gcc/dfp.c

   1 /* Decimal floating point support.
   2    Copyright (C) 2005-2014 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 "tm_p.h"
  26 #include "dfp.h"
  27 #include "wide-int.h"
  28
  29 /* The order of the following headers is important for making sure
  30    decNumber structure is large enough to hold decimal128 digits.  */
  31
  32 #include "decimal128.h"
  33 #include "decimal128Local.h"
  34 #include "decimal64.h"
  35 #include "decimal32.h"
  36 #include "decNumber.h"
  37
  38 #ifndef WORDS_BIGENDIAN
  39 #define WORDS_BIGENDIAN 0
  40 #endif
  41
  42 /* Initialize R (a real with the decimal flag set) from DN.  Can
  43    utilize status passed in via CONTEXT, if a previous operation had
  44    interesting status.  */
  45
  46 static void
  47 decimal_from_decnumber (REAL_VALUE_TYPE *r, decNumber *dn, decContext *context)
  48 {
  49   memset (r, 0, sizeof (REAL_VALUE_TYPE));
  50
  51   r->cl = rvc_normal;
  52   if (decNumberIsNaN (dn))
  53     r->cl = rvc_nan;
  54   if (decNumberIsInfinite (dn))
  55     r->cl = rvc_inf;
  56   if (context->status & DEC_Overflow)
  57     r->cl = rvc_inf;
  58   if (decNumberIsNegative (dn))
  59     r->sign = 1;
  60   r->decimal = 1;
  61
  62   if (r->cl != rvc_normal)
  63     return;
  64
  65   decContextDefault (context, DEC_INIT_DECIMAL128);
  66   context->traps = 0;
  67
  68   decimal128FromNumber ((decimal128 *) r->sig, dn, context);
  69 }
  70
  71 /* Create decimal encoded R from string S.  */
  72
  73 void
  74 decimal_real_from_string (REAL_VALUE_TYPE *r, const char *s)
  75 {
  76   decNumber dn;
  77   decContext set;
  78   decContextDefault (&set, DEC_INIT_DECIMAL128);
  79   set.traps = 0;
  80
  81   decNumberFromString (&dn, s, &set);
  82
  83   /* It would be more efficient to store directly in decNumber format,
  84      but that is impractical from current data structure size.
  85      Encoding as a decimal128 is much more compact.  */
  86   decimal_from_decnumber (r, &dn, &set);
  87 }
  88
  89 /* Initialize a decNumber from a REAL_VALUE_TYPE.  */
  90
  91 static void
  92 decimal_to_decnumber (const REAL_VALUE_TYPE *r, decNumber *dn)
  93 {
  94   decContext set;
  95   decContextDefault (&set, DEC_INIT_DECIMAL128);
  96   set.traps = 0;
  97
  98   switch (r->cl)
  99     {
 100     case rvc_zero:
 101       decNumberZero (dn);
 102       break;
 103     case rvc_inf:
 104       decNumberFromString (dn, "Infinity", &set);
 105       break;
 106     case rvc_nan:
 107       if (r->signalling)
 108         decNumberFromString (dn, "snan", &set);
 109       else
 110         decNumberFromString (dn, "nan", &set);
 111       break;
 112     case rvc_normal:
 113       if (!r->decimal)
 114         {
 115           /* dconst{1,2,m1,half} are used in various places in
 116              the middle-end and optimizers, allow them here
 117              as an exception by converting them to decimal.  */
 118           if (memcmp (r, &dconst1, sizeof (*r)) == 0)
 119             {
 120               decNumberFromString (dn, "1", &set);
 121               break;
 122             }
 123           if (memcmp (r, &dconst2, sizeof (*r)) == 0)
 124             {
 125               decNumberFromString (dn, "2", &set);
 126               break;
 127             }
 128           if (memcmp (r, &dconstm1, sizeof (*r)) == 0)
 129             {
 130               decNumberFromString (dn, "-1", &set);
 131               break;
 132             }
 133           if (memcmp (r, &dconsthalf, sizeof (*r)) == 0)
 134             {
 135               decNumberFromString (dn, "0.5", &set);
 136               break;
 137             }
 138           gcc_unreachable ();
 139         }
