gcc/real.h

   1 /* Definitions of floating-point access for GNU compiler.
   2    Copyright (C) 1989-2015 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 #ifndef GCC_REAL_H
  21 #define GCC_REAL_H
  22
  23 /* An expanded form of the represented number.  */
  24
  25 /* Enumerate the special cases of numbers that we encounter.  */
  26 enum real_value_class {
  27   rvc_zero,
  28   rvc_normal,
  29   rvc_inf,
  30   rvc_nan
  31 };
  32
  33 #define SIGNIFICAND_BITS        (128 + HOST_BITS_PER_LONG)
  34 #define EXP_BITS                (32 - 6)
  35 #define MAX_EXP                 ((1 << (EXP_BITS - 1)) - 1)
  36 #define SIGSZ                   (SIGNIFICAND_BITS / HOST_BITS_PER_LONG)
  37 #define SIG_MSB                 ((unsigned long)1 << (HOST_BITS_PER_LONG - 1))
  38
  39 struct GTY(()) real_value {
  40   /* Use the same underlying type for all bit-fields, so as to make
  41      sure they're packed together, otherwise REAL_VALUE_TYPE_SIZE will
  42      be miscomputed.  */
  43   unsigned int /* ENUM_BITFIELD (real_value_class) */ cl : 2;
  44   unsigned int decimal : 1;
  45   unsigned int sign : 1;
  46   unsigned int signalling : 1;
  47   unsigned int canonical : 1;
  48   unsigned int uexp : EXP_BITS;
  49   unsigned long sig[SIGSZ];
  50 };
  51
  52 #define REAL_EXP(REAL) \
  53   ((int)((REAL)->uexp ^ (unsigned int)(1 << (EXP_BITS - 1))) \
  54    - (1 << (EXP_BITS - 1)))
  55 #define SET_REAL_EXP(REAL, EXP) \
  56   ((REAL)->uexp = ((unsigned int)(EXP) & (unsigned int)((1 << EXP_BITS) - 1)))
  57
  58 /* Various headers condition prototypes on #ifdef REAL_VALUE_TYPE, so it
  59    needs to be a macro.  We do need to continue to have a structure tag
  60    so that other headers can forward declare it.  */
  61 #define REAL_VALUE_TYPE struct real_value
  62
  63 /* We store a REAL_VALUE_TYPE into an rtx, and we do this by putting it in
  64    consecutive "w" slots.  Moreover, we've got to compute the number of "w"
  65    slots at preprocessor time, which means we can't use sizeof.  Guess.  */
  66
  67 #define REAL_VALUE_TYPE_SIZE (SIGNIFICAND_BITS + 32)
  68 #define REAL_WIDTH \
  69   (REAL_VALUE_TYPE_SIZE/HOST_BITS_PER_WIDE_INT \
  70    + (REAL_VALUE_TYPE_SIZE%HOST_BITS_PER_WIDE_INT ? 1 : 0)) /* round up */
  71
  72 /* Verify the guess.  */
  73 extern char test_real_width
  74   [sizeof (REAL_VALUE_TYPE) <= REAL_WIDTH * sizeof (HOST_WIDE_INT) ? 1 : -1];
  75
  76 /* Calculate the format for CONST_DOUBLE.  We need as many slots as
  77    are necessary to overlay a REAL_VALUE_TYPE on them.  This could be
  78    as many as four (32-bit HOST_WIDE_INT, 128-bit REAL_VALUE_TYPE).
