gcc/fixed-value.cc

   1 /* Fixed-point arithmetic support.
   2    Copyright (C) 2006-2024 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 under
   7 the terms of the GNU General Public License as published by the Free
   8 Software Foundation; either version 3, or (at your option) any later
   9 version.
  10
  11 GCC is distributed in the hope that it will be useful, but WITHOUT ANY
  12 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 #include "config.h"
  21 #include "system.h"
  22 #include "coretypes.h"
  23 #include "tm.h"
  24 #include "tree.h"
  25 #include "diagnostic-core.h"
  26
  27 /* Compare two fixed objects for bitwise identity.  */
  28
  29 bool
  30 fixed_identical (const FIXED_VALUE_TYPE *a, const FIXED_VALUE_TYPE *b)
  31 {
  32   return (a->mode == b->mode
  33           && a->data.high == b->data.high
  34           && a->data.low == b->data.low);
  35 }
  36
  37 /* Calculate a hash value.  */
  38
  39 unsigned int
  40 fixed_hash (const FIXED_VALUE_TYPE *f)
  41 {
  42   return (unsigned int) (f->data.low ^ f->data.high);
  43 }
  44
  45 /* Define the enum code for the range of the fixed-point value.  */
  46 enum fixed_value_range_code {
  47   FIXED_OK,             /* The value is within the range.  */
  48   FIXED_UNDERFLOW,      /* The value is less than the minimum.  */
  49   FIXED_GT_MAX_EPS,     /* The value is greater than the maximum, but not equal
  50                            to the maximum plus the epsilon.  */
  51   FIXED_MAX_EPS         /* The value equals the maximum plus the epsilon.  */
  52 };
  53
  54 /* Check REAL_VALUE against the range of the fixed-point mode.
  55    Return FIXED_OK, if it is within the range.
  56           FIXED_UNDERFLOW, if it is less than the minimum.
  57           FIXED_GT_MAX_EPS, if it is greater than the maximum, but not equal to
  58             the maximum plus the epsilon.
  59           FIXED_MAX_EPS, if it is equal to the maximum plus the epsilon.  */
  60
  61 static enum fixed_value_range_code
  62 check_real_for_fixed_mode (REAL_VALUE_TYPE *real_value, machine_mode mode)
  63 {
  64   REAL_VALUE_TYPE max_value, min_value, epsilon_value;
  65
  66   real_2expN (&max_value, GET_MODE_IBIT (mode), VOIDmode);
  67   real_2expN (&epsilon_value, -GET_MODE_FBIT (mode), VOIDmode);
  68
  69   if (SIGNED_FIXED_POINT_MODE_P (mode))
  70     min_value = real_value_negate (&max_value);
  71   else
  72     real_from_string (&min_value, "0.0");
  73
  74   if (real_compare (LT_EXPR, real_value, &min_value))
  75     return FIXED_UNDERFLOW;
  76   if (real_compare (EQ_EXPR, real_value, &max_value))
  77     return FIXED_MAX_EPS;
  78   real_arithmetic (&max_value, MINUS_EXPR, &max_value, &epsilon_value);
  79   if (real_compare (GT_EXPR, real_value, &max_value))
  80     return FIXED_GT_MAX_EPS;
  81   return FIXED_OK;
  82 }
  83
  84
  85 /* Construct a CONST_FIXED from a bit payload and machine mode MODE.
  86    The bits in PAYLOAD are sign-extended/zero-extended according to MODE.  */
  87
  88 FIXED_VALUE_TYPE
  89 fixed_from_double_int (double_int payload, scalar_mode mode)
  90 {
  91   FIXED_VALUE_TYPE value;
  92
  93   gcc_assert (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_DOUBLE_INT);
  94
  95   if (SIGNED_SCALAR_FIXED_POINT_MODE_P (mode))
  96     value.data = payload.sext (1 + GET_MODE_IBIT (mode) + GET_MODE_FBIT (mode));
  97   else if (UNSIGNED_SCALAR_FIXED_POINT_MODE_P (mode))
  98     value.data = payload.zext (GET_MODE_IBIT (mode) + GET_MODE_FBIT (mode));
  99   else
 100     gcc_unreachable ();
 101
 102   value.mode = mode;
 103
 104   return value;
 105 }
 106
 107
 108 /* Initialize from a decimal or hexadecimal string.  */
 109
 110 void
 111 fixed_from_string (FIXED_VALUE_TYPE *f, const char *str, scalar_mode mode)
 112 {
 113   REAL_VALUE_TYPE real_value, fixed_value, base_value;
 114   unsigned int fbit;
 115   enum fixed_value_range_code temp;
 116   bool fail;
 117
 118   f->mode = mode;
 119   fbit = GET_MODE_FBIT (mode);
 120
 121   real_from_string (&real_value, str);
 122   temp = check_real_for_fixed_mode (&real_value, f->mode);
