gcc/c-cppbuiltin.c

   1 /* Define builtin-in macros for the C family front ends.
   2    Copyright (C) 2002, 2003, 2004, 2005 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   if (fmt->pnan < fmt->p)
 223     /* This is an IBM extended double format, so 1.0 + any double is
 224        representable precisely.  */
 225       sprintf (buf, "0x1p%d", (fmt->emin - fmt->p) * fmt->log2_b);
 226     else
 227       sprintf (buf, "0x1p%d", (1 - fmt->p) * fmt->log2_b);
 228   builtin_define_with_hex_fp_value (name, type, decimal_dig, buf, fp_suffix);
 229
 230   /* For C++ std::numeric_limits<T>::denorm_min.  The minimum denormalized
 231      positive floating-point number, b**(emin-p).  Zero for formats that
 232      don't support denormals.  */
 233   sprintf (name, "__%s_DENORM_MIN__", name_prefix);
 234   if (fmt->has_denorm)
 235     {
 236       sprintf (buf, "0x1p%d", (fmt->emin - fmt->p) * fmt->log2_b);
 237       builtin_define_with_hex_fp_value (name, type, decimal_dig,
 238                                         buf, fp_suffix);
 239     }
 240   else
 241     {
 242       sprintf (buf, "0.0%s", fp_suffix);
 243       builtin_define_with_value (name, buf, 0);
 244     }
 245
 246   /* For C++ std::numeric_limits<T>::has_infinity.  */
 247   sprintf (name, "__%s_HAS_INFINITY__", name_prefix);
 248   builtin_define_with_int_value (name,
 249                                  MODE_HAS_INFINITIES (TYPE_MODE (type)));
 250   /* For C++ std::numeric_limits<T>::has_quiet_NaN.  We do not have a
 251      predicate to distinguish a target that has both quiet and
 252      signalling NaNs from a target that has only quiet NaNs or only
 253      signalling NaNs, so we assume that a target that has any kind of
 254      NaN has quiet NaNs.  */
 255   sprintf (name, "__%s_HAS_QUIET_NAN__", name_prefix);
 256   builtin_define_with_int_value (name, MODE_HAS_NANS (TYPE_MODE (type)));
 257 }
 258
 259 /* Define __GNUC__, __GNUC_MINOR__ and __GNUC_PATCHLEVEL__.  */
 260 static void
 261 define__GNUC__ (void)
 262 {
 263   /* The format of the version string, enforced below, is
 264      ([^0-9]*-)?[0-9]+[.][0-9]+([.][0-9]+)?([- ].*)?  */
 265   const char *q, *v = version_string;
 266
 267   while (*v && !ISDIGIT (*v))
 268     v++;
 269   gcc_assert (*v && (v <= version_string || v[-1] == '-'));
 270
 271   q = v;
 272   while (ISDIGIT (*v))
 273     v++;
 274   builtin_define_with_value_n ("__GNUC__", q, v - q);
 275   if (c_dialect_cxx ())
 276     builtin_define_with_value_n ("__GNUG__", q, v - q);
 277
 278   gcc_assert (*v == '.' && ISDIGIT (v[1]));
 279
 280   q = ++v;
 281   while (ISDIGIT (*v))
 282     v++;
 283   builtin_define_with_value_n ("__GNUC_MINOR__", q, v - q);
 284
 285   if (*v == '.')