  79
  80    A number of places assume that there are always at least two 'w'
  81    slots in a CONST_DOUBLE, so we provide them even if one would suffice.  */
  82
  83 #if REAL_WIDTH == 1
  84 # define CONST_DOUBLE_FORMAT     "ww"
  85 #else
  86 # if REAL_WIDTH == 2
  87 #  define CONST_DOUBLE_FORMAT    "ww"
  88 # else
  89 #  if REAL_WIDTH == 3
  90 #   define CONST_DOUBLE_FORMAT   "www"
  91 #  else
  92 #   if REAL_WIDTH == 4
  93 #    define CONST_DOUBLE_FORMAT  "wwww"
  94 #   else
  95 #    if REAL_WIDTH == 5
  96 #     define CONST_DOUBLE_FORMAT "wwwww"
  97 #    else
  98 #     if REAL_WIDTH == 6
  99 #      define CONST_DOUBLE_FORMAT "wwwwww"
 100 #     else
 101        #error "REAL_WIDTH > 6 not supported"
 102 #     endif
 103 #    endif
 104 #   endif
 105 #  endif
 106 # endif
 107 #endif
 108
 109
 110 /* Describes the properties of the specific target format in use.  */
 111 struct real_format
 112 {
 113   /* Move to and from the target bytes.  */
 114   void (*encode) (const struct real_format *, long *,
 115                   const REAL_VALUE_TYPE *);
 116   void (*decode) (const struct real_format *, REAL_VALUE_TYPE *,
 117                   const long *);
 118
 119   /* The radix of the exponent and digits of the significand.  */
 120   int b;
 121
 122   /* Size of the significand in digits of radix B.  */
 123   int p;
 124
 125   /* Size of the significant of a NaN, in digits of radix B.  */
 126   int pnan;
 127
 128   /* The minimum negative integer, x, such that b**(x-1) is normalized.  */
 129   int emin;
 130
 131   /* The maximum integer, x, such that b**(x-1) is representable.  */
 132   int emax;
 133
 134   /* The bit position of the sign bit, for determining whether a value
 135      is positive/negative, or -1 for a complex encoding.  */
 136   int signbit_ro;
 137
 138   /* The bit position of the sign bit, for changing the sign of a number,
 139      or -1 for a complex encoding.  */
 140   int signbit_rw;
 141
 142   /* Default rounding mode for operations on this format.  */
 143   bool round_towards_zero;
 144   bool has_sign_dependent_rounding;
 145
 146   /* Properties of the format.  */
 147   bool has_nans;
 148   bool has_inf;
 149   bool has_denorm;
 150   bool has_signed_zero;
 151   bool qnan_msb_set;
 152   bool canonical_nan_lsbs_set;
 153   const char *name;
 154 };
 155
 156
 157 /* The target format used for each floating point mode.
 158    Float modes are followed by decimal float modes, with entries for
 159    float modes indexed by (MODE - first float mode), and entries for
 160    decimal float modes indexed by (MODE - first decimal float mode) +
 161    the number of float modes.  */
 162 extern const struct real_format *
 163   real_format_for_mode[MAX_MODE_FLOAT - MIN_MODE_FLOAT + 1
 164                        + MAX_MODE_DECIMAL_FLOAT - MIN_MODE_DECIMAL_FLOAT + 1];
 165
 166 #define REAL_MODE_FORMAT(MODE)                                          \
 167   (real_format_for_mode[DECIMAL_FLOAT_MODE_P (MODE)                     \
 168                         ? (((MODE) - MIN_MODE_DECIMAL_FLOAT)            \
 169                            + (MAX_MODE_FLOAT - MIN_MODE_FLOAT + 1))     \
 170                         : ((MODE) - MIN_MODE_FLOAT)])
 171
 172 #define FLOAT_MODE_FORMAT(MODE) \
 173   (REAL_MODE_FORMAT (SCALAR_FLOAT_MODE_P (MODE)? (MODE) \
 174                                                : GET_MODE_INNER (MODE)))
 175
 176 /* The following macro determines whether the floating point format is
 177    composite, i.e. may contain non-consecutive mantissa bits, in which