 123   /* We don't want to warn the case when the _Fract value is 1.0.  */
 124   if (temp == FIXED_UNDERFLOW
 125       || temp == FIXED_GT_MAX_EPS
 126       || (temp == FIXED_MAX_EPS && ALL_ACCUM_MODE_P (f->mode)))
 127     warning (OPT_Woverflow,
 128              "large fixed-point constant implicitly truncated to fixed-point type");
 129   real_2expN (&base_value, fbit, VOIDmode);
 130   real_arithmetic (&fixed_value, MULT_EXPR, &real_value, &base_value);
 131   wide_int w = real_to_integer (&fixed_value, &fail,
 132                                 GET_MODE_PRECISION (mode));
 133   f->data.low = w.ulow ();
 134   f->data.high = w.elt (1);
 135
 136   if (temp == FIXED_MAX_EPS && ALL_FRACT_MODE_P (f->mode))
 137     {
 138       /* From the spec, we need to evaluate 1 to the maximal value.  */
 139       f->data.low = -1;
 140       f->data.high = -1;
 141       f->data = f->data.zext (GET_MODE_FBIT (f->mode)
 142                                 + GET_MODE_IBIT (f->mode));
 143     }
 144   else
 145     f->data = f->data.ext (SIGNED_FIXED_POINT_MODE_P (f->mode)
 146                               + GET_MODE_FBIT (f->mode)
 147                               + GET_MODE_IBIT (f->mode),
 148                               UNSIGNED_FIXED_POINT_MODE_P (f->mode));
 149 }
 150
 151 /* Render F as a decimal floating point constant.  */
 152
 153 void
 154 fixed_to_decimal (char *str, const FIXED_VALUE_TYPE *f_orig,
 155                   size_t buf_size)
 156 {
 157   REAL_VALUE_TYPE real_value, base_value, fixed_value;
 158
 159   signop sgn = UNSIGNED_FIXED_POINT_MODE_P (f_orig->mode) ? UNSIGNED : SIGNED;
 160   real_2expN (&base_value, GET_MODE_FBIT (f_orig->mode), VOIDmode);
 161   real_from_integer (&real_value, VOIDmode,
 162                      wide_int::from (f_orig->data,
 163                                      GET_MODE_PRECISION (f_orig->mode), sgn),
 164                      sgn);
 165   real_arithmetic (&fixed_value, RDIV_EXPR, &real_value, &base_value);
 166   real_to_decimal (str, &fixed_value, buf_size, 0, 1);
 167 }
 168
 169 /* If SAT_P, saturate A to the maximum or the minimum, and save to *F based on
 170    the machine mode MODE.
 171    Do not modify *F otherwise.
 172    This function assumes the width of double_int is greater than the width
 173    of the fixed-point value (the sum of a possible sign bit, possible ibits,
 174    and fbits).
 175    Return true, if !SAT_P and overflow.  */
 176
 177 static bool
 178 fixed_saturate1 (machine_mode mode, double_int a, double_int *f,
 179                  bool sat_p)
 180 {
 181   bool overflow_p = false;
 182   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (mode);
 183   int i_f_bits = GET_MODE_IBIT (mode) + GET_MODE_FBIT (mode);
 184
 185   if (unsigned_p) /* Unsigned type.  */
 186     {
 187       double_int max;
 188       max.low = -1;
 189       max.high = -1;
 190       max = max.zext (i_f_bits);
 191       if (a.ugt (max))
 192         {
 193           if (sat_p)
 194             *f = max;
 195           else
 196             overflow_p = true;
 197         }
 198     }
 199   else /* Signed type.  */
 200     {
 201       double_int max, min;
 202       max.high = -1;
 203       max.low = -1;
 204       max = max.zext (i_f_bits);
 205       min.high = 0;
 206       min.low = 1;
 207       min = min.alshift (i_f_bits, HOST_BITS_PER_DOUBLE_INT);
 208       min = min.sext (1 + i_f_bits);
 209       if (a.sgt (max))
 210         {
 211           if (sat_p)
 212             *f = max;
 213           else
 214             overflow_p = true;
 215         }
 216       else if (a.slt (min))
 217         {
 218           if (sat_p)
 219             *f = min;
 220           else
 221             overflow_p = true;
 222         }
 223     }
 224   return overflow_p;
 225 }
 226
 227 /* If SAT_P, saturate {A_HIGH, A_LOW} to the maximum or the minimum, and
 228    save to *F based on the machine mode MODE.
 229    Do not modify *F otherwise.
 230    This function assumes the width of two double_int is greater than the width
 231    of the fixed-point value (the sum of a possible sign bit, possible ibits,
 232    and fbits).
