gcc/c-cppbuiltin.c

   1 /* Define builtin-in macros for the C family front ends.
   2    Copyright (C) 2002, 2003, 2004 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 2, 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 COPYING.  If not, write to the Free
  18 Software Foundation, 59 Temple Place - Suite 330, Boston, MA
  19 02111-1307, USA.  */
  20
  21 #include "config.h"
  22 #include "system.h"
  23 #include "coretypes.h"
  24 #include "tm.h"
  25 #include "tree.h"
  26 #include "version.h"
  27 #include "flags.h"
  28 #include "real.h"
  29 #include "c-common.h"
  30 #include "c-pragma.h"
  31 #include "output.h"
  32 #include "except.h"             /* For USING_SJLJ_EXCEPTIONS.  */
  33 #include "toplev.h"
  34 #include "tm_p.h"               /* Target prototypes.  */
  35 #include "target.h"
  36
  37 #ifndef TARGET_OS_CPP_BUILTINS
  38 # define TARGET_OS_CPP_BUILTINS()
  39 #endif
  40
  41 #ifndef TARGET_OBJFMT_CPP_BUILTINS
  42 # define TARGET_OBJFMT_CPP_BUILTINS()
  43 #endif
  44
  45 #ifndef REGISTER_PREFIX
  46 #define REGISTER_PREFIX ""
  47 #endif
  48
  49 /* Non-static as some targets don't use it.  */
  50 void builtin_define_std (const char *) ATTRIBUTE_UNUSED;
  51 static void builtin_define_with_value_n (const char *, const char *,
  52                                          size_t);
  53 static void builtin_define_with_int_value (const char *, HOST_WIDE_INT);
  54 static void builtin_define_with_hex_fp_value (const char *, tree,
  55                                               int, const char *,
  56                                               const char *);
  57 static void builtin_define_stdint_macros (void);
  58 static void builtin_define_type_max (const char *, tree, int);
  59 static void builtin_define_type_precision (const char *, tree);
  60 static void builtin_define_float_constants (const char *, const char *,
  61                                             tree);
  62 static void define__GNUC__ (void);
  63
  64 /* Define NAME with value TYPE precision.  */
  65 static void
  66 builtin_define_type_precision (const char *name, tree type)
  67 {
  68   builtin_define_with_int_value (name, TYPE_PRECISION (type));
  69 }
  70
  71 /* Define the float.h constants for TYPE using NAME_PREFIX and FP_SUFFIX.  */
  72 static void
  73 builtin_define_float_constants (const char *name_prefix, const char *fp_suffix, tree type)
  74 {
  75   /* Used to convert radix-based values to base 10 values in several cases.
  76
  77      In the max_exp -> max_10_exp conversion for 128-bit IEEE, we need at
  78      least 6 significant digits for correct results.  Using the fraction
  79      formed by (log(2)*1e6)/(log(10)*1e6) overflows a 32-bit integer as an
  80      intermediate; perhaps someone can find a better approximation, in the
  81      mean time, I suspect using doubles won't harm the bootstrap here.  */
  82
  83   const double log10_2 = .30102999566398119521;
  84   double log10_b;
  85   const struct real_format *fmt;
  86
  87   char name[64], buf[128];
  88   int dig, min_10_exp, max_10_exp;
  89   int decimal_dig;
  90
  91   fmt = REAL_MODE_FORMAT (TYPE_MODE (type));
  92
  93   /* The radix of the exponent representation.  */
  94   if (type == float_type_node)
  95     builtin_define_with_int_value ("__FLT_RADIX__", fmt->b);
  96   log10_b = log10_2 * fmt->log2_b;
  97
  98   /* The number of radix digits, p, in the floating-point significand.  */
