gcc/fixed-value.c

   1 /* Fixed-point arithmetic support.
   2    Copyright (C) 2006-2016 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, machine_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, machine_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.elt (0);
 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       break;
 734
 735     case PLUS_EXPR:
 736       gcc_assert (op0->mode == op1->mode);
 737       return do_fixed_add (f, op0, op1, false, sat_p);
 738       break;
 739
 740     case MINUS_EXPR:
 741       gcc_assert (op0->mode == op1->mode);
 742       return do_fixed_add (f, op0, op1, true, sat_p);
 743       break;
 744
 745     case MULT_EXPR:
 746       gcc_assert (op0->mode == op1->mode);
 747       return do_fixed_multiply (f, op0, op1, sat_p);
 748       break;
 749
 750     case TRUNC_DIV_EXPR:
 751       gcc_assert (op0->mode == op1->mode);
 752       return do_fixed_divide (f, op0, op1, sat_p);
 753       break;
 754
 755     case LSHIFT_EXPR:
 756       return do_fixed_shift (f, op0, op1, true, sat_p);
 757       break;
 758
 759     case RSHIFT_EXPR:
 760       return do_fixed_shift (f, op0, op1, false, sat_p);
 761       break;
 762
 763     default:
 764       gcc_unreachable ();
 765     }
 766   return false;
 767 }
 768
 769 /* Compare fixed-point values by tree_code.
 770    Note that OP0 and OP1 must have the same mode.  */
 771
 772 bool
 773 fixed_compare (int icode, const FIXED_VALUE_TYPE *op0,
 774                const FIXED_VALUE_TYPE *op1)
 775 {
 776   enum tree_code code = (enum tree_code) icode;
 777   gcc_assert (op0->mode == op1->mode);
 778
 779   switch (code)
 780     {
 781     case NE_EXPR:
 782       return op0->data != op1->data;
 783
 784     case EQ_EXPR:
 785       return op0->data == op1->data;
 786
 787     case LT_EXPR:
 788       return op0->data.cmp (op1->data,
 789                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) == -1;
 790
 791     case LE_EXPR:
 792       return op0->data.cmp (op1->data,
 793                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) != 1;
 794
 795     case GT_EXPR:
 796       return op0->data.cmp (op1->data,
 797                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) == 1;
 798
 799     case GE_EXPR:
 800       return op0->data.cmp (op1->data,
 801                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) != -1;
 802
 803     default:
 804       gcc_unreachable ();
 805     }
 806 }
 807
 808 /* Extend or truncate to a new mode.
 809    If SAT_P, saturate the result to the max or the min.
 810    Return true, if !SAT_P and overflow.  */
 811
 812 bool
 813 fixed_convert (FIXED_VALUE_TYPE *f, machine_mode mode,
 814                const FIXED_VALUE_TYPE *a, bool sat_p)
 815 {
 816   bool overflow_p = false;
 817   if (mode == a->mode)
 818     {
 819       *f = *a;
 820       return overflow_p;
 821     }
 822
 823   if (GET_MODE_FBIT (mode) > GET_MODE_FBIT (a->mode))
 824     {
 825       /* Left shift a to temp_high, temp_low based on a->mode.  */
 826       double_int temp_high, temp_low;
 827       int amount = GET_MODE_FBIT (mode) - GET_MODE_FBIT (a->mode);
 828       temp_low = a->data.lshift (amount,
 829                                  HOST_BITS_PER_DOUBLE_INT,
 830                                  SIGNED_FIXED_POINT_MODE_P (a->mode));
 831       /* Logical shift right to temp_high.  */
 832       temp_high = a->data.llshift (amount - HOST_BITS_PER_DOUBLE_INT,
 833                      HOST_BITS_PER_DOUBLE_INT);
 834       if (SIGNED_FIXED_POINT_MODE_P (a->mode)
 835           && a->data.high < 0) /* Signed-extend temp_high.  */
 836         temp_high = temp_high.sext (amount);
 837       f->mode = mode;
 838       f->data = temp_low;
 839       if (SIGNED_FIXED_POINT_MODE_P (a->mode) ==
 840           SIGNED_FIXED_POINT_MODE_P (f->mode))
 841         overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low, &f->data,
 842                                       sat_p);
 843       else
 844         {
 845           /* Take care of the cases when converting between signed and
 846              unsigned.  */
 847           if (SIGNED_FIXED_POINT_MODE_P (a->mode))
 848             {
 849               /* Signed -> Unsigned.  */
 850               if (a->data.high < 0)
 851                 {
 852                   if (sat_p)
 853                     {
 854                       f->data.low = 0;  /* Set to zero.  */
 855                       f->data.high = 0;  /* Set to zero.  */
 856                     }
 857                   else
 858                     overflow_p = true;
 859                 }
 860               else
 861                 overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
 862                                               &f->data, sat_p);
 863             }
 864           else
 865             {
 866               /* Unsigned -> Signed.  */
 867               if (temp_high.high < 0)
 868                 {
 869                   if (sat_p)
 870                     {
 871                       /* Set to maximum.  */
 872                       f->data.low = -1;  /* Set to all ones.  */
 873                       f->data.high = -1;  /* Set to all ones.  */
 874                       f->data = f->data.zext (GET_MODE_FBIT (f->mode)
 875                                                 + GET_MODE_IBIT (f->mode));
 876                                                 /* Clear the sign.  */
 877                     }
 878                   else
 879                     overflow_p = true;
 880                 }
 881               else
 882                 overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
 883                                               &f->data, sat_p);
 884             }
 885         }
 886     }
 887   else
 888     {