 233    Return true, if !SAT_P and overflow.  */
 234
 235 static bool
 236 fixed_saturate2 (machine_mode mode, double_int a_high, double_int a_low,
 237                  double_int *f, bool sat_p)
 238 {
 239   bool overflow_p = false;
 240   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (mode);
 241   int i_f_bits = GET_MODE_IBIT (mode) + GET_MODE_FBIT (mode);
 242
 243   if (unsigned_p) /* Unsigned type.  */
 244     {
 245       double_int max_r, max_s;
 246       max_r.high = 0;
 247       max_r.low = 0;
 248       max_s.high = -1;
 249       max_s.low = -1;
 250       max_s = max_s.zext (i_f_bits);
 251       if (a_high.ugt (max_r)
 252           || (a_high == max_r &&
 253               a_low.ugt (max_s)))
 254         {
 255           if (sat_p)
 256             *f = max_s;
 257           else
 258             overflow_p = true;
 259         }
 260     }
 261   else /* Signed type.  */
 262     {
 263       double_int max_r, max_s, min_r, min_s;
 264       max_r.high = 0;
 265       max_r.low = 0;
 266       max_s.high = -1;
 267       max_s.low = -1;
 268       max_s = max_s.zext (i_f_bits);
 269       min_r.high = -1;
 270       min_r.low = -1;
 271       min_s.high = 0;
 272       min_s.low = 1;
 273       min_s = min_s.alshift (i_f_bits, HOST_BITS_PER_DOUBLE_INT);
 274       min_s = min_s.sext (1 + i_f_bits);
 275       if (a_high.sgt (max_r)
 276           || (a_high == max_r &&
 277               a_low.ugt (max_s)))
 278         {
 279           if (sat_p)
 280             *f = max_s;
 281           else
 282             overflow_p = true;
 283         }
 284       else if (a_high.slt (min_r)
 285                || (a_high == min_r &&
 286                    a_low.ult (min_s)))
 287         {
 288           if (sat_p)
 289             *f = min_s;
 290           else
 291             overflow_p = true;
 292         }
 293     }
 294   return overflow_p;
 295 }
 296
 297 /* Return the sign bit based on I_F_BITS.  */
 298
 299 static inline int
 300 get_fixed_sign_bit (double_int a, int i_f_bits)
 301 {
 302   if (i_f_bits < HOST_BITS_PER_WIDE_INT)
 303     return (a.low >> i_f_bits) & 1;
 304   else
 305     return (a.high >> (i_f_bits - HOST_BITS_PER_WIDE_INT)) & 1;
 306 }
 307
 308 /* Calculate F = A + (SUBTRACT_P ? -B : B).
 309    If SAT_P, saturate the result to the max or the min.
 310    Return true, if !SAT_P and overflow.  */
 311
 312 static bool
 313 do_fixed_add (FIXED_VALUE_TYPE *f, const FIXED_VALUE_TYPE *a,
 314               const FIXED_VALUE_TYPE *b, bool subtract_p, bool sat_p)
 315 {
 316   bool overflow_p = false;
 317   bool unsigned_p;
 318   double_int temp;
 319   int i_f_bits;
 320
 321   /* This was a conditional expression but it triggered a bug in
 322      Sun C 5.5.  */
 323   if (subtract_p)
 324     temp = -b->data;
 325   else
 326     temp = b->data;
 327
 328   unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (a->mode);
 329   i_f_bits = GET_MODE_IBIT (a->mode) + GET_MODE_FBIT (a->mode);
 330   f->mode = a->mode;
 331   f->data = a->data + temp;
 332   if (unsigned_p) /* Unsigned type.  */
 333     {
 334       if (subtract_p) /* Unsigned subtraction.  */
 335         {
 336           if (a->data.ult (b->data))
 337             {
 338               if (sat_p)
 339                 {
 340                   f->data.high = 0;
 341                   f->data.low = 0;
 342                  }
 343               else
 344                 overflow_p = true;
 345             }
 346         }
 347       else /* Unsigned addition.  */
 348         {
 349           f->data = f->data.zext (i_f_bits);
 350           if (f->data.ult (a->data)
 351               || f->data.ult (b->data))
 352             {
 353               if (sat_p)
 354                 {
 355                   f->data.high = -1;
 356                   f->data.low = -1;
 357                 }
 358               else
 359                 overflow_p = true;
 360             }
 361         }
 362     }
 363   else /* Signed type.  */
 364     {
 365       if ((!subtract_p
 366            && (get_fixed_sign_bit (a->data, i_f_bits)
 367                == get_fixed_sign_bit (b->data, i_f_bits))
 368            && (get_fixed_sign_bit (a->data, i_f_bits)
 369                != get_fixed_sign_bit (f->data, i_f_bits)))
 370           || (subtract_p
 371               && (get_fixed_sign_bit (a->data, i_f_bits)
 372                   != get_fixed_sign_bit (b->data, i_f_bits))
 373               && (get_fixed_sign_bit (a->data, i_f_bits)
 374                   != get_fixed_sign_bit (f->data, i_f_bits))))
 375         {
 376           if (sat_p)
 377             {
 378               f->data.low = 1;
 379               f->data.high = 0;
 380               f->data = f->data.alshift (i_f_bits, HOST_BITS_PER_DOUBLE_INT);
 381               if (get_fixed_sign_bit (a->data, i_f_bits) == 0)
 382                 {
 383                   --f->data;
 384                 }
 385             }
 386           else
 387             overflow_p = true;
 388         }
 389     }
 390   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
 391   return overflow_p;
 392 }
 393
 394 /* Calculate F = A * B.