 140       decimal128ToNumber ((const decimal128 *) r->sig, dn);
 141       break;
 142     default:
 143       gcc_unreachable ();
 144     }
 145
 146   /* Fix up sign bit.  */
 147   if (r->sign != decNumberIsNegative (dn))
 148     dn->bits ^= DECNEG;
 149 }
 150
 151 /* Encode a real into an IEEE 754 decimal32 type.  */
 152
 153 void
 154 encode_decimal32 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 155                   long *buf, const REAL_VALUE_TYPE *r)
 156 {
 157   decNumber dn;
 158   decimal32 d32;
 159   decContext set;
 160   int32_t image;
 161
 162   decContextDefault (&set, DEC_INIT_DECIMAL128);
 163   set.traps = 0;
 164
 165   decimal_to_decnumber (r, &dn);
 166   decimal32FromNumber (&d32, &dn, &set);
 167
 168   memcpy (&image, d32.bytes, sizeof (int32_t));
 169   buf[0] = image;
 170 }
 171
 172 /* Decode an IEEE 754 decimal32 type into a real.  */
 173
 174 void
 175 decode_decimal32 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 176                   REAL_VALUE_TYPE *r, const long *buf)
 177 {
 178   decNumber dn;
 179   decimal32 d32;
 180   decContext set;
 181   int32_t image;
 182
 183   decContextDefault (&set, DEC_INIT_DECIMAL128);
 184   set.traps = 0;
 185
 186   image = buf[0];
 187   memcpy (&d32.bytes, &image, sizeof (int32_t));
 188
 189   decimal32ToNumber (&d32, &dn);
 190   decimal_from_decnumber (r, &dn, &set);
 191 }
 192
 193 /* Encode a real into an IEEE 754 decimal64 type.  */
 194
 195 void
 196 encode_decimal64 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 197                   long *buf, const REAL_VALUE_TYPE *r)
 198 {
 199   decNumber dn;
 200   decimal64 d64;
 201   decContext set;
 202   int32_t image;
 203
 204   decContextDefault (&set, DEC_INIT_DECIMAL128);
 205   set.traps = 0;
 206
 207   decimal_to_decnumber (r, &dn);
 208   decimal64FromNumber (&d64, &dn, &set);
 209
 210   if (WORDS_BIGENDIAN == FLOAT_WORDS_BIG_ENDIAN)
 211     {
 212       memcpy (&image, &d64.bytes[0], sizeof (int32_t));
 213       buf[0] = image;
 214       memcpy (&image, &d64.bytes[4], sizeof (int32_t));
 215       buf[1] = image;
 216     }
 217   else
 218     {
 219       memcpy (&image, &d64.bytes[4], sizeof (int32_t));
 220       buf[0] = image;
 221       memcpy (&image, &d64.bytes[0], sizeof (int32_t));
 222       buf[1] = image;
 223     }
 224 }
 225
 226 /* Decode an IEEE 754 decimal64 type into a real.  */
 227
 228 void
 229 decode_decimal64 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 230                   REAL_VALUE_TYPE *r, const long *buf)
 231 {
 232   decNumber dn;
 233   decimal64 d64;
 234   decContext set;
 235   int32_t image;
 236
 237   decContextDefault (&set, DEC_INIT_DECIMAL128);
 238   set.traps = 0;
 239
 240   if (WORDS_BIGENDIAN == FLOAT_WORDS_BIG_ENDIAN)
 241     {
 242       image = buf[0];
 243       memcpy (&d64.bytes[0], &image, sizeof (int32_t));
 244       image = buf[1];
 245       memcpy (&d64.bytes[4], &image, sizeof (int32_t));
 246     }
 247   else
 248     {
 249       image = buf[1];
 250       memcpy (&d64.bytes[0], &image, sizeof (int32_t));
 251       image = buf[0];
 252       memcpy (&d64.bytes[4], &image, sizeof (int32_t));
 253     }
 254
 255   decimal64ToNumber (&d64, &dn);
 256   decimal_from_decnumber (r, &dn, &set);
 257 }
 258
 259 /* Encode a real into an IEEE 754 decimal128 type.  */
 260
 261 void
 262 encode_decimal128 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 263                    long *buf, const REAL_VALUE_TYPE *r)
 264 {
 265   decNumber dn;
 266   decContext set;
 267   decimal128 d128;
 268   int32_t image;
 269
 270   decContextDefault (&set, DEC_INIT_DECIMAL128);
 271   set.traps = 0;
 272
 273   decimal_to_decnumber (r, &dn);
 274   decimal128FromNumber (&d128, &dn, &set);