 286     {
 287       gcc_assert (ISDIGIT (v[1]));
 288       q = ++v;
 289       while (ISDIGIT (*v))
 290         v++;
 291       builtin_define_with_value_n ("__GNUC_PATCHLEVEL__", q, v - q);
 292     }
 293   else
 294     builtin_define_with_value_n ("__GNUC_PATCHLEVEL__", "0", 1);
 295
 296   gcc_assert (!*v || *v == ' ' || *v == '-');
 297 }
 298
 299 /* Define macros used by <stdint.h>.  Currently only defines limits
 300    for intmax_t, used by the testsuite.  */
 301 static void
 302 builtin_define_stdint_macros (void)
 303 {
 304   int intmax_long;
 305   if (intmax_type_node == long_long_integer_type_node)
 306     intmax_long = 2;
 307   else if (intmax_type_node == long_integer_type_node)
 308     intmax_long = 1;
 309   else if (intmax_type_node == integer_type_node)
 310     intmax_long = 0;
 311   else
 312     gcc_unreachable ();
 313   builtin_define_type_max ("__INTMAX_MAX__", intmax_type_node, intmax_long);
 314 }
 315
 316 /* Hook that registers front end and target-specific built-ins.  */
 317 void
 318 c_cpp_builtins (cpp_reader *pfile)
 319 {
 320   /* -undef turns off target-specific built-ins.  */
 321   if (flag_undef)
 322     return;
 323
 324   define__GNUC__ ();
 325
 326   /* For stddef.h.  They require macros defined in c-common.c.  */
 327   c_stddef_cpp_builtins ();
 328
 329   if (c_dialect_cxx ())
 330     {
 331       if (flag_weak && SUPPORTS_ONE_ONLY)
 332         cpp_define (pfile, "__GXX_WEAK__=1");
 333       else
 334         cpp_define (pfile, "__GXX_WEAK__=0");
 335       if (warn_deprecated)
 336         cpp_define (pfile, "__DEPRECATED");
 337     }
 338   /* Note that we define this for C as well, so that we know if
 339      __attribute__((cleanup)) will interface with EH.  */
 340   if (flag_exceptions)
 341     cpp_define (pfile, "__EXCEPTIONS");
 342
 343   /* Represents the C++ ABI version, always defined so it can be used while
 344      preprocessing C and assembler.  */
 345   if (flag_abi_version == 0)
 346     /* Use a very large value so that:
 347
 348          #if __GXX_ABI_VERSION >= <value for version X>
 349
 350        will work whether the user explicitly says "-fabi-version=x" or
 351        "-fabi-version=0".  Do not use INT_MAX because that will be
 352        different from system to system.  */
 353     builtin_define_with_int_value ("__GXX_ABI_VERSION", 999999);
 354   else if (flag_abi_version == 1)
 355     /* Due to a historical accident, this version had the value
 356        "102".  */
 357     builtin_define_with_int_value ("__GXX_ABI_VERSION", 102);
 358   else
 359     /* Newer versions have values 1002, 1003, ....  */
 360     builtin_define_with_int_value ("__GXX_ABI_VERSION",
 361                                    1000 + flag_abi_version);
 362
 363   /* libgcc needs to know this.  */
 364   if (USING_SJLJ_EXCEPTIONS)
 365     cpp_define (pfile, "__USING_SJLJ_EXCEPTIONS__");
 366
 367   /* limits.h needs to know these.  */
 368   builtin_define_type_max ("__SCHAR_MAX__", signed_char_type_node, 0);
 369   builtin_define_type_max ("__SHRT_MAX__", short_integer_type_node, 0);
 370   builtin_define_type_max ("__INT_MAX__", integer_type_node, 0);
 371   builtin_define_type_max ("__LONG_MAX__", long_integer_type_node, 1);
 372   builtin_define_type_max ("__LONG_LONG_MAX__", long_long_integer_type_node, 2);
 373   builtin_define_type_max ("__WCHAR_MAX__", wchar_type_node, 0);
 374
 375   builtin_define_type_precision ("__CHAR_BIT__", char_type_node);
 376
 377   /* stdint.h (eventually) and the testsuite need to know these.  */
 378   builtin_define_stdint_macros ();
 379
 380   /* float.h needs to know these.  */
 381
 382   builtin_define_with_int_value ("__FLT_EVAL_METHOD__",
 383                                  TARGET_FLT_EVAL_METHOD);
 384
 385   builtin_define_float_constants ("FLT", "F", float_type_node);
 386   builtin_define_float_constants ("DBL", "", double_type_node);
 387   builtin_define_float_constants ("LDBL", "L", long_double_type_node);
 388
 389   /* For use in assembly language.  */
 390   builtin_define_with_value ("__REGISTER_PREFIX__", REGISTER_PREFIX, 0);
 391   builtin_define_with_value ("__USER_LABEL_PREFIX__", user_label_prefix, 0);
 392
 393   /* Misc.  */
 394   builtin_define_with_value ("__VERSION__", version_string, 1);
 395
 396   /* Definitions for LP64 model.  */
 397   if (TYPE_PRECISION (long_integer_type_node) == 64