 395    If SAT_P, saturate the result to the max or the min.
 396    Return true, if !SAT_P and overflow.  */
 397
 398 static bool
 399 do_fixed_multiply (FIXED_VALUE_TYPE *f, const FIXED_VALUE_TYPE *a,
 400                    const FIXED_VALUE_TYPE *b, bool sat_p)
 401 {
 402   bool overflow_p = false;
 403   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (a->mode);
 404   int i_f_bits = GET_MODE_IBIT (a->mode) + GET_MODE_FBIT (a->mode);
 405   f->mode = a->mode;
 406   if (GET_MODE_PRECISION (f->mode) <= HOST_BITS_PER_WIDE_INT)
 407     {
 408       f->data = a->data * b->data;
 409       f->data = f->data.lshift (-GET_MODE_FBIT (f->mode),
 410                                 HOST_BITS_PER_DOUBLE_INT, !unsigned_p);
 411       overflow_p = fixed_saturate1 (f->mode, f->data, &f->data, sat_p);
 412     }
 413   else
 414     {
 415       /* The result of multiplication expands to two double_int.  */
 416       double_int a_high, a_low, b_high, b_low;
 417       double_int high_high, high_low, low_high, low_low;
 418       double_int r, s, temp1, temp2;
 419       int carry = 0;
 420
 421       /* Decompose a and b to four double_int.  */
 422       a_high.low = a->data.high;
 423       a_high.high = 0;
 424       a_low.low = a->data.low;
 425       a_low.high = 0;
 426       b_high.low = b->data.high;
 427       b_high.high = 0;
 428       b_low.low = b->data.low;
 429       b_low.high = 0;
 430
 431       /* Perform four multiplications.  */
 432       low_low = a_low * b_low;
 433       low_high = a_low * b_high;
 434       high_low = a_high * b_low;
 435       high_high = a_high * b_high;
 436
 437       /* Accumulate four results to {r, s}.  */
 438       temp1.high = high_low.low;
 439       temp1.low = 0;
 440       s = low_low + temp1;
 441       if (s.ult (low_low)
 442           || s.ult (temp1))
 443         carry ++; /* Carry */
 444       temp1.high = s.high;
 445       temp1.low = s.low;
 446       temp2.high = low_high.low;
 447       temp2.low = 0;
 448       s = temp1 + temp2;
 449       if (s.ult (temp1)
 450           || s.ult (temp2))
 451         carry ++; /* Carry */
 452
 453       temp1.low = high_low.high;
 454       temp1.high = 0;
 455       r = high_high + temp1;
 456       temp1.low = low_high.high;
 457       temp1.high = 0;
 458       r += temp1;
 459       temp1.low = carry;
 460       temp1.high = 0;
 461       r += temp1;
 462
 463       /* We need to subtract b from r, if a < 0.  */
 464       if (!unsigned_p && a->data.high < 0)
 465         r -= b->data;
 466       /* We need to subtract a from r, if b < 0.  */
 467       if (!unsigned_p && b->data.high < 0)
 468         r -= a->data;
 469
 470       /* Shift right the result by FBIT.  */
 471       if (GET_MODE_FBIT (f->mode) == HOST_BITS_PER_DOUBLE_INT)
 472         {
 473           s.low = r.low;
 474           s.high = r.high;
 475           if (unsigned_p)
 476             {
 477               r.low = 0;
 478               r.high = 0;
 479             }
 480           else
 481             {
 482               r.low = -1;
 483               r.high = -1;
 484             }
 485           f->data.low = s.low;
 486           f->data.high = s.high;
 487         }
 488       else
 489         {
 490           s = s.llshift ((-GET_MODE_FBIT (f->mode)), HOST_BITS_PER_DOUBLE_INT);
 491           f->data = r.llshift ((HOST_BITS_PER_DOUBLE_INT
 492                           - GET_MODE_FBIT (f->mode)),
 493                          HOST_BITS_PER_DOUBLE_INT);
 494           f->data.low = f->data.low | s.low;
 495           f->data.high = f->data.high | s.high;
 496           s.low = f->data.low;
 497           s.high = f->data.high;
 498           r = r.lshift (-GET_MODE_FBIT (f->mode),
 499                         HOST_BITS_PER_DOUBLE_INT, !unsigned_p);
 500         }
 501
 502       overflow_p = fixed_saturate2 (f->mode, r, s, &f->data, sat_p);
 503     }
 504
 505   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
 506   return overflow_p;
 507 }
 508
 509 /* Calculate F = A / B.
 510    If SAT_P, saturate the result to the max or the min.
 511    Return true, if !SAT_P and overflow.  */
 512
 513 static bool
 514 do_fixed_divide (FIXED_VALUE_TYPE *f, const FIXED_VALUE_TYPE *a,
 515                  const FIXED_VALUE_TYPE *b, bool sat_p)
 516 {
 517   bool overflow_p = false;
 518   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (a->mode);
 519   int i_f_bits = GET_MODE_IBIT (a->mode) + GET_MODE_FBIT (a->mode);
 520   f->mode = a->mode;
 521   if (GET_MODE_PRECISION (f->mode) <= HOST_BITS_PER_WIDE_INT)
 522     {
 523       f->data = a->data.lshift (GET_MODE_FBIT (f->mode),
 524                                 HOST_BITS_PER_DOUBLE_INT, !unsigned_p);
 525       f->data = f->data.div (b->data, unsigned_p, TRUNC_DIV_EXPR);
 526       overflow_p = fixed_saturate1 (f->mode, f->data, &f->data, sat_p);
 527     }
 528   else
 529     {