 275
 276   if (WORDS_BIGENDIAN == FLOAT_WORDS_BIG_ENDIAN)
 277     {
 278       memcpy (&image, &d128.bytes[0], sizeof (int32_t));
 279       buf[0] = image;
 280       memcpy (&image, &d128.bytes[4], sizeof (int32_t));
 281       buf[1] = image;
 282       memcpy (&image, &d128.bytes[8], sizeof (int32_t));
 283       buf[2] = image;
 284       memcpy (&image, &d128.bytes[12], sizeof (int32_t));
 285       buf[3] = image;
 286     }
 287   else
 288     {
 289       memcpy (&image, &d128.bytes[12], sizeof (int32_t));
 290       buf[0] = image;
 291       memcpy (&image, &d128.bytes[8], sizeof (int32_t));
 292       buf[1] = image;
 293       memcpy (&image, &d128.bytes[4], sizeof (int32_t));
 294       buf[2] = image;
 295       memcpy (&image, &d128.bytes[0], sizeof (int32_t));
 296       buf[3] = image;
 297     }
 298 }
 299
 300 /* Decode an IEEE 754 decimal128 type into a real.  */
 301
 302 void
 303 decode_decimal128 (const struct real_format *fmt ATTRIBUTE_UNUSED,
 304                    REAL_VALUE_TYPE *r, const long *buf)
 305 {
 306   decNumber dn;
 307   decimal128 d128;
 308   decContext set;
 309   int32_t image;
 310
 311   decContextDefault (&set, DEC_INIT_DECIMAL128);
 312   set.traps = 0;
 313
 314   if (WORDS_BIGENDIAN == FLOAT_WORDS_BIG_ENDIAN)
 315     {
 316       image = buf[0];
 317       memcpy (&d128.bytes[0],  &image, sizeof (int32_t));
 318       image = buf[1];
 319       memcpy (&d128.bytes[4],  &image, sizeof (int32_t));
 320       image = buf[2];
 321       memcpy (&d128.bytes[8],  &image, sizeof (int32_t));
 322       image = buf[3];
 323       memcpy (&d128.bytes[12], &image, sizeof (int32_t));
 324     }
 325   else
 326     {
 327       image = buf[3];
 328       memcpy (&d128.bytes[0],  &image, sizeof (int32_t));
 329       image = buf[2];
 330       memcpy (&d128.bytes[4],  &image, sizeof (int32_t));
 331       image = buf[1];
 332       memcpy (&d128.bytes[8],  &image, sizeof (int32_t));
 333       image = buf[0];
 334       memcpy (&d128.bytes[12], &image, sizeof (int32_t));
 335     }
 336
 337   decimal128ToNumber (&d128, &dn);
 338   decimal_from_decnumber (r, &dn, &set);
 339 }
 340
 341 /* Helper function to convert from a binary real internal
 342    representation.  */
 343
 344 static void
 345 decimal_to_binary (REAL_VALUE_TYPE *to, const REAL_VALUE_TYPE *from,
 346                    enum machine_mode mode)
 347 {
 348   char string[256];
 349   const decimal128 *const d128 = (const decimal128 *) from->sig;
 350
 351   decimal128ToString (d128, string);
 352   real_from_string3 (to, string, mode);
 353 }
 354
 355
 356 /* Helper function to convert from a binary real internal
 357    representation.  */
 358
 359 static void
 360 decimal_from_binary (REAL_VALUE_TYPE *to, const REAL_VALUE_TYPE *from)
 361 {
 362   char string[256];
 363
 364   /* We convert to string, then to decNumber then to decimal128.  */
 365   real_to_decimal (string, from, sizeof (string), 0, 1);
 366   decimal_real_from_string (to, string);
 367 }
 368
 369 /* Helper function to real.c:do_compare() to handle decimal internal
 370    representation including when one of the operands is still in the
 371    binary internal representation.  */
 372
 373 int
 374 decimal_do_compare (const REAL_VALUE_TYPE *a, const REAL_VALUE_TYPE *b,
 375                     int nan_result)
 376 {
 377   decContext set;
 378   decNumber dn, dn2, dn3;
 379   REAL_VALUE_TYPE a1, b1;
 380
 381   /* If either operand is non-decimal, create temporary versions.  */
 382   if (!a->decimal)
 383     {
 384       decimal_from_binary (&a1, a);
 385       a = &a1;
 386     }
 387   if (!b->decimal)
 388     {
 389       decimal_from_binary (&b1, b);
 390       b = &b1;
 391     }
