gcc/fixed-value.c

   1 /* Fixed-point arithmetic support.
   2    Copyright (C) 2006-2019 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   return false;
 760 }
 761
 762 /* Compare fixed-point values by tree_code.
 763    Note that OP0 and OP1 must have the same mode.  */
 764
 765 bool
 766 fixed_compare (int icode, const FIXED_VALUE_TYPE *op0,
 767                const FIXED_VALUE_TYPE *op1)
 768 {
 769   enum tree_code code = (enum tree_code) icode;
 770   gcc_assert (op0->mode == op1->mode);
 771
 772   switch (code)
 773     {
 774     case NE_EXPR:
 775       return op0->data != op1->data;
 776
 777     case EQ_EXPR:
 778       return op0->data == op1->data;
 779
 780     case LT_EXPR:
 781       return op0->data.cmp (op1->data,
 782                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) == -1;
 783
 784     case LE_EXPR:
 785       return op0->data.cmp (op1->data,
 786                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) != 1;
 787
 788     case GT_EXPR:
 789       return op0->data.cmp (op1->data,
 790                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) == 1;
 791
 792     case GE_EXPR:
 793       return op0->data.cmp (op1->data,
 794                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) != -1;
 795
 796     default:
 797       gcc_unreachable ();
 798     }
 799 }
 800
 801 /* Extend or truncate to a new mode.
 802    If SAT_P, saturate the result to the max or the min.
 803    Return true, if !SAT_P and overflow.  */
 804
 805 bool
 806 fixed_convert (FIXED_VALUE_TYPE *f, scalar_mode mode,
 807                const FIXED_VALUE_TYPE *a, bool sat_p)
 808 {
 809   bool overflow_p = false;
 810   if (mode == a->mode)
 811     {
 812       *f = *a;
 813       return overflow_p;
 814     }
 815
 816   if (GET_MODE_FBIT (mode) > GET_MODE_FBIT (a->mode))
 817     {
 818       /* Left shift a to temp_high, temp_low based on a->mode.  */
 819       double_int temp_high, temp_low;
 820       int amount = GET_MODE_FBIT (mode) - GET_MODE_FBIT (a->mode);
 821       temp_low = a->data.lshift (amount,
 822                                  HOST_BITS_PER_DOUBLE_INT,
 823                                  SIGNED_FIXED_POINT_MODE_P (a->mode));
 824       /* Logical shift right to temp_high.  */
 825       temp_high = a->data.llshift (amount - HOST_BITS_PER_DOUBLE_INT,
 826                      HOST_BITS_PER_DOUBLE_INT);
 827       if (SIGNED_FIXED_POINT_MODE_P (a->mode)
 828           && a->data.high < 0) /* Signed-extend temp_high.  */
 829         temp_high = temp_high.sext (amount);
 830       f->mode = mode;
 831       f->data = temp_low;
 832       if (SIGNED_FIXED_POINT_MODE_P (a->mode) ==
 833           SIGNED_FIXED_POINT_MODE_P (f->mode))
 834         overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low, &f->data,
 835                                       sat_p);
 836       else
 837         {
 838           /* Take care of the cases when converting between signed and
 839              unsigned.  */
 840           if (SIGNED_FIXED_POINT_MODE_P (a->mode))
 841             {
 842               /* Signed -> Unsigned.  */
 843               if (a->data.high < 0)
 844                 {
 845                   if (sat_p)
 846                     {
 847                       f->data.low = 0;  /* Set to zero.  */
 848                       f->data.high = 0;  /* Set to zero.  */
 849                     }
 850                   else
 851                     overflow_p = true;
 852                 }
 853               else
 854                 overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
 855                                               &f->data, sat_p);
 856             }
 857           else
 858             {
 859               /* Unsigned -> Signed.  */
 860               if (temp_high.high < 0)
 861                 {
 862                   if (sat_p)
 863                     {
 864                       /* Set to maximum.  */
 865                       f->data.low = -1;  /* Set to all ones.  */
 866                       f->data.high = -1;  /* Set to all ones.  */
 867                       f->data = f->data.zext (GET_MODE_FBIT (f->mode)
 868                                                 + GET_MODE_IBIT (f->mode));
 869                                                 /* Clear the sign.  */
 870                     }
 871                   else
 872                     overflow_p = true;
 873                 }
 874               else
 875                 overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
 876                                               &f->data, sat_p);
 877             }
 878         }
 879     }
 880   else
 881     {
 882       /* Right shift a to temp based on a->mode.  */
 883       double_int temp;
 884       temp = a->data.lshift (GET_MODE_FBIT (mode) - GET_MODE_FBIT (a->mode),
 885                              HOST_BITS_PER_DOUBLE_INT,
 886                              SIGNED_FIXED_POINT_MODE_P (a->mode));
 887       f->mode = mode;
 888       f->data = temp;
 889       if (SIGNED_FIXED_POINT_MODE_P (a->mode) ==
 890           SIGNED_FIXED_POINT_MODE_P (f->mode))
 891         overflow_p = fixed_saturate1 (f->mode, f->data, &f->data, sat_p);
 892       else
 893         {