 530       double_int pos_a, pos_b, r, s;
 531       double_int quo_r, quo_s, mod, temp;
 532       int num_of_neg = 0;
 533       int i;
 534
 535       /* If a < 0, negate a.  */
 536       if (!unsigned_p && a->data.high < 0)
 537         {
 538           pos_a = -a->data;
 539           num_of_neg ++;
 540         }
 541       else
 542         pos_a = a->data;
 543
 544       /* If b < 0, negate b.  */
 545       if (!unsigned_p && b->data.high < 0)
 546         {
 547           pos_b = -b->data;
 548           num_of_neg ++;
 549         }
 550       else
 551         pos_b = b->data;
 552
 553       /* Left shift pos_a to {r, s} by FBIT.  */
 554       if (GET_MODE_FBIT (f->mode) == HOST_BITS_PER_DOUBLE_INT)
 555         {
 556           r = pos_a;
 557           s.high = 0;
 558           s.low = 0;
 559         }
 560       else
 561         {
 562           s = pos_a.llshift (GET_MODE_FBIT (f->mode), HOST_BITS_PER_DOUBLE_INT);
 563           r = pos_a.llshift (- (HOST_BITS_PER_DOUBLE_INT
 564                             - GET_MODE_FBIT (f->mode)),
 565                          HOST_BITS_PER_DOUBLE_INT);
 566         }
 567
 568       /* Divide r by pos_b to quo_r.  The remainder is in mod.  */
 569       quo_r = r.divmod (pos_b, 1, TRUNC_DIV_EXPR, &mod);
 570       quo_s = double_int_zero;
 571
 572       for (i = 0; i < HOST_BITS_PER_DOUBLE_INT; i++)
 573         {
 574           /* Record the leftmost bit of mod.  */
 575           int leftmost_mod = (mod.high < 0);
 576
 577           /* Shift left mod by 1 bit.  */
 578           mod = mod.lshift (1);
 579
 580           /* Test the leftmost bit of s to add to mod.  */
 581           if (s.high < 0)
 582             mod.low += 1;
 583
 584           /* Shift left quo_s by 1 bit.  */
 585           quo_s = quo_s.lshift (1);
 586
 587           /* Try to calculate (mod - pos_b).  */
 588           temp = mod - pos_b;
 589
 590           if (leftmost_mod == 1 || mod.ucmp (pos_b) != -1)
 591             {
 592               quo_s.low += 1;
 593               mod = temp;
 594             }
 595
 596           /* Shift left s by 1 bit.  */
 597           s = s.lshift (1);
 598
 599         }
 600
 601       if (num_of_neg == 1)
 602         {
 603           quo_s = -quo_s;
 604           if (quo_s.high == 0 && quo_s.low == 0)
 605             quo_r = -quo_r;
 606           else
 607             {
 608               quo_r.low = ~quo_r.low;
 609               quo_r.high = ~quo_r.high;
 610             }
 611         }
 612
 613       f->data = quo_s;
 614       overflow_p = fixed_saturate2 (f->mode, quo_r, quo_s, &f->data, sat_p);
 615     }
 616
 617   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
 618   return overflow_p;
 619 }
 620
 621 /* Calculate F = A << B if LEFT_P.  Otherwise, F = A >> B.
 622    If SAT_P, saturate the result to the max or the min.
 623    Return true, if !SAT_P and overflow.  */
 624
 625 static bool
 626 do_fixed_shift (FIXED_VALUE_TYPE *f, const FIXED_VALUE_TYPE *a,
 627               const FIXED_VALUE_TYPE *b, bool left_p, bool sat_p)
 628 {
 629   bool overflow_p = false;
 630   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (a->mode);
 631   int i_f_bits = GET_MODE_IBIT (a->mode) + GET_MODE_FBIT (a->mode);
 632   f->mode = a->mode;
 633
 634   if (b->data.low == 0)
 635     {
 636       f->data = a->data;
 637       return overflow_p;
 638     }
 639
 640   if (GET_MODE_PRECISION (f->mode) <= HOST_BITS_PER_WIDE_INT || (!left_p))
 641     {
 642       f->data = a->data.lshift (left_p ? b->data.low : -b->data.low,
 643                                 HOST_BITS_PER_DOUBLE_INT, !unsigned_p);
 644       if (left_p) /* Only left shift saturates.  */
 645         overflow_p = fixed_saturate1 (f->mode, f->data, &f->data, sat_p);
 646     }
 647   else /* We need two double_int to store the left-shift result.  */
 648     {
 649       double_int temp_high, temp_low;
 650       if (b->data.low == HOST_BITS_PER_DOUBLE_INT)
 651         {
 652           temp_high = a->data;
 653           temp_low.high = 0;
 654           temp_low.low = 0;
 655         }
 656       else
 657         {
 658           temp_low = a->data.lshift (b->data.low,
 659                                      HOST_BITS_PER_DOUBLE_INT, !unsigned_p);
 660           /* Logical shift right to temp_high.  */
 661           temp_high = a->data.llshift (b->data.low - HOST_BITS_PER_DOUBLE_INT,
 662                          HOST_BITS_PER_DOUBLE_INT);
 663         }
 664       if (!unsigned_p && a->data.high < 0) /* Signed-extend temp_high.  */
 665         temp_high = temp_high.ext (b->data.low, unsigned_p);
 666       f->data = temp_low;
 667       overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low, &f->data,
 668                                     sat_p);
 669     }
 670   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
 671   return overflow_p;
 672 }
 673
 674 /* Calculate F = -A.