  99   sprintf (name, "__%s_MANT_DIG__", name_prefix);
 100   builtin_define_with_int_value (name, fmt->p);
 101
 102   /* The number of decimal digits, q, such that any floating-point number
 103      with q decimal digits can be rounded into a floating-point number with
 104      p radix b digits and back again without change to the q decimal digits,
 105
 106         p log10 b                       if b is a power of 10
 107         floor((p - 1) log10 b)          otherwise
 108   */
 109   dig = (fmt->p - 1) * log10_b;
 110   sprintf (name, "__%s_DIG__", name_prefix);
 111   builtin_define_with_int_value (name, dig);
 112
 113   /* The minimum negative int x such that b**(x-1) is a normalized float.  */
 114   sprintf (name, "__%s_MIN_EXP__", name_prefix);
 115   sprintf (buf, "(%d)", fmt->emin);
 116   builtin_define_with_value (name, buf, 0);
 117
 118   /* The minimum negative int x such that 10**x is a normalized float,
 119
 120           ceil (log10 (b ** (emin - 1)))
 121         = ceil (log10 (b) * (emin - 1))
 122
 123      Recall that emin is negative, so the integer truncation calculates
 124      the ceiling, not the floor, in this case.  */
 125   min_10_exp = (fmt->emin - 1) * log10_b;
 126   sprintf (name, "__%s_MIN_10_EXP__", name_prefix);
 127   sprintf (buf, "(%d)", min_10_exp);
 128   builtin_define_with_value (name, buf, 0);
 129
 130   /* The maximum int x such that b**(x-1) is a representable float.  */
 131   sprintf (name, "__%s_MAX_EXP__", name_prefix);
 132   builtin_define_with_int_value (name, fmt->emax);
 133
 134   /* The maximum int x such that 10**x is in the range of representable
 135      finite floating-point numbers,
 136
 137           floor (log10((1 - b**-p) * b**emax))
 138         = floor (log10(1 - b**-p) + log10(b**emax))
 139         = floor (log10(1 - b**-p) + log10(b)*emax)
 140
 141      The safest thing to do here is to just compute this number.  But since
 142      we don't link cc1 with libm, we cannot.  We could implement log10 here
 143      a series expansion, but that seems too much effort because:
 144
 145      Note that the first term, for all extant p, is a number exceedingly close
 146      to zero, but slightly negative.  Note that the second term is an integer
 147      scaling an irrational number, and that because of the floor we are only
 148      interested in its integral portion.
 149
 150      In order for the first term to have any effect on the integral portion
 151      of the second term, the second term has to be exceedingly close to an
 152      integer itself (e.g. 123.000000000001 or something).  Getting a result
 153      that close to an integer requires that the irrational multiplicand have
 154      a long series of zeros in its expansion, which doesn't occur in the
 155      first 20 digits or so of log10(b).
 156
 157      Hand-waving aside, crunching all of the sets of constants above by hand
 158      does not yield a case for which the first term is significant, which
 159      in the end is all that matters.  */
 160   max_10_exp = fmt->emax * log10_b;
 161   sprintf (name, "__%s_MAX_10_EXP__", name_prefix);
 162   builtin_define_with_int_value (name, max_10_exp);
 163
 164   /* The number of decimal digits, n, such that any floating-point number
 165      can be rounded to n decimal digits and back again without change to
 166      the value.
