gcc/fixed-value.c

   1 /* Fixed-point arithmetic support.
   2    Copyright (C) 2006-2014 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 #include "wide-int.h"
  27
  28 /* Compare two fixed objects for bitwise identity.  */
  29
  30 bool
  31 fixed_identical (const FIXED_VALUE_TYPE *a, const FIXED_VALUE_TYPE *b)
  32 {
  33   return (a->mode == b->mode
  34           && a->data.high == b->data.high
  35           && a->data.low == b->data.low);
  36 }
  37
  38 /* Calculate a hash value.  */
  39
  40 unsigned int
  41 fixed_hash (const FIXED_VALUE_TYPE *f)
  42 {
  43   return (unsigned int) (f->data.low ^ f->data.high);
  44 }
  45
  46 /* Define the enum code for the range of the fixed-point value.  */
  47 enum fixed_value_range_code {
  48   FIXED_OK,             /* The value is within the range.  */
  49   FIXED_UNDERFLOW,      /* The value is less than the minimum.  */
  50   FIXED_GT_MAX_EPS,     /* The value is greater than the maximum, but not equal
  51                            to the maximum plus the epsilon.  */
  52   FIXED_MAX_EPS         /* The value equals the maximum plus the epsilon.  */
  53 };
  54
  55 /* Check REAL_VALUE against the range of the fixed-point mode.
  56    Return FIXED_OK, if it is within the range.
  57           FIXED_UNDERFLOW, if it is less than the minimum.
  58           FIXED_GT_MAX_EPS, if it is greater than the maximum, but not equal to
  59             the maximum plus the epsilon.
  60           FIXED_MAX_EPS, if it is equal to the maximum plus the epsilon.  */
  61
  62 static enum fixed_value_range_code
  63 check_real_for_fixed_mode (REAL_VALUE_TYPE *real_value, machine_mode mode)
  64 {
  65   REAL_VALUE_TYPE max_value, min_value, epsilon_value;
  66
  67   real_2expN (&max_value, GET_MODE_IBIT (mode), mode);
  68   real_2expN (&epsilon_value, -GET_MODE_FBIT (mode), mode);
  69
  70   if (SIGNED_FIXED_POINT_MODE_P (mode))
  71     min_value = real_value_negate (&max_value);
  72   else
  73     real_from_string (&min_value, "0.0");
  74
  75   if (real_compare (LT_EXPR, real_value, &min_value))
  76     return FIXED_UNDERFLOW;
  77   if (real_compare (EQ_EXPR, real_value, &max_value))
  78     return FIXED_MAX_EPS;
  79   real_arithmetic (&max_value, MINUS_EXPR, &max_value, &epsilon_value);
  80   if (real_compare (GT_EXPR, real_value, &max_value))
  81     return FIXED_GT_MAX_EPS;
  82   return FIXED_OK;
  83 }
  84
  85
  86 /* Construct a CONST_FIXED from a bit payload and machine mode MODE.
  87    The bits in PAYLOAD are sign-extended/zero-extended according to MODE.  */
  88
  89 FIXED_VALUE_TYPE
  90 fixed_from_double_int (double_int payload, machine_mode mode)
  91 {
  92   FIXED_VALUE_TYPE value;
  93
  94   gcc_assert (GET_MODE_BITSIZE (mode) <= HOST_BITS_PER_DOUBLE_INT);
  95
  96   if (SIGNED_SCALAR_FIXED_POINT_MODE_P (mode))
  97     value.data = payload.sext (1 + GET_MODE_IBIT (mode) + GET_MODE_FBIT (mode));
  98   else if (UNSIGNED_SCALAR_FIXED_POINT_MODE_P (mode))
  99     value.data = payload.zext (GET_MODE_IBIT (mode) + GET_MODE_FBIT (mode));
 100   else
 101     gcc_unreachable ();
 102
 103   value.mode = mode;
 104
 105   return value;
 106 }
 107
 108
 109 /* Initialize from a decimal or hexadecimal string.  */
 110
 111 void
 112 fixed_from_string (FIXED_VALUE_TYPE *f, const char *str, machine_mode mode)
 113 {
 114   REAL_VALUE_TYPE real_value, fixed_value, base_value;
 115   unsigned int fbit;
 116   enum fixed_value_range_code temp;
 117   bool fail;
 118
 119   f->mode = mode;
 120   fbit = GET_MODE_FBIT (mode);
 121
 122   real_from_string (&real_value, str);
 123   temp = check_real_for_fixed_mode (&real_value, f->mode);
 124   /* We don't want to warn the case when the _Fract value is 1.0.  */
 125   if (temp == FIXED_UNDERFLOW
 126       || temp == FIXED_GT_MAX_EPS
 127       || (temp == FIXED_MAX_EPS && ALL_ACCUM_MODE_P (f->mode)))
 128     warning (OPT_Woverflow,
 129              "large fixed-point constant implicitly truncated to fixed-point type");
 130   real_2expN (&base_value, fbit, mode);
 131   real_arithmetic (&fixed_value, MULT_EXPR, &real_value, &base_value);
 132   wide_int w = real_to_integer (&fixed_value, &fail,
 133                                 GET_MODE_PRECISION (mode));
 134   f->data.low = w.elt (0);
 135   f->data.high = w.elt (1);
 136
 137   if (temp == FIXED_MAX_EPS && ALL_FRACT_MODE_P (f->mode))
 138     {
 139       /* From the spec, we need to evaluate 1 to the maximal value.  */
 140       f->data.low = -1;
 141       f->data.high = -1;
 142       f->data = f->data.zext (GET_MODE_FBIT (f->mode)
 143                                 + GET_MODE_IBIT (f->mode));
 144     }
 145   else
 146     f->data = f->data.ext (SIGNED_FIXED_POINT_MODE_P (f->mode)
 147                               + GET_MODE_FBIT (f->mode)
 148                               + GET_MODE_IBIT (f->mode),
 149                               UNSIGNED_FIXED_POINT_MODE_P (f->mode));
 150 }
 151
 152 /* Render F as a decimal floating point constant.  */
 153
 154 void