 178    case compile-time FP overflow may not model run-time overflow.  */
 179 #define MODE_COMPOSITE_P(MODE) \
 180   (FLOAT_MODE_P (MODE) \
 181    && FLOAT_MODE_FORMAT (MODE)->pnan < FLOAT_MODE_FORMAT (MODE)->p)
 182
 183 /* Accessor macros for format properties.  */
 184 #define MODE_HAS_NANS(MODE) \
 185   (FLOAT_MODE_P (MODE) && FLOAT_MODE_FORMAT (MODE)->has_nans)
 186 #define MODE_HAS_INFINITIES(MODE) \
 187   (FLOAT_MODE_P (MODE) && FLOAT_MODE_FORMAT (MODE)->has_inf)
 188 #define MODE_HAS_SIGNED_ZEROS(MODE) \
 189   (FLOAT_MODE_P (MODE) && FLOAT_MODE_FORMAT (MODE)->has_signed_zero)
 190 #define MODE_HAS_SIGN_DEPENDENT_ROUNDING(MODE) \
 191   (FLOAT_MODE_P (MODE) \
 192    && FLOAT_MODE_FORMAT (MODE)->has_sign_dependent_rounding)
 193
 194 /* Declare functions in real.c.  */
 195
 196 /* True if the given mode has a NaN representation and the treatment of
 197    NaN operands is important.  Certain optimizations, such as folding
 198    x * 0 into 0, are not correct for NaN operands, and are normally
 199    disabled for modes with NaNs.  The user can ask for them to be
 200    done anyway using the -funsafe-math-optimizations switch.  */
 201 extern bool HONOR_NANS (machine_mode);
 202 extern bool HONOR_NANS (const_tree);
 203 extern bool HONOR_NANS (const_rtx);
 204
 205 /* Like HONOR_NANs, but true if we honor signaling NaNs (or sNaNs).  */
 206 extern bool HONOR_SNANS (machine_mode);
 207 extern bool HONOR_SNANS (const_tree);
 208 extern bool HONOR_SNANS (const_rtx);
 209
 210 /* As for HONOR_NANS, but true if the mode can represent infinity and
 211    the treatment of infinite values is important.  */
 212 extern bool HONOR_INFINITIES (machine_mode);
 213 extern bool HONOR_INFINITIES (const_tree);
 214 extern bool HONOR_INFINITIES (const_rtx);
 215
 216 /* Like HONOR_NANS, but true if the given mode distinguishes between
 217    positive and negative zero, and the sign of zero is important.  */
 218 extern bool HONOR_SIGNED_ZEROS (machine_mode);
 219 extern bool HONOR_SIGNED_ZEROS (const_tree);
 220 extern bool HONOR_SIGNED_ZEROS (const_rtx);
 221
 222 /* Like HONOR_NANS, but true if given mode supports sign-dependent rounding,
 223    and the rounding mode is important.  */
 224 extern bool HONOR_SIGN_DEPENDENT_ROUNDING (machine_mode);
 225 extern bool HONOR_SIGN_DEPENDENT_ROUNDING (const_tree);
 226 extern bool HONOR_SIGN_DEPENDENT_ROUNDING (const_rtx);
 227
 228 /* Binary or unary arithmetic on tree_code.  */
 229 extern bool real_arithmetic (REAL_VALUE_TYPE *, int, const REAL_VALUE_TYPE *,
 230                              const REAL_VALUE_TYPE *);
 231
 232 /* Compare reals by tree_code.  */
 233 extern bool real_compare (int, const REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *);
 234
 235 /* Determine whether a floating-point value X is infinite.  */
 236 extern bool real_isinf (const REAL_VALUE_TYPE *);
 237
 238 /* Determine whether a floating-point value X is a NaN.  */
 239 extern bool real_isnan (const REAL_VALUE_TYPE *);
 240
 241 /* Determine whether a floating-point value X is finite.  */
 242 extern bool real_isfinite (const REAL_VALUE_TYPE *);
 243
 244 /* Determine whether a floating-point value X is negative.  */
 245 extern bool real_isneg (const REAL_VALUE_TYPE *);
 246
 247 /* Determine whether a floating-point value X is minus zero.  */
 248 extern bool real_isnegzero (const REAL_VALUE_TYPE *);
 249
 250 /* Compare two floating-point objects for bitwise identity.  */
 251 extern bool real_identical (const REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *);