 167
 168         p * log10(b)                    if b is a power of 10
 169         ceil(1 + p * log10(b))          otherwise
 170
 171      The only macro we care about is this number for the widest supported
 172      floating type, but we want this value for rendering constants below.  */
 173   {
 174     double d_decimal_dig = 1 + fmt->p * log10_b;
 175     decimal_dig = d_decimal_dig;
 176     if (decimal_dig < d_decimal_dig)
 177       decimal_dig++;
 178   }
 179   if (type == long_double_type_node)
 180     builtin_define_with_int_value ("__DECIMAL_DIG__", decimal_dig);
 181
 182   /* Since, for the supported formats, B is always a power of 2, we
 183      construct the following numbers directly as a hexadecimal
 184      constants.  */
 185
 186   /* The maximum representable finite floating-point number,
 187      (1 - b**-p) * b**emax  */
 188   {
 189     int i, n;
 190     char *p;
 191
 192     strcpy (buf, "0x0.");
 193     n = fmt->p * fmt->log2_b;
 194     for (i = 0, p = buf + 4; i + 3 < n; i += 4)
 195       *p++ = 'f';
 196     if (i < n)
 197       *p++ = "08ce"[n - i];
 198     sprintf (p, "p%d", fmt->emax * fmt->log2_b);
 199     if (fmt->pnan < fmt->p)
 200       {
 201         /* This is an IBM extended double format made up of two IEEE
 202            doubles.  The value of the long double is the sum of the
 203            values of the two parts.  The most significant part is
 204            required to be the value of the long double rounded to the
 205            nearest double.  Rounding means we need a slightly smaller
 206            value for LDBL_MAX.  */
 207         buf[4 + fmt->pnan / 4] = "7bde"[fmt->pnan % 4];
 208       }
 209   }
 210   sprintf (name, "__%s_MAX__", name_prefix);
 211   builtin_define_with_hex_fp_value (name, type, decimal_dig, buf, fp_suffix);
 212
 213   /* The minimum normalized positive floating-point number,
 214      b**(emin-1).  */
 215   sprintf (name, "__%s_MIN__", name_prefix);
 216   sprintf (buf, "0x1p%d", (fmt->emin - 1) * fmt->log2_b);
 217   builtin_define_with_hex_fp_value (name, type, decimal_dig, buf, fp_suffix);
 218
 219   /* The difference between 1 and the least value greater than 1 that is
 220      representable in the given floating point type, b**(1-p).  */
 221   sprintf (name, "__%s_EPSILON__", name_prefix);
 222   sprintf (buf, "0x1p%d", (1 - fmt->p) * fmt->log2_b);
 223   builtin_define_with_hex_fp_value (name, type, decimal_dig, buf, fp_suffix);
 224
 225   /* For C++ std::numeric_limits<T>::denorm_min.  The minimum denormalized
 226      positive floating-point number, b**(emin-p).  Zero for formats that
 227      don't support denormals.  */
 228   sprintf (name, "__%s_DENORM_MIN__", name_prefix);
 229   if (fmt->has_denorm)
 230     {
 231       sprintf (buf, "0x1p%d", (fmt->emin - fmt->p) * fmt->log2_b);
 232       builtin_define_with_hex_fp_value (name, type, decimal_dig,
 233                                         buf, fp_suffix);
 234     }
 235   else
 236     {
 237       sprintf (buf, "0.0%s", fp_suffix);
 238       builtin_define_with_value (name, buf, 0);
 239     }
 240
 241   /* For C++ std::numeric_limits<T>::has_infinity.  */
 242   sprintf (name, "__%s_HAS_INFINITY__", name_prefix);
 243   builtin_define_with_int_value (name,
 244                                  MODE_HAS_INFINITIES (TYPE_MODE (type)));
 245   /* For C++ std::numeric_limits<T>::has_quiet_NaN.  We do not have a
 246      predicate to distinguish a target that has both quiet and
 247      signalling NaNs from a target that has only quiet NaNs or only
 248      signalling NaNs, so we assume that a target that has any kind of
 249      NaN has quiet NaNs.  */
 250   sprintf (name, "__%s_HAS_QUIET_NAN__", name_prefix);
 251   builtin_define_with_int_value (name, MODE_HAS_NANS (TYPE_MODE (type)));
 252 }
 253
 254 /* Define __GNUC__, __GNUC_MINOR__ and __GNUC_PATCHLEVEL__.  */
 255 static void
 256 define__GNUC__ (void)
 257 {
 258   /* The format of the version string, enforced below, is
 259      ([^0-9]*-)?[0-9]+[.][0-9]+([.][0-9]+)?([- ].*)?  */
 260   const char *q, *v = version_string;
 261
 262   while (*v && ! ISDIGIT (*v))
 263     v++;
 264   if (!*v || (v > version_string && v[-1] != '-'))
 265     abort ();
 266
 267   q = v;
 268   while (ISDIGIT (*v))
 269     v++;
 270   builtin_define_with_value_n ("__GNUC__", q, v - q);
 271   if (c_dialect_cxx ())
 272     builtin_define_with_value_n ("__GNUG__", q, v - q);
 273
 274   if (*v != '.' || !ISDIGIT (v[1]))
 275     abort ();
 276   q = ++v;
 277   while (ISDIGIT (*v))
 278     v++;
 279   builtin_define_with_value_n ("__GNUC_MINOR__", q, v - q);
 280
 281   if (*v == '.')