 155 fixed_to_decimal (char *str, const FIXED_VALUE_TYPE *f_orig,
 156                   size_t buf_size)
 157 {
 158   REAL_VALUE_TYPE real_value, base_value, fixed_value;
 159
 160   signop sgn = UNSIGNED_FIXED_POINT_MODE_P (f_orig->mode) ? UNSIGNED : SIGNED;
 161   real_2expN (&base_value, GET_MODE_FBIT (f_orig->mode), f_orig->mode);
 162   real_from_integer (&real_value, VOIDmode,
 163                      wide_int::from (f_orig->data,
 164                                      GET_MODE_PRECISION (f_orig->mode), sgn),
 165                      sgn);
 166   real_arithmetic (&fixed_value, RDIV_EXPR, &real_value, &base_value);
 167   real_to_decimal (str, &fixed_value, buf_size, 0, 1);
 168 }
 169
 170 /* If SAT_P, saturate A to the maximum or the minimum, and save to *F based on
 171    the machine mode MODE.
 172    Do not modify *F otherwise.
 173    This function assumes the width of double_int is greater than the width
 174    of the fixed-point value (the sum of a possible sign bit, possible ibits,
 175    and fbits).
 176    Return true, if !SAT_P and overflow.  */
 177
 178 static bool
 179 fixed_saturate1 (machine_mode mode, double_int a, double_int *f,
 180                  bool sat_p)
 181 {
 182   bool overflow_p = false;
 183   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (mode);
 184   int i_f_bits = GET_MODE_IBIT (mode) + GET_MODE_FBIT (mode);
 185
 186   if (unsigned_p) /* Unsigned type.  */
 187     {
 188       double_int max;
 189       max.low = -1;
 190       max.high = -1;
 191       max = max.zext (i_f_bits);
 192       if (a.ugt (max))
 193         {
 194           if (sat_p)
 195             *f = max;
 196           else
 197             overflow_p = true;
 198         }
 199     }
 200   else /* Signed type.  */
 201     {
 202       double_int max, min;
 203       max.high = -1;
 204       max.low = -1;
 205       max = max.zext (i_f_bits);
 206       min.high = 0;
 207       min.low = 1;
 208       min = min.alshift (i_f_bits, HOST_BITS_PER_DOUBLE_INT);
 209       min = min.sext (1 + i_f_bits);
 210       if (a.sgt (max))
 211         {
 212           if (sat_p)
 213             *f = max;
 214           else
 215             overflow_p = true;
 216         }
 217       else if (a.slt (min))
 218         {
 219           if (sat_p)
 220             *f = min;
 221           else
 222             overflow_p = true;
 223         }
 224     }
 225   return overflow_p;
 226 }
 227
 228 /* If SAT_P, saturate {A_HIGH, A_LOW} to the maximum or the minimum, and
 229    save to *F based on the machine mode MODE.
 230    Do not modify *F otherwise.
 231    This function assumes the width of two double_int is greater than the width
 232    of the fixed-point value (the sum of a possible sign bit, possible ibits,
 233    and fbits).
 234    Return true, if !SAT_P and overflow.  */
 235
 236 static bool
 237 fixed_saturate2 (machine_mode mode, double_int a_high, double_int a_low,
 238                  double_int *f, bool sat_p)
 239 {
 240   bool overflow_p = false;
 241   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (mode);
 242   int i_f_bits = GET_MODE_IBIT (mode) + GET_MODE_FBIT (mode);
 243
 244   if (unsigned_p) /* Unsigned type.  */
 245     {
 246       double_int max_r, max_s;
 247       max_r.high = 0;
 248       max_r.low = 0;
 249       max_s.high = -1;
 250       max_s.low = -1;
 251       max_s = max_s.zext (i_f_bits);
 252       if (a_high.ugt (max_r)
 253           || (a_high == max_r &&
 254               a_low.ugt (max_s)))
 255         {
 256           if (sat_p)
 257             *f = max_s;
 258           else
 259             overflow_p = true;
 260         }
 261     }
 262   else /* Signed type.  */
 263     {
 264       double_int max_r, max_s, min_r, min_s;
 265       max_r.high = 0;
 266       max_r.low = 0;
 267       max_s.high = -1;
 268       max_s.low = -1;
 269       max_s = max_s.zext (i_f_bits);
 270       min_r.high = -1;
 271       min_r.low = -1;
 272       min_s.high = 0;
 273       min_s.low = 1;
 274       min_s = min_s.alshift (i_f_bits, HOST_BITS_PER_DOUBLE_INT);
 275       min_s = min_s.sext (1 + i_f_bits);
 276       if (a_high.sgt (max_r)
 277           || (a_high == max_r &&
 278               a_low.ugt (max_s)))
 279         {
 280           if (sat_p)
 281             *f = max_s;
 282           else
 283             overflow_p = true;
 284         }
 285       else if (a_high.slt (min_r)
 286                || (a_high == min_r &&
 287                    a_low.ult (min_s)))
 288         {
 289           if (sat_p)
 290             *f = min_s;
 291           else
 292             overflow_p = true;
 293         }
 294     }
 295   return overflow_p;
 296 }
 297
 298 /* Return the sign bit based on I_F_BITS.  */
 299
 300 static inline int
 301 get_fixed_sign_bit (double_int a, int i_f_bits)
 302 {
 303   if (i_f_bits < HOST_BITS_PER_WIDE_INT)
 304     return (a.low >> i_f_bits) & 1;
 305   else
 306     return (a.high >> (i_f_bits - HOST_BITS_PER_WIDE_INT)) & 1;
 307 }
 308
 309 /* Calculate F = A + (SUBTRACT_P ? -B : B).
