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