 392
 393   /* Convert into decNumber form for comparison operation.  */
 394   decContextDefault (&set, DEC_INIT_DECIMAL128);
 395   set.traps = 0;
 396   decimal128ToNumber ((const decimal128 *) a->sig, &dn2);
 397   decimal128ToNumber ((const decimal128 *) b->sig, &dn3);
 398
 399   /* Finally, do the comparison.  */
 400   decNumberCompare (&dn, &dn2, &dn3, &set);
 401
 402   /* Return the comparison result.  */
 403   if (decNumberIsNaN (&dn))
 404     return nan_result;
 405   else if (decNumberIsZero (&dn))
 406     return 0;
 407   else if (decNumberIsNegative (&dn))
 408     return -1;
 409   else
 410     return 1;
 411 }
 412
 413 /* Helper to round_for_format, handling decimal float types.  */
 414
 415 void
 416 decimal_round_for_format (const struct real_format *fmt, REAL_VALUE_TYPE *r)
 417 {
 418   decNumber dn;
 419   decContext set;
 420
 421   /* Real encoding occurs later.  */
 422   if (r->cl != rvc_normal)
 423     return;
 424
 425   decContextDefault (&set, DEC_INIT_DECIMAL128);
 426   set.traps = 0;
 427   decimal128ToNumber ((decimal128 *) r->sig, &dn);
 428
 429   if (fmt == &decimal_quad_format)
 430     {
 431       /* The internal format is already in this format.  */
 432       return;
 433     }
 434   else if (fmt == &decimal_single_format)
 435     {
 436       decimal32 d32;
 437       decContextDefault (&set, DEC_INIT_DECIMAL32);
 438       set.traps = 0;
 439
 440       decimal32FromNumber (&d32, &dn, &set);
 441       decimal32ToNumber (&d32, &dn);
 442     }
 443   else if (fmt == &decimal_double_format)
 444     {
 445       decimal64 d64;
 446       decContextDefault (&set, DEC_INIT_DECIMAL64);
 447       set.traps = 0;
 448
 449       decimal64FromNumber (&d64, &dn, &set);
 450       decimal64ToNumber (&d64, &dn);
 451     }
 452   else
 453     gcc_unreachable ();
 454
 455   decimal_from_decnumber (r, &dn, &set);
 456 }
 457
 458 /* Extend or truncate to a new mode.  Handles conversions between
 459    binary and decimal types.  */
 460
 461 void
 462 decimal_real_convert (REAL_VALUE_TYPE *r, enum machine_mode mode,
 463                       const REAL_VALUE_TYPE *a)
 464 {
 465   const struct real_format *fmt = REAL_MODE_FORMAT (mode);
 466
 467   if (a->decimal && fmt->b == 10)
 468     return;
 469   if (a->decimal)
 470       decimal_to_binary (r, a, mode);
 471   else
 472       decimal_from_binary (r, a);
 473 }
 474
 475 /* Render R_ORIG as a decimal floating point constant.  Emit DIGITS
 476    significant digits in the result, bounded by BUF_SIZE.  If DIGITS
 477    is 0, choose the maximum for the representation.  If
 478    CROP_TRAILING_ZEROS, strip trailing zeros.  Currently, not honoring
 479    DIGITS or CROP_TRAILING_ZEROS.  */
 480
 481 void
 482 decimal_real_to_decimal (char *str, const REAL_VALUE_TYPE *r_orig,
 483                          size_t buf_size,
 484                          size_t digits ATTRIBUTE_UNUSED,
 485                          int crop_trailing_zeros ATTRIBUTE_UNUSED)
 486 {
 487   const decimal128 *const d128 = (const decimal128*) r_orig->sig;
 488
 489   /* decimal128ToString requires space for at least 24 characters;
 490      Require two more for suffix.  */
 491   gcc_assert (buf_size >= 24);
 492   decimal128ToString (d128, str);
 493 }
 494
 495 static bool
 496 decimal_do_add (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
 497                 const REAL_VALUE_TYPE *op1, int subtract_p)
 498 {
 499   decNumber dn;
 500   decContext set;
 501   decNumber dn2, dn3;
 502
 503   decimal_to_decnumber (op0, &dn2);
 504   decimal_to_decnumber (op1, &dn3);
 505
 506   decContextDefault (&set, DEC_INIT_DECIMAL128);
 507   set.traps = 0;
 508
 509   if (subtract_p)