 252
 253 /* Extend or truncate to a new mode.  */
 254 extern void real_convert (REAL_VALUE_TYPE *, machine_mode,
 255                           const REAL_VALUE_TYPE *);
 256
 257 /* Return true if truncating to NEW is exact.  */
 258 extern bool exact_real_truncate (machine_mode, const REAL_VALUE_TYPE *);
 259
 260 /* Render R as a decimal floating point constant.  */
 261 extern void real_to_decimal (char *, const REAL_VALUE_TYPE *, size_t,
 262                              size_t, int);
 263
 264 /* Render R as a decimal floating point constant, rounded so as to be
 265    parsed back to the same value when interpreted in mode MODE.  */
 266 extern void real_to_decimal_for_mode (char *, const REAL_VALUE_TYPE *, size_t,
 267                                       size_t, int, machine_mode);
 268
 269 /* Render R as a hexadecimal floating point constant.  */
 270 extern void real_to_hexadecimal (char *, const REAL_VALUE_TYPE *,
 271                                  size_t, size_t, int);
 272
 273 /* Render R as an integer.  */
 274 extern HOST_WIDE_INT real_to_integer (const REAL_VALUE_TYPE *);
 275
 276 /* Initialize R from a decimal or hexadecimal string.  Return -1 if
 277    the value underflows, +1 if overflows, and 0 otherwise.  */
 278 extern int real_from_string (REAL_VALUE_TYPE *, const char *);
 279 /* Wrapper to allow different internal representation for decimal floats. */
 280 extern void real_from_string3 (REAL_VALUE_TYPE *, const char *, machine_mode);
 281
 282 extern long real_to_target_fmt (long *, const REAL_VALUE_TYPE *,
 283                                 const struct real_format *);
 284 extern long real_to_target (long *, const REAL_VALUE_TYPE *, machine_mode);
 285
 286 extern void real_from_target_fmt (REAL_VALUE_TYPE *, const long *,
 287                                   const struct real_format *);
 288 extern void real_from_target (REAL_VALUE_TYPE *, const long *,
 289                               machine_mode);
 290
 291 extern void real_inf (REAL_VALUE_TYPE *);
 292
 293 extern bool real_nan (REAL_VALUE_TYPE *, const char *, int, machine_mode);
 294
 295 extern void real_maxval (REAL_VALUE_TYPE *, int, machine_mode);
 296
 297 extern void real_2expN (REAL_VALUE_TYPE *, int, machine_mode);
 298
 299 extern unsigned int real_hash (const REAL_VALUE_TYPE *);
 300
 301
 302 /* Target formats defined in real.c.  */
 303 extern const struct real_format ieee_single_format;
 304 extern const struct real_format mips_single_format;
 305 extern const struct real_format motorola_single_format;
 306 extern const struct real_format spu_single_format;
 307 extern const struct real_format ieee_double_format;
 308 extern const struct real_format mips_double_format;
 309 extern const struct real_format motorola_double_format;
 310 extern const struct real_format ieee_extended_motorola_format;
 311 extern const struct real_format ieee_extended_intel_96_format;
 312 extern const struct real_format ieee_extended_intel_96_round_53_format;
 313 extern const struct real_format ieee_extended_intel_128_format;
 314 extern const struct real_format ibm_extended_format;
 315 extern const struct real_format mips_extended_format;
 316 extern const struct real_format ieee_quad_format;
 317 extern const struct real_format mips_quad_format;
 318 extern const struct real_format vax_f_format;
 319 extern const struct real_format vax_d_format;
 320 extern const struct real_format vax_g_format;
 321 extern const struct real_format real_internal_format;
 322 extern const struct real_format decimal_single_format;