 889       /* Right shift a to temp based on a->mode.  */
 890       double_int temp;
 891       temp = a->data.lshift (GET_MODE_FBIT (mode) - GET_MODE_FBIT (a->mode),
 892                              HOST_BITS_PER_DOUBLE_INT,
 893                              SIGNED_FIXED_POINT_MODE_P (a->mode));
 894       f->mode = mode;
 895       f->data = temp;
 896       if (SIGNED_FIXED_POINT_MODE_P (a->mode) ==
 897           SIGNED_FIXED_POINT_MODE_P (f->mode))
 898         overflow_p = fixed_saturate1 (f->mode, f->data, &f->data, sat_p);
 899       else
 900         {
 901           /* Take care of the cases when converting between signed and
 902              unsigned.  */
 903           if (SIGNED_FIXED_POINT_MODE_P (a->mode))
 904             {
 905               /* Signed -> Unsigned.  */
 906               if (a->data.high < 0)
 907                 {
 908                   if (sat_p)
 909                     {
 910                       f->data.low = 0;  /* Set to zero.  */
 911                       f->data.high = 0;  /* Set to zero.  */
 912                     }
 913                   else
 914                     overflow_p = true;
 915                 }
 916               else
 917                 overflow_p = fixed_saturate1 (f->mode, f->data, &f->data,
 918                                               sat_p);
 919             }
 920           else
 921             {
 922               /* Unsigned -> Signed.  */
 923               if (temp.high < 0)
 924                 {
 925                   if (sat_p)
 926                     {
 927                       /* Set to maximum.  */
 928                       f->data.low = -1;  /* Set to all ones.  */
 929                       f->data.high = -1;  /* Set to all ones.  */
 930                       f->data = f->data.zext (GET_MODE_FBIT (f->mode)
 931                                                 + GET_MODE_IBIT (f->mode));
 932                                                 /* Clear the sign.  */
 933                     }
 934                   else
 935                     overflow_p = true;
 936                 }
 937               else
 938                 overflow_p = fixed_saturate1 (f->mode, f->data, &f->data,
 939                                               sat_p);
 940             }
 941         }
 942     }
 943
 944   f->data = f->data.ext (SIGNED_FIXED_POINT_MODE_P (f->mode)
 945                             + GET_MODE_FBIT (f->mode)
 946                             + GET_MODE_IBIT (f->mode),
 947                             UNSIGNED_FIXED_POINT_MODE_P (f->mode));
 948   return overflow_p;
 949 }
 950
 951 /* Convert to a new fixed-point mode from an integer.
 952    If UNSIGNED_P, this integer is unsigned.
 953    If SAT_P, saturate the result to the max or the min.
 954    Return true, if !SAT_P and overflow.  */
 955
 956 bool
 957 fixed_convert_from_int (FIXED_VALUE_TYPE *f, machine_mode mode,
 958                         double_int a, bool unsigned_p, bool sat_p)
 959 {
 960   bool overflow_p = false;
 961   /* Left shift a to temp_high, temp_low.  */
 962   double_int temp_high, temp_low;
 963   int amount = GET_MODE_FBIT (mode);
 964   if (amount == HOST_BITS_PER_DOUBLE_INT)
 965     {
 966        temp_high = a;
 967        temp_low.low = 0;
 968        temp_low.high = 0;
 969     }
 970   else
 971     {
 972       temp_low = a.llshift (amount, HOST_BITS_PER_DOUBLE_INT);
 973
 974       /* Logical shift right to temp_high.  */
 975       temp_high = a.llshift (amount - HOST_BITS_PER_DOUBLE_INT,
 976                      HOST_BITS_PER_DOUBLE_INT);
 977     }
 978   if (!unsigned_p && a.high < 0) /* Signed-extend temp_high.  */
 979     temp_high = temp_high.sext (amount);
 980
 981   f->mode = mode;
 982   f->data = temp_low;
 983
 984   if (unsigned_p == UNSIGNED_FIXED_POINT_MODE_P (f->mode))
 985     overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low, &f->data,
 986                                   sat_p);
 987   else
 988     {
 989       /* Take care of the cases when converting between signed and unsigned.  */
 990       if (!unsigned_p)
 991         {
 992           /* Signed -> Unsigned.  */
 993           if (a.high < 0)
 994             {
 995               if (sat_p)
 996                 {
 997                   f->data.low = 0;  /* Set to zero.  */
 998                   f->data.high = 0;  /* Set to zero.  */
 999                 }
1000               else
1001                 overflow_p = true;
1002             }
1003           else
1004             overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
1005                                           &f->data, sat_p);
1006         }
1007       else
1008         {
1009           /* Unsigned -> Signed.  */
1010           if (temp_high.high < 0)
1011             {
1012               if (sat_p)
1013                 {
1014                   /* Set to maximum.  */
1015                   f->data.low = -1;  /* Set to all ones.  */
1016                   f->data.high = -1;  /* Set to all ones.  */
1017                   f->data = f->data.zext (GET_MODE_FBIT (f->mode)
1018                                             + GET_MODE_IBIT (f->mode));
1019                                             /* Clear the sign.  */
1020                 }
1021               else
1022                 overflow_p = true;
1023             }
1024           else
1025             overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
1026                                           &f->data, sat_p);
1027         }
1028     }
1029   f->data = f->data.ext (SIGNED_FIXED_POINT_MODE_P (f->mode)
1030                             + GET_MODE_FBIT (f->mode)
1031                             + GET_MODE_IBIT (f->mode),
1032                             UNSIGNED_FIXED_POINT_MODE_P (f->mode));
1033   return overflow_p;
1034 }
1035
1036 /* Convert to a new fixed-point mode from a real.