 282     {
 283       if (!ISDIGIT (v[1]))
 284         abort ();
 285       q = ++v;
 286       while (ISDIGIT (*v))
 287         v++;
 288       builtin_define_with_value_n ("__GNUC_PATCHLEVEL__", q, v - q);
 289     }
 290   else
 291     builtin_define_with_value_n ("__GNUC_PATCHLEVEL__", "0", 1);
 292
 293   if (*v && *v != ' ' && *v != '-')
 294     abort ();
 295 }
 296
 297 /* Define macros used by <stdint.h>.  Currently only defines limits
 298    for intmax_t, used by the testsuite.  */
 299 static void
 300 builtin_define_stdint_macros (void)
 301 {
 302   int intmax_long;
 303   if (intmax_type_node == long_long_integer_type_node)
 304     intmax_long = 2;
 305   else if (intmax_type_node == long_integer_type_node)
 306     intmax_long = 1;
 307   else if (intmax_type_node == integer_type_node)
 308     intmax_long = 0;
 309   else
 310     abort ();
 311   builtin_define_type_max ("__INTMAX_MAX__", intmax_type_node, intmax_long);
 312 }
 313
 314 /* Hook that registers front end and target-specific built-ins.  */
 315 void
 316 c_cpp_builtins (cpp_reader *pfile)
 317 {
 318   /* -undef turns off target-specific built-ins.  */
 319   if (flag_undef)
 320     return;
 321
 322   define__GNUC__ ();
 323
 324   /* For stddef.h.  They require macros defined in c-common.c.  */
 325   c_stddef_cpp_builtins ();
 326
 327   if (c_dialect_cxx ())
 328     {
 329       if (SUPPORTS_ONE_ONLY)
 330         cpp_define (pfile, "__GXX_WEAK__=1");
 331       else
 332         cpp_define (pfile, "__GXX_WEAK__=0");
 333       if (warn_deprecated)
 334         cpp_define (pfile, "__DEPRECATED");
 335     }
 336   /* Note that we define this for C as well, so that we know if
 337      __attribute__((cleanup)) will interface with EH.  */
 338   if (flag_exceptions)
 339     cpp_define (pfile, "__EXCEPTIONS");
 340
 341   /* Represents the C++ ABI version, always defined so it can be used while
 342      preprocessing C and assembler.  */
 343   if (flag_abi_version == 0)
 344     /* Use a very large value so that:
 345
 346          #if __GXX_ABI_VERSION >= <value for version X>
 347
 348        will work whether the user explicitly says "-fabi-version=x" or
 349        "-fabi-version=0".  Do not use INT_MAX because that will be
 350        different from system to system.  */
 351     builtin_define_with_int_value ("__GXX_ABI_VERSION", 999999);
 352   else if (flag_abi_version == 1)
 353     /* Due to an historical accident, this version had the value
 354        "102".  */
 355     builtin_define_with_int_value ("__GXX_ABI_VERSION", 102);
 356   else
 357     /* Newer versions have values 1002, 1003, ....  */
 358     builtin_define_with_int_value ("__GXX_ABI_VERSION",
 359                                    1000 + flag_abi_version);
 360
 361   /* libgcc needs to know this.  */
 362   if (USING_SJLJ_EXCEPTIONS)
 363     cpp_define (pfile, "__USING_SJLJ_EXCEPTIONS__");
 364
 365   /* limits.h needs to know these.  */
 366   builtin_define_type_max ("__SCHAR_MAX__", signed_char_type_node, 0);
 367   builtin_define_type_max ("__SHRT_MAX__", short_integer_type_node, 0);
 368   builtin_define_type_max ("__INT_MAX__", integer_type_node, 0);
 369   builtin_define_type_max ("__LONG_MAX__", long_integer_type_node, 1);
 370   builtin_define_type_max ("__LONG_LONG_MAX__", long_long_integer_type_node, 2);