 510     decNumberSubtract (&dn, &dn2, &dn3, &set);
 511   else
 512     decNumberAdd (&dn, &dn2, &dn3, &set);
 513
 514   decimal_from_decnumber (r, &dn, &set);
 515
 516   /* Return true, if inexact.  */
 517   return (set.status & DEC_Inexact);
 518 }
 519
 520 /* Compute R = OP0 * OP1.  */
 521
 522 static bool
 523 decimal_do_multiply (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
 524                      const REAL_VALUE_TYPE *op1)
 525 {
 526   decContext set;
 527   decNumber dn, dn2, dn3;
 528
 529   decimal_to_decnumber (op0, &dn2);
 530   decimal_to_decnumber (op1, &dn3);
 531
 532   decContextDefault (&set, DEC_INIT_DECIMAL128);
 533   set.traps = 0;
 534
 535   decNumberMultiply (&dn, &dn2, &dn3, &set);
 536   decimal_from_decnumber (r, &dn, &set);
 537
 538   /* Return true, if inexact.  */
 539   return (set.status & DEC_Inexact);
 540 }
 541
 542 /* Compute R = OP0 / OP1.  */
 543
 544 static bool
 545 decimal_do_divide (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *op0,
 546                    const REAL_VALUE_TYPE *op1)
 547 {
 548   decContext set;
 549   decNumber dn, dn2, dn3;
 550
 551   decimal_to_decnumber (op0, &dn2);
 552   decimal_to_decnumber (op1, &dn3);
 553
 554   decContextDefault (&set, DEC_INIT_DECIMAL128);
 555   set.traps = 0;
 556
 557   decNumberDivide (&dn, &dn2, &dn3, &set);
 558   decimal_from_decnumber (r, &dn, &set);
 559
 560   /* Return true, if inexact.  */
 561   return (set.status & DEC_Inexact);
 562 }
 563
 564 /* Set R to A truncated to an integral value toward zero (decimal
 565    floating point).  */
 566
 567 void
 568 decimal_do_fix_trunc (REAL_VALUE_TYPE *r, const REAL_VALUE_TYPE *a)
 569 {
 570   decNumber dn, dn2;
 571   decContext set;
 572
 573   decContextDefault (&set, DEC_INIT_DECIMAL128);
 574   set.traps = 0;
 575   set.round = DEC_ROUND_DOWN;
 576   decimal128ToNumber ((const decimal128 *) a->sig, &dn2);
 577
 578   decNumberToIntegralValue (&dn, &dn2, &set);
 579   decimal_from_decnumber (r, &dn, &set);
 580 }
 581
 582 /* Render decimal float value R as an integer.  */
 583
 584 HOST_WIDE_INT
 585 decimal_real_to_integer (const REAL_VALUE_TYPE *r)
 586 {
 587   decContext set;
 588   decNumber dn, dn2, dn3;
 589   REAL_VALUE_TYPE to;
 590   char string[256];
 591
 592   decContextDefault (&set, DEC_INIT_DECIMAL128);
 593   set.traps = 0;
 594   set.round = DEC_ROUND_DOWN;
 595   decimal128ToNumber ((const decimal128 *) r->sig, &dn);
 596
 597   decNumberToIntegralValue (&dn2, &dn, &set);
 598   decNumberZero (&dn3);
 599   decNumberRescale (&dn, &dn2, &dn3, &set);
 600
 601   /* Convert to REAL_VALUE_TYPE and call appropriate conversion
 602      function.  */
 603   decNumberToString (&dn, string);
 604   real_from_string (&to, string);
 605   return real_to_integer (&to);
 606 }
 607
 608 /* Likewise, but returns a wide_int with PRECISION.  *FAIL is set if the
 609    value does not fit.  */
 610
 611 wide_int
 612 decimal_real_to_integer (const REAL_VALUE_TYPE *r, bool *fail, int precision)
 613 {
 614   decContext set;
 615   decNumber dn, dn2, dn3;
 616   REAL_VALUE_TYPE to;
 617   char string[256];
 618
 619   decContextDefault (&set, DEC_INIT_DECIMAL128);
 620   set.traps = 0;
 621   set.round = DEC_ROUND_DOWN;
 622   decimal128ToNumber ((const decimal128 *) r->sig, &dn);
 623
 624   decNumberToIntegralValue (&dn2, &dn, &set);
 625   decNumberZero (&dn3);
 626   decNumberRescale (&dn, &dn2, &dn3, &set);
 627
 628   /* Convert to REAL_VALUE_TYPE and call appropriate conversion
 629      function.  */
 630   decNumberToString (&dn, string);
 631   real_from_string (&to, string);
 632   return real_to_integer (&to, fail, precision);
 633 }
 634
 635 /* Perform the decimal floating point operation described by CODE.
