0, a) |

325 | #else |

326 | # define INT_NEGATE_OVERFLOW(a) \ |

327 | INT_NEGATE_RANGE_OVERFLOW (a, _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a)) |

328 | #endif |

329 | #define INT_MULTIPLY_OVERFLOW(a, b) \ |

330 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_MULTIPLY_OVERFLOW) |

331 | #define INT_DIVIDE_OVERFLOW(a, b) \ |

332 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_DIVIDE_OVERFLOW) |

333 | #define INT_REMAINDER_OVERFLOW(a, b) \ |

334 | _GL_BINARY_OP_OVERFLOW (a, b, _GL_REMAINDER_OVERFLOW) |

335 | #define INT_LEFT_SHIFT_OVERFLOW(a, b) \ |

336 | INT_LEFT_SHIFT_RANGE_OVERFLOW (a, b, \ |

337 | _GL_INT_MINIMUM (a), _GL_INT_MAXIMUM (a)) |

338 | |

339 | /* Return 1 if the expression A <op> B would overflow, |

340 | where OP_RESULT_OVERFLOW (A, B, MIN, MAX) does the actual test, |

341 | assuming MIN and MAX are the minimum and maximum for the result type. |

342 | Arguments should be free of side effects. */ |

343 | #define _GL_BINARY_OP_OVERFLOW(a, b, op_result_overflow) \ |

344 | op_result_overflow (a, b, \ |

345 | _GL_INT_MINIMUM (_GL_INT_CONVERT (a, b)), \ |

346 | _GL_INT_MAXIMUM (_GL_INT_CONVERT (a, b))) |

347 | |

348 | /* Store the low-order bits of A + B, A - B, A * B, respectively, into *R. |

349 | Return 1 if the result overflows. See above for restrictions. */ |

350 | #define INT_ADD_WRAPV(a, b, r) \ |

351 | _GL_INT_OP_WRAPV (a, b, r, +, __builtin_add_overflow, INT_ADD_OVERFLOW) |

352 | #define INT_SUBTRACT_WRAPV(a, b, r) \ |

353 | _GL_INT_OP_WRAPV (a, b, r, -, __builtin_sub_overflow, INT_SUBTRACT_OVERFLOW) |

354 | #define INT_MULTIPLY_WRAPV(a, b, r) \ |

355 | _GL_INT_OP_WRAPV (a, b, r, *, __builtin_mul_overflow, INT_MULTIPLY_OVERFLOW) |

356 | |

357 | /* Nonzero if this compiler has GCC bug 68193 or Clang bug 25390. See: |

358 | https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68193 |

359 | https://llvm.org/bugs/show_bug.cgi?id=25390 |

360 | For now, assume all versions of GCC-like compilers generate bogus |

361 | warnings for _Generic. This matters only for older compilers that |

362 | lack __builtin_add_overflow. */ |

363 | #if __GNUC__ |

364 | # define _GL__GENERIC_BOGUS 1 |

365 | #else |

366 | # define _GL__GENERIC_BOGUS 0 |

367 | #endif |

368 | |

369 | /* Store the low-order bits of A <op> B into *R, where OP specifies |

370 | the operation. BUILTIN is the builtin operation, and OVERFLOW the |

371 | overflow predicate. Return 1 if the result overflows. See above |

372 | for restrictions. */ |

373 | #if _GL_HAS_BUILTIN_OVERFLOW |

374 | # define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) builtin (a, b, r) |