 371   builtin_define_type_max ("__WCHAR_MAX__", wchar_type_node, 0);
 372
 373   builtin_define_type_precision ("__CHAR_BIT__", char_type_node);
 374
 375   /* stdint.h (eventually) and the testsuite need to know these.  */
 376   builtin_define_stdint_macros ();
 377
 378   /* float.h needs to know these.  */
 379
 380   builtin_define_with_int_value ("__FLT_EVAL_METHOD__",
 381                                  TARGET_FLT_EVAL_METHOD);
 382
 383   builtin_define_float_constants ("FLT", "F", float_type_node);
 384   builtin_define_float_constants ("DBL", "", double_type_node);
 385   builtin_define_float_constants ("LDBL", "L", long_double_type_node);
 386
 387   /* For use in assembly language.  */
 388   builtin_define_with_value ("__REGISTER_PREFIX__", REGISTER_PREFIX, 0);
 389   builtin_define_with_value ("__USER_LABEL_PREFIX__", user_label_prefix, 0);
 390
 391   /* Misc.  */
 392   builtin_define_with_value ("__VERSION__", version_string, 1);
 393
 394   /* Definitions for LP64 model.  */
 395   if (TYPE_PRECISION (long_integer_type_node) == 64
 396       && POINTER_SIZE == 64
 397       && TYPE_PRECISION (integer_type_node) == 32)
 398     {
 399       cpp_define (pfile, "_LP64");
 400       cpp_define (pfile, "__LP64__");
 401     }
 402
 403   /* Other target-independent built-ins determined by command-line
 404      options.  */
 405   if (optimize_size)
 406     cpp_define (pfile, "__OPTIMIZE_SIZE__");
 407   if (optimize)
 408     cpp_define (pfile, "__OPTIMIZE__");
 409
 410   if (fast_math_flags_set_p ())
 411     cpp_define (pfile, "__FAST_MATH__");
 412   if (flag_really_no_inline)
 413     cpp_define (pfile, "__NO_INLINE__");
 414   if (flag_signaling_nans)
 415     cpp_define (pfile, "__SUPPORT_SNAN__");
 416   if (flag_finite_math_only)
 417     cpp_define (pfile, "__FINITE_MATH_ONLY__=1");
 418   else
 419     cpp_define (pfile, "__FINITE_MATH_ONLY__=0");
 420
 421   if (flag_iso)
 422     cpp_define (pfile, "__STRICT_ANSI__");
 423
 424   if (!flag_signed_char)
 425     cpp_define (pfile, "__CHAR_UNSIGNED__");
 426
 427   if (c_dialect_cxx () && TYPE_UNSIGNED (wchar_type_node))
 428     cpp_define (pfile, "__WCHAR_UNSIGNED__");
 429
 430   /* Make the choice of ObjC runtime visible to source code.  */
 431   if (c_dialect_objc () && flag_next_runtime)
 432     cpp_define (pfile, "__NEXT_RUNTIME__");
 433
 434   /* Show the availability of some target pragmas.  */
 435   if (flag_mudflap || targetm.handle_pragma_redefine_extname)
 436     cpp_define (pfile, "__PRAGMA_REDEFINE_EXTNAME");
 437
 438   if (targetm.handle_pragma_extern_prefix)
 439     cpp_define (pfile, "__PRAGMA_EXTERN_PREFIX");
 440
 441   /* A straightforward target hook doesn't work, because of problems
 442      linking that hook's body when part of non-C front ends.  */
 443 # define preprocessing_asm_p() (cpp_get_options (pfile)->lang == CLK_ASM)
 444 # define preprocessing_trad_p() (cpp_get_options (pfile)->traditional)
 445 # define builtin_define(TXT) cpp_define (pfile, TXT)
 446 # define builtin_assert(TXT) cpp_assert (pfile, TXT)
 447   TARGET_CPU_CPP_BUILTINS ();
 448   TARGET_OS_CPP_BUILTINS ();
 449   TARGET_OBJFMT_CPP_BUILTINS ();
 450
 451   /* Support the __declspec keyword by turning them into attributes.