 636    For a unary operation, OP1 will be NULL.  This function returns
 637    true if the result may be inexact due to loss of precision.  */
 638
 639 bool
 640 decimal_real_arithmetic (REAL_VALUE_TYPE *r, enum tree_code code,
 641                          const REAL_VALUE_TYPE *op0,
 642                          const REAL_VALUE_TYPE *op1)
 643 {
 644   REAL_VALUE_TYPE a, b;
 645
 646   /* If either operand is non-decimal, create temporaries.  */
 647   if (!op0->decimal)
 648     {
 649       decimal_from_binary (&a, op0);
 650       op0 = &a;
 651     }
 652   if (op1 && !op1->decimal)
 653     {
 654       decimal_from_binary (&b, op1);
 655       op1 = &b;
 656     }
 657
 658   switch (code)
 659     {
 660     case PLUS_EXPR:
 661       return decimal_do_add (r, op0, op1, 0);
 662
 663     case MINUS_EXPR:
 664       return decimal_do_add (r, op0, op1, 1);
 665
 666     case MULT_EXPR:
 667       return decimal_do_multiply (r, op0, op1);
 668
 669     case RDIV_EXPR:
 670       return decimal_do_divide (r, op0, op1);
 671
 672     case MIN_EXPR:
 673       if (op1->cl == rvc_nan)
 674         *r = *op1;
 675       else if (real_compare (UNLT_EXPR, op0, op1))
 676         *r = *op0;
 677       else
 678         *r = *op1;
 679       return false;
 680
 681     case MAX_EXPR:
 682       if (op1->cl == rvc_nan)
 683         *r = *op1;
 684       else if (real_compare (LT_EXPR, op0, op1))
 685         *r = *op1;
 686       else
 687         *r = *op0;
 688       return false;
 689
 690     case NEGATE_EXPR:
 691       {
 692         *r = *op0;
 693         /* Flip sign bit.  */
 694         decimal128FlipSign ((decimal128 *) r->sig);
 695         /* Keep sign field in sync.  */
 696         r->sign ^= 1;
 697       }
 698       return false;
 699
 700     case ABS_EXPR:
 701       {
 702         *r = *op0;
 703         /* Clear sign bit.  */
 704         decimal128ClearSign ((decimal128 *) r->sig);
 705         /* Keep sign field in sync.  */
 706         r->sign = 0;
 707       }
 708       return false;
 709
 710     case FIX_TRUNC_EXPR:
 711       decimal_do_fix_trunc (r, op0);
 712       return false;
 713
 714     default:
 715       gcc_unreachable ();
 716     }
 717 }
 718
 719 /* Fills R with the largest finite value representable in mode MODE.
 720    If SIGN is nonzero, R is set to the most negative finite value.  */
 721
 722 void
 723 decimal_real_maxval (REAL_VALUE_TYPE *r, int sign, enum machine_mode mode)
 724 {
 725   const char *max;
 726
 727   switch (mode)
 728     {
 729     case SDmode:
 730       max = "9.999999E96";
 731       break;
 732     case DDmode:
 733       max = "9.999999999999999E384";
 734       break;
 735     case TDmode:
 736       max = "9.999999999999999999999999999999999E6144";
 737       break;
 738     default:
 739       gcc_unreachable ();
 740     }
 741
 742   decimal_real_from_string (r, max);
 743   if (sign)
 744     decimal128SetSign ((decimal128 *) r->sig, 1);
 745 }