gcc/double-int.h

   1 /* Operations with long integers.
   2    Copyright (C) 2006-2017 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 endianess and word endianess.  */
  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 */