 894           /* Take care of the cases when converting between signed and
 895              unsigned.  */
 896           if (SIGNED_FIXED_POINT_MODE_P (a->mode))
 897             {
 898               /* Signed -> Unsigned.  */
 899               if (a->data.high < 0)
 900                 {
 901                   if (sat_p)
 902                     {
 903                       f->data.low = 0;  /* Set to zero.  */
 904                       f->data.high = 0;  /* Set to zero.  */
 905                     }
 906                   else
 907                     overflow_p = true;
 908                 }
 909               else
 910                 overflow_p = fixed_saturate1 (f->mode, f->data, &f->data,
 911                                               sat_p);
 912             }
 913           else
 914             {
 915               /* Unsigned -> Signed.  */
 916               if (temp.high < 0)
 917                 {
 918                   if (sat_p)
 919                     {
 920                       /* Set to maximum.  */
 921                       f->data.low = -1;  /* Set to all ones.  */
 922                       f->data.high = -1;  /* Set to all ones.  */
 923                       f->data = f->data.zext (GET_MODE_FBIT (f->mode)
 924                                                 + GET_MODE_IBIT (f->mode));
 925                                                 /* Clear the sign.  */
 926                     }
 927                   else
 928                     overflow_p = true;
 929                 }
 930               else
 931                 overflow_p = fixed_saturate1 (f->mode, f->data, &f->data,
 932                                               sat_p);
 933             }
 934         }
 935     }
 936
 937   f->data = f->data.ext (SIGNED_FIXED_POINT_MODE_P (f->mode)
 938                             + GET_MODE_FBIT (f->mode)
 939                             + GET_MODE_IBIT (f->mode),
 940                             UNSIGNED_FIXED_POINT_MODE_P (f->mode));
 941   return overflow_p;
 942 }
 943
 944 /* Convert to a new fixed-point mode from an integer.
 945    If UNSIGNED_P, this integer is unsigned.
 946    If SAT_P, saturate the result to the max or the min.
 947    Return true, if !SAT_P and overflow.  */
 948
 949 bool
 950 fixed_convert_from_int (FIXED_VALUE_TYPE *f, scalar_mode mode,
 951                         double_int a, bool unsigned_p, bool sat_p)
 952 {
 953   bool overflow_p = false;
 954   /* Left shift a to temp_high, temp_low.  */
 955   double_int temp_high, temp_low;
 956   int amount = GET_MODE_FBIT (mode);
 957   if (amount == HOST_BITS_PER_DOUBLE_INT)
 958     {
 959        temp_high = a;
 960        temp_low.low = 0;
 961        temp_low.high = 0;
 962     }
 963   else
 964     {
 965       temp_low = a.llshift (amount, HOST_BITS_PER_DOUBLE_INT);
 966
 967       /* Logical shift right to temp_high.  */
 968       temp_high = a.llshift (amount - HOST_BITS_PER_DOUBLE_INT,
 969                      HOST_BITS_PER_DOUBLE_INT);
 970     }
 971   if (!unsigned_p && a.high < 0) /* Signed-extend temp_high.  */
 972     temp_high = temp_high.sext (amount);
 973
 974   f->mode = mode;
 975   f->data = temp_low;
 976
 977   if (unsigned_p == UNSIGNED_FIXED_POINT_MODE_P (f->mode))
 978     overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low, &f->data,
 979                                   sat_p);
 980   else
 981     {
 982       /* Take care of the cases when converting between signed and unsigned.  */
 983       if (!unsigned_p)
 984         {
 985           /* Signed -> Unsigned.  */
 986           if (a.high < 0)
 987             {
 988               if (sat_p)
 989                 {
 990                   f->data.low = 0;  /* Set to zero.  */
 991                   f->data.high = 0;  /* Set to zero.  */
 992                 }
 993               else
 994                 overflow_p = true;
 995             }
 996           else
 997             overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
 998                                           &f->data, sat_p);
 999         }
1000       else
1001         {
1002           /* Unsigned -> Signed.  */
1003           if (temp_high.high < 0)
1004             {
1005               if (sat_p)
1006                 {
1007                   /* Set to maximum.  */
1008                   f->data.low = -1;  /* Set to all ones.  */
1009                   f->data.high = -1;  /* Set to all ones.  */
1010                   f->data = f->data.zext (GET_MODE_FBIT (f->mode)
1011                                             + GET_MODE_IBIT (f->mode));
1012                                             /* Clear the sign.  */
1013                 }
1014               else
1015                 overflow_p = true;
1016             }
1017           else
1018             overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
1019                                           &f->data, sat_p);
1020         }
1021     }
1022   f->data = f->data.ext (SIGNED_FIXED_POINT_MODE_P (f->mode)
1023                             + GET_MODE_FBIT (f->mode)
1024                             + GET_MODE_IBIT (f->mode),
1025                             UNSIGNED_FIXED_POINT_MODE_P (f->mode));
1026   return overflow_p;
1027 }
1028
1029 /* Convert to a new fixed-point mode from a real.