 675    If SAT_P, saturate the result to the max or the min.
 676    Return true, if !SAT_P and overflow.  */
 677
 678 static bool
 679 do_fixed_neg (FIXED_VALUE_TYPE *f, const FIXED_VALUE_TYPE *a, bool sat_p)
 680 {
 681   bool overflow_p = false;
 682   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (a->mode);
 683   int i_f_bits = GET_MODE_IBIT (a->mode) + GET_MODE_FBIT (a->mode);
 684   f->mode = a->mode;
 685   f->data = -a->data;
 686   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
 687
 688   if (unsigned_p) /* Unsigned type.  */
 689     {
 690       if (f->data.low != 0 || f->data.high != 0)
 691         {
 692           if (sat_p)
 693             {
 694               f->data.low = 0;
 695               f->data.high = 0;
 696             }
 697           else
 698             overflow_p = true;
 699         }
 700     }
 701   else /* Signed type.  */
 702     {
 703       if (!(f->data.high == 0 && f->data.low == 0)
 704           && f->data.high == a->data.high && f->data.low == a->data.low )
 705         {
 706           if (sat_p)
 707             {
 708               /* Saturate to the maximum by subtracting f->data by one.  */
 709               f->data.low = -1;
 710               f->data.high = -1;
 711               f->data = f->data.zext (i_f_bits);
 712             }
 713           else
 714             overflow_p = true;
 715         }
 716     }
 717   return overflow_p;
 718 }
 719
 720 /* Perform the binary or unary operation described by CODE.
 721    Note that OP0 and OP1 must have the same mode for binary operators.
 722    For a unary operation, leave OP1 NULL.
 723    Return true, if !SAT_P and overflow.  */
 724
 725 bool
 726 fixed_arithmetic (FIXED_VALUE_TYPE *f, int icode, const FIXED_VALUE_TYPE *op0,
 727                   const FIXED_VALUE_TYPE *op1, bool sat_p)
 728 {
 729   switch (icode)
 730     {
 731     case NEGATE_EXPR:
 732       return do_fixed_neg (f, op0, sat_p);
 733
 734     case PLUS_EXPR:
 735       gcc_assert (op0->mode == op1->mode);
 736       return do_fixed_add (f, op0, op1, false, sat_p);
 737
 738     case MINUS_EXPR:
 739       gcc_assert (op0->mode == op1->mode);
 740       return do_fixed_add (f, op0, op1, true, sat_p);
 741
 742     case MULT_EXPR:
 743       gcc_assert (op0->mode == op1->mode);
 744       return do_fixed_multiply (f, op0, op1, sat_p);
 745
 746     case TRUNC_DIV_EXPR:
 747       gcc_assert (op0->mode == op1->mode);
 748       return do_fixed_divide (f, op0, op1, sat_p);
 749
 750     case LSHIFT_EXPR:
 751       return do_fixed_shift (f, op0, op1, true, sat_p);
 752
 753     case RSHIFT_EXPR:
 754       return do_fixed_shift (f, op0, op1, false, sat_p);
 755
 756     default:
 757       gcc_unreachable ();
 758     }
 759 }
 760
 761 /* Compare fixed-point values by tree_code.
 762    Note that OP0 and OP1 must have the same mode.  */
 763
 764 bool
 765 fixed_compare (int icode, const FIXED_VALUE_TYPE *op0,
 766                const FIXED_VALUE_TYPE *op1)
 767 {
 768   enum tree_code code = (enum tree_code) icode;
 769   gcc_assert (op0->mode == op1->mode);
 770
 771   switch (code)
 772     {
 773     case NE_EXPR:
 774       return op0->data != op1->data;
 775
 776     case EQ_EXPR:
 777       return op0->data == op1->data;
 778
 779     case LT_EXPR:
 780       return op0->data.cmp (op1->data,
 781                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) == -1;
 782
 783     case LE_EXPR:
 784       return op0->data.cmp (op1->data,
 785                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) != 1;
 786
 787     case GT_EXPR:
 788       return op0->data.cmp (op1->data,
 789                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) == 1;
 790
 791     case GE_EXPR:
 792       return op0->data.cmp (op1->data,
 793                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) != -1;
 794
 795     default:
 796       gcc_unreachable ();
 797     }
 798 }
 799
 800 /* Extend or truncate to a new mode.
 801    If SAT_P, saturate the result to the max or the min.
 802    Return true, if !SAT_P and overflow.  */
 803
 804 bool
 805 fixed_convert (FIXED_VALUE_TYPE *f, scalar_mode mode,
 806                const FIXED_VALUE_TYPE *a, bool sat_p)
 807 {
 808   bool overflow_p = false;
 809   if (mode == a->mode)
 810     {
 811       *f = *a;
 812       return overflow_p;
 813     }
 814
 815   if (GET_MODE_FBIT (mode) > GET_MODE_FBIT (a->mode))
 816     {
 817       /* Left shift a to temp_high, temp_low based on a->mode.  */
 818       double_int temp_high, temp_low;
 819       int amount = GET_MODE_FBIT (mode) - GET_MODE_FBIT (a->mode);
 820       temp_low = a->data.lshift (amount,
 821                                  HOST_BITS_PER_DOUBLE_INT,
 822                                  SIGNED_FIXED_POINT_MODE_P (a->mode));
 823       /* Logical shift right to temp_high.  */
 824       temp_high = a->data.llshift (amount - HOST_BITS_PER_DOUBLE_INT,