 310    If SAT_P, saturate the result to the max or the min.
 311    Return true, if !SAT_P and overflow.  */
 312
 313 static bool
 314 do_fixed_add (FIXED_VALUE_TYPE *f, const FIXED_VALUE_TYPE *a,
 315               const FIXED_VALUE_TYPE *b, bool subtract_p, bool sat_p)
 316 {
 317   bool overflow_p = false;
 318   bool unsigned_p;
 319   double_int temp;
 320   int i_f_bits;
 321
 322   /* This was a conditional expression but it triggered a bug in
 323      Sun C 5.5.  */
 324   if (subtract_p)
 325     temp = -b->data;
 326   else
 327     temp = b->data;
 328
 329   unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (a->mode);
 330   i_f_bits = GET_MODE_IBIT (a->mode) + GET_MODE_FBIT (a->mode);
 331   f->mode = a->mode;
 332   f->data = a->data + temp;
 333   if (unsigned_p) /* Unsigned type.  */
 334     {
 335       if (subtract_p) /* Unsigned subtraction.  */
 336         {
 337           if (a->data.ult (b->data))
 338             {
 339               if (sat_p)
 340                 {
 341                   f->data.high = 0;
 342                   f->data.low = 0;
 343                  }
 344               else
 345                 overflow_p = true;
 346             }
 347         }
 348       else /* Unsigned addition.  */
 349         {
 350           f->data = f->data.zext (i_f_bits);
 351           if (f->data.ult (a->data)
 352               || f->data.ult (b->data))
 353             {
 354               if (sat_p)
 355                 {
 356                   f->data.high = -1;
 357                   f->data.low = -1;
 358                 }
 359               else
 360                 overflow_p = true;
 361             }
 362         }
 363     }
 364   else /* Signed type.  */
 365     {
 366       if ((!subtract_p
 367            && (get_fixed_sign_bit (a->data, i_f_bits)
 368                == get_fixed_sign_bit (b->data, i_f_bits))
 369            && (get_fixed_sign_bit (a->data, i_f_bits)
 370                != get_fixed_sign_bit (f->data, i_f_bits)))
 371           || (subtract_p
 372               && (get_fixed_sign_bit (a->data, i_f_bits)
 373                   != get_fixed_sign_bit (b->data, i_f_bits))
 374               && (get_fixed_sign_bit (a->data, i_f_bits)
 375                   != get_fixed_sign_bit (f->data, i_f_bits))))
 376         {
 377           if (sat_p)
 378             {
 379               f->data.low = 1;
 380               f->data.high = 0;
 381               f->data = f->data.alshift (i_f_bits, HOST_BITS_PER_DOUBLE_INT);
 382               if (get_fixed_sign_bit (a->data, i_f_bits) == 0)
 383                 {
 384                   --f->data;
 385                 }
 386             }
 387           else
 388             overflow_p = true;
 389         }
 390     }
 391   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
 392   return overflow_p;
 393 }
 394
 395 /* Calculate F = A * B.