375 | #elif 201112 <= __STDC_VERSION__ && !_GL__GENERIC_BOGUS |

376 | # define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \ |

377 | (_Generic \ |

378 | (*(r), \ |

379 | signed char: \ |

380 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |

381 | signed char, SCHAR_MIN, SCHAR_MAX), \ |

382 | short int: \ |

383 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |

384 | short int, SHRT_MIN, SHRT_MAX), \ |

385 | int: \ |

386 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |

387 | int, INT_MIN, INT_MAX), \ |

388 | long int: \ |

389 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ |

390 | long int, LONG_MIN, LONG_MAX), \ |

391 | long long int: \ |

392 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \ |

393 | long long int, LLONG_MIN, LLONG_MAX))) |

394 | #else |

395 | # define _GL_INT_OP_WRAPV(a, b, r, op, builtin, overflow) \ |

396 | (sizeof *(r) == sizeof (signed char) \ |

397 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |

398 | signed char, SCHAR_MIN, SCHAR_MAX) \ |

399 | : sizeof *(r) == sizeof (short int) \ |

400 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |

401 | short int, SHRT_MIN, SHRT_MAX) \ |

402 | : sizeof *(r) == sizeof (int) \ |

403 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned int, \ |

404 | int, INT_MIN, INT_MAX) \ |

405 | : _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow)) |

406 | # ifdef LLONG_MAX |

407 | # define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \ |

408 | (sizeof *(r) == sizeof (long int) \ |

409 | ? _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ |

410 | long int, LONG_MIN, LONG_MAX) \ |

411 | : _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long long int, \ |

412 | long long int, LLONG_MIN, LLONG_MAX)) |

413 | # else |

414 | # define _GL_INT_OP_WRAPV_LONGISH(a, b, r, op, overflow) \ |

415 | _GL_INT_OP_CALC (a, b, r, op, overflow, unsigned long int, \ |

416 | long int, LONG_MIN, LONG_MAX) |

417 | # endif |

418 | #endif |

419 | |

420 | /* Store the low-order bits of A <op> B into *R, where the operation |

421 | is given by OP. Use the unsigned type UT for calculation to avoid |

422 | overflow problems. *R's type is T, with extrema TMIN and TMAX. |

423 | T must be a signed integer type. Return 1 if the result overflows. */ |

424 | #define _GL_INT_OP_CALC(a, b, r, op, overflow, ut, t, tmin, tmax) \ |

425 | (sizeof ((a) op (b)) < sizeof (t) \ |

426 | ? _GL_INT_OP_CALC1 ((t) (a), (t) (b), r, op, overflow, ut, t, tmin, tmax) \ |

427 | : _GL_INT_OP_CALC1 (a, b, r, op, overflow, ut, t, tmin, tmax)) |

428 | #define _GL_INT_OP_CALC1(a, b, r, op, overflow, ut, t, tmin, tmax) \ |

429 | ((overflow (a, b) \ |

430 | || (EXPR_SIGNED ((a) op (b)) && ((a) op (b)) < (tmin)) \ |

431 | || (tmax) < ((a) op (b))) \ |

432 | ? (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t), 1) \ |

433 | : (*(r) = _GL_INT_OP_WRAPV_VIA_UNSIGNED (a, b, op, ut, t), 0)) |

434 | |

435 | /* Return the low-order bits of A <op> B, where the operation is given |

436 | by OP. Use the unsigned type UT for calculation to avoid undefined |

437 | behavior on signed integer overflow, and convert the result to type T. |

438 | UT is at least as wide as T and is no narrower than unsigned int, |

439 | T is two's complement, and there is no padding or trap representations. |

440 | Assume that converting UT to T yields the low-order bits, as is |

441 | done in all known two's-complement C compilers. E.g., see: |

442 | https://gcc.gnu.org/onlinedocs/gcc/Integers-implementation.html |

443 | |

444 | According to the C standard, converting UT to T yields an |

445 | implementation-defined result or signal for values outside T's |

446 | range. However, code that works around this theoretical problem |

447 | runs afoul of a compiler bug in Oracle Studio 12.3 x86. See: |

448 | https://lists.gnu.org/r/bug-gnulib/2017-04/msg00049.html |

449 | As the compiler bug is real, don't try to work around the |

450 | theoretical problem. */ |

451 | |

452 | #define _GL_INT_OP_WRAPV_VIA_UNSIGNED(a, b, op, ut, t) \ |

453 | ((t) ((ut) (a) op (ut) (b))) |

454 | |

455 | #endif /* _GL_INTPROPS_H */ |

456 |