1 /* Operations with long integers.
2 Copyright (C) 2006-2023 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
7 under the terms of the GNU General Public License as published by the
8 Free Software Foundation; either version 3, or (at your option) any
9 later version.
10
11 GCC is distributed in the hope that it will be useful, but WITHOUT
12 ANY 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 #ifndef DOUBLE_INT_H
21 #define DOUBLE_INT_H
22
23 /* A large integer is currently represented as a pair of HOST_WIDE_INTs.
24 It therefore represents a number with precision of
25 2 * HOST_BITS_PER_WIDE_INT bits (it is however possible that the
26 internal representation will change, if numbers with greater precision
27 are needed, so the users should not rely on it). The representation does
28 not contain any information about signedness of the represented value, so
29 it can be used to represent both signed and unsigned numbers. For
30 operations where the results depend on signedness (division, comparisons),
31 it must be specified separately. For each such operation, there are three
32 versions of the function -- double_int_op, that takes an extra UNS argument
33 giving the signedness of the values, and double_int_sop and double_int_uop
34 that stand for its specializations for signed and unsigned values.
35
36 You may also represent with numbers in smaller precision using double_int.
37 You however need to use double_int_ext (that fills in the bits of the
38 number over the prescribed precision with zeros or with the sign bit) before
39 operations that do not perform arithmetics modulo 2^precision (comparisons,
40 division), and possibly before storing the results, if you want to keep
41 them in some canonical form). In general, the signedness of double_int_ext
42 should match the signedness of the operation.
43
44 ??? The components of double_int differ in signedness mostly for
45 historical reasons (they replace an older structure used to represent
46 numbers with precision higher than HOST_WIDE_INT). It might be less
47 confusing to have them both signed or both unsigned. */
48
49 struct double_int
50 {
51 /* Normally, we would define constructors to create instances.
52 Two things prevent us from doing so.
53 First, defining a constructor makes the class non-POD in C++03,
54 and we certainly want double_int to be a POD.
55 Second, the GCC conding conventions prefer explicit conversion,
56 and explicit conversion operators are not available until C++11. */
57
58 static double_int from_uhwi (unsigned HOST_WIDE_INT cst);
59 static double_int from_shwi (HOST_WIDE_INT cst);
60 static double_int from_pair (HOST_WIDE_INT high, unsigned HOST_WIDE_INT low);
61
62 /* Construct from a fuffer of length LEN. BUFFER will be read according
63 to byte endianness and word endianness. */
64 static double_int from_buffer (const unsigned char *buffer, int len);
65
66 /* No copy assignment operator or destructor to keep the type a POD. */
67
68 /* There are some special value-creation static member functions. */
69
70 static double_int mask (unsigned prec);
71 static double_int max_value (unsigned int prec, bool uns);
72 static double_int min_value (unsigned int prec, bool uns);
73
74 /* The following functions are mutating operations. */
75
76 double_int &operator ++ (); // prefix
77 double_int &operator -- (); // prefix
78 double_int &operator *= (double_int);
79 double_int &operator += (double_int);
80 double_int &operator -= (double_int);
81 double_int &operator &= (double_int);
82 double_int &operator ^= (double_int);
83 double_int &operator |= (double_int);
84
85 /* The following functions are non-mutating operations. */
86
87 /* Conversion functions. */
88
89 HOST_WIDE_INT to_shwi () const;
90 unsigned HOST_WIDE_INT to_uhwi () const;
91
92 /* Conversion query functions. */
93
94 bool fits_uhwi () const;
95 bool fits_shwi () const;
96 bool fits_hwi (bool uns) const;
97
98 /* Attribute query functions. */
99
100 int trailing_zeros () const;
101 int popcount () const;
102
103 /* Arithmetic query operations. */
104
105 bool multiple_of (double_int, bool, double_int *) const;
106
107 /* Arithmetic operation functions. */
108
109 /* The following operations perform arithmetics modulo 2^precision, so you
110 do not need to call .ext between them, even if you are representing
111 numbers with precision less than HOST_BITS_PER_DOUBLE_INT bits. */
112
113 double_int set_bit (unsigned) const;
114 double_int mul_with_sign (double_int, bool unsigned_p, bool *overflow) const;
115 double_int wide_mul_with_sign (double_int, bool unsigned_p,
116 double_int *higher, bool *overflow) const;
117 double_int add_with_sign (double_int, bool unsigned_p, bool *overflow) const;