1037    If SAT_P, saturate the result to the max or the min.
1038    Return true, if !SAT_P and overflow.  */
1039
1040 bool
1041 fixed_convert_from_real (FIXED_VALUE_TYPE *f, machine_mode mode,
1042                          const REAL_VALUE_TYPE *a, bool sat_p)
1043 {
1044   bool overflow_p = false;
1045   REAL_VALUE_TYPE real_value, fixed_value, base_value;
1046   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (mode);
1047   int i_f_bits = GET_MODE_IBIT (mode) + GET_MODE_FBIT (mode);
1048   unsigned int fbit = GET_MODE_FBIT (mode);
1049   enum fixed_value_range_code temp;
1050   bool fail;
1051
1052   real_value = *a;
1053   f->mode = mode;
1054   real_2expN (&base_value, fbit, VOIDmode);
1055   real_arithmetic (&fixed_value, MULT_EXPR, &real_value, &base_value);
1056
1057   wide_int w = real_to_integer (&fixed_value, &fail,
1058                                 GET_MODE_PRECISION (mode));
1059   f->data.low = w.elt (0);
1060   f->data.high = w.elt (1);
1061   temp = check_real_for_fixed_mode (&real_value, mode);
1062   if (temp == FIXED_UNDERFLOW) /* Minimum.  */
1063     {
1064       if (sat_p)
1065         {
1066           if (unsigned_p)
1067             {
1068               f->data.low = 0;
1069               f->data.high = 0;
1070             }
1071           else
1072             {
1073               f->data.low = 1;
1074               f->data.high = 0;
1075               f->data = f->data.alshift (i_f_bits, HOST_BITS_PER_DOUBLE_INT);
1076               f->data = f->data.sext (1 + i_f_bits);
1077             }
1078         }
1079       else
1080         overflow_p = true;
1081     }
1082   else if (temp == FIXED_GT_MAX_EPS || temp == FIXED_MAX_EPS) /* Maximum.  */
1083     {
1084       if (sat_p)
1085         {
1086           f->data.low = -1;
1087           f->data.high = -1;
1088           f->data = f->data.zext (i_f_bits);
1089         }
1090       else
1091         overflow_p = true;
1092     }
1093   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
1094   return overflow_p;
1095 }
1096
1097 /* Convert to a new real mode from a fixed-point.  */
1098
1099 void
1100 real_convert_from_fixed (REAL_VALUE_TYPE *r, machine_mode mode,
1101                          const FIXED_VALUE_TYPE *f)
1102 {
1103   REAL_VALUE_TYPE base_value, fixed_value, real_value;
1104
1105   signop sgn = UNSIGNED_FIXED_POINT_MODE_P (f->mode) ? UNSIGNED : SIGNED;
1106   real_2expN (&base_value, GET_MODE_FBIT (f->mode), VOIDmode);
1107   real_from_integer (&fixed_value, VOIDmode,
1108                      wide_int::from (f->data, GET_MODE_PRECISION (f->mode),
1109                                      sgn), sgn);
1110   real_arithmetic (&real_value, RDIV_EXPR, &fixed_value, &base_value);
1111   real_convert (r, mode, &real_value);
1112 }
1113
1114 /* Determine whether a fixed-point value F is negative.  */
1115
1116 bool
1117 fixed_isneg (const FIXED_VALUE_TYPE *f)
1118 {
1119   if (SIGNED_FIXED_POINT_MODE_P (f->mode))
1120     {
1121       int i_f_bits = GET_MODE_IBIT (f->mode) + GET_MODE_FBIT (f->mode);
1122       int sign_bit = get_fixed_sign_bit (f->data, i_f_bits);
1123       if (sign_bit == 1)
1124         return true;
1125     }
1126
1127   return false;
1128 }