 825                      HOST_BITS_PER_DOUBLE_INT);
 826       if (SIGNED_FIXED_POINT_MODE_P (a->mode)
 827           && a->data.high < 0) /* Signed-extend temp_high.  */
 828         temp_high = temp_high.sext (amount);
 829       f->mode = mode;
 830       f->data = temp_low;
 831       if (SIGNED_FIXED_POINT_MODE_P (a->mode) ==
 832           SIGNED_FIXED_POINT_MODE_P (f->mode))
 833         overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low, &f->data,
 834                                       sat_p);
 835       else
 836         {
 837           /* Take care of the cases when converting between signed and
 838              unsigned.  */
 839           if (SIGNED_FIXED_POINT_MODE_P (a->mode))
 840             {
 841               /* Signed -> Unsigned.  */
 842               if (a->data.high < 0)
 843                 {
 844                   if (sat_p)
 845                     {
 846                       f->data.low = 0;  /* Set to zero.  */
 847                       f->data.high = 0;  /* Set to zero.  */
 848                     }
 849                   else
 850                     overflow_p = true;
 851                 }
 852               else
 853                 overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
 854                                               &f->data, sat_p);
 855             }
 856           else
 857             {
 858               /* Unsigned -> Signed.  */
 859               if (temp_high.high < 0)
 860                 {
 861                   if (sat_p)
 862                     {
 863                       /* Set to maximum.  */
 864                       f->data.low = -1;  /* Set to all ones.  */
 865                       f->data.high = -1;  /* Set to all ones.  */
 866                       f->data = f->data.zext (GET_MODE_FBIT (f->mode)
 867                                                 + GET_MODE_IBIT (f->mode));
 868                                                 /* Clear the sign.  */
 869                     }
 870                   else
 871                     overflow_p = true;
 872                 }
 873               else
 874                 overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
 875                                               &f->data, sat_p);
 876             }
 877         }
 878     }
 879   else
 880     {
 881       /* Right shift a to temp based on a->mode.  */
 882       double_int temp;
 883       temp = a->data.lshift (GET_MODE_FBIT (mode) - GET_MODE_FBIT (a->mode),
 884                              HOST_BITS_PER_DOUBLE_INT,
 885                              SIGNED_FIXED_POINT_MODE_P (a->mode));
 886       f->mode = mode;
 887       f->data = temp;
 888       if (SIGNED_FIXED_POINT_MODE_P (a->mode) ==
 889           SIGNED_FIXED_POINT_MODE_P (f->mode))
 890         overflow_p = fixed_saturate1 (f->mode, f->data, &f->data, sat_p);
 891       else
 892         {
 893           /* Take care of the cases when converting between signed and
 894              unsigned.  */
 895           if (SIGNED_FIXED_POINT_MODE_P (a->mode))
 896             {
 897               /* Signed -> Unsigned.  */
 898               if (a->data.high < 0)
 899                 {
 900                   if (sat_p)
 901                     {
 902                       f->data.low = 0;  /* Set to zero.  */
 903                       f->data.high = 0;  /* Set to zero.  */
 904                     }
 905                   else
 906                     overflow_p = true;
 907                 }
 908               else
 909                 overflow_p = fixed_saturate1 (f->mode, f->data, &f->data,
 910                                               sat_p);
 911             }
 912           else
 913             {
 914               /* Unsigned -> Signed.  */
 915               if (temp.high < 0)
 916                 {
 917                   if (sat_p)
 918                     {
 919                       /* Set to maximum.  */
 920                       f->data.low = -1;  /* Set to all ones.  */
 921                       f->data.high = -1;  /* Set to all ones.  */
 922                       f->data = f->data.zext (GET_MODE_FBIT (f->mode)
 923                                                 + GET_MODE_IBIT (f->mode));
 924                                                 /* Clear the sign.  */
 925                     }
 926                   else
 927                     overflow_p = true;
 928                 }
 929               else
 930                 overflow_p = fixed_saturate1 (f->mode, f->data, &f->data,
 931                                               sat_p);
 932             }
 933         }
 934     }
 935
 936   f->data = f->data.ext (SIGNED_FIXED_POINT_MODE_P (f->mode)
 937                             + GET_MODE_FBIT (f->mode)
 938                             + GET_MODE_IBIT (f->mode),
 939                             UNSIGNED_FIXED_POINT_MODE_P (f->mode));
 940   return overflow_p;
 941 }
 942
 943 /* Convert to a new fixed-point mode from an integer.
