gcc/c-cppbuiltin.c

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