 396    If SAT_P, saturate the result to the max or the min.
 397    Return true, if !SAT_P and overflow.  */
 398
 399 static bool
 400 do_fixed_multiply (FIXED_VALUE_TYPE *f, const FIXED_VALUE_TYPE *a,
 401                    const FIXED_VALUE_TYPE *b, bool sat_p)
 402 {
 403   bool overflow_p = false;
 404   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (a->mode);
 405   int i_f_bits = GET_MODE_IBIT (a->mode) + GET_MODE_FBIT (a->mode);
 406   f->mode = a->mode;
 407   if (GET_MODE_PRECISION (f->mode) <= HOST_BITS_PER_WIDE_INT)
 408     {
 409       f->data = a->data * b->data;
 410       f->data = f->data.lshift (-GET_MODE_FBIT (f->mode),
 411                                 HOST_BITS_PER_DOUBLE_INT, !unsigned_p);
 412       overflow_p = fixed_saturate1 (f->mode, f->data, &f->data, sat_p);
 413     }
 414   else
 415     {
 416       /* The result of multiplication expands to two double_int.  */
 417       double_int a_high, a_low, b_high, b_low;
 418       double_int high_high, high_low, low_high, low_low;
 419       double_int r, s, temp1, temp2;
 420       int carry = 0;
 421
 422       /* Decompose a and b to four double_int.  */
 423       a_high.low = a->data.high;
 424       a_high.high = 0;
 425       a_low.low = a->data.low;
 426       a_low.high = 0;
 427       b_high.low = b->data.high;
 428       b_high.high = 0;
 429       b_low.low = b->data.low;
 430       b_low.high = 0;
 431
 432       /* Perform four multiplications.  */
 433       low_low = a_low * b_low;
 434       low_high = a_low * b_high;
 435       high_low = a_high * b_low;
 436       high_high = a_high * b_high;
 437
 438       /* Accumulate four results to {r, s}.  */
 439       temp1.high = high_low.low;
 440       temp1.low = 0;
 441       s = low_low + temp1;
 442       if (s.ult (low_low)
 443           || s.ult (temp1))
 444         carry ++; /* Carry */
 445       temp1.high = s.high;
 446       temp1.low = s.low;
 447       temp2.high = low_high.low;
 448       temp2.low = 0;
 449       s = temp1 + temp2;
 450       if (s.ult (temp1)
 451           || s.ult (temp2))
 452         carry ++; /* Carry */
 453
 454       temp1.low = high_low.high;
 455       temp1.high = 0;
 456       r = high_high + temp1;
 457       temp1.low = low_high.high;
 458       temp1.high = 0;
 459       r += temp1;
 460       temp1.low = carry;
 461       temp1.high = 0;
 462       r += temp1;
 463
 464       /* We need to subtract b from r, if a < 0.  */
 465       if (!unsigned_p && a->data.high < 0)
 466         r -= b->data;
 467       /* We need to subtract a from r, if b < 0.  */
 468       if (!unsigned_p && b->data.high < 0)
 469         r -= a->data;
 470
 471       /* Shift right the result by FBIT.  */
 472       if (GET_MODE_FBIT (f->mode) == HOST_BITS_PER_DOUBLE_INT)
 473         {
 474           s.low = r.low;
 475           s.high = r.high;
 476           if (unsigned_p)
 477             {
 478               r.low = 0;
 479               r.high = 0;
 480             }
 481           else
 482             {
 483               r.low = -1;
 484               r.high = -1;
 485             }
 486           f->data.low = s.low;
 487           f->data.high = s.high;
 488         }
 489       else
 490         {
 491           s = s.llshift ((-GET_MODE_FBIT (f->mode)), HOST_BITS_PER_DOUBLE_INT);
 492           f->data = r.llshift ((HOST_BITS_PER_DOUBLE_INT
 493                           - GET_MODE_FBIT (f->mode)),
 494                          HOST_BITS_PER_DOUBLE_INT);
 495           f->data.low = f->data.low | s.low;
 496           f->data.high = f->data.high | s.high;
 497           s.low = f->data.low;
 498           s.high = f->data.high;
 499           r = r.lshift (-GET_MODE_FBIT (f->mode),
 500                         HOST_BITS_PER_DOUBLE_INT, !unsigned_p);
 501         }
 502
 503       overflow_p = fixed_saturate2 (f->mode, r, s, &f->data, sat_p);
 504     }
 505
 506   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
 507   return overflow_p;
 508 }
 509
 510 /* Calculate F = A / B.
 511    If SAT_P, saturate the result to the max or the min.
 512    Return true, if !SAT_P and overflow.  */
 513
 514 static bool
 515 do_fixed_divide (FIXED_VALUE_TYPE *f, const FIXED_VALUE_TYPE *a,
 516                  const FIXED_VALUE_TYPE *b, bool sat_p)
 517 {
 518   bool overflow_p = false;
 519   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (a->mode);
 520   int i_f_bits = GET_MODE_IBIT (a->mode) + GET_MODE_FBIT (a->mode);
 521   f->mode = a->mode;
 522   if (GET_MODE_PRECISION (f->mode) <= HOST_BITS_PER_WIDE_INT)
 523     {
 524       f->data = a->data.lshift (GET_MODE_FBIT (f->mode),
 525                                 HOST_BITS_PER_DOUBLE_INT, !unsigned_p);
 526       f->data = f->data.div (b->data, unsigned_p, TRUNC_DIV_EXPR);
 527       overflow_p = fixed_saturate1 (f->mode, f->data, &f->data, sat_p);
 528     }
 529   else
 530     {
 531       double_int pos_a, pos_b, r, s;
 532       double_int quo_r, quo_s, mod, temp;
 533       int num_of_neg = 0;
 534       int i;
 535
 536       /* If a < 0, negate a.  */
 537       if (!unsigned_p && a->data.high < 0)
 538         {
 539           pos_a = -a->data;
 540           num_of_neg ++;
 541         }
 542       else
 543         pos_a = a->data;
 544
 545       /* If b < 0, negate b.  */
 546       if (!unsigned_p && b->data.high < 0)
 547         {
 548           pos_b = -b->data;
 549           num_of_neg ++;
 550         }
 551       else
 552         pos_b = b->data;
 553
 554       /* Left shift pos_a to {r, s} by FBIT.  */
 555       if (GET_MODE_FBIT (f->mode) == HOST_BITS_PER_DOUBLE_INT)
 556         {
 557           r = pos_a;