 452      Note that the current way we do this may result in a collision
 453      with predefined attributes later on.  This can be solved by using
 454      one attribute, say __declspec__, and passing args to it.  The
 455      problem with that approach is that args are not accumulated: each
 456      new appearance would clobber any existing args.  */
 457   if (TARGET_DECLSPEC)
 458     builtin_define ("__declspec(x)=__attribute__((x))");
 459 }
 460
 461 /* Pass an object-like macro.  If it doesn't lie in the user's
 462    namespace, defines it unconditionally.  Otherwise define a version
 463    with two leading underscores, and another version with two leading
 464    and trailing underscores, and define the original only if an ISO
 465    standard was not nominated.
 466
 467    e.g. passing "unix" defines "__unix", "__unix__" and possibly
 468    "unix".  Passing "_mips" defines "__mips", "__mips__" and possibly
 469    "_mips".  */
 470 void
 471 builtin_define_std (const char *macro)
 472 {
 473   size_t len = strlen (macro);
 474   char *buff = alloca (len + 5);
 475   char *p = buff + 2;
 476   char *q = p + len;
 477
 478   /* prepend __ (or maybe just _) if in user's namespace.  */
 479   memcpy (p, macro, len + 1);
 480   if (!( *p == '_' && (p[1] == '_' || ISUPPER (p[1]))))
 481     {
 482       if (*p != '_')
 483         *--p = '_';
 484       if (p[1] != '_')
 485         *--p = '_';
 486     }
 487   cpp_define (parse_in, p);
 488
 489   /* If it was in user's namespace...  */
 490   if (p != buff + 2)
 491     {
 492       /* Define the macro with leading and following __.  */
 493       if (q[-1] != '_')
 494         *q++ = '_';
 495       if (q[-2] != '_')
 496         *q++ = '_';
 497       *q = '\0';
 498       cpp_define (parse_in, p);
 499
 500       /* Finally, define the original macro if permitted.  */
 501       if (!flag_iso)
 502         cpp_define (parse_in, macro);
 503     }
 504 }
 505
 506 /* Pass an object-like macro and a value to define it to.  The third
 507    parameter says whether or not to turn the value into a string
 508    constant.  */
 509 void
 510 builtin_define_with_value (const char *macro, const char *expansion, int is_str)
 511 {
 512   char *buf;
 513   size_t mlen = strlen (macro);
 514   size_t elen = strlen (expansion);
 515   size_t extra = 2;  /* space for an = and a NUL */
 516
 517   if (is_str)
 518     extra += 2;  /* space for two quote marks */
 519
 520   buf = alloca (mlen + elen + extra);
 521   if (is_str)
 522     sprintf (buf, "%s=\"%s\"", macro, expansion);
 523   else
 524     sprintf (buf, "%s=%s", macro, expansion);
 525
 526   cpp_define (parse_in, buf);
 527 }
 528
 529 /* Pass an object-like macro and a value to define it to.  The third
 530    parameter is the length of the expansion.  */
 531 static void
 532 builtin_define_with_value_n (const char *macro, const char *expansion, size_t elen)
 533 {
 534   char *buf;
 535   size_t mlen = strlen (macro);
 536
 537   /* Space for an = and a NUL.  */
 538   buf = alloca (mlen + elen + 2);
 539   memcpy (buf, macro, mlen);
 540   buf[mlen] = '=';
 541   memcpy (buf + mlen + 1, expansion, elen);
 542   buf[mlen + elen + 1] = '\0';
 543
 544   cpp_define (parse_in, buf);
 545 }
 546