1030    If SAT_P, saturate the result to the max or the min.
1031    Return true, if !SAT_P and overflow.  */
1032
1033 bool
1034 fixed_convert_from_real (FIXED_VALUE_TYPE *f, scalar_mode mode,
1035                          const REAL_VALUE_TYPE *a, bool sat_p)
1036 {
1037   bool overflow_p = false;
1038   REAL_VALUE_TYPE real_value, fixed_value, base_value;
1039   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (mode);
1040   int i_f_bits = GET_MODE_IBIT (mode) + GET_MODE_FBIT (mode);
1041   unsigned int fbit = GET_MODE_FBIT (mode);
1042   enum fixed_value_range_code temp;
1043   bool fail;
1044
1045   real_value = *a;
1046   f->mode = mode;
1047   real_2expN (&base_value, fbit, VOIDmode);
1048   real_arithmetic (&fixed_value, MULT_EXPR, &real_value, &base_value);
1049
1050   wide_int w = real_to_integer (&fixed_value, &fail,
1051                                 GET_MODE_PRECISION (mode));
1052   f->data.low = w.ulow ();
1053   f->data.high = w.elt (1);
1054   temp = check_real_for_fixed_mode (&real_value, mode);
1055   if (temp == FIXED_UNDERFLOW) /* Minimum.  */
1056     {
1057       if (sat_p)
1058         {
1059           if (unsigned_p)
1060             {
1061               f->data.low = 0;
1062               f->data.high = 0;
1063             }
1064           else
1065             {
1066               f->data.low = 1;
1067               f->data.high = 0;
1068               f->data = f->data.alshift (i_f_bits, HOST_BITS_PER_DOUBLE_INT);
1069               f->data = f->data.sext (1 + i_f_bits);
1070             }
1071         }
1072       else
1073         overflow_p = true;
1074     }
1075   else if (temp == FIXED_GT_MAX_EPS || temp == FIXED_MAX_EPS) /* Maximum.  */
1076     {
1077       if (sat_p)
1078         {
1079           f->data.low = -1;
1080           f->data.high = -1;
1081           f->data = f->data.zext (i_f_bits);
1082         }
1083       else
1084         overflow_p = true;
1085     }
1086   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
1087   return overflow_p;
1088 }
1089
1090 /* Convert to a new real mode from a fixed-point.  */
1091
1092 void
1093 real_convert_from_fixed (REAL_VALUE_TYPE *r, scalar_mode mode,
1094                          const FIXED_VALUE_TYPE *f)
1095 {
1096   REAL_VALUE_TYPE base_value, fixed_value, real_value;
1097
1098   signop sgn = UNSIGNED_FIXED_POINT_MODE_P (f->mode) ? UNSIGNED : SIGNED;
1099   real_2expN (&base_value, GET_MODE_FBIT (f->mode), VOIDmode);
1100   real_from_integer (&fixed_value, VOIDmode,
1101                      wide_int::from (f->data, GET_MODE_PRECISION (f->mode),
1102                                      sgn), sgn);
1103   real_arithmetic (&real_value, RDIV_EXPR, &fixed_value, &base_value);
1104   real_convert (r, mode, &real_value);
1105 }
1106
1107 /* Determine whether a fixed-point value F is negative.  */
1108
1109 bool
1110 fixed_isneg (const FIXED_VALUE_TYPE *f)
1111 {
1112   if (SIGNED_FIXED_POINT_MODE_P (f->mode))
1113     {
1114       int i_f_bits = GET_MODE_IBIT (f->mode) + GET_MODE_FBIT (f->mode);
1115       int sign_bit = get_fixed_sign_bit (f->data, i_f_bits);
1116       if (sign_bit == 1)
1117         return true;
1118     }
1119
1120   return false;
1121 }