 323 extern const struct real_format decimal_double_format;
 324 extern const struct real_format decimal_quad_format;
 325 extern const struct real_format ieee_half_format;
 326 extern const struct real_format arm_half_format;
 327
 328
 329 /* ====================================================================== */
 330 /* Crap.  */
 331
 332 #define REAL_ARITHMETIC(value, code, d1, d2) \
 333   real_arithmetic (&(value), code, &(d1), &(d2))
 334
 335 #define REAL_VALUES_IDENTICAL(x, y)     real_identical (&(x), &(y))
 336 #define REAL_VALUES_EQUAL(x, y)         real_compare (EQ_EXPR, &(x), &(y))
 337 #define REAL_VALUES_LESS(x, y)          real_compare (LT_EXPR, &(x), &(y))
 338
 339 /* Determine whether a floating-point value X is infinite.  */
 340 #define REAL_VALUE_ISINF(x)             real_isinf (&(x))
 341
 342 /* Determine whether a floating-point value X is a NaN.  */
 343 #define REAL_VALUE_ISNAN(x)             real_isnan (&(x))
 344
 345 /* Determine whether a floating-point value X is negative.  */
 346 #define REAL_VALUE_NEGATIVE(x)          real_isneg (&(x))
 347
 348 /* Determine whether a floating-point value X is minus zero.  */
 349 #define REAL_VALUE_MINUS_ZERO(x)        real_isnegzero (&(x))
 350
 351 /* IN is a REAL_VALUE_TYPE.  OUT is an array of longs.  */
 352 #define REAL_VALUE_TO_TARGET_LONG_DOUBLE(IN, OUT)                       \
 353   real_to_target (OUT, &(IN),                                           \
 354                   mode_for_size (LONG_DOUBLE_TYPE_SIZE, MODE_FLOAT, 0))
 355
 356 #define REAL_VALUE_TO_TARGET_DOUBLE(IN, OUT) \
 357   real_to_target (OUT, &(IN), mode_for_size (64, MODE_FLOAT, 0))
 358
 359 /* IN is a REAL_VALUE_TYPE.  OUT is a long.  */
 360 #define REAL_VALUE_TO_TARGET_SINGLE(IN, OUT) \
 361   ((OUT) = real_to_target (NULL, &(IN), mode_for_size (32, MODE_FLOAT, 0)))
 362
 363 /* Real values to IEEE 754 decimal floats.  */
 364
 365 /* IN is a REAL_VALUE_TYPE.  OUT is an array of longs.  */
 366 #define REAL_VALUE_TO_TARGET_DECIMAL128(IN, OUT) \
 367   real_to_target (OUT, &(IN), mode_for_size (128, MODE_DECIMAL_FLOAT, 0))
 368
 369 #define REAL_VALUE_TO_TARGET_DECIMAL64(IN, OUT) \
 370   real_to_target (OUT, &(IN), mode_for_size (64, MODE_DECIMAL_FLOAT, 0))
 371
 372 /* IN is a REAL_VALUE_TYPE.  OUT is a long.  */
 373 #define REAL_VALUE_TO_TARGET_DECIMAL32(IN, OUT) \
 374   ((OUT) = real_to_target (NULL, &(IN), mode_for_size (32, MODE_DECIMAL_FLOAT, 0)))
 375
 376 extern REAL_VALUE_TYPE real_value_truncate (machine_mode,
 377                                             REAL_VALUE_TYPE);
 378
 379 extern REAL_VALUE_TYPE real_value_negate (const REAL_VALUE_TYPE *);
 380 extern REAL_VALUE_TYPE real_value_abs (const REAL_VALUE_TYPE *);
 381
 382 extern int significand_size (machine_mode);
 383
 384 extern REAL_VALUE_TYPE real_from_string2 (const char *, machine_mode);
 385
 386 #define REAL_VALUE_ATOF(s, m) \
 387   real_from_string2 (s, m)
 388
 389 #define CONST_DOUBLE_ATOF(s, m) \
 390   CONST_DOUBLE_FROM_REAL_VALUE (real_from_string2 (s, m), m)
 391
 392 #define REAL_VALUE_FIX(r) \
 393   real_to_integer (&(r))
 394
 395 /* ??? Not quite right.  */
 396 #define REAL_VALUE_UNSIGNED_FIX(r) \
 397   real_to_integer (&(r))
 398
 399 /* ??? These were added for Paranoia support.  */
 400
 401 /* Return floor log2(R).  */
 402 extern int real_exponent (const REAL_VALUE_TYPE *);
 403
 404 /* R = A * 2**EXP.  */
 405 extern void real_ldexp (REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *, int);
 406
 407 /* **** End of software floating point emulator interface macros **** */