 547 /* Pass an object-like macro and an integer value to define it to.  */
 548 static void
 549 builtin_define_with_int_value (const char *macro, HOST_WIDE_INT value)
 550 {
 551   char *buf;
 552   size_t mlen = strlen (macro);
 553   size_t vlen = 18;
 554   size_t extra = 2; /* space for = and NUL.  */
 555
 556   buf = alloca (mlen + vlen + extra);
 557   memcpy (buf, macro, mlen);
 558   buf[mlen] = '=';
 559   sprintf (buf + mlen + 1, HOST_WIDE_INT_PRINT_DEC, value);
 560
 561   cpp_define (parse_in, buf);
 562 }
 563
 564 /* Pass an object-like macro a hexadecimal floating-point value.  */
 565 static void
 566 builtin_define_with_hex_fp_value (const char *macro,
 567                                   tree type ATTRIBUTE_UNUSED, int digits,
 568                                   const char *hex_str, const char *fp_suffix)
 569 {
 570   REAL_VALUE_TYPE real;
 571   char dec_str[64], buf[256];
 572
 573   /* Hex values are really cool and convenient, except that they're
 574      not supported in strict ISO C90 mode.  First, the "p-" sequence
 575      is not valid as part of a preprocessor number.  Second, we get a
 576      pedwarn from the preprocessor, which has no context, so we can't
 577      suppress the warning with __extension__.
 578
 579      So instead what we do is construct the number in hex (because
 580      it's easy to get the exact correct value), parse it as a real,
 581      then print it back out as decimal.  */
 582
 583   real_from_string (&real, hex_str);
 584   real_to_decimal (dec_str, &real, sizeof (dec_str), digits, 0);
 585
 586   sprintf (buf, "%s=%s%s", macro, dec_str, fp_suffix);
 587   cpp_define (parse_in, buf);
 588 }
 589
 590 /* Define MAX for TYPE based on the precision of the type.  IS_LONG is
 591    1 for type "long" and 2 for "long long".  We have to handle
 592    unsigned types, since wchar_t might be unsigned.  */
 593
 594 static void
 595 builtin_define_type_max (const char *macro, tree type, int is_long)
 596 {
 597   static const char *const values[]
 598     = { "127", "255",
 599         "32767", "65535",
 600         "2147483647", "4294967295",
 601         "9223372036854775807", "18446744073709551615",
 602         "170141183460469231731687303715884105727",
 603         "340282366920938463463374607431768211455" };
 604   static const char *const suffixes[] = { "", "U", "L", "UL", "LL", "ULL" };
 605
 606   const char *value, *suffix;
 607   char *buf;
 608   size_t idx;
 609
 610   /* Pre-rendering the values mean we don't have to futz with printing a
 611      multi-word decimal value.  There are also a very limited number of
 612      precisions that we support, so it's really a waste of time.  */
 613   switch (TYPE_PRECISION (type))
 614     {
 615     case 8:     idx = 0; break;
 616     case 16:    idx = 2; break;
 617     case 32:    idx = 4; break;
 618     case 64:    idx = 6; break;
 619     case 128:   idx = 8; break;
 620     default:    abort ();
 621     }
 622
 623   value = values[idx + TYPE_UNSIGNED (type)];
 624   suffix = suffixes[is_long * 2 + TYPE_UNSIGNED (type)];
 625
 626   buf = alloca (strlen (macro) + 1 + strlen (value) + strlen (suffix) + 1);
 627   sprintf (buf, "%s=%s%s", macro, value, suffix);
 628
 629   cpp_define (parse_in, buf);
 630 }