 944    If UNSIGNED_P, this integer is unsigned.
 945    If SAT_P, saturate the result to the max or the min.
 946    Return true, if !SAT_P and overflow.  */
 947
 948 bool
 949 fixed_convert_from_int (FIXED_VALUE_TYPE *f, scalar_mode mode,
 950                         double_int a, bool unsigned_p, bool sat_p)
 951 {
 952   bool overflow_p = false;
 953   /* Left shift a to temp_high, temp_low.  */
 954   double_int temp_high, temp_low;
 955   int amount = GET_MODE_FBIT (mode);
 956   if (amount == HOST_BITS_PER_DOUBLE_INT)
 957     {
 958        temp_high = a;
 959        temp_low.low = 0;
 960        temp_low.high = 0;
 961     }
 962   else
 963     {
 964       temp_low = a.llshift (amount, HOST_BITS_PER_DOUBLE_INT);
 965
 966       /* Logical shift right to temp_high.  */
 967       temp_high = a.llshift (amount - HOST_BITS_PER_DOUBLE_INT,
 968                      HOST_BITS_PER_DOUBLE_INT);
 969     }
 970   if (!unsigned_p && a.high < 0) /* Signed-extend temp_high.  */
 971     temp_high = temp_high.sext (amount);
 972
 973   f->mode = mode;
 974   f->data = temp_low;
 975
 976   if (unsigned_p == UNSIGNED_FIXED_POINT_MODE_P (f->mode))
 977     overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low, &f->data,
 978                                   sat_p);
 979   else
 980     {
 981       /* Take care of the cases when converting between signed and unsigned.  */
 982       if (!unsigned_p)
 983         {
 984           /* Signed -> Unsigned.  */
 985           if (a.high < 0)
 986             {
 987               if (sat_p)
 988                 {
 989                   f->data.low = 0;  /* Set to zero.  */
 990                   f->data.high = 0;  /* Set to zero.  */
 991                 }
 992               else
 993                 overflow_p = true;
 994             }
 995           else
 996             overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
 997                                           &f->data, sat_p);
 998         }
 999       else
1000         {
1001           /* Unsigned -> Signed.  */
1002           if (temp_high.high < 0)
1003             {
1004               if (sat_p)
1005                 {
1006                   /* Set to maximum.  */
1007                   f->data.low = -1;  /* Set to all ones.  */
1008                   f->data.high = -1;  /* Set to all ones.  */
1009                   f->data = f->data.zext (GET_MODE_FBIT (f->mode)
1010                                             + GET_MODE_IBIT (f->mode));
1011                                             /* Clear the sign.  */
1012                 }
1013               else
1014                 overflow_p = true;
1015             }
1016           else
1017             overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
1018                                           &f->data, sat_p);
1019         }
1020     }
1021   f->data = f->data.ext (SIGNED_FIXED_POINT_MODE_P (f->mode)
1022                             + GET_MODE_FBIT (f->mode)
1023                             + GET_MODE_IBIT (f->mode),
1024                             UNSIGNED_FIXED_POINT_MODE_P (f->mode));
1025   return overflow_p;
1026 }
1027
1028 /* Convert to a new fixed-point mode from a real.
1029    If SAT_P, saturate the result to the max or the min.
1030    Return true, if !SAT_P and overflow.  */
1031
1032 bool
1033 fixed_convert_from_real (FIXED_VALUE_TYPE *f, scalar_mode mode,
1034                          const REAL_VALUE_TYPE *a, bool sat_p)
1035 {
1036   bool overflow_p = false;
1037   REAL_VALUE_TYPE real_value, fixed_value, base_value;
1038   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (mode);
1039   int i_f_bits = GET_MODE_IBIT (mode) + GET_MODE_FBIT (mode);
1040   unsigned int fbit = GET_MODE_FBIT (mode);
1041   enum fixed_value_range_code temp;
1042   bool fail;
1043
1044   real_value = *a;
1045   f->mode = mode;
1046   real_2expN (&base_value, fbit, VOIDmode);
1047   real_arithmetic (&fixed_value, MULT_EXPR, &real_value, &base_value);
1048
1049   wide_int w = real_to_integer (&fixed_value, &fail,
1050                                 GET_MODE_PRECISION (mode));
1051   f->data.low = w.ulow ();
1052   f->data.high = w.elt (1);
1053   temp = check_real_for_fixed_mode (&real_value, mode);
1054   if (temp == FIXED_UNDERFLOW) /* Minimum.  */
1055     {
1056       if (sat_p)
1057         {
1058           if (unsigned_p)
1059             {
1060               f->data.low = 0;
1061               f->data.high = 0;
1062             }
1063           else
1064             {
1065               f->data.low = 1;
1066               f->data.high = 0;
1067               f->data = f->data.alshift (i_f_bits, HOST_BITS_PER_DOUBLE_INT);
1068               f->data = f->data.sext (1 + i_f_bits);
1069             }
1070         }
1071       else
1072         overflow_p = true;
1073     }
1074   else if (temp == FIXED_GT_MAX_EPS || temp == FIXED_MAX_EPS) /* Maximum.  */
1075     {
1076       if (sat_p)
1077         {
1078           f->data.low = -1;
1079           f->data.high = -1;
1080           f->data = f->data.zext (i_f_bits);
1081         }
1082       else
1083         overflow_p = true;
1084     }
1085   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
1086   return overflow_p;
1087 }
1088
1089 /* Convert to a new real mode from a fixed-point.  */
1090
1091 void
1092 real_convert_from_fixed (REAL_VALUE_TYPE *r, scalar_mode mode,
1093                          const FIXED_VALUE_TYPE *f)
1094 {
1095   REAL_VALUE_TYPE base_value, fixed_value, real_value;
1096
1097   signop sgn = UNSIGNED_FIXED_POINT_MODE_P (f->mode) ? UNSIGNED : SIGNED;
1098   real_2expN (&base_value, GET_MODE_FBIT (f->mode), VOIDmode);
1099   real_from_integer (&fixed_value, VOIDmode,
1100                      wide_int::from (f->data, GET_MODE_PRECISION (f->mode),
1101                                      sgn), sgn);
1102   real_arithmetic (&real_value, RDIV_EXPR, &fixed_value, &base_value);
1103   real_convert (r, mode, &real_value);
1104 }
1105
1106 /* Determine whether a fixed-point value F is negative.  */
1107
1108 bool
1109 fixed_isneg (const FIXED_VALUE_TYPE *f)
1110 {
1111   if (SIGNED_FIXED_POINT_MODE_P (f->mode))
1112     {
1113       int i_f_bits = GET_MODE_IBIT (f->mode) + GET_MODE_FBIT (f->mode);
1114       int sign_bit = get_fixed_sign_bit (f->data, i_f_bits);
1115       if (sign_bit == 1)
1116         return true;
1117     }
1118
1119   return false;
1120 }