 408 \f
 409 /* Constant real values 0, 1, 2, -1 and 0.5.  */
 410
 411 extern REAL_VALUE_TYPE dconst0;
 412 extern REAL_VALUE_TYPE dconst1;
 413 extern REAL_VALUE_TYPE dconst2;
 414 extern REAL_VALUE_TYPE dconstm1;
 415 extern REAL_VALUE_TYPE dconsthalf;
 416
 417 #define dconst_e()  (*dconst_e_ptr ())
 418 #define dconst_third()  (*dconst_third_ptr ())
 419 #define dconst_sqrt2()  (*dconst_sqrt2_ptr ())
 420
 421 /* Function to return the real value special constant 'e'.  */
 422 extern const REAL_VALUE_TYPE * dconst_e_ptr (void);
 423
 424 /* Returns the special REAL_VALUE_TYPE corresponding to 1/3.  */
 425 extern const REAL_VALUE_TYPE * dconst_third_ptr (void);
 426
 427 /* Returns the special REAL_VALUE_TYPE corresponding to sqrt(2).  */
 428 extern const REAL_VALUE_TYPE * dconst_sqrt2_ptr (void);
 429
 430 /* Function to return a real value (not a tree node)
 431    from a given integer constant.  */
 432 REAL_VALUE_TYPE real_value_from_int_cst (const_tree, const_tree);
 433
 434 /* Given a CONST_DOUBLE in FROM, store into TO the value it represents.  */
 435 #define REAL_VALUE_FROM_CONST_DOUBLE(to, from) \
 436   ((to) = *CONST_DOUBLE_REAL_VALUE (from))
 437
 438 /* Return a CONST_DOUBLE with value R and mode M.  */
 439 #define CONST_DOUBLE_FROM_REAL_VALUE(r, m) \
 440   const_double_from_real_value (r, m)
 441 extern rtx const_double_from_real_value (REAL_VALUE_TYPE, machine_mode);
 442
 443 /* Replace R by 1/R in the given machine mode, if the result is exact.  */
 444 extern bool exact_real_inverse (machine_mode, REAL_VALUE_TYPE *);
 445
 446 /* Return true if arithmetic on values in IMODE that were promoted
 447    from values in TMODE is equivalent to direct arithmetic on values
 448    in TMODE.  */
 449 bool real_can_shorten_arithmetic (machine_mode, machine_mode);
 450
 451 /* In tree.c: wrap up a REAL_VALUE_TYPE in a tree node.  */
 452 extern tree build_real (tree, REAL_VALUE_TYPE);
 453
 454 /* Calculate R as X raised to the integer exponent N in mode MODE.  */
 455 extern bool real_powi (REAL_VALUE_TYPE *, machine_mode,
 456                        const REAL_VALUE_TYPE *, HOST_WIDE_INT);
 457
 458 /* Standard round to integer value functions.  */
 459 extern void real_trunc (REAL_VALUE_TYPE *, machine_mode,
 460                         const REAL_VALUE_TYPE *);
 461 extern void real_floor (REAL_VALUE_TYPE *, machine_mode,
 462                         const REAL_VALUE_TYPE *);
 463 extern void real_ceil (REAL_VALUE_TYPE *, machine_mode,
 464                        const REAL_VALUE_TYPE *);
 465 extern void real_round (REAL_VALUE_TYPE *, machine_mode,
 466                         const REAL_VALUE_TYPE *);
 467
 468 /* Set the sign of R to the sign of X.  */
 469 extern void real_copysign (REAL_VALUE_TYPE *, const REAL_VALUE_TYPE *);
 470
 471 /* Check whether the real constant value given is an integer.  */
 472 extern bool real_isinteger (const REAL_VALUE_TYPE *c, machine_mode mode);
 473
 474 /* Write into BUF the maximum representable finite floating-point
 475    number, (1 - b**-p) * b**emax for a given FP format FMT as a hex
 476    float string.  BUF must be large enough to contain the result.  */
 477 extern void get_max_float (const struct real_format *, char *, size_t);
 478
 479 #ifndef GENERATOR_FILE
 480 /* real related routines.  */
 481 extern wide_int real_to_integer (const REAL_VALUE_TYPE *, bool *, int);
 482 extern void real_from_integer (REAL_VALUE_TYPE *, machine_mode,
 483                                const wide_int_ref &, signop);
 484 #endif
 485
 486 #endif /* ! GCC_REAL_H */