 558           s.high = 0;
 559           s.low = 0;
 560         }
 561       else
 562         {
 563           s = pos_a.llshift (GET_MODE_FBIT (f->mode), HOST_BITS_PER_DOUBLE_INT);
 564           r = pos_a.llshift (- (HOST_BITS_PER_DOUBLE_INT
 565                             - GET_MODE_FBIT (f->mode)),
 566                          HOST_BITS_PER_DOUBLE_INT);
 567         }
 568
 569       /* Divide r by pos_b to quo_r.  The remainder is in mod.  */
 570       quo_r = r.divmod (pos_b, 1, TRUNC_DIV_EXPR, &mod);
 571       quo_s = double_int_zero;
 572
 573       for (i = 0; i < HOST_BITS_PER_DOUBLE_INT; i++)
 574         {
 575           /* Record the leftmost bit of mod.  */
 576           int leftmost_mod = (mod.high < 0);
 577
 578           /* Shift left mod by 1 bit.  */
 579           mod = mod.lshift (1);
 580
 581           /* Test the leftmost bit of s to add to mod.  */
 582           if (s.high < 0)
 583             mod.low += 1;
 584
 585           /* Shift left quo_s by 1 bit.  */
 586           quo_s = quo_s.lshift (1);
 587
 588           /* Try to calculate (mod - pos_b).  */
 589           temp = mod - pos_b;
 590
 591           if (leftmost_mod == 1 || mod.ucmp (pos_b) != -1)
 592             {
 593               quo_s.low += 1;
 594               mod = temp;
 595             }
 596
 597           /* Shift left s by 1 bit.  */
 598           s = s.lshift (1);
 599
 600         }
 601
 602       if (num_of_neg == 1)
 603         {
 604           quo_s = -quo_s;
 605           if (quo_s.high == 0 && quo_s.low == 0)
 606             quo_r = -quo_r;
 607           else
 608             {
 609               quo_r.low = ~quo_r.low;
 610               quo_r.high = ~quo_r.high;
 611             }
 612         }
 613
 614       f->data = quo_s;
 615       overflow_p = fixed_saturate2 (f->mode, quo_r, quo_s, &f->data, sat_p);
 616     }
 617
 618   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
 619   return overflow_p;
 620 }
 621
 622 /* Calculate F = A << B if LEFT_P.  Otherwise, F = A >> B.
 623    If SAT_P, saturate the result to the max or the min.
 624    Return true, if !SAT_P and overflow.  */
 625
 626 static bool
 627 do_fixed_shift (FIXED_VALUE_TYPE *f, const FIXED_VALUE_TYPE *a,
 628               const FIXED_VALUE_TYPE *b, bool left_p, bool sat_p)
 629 {
 630   bool overflow_p = false;
 631   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (a->mode);
 632   int i_f_bits = GET_MODE_IBIT (a->mode) + GET_MODE_FBIT (a->mode);
 633   f->mode = a->mode;
 634
 635   if (b->data.low == 0)
 636     {
 637       f->data = a->data;
 638       return overflow_p;
 639     }
 640
 641   if (GET_MODE_PRECISION (f->mode) <= HOST_BITS_PER_WIDE_INT || (!left_p))
 642     {
 643       f->data = a->data.lshift (left_p ? b->data.low : -b->data.low,
 644                                 HOST_BITS_PER_DOUBLE_INT, !unsigned_p);
 645       if (left_p) /* Only left shift saturates.  */
 646         overflow_p = fixed_saturate1 (f->mode, f->data, &f->data, sat_p);
 647     }
 648   else /* We need two double_int to store the left-shift result.  */
 649     {
 650       double_int temp_high, temp_low;
 651       if (b->data.low == HOST_BITS_PER_DOUBLE_INT)
 652         {
 653           temp_high = a->data;
 654           temp_low.high = 0;
 655           temp_low.low = 0;
 656         }
 657       else
 658         {
 659           temp_low = a->data.lshift (b->data.low,
 660                                      HOST_BITS_PER_DOUBLE_INT, !unsigned_p);
 661           /* Logical shift right to temp_high.  */
 662           temp_high = a->data.llshift (b->data.low - HOST_BITS_PER_DOUBLE_INT,
 663                          HOST_BITS_PER_DOUBLE_INT);
 664         }
 665       if (!unsigned_p && a->data.high < 0) /* Signed-extend temp_high.  */
 666         temp_high = temp_high.ext (b->data.low, unsigned_p);
 667       f->data = temp_low;
 668       overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low, &f->data,
 669                                     sat_p);
 670     }
 671   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
 672   return overflow_p;
 673 }
 674
 675 /* Calculate F = -A.
 676    If SAT_P, saturate the result to the max or the min.
 677    Return true, if !SAT_P and overflow.  */
 678
 679 static bool
 680 do_fixed_neg (FIXED_VALUE_TYPE *f, const FIXED_VALUE_TYPE *a, bool sat_p)
 681 {
 682   bool overflow_p = false;
 683   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (a->mode);
 684   int i_f_bits = GET_MODE_IBIT (a->mode) + GET_MODE_FBIT (a->mode);
 685   f->mode = a->mode;
 686   f->data = -a->data;
 687   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
 688
 689   if (unsigned_p) /* Unsigned type.  */
 690     {
 691       if (f->data.low != 0 || f->data.high != 0)
 692         {
 693           if (sat_p)
 694             {
 695               f->data.low = 0;
 696               f->data.high = 0;
 697             }
 698           else
 699             overflow_p = true;
 700         }
 701     }
 702   else /* Signed type.  */
 703     {
 704       if (!(f->data.high == 0 && f->data.low == 0)
 705           && f->data.high == a->data.high && f->data.low == a->data.low )
 706         {
 707           if (sat_p)
 708             {
 709               /* Saturate to the maximum by subtracting f->data by one.  */
 710               f->data.low = -1;
 711               f->data.high = -1;
 712               f->data = f->data.zext (i_f_bits);
 713             }
 714           else
 715             overflow_p = true;
 716         }
 717     }
 718   return overflow_p;
 719 }
 720
 721 /* Perform the binary or unary operation described by CODE.