118 double_int sub_with_overflow (double_int, bool *overflow) const;
119 double_int neg_with_overflow (bool *overflow) const;
120
121 double_int operator * (double_int) const;
122 double_int operator + (double_int) const;
123 double_int operator - (double_int) const;
124 double_int operator - () const;
125 double_int operator ~ () const;
126 double_int operator & (double_int) const;
127 double_int operator | (double_int) const;
128 double_int operator ^ (double_int) const;
129 double_int and_not (double_int) const;
130
131 double_int lshift (HOST_WIDE_INT count) const;
132 double_int lshift (HOST_WIDE_INT count, unsigned int prec, bool arith) const;
133 double_int rshift (HOST_WIDE_INT count) const;
134 double_int rshift (HOST_WIDE_INT count, unsigned int prec, bool arith) const;
135 double_int alshift (HOST_WIDE_INT count, unsigned int prec) const;
136 double_int arshift (HOST_WIDE_INT count, unsigned int prec) const;
137 double_int llshift (HOST_WIDE_INT count, unsigned int prec) const;
138 double_int lrshift (HOST_WIDE_INT count, unsigned int prec) const;
139 double_int lrotate (HOST_WIDE_INT count, unsigned int prec) const;
140 double_int rrotate (HOST_WIDE_INT count, unsigned int prec) const;
141
142 /* You must ensure that double_int::ext is called on the operands
143 of the following operations, if the precision of the numbers
144 is less than HOST_BITS_PER_DOUBLE_INT bits. */
145
146 double_int div (double_int, bool, unsigned) const;
147 double_int sdiv (double_int, unsigned) const;
148 double_int udiv (double_int, unsigned) const;
149 double_int mod (double_int, bool, unsigned) const;
150 double_int smod (double_int, unsigned) const;
151 double_int umod (double_int, unsigned) const;
152 double_int divmod_with_overflow (double_int, bool, unsigned,
153 double_int *, bool *) const;
154 double_int divmod (double_int, bool, unsigned, double_int *) const;
155 double_int sdivmod (double_int, unsigned, double_int *) const;
156 double_int udivmod (double_int, unsigned, double_int *) const;
157
158 /* Precision control functions. */
159
160 double_int ext (unsigned prec, bool uns) const;
161 double_int zext (unsigned prec) const;
162 double_int sext (unsigned prec) const;
163
164 /* Comparative functions. */
165
166 bool is_zero () const;
167 bool is_one () const;
168 bool is_minus_one () const;
169 bool is_negative () const;
170
171 int cmp (double_int b, bool uns) const;
172 int ucmp (double_int b) const;
173 int scmp (double_int b) const;
174
175 bool ult (double_int b) const;
176 bool ule (double_int b) const;
177 bool ugt (double_int b) const;
178 bool slt (double_int b) const;
179 bool sle (double_int b) const;
180 bool sgt (double_int b) const;
181
182 double_int max (double_int b, bool uns);
183 double_int smax (double_int b);
184 double_int umax (double_int b);
185
186 double_int min (double_int b, bool uns);
187 double_int smin (double_int b);
188 double_int umin (double_int b);
189
190 bool operator == (double_int cst2) const;
191 bool operator != (double_int cst2) const;
192
193 /* Please migrate away from using these member variables publicly. */
194
195 unsigned HOST_WIDE_INT low;
196 HOST_WIDE_INT high;
197
198 };
199
200 #define HOST_BITS_PER_DOUBLE_INT (2 * HOST_BITS_PER_WIDE_INT)
201
202 /* Constructors and conversions. */
203
204 /* Constructs double_int from integer CST. The bits over the precision of
205 HOST_WIDE_INT are filled with the sign bit. */
206
207 inline double_int
208 double_int::from_shwi (HOST_WIDE_INT cst)
209 {
210 double_int r;
211 r.low = (unsigned HOST_WIDE_INT) cst;
212 r.high = cst < 0 ? -1 : 0;
213 return r;
214 }
215
216 /* Some useful constants. */
217 /* FIXME(crowl): Maybe remove after converting callers?
218 The problem is that a named constant would not be as optimizable,
219 while the functional syntax is more verbose. */
220
221 #define double_int_minus_one (double_int::from_shwi (-1))
222 #define double_int_zero (double_int::from_shwi (0))
223 #define double_int_one (double_int::from_shwi (1))
224 #define double_int_two (double_int::from_shwi (2))
225 #define double_int_ten (double_int::from_shwi (10))
226
227 /* Constructs double_int from unsigned integer CST. The bits over the
228 precision of HOST_WIDE_INT are filled with zeros. */
229
230 inline double_int
231 double_int::from_uhwi (unsigned HOST_WIDE_INT cst)
232 {
233 double_int r;
234 r.low = cst;
235 r.high = 0;
236 return r;
237 }
238
239 inline double_int
240 double_int::from_pair (HOST_WIDE_INT high, unsigned HOST_WIDE_INT low)
241 {
242 double_int r;
243 r.low = low;
244 r.high = high;
245 return r;
246 }
247
248 inline double_int &
249 double_int::operator ++ ()
250 {
251 *this += double_int_one;
252 return *this;
253 }
254
255 inline double_int &
256 double_int::operator -- ()