 398       && POINTER_SIZE == 64
 399       && TYPE_PRECISION (integer_type_node) == 32)
 400     {
 401       cpp_define (pfile, "_LP64");
 402       cpp_define (pfile, "__LP64__");
 403     }
 404
 405   /* Other target-independent built-ins determined by command-line
 406      options.  */
 407   if (optimize_size)
 408     cpp_define (pfile, "__OPTIMIZE_SIZE__");
 409   if (optimize)
 410     cpp_define (pfile, "__OPTIMIZE__");
 411
 412   if (fast_math_flags_set_p ())
 413     cpp_define (pfile, "__FAST_MATH__");
 414   if (flag_really_no_inline)
 415     cpp_define (pfile, "__NO_INLINE__");
 416   if (flag_signaling_nans)
 417     cpp_define (pfile, "__SUPPORT_SNAN__");
 418   if (flag_finite_math_only)
 419     cpp_define (pfile, "__FINITE_MATH_ONLY__=1");
 420   else
 421     cpp_define (pfile, "__FINITE_MATH_ONLY__=0");
 422
 423   if (flag_iso)
 424     cpp_define (pfile, "__STRICT_ANSI__");
 425
 426   if (!flag_signed_char)
 427     cpp_define (pfile, "__CHAR_UNSIGNED__");
 428
 429   if (c_dialect_cxx () && TYPE_UNSIGNED (wchar_type_node))
 430     cpp_define (pfile, "__WCHAR_UNSIGNED__");
 431
 432   /* Make the choice of ObjC runtime visible to source code.  */
 433   if (c_dialect_objc () && flag_next_runtime)
 434     cpp_define (pfile, "__NEXT_RUNTIME__");
 435
 436   /* Show the availability of some target pragmas.  */
 437   if (flag_mudflap || targetm.handle_pragma_redefine_extname)
 438     cpp_define (pfile, "__PRAGMA_REDEFINE_EXTNAME");
 439
 440   if (targetm.handle_pragma_extern_prefix)
 441     cpp_define (pfile, "__PRAGMA_EXTERN_PREFIX");
 442
 443   /* A straightforward target hook doesn't work, because of problems
 444      linking that hook's body when part of non-C front ends.  */
 445 # define preprocessing_asm_p() (cpp_get_options (pfile)->lang == CLK_ASM)
 446 # define preprocessing_trad_p() (cpp_get_options (pfile)->traditional)
 447 # define builtin_define(TXT) cpp_define (pfile, TXT)
 448 # define builtin_assert(TXT) cpp_assert (pfile, TXT)
 449   TARGET_CPU_CPP_BUILTINS ();
 450   TARGET_OS_CPP_BUILTINS ();
 451   TARGET_OBJFMT_CPP_BUILTINS ();
 452
 453   /* Support the __declspec keyword by turning them into attributes.
 454      Note that the current way we do this may result in a collision
 455      with predefined attributes later on.  This can be solved by using
 456      one attribute, say __declspec__, and passing args to it.  The
 457      problem with that approach is that args are not accumulated: each
 458      new appearance would clobber any existing args.  */
 459   if (TARGET_DECLSPEC)
 460     builtin_define ("__declspec(x)=__attribute__((x))");
 461 }
 462
 463 /* Pass an object-like macro.  If it doesn't lie in the user's
 464    namespace, defines it unconditionally.  Otherwise define a version
 465    with two leading underscores, and another version with two leading
 466    and trailing underscores, and define the original only if an ISO
 467    standard was not nominated.
 468
 469    e.g. passing "unix" defines "__unix", "__unix__" and possibly
 470    "unix".  Passing "_mips" defines "__mips", "__mips__" and possibly
 471    "_mips".  */
 472 void
 473 builtin_define_std (const char *macro)
 474 {
 475   size_t len = strlen (macro);
 476   char *buff = alloca (len + 5);
 477   char *p = buff + 2;
 478   char *q = p + len;
 479
 480   /* prepend __ (or maybe just _) if in user's namespace.  */
 481   memcpy (p, macro, len + 1);
 482   if (!( *p == '_' && (p[1] == '_' || ISUPPER (p[1]))))
 483     {
 484       if (*p != '_')
 485         *--p = '_';
 486       if (p[1] != '_')
 487         *--p = '_';
 488     }
 489   cpp_define (parse_in, p);
 490
 491   /* If it was in user's namespace...  */
 492   if (p != buff + 2)
 493     {
 494       /* Define the macro with leading and following __.  */
 495       if (q[-1] != '_')
 496         *q++ = '_';
 497       if (q[-2] != '_')
 498         *q++ = '_';
 499       *q = '\0';
 500       cpp_define (parse_in, p);
 501
 502       /* Finally, define the original macro if permitted.  */
 503       if (!flag_iso)
 504         cpp_define (parse_in, macro);
 505     }
 506 }
 507
 508 /* Pass an object-like macro and a value to define it to.  The third
 509    parameter says whether or not to turn the value into a string
 510    constant.  */
 511 void