 722    Note that OP0 and OP1 must have the same mode for binary operators.
 723    For a unary operation, leave OP1 NULL.
 724    Return true, if !SAT_P and overflow.  */
 725
 726 bool
 727 fixed_arithmetic (FIXED_VALUE_TYPE *f, int icode, const FIXED_VALUE_TYPE *op0,
 728                   const FIXED_VALUE_TYPE *op1, bool sat_p)
 729 {
 730   switch (icode)
 731     {
 732     case NEGATE_EXPR:
 733       return do_fixed_neg (f, op0, sat_p);
 734       break;
 735
 736     case PLUS_EXPR:
 737       gcc_assert (op0->mode == op1->mode);
 738       return do_fixed_add (f, op0, op1, false, sat_p);
 739       break;
 740
 741     case MINUS_EXPR:
 742       gcc_assert (op0->mode == op1->mode);
 743       return do_fixed_add (f, op0, op1, true, sat_p);
 744       break;
 745
 746     case MULT_EXPR:
 747       gcc_assert (op0->mode == op1->mode);
 748       return do_fixed_multiply (f, op0, op1, sat_p);
 749       break;
 750
 751     case TRUNC_DIV_EXPR:
 752       gcc_assert (op0->mode == op1->mode);
 753       return do_fixed_divide (f, op0, op1, sat_p);
 754       break;
 755
 756     case LSHIFT_EXPR:
 757       return do_fixed_shift (f, op0, op1, true, sat_p);
 758       break;
 759
 760     case RSHIFT_EXPR:
 761       return do_fixed_shift (f, op0, op1, false, sat_p);
 762       break;
 763
 764     default:
 765       gcc_unreachable ();
 766     }
 767   return false;
 768 }
 769
 770 /* Compare fixed-point values by tree_code.
 771    Note that OP0 and OP1 must have the same mode.  */
 772
 773 bool
 774 fixed_compare (int icode, const FIXED_VALUE_TYPE *op0,
 775                const FIXED_VALUE_TYPE *op1)
 776 {
 777   enum tree_code code = (enum tree_code) icode;
 778   gcc_assert (op0->mode == op1->mode);
 779
 780   switch (code)
 781     {
 782     case NE_EXPR:
 783       return op0->data != op1->data;
 784
 785     case EQ_EXPR:
 786       return op0->data == op1->data;
 787
 788     case LT_EXPR:
 789       return op0->data.cmp (op1->data,
 790                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) == -1;
 791
 792     case LE_EXPR:
 793       return op0->data.cmp (op1->data,
 794                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) != 1;
 795
 796     case GT_EXPR:
 797       return op0->data.cmp (op1->data,
 798                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) == 1;
 799
 800     case GE_EXPR:
 801       return op0->data.cmp (op1->data,
 802                              UNSIGNED_FIXED_POINT_MODE_P (op0->mode)) != -1;
 803
 804     default:
 805       gcc_unreachable ();
 806     }
 807 }
 808
 809 /* Extend or truncate to a new mode.
 810    If SAT_P, saturate the result to the max or the min.
 811    Return true, if !SAT_P and overflow.  */
 812
 813 bool
 814 fixed_convert (FIXED_VALUE_TYPE *f, machine_mode mode,
 815                const FIXED_VALUE_TYPE *a, bool sat_p)
 816 {
 817   bool overflow_p = false;
 818   if (mode == a->mode)
 819     {
 820       *f = *a;
 821       return overflow_p;
 822     }
 823
 824   if (GET_MODE_FBIT (mode) > GET_MODE_FBIT (a->mode))
 825     {
 826       /* Left shift a to temp_high, temp_low based on a->mode.  */
 827       double_int temp_high, temp_low;
 828       int amount = GET_MODE_FBIT (mode) - GET_MODE_FBIT (a->mode);
 829       temp_low = a->data.lshift (amount,
 830                                  HOST_BITS_PER_DOUBLE_INT,
 831                                  SIGNED_FIXED_POINT_MODE_P (a->mode));
 832       /* Logical shift right to temp_high.  */
 833       temp_high = a->data.llshift (amount - HOST_BITS_PER_DOUBLE_INT,
 834                      HOST_BITS_PER_DOUBLE_INT);
 835       if (SIGNED_FIXED_POINT_MODE_P (a->mode)
 836           && a->data.high < 0) /* Signed-extend temp_high.  */
 837         temp_high = temp_high.sext (amount);
 838       f->mode = mode;
 839       f->data = temp_low;
 840       if (SIGNED_FIXED_POINT_MODE_P (a->mode) ==
 841           SIGNED_FIXED_POINT_MODE_P (f->mode))
 842         overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low, &f->data,
 843                                       sat_p);
 844       else
 845         {
 846           /* Take care of the cases when converting between signed and
 847              unsigned.  */
 848           if (SIGNED_FIXED_POINT_MODE_P (a->mode))
 849             {
 850               /* Signed -> Unsigned.  */
 851               if (a->data.high < 0)
 852                 {
 853                   if (sat_p)
 854                     {
 855                       f->data.low = 0;  /* Set to zero.  */
 856                       f->data.high = 0;  /* Set to zero.  */
 857                     }
 858                   else
 859                     overflow_p = true;
 860                 }
 861               else
 862                 overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
 863                                               &f->data, sat_p);
 864             }
 865           else
 866             {
 867               /* Unsigned -> Signed.  */
 868               if (temp_high.high < 0)
 869                 {
 870                   if (sat_p)
 871                     {
 872                       /* Set to maximum.  */
 873                       f->data.low = -1;  /* Set to all ones.  */
 874                       f->data.high = -1;  /* Set to all ones.  */
 875                       f->data = f->data.zext (GET_MODE_FBIT (f->mode)
 876                                                 + GET_MODE_IBIT (f->mode));
 877                                                 /* Clear the sign.  */
 878                     }
 879                   else
 880                     overflow_p = true;
 881                 }
 882               else
 883                 overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
 884                                               &f->data, sat_p);
 885             }
 886         }