257 {
258 *this -= double_int_one;
259 return *this;
260 }
261
262 inline double_int &
263 double_int::operator &= (double_int b)
264 {
265 *this = *this & b;
266 return *this;
267 }
268
269 inline double_int &
270 double_int::operator ^= (double_int b)
271 {
272 *this = *this ^ b;
273 return *this;
274 }
275
276 inline double_int &
277 double_int::operator |= (double_int b)
278 {
279 *this = *this | b;
280 return *this;
281 }
282
283 /* Returns value of CST as a signed number. CST must satisfy
284 double_int::fits_signed. */
285
286 inline HOST_WIDE_INT
287 double_int::to_shwi () const
288 {
289 return (HOST_WIDE_INT) low;
290 }
291
292 /* Returns value of CST as an unsigned number. CST must satisfy
293 double_int::fits_unsigned. */
294
295 inline unsigned HOST_WIDE_INT
296 double_int::to_uhwi () const
297 {
298 return low;
299 }
300
301 /* Returns true if CST fits in unsigned HOST_WIDE_INT. */
302
303 inline bool
304 double_int::fits_uhwi () const
305 {
306 return high == 0;
307 }
308
309 /* Logical operations. */
310
311 /* Returns ~A. */
312
313 inline double_int
314 double_int::operator ~ () const
315 {
316 double_int result;
317 result.low = ~low;
318 result.high = ~high;
319 return result;
320 }
321
322 /* Returns A | B. */
323
324 inline double_int
325 double_int::operator | (double_int b) const
326 {
327 double_int result;
328 result.low = low | b.low;
329 result.high = high | b.high;
330 return result;
331 }
332
333 /* Returns A & B. */
334
335 inline double_int
336 double_int::operator & (double_int b) const
337 {
338 double_int result;
339 result.low = low & b.low;
340 result.high = high & b.high;
341 return result;
342 }
343
344 /* Returns A & ~B. */
345
346 inline double_int
347 double_int::and_not (double_int b) const
348 {
349 double_int result;
350 result.low = low & ~b.low;
351 result.high = high & ~b.high;
352 return result;
353 }
354
355 /* Returns A ^ B. */
356
357 inline double_int
358 double_int::operator ^ (double_int b) const
359 {
360 double_int result;
361 result.low = low ^ b.low;
362 result.high = high ^ b.high;
363 return result;
364 }
365
366 void dump_double_int (FILE *, double_int, bool);
367
368 #define ALL_ONES HOST_WIDE_INT_M1U
369
370 /* The operands of the following comparison functions must be processed
371 with double_int_ext, if their precision is less than
372 HOST_BITS_PER_DOUBLE_INT bits. */
373
374 /* Returns true if CST is zero. */
375
376 inline bool
377 double_int::is_zero () const
378 {
379 return low == 0 && high == 0;
380 }
381
382 /* Returns true if CST is one. */
383
384 inline bool
385 double_int::is_one () const
386 {
387 return low == 1 && high == 0;
388 }
389
390 /* Returns true if CST is minus one. */
391
392 inline bool
393 double_int::is_minus_one () const
394 {
395 return low == ALL_ONES && high == -1;
396 }
397
398 /* Returns true if CST is negative. */
399
400 inline bool
401 double_int::is_negative () const
402 {
403 return high < 0;
404 }
405
406 /* Returns true if CST1 == CST2. */
407
408 inline bool
409 double_int::operator == (double_int cst2) const
410 {
411 return low == cst2.low && high == cst2.high;
412 }
413
414 /* Returns true if CST1 != CST2. */
415
416 inline bool
417 double_int::operator != (double_int cst2) const
418 {
419 return low != cst2.low || high != cst2.high;
420 }
421
422 /* Return number of set bits of CST. */
423
424 inline int
425 double_int::popcount () const
426 {
427 return popcount_hwi (high) + popcount_hwi (low);
428 }
429
430
431 #ifndef GENERATOR_FILE
432 /* Conversion to and from GMP integer representations. */
433
434 void mpz_set_double_int (mpz_t, double_int, bool);
435 double_int mpz_get_double_int (const_tree, mpz_t, bool);
436 #endif
437
438 namespace wi
439 {
440 template <>
441 struct int_traits <double_int>
442 {
443 static const enum precision_type precision_type = CONST_PRECISION;
444 static const bool host_dependent_precision = true;
445 static const unsigned int precision = HOST_BITS_PER_DOUBLE_INT;
446 static unsigned int get_precision (const double_int &);
447 static wi::storage_ref decompose (HOST_WIDE_INT *, unsigned int,
448 const double_int &);
449 };
450 }
451
452 inline unsigned int
453 wi::int_traits <double_int>::get_precision (const double_int &)
454 {
455 return precision;
456 }
457
458 inline wi::storage_ref
459 wi::int_traits <double_int>::decompose (HOST_WIDE_INT *scratch, unsigned int p,
460 const double_int &x)
461 {
462 gcc_checking_assert (precision == p);
463 scratch[0] = x.low;
464 if ((x.high == 0 && scratch[0] >= 0) || (x.high == -1 && scratch[0] < 0))
465 return wi::storage_ref (scratch, 1, precision);
466 scratch[1] = x.high;
467 return wi::storage_ref (scratch, 2, precision);
468 }
469
470 #endif /* DOUBLE_INT_H */