 512 builtin_define_with_value (const char *macro, const char *expansion, int is_str)
 513 {
 514   char *buf;
 515   size_t mlen = strlen (macro);
 516   size_t elen = strlen (expansion);
 517   size_t extra = 2;  /* space for an = and a NUL */
 518
 519   if (is_str)
 520     extra += 2;  /* space for two quote marks */
 521
 522   buf = alloca (mlen + elen + extra);
 523   if (is_str)
 524     sprintf (buf, "%s=\"%s\"", macro, expansion);
 525   else
 526     sprintf (buf, "%s=%s", macro, expansion);
 527
 528   cpp_define (parse_in, buf);
 529 }
 530
 531 /* Pass an object-like macro and a value to define it to.  The third
 532    parameter is the length of the expansion.  */
 533 static void
 534 builtin_define_with_value_n (const char *macro, const char *expansion, size_t elen)
 535 {
 536   char *buf;
 537   size_t mlen = strlen (macro);
 538
 539   /* Space for an = and a NUL.  */
 540   buf = alloca (mlen + elen + 2);
 541   memcpy (buf, macro, mlen);
 542   buf[mlen] = '=';
 543   memcpy (buf + mlen + 1, expansion, elen);
 544   buf[mlen + elen + 1] = '\0';
 545
 546   cpp_define (parse_in, buf);
 547 }
 548
 549 /* Pass an object-like macro and an integer value to define it to.  */
 550 static void
 551 builtin_define_with_int_value (const char *macro, HOST_WIDE_INT value)
 552 {
 553   char *buf;
 554   size_t mlen = strlen (macro);
 555   size_t vlen = 18;
 556   size_t extra = 2; /* space for = and NUL.  */
 557
 558   buf = alloca (mlen + vlen + extra);
 559   memcpy (buf, macro, mlen);
 560   buf[mlen] = '=';
 561   sprintf (buf + mlen + 1, HOST_WIDE_INT_PRINT_DEC, value);
 562
 563   cpp_define (parse_in, buf);
 564 }
 565
 566 /* Pass an object-like macro a hexadecimal floating-point value.  */
 567 static void
 568 builtin_define_with_hex_fp_value (const char *macro,
 569                                   tree type ATTRIBUTE_UNUSED, int digits,
 570                                   const char *hex_str, const char *fp_suffix)
 571 {
 572   REAL_VALUE_TYPE real;
 573   char dec_str[64], buf[256];
 574
 575   /* Hex values are really cool and convenient, except that they're
 576      not supported in strict ISO C90 mode.  First, the "p-" sequence
 577      is not valid as part of a preprocessor number.  Second, we get a
 578      pedwarn from the preprocessor, which has no context, so we can't
 579      suppress the warning with __extension__.
 580
 581      So instead what we do is construct the number in hex (because
 582      it's easy to get the exact correct value), parse it as a real,
 583      then print it back out as decimal.  */
 584
 585   real_from_string (&real, hex_str);
 586   real_to_decimal (dec_str, &real, sizeof (dec_str), digits, 0);
 587
 588   sprintf (buf, "%s=%s%s", macro, dec_str, fp_suffix);
 589   cpp_define (parse_in, buf);
 590 }
 591
 592 /* Define MAX for TYPE based on the precision of the type.  IS_LONG is
 593    1 for type "long" and 2 for "long long".  We have to handle
 594    unsigned types, since wchar_t might be unsigned.  */
 595
 596 static void
 597 builtin_define_type_max (const char *macro, tree type, int is_long)
 598 {
 599   static const char *const values[]
 600     = { "127", "255",
 601         "32767", "65535",
 602         "2147483647", "4294967295",
 603         "9223372036854775807", "18446744073709551615",
 604         "170141183460469231731687303715884105727",
 605         "340282366920938463463374607431768211455" };
 606   static const char *const suffixes[] = { "", "U", "L", "UL", "LL", "ULL" };
 607
 608   const char *value, *suffix;
 609   char *buf;
 610   size_t idx;
 611
 612   /* Pre-rendering the values mean we don't have to futz with printing a
 613      multi-word decimal value.  There are also a very limited number of
 614      precisions that we support, so it's really a waste of time.  */
 615   switch (TYPE_PRECISION (type))
 616     {
 617     case 8:     idx = 0; break;
 618     case 16:    idx = 2; break;
 619     case 32:    idx = 4; break;
 620     case 64:    idx = 6; break;
 621     case 128:   idx = 8; break;
 622     default:    gcc_unreachable ();
 623     }
 624
 625   value = values[idx + TYPE_UNSIGNED (type)];
 626   suffix = suffixes[is_long * 2 + TYPE_UNSIGNED (type)];
 627
 628   buf = alloca (strlen (macro) + 1 + strlen (value) + strlen (suffix) + 1);
 629   sprintf (buf, "%s=%s%s", macro, value, suffix);
 630
 631   cpp_define (parse_in, buf);
 632 }