 887     }
 888   else
 889     {
 890       /* Right shift a to temp based on a->mode.  */
 891       double_int temp;
 892       temp = a->data.lshift (GET_MODE_FBIT (mode) - GET_MODE_FBIT (a->mode),
 893                              HOST_BITS_PER_DOUBLE_INT,
 894                              SIGNED_FIXED_POINT_MODE_P (a->mode));
 895       f->mode = mode;
 896       f->data = temp;
 897       if (SIGNED_FIXED_POINT_MODE_P (a->mode) ==
 898           SIGNED_FIXED_POINT_MODE_P (f->mode))
 899         overflow_p = fixed_saturate1 (f->mode, f->data, &f->data, sat_p);
 900       else
 901         {
 902           /* Take care of the cases when converting between signed and
 903              unsigned.  */
 904           if (SIGNED_FIXED_POINT_MODE_P (a->mode))
 905             {
 906               /* Signed -> Unsigned.  */
 907               if (a->data.high < 0)
 908                 {
 909                   if (sat_p)
 910                     {
 911                       f->data.low = 0;  /* Set to zero.  */
 912                       f->data.high = 0;  /* Set to zero.  */
 913                     }
 914                   else
 915                     overflow_p = true;
 916                 }
 917               else
 918                 overflow_p = fixed_saturate1 (f->mode, f->data, &f->data,
 919                                               sat_p);
 920             }
 921           else
 922             {
 923               /* Unsigned -> Signed.  */
 924               if (temp.high < 0)
 925                 {
 926                   if (sat_p)
 927                     {
 928                       /* Set to maximum.  */
 929                       f->data.low = -1;  /* Set to all ones.  */
 930                       f->data.high = -1;  /* Set to all ones.  */
 931                       f->data = f->data.zext (GET_MODE_FBIT (f->mode)
 932                                                 + GET_MODE_IBIT (f->mode));
 933                                                 /* Clear the sign.  */
 934                     }
 935                   else
 936                     overflow_p = true;
 937                 }
 938               else
 939                 overflow_p = fixed_saturate1 (f->mode, f->data, &f->data,
 940                                               sat_p);
 941             }
 942         }
 943     }
 944
 945   f->data = f->data.ext (SIGNED_FIXED_POINT_MODE_P (f->mode)
 946                             + GET_MODE_FBIT (f->mode)
 947                             + GET_MODE_IBIT (f->mode),
 948                             UNSIGNED_FIXED_POINT_MODE_P (f->mode));
 949   return overflow_p;
 950 }
 951
 952 /* Convert to a new fixed-point mode from an integer.
 953    If UNSIGNED_P, this integer is unsigned.
 954    If SAT_P, saturate the result to the max or the min.
 955    Return true, if !SAT_P and overflow.  */
 956
 957 bool
 958 fixed_convert_from_int (FIXED_VALUE_TYPE *f, machine_mode mode,
 959                         double_int a, bool unsigned_p, bool sat_p)
 960 {
 961   bool overflow_p = false;
 962   /* Left shift a to temp_high, temp_low.  */
 963   double_int temp_high, temp_low;
 964   int amount = GET_MODE_FBIT (mode);
 965   if (amount == HOST_BITS_PER_DOUBLE_INT)
 966     {
 967        temp_high = a;
 968        temp_low.low = 0;
 969        temp_low.high = 0;
 970     }
 971   else
 972     {
 973       temp_low = a.llshift (amount, HOST_BITS_PER_DOUBLE_INT);
 974
 975       /* Logical shift right to temp_high.  */
 976       temp_high = a.llshift (amount - HOST_BITS_PER_DOUBLE_INT,
 977                      HOST_BITS_PER_DOUBLE_INT);
 978     }
 979   if (!unsigned_p && a.high < 0) /* Signed-extend temp_high.  */
 980     temp_high = temp_high.sext (amount);
 981
 982   f->mode = mode;
 983   f->data = temp_low;
 984
 985   if (unsigned_p == UNSIGNED_FIXED_POINT_MODE_P (f->mode))
 986     overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low, &f->data,
 987                                   sat_p);
 988   else
 989     {
 990       /* Take care of the cases when converting between signed and unsigned.  */
 991       if (!unsigned_p)
 992         {
 993           /* Signed -> Unsigned.  */
 994           if (a.high < 0)
 995             {
 996               if (sat_p)
 997                 {
 998                   f->data.low = 0;  /* Set to zero.  */
 999                   f->data.high = 0;  /* Set to zero.  */
1000                 }
1001               else
1002                 overflow_p = true;
1003             }
1004           else
1005             overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
1006                                           &f->data, sat_p);
1007         }
1008       else
1009         {
1010           /* Unsigned -> Signed.  */
1011           if (temp_high.high < 0)
1012             {
1013               if (sat_p)
1014                 {
1015                   /* Set to maximum.  */
1016                   f->data.low = -1;  /* Set to all ones.  */
1017                   f->data.high = -1;  /* Set to all ones.  */
1018                   f->data = f->data.zext (GET_MODE_FBIT (f->mode)
1019                                             + GET_MODE_IBIT (f->mode));
1020                                             /* Clear the sign.  */
1021                 }
1022               else
1023                 overflow_p = true;
1024             }
1025           else
1026             overflow_p = fixed_saturate2 (f->mode, temp_high, temp_low,
1027                                           &f->data, sat_p);
1028         }
1029     }
1030   f->data = f->data.ext (SIGNED_FIXED_POINT_MODE_P (f->mode)
1031                             + GET_MODE_FBIT (f->mode)
1032                             + GET_MODE_IBIT (f->mode),
1033                             UNSIGNED_FIXED_POINT_MODE_P (f->mode));
1034   return overflow_p;
1035 }
1036
1037 /* Convert to a new fixed-point mode from a real.
1038    If SAT_P, saturate the result to the max or the min.
1039    Return true, if !SAT_P and overflow.  */
1040
1041 bool
1042 fixed_convert_from_real (FIXED_VALUE_TYPE *f, machine_mode mode,
1043                          const REAL_VALUE_TYPE *a, bool sat_p)
1044 {
1045   bool overflow_p = false;
1046   REAL_VALUE_TYPE real_value, fixed_value, base_value;
1047   bool unsigned_p = UNSIGNED_FIXED_POINT_MODE_P (mode);
1048   int i_f_bits = GET_MODE_IBIT (mode) + GET_MODE_FBIT (mode);
1049   unsigned int fbit = GET_MODE_FBIT (mode);
1050   enum fixed_value_range_code temp;
1051   bool fail;
1052
1053   real_value = *a;
1054   f->mode = mode;
1055   real_2expN (&base_value, fbit, mode);
1056   real_arithmetic (&fixed_value, MULT_EXPR, &real_value, &base_value);
1057
1058   wide_int w = real_to_integer (&fixed_value, &fail,
1059                                 GET_MODE_PRECISION (mode));
1060   f->data.low = w.elt (0);
1061   f->data.high = w.elt (1);
1062   temp = check_real_for_fixed_mode (&real_value, mode);
1063   if (temp == FIXED_UNDERFLOW) /* Minimum.  */
1064     {
1065       if (sat_p)
1066         {
1067           if (unsigned_p)
1068             {
1069               f->data.low = 0;
1070               f->data.high = 0;
1071             }
1072           else
1073             {
1074               f->data.low = 1;
1075               f->data.high = 0;
1076               f->data = f->data.alshift (i_f_bits, HOST_BITS_PER_DOUBLE_INT);
1077               f->data = f->data.sext (1 + i_f_bits);
1078             }
1079         }
1080       else
1081         overflow_p = true;
1082     }
1083   else if (temp == FIXED_GT_MAX_EPS || temp == FIXED_MAX_EPS) /* Maximum.  */
1084     {
1085       if (sat_p)
1086         {
1087           f->data.low = -1;
1088           f->data.high = -1;
1089           f->data = f->data.zext (i_f_bits);
1090         }
1091       else
1092         overflow_p = true;
1093     }
1094   f->data = f->data.ext ((!unsigned_p) + i_f_bits, unsigned_p);
1095   return overflow_p;
1096 }
1097
1098 /* Convert to a new real mode from a fixed-point.  */
1099
1100 void
1101 real_convert_from_fixed (REAL_VALUE_TYPE *r, machine_mode mode,
1102                          const FIXED_VALUE_TYPE *f)
1103 {
1104   REAL_VALUE_TYPE base_value, fixed_value, real_value;
1105
1106   signop sgn = UNSIGNED_FIXED_POINT_MODE_P (f->mode) ? UNSIGNED : SIGNED;
1107   real_2expN (&base_value, GET_MODE_FBIT (f->mode), f->mode);
1108   real_from_integer (&fixed_value, VOIDmode,
1109                      wide_int::from (f->data, GET_MODE_PRECISION (f->mode),
1110                                      sgn), sgn);
1111   real_arithmetic (&real_value, RDIV_EXPR, &fixed_value, &base_value);
1112   real_convert (r, mode, &real_value);
1113 }
1114
1115 /* Determine whether a fixed-point value F is negative.  */
1116
1117 bool
1118 fixed_isneg (const FIXED_VALUE_TYPE *f)
1119 {
1120   if (SIGNED_FIXED_POINT_MODE_P (f->mode))
1121     {
1122       int i_f_bits = GET_MODE_IBIT (f->mode) + GET_MODE_FBIT (f->mode);
1123       int sign_bit = get_fixed_sign_bit (f->data, i_f_bits);
1124       if (sign_bit == 1)
1125         return true;
1126     }
1127
1128   return false;
1129 }